Role of connective tissue growth factor in experimental radiation nephropathy in rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Connective tissue growth factor (CTGF) is a potent fibrogenic cytokine which has been associated with progressive glomerulosclerosis and tubulointerstitial fibrosis. We investigated the role of CTGF on the progression of a rat model of radiation nephropathy.</p><p><b>METHODS</b>The model of radiation nephropathy in rats was established as follows: control group (n = 12), underwent only laparotomy; irradiated group (n = 20), underwent a laparotomy, then the rats were subjected to a single dose 25 Gy X-ray to the kidneys. The rats were followed up one, three, six and nine months after renal exposure to radiation.</p><p><b>RESULTS</b>Renal dysfunction was noted early in irradiated rats. Histological analysis showed focal glomerular sclerotic lesions at an early stage after irradiation. Radiation-induced glomerular and tubulointerstitial injuries were particularly severe the sixth month after irradiation as compared to the control group (P < 0.01). By immunohistochemistry, increased expression of CTGF was noted in the irradiated kidneys, which began to increase from the first month after irradiation, and remained significantly higher at the sixth and ninth month after irradiation (P < 0.01). Upon Western blot analysis CTGF protein expression showed an increase in the radiation treated kidneys compared with the control rats. The expression of CTGF closely correlated with the progression of radiation nephropathy. The expression of alpha-smooth muscle actin, vimentin, type III collagen and type IV collagen was also high in the irradiated kidney as compared to control rat kidneys (P < 0.05), and was most severe at the sixth and ninth month after irradiation (P < 0.01). By double immunostaining, CTGF expressing cells were found to be alpha-SMA-positive myofibroblasts and vimentin-positive tubular epithelial cells. Glomerular expression of CTGF closely correlated with the glomerular expression of alpha-SMA (r = 0.628, P < 0.01), vimentin (r = 0.462, P < 0.05) and accumulation of type IV collagen (r = 0.584, P < 0.01) in the irradiated kidney. Similarly, the expression of CTGF was positively correlated with the expression of alpha-SMA (r = 0.613, P < 0.01), vimentin (r = 0.629, P < 0.01), deposition of type III collagen (r = 0.741, P < 0.001) and type IV collagen (r = 0.799, P < 0.0001) in the tubulointerstitium of the irradiated kidney. Finally the expression of CTGF after the irradiation of the kidney positively correlated with the levels of blood urea nitrogen and serum creatinine.</p><p><b>CONCLUSION</b>Overexpression of CTGF may play an important role in the development and progression of glomerulosclerosis and tubulointerstitial fibrosis in radiation nephropathy.</p>

Role of integrin-linked kinase in renal tubular epithelial-mesenchymal transition of mice with obstructive nephropathy / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the expression of integrin-linked kinase (ILK) in kidneys of mice with unilateral ureteral obstruction and its relevance with the epithelial-mesenchymal transition.</p><p><b>METHODS</b>Mice were randomly divided into two groups, sham operation (C, n = 20) and unilateral ureteral obstruction (UUO, n = 40). The animals were sacrificed at day 1, 3, 7 and 14 respectively after the surgery. Tubulointerstitial fibrosis (TIF) was graded according to Masson staining. The protein level of ILK was examined by Western blot. Tissue/cytological expression for ILK, alpha-SMA and E-cadherin were investigated by immunohistochemistry. The mRNA levels of ILK, alpha-SMA and E-cadherin were analyzed by quantitative real-time PCR.</p><p><b>RESULTS</b>In the control animals (group C), weak staining for ILK was detected mainly in the podocytes. Significant increase of staining for ILK in the experimental mice (UUO group) was detected from day 1 onward (t = 16.5, P < 0.01), reaching the peak at day 7. The protein expression of E-cadherin was continuously down-regulated from day 3 onward after surgery (t = 21.0, P < 0.01), while expression for alpha-SMA was up-regulated. From day 1 to day 7, the protein expression of ILK was positively correlated with alpha-SMA (R = 0.88, P < 0.01), but negatively correlated with E-cadherin (R = -0.87, P < 0.01). The mRNA expression of ILK and alpha-SMA analyzed by real-time PCR increased from postoperative day 1 and 3 respectively, but the mRNA expression of E-cadherin decreased from day 3 onward.</p><p><b>CONCLUSION</b>Increasing expression of ILK occurs in the early phase of UUO mouse and may play an important role in the process of TIF through mediating the epithelial-mesenchymal transition.</p>

Connective tissue growth factor is associated with the early renal hypertrophy in uninephrectomized diabetic rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Renal hypertrophy has been regarded as the early feature of diabetic nephropathy (DN), which may eventually lead to proteinuria and renal fibrosis. However, the exact mechanism of renal hypertrophy is still unclear. The aim of this study was to investigate the possible association of connective tissue growth factor (CTGF) with renal hypertrophy in uninephrectomized diabetic rats.</p><p><b>METHODS</b>Seventy-two Sprague-Dawley (SD) rats were randomly divided into two groups: control group (group C, n = 32) and diabetic nephropathy (group DN, n = 40). Each group was re-divided into 4 subgroups according to the experimental period. The rats were sacrificed at 1, 2, 4, and 8 weeks respectively after induction of diabetes. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) after rats had received uninephrectomy. Blood glucose (BG), body weight (BW), 24-h urinary albumin excretion (24hUalb), kidney weight (KW), KW/BW, glomerular tuft area (AG), glomerular tuft volume (VG), proximal tubular area (AT) at each time point, the width of glomerular basement membrane (GBM) and tubular basement membrane (TBM) at week 8 were measured when the rats were sacrificed. Renal expression of CTGF and p27kip1 were detected by immunohistochemical staining. The relationship between CTGF expression and increasing of VG and AT was analyzed.</p><p><b>RESULTS</b>There was a significant increase of 24hUalb, KW, and KW/BW from week 1 onward in diabetic rats compared to those in group C (P < 0.05, respectively), diabetic rats also had a significant increase of AG, VG, and AT from week 1 onward. It was also shown that diabetic rats had a thickening of GBM [(245.7 +/- 103.0) nm vs (121.8 +/- 19.1) nm, P < 0.01] and TBM [(767.7 +/- 331.1) nm vs (293.0 +/- 110.5) nm, P < 0.01] at week 8. There was a weak expression for CTGF and p27kip1 in normal glomeruli and tubuli, while a significant increasing expression of CTGF and p27kip1 was found in glomeruli and tubuli in diabetic kidney from week 1 onward (P < 0.05, respectively), and the extent of CTGF expression was positively correlated with AG (r = 0.92, P < 0.05), VG (r = 0.86, P < 0.05), AT (r = 0.94, P < 0.01) and positively correlated with the expression of p27kip1 (r = 0.96, P < 0.01).</p><p><b>CONCLUSION</b>The expression of CTGF increases in diabetic rat kidney at the early stage, which might be an important mediator of renal hypertrophy through arresting cell cycling.</p>