TY - JOUR T1 - Evidences for a protective role of vitamin D in COVID-19 JF - RMD Open JO - RMD Open DO - 10.1136/rmdopen-2020-001454 VL - 6 IS - 3 SP - e001454 AU - Maurizio Cutolo AU - Sabrina Paolino AU - Vanessa Smith Y1 - 2020/12/01 UR - http://rmdopen.bmj.com/content/6/3/e001454.abstract N2 - Vitamin D and COVID-19A growing number of concordant reports support a protective role for vitamin D in reducing at least the risk/severity of respiratory tract infections (RTIs), especially in the influenza and COVID-19 context.1–5Major clinical reports show that vitamin D deficiency contribute to acute respiratory distress syndrome (ARDS) SARS-CoV-2 and that case-fatality rates increase with age and the highest SARS-CoV-2 serum concentrations.6 7In addition, the outbreak of COVID-19 seems to occur mainly in the cold winter time, when serum 25-hydroxyvitamin D (25(OH)D—calcidiol or calcifediol) concentrations are the lowest, as well as the ultraviolet B (UVB) doses, whereas the number of cases in the Southern Hemisphere near the end of summer are lower.8-Targeted 25(OH)D serum concentration measurements and vitamin D supplementation is strongly suggested have important patient and public health benefits.9 The positive role of vitamin D replacement therapy (vDRT) in reducing risk and severity in COVID-19 patients is supported by several clinical evidences and RCTs are undergoing, however, previous experiences of RCT related to vDRT are available from other lung viral infection studies and even in mechanically ventilated adult intensive care unit (ICU) patients.10–14These important observations are corroborated by several biological/molecular mechanisms through vitamin D can generally reduce risk of infections and downregulate the immune/inflammatory reaction. Indeed, functional vitamin D receptors (VDR) are highly-expressed in B-lymphocytes and T-lymphocytes and mainly in monocytes/macrophages, justifying a role in modulating both innate and adaptive immune responses15–18 (figure 1).Figure 1 Proposed mechanism whereby 1,25(OH) D -VDR (D-hormone) signalling acts on the respiratory system during the COVID-19 infection. 1,25(OH) D, 1,25-hydroxyvitamin D; ARTI, acute respiratory tract infection; IFN-gamma, inteferon gamma; IL-6, inteleukin 6; IL10, interleukin; IL -12, interleukin 12; IL-17, interleukin 17; Treg, T regulatory cells; TNF, tumour necrosis factor; UV, ultraviolet; VDR, vitamin D receptor.We … ER -