Toll-Like Receptor 4 Polymorphisms (896A/G and 1196C/T) as an Indicator of COVID-19 Severity in a Convenience Sample of Egyptian Patients.

BACKGROUND: The clinical spectrum of COVID-19 is extremely variable. Thus, it is likely that the heterogeneity in the genetic make-up of the host may contribute to disease severity. Toll-like receptor (TLR)-4 plays a vital role in the innate immune response to SARS-CoV-2 infection. The susceptibility of humans to severe COVID-19 concerning TLR-4 single nucleotide polymorphisms (SNPs) has not been well examined. OBJECTIVE: The goal of this research was to investigate the association between TLR-4 (Asp299Gly and Thr399Ile) SNPs and COVID-19 severity and progression as well as the cytokine storm in Egyptian patients. METHODS: We genotyped 300 adult COVID-19 Egyptian patients for TLR-4 (Asp299Gly and Thr399Ile) SNPs using PCR-restriction fragment length polymorphism (PCR-RFLP). We also measured interleukin (IL)-6 levels by enzyme-linked immunosorbent assay (ELISA) as an indicator of the cytokine storm. RESULTS: The minor 299Gly (G) and 399Ile (T) alleles were associated with a significant (P < 0.001) positive risk of severe COVID-19 (OR = 3.14; 95% CI = 2.02-4.88 and OR = 2.75; 95% CI = 1.66-4.57), their frequency in the severe group were 71.8% (84/150) and 70.7% (58/150), respectively. We detected significant differences between TLR-4 (Asp299Gly, Thr399Ile) genotypes with regard to serum levels of IL-6. Levels of IL-6 increased significantly with the presence of the mutant 299Gly (G) and 399Ile (T) alleles to reach the highest levels in the Gly299Gly (GG) and the Ile399Ile (TT) genotypes (170 pg/mL (145-208.25) and 112 pg/mL (24-284.75), respectively). CONCLUSION: The TLR-4 (Asp299Gly and Thr399Ile) minor alleles 299Gly (G) and 399Ile (T) are associated with COVID-19 severity, mortality, and the cytokine storm.

Comparison of COVID-19 characteristics in Egyptian patients according to their Toll-Like Receptor-4 (Asp299Gly) polymorphism.

Background: Toll-like receptor (TLR)-4 plays a vital role in recognizing viral particles, activating the innate immune system, and producing pro-inflammatory cytokines. Objectives: This cross-sectional study aimed to compare COVID-19 severity, progression, and fate according to TLR-4 (Asp299Gly) polymorphism in Egyptian patients. Methods: A total of 145 COVID-19 patients were included in this study. TLR-4 (Asp299Gly) genotyping was done using the PCR restriction fragment length polymorphism (PCR-RFLP) approach. Results: The most commonly encountered TLR-4 genotype in relation to the amino acid at position 299 was the wild-type AA (73.1%); meanwhile, the homozygous mutant GG genotype (8.3%) was the least encountered. At hospital admission, 85.8% of the AA group had free (with no ground glass opacities) chest computed tomography (CT) examination, and 16.0% were asymptomatic. On the other hand, of the AG and GG groups, 81.5% and 83.3%, respectively showed bilateral ground-glass opacities in chest CT, as well as 25.9% and 75.0%, respectively were dyspneic. Values of the total leucocytic count, C-reactive protein (CRP), ferritin, and D dimer increased in the AAAG>GG sequence. ICU admission (83.3%) and in-hospital death (33.3%) rates were significantly higher in the GG group. Conclusions: In COVID-19 patients, the TLR-4 mutant G allele may be associated with a more aggressive disease course and in-hospital death. New therapeutic alternatives could be aimed at this area.