Fluvastatin suppresses oxidative stress and fibrosis in the interstitium of mouse kidneys with unilateral ureteral obstruction

BACKGROUND: Recently, we demonstrated increased oxidative stress in the interstitium of ureteral obstructed kidneys based on the increased expression of heme oxygenase-1 and immunohistochemical detection of advanced glycation end products (AGE) in the interstitium. Antioxidant therapy may have a therapeutic potential toward interstitial fibrosis of unilateral ureteral obstruction (UUO) kidneys. Fluvastatin is an HMG-CoA reductase inhibitor and has been demonstrated to have an antioxidant activity in vitro. METHODS: The effects of fluvastatin on UUO kidneys from the viewpoints of antioxidant action in vivo and antifibrosis action were studied. To investigate the antioxidant action and its therapeutic efficacy of fluvastatin in UUO kidneys, AGE accumulation and fibrosis in the obstructed kidneys was compared among vehicle-, pravastatin-, or fluvastatin-treated (10 or 40 mg/kg/day) groups. RESULTS: Tubulointerstitial fibrosis was significantly attenuated in fluvastatin-treated animals. Fluvastatin significantly suppressed the degree of immunostaining of AGE in UUO kidneys. CONCLUSIONS: These results provide evidence for the antioxidant action of fluvastatin in vivo. The decreased interstitial fibrosis along with a decreased oxidative stress marker in the interstitial lesion strongly suggests the existence of a causal relationship between them. Fluvastatin may have therapeutic value in slowing or preventing interstitial fibrosis in progressive renal disease.     

Heme oxygenase-1 protects rat kidney from ureteral obstruction via an antiapoptotic pathway

This study examined the functional significance of heme oxygenase-1 (HO-1) expression on renal injury induced by ureteral obstruction in the rat kidney. Male Sprague-Dawley rats were divided into three groups, after which unilateral ureteral obstruction (UUO) was performed: untreated (group 1), treated with 30 mg/kg body wt hemin (group 2), and treated with 50 microg/kg body wt zinc (alpha) protoporphyrin eta (ZnPP) and 30 mg/kg hemin (group 3). After 7 and 14 d, histologic changes and the expression of HO-1, Bcl-2, Bad, TGF-beta, and cleaved caspase-3 were examined. Tubular lumens were dilated and epithelial cells were flattened on day 7 after UUO. Interstitial fibrosis and separation of the tubules were markedly increased on day 14. In contrast, the kidneys that were treated with hemin exhibited minimal interstitial fibrosis and flattening of epithelial cells on day 7 and fewer changes on day 14 than in the controls. However, treatment with ZnPP, an inhibitor of HO enzyme activity, eliminated the beneficial effect of hemin on interstitial fibrosis and tubular dilation. Increased HO-1 expression was associated with increased Bcl-2. In the ZnPP-treated rats, Bcl-2 signals were decreased compared with the hemin group. The level of proapoptotic Bad was not changed in any group. The positive cells for cleaved caspase-3 were significantly increased in renal tubular epithelial cells and tubulointerstitial cells in the obstructed rats, and hemin treatment decreased the caspase-3 activation. This study demonstrates that upregulation of HO-1 provides protection against renal injury that follows UUO. This effect is dependent on modulation of the antiapoptotic pathway by HO-1 expression.     

mTOR通路调控肾间质成纤维细胞活化的机制

目的 探讨mTOR信号通路在肾间质成纤维细胞增生活化过程中的调控作用,并研究其抑制剂在抗肾纤维化治疗中的可行性.方法 用8周龄雌性C57BL/6小鼠构建单侧输尿管结扎(UUO)肾间质纤维化动物模型(n=30),按数字随机法分为雷帕霉素组(n=15)及UUO组(n=15).雷帕霉素组术前1d开始腹腔注射雷帕霉素(2 mg·kg-1·d-1)至实验结束;UUO组注射生理盐水.分别于术后1、3、7、14 d处死小鼠(n=3),留肾组织进行相关检测.同时,体外实验评估雷帕霉素对TGF-β诱导鼠成纤维细胞株(NIH3T3细胞)活化的干预作用.结果 UUO小鼠肾组织中活化的肌成纤维细胞[α肌动蛋白(α-SMA)阳性]高表达mTOR通路下游效应因子pS6K.雷帕霉素显著抑制pS6K表达及肾间质中肌成纤维细胞的活化,改善肾小管间质损伤及纤维化程度.实时荧光定量PCR结果提示雷帕霉素组小鼠肾皮质组织中成纤维细胞特异蛋白1 (FSP1)、转化生长因子β(TGF-β)、结缔组织因子(CTGF)及Ⅳ型胶原蛋白基因α1 (Col 4A1)的mRNA水平显著下降.体外实验结果示TGF-β诱导小鼠成纤维细胞株( NIH3T3)的mTOR通路显著活化,并大量合成α-SMA.雷帕霉素能够明显抑制mTOR通路活性,降低细胞的纤维化活性.结论 肾间质纤维化过程中成纤维细胞内的mTOR信号通路高度活化.抑制mTOR通路能够显著降低成纤维细胞的活性,改善肾间质纤维化程度.     

NGAL、MMP-9及TIMP-1在单侧输尿管梗阻大鼠肾组织中的表达

目的：动态观测单侧输尿管梗阻大鼠肾组织中中性粒细胞相关脂质运载蛋白（NGAL）、基质金属蛋白酶-9（MMP-9）及金属蛋白酶组织抑制因子（TIMP—1）的表达变化,探讨NGAL分子在肾小管间质纤维化发展中的作用机制。方法：将48只雄性SD大鼠随机分为UUO模型组及假手术（SOR）组,每组24只,UUO组行左侧输尿管梗阻术,SOR组仅游离左侧输尿管不结扎。术后第1、4、7、14天分别处死每组6只大鼠,取左肾行HE＆Masson染色,并用免疫组化EI,iVision‘M1plus法检测肾组织NGAL、MMP-9及TIMP-1的表达。结果：HE、Masson染色切片示：UUO组间质损伤指数在术后各时间点高于SOR组（P〈0．05）。免疫组化结果显示：UUO组术后各时间点NGAL表达高于SOR组（P〈0．05）,与肾小管损伤指数呈明显负相关;MMP-9在uu0术后早期（1～7天）有所上升,随着病程进展,7～14天表达有所下降;TIMP1在UUO术后表达逐渐增强;NGAI。与MMP-9／TIMP-1比值呈明显正相关。结论：NGAL在肾间质纤维化早期发挥负向调节作用,对调节MMP-9／TIMP-1的平衡亦发挥重要作用。     

干细胞因子联合粒细胞集落刺激因子动员骨髓干细胞促进单侧输尿管梗阻大鼠肾脏损伤的修复

目的 研究干细胞因子（SCF）联合粒细胞集落刺激因子（G-CSF）动员单侧输尿管梗阻（UUO）大鼠骨髓干细胞对肾间质中微血管、纤维化程度和肾功能的影响,并探讨其对微血管影响的可能机制。 方法 128只大鼠按数字随机法分为假手术组（Sham组）、SCF联合G-CSF动员组（SCF-G组）、UUO组、UUO+SCF-G组。于实验第 5、14、21、28天每组各随机抽取8只处死,检测Scr、肾间质CD34阳性表达细胞数目和Ⅷ因子阳性表达细胞数目、肾间质纤维化和间质病理损害积分、肾皮质血管内皮生长因子（VEGF）mRNA和血小板反应蛋白1（TSP-1）mRNA的表达。 结果 (1)UUO组2周时可见到肾间质纤维化伴肾小管周微血管的丢失。（2）UUO+SCF-G组肾间质干细胞归巢数目明显高于UUO组和Sham组（P < 0.05）。（3）UUO+SCF-G组肾小管周微血管指数减少出现的时间晚于UUO组（P < 0.05）。（4）第14、21、28天UUO+SCF-G组间质化纤维程度和肾小管损伤程度均轻于UUO组（P < 0.05）。（5）UUO+SCF-G组术后VEGF mRNA表达下调出现的时间晚于UUO组,且表达均高于同期UUO组 （P < 0.05)。（6）UUO+SCF-G组术后TSP-1 mRNA表达增高出现的时间晚于UUO组,且表达均低于同期UUO组（P < 0.05）。（7）在UUO组和UUO+SCF-G组中,肾小管周微血管指数与Scr、间质纤维化积分和肾小管间质病理积分均呈负相关;肾皮质VEGF mRNA表达与肾小管周微血管指数呈正相关;肾皮质TSP-1 mRNA表达与肾小管周微血管指数呈负相关。 结论 （1）UUO大鼠存在肾小管周微血管丢失,并与肾间质纤维化及间质病理损伤相关。（2）联合应用SCF和G-CSF动员骨髓干细胞可以归巢至受损的肾脏,有助于减少肾小管周微血管丢失,并进而减轻肾间质纤维化和间质损害,保护肾功能。（3）联合应用SCF和G-CSF可以上调肾皮质VEGF mRNA水平和下调TSP-1 mRNA水平,这可能是其促进内皮细胞修复及保护肾间质微血管损伤的机制之一。     

Renal structural and functional repair in a mouse model of reversal of ureteral obstruction

The end point of immune and nonimmune renal injury typically involves glomerular and tubulointerstitial fibrosis. Although numerous studies have focused on the events that lead to renal fibrosis, less is known about the mechanisms that promote cellular repair and tissue remodeling. Described is a model of renal injury and repair after the reversal of unilateral ureteral obstruction (UUO) in male C57bl/6J mice. Male mice (20 to 25 g) underwent 10 d of UUO with or without 1, 2, 4, or 6 wk of reversal of UUO (R-UUO). UUO resulted in cortical tubular cell atrophy and tubular dilation in conjunction with an almost complete ablation of the outer medulla. This was associated with interstitial macrophage infiltration; increased hydroxyproline content; and upregulated type I, III, IV, and V collagen expression. The volume density of kidney occupied by renal tubules that exhibited a brush border was measured as an assessment of the degree of repair after R-UUO. After 6 wk of R-UUO, there was an increase in the area of kidney occupied by repaired tubules (83.7 +/- 5.9%), compared with 10 d UUO kidneys (32.6 +/- 7.3%). This coincided with reduced macrophage numbers, decreased hydroxyproline content, and reduced collagen accumulation and interstitial matrix expansion, compared with obstructed kidneys from UUO mice. GFR in the 6-wk R-UUO kidneys was restored to 43 to 88% of the GFR in the contralateral unobstructed kidneys. This study describes the regenerative potential of the kidney after the established interstitial matrix expansion and medullary ablation associated with UUO in the adult mouse.     

The expression of mRNA for tumour necrosis factor-α increases in the obstructed kidney of rats soon after unilateral ureteral ligation

Summary: Cytokines, including transforming growth factor (TGF)-β1, contribute to the tubulointerstitial fibrosis of ureteral obstruction. Tumour necrosis factor (TNF)-α, a proinflammatory cytokine produced by multiple cells including macrophages and resident renal cells, has a role in inflammatory cell recruitment in glomerular injury. We measured TNF-α mRNA in the renal cortex of rats at different times after the onset of unilateral ureteral obstruction (UUO) and determined whether angiotensin II (AngII) inhibition or total body irradiation affects the mRNA levels of TNF-α. Rats were killed at 1, 2, 4, 24, 72 and 120h after UUO. Levels of TNF-α mRNA increased significantly in the obstructed kidney at 1h (X 2), 2h (X 2.7), 4h (X 3.6), 24h (X 2.7), 72h (X 1.8) and 120h (X 2.8) after ureteral ligation when compared to the contralateral kidney of the same animals or to control (normal) kidneys. Tumour necrosis factor-α mRNA increased in renal cortical tubules but not in glomeruli. Treatment with enalapril, an angiotensin-converting enzyme (ACE) inhibitor, before and after UUO decreased TNF-α mRNA levels in the obstructed kidney by about 40% at 4h after the onset of UUO, but at 120h there was no difference in TNF-α levels in the obstructed kidney of treated and untreated animals. Total body irradiation, which depletes macrophages in the obstructed kidney, did not prevent the upregulation of TNF-α mRNA expression at 4 h after UUO. Thus, TNF-α may have a role in initiating tubulointerstitial injury in the obstructed kidney. Leucocytes infiltrating the renal interstitium of the obstructed kidney do not appear to contribute to the increased mRNA expression of TNF-α. Angiotensin II may contribute, at least in part, to the early increased expression of TNF-α mRNA in the obstructed kidney.     

Time course of cytokine mRNA expression in kidneys of rats with unilateral ureteral obstruction

The development of renal interstitial fibrosis (RIF) is related to the expression and excretion of cytokines and growth factors. Thus, we investigated the time course of mRNA expression of cytokines known as causative factors in a model of RIF in rats before and on day 10 after unilateral ureteral obstruction (UUO), when first signs of fibrosis were visible, as well as during progressive RIF. UUO causes a fivefold increase in mRNA expression of monocyte chemoattractant protein 1 15 days after surgery as compared with contralateral kidneys. The level remains elevated about three-fold up to day 25. The mRNA of the fibrogenic cytokine transforming growth factor beta 1 (TGF-beta1) is increased two- to threefold during the time course, whereas the mRNAs of platelet-derived growth factor B chain (PDGF-B) and its receptor beta (PDGF-Rbeta) increase after UUO, reaching their maxima on days 10-15. PDGF-B mRNA increase up to day 15, marking the onset of fibrosis, and decreases thereafter, whereas the expression of the PDGF-Rbeta mRNA remains elevated more than threefold over the entire study period. Incubation of cultured renal fibroblasts with TGF-beta1 and/or PDGF-B suggests that their specific action on cell growth and proliferation is maintained even when they are used in combination. The sustained elevation of TGF-beta1 and PDGF-B/PDGF-Rbeta mRNA levels confirms the assumption of a particular involvement of these cytokines in the pathogenesis of RIF. The mRNA expression of the gap junctional protein connexin 43 in ureteral ligated kidneys is increased sixfold already 5 days after UUO. In this way, the increased connexin 43 mRNA levels indicate a possible function in the remodeling of the kidney tissue after tubular damage and fibrosis.     

Recovery following relief of unilateral ureteral obstruction in the neonatal rat

BACKGROUND: Obstructive nephropathy is a primary cause of renal insufficiency in infants and children. This study was designed to distinguish the reversible and irreversible cellular consequences of temporary unilateral ureteral obstruction (UUO) on the developing kidney. METHODS: Rats were subjected to UUO or sham operation in the first 48 hours of life, and the obstruction was removed five days later (or was left in place). Kidneys were removed for study 14 or 28 days later. In additional groups, kidneys were removed at the end of five days of obstruction. Immunoreactive distribution of renin was determined in arterioles, and the distribution of epidermal growth factor, transforming growth factor-beta1, clusterin, vimentin, and alpha-smooth muscle actin was determined in tubules and/or interstitium. The number of glomeruli, glomerular maturation, tubular atrophy, and interstitial collagen deposition was determined by morphometry. Renal cellular proliferation and apoptosis were measured by proliferating cell nuclear antigen and the TdT uridine-nick-end-label technique, respectively. The glomerular filtration rate was measured by inulin clearance. RESULTS: Renal microvascular renin maintained a fetal distribution with persistent UUO; this was partially reversed by the relief of obstruction. Although glomerular maturation was also delayed and glomerular volume was reduced by UUO, the relief of obstruction prevented the reduction in glomerular volume. Although relief of obstruction did not reverse a 40% reduction in the number of nephrons, the glomerular filtration rate of the postobstructed kidney was normal. The relief of obstruction did not improve tubular cell proliferation and only partially reduced apoptosis induced by UUO. This was associated with a persistent reduction in the tubular epidermal growth factor. In addition, the relief of obstruction reduced but did not normalize tubular expression of transforming growth factor-beta1, clusterin, and vimentin, all of which are evidence of persistent tubular injury. The relief of obstruction significantly reduced interstitial fibrosis and expression of alpha-smooth muscle actin by interstitial fibroblasts, but not to normal levels. CONCLUSIONS: The relief of obstruction in the neonatal rat attenuates, but does not reverse, renal vascular, glomerular, tubular, and interstitial injury resulting from five days of UUO. Hyperfiltration by remaining nephrons and residual tubulointerstitial injury in the postobstructed kidney are likely to lead to deterioration of renal function later in life.     

Chemokine receptor CCR1 but not CCR5 mediates leukocyte recruitment and subsequent renal fibrosis after unilateral ureteral obstruction

As chemokine receptor CCR1 and CCR5 expression on circulating leukocytes is thought to contribute to leukocyte recruitment during renal fibrosis, the authors examined the effects of unilateral ureteral obstruction (UUO) in mice deficient for CCR1 or CCR5. Analysis of UUO kidneys from CCR1-deficient mice revealed a reduction of interstitial macrophages and lymphocytes (35% and 55%, respectively) compared with wild-type controls. CCR1-deficient mice had reduced CCR5 mRNA levels in UUO kidneys, which correlated with a reduction of CCR5+ T cell infiltrate as determined by flow cytometry. Interstitial fibroblasts, renal TGF-beta1 mRNA expression, interstitial volume, and collagen I deposits were all significantly reduced in CCR1-deficient mice. In contrast, renal leukocytes and fibrosis were unaffected in CCR5-deficient mice with UUO. However, if treated with the CCR1 antagonist BX471, CCR5-deficient mice showed a similar reduction of renal leukocytes and fibrosis as CCR1-deficient mice. To determine the underlying mechanism labeled macrophages and T cells isolated from either wild-type, CCR1-deficient, or CCR5-deficient mice were injected into wild-type mice with UUO. Three hours later, renal cell recruitment was reduced for CCR1-deficient cells or cells pretreated with BX471 compared with CCR5-deficient or wild-type cells. Thus, CCR1 but not CCR5 is required for leukocyte recruitment and fibrosis after UUO in mice. Therefore, CCR1 is a promising target for therapeutic intervention in leukocyte-mediated fibrotic tissue injury, e.g. progressive renal fibrosis.     

PAI-1 deficiency attenuates the fibrogenic response to ureteral obstruction

BACKGROUND: Progressive renal disease is characterized by the induction of plasminogen activator inhibitor-1 (PAI-1), suggesting that impaired activity of the renal plasmin cascade may play a role in renal fibrosis. METHODS: To test this hypothesis, the severity of renal fibrosis caused by unilateral ureteral obstruction (UUO) was compared in PAI-1 wild-type (+/+) and PAI-1 deficient (-/-) mice. The extent of interstitial inflammation and fibrosis, renal plasminogen activator and plasmin activity, and renal expression of profibrotic genes was evaluated after 3, 7, and 14 days of UUO. RESULTS: Renal PAI-1 mRNA levels increased 8- to 16-fold in the +/+ mice after UUO surgery, and PAI-1 protein was detected in kidney homogenates. Interstitial fibrosis was significantly attenuated in -/- mice compared with +/+ mice at day 7 and day 14, based on the interstitial area stained with picrosirius red and total kidney collagen content. However, neither the mean renal plasminogen activator nor plasmin activities were increased in -/- mice compared with +/+ mice. The number of interstitial macrophages were significantly lower in the -/- mice three and seven days after UUO; interstitial myofibroblasts were significantly fewer at three days. At the same time points, this altered interstitial cellularity was associated with a significant reduction in renal mRNA levels for transforming growth factor-beta and procollagens alpha 1(I) and alpha 1(III). CONCLUSIONS: These studies establish an important fibrogenic role for PAI-1 in the renal fibrogenic response. The results demonstrate that one important fibrosis-promoting function of PAI-1 is its role in the recruitment of fibrosis-inducing cells, including myofibroblasts and macrophages.     

Mannose receptor 2 attenuates renal fibrosis

Mannose receptor 2 (Mrc2) expresses an extracellular fibronectin type II domain that binds to and internalizes collagen, suggesting that it may play a role in modulating renal fibrosis. Here, we found that Mrc2 levels were very low in normal kidneys but subsets of interstitial myofibroblasts and macrophages upregulated Mrc2 after unilateral ureteral obstruction (UUO). Renal fibrosis and renal parenchymal damage were significantly worse in Mrc2-deficient mice. Similarly, Mrc2-deficient Col4α3(-/-) mice with hereditary nephritis had significantly higher levels of total kidney collagen, serum BUN, and urinary protein than Mrc2-sufficient Col4α3(-/-) mice. The more severe phenotype seemed to be the result of reduced collagen turnover, because procollagen III (α1) mRNA levels and fractional collagen synthesis in the wild-type and Mrc2-deficient kidneys were similar after UUO. Although Mrc2 associates with the urokinase receptor, differences in renal urokinase activity did not account for the increased fibrosis in the Mrc2-deficient mice. Treating wild-type mice with a cathepsin inhibitor, which blocks proteases implicated in Mrc2-mediated collagen degradation, worsened UUO-induced renal fibrosis. Cathepsin mRNA profiles were similar in Mrc2-positive fibroblasts and macrophages, and Mrc2 genotype did not alter relative cathepsin mRNA levels. Taken together, these data establish an important fibrosis-attenuating role for Mrc2-expressing renal interstitial cells and suggest the involvement of a lysosomal collagen turnover pathway.     

Unilateral ureteral obstruction impairs renal antioxidant enzyme activation during sodium depletion

BACKGROUND: Obstructive nephropathy leads to progressive renal tubular atrophy and interstitial fibrosis and is associated with sodium wasting and sodium depletion. Renal damage resulting from unilateral ureteral obstruction (UUO) may be aggravated by reactive oxygen species (ROS), which are produced by a variety of processes. Ideally, deleterious effects of ROS are attenuated by antioxidant enzymes, including the superoxide dismutases, glutathione peroxidases, catalase, and glutathione-S-transferases. The general paradigm is that tissue damage occurs when ROS production is greater than the protective capacity of the antioxidant enzymes. METHODS: This study was designed to investigate the response of renal antioxidant enzymes to UUO and sodium depletion. Adult, male Sprague-Dawley rats received normal-sodium or sodium-depleted siets and were subjected to UUO or sham operation. Obstructed (UUO), intact opposite, or sham-operated kidneys were harvested after 14 days, and antioxidant enzyme activities were measured in kidney homogenates. Thiobarbituric acid reactive substances were measured in these homogenates at 3 and 14 days after UUO or sham operation as an index of ROS production. RESULTS: Renal interstitial area, a measure of fibrosis, was increased by UUO and was doubled in sodium-depleted animals. Sodium depletion increased manganese superoxide dismutase, glutathione peroxidases, and glutathione-S-transferase activities in sham-operated kidneys but not in UUO kidneys. Relative to intact opposite kidneys, UUO kidneys had reduced activities of catalase, manganese superoxide dismutase, and glutathione-S-transferase in normal-sodium animals and all antioxidant enzymes tested in sodium-depleted animals. Renal thiobarbituric acid reactive substances were increased by three days of UUO and were increased further by 14 days of sodium depletion. CONCLUSION: In summary, sodium depletion increased several renal antioxidant enzymes, consistent with a stress response to increased ROS production. Further, UUO not only reduced antioxidant enzyme activities but also inhibited increases seen with sodium depletion. We conclude that suppression of renal antioxidant enzyme activities by UUO contributes to the progression of renal injury in obstructive nephropathy, a process exacerbated by sodium depletion.     

冬虫夏草通过诱导血色素加氧酶-1表达抑制肾小管间质纤维化

目的：观察冬虫夏草对单侧输尿管梗阻（unilateral ureteral obstruction,UUO）模型大鼠肾小管间质纤维化进展的保护作用。方法：72只雄性清洁级SD大鼠随机分为4组：假手术组,UUO模型组,UUO加冬虫夏草治疗组,UUO加冬虫夏草和血色素加氧酶抑制剂卟啉锌[（zinc（a）protoporphyrinη,znpp）]治疗组。各组大鼠分别于术后（建模后）第3、7、14天分批处死,留取手术侧（模型组梗阻侧）肾脏组织。采用HE、Masson染色、荧光定量PCR、免疫组织化学染色评价肾小管间质纤维化损伤程度并检测肾脏组织血色素加氧酶-1（hemoglobin oxygenase-1,HO-1）,α平滑肌肌动蛋白（α-smooth muscle ac-tin,α-SMA）mRNA及蛋白表达变化情况。结果：冬虫夏草治疗组相对于UUO模型组,肾脏病理损伤及进展程度明显减轻且HO-1的表达上调,α-SMA的表达下调（P〈0.05）,而冬虫夏草加HO-1抑制剂znpp后,以上作用明显减弱。结论：冬虫夏草可以通过诱导血色素加氧酶的表达减轻肾小管间质纤维化程度。     

Sulfasalazine reduces inflammatory renal injury in unilateral ureteral obstruction

The purpose of this study was to test whether sulfasalazine has a protective action against interstitial inflammation and the development of renal fibrosis in obstructive nephropathy. Female rats were subjected to a sham (n = 10) or unilateral ureteral obstruction (UUO, n = 30). UUO was induced in rats by ligating the left ureter. Three days after operation, rats subjected to UUO were randomized to receive tretment with either sulfasalazine (100 mg/kg) or vehicle every day for the last 7 days of the experiment. At 10 days following UUO, the obstructed kidney exhibited tubulointerstitial injury and leukocyte infiltration (mainly monocytes) that were associated with high levels of reactive oxygen species, cytokines, transforming growth factor (TGF)-β1, myeloperoxidase (MPO), and lipid peroxidation. Ten days after UUO, the obstructed kidney was also associated with increased nuclear factor kappa beta (NF-κβ) expression in saline-treated rats. Compared with sham-operated rats, UUO rat kidneys showed lower concentrations of antioxidant enzymes in the obstructed kidney tissue. All of these changes were significantly attenuated by treatment with sulfasalazine in the obstructed kidney. Sulfasalazine protected against the renal interstitial inflammation and tissue damage elicited by ureteral occlusion. Inhibition of the NF-κβ-dependent pathway and inflammatory response and oxidative stress inhibition is likely to be involved in the beneficial effects of sulfasalazine.     

Transforming growth factor-beta 1 antisense oligodeoxynucleotides block interstitial fibrosis in unilateral ureteral obstruction

BACKGROUND: Interstitial expression of transforming growth factor-beta1 (TGF-beta1) is important in tubulointerstitial fibrosis, a common process in most progressive renal diseases. However, no effective therapy for progressive interstitial fibrosis is known. Recently, we developed an artificial viral envelope (AVE)-type hemagglutinating virus of Japan (HVJ) liposome-mediated retrograde ureteral gene transfer method, which allowed us to introduce the genetic material selectively into renal interstitial fibroblasts. METHOD: We introduced antisense or scrambled oligodeoxynucleotides (ODNs) for TGF-beta 1 into interstitial fibroblasts in rats with unilateral ureteral obstruction, a model of interstitial fibrosis, to block interstitial fibrosis by retrograde ureteral injection of AVE-type HVJ liposomes. RESULTS: TGF-beta 1 and type I collagen mRNA increased markedly in the interstitium of untreated obstructed kidneys, and those were not affected by scrambled ODN transfection. Northern analysis and in situ hybridization revealed that the levels of TGF-beta 1 and type I collagen mRNA were dramatically decreased in antisense ODN-transfected obstructed kidneys. Consequently, the interstitial fibrotic area of the obstructed kidneys treated with antisense ODN was significantly less than that of the obstructed kidneys untreated or treated with scrambled ODN. CONCLUSION: The introduction of TGF-beta 1 antisense ODN into interstitial fibroblasts may be a potential therapeutic maneuver for interstitial fibrosis.