Chapter 5 - Kidney—Inflammation and remodeling

Abstract

Macrophages populate the kidney in several waves during kidney development, out of which some remain there and, together with dendritic cells, form a peritubular network of resident mononuclear phagocytes. Little information exists on how these cells contribute to homeostasis in a healthy kidney. During the different phases of kidney injury and repair, resident and infiltrating macrophages both amplify changing local microenvironments. In an early injury, they empower host defense to infections or enhance sterile inflammation, while later they enhance the resolution of inflammation and healing responses. In chronic kidney disease, macrophages contribute to continued inflammatory tissue remodeling and tissue fibrosis. The different functional properties of kidney macrophages associate with different gene expression patterns, surface markers, and cytokine secretion profiles, which have led to different phenotype classifications. A universal classification concept that integrates all different views on kidney macrophages still does not exist. However, numerous interventional studies demonstrate that modulating macrophage recruitment and activation patterns can modulate the outcome of kidney disease models. This chapter gives an overview of general concepts and main findings of macrophages in the kidney, a dynamic field with inputs from many different research domains.