Molecular Aspects of immunomodulatory and antioxidant effects of vitamin D on prevention of COVID-19 complications

Introduction: SARS-CoV-2, the viral cause of COVID-19, leads to lethal infection with multiple organ damages. Strong data shows a definite correlation between Vitamin D (VD) serum levels and inflammatory disorders. Moreover, these nutritious compounds have antioxidant effects that can prevent organ damages due to oxidative stress. In this paper, we studied the role of VD in the prevention of COVID-19 complications due to its immunomodulatory and antioxidant effects.Description: In patients with COVID-19, Ang II/Ang (1-7) ratio is enhanced. This leads to over-activation of NADPH oxidase and NF-κB upregulation. Also, Ang II over-activation in some pathological conditions, like COVID-19, leads to the upregulation of NOX1 and NOX2 enzymes, resulting in overproducing the reactive oxygen species (ROS) molecules. Several studies shown that VD is closely linked to the T cell immune response, differentiation and activation status of B cells and the development of Natural killer cells during inflammatory responses. Moreover, production of some anti-microbial molecules such as defensins and cathelicidins is also stimulated by VD. VD also has antioxidant effects through modulating the mitochondrial activities, up-regulating of glutathione, glutathione peroxidase, superoxide dismutase, and down-regulating the NADPH oxidase.Discussion and conclusion: VD and its metabolites have immunomodulatory and anti-oxidant effects; So it might be helpful in multi-organ failure due to oxidative stress and cytokine storm induced by SARS-CoV2 in COVID-19. It seems that VD supplementation therapy, at-least in VD deficient patients, have potential protective effects against the COVID-19-induced morbidities; An issue needed to be evaluated at the next well-designed clinical trials.