Lésions d’ischémie-reperfusion rénale

Ischemia-reperfusion-induced renal injury due to profound decrease of renal blood flow followed by restoration of renal perfusion is frequent in critically ill patients. Ischemic-induced microcirculatory dysfunction and perfusion defects persist after reperfusion leading to extension of initial renal damage, renal fibrosis, and acute or chronic renal failure. Renal ischemia-reperfusion should not be regarded as a sole ischemic injury with acute tubular necrosis but involves renal inflammation with infiltration of immune cells with tubular necrosis and apoptosis. Despite numerous promising pre-clinical therapeutic interventions protecting the kidney from ischemic injury, such strategies have been mostly unsuccessful in the clinical setting. Multiplicity of factors involved with complexes mechanisms of injury in most clinical scenarios may explain such discrepancy.     

The role of CXCL10 in the pathogenesis of experimental septic shock

Introduction

The chemokine CXCL10 is produced during infection and inflammation to activate the chemokine receptor CXCR3, an important regulator of lymphocyte trafficking and activation. The goal of this study was to assess the contributions of CXCL10 to the pathogenesis of experimental septic shock in mice.

Methods

Septic shock was induced by cecal ligation and puncture (CLP) in mice resuscitated with lactated Ringer’s solution and, in some cases, the broad spectrum antibiotic Primaxin. Studies were performed in CXCL10 knockout mice and mice treated with anti-CXCL10 immunoglobulin G (IgG). Endpoints included leukocyte trafficking and activation, core body temperature, plasma cytokine concentrations, bacterial clearance and survival.

Results

CXCL10 was present at high concentrations in plasma and peritoneal cavity during CLP-induced septic shock. Survival was significantly improved in CXCL10 knockout (CXCL10KO) mice and mice treated with anti-CXCL10 IgG compared to controls. CXCL10KO mice and mice treated with anti-CXCL10 IgG showed attenuated hypothermia, lower concentrations of interleukin-6 (IL-6) and macrophage inhibitory protein-2 (MIP-2) in plasma and lessened natural killer (NK) cell activation compared to control mice. Compared to control mice, bacterial burden in blood and lungs was lower in CXCL10-deficient mice but not in mice treated with anti-CXCL10 IgG. Treatment of mice with anti-CXCL10 IgG plus fluids and Primaxin at 2 or 6 hours after CLP significantly improved survival compared to mice treated with non-specific IgG under the same conditions.

Conclusions

CXCL10 plays a role in the pathogenesis of CLP-induced septic shock and could serve as a therapeutic target during the acute phase of septic shock.     

Endotoxin tolerance enhances interleukin-10 renal expression and decreases ischemia-reperfusion renal injury in rats

The potential implication of interleukin (IL) 6, tumor necrosis factor alpha (TNF-alpha), and IL-10 in the protective effect of low-dose lipopolysaccharide (LPS) administration against renal ischemia-reperfusion injury was evaluated in a rat model. Eighteen male Sprague-Dawley rats were injected intravenously with either 0.5 mg/kg of LPS (tolerant group) or saline (control group) 2 days before surgery. Ischemic renal injury was induced by clamping the left renal artery for 60 min on rats immediately after right-side nephrectomy. Reperfusion was obtained by clamp removal and was studied at R0 (no reperfusion), 2H (R2), and 24H (R24) by renal tubular disorder characterization and by plasma creatinine as well as renal cytokine (IL-6, IL-10, and TNF-alpha) studies. No differences were observed between the two groups as concerns the period immediately after renal ischemia (R0). The endotoxin-tolerant group was associated with a significantly lower creatinine level at R24 (231 +/- 28 vs 315 +/- 36 micromol/L; P = 0.007). Pretreatment with LPS significantly reduced the degree of proximal tubule necrosis and outer medulla congestion. In such tolerant animals, renal IL-6 production was decreased, whereas IL-10 production was significantly increased at R2 and R24. There were no differences in TNF-alpha renal production. In this study, we demonstrated that administration of low doses of LPS to rats had a protective effect from renal reperfusion injury, and our data suggest that IL-10 might play a role in this phenomenon.     

Adenine nucleotides stimulate migration in wounded cultures of kidney epithelial cells.

Adenine nucleotides speed structural and functional recovery when administered after experimental renal injury in the rat and stimulate proliferation of kidney epithelial cells. As cell migration is a component of renal regeneration after acute tubular necrosis, we have used an in vitro model of wound healing to study this process. High density, quiescent monkey kidney epithelial cultures were wounded by mechanically scraping away defined regions of the monolayer to simulate the effect of cell loss after tubular necrosis and the number of cells that migrated into the denuded area was counted. Migration was independent of cell proliferation. Provision of adenosine, adenine nucleotides, or cyclic AMP increased the number of migrating cells and accelerated repair of the wound. Other purine and pyrimidine nucleotides were not effective. Arginine-glycine-aspartic acid-serine peptide, which blocks the binding of extracellular fibronectin to its cell surface receptor, completely inhibited migration in the presence or absence of ADP. Very low concentrations of epidermal growth factor (K0.5 approximately 0.3 ng/ml) stimulated migration, whereas transforming growth factor-beta 2 was inhibitory (Ki approximately 0.2 ng/ml). Thus, adenosine and/or adenine nucleotides released from injured or dying renal cells, or administered exogenously, may stimulate surviving cells in the wounded nephron to migrate along the basement membrane, thereby rapidly restoring tubular structure and function.     

大鼠肾脏热缺血再灌注损伤过程中水通道蛋白的表达变化

背景:如何有效防治肾脏的缺血再灌注损伤,一直是肾损伤与肾移植过程中众多学者研究的热点,但目前仍然不是很清楚相关实验表明水通道蛋白在这一过程中起重要作用.目的:研究大鼠肾脏缺血再灌注损伤后水通道蛋白1的表达变化与肾功能变化的关系.设计、时间及地点:随机对照动物实验,于2007-06/2008-02在大连医科大学组织胚胎实验室完成.材料:健康成年雌性Wister大鼠80只,随机分为对照组和缺血再灌注组,每组又分为术后1,2,3,5,7 d 5个时间点组,8只/组,建立大鼠左侧肾脏缺血再灌注损伤模型.方法:所有大鼠均摘除右肾,游离左侧肾蒂,缺血再灌注组大鼠用无损伤动脉夹夹闭左侧肾蒂,阻断出入肾脏血流,40 min后重新恢复肾脏血液灌注.当松开动脉夹后肾脏在2～5 min内颜色由暗红转为鲜红表明缺血再灌注损伤模型建立成功,肾血管无血栓形成,关腹.若超过5 min肾脏颜色仍然未转为鲜红色则认为肾脏有血栓形成,排除出缺血再灌注组,不进行夹闭,40 min后关腹.主要观察指标:于缺血再灌注损伤1,2,3,5,7 d处死大鼠,留取尿液、血清、肾脏标本行尿常规、肾功能、肾脏病理形态学及水通道蛋白-1的免疫组化、RT-PCR检测.结果:大鼠肾脏缺血再灌注损伤后出现尿量增多、尿渗透压降低,血肌苷、尿素氮升高症状;苏木精-伊红染色示肾小管上皮细胞肿胀、坏死、脱落;水通道蛋白表达量及其mRNA含量均较对照组减少,这些变化于缺血再灌注损伤 1 d时最低,至缺血再灌注损伤 5 d时恢复正常.结论:肾脏缺血再灌注损伤后水通道蛋白表达的减少可能是急性肾衰竭时反映肾功能变化的重要指标之一.     

Role of endogenous interleukin-10 in local and distant organ injury after visceral ischemia-reperfusion

The anti-inflammatory cytokine interleukin (IL)-10 has been detected in serum after visceral ischemia-reperfusion injury and exogenous IL-10 administration has been shown to attenuate the associated distant organ injury. This study was designed to examine the role that endogenous IL-10 production plays on both local and distant organ injury after visceral ischemia-reperfusion injury. Wild-type and IL-10(-/-)-null C57BL/6 mice were subjected to 20 min of supraceliac aortic occlusion or sham laparotomy. Serum and lung tissue cytokine levels (tumor necrosis factor alpha, IL-1beta, IL-6, KC/GRO, and IL-10) were measured after reperfusion (1, 2, and/or 4 h) using either enzyme-linked immunoassay or bioassay. Lung neutrophil infiltration and injury were quantified after reperfusion injury using myeloperoxidase concentration (2 h) and mean capillary permeability (4 h), respectively, whereas the direct liver injury was quantified with serum aspartate aminotransferase levels (1, 2, and 4 h). A subset of IL-10(-/-)-null animals was administered human recombinant IL-10 before the visceral ischemia and lung MPO was measured after reperfusion (2 h). Visceral ischemia-reperfusion in the wild-type and IL-10(-/-)-null mice was associated with in an increase in both serum (IL-1beta, KC/GRO, IL-6) and lung tissue (IL-1beta, KC/GRO) cytokine levels and resulted in lung neutrophil infiltration (myeloperoxidase), lung injury (mean capillary permeability) and liver injury (aspartate aminotransferase). The magnitude of the lung tissue cytokine response (IL-1beta, KC/GRO), neutrophil infiltration, and injury were greater in the IL-10(-/-)-null mice. Exogenous IL-10 resulted in a decrease in the lung neutrophil infiltration in the IL-10(-/-)-null mice. The endogenous IL-10 response to visceral ischemia-reperfusion attenuates the associated lung neutrophil infiltration and injury but has no effect upon either the hepatic injury or the magnitude of the systemic inflammatory response. The beneficial effects of IL-10 may be mediated by the inhibition of IL-1beta and KC/GRO through an endocrine rather than paracrine signal.     

CSF-1 signals directly to renal tubular epithelial cells to mediate repair in mice

Tubular damage following ischemic renal injury is often reversible, and tubular epithelial cell (TEC) proliferation is a hallmark of tubular repair. Macrophages have been implicated in tissue repair, and CSF-1, the principal macrophage growth factor, is expressed by TECs. We therefore tested the hypothesis that CSF-1 is central to tubular repair using an acute renal injury and repair model, ischemia/reperfusion (I/R). Mice injected with CSF-1 following I/R exhibited hastened healing, as evidenced by decreased tubular pathology, reduced fibrosis, and improved renal function. Notably, CSF-1 treatment increased TEC proliferation and reduced TEC apoptosis. Moreover, administration of a CSF-1 receptor–specific (CSF-1R–specific) antibody after I/R increased tubular pathology and fibrosis, suppressed TEC proliferation, and heightened TEC apoptosis. To determine the contribution of macrophages to CSF-1–dependent renal repair, we assessed the effect of CSF-1 on I/R in mice in which CD11b⁺ cells were genetically ablated and determined that macrophages only partially accounted for CSF-1–dependent tubular repair. We found that TECs expressed the CSF-1R and that this receptor was upregulated and coexpressed with CSF-1 in TECs following renal injury in mice and humans. Furthermore, signaling via the CSF-1R stimulated proliferation and reduced apoptosis in human and mouse TECs. Taken together, these data suggest that CSF-1 mediates renal repair by both a macrophage-dependent mechanism and direct autocrine/paracrine action on TECs.     

PALMITOYLETHANOLAMIDE REDUCES EARLY RENAL DYSFUNCTION AND INJURY CAUSED BY EXPERIMENTAL ISCHEMIA AND REPERFUSION IN MICE

ABSTRACT: This study was designed to assess a protective effect of palmitoylethanolamide (PEA) in the development of inflammation after ischemia-reperfusion injury of the kidney. Moreover, to suggest a possible mechanism, renal ischemia-reperfusion was performed in mice with targeted disruption of peroxisome proliferator-activated receptor α (PPAR-α) gene (PPAR-αKO) to explain whether the observed PEA effect was dependent on PPAR-α pathway. Peroxisome proliferator-activated receptor-αKO and littermate wild-type controls (PPAR-αWT) were subjected to bilateral renal artery occlusion (30 min) and reperfusion (6 h) and received PEA (10 mg/kg i.p.) 15 min before release of clamps. Serum and urinary indicators of renal dysfunction and tubular and reperfusion injury were measured, specifically serum urea, creatinine, aspartate aminotransferase and γ-glutamyl transferase, and creatinine clearance. In addition, renal sections were used for histological scoring of renal injury and for immunologic evidence of nitrotyrosine formation, poly[adenosine diphosphate-ribose] (PAR), and adhesion molecules expression. The oxidative stress-sensitive nuclear factor κB signaling pathway was also investigated by Western blot analysis. Kidney myeloperoxidase activity and malondialdehyde levels were measured for assessment of polymorphonuclear leukocyte cell infiltration and lipid peroxidation, respectively. Apoptotic mechanisms were also investigated. Moreover, the infiltration and activation of mast cells were explored. In vivo, PEA administration during ischemia significantly reduced the increase in (i) creatinine, γ-glutamyl transferase, aspartate aminotransferase; (ii) nuclear translocation of nuclear factor κB p65; (iii) kidney myeloperoxidase activity and malondialdehyde levels; (iv) nitrotyrosine, PAR, and adhesion molecules expression; (v) the infiltration and activation of mast cells; and (vi) apoptosis. Our results clearly demonstrate that PEA significantly attenuated the degree of renal dysfunction, injury, and inflammation caused by ischemia-reperfusion injury. Moreover, the positive effects of PEA were at least in part dependent on PPAR-α pathway.     

Bone marrow-derived cells mobilized by granulocyte-colony stimulating factor facilitate vascular regeneration in mouse kidney after ischemia/reperfusion injury

Bone marrow-derived cells (BMDC) play crucial roles in tissue regeneration. Granulocyte-colony stimulating factor (G-CSF) mobilizes BMDC and may facilitate the repair of kidney tissues after ischemia/reperfusion (I/R) injury. The tissue protective action of resveratrol, an antioxidant, might modify the regenerating potential of BMDC in I/R renal injury. This study examined whether G-CSF and/or resveratrol affect the recruitment of BMDC into vascular endothelial cells and renal tubular cells and the kidney function after I/R injury. I/R renal injury was induced in female mice that had been lethally irradiated and transplanted with male bone marrow cells. The mice were given saline, resveratrol or G-CSF, daily for 7 days. Non-irradiated and non-bone-marrow-transplanted female mice, which underwent the same kidney injury, were included as control. White blood cell (WBC) count and serum creatinine were monitored. Immunohistologic evaluation for renal tubular cells (cytokeratin) and endothelial cells (factor VIII-related antigen), and fluorescence in situ hybridization for mouse Y chromosome were performed. Although WBC was significantly higher in the G-CSF group, there was no significant difference in creatinine levels among all groups. Factor VIII-related antigen-positive cells with a Y-chromosome signal were identified in the capillary wall between renal tubuli and most frequently seen in the G-CSF group (p < 0.0001). Resveratrol did not affect kidney recovery in this model. No cytokeratin-positive renal tubular cells having a Y-chromosome signal were identified. In conclusion, BMDC are recruited into endothelial cell in I/R renal injury without apparent renal tubular cell regeneration, and G-CSF facilitates the endothelial cell regeneration.     

5-Aminoisoquinolinone, a novel inhibitor of poly(adenosine disphosphate-ribose) polymerase, reduces microvascular liver injury but not mortality rate after hepatic ischemia-reperfusion

OBJECTIVE: The aim of this study was to investigate the impact of the novel, potent, water-soluble inhibitor of poly(adenosine diphosphate-ribose) polymerase (PARP) 5-aminoisoquinolinone (5-AIQ) on hepatic microcirculation, hepatocellular injury, and survival in a murine model of hepatic ischemia-reperfusion. DESIGN: Randomized animal study. SETTING: Research laboratory. SUBJECTS: C57BL6 mice were subjected to warm either partial (90 mins) or total (75 mins) ischemia of the liver. INTERVENTIONS: Either PARP inhibitor 5-AIQ (3 mg/kg) or vehicle was administered to mice intravenously immediately before the start of reperfusion. Sham-operated animals served as controls. MEASUREMENTS AND MAIN RESULTS: As shown by intravital fluorescence microscopy after 30-60 mins of reperfusion, ischemia-reperfusion significantly enhanced platelet- and leukocyte-endothelial cell interactions in hepatic microvessels and impaired sinusoidal perfusion. Hepatocellular injury was characterized by an increase in the number of necrotic and apoptotic cells, dramatic elevation of aspartate aminotransferase/alanine aminotransferase serum activity, and lipid peroxidation in liver tissue. 5-AIQ treatment attenuated ischemia-reperfusion-induced increases in the numbers of adherent platelets and leukocytes as well as of necrotic and apoptotic cells and ameliorated perfusion failure. Furthermore, PARP inhibition prevented the increase in aspartate aminotransferase activity after ischemia-reperfusion but did not affect postischemic alanine aminotransferase release. However, no protective impact of 5-AIQ on postischemic oxidative stress was observed. Although PARP inhibition did not alter the survival percentage after ischemia-reperfusion (22% in both groups), this approach prolonged survival from 1 to 24 hrs (ischemia-reperfusion + vehicle) up to 48-72 hrs in the treated group. CONCLUSIONS: PARP inhibition with 5-AIQ during hepatic ischemia-reperfusion attenuates microvascular injury and reduces the extent of necrotic/apoptotic cell damage but does not protect from oxidative injury and does not improve postoperative survival rate.     

p21对缺血-再灌注损伤后肾小管上皮细胞演变的影响

目的 探讨p21对缺血-再灌注损伤（IRI）后肾小管上皮细胞演变的影响。方法 选择低龄（2个月龄）和高龄（12个月龄）p21（＋／＋）和p21（-／-）鼠，建立左肾IRI模型。于IRI后0、1、3、7d及1、3、6个月光镜下观察肾小管组织学变化，采用免疫组化法检测肾小管上皮细胞增殖细胞核抗原（PCNA）表达，组织化学染色观察肾小管上皮细胞衰老相关β-半乳糖苷酶（SA-β-gal）活力，末端脱氧核糖转移酶介导的生物素化脱氧尿嘧啶缺刻标记技术（TUNEL）检测肾小管上皮细胞凋亡。结果 IRI后0d，肾小管以坏死为主，高龄鼠比低龄鼠严重、p21（-／-）鼠比p21（＋／＋）鼠严重（P均〈0．05）。肾小管上皮细胞凋亡在IRI 1d后出现，7d达高峰，且高龄鼠比低龄鼠明显、p21（-／-）鼠比p21（＋／＋）鼠明显（P均d0．05）。低龄鼠IRI后1个月出现SA—β-gal染色阳性的肾小管上皮细胞，而对侧肾此时未见衰老细胞，3和6个月时衰老的肾小管上皮细胞显著增多，且p21（＋／＋）鼠比p21（-／-）鼠明显（P〈0．05）；p21（＋／＋）高龄鼠IRI后0d双肾即可见大量的SA-β-gal染色阳性肾小管上皮细胞，且较p21（-／-）鼠显著增多（P〈O．05），但1d后，p21（＋／＋）和p21（-／-）鼠IRI肾衰老细胞均明显减少（P均〈0．05），1个月后又呈进行性增加，且p21（＋／＋）鼠始终比p21（-／-）鼠严重。高龄和低龄p21（＋／＋）鼠PCNA阳性染色细胞出现的几率差异无显著性（P〉0．05），但低龄鼠细胞增殖能力要强于高龄鼠；而p21（-／-）鼠的细胞增殖能力明显强于p21（＋／＋）鼠，低龄鼠更为显著（P均〈0．05）。对高龄鼠IRI后1d细胞衰老和凋亡进行相关分析显示，二者呈显著负相关Cp21（＋／＋）鼠：r=-0．82，P〈0．001,p21（-／-）鼠：r=-0．76，P〈0．0013。结论 ①IRI可促进正常肾小管上皮细胞衰老的进程；②已经进入衰老状态的肾小管上皮细胞在遭受IRI刺激后，更易走向死亡[坏死和（或）凋亡]；③p21在IRI所致肾小管上皮细胞演变过程中发挥重要的调控作用。     

Intrarenal cells, not bone marrow-derived cells, are the major source for regeneration in postischemic kidney

Ischemic injury to the kidney produces acute tubular necrosis and apoptosis followed by tubular regeneration and recovery of renal function. Although mitotic cells are present in the tubules of postischemic kidneys, the origins of the proliferating cells are not known. Bone marrow cells (BMCs) can differentiate across lineages to repair injured organs, including the kidney. However, the relative contribution of intrarenal cells and extrarenal cells to kidney regeneration is not clear. We produced transgenic mice that expressed enhanced GFP (EGFP) specifically and permanently in mature renal tubular epithelial cells. Following ischemia/reperfusion injury (IRI), EGFP-positive cells showed incorporation of BrdU and expression of vimentin, which provides direct evidence that the cells composing regenerating tubules are derived from renal tubular epithelial cells. In BMC-transplanted mice, 89% of proliferating epithelial cells originated from host cells, and 11% originated from donor BMCs. Twenty-eight days after IRI, the kidneys contained 8% donor-derived cells, of which 8.4% were epithelial cells, 10.6% were glomerular cells, and 81% were interstitial cells. No renal functional improvement was observed in mice that were transplanted with exogenous BMCs. These results show that intrarenal cells are the main source of renal repair, and a single injection of BMCs does not make a significant contribution to renal functional or structural recovery.     

Guanosine supplementation reduces apoptosis and protects renal function in the setting of ischemic injury

Ischemic injury to the kidney is characterized in part by nucleotide depletion and tubular cell death in the form of necrosis or apoptosis. Recently, we linked anoxia-induced apoptosis in renal cell cultures specifically to the depletion of GTP. We therefore hypothesized that enhancing GTP repletion in vivo might protect function by reducing apoptosis in postischemic tubules. Male C57 black mice (the "I" group of animals) underwent bilateral renal artery clamp for 32 minutes to induce ischemia and then received either normal saline ("NS") or guanosine ("G"). After 1 hour of reperfusion, renal GTP levels in NS/I were reduced to nearly half of those in sham operated mice, whereas these levels were nearly unchanged in G/I mice. Morphologic examination of tubular injury revealed no significant differences between the two groups. However, there was a significant reduction in the number of apoptotic tubular cells in the medulla in the G/I group as compared with the NS/I group. At 24 hours, creatinine was significantly elevated in the NS/I group, compared to the G/I group. We conclude that guanosine protects against renal ischemic injury by replenishing GTP stores and preventing tubular apoptosis.     

CSF-1 signaling mediates recovery from acute kidney injury

Renal tubule epithelia represent the primary site of damage in acute kidney injury (AKI), a process initiated and propagated by the infiltration of macrophages. Here we investigated the role of resident renal macrophages and dendritic cells in recovery from AKI after ischemia/reperfusion (I/R) injury or a novel diphtheria toxin–induced (DT-induced) model of selective proximal tubule injury in mice. DT-induced AKI was characterized by marked renal proximal tubular cell apoptosis. In both models, macrophage/dendritic cell depletion during the recovery phase increased functional and histologic injury and delayed regeneration. After I/R-induced AKI, there was an early increase in renal macrophages derived from circulating inflammatory (M1) monocytes, followed by accumulation of renal macrophages/dendritic cells with a wound-healing (M2) phenotype. In contrast, DT-induced AKI only generated an increase in M2 cells. In both models, increases in M2 cells resulted largely from in situ proliferation in the kidney. Genetic or pharmacologic inhibition of macrophage colony-stimulating factor (CSF-1) signaling blocked macrophage/dendritic cell proliferation, decreased M2 polarization, and inhibited recovery. These findings demonstrated that CSF-1–mediated expansion and polarization of resident renal macrophages/dendritic cells is an important mechanism mediating renal tubule epithelial regeneration after AKI.     

Pivotal role of dendritic cell-derived CXCL10 in the retention of T helper cell 1 lymphocytes in secondary lymph nodes

Various immune diseases are considered to be regulated by the balance of T helper (Th)1 and Th2 subsets. Although Th lymphocytes are believed to be generated in draining lymph nodes (LNs), in vivo Th cell behaviors during Th1/Th2 polarization are largely unexplored. Using a murine granulomatous liver disease model induced by Propionibacterium acnes, we show that retention of Th1 cells in the LNs is controlled by a chemokine, CXCL10/interferon (IFN) inducible protein 10 produced by mature dendritic cells (DCs). Hepatic LN DCs preferentially produced CXCL10 to attract 5'-bromo-2'-deoxyuridine (BrdU)+CD4+ T cells and form clusters with IFN-gamma-producing CD4+ T cells by day 7 after antigen challenge. Blockade of CXCL10 dramatically altered the distribution of cluster-forming BrdU+CD4+ T cells. BrdU+CD4+ T cells in the hepatic LNs were selectively diminished while those in the circulation were significantly increased by treatment with anti-CXCL10 monoclonal antibody. This was accompanied by accelerated infiltration of memory T cells into the periphery of hepatic granuloma sites, most of them were in cell cycle and further produced higher amount of IFN-gamma leading to exacerbation of liver injury. Thus, mature DC-derived CXCL10 is pivotal to retain Th1 lymphocytes within T cell areas of draining LNs and optimize the Th1-mediated immune responses.     

Targeted expression of a dominant-negative EGF-R in the kidney reduces tubulo-interstitial lesions after renal injury

The role of EGF in the evolution of renal lesions after injury is still controversial. To determine whether the EGF expression is beneficial or detrimental, we generated transgenic mice expressing a COOH-terminal-truncated EGF-R under the control of the kidney-specific type 1 gamma-glutamyl transpeptidase promoter. As expected, the transgene was expressed exclusively at the basolateral membrane of proximal tubular cells. Under basal conditions, transgenic mice showed normal renal morphology and function. Infusion of EGF to transgenic animals revealed that the mutant receptor behaved in a dominant-negative manner and prevented EGF-signaled EGF-R autophosphorylation. We next evaluated the impact of transgene expression on the development of renal lesions in two models of renal injury. After 75% reduction of renal mass, tubular dilations were less severe in transgenic mice than in wild-type animals. After prolonged renal ischemia, tubular atrophy and interstitial fibrosis were reduced in transgenic mice as compared with wild-type mice. The beneficial effect of the transgene included a reduction of tubular cell proliferation, interstitial collagen accumulation, and mononuclear cell infiltration. In conclusion, functional inactivation of the EGF-R in renal proximal tubular cells reduced tubulo-interstitial lesions after renal injury. These data suggest that blocking the EGF pathway may be a therapeutic strategy to reduce the progression of chronic renal failure.     

The beneficial effect of 2′-deoxycoformycin in renal ischemia-reperfusion is mediated both by preservation of tissue ATP and inhibition of lipid peroxidation

Renal ischemia injures the renal tubular cell by disrupting the vital cellular metabolic machinery. Further cell damage is caused when the blood flow is restored by oxygen free radicals that are generated from xanthine oxidase. Oxygen radicals cause lipid peroxidation of cell and organelle membranes, disrupting the structural integrity and capacity for cell transport and energy metabolism. In the present study, the possible therapeutic usefulness of the adenosine deaminase inhibitor, 2'-deoxycoformycin (DCF), during renal ischemia and reperfusion injury was investigated. The effects of DCF on renal malondialdehyde (MDA) and ATP levels were studied after 45 min ischemia and 15 min subsequent reperfusion in rat kidneys. MDA levels remained unchanged during ischemia, but increased after the subsequent reperfusion. DCF pretreatment (2.0 mg/kg i.m.) decreased MDA and increased ATP levels during the ischemia-reperfusion period. DCF exerts a dual protective action by facilitating purine salvage for ATP synthesis and inhibiting oxygen radical-induced lipid peroxidation. These results suggest that DCF therapy could be beneficial in the treatment of ischemia-reperfusion renal injuries.     

骨髓间充质干细胞在肾缺血-再灌注损伤早期的抗凋亡作用

目的 观察骨髓间充质干细胞(mesenchymal stem cells,MSCs)自体移植对兔肾缺血-再灌注(ischemia reperfusion,I/R)损伤早期的治疗作用及其对肾小管上皮细胞凋亡的影响.方法 骨穿刺抽取新西兰大耳白兔股骨骨髓,分离、培养、扩增MSCs.30只新西兰大耳白兔随机分为移植组、对照组和假手术组,每组10只.移植组夹闭双肾动脉90 min,再灌注后经颈静脉移植BrdU标记的自体MSC8.对照组夹闭双肾动脉90 min,再灌注后经颈静脉注入等量生理盐水.假手术组假手术后经颈静脉移植Brdu标记的自体MSCs.肾I/R后48 h处死兔,比较兔肾功能和肾组织损伤,免疫组化法检测肾组织MSCs来源细胞,TUNEL法检测肾小管上皮细胞凋亡.用SPSS 13.0统计软件进行统计学分析,肾功能和肾小管细胞凋亡比较用ANOVA单因素方差分析;肾损伤指数比较用非参数的Kruskalwallis检验,以P<0.05为差异有统计学意义.结果 移植组较对照组肾功能明显改善(24 h,BUN:F=7.483,Scr:F=15.091;48 h,BUN:F=17.741,Scr:F=61.865;P<0.05),肾损伤明显减轻(F=12.658,P<0.01).移植组肾小管上皮细胞凋亡明显减少(F=135.495,P<0.01),且差异均具有统计学意义(P<0.05).I/R后48 h,移植组肾组织内可见少量BrdU阳性细胞.结论 MSCs自体移植对急性肾I/R损伤有治疗作用,其可能机制是通过减少肾小管上皮细胞凋亡来减轻肾I/R损伤早期的肾损害.     

淫羊藿苷对大鼠肾脏缺血再灌注后炎性损伤的保护

背景：肾移植过程中移植肾缺血再灌注损伤不可避免,采用药物减轻该损伤有助于提高肾移植近远期疗效。淫羊藿苷对心肌和脑缺血的治疗效果较好,对肾脏缺血再灌注的作用尚不清楚。目的：探索淫羊藿苷对肾脏的缺血再灌注损伤的保护机制。方法：54只SD大鼠随机等分为假手术组、淫羊藿苷组和模型组,后2组大鼠建立单侧肾脏缺血再灌注损伤模型,假手术组大鼠仅游离肾蒂而不钳夹阻断肾血管。淫羊藿苷组和模型组在造模前2d至造模后12d分别给予100mg/kg淫羊藿苷和1mL/kg0.3%羧甲基纤维素钠灌胃,1次/d。结果与结论：相比于对照组,肾脏缺血再灌注损伤后大鼠血肌酐明显升高,肌酐清除率下降,肾组织出现病理性损伤,而给予淫羊藿苷的大鼠,大鼠肾组织诱生型一氧化氮合酶mRNA和蛋白表达水平下降,肾组织内的促炎因子（肿瘤坏死因子α、白细胞介素1β,6）、趋化因子（干扰素诱导蛋白10、单核细胞趋化蛋白1、巨噬细胞炎性蛋白2）mRNA的表达水平降低,肾脏缺血再灌注损伤后6h,大鼠血浆亚硝酸盐/硝酸盐和肾组织内髓过氧化物酶水平最高,而后逐渐下降;且淫羊藿苷组大鼠血浆亚硝酸盐/硝酸盐和肾组织内髓过氧化物酶水平低于模型组（P〈0.05）。提示淫羊藿苷可通过抑制诱生型一氧化氮合酶酶表达及其下游的炎症级联反应而减轻大鼠肾脏缺血再灌注损伤。     

ARNT基因失活小鼠的肾脏缺血再灌注损伤

背景：如何有效防治肾脏的缺血再灌注损伤,一直是肾移植领域的研究重点。但目前其机制仍然不是很清楚。目的：探讨缺氧诱导因子系统对小鼠肾缺血再灌注损伤的影响及可能的作用机制。方法：选取两种小鼠,一种为芳香族碳氢化合物核转移子（aryl hydrocarbon receptor nuclear translocator,ARNT）基因敲除小鼠,一种为同窝对照组小鼠。每种小鼠分别进行假手术、缺血再灌注、缺血再灌注时注射重组人促红细胞生成素、缺血再灌注时注射等量生理盐水。建立小鼠肾脏缺血再灌注损伤模型,分别比较再灌注损伤后1h血清促红细胞生成素含量、24h血清肌酐值、肾组织PAS染色肾小管损伤评分和TUNEL法计算肾小管细胞凋亡数。结果与结论：再灌注后1h血清促红细胞生成素水平ARNT敲除组明显低于对照组（P〈0.01）。24h血清肌酐水平ARNT敲除组明显高于对照组（P〈0.01）。ARNT敲除组明显比对照组损伤程度重,肾小管评分明显高于对照组（P〈0.01）。ARNT敲除组阳性凋亡细胞数明显多于ARNT＋/＋组（P〈0.01）。补充促红细胞生成素后,ARNT敲除组与对照组比较,差异无显著性意义（P〉0.05）。结果表明,缺氧诱导因子系统对肾脏缺血再灌注损伤有重要的保护作用。可能是促红细胞生成素来介导其最大的保护效应。