Met-RANTES ameliorates fibrous airway obliteration and decreases ERK expression in a murine model of bronchiolitis obliterans.

OBJECTIVES: Bronchiolitis obliterans (BO) is the main cause of late mortality among long-term survivors of lung transplantation. Chemokine-chemokine receptor (CCR) interaction and subsequent recruitment of infiltrating cells to the graft are early events in the development of chronic rejection of transplanted lungs. The present study investigated whether blockade of chemokine receptors CCR1 and CCR5 with Met-regulated-on-activation, normal T cells expressed and secreted (RANTES), an amino-terminal modified derivative of RANTES/CCL5, affects the development of BO in murine model and we sought to determine the expression of RANTES/CCL5 and their relationship with extracellular signal-regulated kinase (ERK). Materials and Methods: BALB/c mouse tracheas were heterotopically transplanted into C57Black6 recipients and treated for 21 days with either Met-RANTES at 20 microg/day or vehicle. Animals were killed at 21 days after transplantation for histologic examination of ERK expression. RESULTS: RANTES/CCL5 was highly expressed in allografts compare to isografts. Met-RANTES treatment ameliorated fibrous airway obliteration in a mouse model of BO and decreased ERK expression. CONCLUSION: Blockade of chemokine receptors by Met-RANTES ameliorated airway obliteration and decreased ERK expression. These findings suggest that chemokine receptors CCR1 and CCR5 play significant roles in the development of chronic rejection and ERK may be a new molecular target for chronic rejection.     

Cytomegalovirus accelerates chronic allograft nephropathy in a rat renal transplant model with associated provocative chemokine profiles

BACKGROUND: Studies have shown that rat cytomegalovirus (RCMV) infection accelerates transplant vascular sclerosis (TVS) in rat heart and small bowel allotransplants. In these models, RCMV-accelerated TVS results from increased graft infiltration of inflammatory cells through up-regulation of chemokine expression. The aim of this study was to determine if RCMV infection accelerates renal transplant chronic allograft nephropathy (CAN), and the role of chemokines in this process. METHODS: F344 kidneys were transplanted into Lewis recipients with and without RCMV infection. To monitor CAN, serum creatinine (Cr) levels were measured starting at 4 weeks posttransplantation. At 7 and 21 days, and at terminal rejection, grafts were examined for histologic changes, inflammatory cell infiltrates, viral load, and chemokine expression profiles. RESULTS: By week 8, serum Cr showed significant elevation (P < .01) in the RCMV-infected group vs uninfected group, and remained significantly elevated through the end of the study. RCMV+ renal allografts had significant inflammatory cell infiltration and increased CAN at postoperative day (POD) 28. The CC chemokines RANTES, MCP-1, and MIP-1alpha, and the CXC chemokine IP-10 were up-regulated in RCMV-infected vs uninfected allografts. IP-10 was significantly up-regulated early in the process, whereas RANTES and MCP-1 were induced at a later time. CONCLUSIONS: RCMV infection accelerates CAN, with associated graft inflammatory infiltrates, which is paralleled by an increase in expression of CC and CXC chemokines. Our findings suggest that the early induction of IP-10 in the infected allografts promotes alterations in T-cell and monocyte migration to the graft, which initiates accelerated inflammatory and fibrotic changes associated with CAN.     

Differential expression of beta-chemokines MCP-1 and RANTES and their receptors CCR1, CCR2, CCR5 in acute rejection and chronic allograft nephropathy of human renal allografts

BACKGROUND: The beta-chemokines MCP-1 (CCL2) and RANTES (CCL5) have been shown to play important roles in acute renal transplant rejection (AR) and chronic allograft nephropathy (CAN). The potential relationship of expression of these chemokines, their chemokine receptors CCR1, CCR2, CCR5, and the cell populations of inflammatory infiltrate, histological and clinical diagnoses were investigated in biopsies at the time of AR and compared with biopsies of CAN. METHODS: In 24 renal transplant biopsies with AR (n = 15) and CAN (n = 9), the expression of MCP-1 and RANTES, their receptors CCR1, CCR2, and CCR5 and the infiltration with monocytes/macrophages and T cells were studied. RESULTS: As previously described, chemokine and chemokine receptor expression was found mainly in mononuclear cells infiltrating the interstitium and glomeruli. In the tubulointerstitial area and glomeruli the expression of MCP-1, RANTES, and their receptors correlated with an infiltration by monocytes/macrophages. Biopsies with CAN revealed a lower expression of MCP-1, RANTES, CCR1, CCR2 and CCR5 in tubulointerstitial cells, and a significantly lower infiltration with MRP14-positive monocytes/macrophages than biopsies with AR. In AR, MCP-1 and CCR1 showed a lower expression compared to RANTES, CCR2, and CCR5. CONCLUSIONS: The positive correlation between chemokines and chemokine receptors and infiltrating leukocytes during acute rejection, the lower but detectable expression of MCP-1, RANTES, CCR1, CCR2 and CCR5 in CAN, and the differences in the quantity of expression between the different chemokines and chemokine receptors point to a complex regulation of chemokine expression in renal allografts. Since chemokines are not only involved in inflammation but also in tissue regeneration, this could have impact on the development of CAN.     

Early and late chemokine production correlates with cellular recruitment in cardiac allograft vasculopathy

BACKGROUND: Cardiac allograft vasculopathy (CAV) remains the leading cause of late mortality in heart transplant recipients. Activated T lymphocytes and macrophages infiltrate the donor heart before vascular intimal thickening develops, but the specific mediators of mononuclear cell recruitment leading to CAV are unknown. Therefore, we sought to define the relationship between chemokine gene expression and production, T lymphocyte and macrophage recruitment, and intimal thickening in a murine model of CAV. METHODS: B10.A or B10.BR strain hearts were transplanted heterotopically into B10.BR mice. Recipients were killed at 1, 4, 7, 14, and 30 days. Donor hearts were assayed for chemokine gene expression with ribonuclease protection and for protein with ELISA. Intragraft cellular infiltration was defined immunohistochemically. Intimal thickening was quantitated morphometrically. RESULTS: Early and late patterns of intragraft chemokine expression associated with distinct cellular infiltration were identified. First, transient MIP-2 and MCP-1/JE production in isografts and allografts correlated with neutrophil and macrophage infiltration. MCP-1/JE production and macrophage infiltration was greater in allografts than isografts. Second, allografts demonstrated sustained lymphotactin, RANTES, and IP-10 expression, beginning at day 4, correlating with persistent macrophage and T lymphocyte infiltration. Intimal thickening became evident at 14 days. Isografts did not display the late pattern of sustained chemokine gene expression, cellular infiltration, or intimal thickening. CONCLUSIONS: Transient, early MIP-2, and MCP-1/JE production in isografts and allografts correlated with neutrophil and macrophage recruitment, and is likely related to ischemia-reperfusion. In allografts, the delayed induction of chemokines specific for macrophages and T lymphocytes correlated with mononuclear cell infiltration and preceded intimal thickening. This study thus demonstrates a dual pattern of chemokine induction correlating with intragraft mononuclear cell recruitment, associated with ischemia-reperfusion and CAV development. Chemokine-directed interventions may interfere with leukocyte trafficking and inhibit CAV development.     

Early increased chemokine expression and production in murine allogeneic skin grafts is mediated by natural killer cells

BACKGROUND: Increased expression of chemokine mRNA is observed in allogeneic but not syngeneic skin grafts 3-4 days after transplantation. The recipient cells mediating this early inflammatory response in allografts remain unidentified. METHODS: Isogeneic and allogeneic skin grafts were transplanted to euthymic and athymic nude mice. mRNA expression and protein production of macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and the murine homolog of Gro(alpha), i.e. KC, from graft homogenates retrieved 3-4 days posttransplantation was tested by Northern blot hybridization and ELISA. To deplete NK cells, recipients were treated with antiasialo GM1 (ASGM1) antisera or with anti-NK1.1 mAb before transplantation. RESULTS: Expression of KC, MIP-1alpha, and MIP-1beta mRNA was equivalent in C57BL/6 allogeneic skin grafts and BALB/c isografts at day 2 posttransplant. At day 3 posttransplant, chemokine mRNA levels decreased in isografts but were maintained at high levels in the allografts. Increased early chemokine mRNA was also observed in C57BL/6, but not BALB/c++ grafts on BALB/c athymi(nu/nu) recipients. Treatment of allograft recipients with ASGM1 or with anti-NK1.1 antibody eliminated NK cells from the spleen and allograft infiltrating cell populations and decreased early chemokine mRNA levels in allografts 60-70%. Analyses of allograft homogenates indicated increased levels of KC, MIP-1alpha, and MIP-1beta protein at day 4 posttransplant that were decreased in recipients depleted of NK cells. Early chemokine mRNA levels were equivalent in isogeneic and semiallogeneic F1 grafts. CONCLUSIONS: Early chemokine mRNA expression and protein production in allogeneic skin grafts is amplified by recipient natural killer (NK) cells. These results indicate a novel function for infiltrating NK cells in mediating early increased intra-allograft chemokine production and inflammation during the initiation of acute rejection.     

Protective effects of FTY720 on chronic allograft nephropathy by reducing late lymphocytic infiltration

BACKGROUND: Lymphocytic infiltration is obvious throughout early and late stages of chronic allograft nephropathy. Early infiltrating lymphocytes are involved in initial insults to kidney allografts, but the contribution of late infiltration to long-term allograft attrition is still controversial. Early application of FTY720 reduced the number of graft infiltrating lymphocytes, and inhibited acute rejection. The present study investigated the potential of FTY720 to reduce the number of infiltrating lymphocytes even at a late stage, and, thus, slow the pace of chronic allograft nephropathy. METHODS: Fisher (F344) rat kidneys were orthotopically transplanted into Lewis recipients with an initial 10-day course of cyclosporine A (1.5 mg/kg/day). FTY720, at a dose of 0.5 mg/kg/day, or vehicle was administered to recipients either from weeks 12 to 24 or from 20 to 24 after transplantation. Animals were harvested 24 weeks after transplantation for histologic, immunohistologic, and molecular analysis. RESULTS: FTY720, either initiated at 12 or 20 weeks after transplantation, reduced urinary protein excretion, and significantly ameliorated glomerulosclerosis, interstitial fibrosis, tubular atrophy, and intimal proliferation of graft arteries at 24 weeks after transplantation. Furthermore FTY720 markedly suppressed lymphocyte infiltration and decreased mRNA levels of interleukin-10 (IL-10), transforming growth factor-beta (TGF-beta), and platelet-derived growth factor-B (PDGF-B) but enhanced the number of apoptotic cells in grafts. CONCLUSIONS: FTY720 ameliorated chronic allograft nephropathy even at advanced stages. Furthermore, our data suggest that this effect was achieved by a reduction of graft infiltrating lymphocytes.     

CXCR3 and CCR5 positive T-cell recruitment in acute human renal allograft rejection

BACKGROUND: Experimental studies suggest that the infiltration of activated T cells into the allograft, the key event in the development of acute renal allograft rejection, depends on the expression of chemokines and their interaction with chemokine receptors expressed on T cells. METHODS: For a more detailed comprehension of the pathogenesis of T-cell recruitment in human acute rejection, the in situ expression of chemokines and chemokine receptors in allografts of 26 patients between day 3 and 9 after renal transplantation was examined in the present prospective study. RESULTS: Immunohistochemical staining showed a significantly increased number of CXCR3 (P<0.01) and CCR5 positive T cells (P<0.01) in the tubulointerstitium of patients with acute allograft rejection according to Banff grade Ia-IIb. Likewise the intrarenal RNA expression of the CXCR3 ligands IP-10 (5.2-fold) and I-TAC (7.2-fold) and the CCR5 ligand RANTES (5.7-fold), was significantly up-regulated in rejecting organs. In situ hybridization revealed that IP-10 but not I-TAC was predominantly expressed by infiltrating leukocytes in the tubulointerstitial area, co-localizing with CXCR3 positive T cells. To a lesser degree expression by tubular cells could be detected, providing a possible explanation for the increased urinary IP-10 excretion we found in patients with rejecting organs. CONCLUSIONS: These data from a prospective, biopsy-controlled study indicate that the local expression of IP-10 and RANTES leads to the directional movement of activated CXCR3 and CCR5 bearing T cells into the renal allograft and mediates acute rejection. Our data provide a rationale that blocking CXCR3 and CCR5 may offer a unique therapeutic approach to prevent episodes of acute rejection in the early phase after renal transplantation.     

急性排斥反应时Fractalkine及其受体在移植心脏中的表达

目的　探讨急性排斥反应过程中Fractalkine(FKN)及其受体CX3CR1在移植心脏局部表达的意义及环孢素A(CsA)对它们的影响。　方法　施行大鼠异位心脏移植术 ,移植大鼠分为 3组 ,每组 45只 ,对照组 5只。SD大鼠间的移植为同系移植组 (A组 ) ,Wistar至SD大鼠的移植分为未用CsA干预组 (B组 )及CsA干预组 (C组 ) ,健康SD大鼠为对照组。采用RT PCR方法检测排斥反应中移植心脏局部FKNmRNA的表达水平 ,免疫组化方法检测FKN和CX3CR1的蛋白表达水平。　结果FKNmRNA与蛋白在A组各时间点和对照组均呈低水平表达 ;在B组的表达变化与急性排斥反应的进程相关 ,术后第 7天FKNmRNA表达上调至峰值 (0 8± 0 2 6) ;C组应用CsA后 ,FKNmRNA表达峰值显著低于B组 (t=2 3 90 ,P <0 0 5 )。FKN和CX3CR1蛋白分别定位于移植心脏血管内皮细胞及间质浸润的单个核细胞中。　结论　急性排斥反应过程中 ,FKN及其受体CX3CR1表达上调 ,与移植物间质单个核细胞浸润密切相关 ;抑制FKN CX3CR1通路的活化可能是CsA发挥作用的又一分子免疫学机制     

Opposite effects of testosterone and estrogens on chronic allograft nephropathy

In the present study we investigated whether donor gender or the effects of sex hormones play the greater role in the development of chronic allograft nephropathy. Kidneys of male and female Fisher rats were orthotopically transplanted into castrated male Lewis recipients. Animals were treated with testosterone, estradiol, or vehicle and the kidneys were harvested 20 weeks after transplantation for histological, immunohistological, and molecular analysis. Testosterone treatment resulted in increased proteinuria and profound glomerulosclerosis, irrespective of donor gender. In addition, mRNA levels of transforming growth factor-beta1 (TGF-beta1) and platelet-derived growth factor-A and B (PDGF-A and B) chains were enhanced in these allografts. Estradiol reduced glomerulosclerosis and mononuclear cell infiltration in allografts of both genders that paralleled a decreased mRNA expression of TGF-beta1, PDGF-A and B. No donor gender-related differences were noted in vehicle-treated animals. Our findings demonstrate that sex hormones rather than donor gender have a significant impact on chronic allograft nephropathy.     

CC-chemokine RANTES is increased in serum and urine in the early post-transplantation period of human renal allograft recipients

BACKGROUND: The chemokine RANTES is a potent chemoattractant for T cells and monocytes that has been shown to enhance inflammation. The aim of our study was to investigate whether RANTES is upregulated within the early post-transplantation period that may influence short-time allograft function rate. METHODS: Serum and urine samples from transplanted renal allograft recipients (n = 17) were obtained from specimens taken for diagnostic reasons. Four patients developed biopsy-proven rejection episodes within the first month. Time course of RANTES was studied within the first 12 days after renal transplantation using ELISA technique. Data were tested for significances between patients with rejection and without rejection, compared to healthy volunteers as controls, and correlated with clinical data. RESULTS: In the control group RANTES concentration was 37.2 +/- 2.7 ng/ml (serum) and 8.1 +/- 1.3 pg/ml (urine), respectively. In transplanted recipients serum RANTES was significantly upregulated up to 132 +/- 28 ng/ml on day 1 after transplantation and remained elevated within the first 12 days (n = 17). Time course of urine RANTES demonstrated elevated concentrations with 754 +/- 115 pg/ml on day 1 followed by an continuous decrease to 22.3 +/- 7 pg/ml on day 12 (n = 17). No significant differences could be detected between patients with rejection and without rejection episodes. CONCLUSIONS: In contrast to data of other urinary marker molecules (like IL-6), there are no significant differences between the rejection and non-rejection group. RANTES is therefore not suitable for early detection of rejection. Nevertheless, serum and urine RANTES concentrations were highly elevated in freshly transplanted renal allograft recipients reflecting an activated immune system.     

Genetic deletion of chemokine receptor CXCR3 or antibody blockade of its ligand IP-10 modulates posttransplantation graft-site lymphocytic infiltrates and prolongs functional graft survival in pancreatic islet allograft recipients

BACKGROUND: Interaction of chemokine receptor CXCR3 with its ligand IP-10 mediates effector cell trafficking to sites of allograft rejection in murine models of whole organ allotransplantation. We hypothesized that blocking the CXCR3/IP-10 interaction would impair posttransplantation leukocyte trafficking to and delay rejection of pancreatic islet allografts. METHODS: A/J strain murine islets were implanted to the kidney capsule of H-2 disparate, streptozotocin-induced diabetic wild type (WT), CXCR3 deficient (CXCR3(-/-)) or IP-10 antibody-treated WT (alphaIP-10) C57BL/6 recipients. Representative grafts from each group were harvested at day 7. Ribonuclease protection assay was used to determine gene expression for cell markers F4/80 (macrophages), CD8 (type I T cells), CD4 (type II T cells), and CD 19 (natural killer cells), and for chemokines IP-10, MIP-1alpha, MIP-1beta, MCP-1, and RANTES. Immunohistochemistry was used to confirm ribonuclease protection assay infiltrate data. Graft-site chemokine gene expression and cellular infiltrate were correlated with time to functional graft rejection. RESULTS: Untreated WT recipients demonstrated heavy graft-site cell infiltrates and increased graft-site gene expression for cell markers F4/80, CD8, CD4, and CD19, and for chemokines RANTES, IP-10, and MIP-1beta at day 7. In comparison with untreated WT, alphaIP-10-treated WT and CXCR3(-/-) recipients demonstrated the same degree of chemokine gene expression but less lymphocytic infiltrate. The mean length of allograft survival was 12.7 +/- 3.1 days in untreated WT versus 20.2 +/- 2.7 days (P <.05) for CXCR3(-/-)- and 19.7 +/- 2.3 days (P <.05) for alphaIP-10-treated WT recipients. CONCLUSIONS: CXCR3 gene deletion or alphaIP-10 antibody therapy modulates posttransplantation lymphocytic graft infiltration and statistically prolongs graft survival in murine islet allograft recipients.     

Beneficial effects of targeting CCR5 in allograft recipients

BACKGROUND: The chemokine receptor, CCR5, and its three high-affinity ligands, macrophage inflammatory protein- (MIP) 1alpha, MIP-1beta, and regulated on activation normal T cell expressed and secreted (RANTES), are expressed by infiltrating mononuclear cells during the rejection of clinical and experimental organ allografts, although the significance of these molecules in the pathogenesis of rejection has not been established. METHODS: We studied intragraft events in four allograft models. First, we studied cardiac transplants in fully MHC-mismatched mice that were deficient in CCR5 or two of its ligands, MIP-1alpha or RANTES. Second we tested the effects of a neutralizing rat anti-mCCR5 monoclonal antibody on allograft survival. Third we assessed whether a subtherapeutic course of cyclosporine would potentiate enhance survival in CCR5-deficient recipients. Finally, we tested the effect of targeting CCR5 in a class II-mismatched model. RESULTS: Whereas mice deficient in expression of MIP-1alpha or RANTES reject fully MHC-mismatched cardiac allografts normally, CCR5-/- mice, or CCR5+/+ mice treated with a neutralizing mAb to mCCR5, show enhanced allograft survival. MHC class II-disparate mismatched are permanently accepted in CCR5-/- but not CCR5+/+ recipients. Finally, the beneficial effects of targeting of CCR5 are markedly synergistic with the effects of cyclosporine, resulting in permanent engraftment without development of chronic rejection. CONCLUSIONS: We conclude that CCR5 plays a key role in the mechanisms of host T cell and macrophage recruitment and allograft rejection, such that targeting of CCR5 clinically may be of therapeutic significance.     

Prevention of allograft heart valve failure in a rat model

OBJECTIVE: Allograft heart valves are commonly used in cardiac surgery. Despite mounting evidence that these valves are immunogenic, leading to premature failure, current clinical practice does not attempt to minimize or control such a response. The objective of this study was to evaluate immune modulatory approaches to ameliorate allograft valve failure in a rat model. METHOD: Aortic valve grafts were implanted infrarenally into Lewis rat recipients (n = 32). There were 4 transplant groups: syngeneic grafts (Lewis to Lewis), untreated allografts (Brown Norway to Lewis), allograft recipients treated with cyclosporine (INN: ciclosporin) (10 mg/kg per day for 7 or 28 days), and allograft recipients treated with anti-alpha4 integrin and anti-beta2 integrin monoclonal antibodies for 7 days. At 7 and 28 days the valves were examined for structural integrity and cellular infiltration. RESULTS: Both cyclosporine and anti-alpha4/beta2 integrin treatment resulted in significant reduction in leaflet infiltration by macrophages (ED1(+)), T cells (CD3(+)), and CD8(+) T cells at 7 days with preservation of structural integrity when compared with control allografts. Twenty-eight days after implantation, daily treatment with cyclosporine preserved leaflet structural integrity and inhibited cellular infiltration. However, a short course of cyclosporine (7 days) failed to prevent destruction of the valves at 28 days. CONCLUSIONS: Immune modulatory approaches aimed at T-cell activation or trafficking decrease leaflet cellular infiltration and prevent allograft valve structural failure. However, short-course therapy does not appear to be sufficient and must be maintained to allow long-term preservation of leaflet structural integrity (28 days).     

Airway Epithelium is the Primary Target of Allograft Rejection in Murine Obliterative Airway Disease

Murine heterotopic tracheal allografts develop obliterative airway disease (OAD), a suitable model of chronic lung allograft rejection. This model, however, fails to account for the behavior of the allograft when adjacent to recipient airway tissues, particularly the epithelium. This study was performed to determine the immunologic role of the epithelium in development of OAD. BALB/c (H2d) tracheal allografts were transplanted orthotopically into C57BL/6 (H2b) mice and harvested 14-150 days post-transplantation. The phenotype of the allograft epithelium after orthotopic transplantation was determined with immunofluorescent staining. Orthotopic BALB/c tracheal allografts harvested at 28 days were re-transplanted heterotopically into BALB/c or C57BL/6 mice, harvested after 28 days, and assessed for OAD. Orthotopic allografts displayed mild cellular infiltration, no fibrosis and preserved epithelium at 28 days post-transplant. The presence of recipient-derived epithelium within the allograft was demonstrated with immunofluorescent staining at day 14. Significantly, BALB/c orthotopic allografts re-transplanted heterotopically into BALB/c mice developed OAD by day 28, whereas BALB/c orthotopic allografts re-transplanted heterotopically into C57BL/6 mice did not. Repopulation of orthotopic tracheal allografts with recipient-derived epithelium confers a protective effect against OAD after heterotopic re-transplantation. This indicates that the airway epithelium plays a crucial role in OAD development.     

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.     

BCA-1/CXCL13 expression is associated with CXCR5-positive B-cell cluster formation in acute renal transplant rejection

BACKGROUND: Recent studies showed a crucial role for B cells in acute renal allograft rejection. It remains largely unknown, however, which mechanisms lead to the B-cell recruitment into the allograft. The chemokine CXCL13 and its corresponding receptor CXCR5 play a central role in B-cell trafficking to secondary lymphatic tissue and ectopic B-cell clusters in rheumatoid arthritis. We therefore investigated the potential role of CXCL13 and CXCR5 in formation of B-cell clusters in renal transplant rejection. METHODS: Serial immunohistochemical staining for CXCL13, CXCR5, and CD20 was carried out in protocol biopsies of 23 patients obtained between day 4 and day 9 after renal transplantation. Intragraft mRNA expression of CXCL13 was assessed by real-time polymerase chain reaction (PCR) analysis. RESULTS: Of 23 kidney biopsies obtained between days 4 and 9 after renal transplantation, 13 revealed an acute rejection. Four of these patients showed a substantial infiltration of the transplant with cluster-forming B cells. By immunohistochemistry CXCL13 and the corresponding receptor CXCR5 were exclusively detected in areas of B-cell clusters. Intrarenal CXCL13 mRNA expression was 27-fold higher in transplants with B-cell clusters compared to rejecting allografts without B-cell accumulation (P= 0.011). CONCLUSION: We describe a striking colocalization of CXCL13 expression with CXCR5- and CD20-positive B cells in renal transplants undergoing rejection. This is the first study demonstrating a potential role of CXCL13 and its specific receptor CXCR5 in recruitment of B cells in renal allograft rejection.