Expression of 90-kDa heat shock protein within cellular crescents in human diseased kidneys

We previously reported the induction of 90 kDa heat-shock protein (HSP90) in rat kidneys with cisplatin-induced acute tubular injury, gentamicin-induced acute renal failure and ischaemia-induced acute renal failure. In the present study, we examined the expression of HSP90 in normal and diseased human kidneys. The 90-kDa heat-shock protein (HSP90) from mouse brains was purified, and a specific antibody against the protein in a rabbit was produced. This antibody cross-reacted with human renal HSP90 on immunoblot analysis. Using this antibody we observed the intrarenal immunohistochemical localization of HSP90 in both normal and various human diseased kidneys. We also examined the differences between the distributions of macrophages and HSP90 in cellular crescents. In the normal kidney, HSP90 was present in glomerular podocytes, Bowman's epithelia and epithelial cells from the distal tubules to the collecting duct. In diseased kidneys HSP90 was markedly expressed in the cytoplasm of proliferative cells within cellular crescents, but not in fibrocellular crescents. The localization of HSP90 in crescents did not coincide with that of macrophages. These results demonstrated that HSP90 is induced in the cytoplasm of cellular crescents. Heat-shock protein 90 may be expressed partly in response to some factors produced by macrophages.