Suramin promotes recovery from renal ischemia/reperfusion injury in mice

Suramin is a polysulfonated naphthylurea originally designed as a treatment for trypanosomiasis; but that has also been used to treat rodent models of fulminant hepatic failure and focal brain ischemia. In this study, we determined the effects of suramin on renal ischemia/reperfusion-induced acute kidney injury in mice, in particular its effect when administered after renal injury has been established. Increasing concentrations of suramin were given 24 hours following reperfusion, a time when serum creatinine levels were at their highest level. This treatment improved renal function, as evidenced by decreased blood urea nitrogen and serum creatinine to control values and diminished histopathologic tubular damage. Suramin-treated animals had a significant reduction in apoptotic tubular cells and infiltrating leukocytes. There was also an increase of proliferating tubular cells following reperfusion compared to the number found in untreated animals. Our study shows that suramin promotes the recovery of renal function and has effective therapeutic applications when given after the occurrence of renal injury.     

Melatonin ameliorates renal ischemia/reperfusion injury

BACKGROUND: We studied whether melatonin is able to reduce organ damage during renal ischemia/reperfusion via its effects on the oxidative response in early and late reperfusion. MATERIALS AND METHODS: Renal ischemia/reperfusion injury (I/R) was induced in two groups of rats by 75 min occlusion of the left renal artery and vein and right nephrectomy, followed by reperfusion. The formation of reactive oxygen species was evaluated in the early reperfusion phase (60 min) by lipid peroxidation products and glutathione assay. In the late reperfusion phase (24 h) tissue neutrophil infiltration, inducible nitric oxide synthase (iNOS) gene expression, and histopathology were evaluated. Groups received either systemic melatonin (MEL) or normal saline (NS). There were two nonischemic sham control groups, one with and another without melatonin (S+MEL and S). RESULTS: Creatinine was higher in the NS group at all times. A reduction in glutathione and increases in lipid peroxidation products and myeloperoxidase activity induced by I/R indicated renal injury involving reactive oxygen formation. Melatonin reversed this oxidant response and reduced the rise in creatinine and iNOS expression. Seven-day group survivals were 5/10 for NS, 8/10 for MEL, and 10/10 for both Sham groups. CONCLUSIONS: Exogenous melatonin is able to preserve renal functional status following I/R-induced injury by increasing glutathione and reducing lipid peroxidation in the early reperfusion phase, without any apparent effect on neutrophil infiltration in the late reperfusion phase.     

胆总管结扎预适应减轻小鼠肾脏缺血再灌注损伤

目的 探讨胆总管结扎预适应减轻小鼠肾脏缺血再灌注损伤的可能机制.方法 C57BL/6小鼠分为3组进行实验.胆总管结扎预适应组(CBDL组)结扎胆总管(d0),2d后(d2)再通,再过2d后(d4)行左肾缺血再灌注手术;假手术组仅结扎胆囊管(d0),d4再行左肾缺血再灌注手术;对照组不进行任何处理.监测血胆红素总量(TBil)的变化情况.肾脏缺脏再灌注后24 h(dS)检测各组小鼠血清肌酐(Cr).蛋白质印迹法检测CBDL组和假手术组肾脏热休克蛋白27 (HSP-27)和内皮型一氧化氮合酶(eNOS)的表达情况.结果 CBDL组胆总管结扎2d后,TBil达到最高,再通2d后,TBil基本降至正常水平.CBDL组Cr低于假手术组(P＜0.05).CBDL组HSP-27和eNOS的表达量高于假手术组(P＜0.05).结论 胆道结扎预适应能明显减轻小鼠肾脏缺血再灌注损伤,其机制可能与引起肾脏局部HSP-27和eNOS高表达有关.     

静脉注射含饱和氢气生理盐水减轻小鼠肾脏缺血再灌注损伤

目的 研究静脉注射含饱和氢气生理盐水对小鼠肾脏缺血再灌注(IR)损伤的保护作用及其机制.方法 健康、雄性的C57BL/6小鼠随机分为3组,每组10只.假手术组(SO组)小鼠仅接受中线开腹、双侧肾蒂游离及关腹操作;缺血再灌注组(IR组)小鼠用无损伤动脉夹同时钳夹双侧肾蒂,阻断45 min,制成肾脏IR损伤模型,并于肾脏缺血同时经尾静脉注射生理盐水,5 ml/kg;实验组小鼠制成肾脏IR损伤模型,并于肾脏缺血同时经尾静脉注射含饱和氢气生理盐水,5 ml/kg.各组小鼠于肾脏再灌注6 h时检测血清尿素氮(BUN)和肌酐(Scr);检测肾组织中丙二醛(MDA)和髓过氧化物酶(MPO)的含量;观察肾脏组织形态学变化并检测肾小管上皮细胞的凋亡情况;观察肾组织中巨噬细胞的浸润情况;检测各组小鼠肾组织中肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、IL-1β和IL-17 mRNA的水平.结果 实验组血清BUN和Scr水平明显低于IR组(P<0.05).实验组肾组织病理改变较IR组明显减轻,其肾小管损伤评分明显低于IR组(P<0.01),肾小管上皮细胞凋亡明显轻于IR组(P<0.05).实验组肾组织内MDA含量低于IR组(P<0.05).实验组小鼠肾组织内中性粒细胞和巨噬细胞的浸润较IR组减少(P<0.05).实验组TNF-α、IL-6、IL-1β和IL-17mRNA的水平均低于IR组(P<0.05).结论 静脉注射含饱和氢气生理盐水能够在一定程度上减轻肾脏IR损伤,其机制可能与抑制肾脏IR后炎症反应有关.     

Earlier renal fibrosis aggravates acute kidney injury induced by ischemia reperfusion in mice

Objective To investigate the influence of earlier renal fibrosis on ischemia and reperfusion induced acute kidney injury. Methods Male C57BL/6 mice at eight to twelve weeks old age were divided into 4 groups randomly: (1)Sham (n=3); (2)Unilateral ureter obstruction (UUO, n=6): UUO for 3 days (UUO3d, n=3) and UUO for 5 days (UUO5d, n=3);(3)Ischemia and reperfusion (IR, n=7): bilateral kidney ischemia for 40 minutes followed by 24 hours of reperfusion; (4)UUO for 3 days plus IR (UUO3d+IR, n=6): bilateral kidney ischemia after UUO 2 days for 40 minutes followed by 24 hours of reperfusion, and the real time for UUO was 3 days. Pathologic analysis for acute or chronic injury was performed on paraffin embedded kidney sections with hematoxylin and eosin (HE) or Masson staining. Apoptosis was detected by immunohistochemistry(IHC) and Western blotting with anti-caspase-3 antibody, and proliferation was observed by IHC with anti-ki67 antibody. Results On kidney sections with HE or Masson staining, it showed that the chronic kidney lesions and fibrosis got more severe as time of UUO prolonged from 3 days to 5 days; the area of matrix deposition increased in UUO5d and UUO3d mice significantly compared to Sham mice (P＜0.05) and was smaller in UUO3d mice compared with UUO5d mice obviously (P＜0.05). Acute kidney injury could be observed in UUO3d+IR mice, such as massive inflammatory cells infiltration, tubules dilation, brush border disappearance, tubular epithelial cells vacuolar degeneration, necrosis, casting formation, coexisting with chronic lesions: thinner cortex, broadened interstitial space, and increased blue stained matrix. Acute kidney injury score in UUO3d+IR mice was higher than that in IR mice significantly (P＜0.05), and serum creatinine level increased significantly in UUO3d+IR mice compared to Sham mice (P＜0.05). Caspase-3 expression increased and ki67 positive tubular cells decreased in UUO3d+IR mice than those in IR mice obviously (P＜0.05). Conclusion Earlier renal fibrosis aggravates acute kidney injury induced by ischemia reperfusion in mice through increasing apoptosis and decreasing proliferation of tubular epithelial cells.     

Mycophenolate mofetil attenuates renal ischemia/reperfusion injury

Immunosuppressive agents may have an impact on ischemia/reperfusion (I/R) injury. The immunosuppressant mycophenolate mofetil (MMF) presents properties that can attenuate such injury. This study investigated the effects of MMF on renal I/R injury. Male Wistar rats received MMF (20 mg/kg per d) or vehicle by gavage beginning 2 d before ischemia and maintained during the entire study. Ischemic injury was induced by bilateral renal arteries occlusion for 60 min. Control rats received MMF and underwent sham operation. At days 1, 2, and 14, post-ischemia renal function was assessed and kidneys were removed for histologic and immunohistochemical studies. MMF given to nonischemic rats did not alter renal function. There was no functional protection at 24 h post-ischemia with MMF. At 2 d, post-ischemia rats pretreated with MMF presented higher inulin clearance compared with untreated rats (0.42 +/- 0.04 versus 0.15 +/- 0.02 ml/min per 100 g; P < 0.001) and attenuated renal blood flow decrease (5.23 +/- 0.28 versus 3.24 +/- 0.37 ml/min; P < 0.01). The immunostaining for intercellular adhesion molecule-1 (ICAM-1) was less intense in rats pretreated with MMF. These rats also presented an earlier decreased infiltrating macrophages/lymphocytes and cell proliferation at day 1 post-ischemia. The functional and immunohistochemical analyses performed at day 14 post-ischemia returned to values similar to controls in both groups of rats. To determine whether mycophenolic acid (MPA) could induce cytoprotection, the effects of MPA on normoxic and hypoxic/reoxygenated (H/R) isolated tubule suspensions were also investigated. MPA was not deleterious to normoxic tubules and it was not protective against H/R tubules. In conclusion, pretreatment with MMF attenuates I/R injury in rats and does not limit the recovery from ischemia. The protective effect of MMF by reducing inflammation precedes the hemodynamic changes and tubular injury.     

Distant effects of experimental renal ischemia/reperfusion injury

Acute renal failure results in significant morbidity and mortality, yet renal failure is not the usual cause of death in the clinical situation. We have previously reported systemic increases in the inflammatory mediators tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) after renal ischemia in the mouse. In the present study, an animal model of bilateral renal ischemia was used to test the hypothesis that cytokines released with renal ischemia have effects on other organ systems. Increased levels of immunoreactive TNF-alpha and IL-1 and intercellular adhesion molecule-1 mRNA were found in the heart after renal ischemia in the rat. This was accompanied by increases in myeloperoxidase activity, an index of tissue leukocyte infiltration, in the heart as well as the liver and lung. Functional changes in the heart 48 h after renal ischemia included increases in left ventricular end diastolic diameter, left ventricular end systolic diameter, and decreased fractional shortening by echocardiography. Evidence of apoptosis of cardiac cells was also found 48 h after an abbreviated period of renal ischemia insufficient to induce azotemia but not bilateral nephrectomy (which resulted in significant renal failure), suggesting that renal ischemia but not uremia is necessary for the apoptosis observed. It was also found that blocking the action of TNF-alpha limited cardiac apoptosis. Renal ischemia results in distant effects and the alterations observed in the heart may be important in the morbidity and mortality observed clinically.     

T cells as mediators in renal ischemia/reperfusion injury

Inflammation has been established to contribute substantially to the pathogenesis of ischemia/reperfusion (I/R) with a central role for particular cells, adhesion molecules, and cytokines. Until recently, most of the research trying to unravel the pathogenesis of I/R injury has been focused on the role of neutrophils. However, recent studies have brought evidence that T cells and macrophages are also important leukocyte mediators of renal and extrarenal (liver) I/R injury. In vivo depletion of CD4+ cells but not CD8+ cells in wild-type mice was protective in I/R of the kidney. A marked preservation of liver function was also found after I/R in T-cell deficient athymic mice. Blocking the b130/CD28 costimulatory pathway by CTLA-4 Ig (recombinant fusion protein) ameliorated renal dysfunction and decreased mononuclear cell infiltration in I/R of the kidney. b130-1 expression was found limited to the membrane of the endothelial cells of the ascending vasa recta, resulting in trapping of CD28-expressing CD4 T cells. This trapping of leukocytes results in the upstream congestion in the ascending arterial vasa recta, generating the since more than 150 years described medullary vascular congestion of the kidney soon after ischemic injury. It seems worthwhile to study a combination therapy using anti-inflammatory/anti-adhesion molecules in the early phase of I/R.     

Hydrogen sulfide reduce renal ischemia/reperfusion injury by NOD-like receptor pathway

Objective To investigate whether the nod-like receptor (NLR) pathway is involved in protection of hydrogen sulfide (H2S) preconditioning during renal ischemia reperfusion. Methods Male Wistar rats were randomly divided into 3 groups: sham operation (Sham) group, renal ischemia/reperfusion (I/R) group subjected to occlusion of left renal pedicle for 45 min then reperfusion for 24 hours, and sodium hydrosulfide (NaHS) preconditioning group with continuous infusion of NaHS (300 nmol/min) by left renal artery for 15 min before I/R treatment. Renal injuries were evaluated by HE staining. The protein levels of NOD1, NOD2, nuclear NF-κB P65 and caspase-1 were analyzed by Western blot assay. The protein level of MCP-1 and IL-1β expressions was determined by immunohistochemical staining assay. Cell apoptosis were evaluated by Tunel staining assay. Results In I/R group, the renal NOD1 and NOD2 protein expressions were upregulated. Moreover, the nuclear NF-κB P65 expression was also elevated with an increase in its target genes-MCP-1 and IL-1β (All P＜0.01). HE staining revealed the existence of acute tubular necrosis in I/R kidney. TUNEL staining revealed more apoptotic cells in risk zone with the activation of caspase-1 of I/R-treated kidney(P＜0.01). NaHS preconditioning reversed I/R-induced increase in the expression of NOD1 and NOD2(P＜0.05). NaHS preconditioning also reduced I/R-induced activation of NF-κB P65 (P＜0.05) and upregulation of MCP-1 and IL-1β (P＜0.01). Moreover, NaHS preconditioning attenuated inflammation, repressed caspase-1 activation and reduced apoptotic cells after I/R. Conclusion Hydrogen sulfide preconditioning can alleviate renal ischemia/reperfusion injury by Nod-like receptor dependent on inflammatory pathway.     

Chemically modified tetracycline improves contractility in porcine coronary ischemia/reperfusion injury

BACKGROUND: Reperfusion of ischemic myocardium has been implicated in extension of infarct size and deleterious clinical outcomes. Anti-inflammatory agents reduce this reperfusion injury. Chemically modified tetracycline-3 (CMT-3) (Collagenex Pharmaceuticals, Newtown, PA, USA) lacks antimicrobial properties yet retains anti-inflammatory activity. We examined infarct size and myocardial function in a porcine coronary artery occlusion/reperfusion model in CMT-3-treated and control animals. METHODS: Yorkshire pigs (n = 8) underwent median sternotomy, pretreatment with heparin (300 U/kg and 67 U/kg/hr IV) and lidocaine (1 mg/kg IV) and were divided into two groups. Group one (n = 4) had the left anterior descending artery (LAD) occluded for 1 hour, after which it was reperfused for 2 hours. Group two (n = 4) had an identical protocol to group one except CMT-3 (2 mg/kg IV) was administered prior to occlusion of the LAD. RESULTS: Animals receiving CMT-3 had significantly decreased infarct size in relation to the ventricular area-at-risk (AAR) (28 +/- 9% vs. 64 +/- 8%; p < 0.05). Myocardial contractile function was superior in the CMT-3 treatment, indicated by a higher cardiac index (2.9 +/- 0.3 vs. 2.0 +/- 0.3 L/min/m(2); p < 0.05) and stroke volume index (22 +/- 2 vs. 17 +/- 1 L/m(2)/beat; p < 0.05). CONCLUSIONS: CMT-3 decreased infarct size in relation to the AAR resulting in relative preservation of contractility, suggesting CMT-3 may improve outcomes during myocardial ischemia reperfusion.     

Inhibiting the complement system does not reduce injury in renal ischemia reperfusion.

The complex pathogenesis of ischemia reperfusion injury (IRI) includes endothelial expression of adhesion molecules, leukocyte recruitment and activation, reactive oxygen species production, and apoptotic and necrotic cell death. A role for complement in IRI of different organs, including kidney, has been proposed on the basis of results of experiments that used pharmacologic inhibitors as well as animals that were deficient in individual complement proteins. Here, renal IRI in mice was examined. Animals that were deficient in C3 had partial protection from IRI induced by 27.5 min of bilateral renal ischemia, followed by 20 h of reperfusion (blood urea nitrogen [BUN] values, 46.6 +/- 6.9 and 68.4 +/- 7.9 mg/dl in C3 -/- and C3 +/+ mice; n = 7 and 8, respectively; P = 0.033). Given the reduction in IRI in C3 -/- mice, it was investigated, by use of the rodent C3 convertase inhibitor CR1-related gene/protein y-Ig (Crry-Ig), whether exogenous administration of a complement inhibitor could lessen renal injury. Despite the use of Crry-Ig in high doses, there was no significant reduction of injury induced by 20 to 30 min of ischemia followed by up to 30 h of reperfusion. Histologic examination revealed acute tubular necrosis and neutrophilic infiltration, both of which correlated significantly with BUN values (P < 0.001). Of interest, C3 deposition around renal tubules was significantly less in animals with IRI, compared with that in unmanipulated controls (P < 0.001). In Crry-Ig-treated animals, C3 deposition was inversely proportional to BUN values (r = -0.63; P < 0.001), which presumably indicates that severe vascular IRI allowed access of the 160 kD Crry-Ig to the interstitium. Thus, renal IRI in mice may have a partial complement dependence, yet pharmacologic inhibition of the complement system does not seem to be effective, likely because of the presence of other mediator systems that operate in parallel.