Expression of perforin and granzyme B mRNA in judgement of immunosuppressive effect in rat liver transplantation

Protective effect of nitric oxide on hepatopulmonary syndrome from ischemia-reperfusion injury

AIM: To evaluate immunological protection of nitric oxide (NO) in hepatopulmonary syndrome and probable mechanisms of ischemia-reperfusion (IR) injury in rat liver transplantation.

METHODS: Sixty-six healthy male Wistar rats were randomly divided into three groups (11 donor/recipient pairs). In group II, organ preservation solution was lactated Ringer’s solution with heparin 10  000/μL at 4 °C. In groups I and III, the preservation solution added, respectively, L-arginine or N^G-L-arginine methyl ester (L-NAME) (1 mmol/L) based on group II, and recipients were injected with L-arginine or L-NAME (50 mg/kg) in the anhepatic phase. Grafted livers in each group were stored for 6 h and implanted into recipients. Five rats were used for observation of postoperative survival in each group. The other six rats in each group were used to obtain tissue samples, and executed at 3 h and 24 h after transplantation. The levels of alanine aminotransferase (ALT), tumor necrosis factor (TNF)-α and NO metabolites (NOx) were detected, and expression of NO synthase, TNF-α and intercellular adhesion molecule 1 (ICAM-1) was examined by triphosphopyridine nucleotide diaphorase histochemical and immunohistochemical staining.

RESULTS: By supplementing L-arginine to strengthen the NO pathway, a high survival rate was achieved and hepatic function was improved. One-week survival rate of grafted liver recipients in group I was significantly increased (28.8 ± 36.6 d vs 4 ± 1.7 d, P < 0.01) as compared with groups II and III. Serum levels of ALT in group I were 2-7 times less than those in groups II and III (P < 0.01). The cyclic guanosine monophosphate (cGMP) levels in liver tissue and NOx in group I were 3-4 times higher than those of group II after 3 h and 24 h reperfusion, while in group III, they were significantly reduced as compared with those in group II (P < 0.01). The levels of TNF-α in group I were significantly lower than in group II after 3 h and 24 h reperfusion (P < 0.01), while being significantly higher in group III than group II (P < 0.01). Histopathology revealed more severe tissue damage in graft liver and lung tissues, and a more severe inflammatory response of the recipient after using NO synthase inhibitor, while the pathological damage to grafted liver and the recipient’s lung tissues was significantly reduced in group I after 3 h and 24 h reperfusion. A small amount of constitutive NO synthase (cNOS) was expressed in liver endothelial cells after 6 h cold storage, but there was no expression of inducible NO synthase (iNOS). Expression of cNOS was particularly significant in vascular endothelial cells and liver cells at 3 h and 24 h after reperfusion in group II, but expression of iNOS and ICAM-1 was low in group I. There was diffuse strong expression of ICAM-1 and TNF-α in group III at 3 h after reperfusion.

CONCLUSION: The NO/cGMP pathway may be critical in successful organ transplantation, especially in treating hepatopulmonary syndrome during cold IR injury in rat orthotopic liver transplantation.

Effect of local CTLA4Ig gene transfection on acute rejection of small bowel allografts in rats

AIM: To evaluate the local expression of CTLA4Ig gene in small bowels and its action on preventing acute rejection of the small bowel allografts.

METHODS: Wistar rats underwent heterotopic small bowel transplantation from SD rats. The recipients were divided into experimental group (allografts were transfected with CTLA4Ig gene) and control group (CTLA4Ig gene not transfected) randomly. In the experimental group, the donor small bowels were perfused in vitro with CTLA4Ig cDNA packaged with lipofectin vector via intra-superior mesenteric artery before transplantation, and the CTLA4Ig expression in the small bowel grafts post-transplantation was assessed by immunohistology. On d 3, 7 and 10 post-transplantation, the allografts in each group were harvested for the examination of histology and assay of apoptosis.

RESULTS: Small bowel allografts treated with CTLA4Ig cDNA showed abundant CTLA4Ig expression after transplantation. Acute rejection grade Ⅰ on day 7 and grade Ⅱ on day 10 after transplantation was noticed in the control allografts, and a dramatically increased number of apoptotic enterocytes in parallel to the progressive rejection could be recognized. In contrast, the allografts treated with CTLA4Ig cDNA showed nonspecific histological changes and only a few of apoptotic enterocytes were found after transplantation.

CONCLUSION: Local CTLA4Ig gene transfection of small bowel allograft is feasible, and the local CTLA4Ig expression in the allograft can prevent acute rejection after transplantation.

Application of modified two-cuff technique and multiglycosides tripterygium wilfordii in hamster-to-rat liver xenotransplant model

AIM: To modify the hamster-to-rat liver xenotransplant technique to prevent postoperative complications, and to study the inhibiting effect of multiglycosides tripterygium wilfordii (T_II) on immune rejection.

METHODS: Female golden hamsters and inbred male Wistar rats were used as donors and recipients, respectively. One hundred and twelve orthotopic liver xenotransplants were performed by Kamada’s cuff technique with modifications. Over 72 hour survival of the animal after operation was considered as a successful operation. When the established surgical model became stable, 30 of the latest 42 cases were divided into untreated control group (n = 15) and T_II group (n = 15) at random. Survival of recipients was observed. Liver specimens were collected at 2 and 72 h from the operated animals and postmortem, respectively, for histological study.

RESULTS: The successfully operative rate of the 30 operations was 80%, and the survival of the control and T_II group was 7.1 ± 0.35 was days and 7.2 ± 0.52 d, respectively (t = 0.087, P = 0.931). The rate of conjunctival hyperemia in control group (100%) differed significantly from that (31%) in T_II group (P = 0.001). Rejection did not occur in both groups within 2 h postoperatively, but became obvious in control group at 72 h after surgery and mild in T_II group. Although rejections were obvious in both groups at death of recipients, it was less severe in T_II group than in control group.

CONCLUSION: This modified Kamada’s technique can be used to establish a stable hamster-to-rat liver xenotransplant model. Monotherapy with multiglycosides tripteryguiumwilfordii (30 mg•kg^-1•l^-1) suppresses the rejection mildly, but fails to prolong survival of recipients.

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Influence of intrauterine injection of rat fetal hepatocytes on rejection of rat liver transplantation

AIM: To investigate the influence of immune tolerance induced by intrauterine exposure to fetal hepatocytes on liver transplantation in the adult rat.

METHODS: LOU/CN rat fetal hepatocytes were injected into the fetuses of pregnant CHN rats (14-16 days of gestation). At 7-9 weeks of age, the surviving male rats received orthotopic liver transplantation (OLT) from male LOU/CN donors and the survival period was observed and monitered by mixed lymphocyte reaction assay and cytotoxicity test.

RESULTS: (1) A total of 31 pregnant CHN rats with 172 fetuses received fetal hepatocytes from LOU/CN rats via intrauterine injection. Among them, thirteen pregnant rats showed normal parturition, with 74 neonatal rats growing up normally. (2) The mean survival period after OLT in rats with fetal exposure to fetal hepatocytes was 32.1 ± 3.7 days, which was significantly different from the control (11.8 ± 2.3 days, P < 0.01) in rats without fetal induction of immune tolerance. (3) Mixed lymphocyte proliferation assays yielded remarkable discrepancies between the groups of rats with- or without fetal exposure to fetal hepatocytes, with values of 8411 ± 1361 and 22473 ± 1856 (CPM ± SD, P < 0.01) respectively. (4) Cytotoxicity assays showed values of 21.2 ± 6.5% and 64.5 ± 7.2% (P < 0.01) in adult rats with or without fetal induction of immune tolerance.

CONCLUSION: Intrauterine injection of fetal hepatocytes into rat fetuses can prolong the survival period of liver transplant adult male rats recipients, inducting immune tolerance in OLT.

Expression of MMP-2, TIMP-2 protein and the ratio of MMP-2/TIMP-2 in gallbladder carcinoma and their significance

AIM: To study the correlation between expression of MMP-2, TIMP-2 protein and the ratio of MMP-2/TIMP-2 and clinical-pathological parameters of patients with gallbladder carcinoma.

METHODS: Carcinomas (n = 45) and polypoid lesions (n = 15) of the gallbladder were studied for the expression of MMP-2 and TIMP-2 protein by immunohistochemical avidin-biotin-complex method and image analysis. Clinical-pathological data of patients with gallbladder carcinoma such as histological type, grade of differentiation, level of infiltration, liver invasion and lymph node involvement, etc, were recorded.

RESULTS: There was significant difference between the average level (1.123 ± 0.108 vs 1.030 ± 0.054, P = 0.002) of MMP-2, the ratio (1.050 ± 0.013 vs 0.937 ± 0.078, P = 0.003) of MMP-2/TIMP-2 in gallbladder carcinomas and in polypoid lesions of the gallbladder. Significant difference was found between the expression of MMP-2 in early stage and advanced tumors, but there was no correlation between MMP - 2 protein expression and histological type, differentiation degree, infiltration level, lymph node involvement or liver invasion. Although no difference was observed between TIMP-2 expression and histological type or differentiation degree, significant difference was found between TIMP-2 expression and different Nevin stage, infiltration level, local lymph node involvement or liver invasion (1.168 ± 0.067 vs 1.048 ± 0.075, 1.170 ± 0.062 vs 1.039 ± 0.069, 1.039 ± 0.076 vs 1.147 ± 0.083, 1.048 ± 0.074 vs 1.103 ± 0.095, P < 0.05). MMP-2/TIMP-2 ratio did not correlate with histological type, grade of differentiation and liver invasion, but significant differences were found between MMP-2/TIMP-2 ratio and different Nevin stage, infiltration level and lymph node involvement in patients with carcinoma of gallbladder.

CONCLUSION: TIMP-2 and MMP-2/TIMP-2 ratio could reflect more accurately biological characteristic of gallbladder carcinoma and MMP-2/TIMP-2 ratio might be a new significant marker in early diagnosis, in the judgment of invasion or metastasis and the estimate of prognosis in patients with gallbladder carcinomas.