to study the effect of enhancing therapeutic efficacy and reducing adverse effects of dexamethasone on the inflammatory diseases and thymus atrophy , a formulation is developed , which comprises dexamethasone ( dex ) and dihydromyricetin ( dmy ), with a ratio of 1 / 640 in one embodiment . it has been shown that the formulation could significantly inhibit inflammation and simultaneously prevent thymus atrophy . the reference cited throughout this application is identified in square bracket as “[ xx ]” with xx referring to the number of the corresponding reference on the list of “ references ”. study on the effect of dex , dmy and the formulation comprising dex and dmy on anti - inflammatory effects . male balb / c mice , weighing 19 - 21 g were sensitized through topical application of 20 μl of 0 . 5 % ( v / v ) dnfb in acetone onto the shaved abdomen on days 1 and 2 . challenge was then preformed on day 6 by applying dnfb ( 20 μl , 0 . 5 %, v / v ) on the left inner and outer ear surfaces of mice . dmy ( at dosage of 1 mg / ear ) and / or dex ( 1 . 5625 μg / ml ) dissolved in acetone was topically applied ( 20 μl ) to the ears at 2 nd , 24 th , 48 th , 72 nd , hour after the challenge . the edema was calculated as the difference between the thickness of left and right ear at the 24 th , 48 th and 72 nd h after challenge . fig1 a shows the average of the ear edema of the different groups of mice at that time spot . the control 100 group was treated only with dnfb or solvent solution . fig1 a and 1 b show the effects of dex , dmy and the combinational application of dmy and dex ( illustrated as the dmy + dex group ) on treatment of ear edema of dth mice induced by dnfb . edema as expressed as the increase in ear thickness ( δt in micrometer ± s . e . m .) in the dnfb experiments . percentages of inhibition (% i ) for each measurement were calculated from values for the dex , dmy and dmy + dex groups with respect to those for the model group . statistically significant differences with respect to the model group are expressed as * p & lt ; 0 . 05 and ** p & lt ; 0 . 01 ( dunnett &# 39 ; s t test ). it was shown that the percentages of inhibition of dmy + dex group were significantly increased . further , both dmy and dex could inhibit ear edema of the mice , and the anti - inflammatory effect of dex could be enhanced by dmy . in short , example 1 shows that the dmy could enhance the anti - inflammatory effect of dex on ear edema of mice mediated by dnfb . study on the effect of dex , dmy and the formulation comprising dex and dmy on thymus atrophy . the animal model was conducted as mentioned in section 1 . 1 of example 1 above , in which after the mice were sacrificed by cervical dislocation , the spleens and thymuses were isolated and weighed . fig2 a and 2 b show that the effect of dex , dmy and the combinational application of dmy and dex ( illustrated as the dmy + dex group ) on thymus weight of dth mice induced by dnfb . statistically significant differences with respect to the model group or control group are expressed as * p & lt ; 0 . 05 , ** p & lt ; 0 . 01 ; † p & lt ; 0 . 05 and †† p & lt ; 0 . 01 ( dunnett &# 39 ; s t test ), respectively . percentages of inhibitory rate for each measurement were calculated from values for the dex , dmy and dmy + dex groups with respect to those for the model group . as shown in fig2 a and b , in addition of dmy , the formulation could significantly prevent thymus atrophy induced by dex . in short , example 2 shows the protective effect of dmy on thymus degeneration and the side effect of dex , when it was used to treat ear edema induced by dnfb . study on the effect of dex , dmy and the formulation comprising dex and dmy on the population of cd4 + and cd8 + t cell the animal model was conducted as mentioned in section 1 . 1 of example 1 above , in which after the mice were sacrificed by cervical dislocation , the thymocytes were isolated and washed by pbs . the cells were stained by 20 μl cd4 with cd8 for 30 min avoiding from light , followed by 4 % pfa to fix the cells , and flow cytometery was then conducted . as illustrated in fig3 , the assay shows that cd4 + cd8 + t cell is about 76 % in the thymuses of the control and model groups . when the mice were topically applied by dex , the cd4 + cd8 + t cell population could be decreased to 54 . 7 %. while in the addition of dmy , the ratio of cd4 + cd8 + could be recovered . in short , example 3 describes the assay to show that the effect of dmy , dex and the formulation comprising dex and dmy on immature t population in thymus . study on the effect of dex , dmy and the formulation comprising dex and dmy on the apoptosis of thymocytes . the animal model was conducted as mentioned in section 1 . 1 of example 1 above . thymocytes were washed by cold pbs and binding buffer , resuspended in binding buffer including annexin v - fitc , and then incubated at room temperature for 10 minutes . after adding the binding buffer containing pi , the cells were incubated on ice for another 15 minutes . the data was analyzed by flow cytometry within one hour . as shown in fig4 , in the model group , the ratio of thymocyte apoptosis was about 72 %, while dex increased the ratio of apoptosis to 77 . 9 %. in addition of dmy to dex , the ratio of apoptotic cells was reduced to 72 % in the formulation ( dex + dmy ) group . example 4 shows the effect of dmy , dex and the formulation comprising dex and dmy on the apoptosis of thymocytes using annexin v - fitc and pi . study on the dose - dependent inhibitory effect and the formulation comprising dex and dmy on ear edema of balb / c mice induced by dnfb the animal model was conducted as mentioned in section 1 . 1 of example 1 above . fig5 shows the effect of the combinational application of dmy and dex in a ratio of 640 : 1 ( illustrated as the dmy + dex group ) on treatment of ear edema of dth mice induced by dnfb . edema as expressed as the increase in ear thickness ( δt in micrometer ± s . e . m .) in the dth experiments . percentages of inhibition (% i ) for each measurement were calculated from values for the dmy + dex group with respect to those for the model . statistically significant differences with respect to the model group are expressed as * p & lt ; 0 . 05 and ** p & lt ; 0 . 01 ( dunnett &# 39 ; s t test ). as illustrated in fig5 a and 5 b , the formulation comprising dmy and dex in a ratio of 640 : 1 was dose - dependent and shown to significantly inhibit the ear edema induced by dnfb . in short , example 5 shows that the formulation comprising dmy and dex could suppress the ear edema in a dose - dependent manner . study on the inhibitory effect of the formulation comprising dex and dmy on thymus atrophy of balb / c mice induced by dex . the animal model was conducted as mentioned method in section 1 . 1 of example 1 above . fig6 shows the effect of the combinational application of dmy and dex ( as illustrated in the dmy + dex group ) in a ratio of 640 : 1 after 72 hours of treatment on thymus weight of dth mice induced by dnfb . statistically significant differences with respect to the model group or control group are expressed as * p & lt ; 0 . 05 ; † p & lt ; 0 . 05 and †† p & lt ; 0 . 01 ( dunnett &# 39 ; s t test ), where ns represents not significant . as seen from fig6 a and 6 b , the formulation comprising dmy and dex in a ratio of 640 : 1 was dose - dependent and shown to significantly prevent thymus atrophy . in short , example 6 shows that the formulation comprising dmy and dex could prevent thymus atrophy induced by dex in a dose - dependent fashion . the animal model was conducted as mentioned in section 1 . 1 of example 1 above . for cd4 and cd8 staining of ear sections , paraffin - embedded ears were sectioned and cut into 5 - μm sections , hence then deparaffinized using xylene , 100 % etoh , 95 % etoh , 75 % etoh , and h2o series . antigens were retrieved by steaming samples in dako target retrieval buffer ( dako ) for 20 minutes . after the nonspecific binding sites were blocked , the sections were incubated overnight at 4 ° c . with cd4 or cd8 antibodies ( phoenix pharmaceuticals ). sections were stained with 3 , 3 ′- diaminobenzidine substrate and counterstained with meyer hematoxylin and eosin . negative controls generated by the exclusion of the primary antibody and through the use of an unrelated isotype - matched igg failed to demonstrate any specific labeling . dna was isolated from purified thymic t cells using dna purification kit . pcr was performed using mδrec - and ψjα - specific primers and an mδrec - ψjα fluorescent probe as described previously . the standard curves for murine trecs were generated using a mδrec - ψjα trec pcr product cloned into a pc dna3 . 1 plasmid from prof . gregory d . sempowski ( duke human vaccine institute , duke university medical center , durham , n . c ., usa .). the assay was performed on slides according to previous study [ 1 , 2 ]. as shown in fig7 , dnfb treatment results in a marked increase of the prominent mononuclear cell infiltrate in the ear . when the mice were treated by dex , dmy or the formulation comprising dex and dmy , the number of inflammatory cells could be significantly reduced in the ear cd4 + and cd8 + lymphocytes are required as effector cells for dnfb - induced delayed - type hypersensitivity to develop fully [ 3 ], accounts of these cells in the ears punched from the mice were examined by immunohistochemical analysis . in fig8 and 9 , the results showed that more inflammatory cells could be easily found in the dnfb - induced ears as compared to normal animals , while dex , dmy and formulation comprising dex and dmy ( illustrated as the dmy + dex group ) were shown to reduce the accounts of cd4 + and cd8 + cells in the treated ears in comparison with the model group . on comparing with dex - treated animals , dmy or the formulation comprising dmy and dex was shown to significantly improve the thymic architecture according to the histological examination of thymus . as shown in fig1 , the groups of dmy or the formulation comprising dmy and dex ( illustrated as the dmy + dex group ) are associated with better defined corticomedullary junctions ( dotted line ) than dex group , in which the site of junctions is the place where progenitors arrive in thymus . the t cell output and generation of the newly formed t cells from the thymus can be evaluated by quantifying the presence of tcr excision circles ( trecs ) in thymus that have not proliferated after rearrangement of their tcr , as shown in fig1 . given that formulation comprising dmy and dex induces an increase in thymic weight and improvement of thymic architecture in the mice treated by dex , thymopoiesis and recent thymic emigrants ( rtes ) were quantified by measuring the excisional dna of tcr gene rearrangement . on comparing with the dex - treated animals , it was observed that dmy and the formulation comprising dmy and dex could increase the levels of signal - joint trecs in thymocytes , suggesting that dmy can protect or reverse the thymopoiesis in the dex - treated animals . in view of the above results , the formulation comprising dmy and dex could enhance the anti - inflammatory effect of dex on ear edema , and prevent the thymus atrophy mediated by dex . the exemplary embodiments of the present invention are thus fully described . although the description referred to particular embodiments , it will be clear to one skilled in the art that the present invention may be practiced with variation of these specific details . hence this invention should not be construed as limited to the embodiments set forth herein . 1 . sempowski , g . d ., and rhein , m . e . ( 2004 ) measurement of mouse t cell receptor excision circles , curr protoc immunol chapter 10 , unit 10 31 . 2 . lynch , h . e ., and sempowski , g . d . molecular measurement of t cell receptor excision circles , methods mol biol 979 , 147 - 159 . 3 . wang , b ., fujisawa , h ., zhuang , l ., freed , i ., howell , b . g ., shahid , s ., shivji , g . m ., mak , t . w ., and sauder , d . n . ( 2000 ) cd4 + th1 and cd8 + type 1 cytotoxic t cells both play a crucial role in the full development of contact hypersensitivity , j immunol 165 , 6783 - 6790 .
this invention provides a method of preventing and / or treating thymus degeneration comprising administering an effective amount of dihydromyricetin to a subject in need thereof , in which the degeneration is induced by dexamethasone . in one embodiment , the thymus degeneration is induced during the course of treatment of inflammation by dexamethasone .