Paradoxical body and kidney growth in potassium deficiency

In the growing animal, K deficiency (KD) retards body growth, but paradoxically stimulates renal growth. If KD persists, interstitial infiltrates appear and eventually tubulointerstitial fibrosis develops. In patients with chronic KD, renal cysts may form and with time tubulointerstitial disease with renal failure develops. Since early in KD, kidney IGF-I levels increase and may be a cause of the renal hypertrophy, and as TGF-beta promotes hypertrophy and fibrosis, we examined the expression of these growth factors in chronic KD. Rats were given a KD diet or pair or ad-lib fed a normal K diet. After 21 days, KD rats weighed less than pair fed controls, while the kidneys were 49% larger Serum IGF-I and kidney IGF-I protein levels were depressed, as were IGF-I mRNA levels, and is largely attributable to decreased food intake. Kidney IGFBP-1 and TGF-beta mRNA levels were increased (p < 0.05). There was marked hypertrophy and adenomatous hyperplasia of outer medullary collecting ducts, hypertrophy of thick ascending limbs of Henle (TALH) and interstitial infiltrates. Both nephron segments stained strongly for IGF-I and IGFBP-1. Only the non-hyperplastic TALH was strongly TGF-beta positive. Interstitial infiltrates containing monocytes/macrophages were prominent. These findings are consistent with a sustained role for IGF-I in promoting the renal hypertrophy of KD and appear to be caused by local trapping of IGF-I by the over-expressed IGFBP-1. Localization of TGF-beta to the hypertrophied non-hypoplastic tubules containing IGF-I, suggests that TGF-beta may be acting to convert the proliferative action of IGF-I into a hypertrophic response. TGF-beta may also contribute to the genesis of the tubulointerstitial infiltrate. Finally, the reduced levels of serum IGF-1 levels may be a cause of the blunted body growth.     

Expression of insulin-like growth factor-I and transforming growth factor-beta in hypokalemic nephropathy in the rat

BACKGROUND: Potassium deficiency (KD) in the rat retards body growth but stimulates renal enlargement caused by cellular hypertrophy and hyperplasia, which is most marked in the outer medulla. If hypokalemia persists, interstitial infiltrates appear and eventually fibrosis. Since early in KD insulin-like growth factor-I (IGF-I) levels in the kidney are elevated, suggesting that it may be an early mediator of the exaggerated renal growth, and as transforming growth factor-beta (TGF-beta) promotes cellular hypertrophy and fibrosis, we examined the renal expression of these growth factors in prolonged KD. METHODS: Rats were given a K-deficient diet or were pair fed or ad libitum fed a K-replete diet for 21 days. Growth factor mRNA levels were measured in whole kidney and protein expression localized by immunohistochemistry. RESULTS: KD rats weighed less than pair-fed controls, while the kidneys were 49% larger. Their serum IGF-I and kidney IGF-I protein levels were depressed, as were their IGF-I mRNA levels in liver, kidney, and muscle. These changes can largely be attributed to decreased food intake. In contrast, kidney IGF binding protein-1 (IGFBP-1) mRNA and TGF-beta mRNA levels were increased significantly. Histology of outer medulla revealed marked hypertrophy and adenomatous hyperplasia of the collecting ducts and hypertrophy of the thick ascending limbs of Henle with cellular infiltrates in the interstitium. Both nephron segments immunostained strongly for IGF-I and IGFBP-1, but only the nonhyperplastic enlarged thick ascending Henle limb cells immunostained for TGF-beta, which was strongly positive. Prominent interstitial infiltrates with ED1 immunostained monocytes/macrophages were present. CONCLUSIONS: These findings are consistent with a sustained role for IGF-I in promoting the exaggerated renal growth of KD and appear to be mediated through local trapping of IGF-I by the overexpressed IGFBP-1, which together with IGF-I can promote renal growth. The selective localization of TGF-beta to hypertrophied nonhyperplastic nephron segments containing IGF-I raises the possibility that TGF-beta may be serving to convert the mitogenic action of IGF-I into a hypertrophic response in these segments. It is also conceivable that TGF-beta may be a cause of the tubulointerstitial infiltrate. Finally, the low circulating IGF-I levels likely contribute to the impaired body growth.     

How Does TGF-β Mediate Tubulointerstitial Fibrosis?

Tubulointerstitial fibrosis mediates the development of end-stage renal disease from renal injuries of all etiologies and is considered an important predictor of renal survival. Transforming growth factor-β (TGF-β) is one of the most important growth factors that promotes tubulointerstitial fibrosis, but the mechanisms whereby this occurs are not well defined. This is because TGF-β has pleiotropic effects that depend on the target cell type. This review discusses how TGF-β signaling in each of the relevant cell types (eg, tubular epithelium, fibroblasts) may contribute to tubulointerstitial fibrosis progression and suggests ways in which future research can improve our understanding of TGF-β-mediated tubulointerstitial fibrosis.     

Preferential expression of insulin-like growth factor binding proteins-1, -3, and -5 during early diabetic renal hypertrophy in rats

The renal insulin-like growth factor-I (IGF-I) system has been implicated in the pathogenesis of renal hypertrophy, altered hemodynamics, and extracellular matrix expansion associated with early diabetes. The relative abundance of IGF binding proteins (IGFBPs) in the renal microenvironment may modulate IGF-I actions. However, the precise IGFBPs expressed in the glomerular and tubulointerstitial compartments during diabetic renal growth have not been characterized. In the present study, in situ hybridization studies were performed to examine the expression of IGFBP-1 to -6 messenger RNAs (mRNAs) 3, 7, and 14 days after streptozotocin (STZ) injection in rats. In control, nondiabetic kidneys, all six IGFBP mRNAs were differentially expressed with a predominance of IGFBP-5. The onset of renal hypertrophy in STZ-induced diabetes was associated with a rapid and site-specific induction of IGFBP-1, -3, and -5 mRNAs. In contrast, basal expression of IGFBP-2, -4, and -6 mRNAs was not altered in diabetic rats. IGFBP-5 mRNA expression increased in diabetic glomeruli, cortical, and inner medullary peritubular interstitial cells at days 3, 7, and 14. Although normal glomeruli failed to express IGFBP-3, it was induced concomitantly with IGFBP-5 in diabetic glomeruli and cortical peritubular interstitial cells. IGFBP-1 mRNA levels also increased in cortical tubular cells at each time point tested. Peak induction of IGFBP-3 and -5 was observed at day 3, whereas IGFBP-1 was delayed until day 7. IGFBP-1, -3, and -5 mRNA levels declined by day 14, but remained persistently elevated above control. By immunoperoxidase staining, similar alterations in the pattern of IGFBP-3 and -5 protein expression were observed at each time point. The preferential and site-specific increase in IGFBP-1, -3, and -5 suggest that these IGFBPs may regulate the local autocrine and/or paracrine actions of IGF-I and contribute to the pathogenesis of the early manifestations of diabetic nephropathy.     

Juxtaglomerular cell tumor with retroperitoneal fibrosis and secondary immune-complex glomerulonephritis: A possible contribution of the renin angiotensin system to renal fibrosis

We present a case of a 25-year-old woman with a renin-secreting juxtaglomerular cell tumor, retroperitoneal fibrosis associated with glomerular hypertrophy, glomerulonephritis, and marked tubulointerstitial alterations. Myofibroblasts, as shown by positive immunostaining for α-smooth muscle actin, were found along with transforming growth factor-beta (TGF-β) in the interstitium of the tumor-free kidney. Regarding the pathogenesis of renal fibrosis and glomerular hypertrophy, this case may provide evidence not only experimentally but also clinically that the renin-angiotensin system plays an important role because angiotensin II is known to induce renal fibrosis associated with increased TGF-β and the appearance of myofibroblasts.     

骨形成蛋白7和转化生长因子β1在不同病理类型IgA肾病的变化

目的 观察转化生长因子β1（TGF-β1）和骨形成蛋白7（BMP-7）在不同病理类型IgA肾病的变化,并探讨其意义。方法 89例IgA肾病患者分成3组：A组为47例轻度系膜增生性IgA肾病;B组为29例中重度系膜增生性IgA肾病;C组为13例增生硬化或硬化性IgA肾病。检测患者的血压、尿蛋白量（24 h）、Scr和Ccr。免疫组化和ELISA方法测定患者肾组织冰冻切片及其血、尿中TGF-β1和BMP-7水平。计算患者病理切片硬化肾小球数、新月体数和间质纤维化面积百分比。结果 随着IgA肾病患者肾小球病变的加重,肾小管萎缩和肾间质纤维化增多,其血压、尿蛋白量（24 h）、Scr逐渐增加,除B、C两组间尿蛋白量（24 h）无显著差异外,其余各组间差异均有统计学意义（P＜0．05）。与A组比较,B组肾组织及血、尿TGF-β1明显增多,C组显著降低（P＜0．01）。肾组织冰冻切片及血、尿BMP-7随着肾脏病变的加重,水平逐渐下降（P＜0．01）;而且与Ccr呈正相关;与血压、Scr、尿蛋白量（24 h）、硬化肾小球数、新月体数、肾间质纤维化面积呈负相关。结论 TGF-β1在IgA肾病系膜增生严重时明显增加,肾脏广泛纤维化时明显降低,可能参与了IgA肾病肾间质纤维化的发生。BMP-7随肾脏病变的加重而明显降低,可能导致其抗肾纤维化作用减弱。     

Suramin inhibits renal fibrosis in chronic kidney disease

The activation of cytokine and growth factor receptors associates with the development and progression of renal fibrosis. Suramin is a compound that inhibits the interaction of several cytokines and growth factors with their receptors, but whether suramin inhibits the progression of renal fibrosis is unknown. Here, treatment of cultured renal interstitial fibroblasts with suramin inhibited their activation induced by TGF-β1 and serum. In a mouse model of obstructive nephropathy, administration of a single dose of suramin immediately after ureteral obstruction abolished the expression of fibronectin, largely suppressed expression of α-SMA and type I collagen, and reduced the deposition of extracellular matrix proteins. Suramin also decreased the expression of multiple cytokines including TGF-β1 and reduced the interstitial infiltration of leukocytes. Moreover, suramin decreased expression of the type II TGF-β receptor, blocked phosphorylation of the EGF and PDGF receptors, and inactivated several signaling pathways associated with the progression of renal fibrosis. In a rat model of CKD, suramin abrogated proteinuria, limited the decline of renal function, and prevented glomerular and tubulointerstitial damage. Collectively, these findings indicate that suramin is a potent antifibrotic agent that may have therapeutic potential for patients with fibrotic kidney diseases.     

Insulin-like growth factor-I and insulin-like growth factor-binding proteins in the nephrotic syndrome

Similar to findings in the nephrotic syndrome in humans, rats with the doxorubicin-induced nephrotic syndrome (which resembles minimal change disease) have reduced serum levels of insulin-like growth factor-I (IGF-I). This is mainly caused by glomerular ultrafiltration of IGF-I-containing binding protein complexes, primarily of a molecular weight of approximately 50 kilodaltons, and urinary losses of the peptide. Despite urinary excretion of IGF-binding protein (IGFBP)-2, serum levels are increased more than twofold in the nephrotic syndrome compared with controls, because of increased synthesis of this binding protein by the liver. In contrast, the liver synthesis of IGFBP-3, the predominant binding protein in normal serum, is unchanged in the nephrotic syndrome. However, binding and serum levels of IGFBP-3 are reduced in nephrotic rat serum, apparently due to proteolytic degradation of IGFBP-3. The glomerular ultrafiltration of IGF-I, which leads to biologically significant IGF-I concentrations of about 1.35 nM in proximal tubule fluid, may have metabolic consequences, such as increased tubular phosphate absorption. Hypothetically, tubule fluid IGF-I may also contribute to progressive tubulointerstitial fibrosis which is sometimes present in protractive nephrotic glomerulopathies. The profound changes in the IGF-I/IGFBP system in the nephrotic syndrome may also contribute to systemic metabolic abnormalities and growth failure.     

Effect of thymosin β4 on transforming growth factor-β/connective tissue growth factor of renal tubular interstitial fibrosis rats

Objective To investigate the influence of thymosin beta 4 (Tβ4) with two different dosages on the expression of transforming growth factor beta (TGF-β) and connective tissue growth factor (CTGF) in rats with renal tubular interstitial fibrosis, and to further estimate the changes of renal tubular interstitial lesions. Methods Rat models of renal tubular interstitial fibrosis were established by unilateral ureteral occlusion (UUO). The male SD rats were randomly divided into 4 groups and 15 rats in each group: sham group, model group, treatment group with 1 mg/L Tβ4 and treatment group with 5 mg/L Tβ4. Rats in sham group and model group were poured into the same amount of saline. The renal function and renal pathological changes were observed after the second week. The mRNA and protein expression of TGF-β and CTGF in renal tissues was tested by in-situ hybridization and Western blotting. Results Compared with that in sham group, the expression of TGF-β mRNA and its protein, CTGF mRNA and its protein was significantly higher in model group (all P＜0.01). Compared with rats of model group, Tβ4 treatment rats had lower mRNA and protein expression of TGF-β and CTGF (all P＜0.01), and the expression in treatment group with 5 mg/L Tβ4 was lower than that in treatment group with 1 mg/L Tβ4 (P＜0.05). And the expression of TGF-β mRNA was positively correlated with CTGF mRNA expression (r=0.697, P＜0.01). The 24 h total urinary protein and the area of renal tubular interstitial lesion in model group were significantly more than those in sham group, and also more than those in Tβ4 treatment group (all P＜0.05). Tβ4 treatment attenuated kidney damage, and the effects in treatment group with 5 mg/L Tβ4 were better than those in treatment group with 1 mg/L Tβ4. No difference in serum creatinine and blood urea nitrogen was observed among 4 groups (all P＞0.05). Conclusions Tβ4 treatment can inhibit the renal TGF-β and CTGF expression of rats with tubular interstitial fibrosis in a dose-dependent manner, and play a protective role in kidney.     

STAT3抑制剂S3I－201对实验性肾小管间质纤维化的保护作用

目的探讨STAT3抑制剂S3I－201对小鼠实验性肾小管间质纤维化的保护作用。 方法采用单侧输尿管梗阻手术的方法建立肾小管间质纤维化模型。将实验小鼠随机分为药物假手术组(Sham＋S3I－201),安慰剂假手术组(Sham＋Vehicle),药物造模组(UUO＋S3I－201),安慰剂造模组(UUO＋Vehicle)4组,通过腹腔注射S3I－201溶液(药物)或0.05%DMSO PBS(安慰剂)给药,每天给药一次。造模第7天时留取肾脏标本,用Masson染色和颜色面积测算法评估胶原蛋白沉积的情况。用qRT－PCR法检测肾组织内趋化因子配体16(CXCL16),白介素－1β(IL－1β),细胞间黏附分子1(ICAM－1),转化生长因子－β(TGF－β),肿瘤坏死因子(TNF－α)的mRNA表达,用免疫组化法染色和免疫印迹法检测PDGFRβ蛋白在梗阻肾脏内的表达。 结果UUO＋Vehicle小鼠的肾间质胶原蛋白沉积显著高于Sham＋Vehicle组(P<0.05)。UUO＋Vehicle小鼠肾组织CXCL16,IL－1β,ICAM－1,TGF－β,TNF－α的mRNA表达显著高于Sham＋Vehicle组(P<0.05),UUO＋Vehicle小鼠肾组织血小板来源生长因子受体β(PDGFRβ)蛋白表达显著高于Sham＋Vehicle组(P<0.05)。经过S3I－201治疗7 d后,UUO＋S3I－201小鼠的上述各项指标均显著低于UUO＋Vehicle(P<0.05)。 结论S3I－201通过抑制多种细胞因子的mRNA表达,以及降低PDGFRβ蛋白的表达,减轻实验性肾小管间质纤维化小鼠的肾间质炎症反应,从而发挥肾脏保护作用。     

美沙拉嗪对单侧输尿管梗阻大鼠肾间质NF—kB和TGF—β1表达的影响

目的观察单侧输尿管梗阻大鼠模型肾间质核因子-kB（NF-kB）、转化生长因子β1（TGF-β1）的表达变化,探讨美沙拉嗪干预后对其表达的影响。方法将30只雌性SD大鼠随机分为假手术组（SOR组）、模型组（UUO组）、美沙拉嗪治疗组（MES组）,每组10只。建立单侧输尿管梗阻大鼠模型72h后灌胃给药：MES组给予美沙拉嗪（200mg·kg-1·d-1）灌胃给药;SOR组、UUO组给予等量生理盐水灌胃给药。建模成功后第10天检测各组血肌酐、尿素氮,并取梗阻侧。肾组织,行HE及Masson染色观察肾脏病理变化;免疫组织化学检测NF-xBp65和TGF-β1在肾间质的表达和变化。结果①UUO组术后第10天梗阻侧肾脏肾小管间质损害指数明显高于SOR组（P〈0．01）,MES组则低于UUO组（P〈0．05）。②UUO组大鼠。肾间质NF-kB p65及TGF-β1表达增加,明显高于SOR组（P〈0．01）,MES组则低于UUO组（P〈0．05）。结论单侧输尿管梗阻大鼠模型肾脏存在肾小管间质的炎症损伤和纤维化,美沙拉嗪通过抑制NF-kB p65和TGF-β1表达而减轻肾间质炎性损害和纤维化。     

Serum insulin-like growth factors and their binding proteins in children with end-stage renal disease

Serum levels of insulin-like growth factor-I (IGF-I), IGF-II, and IGF binding protein-1 (IGFBP-1), IGFBP-2, and IGFBP-3 were measured in 54 children with end-stage renal disease (ESRD). The results were compared with their respective age-dependent normal ranges. IGFs and IGFBPs were quantified by specific radioimmunoassay. Serum IGF-I in children with ESRD tended to cluster in the low-normal range. Mean age-related serum IGF-I levels were slightly, but significantly decreased (–1.08±0.17 SDS). In view of the prevailing elevated growth hormone levels in ESRD, these serum, IGF-I levels must be interpreted as inadequately low. In contrast to IGF-I, individual serum IGF-II levels were either in the uppernormal range or clearly elevated. Mean age-related IGF-II (1.09±0.15 SDS) was lightly, but significantly elevated. Mean age-related IGFBP-1 serum levels (2.20±0.10 SDS) were moderately increased, while mean age-related serum IGFBP-2 (5.65±0.36) and IGFBP-3 levels (3.60±0.19) were markedly elevated. Affinity cross-linking of¹²⁵iodine-IGF-II to sera from patients with ESRD and immunoprecipitation with a specific antiserum showed that low molecular weight IGFBP-3 fragments in ESRD serum are capable of binding IGF. In patients with ESRD, a rapid and persistent decline of immunoreactive IGFBP-3 in response to restoration of renal function by renal transplantation was observed. This finding indicates that renal dysfunction contributes to high immunoreactive, IGFBP-3 levels in ESRD. In conclusion, the imbalance between normal total IGF levels and the excess of IGFBPs in ESRD is likely to play a role in growth failure in these children.     

急性缺血再灌注损伤对肾脏的近期和远期作用

目的 探讨急性缺血再灌注（IR）损伤对大鼠肾脏的近期和远期作用及其机制。 方法 双侧肾蒂夹闭40 min后再灌注，制作大鼠IR模型。术后4 h、24 h、48 h、72 h、1周、5周和10周收集血样和肾脏标本，动态观察肾脏病理、肾功能和大鼠死亡情况。用透射电镜观察小管上皮细胞的超微结构；原位末端标记法（TUNEL）检测肾小管上皮细胞凋亡情况；Masson染色法观察小管间质纤维化程度；Western印迹法测定α?鄄平滑肌肌动蛋白(α-SMA)表达；免疫组织化学法观察肾脏α-SMA和转化生长因子β1 (TGF-β1)的分布和表达。 结果　 再灌注后IR组的Scr 和BUN水平逐渐升高，48 h达到最高峰。IR组病死率为32% (8/25)，假手术（Sham）组病死率为0 (0/22)。再灌注48 h IR组出现近端肾小管上皮细胞广泛性坏死和少量凋亡；IR组术后5周和10周有轻至中度的小管间质纤维化，术后1周肾脏α-SMA和TGF-β1蛋白表达显著升高，以后两者表达有所下降但仍高于Sham组。 结论 严重的缺血再灌注损伤不仅是早期肾小管大量坏死、肾功能急剧下降和病死率增高的原因，而且可以导致小管间质纤维化，影响肾脏的远期预后。TGF-β1过表达和肌成纤维细胞增多可能介导了纤维化病变。     

补体C5α受体和转化生长因子-β1在大鼠肾间质纤维化不同阶段肾组织的表达

目的：动态观测补体C5α受体（C5αR）和转化生长因子β1（TGF-β1）在单侧输尿管梗阻（UUO）大鼠肾组织的表达变化,从而探讨C5αR在。肾小管间质纤维化发生中的作用机制。方法：将36只雄性SPF级SD大鼠随机分为模型组及假手术组。模型组行UUO术,假手术组仅游离输尿管,不结扎。术后第5、10、15天分别处死每组中的6只大鼠,取梗阻侧肾行苏木精-伊红（H—E）和Masson染色,并用免疫组织化学ELiVision^TMplus法检测肾小管间质中C5αR和TGF-β1的表达。结果：模型组第5天肾小管扩张,小管间质细胞部分变性,第10天小管间质细胞可见坏死,间质纤维增多,第15天可见弥漫的肾小管基底膜增厚皱缩,纤维化明显（P〈0．05）。免疫组织化学结果显示：假手术组大鼠肾小管间质中仅有少量TGF-β1和C5αR表达,随时间延长未见明显变化;模型组大鼠梗阻侧肾组织中C5αR和TGF-β1的表达随时间进展而明显增加（P〈0．05）,其中C5αR在梗阻早期（第5～10天）表达明显增多,而晚期（第11～15天）仅轻微增多。结论：模型组实验大鼠梗阻侧。肾组织中C5αR和TGF-β1表达随着梗阻时间延长而上调,提示C5αR可能在。肾间质纤维化早期通过介导TGF-β1的上调发挥作用。     

Heterogeneous nuclear ribonucleoprotein f suppresses angiotensinogen gene expression and attenuates hypertension and kidney injury in diabetic mice

We investigated the impact of heterogeneous nuclear ribonucleoprotein F (hnRNP F) overexpression on angiotensinogen (Agt) gene expression, hypertension, and renal proximal tubular cell (RPTC) injury in high-glucose milieu both in vivo and in vitro. Diabetic Akita transgenic (Tg) mice specifically overexpressing hnRNP F in their RPTCs were created, and the effects on systemic hypertension, Agt gene expression, renal hypertrophy, and interstitial fibrosis were studied. We also examined immortalized rat RPTCs stably transfected with control plasmid or plasmid containing hnRNP F cDNA in vitro. The results showed that hnRNP F overexpression attenuated systemic hypertension, suppressed Agt and transforming growth factor-β1 (TGF-β1) gene expression, and reduced urinary Agt and angiotensin II levels, renal hypertrophy, and glomerulotubular fibrosis in Akita hnRNP F-Tg mice. In vitro, hnRNP F overexpression prevented the high-glucose stimulation of Agt and TGF-β1 mRNA expression and cellular hypertrophy in RPTCs. These data suggest that hnRNP F plays a modulatory role and can ameliorate hypertension, renal hypertrophy, and interstitial fibrosis in diabetes. The underlying mechanism is mediated, at least in part, via the suppression of intrarenal Agt gene expression in vivo. hnRNP F may be a potential target in the treatment of hypertension and kidney injury in diabetes.     

肾淋巴循环障碍致肾小管间质纤维化及对转化生长因子β1和Smad2/3表达的影响

目的 探讨肾淋巴循环障碍对大鼠肾小管间质纤维化的作用及其与TGF-β1、Smad2/3表达变化的关系。 方法 雄性Wistar大鼠48只，随机分为淋巴循环障碍模型组和假手术对照组各24只。分别在术后1、2、4、8周每组各处死6只。测定尿蛋白量（24 h）和Scr。PAS和Masson染色观察肾组织病理改变。用实时PCR检测TGF-β1、Smad2/3、I型胶原（ColⅠ）mRNA的表达量。用免疫组化和（或）Western 印迹方法检测肾组织ColⅠ、TGF-β1、Smad2/3和磷酸化Smad2/3（p-Smad2/3）的蛋白表达量及主要表达部位。 结果 模型组大鼠尿蛋白显著增加，随着时间推移肾功能逐渐减退，并出现明显的组织病理改变，小管间质损伤指数明显高于对照组（P < 0.05或P < 0.01），并随时间延长而逐渐加重。肾组织中ColⅠ、TGF-β1、Smad2/3、p-Smad2/3的蛋白和（或）基因表达水平也明显增高（P < 0.01），且主要表达在肾小管上皮细胞及肾间质。 结论 肾淋巴循环障碍可导致大鼠肾脏功能及小管间质的损害，并随着时间的延长而加重。其作用机制可能与激活TGF-β-Smad途径，导致肾小管间质纤维化有关。     

Aminoguanidine ameliorates changes in the IGF system in experimental diabetic nephropathy.

BACKGROUND: Formation of advanced glycation end-products (AGEs) has been implicated in the development of diabetic complications. As well as causing changes in structural proteins, AGEs may also alter gene expression of growth factors in vitro. The insulin-like growth factor (IGF) system, including IGF-I and modulatory IGF binding proteins (IGFBPs), is dysregulated during the development of diabetic nephropathy. METHODS: Quantitative in situ hybridization histochemistry and immunohistochemistry were used to determine the effects of aminoguanidine, an inhibitor of AGE formation, on gene expression of IGF-I and IGFBPs in kidneys of long-term (8 months duration) streptozotocin-diabetic rats. RESULTS: Diabetes was associated with increased renal expression of IGFBP-1 mRNA (diabetes 824+/-236 vs control 264+/-76 arbitrary units, P<0.01) and decreased expression of mRNAs for IGF-I (diabetes 39+/-7 vs control 185+/-23 arbitrary units, P<0.001) and IGFBP-4 (diabetes 139+/-25 vs control 383+/-54 arbitrary units, P<0.001). Aminoguanidine treatment inhibited the effects of diabetes on renal expression of mRNA for IGF-I, IGFBP-1 and IGFBP-4. The changes in IGF-I and IGFBP-1 mRNA levels were reflected in altered peptide levels. In diabetic kidneys, IGFBP-5 mRNA levels were slightly decreased to 75% of control levels (P<0.01); aminoguanidine had no effect on IGFBP-5 mRNA levels. CONCLUSIONS: These results suggest that amelioration of changes in the renal IGF system by aminoguanidine may contribute to the renoprotective effects of the latter, which have been previously shown to inhibit structural and functional aspects of diabetic nephropathy in the rat.     

血管内皮生长因子C参与肾间质纤维化的进程

目的探讨血管内皮生长因子C（VEGF-C）在大鼠。肾小管上皮细胞向间充质细胞转化（EMT）过程中的变化及其作用通路,并利用动物模型研究血管紧张素Ⅱ受体拮抗剂替米沙坦对VEGF-C的影响,从而探讨VEGF-C在肾间质纤维化中的作用。方法体外培养大鼠肾小管上皮细胞（NRK52E）,用转化生长因子B1（TGF-β1）孵育不同时间,观察其对VEGF-C、上皮型钙黏蛋白（E-cadherin）、波形蛋白（vimentin）、磷酸化AKT（P-AKT）等表达的影响,并在TGF-131作用同时加入PBK抑制剂Wortmannin,观察上述指标的变化;用单侧输尿管结扎术（UUO）制作SD大鼠肾间质纤维化模型,将21只大鼠随机分为假手术组、模型组和替米沙坦治疗组,每组7只。2周后,用免疫组织化学法检测α平滑肌肌动蛋白（mSMA）及VEGF-C在肾组织的分布,用RT-PCR和Westernblot—ring法检测其mRNA和蛋白表达。结果TGF-β1促进EMT的同时促进VEGF-C的表达增加。加入Wortmannin后EMT被抑制,同时VEGF-C的表达减低。动物模型组α-SMA和VEGF-C表达较假手术组高,替米沙坦治疗组α-SMA和VEGF-C表达较模型组低。结论TGF-β1可通过P13K—AKT通路促进VEGF-C的表达,VEGF-C与α-SMA的变化有同步性,提示VEGF-C可能参与肾间质纤维化的进程。     

转化生长因子-β和碱性成纤维细胞因子在儿童原发性局灶节段性肾小球硬化肾组织中的表达

目的：通过检测转化生长因子-β（TGF-β）和碱性成纤维细胞生长因子（bFGF）在儿童原发性局灶节段性肾小球硬化（FSGS）肾组织中的表达情况,并分析其与肾小管间质病理变化的关系,以了解TGF-β与bFGF在原发性FSGS发生发展中的作用。方法：选择肾活检明确诊断为原发性FSGS患儿的肾组织共43例,其中不伴有肾小管间质病变的FSGS肾组织共16例,设为实验1组;伴有肾小管间质病变的FSGS肾组织共27例,为实验2组。另将同期因孤立性血尿入院肾活检证实为非FSGS、病理改变较轻的肾组织作为对照组,共17例。采用免疫组化法检测细胞/生长因子TGF-β、bFGF在各组中的表达。通过方差分析（ANOVA）和相关分析法分析细胞/生长因子的表达与FSGS肾组织病理变化的关系以及细胞/生长因子之间的相互作用关系。结果：TGF-β、bFGF在各组肾组织中均有表达,表达量在对照组、实验1组和实验2组中依次升高,各组间的差异均具有统计学意义（P〈0.05）;且TGF-β和bFGF的表达与肾小管间质指数呈正相关,相关系数依次为0.763和0.661。此外,TGF-β和bFGF两者的表达量经相关分析也显示呈正相关,相关系数为0.587。结论：TGF-β和bFGF在原发性FSGS患儿肾组织中高表达;随着FSGS的发展,它们在肾组织中表达量不断增加,促使肾小管间质向纤维化发展,而且两者在促进肾脏纤维化具有一定的协同作用。