Chronic Inflammation and Metabolic Stress

Abstract

In this chapter, we will present monocytes and macrophages as the key players in acute and chronic inflammation. Macrophages react stimulus- and tissue-specifically and either develop from monocytes that are circulating in the blood or from self-renewing embryonal cell populations. M1-type macrophages are key cells in the initiation of the acute inflammatory response, while M2-type macrophages are resolving inflammation and coordinate tissue repair. Tissue inflammation is not only caused by bacterial infection or tissue injury but also derives from changes in the concentration of nutrients and metabolites. We will provide examples of metabolic stress, such as disturbance of reverse cholesterol transport and ER stress. The latter is, in contrast to infectious or traumatic stress, often caused by lipid overload in the blood and in adipose tissue. Thus, the immune system is implicated in the regulation of metabolic homeostasis, while perturbations in this immune-metabolic network are often the basis of the different features of the metabolic syndrome.