Comparative study of TNF-α and IL-10 levels at different times of the course of COVID-19

Introduction: SARS-CoV-2 infection (COVID-19) induces dysregulated production of pro- and anti-inflammatory cytokines, called the cytokine storm, leading to the development of severe pneumonia and ARDS. We aimed to examine the dynamic cytokine response on different days of the disease in adult COVID-19 patients. Methodology: Our study included 142 patients (with SARS-CoV-2 PCR-positive nasopharyngeal samples) with varying disease severity and admitted on different days of the disease. We examined the presence and mean levels of TNF-α and IL-10 and did a correlation and logistic regression analysis. Results: TNF-α levels were high in all patients, with mean levels being the highest on day 5 of the disease. IL-10 was high only in a quarter of the patients. The levels of IL-10 were also the highest on day 5, which was significantly different from the mean levels on the other days of the disease. Average IL-10 levels were not any higher than the normal range on the other days. We found a significant positive correlation between the levels of TNF-α and IL-10 during the first week of the infection. In the second week, the positive correlation was no longer significant, and starting from day 10, there was even a slight negative correlation. IL-10 level increase showed prognostic significance for severe, but not the critical forms of the disease. Conclusions: The uncontrolled immune response to SARS-CoV-2 in the second week of the disease can be the result of dysregulated production of endogenous anti-inflammatory cytokines. This leads to a severe disease course and a possible unfavorable outcome.