The association of Sirtuin1 (SIRT1) polymorphism and downregulation of STAT4 gene expression with increased susceptibility to COVID-19 infection

Sirtuin1 (SIRT1) is an epigenetic modulator that belongs to sirtuins family and participates in many physiologic reactions, as genomic stabilization, apoptosis, proliferation, and inflammation. STAT4 (signal transducer and activator of transcription 4) gene is a component of JAK-STAT signaling pathway, which plays key role in activating cellular-mediated immune responses. The present study aimed to investigate the association between SIRT1 rs12778366 SNP, expression level of STAT4 gene and susceptibility to COVID-19 infections as well as their correlation to clinicopathological data.The present study included 100 ICU patients with severe COVID-19 infection and 100 age- and sex-matched healthy controls. DNA was extracted. Genotyping of SNP in SIRT1 (rs12778366) was performed, Total RNA was extracted from PBMCs. Reverse transcription was done. STAT4 gene expression levels were evaluated with GAPDH as internal control using real-time PCR. We found a significantly higher frequency of ‘C’ allele and C/T genotype in case vs. control. The association was of low strength (φ = 0.105 for alleles, and 0.154 for genotypes). This was associated with higher expression of STAT4 gene (P < 0.001) and increased tendency for lower respiratory complications. Median STAT4 (FC) (Median = 0.18, 95% CI = 0.15–0.27) was lower than normal control value of 1.0. This difference was statistically significant (Hodges-Lehmann location estimator = 0.217, P < 0.001). SIRT1 polymorphism and decreased expression of STAT4 gene are associated with increased susceptibility to COVID-19 infection and correlate to its phenotypic manifestations.