Inflammatory cells in renal injury and repair

Renal inflammation may result from a myriad of insults and often is characterized by the presence of infiltrating inflammatory leukocytes within the glomerulus or tubulointerstitium. Accumulating evidence indicates that infiltrating leukocytes are key players in the induction of renal injury. Although renal inflammation often is followed by the development of fibrosis with loss of renal function, it can resolve. Resolution may be spontaneous as in poststreptococcal glomerulonephritis or after the administration of effective treatment such as immunosuppressive agents. The mechanisms and cells underlying the resolution process and the exact temporal sequence remains uncertain at present but likely involves the removal of injurious leukocytes, the down-regulation of immune responses, and the alteration of the phenotype of infiltrating macrophages from proinflammatory to prorepair. In this review we examine the role of leukocytes in both renal inflammation and repair.