Cytomegalovirus chemokine receptor M33 knockout reduces chronic allograft rejection in a murine aortic transplant model

BackgroundNumerous studies suggest that cytomegalovirus (CMV) infection may act as isolated risk factor in the development of cardiac allograft vasculopathy (CAV). Viral G protein-coupled receptors (GPCRs) are thought to contribute to the pathogenic changes associated with CMV infection. The aim of this study was to investigate the role of murine cytomegalovirus GPCR M33 in the development of CAV in a murine aortic allograft model.MethodsMHC I-mismatched aortas of C.B10 (H2^b) mice were transplanted into BALB/c (H2^d) recipients, which were either mock-infected, infected with wild type (WT) MCMV or MCMV with a deleted M33-receptor gene (delM33). Persistence of cytomegalovirus infection was confirmed by qPCR and by luciferase assay to ensure active viral replication. Grafts were harvested on days 21 and 37 for intragraft mRNA expression and histological analysis.ResultsActive viral replication was demonstrated and MCMV presence was confirmed by PCR within spleen, liver, salivary glands, lung and the aortic transplant. Infection with delM33 resulted in significantly less intimal proliferation compared to WT-MCMV but more pronounced proliferation than in mock-infected allografts (32.19% [delM33] vs. 41.71% [WT-MCMV] vs. 24.33% [MCMV-]). Intragraft expression of most analyzed genes was significantly increased in infected mice. VCAM-1, ICAM-1, PDGFβ, CXCR3 and Granzyme B were distinctly less expressed in grafts of delM33 infected compared to WT infected mice. Cellular infiltration revealed reduced dendritic cells and T cells in grafts infected with delM33 compared to WT MCMV.ConclusionsThese data suggest that the MCMV encoded receptor M33 plays an important role as a viral effector mechanism contributing to the development of CAV in a murine aortic transplant model.     

Development of a mouse aortic transplant model of chronic rejection

Chronic rejection is the most common cause of late graft failure after solid organ transplantation. A model of chronic rejection, the rat aortic allograft, has histologic features that parallel those in the vessels of human transplanted organs. However, the molecular tools required to dissect the immunology of chronic rejection are unavailable in the rat. We developed aortic transplantation in the mouse as a new model of chronic rejection. This will allow the use of the diversity of recombinant cytokines and monoclonal antibodies available for the mouse and its well-defined genetics to investigate chronic rejection in greater detail. We describe the perioperative care and surgical technique for the model in which a 1 cm segment of donor thoracic aorta was used to replace a section of recipient abdominal aorta below the renal arteries and above the aortic bifurcation. Mortality rates were initially high (70%) due to thrombosis and shock. Changes in technique and operator facility resulted in a high rate of success (75%). After 192 operations, the current success rate is >80%. Mice free from complications at 12 hrs postop had indefinite survival, and after 2 months the typical vascular lesion of chronic rejection was present. This new model of chronic rejection will be a valuable tool to study the molecular immunology and genetics of chronic rejection. © 1995 Wiley-Liss, Inc.     

Macrophage subpopulations and their impact on chronic allograft rejection versus graft acceptance in a mouse heart transplant model

Macrophages infiltrating the allografts are heterogeneous, consisting of proinflammatory (M1 cells) as well as antiinflammatory and fibrogenic phenotypes (M2 cells); they affect transplantation outcomes via diverse mechanisms. Here we found that macrophage polarization into M1 and M2 subsets was critically dependent on tumor necrosis factor receptor–associated factor 6 (TRAF6) and mammalian target of rapamycin (mTOR), respectively. In a heart transplant model we showed that macrophage‐specific deletion of TRAF6 (LysM^CreTraf6 ^fl/fl) or mTOR (LysM^CreMtor^fl/fl) did not affect acute allograft rejection. However, treatment of LysM^CreMtor^fl/fl recipients with CTLA4‐Ig induced long‐term allograft survival (>100 days) without histological signs of chronic rejection, whereas the similarly treated LysM^CreTraf6 ^fl/fl recipients developed severe transplant vasculopathy (chronic rejection). The presentation of chronic rejection in CTLA4‐Ig–treated LysM^CreTraf6 ^fl/fl mice was similar to that of CTLA4‐Ig–treated wild‐type B6 recipients. Mechanistically, we found that the graft‐infiltrating macrophages in LysM^CreMtor^fl/fl recipients expressed high levels of PD‐L1, and that PD‐L1 blockade readily induced rejection of otherwise survival grafts in the LysM^CreMtor^fl/fl recipients. Our findings demonstrate that targeting mTOR‐dependent M2 cells is critical for preventing chronic allograft rejection, and that graft survival under such conditions is dependent on the PD‐1/PD‐L1 coinhibitory pathway.     

排斥反应时血清可溶性白细胞相关免疫球蛋白样受体1的水平及意义

目的 探讨可溶性白细胞相关免疫球蛋白样受体1(sLAIR-1)与移植物排斥反应的相关性.方法 采用双抗体夹心酶联免疫吸附试验测定23例肝移植、139例肾移植患者的血清sLAIR-1水平,并以健康志愿者为对照.结果 健康志愿者的血清sLAIR-1水平为(4.3±2.3)μg/L,移植器官功能正常者(肝移植11例,肾移植87例)的sLAIR-1为(6.3±3.7)μg/L,二者比较,差异无统计学意义(P>0.05).肝移植后发生急性排斥反应的6例患者,其血清sLAIR-1水平为(47.2±25.9)μg/L;肾移植后后发生急性排斥反应的20例患者,其血清sLAIR-1水平(36.3±14.7)μg/L;移植肾功能丧失的5例患者,其血清sLAIR-1水平为(28.8±9.4)μg/L,上述三者的血清sLAIR-1水平均明显高于移植物功能正常者和健康志愿者(P<0.01).移植肝重度排斥反应的1例,其血清sLAIR-1高达117.3μg/L,为正常人的27倍.移植肝慢性排斥反应者(5例)和移植肾慢性排斥反应者(27例)的血清sLAIR-1水平分别为(16.1±6.4)μg/L和(13.1±5.5)μg/L,也明显高于移植物功能正常者和健康志愿者(P<0.05).结论 发生排斥反应者的血清sLAIR-1水平升高,其水平的升高可能是发生排斥反应的重要风险因素.     

Glomerular transplant rejection: a distinctive pattern of early graft damage

Five hundred seventy-six consecutive biopsy or nephrectomy specimens obtained during the first 6 months of transplantation from 300 grafts in 431 recipients were examined by light microscopy for focal or diffuse endocapillary hypercellularity. Forty-seven (8.2%) of the 576 specimens obtained from 37 (12.3%) of the 300 grafts exhibited segmental or global occlusion of capillaries by swollen cells in 40-100% of glomeruli per biopsy. The lesions occurred at any time after transplantation, but 34 (72.3%) were present by day 60 and 7 (14.9%) before day 10. Immunofluorescence in 39 affected biopsies revealed focal or segmental glomerular staining in 18 (46.2%), among which IgM was found most frequently, and was considered to be non-specific. Electron micrographs of 17 biopsies from 14 grafts revealed that glomerular capillaries were narrowed or occluded by mononuclear cells of uncertain type, possibly monocytes, as well as lymphocytes and a few neutrophils. Complement-fixing antibody titers to cytomegalovirus rose at least fourfold in 10 (45.5%) of the 22 patients studied, but glomerular lesions were no more severe in the seroconverters than in the non-converters, and there was no consistent temporal relationship between the occurrence of glomerular changes and seroconversion. Cellular or vascular rejection was present in most biopsies. One year graft survival was 34% among 35 accessed grafts with glomerular lesions, compared to 55% among 243 biopsied grafts with no glomerular changes. We consider that these lesions do not have a consistent association with cytomegalovirus infection and that they represent a distinctive form of glomerular rejection. Whether they indicate a poor graft survival, as the present results suggest but do not prove, requires further studies of other series of cases.     

Is graft irradiation of value in renal transplant rejection?

Thirty-six patients who received renal transplants and who subsequently underwent rejection episodes were randomized into two groups before undergoing treatment. One group received high doses of steroid drugs, and the other group received in addition 600 rads of radiotherapy to the graft. After 3 years (minimum follow-up 12 months) the groups were compared with respect to initial response to treatment, patient and graft survivals, and level of transplant function. No benefit was obtained by the group receiving radiotherapy.     

趋化因子受体CXCR3动态检测在早期诊断肝移植术后急性排斥中的应用价值

目的：探讨趋化因子受体 CXCR3动态变化与肝移植排斥的关系及其在早期诊断中的意义。方法：以 2005年4月～2005年9月在本院行肝移植术的30例病人为研究对象，采用流式细胞仪检测病人术前1d 及术后第 1、 3、 5、 7天外周血中淋巴细胞 CXCR3的表达，临床诊断为急性排斥的病人在确诊当天以及经激素冲击治疗后第3、 7天各检测病人外周血中淋巴细胞 CXCR3的表达变化。结果：急性排斥反应(AR)组病人的 CXCR3表达均明显升高， 与非排斥组、肝癌肝硬化组及正常人对照组有明显差异(P＜0． 01) ，当 AR 组经冲击治疗逆转后 CXCR3表达明显下降 并维持持较低水平。结论：外周血中 CXCR3的表达与排斥反应密切相关，可作为诊断急性排斥反应的发生及观察抗 排异疗效的指标。     

Acute graft pyelonephritis: a potential cause of acute rejection in renal transplant

Acute graft pyelonephritis is a common complication in renal transplant recipients. The consequences of this complication on kidney allograft survival remain controversial. Bacterial infection is likely to activate the immune system, potentially leading to acute or chronic rejection. Here, we report for the first time two documented cases of acute rejection occurring shortly after acute graft pyelonephritis, suggesting that pyelonephritis can initiate acute rejection. The immunologic process leading to the alloimmune response is discussed. These reports suggest that acute rejection should be questioned in case of atypical graft outcome in the context of acute graft pyelonephritis.     

趋化因子IP-10及其受体CXCR3在大鼠肝移植急性排斥反应中的作用

目的探讨趋化因子IP-10及其受体CXCR3的表达在大鼠肝移植手术前后的动态变化,分析其与肝移植急性排斥(acute rejection,AR)的关系。方法改良"二袖套"法建立大鼠原位肝移植模型和急性排斥模型,分为4组:手术创伤组,肝移植无排斥组,肝移植急性排斥组,FK506组。ELISA法检测血清IP-10表达。流式细胞仪检测外周血淋巴细胞CXCR3的表达,用Cellquest软件分析阳性细胞百分率。半定量RT-PCR检测各组第7天肝脏组织CXCR3-mRNA的表达。结果①各组大鼠手术后外周血趋化因子IP-10及其受体CXCR3表达明显升高;②AR组在术后第5天起IP-10及其受体CXCR3表达均高于各对照组(P0.01);③AR组大鼠在移植后第7天,外周血IP-10和CXCR3的表达随着AR组RAI积分的升高而逐步升高,相关系数分别为0.89和0.92(P0.05)。结论血清中趋化因子IP-10及其受体CXCR3的高表达与AR密切相关,有望成为诊断AR较特异、敏感的指标。     

Cytokine gene polymorphism and early graft rejection in liver transplant recipients

Cytokines, which play important roles in allograft rejection, show variable production among individuals. These variations may be related to genetic polymorphisms within the regulatory regions of the cytokine genes. We investigated the association between the role tumor necrosis factor alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interferon gamma (IFN-gamma), interleukin (IL)-10 and IL-6 gene polymorphisms and early graft rejection among liver transplant recipients. Forty-three liver transplant recipients enrolled in this study were divided into 2 groups based on events in the first 2 months posttransplantations, namely, those experiencing at least 1 rejection episode (n = 26) or those without any episode (n = 17). The allele or genotype frequencies of cytokine gene polymorphisms showed no difference between liver recipients with or without nonrejection. In conclusion, there was no significant correlation between early graft rejection and cytokine gene polymorphism of TNF-alpha, TGF-beta, IL-10, IL-6, and IFN-gamma in liver transplant recipients.