Impact of the MCP-1-2518A>G polymorphism on COVID-19 severity in the Iranian population: A case-control study

As a result of SARS-CoV-2 infection, the host's immune system is disrupted, and chemokines and cytokines are intensified to eliminate the virus, resulting in cytokine storm syndrome and acute respiratory distress syndrome (ARDS). Patients with COVID-19 have been observed to have elevated levels of MCP-1, a chemokine associated with the severity of the disease. In some diseases, polymorphisms in the regulatory region of the MCP-1 gene correspond to serum levels and disease severity. An attempt was made in this study to assess the relationship between MCP-1 G-2518A and serum MCP-1 levels in Iranian COVID-19 patients and the severity of the disease. In this study, patients were randomly sampled from outpatients on the first day of diagnosis and from inpatients on the first day of their hospitalization. Patients were classified into the outpatient (without symptoms or with mild symptoms) and inpatient (with moderate, severe, and critical symptoms) groups. The serum level of MCP-1 was measured by ELISA and the frequency of MCP-1 G-2518A gene polymorphism genotypes in COVID-19 patients was checked by the RFLP-PCR method. Participants with COVID-19 infection had a higher rate of underlying diseases, such as diabetes, high blood pressure, kidney disease, and cardiovascular disease than the control group (P-value < 0.001). Also, the frequency of these factors in inpatients was significantly higher compared to outpatients (P-value < 0.001). Additionally, the level of MCP-1 in serum was significantly different with an average of 11.90 in comparison to 2.98 in the control group (P-value, 0.05), which is attributed to elevated serum levels among patients in hospitals with an average of 11.72 in comparison to 2.98 in the control group. Compared with outpatients, inpatients had a higher frequency of the G allele of the MCP-1-2518 polymorphism (P-value < 0.05), while a notable difference was observed in the serum level of MCP-1 in COVID-19 patients with the MCP-1-2518 AA genotype in the whole group in comparison to the control group (P-value: 0.024). Totally, the results showed that a high frequency of the G allele is related to hospitalization and poor outcome in COVID-19 cases.