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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, RESULTS. Meshes: Aged, Arteries, Case-Control Studies, Diabetes Mellitus, Female, Glycation End Products, Advanced, Humans, Male, Middle Aged, Mitogen-Activated Protein Kinase 3, Monocytes, Neovascularization, Pathologic, Oxidative Stress, Phosphorylation, Proto-Oncogene Proteins c-akt, Receptor for Advanced Glycation End Products, Receptors, Immunologic, Signal Transduction, Vascular Endothelial Growth Factor A, Vascular Endothelial Growth Factor Receptor-1, p38 Mitogen-Activated Protein Kinases.
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Does diabetes mellitus activate signal transduction pathways resulting in vascular endothelial growth factor resistance of human monocytes? Context: Monocytes are cellular components of wound repair, arteriogenesis, and atherogenesis. Vascular endothelial growth factor (VEGF)-A and placental growth factor recruit monocytes to sites of arteriogenesis via stimulation of VEGF receptor-1 (VEGFR-1). The chemotactic response of monocytes to VEGF-A is attenuated in individuals with diabetes mellitus (DM). This VEGF resistance correlates with impaired collateral growth. The aim of this study is to elucidate the molecular basis of VEGF resistance and impaired monocyte response in DM. Phosphorylation of Akt, p38, and extracellular signal-regulated kinase 1/2 (ERK1/2) could be stimulated with either placental growth factor-1 or VEGF-A in monocytes from non-DM but not DM individuals. In contrast, formyl-methionyl-leucyl-phenylalanine caused a comparable activation of these molecules in both DM and non-DM monocytes. Baseline phosphorylation of Akt, p38, and ERK1/2 was significantly elevated in monocytes from DM compared with non-DM subjects. Of note, H(2)O(2) activated Akt, p38, and ERK1/2 in non-DM monocytes ex vivo. Protein tyrosine phosphatases had stronger oxidative modifications in monocytes from DM than from non-DM individuals, which reflects functional protein tyrosine phosphatase inhibition, similar to that seen after H(2)O(2) challenge. Overall, protein tyrosine phosphatase and protein tyrosine phosphatase-1B activity were reduced in DM monocytes. DM monocytes revealed higher expression of the receptor for advanced glycation end products. Stimulation with advanced glycation end products ligands resulted in activation of non-DM monocytes and inhibition of VEGFR-1-mediated chemotaxis. The elevated baseline phosphorylation/activation of Akt, p38, and ERK1/2 in DM monocytes likely causes the resistance to further stimulation with specific stimuli such as VEGF-A, revealing a molecular explanation of the DM-related signal transduction defect.
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We propose that elevated advanced glycation end products expression and increased oxidative stress in diabetic monocytes lead to activation of VEGFR-1-related signaling pathways and to desensitization of VEGFR-1 responses. These data establish VEGF resistance as a novel molecular concept for DM-related cellular dysfunction. Final Decision: yes