The role of mineralocorticoid receptor activation in kidney inflammation and fibrosis

Chronic kidney disease is characterized by progressive scarring that results in loss of normal tissue in the kidney and eventually end-stage kidney disease. Interstitial fibrosis and tubular atrophy have been most closely correlated with decline in renal function. Potential mechanisms include profibrotic changes in tubules, influx of profibrotic rather than healing reparative macrophages, and an increase in activated myofibroblasts. Aldosterone activates the mineralocorticoid receptor in the collecting duct to increase sodium reabsorption, resulting in increased blood pressure. Aldosterone also promotes inflammation and fibrosis in the kidney by activating the mineralocorticoid receptor in other cellular compartments, including podocytes, mesangial cells, epithelial cells, and myeloid cells. Aldosterone also may act indirectly by stimulating factors in epithelial tissues that contribute to inflammatory macrophage polarization, myofibroblast differentiation, and progressive fibrosis. This review discusses the potential mechanisms by which aldosterone and mineralocorticoid receptor activation promotes inflammation and fibrosis via nonclassical pathways in the kidney.