ИСТИНА

Neutrophils and endothelium cells are essential components of innate immunity and readily activated by both pathogenic stimuli and damage-associated molecular patterns (DAMPs) derived from damaged cells. Mitochondrial debris components (MTD) including mitochondrial DNA (mtDNA) were recently shown to belong to DAMPs [1]. At the present time there are contradictory reports concerning details of DNA-induced activation of neutrophils and endothelial cells. Some researchers report that pure DNA alone may directly activate these cells, while others use Lipofectamine for endothelial cells in order to deliver DNA to endosomal compartments containing TLR9 [2][3]. In our hands highly purified mtDNA from human endothelial cell line EA.hy926 was unable to increase p38 MAPK phosphorylation or MMP9 activity of human neutrophils that contradicted results of C. Hauser [1]. We argue that standard mtDNA purification procedure using a commercially available kit may result in mtDNA impurity causing activation of neutrophils. Similar results were obtained with endothelial cells where ICAM1 mRNA expression level was nearly the same after mtDNA treatment. However, the cells were readily activated by mtDNA complexed with Lipofectamine. At the same time we confirmed that MTD activate human neutrophils. We also applied mitochondrial-targeted antioxidant (SkQ1) to prevent neutrophils activation by MTD. We showed that SkQ1 treatment decreases the level of MAPK p38 phosphorylation in response to mitochondrial components. However, MMP9 activity and neutrophils chemotaxis were not significantly affected.