The immune system and kidney disease: basic concepts and clinical implications

Chronic kidney diseases are common in ageing populations and, if they progress to the end stage, are an economic burden because of the need for dialysis or transplantation. Immune mechanisms are centrally involved in the progression of kidney disease and their elucidation is an important research goal.Recent studies have defined the immune mechanisms responsible for some previously unexplained kidney diseases. These may also be relevant to diseases affecting other organs.Greater knowledge of immune homeostasis in the kidneys has identified features that render this organ susceptible to distinct types of immune-mediated damage; for example, kidney-specific damage-associated molecular patterns (DAMPs) and a predisposition to crystal formation.The availability of well-characterized animal models and of biopsy samples from patients with renal disease makes the kidney an attractive model organ to analyse novel pathways of host defence, autoimmune injury, sterile inflammation and fibrosis.The kidney has a central role in electrolyte homeostasis and the removal of toxins and so, when its function is compromised, normal immune effector cell function and intestinal microbial homeostasis are disturbed.Kidney failure increases susceptibility to infection and promotes exaggerated inflammatory responses, both of which increase mortality. The underlying mechanisms responsible remain to be clarified.