肝细胞生长因子在损伤肾组织中的作用

肝细胞生长因子（hepatocyte growth factor．HGF）是一种多效性生长因子,主要由间质细胞产生,通过自分泌和旁分泌方式作用于上皮细胞、内皮细胞以及间质细胞本身,具有促有丝分裂、促细胞形态形成和调节细胞活动的功能,从而对损伤的器官和组织进行修复。许多新的研究显示,在急性肾损伤时给予外源性HGF可以保护肾小管上皮细胞、重建肾小管结构和维持肾功能完整性。此外,HGF还能有效地抑制与慢性肾脏疾病及慢性肾功能衰竭密切相关的肾间质纤维化的进展过程。     

携带人肝细胞生长因子重组质粒pUDK-HGF对大鼠肾纤维化的防治作用

目的:研究肝细胞生长因子(HGF)基因转导对庆大霉素诱导的大鼠肾纤维化损伤的防治效果。方法:以雄性Wistar大鼠腹腔注射硫酸庆大霉素注射液制备肾纤维化模型;实验分为正常对照组、肾纤维化模型组、HGF治疗组;造模后第30 d,HGF治疗组于左侧肾脏直接注射重组质粒pUDK-HGF注射液,模型组注射质粒pUDK,正常对照组只进行假手术;于造模后第60 d处死大鼠,评价HGF对血尿素氮、血肌酐、24 h尿蛋白、肾系数等肾功能指标的改善作用,并对肾纤维化进行组织学评价。结果:与正常对照组相比,模型组肾功能下降,肾系数(8.8±0.95 g/kg)、血尿素氮(9.4±2.61 mmol/L)、血肌酐(42±10.33μmol/L,P<0.05)及24 h尿蛋白定量(25.78±8.66 mg,P<0.05)升高;HGF治疗组对肾功能有所改善,可缓解肾纤维化的进展。此外,本实验表明,对已纤维化肾脏直接注射HGF基因,可促进肾间质血管再生,并进一步降低肾小管间质损伤积分。结论:将HGF基因靶向导入大鼠体内可有效防治肾纤维化。     

肾间质纤维化相关信号通路的研究进展

肾间质纤维化是以正常的肾间质和肾小管结构被大量聚集的细胞外基质所替代为特征的病理过程,是多数慢性肾脏疾病进展为终末期肾衰竭共同的病变过程,其病理变化主要由多种细胞因子和多条信号通路控制,是众多关键信号通路的交互影响与共同作用的结果。深入了解信号通路的相互作用对进一步揭示肾间质纤维化的分子机制有重要意义。现综述肾间质纤维化病理变化中关键的信号通路,以期为肾间质纤维化分子机制的研究提供参考。     

巨噬细胞在小鼠肾纤维化恢复期的研究

目的:观察巨噬细胞在小鼠肾纤维化进展期和恢复期的作用。方法:采用单侧输尿管结扎(UUO)肾纤维化模型和输尿管再通模型(RUUO)进行试验研究;用Masson染色和HE染色观察肾脏纤维化程度和炎症变化趋势;流式分析肾脏中巨噬细胞细胞群的比例变化。结果:Masson染色显示肾脏纤维化程度在梗阻解除后胶原沉积面积减轻从80%降到46%,差异有统计学意义(P0.05)。HE染色显示梗阻解除后肾间质炎症减轻,且有新生小管形成。流式结果显示梗阻解除后巨噬细胞细胞群比例由19%降到2.6%,差异有统计学意义(P0.05)。结论:巨噬细胞可能在肾纤维化恢复期发挥一定作用。     

脂代谢异常对肾病的影响

肾脏疾病发展为慢性肾衰竭是个不可逆的过程,脂质代谢的异常,对肾病患者具有重要的影响。多项实验已经证实,即使在肾病的早期阶段,也会出现不同程度的脂质及脂类代谢的异常,高密度脂蛋白(HDL)、低密度脂蛋白(LDL)、脂联素、瘦素等脂类代谢相关物质发生改变,不仅对血浆脂代谢产生影响,对于肾小球及肾小管的结构及功能也会有一定的损伤作用。肾病患者,如肾病综合征、慢性肾衰竭等疾病,多数有肾小球及肾小管间质的损伤,肾脏的脂毒性加重肾单位的破坏。随着人们对于慢性肾脏病认识的逐渐深入,降脂治疗的普遍应用,人们普遍认为改善血浆中脂类的水平,对于肾病的治疗,尤其对于慢性肾衰竭的预防具有重要作用。     

TNFRSF13C 在单侧输尿管梗阻大鼠肾组织中的表达及其意义

目的：检测单侧输尿管梗阻（UUO）大鼠肾组织中B 细胞激活因子受体（TNFRSF13C）的表达变化,探讨其在肾间质纤维化 病变中的作用。方法：采用UUO法建立肾间质纤维化大鼠模型,20只成年雄性大鼠,随机分为4组,分别于术后0、3、7、14 天处死 大鼠。取左侧梗阻肾脏进行Masson染色,拍照后,采用双盲法评定各组肾小管间质纤维化程度。提取肾组织中总RNA,用实时荧 光定量聚合酶链反应（RT-PCR）法检测各组肾组织中TNFRSF13C基因表达情况。Pearson 检测TNFRSF13C表达量与肾小管间质 纤维化程度的相关性。结果：随着梗阻时间的延长,肾组织中TNFRSF13C 的mRNA 表达量进行性升高,与肾间质纤维化病变程 度一致,两者呈显著正相关（r=0.915,P<0.01）。结论：TNFRSF13C可能在肾间质纤维化病程中起到了重要作用,并有望成为慢性 肾脏病的临床监测指标。     

细胞焦亡与糖尿病肾病肾间质纤维化

肾间质纤维化是糖尿病肾病等慢性肾脏疾病进展至终末期肾病的不可逆性危险因素。细胞焦亡是一种新型程序性细胞死亡,通过诱导炎症反应的发生参与糖尿病肾病。焦亡引起的慢性炎症和纤维化被认为是糖尿病肾病发病的重要因素。因此,明确细胞焦亡与糖尿病肾病肾间质纤维化之间的关系对延缓糖尿病肾病进展至关重要。本文综述了近年来细胞焦亡在糖尿病肾病肾间质纤维化发病机制中的研究进展,以期为临床防治糖尿病肾病提供更多的理论基础。     

肾纤维化进程中的关键信号通路研究进展

肾纤维化是慢性肾脏疾病(chronic kidney disease, CKD)和慢性肾脏衰竭(chronic renal failure, CRF)发展的终末途径,CKD和CRF的治疗效果与肾纤维化的程度密切相关。探究肾纤维化的发生机制是了解CKD发展过程的重要途径。目前认为,肾纤维化的发生机制主要为肾小管上皮细胞间充质转化(epithelialmesenchymal transition, EMT)、效应细胞的激活和局部缺血、缺氧等因素影响各种信号通路,最终导致肾实质受损、肾小球滤过率下降,从而进展至慢性和终末期肾脏疾病。信号通路调控细胞核基因转录失调可能是导致肾纤维化发生的主要原因之一。TGF-β、Wnt、Notch和Hedgehog信号通路是目前研究肾纤维化的主要通路,这些信号通路通过独立或交互作用来调节肾纤维化的发生发展,但其具体机制尚不完全清楚。现就以上信号通路如何响应肾脏损伤进而调节肾纤维化进程进行综述。     

β-转化生长因子与肝细胞生长因子在肾间质纤维化中的关系

肾间质纤维化是各种慢性肾脏疾病的最终通路。研究发现,β-转化生长因子与肝细胞生长因子的平衡关系可能在肾间质纤维化发生发展过程中起着重要作用。     

大鼠心肌虚血再灌流后肝细胞再生因子的表达变化

肝细胞再生因子（hepatocyte growth factor, HGF）对多种细胞都具有促进增殖及运动、抗凋亡的作用,对组织器官的发育形成也起到重要作用．在肝脏、肾脏、肺、心脏等器官受损之后的修复过程中,有积极的促进再生的作用．本研究采用了心虚血再灌流大鼠模型,发现心肌细胞受损伤后 6 h 血清中HGF水平显著增高．在比较了肾脏、肺、肝脏、脾脏等组织提取液中HGF的含量之后,发现心虚血再灌流手术后,肾脏、肺、肝脏中HGF的含量变化不明显,而脾脏的提取液中HGF的含量增加显著．对脾脏组织的连续切片进行HGF与血管内皮细胞的特异性标志物von Willanbrand Factor (vWF)免疫组织化学染色研究,发现手术后脾脏中产生HGF的细胞主要为血管内皮细胞．此项研究首次阐明组织器官受损后,远端组织器官的血管内皮细胞能够增加HGF的合成和分泌,增加的HGF通过体液循环到达受损组织器官,促进其修复再生．     

Activation of PI3K-Akt-GSK3beta pathway mediates hepatocyte growth factor inhibition of RANTES expression in renal tubular epithelial cells

Hepatocyte growth factor (HGF) was recently reported to ameliorate renal inflammation in a rat model of chronic renal failure. HGF exerted its action through suppression of RANTES expression in renal tubules. In the present study, we utilized an in vitro model of human kidney proximal tubule epithelial cells (HKC) to elucidate the mechanisms of RANTES suppression by HGF. HGF significantly suppressed basal and TNF-alpha-induced mRNA and protein expression of RANTES in a time and dose dependent fashion. HGF elicited PI3K-Akt activation and inhibited GSK3, a downstream transducer of PI3K-Akt, by inhibitory phosphorylation at Ser-9. When the PI3K-Akt pathway was blocked by wortmannin, HGF inhibition of RANTES was abrogated, demonstrating that the PI3K-Akt pathway is necessary for HGF action. In addition, specific inhibition of GSK3 activity by lithium ion suppressed basal and TNF-alpha-induced RANTES expression, reminiscent of the action of HGF. To further investigate the role of GSK3 in modulating RANTES expression, we examined the effect of forced expression of wild type GSK3beta or an uninhibitable mutant GSK3beta, in which the regulatory Ser-9 residue is changed to alanine (S9A-GSK3beta) in HKC. Overexpression of wild type GSK3beta did not alter the inhibitory action of HGF on RANTES. In contrast, expression of S9A-GSK3beta abolished HGF inhibition of basal and TNF-alpha stimulated RANTES expression. These findings suggest that PI3K-Akt activation and subsequent inhibitory phosphorylation of GSK3beta are required for HGF-induced suppression of RANTES in HKC.     

Renotropic functions of hepatocyte growth factor in renal regeneration after unilateral nephrectomy.

Hepatocyte growth factor (HGF), a most potent growth factor for mature hepatocytes may act as a trigger for liver regeneration. We reported that HGF strongly stimulates DNA synthesis of rabbit renal tubular cells in secondary culture (Igawa, T., Kanda, S., Kanetake, H., Saitoh, Y., Ichihara, A., Tomita, Y., and Nakamura, T. (1991) Biochem. Biophys. Res. Commun. 174, 831-838). To investigate whether or not HGF is involved in renal regeneration, we examined changes in HGF mRNA, HGF activity, and HGF receptor in the rat kidney following unilateral nephrectomy or treatment with carbon tetrachloride (CCl4). In the intact kidney, the HGF mRNA increased markedly reaching a maximum 6 h after unilateral nephrectomy, followed by an increase of HGF activity at 12 h after the surgery. The marked increase in HGF mRNA and HGF activity was also found in the kidney of rats treated with CCl4. Results of in situ hybridization suggested that cells producing HGF in the kidney are endothelial cells. The number of HGF receptors on renal plasma membranes decreased to 30% of the normal value 12 h after unilateral nephrectomy, with no change in the Kd value. The HGF receptor was greatly diminished 24 h after the operation, and recovery to 60% of the normal level was evident 1 week after the operation. Because the decrease in HGF binding may result from internalization of the HGF receptor, the HGF may bind to its receptor in vivo and act as a mitogen for renal epithelial cells. HGF may function as a renotropic factor during renal regeneration after kidney injury.     

Marked induction of hepatocyte growth factor mRNA in intact kidney and spleen in response to injury of distant organs.

Hepatocyte growth factor (HGF) is a potent mitogen for various epithelial cells, including mature hepatocytes and renal tubular cells. Here, HGF mRNA was found to be markedly increased in non-injured kidney and spleen, when the liver or kidney in rats was injured by 70% partial hepatectomy or unilateral nephrectomy. HGF mRNA increased to 3-4 fold higher level than the normal in the kidney and spleen as well as in the remnant liver after partial hepatectomy. Similarly, HGF mRNA markedly increased in the spleen as well as in the remnant kidney after unilateral nephrectomy. These results suggest that the onset of injury to the liver or kidney may be recognized by distal non-injured organs by the signalling of a humoral factor and that HGF derived from these organs may be involved in the regeneration of liver or kidney, through an endocrine mechanism.     

Profiling of anti-fibrotic signaling by hepatocyte growth factor in renal fibroblasts

Hepatocyte growth factor (HGF) is a multifunctional growth factor affecting cell proliferation and differentiation. Due to its mitogenic potential, HGF plays an important role in tubular repair and regeneration after acute renal injury. However, recent reports have shown that HGF also acts as an anti-inflammatory and anti-fibrotic factor, affecting various cell types such as renal fibroblasts and triggering tubulointerstitial fibrosis of the kidney.The present study provides evidence that HGF stimulation of renal fibroblasts results in the activation of both the Erk1/2 and the Akt pathways. As previously shown, Erk1/2 phosphorylation results in Smad-linker phosphorylation, thereby antagonizing cellular signals induced by TGFβ. By siRNA mediated silencing of the Erk1/2-Smad linkage, however, we now demonstrate that Akt signaling acts as an auxiliary pathway responsible for the anti-fibrotic effects of HGF. In order to define the anti-fibrotic function of HGF we performed comprehensive expression profiling of HGF-stimulated renal fibroblasts by microarray hybridization. Functional cluster analyses and quantitative PCR assays indicate that the HGF-stimulated pathways transfer the anti-fibrotic effects in renal interstitial fibroblasts by reducing expression of extracellular matrix proteins, various chemokines, and members of the CCN family.     

Hepatocyte growth factor preferentially activates the anti-inflammatory arm of NF-κB signaling to induce A20 and protect renal proximal tubular epithelial cells from inflammation

Inflammation induces the NF-κB dependent protein A20 in human renal proximal tubular epithelial cells (RPTEC), which secondarily contains inflammation by shutting down NF-κB activation. We surmised that inducing A20 without engaging the pro-inflammatory arm of NF-κB could improve outcomes in kidney disease. We showed that hepatocyte growth factor (HGF) increases A20 mRNA and protein levels in RPTEC without causing inflammation. Upregulation of A20 by HGF was NF-κB/RelA dependent as it was abolished by overexpressing IκBα or silencing p65/RelA. Unlike TNFα, HGF caused minimal IκBα and p65/RelA phosphorylation, with moderate IκBα degradation. Upstream, HGF led to robust and sustained AKT activation, which was required for p65 phosphorylation and A20 upregulation. While HGF treatment of RPTEC significantly increased A20 mRNA, it failed to induce NF-κB dependent, pro-inflammatory MCP-1, VCAM-1, and ICAM-1 mRNA. This indicates that HGF preferentially upregulates protective (A20) over pro-inflammatory NF-κB dependent genes. Upregulation of A20 supported the anti-inflammatory effects of HGF in RPTEC. HGF pretreatment significantly attenuated TNFα-mediated increase of ICAM-1, a finding partially reversed by silencing A20. In conclusion, this is the first demonstration that HGF activates an AKT-p65/RelA pathway to preferentially induce A20 but not inflammatory molecules. This could be highly desirable in acute and chronic renal injury where A20-based anti-inflammatory therapies are beneficial.     

The alleviation of acute and chronic kidney injury by human Wharton's jelly-derived mesenchymal stromal cells triggered by ischemia-reperfusion injury via an endocrine mechanism

Background aimsThe effects of human Wharton's jelly-derived mesenchymal stromal cells (WJ-MSC) on acute and chronic kidney injury induced by ischemia-reperfusion injury (IRI) were assessed.MethodsWJ-MSC were injected intravenously immediately after solitary kidney ischemia for 45 min. Cells were labeled with 5-bromo-2′deoxy-uridine (BrdU) for tracing in vivo. At 48 h post-IRI, serum creatinine and blood urea nitrogen (BUN) were measured. Tubular cell proliferation and apoptosis as well as activation of the Akt signal were identified by immunostaining. Real-time polymerase chain reaction (PCR) was employed to determine gene expression of inflammation-related cytokines and hepatocyte growth factor (HGF). Levels of human HGF were assayed by enzyme-linked immunosorbant assay (ELISA). Twenty-two weeks later, renal fibrosis was assessed by Masson's tri-chrome staining, collagen content and α-smooth muscle actin (α-SMA) staining.ResultsThere was no sign of labeled cells residing in the damaged kidney. Acute renal dysfunction elicited by IRI was considerably improved by WJ-MSC, in parallel with a stronger proliferative response and less apoptotic events. Additionally, phosphoAkt staining in injured tubular cells was substantially intensified. Cell treatment also caused a remarkable up-regulation of kidney interleukin (IL)-10, heme oxygenase (HO)-1 and HGF expression. Human HGF was detected in cell supernatants and the serum of cell-infused rats. Moreover, IRI-initiated fibrosis was abrogated by cell therapy, coincident with function amelioration.ConclusionsWJ-MSC alleviate acute kidney injury, thereby rescuing the ensuing fibrotic lesions in an endocrine manner. The Akt signal in impaired tubular cells is reinforced by WJ-MSC, facilitating cell resistance to apoptosis and cell proliferation. HGF, either delivered or induced by WJ-MSC, is an important contributor.     

Augmenter of liver regeneration ameliorates renal fibrosis in rats with obstructive nephropathy

Renal fibrosis is a hallmark in CKD (chronic kidney disease) and is strongly correlated to the deterioration of renal function that is characterized by tubulointerstitial fibrosis, tubular atrophy, glomerulosclerosis and disruption of the normal architecture of the kidney. ALR (augmenter of liver regeneration) is a growth factor with biological functions similar to those of HGF (hepatocyte growth factor). In this study, our results indicate that endogenous ALR is involved in the pathological progression of renal fibrosis in UUO (unilateral ureteral obstruction) rat model. Moreover, we find that administration of rhALR (recombinant human ALR) significantly alleviates renal interstitial fibrosis and reduces renal-fibrosis-related proteins in UUO rats. Further investigation reveals that rhALR suppresses the up-regulated expression of TGF-β1 (transforming growth factor β1) induced by UUO operation in the obstructed kidney, and inhibits Smad2 and Smad3 phosphorylation activated by the UUO-induced injury in the animal model. Therefore we suggest that ALR is involved in the progression of renal fibrosis and administration of rhALR protects the kidney against renal fibrosis by inhibition of TGF-β/Smad activity.     

Taurine: A therapeutic agent in experimental kidney disease

Summary Taurine is an abundant free amino acid in the plasma and cytosol. The kidney plays a pivotal role in maintaining taurine balance. Immunohistochemical studies reveal a unique localization pattern of the amino acid along the nephron. Taurine acts as an antioxidant in a variety ofin vitro andin vivo systems. It prevents lipid peroxidation of glomerular mesangial cells and renal tubular epithelial cells exposed to high glucose or hypoxic culture conditions. Dietary taurine supplementation ameliorates experimental renal disease including models of refractory nephrotic syndrome and diabetic nephropathy. The beneficial effects of taurine are mediated by its antioxidant action. It does not attenuate ischemic or nephrotoxic acute renal failure or chronic renal failure due to sub-total ablation of kidney mass. Additional work is required to fully explain the scope and mechanism of action of taurine as a renoprotective agent in experimental kidney disease. Clinical trials are warranted to determine the usefulness of this amino acid as an adjunctive treatment of progressive glomerular disease and diabetic nephropathy.     

Expressions of receptor gene for hepatocyte growth factor in kidney after unilateral nephrectomy and renal injury.

The renal expressions of the receptor gene (c-met) for hepatocyte growth factor (HGF) were examined in unilateral nephrectomy (UNX), renal ischemia or folic acid administration. The levels of c-met mRNA were increased rapidly in all rat models at 6h after the operations. On the other hand, the expression of c-met mRNA in a kidney cell line (MDCK cells) was down-regulated for 8 h after HGF addition, indicating that c-met mRNA induction in rat models may be independent of the stimulated production of HGF. The stimulated expression of c-met in these models suggest that HGF may play an important role in renal hypertrophy after UNX and regeneration after ischemic or nephrotoxic injury.