Plasma Leptin Is Increased in Intensive Care Patients with COVID-19-An Investigation Performed in the PronMed-Cohort.

Anders Larsson,Mats Eriksson,Michael Hultström,Miklós Lipcsey,Robert Frithiof

doi:10.3390/biomedicines10010004

Abstract

COVID-19 has shaken the world and intensive care units (ICU) have been challenged by numerous patients suffering from a previously unknown disease. Leptin is a polypeptide pleiotropic hormone, mainly expressed by adipocytes. It acts as a proinflammatory cytokine and is associated with several conditions, known to increase the risk of severe COVID-19. Very little is known about leptin in severe viral disorders. Plasma leptin was analyzed in 222 out of 229 patients with severe COVID-19 on admission to an ICU at Uppsala University Hospital, a tertiary care hospital in Sweden, and compared to plasma leptin in 25 healthy blood donors. COVID-19 was confirmed by positive PCR. Leptin levels were significantly higher in patients with COVID-19 (18.3 ng × mL−1; IQR = 30.4), than in healthy controls (7.8 ng × mL−1; IQR = 6.4). Women had significantly higher leptin values (22.9 ng × mL−1; IQR = 29.8) than men (17.5 ng × mL−1; IQR = 29.9). Mortality at 30 days was 23% but was not associated with increased leptin levels. Neither median duration of COVID-19 before admission to ICU (10 days; IQR = 4) or median length of ICU stay (8 days; IQR = 11) correlated with the plasma leptin levels. Leptin levels in COVID-19 were higher in females than in males. Both treatment (e.g., use of corticosteroids) and prophylaxis (vaccines) have been improved since the start of the COVID-19 pandemic, which may contribute to some difficulties in deciphering relations between COVID-19 and leptin.

Highlights

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19), a pandemic responsible for more than a quarter of a billion confirmed cases, including over five million deaths as per WHO dashboard, datedLeptin is a 16-kDa non-glycosylated hormonal protein, primarily synthesized by adipocytes [12]
Factors that contribute to increased sodium reabsorption in obesity include adipokines, leptin, which may contribute to renin
We investigated plasma levels of leptin in critically ill patients with COVID-19 included in the PronMed-study, approved by the National Ethical Review Agency

Summary

Introduction

Leptin is a 16-kDa non-glycosylated hormonal protein, primarily synthesized by adipocytes [12]. Leptin is a pleiotropic hormone and a proinflammatory cytokine, influencing multiple endocrine functions, including both innate and adaptive immune responses [13]. Leptin may act as a link between obesity, metabolism, an increased inflammatory milieu, cytokine production, and a dysregulated innate immune response [14,15,16,17]. Leptin is associated with the formation of both arterial and venous thromboembolism [21,22], deterioration of kidney function, and increased morbidity and mortality in end-stage renal disease [23,24]. Factors that contribute to increased sodium reabsorption in obesity include adipokines, leptin, which may contribute to renin–

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Conclusion