Telomerase activity in rat liver allografts

BACKGROUND: Telomerase activity in grafts may be involved in the alteration of cellular senescence after transplantation or its relevant immunological events. METHODS: At the age of 20 weeks, donor livers harvested from DA (RT1a) were orthotopically transplanted into PVG (RT1c) or LEW (RT1(1)) rats. Rats having undergone orthotopic liver transplantation (OLT; DA-PVG) naturally overcome rejection, whereas all OLT (DA-LEW) rats die from acute rejection within 14 days. Telomerase activity in liver allografts was measured at various intervals post OLT. RESULTS: At day 7 when the most severe rejection episode was observed in OLT (DA-LEW) and OLT (DA-PVG), the telomerase activity was significantly higher than in syngeneic OLT (DA-DA) rats, in which no rejection occurred. Telomerase activity in tolerogenic OLT (DA-PVG) livers remained elevated for at least 2 months. CONCLUSION: These results suggest that telomerase activity in allogeneic OLT livers may reflect regenerating hepatocytes or activation of lymphocytes and/or hematopoietic stem cells associated with rejection or tolerance.     

A study of tolerance induced by liver transplantation on intestinal graft in the rat]

In some strain combinations of rats, orthotopic liver transplantation (OLT) permits long-term donor-specific survival of fully allogeneic kidney, heart or skin grafts. The difficulties encountered in the clinical situation to obtain tolerance of small-bowel transplantation (SBT), in spite of massive non-specific immunosuppression, led us to study possible liver-induced tolerance in SBT. Inbred DA (RTIa) and PVG (RT1c) rats were used respectively as donors and recipients and divided in two groups: group 1: SIT alone (n = 6); group 2: combined OLT/SBT (n = 6). SIT was performed 17 days after OLT. No immunosuppressive treatment was given to the recipients. Biopsies of small-bowel grafts were performed in both groups at various times after small bowel engraftment. All animals in group 1 showed evidence of acute rejection of the graft between days 6 and 9 post-graft. The histologic pattern of rejection associated lamina propria (LP) mononuclear cell infiltration, crypt lesions and villous atrophy at the end-point of rejection. In group 2, long-term survival (> 100 days) of small bowel grafts was achieved in five of the six animals in spite of strong mononuclear cell infiltration in the LP, which peaked two months after small bowel grafting but then disappeared partially. This striking mononuclear cell infiltrate contrasted with only minor epithelial damage. These data demonstrate that liver grafting can enhance the survival of a small-bowel graft from the same donor in a rat model. Histological findings show that an intense immunological reaction takes place within liver-induced tolerated small-bowel grafts.     

Nitric oxide inhibition and consecutive Aspisol application show a prolonged survival of orthotopic transplanted livers in a rat model

BACKGROUND: It is generally accepted that nitric oxide (NO) plays a crucial role in acute rejection caused by inflammatory responses. Therefore, the purpose of this study was to investigate the effect on survival following arterialized orthotopic rat liver transplantations (o-RLTx) of NO inhibition and consequent blockade of platelet aggregation by application of Aspisol. MATERIALS AND METHODS: Inbred LEWIS-(RT(1)) rats underwent arterialized o-RLTx under ether anesthesia with DA-(RT1av1) rats as organ donors. After liver transplantation, serum parameters were determined and hepatic biopsy specimens were sampled on postoperative days 5, 8, 10, 30, and 90. Sixty-one rats were divided into 5 groups: syngenic controls (group I, n = 12); allogenic controls (group II, n = 11); allogenic with FK506 immunosuppression (group III, n = 12); allogenic with AGH-treatment (group IV, n = 13); and allogenic with AGH/low- dose Aspisol treatment for 5 days after liver transplantation (group V, n = 13) (Bayer, Leverkusen, Germany). RESULTS: Rats of group V with AGH/low-dose Aspisol treatment showed significantly longer graft survival (18.2 days +/- 1.8 days) compared with group II rats with untreated grafts (11.3 days +/- 1.7 days) the allogenic group IV with AGH treatment (11.2 days +/- 1.8 days; P < .05). Histological examination revealed moderate graft rejection among the AGH-treated group IV; however, marked platelet aggregation in sinusoids was present, which was not observed in the AGH/low-dose Aspisol-treated animals (group V). CONCLUSION: Our data suggested that simultaneous treatment with AGH/low-dose Aspisol leads to a significant increase in survival and inhibition of platelet aggregation in the graft after orthotopic liver transplantation.     

Identification of two down-regulated genes in rat liver allografts by mRNA differential display

Total RNA differential display (DD) using random primers was performed for rat orthotopic liver transplantation (OLT) models. DA (RT1^a) donor livers were transplanted into DA, PVG (RT1^c), and LEW (RT1^l) recipients: (1) syngeneic OLT (DA-DA): no rejection occurs; (2) allogeneic OLT (DA-PVG): rejection occurs, but is naturally overcome without immunosuppression; (3) allogeneic OLT (DA-LEW): animals die of acute rejection within 14 days. cDNA was isolated from selected bands, re-amplified for sequencing, and confirmed by Northern blots. Two down-regulated genes were observed in day-7 allogeneic OLT livers (DA-PVG, DA-LEW), while they were consistently expressed in day-7 syngeneic OLT (DA-DA) livers. These two genes were identified as α-glutathione sulfotransferase (α-GST) Ya gene and estrogen sulfotransferase (EST), respectively. Northern blots confirmed that their expression was down-regulated in OLT (DA-PVG) livers on days 7–26 and gradually restored. The mRNA expression of GST and EST may be good markers to predict rejection or induction of tolerance. Received: 14 December 1999 Revised: 28 September 2000 Accepted: 16 March 2001     

Moderate hypothermia prevents cerebral hyperemia and increase in intracranial pressure in patients undergoing liver transplantation for acute liver failure

BACKGROUND: During orthotopic liver transplantation (OLT) for acute liver failure (ALF), some patients develop acute increases in intracranial pressure (ICP). The authors tested the hypothesis that increases in ICP during OLT for ALF can be prevented by moderate hypothermia. METHODS: Sixteen patients with ALF undergoing OLT were studied. Depending on the measured ICP before OLT, the patients were divided into three groups as follows: group I (n=6), did not require treatment for increased ICP (ICP <15 mm Hg); group II (n=5), had episodes of increased ICP that were controlled by conventional treatment (group I and group II patients were maintained normothermic during OLT); and group III (n=5), had uncontrolled increased ICP before OLT for which they had been cooled and underwent OLT with the median core temperature of 33.4 degrees C (92.1 degrees F) (range, 31.9 degrees -33.8 degrees C [89.4 degrees -92.8 degrees F]) RESULTS: There was a significant increase in ICP during the dissection and reperfusion phases in the patients in groups I and II (P=0.004 and P=0.006, respectively). Patients in group III had no significant increase in ICP during the OLT. The increase in ICP in groups I and II was associated with an increase in cerebral blood flow, which was not observed in group III. The increase in ICP was corrected during the anhepatic phase of the operation. There was no difference in the requirement of transfusions or incidence of postoperative infection between the groups. CONCLUSIONS: Moderate hypothermia is safe and successfully prevents increases in ICP during OLT for ALF.     

Advantages of promoting interleukin-10 by silence of histone deacetylase 11 in inducing tolerance in orthotopic liver transplantation in rats

Aims

The aims of this study were to study the role of histone deacetylase 11 (HDAC11) in tolerance induction in orthotopic liver transplantation (OLT) in rats and to assess the advantages of gene therapy over the immunosuppressant FK506.

Methods

Recipients were assigned to an acute rejection group (AcR; group I), an FK506 intervention group (group II), and a tolerance group (group III). Acute rejection (AcR) was graded by the Banff scheme and we examined postoperative survival. The messenger RNA (mRNA) and protein expressions of histone deacetylase 11 (HDAC11) and interleukin (IL) 10 in liver tissue were detected using real-time polymerase chain reaction (PCR) and Western blots, respectively. Plasma levels of tumor necrosis factor (TNF)-α, IL-2, and IL-10 were measured using enzyme-linked immunosorbent Assays.

Results

Group I displayed severe, Group II had less, and Group III had no evidence of AR. The survivals among Group III were longer than those in Group I and Group II. IL-10 expression was promoted by HDAC11-shRNA at 7 days after OLT. Serum IL-2 and TNF-α levels were significantly lower among Group III compared with Groups I and II, whereas IL-10 showed the opposite result.

Conclusions

Silence of HDAC11 promotes IL-10 expression and leads to tolerance following OLT in rats. Thus HDAC11 is a promising target for gene therapy to induce tolerance with advantages over immunosuppressive drugs.     

Involvement of autoimmunity against nuclear histone H1 in liver transplantation tolerance

BACKGROUND: Our recent studies suggested that anti-histone H1 autoantibody (auto-Ab) plays an important role in experimental and clinical liver allograft tolerance as a natural immunosuppressive factor. The present study aimed to explore how the autoimmune response against histone H1 is involved in tolerance induction. METHODS: The measurement of anti-histone H1 auto-Ab and immunohistochemical analysis were performed in serum and liver allografts after orthotopic liver transplantation (OLT). To compare the auto-Ab response against histone H1 between the recipients of rejector (DA-LEW) and tolerogenic (DA-PVG) OLT models, na?ve recipients were immunized with calf thymus histone H1. The immunosuppressive state of histone H1-immunized rats was assayed by mixed lymphocyte reaction (MLR). RESULTS: Anti-histone H1 Ab titer was transiently increased during the rejection phase after OLT (days 7-21) in the DA-PVG combination, while no such response was confirmed in the DA-LEW acute rejection model. Nuclear histone H1 antigens were found in the cytoplasm and the extracellular environment in liver allografts at the rejection phase in the tolerogenic model but not in the rejector model, resulting from the transient induction of anti-histone H1 auto-Ab in recipient PVG rats after OLT. Low dose and short-term immunization with histone H1 upregulated the anti-histone H1 Ab titer in na?ve PVG rats, which exhibited a low allogeneic immune response, while no such response was found in na?ve LEW rats. CONCLUSIONS: These results suggest that the sensitivity to nuclear antigens such as histone H1 may be a key factor determining the acceptance or rejection of donor liver grafts, at least in DA-PVG and DA-LEW combinations.     

Immunosuppressive activity of serum from liver-grafted rats. Passive enhancement of fully allogeneic heart grafts and induction of systemic tolerance

Immunological enhancement of allogeneic heart graft survival by serum from rats tolerized by liver grafting has been studied. Serum taken from long-term-surviving PVG rats carrying orthotopic DA liver transplants (OLT serum) was able to increase the survival time of PVG.RT1a heterotopic heart grafts in PVG recipients. Administration of 1 ml of OLT serum at the time of heart grafting led to permanent survival of the grafts in all animals. The recipients became systemically tolerant of RT1a and several weeks later were able to accept permanently skin grafts from the same donor strain, while rejecting third-party grafts. Enhancement appeared to be mediated initially by IgG antibodies in the OLT serum against class II donor RT1a antigens; significant enhancement was produced by as little as 100 micrograms of antibody. Recipient alloantibody responses following enhancement were studied and showed selective suppression of the anti-class-I (RT1Aa) antibody levels, while the anti-class-II antibody response was apparently unaffected. The implications of these results for mechanisms of unresponsiveness following enhancement and liver transplantation are discussed.     

Relationship Between Ischemia/Reperfusion Injury and Acute Rejection of Allogeneic Liver Transplant in Rats

Objective

This study aimed to investigate the relationship between the severity of ischemia/reperfusion (I/R) injury and the acute rejection (AR) of allogeneic liver transplants in rats.

Methods

The experimental rats were divided in different groups: normal control group (sham group, group I); syngeneic liver transplant control group (similar gene group, group II); and allogeneic liver transplant groups (groups III to VI). The rats were humanely killed at 1, 3, 5, and 7 days after transplantation or sham operation to determine the severity of I/R injury, rejection classification, and hepatocyte apoptosis. Messenger RNA (mRNA) and protein expression levels of Fas, perforin, and granzyme B were assessed in the liver tissues using real-time polymerase chain reaction and immunohistochemistry, respectively.

Results

The rejection scores of the transplanted liver tissues gradually increased until these scores were proportional to the severity of I/R injury in groups III, IV, and V. The maximum scores were reached at 7 days after transplantation as the duration of transplantation was extended. The mRNA and protein expression levels of Fas, perforin, and granzyme B were significantly increased at 1, 3, 3, 5, and 7 days after liver reperfusion in groups III, IV, and V compared with those in groups I, II, and VI (P < .05).

Conclusion

The occurrence of AR after allogeneic liver transplantation in rats was positively correlated with the severity of I/R injury. Given that I/R injury caused serious damage to the transplanted liver, the occurrence of AR consequently decreased.     

Wistar-SD大鼠原位肝移植急性排斥反应的观察

目的 观察Wistar-SD大鼠原位肝移植（OLT）术后发生急性排斥反应时的表现及其判断方法。方法 观察大鼠术后生存状况，采用肝功能检查及组织病理学检查等方法研究OLT模型大鼠发生急性排斥反应的表现，结果Wistar-SD实验组OLT术后发生中，重度急性排斥反应。实验组大鼠肝移植术后血清ALT，AST，TB于第1～3天及第7天各指标数值呈明显上升，高于对照组各相应时点，差异仃统计学意义（P〈0.05）：结论Wistar-SD大鼠OLT模型可发生巾，重度急性排斥反应，其肝功能指标的变化可以说明急性排斥反应是否已发生.     

Leukocyte reduction during orthotopic liver transplantation and postoperative outcome: a pilot study

STUDY OBJECTIVE: To investigate the effect of intraoperative leukocyte reduction of administered blood products on the incidence of acute cellular rejection and postoperative patient outcome. DESIGN: Prospective, nonrandomized, historical control study. SETTING: Academic tertiary medical center. PATIENTS: The study group (Group 1) consisted of 30 consecutive adult patients with end-stage liver disease scheduled to undergo orthotopic liver transplantation (OLT) between 1998 and 2000. The historical control group (Group 2) consisted of 30 adult patients with end-stage liver disease matched to study group patients as closely as possible for age, gender, and etiology of liver disease who underwent OLT between 1995 and 1999. INTERVENTIONS: Group 1 patients had all intraoperative allogeneic and cell salvaged blood products leukocyte reduced before administration. Group 2 patients underwent OLT without leukocyte filtration of any administered blood products. MEASUREMENTS: Demographic data were collected for both patient groups and included age, gender, etiology of liver disease, and both intraoperative and postoperative immunosuppression. Demographic allograft donor data for both patient groups were collected and included age, gender, use of vasopressors during procurement, and cold and warm donor organ ischemic times. Outcome variables measured included incidence of acute cellular rejection, length of intensive care unit (ICU) and length of hospital stay, incidence of both graft loss and retransplantation, and mortality. MAIN RESULTS: The incidence of acute cellular rejection was 40% in Group 1 and 66.7% in Group 2 (p = 0.037). Length of ICU stay was 3.0 (2.0, 5.0) days in Group 1 and 4.0 (3.0, 6.0) days in Group 2 (p = 0.16). Length of hospital stay was 14.0 (11.0, 18.0) days in Group 1 and 18.0 (14.0, 27.0) days in Group 2 (p = 0.035). One allograft was lost in Group 2 because of primary nonfunction requiring retransplantation (p = 0.31), and three postoperative deaths occurred in Group 1 as a result of multisystem organ failure (p = 0.08). CONCLUSIONS: Coincident with leukocyte reduction of all administered blood products during OLT, an improved outcome was observed in Group 1 patients as demonstrated by both a decreased incidence of acute cellular rejection and length of hospital stay.     

Assessment of serum matrix metalloproteinases MMP-2 and MMP-9 after human liver transplantation: increased serum MMP-9 level in acute rejection

BACKGROUND: Alterations in synthesis and breakdown of extracellular matrix components play a role in acute rejection after orthotopic liver transplantation (OLT). Matrix metalloproteinases (MMPs) are capable of degrading basement membranes and are involved in the process of tissue remodelling in inflammation and liver fibrosis. METHODS: We examined MMP-2 and MMP-9 in serum of 33 patients before and during 1 year after OLT, in 60 controls as well as in some specimens of cirrhotic liver and control liver tissue. RESULTS: Serum MMP-2 levels before OLT were significantly higher compared with controls and decreased approximately 50% after OLT. Also, the MMP-2 content of cirrhotic liver specimens was significantly higher compared with normal liver. MMP-9 in serum and liver tissue of patients were similar to controls, but serum levels showed a peak at 1 week after OLT. At this time-point, total and active/inhibitor-complexed MMP-9 was significantly higher in patients with rejection (n=13) compared with those without rejection (n=20). The relative amount of MMP-9 in the active/inhibitor-complexed form did not differ between each group over time. Immunohistochemical staining at 1 week after OLT showed increased numbers of MMP-9-positive inflammatory cells in the portal triads of patients with rejection. CONCLUSIONS: Patients with acute allograft rejection have elevated serum levels of MMP-9 1 week after OLT, which was most likely derived from inflammatory cells. An increased MMP-2 serum level and liver tissue content was found in patients with cirrhosis, which decreased after OLT. These observations indicate active involvement of MMP-2 and -9 in end-stage liver disease and OLT.     

Role of inducible nitric oxide synthase in pig liver transplantation

BACKGROUND: Previously, we clarified the role of inducible nitric oxide synthase (iNOS) and the protective effect of an iNOS inhibitor in warm ischemia and reperfusion model. In this study, we investigated whether the same effects would be obtained by iNOS inhibitor in liver transplantation model. MATERIAL AND METHODS: Orthotopic liver transplantation was performed in pigs in the usual manner after about 6 h of cold preservation in University of Wisconsin solution. Aminoguanidine hemisulfate (AG) was used as the iNOS inhibitor and AG was administered intraportally at the dose of 10 mg/kg just after reperfusion. Two experimental groups were subjected, control group (n = 10), and AG group (n = 10). We investigated changes of serum nitrite/nitrate (NOx) and aspartate aminotransferase (AST). Expression of iNOS was examined by immunohistochemistry, including a double immunofluorescnce technique in combination with cofocal laser scanning microscopy. RESULTS: Serum NOx and AST were significantly lower in the AG group. Histological hepatic damage and thrombocyte thrombi were attenuated in the AG group. Expression of iNOS was recognized strongly at Kupffer cells and neutrophils in the centrilobular region of liver after reperfusion by cofocal laser scanning microscopy. Moreover, iNOS staining was attenuated in AG group compared with control group. CONCLUSIONS: These results indicate that hepatic ischemia and reperfusion injury in liver transplantation might be triggered by iNOS expression of Kupffer cells and neutrophils, and attenuated by administration of an iNOS inhibitor. Moreover, AG showed down regulation of iNOS expression after reperfusion.     

自异体微粒皮昆合移植的优化比例研究

目的观察不同比例自异体微粒皮混合移植后创面愈合的效果. 方法以雄性Wistar大鼠为供体,在雌性SD大鼠背部建立全层皮肤缺损创面模型.将SD大鼠随机分为4组,每组10只(1)异体皮组,移植面积扩张比为103的异体微粒皮.(2)自体皮组,移植面积扩张比为101的自体微粒皮.(3)混合1组,自异体微粒皮移植面积扩张比各为101.(4)混合2组,自异体微粒皮移植面积扩张比分别为101和103.于移植术后2、3、4周对各组大鼠创面进行外观和组织学观察,数码相机照相后运用图像分析软件测定创面愈合率和创面收缩率,并进行各组间的比较.结果(1)异体皮组大鼠创面随着排斥反应发生,除创缘有新生表皮向内爬行外均为肉芽创面;自体皮组因微粒皮数量偏少,术后2周仍有部分为肉芽创面;两个混合移植组术后2周创面基本上皮化.(2)移植后各组创面真皮内有不同程度的血管扩张和单个核细胞浸润,在异体皮组和混合2组中更加明显,自体皮组及混合1、2组大鼠创面的表皮层明显增厚.(3)异体皮组移植后2～4周,随着排斥反应的发生,其创面愈合率明显下降.移植后3周,自体皮组创面愈合率为(55±26)%,明显低于混合1、2组的(88±6)%和(76±10)%(P《0.05或0.01).(4)移植后3周,混合2组创面收缩率为(69±7)%,高于异体皮组[(58±11)%],其余各组之间比较差异无统计学意义(P》0.05).结论适当比例的自异体微粒皮混合移植,可以促进创面愈合;当两者移植面积扩张比均为101时,具有较好的促创面愈合效果.     

The effect of cyclosporin on endothelin levels after orthotopic liver transplantation in rats

To assess the effects of cyclosporin (CyA) on endothelin-1 (ET-1) in rat liver allograft rejection, we evaluated ET-1 expression in samples obtained from BN(RT1ⁿ)-to-BN (group 1) rats, DA(RT1^a)-to-BN (group 2) rats, and DA-to-BN rats treated with 5 mg/kg per day of CyA (group 3). Serum and hepatic ET-1 levels, determined by a radioimmunoassay, remained unchanged in group 1. In group 2, the ET-1 levels peaked on postoperative day (POD) 5 in the liver at 344 ± 31.6 pg/g wet, and on POD 7 in the serum at 38.7 ± 13.1 pg/ml. In group 3, hepatic and renal ET-1 levels showed a progressive increase until POD 10, while serum ET-1 levels remained unchanged. In conclusion, acute rejection caused a temporary increase in the ET-1 level in both the serum and the liver in the early postoperative period what might have been caused by endothelial damage due to ongoing, acute rejection. CyA caused a time-dependent increase in the ET-1 level in both the liver and the kidney without an increase in the serum ET-1 level. The serum ET-1 level might have been affected by the clearance of ET from the liver or kidney. Received: 10 April 1996 Received after revision: 29 October 1996 Accepted: 12 November 1996     

Evolution of hepatorenal syndrome after orthotopic liver transplantation: comparative analysis with patients who developed acute renal failure in the early postoperative period of liver transplantation

OBJECTIVE: The purpose of this study was to ascertain the prognosis of patients with hepatorenal syndrome (HS) prior to orthotopic liver transplantation (OLT) by comparisons with a group of selected patients with normal renal function (NRF) pretransplantation who developed acute renal failure (ARF) in the early postoperative period. MATERIALS AND METHODS: Fifty-two OLT cases developed ARF in the early postoperative period between March 1999 and October 2004; 17 cases experienced HS prior to OLT. ARF was defined as serum creatinine level (Cr) >1.5 mg/dL or a creatinine clearance (CrCl) <50 mL/min. The immunosuppressive therapy was the same in both groups: low doses of tacrolimus were prescribed to reach trough levels of 5 ng/mL in the first week after OLT, where patients were administered monoclonal antibodies and corticosteroids. RESULTS: No differences were observed between the groups for gender, age or APACHE II Score in the first 24 hours after OLT. Patients with HS pretransplantation showed higher Cr and urea (U) levels than the other group (Cr: 2.1 +/- 0.8 HS vs 0.9 +/- 0.2, P = .000; U: 93.6 +/- 51.9 HS vs 42.1 +/- 19.3, P = .001). The ICU days of stay were similar (12.8 +/- 0.5 HS vs 19.7 +/- 15.2, P = .053). At the end of 1 year follow-up after OLT there were no differences in mortality (35% HS vs 26%), need for renal replacement therapy (23% HS vs 34%), infection (59% HS vs 51%), or rejection (6% HS vs 29%, P = .06). CONCLUSIONS: Patients with HS prior to OLT showed a similar prognosis to a group of selected patients with NRF pretransplantation, but developed ARF in the early postoperative period which was treated with monoclonal antibodies and low doses of tacrolimus.     

肝硬化大鼠原位肝移植模型的制作及术后排斥反应的观察

目的 制备肝硬化大鼠的原位肝移植模型,观察术后排斥反应发生情况,为进行其它研究创建一个平台.方法 以皮下注射CCl4联合饮用苯巴比妥钠和乙醇溶液的方法制备大鼠肝硬化模型,应用改良的"二袖套"法建立大鼠原位肝移植模型,同系移植者的供、受者均为SD大鼠(SD实验组),以接受肝移植的正常SD大鼠为对照(SD对照组);同种移植者的供者为Lewis大鼠,受者为BN大鼠(BN实验组),以接受肝移植的正常BN大鼠为对照(BN对照组).术后观察受者的存活情况以及移植肝的组织学变化.结果 肝硬化大鼠门静脉压力为(182.0±10.7)mm H2O,显著高于正常大鼠的(70.8±5.5)mm H2O(P＜0.01),移植后7 d降至(82.7±10.7)mm H2O.同种移植组术后5～12 d,移植肝组织中均可见中、重度急性排斥反应病理改变.同系移植者存活时间中位数均＞100 d;同种移植者中,BN对照组和BN实验组受者肝移植后存活时间中位数均为10 d.结论 以Lewis大鼠为供者、肝硬化BN大鼠为受者制备的肝移植模型术后排斥反应的发生率较高,可作为肝移植后排斥反应相关研究的平台.     

The relation between apoptosis of acinar cells and nitric oxide during acute rejection of pancreas transplantation in rats

Apoptosis is an important mechanism of immune-mediated graft damage. Nitric oxide (NO) generated by inducible NO synthase (iNOS) has been demonstrated to induce apoptosis. This study investigated whether apoptosis occurs during pancreas allograft rejection and examined the relationship of apoptosis of acinar cells and NO. The rats were divided into three groups: untreated isograft group, untreated allograft group and aminoguanidine (AG)-treated group. The pancreatic grafts were harvested on the post-transplantation day 3, 5 and 7 and were used to detect the histopathological rejection grade, the expression of iNOS and the apoptotic index (AI) of the graft. iNOS presented faint positive in the acinar cells of untreated isografts and did not change greatly after transplantation (P>0.05), the level of iNOS in the untreated allografts increased progressively (P<0.01) and at the same time point was significantly higher than that of untreated isograft group and AG-treated group (P<0.01). The transferase-mediated dUTP nick end labeling showed that the apoptotic cells were mainly acinar cells. A significant correlation between AI and iNOS was noted (P<0.01, r=0.611). Therefore, NO-mediated apoptosis of acinar cells plays an important role in acute rejection of pancreas transplantation, AG can mitigate the damage of pancreas allografts.     

Deletion variant of hepatocyte growth factor prolongs allograft survival after liver transplantation in rats.

BACKGROUND: Despite continued progress in the development of immunosuppressive agents, allograft rejection remains an important cause of morbidity and mortality after liver transplantation. We examined the effect of the deletion variant of hepatocyte growth factor (dHGF) on allograft rejection after liver transplantation. METHODS: Male Dark Agouti rats (RT1a) were selected as donors and male Lewis rats (RT1l) as recipients for a rejection model. The recipients were divided into 2 groups after orthotopic liver transplantation (OLTx): in the dHGF group dHGF was given intravenously twice a day (1 mg/kg/day) after OLTx, whereas in the control group vehicle buffer was given intravenously daily twice after OLTx. The survival period, serum chemistry studies, and histopathologic findings were then compared between the 2 groups. RESULTS: The mean survival period after OLTx in the dHGF group was significantly longer than that in the control group (21.4 +/- 1.3 days vs 11.8 +/- 0.4 days, P < .001). On the 10th posttransplant day the serum albumin level significantly improved in the dHGF group (P < .01), and the serum total bilirubin and aspartate aminotransferase levels were significantly lower in the dHGF group (P < .01 and P < .05, respectively). On the 10th posttransplant day a histologic examination revealed no apparent difference in the severity of rejection between the 2 groups. The number of proliferating cell nuclear antigen-positive hepatocytes in the dHGF group significantly increased (P < .01), whereas the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling-positive hepatocytes were significantly reduced in the dHGF group (P < .01) in comparison with those in the control group. CONCLUSION: dHGF has an antiapoptotic property as well as a proliferative and protective effect on hepatocytes under allograft rejection. dHGF might serve as a novel agent for reducing the harmful effects of hepatic allograft rejection in rats.