Caspase抑制剂对小鼠心脏移植物细胞凋亡的影响

目的　探讨Caspase抑制剂对同种异体心脏移植物细胞凋亡的影响。方法　以BALB/c小鼠为供者 ,C5 7BL/6J小鼠为受者建立异位 (颈部 )心脏移植模型 ,治疗组受者术中、术后分别给Caspase抑制剂 (Z Asp cmk) 0 .2 5mg ,对照组受者相应时间给等量的溶媒。术后观察移植心脏的存活时间 ,术后 5d处死部分受者 ,切取移植心及受者自身心脏组织 ,检测心脏组织中Caspase酶的活性及心肌细胞凋亡情况。结果　对照组移植心脏的中位存活时间为 7d ,治疗组为 13d ,二者比较 ,差异有高度显著性 (P <0 .0 1) ;移植心脏组织的Caspase 3活性 ,对照组为 (310± 83)nmolAFC·min-1·mg-1,治疗组为 (6 5± 19)nmolAFC·min-1·mg-1,受者自身心脏为 (47± 11)nmolAFC·min-1·mg-1,治疗组与受者自身心脏比较 ,差异无显著性 (P >0 .0 5 ) ,与对照组比较 ,差异有高度显著性 (P <0 .0 1) ;治疗组与对照组心肌细胞的凋亡指数分别为 7.95± 1.71及 0 .5 6± 0 .2 0 ,二者比较 ,差异有显著性 (P <0 .0 5 )。结论　Caspase抑制剂能够有效抑制小鼠心脏移植物的心肌细胞凋亡。     

Diagnosis and treatment of acute cardiac allograft rejection.

Integration of data derived from immunologic monitoring techniques and endomyocardial biopsy currently permits more precise administration of immunosuppressive medications for the treatment of acute cardiac allograft rejection than was formerly possible, resulting in a substantially improved outlook for long-term survival. Indeed, the probability of survival for 5 years postoperatively of 50% exceeds that for several categories of cardiac patients currently undergoing other more common forms of heart surgery. The continuing demonstration of the potential for cardiac transplantation clearly warrants further application of this procedure for the treatment of appropriate patients with end-stage cardiac disease.     

白细胞介素10基因转染抑制小鼠心脏移植排斥反应的实验研究

目的　探讨白细胞介素 1 0 (IL 1 0 )基因转染对小鼠心脏移植排斥反应的抑制作用。方法　采用小鼠颈部心脏移植模型。随机将心脏移植后的小鼠分为 4组 :(1 )对照组 :心脏移植后每天用生理盐水 1ml灌胃 ;(2 )环孢素A(CsA)组 :心脏移植后每天用CsA 5mg/kg 灌胃 ;(3)IL 1 0组 :心脏移植时用IL 1 0重组腺病毒 30 0 μl(腺病毒滴度为 5× 1 0 1 1 pfu/ml)经主动脉根部灌注小鼠供心。(4)IL 1 0 CsA半剂量组 :在IL 1 0组的基础上 ,每天用CsA 2 .5mg/kg灌胃。观察移植心脏的存活时间及心脏跳动情况。结果　IL 1 0组、IL 1 0 CsA半剂量组和CsA组移植心脏存活时间均较对照组显著延长 (P <0 .0 1 ) ;IL 1 0组移植心脏存活时间较CsA组明显延长 (P <0 .0 5 ) ;IL 1 0 CsA半剂量组移植心脏存活时间最长 ,优于IL 1 0组 (P <0 .0 5 )和CsA组 (P <0 .0 1 )。结论　IL 1 0基因转染对心脏移植排斥反应有较强的免疫抑制作用 ,可明显延长移植心脏的存活时间 ,并且与CsA有协同作用 ,共同应用时 ,可减少CsA的用量。     

Edema treatment during cardiac allograft rejection

BACKGROUND: Interstitial edema of rejecting organs can be correlated with the accumulation of hyaluronan in the transplant; since hyaluronan has strong water-binding capacity, treatment with the hyaluronan-degrading enzyme hyaluronidase reduces not only the hyaluronan content but also the water content of the graft. The aim of the present study was to investigate whether a further reduction of the water content would be the result if hyaluronidase was used in conjunction with classic diuretic substances. METHODS: Five days after heterotopic heart transplantation (PVG to Wistar/Kyoto), recipient rats received hyaluronidase as a continuous intravenous infusion over 2 hours together with either a loop-diuretic (furosemide) or an osmotic diuretic (mannitol). RESULTS: Hyaluronidase was found to reduce the hyaluronan contents of the grafts from 586+/-52 microg/g in control animals receiving vehicle infusion to 161+/-48 microg/g (p < 0.001) and the water contents from 81.3+/-0.4 x 10(-2) U to 79.7+/-0.4 x 10(-2) U (p < 0.05). Combined treatment with furosemide or mannitol did not affect the results and neither furosemide nor mannitol had any intrinsic capacity to affect the water or hyaluronan contents of the cardiac grafts. CONCLUSION: This experiment confirms our previous findings of hyaluronidase as an effective edema-reducing drug and indicate that no additive effect is obtained by a combined therapy with diuretics and hyaluronidase.     

Innate immunity and cardiac allograft rejection

The development of immunosuppressive drugs to control adaptive immune responses has led to the success of heart transplantation as a therapy for end-stage heart failure. However, these agents are largely ineffective in suppressing components of the innate immune system. This distinction has gained clinical significance as mounting evidence now indicates that innate immune responses have important roles in the acute and chronic rejection of cardiac allografts including cardiac allograft vasculopathy (CAV). Whereas clinical interest in natural killer (NK) cells was once largely confined to the field of bone marrow transplantation, recent findings suggest that these cells can also participate in the acute rejection of cardiac allografts and in the development of CAV. Stimulation of Toll-like receptors (TLRs), another important component of innate immunity, by endogenous ligands released in response to ischemia/reperfusion is now known to cause an inflammatory milieu favorable to graft rejection. Finally, new data indicate that activation of complement is linked to acute rejection and CAV. In summary, the conventional wisdom that the innate immune system is of little importance in whole-organ transplantation is no longer tenable. The addition of strategies that target TLRs, NK cells, and complement will be necessary to prevent CAV completely and to eventually achieve long-term tolerance to cardiac allografts.     

低分子肝素减轻大鼠移植心脏排斥反应的作用及其机制

目的 探讨低分子肝素对大鼠移植心脏急性和慢性排斥反应的影响及其机制.方法 以SD大鼠为供者,Wistar大鼠为受者,进行异位(腹部)心脏移植.将受者随机分为急性排斥反应组(简称"急排组")和慢性排斥反应组(简称"慢排组").急排组中,15只于移植当天开始皮下注射低分子肝素200 μg穔g-1穌-1(小剂量者),直至移植心脏停搏;15只皮下注射低分子肝素2000 μg穔g-1穌-1(大剂量者),用药时间同前;以不给低分子肝素者作对照.慢排组所有受者均于移植当天至移植术后第9天腹腔注射环孢素A 5 mg·kg-1·d-1,其中10只还于移植当天至移植后第90天皮下注射低分子肝素2000 μg穔g-1穌-1,10只注射低分子肝素的同时再皮下注射左旋精氨酸甲酯(L-NAME)10mg·kg-1·d-1,以不给低分子肝素和L-NAME者作对照.移植后第5天,处死急排组部分受者,切取移植心脏,根据Stanford标准进行移植物排斥反应的病理学诊断和分级;剩余受者观察移植心脏存活时间.移植后第90天,测定慢排组受者的血NO浓度和移植心脏组织中诱生型NO合酶(iNOS)mRNA表达强度,并行心脏移植物血管病(CAV)评分.结果 急排组中,对照者、小剂量者和大剂量者的排斥反应等级评分分别为(4.20±0.45)分、(3.60±0.55)分和(2.40±0.55)分,移植心脏存活时问分别为(7.30±1.49)d、(8.20±1.47)d和(9.20±1.23)d,大剂量者的排斥反应等级评分明显低于对照者和小剂量者,移植心脏存活时间明显长于对照者和小剂量者(P＜0.05).慢排组中,仅给予低分子肝素者的血NO浓度和iNOS mRNA表达强度明显高于对照者和加用L-NAME者,而其CAV评分明显低于对照者和加用L-NAME者,差异均有统计学意义(P＜0.01).结论 低分子肝素可减轻急、慢性排斥反应程度,延长移植心脏存活时间;其抑制CAV的作用可能是通过上调iNOS mRNA表达水平,进而增加NO的释放来实现的.     

The treatment of advanced cardiac allograft rejection

Severe cardiac allograft rejection remains a serious problem despite the advances of cyclosporine-based immunosuppression. This study analyzes our experience with 202 recipients of cardiac allografts who were treated primarily with cyclosporine and prednisone. Failure of such therapy in 86 patients (43%) resulted in 105 episodes of advanced cardiac allograft rejection as diagnosed by endomyocardial biopsy. Of 101 rejection episodes that were initially treated with intravenous pulse therapy, 48 (48%) were successfully resolved, yet 60% of these successes were associated with major infections. Patients in whom steroid therapy failed or was contra-indicated received intravenous antithymocyte globulin (ATG) or intravenous monoclonal antibody (OKT3). ATG and OKT3 successfully reversed severe rejection in 26 (81%) of 32 and in 13 (93%) of 14 episodes, respectively. Infectious complication rates were 54% and 21%, respectively. Because the majority (87%) of these rejection episodes occurred within the first 30 days after treatment, many of them may have resulted from inadequate immunosuppressive induction therapy. Based on our results, we believe that advanced cardiac allograft rejection may be managed best by individualizing immunosuppressive therapy, thus enhancing prevention, and by adding OKT3 to the regimen when rejection occurs.     

Noninvasive monitoring of human cardiac allograft rejection

The frequency of donor-reactive cytolytic T lymphocytes was measured in the peripheral blood mononuclear cell population of a group of 12 cardiac allograft recipients immediately before and at various time points after transplantation. At each of the time points after transplantation the donor heart was biopsied and the rejection status of the graft was determined by applying standard histological criteria. The results of this study showed that the preoperative frequency of donor-reactive cytolytic T lymphocytes in the blood was not predictive of a future tendency toward graft rejection. However, when all the data were examined it was apparent that the frequency of donor-reactive cytolytic T lymphocytes was significantly higher (P less than 0.05) in blood samples from patients whose simultaneous biopsy showed histological evidence of acute cardiac allograft rejection than in blood samples from transplant patients showing no evidence of rejection.     

Use of epicardial electrocardiograms for detecting cardiac allograft rejection.

Since the advent of cyclosporin A surface electrocardiograms have been unreliable for diagnosing cardiac allograft rejection. Although several noninvasive methods have been proposed, none have been sufficiently accurate to be considered for clinical use. We have studied the use of the QRS complex amplitude, the unipolar peak-to-peak amplitude, recorded from intramyocardial electrodes for detecting rejection. Ten adult mongrel dogs underwent placement of intramyocardial electrodes on each ventricle. After stabilization of signals the hearts were transplanted heterotopically into unmatched recipients receiving cyclosporin A, azathioprine and methylprednisolone. Endomyocardial biopsies were performed after stabilization of unipolar peak-to-peak amplitude, twice weekly thereafter, and when unipolar peak-to-peak amplitude fell significantly. This detected 13 of 14 episodes of rejection. There was one false-positive and one false-negative result. The false-negative study became positive the following day. Thus, analysis of unipolar peak-to-peak amplitude detected all episodes of rejection in a clinically relevant time frame and was able to detect mild forms of rejection and multiple episodes of rejection in the same heart even in the presence of therapeutic levels of cyclosporin A.     

Molecular mechanism of contractile dysfunction in cardiac allograft rejection.

Alterations in the beta-adrenergic receptor adenylyl cyclase pathway are well known in heart failure. To determine if an alteration in this pathway occurs during the reversible phase of cardiac allograft rejection, we used a rat heterotopic heart transplant model. Lewis rats received either isografts or Lewis Brown Norway allografts. Cardiac grafts and native hearts were explanted 4, 5, or 6 days later. Receptor-mediated modulation of adenylyl cyclase activity was investigated using isoproterenol, forskolin, and the muscarinic and adenosine receptor agonists carbachol and R-N6-(C2-phenyl-isopropyl)-adenosine (R-PIA), respectively. Allografts demonstrated evidence of histological rejection and a significantly impaired response to forskolin and isoproterenol on all days: [table: see text] (% increase in cAMP in response to forskolin or isoproterenol +/- standard error. All results P less than 0.03 except Day 4 forskolin and Day 5 isoproterenol.) No significant difference was noted between isografts and allografts stimulated with carbachol and R-PIA. These data suggest that a primary alteration in adenylyl cyclase activity may be a component of the molecular basis of reversible contractile dysfunction in cardiac allograft rejection.     

Mycophenolic acid concentrations are associated with cardiac allograft rejection.

BACKGROUND: Mycophenolate mofetil (MMF) therapy decreases the incidence of allograft rejection following solid-organ transplantation. Current dosing strategies of MMF are not routinely adjusted based on mycophenolic acid (MPA) area under the concentration-time curve (AUC), MPA trough, or free MPA (fMPA) AUC values. METHODS: To determine the clinical significance of MPA concentrations following orthotopic heart transplantation (OHT), we measured pre-dose MPA trough, MPA free fraction, an estimated MPA AUC using an abbreviated sampling schedule, and fMPA AUC in 38 consecutive patients. We measured MPA concentrations using a validated high-performance liquid chromatography method and graded endomyocardial biopsies based on the International Society for Heart and Lung Transplantation (ISHLT) grading system. RESULTS: The MPA values for the study group were as follows: MPA trough of 1.2 +/- 0.6 microg/ml; MPA free fraction of 1.9 +/- 0.4%; MPA AUC of 44.5 +/- 16. 1 microg/hour/ml; and fMPA AUC of 0.83 +/- 0.30 microg/hour/ml. We compared patients with Grade 0 (n = 22), Grade 1 (n = 13), or Grade 2/3 (n = 3). The MPA AUC values were lower in patients with Grade 2/3 than in patients with Grade 0 (26.1 +/- 6.6 vs 42.8 +/- 14.0 microg/hour/ml, p < 0.08) or Grade 1 rejection (26.1 +/- 6.6 vs 51.7 +/- 17.5 microg/hour/ml, p < 0.05). The fMPA AUC values were lower in patients with Grade 2/3 than with patients with Grade 0 (0.49 +/- 0.11 vs 0.81 +/- 0.25 microg/hour/ml, p < 0.05) or Grade 1 (0.49 +/- 0.25 vs 0.95 +/- 0.34 microg/hour/ml, p < 0.05) rejection. We noted a trend in MPA trough concentrations between patients with Grade 2/3 vs 0 (0.65 +/- 0.15 vs 1.20 +/- 0.58 microg/ml, p = 0.15) and Grade 1 (0.65 +/- 0.15 vs 1.24 +/- 0.72 microg/ml, p = 0.14) rejection. CONCLUSION: These preliminary results suggest that lower MPA AUC and fMPA AUC values are associated with cardiac allograft rejection in heart transplant recipients. Individualizing MMF dosing based on MPA determinations may minimize the risk of rejection following OHT.     

Noninvasive detection of cardiac allograft rejection by prospective telemetric monitoring.

A method for cardiac allograft surveillance that is less invasive than endomyocardial biopsy is needed. A fall in the unipolar peak-to-peak amplitude recorded from cardiac allografts has been shown to detect rejection when retrospectively compared with endomyocardial biopsy. This study was performed to assess the sensitivity and specificity of prospective telemetric unipolar peak-to-peak amplitude surveillance in detecting rejection of heterotopic canine cardiac allografts occurring through triple drug immunosuppression. Native heart and graft amplitudes were telemetrically acquired on a daily basis. A fall in normalized unipolar peak-to-peak graft amplitude to less than 85% was used as an indication for biopsy. A quantitative rejection score was calculated for each endomyocardial biopsy (rejection score greater than 0.66 = histologic rejection). Rejection was documented in all animals. Thirty-six biopsies were performed (10 control biopsies and 26 amplitude-directed biopsies); 25 of the 36 demonstrated rejection. Sensitivity and specificity were 88% and 91%, respectively. A linear correlation between unipolar peak-to-peak amplitude and rejection severity was seen (R = 0.87, p less than 0.001). The first true positive amplitude was associated with mild-to-moderate rejection (rejection score = 1.63 +/- 0.45). Unipolar peak-to-peak amplitude recorded from native hearts remained stable during allograft rejection. It is concluded that prospective, telemetric cardiac allograft surveillance can accurately detect rejection occurring through ongoing immunosuppression.     

Evidence of mitochondrial impairment during cardiac allograft rejection

NADH laser fluorimetry and mitochondrial oxigraphy were used to study myocardial oxidative energy metabolism during cardiac allograft rejection. Heterotopic cardiac transplantation was performed on Lewis rats; allografts (with Fischer rat donors) were compared with isografts (with Lewis rat donors). In vivo and in vitro assays were performed six days after transplantation. Myocardial NADH fluorescence was recorded in vivo from grafted hearts, at baseline; during brief, complete ischemia; and during reperfusion. Oxygen consumption of mitochondria isolated from both native and grafted hearts was determined. Neither baseline levels nor maximum ischemic levels of NADH fluorescence (F0 = k[NADH]) were found to be significantly different between allografts (0.45 +/- 0.05 to 0.87 +/- 0.10) and isografts (0.45 +/- 0.04 to 1.11 +/- 0.05). During recovery, the rate of fluorescence decrease was significantly lower in allografts than in isografts (0.024 +/- 0.001 vs. 0.038 +/- 0.002 delta F0.s-1, P less than 10(-3], indicating a lower rate of NADH reoxidation. In the presence of malate and glutamate substrates, mitochondrial O2 consumption was significantly lower in allografts than in isografts (30 +/- 9 vs. 100 +/- 15 nanoatoms O2. min-1.mg prot-1, P less than 10(-2]. These results indicate that mitochondrial oxidative metabolism was impaired during the rejection process. Such energy production disturbances may contribute to the dysfunction of rejecting hearts.