苦参素对肾间质纤维化大鼠单核巨噬细胞浸润及MCP-1表达的影响

目的 观察苦参素对肾间质纤维化大鼠单核巨噬细胞（MC/MP）浸润,MCP-1及Ⅰ型胶原表达的影响。方法 大鼠行单侧输尿管结扎（UUO）建立肾小管间质纤维化模型。实验分为3组：假手术组,UUO组,苦参素治疗组。治疗组在UUO的基础上每天以苦参素100mg/Kg腹腔注射。各组于术后第14d分别处死5只大鼠。用PAS及Masson染色法观察肾脏病理改变。用免疫组织化学法观察肾间质ED-1阳性的MC/MP细胞浸润,单核细胞趋化蛋白-1（MCP-1）及Ⅰ型胶原（ColⅠ）的表达。结果 苦参素治疗组肾间质MC/MP细胞浸润数及MCP-1,ColⅠ的表达显著低于UUO组,肾小管变性和肾间质纤维化的程度也明显减轻。结论 苦参素可下调UUO大鼠肾间质MCP-1的表达,减少MC/MP细胞浸润,减轻肾间质纤维化。     

MMP-2 inhibition reduces renal macrophage infiltration with increased fibrosis in UUO

We examined the role of matrix metalloproteinase-2 (MMP-2) in renal fibrosis and its effect on interstitial macrophage infiltration in a mouse model of unilateral ureteral obstruction (UUO). TISAM, a selective inhibitor of MMP-2, was administered during early stage (day -2 to 4; protocol A) and late stage (day 7 to 13; protocol B) after UUO. Treatment with TISAM accelerated fibrosis both at day 5 (A) and at day 14 (B). The degree of macrophage infiltration was decreased by the treatment with TISAM at day 14, but not at day 5. In vitro macrophage migration assay showed a greater migration to renal tissue of control UUO kidney (day 14) than to TISAM-treated kidney, which was suppressed by preincubating macrophages with RGDS, a fibronectin degradation peptide. These results suggest that MMP-2 acts to accelerate macrophage infiltration in the late stage of UUO, possibly by degrading extracellular matrix components.     

羟苯磺酸钙通过抑制Ⅰ型胶原表达减轻肾间质纤维化

目的:研究羟苯磺酸钙对小鼠肾间质纤维化、Ⅰ型胶原表达的影响。方法:将C57小鼠随机分为假手术组(Sham组,n=4)、肾间质纤维化模型组(UUO组,n=5)及羟苯磺酸钙治疗组(CDT组,n=4);采用单侧输尿管梗阻制备肾间质纤维化模型,CDT组给予羟苯磺酸钙灌胃、Sham组和UUO组给予双蒸水灌胃;采用HE染色、Masson染色、免疫组化、实时定量PCR以及蛋白免疫印迹观察单侧输尿管梗阻术后14 d小鼠术侧肾脏的肾间质纤维化程度和Ⅰ型胶原表达情况。结果:与Sham组比较,UUO组小鼠术后14 d术侧肾脏肾发生显著肾间质纤维化,Ⅰ型胶原表达显著增强(Ⅰ型胶原基因相对表达量:Sham组:1.00000,UUO组:114.92289,P0.0001)。与UUO组比较,CDT组小鼠术后14 d术侧肾间质纤维化程度显著减轻,Ⅰ型胶原表达显著减弱(Ⅰ型胶原基因相对表达量:UUO组:114.92289,CDT组:45.33516,P0.005)。结论:羟苯磺酸钙通过抑制小鼠肾间质Ⅰ型胶原表达从而减轻单侧输尿管结扎小鼠肾间质纤维化。     

Galectin-3 preserves renal tubules and modulates extracellular matrix remodeling in progressive fibrosis

Renal tubular cell apoptosis is a critical detrimental event that leads to chronic kidney injury in association with renal fibrosis. The present study was designed to investigate the role of galectin-3 (Gal-3), an important regulator of multiple apoptotic pathways, in chronic kidney disease induced by unilateral ureteral obstruction (UUO). After UUO, Gal-3 expression significantly increased compared with basal levels reaching a peak increase of 95-fold by day 7. Upregulated Gal-3 is predominantly tubular at early time points after UUO but shifts to interstitial cells as the injury progresses. On day 14, there was a significant increase in TdT-mediated dUTP nick end labeling-positive cells (129%) and cytochrome c release (29%), and a decrease in BrdU-positive cells (62%) in Gal-3-deficient compared with wild-type mice. The degree of renal damage was more extensive in Gal-3-deficient mice at days 14 and 21, 35 and 21% increase in total collagen, respectively. Despite more severe fibrosis, myofibroblasts were significantly decreased by 58% on day 14 in the Gal-3-deficient compared with wild-type mice. There was also a corresponding 80% decrease in extracellular matrix synthesis in Gal-3-deficient compared with wild-type mice. Endo180 is a recently recognized receptor for intracellular collagen degradation that is expressed by interstitial cells during renal fibrogenesis. Endo180 expression was significantly decreased by greater than 50% in Gal-3-deficient compared with wild-type mice. Taken together, these results suggested that Gal-3 not only protects renal tubules from chronic injury by limiting apoptosis but that it may lead to enhanced matrix remodeling and fibrosis attenuation.     

化瘀解毒中药抑制梗阻性肾病巨噬细胞浸润减轻炎性损伤的作用

为观察化瘀解毒中药对梗阻性肾病巨噬细胞浸润的影响及作用机制。将48只健康雄性Wistar大鼠随机分为假手术组、模型组、依普利酮组、中药组,每组12只。除假手术组外,其余大鼠结扎单侧输尿管(UUO)复制肾间质纤维化动物模型。治疗组分别给以依普利酮(100 mg/kg/d加入饲料喂养)和化瘀解毒中药煎剂(14 g/kg/d灌胃)。10 d后摘取肾脏,观察大鼠肾脏组织病理改变。免疫组化法标记巨噬细胞浸润,免疫组化、Western Blot方法检测血清和糖皮质激素诱导蛋白激酶1(SGK-1)、单核细胞趋化蛋白-1(MCP-1)、白细胞介素-1(IL-1)、肿瘤坏死因子-α(TNF-α)的表达。肾脏病理显示,UUO组大鼠肾脏有明显的肾小管扩张及上皮细胞脱落,间质巨噬细胞浸润增多和细胞外基质(ECM)大量积聚,SGK-1、MCP-1、IL-1、TNF-α表达明显增强。化瘀解毒中药可明显减轻UUO大鼠肾脏巨噬细胞等炎性细胞浸润和ECM沉积,下调SGK-1、MCP-1、IL-1、TNF-α表达。以上结果说明化瘀解毒中药可抑制梗阻性肾病诱导的巨噬细胞浸润,减轻肾脏炎性损伤。     

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。     

Toll-like receptor signaling and SIGIRR in renal fibrosis upon unilateral ureteral obstruction

Innate immune activation via IL-1R or Toll-like receptors (TLR) contibutes to acute kidney injury but its role in tissue remodeling during chronic kidney disease is unclear. SIGIRR is an inhibitor of TLR-induced cytokine and chemokine expression in intrarenal immune cells, therefore, we hypothesized that Sigirr-deficiency would aggravate postobstructive renal fibrosis. The expression of TLRs as well as endogenous TLR agonists increased within six days after UUO in obstructed compared to unobstructed kidneys while SIGIRR itself was downregulated by day 10. However, lack of SIGIRR did not affect the intrarenal mRNA expression of proinflammatory and profibrotic mediators as well as the numbers of intrarenal macrophages and T cells or morphometric markers of tubular atrophy and interstitial fibrosis. Because SIGIRR is known to block TLR/IL-1R signaling at the level of the intracellular adaptor molecule MyD88 UUO experiments were also performed in mice deficient for either MyD88, TLR2 or TLR9. After UUO there was no significant change of tubular interstitial damage and interstitial fibrosis in neither of these mice compared to wildtype counterparts. Additional in-vitro studies with CD90+ renal fibroblasts revealed that TLR agonists induce the expression of IL-6 and MCP-1/CCL2 but not of TGF-β, collagen-1α or smooth muscle actin. Together, postobstructive renal interstitial fibrosis and tubular atrophy develop independent of SIGIRR, TLR2, TLR9, and MyD88. These data argue against a significant role of these molecules in renal fibrosis.     

兔慢性肾功能衰竭模型的建立与评价

目的建立兔慢性肾功能衰竭模型,为干细胞移植治疗和相关研究奠定基础。方法普通级大耳白兔随机分为正常对照组和单侧输尿管结扎（unilateral ureteral obstruction,UUO）组。UUO组于输尿管结扎后2、4、6、8周进行血生化肾功能指标检测,并取肾组织观察肾脏病理学改变,通过SPECT动态观察肾小球滤过率的变化,采用免疫组织化学方法观察肾组织转化生长因子-β1（TGF-β1）的表达情况。结果①UUO组术后第2周,出现明显的血肌酐升高,尿素氮术后第8周开始升高（P〈0.01）。②UUO组术后第4周,肾脏组织出现了早期间质纤维化的病理改变,术后第8周肾小球开始出现硬化,间质纤维化明显,皮质明显变薄。术后第12周,肾小球硬化比例增加,肾小管玻璃样变性,间质纤维化进一步加重（P〈0.05）。③SPECT动态观察肾小球滤过率,UUO组第4周GFR值比正常对照组降低,到第8周时,GFR值进一步下降,结扎侧肾脏功能降低甚至丧失。④免疫组织化学染色显示,TGF-β1在术后第4、8、12周均明显增强,并且各时间点表达均有显著差异（P〈0.05）。结论单侧输尿管结扎法成功制作比较稳定的慢性肾功能不全模型,UUO后第8周符合肾脏间质纤维化模型标准。     

Epigallocatechin-3-Gallate Attenuates Unilateral Ureteral Obstruction-Induced Renal Interstitial Fibrosis in Mice

The severity of tubulointerstitial fibrosis is regarded as an important determinant of renal prognosis. Therapeutic strategies targeting tubulointerstitial fibrosis have been considered to have potential in the treatment of chronic kidney disease. This study aims to evaluate the protective effects of (-)-epigallocatechin-3-gallate (EGCG), a green tea polyphenol, against renal interstitial fibrosis in mice. EGCG was administrated intraperitoneally for 14 days in a mouse model of unilateral ureteral obstruction (UUO). The results of our histological examination showed that EGCG alleviated glomerular and tubular injury and attenuated renal interstitial fibrosis in UUO mice. Furthermore, the inflammatory responses induced by UUO were inhibited, as represented by decreased macrophage infiltration and inflammatory cytokine production. Additionally, the expression of type I and III collagen in the kidney were reduced by EGCG, which indicated an inhibition of extracellular matrix accumulation. EGCG also caused an up-regulation in α-smooth muscle actin expression and a down-regulation in E-cadherin expression, indicating the inhibition of epithelial-to-mesenchymal transition. These changes were found to be in parallel with the decreased level of TGF-β1 and phosphorylated Smad. In conclusion, the present study demonstrates that EGCG could attenuate renal interstitial fibrosis in UUO mice, and this renoprotective effect might be associated with its effects of inflammatory responses alleviation and TGF-β/Smad signaling pathway inhibition.     

Bone marrow–derived mesenchymal stem cells attenuate tubulointerstitial injury through multiple mechanisms in UUO model

Current evidence supports the use of bone marrow–derived mesenchymal stem cells (MSCs) for a diverse range of clinical applications, and many studies have shown that MSCs have renal-protective effects, but the mechanism is not well understood. Therefore, in this study, we aim to further identify whether MSCs can attenuate renal fibrosis by decreasing tubulointerstitial injury in a unilateral ureteral obstruction (UUO) model. In this study, we cultured MSCs and then transplanted them into a UUO model through the tail vein. Histology, cell proliferation, peritubular capillary (PTC) loss and myofibroblast markers were examined on days 3, 7 and 14 after surgery. We demonstrated that renal interstitial fibrosis in the MSC group was significantly attenuated compared with the UUO and DMEM groups. Moreover, MSC treatment inhibited the loss of PTCs and increased parenchymal cell proliferation. In addition, UUO-induced activation and proliferation of myofibroblasts were suppressed by MSC infusion. Furthermore, MSCs attenuated tubulointerstitial infiltration of macrophages in UUO mice. Tubulointerstitial damage plays a very important role in the progression of chronic kidney disease (CKD). PTC loss, macrophage recruitment, and myofibroblast activation are directly correlated with the development of renal tubulointerstitial fibrosis. Our results suggest that MSC infusion in the UUO model is a promising therapeutic strategy for promoting kidney repair.     

The Role of M2 Macrophages in the Progression of Chronic Kidney Disease following Acute Kidney Injury

Introduction

Acute kidney injury (AKI) is a major risk factor in the development of chronic kidney disease (CKD). However, the mechanisms linking AKI to CKD remain unclear. We examined the alteration of macrophage phenotypes during an extended recovery period following ischemia/reperfusion injury (IRI) and determine their roles in the development of fibrosis.

Methods

The left renal pedicle of mice was clamped for 40 min. To deplete monocyte/macrophage, liposome clodronate was injected or CD11b-DTR and CD11c-DTR transgenic mice were used.

Results

Throughout the phase of IRI recovery, M2-phenotype macrophages made up the predominant macrophage subset. On day 28, renal fibrosis was clearly shown with increased type IV collagen and TGF-β. The depletion of macrophages induced by the liposome clodronate injection improved renal fibrosis with a reduction of kidney IL-6, type IV collagen, and TGF-β levels. Additionally, the adoptive transfer of the M2c macrophages partially reversed the beneficial effect of macrophage depletion, whereas the adoptive transfer of the M1 macrophages did not. M2 macrophages isolated from the kidneys during the recovery phase expressed 2.5 fold higher levels of TGF-β than the M1 macrophages. The injection of the diphtheria toxin into CD11b or CD11c-DTR transgenic mice resulted in lesser depletion or no change in M2 macrophages and had little impact on renal fibrosis.

Conclusion

Although M2 macrophages are known to be indispensible for short-term recovery, they are thought to be main culprit in the development of renal fibrosis following IRI.     

Vitronectin accumulates in the interstitium but minimally impacts fibrogenesis in experimental chronic kidney disease

Vitronectin (Vtn) is a glycoprotein found in normal serum and pathological extracellular matrix. Given its known interactions with plasminogen activator inhibitor-1 (PAI-1) and Vtn cellular receptors, especially αvβ3 integrin and the urokinase receptor (uPAR), this study was designed to investigate its role in renal fibrogenesis in the mouse model of unilateral ureteral obstruction (UUO). Kidney Vtn mRNA levels were increased ×1.8-5.1 and Vtn protein levels ×1.9-3 on days 7, 14, and 21 after UUO compared with sham kidney levels. Groups of age-matched C57BL/6 wild-type (Vtn+/+) and Vtn-/- mice (n = 10-11/group) were killed 7, 14, or 21 days after UUO. Absence of Vtn resulted in the following significant differences, but only on day 14: fewer αSMA+ interstitial myofibroblasts (×0.53), lower procollagen III mRNA levels (×0.41), lower PAI-1 protein (×0.23), higher uPA activity (×1.1), and lower αv protein (×0.32). The number of CD68+ macrophages did not differ between the genotypes. Despite these transient differences on day 14, the absence of Vtn had no effect on fibrosis severity based on both picrosirius red-positive interstitial area and total kidney collagen measured by the hydroxyproline assay. These findings suggest that despite significant interstitial Vtn deposition in the UUO model of chronic kidney disease, its fibrogenic role is either nonessential or redundant. These data are remarkable given Vtn's strong affinity for the potent fibrogenic molecule PAI-1.     

Overexpression of Heme Oxygenase-1 Prevents Renal Interstitial Inflammation and Fibrosis Induced by Unilateral Ureter Obstruction

Renal fibrosis plays an important role in the onset and progression of chronic kidney diseases. Many studies have demonstrated that heme oxygenase-1 (HO-1) is involved in diverse biological processes as a cytoprotective molecule, including anti-inflammatory, anti-oxidant, anti-apoptotic, antiproliferative, and immunomodulatory effects. However, the mechanisms of HO-1 prevention in renal interstitial fibrosis remain unknown. In this study, HO-1 transgenic (TG) mice were employed to investigate the effect of HO-1 on renal fibrosis using a unilateral ureter obstruction (UUO) model and to explore the potential mechanisms. We found that HO-1 was adaptively upregulated in kidneys of both TG and wild type (WT) mice after UUO. The levels of HO-1 mRNA and protein were increased in TG mice compared with WT mice under normal conditions. HO-1 expression was further enhanced after UUO and remained high during the entire experimental process. Renal interstitial fibrosis in the TG group was significantly attenuated compared with that in the WT group after UUO. Moreover, overexpression of HO-1 inhibited the loss of peritubular capillaries. In addition, UUO-induced activation and proliferation of myofibroblasts were suppressed by HO-1 overexpression. Furthermore, HO-1 restrained tubulointerstitial infiltration of macrophages and regulated the secretion of inflammatory cytokines in UUO mice. We also found that high expression of HO-1 inhibited reactivation of Wnt/β-catenin signaling, which could play a crucial role in attenuating renal fibrosis. In conclusion, these data suggest that HO-1 prevents renal tubulointerstitial fibrosis possibly by regulating the inflammatory response and Wnt/β-catenin signaling. This study provides evidence that augmentation of HO-1 levels may be a therapeutic strategy against renal interstitial fibrosis.     

PDGF receptor kinase blocker AG1295 attenuates interstitial fibrosis in rat kidney after unilateral obstruction

The current study was designed to investigate possible effects of the platelet-derived growth factor (PDGF) receptor kinase blocker AG1295 on the development of interstitial fibrosis in rats with unilateral ureteral obstruction (UUO), monitored by ED-A⁺ fibronectin expression, the number of macrophages, and the presence of myofibroblasts as visualized by immunohistochemistry with monoclonal antibodies (mAb) IST9, mAb ED1, and mAb 1A4, respectively; interstitial fibrosis was quantified by Sirius-Red staining and computer-aided image analysis. Without AG1295 treatment, the Sirius-Red stained area of the control kidneys comprised 6.8ǃ.3% of the totally inspected area and increased to 19.0ǃ.9% in animals by 14 days and to 23.4ǃ.7% by 21 days after UUO. The number of macrophages increased from 4.3ǃ.1 in controls to 16.6DŽ.6 in animals at 14 days and to 23.2dž.4 at 21 days after UUO. This was accompanied by an increase in both ED-A⁺ fibronectin deposition and !-smooth muscle actin expression. Treatment with AG1295 (12 mg/kg body weight, daily i.p.) significantly reduced interstitial fibrosis as verified by a smaller Sirius-Red stained area (15.7ǃ.9% in animals at 14 days and 17.0ǂ.7% at 21 days after UUO) and also by a reduced number of macrophages (12.8ǃ.4 in animals at 14 days and 15.5Dž.8 at 21 days after UUO), and by the ED-A⁺ fibronectin deposition and the number of cells positive for !-smooth muscle actin. The study indicates that the PDGF receptor kinase blocker AG1295 is able to decrease interstitial fibrosis in the rat UUO model significantly. The diminution of early fibrosis mediators, i.e., macrophages, ED-A⁺ fibronectin, and myofibroblast phenotype, points to a modulated fibrosis process via a blockade of PDGF actions.     

Tubulointerstitial macrophage accumulation is regulated by sequentially expressed osteopontin and macrophage colony-stimulating factor: implication for the role of atorvastatin

Infiltration and local proliferation are known factors that contribute to tubulointerstitial macrophage accumulation. This study explored the time course of these two contributors' roles as tubulointerstitial inflammation and fibrosis progressing, and evaluated the mechanisms of the protective effect of atorvastatin. Unilateral ureteral obstructive (UUO) rats were treated with atorvastatin (10 mg/Kg) or vehicle. Expression of osteopontin (OPN) and macrophage colony-stimulating factor (M-CSF) was evaluated by RT-PCR and immunohistochemistry. Immunohistochemistry staining of ED1 was used to assess macrophage accumulation in interstitium. Histological evaluation was performed to semiquantify tubulointerstitial fibrosis. The results showed that on day 3 after UUO operation, OPN expression significantly increased and positively correlated with the number of the interstitial ED1(+) cells, while on day 10, M-CSF expression upregulated and correlated with interstitial ED1(+) cells. In atorvastatin treatment group, the increments of these two factors were attenuated significantly at the two time points, respectively. ED1(+) cell accumulation and fibrosis also ameliorated in the treatment group. For all the samples of UUO and treatment group on day 10, ED1(+) cells also correlated with interstitial fibrosis scores. The results suggest that OPN may induce the early macrophage/monocyte infiltration and M-CSF may play an important role in regulating macrophage accumulation in later stage of UUO nephropathy. Statin treatment decreases interstitial inflammation and fibrosis, and this renoprotective effect may be mediated by downregulating the expression of OPN and M-CSF.     

Transplantation of endothelial progenitor cells alleviates renal interstitial fibrosis in a mouse model of unilateral ureteral obstruction

AimsThe present study investigated whether transplantation of bone marrow-derived endothelial progenitor cells (BM-EPCs) in renal capillary network improves renal interstitial fibrosis in unilateral ureteral obstruction (UUO) model in mice.Main methodsEx vivo generated, characterized, and cultivated mice BM-EPCs were identified by their vasculogenic properties in vitro. BM-EPCs were labelled with carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) before transplantation. The animal models of UUO were used. Histological changes in renal tubular interstitium were observed with HE and Masson staining. The protein levels of vascular endothelial growth factor(VEGF), hypoxia inducible factor-1α (HIF-1α) and connective tissue growth factor (CTGF) were analyzed by western blotting and immunohistochemistry. Transforming growth factor-β1 (TGF-β1) was detected by immunohistochemistry. Peritubular capillary (PTC) density was determined by CD31 immunostaining.Key findingsTransplanted BM-EPCs were successfully incorporated into the capillary network in the obstructed kidney in vivo. UUO induced a significant decrease in VEGF levels and PTC density in the kidney tissue, which was accompanied by a significant increase in HIF-1α, CTGF and TGF-β1. Transplantation of BM-EPCs increased PTC density, VEGF expression and alleviated the development of renal interstitial fibrosis in UUO mice. No significant pathological changes were found in control mice.SignificanceThe reduction of PTC density and up-regulation of HIF-1α are the important mechanisms of interstitial fibrosis in UUO mice. BM-EPCs transplantation may increase the number of capillary density and alleviate the development of renal fibrosis in obstructive nephropathy in mice.     

CD39 overexpression does not attenuate renal fibrosis in the unilateral ureteric obstructive model of chronic kidney disease

Chronic kidney disease has multiple etiologies, but its single, hallmark lesion is renal fibrosis. CD39 is a key purinergic enzyme in the hydrolysis of ATP and increased CD39 activity on regulatory T cells (Treg) is protective in adriamycin-induced renal fibrosis. We examined the effect of overexpression of human CD39 on the development of renal fibrosis in the unilateral ureteric obstructive (UUO) model, a model widely used to study the molecular and cellular factors involved in renal fibrosis. Mice overexpressing human CD39 (CD39Tg) and their wild-type (WT) littermates were subjected to UUO; renal histology and messenger RNA (mRNA) levels of adenosine receptors and markers of renal fibrosis were examined up to 14 days after UUO. There were no differences between CD39Tg mice and WT mice in the development of renal fibrosis at days 3, 7, and 14 of UUO. Relative mRNA expression of the adenosine A_2A receptor and endothelin-1 were higher in CD39Tg than WT mice at day 7 post UUO, but there were no differences in markers of fibrosis. We conclude that human CD39 overexpression does not attenuate the development of renal fibrosis in the UUO model. The lack of protection by CD39 overexpression in the UUO model is multifactorial due to the different effects of adenosinergic receptors on the development of renal fibrosis.     

Chemokine receptor 5 blockade modulates macrophage trafficking in renal ischaemic-reperfusion injury

Chemokine receptor 5 (CCR5) is a pivotal regulator of macrophage trafficking in the kidneys in response to an inflammatory cascade. We investigated the role of CCR5 in experimental ischaemic-reperfusion injury (IRI) pathogenesis. To establish IRI, we clamped the bilateral renal artery pedicle for 30 min and then reperfused the kidney. We performed adoptive transfer of lipopolysaccharide (LPS)-treated RAW 264.7 macrophages following macrophage depletion in mice. B6.CCR5^−/− mice showed less severe IRI based on tubular epithelial cell apoptosis than did wild-type mice. CXCR3 expression in CD11b⁺ cells and inducible nitric oxide synthase levels were more attenuated in B6.CCR5^−/− mice. B6.CCR5^−/− mice showed increased arginase-1 and CD206 expression. Macrophage-depleted wild-type mice showed more injury than B6.CCR5^−/− mice after M1 macrophage transfer. Adoptive transfer of LPS-treated RAW 264.7 macrophages reversed the protection against IRI in wild-type, but not B6.CCR5^−/− mice. Upon knocking out CCR5 in macrophages, migration of bone marrow-derived macrophages from wild-type mice towards primary tubular epithelial cells with recombinant CCR5 increased. Phospho-CCR5 expression in renal tissues of patients with acute tubular necrosis was increased, showing a positive correlation with tubular inflammation. In conclusion, CCR5 deficiency favours M2 macrophage activation, and blocking CCR5 might aid in treating acute kidney injury.     

Fight-or-flight: murine unilateral ureteral obstruction causes extensive proximal tubular degeneration, collecting duct dilatation, and minimal fibrosis

Unilateral ureteral obstruction (UUO) is the most widely used animal model of progressive renal disease. Although renal interstitial fibrosis is commonly used as an end point, recent studies reveal that obstructive injury to the glomerulotubular junction leads to the formation of atubular glomeruli. To quantitate the effects of UUO on the remainder of the nephron, renal tubular and interstitial responses were characterized in mice 7 and 14 days after UUO or sham operation under anesthesia. Fractional proximal tubular mass, cell proliferation, and cell death were measured by morphometry. Superoxide formation was identified by nitro blue tetrazolium, and oxidant injury was localized by 4-hydroxynonenol and 8-hydroxydeoxyguanosine. Fractional areas of renal vasculature, interstitial collagen, α-smooth muscle actin, and fibronectin were also measured. After 14 days of UUO, the obstructed kidney loses 19% of parenchymal mass, with a 65% reduction in proximal tubular mass. Superoxide formation is localized to proximal tubules, which undergo oxidant injury, apoptosis, necrosis, and autophagy, with widespread mitochondrial loss, resulting in tubular collapse. In contrast, mitosis and apoptosis increase in dilated collecting ducts, which remain patent through epithelial cell remodeling. Relative vascular volume fraction does not change, and interstitial matrix components do not exceed 15% of total volume fraction of the obstructed kidney. These unique proximal and distal nephron cellular responses reflect differential "fight-or-flight" responses to obstructive injury and provide earlier indexes of renal injury than do interstitial compartment responses. Therapies to prevent or retard progression of renal disease should include targeting proximal tubule injury as well as interstitial fibrosis.