Investigating the Relationship between the Levels of IL18, RANKL Gene Expression, MicroRNA-146a and Inflammatory Factors with the Severity of COVID-19

Abstract

COVID-19 can induce lung inflammation, and inflammatory factors play an essential role in its pathogenesis. This inflammation can be controlled to a great extent by microRNAs (miRs). This study evaluated miR-146a-5p expression levels in the serum of patients with COVID-19 and their association with the expression of interleukin (IL)-18 and receptor activator of nuclear factor kappa-Β ligand (RANKL) genes, and lung damage. Eighty-Five patients with COVID-19 were divided into two groups: mild and severe phases. The severe phase is defined as having a positive polymerase chain reaction (PCR) for SARS-CoV2, and acute pulmonary symptoms. The subjects' demographic, clinical, and paraclinical characteristics were collected according to a pre-prepared checklist. Total RNA was isolated from all samples using the Trizol kit to assess gene expression. The extracted product was then evaluated for the expression of miR-146a and the target genes (i.e., IL-18 and RANKL) using real-time PCR. The miR-146a gene's mean expression in mild and severe patients was 0.73 and 1.89, respectively, and this difference was statistically significant between the two groups. Also, the mean Expression of the IL-18 gene, 1.37±0.38 in the mild and 2.83±0.58 in the severe groups of the disease, demonstrated a significant difference between the two groups. In contrast, the expression levels of the RANKL gene did not show a significant difference between the two groups. Therefore, it may be hypothesized that altered levels of miR-146a may contribute to the severe COVID-19 that is more commonly observed in smokers, but further research is required.