Heat Shock Protein 47: A Novel Biomarker of Phenotypically Altered Collagen-Producing Cells

Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone that helps the molecular maturation of various types of collagens. A close association between increased expression of HSP47 and the excessive accumulation of collagens is found in various human and experimental fibrotic diseases. Increased levels of HSP47 in fibrotic diseases are thought to assist in the increased assembly of procollagen, and thereby contribute to the excessive deposition of collagens in fibrotic areas. Currently, there is not a good universal histological marker to identify collagen-producing cells. Identifying phenotypically altered collagen-producing cells is essential for the development of cell-based therapies to reduce the progression of fibrotic diseases. Since HSP47 has a single substrate, which is collagen, the HSP47 cellular expression provides a novel universal biomarker to identify phenotypically altered collagen-producing cells during wound healing and fibrosis. In this brief article, we explained why HSP47 could be used as a universal marker for identifying phenotypically altered collagen-producing cells

Increased Expression of Collagen-binding Heat Shock Protein 47 in Human and Experimentally-induced Rat Crescentic Glomerulonephritis: its Possible Role in Fibrotic Process

The 47-kD heat shock protein 47 (HSP47), a major collagen-binding stress protein, is thought to play an important role in fibrotic diseases. To investigate the role of HSP47 in the fibrotic process of crescent formation in renal glomeruli, involvement of HSP47 was examined in both human and experimental crescentic glomerulonephritis (GN). Renal biopsy sections of 15 cases of crescentic GN and 5 cases of minimal change nephrotic syndrome were examined for the expression of HSP47. Experimental crescentic GN was induced by anti-glomerular basement membrane antibody in rats. HSP47 expression was examined in crescents at various stages of formation (days 7, 14, 21, 28 and 42). In human renal biopsy sections, increased expression of HSP47 was noted in the cellular stage of crescent formation. Double immunostaining demonstrated that the majority of ﾎｱ-smooth muscle actin-positive cells in the crescent expressed HSP47. However, its expression was less in fibrous crescents, which were predominantly composed of type III collagen. In the rat model of crescent GN, increased expression of HSP47, both at mRNA and protein levels, was noted in the early stages of cellular crescents. However, its expression was decreased in the late stages of fibrous crescents. Based on the collagen synthesis ability of HSP47, we speculate that overexpression of HSP47 in cellular crescents may contribute to the excessive synthesis/ assembly of collagens and subsequently lead to irreversible fibrous crescent formation

The incidence and distribution of biopsy-proven renal diseases in children

The precise distribution pattern of pediatric renal diseases has seldom been reported especially for young children. In orderto clarify the incidence and distribution of renal diseases in children, 599 renal biopsy specimens obtained from 547 pediatricpatients (≦15 years old) were analyzed by routine light, electron and immunofluorescence microscopy. Among the total biopsycases, the most common renal disease identified in childhood was IgA glomerulonephritis (IgAGN; 37%). More than 80%of patients with IgAGN were discovered by urinary screening at the school, showing asymptomatic proteinuria and/orhematuria. The other major renal diseases were minor glomerular abnormality (12.2%), Henoch-Schönlein purpura nephritis(HSPN; 10.6%), and thin basement membrane disease (7.1%). One of the major causes of pediatric nephrotic syndrome wereminimal change nephrotic syndrome (58%), whereas the other causes were IgAGN (11.6%), HSPN (8.9%), membranousglomerulonephritis (5.4%), membranoproliferative glomerulonephritis (3.6%). In conclusion, IgAGN was the most commonrenal disease also in children as in adolescence. From the age of seven years, the incidence of IgA-GN was highest amongall the pediatric renal diseases during whole childhood period, and the incidence and number of the patients increased as theygrow. On the other hand, there are also many cases with non-progressive clinical courses, such as minor glomerular abnormalityand thin basement membrane disease in children. The renal biopsy following routine urinary screening at the schoolmay be important for the therapeutic and prognostic guidelines of pediatric group of patients with renal diseases

Role of Connective Tissue Growth Factor and Angiotensin II in Tubulointerstitial Fibrosis in Experimental Obstructive Nephropathy

Angiotensin II (Ang-II) and connective tissue growth factor (CTGF) are involved in various renal disorders that lead to end-stage renal disease. Here, we determined the role of Ang-II and CTGF in the progression of tubulointerstitial injury in the rat unilateral ureteral obstruction (UUO) model. Sprague-Dawley rats (n=16) were used; 10 rats underwent UUO, and 6 control rats underwent sham operation; and rats of both groups were sacrificed on days 7 or 14. Histomorphometric analysis was performed to quantitate tubulointerstitial injuries in the experimental group. Kidney sections were stained immunohistochemically for Ang-II, CTGF, transforming growth factor-β1 (TGF-β1), type III collagen and α-smooth muscle actin (α-SMA). Renal CTGF expression was studied using in situ hybridization and reverse transcriptase-polymerase chain reaction. Double staining for Ang-II with α-SMA and CTGF with α-SMA was performed to identify cells with enhanced expression of Ang-II and CTGF. Similar dual staining of Ang-II with type III collagen and CTGF with type III collagen was performed. The correlation between Ang-II and CTGF expression and tubulointerstitial injury was examined. In obstructed kidneys, there was a significant (p<0.001) increase in expression of Ang-II, CTGF, TGF-β1, type III collagen and α-SMA, compared with control kidneys. Tubular epithelial cells and interstitial cells were the main Ang-II- and CTGF-producing cells in the obstructed kidneys. A significantly (p<0.001) positive correlation was detected in obstructed kidneys between renal expression of CTGF and expression of TGF-β1 (r=0.91), type III collagen (r=0.87) or α-SMA (r=0.90). Similarly a significantly (p<0.001) positive correlation was found in obstructed kidneys between Ang-II expression and expression of TGF-β1 (r=0.88), type III collagen (r=0.79) and α-SMA (r=0.91). Finally, there were significantly positive correlations between CTGF /Ang-II expression and tubulointerstitial fibrosis in the obstructed kidneys (r=0.88, p<0.001). The results of our in vivo studies suggest that both Ang-II and CTGF, produced by intrarenal cells, coordinately regulate progression of renal tubulointerstitial injury, by facilitating increased accumulation of interstitial collagens in obstructed kidneys

Role of Connective Tissue Growth Factor and Angiotensin II in Tubulointerstitial Fibrosis in Experimental Obstructive Nephropathy

Angiotensin II (Ang-II) and connective tissue growth factor (CTGF) are involved in various renal disorders that lead to end-stage renal disease. Here, we determined the role of Ang-II and CTGF in the progression of tubulointerstitial injury in the rat unilateral ureteral obstruction (UUO) model. Sprague-Dawley rats (n=16) were used; 10 rats underwent UUO, and 6 control rats underwent sham operation; and rats of both groups were sacrificed on days 7 or 14. Histomorphometric analysis was performed to quantitate tubulointerstitial injuries in the experimental group. Kidney sections were stained immunohistochemically for Ang-II, CTGF, transforming growth factor-β1 (TGF-β1), type III collagen and α-smooth muscle actin (α-SMA). Renal CTGF expression was studied using in situ hybridization and reverse transcriptase-polymerase chain reaction. Double staining for Ang-II with α-SMA and CTGF with α-SMA was performed to identify cells with enhanced expression of Ang-II and CTGF. Similar dual staining of Ang-II with type III collagen and CTGF with type III collagen was performed. The correlation between Ang-II and CTGF expression and tubulointerstitial injury was examined. In obstructed kidneys, there was a significant (p<0.001) increase in expression of Ang-II, CTGF, TGF-β1, type III collagen and α-SMA, compared with control kidneys. Tubular epithelial cells and interstitial cells were the main Ang-II- and CTGF-producing cells in the obstructed kidneys. A significantly (p<0.001) positive correlation was detected in obstructed kidneys between renal expression of CTGF and expression of TGF-β1 (r=0.91), type III collagen (r=0.87) or α-SMA (r=0.90). Similarly a significantly (p<0.001) positive correlation was found in obstructed kidneys between Ang-II expression and expression of TGF-β1 (r=0.88), type III collagen (r=0.79) and α-SMA (r=0.91). Finally, there were significantly positive correlations between CTGF /Ang-II expression and tubulointerstitial fibrosis in the obstructed kidneys (r=0.88, p<0.001). The results of our in vivo studies suggest that both Ang-II and CTGF, produced by intrarenal cells, coordinately regulate progression of renal tubulointerstitial injury, by facilitating increased accumulation of interstitial collagens in obstructed kidneys

The incidence and distribution of biopsy-proven renal diseases in children

The precise distribution pattern of pediatric renal diseases has seldom been reported especially for young children. In order to clarify the incidence and distribution of renal diseases in children, 599 renal biopsy specimens obtained from 547 pediatric patients (≦15 years old) were analyzed by routine light, electron and immunofluorescence microscopy. Among the total biopsy cases, the most common renal disease identified in childhood was IgA glomerulonephritis (IgAGN; 37%). More than 80% of patients with IgAGN were discovered by urinary screening at the school, showing asymptomatic proteinuria and/or hematuria. The other major renal diseases were minor glomerular abnormality (12.2%), Henoch-Schönlein purpura nephritis (HSPN; 10.6%), and thin basement membrane disease (7.1%). One of the major causes of pediatric nephrotic syndrome were minimal change nephrotic syndrome (58%), whereas the other causes were IgAGN (11.6%), HSPN (8.9%), membranous glomerulonephritis (5.4%), membranoproliferative glomerulonephritis (3.6%). In conclusion, IgAGN was the most common renal disease also in children as in adolescence. From the age of seven years, the incidence of IgA-GN was highest among all the pediatric renal diseases during whole childhood period, and the incidence and number of the patients increased as they grow. On the other hand, there are also many cases with non-progressive clinical courses, such as minor glomerular abnormality and thin basement membrane disease in children. The renal biopsy following routine urinary screening at the school may be important for the therapeutic and prognostic guidelines of pediatric group of patients with renal diseases