Are adipokines the missing link between obesity, immune response, and outcomes in severe COVID-19?

Abstract

Introduction: Obesity is commonly reported in COVID-19 patients and is associated with poorer outcomes. It is suggested that leptin could be the missing link between obesity and severe COVID-19. Our study aimed to unravel the link between adipokines, COVID-19 status, immune response, and outcomes in severe pneumonia.

Methods: In this prospective observational single-center study, 63 immunocompetent patients with severe pneumonia (36 non-COVID-19 and 27 COVID-19) were enrolled, most required intensive care. Clinical and biological characteristics (glucose metabolism, plasma adipokines, and cytokine concentrations) and outcomes were compared.

Results: At similar baseline severity, COVID-19 patients required mechanical ventilation for significantly longer than non-COVID-19 patients (p = 0.0049). Plasma concentrations of leptin and adiponectin were respectively positively and negatively correlated with BMI and glucose metabolism (glycemia and insulinemia), but not significantly different between the two groups. Leptin levels were negatively correlated with IL-1β and IL-6, but the adipokines were not correlated with most other inflammatory mediators, baseline severity (SOFA score), or the duration of mechanical ventilation.

Conclusion: Adipokine levels were correlated with BMI but not with most inflammatory mediators, severity, or outcomes in severe pneumonia, regardless of the origin. The link between obesity, dysregulated immune response, and life-threatening COVID-19 requires further investigation.

Clinical trial: ClinicalTrials.gov: NCT03505281.

Fig. 1. Correlations between adipokines, body mass index, clinical severity and outcome, glucose metabolism, and plasma cytokine concentrations.

Scatterplot depicting correlations between body mass index (BMI) and plasma concentrations of leptin (A) or adiponectin (B). (C) Heatmap of the Spearman correlation (r) between adipokines, BMI, clinical severity and outcome, glucose metabolism, and plasma cytokine concentrations. Spearman correlations: *p < 0.05; **p < 0.01; ***p < 0.001 between each cytokine (our outcome) and ELF concentration of SARS-CoV-2 (LYMPHONIE study, 2018–2020).