外源性硫化氢抑制TLR2和TLR4表达并减轻大鼠肾脏缺血再灌注损伤

目的观察外源性硫化氢(H₂S)供体硫氢化钠(NaHS)能否抑制Toll样受体2(TLR2)和Toll样受体4(TLR4)表达、减轻大鼠肾脏缺血再灌注损伤(IRI)。 方法24只6~8周龄雄性SD大鼠随机分为3组：假手术(Sham)组、肾脏缺血再灌注(I/R)组、NaHS+I/R组。采用右肾切除联合左肾动脉夹闭45 min后再灌注24 h的方法诱导肾IRI。夹闭左肾动脉前，NaHS+I/R组给予NaHS(300 nmol/min)连续输注10 min，Sham组和I/R组则给予等体积生理盐水。分别留取各组腹主动脉血及肾组织标本。Western印迹法检测肾组织TLR2、TLR4蛋白的表达；免疫组织化学法检测肾组织白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)的表达；比色法检测血尿素氮(BUN)、血肌酐(Scr)。HE染色观察肾脏组织学改变；TUNEL法检测肾组织细胞凋亡。 结果与Sham组比较，I/R组的TLR2、TLR4、IL-6、TNF-α表达均增加(P<0.05)，BUN、Scr亦明显升高(P<0.05)，肾小管上皮损伤评分较高(P<0.05)，肾组织凋亡细胞增加(P<0.05)。与I/R组比较，NaHS+I/R组的TLR2、TLR4、IL-6、TNF-α表达均减少(P<0.05)，BUN、Scr亦明显下降(P<0.05)，肾小管上皮损伤评分较低(P<0.05)，肾组织凋亡细胞减少(P<0.05)。 结论外源性H₂S可以抑制TLR2、TLR4途径，减少炎症因子释放及细胞凋亡，减轻大鼠肾脏IRI。     

Ischemia-reperfusion injury activates innate immunity in rat kidneys

BACKGROUND: There is growing evidence of a role of the immune system in the pathophysiology of ischemia-reperfusion (I/R) injury, but the influence of I/R injury on innate immunity is still undetermined. METHODS: Sprague-Dawley rats were used. I/R injury was induced by clamping both renal arteries for 45 min, and the rats were killed 1, 3, 5, and 7 days later. Activation of innate immunity was evaluated in terms of the expression of toll-like receptor (TLR) 2 or TLR4 mRNAs and protein, by the level of the TLR ligand (heat shock protein [HSP] 70), and maturation of dendritic cells by double-label immunohistochemistry of dendritic cells for major histocompatibility complex (MHC) class II antigen. RESULTS: I/R injury increased TLR2 and TLR4 mRNA and protein expression, and they were mainly observed on renal tubular cells. I/R injury also produced endogenous TLR ligand (HSP70) on renal tubular cells. I/R injury increased not only the numbers of dendritic cells but also the production of MHC class II antigen in dendritic cells, suggesting maturation of these cells. Activation of innate immunity was observed at day 1, peaked at days 3 to 5 after I/R injury, and thereafter gradually decreased. CONCLUSIONS: I/R injury rapidly activates the innate immune response.     

Effect of apigenin on apoptosis induced by renal ischemia/reperfusion injury in vivo and in vitro

Objectives: This study aims to investigate the effects and molecular mechanisms of apigenin (ApI) on renal ischemia/reperfusion (I/R) injury in vivo and in vitro.

Methods: In vivo, the left renal artery was clamped for 45?min and the right kidney was removed to study renal I/R injury on Sprague-Dawley (SD) rats. ApI was injected at 60?min before renal ischemia. In vitro, renal tubular epithelial cells (HK-2) were pretreated with or without ApI (20 uM) for 60?min and then treated with hypoxia/reoxygenation (H/R). Renal function, histology, cells apoptosis, and cell viability were tested. Furthermore, the potential molecular mechanisms were assessed.

Results: ApI pretreatment could significantly alleviated the renal function and the pathological damage as well as cells apoptosis after I/R injury. Meanwhile, ApI treatment protects H/R induced HK-2 cell apoptosis in vitro. The results of Western blot showed that ApI significantly increased the expressions of B-cell lymphoma 2 (Bcl-2) and phosphor-AKt (p-AKt), Phosphoinositide 3-kinase (PI3K), while down-regulated the expressions of Caspase3 and Bax induced by H/R injury.

Conclusions: ApI pretreatment can protect renal function against I/R injury and prevent renal tubular cells from apoptosis in vivo and in vitro which might through PI3K/Akt mediated mitochondria-dependent apoptosis signaling pathway.     

Ischemic post-conditioning attenuates renal ischemic reperfusion injury via down-regulation of toll-like receptor 4 in diabetic rats

Background: Ischemia/reperfusion (I/R) injury, which is commonly seen in the field of renal surgery or transplantation, is a major cause of acute renal failure (ARF). The ischemic ARF in diabetic rats is much more severe than that in the normal rats exposed to as same ischemic time. Ischemic post-conditioning (IPO) is a phenomenon by which intermittent interruptions of blood flow in the early phase of reperfusion can protect organs from I/R injury. To determine whether the renal protection effect of IPO mediates by toll-like receptor 4 (TLR4) signaling pathway in diabetic rats.

Methods: Streptozotocin-induced diabetic rats were randomly divided into three groups: sham operation group, I/R group, and IPO group. Except sham operation group, rats were subjected to 30?min of renal ischemia, both with and without treatment with IPO, then reperfusion 24?h. Light microscope and transmission electronic microscope were used to observe structural changes of renal tubule. RT-PCR was used to measure TLR4 and tumor necrosis factor-alpha (TNF-α) mRNA expression level, renal TLR4 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) protein expression was detected by Western blot.

Results: The results demonstrated that IPO markedly decreased renal ischemic injury caused by I/R and inhibited the proinflammatory expression levels of TLR4, TNF-α, and NF-κB, all of which up-regulated by I/R in diabetic rats.

Conclusion: Taken together, our results suggest that proper IPO may have protective effect on the ischemic injury mediated by renal I/R, which might be associated with inhibition of TLR4 signaling pathway in diabetic rats.     

Toll-like receptor 4 is protective against neonatal murine ischemia-reperfusion intestinal injury

Purpose

Premature infants receiving probiotics have a decreased incidence of necrotizing enterocolitis. This may be mediated by intestinal bacterial signaling via toll-like receptors (TLRs) 2 and 4 maintaining intestinal homeostasis. We hypothesized that TLRs 2 and 4 are protective against ischemia-reperfusion (I/R) intestinal injury.

Methods

Two-week-old C57BL/6 wild-type (WT), B6.TLR2^−/−, B6.TLR4^−/−, B6.TLR2^−/−4^−/−, and microbially reduced (antibiotic-treated) mice (MR) underwent 60 minutes of superior mesenteric artery occlusion (I) followed by 90 minutes of reperfusion (R). Small intestine was harvested for analysis of microscopic injury, apoptosis, and inflammatory gene expression using quantitative polymerase chain reaction.

Results

After I/R, the median histologic injury scores of the B6.TLR4^−/−, B6.TLR2^−/−4^−/−, and MR pups were higher than the WT or B6.TLR2^−/− pups that corresponded with greater apoptosis based on terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labeling and activated caspase-3 immunostaining. B6.TLR4^−/−, B6.TLR2^−/−4^−/−, and MR also had elevated tissue innate immunity-associated chemokine and cytokine expression.

Conclusions

Neonatal mice deficient in TLR4, either alone or also deficient in TLR2, as well as those lacking a normal commensal intestinal microbiome are more susceptible to an I/R model of intestinal injury. These results may provide a mechanism for commensal bacterial-mediated protection, which may help to direct further studies to elucidate the mechanism of probiotic protection.     

雷公藤内酯醇对大鼠肾缺血再灌注损伤时Toll样受体4表达的影响

目的 观察雷公藤内酯醇(TRI)对大鼠肾缺血再灌注损伤时肾组织中Toll样受体4(TLR4)表达的影响.方法 随机将51只Wistar大鼠分为3组.(1)阴性对照组(n=15):游离双侧肾脏,切除右肾,缝合腹壁.(2)缺血再灌注组(n=18):实验过程与阴性对照组相同,但在切除右肾和游离左肾之后,将左肾动、静脉夹闭45 min,然后开通.(3)TRI处理组(n=18):肾缺血再灌注前3 d经大鼠腹腔注射TRI 0.4 mg/kg,每天1次,连续3 d,其他实验过程与缺血再灌注组相同.肾缺血再灌注1、3、5 d后,分别采用全自动生化分析仪检测血清尿素氮(BUN)和肌酐(Cr)的含量;逆转录聚合酶链反应(RT-PCR)方法检测肾组织中TLR4 mRNA的表达水平;免疫印记法(Western blot)检测肾组织中TLR4表达水平.结果 肾缺血再灌注1、3、5 d后,缺血再灌注组和TRI处理组血清BUN及Cr均明显高于阴性对照组(P＜0.01),肾组织中TLR4 mRNA和TLR4的表达也明显高于阴性对照组(P＜0.05);但与缺血再灌注组比较,TRI处理组血清BUN和Cr明显降低(P＜0.01),肾组织中TLR4 mRNA和TLR4的表达也显著降低(P＜0.05).结论 雷公藤内酯醇可以减轻肾缺血再灌注损伤,其机制可能是通过抑制TLR4的表达而发挥作用的.     

Protective Effects of Toll-like Receptor 4 Inhibitor Eritoran on Renal Ischemia-Reperfusion Injury

Background

Ischemia-reperfusion injury (I/R) has a negative effect on renal allograft survival. Using a rat model of kidney IR injury, we demonstrated inhibition of Toll-like receptor (TLR) 4 with erotoran may shed new light on I/R therapy.

Methods

All 44 Fisher rats were anesthetized with ethrane. Animals were randomly divided into the S group (sham, n = 11) that received only right kidney nephrectomy or the I/R group of right kidney nephrectomy and ichemia for 40 minutes by clamping of left renal artery (n = 11). In addition, the E group (Eritoran, n = 11) and the V group (vehicle, n = 11) received eritoran (5 mg  ·  kg⁻¹) and vehicle pretreatment, respectively. Analysis of renal histology, function, cytokine/chemokine production, as well as animal mortality was performed in parallel groups by ribonuclease protection assay (RPA).

Results

At 24 hours, the creatinine value 1.49 ± 0.2 mg/dL in the eritoran group was significantly lower than untreated controls (2.17 ± 0.4 mg/dL). Histological findings showed tubular loss and morphological stutus as well as animal survival post-I/R injury compared to vehicle-treated rats; the difference between the S versus E groups was significant. Eritoran administration significantly attenuated monocyte infiltration into the kidney. RPA assays showed the following fold increase over sham normalized to that of GAPDH mRNA expression of tumor necrosis factor-α (4.67 ± 1.52 vs 1.37 ± 0.05), interleukin (IL)-1β (5.11 ± 1.17 vs 1.92 ± 0.27), IL-6 (4.20 ± 0.29 vs 1.21 ± 0.37) and monocyte chemoattractant protein-1 (8.77 ± 1.24 vs 2.57 ± 1.59). GAPDH was markedly reduced by eritoran treatment (eritoran vs vehicle group).

Conclusion

These data demonstrated that inhibition of TLR4 with eritoran reduced I/R-related inflammatory responses and improved the course of kidney I/R injury.     

The effects of preoperative immunosuppressive therapy on ischemia and reperfusion (I/R) injury in healthy rats

Purpose

Warm-ischemia-induced injuries might be encountered during renal transplants from cadavers and healthy donors. Toll-like receptors (TLR) in ischemia–reperfusion (I/R) injury are one of the indicators of intracellular injury pathways. The intensity of ischemic injury is directly proportionate to high TLR levels. To minimize the I/R injury, we investigated TLR2 and TLR4 levels on rats, which were pretreated with tacrolimus (FK506) before I/R.

Methods

Eight Wistar albino rats in the study group were administered .01 mg/kg intramuscular tacrolimus. Administration to the study group was performed 24 and 1 h before warm ischemia. Eight rats in the control group were injected with 0.1 c.c. of distilled water. Blood samples were collected from the tail veins of all the rats on the first, second and third days. Expression levels of TLR2 and TLR4 genes were analyzed using the polymerase chain reaction method, to determine any significant difference between the control and study groups on the days when blood was taken.

Results

TLR2 (p = 0.045) and TLR4 (p = 0.022) levels in the study group were found to be statistically, and significantly, lower than those in the control group, on the second day following warm-ischemia- and reperfusion-induced injury.

Conclusions

Administration of immunosuppressive drugs to healthy donor rats led to a statistically significant reduction in the expression levels of TLR2 and TLR4 in the early period. In light of the data obtained by this study, we hypothesize that a preoperative therapy on donors might have a role in preventing I/R injury.     

垂体中叶素对肾脏缺血再灌注大鼠肾小管上皮细胞凋亡的影响及其机制

目的 探讨垂体中叶素（IMD）对肾脏缺血再灌注（I/R）大鼠肾小管上皮细胞凋亡的影响及相关机制。 方法 健康雄性Wistar大鼠24只随机分为假手术组、I/R组、空质粒组、IMD质粒组。动物右肾切除后,采用超声微泡法,将空质粒或IMD质粒转染入左肾,1周后制作肾脏I/R模型。TUNEL法测定细胞凋亡;半定量RT-PCR检测Bax、Bcl-2、Fas的mRNA表达水平;比色法检测caspase-8、-9的活性;Western印迹法检测caspase-3蛋白的表达水平。 结果 与假手术组相比,I/R组细胞凋亡率增高,Bax、Fas mRNA表达增加,bcl-2 mRNA表达下降,caspase-8、-9活性增强,caspase-3蛋白表达增加（均P < 0.05）。与I/R组相比,IMD转染组细胞凋亡率明显降低,Bax、Fas的mRNA表达下降,bcl-2的mRNA表达增加,caspase-8、-9活性减弱,caspase-3蛋白表达减少（均P < 0.05）。转空质粒组与I/R组比较,各指标差异均无统计学意义。 结论 IMD能上调bcl-2表达,降低bax、Fas的表达,降低caspase-8、-9活性,从而抑制肾脏I/R损伤所诱导的凋亡。     

TLR4 Promotes Fibrosis but Attenuates Tubular Damage in Progressive Renal Injury

Toll-like receptors (TLRs) can orchestrate an inflammatory response upon activation by pathogen-associated motifs and release of endogenous stress ligands during tissue injury. The kidney constitutively expresses most TLRs, including TLR4. The function of TLR4 during the inflammation, tubular atrophy, and fibrosis that accompany progressive renal injury is unknown. Here, we subjected wild-type (WT) and TLR4-deficient mice to unilateral ureteral obstruction and observed elevated levels of TLR4 mRNA in the kidney after obstruction. One day after unilateral ureteral obstruction, TLR4-deficient mice had fewer proliferating tubular epithelial cells and more tubular damage than WT mice; however, TLR4-deficient mice developed considerably less renal fibrosis despite decreased matrix metalloproteinase activity and without significant differences in myofibroblast accumulation. In vitro, TLR4-deficient primary tubular epithelial cells and myofibroblasts produced significantly less type I collagen mRNA after TGF-β stimulation than WT cells. The reduced fibrosis in TLR4-deficient mice associated with an upregulation of Bambi, a negative regulator of TGF-β signaling. In conclusion, TLR4 attenuates tubular damage but promotes renal fibrosis by modulating the susceptibility of renal cells to TGF-β. These data suggest that TLR4 signaling may be a therapeutic target for the prevention of renal fibrosis.Fibroproliferative diseases, including progressive renal disease, are a leading cause of morbidity and mortality worldwide.¹ Renal tubular damage, inflammation, and interstitial fibrosis are main predictors for the risk for progression toward end-stage renal failure.² Progression of renal fibrosis involves a cascade of pathophysiologic processes, including disruption of tubular integrity, a robust inflammatory response, accumulation of (myo)fibroblasts, tubular atrophy, and an increased deposition of extracellular matrix (ECM) components, resulting in fibrogenesis.^3–5The group of Toll-like receptors (TLRs) may be one of the receptor families that orchestrate this cascade of inflammation, myofibroblast accumulation, and fibrosis in the kidney. TLRs can initiate an inflammatory response upon recognition of specific pathogen-associated molecular patterns. It is widely accepted that not only pathogen-associated molecular patterns can trigger TLR-mediated immune responses but endogenous danger molecules that are released upon tissue or cell injury as well.^6–11 We already found that several of these endogenous ligands that can potentially activate both TLR2 and TLR4^9,11–13 are strongly upregulated in murine kidneys after unilateral ureteral obstruction (UUO).^14,15 We demonstrated that TLR2 does not play a role in the development of fibrosis or injury after UUO.¹⁴ Until now, the role of TLR4 in progressive renal injury and fibrosis has remained unknown. In a model of hepatic fibrogenesis, it was demonstrated that TLR4 can enhance TGF-β signaling and myofibroblast activation, suggesting that TLR4 can function as a molecular link between proinflammatory and profibrogenic signals in liver tissue.¹⁶ Interestingly, TLR4 is widely and constitutively expressed in the kidney (e.g., on tubular epithelial cells [TECs]).^17,18 We and others have shown that renal-associated TLR2 and TLR4 can induce an exaggerated inflammatory response in the kidney upon acute ischemic renal injury with subsequent detrimental effects on renal histology and function.^19–21 To study the role of TLR4 in progressive renal injury and renal fibrosis, we subjected wild-type (WT) and TLR4−/− mice to UUO.     

Toll-Like Receptor Signaling in Liver Ischemia and Reperfusion

ABSTRACT

Liver ischemia–reperfusion (I/R) injuries are significant clinical challenges implicated in various hepatic surgical procedures and transplantations. Associated with varying degrees of insult, the hallmark of I/R is the excessive inflammatory response potentiated by the host immune system. Toll-like receptors (TLRs), known to play an important role in pathogen-derived inflammation, are now thought to participate in I/R injury-derived inflammation signaling pathways. Endogenous particles (proteins, cytokines, nucleic acids) that are released from damaged host cells bind to TLR2, TLR4, and TLR9, resulting in even further injury by subsequent inflammatory reactions and activation of the innate immune system. This review aims to systematically examine the current literature about TLR signaling mechanisms, allowing for a greater understanding of the precise role of TLRs in hepatic I/R injuries.     

基于NOD2信号通路探讨NADPH抑制剂对肾脏缺血再灌注损伤的影响

目的基于抑制核苷酸寡聚化结构域蛋白-2(nucleotide-binding oligomerization domain-2,NOD2)信号通路,探讨NADPH抑制剂对大鼠肾脏缺血再灌注损伤(ischemia/reperfusion injury,IRI)的影响及作用机制。方法将雄性Wistar大鼠切除右肾,并随机分为4组:①肾脏缺血再灌注(I/R)组:给予等量生理盐水预处理后夹闭左肾动脉制备IRI模型;②I/R组+氯化二碘联苯(diphenylene iodonium,DPI)组:给予DPI预处理后夹闭左肾动脉制备IRI模型;③I/R组+4-羟基-3甲氧基苯乙酮(4-hydroxy-3-methoxyacetophenone,Apocynin)组:给予Apocynin预处理后夹闭左肾动脉制备肾脏IRI模型;④假手术(Sham)组:给予等量生理盐水处理后不予夹闭左肾动脉。试验结束24 h后收集各组大鼠血及肾组织标本,采用Western blot法分别对NOD2、核因子κB(nuclear factor-κB,NF-κB)、半胱氨酸蛋白酶(Caspase-1)的表达进行检测;采用实时定量PCR法对NOD2 mRNA的表达进行检测;采用HE染色法观察肾脏组织学改变;采用免疫组织化学法检测肾组织炎症因子IL-1β的表达。结果与Sham组比较,I/R组的大鼠肾组织NOD2、NF-κB蛋白、Caspase-1表达显著增加(P<0.05);NOD2 mRNA表达显著增加(P<0.05);I/R组肾脏病理表现为肾小管上皮细胞水肿、坏死,脱落于管腔,肾间质炎性细胞浸润,肾小管损伤评分明显增加(P<0.05)。与I/R组相比,I/R+Apocynin组和I/R+DPI组的NOD2、NF-κB蛋白、Caspase-1表达均显著减少(P<0.05),NOD2 mRNA表达显著减少(P<0.05),肾脏病理显示急性肾小管坏死程度减轻,肾小管损伤评分显著减低(P<0.05)。结论抑制氧化应激可通过阻断NOD2受体信号通路来减轻肾脏IRI过程。     

Bcl-2 Protects Tubular Epithelial Cells From Ischemia/Reperfusion Injury by Dual Mechanisms

Ischemia/reperfusion (I/R) injury, which induces extensive loss of tubular epithelial cells, is associated with delayed graft function following kidney transplantation. Recent reports have suggested that cell death by I/R injury occurs by autophagy, a cellular degradation process responsible for the turnover of unnecessary or dysfunctional organelles and cytoplasmic proteins, as well as by apoptosis. Recently, we demonstrated that overexpression of the anti-apoptotic factor, Bcl-2, inhibited tubular apoptosis and subsequent tubulointerstitial damage after I/R injury. Autophagy is also observed in cells undergoing cell death in several diseases. Therefore, we hypothesized that increased Bcl-2 protein may protect tubular epithelial cells by suppressing autophagy and inhibiting apoptosis. In the present study, a transgenic mouse model (LC3-GFP TG) in which autophagosomes are labeled with LC3-GFP and Bcl-2/LC3-GFP double transgenic mice (Bcl-2/LC3-GFP TG) were used to examine the effect of Bcl-2 on I/R-induced autophagy. I/R injury, which is associated with marked disruption of normal tubular morphology, promoted the formation of LC3-GFP dots, representing extensively induced autophagosomes. On electron microscopy, the autophagosomes contained mitochondria in I/R-injured tubular epithelial cells. In contrast, Bcl-2 augmentation suppressed the formation of autophagosomes and there was less tubular damage. In conclusion, Bcl-2 augmentation protected renal tubular epithelial cells from I/R injury by suppressing autophagosomal degradation and inhibiting tubular apoptosis.     

HO-1 upregulation suppresses type 1 IFN pathway in hepatic ischemia/reperfusion injury

Upregulation of heme oxygenase (HO)-1, a heat shock protein 32, protects against hepatic ischemia/reperfusion (I/R) injury. Activation of "innate" toll-like receptor (TLR) 4 system triggers the I/R injury cascade. This study explores cytoprotective functions of HO-1 overexpression following exogenous administration of cobalt protoporphyrin (CoPP), and its relationship with the TLR4 pathway in a model of mouse partial hepatic warm I/R injury. CoPP treatment markedly improved hepatic function and histology, and suppressed pro-inflammatory cytokine elaboration profile, as compared with untreated controls. Although administration of CoPP did not affect intrahepatic TLR4, it downregulated IFN-inducible protein 10 (IP-10) expression. As IP-10 is the major product of type-1 IFN pathway downstream of TLR4, we then infused recombinant IFN-beta (rIFN-beta) directly into mouse livers. Interestingly, infusion of rIFN-beta upregulated hepatic IP-10 expression. In contrast, adjunctive CoPP treatment decreased IP-10 levels in mouse livers infused with rIFN-beta. Thus, CoPP-induced HO-1 upregulation suppresses type-1 IFN pathway downstream of TLR4 system in hepatic warm I/R injury model.     

Receptor activator of the NFκB ligand system protects renal function during experimental renal ischemia-reperfusion in mice

Renal ischemia-reperfusion (I/R) injury is closely associated with delayed graft function and poor long-term graft survival following transplantation. Various pathophysiologies can cause the deterioration of renal function; however, the immune system plays important roles in promoting and protecting renal tissues. Receptor activator of NFκB ligand (RANKL) is a member of the TNF superfamily and is produced by bone-forming osteoblasts; the receptor for RANKL is called RANK. In bone biology, RANKL-RANK signaling has been extensively studied, but its roles in the immune system are still obscure. We investigated the role of the RANK system in I/R injury of the kidney using an experimental mouse I/R model. The left renal pedicles of 10-week-old male mice were clamped for 60 min, and reperfusion and right nephrectomy were simultaneously performed. Separate groups were administered an anti-RANKL antibody and recombinant RANKL (rRANKL) 24 h prior to I/R. After reperfusion for a set period of time, the serum creatinine level was measured, and the left kidney was removed for histological examination and western blotting to evaluate the expression and localization of RANK-associated molecules and cytokines. The serum creatinine levels were significantly elevated after I/R injury. A time-dependent increase in RANKL was observed up to 24 h, whereas RANK was induced for 12 h after reperfusion. RANK was expressed in infiltrating inflammatory cells, which were positive for CD68, a marker of monocytes/macrophages. The pre-treatment with the anti-RANKL antibody significantly impaired renal function and increased the induction of inflammatory cytokines (TNFα and IL-6), Toll-like receptor (TLR4) and MyD88 (all p < .05) compared to the levels in the I/R group. However, rRANKL significantly improved renal function and decreased the levels of inflammatory cytokines (TNFα and IL-6), TLR4 and MyD88 (p < .05) compared to those in the I/R group. The present study is the first to evaluate the role of the RANK system in renal I/R injury. RANKL-RANK signaling affects macrophage function and results in the downregulation of TLR4 and reduction in TNFα and IL-6, leading to improved renal function following I/R injury.     

Silymarin attenuates the renal ischemia/reperfusion injury-induced morphological changes in the rat kidney

OBJECTIVES: Renal ischemia/reperfusion (I/R) injury is associated with increased mortality and morbidity rates due to acute renal failure (ARF). Oxidative stress induced with renal I/R injury directly affects glomerular and tubular epithelium through reactive oxygen species. Several studies have been directed to the treatment of renal I/R injury. The aim of this study was to test the attenuation with silymarin (SM) treatment of renal I/R injury-induced morphological changes in the rat kidney. METHODS: A total of 32 adult male Sprague-Dawley rats were evaluated in four groups. Group I (sham), Group II (renal I/R), Group III (renal I/R injury + SM 50 mg per kg) and Group IV (renal I/R injury + SM 100 mg per kg) were designed to evaluate the dose-dependent effects of SM on the morphological changes of renal I/R injury. Renal I/R injury were induced with left renal pedicle occlusion for 45 min followed with reperfusion for 6 h under anesthesia. After induction of I/R injury, left nephrectomies were performed for histopathological examinations. RESULTS: After renal I/R injury, significant tubular dilatation, tubular vacuolization, pelvic inflammation, interstitial inflammation, perirenal adipose infiltration, tubular necrosis and glomerular necrosis (cortical necrosis) were observed. However, even with low dose SM in Group III (50 mg per kg SM), histopathological changes due to I/R injury were prevented. CONCLUSIONS: The results of this study have demonstrated that SM significantly prevents renal I/R injury-induced renal tubular changes in the rat. SM in 50 mg/kg was observed to be sufficient to significantly prevent renal tubular necrosis. Further, to our literature knowledge, this is the first specific study to demonstrate the preventive effect of SM on renal I/R injury.     

Effects of Intravenous Anesthetics on Renal Ischemia/Reperfusion Injury

Background. Renal ischemia/reperfusion (I/R)-induced tubular epithelial cell injury, called ischemic acute renal failure, is associated with high mortality in humans. Protecting the kidney against I/R injury is very important during complicated renal operations, transplantation surgery, and anesthesia. Aim. The purpose of this study was to investigate and compare the efficiency of ketamine, thiopental, propofol, etomidate, and intralipid in reducing the injury induced by free radicals in a rat model of renal I/R. Method. Forty-two Wistar rats were divided into seven groups in our study. Rats in the sham group underwent laparotomy and waited for 120 minutes (min) without ischemia. Rats in the control group were given nothing with ischemia-reperfusion. Rats in the I/R groups were given ketamine (20 mg/kg), thiopental (20 mg/kg) propofol (25 mg/kg), etomidate (10 mg/kg) and 10% intralipid (250 mg/kg) intraperitoneally 15 min prior to the ischemia for 60 min, followed by reperfusion for 60 min. The blood samples and kidney tissues of the rats were obtained under anesthesia at the end of the reperfusion period. Biochemical malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), blood urea nitrogen (BUN), creatine (Cr), aspartate aminotransferase (AST) were determined, and histopathological analysis was performed with these samples. Results. MDA level was increased significantly in the control group (p < 0.05). Histopathological findings of the control group confirmed that there was renal impairment by tubular cell swelling, interstitial edema, medullary congestion, and tubular dilatation. MDA levels were lower in the ketamine, thiopental, and propofol groups compared to the control group (p < 0.05). In the thiopental and propofol groups, the levels of histopathological scores were significantly lower than control and etomidate groups in ischemia-reperfusion. Conclusion. Our results demonstrated that I/R injury was significantly reduced in the presence of propofol and thiopental. The protective effects of these drugs may belong to their antioxidant properties. These results may indicate that propofol and thiopental anesthesia protects against functional, biochemical, and morphological damage better than control in renal I/R injury.