The regulation of efferocytosis signaling pathways and adipose tissue homeostasis in physiological conditions and obesity: Current understanding and treatment options

Abstract

Obesity is associated with changes in the resolution of acute inflammation that contribute to the clinical complications. The exact mechanisms underlying unresolved inflammation in obesity are not fully understood. Adipocyte death leads to pro-inflammatory adipose tissue macrophages, stimulating additional adipocyte apoptosis. Thus, a complex and tightly regulated process to inhibit inflammation and maintain homeostasis after adipocyte apoptosis is needed to maintain health. In normal condition, a specialized phagocytic process (efferocytosis) performs this function, clearing necrotic and apoptotic cells (ACs) and controlling inflammation. For efficient and continued efferocytosis, phagocytes must internalize multiple ACs in physiological conditions and handle the excess metabolic burden in adipose tissue. In obesity, this control is lost and can be an important hallmark of the disease. In this regard, the deficiency of efferocytosis leads to delayed resolution of acute inflammation and can result in ongoing inflammation, immune system dysfunction, and insulin resistance in obesity. Hence, efficient clearance of ACs by M2 macrophages could limit long-term inflammation and ensue clinical complications, such as cardiovascular disease and diabetes. This review elaborates upon the molecular mechanisms to identify efferocytosis regulators in obesity, and the mechanisms that can improve efferocytosis and reduce obesity-related complications, such as the use of pharmacological agents and regular exercise.