Evaluation of serum levels of IL-6 and adiponectin in COVID-19 patients and their relationship with disease severity

Abstract

Background: The SARS-CoV-2 pandemic has prompted researchers around the world to identify risk factors associated with disease severity and mortality. The results suggest that the mortality of COVID-19 might be due to "cytokine storm" involving IL-6, and that obesity could be considered as a risk factor for the prevalence, severity, and mortality of COVID-19 patients. The current study aimed to evaluate the serum levels of IL-6 and adiponectin in patients and their relationship with disease progression. Methods: ELISA was used to assess the levels of IL-6 and adiponectin in serum samples of control group and patients with COVID-19 at the time of admission to the ICU or non-ICU wards. The results were analyzed using Mann-Whitney and Spearman tests. Results: ICU and non-ICU hospitalized patients had higher level of adiponectin compared to the control group (P0.001 and P=0.002, respectively). Moreover, the mean sera levels of adiponectin in patients admitted to ICU (10.18 15.4 ng /ml) was significantly higher than patients admitted to the non-ICU ward (3.14 3ng /ml, P = 0.001). Mean sera levels of IL-6 showed a similar, however the difference was not statistically significant (P= 0.18). In the ICU hospitalized patients with diabetes and hypertension, the IL-6 levels were significantly higher compared to patients without underlying disease (P = 0.01, P = 0.02, respectively). In addition, a significant direct correlation was observed between adiponectin expression and IL-6 (R = 0.2, P = 0.03). Conclusion: The results of the present study showed that the sera levels of adiponectin in COVID-19 patients with severe lung involvement were significantly higher than those with less lung involvement. This finding is of high importance mainly due to the critical role of the lung in adiponectin signaling, and as a result, adiponectin disorders may be associated with pulmonary complications in patients with COVID-19.