Investigation of the Toll-like receptors expression profile in peripheral blood mononuclear cells in COVID-19 patients in Iran

Background: Coronavirus disease2019 (COVID-19) spread all around the world and leads to many new infection cases and mortality. A better understanding of the SARS-CoV-2 pathogenesis could lead to more efficient therapeutic approaches. The current study aimed to investigate the Toll-like receptors expression profile in peripheral blood mononuclear cells in COVID-19 patients in Iran. Materials and methods: In this cross-sectional study, we evaluate 32 patients. At the admission time based on the disease severity patients were divided into two groups severe and mild COVID-19. A group of 16 normal people was evaluated as the control. Blood samples were collected before any treatment from patients at the admission time. The Blood samples were used for PBMC isolation. RNA extracted from PBMCs and use for the cDNA synthesis. The expression level of TLR-3, 4, and 7 were evaluated by using semi-quantitative real-time PCR. Results: The patient's mean age was 57.12±3.08 years and 15 (47%) were male. The background disorders represent two patients in the severe group with respiratory disorders, 4 patients with cardiovascular disease, and seven patients with diabetes. The TLRs expression levels represent a higher expression of TLR-4 in COVID-19 in comparison with controls for TLR-4 (p=0.00), TLR-3 and 7 also represent up-regulation but there were no statistically significant differences in the relative fold changes (RFC) between groups for all other evaluated TLRs (p>0.05). Conclusion: The study highlights the importance of the TLR-4 in COVID-19 patients in expression level. Further studies for a clear conclusion about TLRs expression levels are recommended.