TLR-9 (-1237)*T/C polymorphism in russian COVID-19 patients from the chelyabinsk region

In COVID-19, the clinical outcome depends on a wide range of factors, including genetic features. Among them, TLRs, the genes encoding the receptors of innate immune system are of particular interest since they play the key role in development of innate immune response. The present study concerns the newely identified allelic variants of the TLR-9 (-1237)*T/C gene in Russian residents from the Chelyabinsk Region who had COVID-19 complicated by the bilateral viral pneumonia. Polymorphic variants of TLR-9 (-1237)*T/ C were determined by polymerase chain reaction. It was found that, among the COVID-19 patients, a TLR-9 allele (-1237 C) with higher transcriptional activity was more common than in the control group (19.421% and 11.275%, respectively, p = 0.019), and its homozygous genotype TLR-9 (-1237)*C was not detected in the comparison group. TLR-9 allele (-1237)*T in the patients with COVID-19 was less common in comparison with the control group (80.579% and 88.725%, respectively, p = 0.019). Taking into account the differences in suggested TLR-9 expression in more severe COVID-19 patients, we compared distribution of TLR-9 (-1237)*T/ С allele polymorphism in the patients with different severity of COVID-19. In the group of patients with mild form, the TLR-9 (-1237)*T/T genotype was more common as compared with patients who had more severe clinical course. The differences were significant at the trend level when compared with patients with a medium-severity disease (86.364% and 66,000%, respectively; p = 0.076).