Adrenergic Regulation of Macrophage-Mediated Innate/Inflammatory Responses in Obesity and Exercise in this Condition: Role of β2 Adrenergic Receptors

Background: The effects of exercise on the innate/inflammatory immune responses are crucially mediated by catecholamines and adrenoreceptors; and mediations in both stimulatory and anti-inflammatory responses have been attributed to them. Obesity and metabolic syndrome are included among low-grade chronic inflammatory pathologies; particularly because patients have a dysregulation of the inflammatory and stress responses, which can lead to high levels of inflammatory cytokines that induce insulin resistance, contributing to the onset or exacerbation of type 2 diabetes. Macrophages play a crucial role in this obesity-induced inflammation. Although most of the antiinflammatory effects of catecholamines are mediated by β adrenergic receptors (particularly β2), it is not known whether in altered homeostatic conditions, such as obesity and during exercise, innate/ inflammatory responses of macrophages to β2 adrenergic stimulation are similar to those in cells of healthy organisms at baseline. Objective: This review aims to emphasize that there could be possible different responses to β2 adrenergic stimulation in obesity, and exercise in this condition. Methods: A revision of the literature based on the hypothesis that obesity affects β2 adrenergic regulation of macrophage-mediated innate/inflammatory responses, as well as the effect of exercise in this context. Conclusion: The inflammatory responses mediated by β2 adrenoreceptors are different in obese individuals with altered inflammatory states at baseline compared to healthy individuals, and exercise can also interfere with these responses. Nevertheless, it is clearly necessary to develop more studies that contribute to widening the knowledge of the neuroimmune regulation process in obesity, particularly in this context.