STAT3 eye-opener in COVID-19

Among the elevated inflammatory mediators, blood Interleukin-6 (IL-6) level is highly correlated with COVID-19 mortality and predicts the need for mechanical ventilation. IL-6 is the major activator of signal transducers and activators of transcription-3 (STAT3) during inflammatory responses. The primary objective of the study is to explore STAT3 activation in different subsets of circulating cells derived from 25 COVID-19 patients (patients) admitted to an Internal Medicine department compared to 25 healthy donors (HD). Higher percentages of classical and intermediate monocytes were observed in patients, compared to HD (respectively P<0.01 and P<0.001). The active form of STAT3, phosphorylated STAT3 (pSTAT3) was significantly higher in patients, compared to HD, both in non-classical and in intermediate monocytes (P<0.001). Low-density neutrophils (LDN) count was significantly higher in patients compared to HD (P<0.001). The pSTAT3 was significantly higher in LDN derived from patients (P<0.05). High pSTAT3 was significantly directly related to d-dimer and inversely related to vitamin D levels (P<0.01). This study gives information about STAT3 activation and the possible role of Vitamin D as a tool against COVID-19.