ИСТИНА

Inflammation is an important component of the innate immunity. The increased level of pro-inflammatory cytokines, such as TNFα are usually observed in chronic and acute inflammation. The cytokines increase leukocyte adhesion and vascular permeability. One of the key factors mediating intercellular adhesion is ICAM1 (intercellular adhesion molecule 1). ICAM1 mediates the firm adhesion of leukocytes to the surface of vascular endothelial cells and their migration to the site of inflammation. Overexpression of ICAM1 is observed under many pathological conditions including autoimmune diseases, vascular dysfunctions and aging. We have previously shown that mitochondria-targeted antioxidant SkQ1 is able to decrease endothelial cell activation caused by TNFα. These in vitro experiments also indicated that SkQ1 prevented disassembly of intercellular contacts by protecting the cytoskeleton proteins β-catenin and VE-cadherin from TNFα-induced degradation. Thus SkQ1 decreased the level of endothelium permeability. The main target of current work was to elucidate the mechanism underlying SkQ1 activities on endothelium cells, especially on the ICAM1 expression. Incubation of endothelial cells with picomolar concentrations of SkQ1, or with its derivate without antioxidant moiety C12TPP (C12-triphenilphosphonium) or even with classical mitochondrial uncoupler DNP (2, 4-dinitrophenol) led to decreased expression of level of ICAM1 mRNA. These compounds also prevented TNFα-induced increase in ICAM1 expression as well as secretion of proinflammatory cytokines IL-6 and IL-8. Since SkQ1 and C12TPP were previously shown to have mild uncoupling activity, we assume that mitochondrial uncoupling leads to downregulation of cellular adhesion molecules expression. There are two main mechanisms regulating ICAM1 expression via TNFα: MAPK- and NFkB-signaling pathways. Since MAPK-signaling pathway didn`t have significant impact on the ICAM1 expression under our experimental conditions we focused on the NFkB-signaling pathway. We have shown SkQ1 and other uncouplers to inhibit various stages of NFkB-signaling pathway including IkBa phosphorylation and p65 (RelA) translocation into the nucleus. The experiments on animals also proved anti-inflammatory activity of SkQ1. The level of ICAM1 mRNA in aortas of SkQ1-treated old mice was significantly lower than the level of ICAM1 mRNA in the aortas of non-treated mice. The obtained results proved that mitochondrial uncouplers including SkQ1 are able to regulate ICAM1 expression via NFkB-signaling pathway assuming mitochondria to play important role in inflammatory processes thus opening new possibilities for the development of next generation drugs against various endothelial dysfunctions.