bims-noxint 2021-10-24 papers

Issue of 2021–10–24
three papers selected by
Laia Caja Puigsubira, Uppsala University

J Clin Med. 2021 Oct 19. pii: 4791. [Epub ahead of print]10(20):

Oxidative Stress Induced by Reactive Oxygen Species (ROS) and NADPH Oxidase 4 (NOX4) in the Pathogenesis of the Fibrotic Process in Systemic Sclerosis: A Promising Therapeutic Target.

Sonsoles Piera-Velazquez, Sergio A Jimenez.

Numerous clinical and research investigations conducted during the last two decades have implicated excessive oxidative stress caused by high levels of reactive oxygen species (ROS) in the development of the severe and frequently progressive fibrotic process in Systemic Sclerosis (SSc). The role of excessive oxidative stress in SSc pathogenesis has been supported by the demonstration of increased levels of numerous biomarkers, indicative of cellular and molecular oxidative damage in serum, plasma, and other biological fluids from SSc patients, and by the demonstration of elevated production of ROS by various cell types involved in the SSc fibrotic process. However, the precise mechanisms mediating oxidative stress development in SSc and its pathogenetic effects have not been fully elucidated. The participation of the NADPH oxidase NOX4, has been suggested and experimentally supported by the demonstration that SSc dermal fibroblasts display constitutively increased NOX4 expression and that reduction or abrogation of NOX4 effects decreased ROS production and the expression of genes encoding fibrotic proteins. Furthermore, NOX4-stimulated ROS production may be involved in the development of certain endothelial and vascular abnormalities and may even participate in the generation of SSc-specific autoantibodies. Collectively, these observations suggest NOX4 as a novel therapeutic target for SSc.

Keywords: NADPH; NOX4; fibrosis; oxidative stress; reactive oxygen species; systemic sclerosis

DOI: https://doi.org/10.3390/jcm10204791

Redox Biol. 2021 Oct 14. pii: S2213-2317(21)00326-8. [Epub ahead of print]47 102166

Cooperation between CYB5R3 and NOX4 via coenzyme Q mitigates endothelial inflammation.

Shuai Yuan, Scott A Hahn, Megan P Miller, Subramaniam Sanker, Michael J Calderon, Mara Sullivan, Atinuke M Dosunmu-Ogunbi, Marco Fazzari, Yao Li, Michael Reynolds, Katherine C Wood, Claudette M St Croix, Donna Stolz, Eugenia Cifuentes-Pagano, Placido Navas, Sruti Shiva, Francisco J Schopfer, Patrick J Pagano, Adam C Straub.

NADPH oxidase 4 (NOX4) regulates endothelial inflammation by producing hydrogen peroxide (H2O2) and to a lesser extent O2•-. The ratio of NOX4-derived H2O2 and O2•- can be altered by coenzyme Q (CoQ) mimics. Therefore, we hypothesize that cytochrome b5 reductase 3 (CYB5R3), a CoQ reductase abundant in vascular endothelial cells, regulates inflammatory activation. To examine endothelial CYB5R3 in vivo, we created tamoxifen-inducible endothelium-specific Cyb5r3 knockout mice (R3 KO). Radiotelemetry measurements of systolic blood pressure showed systemic hypotension in lipopolysaccharides (LPS) challenged mice, which was exacerbated in R3 KO mice. Meanwhile, LPS treatment caused greater endothelial dysfunction in R3 KO mice, evaluated by acetylcholine-induced vasodilation in the isolated aorta, accompanied by elevated mRNA expression of vascular adhesion molecule 1 (Vcam-1). Similarly, in cultured human aortic endothelial cells (HAEC), LPS and tumor necrosis factor α (TNF-α) induced VCAM-1 protein expression was enhanced by Cyb5r3 siRNA, which was ablated by silencing the Nox4 gene simultaneously. Moreover, super-resolution confocal microscopy indicated mitochondrial co-localization of CYB5R3 and NOX4 in HAECs. APEX2-based electron microscopy and proximity biotinylation also demonstrated CYB5R3's localization on the mitochondrial outer membrane and its interaction with NOX4, which was further confirmed by the proximity ligation assay. Notably, Cyb5r3 knockdown HAECs showed less total H2O2 but more mitochondrial O2•-. Using inactive or non-membrane bound active CYB5R3, we found that CYB5R3 activity and membrane translocation are needed for optimal generation of H2O2 by NOX4. Lastly, cells lacking the CoQ synthesizing enzyme COQ6 showed decreased NOX4-derived H2O2, indicating a requirement for endogenous CoQ in NOX4 activity. In conclusion, CYB5R3 mitigates endothelial inflammatory activation by assisting in NOX4-dependent H2O2 generation via CoQ.

Keywords: CYB5R3; CoQ; Inflammation; NOX4; ROS

DOI: https://doi.org/10.1016/j.redox.2021.102166

Front Med (Lausanne). 2021 ;8 732528

Crosstalk Between SMPDL3b and NADPH Oxidases Mediates Radiation-Induced Damage of Renal Podocytes.

Patrick Azzam, Marina Francis, Tarek Youssef, Manal Mroueh, Alaa Abou Daher, Assaad A Eid, Alessia Fornoni, Brian Marples, Youssef H Zeidan.

Patients undergoing radiotherapy (RT) for various tumors localized in the abdomen or pelvis often suffer from radiation nephrotoxicity as collateral damage. Renal podocytes are vulnerable targets for ionizing radiation and contribute to radiation-induced nephropathies. Our prior work previously highlighted the importance of the lipid-modifying enzyme sphingomyelinase acid phosphodiesterase like 3b (SMPDL3b) in modulating the radiation response in podocytes and glomerular endothelial cells. Hereby, we investigated the interplay between SMPDL3b and oxidative stress in mediating radiation injury in podocytes. We demonstrated that the overexpression of SMPDL3b in cultured podocytes (OE) reduced superoxide anion generation and NADPH oxidase activity compared to wild-type cells (WT) post-irradiation. Furthermore, OE podocytes showed downregulated levels of NOX1 and NOX4 after RT. On the other hand, treatment with the NOX inhibitor GKT improved WTs' survival post-RT and restored SMPDL3b to basal levels. in vivo, the administration of GKT restored glomerular morphology and decreased proteinuria in 26-weeks irradiated mice. Taken together, these results suggest a novel role for NOX-derived reactive oxygen species (ROS) upstream of SMPDL3b in modulating the response of renal podocytes to radiation.

Keywords: NADPH oxidases (NOX); ionizing radiation (IR); nephropathies; podocytes (MeSH: D050199); reactive oxygen species (ROS); smpdl3b; sphingolipids (SLs)

DOI: https://doi.org/10.3389/fmed.2021.732528