Involvement of glycated albumin in adipose-derived-stem cell-mediated interleukin 17 secreting T helper cell activation

BACKGROUND: Advanced glycation end products (AGE) are a marker of various diseases including diabetes, in which they participate to vascular damages such as retinopathy, nephropathy and coronaropathy. Besides those vascular complications, AGE are involved in altered metabolism in many tissues, including adipose tissue (AT) where they contribute to reduced glucose uptake and attenuation of insulin sensitivity. AGE are known to contribute to type 1 diabetes (T1D) through promotion of interleukin (IL)-17 secreting T helper (Th17) cells. AIM: To investigate whether lean adipose-derived stem cells (ASC) could be able to induce IL-17A secretion, with the help of AGE. METHODS: As we have recently demonstrated that ASC are involved in Th17 cell promotion when they are harvested from obese AT, we used the same co-culture model to measure the impact of glycated human serum albumin (G-HSA) on human lean ASC interacting with blood mononuclear cells. IL-17A and pro-inflammatory cytokine secretion were measured by ELISA. Receptor of AGE (RAGE) together with intercellular adhesion molecule 1 (ICAM-1), human leukocyte Antigen (HLA)-DR, cluster of differentiation (CD) 41, and CD62P surface expressions were measured by cytofluorometry. Anti-RAGE specific monoclonal antibody was added to co-cultures in order to evaluate the role of RAGE in IL-17A production. RESULTS: Results showed that whereas 1% G-HSA only weakly potentiated the production of IL-17A by T cells interacting with ASC harvested from obese subjects, it markedly increased IL-17A, but also interferon gamma and tumor necrosis factor alpha production in the presence of ASC harvested from lean individuals. This was associated with increased expression of RAGE and HLA-DR molecule by co-cultured cells. Moreover, RAGE blockade experiments demonstrated RAGE specific involvement in lean ASC-mediated Th-17 cell activation. Finally, platelet aggregation and ICAM-1, which are known to be induced by AGE, were not involved in these processes. CONCLUSION: Thus, our results demonstrated that G-HSA potentiated lean ASC-mediated IL-17A production in AT, suggesting a new mechanism by which AGE could contribute to T1D pathophysiology.