The benefits of Vitamin D in the COVID-19 pandemic: biochemical and immunological mechanisms

Abstract

In December 2019, a new infectious complication called CoronaVirus Infectious Disease-19, briefly COVID-19, caused by SARS-COV-2, is identified in Wuhan, China. It spread all over the world and became a pandemic. In many individuals who had suffered SARS-COV-2 infection, cytokine storm starts through cytokine overproduction and leads to Acute Respiratory Syndrome (ARS), organ failure, and death. According to the obtained evidence, Vitamin D (VitD) enhances the ACE2/Ang(1–7)/MasR pathway activity, and it also reduces cytokine storms and the ARS risk. Therefore, VitD intake may be beneficial for patients with SARS-COV-2 infection exposed to cytokine storm but do not suffer hypotension. In the present review, we have explained the effects of VitD on the renin-angiotensin system (RAS) function and angiotensin-converting enzyme2 (ACE2) expression. Furthermore, we have reviewed the biochemical and immunological effects of VitD on immune function in the underlying diseases and its role in the COVID-19 pandemic.

Keywords:

• Vitamin D
• ACE2
• cytokine storm
• SARS-COV-2

Acknowledgements

We thank Dr. Pejman Hakemi for his help in preparing the figures.

Ethical standards statement

The Ethics Committee of Babol University of Medical Sciences approved this study (IR.MUBABOL.REC.1399.161).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to governmental policy and privacy.

Figure 1. The virus may enter cells by binding to the ACE2 receptor. The appropriate viral performance depends on the receptor expression and its distribution. The virus can infiltrate the body through the nose and mouth and eventually via the lungs' airways. Alveolar type II (AECII) epithelial cells comprise about 83% of the cells expressing ACE2. Besides the lungs (Zhang et al. 2020b), ACE2 is also available in intestinal epithelial cells through the lumen's surface, and the gut can be another route for the virus to enter the body (Pan et al. 2020, Young et al. 2020). The entered virus infects providers' ACE2 organs, including the heart, kidneys, brain, liver, and pancreas (Chai et al. 2020, Huang et al. 2020a, Walls et al. 2020, Zhang et al. 2020a, Wadman et al. 2020).

Figure 2. The binding of SARS-COV-2 to receptors and its entrance into cells depends on a cellular protease; subsequently, the virus involves the angiotensin-convertase enzyme 2 (ACE2) and cellular TMPRSS2 serine protease for protein S priming. After protease action, SARS / ACE2 binding starts; the ACE2 operation is the primary determinant of SARS-COV-2 transmission (Hoffmann et al. 2020). Macrophages and dendritic cells process viral antigens and deliver them to CD4+ and CD8+ T cells. Activation of T cells causes their cytolytic and pre-inflammatory effects on infected tissues (Meftahi et al. 2020).

Figure 3. The relationship between VitD, ACE2, and SARS-COV2 (Cui et al. 2019, Hanff et al. 2020, Gombart et al. 2020).