Regulation of energy balance by inflammation: Common theme in physiology and pathology

Abstract

Inflammation regulates energy metabolism in both physiological and pathological conditions. Pro-inflammatory cytokines involves in energy regulation in several conditions, such as obesity, aging (calorie restriction), sports (exercise), and cancer (cachexia). Here, we introduce a view of integrative physiology to understand pro-inflammatory cytokines in the control of energy expenditure. In obesity, chronic inflammation is derived from energy surplus that induces adipose tissue expansion and adipose tissue hypoxia. In addition to the detrimental effect on insulin sensitivity, pro-inflammatory cytokines also stimulate energy expenditure and facilitate adipose tissue remodeling. In caloric restriction (CR), inflammatory status is decreased by low energy intake that less energy supply to immune cells, which favors energy saving in the body under caloric restriction. During physical exercise, inflammatory status is elevated due to muscle production of pro-inflammatory cytokines, which promote fatty acid mobilization from adipose tissue to meet the muscle energy demand. In cancer cachexia, chronic inflammation is elevated by the immune response in the fight against cancer. The energy expenditure from chronic inflammation contributes to weight loss. Immune tolerant cancer cells gains more nutrients during the inflammation. In these conditions, inflammation coordinates energy distribution and energy demand between tissues. If the body lacks response to the pro-inflammatory cytokines (Inflammation Resistance), the energy metabolism will be impaired leading to an increased risk for obesity. In contrast, super-induction of the inflammation activity leads to weight loss and malnutrition in cancer cachexia. In summary, inflammation is a critical component in the maintenance of energy balance in the body. Literature is reviewed in above fields to support this view.

Intracellular ATP in balance of pro- and anti-inflammatory cytokines in adipose tissue with and without tissue expansion

“…In addition, more evidence supports that the adipose inflammation has favorite activities in the regulation of metabolism, such as induction of energy expenditure and stimulation of adipose tissue remodeling in obesity 4–6 . The beneficial activities are further supported by the report that inflammation is required for adipose tissue growth and function in several transgenic models 7 , which represents a new support to the “positive effect” of adipose inflammation 8 . There is an ongoing debate on the beneficial and detrimental effects of adipose inflammation.…”

“…The resting metabolic rate is decreased by fasting and calorie restriction 8 . The decrease correlates to the reduction in pro- and anti-inflammatory cytokines in this study, which suggests a role of energy supply in the control of the gene expression.…”

Racial discrimination predicts greater systemic inflammation in pregnant African American women

“…The rationale for these covariates is that low levels of education were related to experiences of racial discrimination; and unemployment was related to IL-4. Smoking and BMI were included since smoking and obesity have each been related to higher levels of inflammation (Gonçalves et al, 2011; Wang & Ye, 2015). Gestational age at data collection was included in the analysis given limited data suggesting that IL-6 and IL-10 increase across pregnancy (Christian & Porter, 2014; Coussons-Read, Okun, & Nettles, 2007).…”

Malnutrition Risk in Hemodialysis Patients in Israel: Results of the Status of Nutrition In Hemodialysis Patients Survey Study

“…Other factors contributing to increased energy expenditure in HD patients include persistent inflammation, which simultaneously increases energy expenditure and reduces serum albumin synthesis and half-life, reducing plasma protein levels [6][7][8], a variety of hormonal disruptions including deficient testosterone production in both women and men [9], low triidothyroid levels [10], and insulin and growth hormone resistance [11]. Acidosis, a common metabolic derangement in HD patients, accelerates protein degradation and inhibits protein synthesis [12].…”