Hepatocyte growth factor prevents the development of chronic allograft nephropathy in rats

Long-term renal isografts in humans and laboratory animals exhibit features similar to those of chronic allograft nephropathy (CAN), indicating that antigen-independent factors, such as acute renal ischemia, are likely to be involved in the development of CAN. Hepatocyte growth factor (HGF) has been demonstrated to play a renotropic role in renal regeneration and protection from acute ischemic injury. This study was thus conducted to investigate the effect of HGF on the development of CAN, using an established rat model. HGF was administered daily (100 microg/d, intravenously) for 4 wk after engraftment. Control animals received saline solution. Allografts from control animals exhibited early evidence of severe structural collapse and necrotic cell death in the proximal tubules and outer medulla, with mononuclear cell infiltration, within 1 wk after engraftment. This was followed by sequential upregulation of adhesion molecules and cytokines, accompanied by dense macrophage infiltration. Fibrogenic events, as indicated by marked increases in transforming growth factor-beta1 expression and the accumulation of smooth muscle alpha-actin, occurred during the same period. Control animals ultimately developed features typical of CAN, with functional deterioration and severe histologic changes; a survival rate of 50.6% by 32 wk was observed. In contrast, remarkably little early injury and no late fibrogenic events were observed for the HGF-treated group. All treated animals survived, with well preserved graft function, during the 32-wk follow-up period. These results indicate that renal protection and recovery from early allograft injury with HGF treatment greatly contribute to a reduction of susceptibility to the subsequent development of CAN in a rat model. The potential application of HGF in the prevention of CAN warrants further attention.     

Hepatocyte growth factor suppresses interstitial fibrosis in a mouse model of obstructive nephropathy

BACKGROUND: As tubulointerstitial fibrosis (TIF) reflects the prognosis of patients with various chronic renal diseases, the pathogenesis of TIF has to be clarified. Transforming growth factor-beta (TGF-beta) is a key mediator for renal fibrosis. We reported that hepatocyte growth factor (HGF) prevents renal fibrosis in nephrotic mice. However, the function of HGF in chronic renal failure, except for nephrotic syndrome, remains to be determined. METHODS: Using mice subjected to unilateral ureter-ligated obstruction (UUO), we investigated the roles of HGF in TIF, as induced by obstructive nephropathy. Pathophysiological changes in the kidney after UUO treatment were analyzed focusing on expressions of renal HGF and TGF-beta, TIF, tubular proliferation, and apoptosis. Neutralizing antibody against rodent HGF, or recombinant human HGF (rhHGF), was administrated to the UUO mice, and pathophysiological changes after neutralization or supplements of HGF were analyzed. RESULTS: In this UUO model, TIF with tubular apoptosis became evident, and it was accompanied by a decrease in renal HGF expression and an increase in renal TGF-beta expression. Neutralization of endogenous HGF accelerated the progression of TIF, accompanied by increases in TGF-beta expression and tubular apoptosis as well as by decreases in tubular proliferation. In contrast, rhHGF attenuated TIF progression, and there were decreases in TGF-beta expression and tubular apoptosis, and an increase in tubular proliferation. CONCLUSIONS: Endogenous as well as exogenous HGF attenuated the progression of the fibrosis caused by obstructive nephropathy in these mice. Thus, local reduction in HGF levels may account for TIF in chronic renal diseases.     

大黄酸对2型糖尿病肾病大鼠疗效观察

目的：观察大黄酸防治2型糖尿病肾病的作用。方法：以高糖高脂饮食联合低剂量链脲佐菌素（STZ）注射方法诱导出2型糖尿病肾病大鼠模型后，分模型组、预防组和治疗组，后2组分别在STZ注射后1周和1个月后给予大黄酸100mg/kg剂量灌胃，每日1次，连续6个月，在不同时间进行形态学和有关生化指标的观察。结果：大黄酸预防给药和治疗后的观察结果显示，大黄酸明显降低糖尿病大鼠的24h尿蛋白排泄，改善肾重指数。肾脏组织病理学显示，大黄酸处理后的糖尿病大鼠肾小球和丝球体的面积明显减小，襻腔扩张减轻，系膜增生和细胞外基质减少。大鼠肾小球纤连蛋白沉积明显减弱。大黄酸也明显降低糖尿病大鼠的血脂水平。以上作用随着给药时间的延长，效果越来越明显。胰岛素抑制试验表明，在大黄酸预防给药和治疗6个月后，糖尿病大鼠的血浆稳态葡萄糖水平（SSPG）显著降低。以上结果比较，以预防组效果为佳。结论：大黄酸通过降低糖尿病大鼠的尿蛋白排泄、减轻肾脏肥大、改善胰岛素敏感性、降低血脂水平，有效地防治2型糖尿病肾病。     

Halting the progression of chronic nephropathy

The incidence of end-stage renal disease (ESRD) is increasing worldwide. In the United States alone, there were 372,000 patients requiring renal replacement therapy in the year 2000 and is expected to rise to 650,000 by the year 2010. The trends in Europe and Japan are forecasted to follow a similar path. These increases represent a significant burden to countries worldwide; not only due to the financial costs of providing ESRD care, but also because of lost productivity and significant morbidity and mortality for the affected patients. There is clearly a pressing need for the aggressive identification and early treatment of patients with nephropathy to prevent progression to ESRD. Research in the last 25 yr has made great advances in the understanding of the progression of chronic renal disease in diabetic and nondiabetic proteinuric nephropathy. There are now effective treatment options that can slow the progression of chronic nephropathies in many individuals, and ongoing research has raised the tantalizing prospect of the reversal of renal disease progression.     

Regression of advanced diabetic nephropathy by hepatocyte growth factor gene therapy in rats

Diabetic nephropathy is the main cause of end-stage renal disease requiring dialysis in developed countries. In this study, we demonstrated the therapeutic effect of hepatocyte growth factor (HGF) on advanced rather than early diabetic nephropathy using a rat model of streptozotocin-induced diabetes. Early diabetic nephropathy (16 weeks after induction of diabetes) was characterized by albuminuria, hyperfiltration, and glomerular hypertrophy, whereas advanced diabetic nephropathy showed prominent transforming growth factor (TGF)-beta1 upregulation, mesangial expansion, and glomerulosclerosis. An SP1017-formulated human HGF (hHGF) plasmid was administered by intramuscular injection combined with electroporation over a 30-day follow-up in rats with early and advanced diabetic nephropathy. hHGF gene therapy upregulated endogenous rat HGF in the diabetic kidney (rat HGF by RT-PCR was threefold higher than in diabetic rats without therapy). hHGF gene therapy did not improve functional or morphologic abnormalities in early diabetic nephropathy. hHGF gene therapy reduced albuminuria and induced strong regression of mesangial expansion and glomerulosclerosis in advanced diabetic nephropathy. These findings were associated with suppression of renal TGF-beta1 and mesangial connective tissue growth factor (CTGF) upregulation, inhibition of renal tissue inhibitor of metalloproteinase (TIMP)-1 expression, and reduction of renal interstitial myofibroblasts. In conclusion, our results suggest that hHGF gene therapy may be considered as an innovative therapeutic strategy to treat advanced diabetic nephropathy.     

Hepatocyte growth factor prevents chronic allograft dysfunction in liver-transplanted rats

BACKGROUND: Hepatocyte growth factor (HGF) is a growth factor with multiple biologic properties, including mitogenic, morphogenic, anti-apoptotic, and antifibrogenic activities. Long-term administration of the deletion variant of HGF (dHGF) might contribute to the prevention of chronic liver allograft dysfunction, which is attributed to immunologic and nonimmunologic reactions. METHODS: Low-dose tacrolimus was administered to rat-liver recipients after transplantation. Effects of dHGF on transplanted livers treated with low-dose tacrolimus were investigated. RESULTS: Rats receiving liver transplants treated with only low-dose tacrolimus administration showed chronic allograft dysfunction. Treatment with dHGF prolonged the survival time of rats that received liver allografts and suppressed fibrosis of liver allograft. Treatment with dHGF also suppressed the expression levels of interleukin (IL)-1beta, caspase-1, and transforming growth factor (TGF)-beta mRNAs in liver allografts. CONCLUSIONS: The findings indicate that dHGF may prevent chronic liver-allograft dysfunction and thus may become a novel treatment for chronic liver-allograft dysfunction.     

Hepatocyte growth factor gene therapy and angiotensin II blockade synergistically attenuate renal interstitial fibrosis in mice

Tubulointerstitial fibrosis is considered to be common endpoint result of many forms of chronic renal diseases. Except for renal replacement, chronic renal fibrosis is presently incurable. This study demonstrates that the combination of hepatocyte growth factor (HGF) gene therapy with inhibition of the renin-angiotensin system produced synergistic beneficial effects leading to dramatic attenuation of renal tubulointerstitial fibrosis in obstructive nephropathy in mice. The combined treatment with human HGF gene and losartan, an angiotensin II (AngII) type I receptor blocker, preserved renal mass and gross morphology of the obstructed kidneys. Although HGF gene therapy alone inhibited the expression of alpha-smooth muscle actin (alpha SMA) by approximately 54% and 60% at day 7 and day 14 after surgery, respectively, its combination with losartan almost completely abolished alpha SMA induction in the obstructed kidneys. The combined therapy also synergistically inhibited the accumulation of interstitial matrix components, such as fibronectin and collagen I, and suppressed renal expression of transforming growth factor-beta1 (TGF-beta1) and its type I receptor. In vitro studies revealed that AngII by itself did not induce alpha SMA, but it drastically potentiated TGF-beta1-initiated alpha SMA expression in tubular epithelial cells. Furthermore, HGF abrogated de novo alpha SMA expression induced by TGF-beta1 plus AngII. These results suggest that many factors are implicated in the pathogenesis of renal interstitial fibrosis; therefore, a combined therapy aimed at simultaneously targeting multiple pathologic pathways may be necessary for halting the progression of chronic renal diseases. These findings may provide the basis for designing future therapeutic regimens for blocking progressive renal fibrosis in patients.     

Hepatocyte growth factor ameliorates progression of interstitial fibrosis in rats with established renal injury

BACKGROUND: Hepatocyte growth factor (HGF) has been reported to prevent injury in several models of renal disease; however, whether HGF can also retard progression of established renal disease is not known. METHODS: The aim of the present study was to examine the effects of HGF on progression of chronic renal disease in rats with remnant kidneys and established injury. Studies were performed in rats that underwent subtotal nephrectomy, were observed for two weeks without therapy, and then randomized to receive HGF or vehicle by continuous infusion for an additional two weeks. RESULTS: HGF administration was associated with a reduction in morphologic evidence of interstitial, but not glomerular injury. The beneficial effects of HGF were not associated with reductions in the expression of transforming growth factor-beta (TGF-beta), or in the extent epithelial cell apoptosis or transdifferentiation. Rather, HGF appeared to induce fibrinolytic pathways by increasing expression of metalloproteinase-9 (MMP-9) and decreasing levels of plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metalloproteinase-1 (TIMP-2). HGF administration was also associated with an apparent increase in renal endothelin production and a significant reduction in glomerular capillary pressure. CONCLUSION: These findings suggest that HGF can retard progression of chronic renal disease even after injury is already established, primarily by promoting matrix degradation.     

Vascular endothelial growth factor in chronic rat allograft nephropathy

BACKGROUND: Chronic allograft nephropathy (CAN) is a complex process of alloimmune responses and chronic inflammation leading to fibrosis and vasculopathy. We examined the biological role of proinflammatory vascular endothelial growth factor (VEGF) in a rat renal transplantation model of CAN. METHODS: Syngraft and allograft recipients were treated with a suboptimal dose of cyclosporine A which allows acute rejection and CAN to develop. Intragraft VEGF, VEGFR-1 and VEGFR-2 expressions were determined at 5, 14, 30 and 60 days. Protein tyrosine kinase inhibitor PTK787 was used to inhibit VEGFR activity. RESULTS: In nontransplanted kidneys and syngrafts, mild VEGF expression was observed in the glomeruli and tubuli. VEGFR-1 was detected in vascular structures and VEGFR-2 in glomeruli as well. In allografts, total intragraft VEGF expression and interstitial inflammatory cell VEGF expression were induced and correlated with the chronic allograft damage index (CADI) score. Total intragraft and interstitial inflammatory cell VEGFR-1 expression was induced and interstitial cell VEGFR-1 expression correlated with the CADI score. Blocking VEGF receptor signaling with PTK787 significantly reduced fibrosis and the CADI score, but did not affect early inflammation or VEGF, VEGFR-1, VEGFR-2 expressions compared to vehicle treated group. CONCLUSIONS: Interstitial inflammatory cell VEGF and VEGFR-1 expressions are induced during the development of CAN. Increased VEGF activity may enhance the alloimmune induced inflammatory responses leading to fibrosis and CAN.     

Peritubular capillary regression during the progression of experimental obstructive nephropathy

Injury to the renal microvasculature may be a major factor contributing to the progression of renal disease. Although severe disruption of peritubular capillaries (PTC) could lead to marked tubulointerstitial scarring, elucidation of that process remains incomplete. This study investigated the morphologic changes in PTC and their likely regulation by vascular endothelial growth factor (VEGF) during the progression of tubulointerstitial injuries. Unilateral ureteral obstruction was induced in Wistar rats by ligation of the left ureter, and the kidneys were then collected at selected times. PTC lumina and the expression of VEGF and its receptor Flk-1 were immunohistochemically detected. Morphologic changes in PTC endothelial cells were examined by using Ki67 staining, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling, and electron-microscopic studies. In the first week of the disease period, immunohistochemical labeling of tubular VEGF intensified, with accompanying deformation and dilation of adjacent thrombomodulin (TM)-positive PTC lumina; an angiogenic response of endothelial cells was demonstrated with Ki67 and TM double-staining. During the subsequent 2 wk, tubular VEGF labeling decreased until it was virtually absent, an effect confirmed by Western blotting. Concomitantly, labeling of the VEGF receptor Flk-1 in PTC endothelial cells decreased and PTC lumina began to regress, demonstrating endothelial cell apoptosis (as detected in terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling and electron-microscopic studies). By the end of week 4, the numbers of TM-positive PTC lumina were significantly decreased in areas of marked tubulointerstitial scarring. These results suggest that PTC regression, involving an early, unsustained, angiogenic response followed by progressive endothelial cell apoptosis, could be a potential factor contributing to tubulointerstitial scarring in this unilateral ureteral obstruction model.     

Adenovirus-mediated antisense-ERK2 gene therapy attenuates chronic allograft nephropathy

BACKGROUND: The aim of this study was to investigate the effects of adenovirus-mediated antisense ERK2 (Adanti-ERK2) gene therapy on chronic allograft nephropathy. METHODS: We employed a rat kidney transplantation mode (F344-->Lewis) and studied four groups: (1) controls (n = 6); (2) vector controls (n = 6); (3) an Adanti-ERK2 group (n = 10); and (4) an isograft group (n = 4). The animals were monitored for proteinuria, graft histology, infiltrating cells, and immune-related gene (interleukin-2 [IL-2] and intracellular adhesion molecule-1 [ICAM-1]) expression for 20 weeks after transplantation. RESULTS: The control group had increasing proteinuria during the 20-week follow-up. All rats showed advanced chronic renal failure associated with strong immune cell infiltration and immune gene expression. Chronic graft injury was accelerated in the vector-control group, but no significant difference was observed compared with the control group. In contrast, the Adanti-ERK2 group showed less inflammation and improved graft histology/function compared with controls. Moreover, ERK2 protein expression in the Adanti-ERK2 group was lower than in the control group (P < .05) and vector-control group (P < .05). Furthermore, serial estimates of genes (IL-2, ICAM-1) related to chronic rejection showed significant downregulation in the Adanti-ERK2 group (P < .01). CONCLUSIONS: Adenovirus-mediated antisense ERK2 gene therapy attenuated chronic allograft nephropathy. The protective effects of antisense ERK2 gene therapy may have derived from a blocked ERK signal transduction pathway, which reduced ERK expression as well as those of immune-related genes.     

肝细胞生长因子与男性生殖

肝细胞生长因子(HGF)是一种多效性生长因子,通过与受体c-Met结合后发挥多种生物学效应。本文阐述其生物学特性,并着重强调其与男性生殖的相关性,包括HGF具有促胚胎期睾丸发育、睾丸生精细胞和精子发生、睾丸间质细胞睾酮合成等作用,希望HGF能在男性迟发性性腺功能减退、少弱精子症等男科疾病的治疗方面,提供新的思路与方法,只是目前尚缺乏相关的临床研究。