Can blood components with age-related changes influence the ageing of endothelial cells?

Research on vascular endothelial cell ageing helps elucidate the pathogenesis of diseases associated with cell ageing. To investigate endothelial senescence, we used 2-DE coupled with MS to perform a proteomic analysis of: (i) peripheral blood mononuclear cells (PBMCs) from donors in their 20 s ('young') or 60 s ('old') and (ii) human dermal microvascular endothelial cells (HDMECs) treated with sera from young and old donors. Identified proteins could be classified into several functional categories: (i) cytoskeletal regulators: CapG and cofilin 1; (ii) stress response and signal pathway proteins: TXNDC5 and RSU-1; and (iii) apoptosis proteins: Annexin V. We confirmed by Western blot a decrease of RSU-1, CapG and TXNDC5 in PBMCs from old donors. RSU-1, which regulates signal transduction of the downstream Ras, showed decreased mRNA and protein levels in PBMCs from old donors and decreased mRNA levels in HDMECs treated with sera from old donors. In addition, Ras protein levels were increased in PBMCs from old donors. These data indicate that reduced RSU-1 might induce Ras expression, which subsequently could provoke Ras-induced senescence. In conclusion, our data suggest that blood components that exhibit age-related changes, such as alterations in cytoskeletal regulators and stress proteins, may be associated with endothelial cell ageing.