Association between toll-like receptor genes polymorphism (TLR2, TLR4, and TLR6) and SARS-CoV-2 infection in the West Siberian region of Russia

The presence of preceding cardiovascular disease (CVD) is an important risk factor for the severe clinical course of COVID-19. In addition, COVID-19 is often aggravated by cardiovascular complications. The relationship between COVID-19 and the cardiovascular system is very complex and has not been studied. When infected with SARS-CoV-2, the innate immune response is activated through the toll-like receptors (TLRs) family. And TLR role in the pathogenesis of cardiovascular diseases is important. The aim of the study was to conduct the comprehensive comparative analysis by assessing toll-like receptor TLR2 (rs5743708), TLR4 (rs4986790, rs4986791), TLR6 (rs5743810), TLR6 (rs5743810) gene polymorphism in COVID-19 convalescent patients to identify markers for disease susceptibility, severity of the course and development of cardiovascular complications. 260 patients with COVID-19 of varying severity degrees were examined. Groups with mild, moderate, and severe disease, groups with history of cardiovascular issues, and COVID-19 convalescent patients newly diagnosed with them were identified. Single nucleotide polymorphisms TLR2 (rs5743708), TLR4 (rs4986790, rs4986791), TLR6 (rs5743810) were analyzed by real-time PCR. Statistical was carried out by using SPSS 23.0 software. Gene allele and genotype rates were assessed by using a two-way Fisher criterion, and in cases of multiple comparisons, the Bonferroni correction. An increase of TLR2G and TLR2GG was revealed in COVID-19 patients. Heterozygosity in this position was significantly reduced in the group of patients. No differences in the frequencies of genotypes between groups with different disease severity was observed. TLR2-753 ArgArg:TLR4-299 AspGly:TLR4-399 ThrThr were decreased in patients with a combined moderate-severe vs. mild COVID-19. CVD patients with TLR4-299 AspAsp, TLR4-299 AspAsp:TLR4-399ThrThr were significantly more likely to suffer from severe COVID-19. The complex TLR4-299 AspGly:TLR4-399 ThrThr and TLR2-753 ArgArg:TLR4-299 AspGly:TLR4-399 ThrThr are associated with a milder disease course. Six complexes were identified, the frequency of which is significantly higher in COVID-19 convalescent patients with cardiovascular complications. These data confirm that the TLR polymorphism affects COVID-19 development and clinical diversity.