Obesity as an adipose tissue dysfunction disease and a risk factor for infections - Covid-19 as a case study

Abstract

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV2) disease (COVID-19) is a novel threat that hampers life expectancy especially in obese individuals. Though this association is clinically relevant, the underlying mechanisms are not fully elucidated. SARS CoV2 enters host cells via the Angiotensin Converting Enzyme 2 receptor, that is also expressed in adipose tissue. Moreover, adipose tissue is also a source of many proinflammatory mediators and adipokines that might enhance the characteristic COVID-19 cytokine storm due to a chronic low-grade inflammatory preconditioning. Further obesity-dependent thoracic mechanical constraints may also incise negatively into the prognosis of obese subjects with COVID-19. This review summarizes the current body of knowledge on the obesity-dependent circumstances triggering an increased risk for COVID-19 severity, and their clinical relevance.

Keywords: ARDS; Adipokines; Adiponectin; Bariatric surgery; COVID-19; Cytokine storm; Diabetes mellitus; Hypertension; Leptin; Mortality; Obesity; SARS-CoV-2.

Fig. 1

Severe COVID-19 obesity tetrad. Obesity entails an increased proinflammatory, prothrombotic state associated with a hormonal rearrangement in a context of decreased cardio-respiratory fitness and limited respiratory capacity. IL6: interleukin 6; IL8: interleukin 8; TNFα: tumor necrosis factor α; Ang II: angiotensin II; vWF: von Willebrand Factor; FVIII: coagulation-cascade factor VIII; NET: Neutrophil extracellular trap; TF: tissue factor.

Fig. 2

COVID-19 clinical course. ARDS: acute respiratory distress syndrome.

Fig. 3

Putative COVID-19 impact on health of people living with obesity.

Fig. 4

Flow diagram of the search strategy.