Table 3 The energy appeal reaction
From: Energy metabolism and rheumatic diseases: from cell to organism
Known reaction | Physiological meaning in transient inflammatory episodes | Pathophysiological problem in chronic inflammatory diseases |
|---|---|---|
Fatigue | Stop of energy expenditure for brain and muscles, stop of courtship and foraging behavior | Depressive symptoms/longstanding fatigue (sickness behavior) |
Anorexia | Stop of energy expenditure for gut function | Reduced or stopped uptake of energy-rich substrates |
Malnutrition | Stop of energy expenditure for gut function | Reduced or stopped uptake of vitamins and trace elementsa |
Muscle breakdown | Stop of energy expenditure for muscles, and redirection of muscle proteins to gluconeogenesis | Cachexia |
Increased muscle relative to fat breakdown | Stop of energy expenditure for muscles, and redirection of muscle proteins to gluconeogenesis | Cachectic obesity |
Insulin (insulin-like growth factor-1) resistance in liver, muscle, and fat tissue | Redirection of glucose and free fatty acids to immune cells, which do not become insulin (insulin-like growth factor-1) resistant | Insulin resistance as part of the metabolic syndrome |
Appearance of a proinflammatory form of HDL cholesterol | Acute-phase reaction of lipid metabolism leading to higher delivery of cholesterol and other lipids to macrophages | Dyslipidemia as part of the metabolic syndrome |
Alterations of steroid hormone axes | Cytokine/leptin-driven hypoandrogenemia supports muscle breakdown and protein delivery for gluconeogenesis and support of an activated immune system (alanine, glutamine) | Cortisol-to-androgen preponderance in chronic inflammation is catabolic and gluconeogenetic |
Elevated sympathetic tone and local sympathetic nerve fiber loss, decreased parasympathetic tone | Cytokine-driven increase of sympathetic nervous system activity increases gluconeogenesis and lipolysis. The parallel loss of sympathetic nerve fibers in inflamed tissue supports local inflammation and local lipolysis | Hypertension as part of the metabolic syndrome |
Increase of body water | Cytokine-driven activation of the water retention system due to systemic water loss during inflammation | Hypertension as part of the metabolic syndrome |
Inflammation-related anemia | Stop of energy expenditure for brain and muscle activity | Anemia |
Inflammation-related provision of calcium and phosphorus | High calcium and phosphorus are mandatory for energy-consuming reactions (think of ATP) | Local and general osteopenia |