ИСТИНА

Mitochondria-targeted antioxidants against inflammation Nina V. Vorobjeva, Ivan I. Galkin, Anastasia S. Prikhodko, Maria A. Chelombitko, Sergei A. Golyshev, Konstantin G. Lyamzaev, Vlada V. Zakharova, Olga Yu. Pletjushkina, Ekaterina N. Popova, Roman A. Zinovkin, Boris V. Chernyak Bchernyak1@gmail.com A.N.Belozersky Institute of Physico-Chemical Biology, and Biology Faculty, Lomonosov Moscow State University, Moscow 119992, Russia Inflammation is a complex defence reaction to pathogens and other harmful stimuli involving immune cells as well as blood vessels. Reactive oxygen species produced by mitochondria (mtROS) can be involved in the regulation of inflammatory responses in both types of cells. We have verified this hypothesis on various models of inflammation using the new mitochondria-targeted antioxidants of SkQ family, introduced by V.P. Skulachev and co-workers two decades ago. SkQ1 has been shown to accelerate the resolution of the acute inflammatory phase of dermal wounds in old or diabetic mice [1-3]. The anti-inflammatory effect of SkQ1 contributed to a marked acceleration of wound healing in these models. The suppression of acute inflammation with SkQ1 was also demonstrated in mouse models of subcutaneous air pouch [4,5] and pyelonephritis [6]. In a systemic inflammatory response syndrome (SIRS) model, SkQ1 prevented acute mortality in mice caused by intravenous injection of TNF [7,8]. Endothelium appeared to be one of the primary targets of SkQ1 in the models of acute as well as chronic inflammation. In both old and diabetic mice increased expression of the adhesion molecules (selectins, ICAM1, VCAM) in aortas was strongly suppressed by prolonged treatment with SkQ1 while elevation of the major proinflammatory cytokines TNF and IL-6 in serum was not affected [9]. The similar effect was observed in the model of SIRS [7]. In endothelial cell culture, SkQ1 attenuated TNF-induced increase in ICAM1, VCAM, and E-selectin expression and prevented neutrophil adhesion to the endothelial monolayer. Moreover, SkQ1 rescued from TNF-induced endothelial permeability, disassembly of cell contacts and VE-cadherin cleavage by the matrix metalloprotease 9 [7, 9, 10]. Both endothelial responses are critical for the extravasation of neutrophils from the blood into the inflammatory lesions in the tissues. We have demonstrated that the effects of SkQ1 in endothelial cells are mediated by a decrese in NF-κB activation due to inhibition of phosphorylation and proteolytic cleavage of the inhibitory subunit IκBα. Neutrophils are the most abundant blood leucocytes which are the main participants in the first line of inflammatory defense against invading pathogens. At the sites of infection, neutrophil protective weapons are activated, in particular phagocytosis, oxidative burst, exocytosis of various granule types (degranulation), and release of DNA-based extracellular traps (NETosis). Using SkQ1, we demonstrated that mtROS are involved in the oxidative burst caused by activation of NADPH oxidase (Nox2), as well as in the exocytosis of primary (azurophil) and secondary (specific) granules. SkQ1 also significantly accelerated apoptosis of activated neutrophils [11]. NETosis is the last suicidal resource of neutrophils in the fight against infection. NETosis plays also an important role in the pathogenesis of various autoimmune and inflammatory diseases. Using SkQ1 and specific inhibitors of NADPH oxidase, we showed that both sources of ROS are critical for NETosis induced by Ca2+ionophore A23187 in human neutrophils [12]. Interestingly in neutrophils from patients with chronic granulomatous disease (CGD) lacking Nox2, A23187-induced NETosis also was sensitive to SkQ1. We concluded that Ca2+-triggered mtROS production contributes to NETosis either directly (CGD neutrophils) or by stimulating NADPH oxidase. Our data indicate that mtROS play a critical role in signal transduction, which mediates major inflammatory responses in both endothelial and immune cells. The anti-inflammatory effect of SkQ1 probably underlies its therapeutic action in pathologies of various origin. 1. Demyanenko IA, et al. Biochemistry (Moscow) (2010) 75, 337-345. 2. Demyanenko IA, et al. Aging (2015) 7, 475-485. 3. Demyanenko IA, et al. Oxid Med Cell Longev (2017) 2017, 6408278. 4. Chelombitko MA, et al. Bull Exp Biol Med. (2017) 162, 730-733. 5. Chelombitko MA, et al. Biochemistry (Moscow) (2017) 82, 1858-1871. 6. Plotnikov EY, et al. Proc Natl Acad Sci U S A. (2013) 110, E3100-108. 7. Zakharova VV, et al. J Cell Physiol. (2017) 232, 904-912. 8. Zakharova VV, et al. Biochim Biophys Acta. (2017) 1863, 968-977 9. Zinovkin RA, et al. Aging (2014) 6, 661-674. 10. Galkin II, et al. (2016) Biochemistry (Moscow) 81, 1826-1835. 11. Vorobjeva NV, et al. Eur J Cell Biol. (2017) 96, 254-265. 12. Vorobjeva NV, et al. (2020) Biochim Biophys Acta Mol Basis Dis. (2020) 1866, 165664.