All-Trans Retinoic Acid and Glycated Albumin Reciprocally Influence their Effects in Human Mesangial Cells

All-trans-retinoic acid (tRA) modulates in human mesangial cells (MC) antioxidant defenses, the expression of interleukin-1β-induced vascular cell-adhesion molecule-1 (VCAM-1), cyclooxygenase-2 (COX-2), and the retinoic acid-receptor-β (RAR-β). The correlation of the serum levels of glycated hemoglobin A1c with tRA in type 2 diabetes mellitus patients led us to hypothesize that tRA and glycated albumin (GA), the main circulating glycated protein, might mutually interact in MC. We studied 1) the influence of tRA on GA effects in cultured MC: an assessment was made on how pre-incubation with tRA modified the effects of GA on intracellular oxidation and on the expression of mRNA and protein of COX-2 and VCAM-1; and 2) the influence of GA on tRA effects in MC: we studied how the induction of RARβ expression by tRA was modified by GA. Results: GA dose-dependently increased intracellular oxidation and the expression of the molecules involved in leukocyte infiltration, namely COX-2 and VCAM-1. Pre-incubation wit...