Functional changes of dendritic cells derived from allogeneic partial liver graft undergoing acute rejection in rats

Zinc finger protein A20 inhibits maturation of dendritic cells resident in rat liver allograft

BACKGROUND

In organ transplant field, although viewed traditionally as instigators of organ allograft rejection, donor-derived interstitial dendritic cells (DCs), including those resident in liver, or host DCs have also been implicated in transplant tolerance in experimental models. This functional dichotomy of DC is governed by various factors, the most important of which appears to be their stage of maturation. This study was designed to examine the effect of zinc finger protein A20 on maturation of DCs resident in rat liver allograft.

MATERIALS AND METHODS

Allogeneic (Dark Agouti [DA] rat to Lewis rat) liver transplantation was performed. Adenovirus carrying the full length of A20 was introduced into liver allografts by ex vivo perfusion via the portal vein during preservation (group A20), physiological saline (group PS), and empty Ad vector rAdEasy (group rAdEasy) that served as controls. Acute liver allograft rejection was assessed, and DCs resident in liver allografts were isolated on day 7 after transplantation. Nuclear factor kappa B (NF-κB)-binding activities, surface expression of costimulatory molecules (CD40, CD80, and CD86), expression of interleukin (IL) 12 messenger RNA (mRNA), and allocostimulatory capacity of DCs were measured with electrophoretic mobility shift assay, flow cytometry, reverse transcription-polymerase chain reaction, and mixed lymphocyte reaction (MLR), respectively.

RESULTS

Ex vivo transfer of A20 adenovirus by portal vein infusion resulted in overexpression of A20 protein in liver allograft after transplantation. On day 7 after transplantation, histologic examination revealed a mild rejection in group A20 but a more severe rejection in group PS and group rAdEasy. DCs from group A20 liver allografts exhibited features of immature DC with detectable but very low level of NF-κB activity, IL-12 mRNA expression, and surface expression of costimulatory molecules (CD40, CD80, and CD86), whereas DCs from group rAdEasy and group PS liver allograft displayed features of mature DC with high level of NF-κB activity, IL-12 mRNA expression, and surface expression of costimulatory molecules (CD40, CD80, and CD86). DCs from group PS and group rAdEasy liver allograft were potent inducers of DNA synthesis and interferon γ production in MLR, and DCs from group A20 liver allografts induced only minimal levels of cell proliferation and interferon γ production in MLR.

CONCLUSIONS

These data suggest that A20 overexpression could effectively inhibit maturation of DCs resident in liver allograft and consequently suppress acute liver allograft rejection.

Granulocyte colony stimulating factor accelerates regeneration and attenuates injury of partial liver allograft in rats

AIM: To investigate the effect of granulocyte colony-stimulating factor (G-CSF) on the rege-neration of partial liver allograft in rats.

METHODS: Rat models with 50% partial liver transplantation (PLTx) were established, followed by administration of either saline or G-CSF for 5 consecutive days. Livers and serum samples were harvested 1 3, 5, 7 and 14 d after PLTx. GRWR (graft-recipient weight ratio) and serum biochemical parameters were calculated or measured, and the expression of PCNA (proliferating cell nuclear antigen) was detected by immunohistochemistry (SABC).

RESULTS: As compared with that in control group, the survival rate of liver allograft was significantly higher (90% vs 60%, χ²= 5.03, P < 0.05) in G-CSF groups. Three days after PLTx, liver regeneration reached the peak in both groups. In comparison with those in the controls, GRWR was increased (P < 0.05), and the level of aspartate transaminase (AST) and alanine aminotransferase (ALT) were lower (3 d: t = 17.61, P < 0.05; t = 20.16, P < 0.05; 5 d: t = 15.64, P < 0.05; t = 23.08, P < 0.05); the level of albumin (ALB) (3 d: 36.2 ± 4.7 vs 29.5 ± 3.4, P < 0.05; 5 d: 43.2 ± 4.1 vs 33.8 ± 3.9, P < 0.05) and the expression of PCNA (t = 23.08, P < 0.05) were higher 3 and 5 d after PLTx in G-CSF groups.

CONCLUSION: G-CSF can promote the regeneration and alleviate the injury of partial liver allograft in rats.

Nuclear factor-kappaB decoy oligodeoxynucleotides attenuates ischemia/reperfusion injury in rat liver graft

AIM

To evaluate the protective effect of NF-kappaB decoy oligodeoxynucleotides (ODNs) on ischemia/reperfusion (I/R) injury in rat liver graft.

METHODS

Orthotopic syngeneic rat liver transplantation was performed with 3 h of cold preservation of liver graft in University of Wisconsin solution containing phosphorothioated double-stranded NF-kappaB decoy ODNs or scrambled ODNs. NF-kappaB decoy ODNs or scrambled ODNs were injected intravenously into donor and recipient rats 6 and 1 h before operation, respectively. Recipients were killed 0 to 16 h after liver graft reperfusion. NF-kappaB activity in the liver graft was analyzed by electrophoretic mobility shift assay (EMSA). Hepatic mRNA expression of TNF-alpha, IFN-gamma and intercellular adhesion molecule-1 (ICAM-1) were determined by semiquantitative RT-PCR. Serum levels of TNF-alpha and IFN-gamma were measured by enzyme-linked immunosorbent assays (ELISA). Serum level of alanine transaminase (ALT) was measured using a diagnostic kit. Liver graft myeloperoxidase (MPO) content was assessed.

RESULTS

NF-kappaB activation in liver graft was induced in a time-dependent manner, and NF-kappaB remained activated for 16 h after graft reperfusion. NF-kappaB activation in liver graft was significant at 2 to 8 h and slightly decreased at 16 h after graft reperfusion. Administration of NF-kappaB decoy ODNs significantly suppressed NF-kappaB activation as well as mRNA expression of TNF-alpha, IFN-gamma and ICAM-1 in the liver graft. The hepatic NF-kappaB DNA binding activity [presented as integral optical density (IOD) value] in the NF-kappaB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat (2.16+/-0.78 vs 36.78+/-6.35 and 3.06+/-0.84 vs 47.62+/- 8.71 for IOD value after 4 and 8 h of reperfusion, respectively, P<0.001). The hepatic mRNA expression level of TNF-alpha, IFN-gamma and ICAM-1 [presented as percent of beta-actin mRNA (%)] in the NF-kappaB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat (8.31+/-3.48 vs 46.37+/-10.65 and 7.46+/- 3.72 vs 74.82+/-12.25 for hepatic TNF-alpha mRNA, 5.58+/-2.16 vs 50.46+/-9.35 and 6.47+/-2.53 vs 69.72+/-13.41 for hepatic IFN-gamma mRNA, 6.79+/-2.83 vs 46.23+/-8.74 and 5.28+/-2.46 vs 67.44+/-10.12 for hepatic ICAM-1 mRNA expression after 4 and 8 h of reperfusion, respectively, P<0.001). Administration of NF-kappaB decoy ODNs almost completely abolished the increase of serum level of TNF-alpha and IFN-gamma induced by hepatic ischemia/reperfusion, the serum level (pg/mL) of TNF-alpha and IFN-gamma in the NF-kappaB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat (42.7+/-13.6 vs 176.7+/-15.8 and 48.4+/-15.1 vs 216.8+/-17.6 for TNF-alpha level, 31.5+/-12.1 vs 102.1+/-14.5 and 40.2+/-13.5 vs 118.6+/-16.7 for IFN-gamma level after 4 and 8 h of reperfusion, respectively, P<0.001). Liver graft neutrophil recruitment indicated by MPO content and hepatocellular injury indicated by serum ALT level were significantly reduced by NF-kappaB decoy ODNs, the hepatic MPO content (A655) and serum ALT level (IU/L) in the NF-kappaB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat (0.17+/-0.07 vs 1.12+/-0.25 and 0.46+/-0.17 vs 1.46+/-0.32 for hepatic MPO content, 71.7+/-33.2 vs 286.1+/-49.6 and 84.3+/-39.7 vs 467.8+/-62.3 for ALT level after 4 and 8 h of reperfusion, respectively, P<0.001).

CONCLUSION

The data suggest that NF-kappaB decoy ODNs protects against I/R injury in liver graft by suppressing NF-kappaB activation and subsequent expression of proinflammatory mediators.

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Influence of liver nonparenchymal cell infusion combined with cyclosporin A on rejection of rat small bowel transplantation

AIM: To investigate the effect of liver nonparenchymal cell infusion combined with cyclosporin A (CsA) on rejection of heterostrain rat small bowel transplantation.

METHODS: The liver nonparenchymal cell suspension was prepared by density gradient centrifugation method with Percoll centrifugal solution. Heterotopic small bowel transplantation was performed. Then the rats were divided into four groups. Group one: homogenic transplantation (F344/N→F344/N), group two: allotransplantation (F344/N →Wistar), group three: allotransplantation (F344/N→Wistar) + CsA, with CsA 10 mg·kg^-1·d^-1 after transplantation, group four: allotransplantation + CsA (F344/N→Wistar) + liver nonparenchymal cell infusion + CsA (F344/N→Wistar), in which recipient Wistar rats had been injected with 2 × 10⁸ F344/N liver nonparenchymal cells 20 days before transplantation, and treated with CsA after transplantation. Finally, the survival time after small bowel transplantation, gross and histopathological examination, and IL-2 levels in serum were observed.

RESULTS: The survival time after small bowel transplantation was 7.14 ± 0.33 d, 16.32 ± 0.41 d and 31.41 ± 0.74 d in group 2, 3, and 4, respectively. The survival time was significant longer (P < 0.01) in group 4. The gross and histopathological examination showed that the rejection degree in group 4 was lower than those in groups 2 and 3. Serum IL-2 level in group 4 was also lower than those in groups 2 and 3 (P < 0.01).

CONCLUSION: Liver nonparenchymal cell infusion combined with CsA can prolong the survival time of rat small bowel transplantation, and the anti-rejection effect is good.

NF-κB activation and zinc finger protein A20 expression in mature dendritic cells derived from liver allografts undergoing acute rejection

AIM: To investigate the role of NF-κB activation and zinc finger protein A20 expression in the regulation of maturation of dendritic cells (DCs) derived from liver allografts undergoing acute rejection.

METHODS: Sixty donor male SD rats and sixty recipient male LEW rats weighing 220-300 g were randomly divided into whole liver transplantation group and partial liver transplantation group. Allogeneic (SD rat to LEW rat) whole and 50% partial liver transplantation were performed. DCs from liver grafts 0 hour and 4 d after transplantation were isolated and propagated in the presence of GM-CSF in vitro. Morphological characteristics and phenotypical features of DCs propagated for 10 d were analyzed by electron microscopy and flow cytometry, respectively. NF-κB binding activity, IL-12 p70 protein and zinc finger protein A20 expression in these DCs were measured by EMSA and Western blotting, respectively. Histological grading of rejection was determined.

RESULTS: Allogeneic whole liver grafts showed no signs of rejection on day 4 after the transplantation. In contrast, allogeneic partial liver grafts demonstrated moderate to severe rejection on day 4 after the transplantation. After propagation for 10 d in the presence of GM-CSF in vitro, DCs from allogeneic whole liver grafts exhibited features of immature DC with absence of CD40 surface expression, these DCs were found to exhibit detectable but very low level of NF-κB activity, IL-12 p70 protein and zinc finger protein A20 expression. Whereas, DCs from allogeneic partial liver graft 4 d after transplantation displayed features of mature DC, with high level of CD40 surface expression, and as a consequence, higher expression of IL-12p70 protein, higher activities of NF-κB and higher expression of zinc finger protein A20 compared with those of DCs from whole liver grafts (P < 0.001).

CONCLUSION: These results suggest that A20 expression is up-regulated in response to NF-κB activation in mature DCs derived from allogeneic liver grafts undergoing acute rejection. Given the NF-κB inhibition function of this gene, it is suggested that their expression survives to limit NF-κB activation and maturation of DCs, and consequently inhibits the acute rejection and induces acceptance of liver graft.

Postoperative endoscopic surveillance of human living-donor small bowel transplantations

AIM: To determine the significance of endoscopic surveillance in the diagnosis of acute rejection after human living-donor small bowel transplantations.

METHODS: Endoscopic surveillance was performed through the ileostomy after human living-donor small bowel transplantations. The intestinal mucosa was observed and biopsies were performed for pathological observations.

RESULTS: Acute rejection was diagnosed in time by endoscopic surveillance. The endoscopic and pathological manifestations of acute rejection were described.

CONCLUSION: Endoscopic surveillance and biopsy are reliable methods to diagnose the acute rejection after human living-donor small bowel transplantations.