Interleukin-6 Expression by Hypothalamic Microglia in Multiple Inflammatory Contexts: A Systematic Review

Author(s)

Bobbo, Vanessa C. D. ^{[1, 2]} ; Jara, Carlos P. ^{[1, 2]} ; Mendes, Natalia F. ^{[1, 2]} ; Morari, Joseane ^[2] ; Velloso, Licio A. ^[2] ; Araujo, Eliana P. ^{[1, 2]}

Affiliation

^[1] Univ Estadual Campinas, Fac Nursing, BR-13083887 Campinas, SP - Brazil

^[2] Univ Estadual Campinas, Obes & Comorbid Res Ctr, Lab Cell Signaling, BR-13083864 Campinas, SP - Brazil

• Document type: Review article
• Source: BIOMED RESEARCH INTERNATIONAL; v. 2019, AUG 22 2019.
• Web of Science Citations: 0

Abstract

Interleukin-6 (IL-6) is a unique cytokine that can play both pro- and anti-inflammatory roles depending on the anatomical site and conditions under which it has been induced. Specific neurons of the hypothalamus provide important signals to control food intake and energy expenditure. In individuals with obesity, a microglia-dependent inflammatory response damages the neural circuits responsible for maintaining whole-body energy homeostasis, resulting in a positive energy balance. However, little is known about the role of IL-6 in the regulation of hypothalamic microglia. In this systematic review, we asked what types of conditions and stimuli could modulate microglial IL-6 expression in murine model. We searched the PubMed and Web of Science databases and analyzed 13 articles that evaluated diverse contexts and study models focused on IL-6 expression and microglia activation, including the effects of stress, hypoxia, infection, neonatal overfeeding and nicotine exposure, lipopolysaccharide stimulus, hormones, exercise protocols, and aging. The results presented in this review emphasized the role of injury-like stimuli, under which IL-6 acts as a proinflammatory cytokine, concomitant with marked microglial activation, which drive hypothalamic neuroinflammation. Emerging evidence indicates an important correlation of basal IL-6 levels and microglial function with the maintenance of hypothalamic homeostasis. Advances in our understanding of these different contexts will lead to the development of more specific pharmacological approaches for the management of acute and chronic conditions, like obesity and metabolic diseases, without disturbing the homeostatic functions of IL-6 and microglia in the hypothalamus. (AU)

• FAPESP's process: 13/07607-8 - OCRC - Obesity and Comorbidities Research Center
• Grantee: Licio Augusto Velloso
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC