Analysis of serum cytokine and protective vitamin D levels in severe cases of COVID-19

In this study, we investigated the role and relationship between the cytokine profile and protective vitamin D by measuring their serum levels in COVID-19 intensive care unit patients with severe illnesses. A total of 74 patients were included in our study. Patients were divided into two groups. Patients in the COVID-19 group (n = 31) and individuals without a history of serious illness or infection were used as the control group (n = 43). The serum concentrations of interleukin-1 (IL-1), IL-6, IL-10, IL-21, and tumor necrosis factor-alpha (TNF-alpha) were measured by enzyme-linked immunosorbent assays. Levels of serum vitamin D were detected with Liquid chromatography-mass spectrometry methodologies. TNF-alpha, IL-1, IL-6, IL-10, IL-21, and vitamin D levels were measured in all patients. The serum cytokine levels in the COVID-19 patient group were significantly higher (151.59 +/- 56.50, 140.37 +/- 64.32, 249.02 +/- 62.84, 129.04 +/- 31.64, and 123.58 +/- 24.49, respectively) than control groups. Serum vitamin D was also significantly low (6.82 +/- 3.29) in patients in the COVID-19 group than the controls (21.96 +/- 5.39). Regarding the correlation of vitamin D with cytokine levels, it was significantly variable. Our study shows that COVID-19 patients are associated with lower serum vitamin D and higher pro-inflammatory cytokines associated with increased virus presence. Our data provide more evidence of the anti-inflammatory effect of vitamin D on COVID-19 patients and the protective effects of vitamin D on risk were demonstrated.