ENG (ENDOGLIN), ACVRL1 (ALK1), and SMAD4 (SMAD4) genes, account for most of HHT cases. 10–20% of HHT patients develop brain AVMs (bAVMs), which can lead to vessel wall rupture and intracranial hemorrhages. Though the main mutations are known, mechanisms leading to AVM formation are unclear, partially due to lack of animal models. Recent mouse models allowed significant advances in our understanding of AVMs. Endothelial-specific deletion of either Acvrl1, Eng or Smad4 is sufficient to induce AVMs, identifying endothelial cells (ECs) as primary targets of BMP signaling to promote vascular integrity. Loss of ALK1/ENG/SMAD4 signaling is associated with NOTCH signaling defects and abnormal arteriovenous EC differentiation. Moreover, cumulative evidence suggests that AVMs originate from venous ECs with defective flow-migration coupling and excessive proliferation. Mutant ECs show an increase of PI3K/AKT signaling and inhibitors of this signaling pathway rescue AVMs in HHT mouse models, revealing new therapeutic avenues. In this review, we will summarize recent advances and current knowledge of mechanisms controlling the pathogenesis of bAVMs, and discuss unresolved questions.Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by vessel dilatation, such as telangiectasia in skin and mucosa and arteriovenous malformations (AVM) in internal organs such as the gastrointestinal tract, lungs, and brain. AVMs are fragile and tortuous vascular anomalies that directly connect arteries and veins, bypassing healthy capillaries. Mutations in transforming growth factor β (TGFβ) signaling pathway components, such as  Hereditary hemorrhagic telangiectasia (HHT), or Rendu-Osler disease, is an autosomal-dominant inherited syndrome with a prevalence of around 1:5,000–8,000 people , charactID1) and ID3  are responsible for HHT1 (ACVRL1 (encoding for ALK1) leads to HHT2 -HHT -HHT . Finallyectively , while Hectively . It shouectively .This review will focus on HHT bAVMs and summarize recent advances in organotypic pathogenicity, animal models, cellular and molecular mechanisms, and therapeutics.The blood supply of the human brain relies on only two pairs of large arteries: the internal carotids, which supply the blood to the cerebrum, and the vertebral arteries, which join distally to form the basilar artery, and finally vascularize the cerebellum and the brain stem. Proximally, the basilar artery and the internal carotid arteries join to form a ring at the brain’s base known as the circle of Willis.The circle of Willis gives rise to three pairs of main arteries: the anterior, middle, and posterior cerebral arteries, which divide progressively into smaller arteries and pial arterioles within the brain’s subarachnoid space meninges. Then, penetrating arterioles dive into the cortex and divide into precapillary arterioles and capillaries, the most predominant brain vessels. Similarly, the pial venular network from the brain surface is connected to ascending venules diving into the parenchyma, followed by postcapillary venules, which branch to capillaries.Even if human brain vascularization is well described, its development is based on studies done in animal models, such as rodents. Comprehensive studies on the mouse brain showed that vascularization starts at embryonic day (E) 7.5–8.5 by vasculogenesis at the ventral region of the neural tube, followed by the invasion of capillary sprouts into the neuroepithelium at E9.5 . BranchiThe ECs lining vessels have developed a unique and highly selective BBB to maintain brain homeostasis and neural function . This orA healthy blood vascular network has capillary plexuses between arteries, a high flow region, and veins, a low flow region. Capillaries are essential for the delivery of oxygen and nutrients. Therefore, neurovascular coupling, the blood flow regulation by neurons, is essential for neuronal function . The maiThere are different types of bAVMs defined by specific features : arterioEven if the different AVMs have different characteristics, no differences in the localization in the brain have been reported . AVMs arMost bAVMs are asymptomatic, and the diagnosis is often made by brain imaging after hospitalization or examination for another medical reason. However, some patients may develop symptoms such as headaches, seizures, and hemorrhages . In addiThe risks of hemorrhage may be increased by the position of the AVM in the brain, with a deep location having a higher risk of rupture . HoweverHowever, mechanisms that lead to the development of those symptoms are not yet well understood, mainly because only a few patients develop cerebral symptoms, the distribution of these symptoms are heterogeneous among patients, and the lack of experimental models.It is crucial to develop animal models that recapitulate HHT pathophysiology to improve our knowledge of AVMs’ pathogenesis and reveal new therapeutic avenues. Several studies have used new sophisticated models to decipher AVM mechanisms in the last two decades, as summarized below .Eng were first developed in order to recapitulate HHT1 . The retina is a part of the central nervous system and is a well-established model for studying angiogenic processes such as endothelial sprouting, arterio-venous specification, and vascular remodeling . In miceogenesis .Eng, Acvrl1 and Smad4 are appropriate models to study pathology. In the retina, in addition to the formation of AVMs, mutants show an increase in EC sprouting, proliferation, and vessel dilatation. Mural cells are also affected with a decrease in pericyte coverage on the one hand and arterialization of the veins on the other with the recruitment of vascular smooth muscle cells (vSMC). However, despite some degree of similarity in the vascular phenotype, these mutant mice also present distinct phenotypes. For example, 60% of Acvrl1 mutants develop AVMs in the retina , within the physiological range, triggers a number of flow responses in EC, including PI3K/AKT signaling pathway activation, alignment in the direction of flow , migratiEng in development and disease, whereas its expression is attenuated in adult quiescent endothelium  and APELIN receptor (AplnR). Blood flow was shown to promote the association of ALK1 and ENG at the EC membrane, thereby enhancing BMP signaling and vascular quiescence  . Integri in AVMs . They alvia the VEGFR2-integrins complex and the activation of downstream signaling pathways, such as PI3K/AKT and YAP/TAZ.All these studies demonstrate that BMP9/ALK1 signaling is essential to control LSS-induced EC quiescence and polarity Smad4 deletion induces retinal AVMs and hypersprouting, as observed in the Acvrl1 and Eng mutant mice  and increases the expression of the proto-oncogene c-MYC  SMAD1 and SMAD5 has also been shown to result in the formation of AVMs. Benn and colleagues reported that endothelial-specific simultaneous deletion of ood flow . The forher flow . AltogetSmad4 deletion in brain ECs increased EC proliferation, leading to cerebral hemorrhages (Dll4) and Recombination Signal Binding Protein For Immunoglobulin Kappa J Region (Rbpj), exhibit bAVMs  pathway, can rescue SMAD1/5/8 signaling and AVMs by activating ALK2 in BMP9/10 immunodepleted mice .Despite the specificities of distinct HHT types, the different mouse models suggest that there is one common mechanism that controls AVM formation. The loss of the BMP/ALK1/SMAD4 signaling pathway in venous ECs leads to an abnormal response to blood flow, including the increase of PI3K/AKT signaling activation and EC proliferation and inhibition of LSS-induced EC polarity and migration against the flow. Then, mutant ECs accumulate in abnormal capillaries, which get enlarged, experience higher blood flow, and acquire venous markers. Whereas arterial ECs might be dispensable, the decrease of NOTCH signaling and arterial marker expression are associated with AVMs. Ultimately, the loss of capillary bed and distinct EC phenotypes forms fragile AVMs . Furtherin vitro and animal models , which triggers the downstream MAPK/ERK chain, including Rapidly Accelerated Fibrosarcoma (RAF) and Mitogen-activated protein kinase kinase (MEK). Finally, the activated ERK will translocate into the nucleus to regulate the expression of genes involved in cell proliferation .Somatic mutations in the MAPK pathway lead to AVMs formation, such as activating mutations of KRAS, BRAF, or MAPK1/2. Moreover, loss-of-function mutations of RASA1, a negative regulator of RAS signaling, are associated with capillary-malformation arteriovenous malformation (CM-AVM1) and bAVMs in humans . These ARasa1 loss of function mice exhibit vascular and lymphatic defects, they did not feature bAVMs  (which varies from 0.9 to 34.3%), the treatment of unruptured bAVMs has become controversial, as untreated patients’ fate may be less morbid than those treated with invasive therapies. Thus, the demand for pharmacologic treatment options is high .Because of the enhanced angiogenesis associated with bAVMs formation, the most common pharmacologic target is VEGF. The anti-VEGF drug bevacizumab is currently undergoing phase III clinical trial for HHT (NCT 03227263) after showing promising effects on other HHT symptoms such as epistaxis and gastrointestinal bleedings in phase II clinical trials and case reports , withoutElucidation of the signaling events associated with HHT has confirmed the contribution of inadequate BMP9/ALK1/SMAD signaling in the formation of bAVMs, and as such, some research was done using tacrolimus, an anti-inflammatory FDA-approved drug, to evaluate whether it could potentiate the activity of the impaired BMP9/ALK1/SMAD pathway present in HHT patients resulting from haploinsufficiency. Indeed, a preclinical study demonstrated that tacrolimus could reduce the development of retinal AVMs in BMP9/10 immunodepleted mice, and it is currently undergoing a clinical trial to evaluate its ability to reduce epistaxis (NCT 03152019) .A better understanding of the signaling pathways inducing bAVMs opens up opportunities for pharmacological treatments using other drugs such as tyrosine kinase inhibitors. Some case reports already showed an improvement of epistaxis and telangiectasia in mostly HHT1 and two patients with different tyrosine kinase inhibitors  targetinOther potential treatments are based on inhibiting the PI3K/AKT/mTOR pathway, which is highly activated downstream of ANGPT2 and VEGF signaling. The most common mTOR inhibitor is sirolimus (rapamycin), which was shown to prevent bleeding and anemia in preclinical mouse models of HHT by controlling VEGFR2 and mTOR overactivation . One casAltogether, although preclinical and clinical tests on pharmacological treatments are ongoing, the probability of reversing the bAVMs is still weak. Despite advances in research to identify the mechanisms, surgical treatments are still the best option to treat bAVMs. Thus, improving surgical conditions and tools currently remains the optimal avenue to improve the survival of HHT patients .Identifying the molecular mechanisms associated with bAVM formation is an essential step toward elucidating the mechanisms of these malformations. Several additional questions, however, remain to be addressed. Are there modifying genes that may explain the clinical variability of bAVMs? How does inadequate ALK1/ENG signaling affect the response of ECs to mechanical stress, and how does this contribute to bAVM formation? Is PI3K/AKT signaling increased in HHT bAVMs, and could it be targeted to improve the malformations? What is the contribution of NOTCH signaling in the formation of bAVMs in HHT patients? In addition to these questions, one significant challenge remains to characterize and understand the common mechanisms underlying idiopathic bAVMs and those observed in HHT patients. The recent identification of several signaling pathways involved in bAVMs formation, as well as the analysis of several experimental animal models, have provided several clues to this goal and could pave the way for developing novel therapies.ED, TA, BL, and AD wrote the manuscript, collected literature information, and edited the manuscript. All authors reviewed and commented on the manuscript.


Hyperuricemia (HUA) is a kind of metabolic disease with high incidence that still needs new countermeasures. Apigenin has uric-lowering and kidney-protective activities, but how apigenin attenuates HUA and renal injury remains largely unexploited. To this end, an acute HUA mouse model was established by intraperitoneal injection of potassium oxazinate and oral administration with hypoxanthine for 7 consecutive days. Apigenin intervention decreased serum uric acid (UA), creatinine (CRE), blood urea nitrogen (BUN), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor (TNF-α), interleukin-18 (IL-18), liver xanthine oxidase (XOD), and urine protein levels, and increased serum interleukin-10 (IL-10) and urine UA and CRE levels in HUA mice. Moreover, administration of apigenin to HUA mice prevented renal injury, decreased renal glucose transporter 9 (GLUT9) and urate anion transporter 1 (URAT1) levels, and increased renal organic anion transporter 1 (OAT1). These alterations were associated with an inhibition of IL-6, phospho-janus kinase 2 (P-JAK2), phospho-signal transducer, and activator of transcription 3 (P-STAT3), and suppression of cytokine signaling 3 (SOCS3) expression in the kidneys. Additionally, the molecular docking results showed that apigenin had strong binding capacity with UA transporters and JAK2 proteins. In summary, apigenin could improve UA metabolism and attenuate renal injury through inhibiting UA production, promoting excretion, and suppressing the JAK2/STAT3 signaling pathway in HUA mice. The results suggest that apigenin may be a suitable drug candidate for management of HUA and its associated renal injury. Hyperuricemia (HUA) is characterized by sustained high levels of serum uric acid (UA), which is caused by overproduction or underexcretion of UA or both in the body ,2,3. It Serum UA levels are mainly determined by: (1) liver xanthine oxidase (XOD), which is a rate-limiting enzyme that converts hypoxanthine to xanthine and then xanthine to UA ; (2) renApigenin , a natural flavonoid, is mainly derived from Apium graveolens L.(celery) and it is also found in a variety of plants, fruits, and vegetables . The accp < 0.01). As expected, treatment with apigenin  markedly decreased serum levels of UA and BUN in HUA mice in comparison with the vehicle-treated ones (p < 0.01). However, only a high dose of apigenin (100 mg/kg) could decrease serum CRE levels in HUA mice. In addition, serum UA levels were markedly decreased in allopurinol (Allop)-treated HUA mice in comparison with the vehicle-treated ones (p < 0.01), but this treatment did not affect serum BUN and CRE levels.As shown in p < 0.05 or 0.01). However, Allop intervention only significantly increased urine CRE levels on day 6 in HUA mice (p < 0.05). These results suggest that apigenin not only has dual actions on UA metabolism, but also could alleviate HUA-induced renal injury.As shown in p < 0.01). Administration with apigenin could prevent an increase in the KW/BW in HUA mice compared to the vehicle-treated ones (p < 0.05 or 0.01). In addition, as shown in p < 0.01). Furthermore, as shown in p < 0.01). As expected, treatment with apigenin or Allop significantly reversed these alterations in HUA mice (p < 0.05 or 0.01). These results suggested that apigenin could alleviate renal injury in HUA mice.As shown in As shown in p < 0.01). Notably, administration with apigenin  and Allop to HUA mice significantly reduced serum levels of IL-6, TNF-α, and IL-18 in comparison with those of the vehicle-treated ones (p < 0.01). However, as shown in p < 0.05 or 0.01). In addition, as shown in p < 0.01). Notably, 100 mg/kg of apigenin significantly prevented a decrease in serum IL-10 levels in HUA mice (p < 0.05).Accumulating evidence suggests that acute HUA may cause inflammation response, which further upregulates serum UA levels and subsequently causes kidney dysfunction ,39,40. Ap < 0.05 or 0.01). Based on the above-mentioned results, the high dose of apigenin (100 mg/kg) was better than the low and medium doses of apigenin in preventing the alterations in HUA mice. Therefore, the mice in the high dose of apigenin-treated group were used to the following experiments.Next, we examined the effect of apigenin on the protein expressions involved in UA generation and excretion in HUA mouse. As shown in p < 0.05). As expected, apigenin (100 mg/kg) markedly reversed the expression levels of GLUT9, URAT1, and OAT1 in the kidneys of HUA mice (p < 0.05). These results suggested that apigenin may have the ability of promoting UA excretion in the kidney.Moreover, as shown in In order to examine the binding ability of apigenin with UA transporters and JAK2 protein, the SYBYL-X 2.0 software was used to conduct molecular docking analysis. As shown in There were two binding sites between apigenin with GLUT9 (the active site residues were LYS431 and GLY58) and URAT1 (the active site residues were LYS393 and HIS245) proteins, respectively. Though the total score  was not that high, their C-score was 5 points, and they had relatively low absolute Grash scores  and Polar scores , indicating that apigenin has a strong binding capacity with the two proteins.There were 3 binding sites  between apigenin and OAT1 protein, and the total score was over 6 points, while the C-score was 3 points. Additionally, the smaller Polar score value (2.61 points) and the absolute value of Grash score (−0.65 points) indicate that the molecule was closer to the active center of the target OAT1 protein and had the higher energy generated by collision. Therefore, apigenin has a strong binding capacity with OAT1 protein.In addition, as shown in p < 0.01). By contrast, supplement of 100 mg/kg of apigenin to HUA mice significantly down-regulated the expression levels of IL-6, P-JAK2, and P-STAT3 compared to those of the vehicle-treated ones (p < 0.05 or 0.01). Moreover, the results from the western blots corroborated the findings from the IHC staining.As shown in p < 0.05). These results suggested that apigenin may inhibit JAK2/STAT3 signaling pathway in the kidney of HUA mouse.The activation of JAK2/STAT3 may facilitate SOCS3 expression, which potentiates the inflammatory response in the kidney ,45. TherThe globally increasing prevalence of HUA and its associated nephropathy are in high demand of new countermeasures . Here, wIn the current study, apigenin was demonstrated to decrease serum UA, CRE, and BUN levels, and increase urine UA and CRE levels in PO- and Hypox-induced acute HUA mouse. In support of the current findings, apigenin was reported to reduce serum levels of UA, CRE, and BUN in PO- and adenine-induced hyperuricemic nephropathy KM mice , and decThe sustained high serum UA levels may cause renal endothelial cell inflammation, and an enhanced secretion of pro-inflammatory molecules such as IL-6, TNF-α, and IL-1β and a diminished production of anti-inflammatory molecules, such as IL-10 , as wellWe have for the first time to report that apigenin intervention could decrease SOSC3 expression in the kidney of HUA mouse. The accumulating evidence suggest that SOSC3 is a downstream regulator of JAK2/STAT3 signaling pathway ,52, whicIn the present study, we demonstrated that apigenin does not affect liver functions in acute HUA mice. However, Singh et al. reported that acute exposure of apigenin may cause liver dysfunction in mice . The incIn the present study, the urine levels of UA were determined on days 0, 2, and 6 during modeling and drug administration, which may allow the efficacy of apigenin on the alterations of urine UA and CRE in mice to be better observed ,58,59,60The present results showed that the urine levels of UA and CRE were not consistent before and after the treatment in each group. These alterations may be attributed to the following two reasons: (1) The vehicle-treatment effect. During the experiments, mice in the NC group were intraperitoneally injected and/or gavaged with the corresponding control vehicles. These treatments may induce a certain type of psychological and/or physical stresses, which lead to the variations in the values of blood and urine parameters. Therefore, we have set the controls for each time point to eliminate possible errors between different batches. Indeed, several investigations have shown that blood UA levels may increase under acute stress ,62,63, wIn this study, Allop was demonstrated to decrease the levels of liver XOD and serum UA, and increase the levels of urine CRE (day 6) in this rapid HUA mouse model. However, Allop did not reverse the increased serum levels of CRE and BUN in HUA mice. By contrast, Chen et al.  reportedSome limitations of the present study may exist regarding interpretation of the data. Firstly, we did not evaluate the anti-inflammation effect of apigenin on renal tubular epithelial cells. However, apigenin has been demonstrated to inhibit the overproduction of TNFα, IL-1β, and IL-6 in D-glucose treated HK-2 cells . SecondlApigenin  was purchased from RuiFenSi Biotechnology Co., Ltd. . Allop (H31020334) was bought from Xinyi Mixane Pharmaceutical Co., Ltd. . PO (CAS:2207-75-2) and Hypox (CAS:68-94-0) were purchased from Macklin . Antibodies against JAK2 (Cat# 3023), STAT3 (Cat# 30835), and P-STAT3 (Cat# 9145) were obtained from Cell Signaling . Antibodies against URAT1 (Cat# 14937-1-AP), OAT1 (Cat# 26574-1-AP), GLUT9 (Cat# 26486-1-AP), IL-6 (Cat# 21865-1-AP), SOCS3 (Cat# 66797-1-Ig), β-actin (Cat# 66009-1-Ig), and GAPDH (Cat# 60004-1-Ig) were obtained from Proteintech Co., Ltd. . Antibodies against P-JAK2 (Cat# AP0531) were obtained from ABclonal company . The commercial kits for UA (Cat# C012-2-1), CRE (cat# C011-2-1), BUN (Cat# C013-2-1), urinary albumin (C035-2-1), ALT (Cat# C009-2-1), AST (Cat# C010-2-1), and XOD (Cat# A002-1-1) were purchased from Nanjing Jiancheng Bioengineering Institute . The ELISA kits for IL-6 (KT2163-A), IL-10 (KT2176-A), IL-18 (KT2169-A), IL-1β (KT2040-A), and TNF-α (KT2132-A) were purchased from Jiangsu KeTe Biotechnology Co., Ltd. .Male KM mice (20 ± 2 g) were purchased from Beijing SiBeiFu Animal Technology Co., Ltd.  and housed in a specific-pathogen-free (SPF) animal facility with constant temperature (21 ± 2 °C), humidity (55 ± 5%), and a 12-h light/dark cycle at the Beijing University of Chinese Medicine (BUCM). All mice were supplied with regular chow and drinking water ad libitum. All the animal procedures were approved by the BUCM Animal Care Committee, Beijing, China (Approve No. BUCM-4-2021042302-2016).After acclimatization for one week, the KM mice were randomly divided into six groups (10 mice per group): (1) NC group, (2) HC group, (3) Allop group, (4) low dose of apigenin-treated (APL) group, (5) medium dose of apigenin-treated (APM) group, (6) high dose of apigenin-treated (APH) group. In detail, mice in the last five groups were daily administered with PO  and Hypox  according to the previous publications ,58,68. SDuring the treatment, the urine of the mouse on days 0, 2, and 6 were collected for subsequent analysis. One hour after the last treatment, blood was collected from the anesthetized mouse to obtain the serum. The liver and kidney were quickly removed from the mouse and then stored either in −80 °C or in 4% paraformaldehyde solution.The levels of UA, CRE, BUN, albumin, ALT, and AST in serum or urine, and XOD in the liver were measured using commercial kits according to the manufacturer’s instructions. Serum levels of IL-6, IL-1β, IL-18, TNF-α, and IL-10 were detected using ELISA kits according to the corresponding protocols.The kidneys from the mice were fixed in 4% paraformaldehyde for 48 h and then embedded in paraffin. The H&E and Masson trichome staining was performed according to the routine procedure ,69. The The IHC staining of the kidney was conducted as previously described . BrieflyThe total proteins of the kidneys were extracted with a RIPA buffer and quantified by a BCA kit. The equal amounts of protein were loaded onto SDS-PAGE gels and subsequently transferred to the PVDF membrane. Then, the membrane was separately incubated with the appropriate primary antibody  overnight at 4 °C and subsequently incubated with the corresponding secondary antibodies for 1 h at room temperature. Immunopositive bands were visualized using high sensitivity ECL and images were captured by the Azure (C500) Bio-image system . The grey values of the bands were quantified using an Image J software (V1.8.0.112) and normalized with the corresponding β-actin  or GAPDH .https://pubchem.ncbi.nlm.nih.gov/, accessed on 10 May 2022). The crystal structures of the XOD , GLUT9 , URAT1 , OAT1 , and JAK2  were derived from the RCSB Protein Data Bank , National Center for Biotechnology Information  and UniProt . The Sybyl-x 2.0 software was used for molecular docking analysis of apigenin with UA transporters and JAK2 proteins.The 3D structure of apigenin molecule was retrieved from the PubChem  was employed. A Dunnett’s T3 test or nonparametric test was applied, respectively, when the date met a normal distribution, but the homogeneity of variances was not achieved, or did not meet a normal distribution. A value of In summary, the current study provides evidence that apigenin could attenuate UA levels and renal injury in HUA mice. The potential mechanism behind this action may be related to an inhibition of UA overproduction and a promotion of UA excretion as well as the regulation of JAK2/STAT3 signaling pathway. These results highlight the potential of apigenin in the management of HUA patients with renal injury. Further investigations of the actions of apigenin HUA will contribute to providing a suitable scaffold for developing multitargeted anti-HUA agents.


PrEP delivery programmes should consider prioritizing the long-acting injectable INSTI, cabotegravir, in HTLV-1 endemic settings.HIV pre-exposure prophylaxis (HIV-PrEP) is effective in reducing the likelihood of HIV acquisition in HIV-negative people at high risk of exposure. Guidelines recommend testing for sexually transmitted infections (STIs) before starting, and periodically on PrEP, including bacterial infections, HIV, hepatitis C virus, and, for those who are non-immune, hepatitis B virus. Diagnosed infections can be promptly treated to reduce onward transmission. HTLV-1 is not mentioned; however, it is predominantly sexually transmitted, causes adult T-cell leukaemia/lymphoma (ATL) or myelopathy in 10% of those infected, and is associated with an increased risk of death in those without any classically HTLV-associated condition. The 2021 WHO Technical Report on HTLV-1 called for the strengthening of global public health measures against its spread. In this scoping review, we, therefore, (1) discuss the epidemiological context of HIV-PrEP and HTLV-1 transmission; (2) present current knowledge of antiretrovirals in relation to HTLV-1 transmission prevention, including nucleos(t)ide reverse transcriptase inhibitors (NRTIs) and integrase strand transfer inhibitors (INSTIs); and (3) identify knowledge gaps where data are urgently required to inform global public health measures to protect HIV-PrEP users from HTLV-1 acquisition. We suggest that systematic seroprevalence studies among PrEP-using groups, including men who have sex with men (MSM), people who inject drugs (PWIDs), and female sex workers (FSWs), are needed. Further data are required to evaluate antiretroviral efficacy in preventing HTLV-1 transmission from  HIV pre-exposure prophylaxis (PrEP) reduces the likelihood of HIV acquisition and is recommended for high-risk groups. Indications include being HIV-negative and reporting anal or vaginal sex plus any of  HIV-posiGuidelines recommend STI testing before starting and, periodically on PrEP  given thIn 2021, the WHO HTLV-1 Technical Report called for the strengthening of public health measures against its spread . In thisThe current US Food and Drug Administration-approved HIV-PrEP antiretrovirals are an oral combination of nucleos(t)ide reverse transcriptase inhibitors (NRTI), emtricitabine (FTC) plus either tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide (TAF), taken daily or episodically around a potential exposure, or intramuscular, twice-monthly injections of the long-acting integrase strand transfer inhibitor (INSTI), cabotegravir. Randomized trials have shown the efficacy of TDF/FTC , 8 and TMen who have sex with men (MSM) are the major PrEP-user group in industrialized countries. In the UK, 96% of 24,255 users were cis-gender MSM . ApproxiThe MSM and others at risk of HIV acquisition in HTLV endemic countries are increasingly interested in, or already using, PrEP, including Brazil , Peru 1, JamaicaAmongst STI clinic attendees in Jamaica, multiple partners, condomless sex, and a history of STIs or anogenital ulcers were associated with increased HTLV risk . HSV-2 sThe HTLV-1 seroprevalence may be increased in MSM in endemic and non-endemic settings . In BarbIncreased HTLV-1 prevalence is reported amongst FSW in endemic settings. A systematic review in Latin America demonstrated greater prevalence than in blood donors or pregnant women, up to 21.8, 0.9, and 1.7%, respectively, in Peru , 73. A sA high HTLV seroprevalence has been reported in PWIDs. HTLV-1 and HTLV-2 seroprevalence amongst HIV-1 positive PWID in Sao Paulo was 15.3 and 11.1%, respectively . HTLV-2 The rising HTLV seroprevalence observed with increasing age in Japanese and Brazilian cohorts suggests that the major mode of transmission is sexual, with >80% of infections acquired in adulthood , 80. SemMale-to-female transmission is more efficient than vice versa, with a four times greater relative transmission rate . Sexual Reasons for increased efficiency of male-to-female transmission may include enhancing co-factors or greater lymphocyte content within a seminal fluid, inhibitory factors in cervical fluid, or the greater area of susceptible mucosa in the female genital tract. Most seroprevalence studies found that HTLV-1 seroprevalence increases after menopause, suggesting the mucosa becomes more susceptible after this event. Amongst MSM, the association of CRAI with transmission could be explained by the enhancing presence of seminal fluid, or a greater area of susceptible anorectal vs. penile mucosa.Zidovudine (AZT) reduced HTLV-1 proviral DNA production following co-culture of infected cell lines with lymphocytes when added at time zero of infection –94 but wIn an ATL model, where rabbits were inoculated intraperitoneally with an HTLV-1 transformed cell line, AZT at time zero prevented infection . In knocde novo T-cell infection, as such cells are critical for the survival of the malignant clone (The combination AZT/interferon (IFN)-alpha improves survival and is the first-line treatment for certain ATL types , 101 altnt clone .in vitro, although with reduced potency vs. AZT (Lamivudine (3TC) protected lymphocytes from HTLV-1 infection  vs. AZT , in one  vs. AZT . However vs. AZT .Others reported that lamivudine did not block infection  and highLamivudine therapy in five people with HAM initially reduced the HTLV-1 proviral DNA load by 10-fold, with the nadir reached over a variable period of 1–6 months. However, the effect was not sustained .AZT-3TC therapy vs. placebo over 48 weeks in 16 patients with HAM had no effect on PVL or clinical response  with lacInhibition of HTLV-1 cell-to-cell transmission by tenofovir was twenty times more potent in one study than AZT . Others in vivo activity of tenofovir. In a knock-out mouse model, TDF at time zero of inoculation prevented infection, with no effect if administered 1 week later  for the first 6 months followed by a rebound, with no impact on the asymptomatic infection (n = 3) (n = 16) receiving 6 months of raltegravir, PVL in PBMC and/or cerebrospinal fluid (CSF) declined in some individuals but with no impact on the overall cohort. Spontaneous lymphoproliferation, a measure of ex vivo T-cell activation, was significantly reduced overall. Clinical measurements remained stable  . Geneticd stable .in vitro (The non-nucleoside reverse transcriptase inhibitor (NNRTI), dapivirine intravaginal ring, has been approved by the European Medicines Agency for use as HIV-PrEP in high prevalence settings , 118. Hoin vitro , 119. Thin vitro , 121.ex vivo, probably due to the anti-nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB) activity rather than HTLV-1 protease inhibition  co-receptor antagonist, maraviroc; fusion inhibitor, enfuvirtide; attachment inhibitor, fostemsavir; or the post-attachment inhibitor, ibalizumab-uiyk. However, a lack of anti-HIV-2 activity of enfuvirtide and fostemsavir suggests inactivity against HTLV-1. A lack of use of a cluster of differentiation 4 (CD4) receptors or CCR5 co-receptors for HTLV-1 attachment predicts the inactivity of ibalizumab and maraviroc, respectively.in vitro studies reflecting (1) different assays, particularly comparing cell-to-cell transmission vs. enzyme inhibition, (2) cell-type-dependent drug uptake and intracellular phosphorylation, (3) RT sequence variation, and (4) intracellular RT activity, which may vary with the cellular environment. In vivo, most studies have yielded disappointing results for NRTI in established HTLV-1 infection .It has been speculated that following exposure, HTLV-1 proliferation is first through viral replication and infectious transmission, and then predominantly although not exclusively by the mitotic expansion of infected clones . HoweverIn iatrogenically immunosuppressed patients infected with HTLV-1 through organ transplantation, any initial phase of infectious spread lasted no more than a few weeks . For thrElsewhere, AZT/3TC/raltegravir was initiated 24 h post-renal transplantation from an infected donor for 1 month. At PEP cessation, both PVL and HTLV antibodies were undetected. Two months later, high-level PVL and HTLV-1 antibodies were detected, followed by HAM. Antivirals were re-initiated but HAM rapidly progressed . The autConsensus, opinion-based guidelines recommend 6 weeks of AZT/raltegravir PEP initiated within 48 h of transplantation from an HTLV-1 seropositive donor; or as pre-emptive therapy, where the donor's HTLV-1 seropositivity is detected >48 h post-transplant and the recipient's PVL is undetected . Some clvia breastfeeding, intrauterine and perinatal infection is also reported. Transmission rates are 7-32% for long term (>6 months) breastfeeding vs. 2.5–5.7% for exclusive formula-feeding (Although most mother-to-child HTLV-1 transmission (MTCT) occurs -feeding . There a-feeding .Although occupational exposure, such as in healthcare workers, is a recognized transmission route for HTLV-1 and HTLV-2 , 134, daThere are no data on antiviral PEP after sexual exposure to HTLV-1.HIV-PrEP roll-out has critical implications for HTLV transmission. First, sexually transmitted HTLV outbreaks could occur, as described for HCV . Data arSecond, PrEP programmes should evaluate antiretroviral efficacy in preventing HTLV-1 transmission. Unlike HIV, antiviral therapy to treat established HTLV is lacking, placing greater emphasis on transmission prevention. Observational cohort studies should measure HTLV-1 incidence in PrEP-users and matched non-PrEP user controls. Cohorts should include MSM and PWID, as most HTLV incidence data are from heterosexual couple studies.in vitro and in animal models, including in combination with NRTI. Antiretrovirals under development and clinical trials should also be evaluated, particularly, long-acting agents such as the HIV-1 capsid inhibitor, lenacapavir. Data could also be obtained from HBV MTCT prevention studies of TDF, where individuals are HTLV-1-coinfected and compared to non-TDF-receiving controls; however, such studies might only assess the effect of transplacental TDF to prevent intrapartum transmission. In the interim, PrEP programmes should prioritize injectable cabotegravir for roll-out in HTLV-1 endemic settings, both for its predicted greater efficacy in blocking HTLV-1 transmission, and superior efficacy in preventing HIV-1 transmission vs. oral NRTI PrEP.Third, further data on antiretroviral activity against HTLV-1 transmission are required. This should include cabotegravir Finally, country-specific data are required to understand HTLV-1 awareness amongst PrEP users, clinicians, and community groups, including risk factors, clinical consequences, treatments for HTLV-related conditions, and measures to prevent onward transmission. Findings should encourage campaigns to improve HTLV-1 knowledge and clinical care.DB and GT devised the manuscript. DB wrote the first draft and GT revised it. Both authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


ESCs can be obtained from the inner cell mass of the blastocysts and give rise to all the embryonic three germ layers, however, the critical ethical predicament limits ESCs clinical applications. iPSCs possess the same differentiation capacity as ESCs but avoid ESCs usage-associated ethical dilemmas. Therefore, the generation of iPSCs Stem cells inhabit specialized microenvironments called “stem cell niches” that maintain a hypoxic and low level of reactive oxygen species (ROS) environment. The stem cell niche is essential for preserving stem cell stemness and self-renewal potency. ROS has been considered for a long time to be implicated in stress and various disorders and has been redefined as a vital signaling molecule with multifaceted functions in modulating stem cell biology and differentiation .2O2) and the superoxide anion radical (O2.-), are produced primarily by NADPH oxidases and controlled by growth hormones, cytokines, cytokines, mitochondrial electron transport chain. There are more than 40 enzymes involved in this process. H2O2 is implicated in a vast majority of redox-associated modulation of biological activities  reactions and form oxidative alteration on biological macromolecules, and ultimately activate key redox signaling and its related biological functions. Two key ROS signaling molecules hydrogen peroxide /protein kinase B (Akt) pathway. This finding is the main attribute in cyclic mechanical stress-mediated PDLSCs’ osteogenic differentiation.The cyclic mechanical stress was found to boost the ROS level and induce the expression of nuclear factor erythroid-2-related factor-2 (Nrf2) and its downstream molecules including heme oxygenase 1 (HO1) and NADPH dehydrogenase quinone 1 (NQO1), which ultimately promoted the osteogenic differentiation in human periodontal ligament stem cells (PDLSCs) . In thisSinenko et al. covers the recent advances in the physiological functions of the intracellular ROS as a signaling molecule and a secondary messenger of a wide range of cellular signaling in modulating the potency and differentiation of stem cells as well as the development of invertebrate Drosophila.A well-written review paper from Sheng et al. showed that a novel natural antioxidant compound, Caffeic acid (CA) efficiently delayed the aging events in the Drosophila gut, which is associated with the aberrant function of intestinal stem cells (ISCs) and the subsequent dysplasia. This beneficial antioxidant effect is attributed to the potency of CA to suppress oxidative stress-induced JNK signaling.A study by Drosophila as a proper genetic model for studying the mitochondrial electron transport chain and mitochondrial ROS-associated biological functions and the necessity of translating various pathophysiological aspects in Drosophila that are enigmatic in humans. While editing this Research Topicr, we hoped that the contributed research work would serve as an inspiration for scientists in the field to investigate further mechanisms and applications of ROS signaling in flies that could be translational for promoting ROS-mediated enhanced stem cell function and clinical applications.These studies underscored the importance of Wang et al. demonstrated the beneficial effects of the bone marrow mesenchymal stem cell-derived exosomes on the pathogenesis of osteoarthritis through targeting the competitive endogenous RNA (ceRNA) networks represented in LYRM4-AS1/GRPR/miR-6515-5p signaling pathway.Moreover,


Neuropathic pain is a debilitating chronic disorder, significantly causing personal and social burdens, in which activated neuroinflammation is one major contributor. Thymic stromal lymphopoietin (TSLP) and interleukin (IL)-33 is important for chronic inflammation. Linalyl acetate (LA) is main component of lavender oil with an anti-inflammatory property through TSLP signaling. The aim of the study is to investigate how LA regulates mechanical hyperalgesia after sciatic nerve injury (SNI). Adult Sprague-Dawley male rats were separated into 3 groups: control group, SNI group and SNI with LA group. LA was administrated intraperitoneally one day before SNI. Pain behavior test was evaluated through calibration forceps testing. Ipsilateral sciatic nerves (SNs), dorsal root ganglions (DRGs) and spinal cord were collected for immunofluorescence staining and Western blotting analyses. SNI rats were more sensitive to hyperalgesia response to mechanical stimulus since operation, which was accompanied by spinal cord glial cells reactions and DRG neuro-glial interaction. LA could relieve the pain sensation, proinflammatory cytokines and decrease the expression of TSLP/TSLPR complex. Also, LA could reduce inflammation through reducing IL-33 signaling. This study is the first to indicate that LA can modulate pain through TSLP/TSLPR and IL-33 signaling after nerve injury. Chronic neuropathic pain triggered by peripheral nerve injury creates both personal and social huge burdens, with a varied prevalence from 11 to 30% in worldwide population . SciaticActivated immune system and inflammation are major contributors to neuropathic pain. An imbaLavender, a worldwide aromatic shrub, whose oil can relieve inflammation reaction in chronic disease. LinalylIn our recent study, we found that differential TSLP expression in DRG neurons in the same CCI rat. LA attenuated expression of TSLP in nociceptive DRG neurons, and apoptotic DRG neurons at the injured side, not the uninjured side. CentralAll procedure of the experiment involving rats were approved by the Institutional Animal Care and Use Committee (IACUC) at Kaohsiung Medical University. Adult Sprague–Dawley male rats (300–350 g) in this study  were anesthetized with intraperitoneal administration of Zolitil50  and euthanized using standard IACUC procedures.These rats were randomly separately into three different groups: control group, SNI group and SNI with LA group. The SNI rats were generated as previous described on the right SN . The nerThe calibrated forceps  displayed the force at which the rats react to the mechanical nociception threshold. To measure the threshold, rats were loosely restrained and placed on a bench with their head and body covered by a towel. Their hind-paws were put between the forceps and the force was applied gradually increase with a constant rate until response. The forces indicated that the grams (g) of force illustrated on the dynamometer at the time of hind-paw withdrawal. These measurements were repeated 5 times every 5 s. Only three values were averaged to calculate the mechanical threshold excluding the maximum and minimum values.For immunofluorescence (IF) staining and western blotting assay, these rats were sacrificed by intracardial perfusion with phosphate-buffered saline (PBS) with/ without post-fixed with 4% paraformaldehyde, respectively. 8 μm thickness tissue sections of the right lumbar 4th /5th dorsal root ganglion (DRG) and spinal dorsal horn were dried and incubated with blocking buffer at room temperature (RT). Also, lysis buffer was added to homogenize DRGs and SNs samples which further were incubated at RT.Sections of DRGs, spinal cords  and SNs (injured area) were washed for times with PBS, then incubated with the primary antibodies . After washing for several times, these sections were further incubated with secondary antibodies [the Alexa Fluor 488-conjugated AffiniPure Goat Anti-Rabbit IgG (H + L)  and the Alexa Fluor 594-conjugated AffiniPure Goat Anti-Mouse IgG (H + L) ] with DAPI nuclear counterstaining. At last, these sections were visualized and photographed under a fluorescence microscopy . The intensity was calculated by Image J software.Protein expression of DRGs and SNs were measured through Western blotting. A total of 25 mg protein per DRG sample and 35 mg protein per SN sample were separated by 8–15% SDS-PAGE and then transferred to PVDF membranes. After blocking with 5% non-fat milk, the membranes were incubated with the following primary antibodies . Next, the membranes were washed for several times and probed with the Peroxidase-conjugated AffiniPure Goat Anti-Rabbit IgG (H + L)  and the Peroxidase-conjugated AffiniPure Goat Anti-Mouse IgG (H + L) . At last, the bands were measured through the MiniChemi™ chemiluminescent system .± SEM. All experiments were repeated for three times at least and one representative result was shown. Differences between groups were analyzed by one-way or two-way ANOVA using SPSS (V24.0) statistical software. These differences were regarded statistically significant with p value less than 0.05.These results were presented as mean At first, the SNI rat models were generated. In the calibrated forceps testing, the ipsilateral paw withdrawal threshold (pain threshold) exhibited a significant decrease since the 3rd day after SNI and persisted to the 7th day, indicating the SNI rats presented the mechanical hyperalgesia Fig.  A. To exPrevious article revealed that LA can decrease inflammatory response though influencing TSLP pathway, 20. TraGlial cell reactions  and ionized calcium binding adaptor molecule-1 (IBA-1)) and neuro-glial interactions are major mechanisms underlying chronic pain , 27. To To further confirm that LA inhibited the inflammation response in SNI rats, we examined the cytokines by western analyses in DRGs on the 7th day after SNI (TSLP peak day). The expression of IL-33, and IL-6 in lumbar 4th /5th DRGs significantly increased nearly by 2-fold separately after SNI; however, the changes were decreased by administration of LA . Immunofluorescence staining for Neu-N (marker for neurons), GFAP  and IBA-1 (marker for macrophage) were performed. In the DRGs, TSLP was co-localized with Neu-N Fig.  A and GF+ macrophages accumulated after SNI, which improved by LA. Next, we examined the expression of TSLP and TSLPR in the ipsilateral SNs of SNI rats. The expression of TSLP and TSLPR significantly increased nearly by 2-fold after SNI and decreased by administration of LA (Fig. To investigate the activated macrophages in the ipsilateral SNs, we performed immunofluorescence testing to evaluate the expression of IBA-1 in ipsilateral SNs of SNI rats. Figure  LA Fig.  A-C. We  LA Fig.  A, D-F.Accumulating evidences indicate that abnormal production of inflammatory cytokines mediates neuroinflammation and sensitize neurons to induce hyperalgesia or allodynia in neuropathic pain or radiculopathy . In the The pathomechanism of pain or hyperalgesia remains multifactorial. Glial cell reactions contribute to pain response after nerve injury. RetrogrNeuro-glial interaction in DRG is another emerging underlying cause to pathological pain. Glial cCentral and peripheral sensitization develop following inflammatory processes. PeripheAlthough our study provides some novel insights into the mechanism of linalyl acetate on mechanical hyperalgesia, some potential limitations to our study exists here. DRG consists of not only neurons but non-neuronal cells. DRG neurons have diverse molecular or functional properties and the Our data demonstrated a novel finding that LA attenuated SNI in rats through mediating the expression of TSLP/TSLPR and IL-33 in DRGs and SNs. By regulating TSLP/TSLPR, LA decreased the inflammatory cytokines and IL-33, which were associated with mechanical hyperalgesia, spinal cord glial cell reactions and neuronal-glial interactions in DRGs. This study is the first to show the potential role of LA in regulating neuropathic pain through TSLP/TSLPR and IL-33 signaling.


Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology. Glaucoma is the leading cause of irreversible blindness worldwide, with global prevalence of the disease estimated to surpass 100 million cases by 2040 . The disGlaucoma shares comorbidities with a number of systemic vascular diseases, including diastolic hypotension, diabetes, ischemic cardiac disease, peripheral vasospasm, and arterial hypertension ,8. AdvanThe visual system has developed intricate regulatory mechanisms to fulfill the high metabolic demand of the retina. One such mechanism is neurovascular coupling (NVC), whereby an increased neuronal activity promotes signaling between cells of the neurovascular unit (NVU), resulting in increased supply of metabolites and removal of waste products by the vasculature . The retVascular autoregulation and NVC mechanisms are severely compromised in glaucoma patients . DysfuncThe nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling pathway is integral to NVC mechanisms and is the prime mediator of vasodilation in endothelial cells . NO is pGUCY1A3/GUCY1B3 gene locus was significantly associated with paracentral visual field loss in female glaucoma patients . Mo. Mo34]. 2+-mediated contractility and NO-mediated relaxation [2+ influx, causing vasoconstriction [The vascular cells of the NVU also include pericytes; however, exploration of their role within the retinal NVU in glaucoma pathology is in its infancy compared to other cells of the retinal vasculature . Pericytlaxation . Recentllaxation . The idelaxation . Damage triction . Similartriction ,49,52,53triction . Since atriction . It is ttriction .2+ levels, and decreases whisker-pad stimulation-induced vasodilator responses in capillaries [2+ influx, which causes pericyte contraction, can be inhibited via 8-Br-cGMP (a cGMP agonist), as well as SNP (a NO donor) [2+ is related to changes in pericyte contractility and may impact retinal microvascular function. Across the vascular cells of the NVU, breakdown of NO-cGMP signaling may contribute to dysfunction in endothelial and smooth muscle-cell mediated vasodilation, endothelial monolayer permeability, and pericyte vasoactivity, all of which are pertinent to the vascular component of glaucomatous damage  and the vascular-associated glaucomatous pathology observed in patients. In liver pericytes, exogenous NO supplementation and inhibition of cGMP breakdown via PDE inhibitor sildenafil citrate diminished the extent of endothelial dysfunction caused by contraction of active pericytes . Moreoveillaries . This isillaries , and thaillaries . In retiO donor) . It is ts damage . HoweverThe retinal glia, including astrocytes, Müller glia, and microglia, were thought to be relatively passive elements in the CNS; however, recently, it has become clear that they play a critical intermediary role between the neurons and vascular cells of the NVU ,61,62. TIn glaucoma, glial dysfunction and/or activation may contribute to breakdown in NVC, rendering RGCs more susceptible to degeneration. Given their localization in the RGC layer and role in metabolic support, changes in astrocyte physiology may have a large impact on the health and physiology of RGCs. During pathological conditions in the retina, astrocytes respond robustly with gross morphological and physiological changes, which may prompt the dysfunction and degeneration of RGC axons ,67,74,75Examining the role of NO-cGMP signaling in the NVU may help to elucidate the relationship between glia, vascular function, and glaucoma pathology. In the CNS, decreased GC1 expression is detected in the reactive glia of post-mortem patients with neurodegenerative diseases such Alzheimer’s disease and multiple sclerosis ,85,86. I−/−GC1 mice that developed RGC degeneration with age [−/−GC1 mice [−/−GC1 mice exhibit a greater decrease in connexin-43 levels with age [To date, the role of NO-cGMP signaling in astrocyte function has been explored in many contexts, both within the CNS and systemically, and has been summarized in with age ,28 were with age ,29. Intewith age ,99. Morewith age . Connexiwith age . cGMP/PKwith age . Given tGC1−/− mice exhibit Cx43 phosphorylation in the intercalated disc of cardiac tissue, resulting in dysfunctional gap junction electrical conductivity [In cell types outside of the CNS, Cx43 expression and function is mediated by cGMP signaling. Rat mesangial cells treated with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) or 8-Br-cGMP increased expression of Cx43 . Additiouctivity . Finallyuctivity . The pot2+ channels have been confirmed to populate the astrocytes of the rat forebrain, midbrain, and hindbrain, and are important for astrocyte function [2+ channels [2+ signaling plays a critical role in maintaining the integrity of the BBB [2+ channels specifically contribute to the abnormal vascular function of astrocytes in the glaucomatous NVU. cGMP-gated Ca2+ channels in astrocytes have been investigated as a potential therapeutic target for vascular dysfunction in Alzheimer’s disease [2+ channels in retinal astrocytes in glaucoma may uncover a novel therapeutic target.Besides connexins, cGMP-gated channels also impart changes in astrocyte physiology that may perturb vascular function in glaucoma. cGMP-gated Cafunction . MG alsochannels . Within  the BBB ; yet, it disease . Given t disease , investi2+ influx into RGCs, which activates neuronal nitric oxide synthase, leading to NO production and release, stimulating vasodilation in its target vascular cells via cGMP [−/−GC1 mice [2+ levels. Since cGMP has multiple downstream effectors that may contribute to the neuroprotective effects observed in RGCs, further research is needed to distinguish the apparent neuroprotective and neurodegenerative arms of the cGMP signaling cascade.In glaucoma, the degeneration of RGCs and their axons in the optic projection results in irreversible vision loss. The role of NO-cGMP signaling in RGCs appears to be multifaceted. In CNS neurons, NO-cGMP signaling is important in NVC, synaptic plasticity, and synaptic transmission . GC1 is via cGMP . Interes−/− mice  develop −/− mice . Further−/− mice . Within −/− mice , and mul−/− mice ,112,113 −/− mice ,114. How−/− mice ,116, sug−/− mice ,118. The−/− mice ,120,121.−/− mice  and therGlaucoma is a devastating optic neuropathy afflicting millions worldwide, and yet the complex etiology of the disease results in the ensuing neurodegeneration not receiving effective treatment for many individuals. While the past understanding and treatment of the disease has focused on controlling IOP, the only current modifiable risk factor, recent research has elucidated a substantial contribution of retinal vasculature dysfunction to disease progression ,7,9,34. It is clear that NO-cGMP signaling is integral to NVC between retinal neurons and the retinal vasculature and that proper cGMP signaling helps to maintain the integrity of the BRB. Interestingly, NO-cGMP signaling has additional roles in glial cell physiology and homeostasis. While we have highlighted the importance of NO-cGMP signaling in multiple cell types of the NVU and have provided evidence of dysfunctional cGMP signaling in glaucoma, a number of questions remain. Specifically, in glaucoma, how might dysfunctional NO-cGMP signaling in cells of the NVU directly contribute to RGC degeneration? Given the ubiquity of cGMP in cells of the NVU, answering this question will not be facile. Future studies implementing cell-specific knockouts or knockdowns of GC1, combined with animal models of neurodegeneration will be critical in elucidating the relationship between NO-cGMP signaling in the NVU, vascular dysfunction, and glaucoma pathology. Disentangling the specific role of NO-cGMP in cells of the NVU and the relationship to glaucomatous degradation would be indispensable in providing a more comprehensive understanding of the vascular mechanisms of the disease and help to provide effective novel therapeutic targets.


African savannas are experiencing anthropogenically-induced stressors that are accelerating the increase of woody vegetation cover. To combat this, land managers frequently implement large-scale clearing of trees, which can have a cascading influence on mammalian herbivores. Studies rarely focus on how differences in woody cover influence the herbivore assemblage, making it difficult to assess how aggressive measures, or the lack of management, to counteract increasing woody cover affect the local composition and biodiversity of herbivores. We address this knowledge gap by applying a model-based clustering approach to field observations from MalaMala Game Reserve, South Africa to identify multiple herbivore–vegetation ‘configurations,’ defined as unique sets of herbivore assemblages  associated with differing woody plant covers. Our approach delineated how tree-clearing influences the distribution and abundance of the herbivore community in relation to surrounding savanna areas, which represent a natural mosaic of varying woody cover. Regardless of season, both intensively managed areas cleared of trees and unmanaged areas with high tree cover contained configurations that had depauperate assemblages of herbivores . By contrast, habitats with intermediate cover of woody vegetation had much higher richness and abundance. These results have substantial implications for managing African savannas in a rapidly changing climate. Savannas cover approximately 50% of the land surface of the African continent . This biTragelaphus strepsiceros, and giraffe, Giraffa camelopardalis) as well as influences soil properties that can affect the quality and quantity of the herbaceous layer for grazing species  [Woody plant cover is a key factor that influences the distribution of mammalian herbivores across the landscape because it synergistically influences both top-down  and bottom-up  processes –10. Specaurinus) . Ultimataurinus) , 15. Howaurinus) –20. BecaUnderstanding the response of the herbivore community to a woody plant gradient is critically important, especially in the context of global change. For example, African savannas and savannas globally are experiencing shifts towards woody plant dominance via woody thickening  and woody encroachment  , 22. To Here, we leverage large-scale tree clearings to understand how management approaches that control increasing woody cover influence the distribution, abundance, and diversity of the herbivore community. These clearings occur within an African savanna that is characterized by a natural gradient of tree densities, including areas that have experienced woody thickening. This allows assessment of the response of herbivores along a woody plant cover gradient and provides a unique opportunity to address the effects of this widespread management action on herbivore assemblages . We identified unique configurations consisting of herbivore assemblages associated with particular levels of woody plant cover and then used these to explore how woody plant cover influences patterns of herbivore species richness and abundance. We predicted that woody plant cover would structure herbivore assemblages, however, the exact responses of herbivores to woody cover would be modulated by their feeding guild. Specifically, an increase in woody plant cover should favor browsing species while negatively impacting grazing species. Moreover, because of seasonal effects on the resource acquisition-predation risk tradeoff, we predicted that herbivore responses would vary across the wet and dry seasons with herbivores shifting towards woodier areas in the dry season. Finally, using our findings, we identify management approaches that could either facilitate or suppress the diversity and abundance of the savanna herbivore communities.Panthera leo) and leopard (Panthera pardus) as well as various cursorial predators including cheetah (Acinonyx jubatus), African wild dog (Lycaon pictus), and spotted hyena (Crocuta crocuta). Additionally, our study site has a diverse herbivore guild (see below).We conducted our study in the MalaMala Game Reserve  within the Sabi Sands Wildtuin–MalaMala Complex, which forms part of the Greater Kruger National Park, South Africa. The study site is unfenced and is bordered by the Kruger National Park to the east and the Sabi Sands Wildtuin to the north, south, and west. The Sand River is the major source of water. There are a number of dams and pans scattered throughout the study site, however, these do not receive artificial water provisioning during the dry season. MalaMala Game Reserve contains a diverse large predator guild including ambush predators such as lion  clearing campaign 50–60 years ago , creating large (30–50 ha) swaths of human-made, artificial grassland [2. The remaining tree species in these areas are the same species found in the adjacent mosaic of savanna vegetation. The tree-cleared areas have been maintained by annual mowing creating open, artificial grasslands that occur within a natural mosaic of woody plant cover ranging from open savannas to woody thickets.The vegetation is characterized by a mixed combretum/terminalia woodland , with thrassland . These crassland . In thesSyncerus caffer), common duiker (Sylvicapra grimmia), African elephant (Loxodonta africana), giraffe, impala (Aepyceros melampus), kudu, nyala (T. angasii), steenbok (Raphicerus campestris), warthog (Phacochoerus africanus), blue wildebeest, white rhinoceros (Ceratotherium simum), and plains zebra. These species fall into one of three feeding guilds: browser (eats primarily woody vegetation), grazer (eats primarily grasses), or mixed-feeder (eats both woody vegetation and grasses)  see .as per Caro [To assess the abundance and habitat associations of the herbivores, we conducted standardized daily driving transects (20 or 40 km per day) during the wet  and dry  seasons of 2018, following the guidelines of Caro . Such trper Caro . The traper Caro , the patper Caro  and is fper Caro , 33, 34.per Caro .The same two observers enumerated all herbivore species encountered within 50 m of the road, which is within the established detection range for the majority of large mammals, as per Caro  wet sea. To linkBecause diel cycles can influence patterns of herbivore habitat use e.g., , we corret al. [mclust package in R [et al. [Similar to Hempson et al. , who useage in R . This frage in R . Thus, t [et al. . The 12 The availability of habitats with different levels of woody plant cover can influence herbivore habitat use. Thus, to assess whether our configurations were influenced by habitat availability, as well as make them more meaningful, we linked percentage woody plant cover associated with the configurations with six key habitat types found in African savannas (as described above) based on their average woody plant cover e.g., . The higstatmod package in R, following Dunn and Smythe [To investigate whether herbivore species richness and abundance varied with woody plant cover, we used generalized linear models (Gamma distribution with a log link function) to compare total herbivore richness and total abundances across configurations in each season. Model contrasts and confidence intervals were calculated with Tukey’s Honest Significant Difference Tests. In addition, herbivores were grouped into their respective feeding guilds  and the seasonal abundance of each feeding guild category across the different model-generated configurations was analyzed using generalized linear models (Compound Poisson distribution with a log link function from the Tweedie family of distributions) using the d Smythe . We usedd Smythe . To redud Smythe  correctid Smythe .Our Bayesian model-based clustering identified thirteen distinct herbivore-woody plant cover configurations in our system . Seven cConfigurations at opposite ends of the woody plant cover gradient were species depauperate and had low relative abundance of each species compared to configurations that occurred in intermediate woody cover habitats  also had lower species richness and herbivore abundance compared to habitats having intermediate levels of woody cover . The disP-values <0.001, The overall patterns in total herbivore abundance across configurations are the result of herbivores, irrespective of their feeding guild, showing similar responses to the woody plant cover gradient. We found significant differences in abundance across configurations in both seasons  and bottom-up  processes –10. Althet al. [We found that the distribution of herbivores across the landscape, as revealed by our configurations, was influenced by woody plant cover. Similar to Anderson et al. , there wet al. , 53. TheThe diversity of herbivores in African savannas is frequently linked to the spatial and temporal heterogeneity inherent to this biome , 54. At In tree-cleared areas, the removal of trees and shrubs reduces structural heterogeneity. Similarly, the widespread increase in woody plant cover, especially through woody densification can reduce the herbaceous layer and homogenize vegetation structure. Combined, these practices result in the habitat homogenization at large spatial scales. This homogenization reduces the potential niches for species to occupy, which likely drives the low observed species richness and abundance in these areas. Similarly, the negative effect of homogenizing habitat structure has been shown in other systems for a range of different taxa, including birds, bats, reptiles, and small mammals , 57. We With respect to the avoidance of tree-cleared and encroached habitats, we posit that animal behavior is playing an important role. For example, herbivores perceive savanna habitats with low woody plant cover to be less risky than habitats with higher woody plant cover because of increased visibility to detect predators , 12, 62.In contrast to configurations at the extreme ends of the woody plant gradient, habitats with intermediate woody plant cover had configurations with the highest levels of richness and abundance. These patterns are likely a result of the fact that these habitats provide the best balance between food acquisition and predation risk as well as provide the most niches for the herbivore community to fill . For allet al. [Large mammalian herbivores can influence ecosystem structure and function through both herbivory, which affects plant community composition and structure –72, and et al.  found thet al. , 75. Foret al. . Thus, aet al. . FurtherA meta-analysis of long-term change revealed that numerous African savannas are on a trajectory of accelerating rates of increasing woody plant cover . Due to Our configuration approach captures the dynamics of both herbivores and woody vegetation cover in the light of global change and habitat management to provide new insights into the ecological complexity of African savannas. Ultimately, by using an approach that considers both large-scale vegetation physiognomy and herbivore assemblages, we provide an important assessment approach that resource managers can apply to understand how management interventions may structure the distribution of the herbivore community. Finally, these results not only highlight the importance of creating and maintaining savannas with diverse habitats that range in tree cover, but also emphasize the ecological need for evaluating both the vegetation and herbivore communities in a holistic way to guide management interventions.S1 Table(DOCX)Click here for additional data file.S1 Fig(DOCX)Click here for additional data file.S2 FigData for each habitat type, except thicket, were collected from our study site. For the thicket habitat, we used the estimate of woody plant density in Belsky (1990), hence the lack of 95% confidence intervals.(DOCX)Click here for additional data file.S3 FigWe found that artificial grasslands comprise ~10%, open canopy savanna comprise ~12%, semi-open canopy savanna comprise ~20%, woody savanna comprise ~15%, closed-canopy woody savanna comprise ~26%, and thicket comprise ~16%. The marginal differences in the proportional availability of the different habitats are unlikely to influence the observed patterns of configurations generated from our model (see main text).(DOCX)Click here for additional data file.S1 Text(DOCX)Click here for additional data file.


Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic human retrovirus which causes a lifelong infection. An estimated 5–10 million persons are infected with HTLV-1 worldwide – a number which is likely higher due to lack of reliable epidemiological data. Most infected individuals remain asymptomatic; however, a portion of HTLV-1-positive individuals will develop an aggressive CD4+ T-cell malignancy called adult T-cell leukemia/lymphoma (ATL), or a progressive neurodegenerative disease known as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Few treatment options exist for HAM/TSP outside of palliative care and ATL carries an especially poor prognosis given the heterogeneity of the disease and lack of effective long-term treatments. In addition, the risk of HTLV-1 disease development increases substantially if the virus is acquired early in life. Currently, there is no realistic cure for HTLV-1 infection nor any reliable measure to prevent HTLV-1-mediated disease development. The severity of HTLV-1-associated diseases  and limited treatment options highlights the need for development of a preventative vaccine or new therapeutic interventions. This review will highlight past HTLV-1 vaccine development efforts, the current molecular tools and animal models which might be useful in vaccine development, and the future possibilities of an effective HTLV-1 vaccine. Human T-cell leukemia virus type 1 (HTLV-1) was the first identified human retrovirus and is the only oncogenic human retrovirus known to date . An estiin utero or during delivery. Several risk factors increase the chances of HTLV-1 MTCT including duration of breastfeeding, HTLV-1 proviral load in the mother’s blood and/or breastmilk, level of HTLV-1 antibody titer, HLA concordance, presence of disease in the mother, Strongyloides co-infection, and family income  drug users, blood donations, and organ transplantation. Cases of transplant-derived HAM/TSP and ATL have been reported in many countries . In one Sexual transmission of HTLV-1 is more efficient from men to women than women to men . InfectiLike all retroviruses, HTLV-1 has two positive polarity single-stranded RNA genomes, packaged with several viral enzymes , surrounded by capsid proteins forming a roughly spherical viral nucleocapsid. A host-derived lipid bilayer envelope, studded with viral glycoproteins  surrounds the viral capsid. As a member of the deltaretrovirus genus, HTLV-1 is a complex retrovirus that expresses several regulatory and accessory genes, in addition to the standard structural and enzymatic genes common to all retroviruses . These rIn order to develop a protective HTLV-1 vaccine, the structure and function of the proteins that mediate viral entry and the viral life cycle must be characterized. The HTLV-1 envelope is the primary protein that mediates viral entry. It is an immunodominant viral glycoprotein composed of two subunits: gp46  and gp21  . Like moUnlike many other viruses, cell-free infection by HTLV-1 is extremely inefficient  . EfficieViral transcription initiates at promoter/enhancer elements found in the 5′ LTR, while a polyadenylation signal is found in the 3′ LTR. The first viral transcript expressed from the provirus after integration is the doubly spliced tax/rex transcript . Tax funde novo infection. In addition to its transcriptional role, Hbz also regulates genomic integrity, apoptosis, autophagy, and immune evasion in infected cells  . ATL is The availability of a well-established animal model is an essential feature of vaccine design. The HTLV-1 field has two widely available and established animal models: one that mimics early infection in humans (rabbits) and one that models lymphoproliferative disease after HTLV-1 infection [humanized immune system (HIS) mice].in vivo infection (The rabbit model of infection was first demonstrated in 1985 when intravenous inoculation of rabbits with a HTLV-1-infected rabbit lymphoid cell line (Ra-1) lead to rabbit seropositivity . Other pnfection . New Zeanfection . Importaex vivo HTLV-1-infected CD34+ hematopoietic progenitor and stem cells (HP/HSCs) and subsequently developed CD4+ T-cell lymphomas with elevated T-cell proliferation. In a 2011 report, NSG mice were reconstituted with CD34+ stem cells and subsequently infected with HTLV-1 ] mice were inoculated with human PBMCs followed by infection with HTLV-1-infected cells . This reh HTLV-1 . This sth HTLV-1 .in vivo. One approach to develop better adaptive immune responses was reported in 2014. In this study, HIS mice were created by transplanting human CD133+ hematopoietic stem cells into the bone marrow cavity of NOG mice using an intra-bone marrow injection method , protein vaccines, DNA vector vaccines, and peptide vaccines.in vitro, but had varying antibody responses, suggesting that the capacity of various vaccinia strains to induce antibody titers in vivo may be affected by their growth rates in rabbits.One of the first published HTLV-1 vaccine studies in 1987 used a recombinant vaccinia virus (rVV) that expressed the envelope glycoprotein in place of the hemagglutinin gene . One inoA subsequent study in 1995 used the entire envelope DNA sequence  and expressed it in a highly attenuated poxvirus vaccine vector . New ZeaHTLV-1 Env rVV vaccine trials have also been tested in cynomolgus monkeys . This reA recent rVV study used either Hbz or Tax as a target for host immune responses . VaccinaProtein vaccine approaches have also showed promising results. One study from 1990 immunized pig-tailed macaques with soluble proteins isolated from MT2 cells, an HTLV-1 transformed cell line . After cIn 1997, the first report of direct DNA inoculation with a plasmid encoding HTLV-1 envelope in BALB/c mice was reported . ProteinA study in 2001 evaluated the immunogenicity and protective effect of a vaccine involving priming with a highly attenuated vaccinia virus NYVAC HTLV-1 vaccine, followed by a booster with HTLV-1 Env DNA in squirrel monkeys . SquirreN-acetylglucosamine at residue Asn244. Similar conformation between both the glycosylated and non-glycosylated peptides was observed and both chimeric peptides were highly immunogenic in rabbits – producing antibody titers within 3 weeks post vaccination. Human sera from HTLV-1-positive individuals were able to recognize both the glycosylated and non-glycosylated constructs. Together this data suggests glycosylation of HTLV-1 gp46 does not affect the conformational preference or stability of the glycoprotein nor alter immunogenicity.Peptide vaccines have also had some success for HTLV-1 vaccine purposes. One of the first peptide studies in 1992 used a synthetic peptide derived from an immunodominant external envelope region mapping within amino acids 242–257 . When teOne disadvantage of peptide-based vaccines is their poor immunogenicity, thus often requiring tailored immunization procedures and adjuvants to evoke immune responses. A previous study used a gp46 peptide sequence from amino acids 175–218 linked C-terminal by a four-residue motif (GPSL) turn to the promiscuous T-cell epitope of the measles virus fusion protein . This chMuch of the HTLV-1 vaccine research that has predominated the literature are preventative vaccines. In 2015, a pilot study (three patients) investigated the safety and efficacy of a Tax peptide-pulsed dendritic cell vaccine used to treat ATL patients . HTLV-1-in vivo half-life, as well as enhanced efficacy through modulation of stability and translation  and 2 were given no treatment at birth. HTLVIG treated litters had significantly less infection compared to control litters (8.3 vs. 42.9%)  . A separ. 42.9%) . However to MTCT . Taken tThe best way to prevent HTLV-1 infection is to block viral entry into host cells. The HTLV-1 envelope is one of the most immunogenic HTLV-1 proteins and is required for entry of target cells and establishment of initial viral infection. Antibody responses against Env can be detected in ATL patients as well as asymptomatic carriers  and it iin vivo data in rabbits suggests glycosylation of HTLV-1 gp46 does not alter immunogenicity , as well as cellular responses, may be required to identify and eliminate infected cells for protection.A major challenge in eliciting protective vaccine responses is the cell-to-cell transmission of HTLV-1. Cell-to-cell transmission of HTLV-1 can occur through the establishment of cellular conduits, the formation of a virological synapse (VS), or extracellular viral assemblies . It is uAnother challenge of HTLV-1 vaccine design is the lack of research characterizing the HTLV-1 Env structure. While HTLV-1 virions have been imaged and the structure of the gp21 transmembrane domain has been solved, the structure of subunit gp46 has still not been resolved . Since tHTLV-1 is a bloodborne pathogen that infects 5-10 million people and transmission occurs through breastfeeding, sexual transmission, and contaminated blood products. It is the causative infectious agent of several diseases including an aggressive CD4+ T-cell malignancy (ATL) and a progressive neurodegenerative disease (HAM/TSP). Approximately 5–10% of infected individuals develop disease after a prolonged clinical latency period of several decades. Despite decades of research, the complex mechanism of HTLV-1 persistence and disease development remains poorly defined and current treatment options are largely ineffective.There is currently no vaccine for HTLV-1, although the development of one is considered feasible. Past vaccination efforts have focused on preventative vaccines targeting the envelope glycoprotein. Various approaches including recombinant vaccinia virus vectors, protein vaccines, DNA vector vaccines, and peptide vaccines have been explored with some success. Env is one of the most immunogenic HTLV-1 proteins, and antibody responses against Env can be detected both in ATL patients and asymptomatic carriers. The genetic stability of Env, high sequence conservation among viral isolates, and anti-Env activity in infected individuals makes this protein a favorable target for vaccine development. Recent approaches have also examined the safety and efficacy of therapeutic Tax peptide-pulsed dendritic cell vaccines to treat ATL patients.Current advances in vaccine research have made mRNA vaccines a promising prophylactic strategy against viruses, and their potential use for HTLV-1 is intriguing. While hurdles remain, such as viral transmission strategies (cell-to-cell) and lack of structural research tools, there are several advantages, including the wide use of animal models and highly conserved nature of the HTLV-1 genome, which would benefit the development of a preventative vaccine.JT and AP wrote the first draft of the manuscript. VM and LR wrote sections of the manuscript. All authors contributed to manuscript revision, read, and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Genetic characteristics related to lower angiogenesis activity might be associated with a lower chance of establishing HTLV-1 infection. Although further investigation is necessary, angiogenesis might play a crucial role in the establishment of HTLV-1 infection.Previous studies have reported a close correlation between vascular endothelial growth factor (VEGF), which plays an important role in angiogenesis, and human T-cell leukemia virus 1 (HTLV-1). However, an association between genetic characteristics related to VEGF and HTLV-1 infection has not yet been reported. Because the VEGF polymorphism rs3025039 is inversely associated with serum concentrations of VEGF, we focus on rs3025039 in the present study. To clarify the association between the VEGF polymorphism rs3025039 and HTLV-1 infection, a cross-sectional study of 1924 Japanese individuals aged 60–79 years who participated in general health check-ups was conducted. Using logistic regression, odds ratios (ORs) and 95% confidence intervals (CIs) for HTLV-1 infection in relation to rs3025039 genotype were calculated with adjustment for known confounders. Compared with rs3025039 CC-homozygotes, (T) allele carriers had a significantly lower OR for HTLV-1 infection. The adjusted OR and 95% CI for HTLV-1 infection was 0.70 (0.54–0.91) ( Human T-cell leukemia virus 1 (HTLV-1) spreads though parenteral, sexual, and vertical (mother-to-child) routes . TherefoMost HTLV-1 carriers remain asymptomatic throughout their life ,4,5. HowHTLV-1–infected T cells acquire the ability to secrete vascular endothelial growth factor (VEGF) , which iFurthermore, angiogenesis likely contributes to the development of leukemia . IncreasIn addition, because HTLV-1 infected cells acquire the ability to secrete VEGF , serum cTherefore, genetic characteristics that have the disadvantage of activating angiogenesis could prevent HTLV-1 activity during the early stages of HTLV-1 infection. HTLV-1 infected cells might not have increased levels of VEGF in individuals in the early stages of HTLV-1 infection. Serum VEGF concentration is reported to be inversely associated with the (T) allele of the VEGF polymorphism rs3025039 , which iClarifying the association between VEGF polymorphisms rs3025039 and rs3025020 and HTLV-1 infection might help to clarify the crucial role of angiogenesis during the early stage of HTLV-1 infection. We hypothesize that VEGF polymorphism rs3025039 is inversely associated with HTLV-1 infection among older individuals. To clarify the association between VEGF polymorphism rs3025039 and HTLV-1 infection, a cross-sectional study was conducted.A cross-sectional study was conducted using data from the Nagasaki Island Study, which was a cohort study performed in Goto city in western Japan. The survey was conducted in different areas of Goto city over a period of three years to ensure that all areas of the city were included. Details about this survey have been provided elsewhere .After obtaining informed consent, 2405 Japanese individuals (922 men and 1483 women) aged 60–79 years who had undergone a comprehensive health check-up from 2016 to 2018 participated this study. Individuals without data on HTLV-1 status (n = 9), VEGF polymorphism rs3025039 genotype (n = 468), or VEGF polymorphism rs3025020 genotype (n = 4) were excluded. The remaining 1924 elderly Japanese individuals (711 men and 1213 women) were included in the analysis. Their mean (standard deviation [SD]) age was 70.3 (5.3) years.Written consent forms were made available to ensure that the participants understood the objective of the study. The ethics committee of Nagasaki University Graduate School of Biomedical Sciences approved the study (project registration number: 14051404-13), which was conducted according to the ethical standards defined in the 1964 Declaration of Helsinki and its subsequent amendments.Trained interviewers obtained medical histories from participants. Blood pressure (systolic and diastolic) was measured at rest in a seated position using a blood pressure measuring device . Hypertension was defined as systolic blood pressure ≥140 mmHg, diastolic blood pressure ≥90 mmHg, or antihypertensive medication use.A chemiluminescent enzyme immunoassay kit  was used at SRL, Inc.  to detect HTLV-1 infection. Confirmatory tests for the detection of HTLV-1 were not performed in this study. Therefore, the presence of serum anti–HTLV-1 antibody was considered to indicate HTLV-1 infection; testing for HTLV-1 viral DNA was not performed. However, we believe that the influence of the lack of confirmatory testing for HTLV-1 infection was limited. Our previous study that involved real-time reverse transcription polymerase chain reaction with a hydrolysis probe and western blotting assays showed a low false-positive rate (1.2%) .Genomic DNA was extracted from 2 mL of peripheral whole blood using a Gene Prep Star NA-480 . Genotyping of the single nucleotide polymorphisms (SNPs) rs3025039 and rs3025020 was conducted using TaqMan assays and a LightCycler 480 thermal cycling platform .Carotid intima-media thickness (CIMT) was measured using B-mode ultrasonography with a LOGIQ Book XP device and a 10-MHz transducer . Because CIMT reflects organic lesions, CIMT acts as an indicator of structural arterial stiffness. Maximum CIMT values for the left and right common carotid arteries were calculated using a semi-automated digital edge-detection software program  .p-values.The characteristics of the study participants by rs3025039 genotype or rs2025020 genotype were expressed as means ± SD for continuous variables. The sex distribution and the prevalence of hypertension, rs3025020 or rs3025039 (CT) genotype, and rs3025020 or rs3025039 (TT) genotype were expressed as percentages. The trend test was performed in logistic regression models to evaluate Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to determine the association between rs3025039 genotype  and two categories  allele carrier)) and HTLV-1 infection. In addition, logistic regression was used to evaluate the associations between HTLV-1 infection and rs3025020 genotype as a variable with three categories  or two categories  allele carrier).To adjust for confounding factors, two different models were conducted. Model 1 adjusted for age (years) and sex. In Model 2, we included three other potential confounding factors , CIMT (mm), and rs3025020 genotype or rs3025039) for the following reasons. HTLV-1 infection was revealed to be inversely associated with hypertension and positively associated with structural atherosclerosis as evaluated by CIMT . Serum cFor sensitivity analysis, we performed the main analyses for the association between rs3025039 genotype  allele carrier)) and HTLV-1 infection stratified by sex.p-values for statistical tests were two-tailed, and p-values of <0.05 were regarded as statistically significant.All statistical analyses were performed using SAS for Windows, version 9.4 . All In this study, there were 1234 CC-homozygotes, 584 CT-heterozygotes, and 106 TT-homozygotes with the rs3025039 genotype. There were 1019 CC-homozygotes, 723 CT-heterozygotes, and 182 TT-homozygotes for the rs3025020 genotype. There were 347 HTLV-1 carriers.The association between rs3025039 genotype (three categories) and HTLV-1 infection is shown in In the sex- and age-adjusted model (Model 1) with CC-homozygotes as the referent group, the adjusted ORs and 95% CIs for HTLV-1 infection were 0.75  for CT-heterozygotes and 0.59  for TT-homozygotes. Even after further adjustment for CIMT, hypertension, and rs3025020 genotype (Model 2), these associations remained. With CC-homozygotes as the referent group, the fully-adjusted ORs and 95% CIs for HTLV-1 infection were 0.72  for CT-heterozygotes and 0.57  for TT-homozygotes.With CC-homozygotes as the referent group, the adjusted ORs and 95% CIs for HTLV-1 infection were 0.72  for (T) allele carriers in the sex- and age-adjusted model (Model 1) and 0.70  in the fully-adjusted model (Model 2).For sensitivity analysis, we performed the main analysis using sex-specific models. We found essentially the same associations. The fully adjusted ORs and 95% CIs for HTLV-1 infection among rs3025039 (T) allele carriers were 0.45  among men (n = 711) and 0.84  among women (n = 1213), respectively.In the sex- and age-adjusted model (Model 1) with CC-homozygotes as the referent group, the adjusted ORs and 95% CIs for HTLV-1 infection were 0.94  for CT-heterozygotes and 1.14  for TT-homozygotes. The associations were essentially the same after further adjustment for CIMT, hypertension, and rs3025039 genotype (Model 2). With CC-homozygotes as the referent group, the fully-adjusted ORs and 95%CIs for HTLV-1 infection were 0.86  for CT-heterozygotes and 0.96  for TT-homozygotes.With CC-homozygotes as the referent group, the adjusted ORs and 95% CIs for HTLV-1 infection were 0.88  for (T) allele carriers in the sex and age-adjusted model (Model 1) and 0.88  in the fully-adjusted model (Model 2).The major finding of the present study involving older Japanese individuals is that VEGF polymorphism rs3025039 (T) allele carriers had significantly lower odds of HTLV-1 infection compared with CC-homozygotes. Potential mechanisms underlying the inverse association between VEGF polymorphism rs3025039 and HTLV-1 infection need to be further discussed.Serum concentrations of VEGF are inversely associated with the (T) allele of VEGF polymorphism rs3025039 and positively associated with the (T) allele of VEGF polymorphism rs3025020 . In the Because no significant associations between the rs3025020 genotype and HTLV-1 infection were observed, the lack of angiogenesis-related hetero-cellular communication and shortage of VEGF-related tumor-induced immune suppression might play important roles in the inverse association between being an rs3025039 (T) allele carrier and HTLV-1 infection.Angiogenesis plays a crucial role in leukemia proliferation . AngiogeFurthermore, VEGF contributes to tumor-induced immune suppression . TherefoHTLV-1-infected cells secrete VEGF . TherefoThis is the first study to report that an angiogenesis-related genetic factor could influence the infectious capacity of HTLV-1. Asymptomatic HTLV-1 infection is positively associated with periodontitis ,23. BecaLife-long follow-up studies are necessary in order to clarify the influence of symptomatic disease on the association between rs3025039 and HTLV-1 infection, as aging is a process that elevates the risk of adult T-cell leukemia-lymphoma among asymptomatic HTLV-1 carriers ,5. The pSeveral limitations of the present study warrant consideration. First, there were only thirteen individuals infected with HTLV-1 who were TT-homozygotes, which might have been insufficient to detect a statistically significant association. Although an inverse association between HTLV-1 infection and the (T) allele of rs3025039 has been observed, further investigation with more individuals with HTLV-1 infection and TT-homozygote status is necessary. Second, we had no data about hematopoietic stem cells. Hematopoietic stem cells, such as CD34-positive cells, might play an important role in the present results, as CD34-positive cells contribute to the development of structural atherosclerosis  and progIn conclusion, compared with CC-homozygotes, (T) allele carriers of the VEGF polymorphism rs3025039 have significantly lower odds of HTLV-1 infection among older Japanese individuals. Genetic factors related to a lower chance of progressive angiogenesis reduce the risk of HTLV-1 infection.