Novel protective circulating miRNA are associated with preserved vitamin D levels in patients with mild COVID-19 presentation at hospital admission not progressing into severe disease

Purpose: Low vitamin D levels were reported to negatively influence the outcomes of acute COVID-19, as well as other biochemical markers were linked to COVID-19, including microRNAs (miRNAs). This study aimed to prospectively evaluate miRNAs and vitamin D relationship in predicting COVID-19 outcomes. Methods: COVID-19 patients were part of a previously reported cohort and enrolled in a matched-ratio based on the presence/or not of severe disease at hospital admission. 25(OH) vitamin D levels and miRNAs expression were evaluated. Results: Patients affected by non-severe COVID-19 were characterized by a higher expression of miRNAs hsa-miR-3115 and hsa-miR-7151-3p, as compared to those affected by severe disease. In non-severe patients, these miRNAs were more frequently expressed in those who subsequently did not develop worsening outcomes. In addition, patients with miRNA-7151 expression and without worsening disease were characterized by higher 25(OH) vitamin D levels and lower prevalence of vitamin D deficiency. Conclusions: The expression of two novel miRNAs was reported for the first-time to be associated with a less severe COVID-19 form and to prospectively predict the occurrence of disease outcome. Furthermore, the association observed between vitamin D deficiency and lack of miRNA-7151 expression in COVID-19 patients with worse outcomes may support the hypothesis that the co-existence of these two conditions may have a strong negative prognostic role.