Effects of cytomegalovirus infection and prolonged cold ischemia on chronic rejection of rat renal allografts

Previous studies have demonstrated that both cytomegalovirus (CMV) infection and prolonged cold ischemia of the allograft (CI) are associated with chronic rejection of renal transplants. The purpose of this study is to investigate the effect of CMV infection, of CI and of the combination of both, on the progression of chronic rejection, and to obtain a more detailed insight in their effects on the expression of adhesion molecules. Therefore, a rat transplantation model was used. Lewis recipients of renal allografts (with and without CI) from MHC-incompatible Brown Norway rats were inoculated with rat CMV or left uninfected. CMV infection alone resulted in an increased influx of CD4+ cells and macrophages early after infection, and in an increase in glomerular sclerosis and intima proliferation. CI caused an increase in infiltrating NK cells and an effect on intimal proliferation, glomerular sclerosis, and tubular atrophy. When CMV infection and CI were combined, an additive effect could be measured. This was however not the case for the function of the kidney. The creatinin showed a synergistic effect of the two influencing factors. Due to the CMV infection, an increase in CD49 d cells was detected. CI resulted in an increase in CD18 cells and an increase in the expression of CD62P on vessels, and CD54 and CD44 on tubules. When CMV infection and CI were combined, all the effects caused by CMV and CI alone were present in an additional way.¶The results of the present study suggest that special attention should be paid to the recipient of an ischemically injured graft when either the donor or the recipient is CMV-infected. The patterns seen in histology, the infiltration of leukocytes and the expression of adhesion molecules, suggest that CI and CMV infection both have an effect on rejection, but act by different mechanisms.     

Chronic rejection in lung allografts: immunohistological analysis of fibrogenesis

Abstract  In ongoing chronic rejection after lung transplantation, alveolar interstitial fibrosis develops. However, little is known about the mechanisms involved. In order to investigate these mechanisms, expression of extracellular matrix molecules (ECM) (undulin, decorin, tenascin, laminin, and fibronectin) and cytokines [transforming growth factor(TGF)-β1, TGF-β3, platelet-derived growth factor(PDGF), and PDGF receptor] were semiquantita-tively evaluated in chronically rejected lung allografts, using standard immunohistochemical techniques. Additionally, the presence of mac-rophages was analysed. The present study demonstrates an increased infiltration of macrophages with a concomitant upregulation of cytokines (TGF-β1, TGF-β3, and PDGF) and an increased deposition of ECM in chronic lung rejection. These cytokines have an important role in the stimulation of fibroblasts which are a major source of ECM. Upregulated expression of ECM in the alveolar interstitial space leads to alveolar malfunction by thickening of the wall and, thus, is one of the causative factors of respiratory dysfunction in chronic lung graft rejection.     

Chronic thromboxane inhibition preserves function of rejecting rat renal allografts

Increased production of thromboxane (TX) by rejecting renal allografts results in significant and partially reversible renal vasoconstriction. In this study, we evaluated the potential benefit of chronically administering the TX synthetase inhibitor OKY-046 from the time of transplantation in a rat model of acute renal allograft rejection. In animals which received 75 mg/kg/day of OKY-046 by intermittent i.p. injection, allograft function was not improved, but renal thromboxane production was not significantly inhibited. However, animals which received an equivalent dose of OKY-046 by continuous intra-arterial infusion for four days maintained clearances of inulin (4.46 +/- 0.79 ml/min/kg) and PAH (23.86 +/- 1.81 ml/min/kg) at normal levels not different from non-rejecting isografts (4.83 +/- 0.93 and 18.33 +/- 2.55 ml/min/kg, respectively). In contrast, animals which received continuous infusion of saline vehicle alone developed a significant reduction in renal function (CIn: 1.58 +/- 0.27 ml/min/kg; CPAH: 9.12 +/- 1.51 ml/min/kg) by the fourth day after transplantation. Intra-arterial infusion of OKY-046 significantly reduced four-day allograft TXB2 production, as well as urinary TXB2 excretion, but had no effect on allograft production of PGE2 or 6-keto-PGF1 alpha. Despite the beneficial effects on allograft function, OKY-046 neither altered the morphologic appearance of the cellular infiltrate nor the systemic proliferative and cytotoxic anti-donor cellular immune responses. Six days following transplantation, renal TXB2 production was only partially inhibited in animals given continuous infusions of OKY-046, and remained markedly elevated. This partial inhibition of TX production resulted in a slight but insignificant functional improvement.(ABSTRACT TRUNCATED AT 250 WORDS)     

LF 08‐0299 In the prophylaxis and treatment of chronic rejection in a rat aortic allograft model

Abstract Chronic rejection is the major cause of late kidney allograft failure. We evaluated the efficacy of LF 08‐299 (LF), an analogue of 15‐deoxyspergualin, in a rat aortic allograft model of chronic rejection. BN aortic allografts were transplanted to Lew recipients. LF was administered at a dose of 6 mg/kg and 2.5 mg/kg on days 0‐20 and 6 mg/kg on days 60‐90. CyA was used at a dose of 5 mg/kg on days 0‐20. Untreated isografts and allografts were used as controls. Histological changes and immunohistochemistry were monitored sequentially at 8, 12, 16 and 20 weeks. There were no differences in intimal proliferation between LF‐treated allografts and untreated or CyA‐treated controls. Only a tendency in adventitial infiltration reduction was seen in LF‐treated animals. We found a significantly less pronounced reduction in media diameter in LF‐treated animals. We concluded that LF 08‐0299 is only able to reverse reduction in media thickness in aortic allografts, but not intimal proliferation in this model of chronic rejection.     

Chronic rejection of rat renal allograft

Chronic allograft rejection is both a clinical and a histopathological diagnosis. Until recently, the histological definition of chronic renal allograft rejection was based on clinical diagnostic biopsies, where the evidence was partially obscured by recurrence of the original renal disease, and/or by administration of immunosuppressive drugs. In this communication, we present an experimental rat model for chronic renal allograft rejection, devoid of recurrence of the original disease. By comparing allografts to similarly immunosuppressed syngeneic transplants, we define which histological features should be attributed to chronic rejection and which to cyclosporin nephrotoxicity. Rat renal transplants were performed from DA (Ag-B4, RT1^av1) to WF strain (Ag-B2, RT1^u) or, for control, to DA strain, and immunosuppressed for 2 or 3 weeks with cyclosporin using a variety of different dosages. The animals were monitored weekly for serum creatinine levels and for blood cyclosporin concentrations, and core needle biopsies were performed on the grafts at regular intervals. At 3 months post-transplantation the animals were sacrificed and a complete histopathological evaluation was performed. Thirty-one histological variables were scored blindly by two investigators and separately for the graft interstitium, glomeruli, tubuli, and the graft vasculature. The following histological alterations were significantly more prominent in allografts than in similarly immunosuppressed syngeneic transplants: the intensity of interstitial inflammation, particularly the degree of pyroninophilia within the inflammatory cell population; the extent of glomerular mesangial matrix increase, basement membrane thickening, and glomerular sclerosis; the increase in the vascular intimal thickness affecting in particular the first and second order branches of the renal artery; and the obliteration of the graft vasculature. These alterations were considered as being primarily due to chronic rejection. In contrast, the extent of interstitial fibrosis and the extent of tubular changes, including tubular epithelial vacuolation, epithelial atrophy, and tubular basement membrane changes, were not significantly different in the allografts as compared to the syngeneic controls. These alterations were attributed primarily to cyclosporin nephrotoxicity. Serial monitoring of the grafts by needle biopsies clarified the sequence of events in the development of the chronic alterations in the transplant. The first event, as expected, was tubulointerstitial pyroninophilic inflammation, resembling that of acute episodes of rejection. This was significantly stronger and appeared earlier in allografts immunosuppressed for 2 rather than for 3 weeks. Vascular alterations developed next. The last to develop were the glomerular lesions.     

Sequential analysis of adhesion molecules and their ligands in rat renal allografts during the development of chronic rejection

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are important in endothelial cell-leukocyte interactions. In this sequential study, the expression of ICAM-1 and VCAM-1 and their ligands LFA-1 and VLA-4 as well as major histocompatibility complex class II antigens (MHC class II), and interleukin-2-receptor (IL-2R) were investigated during the development of chronic renal allograft rejection in a rat model. The time-related expression of adhesion molecules and their ligands in the graft was correlated to the chronic allograft damage index (CADI). In association with an initial short immune activation, there was a significant ICAM-1 and VCAM-1 induction in the vascular endothelium and the tubular epithelium. In the interstitium, there was infiltration of lymphocytes expressing ligand molecules VLA-4 and LFA-1, as well as activation markers MHC class II and IL-2R. Thereafter, the expression declined together with the increase of CADI-values. In end-stage chronic rejection, there was practically no expression of ICAM-1 and VCAM-1. In the interstitium, there were only few ligand-expressing leukocytes. In conclusion, adhesion molecules and their ligands are involved in the induction phase of the process but no longer in the later stages of chronic rejection. Received: 12 July 1999 Revised: 7 December 1999 Accepted: 27 April 2000     

慢性排斥反应标准动物模型的建立及意义

目的：建立大鼠慢性排斥反应动物模型。方法：将１６５只Ｗｉｓｔｅｒ系和ＳＤ系大鼠分为两组，即异系移植实验组６７只，同系移植对照组９８只。采用腹主动脉移植的方法分别建立慢性排斥反应动物模型，观察术后３，７，１４，２０，３０及６０ｄ各时相点移植动脉病理及免疫组织化学的变化。     

Chronic rejection of liver transplants revisited

We examined 27 hept-ectomy specimens to assess the frequency of foam cell endovasculitis and bile duct loss in chronic rejection. Arterial lesions, defined as total occlusion by subintimal foam cells and/or fibromuscular proliferation, were found mainly in hilar and septal arteries, whereas bile duct loss, defined as the absence of bile ducts in more than 50% of portal tracts, affected aminly small tracts. Both were found in 20 livers (74%). In two livers (7%) there was significant bile duct loss but no arterial lesions, whilst in five cases (19%) there were occlusive arterial lesions but no bile duct loss. Small arteries were involved in only 10% of the cases. These results indicate that in one-third of the cases arterial and bile duct lesions develop independently of each other, suggesting different pathogenetic pathways. In addition, liver biopsy may not be pathognomonic since small arteries are involved in only 10% of cases and bile duct loss may not be extensive. In such cases the diagnosis of chronic rejection should only be made in the presence of progressive clinical deterioration.     

Chronic rejection of human face allografts

Face vascularized composite allografts (FVCAs) have helped patients with severe facial disfigurement, with acute rejection now largely controlled through iatrogenic immunosuppression. However, little is known regarding the incidence and mechanism(s) of more long‐term pathologic alterations in FVCAs that may affect function and graft durability. Protocol surveillance biopsy specimens for up to an 8‐year interval in 7 patients who received FVCAs at our institution revealed histopathologic evidence of chronic rejection. Clinical manifestations included features of premature aging, mottled leukoderma accentuating suture lines, telangiectasia, and dryness of nasal mucosa. Pathologic changes consisted of epidermal thinning accompanied by discrete foci of lymphocyte‐mediated cytotoxicity, hyperkeratosis, follicular plugging, vascular ectasia, and sclerosis beneath the epidermal layer associated with collagen type I deposition. Genomic interrogation and immunohistochemistry of sclerotic zones revealed upregulation of the AP‐1 pathway components, JunB and c‐Fos, previously implicated in overproduction of type I dermal collagen in the setting of systemic sclerosis. We conclude that some patients develop chronic rejection in FVCAs with striking similarities to alterations seen in certain autoimmune cutaneous disorders (lupus erythematosus and scleroderma/chronic sclerodermoid graft‐versus‐host disease). Identification of relevant pathways and genes, such as JunB and c‐Fos, may provide new targets for preventative therapies for chronic immune‐mediated changes in vascularized composite allografts.     

冷保存、慢性排斥反应构建移植肝胆管病大鼠模型

目的 建立大鼠移植肝胆管病模型并评估其意义.方法 将大鼠按实验要求分为4组:(1)长时间(12 h)冷保存组(n=24):同基因系近交系大鼠♂Wistar→♂Wistar,所获供肝于4℃UW液保存12 h后行两袖套法大鼠原位肝移植(rat liver orthotopic transplantation,ROLT).术中利用内支架管直接对合供、受体肝总动脉及肝外胆管;(2)慢性排斥反应组(低剂量环孢素每天1 mg/kg,冷缺血时间1 h)(n=24):异基因近交系大鼠♂DA→♂Lewis.供肝于4℃UW液保存1h后同法行ROLT; (3)对照组(冷保存时间1 h)(n=24):同基因系近交系大鼠♂Wistar→♂Wistar,供肝于4℃UW液保存1h后同法行ROLT; (4)假手术组(n=24):♂Wistar大鼠,只进行开关腹手术.观察术后16周内各组大鼠并发症的发生情况和大鼠肝脏标本的病理学改变.结果 在长时间冷保存组和慢性排斥反应组,术后大鼠意识恢复慢,胆道及血管并发症发生率高,肝内汇管区胆管增生及炎细胞浸润明显.16周时可见肝小叶被增生胆管分隔,正常肝小叶结构消失,增生胆管上皮细胞萎缩、坏死、胞浆消失,仅见固缩的细胞核.胆管周围有较多的炎细胞浸润,肝内小动脉闭塞或消失.结论 通过供肝长时间冷保存或诱导慢性排斥反应可以建立稳定可靠的大鼠移植肝胆管病模型.该模型是研究肝移植术后移植肝胆管病的理想模型.     

Chronic renal allograft rejection: the significance of non-MHC alloantigens

We studied the role of polymorphic endothelial antigens other than MHC in antibody-mediated chronic renal allograft rejection in two models. In the first model, donor Lewis rat kidneys were transplanted into BN recipients that had been made tolerant for donor class I antigens at the B cell (antibody) level. In this setting Lewis kidney grafts were chronically rejected with stable renal function but increasing proteinuria (> 100 mg/24 h). Rejected graft tissue showed mononuclear cell infiltration and the presence of glomerular vasculonecrotic lesions with fibrinoid material, associated with IgG and IgM deposition, but with absent or weak C3 binding. Graft endothelium showed no expression of MHC class II antigens. Serum antibodies were not reactive with donor class I antigens, but did react with endothelial non-MHC alloantigens. In the second model, more direct information on the role of endothelial non-MHC alloantigens in renal allograft rejection was obtained by transplanting Lewis 1 N kidneys into unmodified BN recipients (MHC-matched transplants). Here, similar to the first model, the animals developed severe proteinuria with stable renal function. Histopathological examination showed mononuclear cell infiltration and deposition of IgM and IgG along the glomerular vasculature, but this time in the presence of strong C3 reactivity. However, glomerular vasculonecrotic lesions with intense fibrin deposition were not observed. The data showed that although clinically the two kidney transplantation models used gave similar chronic rejection phenomena, histopathologically some striking differences were observed in the glomeruli. The precise mechanisms effecting chronic rejection of the grafts is still a puzzle. However, immune reactivity against graft (endothelial) non-MHC antigens may play a significant role.     

Infiltration patterns of macrophages and lymphocytes in chronically rejecting rat kidney allografts

The migration of circulating leukocytes to sites of inflammation or antigen is based, at least in part, on the activities of adhesion molecules. In the context of organ transplantation, some of these have been shown to be upregulated during acute allograft rejection. As their role during chronic rejection has not been examined, we have used an established rat model to compare sequentially the presence of host cells within the grafts, as defined immunohistologically, with patterns of in vitro leukocyte binding and their dependence upon particular adhesion molecules. Various donor populations of peripheral blood lymphocytes (PBL), lymph node lymphocytes (LNL), and splenic monocytes were interacted with snap-frozen sections of allografted, isografted, and native kidneys at serial intervals up to 24 weeks after transplantation. Monocyte binding in the allografts rose at 8 weeks and peaked at 12 weeks, a period preceding the maximum numbers of macrophages noted immunohistologically in the chronically rejecting grafts at 16 weeks. Lymphocyte binding and infiltration patterns were similar, remaining stable throughout the follow-up period and consistently greater than those noted in isografts. In vitro binding of the monocytes was inhibited by mAbs against ICAM-1, LFA-1, CD18, and MAC-1; MAC-1 did not influence lymphocyte binding, although the other mAbs were effective. We conclude that adhesion molecules are responsible, at least in part, for patterns of cell populations infiltrating chronically rejecting renal allografts.     

Chronic rejection of rat aortic allograft

Rat aortic allografts immunosuppressed with cyclosporin — but not with azathioprine or steroids — develop an early inflammatory lesion in the subendothelial space. This endothelialitis is followed by an influx of proliferating smooth muscle cells into the intima, resulting in intimal thickening and accelerated arteriosclerosis. Administration of azathioprine and steroids largely ameliorates the development of the accelerated lesion. Similar endothelialitis and accelerated arteriosclerosis have been observed previously in the autopsy material of cardiac transplant recipients. Our results confirm the suggestion that the development of accelerated allograft arteriosclerosis is most likely linked to cyclosporin administration.     

Expression of CD44 in rat liver allografts during rejection

As CD44 is believed to be a homing receptor involved in lymphoid trafficking and inflammatory responses, it is expected to be closely linked to transplant rejection. In this study, the expression of CD44 during liver transplant rejection was compared with the expression of lymphocyte-function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1), which play an essential role in cell interactions and the initiation of immune responses. Male Brown Norway (BN) and Lewis (LEW) rats were used as donors and recipients, respectively. Orthotopic liver transplantation (OLTX) was done using the cuff technique of Kamada and Calne. Animals were killed on days 3, 5, and 7 after OLTX, and a piece of tissue from each of the liver grafts was obtained. Immunohistochemical staining was used to investigate the expression of CD44, ICAM-1, and LFA-1. CD44 was strongly expressed in portal areas of the rejected liver, and LFA-1 and ICAM-1 were expressed mainly on sinusoids and hepatocytes. These findings indicate that CD44 is closely involved in lymphocyte infiltration, which is dominant in portal areas, and that lymphocyte infiltration during the rejection process may involve a homing mechanism. Received for publication on Oct. 17, 1997; accepted on Oct. 21, 1997     

Beneficial effect of proteases on allograft arteriosclerosis in a rat aortic model

Recently it has been shown that protease therapy amelioratescertain immune-mediated diseases. Thus we studied the effectof administration of a protease mixture on aortic transplantarteriosclerosis in rats. Segments of abdominal aorta from SHRstrain were transplanted orthotopically into WKY recipients.Two groups of allografted rats were used. One group (n=8) wastreated with daily intraperitoneal injections of 12 mg of aprotease formulation containing trypsin, bromelain and rutosid,and another group (n=8) with placebo. Eight WKY rats were transplantedwith syngenic aortas and treated with placebo. After 8 weeks,structural changes of the grafted segment were evaluated bymorphometric analysis of formalin-fixed sections with specificstains. In untreated allografts there was a marked intimal thickening,medial necrosis with disruption of elastic fibres, and inflammatoryinfiltrates in the adventitia. Administration of proteases inhibitedformation of neointima by 59.0% when cross-sectional areas werecompared (80±11 versus 195±11 µm², P<0.01;protease-versus placebo-treated allograft recipients respectively)and decreased medial injury as estimated by the integrity ofelastic fibres and smooth-muscle cell density. Thus, in an experimentalmodel of rat aortic allograft, protease administration amelioratesrejection-induced arterial wall remodelling.     

In vivo migration of lymphocytes in chronically rejecting rat kidney allografts

Histological analyses have identified lymphocytes and macrophages as the predominant leukocyte populations that infiltrate organs undergoing chronic rejection. In order to define the time frame of this infiltration, we investigated the in vivo migration pattern of lymphocytes in a well-established rat model of chronic kidney allograft rejection. F344 kidneys were orthotopically transplanted into bilaterally nephrectomized Lewis rats. Recipients were treated with cyclosporin A (1.5 mg/kg/per day) for the first 10 days. After anti-CD18 or vehicle pretreatment, peripheral blood lymphocytes obtained from naive Lewis rats and labeled with 3H-uridine were injected into transplanted rats 12 and 16 weeks after transplantation. Organs were harvested 4, 8, and 12 h thereafter. After 12 weeks, proteinuria developed, accompanied by all signs of chronic rejection including glomerular sclerosis. Labeled lymphocytes rapidly infiltrated grafted kidneys 4 h after injection. Even more lymphocytes had accumulated in the grafts 12 h after injection. After 16 weeks, few lymphocytes had emigrated into the graft at 4 h, while infiltration was most pronounced by 12 h. Pretreatment with anti-CD18 inhibited the influx of lymphocytes. There was no difference between the patterns of lymphocytes derived from naive and transplanted rats. Our results emphasize the importance of endothelial cells in chronically rejecting kidneys for the control of leukocyte influx. β2-integrins may play a central role in determining the transendothelial migration during this process. Received: 26 May 1998 Received after revision: 28 July 1998 Accepted: 25 September 1998     

小肠移植急性排斥反应中bcl-2及bax表达的意义

目的探讨bcl-2及bax的异常表达与小肠移植急性排斥反应的关系。方法选用近交系F344/N和封闭群Wistar/A大鼠建立同种异基因小肠移植模型,并随机分为同基因移植组、异基因移植组、异基因加普乐可复(FK506)治疗组和对照组,用免疫组织化学技术检测36只大鼠术后移植肠组织中bcl-2及bax在移植肠组织中的表达。结果异基因组术后第3天,bcl-2的表达显著低于对照组(P<0.05),并随着移植天数的增加,差异更加具有显著性意义(P<0.01);bax的表达与对照组比较差异无显著性意义(P>0.05);FK506治疗组bcl-2及bax表达与对照组比较,差异均无显著性意义(P>0.05)。结论移植肠组织内bcl-2表达水平可作为早期诊断急性排斥反应的一个有参考意义的指标。     

CD44在大鼠肾移植急性排斥反应中的表达

目的:探讨移植肾组织CD44的表达及血清中可溶性CD44的含量与急性排斥反应的关系。方法:雄性Wistar大鼠和SD大鼠分别作为供体和受体,共分为四组,采用改进的Blom法大鼠原位肾移植模型。免疫组织化学染色法检测移植肾组织CD44分子的表达;酶联免疫吸附试验测定术后血清中可溶性CD44水平的变化。结果:移植肾组织CD44分子的表达在同种异体移植组显著高于同品系移植组、手术对照组及药物治疗组(均P<0.05);移植肾组织CD44分子的表达与急性排斥反应呈正相关(皮质:r=0.734,髓质:r=0.670,均P<0.01);发生急性排斥反应的移植肾组织CD44分子的表达与Banff急性排斥反应指数无相关性(P>0.05);血清中可溶性CD44分子各组间差异无统计学意义,与急性排斥反应及Banff指数均无相关性(均P>0.05)。结论:CD44分子在肾移植急性排斥反应的发病机制中起着重要作用,为进一步提高移植排斥反应防治水平提供理论依据。