Leptin in the Respiratory Tract: Is There a Role in SARS-CoV-2 Infection?

Abstract

Leptin is a pleiotropic adipocytokine involved in several physiologic functions, with a known role in innate and adaptive immunity as well as in tissue homeostasis. Long- and short-isoforms of leptin receptors are widely expressed in many peripheral tissues and organs, such as the respiratory tract. Similar to leptin, microbiota affects the immune system and may interfere with lung health through the bidirectional crosstalk called the “gut-lung axis.” Obesity leads to impaired protective immunity and altered susceptibility to pulmonary infections, as those by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although it is known that leptin and microbiota link metabolism and lung health, their role within the SARS-CoV2 coronavirus disease 2019 (COVID-19) deserves further investigations. This review aimed to summarize the available evidence about: (i) the role of leptin in immune modulation; (ii) the role of gut microbiota within the gut-lung axis in modulating leptin sensitivity; and (iii) the role of leptin in the pathophysiology of COVID-19.

COVID-19 and Pregnancy: A Dangerous Mix for Bone Turnover and Metabolism Biomarkers in Placenta and Colostrum

“…In addition, leptin regulates bronchial diameter by counteracting the parasympathetic effect on the airways [33]. It is also important for immune system development and function because leptin-deficient subjects show increased risk of death due to infections [34]. Low leptin production is linked with the pathogenesis of several pulmonary diseases and pulmonary arterial hypertension.…”

Serum biomarkers for nutritional status as predictors in COVID-19 patients before and after vaccination

“…The IGF-1 is altered in liver disease, renal impairment and severe trauma such as burns ( Keller, 2019 ). Leptin also functions as a cytokine, coordinating the host innate and adaptive Th1-mediated immune responses ( Bruno et al, 2021 ), and has also been associated with inflammation and is modulated by gut microbiota, linking metabolism and lung health ( Bruno et al, 2021 , Heiss and Olofsson, 2018 ). Nefastin-1 participates in the redox balance, interplays with the gut microbiota, and alters the structure of the intestinal barrier with possible implications in anti-inflammatory and anti-apoptotic effects ( Kras et al, 2022 ).…”

Noncommunicable diseases risk factors and the risk of COVID-19 among university employees in Indonesia

“…Leptin is the link between metabolic and immunity responses involving T-cell activation upon an acute respiratory viral infection, including SARS-CoV-2. In obesity, there is a large dysregulation of endocrine and inflammatory events leading to an inadequate immune response to acute SARS-CoV-2 infection [ 28 , 29 ].…”