Publication Date:
2020
Description:
〈p〉Publication date: 1 May 2020〈/p〉
〈p〉〈b〉Source:〈/b〉 Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, Volume 1866, Issue 5〈/p〉
〈p〉Author(s): Nina Vorobjeva, Ivan Galkin, Olga Pletjushkina, Sergei Golyshev, Roman Zinovkin, Anastasia Prikhodko, Vladimir Pinegin, Irina Kondratenko, Boris Pinegin, Boris Chernyak〈/p〉
〈div xml:lang="en"〉
〈h5〉Abstract〈/h5〉
〈div〉
〈p〉Neutrophils release neutrophil extracellular traps (NETs) in response to numerous pathogenic microbes as the last suicidal resource (NETosis) in the fight against infection. Apart from the host defense function, NETs play an essential role in the pathogenesis of various autoimmune and inflammatory diseases. Therefore, understanding the molecular mechanisms of NETosis is important for regulating aberrant NET release. The initiation of NETosis after the recognition of pathogens by specific receptors is mediated by an increase in intracellular Ca〈sup〉2+〈/sup〉 concentration, therefore, the use of Ca〈sup〉2+〈/sup〉 ionophore A23187 can be considered a semi-physiological model of NETosis. Induction of NETosis by various stimuli depends on reactive oxygen species (ROS) produced by NADPH oxidase, however, NETosis induced by Ca〈sup〉2+〈/sup〉 ionophores was suggested to be mediated by ROS produced in mitochondria (mtROS).〈/p〉
〈p〉Using the mitochondria-targeted antioxidant SkQ1 and specific inhibitors of NADPH oxidase, we showed that both sources of ROS, mitochondria and NADPH oxidase, are involved in NETosis induced by A23187 in human neutrophils. In support of the critical role of mtROS, SkQ1-sensitive NETosis was demonstrated to be induced by A23187 in neutrophils from patients with chronic granulomatous disease (CGD). We assume that Ca〈sup〉2+〈/sup〉-triggered mtROS production contributes to NETosis either directly (CGD neutrophils) or by stimulating NADPH oxidase. The opening of the mitochondrial permeability transition pore (mPTP) in neutrophils treated by A23187 was revealed using the electron transmission microscopy as a swelling of the mitochondrial matrix. Using specific inhibitors, we demonstrated that the mPTP is involved in mtROS production, NETosis, and the oxidative burst induced by A23187.〈/p〉
〈/div〉
〈/div〉
〈div xml:lang="en"〉
〈h5〉Graphical abstract〈/h5〉
〈div〉
〈p〉Schematic representation of the mechanisms of chromatin release from neutrophil nuclei (〈strong〉N〈/strong〉) called neutrophil extracellular traps (〈strong〉NETs〈/strong〉) formation activated by various inducers, particularly by calcium ionophores. In the scheme, calcium ionophore 〈strong〉A23187〈/strong〉 mobilizes Ca〈sup〉2+〈/sup〉 from the endoplasmic reticulum (〈strong〉ER〈/strong〉) resulting in the opening of store-operated Ca〈sup〉2+〈/sup〉 channels and a sustained increase in cytosolic Ca〈sup〉2+〈/sup〉 concentration. Subsequently, Ca〈sup〉2+〈/sup〉 accumulates in the mitochondrial matrix due to the membrane potential, and this stimulates the opening of large nonspecific mitochondrial permeability transition pore (〈strong〉mPTP〈/strong〉). The opening of mPTP is a powerful stimulus for the mitochondrial ROS (〈strong〉mtROS〈/strong〉) production, while the resulting oxidative stress, in turn, facilitates mPTP opening. Subsequently, mtROS leave mitochondrial matrix for the cytoplasm, where they activate NADPH oxidase (NOX2), presumably, via activation of protein kinase C (〈strong〉PKC〈/strong〉). PKC can be activated by 〈em〉N〈/em〉-Formyl-methionyl-leucyl-phenylalanine (〈strong〉fMLP〈/strong〉) via receptor-mediated phospholipase C (PLC)-dependent formation of diacylglycerol (DAG) and inositol trisphosphate (〈strong〉IP3〈/strong〉) or directly by phorbol 12-myristate 13-acetate (〈strong〉PMA〈/strong〉). mPTP-dependent production of mtROS is involved in NOX2 activation induced by fMLP but not by PMA. In our study using the mitochondria-targeted antioxidant 〈strong〉SkQ1〈/strong〉 and specific inhibitors, we demonstrated that NETs formation induced by calcium ionophore A23187 depends on mPTP opening and on mtROS production.〈/p〉
〈p〉Inhibitors of NOX2: 〈strong〉apocynin〈/strong〉, 〈strong〉VAS2870〈/strong〉;〈/p〉
〈p〉Inhibitors of mPTP: 〈strong〉CsA〈/strong〉, cyclosporin A; 〈strong〉MeVal4CsA〈/strong〉, analog of CsA; 〈strong〉SfA〈/strong〉, sanglifehrin A; 〈strong〉BKA〈/strong〉, bongkrekic acid.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092544392030003X-ga1.jpg" width="280" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉
〈/div〉
〈/div〉
Print ISSN:
0925-4439
Electronic ISSN:
1879-260X
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Physics
Permalink