MO712: Involvement of Mitochondrial Dysfunction in the Inflammatory Response in Human Mesothelial Cells from Peritoneal Dialysis Effluent

Abstract

Abstract BACKGROUND AND AIMS Recent studies have related mitochondrial impairment with peritoneal membrane damage in peritoneal dialysis (PD) therapy. Here we assessed the involvement of mitochondrial dysfunction in the inflammatory response in human mesothelial cells, a hallmark in the pathogenesis of PD-related peritoneal membrane damage. METHOD Ex vivo studies of effluent-derived human mesothelial cells were carried out. Mitochondria function was evaluated by analysing the mitochondrial membrane potential with flow cytometry using the fluorescent dye tetramethylrhodamine. Mitochondrial dysfunction was induced with the inhibitors oligomycin and paraquat. The effects of mitochondrial dysfunction on inflammatory mediators were studied. Mitochondrial ROS scavenger (MitoTEMPO) and a NF-κB inhibitor (BAY-117 085) were used to investigate the pathways involved. The natural anti-inflammatory antioxidant resveratrol was also tested. RESULTS Our ex vivo studies showed that IL-1β causes a drop in the mitochondrial membrane potential in cells from peritoneal effluent. Besides, when mitochondrial damage was induced by inhibitors of mitochondrial function a low-grade inflammatory response was generated. Interestingly, mitochondrial damage sensitizes mesothelial cells causing a significant increase in the inflammatory response induced by cytokines, in which ROS generation and NF-κB activation are involved since inflammation was counteracted by both MitoTEMPO and BAY-117 085. Furthermore, pretreatment with resveratrol significantly reduced the inflammatory response by reversing the decline in mitochondrial membrane potential and decreasing the expression of IL-8, COX-2 and PGE2 caused by IL-1β. CONCLUSION These findings suggest that IL-1β regulates mitochondrial function in mesothelial cells and that mitochondrial dysfunction could induce an inflammatory scenario and sensitize these cells, causing a significant amplification of the inflammatory response induced by cytokines. Resveratrol may represent a promising strategy in controlling the mesothelial inflammatory response.