Adipokines, Possible Biomarkers and Therapeutic Targets in Obesity and Related Pathologies

Obesity has reached epidemic proportions in Western society and is increasing in the developing world. It is considered one of the main contributors to the global burden of disability and chronic diseases, including autoimmune, inflammatory and degenerative diseases. It has notably transformed the obsolete concept that white adipose tissue (WAT) serves simply as an energy deposit. WAT is now recognized as an endocrine organ, active and inflammatory, capable of producing a wide variety of factors known as adipokines. These molecules participate in a wide variety of physiological and physiopathological processes, regulating food intake, insulin sensitivity, immunity and inflammation. Obese patients have chronic inflammation due to the sustained production of pro-inflammatory cytokines in adipose tissue and higher levels of inflammatory cytokines such as IL-6 and C-reactive protein (CRP). Also, within the subsets of adipose tissue pro-inflammatory macrophages (phenotype M1), it has been shown that they replace anti-inflammatory macrophages (phenotype M2). Adipose tissue also produces a large amount of adipokines that act as signaling molecules, with a broad range of effects on many organ systems, including the lungs. Therefore, a possible underlying physiopathological mechanism that explains the effect of obesity on the severity of SARS-CoV-2 infection may be due to anomalies in the production of adipokines by fatty tissue, contributing to the condition called a “cytokine storm”, which characterizes the severe form of COVID 19. Also, expression of the gene (SARS-CoV-2 receptor) is greater in visceral and subcutaneous adipose tissue than in lung tissue, an important target affected by SARS-CoV-2 infection. This suggests a mechanism by which excess adiposity may lead to greater severity of infection in patients with COVID-19. The production of these adipokines and pro inflammatory factors of adipose tissue, as well as its importance in the severity of COVID-19, are analyzed in this chapter, proposing these cytokines as possible markers of metabolic and immunological diseases.