Energy metabolism of the immune system : Consequences in chronic inflammation

Abstract

Energy is the currency of life. The systemic and intracellular energy metabolism plays an essential role for the energy supply of the resting and activated immune system and this also applies to chronic inflammatory diseases. This presentation examines both components of the systemic and cellular energy metabolism in health and chronic inflammation. Aliterature search was conducted using PubMed, Embase and the Cochrane Library. The information is presented in the form of anarrative review. Achronically activated immune system acquires large amounts of energy-rich substrates that are lost for other functions of the body. In particular, the immune system and the brain are in competition. The consequences of this competition are many known diseases, such as fatigue, anxiety, depression, anorexia, sleep problems, sarcopenia, osteoporosis, insulin resistance, hypertension and others. The permanent change in the brain causes long-term alterations that stimulate disease sequelae even after disease remission. In the intracellular energy supply, chronic inflammation typically involves a conversion to glycolysis (to lactate, which has its own regulatory functions) and the pentose phosphate pathway in disorders of mitochondrial function. The chronic changes in immune cells of patients with rheumatoid arthritis (RA) lead to adisruption of the citric acid cycle (Krebs cycle). The hypoxic situation in the inflamed tissue stimulates many alterations. A differentiation is made between effector functions and regulatory functions of immune cells. Based on the energy changes mentioned, novel treatment suggestions can be made in addition to those already known in energy metabolism.