BACKGROUND: Tubulointerstitial inflammation and fibrosis are the main pathological features of chronic renal allograft rejection, which is characterized by accumulation of extracellular matrix protein. Heat shock protein 47 (HSP47), known as a collagen-specific stress protein, is thought to be a molecular chaperone during the processing and/or secretion of procollagen. HSP47 is thought to be involved in the progression of fibrosis, but its expression in chronic renal allograft rejection is still unknown. METHODS: We examined the expression of HSP47 together with that of alpha-smooth muscle actin (alpha-SMA), a marker of myofibroblasts, and CD68, a marker of macrophages, by immunohistochemistry in allograft kidney tissues. Uninvolved portions of surgically removed kidneys with tumours served as control tissue. RESULTS: Expression of HSP47 was detected in the interstitium of fibrotic regions of allograft kidneys. Cells positive for HSP47 were also stained for alpha-SMA and type I collagen, and the expression of HSP47 correlated with the degree of interstitial fibrosis. Furthermore, the expression of HSP47 correlated with the number of infiltrating macrophages. In contrast, HSP47 and alpha-SMA were not expressed in the control tissues, sections of 1 h post-transplantation biopsy specimens and acute allograft rejection without fibrosis. CONCLUSION: Our results suggest that HSP47 may contribute to the progression of interstitial fibrosis in allograft renal tissues.
BACKGROUND: Tubulointerstitial inflammation and fibrosis are the main pathological features of chronic renal allograft rejection, which is characterized by accumulation of extracellular matrix protein. Heat shock protein 47 (HSP47), known as a collagen-specific stress protein, is thought to be a molecular chaperone during the processing and/or secretion of procollagen. HSP47 is thought to be involved in the progression of fibrosis, but its expression in chronic renal allograft rejection is still unknown. METHODS: We examined the expression of HSP47 together with that of alpha-smooth muscle actin (alpha-SMA), a marker of myofibroblasts, and CD68, a marker of macrophages, by immunohistochemistry in allograft kidney tissues. Uninvolved portions of surgically removed kidneys with tumours served as control tissue. RESULTS: Expression of HSP47 was detected in the interstitium of fibrotic regions of allograft kidneys. Cells positive for HSP47 were also stained for alpha-SMA and type I collagen, and the expression of HSP47 correlated with the degree of interstitial fibrosis. Furthermore, the expression of HSP47 correlated with the number of infiltrating macrophages. In contrast, HSP47 and alpha-SMA were not expressed in the control tissues, sections of 1 h post-transplantation biopsy specimens and acute allograft rejection without fibrosis. CONCLUSION: Our results suggest that HSP47 may contribute to the progression of interstitial fibrosis in allograft renal tissues.