Lymphatic microvessels in the rat remnant kidney model of renal fibrosis: aminopeptidase p and podoplanin are discriminatory markers for endothelial cells of blood and lymphatic vessels

ABSTRACT. Rat remnant kidney is an established model of renal tubulointerstitial fibrosis and progression to end-stage renal failure. The morphologic lesions comprise nephron loss and regeneratory tubular hypertrophy, interstitial infiltration, predominately by macrophages, and progressive fibrosis. A critical role in this complex pathology was assigned to tubulointerstitial blood microvessels that regulate the supply of oxygen and nutrients of tubuli. Whereas some investigations reported a rarefaction of the vascular network in association with the degenerative cortical changes, others observed an increase in vascularization. Here these discrepant findings are addressed by reinvestigation of the vascularization of rat remnant kidneys by the use of two novel endothelial lineage specific, discriminatory markers, i.e., the membrane mucoprotein podoplanin with specificity for lymphatic endothelia, and the glycosyl-phosphatidylinositol (GPI)-anchored membrane enzyme aminopeptidase P that is recognized by a monoclonal antibody designated JG12 and that is specifically expressed by endothelial cells of blood vessels only. The results obtained confirm a regional rarefaction of aminopeptidase P-positive blood microvessels; they also establish major changes in the renal lymphatic vasculature. Massive proliferation of lymphatic vessels was observed in fibrotic tubulointerstitial regions, whereas in kidneys of sham-operated rats, only a few lymphatic vessels were found adjoined with arteries. The lymphatic vessels frequently contained mononuclear cells that were also encountered in the interstitial spaces and expressed relative large amounts of vascular endothelial growth factor-C mRNA by in situ hybridization. Collectively, these results indicate that a large proportion of the microvessels encountered in the cortex of remnant kidneys are of lymphatic origin and cannot be discriminated by common endothelial markers, such as CD34, that are expressed by both lymphatic and blood endothelia cells. As lymphatic endothelial cells secrete chemokines that attract dendritic cells, it is possible that the increase in lymphatic vascularization could enhance the immunologic surveillance of remnant kidneys.     

Chronic renal allograft rejection. Selective involvement of the glomerular endothelium in humoral immune reactivity and intravascular coagulation

To study immune reactive and thrombotic mechanisms involved in chronic renal allograft rejection, Lewis rat kidneys were transplanted into bilaterally nephrectomized Brown Norway recipients tolerant of LEW erythrocyte antigens. Such BN rats fail to produce anti class I MHC alloantibodies after insertion of a LEW kidney. The LEW renal allografts experience a transient rejection episode without proteinuria followed by the development of chronic rejection, clinically characterized by glomerular proteinuria in the presence of stable renal function. Immunohistological studies of such chronically rejected LEW renal allografts showed the occurrence of glomerular and interstitial infiltration of predominantly monocytes and T cells. CD4-positive T cells dominated over CD8-positive T cells in the chronically rejected LEW renal grafts. IgG deposition was found deposited throughout the renal vasculature--this in contrast to IgM, which was observed only in the glomerular vasculature. Glomerular antibodies were not directed to endothelial class II MHC antigens, and showed only weak complement fixation as demonstrated by C3 staining. Selective glomerular IgM deposition was associated with vascular (platelet-containing) thrombi, and focal and segmental fibrinoid necrosis. In contrast, acutely rejected LEW renal grafts in unmodified BN recipients showed IgM deposition as well as thrombus formation throughout the entire renal vasculature. The results demonstrate that the antibody response to endothelial--and, in particular, glomerular endothelial non-MHC antigens--may bring about chronic vascular renal allograft rejection. How the formation of glomerular thrombotic lesions may be assisted by endothelial reactivity to cytokines from local immune reactive cells is discussed.     

大鼠慢性移植肾肾病动物模型的制作经验总结

目的 总结制作稳定的大鼠慢性移植肾肾病(CAN)动物模型的经验.方法 以F344近交系大鼠为供者,取供者左肾作为供肾,原位低温灌注;以Lewis近交系大鼠为受者,行左侧原位肾移植,供肾动脉与受者腹主动脉端侧吻合,供肾静脉与受者肾静脉端端吻合,输尿管带膀胱瓣与受者膀胱吻合.术后用环孢素A灌胃10 d,剂量为10 mg·kg-1·d-1.每月采集受者血液和尿液,测定血肌酐及24 h尿蛋白,分别于术后2、4个月获取移植肾进行病理检查.结果 45只进行移植,手术成功率为85%,单次手术时间为(120±20)min.移植后1个月,大鼠即出现血肌酐、尿素氮及血胱抑素升高,24 h尿蛋白增加,与术前相比,各项指标均升高(P<0.05);术后2个月及4个月,除尿蛋白继续增加外,其余观察指标上升不明显.移植术后2个月,移植肾有轻度至中度的间质纤维化,淋巴细胞和浆细胞的浸润;4个月时,移植肾可见广泛的间质纤维增生,间质细胞大量浸润,肾小球基底膜增厚、硬化、闭塞,肾小管萎缩退化,符合CAN的病理改变.结论 通过充分的手术强化训练及改进,规范大鼠取、肾、移植术中、术后管理的每个细节,大鼠CAN模型的成功率及稳定性高.

Abstract：

Objective To summarize the experience of establishing the stable rat model of chronic allograft nephropathy. Methods We used Fisher rats as donors and Lewis rats as recipients.After the left kidney of the donor perfused in situ under hypothermic condition, the left renal vein,abdominal aorta and bladder flap of the donor was anastomosed with the left renal vein, renal artery and bladder of the recipient, respectively. The recipients were given cyclosporin oral solution 10 mg/kg every day by gavage for 10 days after transplantation. The blood and urine samples were collected 1 month, 2 months and 4 months after transplantation and renal function and total urine protein were examined. The pathological changes of the renal allograft were observed 2 and 4 months after transplantation. Results Forty-five rats received operation and achievement ratio was 85%. The renal transplantations were finished in 120 ± 20 min. The Scr, BUN, Cycs and total urine protein demonstrated a significant increase one month after transplantation. On the second and fourth month,with the exception of urine protein continued to increase, the other indicators did not change significantly. Two months after transplantation renal pathology demonstrated light to moderate interstitial fibrosis, infiltration of lymphocytes and plasma cells. At 4th month the renal allografts showed extensive interstitial fibrosis, a large number of infiltrating interstitial cells, thickening,hardening, occlusion of glomerular basement membrane, and renal tubular atrophy that were consistent with pathological changes of chronic allograft nephropathy. Conclusion Through adequate surgical training and improvement, and specification for rat nephrectomy, transplantation surgery,and postoperative management in every detail, the model with high success rate and stability can be achieved.     

磷酸化糖原合成酶激酶-3β在大鼠移植肾早期病理改变中的作用

目的 探讨糖原合成酶激酶-3β(GSK-3β)在大鼠移植肾早期病理改变中的作用.方法 以F344大鼠为供者,Lewis大鼠为受者,依照标准的慢性移植肾肾病(CAN)模型要求行左肾原位移植,制作CAN模型(移植组).术后7d切除受者的右肾.以切除一侧肾脏的雄性F344大鼠和Lewis 大鼠为对照(F344对照组和LEW对照组).分别于术后4、8、12、16及24周时收集24 h尿液,采集血液,测定24 h尿蛋白和血肌酐,取移植肾组织,观察组织学改变,并用免疫组化法检测肾组织中磷酸化GSK-3β表达.结果 移植组术后早期(4、8和12周)移植肾病理改变主要表现为单个核细胞浸润、血管平滑肌细胞(SMC)的移行增殖,在后期(16和24周)尿蛋白排泄率显著增高,移植肾病理改变表现为肾间质单个核细胞浸润明显增加及严重的肾间质纤维化、肾小管萎缩.移植组术后各时间点移植肾组织中磷酸化GSK-3β及其mRNA表达水平均显著低于LEW对照组和F344对照组相同时点的表达水平(P＜0.05),并随着移植时间的延长进一步降低.磷酸化GSK-3β表达水平与早期肾间质单个核细胞浸润程度、SMC移行增殖及后期肾间质纤维化、肾小管萎缩、血管硬化程度呈显著负相关.结论 磷酸化GSK-3β表达下调在大鼠移植肾早期的肾间质单个核细胞浸润、SMC移行增殖及后期的肾间质纤维化、肾小管萎缩、肾血管硬化病变的发生中均起重要作用.     

HGF gene therapy attenuates renal allograft scarring by preventing the profibrotic inflammatory-induced mechanisms

Inflammatory processes and tissue scarring are characteristic features of chronic allograft nephropathy. Hepatocyte growth factor (HGF) has beneficial effects on renal fibrosis and it also ameliorates renal interstitial inflammation as it has been recently described. Contrarily to protein administration, intramuscular gene electrotransfer allows sustained release of HGF. So, here we hypothesized that gene therapy with human HGF would diminish the characteristic scarring of chronic allograft nephropathy either by antagonizing tissue fibrosis mechanisms or by reducing inflammation. Lewis rats transplanted with cold preserved Fischer kidneys received vehicle (NoHGF) or intramuscular plasmid DNA encoding HGF plus electroporation either before transplantation (IniHGF, early post-transplant cytoprotection of tubular cells) or 8/10 weeks after transplantation (DelHGF, delayed prevention of chronic mechanisms). Serum creatinine and proteinuria were measured every 4 weeks for 24 weeks. Grafts at 12 or 24 weeks were evaluated for glomerulosclerosis, fibrosis inflammatory cells and mediators, cell regeneration and tubulo-interstitial damage. Nontreated animals developed renal insufficiency, progressive proteinuria and fibrosis among other characteristic histological features of chronic allograft nephropathy. Treatment with human HGF, especially when delayed until the onset of fibrogenic mechanisms, reduced renal failure and mortality, diminished tubule-interstitial damage, induced cell regeneration, decreased inflammation, NF-kappaB activation, and profibrotic markers at 12 weeks and prevented late interstitial fibrosis and glomerulosclerosis. The effectiveness of HGF-gene therapy in the prevention of renal allograft scarring is related with the halt of profibrotic inflammatory-induced mechanisms.     

整合素连接激酶在大鼠慢性移植肾肾病中的作用与机制

目的探讨整合素连接激酶(ILK)在慢性移植肾肾病(CAN)中的作用与机制。方法实验组肾移植受者为雄性Lewis大鼠40只,供者为雄性F344大鼠40只,依照标准的慢性移植肾肾病大鼠模型要求行左肾原位移植。对照组分别为行单纯右肾切除的Lewis大鼠及F344大鼠各25只。于术后4、8、12、16及24周时分批处死大鼠,同时做肾功能与组织学检测,免疫组织化学与蛋白印迹法测定肾组织中ILK的表达,逆转录聚合酶链(RT-PCR)法检测ILK mRNA的表达,免疫组织化学方法检测基质金属蛋白酶9(MMP-9)的表达。结果CAN大鼠移植4周时肾间质可见单个核细胞浸润,12周时可见血管平滑肌细胞的移行与增殖,24周时可见轻度肾间质纤维化、血管硬化及管腔狭窄。CAN大鼠肾组织中ILK及ILK mRNA表达水平显著增高,且随着移植时间的延长有逐渐增高趋势。CAN大鼠肾移植术后8周前肾小管间质及肾小动脉MMP-9表达水平均显著高于同时段LEW对照组及F344对照组,16周后显著降低。Spearman等级相关分析结果显示:CAN大鼠肾组织中ILK表达水平与24 h尿蛋白定量、血清肌酐水平、肾间质单个核细胞浸润程度、肾小动脉平滑肌细胞数量、肾间质纤维化程度等呈显著正相关,与8周前MMP-9表达水平呈正相关,12周后无显著相关性。结论ILK在慢性移植肾肾病病理变化中发挥重要作用,移植早期肾小管间质及肾小动脉中MMP-9表达上调与ILK的作用机制有关。     

Recipient hypertension potentiates chronic functional and structural injury of rat renal allografts

BACKGROUND: Systemic hypertension affects many allograft recipients, is an important risk factor for chronic graft dysfunction, and is linked to reduced graft survival. The condition may up-regulate the expression of inflammatory host cells and their products. These, in turn, may significantly injure vascular endothelium and other components of allografted kidneys. METHODS: Lewis rats received orthotopic F344 renal allografts, a standard model of chronic rejection. Renovascular hypertension was produced by placing a silver clip (0.25 mm) on the renal artery of the retained contralateral native kidney 4 weeks after transplantation. Sham-clipped rats served as normotensive controls. Four recipient groups (Gp) were studied: Gp 1, rats with an allograft plus a clipped native kidney; Gp 2, those with an allograft and a sham-clipped native kidney; Gp 3, isografted animals with a clipped native kidney; and Gp 4, those bearing an isograft and a sham-clipped native kidney. Systolic blood pressure and proteinuria were measured every 2 weeks for 24 weeks. Grafts were assessed serially for morphologic and immunohistologic changes. RESULTS: Systemic blood pressure rose to hypertensive levels in Gps 1 and 3 within a week of clipping but never increased in Gps 2 and 4. Proteinuria developed in hypertensive animals but remained at baseline in normotensive controls. Intimal thickening of allograft arteries progressed to luminal obliteration with extensive perivascular and interstitial fibrosis by 24 weeks. In contrast, vascular changes in isografts of hypertensive hosts were restricted to medial hypertrophy. Tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, platelet derived growth factor (PDGF), endothelin, Il-6, major histocompatibility complex (MHC) class II, and B7 were up-regulated in allografts in hypertensive hosts. Vascular deposition of immunoglobulin (IgG) was increased. These changes were markedly less pronounced in Gp 3 isografts and minimal in the kidneys of the normotensive animals of Gps 2 and 4. CONCLUSIONS: An experimental model is presented that examines the influence of recipient hypertension in the pathogenesis of chronic dysfunction and injury developing in rat renal allografts over time.     

Nephrotic range proteinuria with "minimal change glomerulopathy" in human renal allografts: report of four cases

Four patients who received renal allografts developed nephrotic range proteinuria 2 to 16 months after renal transplantation. Twenty-four-hour urine protein excretion at the time of renal allograft biopsy ranged from 5.9 to 17.0 g/24 hours. The serum creatinine at the time of renal allograft biopsy ranged from 2.0 to 3.9 mg/dl (180 to 350 mumol/L). Biopsies of the allografts demonstrated minimal glomerular abnormalities by light microscopy, immunomicroscopy, and electron microscopy. Two biopsies exhibited severe interstitial fibrosis. These four cases illustrate the unusual finding of "minimal change glomerulopathy" in renal allograft recipients exhibiting nephrotic range proteinuria. All four patients progressed to dialysis 4, 36, 46, and 53 months after transplantation. Transplant nephrectomy was performed in three patients. One showed acute cortical necrosis. Two showed glomerular, vascular, and tubular-interstitial features of chronic rejection.     

Histopathology of chronic renal allograft dysfunction

The rate of late allograft loss remains relatively constant, despite greatly improved success in the early management of renal transplants. The pathological changes encountered in kidneys undergoing late allograft dysfunction are the result of a variety of processes, both immune and nonimmune. The gradual appearance of interstitial fibrosis and tubular atrophy is a nonspecific finding, which characterizes late allograft dysfunction. Features that indicate chronic rejection include transplant glomerulopathy, vascular intimal hyperplasia, particularly in association with intimal lymphocytic infiltration. Both of these changes may be related to humoral rejection. Animal models provide important insights into the mechanism of chronic rejection. In a commonly used model, the Fisher to Lewis rat model, antidonor antibodies against matrix proteins are associated with the development of transplant glomerulopathy, and the appearance of antitubular antibodies and a granulomatous interstitial nephritis may indicate graft-host differences in tubular basement membrane structure.     

Erythropoietin, but not the correction of anemia alone, protects from chronic kidney allograft injury

Anemia can contribute to chronic allograft injury by limiting oxygen delivery to tissues, particularly in the tubulointerstitium. To determine mechanisms by which erythropoietin (EPO) prevents chronic allograft injury we utilized a rat model of full MHC-mismatched kidney transplantation (Wistar Furth donor and Lewis recipients) with removal of the native kidneys. EPO treatment entirely corrected post-transplant anemia. Control rats developed progressive proteinuria and graft dysfunction, tubulointerstitial damage, inflammatory cell infiltration, and glomerulosclerosis, all prevented by EPO. Normalization of post-transplant hemoglobin levels by blood transfusions, however, had no impact on chronic allograft injury, indicating that EPO-mediated graft protection went beyond the correction of anemia. Compared to syngeneic grafts, control allografts had loss of peritubular capillaries, higher tubular apoptosis, tubular and glomerular oxidative injury, and reduced expression of podocyte nephrin; all prevented by EPO treatment. The effects of EPO were associated with preservation of intragraft expression of angiogenic factors, upregulation of the anti-apoptotic factor p-Akt in tubuli, and increased expression of Bcl-2. Inhibition of p-Akt by Wortmannin partially antagonized the effect of EPO on allograft injury and tubular apoptosis, and prevented EPO-induced Bcl-2 upregulation. Thus non-erythropoietic derivatives of EPO may be useful to prevent chronic renal allograft injury.     

Protective effects of atorvastatin on chronic allograft nephropathy in rats

OBJECTIVE: Chronic allograft nephropathy (CAN) is the leading cause of late kidney allograft loss. Recent studies have suggested that atorvastatin (ATO) may interact with the acute inflammatory process in the renal interstitium and suppress the proliferation of mesangial cells. We hypothesized that ATO could also inhibit the chronic inflammatory process and prevent the progression of CAN. MATERIALS AND METHODS: Fisher (F344) kidneys were orthotopically transplanted into Lewis rat recipients. Lewis-to-Lewis rat kidney transplantation was served as the syngeneic control (Syn group). Allograft recipients were randomized and treated with cyclosporine A alone (Allo group) or in combination with ATO (15 or 30 mg/kg/d intrgastric, respectively, the low dose treatment group/high dose treatment group [LT/HT] groups). Renal function and the urine protein excretion were analyzed. Animals were sacrificed 20 weeks posttransplantation for histological and immunohistochemical studies, as well as analysis of mRNA levels of cytokines and chemokines. RESULTS: Renal function progressively deteriorated and substantial proteinuria developed in the Allo group compared with the Syn group. ATO-treated rats had significantly higher creatinine clearance rate and less amount of proteinuria. Histological examination revealed obvious features of CAN in the Allo group, whereas LT/HT groups demonstrated minimal glomerulosclerosis, interstitial fibrosis, intimal thickening, and tubular atrophy. The numbers of infiltrating mononuclear cells (ED1+, CD8+, and CD68+) decreased markedly, and the intragraft expression of transforming growth factor beta1 (TGF-beta1) and collagen III were also significantly attenuated in the LT/HT groups, as compared with the Allo group. The mRNA levels of proinflammatory cytokines (interleukin-2, interferon-gamma, interleukin-10), chemokines (RANTES, MCP-1), and profibrotic genes (TGF-beta1, collagen III) were significantly down-regulated in ATO-treated rats. CONCLUSION: Atorvastatin showed excellent favorable effects on blocking renal inflammation and fibrosis, and thus, efficiently inhibited the development and progression of CAN, which might improve the long-term survival rate of renal allografts.     

Impact of renal transplantation on small vessel reactivity

BACKGROUND: The function of large arteries is altered after renal transplantation. Whether transplantation also induces agonist-dependent functional changes in small arterial renal and extrarenal vessels has not yet been studied. METHODS: Chronic rejection was induced by grafting Lewis rats with kidneys from Fischer rats (FL). Rats that underwent transplantation were bilaterally nephrectomized. Rats that underwent syngeneic transplantation, uninephrectomized rats, uninephrectomized rats with denervated kidneys or with kidneys made ischemic, and native rats served as controls. All animals were treated with cyclosporine for 10 days. Eighteen weeks after surgery, the reactivity of small arteries (220-270 microm) was tested by myography. RESULTS: Weight gain, glomerular filtration rate, and arterial pressure were similar in all groups, whereas proteinuria was elevated in FL. Only kidneys from FL showed glomerular lesions, tubular atrophy, and vasculopathy. Responsiveness of coronary, mesenteric, and femoral resistance vessels to both constrictor and dilator agonists was similar in transplanted and nontransplanted animals. Resistance vessels obtained from both allogeneically and syngeneically transplanted kidneys were more sensitive to norepinephrine, phenylephrine, angiotensin II, and vasopressin than renal vessels from weight-matched controls. Vasodilation in response to acetylcholine and sodium nitroprusside was mitigated in transplanted versus nontransplanted kidneys. CONCLUSIONS: In rat renal transplantation, renal resistance vessel responsiveness to constrictor or dilator stimuli is altered. Extrarenal small vessel function is not affected. The changes in function of renal resistance vessels are not explained by reduction of nephron mass, denervation, ischemia, or chronic rejection.     

Renoprotective effects of the AGE-inhibitor pyridoxamine in experimental chronic allograft nephropathy in rats.

BACKGROUND: Advanced glycation end products (AGEs) are involved in diabetic nephropathy (DN). The AGE formation inhibitor pyridoxamine (PM) is renoprotective in DN and in normoglycaemic obese Zucker rats. In chronic allograft nephropathy (CAN), renal AGE accumulation occurs as well. METHODS: To investigate whether inhibition of AGE formation is renoprotective in CAN, we studied the Fisher 344 to Lewis (F-L) allograft rat model of experimental CAN. Fisher to Fisher (F-F) isografts served as controls. Proteinuria, renal function and renal histology of untreated transplanted rats (F-L n = 8, F-F n = 8) were compared to rats receiving PM 2 g/l in drinking water for 20 weeks starting at transplantation (F-L n = 5, F-F n = 10). All rats received cyclosporin A (1.5 mg/kg/day) for 10 days after transplantation to prevent early acute rejection. RESULTS: Compared to untreated allografts, PM significantly decreased proteinuria (76 +/- 18 vs 29 +/- 3 mg/day), serum creatinine (130 +/- 12 vs 98 +/- 5 micromol/l), focal glomerulosclerosis (116 +/- 27 vs 16 +/- 5 AU), glomerular macrophage influx (5.6 +/- 0.6 vs 3.3 +/- 1.0), interstitial fibrosis (132 +/- 24 vs 76 +/- 2 AU) and interstitial macrophage influx (47.0 +/- 8.7 vs 15.4 +/- 5.0. Moreover, PM significantly ameliorated tubular accumulation of pentosidine, compared to untreated allografts (2.5 +/- 0.6 vs 0.3 +/- 0.3, all p < 0.05). In the isograft controls, these values did not differ between untreated and PM treated rats. CONCLUSION: PM exerts renoprotective effects and decreases renal pentosidine accumulation in experimental CAN, suggesting a detrimental role for renal AGE accumulation in the pathogenesis of renal damage in this non-diabetic model. These results indicate that inhibition of AGE formation might be a useful adjunct therapy to attenuate CAN.     

Early application of Met-RANTES ameliorates chronic allograft nephropathy

BACKGROUND: Initial insults to kidney allografts, characterized by infiltration of mononuclear inflammatory cells, contribute to chronic allograft nephropathy. Chemokines such as RANTES (regulated upon activation, normal T cell expressed) are thought to be responsible for the recruitment and activation of infiltrating cells. The present study investigated whether early application of Met-RANTES, a chemokine receptor antagonist that blocks the effects of RANTES, can protect renal allografts from long-term deterioration. METHODS: Fisher (F344) rat kidneys were orthotopically transplanted into Lewis recipients and treated with cyclosporine A (1.5 mg/kg/day) for the first 10 days following transplantation, together with either Met-RANTES at 40 microg/day, 200 microg/day or vehicle for the first 7 days. Animals were harvested at 2 and 28 weeks after transplantation for histologic, immunohistologic and molecular analysis. RESULTS: Met-RANTES treatment reduced the infiltration of lymphocytes and macrophages in allografts at 2 weeks after transplantation, accompanied by decreased mRNA expression of interleukin (IL)-2, IL-1beta, tumor necrosis factor-alpha (TNF-alpha) and RANTES. At post-transplantation week 28, Met-RANTES treatment at high and low doses reduced urinary protein excretion and significantly ameliorated glomerulosclerosis, interstitial fibrosis, tubular atrophy, intimal proliferation of graft arteries and mononuclear cell infiltration. However, creatinine clearance was not influenced by Met-RANTES. Furthermore, Met-RANTES suppressed the mRNA expression of transforming growth factor-beta (TGF-beta) and platelet-derived growth factor-B (PDGF-B). CONCLUSIONS: Blockade of chemokine receptors by Met-RANTES diminishes early infiltration and activation of mononuclear cells in the grafts, and thus reduces the pace of chronic allograft nephropathy.     

Beyond operational tolerance: effect of ischemic injury on development of chronic damage in renal grafts

BACKGROUND: The induction of operational tolerance is the holy grail of clinical transplantation. However, in animal models with operational tolerance, long- term grafts still develop chronic damage. The elucidation of the impact of allogenic versus nonallogeneic factors in such a model is important. This study examined the effect of a clinically relevant combination of warm ischemia and cold preservation in the absence of allogeneic response (isografts) and in the context of operational tolerance. METHODS: Dark Agouti (DA) rat kidneys were transplanted into DA recipients (isografts) or Albino Surgery recipients (allografts) tolerized by two transfusions of DA blood, under cover of cyclosporin A. Grafts were subjected to minimal cold preservation or to 30 mins warm ischemia followed by 24 hrs cold preservation. RESULTS: After an initial peak of renal dysfunction, serum creatinine concentration returned to normal in isografts and nonischemic allografts, but remained significantly elevated in ischemic allografts (P<0.0002) throughout 6 months follow-up. Both allograft groups developed proteinuria. At 6 months, ischemic isografts and nonischemic allografts demonstrated very mild tubular atrophy and interstitial fibrosis. Tubulointerstitial injury was significantly more severe in ischemic allografts (P<0.01 vs. nonischemic allografts) and was associated with increased infiltrating monocyte/macrophages and NK cells (P<0.05). Moderate glomerulosclerosis was a feature of both allograft groups (P<0.05). CONCLUSIONS: The modified allogeneic response in operationally tolerant recipients acts in synergy with ischemia/reperfusion injury in the development of chronic damage. Strategies to limit or modify the initial ischemia/reperfusion injury may ameliorate chronic tubulointerstitial damage. Progressive glomerular damage and proteinuria in allografts may require other pharmacological intervention.     

Tubular epithelial syndecan-1 maintains renal function in murine ischemia/reperfusion and human transplantation

Syndecan-1, a heparan sulfate proteoglycan, has an important role in wound healing by binding several growth factors and cytokines. As these processes are also crucial in damage and repair after renal transplantation, we examined syndecan-1 expression in human control kidney tissue, renal allograft protocol biopsies, renal allograft biopsies taken at indication, and non-transplant interstitial fibrosis. Syndecan-1 expression was increased in tubular epithelial cells in renal allograft biopsies compared with control. Increased epithelial syndecan-1 in allografts correlated with low proteinuria and serum creatinine, less interstitial inflammation, less tubular atrophy, and prolonged allograft survival. Knockdown of syndecan-1 in human tubular epithelial cells in vitro reduced cell proliferation. Selective binding of growth factors suggests that syndecan-1 may promote epithelial restoration. Bilateral renal ischemia/reperfusion in syndecan-1-deficient mice resulted in increased initial renal failure and tubular injury compared with wild-type mice. Macrophage and myofibroblast numbers, tubular damage, and plasma urea levels were increased, and tubular proliferation reduced in the kidneys of syndecan-1 deficient compared with wild-type mice 14 days following injury. Hence syndecan-1 promotes tubular survival and repair in murine ischemia/reperfusion injury and correlates with functional improvement in human renal allograft transplantation.     

Chemokine-binding viral protein M-T7 prevents chronic rejection in rat renal allografts

M-T7 is a myxoma virus-encoded protein that has been found to bind and disrupt human chemokine gradients. This study examined whether purified M-T7 could prevent chronic rejection in a rat renal allograft model. Fisher F344 renal allografts were transplanted into Lewis rats. Recipients were randomly grouped into two groups: control animals treated with cyclosporine alone and animals treated with cyclosporine combined with low-, medium- and high-dose M-T7 viral protein. The survival rate was not significantly different between allograft groups. Renal allografts treated with high-dose M-T7 demonstrated a significant reduction in tubular atrophy, glomerular atrophy, vascular hyalinization, cortical scarring, and lymphocyte infiltration. Morphometric analyses demonstrated that the high-dose M-T7 group also showed a significantly decreased amount of glomerulosclerosis and transplant arteriosclerosis. These data demonstrate for the first time that the immunoregulatory viral protein M-T7 can effectively attenuate chronic rejection in rat renal allografts.     

雌激素预防大鼠同种肾移植慢性排斥反应的实验研究

目的 探讨雌激素对移植肾慢性排斥反应的影响。方法 以Fisher大鼠作供者,雌性Lewis大鼠作受者进行同种肾移植,为排除排卵周期及相应的内源性性激素变化的影响,肾移植均在非排卵期进行,后治疗组大鼠隔日给予25μg/kg雌二醇皮下注射。移植后16周作肾功能、移植肾组织学及免疫组化检测,测定肾组织中转化生长因子及β－机动蛋白mRNA的表达。结果 与对照组比较,移植后治疗组24d尿蛋白持续保持较低的水平（P＜0.01）,血清肌酐水平降低（P＜0.01）,肌酐清除率升高（P＜0.01）,移植肾组织管内膜增厚、肾小球硬化和间质纤维化程度减轻（P均＜0.01）,淋巴细胞和单核／巨噬细胞浸润减少（P＜0.01）,细胞间粘附分子（ICAM－1）、转化生长因子（TGF－β1）的mRNA表达减少（P均＜0.01）。结论 雌激素对移植肾功能有保护作用,其机理与影响上述细胞因子在移植肾的表达有关,提示雌激素可能为一类潜在的抗慢性排斥反应药物。