Tumor Necrosis Factor Receptor -1 and -2 Double Deficiency Reduces Graft Arterial Disease in Murine Cardiac Allografts

Graft arterial disease (GAD) remains the leading cause of long-term solid organ allograft failure. Tumor necrosis factor (TNF) promotes multiple aspects of allograft rejection via binding to type 1 (p55) and type 2 (p75) receptors. We used TNF type 1 receptor deficient (TNFR1KO), type 2 receptor deficient (TNFR2KO) and receptor double-deficient (TNFRDKO) mice to assess the relative roles of TNFR in acute rejection and GAD. Heterotopic cardiac transplantation was performed between C57BL/6 (B/6) and Balb/c (B/c) mice (total allomismatches) to assess the effects on graft survival; B/6 and Bm12 mice (class II mismatches) were used to assess the effects on GAD 8 weeks after transplantation. We found that graft survival in the total allomismatch combinations was the same regardless of TNFR status. In class II mismatches, wild-type (WT) combinations showed severe GAD, and GAD was not diminished when WT hearts were transplanted into TNFRDKO hosts. TNFR1KO donors or TNFR2KO donors had GAD comparable to WT donors, however, GAD was significantly diminished in B/6 TNFRDKO donor hearts. We conclude that both p55 and p75 signals on donor vascular wall cells are involved in the development of GAD, and either TNFR is capable of mediating a response that will culminate in GAD.     

Renal protective effects of pitavastatin on spontaneously hypercholesterolaemic Imai Rats.

BACKGROUND: Independent of their lipid-lowering effects, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have renal protective effects on various models of progressive renal diseases, therefore, additional therapeutic advantages have been considered. In the present study, using spontaneously hypercholesterolaemic Imai rats, we examined the protective effects of pitavastatin on renal injuries and the oxidative modification of the low-density lipoprotein (LDL) and high-density lipoprotein (HDL), since oxidized lipoproteins are speculated to be involved in the mechanism of this rat strain's renal injuries. METHODS: Male Imai rats were treated with pitavastatin (n = 11) at a dose of 100 mg/kg diet or received no specific therapy as controls (n = 11) from 10 to 22 weeks of age. Body weight, urinary protein excretion and serum constituents were evaluated every 4 weeks. At the end of the study, the effects of pitavastatin on the susceptibility of serum LDL and HDL to oxidation, and renal histology were examined. RESULTS: Pitavastatin treatment did not affect hyperlipidaemia, but significantly reduced proteinuria and preserved creatinine clearance deterioration. At the end of the study, lag times for LDL and HDL oxidation were prolonged by the treatment of pitavastatin to 126 and 153%, respectively, compared with the controlled group. The glomerulosclerosis index (SI) for untreated controlled rats was significantly higher than that for the pitavastatin-treated group. An immunohistochemistry study showed significantly lower numbers of ED-1 positive macrophages in the glomeruli and interstitium in pitavastatin-treated rats compared with those controlled. CONCLUSION: Pitavastatin treatment prevented renal injuries in Imai rats independent of lipid-lowering effects. Prevention of oxidative modification of LDL and HDL may play an important role on the beneficial effects of pitavastatin treatment.     

Cardiac allograft rejection in the absence of macrophage migration inhibitory factor

BACKGROUND: Macrophage migration inhibitory factor (MIF) is a secreted proinflammatory lymphokine essential for elicitation of delayed-type hypersensitivity (DTH) reactions in vivo. We tested whether MIF blockade-absence affected acute or chronic murine cardiac allograft rejection. METHODS: Wild-type (WT) C57BL/6 (B6) mice underwent transplantation with BALB/c hearts with or without blocking anti-MIF antibody, and MIF knockout (KO) B6 mice underwent transplantation with MIF KO BALB/c hearts. Chronic immune injury was induced in WT and KO recipients using donor-specific transfusion and anti-CD40L antibody. RESULTS: Unexpectedly, the blockade or genetic absence of MIF did not prolong graft survival even if recipient T-cell cytotoxicity was additionally impaired. The histologic manifestations of acute and chronic immune injury to the allograft were similar between groups. CONCLUSIONS: MIF is not required for acute or chronic allograft rejection in mice. The findings raise questions about the role of DTH as an important mediator of cardiac allograft injury.     

Graft Protective Effect of HMG-CoA Reductase Inhibitor Pravastatin in Murine Cardiac Allograft Transplantation

The HMG-CoA reductase inhibitor (statin), which reduces serum cholesterol, has been demonstrated in the control of immune responses and may potentially play an important role in the regulation of acute and chronic rejection in organ transplantations. We investigated the graft-protective effect of a kind of statin, pravastatin, in the survival of fully major histocompatibility complex--mismatched murine cardiac allograft transplantation. Fully vascularized heterotopic hearts from C57BL/6 donors were transplanted into CBA recipients through microsurgical techniques. CBA recipients transplanted with a C57BL/6 heart received oral administration of 40, 120, or 400 μg/kg/day of pravastatin from the day of transplantation to 7 days afterward. Immunohistochemical staining studies were performed to determine whether intimal formation of coronary arteries in the transplanted cardiac allografts was preserved and also to conduct morphometric analysis. Untreated CBA recipients rejected C57BL/6 cardiac grafts acutely (median survival time [MST] 7 days). CBA recipients exposed with 40 and 120 μg/kg/day of pravastatin had a small prolonged allograft survival (MSTs of 10 and 9 days, respectively). However, the MST of CBA recipients exposed to 400 μg/kg/day of pravastatin was significantly effective for allograft survival (MST 50 days). Immunohistochemical staining assessments on 4 weeks after grafting showed suppression of intimal hyperplasia in allograft coronary arteries. Pravastatin could induce the prolongation of fully major histocompatibility complex--mismatched cardiac allograft through the protection of the coronary artery.     

Spontaneous allograft tolerance in B7-deficient mice independent of preexisting endogenous CD4+CD25+ regulatory T-cells

BACKGROUND: Acute cardiac allograft rejection requires host, but not donor, expression of B7-1/B7-2 costimulatory molecules. However, acute cardiac rejection requires direct antigen presentation by donor-derived antigen presenting cells to CD4 T-cells and does not require indirect antigen presentation to CD4 T-cells. Given this discrepancy in the literature and that the consequence of allograft exposure in B7-deficient mice is unknown; the goal of the study was to examine the antidonor status of allografted B7-1/B7-2-deficient hosts. METHODS: C57Bl/6 B7-1/B7-2-/- mice were grafted with heterotopic BALB/c hearts. Recipients bearing long-term surviving allografts were used to examine the status of antidonor reactivity in vitro and in vivo. Tolerance was examined in vivo through adoptive transfer of splenocytes from graft-bearing animals to secondary immune-deficient Rag-1-/- hosts bearing donor-type or third-party cardiac allografts and by regulatory T-cell depletion with anti-CD25 antibody. RESULTS: When transferred to B7-replete Rag-1-/- recipients, cells from na?ve B7-1/B7-2-/- mice readily initiated cardiac allograft rejection. However, splenocytes transferred from long-term allograft acceptor B7-1/B7-2-/- hosts failed to reject donor-type hearts but acutely rejected third-party allografts. In addition, such cells did not reject (donorxthird-party) F1 allografts. Finally, in vivo depletion of regulatory T-cells did not prevent long-term acceptance. CONCLUSIONS: Results demonstrate that B7-deficient T-cells are capable of acute cardiac allograft rejection in a B7-replete environment. Importantly, results also show that B7-deficient hosts do not simply ignore cardiac allografts, but rather spontaneously develop transferable, donor-specific tolerance and linked suppression in vivo. Interestingly, this tolerant state does not require endogenous CD4+CD25+ regulatory T-cells.     

他汀类药物在同种异体全厚皮片移植中的作用

目的：研究他汀类药物在同种异体全厚皮片移植中作用。方法：荷兰黑兔作为供体,日本白兔作为受体。实验分为三组（n=8）：1组,空白对照组;2组,小剂量他汀类药物（术后给于2mg／kg／天）;3组,大剂量他汀类药物（术后给于4mg／kg／d）。通过临床评估和病理组织活检来计算皮片的存活时间以及他汀类药物抑制炎性细胞浸润的作用,通过免疫组织化学检测和外周血IL-2水平测定来观察他汀类药物在对抗急性炎症反应的作用。结果：全厚皮片的存活时间：1组,（7．0±1．07）天;2组,（8．13±1．13）天;3组,（13．25±0．71）天。3组的存活时间长于1组和2组,但1组和2组之间比较没有统计学差异．大剂量阿托伐他汀延长了皮片的存活时间,阻止了淋巴细胞的浸润,而且在对抗急性排斥反应中有很大的作用。结论：阿托伐他汀延长了同种异体全厚皮片移植的存活时间,抑制了炎性细胞的浸润,有效的对抗急性排斥反应。     

Prolonged survival of heart allografts from p53-deficient mice

BACKGROUND: Acute rejection of the heart allograft is the major cause of heart failure in the first month after transplantation. Most studies on the prevention of acute rejection have concentrated on immune suppression of the recipients, whereas little is known about the effects of genetically manipulated donor organs on heart allograft survival. Herein, we describe a mouse model of heart allografts donated by p53-/- mice that can prolong the survival time of the grafts. METHODS: Hearts of p53-/- or p53+/+ C57BL/6J mice were grafted to the neck carotid artery and jugular vein of BALB/c mice using a cuff technique. The graft survival was observed daily. The hearts were analyzed using several techniques, including histology, immunofluorescence, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and Western blot analysis. RESULTS: p53+/+ allografts ceased beating at 7.6+/-0.5 days, whereas p53-/- hearts were beating at 10.5+/-1.1 days after transplantation (P<0.01). Mean histological rejection scores were significantly lower in allografts donated by p53-deficient mice. Furthermore, apoptotic cells, determined by TUNEL and a reagent kit for detection of cardiac apoptosis, were of high numbers in the allograft sections from wild-type hearts but rare in p53-/- allografts (4.2+/-1.3 vs. 0.7+/-0.5/250x field). Immunofluorescence staining and Western blot analysis revealed that high levels of p53 and proapoptotic protein Bax were expressed in wild-type grafts but not p53-/- allografts. Interestingly, Bcl-2, an antiapoptotic protein, was abundant in cardiac allografts from p53-/- mice and almost undetectable in grafts from wild-type mice. CONCLUSIONS: Thus, p53 is involved in cardiac apoptosis induced by alloimmune reaction, and prolonged survival of heart allografts can be achieved when p53 is lacking.     

Importance of donor- and recipient-derived selectins in cardiac allograft rejection

The selectins expressed on activated endothelial cells (E- and P-selectin), leukocytes (L-selectin), and platelets (P-selectin) play crucial roles in the rolling and tethering of leukocytes. We explored the importance of donor and recipient selectins in acute and chronic cardiac allograft rejection using mice deficient in all three selectins (ELP-/-). In BALB/c recipients, survival of fully allomismatched hearts from ELP-/- C57BL/6 donors was almost double that of wild-type grafts. In ELP-/- cardiac allografts, mononuclear cell infiltration and vasculitis of intramyocardial coronary arteries were significantly reduced. Interestingly, ELP-/- grafts were rejected similarly in both the presence and the absence of recipient selectins, and both wild-type and ELP-/- recipients promptly rejected wild-type hearts. Alternative adhesive molecules such as alpha4beta7 integrin may compensate for the lack of selectins and may mediate rejection in ELP-/- recipients. Chronic rejection was evaluated in a major histocompatibility complex (MHC) class II mismatch model using C57BL/6.C-H2(bm12) mice. While lack of selectins in recipients did not offer protection against chronic rejection, luminal stenosis of coronary arteries in ELP-/- grafts was markedly diminished. In conclusion, donor-derived selectins contribute to the development of both acute and chronic cardiac allograft rejection, and targeting donor selectins may open novel therapeutic approaches in clinical transplantation.     

Fluvastatin in combination with rad significantly reduces graft vascular disease in rat cardiac allografts

BACKGROUND: RAD is a potent immunosuppressive agent that has been shown to be effective in preventing acute and chronic allograft rejection in animal models. The HMGCoA reductase inhibitors have been found to reduce the incidence of graft vascular disease (GVD) in heart transplant patients and in animal models. This study was designed to investigate the effects of fluvastatin or pravastatin in a rodent model of GVD produced using low doses of RAD to prevent acute rejection. METHODS: Hearts from Fisher 344 rats were heterotopically transplanted to Lewis rat recipients. RAD was administered orally at 0.5 mg/kg per day for days 0 to 14 and then 0.25 mg/kg per day for an additional 85 days to prevent acute rejection but allow for the development of GVD. Pravastatin (20 mg/kg per day) or fluvastatin (2 or 6 mg/kg per day) was added to the RAD treatment. At the end of a 100-day treatment period, the hearts were harvested for morphometric and histopathologic examinations. RESULTS: Rats treated with fluvastatin, at either dose, had a significant (P< or =0.0239) decrease in coronary arterial intimal thickening (GVD) of approximately 43%. Rats treated with pravastatin had a 22% reduction in GVD that did not reach statistical significance. Treatment with fluvastatin, but not pravastatin, decreased the degree of endomyocardial mononuclear cell infiltration seen with RAD administered alone. CONCLUSIONS: Fluvastatin significantly decreased GVD in a rat model produced using low-dose RAD immunosuppression. To a lesser extent, pravastatin also decreased GVD in this model. These data lend further support for the study of fluvastatin, pravastatin, and other HMG-CoA reductase inhibitors for the prevention of GVD in cardiac transplant patients.     

白细胞介素-15在心脏移植排斥反应中的表达及意义

目的 探讨白细胞介素-15（IL-15）在心脏移植排斥反应中的表达及其与排斥反应的关系。方法 采用小鼠颈部心脏移植模型，随机分为2组：同基因移植组，供、受体均为C57BL／6小鼠；异基因移植组，供、受体分别为BALB／C、C57BL／6小鼠。以pactin作内参照，分别于术后第1、3、5、7天取移植心脏，用逆转录-聚合酶链式反应（RT—PCR）法观察IL-15的表达情况。结果 随着术后天数的增加，异基因移植组IL-15表达逐渐升高，第5天达高峰（与同基因移植组相比，P〈0．01）。结论 IL-15的表达与心脏移植急性排斥反应的发生发展密切相关，可作为心脏移植急性排斥反应的监测指标，对急性排斥反应的早期诊断和移植物的预后估计具有重要的临床意义。     

Cytokine regulation of chronic cardiac allograft rejection: evidence against a role for Th1 in the disease process.

BACKGROUND: Transient depletion of CD4+ T cells in cardiac allograft recipients prolongs allograft survival; however, grafts exhibit signs of chronic rejection characterized by collagen deposition and neointima development. Although it is believed that Th1 cells promote acute graft rejection, the role of these cells in chronic rejection remains unclear. Hence, our study evaluated whether Th1 cells are associated with the development of chronic cardiac allograft rejection. METHODS: Splenocytes obtained from C57BL/6 recipients bearing BALB/c hearts with signs of chronic rejection were adoptively transferred into C57BL/6 SCID cardiac allograft recipients. As a measure of Th1 function, interferon-y production was determined after restimulation of recipient splenocytes with donor alloantigens. RESULTS: Transfer of splenocytes in SCID allograft recipients resulted in accelerated chronic rejection in the majority of mice. Characterization of these cells before transfer revealed hyporesponsive Th1 function. However, donor-specific proliferative responses and precursor interleukin-2 producing helper and cytotoxic T lymphocyte frequencies were comparable to that of naive splenocytes. Further, splenocytes obtained from SCID recipients with advanced signs of chronic rejection remained deficient in Th1 function, suggesting that Th1 are not involved in this disease process. This possibility was further supported by the development of chronic rejection in IL-12 knockout recipients. Finally, when splenocytes used for adoptive transfer retained Th1 function, transfer of these cells into SCID recipients resulted in acute allograft rejection. CONCLUSIONS: We have established a model in which the mediators of chronic rejection may be further explored. In this system, the absence rather than the presence of donor-reactive Th1 is associated with chronic rejection. These data indicate that Th1-independent effector mechanisms are responsible for chronic rejection in this model.     

HMG-CoA reductase inhibitor cerivastatin prolonged rat cardiac allograft survival by blocking intercellular signals.

BACKGROUND: The development of atherosclerotic cardiovascular complications caused by hyperlipidemia is a common and serious problem for long-term survivors of organ transplantation. However, adhesion molecules such as intercellular adhesion molecule (ICAM)-1 and lymphocyte function-associated antigen (LFA)-1 are involved in allograft rejection, possibly by providing costimulatory signals. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor cerivastatin has been shown to suppress ICAM-1 expression in acute inflammatory responses. METHODS: In this study, we evaluated the immunosuppressive effects of cerivastatin in rat cardiac allografts. The hearts of Fischer rats were transplanted heterotopically into Lewis rats. Cerivastatin (2 mg/kg) was administrated intraperitoneally to recipients for 7 consecutive days from the day before transplantation. RESULTS: Graft survival in the cerivastatin-treated group (n = 8) was significantly longer than in controls (n = 10) (24.6 +/- 2.2 days vs 10.2 +/- 1.3 days, p < 0.05). Mixed lymphocyte reaction (MLR) showed that on Day 8 after grafting, the proliferative response of alloreactive T cells against F344 alloantigen in cerivastatin-treated rats was significantly more suppressed than in Lewis rats. The Interleukin-2 concentration of supernatant in MLR cultures in the cerivastatin-treated group was lower than in the control group. Immunohistochemical analysis showed that the percentage of CD4-positive cells to infiltrating mononuclear cells was less prominent in the cerivastatin-treated group (9.8% +/- 2.2%) than in the control group (20.9% +/- 3.2%). CONCLUSIONS: The HMG-CoA reductase inhibitor cerivastatin effectively suppressed acute graft rejection, possibly by blocking intercellular signals via ICAM/LFA-1, and cerivastatin may be a candidate for treating patients with hyperlipidemia who undergo organ transplantation.     

Detection of an up-regulation of a group of chemokine genes in murine cardiac allograft in the absence of interferon-gamma by means of DNA microarray

BACKGOUND: Interferon (IFN)-gamma and the IFN-gamma-dependent pathway are prominent in vascularized allograft during acute rejection. However, IFN-gamma deficient (IFN-gamma-/-) mice can rapidly reject cardiac allografts. To bring the alternative pathway during allograft rejection into more precise focus, we investigated the gene expression profile in murine cardiac allografts in IFN-gamma-/- mice by means of DNA microarray. MATERIAL AND METHOD: We screened for gene expression changes in murine cardiac allografts of BALB/c H-2d into both wild-type C57BL/6 H-2b (n=3) and IFN-gamma-/- C57BL/6 H-2b(IFN-gamma-/-, n=4) using Affymetrix oligonucleotide arrays to monitor more than 11,000 genes and expressed sequence tag (ESTs). The heart was heterotopically transplanted. Transplanted hearts were harvested on day 5. As a control, isografts (C57BL/6 to C57BL/6) were also harvested on day 5. RESULTS: On day 5, 64 of the 84 genes induced in the allografts in wild-type mice were not up-regulated in IFN-gamma-/- mice. We identified a group of 54 genes that were up-regulated in allografts in IFN-gamma-/- mice. Several chemokine genes, including monocyte chemoattractant protein=1 and macrophage inflammatory protein, were induced in the allografts in both wild-type and IFN-gamma-/- mice. Interestingly, a group of genes, including C10-like chemokine and platelet factor 4, were specifically induced in the IFN-gamma-/- mice. CONCLUSION: DNA microarray analysis reveals a unique pattern of mRNA expression in allografts in IFN-gamma-/- mice as well as a group of genes induced in cardiac allografts in both wild-type and IFN-gamma-/- mice, including monocyte chemoattractant protein-1 and monocyte chemoattractant protein-1.     

Role of CXCR3 and CCR5 in allograft rejection

Chemokines are known to participate in allograft rejection by mediating leukocyte trafficking. Despite redundancy in chemokine family, several chemokine-chemokine receptor interactions have proven critical in alloimmune responses. We sought to determine the effect of combined blockade of CXCR3 and CCR5, two critical chemokine receptors, in acute rejection. METHODS: Heterotopic heart transplantation was performed using BALB/c to B6/129 mice deficient in CCR5. Following transplantation these mice were treated with goat anti-CXCR3 serum every other day. In the control group, BALB/c hearts were transplanted in wild type B6/129 recipients and treated with goat serum alone. No immunosuppression was given to either group. Recipient mice were then assessed daily for allograft function by abdominal palpation, and graft survival was confirmed by laparotomy. RESULTS: The donor hearts in the control group were rejected at 6 +/- 1 days posttransplantation. Combined blockade of CXCR3 and CCR5 prolonged allograft survival versus control; all allografts survived to 24 days. In addition, there was a decrease in graft infiltrating CD4 and CD8 lymphocytes in the experimental group at 24 days. CONCLUSION: Combined CXCR3 and CCR5 blockade is effective in prolonging allograft survival in a fully MHC mismatched murine model. Combined chemokine blockade holds promise in control of acute rejection in organ transplantation.     

Acute rejection and cardiac graft vasculopathy in the absence of donor-derived ICAM-1 or P-selectin.

BACKGROUND: ICAM-1 and P-selectin are molecules that facilitate adhesion of circulating leukocytes to vessel walls. We have investigated the role of donor-derived ICAM-1 and P-selectin in acute and chronic cardiac allograft rejection. METHODS: C57BL/6J (H-2(b)) mice were used as donors for heterotopic heart transplantation into CBA/Ca (H-2(k)) recipients. The donors were wild-type or homozygous for gene mutations of ICAM-1 or P-selectin. We measured acute rejection in non-immunosuppressed recipients by daily palpation and sacrificed mice at Days 2, 4, and 6 for immunohistochemical analysis. For chronic rejection, recipients received monoclonal antibody against CD4+ T cells. We removed hearts at Days 60 to 62 for histologic assessment of vasculopathy using quantitative morphometry to measure intimal thickening. RESULTS: Time (days) to rejection was 7.1 +/- 0.57 for wild-type (n = 10), 7.0 +/- 0.71 for ICAM-1 -/- (not significantly different, n = 7) and 6.1 +/- 0.33 (p = 0.001) for P-selectin -/- donors. ICAM-1 deficiency was associated with delayed infiltrate at Day 4 compared with wild-type. In the model of chronic rejection, elastin-positive vessels showed a mean occlusion of 34% +/- 3% in transplanted wild-type hearts; vessels were divided into those showing 0% to 20%, 20% to 50%, and 50% to 100% occlusion. We observed no difference in the number of affected vessels or the amount of vascular thickening in donors lacking ICAM-1 or P-selectin compared with wild-type controls. CONCLUSIONS: The absence of ICAM-1 or P-selectin in donor tissues neither lengthens the time of allograft survival nor inhibits the vascular lesions associated with chronic rejection. Indeed, the absence of P-selectin may exacerbate alloimmune injury.     

Prevention of acute vascular rejection by a functionally blocking anti-C5 monoclonal antibody combined with cyclosporine

BACKGROUND: Inhibition of the complement cascade at C5 prevents formation of pro-inflammatory molecules C5a and C5b-9, which play a key role in allograft rejection. The present study was undertaken to determine whether blocking terminal complement with anti-C5 monoclonal antibody (mAb) alone or combined with cyclosporine (CsA) would prevent acute vascular rejection (AVR) in a mouse cardiac allograft model. METHODS: C3H mouse hearts were transplanted into BALB/c mice and randomized into five groups with the following treatments: (1) no treatment; (2) CsA alone; (3) control mAb; (4) anti-C5 mAb alone; and (5) anti-C5 mAb and CsA. RESULTS: Allografts in untreated or control mAb-treated recipients were rapidly rejected at 8.0+/-0.6 and 8.2+/-0.8 days, respectively. These grafts exhibited typical AVR, characterized by vasculitis, hemorrhage, and thrombosis. A high level of complement activity was also demonstrated in these animals. High-dose CsA was not able to inhibit complement activation or AVR, and grafts were rejected in 15.5+/-1.1 days. Anti-C5 monotherapy completely inhibited complement activation and attenuated AVR, but grafts were rejected in 8.3+/-0.5 days by acute cellular rejection. In contrast, a combination of anti-C5 mAb and CsA successfully achieved indefinite graft survival (>100 days). This combined therapy completely inhibited terminal complement activation and prevented both humoral- and cellular-mediated rejection. CONCLUSIONS: Combination therapy of anti-C5 mAb and CsA achieves indefinite graft survival in a mouse cardiac allograft model. These data suggest that inhibition of terminal complement using anti-C5 mAb may be an effective therapeutic adjunct to prevent AVR in clinical transplantation.     

槐耳清膏在小鼠心脏移植排斥反应中作用的初步探讨

目的 探讨槐耳清膏在小鼠心脏移植急性排斥反应中的作用.方法 实验分为3组:A组:同种异基因移植后槐耳清膏处理组(槐耳清膏组);B组:同种异基因移植财照组(移植排斥组)及C组:同系移植对照组(同系移植组).观察各组移植心脏的存活时间、术后第5天供心的组织病理改变.用免疫荧光检测移植心脏中CD8+T淋巴细胞的浸润和颗粒酶B的表达水平.结果 A组移植心脏的平均存活时间为(6.38±0.69)d,与B组(8.31±0.59)d相比明显缩短(P<0.01);心肌组织呈3级急性排斥反应病理改变,CD8+T淋巴细胞弥漫性浸润及颗粒酶B表达与两个对照组相比明显增强(P<0.05).结论 在术后早期单用槐耳清音会促进小鼠心脏移植物的急性排斥反应,可能机制足促进CD8+T淋巴细胞的组织浸润并增强颗粒酶B的表达.     

Function of the vascular endothelial growth factor receptors Flt-1 and Flk-1/KDR in the alloimmune response in vivo

BACKGROUND: We have recently reported that vascular endothelial growth factor (VEGF) functions as a proinflammatory cytokine to regulate the trafficking of leukocytes into allografts in the early posttransplant period. VEGF binds two major VEGF receptors: VEGFR-1 (flt-1) and VEGFR-2 (flk-1/KDR). Here, we wished to investigate the expression and function of VEGF receptors in the process of acute allograft rejection in vivo. METHODS: We performed fully MHC-mismatched C57BL/6 (H-2b) into BALB/c (H-2d) vascularized heterotopic murine cardiac transplants and we examined the expression of VEGF and VEGF receptors by immunohistochemistry during acute allograft rejection. Next, we treated mice with specific neutralizing monoclonal antibodies against murine VEGFR-1 and VEGFR-2 and examined their effect on the development of acute allograft rejection by histology and by analysis of graft survival. The intragraft expression of cytokines and chemokines were also evaluated by quantitative real-time PCR analysis. RESULTS: The expression of VEGF, VEGFR-1 and VEGFR-2 were significantly up-regulated during allograft rejection as compared to isografts. Administration of either anti-VEGFR-1 or anti-VEGFR-2 alone failed to inhibit allograft rejection. However, coadministration of both antibodies together inhibited leukocyte infiltration of allografts and prolonged allograft survival. Furthermore, the effect of VEGFR blockade was associated with the downregulation of intragraft cytokine and chemokine expression. CONCLUSIONS: Our data suggest that VEGF-VEGFR interactions function in the alloimmune response in vivo. Targeting VEGFRs may represent a novel therapy to protect allografts following clinical transplantation.