Epigenetic, post-transcriptional and metabolic mechanisms of macrophage reprogramming

Abstract

A key role in the ability of immunity to adequately respond to pathogenic factors play macrophages. Depending on the type of infection and the microenvironment macrophages can rapidly change their phenotype towards the proinflammatory M1 or antiinflammatory M2 one. The process of changing the cell phenotype is termed "reprogramming." This process plays a central role in the immune response and therefore its disturbance triggers the development of disease. Reprogramming of macrophages is provided by intracellular signaling pathways. These paths can also control epigenetic, post-transcriptional and metabolic mechanisms of phenotypic activity of macrophages. Epigenetic mechanisms can be divided into the reprogramming mechanisms towards M1 and M2 phenotype. A key component of post-transcriptional regulation is micro-mRNA (miR). On M1- and M2- stimuli macrophages express different sets of miRs. MiRs may form a positive feedback mechanism for quick reprogramming of macrophages and negative feedback mechanisms, to limit excessive inflammation in the case of M1 phenotype and to restrict fall bactericidal activity in the case of M2 phenotype. Reprogramming of macrophages leads to a change in the metabolism of these cells. Formation of M1 phenotype accompanied by a shift of the arginine metabolism towards NO-synthase activation and increased production of NO, an increase in the contribution of glycolysis to ATP production, increased deposition of bacteriostatic iron. Formation of the M2 phenotype is accompanied by a shift of the arginine metabolism towards arginase 1 activation and increasing production of urea, increased ATP synthesis in mitochondria and increased capture of fatty acids, increased the capture of heme iron. Metabolic control of macrophage phenotype also involves the positive and negative feedback. In general, macrophage reprogramming involves very good coordinated and adapted to each other changes in the activity of signaling, epigenetic, post-translational and metabolic mechanisms. A detailed understanding of the mechanisms of reprogramming will assist in selecting the correct effective therapeutic targets to develop new ways for correction of impaired immunity.