Analysis of intragraft adhesion molecules and their release in clinical liver transplantation: impact of reperfusion injury

Transcriptome Analysis of Acute Phase Liver Graft Injury in Liver Transplantation

BACKGROUND

Liver transplantation remains the treatment of choice for a selected group of hepatocellular carcinoma (HCC) patients. However, the long-term benefit is greatly hampered by post-transplant HCC recurrence. Our previous studies have identified liver graft injury as an acute phase event leading to post-transplant tumor recurrence.

METHODS

To re-examine this acute phase event at the molecular level and in an unbiased way, RNA sequencing (RNA-Seq) was performed on liver graft biopsies obtained from the transplant recipients two hours after portal vein reperfusion with an aim to capture frequently altered pathways that account for post-transplant tumor recurrence. Liver grafts from recurrent recipients (n = 6) were sequenced and compared with those from recipients without recurrence (n = 5).

RESULTS

RNA expression profiles comparison pointed to several frequently altered pathways, among which pathways related to cell adhesion molecules were the most involved. Subsequent validation using quantitative polymerase chain reaction confirmed the differential involvement of two cell adhesion molecules HFE (hemochromatosis) and CD274 and their related molecules in the acute phase event.

CONCLUSION

This whole transcriptome strategy unravels the molecular landscape of liver graft gene expression alterations, which can identify key pathways and genes that are involved in acute phase liver graft injury that may lead to post-transplant tumor recurrence.

Failure of P-selectin blockade alone to protect the liver from ischemia-reperfusion injury in the isolated blood-perfused rat liver

AIM: To determine if blockade of P-selectin in the isolated blood-perfused cold ex vivo rat liver model protects the liver from ischemia-reperfusion injury.

METHODS: The effect of P-selectin blockade was assessed by employing an isolated blood-perfused cold ex vivo rat liver with or without P-selectin antibody treatment before and after 6 h of cold storage in University of Wisconsin solution.

RESULTS: In our isolated blood-perfused rat liver model, pre-treatment with P-selectin antibody failed to protect the liver from ischemia-reperfusion injury, as judged by the elevated aspartate aminotransferase activity. In addition, P-selectin antibody treatment did not significantly reduced hepatic polymorphonuclear leukocyte accumulation after 120 min of perfusion. Histological evaluation of liver sections obtained at 120 min of perfusion showed significant oncotic necrosis in liver sections of both ischemic control and P-selectin antibody-treated groups. However, total bile production after 120 min of perfusion was significantly greater in P-selectin antibody-treated livers, compared to control livers. No significant difference in P-selectin and ICAM-1 mRNAs and proteins, GSH, GSSG, and nuclear NF-κB was found between control and P-selectin antibody-treated livers.

CONCLUSION: In conclusion, we have shown that blockade of P-selectin alone failed to reduced polymorphonuclear leukocyte accumulation in the liver and protect hepatocytes from ischemia-reperfusion injury in the isolated blood-perfused cold-ex vivo rat liver model.

Glomerular endothelium exhibits enhanced expression of costimulatory adhesion molecules, CD80 and CD86, by warm ischemia/reperfusion injury in rats

Recent studies suggested that the vascular endothelial cells function as a resident antigen-presenting cell (APC) in certain situations such as organ transplantation, and the ischemia/reperfusion injury, an inevitable event in organ transplantation, leads to an enhanced biosynthesis of cell adhesion molecules. We have demonstrated that the hepatic sinusoidal endothelial cells have potential ability as APCs by expressing the costimulatory adhesion molecule proteins, CD80 (B7-1) and CD86 (B7-2), of which expression was enhanced by warm ischemia/reperfusion of the rat liver. In this study, we assessed the localization of CD80, CD86, and intercellular adhesion molecule 1 in the rat kidneys and the influence of warm ischemia/reperfusion with or without a hypercreatinemic condition on the expression of these adhesion molecules in the renal tissues. Wistar male rats weighing 150 to 230 g were divided into group A, receiving a sham-operation (control), group B, receiving 1-hour clamping of the left renal pedicle (temporary ischemia), and group C, receiving right nephrectomy and 1-hour clamping of the left renal pedicle (temporary ischemia with hypercreatinemia). The left kidneys were submitted to immunohistochemical and molecular analyses sequentially for the period of 14 days. We found that CD80, CD86, and intercellular adhesion molecule 1 proteins localized on the glomerular and peritubular endothelium and were up-regulated after ischemia/reperfusion. The up-regulation of these three proteins was enhanced by the hypercreatinemic condition. The relative mRNA levels analyzed by real-time reverse transcription polymerase chain reaction showed that CD80 and CD86 expressions were constitutively observed and significantly increased for 14 days after the warm ischemia reperfusion with a peak level at Day 3 (6.7- and 20.8-fold increase for CD80 and CD86, respectively). Our results suggested that the glomerular endothelial cells will play a pivotal role as a APC by expressing CD80 and CD86 in the induction of renal tissue injury associated with the ischemia/reperfusion at renal transplantation surgery, as well as the peritubular endothelium.

TNF-alpha and its receptors mediate graft rejection and loss after liver transplantation

Tumour necrosis factor-alpha (TNF-alpha) plays a pivotal role in the immune response and mediates inflammation by its receptors (TNF-RI and TNF-RII), as observed during rejection episodes and impaired graft function after liver transplantation. TNF-alpha and its receptors were analysed by an ELISA technique in serum samples from 77 consecutive liver transplantations in 63 patients. Samples were collected preoperatively from donors and recipients and then daily in the first two postoperative weeks. Peak levels of TNF-alpha and its soluble receptors (sTNF-RI and sTNF-RII) in the first and second postoperative week correlated with the extent of reperfusion injury. Impaired graft functions correlated with high sTNF-RI levels preoperatively (> 5 ng/ml, p = 0.01) and in the postoperative period (> 16 ng/ml, p = 0.02). Significantly increased TNF-alpha (> 25 pg/ml, p = 0.009) and sTNF-RI levels (> 5 ng/ml, p = 0.05) were found in donors of grafts with a high rejection risk. Elevated levels of TNF-alpha in the postoperative period correlated with an increased rejection risk (> 90 pg/ml, p = 0.02). The activity of the immune system with high concentrations of TNF-alpha and its receptors both in the recipient and the transplant donor seems to play an essential role in allograft development.