Methylglyoxal disturbs the expression of antioxidant, apoptotic and glycation responsive genes and triggers programmed cell death in human leukocytes

Abstract

Methylglyoxal (MG) is a α-dycarbonyl compound derived mainly from glycolysis, whose accumulation is harmful for cells and tissues. Here, we evaluated the cytotoxic effects induced by MG in leukocytes after an acute exposure, measuring as endpoints of toxicity some markers of oxidative stress and programmed cell death. Human leukocytes were isolated and incubated with MG at concentrations ranging from 0.1 to 10 mM for 2.5 h, and subsequently prepared for assays based in flow cytometry, gene expression and immunoreactivity profile. The cells exposed to higher concentrations of MG had significant loss of viability, increased reactive species (RS) production and apoptosis/necrosis rate. These phenomena were accompanied by morphological changes (increased size and granularity) and disruption in mRNA expression of antioxidant, apoptotic and glycation-responsive genes, particularly: Nrf2 (Nuclear factor (erythroid-derived 2)-like 2), SOD1 (CuZn-superoxide dismutase), SOD2 (Mn-superoxide dismutase), GSR (glutathione-S-reductase), BAX (BAX-associated X protein), BCL-2 (BCL-2-associated X protein), AIF (apoptosis inducing factor), GLO-1 (glyoxalase-1) and RAGE (receptor for advanced glycation end products). The mRNA expression of CASP 9 and CASP 3 (caspase-9 and 3) as well as the immunoreactivity of proteins were not changed by MG. Collectively, our data provide evidence that MG activates programmed cell death pathways in leukocytes and that this effect seems to be associated with disturbances in cell redox signaling.