Vitamin D and immuno-pathology of COVID-19: many interactions but uncertain therapeutic benefits

ABSTRACT

Introduction: COVID-19 pandemic has caused huge loss of human lives and extensive socio-economic damages. The immuno-pathology of this disease is neither clearly understood nor there are effective drugs for severe cases of COVID-19. Repurposing of available drugs for the treatment of COVID-19 is imperative.

Areas Covered: This review has gathered the evidence from PubMed, Google Scholar, WHO, and other reliable websites on COVID-19 and summarized the existing knowledge of the immuno-pathology of COVID-19. We elucidated how vitamin D through its diverse actions on immune effector cells, epithelial cells, or renin-angiotensin-aldosterone system could have a modulatory role on the pathogenic mechanisms of COVID-19. The epidemiological evidence associating vitamin D deficiency with the severity and incidence of COVID-19 is also presented. However, the evidence of clinical benefit to patients of COVID-19 from randomized controlled trials with vitamin D has not come as yet.

Expert opinion: It is now established that fatality of COVID-19 is primarily determined by hyperactivation of the host’s innate immune system in response to SARS-CoV-2 invasion, and thus the research on the immuno-modulatory and other roles of vitamin D against viral infections should be pursued vigorously. This would be also useful for future pandemics caused by other novel viruses.

KEYWORDS:

• COVID-19
• cytokine
• immuno-modulation
• innate immunity
• interferon
• SARS-CoV-2
• vitamin D

Notes on contributors

AB¹, UG², SC² conceptualized the article. UG² and AB¹ wrote the paper, and SC² edited it thoroughly. SS³, SC⁴ and RVS⁵ did extensive literature survey and provided important inputs. RKR⁶ and LS⁷ provided critical comments on the content and organization of the manuscript.

REVIEW

Acknowledgements

The authors thank the management at Maharishi Markandeshwar University (Deemed to be) for their support.

Article highlights

• SARS-CoV-2 invades respiratory and other epithelial cells.

• Host’s hyperactive immune response triggers COVID-19 pathology.

• Hyperactive immune response is manifested as a ‘Cytokine Storm’.

• Renin-angiotensin-aldosterone system (RAAS) dysfunction also contributes to Covid-19 pathophysiology.

• Vitamin D modulates host’s immune response to SARS-CoV-2

• Vitamin D may correct RAAS dysfunction also in COVID-19.

• Hypovitaminosis D is associated with COVID-19 incidence and severity.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.