Effect of ischemia-reperfusion on the incidence of acute cellular rejection and timing of histologic hepatitis C virus recurrence after liver transplantation

Effect of intraoperative dexmedetomidine on hepatic ischemia-reperfusion injury in pediatric living-related liver transplantation: A propensity score matching analysis

Background

Hepatic ischemia-reperfusion injury (HIRI) is largely unavoidable during liver transplantation (LT). Dexmedetomidine (DEX), an α2-adrenergic agonist, exerts a variety of organ-protective effects in pediatric populations. However, evidence remains relatively limited about its hepatoprotective effects in pediatric living-related LT.

Methods

A total of 121 pediatric patients undergoing living-related LT from June 2015 to December 2018 in our hospital were enrolled. They were classified into DEX or non-DEX groups according to whether an infusion of DEX was initiated from incision to the end of surgery. Primary outcomes were postoperative liver graft function and the severity of HIRI. Multivariate logistic regression and propensity score matching (PSM) analyses were performed to identify any association.

Results

A 1:1 matching yielded 35 well-balanced pairs. Before matching, no significant difference was found in baseline characteristics between groups except for warm ischemia time, which was longer in the non-DEX group (44 [38–50] vs. 40 [37–44] min, p = 0.017). After matching, the postoperative peak lactic dehydrogenase levels decreased significantly in the DEX group than in the non-DEX group (622 [516–909] vs. 970 [648–1,490] IU/L, p = 0.002). Although there was no statistical significance, a tendency toward a decrease in moderate-to-extreme HIRI rate was noted in the DEX group compared to the non-DEX group (68.6% vs. 82.9%, p = 0.163). Patients in the DEX group also received a significantly larger dosage of epinephrine as postreperfusion syndrome (PRS) treatment (0.28 [0.17–0.32] vs. 0.17 [0.06–0.30] µg/kg, p = 0.010). However, there were no significant differences between groups in PRS and acute kidney injury incidences, mechanical ventilation duration, intensive care unit, and hospital lengths of stay. Multivariate analysis revealed a larger graft-to-recipient weight ratio (odds ratio [OR] 2.657, 95% confidence interval [CI], 1.132–6.239, p = 0.025) and intraoperative DEX administration (OR 0.333, 95% CI, 0.130–0.851, p = 0.022) to be independent predictors of moderate-to-extreme HIRI.

Conclusion

This study demonstrated that intraoperative DEX could potentially decrease the risk of HIRI but was associated with a significant increase in epinephrine requirement for PRS in pediatric living-related LT. Further studies, including randomized controlled studies, are warranted to provide more robust evidence.

CD47 blockade alleviates acute rejection of allogeneic mouse liver transplantation by reducing ischemia/reperfusion injury

Despite advances in immunosuppressive therapies, acute rejection response is still a serious concern especially in the early phase after liver transplantation. This study aimed to evaluate whether blocking the TSP1-CD47 signaling pathway could attenuate the acute rejection after liver transplantation. An allogeneic mouse orthotopic liver transplantation model (Balb/c→C3H) with prolonged cold ischemic phase was used to induce severe IRI and lethal acute rejection. CD47mAb or isotype matched-control IgG_2a was administered to donor liver during graft perfusion. Recipients were sacrificed at 1d, 3d, 5d and 7d after reperfusion. Blood samples were collected to evaluate serum alanine aminotransferase, total bilirubin, HMGB-1,TNF-α, IL-2 and INF-γ level. Flow cytometric analysis was used to detect the strength of innate and adaptive immune response. Liver tissue was obtained for HE, TUNEL staining and F4/80 immumohistochemical staining. Moreover, we conducted a mixed lymphocyte reaction treated with IgG_2a or CD47mAb. Mice in CD47mAb-treated group demonstrated improved survival and significantly lower increase in Suzuki score, apoptosis index, acute rejection index, serum alanine aminotransferase, total bilirubin, HMGB-1, TNF-α, IL-2, INF-γ level and the degree of Kupffer cells' activation especially in the early phase of acute rejection. In addition, Pearson's correlation analysis confirmed significant correlation between Suzuki score/ALT and acute rejection index. The in vitro inhibition assay showed that CD47 blockade couldn't directly inhibit recipient lymphocyte proliferation. Based on the evidence that TSP1-CD47 signaling blockade with CD47mAb could alleviate acute rejection by reducing the extent of IRI after liver transplantation indirectly, this study provided a basis for new interventions and management methods to support better transplant outcomes.

Post-liver transplant hepatitis C virus recurrence: an unresolved thorny problem

Hepatitis C virus (HCV)-related cirrhosis represents the leading cause of liver transplantation in developed, Western and Eastern countries. Unfortunately, liver transplantation does not cure recipient HCV infection: reinfection universally occurs and disease progression is faster after liver transplant. In this review we focus on what happens throughout the peri-transplant phase and in the first 6-12 mo after transplantation: during this crucial period a completely new balance between HCV, liver graft, the recipient's immune response and anti-rejection therapy is achieved that will deeply affect subsequent outcomes. Nearly all patients show an early graft reinfection, with HCV viremia reaching and exceeding pre-transplant levels; in this setting, histological assessment is essential to differentiate recurrent hepatitis C from acute or chronic rejection; however, differentiating the two patterns remains difficult. The host immune response (mainly cellular mediated) appears to be crucial both in the control of HCV infection and in the genesis of rejection, and it is also strongly influenced by immunosuppressive treatment. At present no clear immunosuppressive strategy could be strongly recommended in HCV-positive recipients to prevent HCV recurrence, even immunotherapy appears to be ineffective. Nonetheless it seems reasonable that episodes of rejection and over-immunosuppression are more likely to enhance the risk of HCV recurrence through immunological mechanisms. Both complete prevention of rejection and optimization of immunosuppression should represent the main goals towards reducing the rate of graft HCV reinfection. In conclusion, post-transplant HCV recurrence remains an unresolved, thorny problem because many factors remain obscure and need to be better determined.

Recurrent hepatitis C after liver transplant

End stage liver disease from hepatitis C is the most common indication for liver transplantation in many parts of the world accounting for up to 40% of liver transplants. Antiviral therapy either before or after liver transplantation is challenging due to side effects and lower efficacy in patients with cirrhosis and liver transplant recipients, as well as from drug interactions with immunosuppressants. Factors that may affect recurrent hepatitis C include donor age, immunosuppression, IL28B genotype, cytomegalovirus infection, and metabolic syndrome. Older donor age has persistently been shown to have the greatest impact on recurrent hepatitis C. After liver transplantation, distinguishing recurrent hepatitis C from acute cellular rejection may be difficult, although the development of molecular markers may help in making the correct diagnosis. The advent of interferon free regimens with direct acting antiviral agents that include NS3/4A protease inhibitors, NS5B polymerase inhibitors and NS5A inhibitors holds great promise in improving outcomes for liver transplant candidates and recipients.

Strategies to reduce hepatitis C virus recurrence after liver transplantation

Hepatitis C virus (HCV) is a major health problem that leads to chronic hepatitis, cirrhosis and hepatocellular carcinoma, being the most frequent indication for liver transplantation in several countries. Unfortunately, HCV re-infects the liver graft almost invariably following reperfusion, with an accelerated history of recurrence, leading to 10%-30% of patients progressing to cirrhosis within 5 years of transplantation. In this sense, some groups have even advocated for not re-transplanting this patients, as lower patient and graft outcomes have been reported. However, the management of HCV recurrence is being optimized and several strategies to reduce post-transplant recurrence could improve outcomes, decrease the rate of re-transplantation and optimize the use of available grafts. Three moments may be the focus of potential actions in order to decrease the impact of viral recurrence: the pre-transplant moment, the transplant environment and the post-transplant management. In the pre-transplant setting, it is not well established if reducing the pre transplant viral load affects the risk for HCV progression after transplant. Obviously, antiviral treatment can render the patient HCV RNA negative post transplant but the long-term benefit has not yet been fully established to justify the cost and clinical risk. In the transplant moment, factors as donor age, cold ischemia time, graft steatosis and ischemia/reperfusion injury may lead to a higher and more aggressive viral recurrence. After the transplant, discussion about immunosuppression and the moment to start the treatment (prophylactic, pre-emptive or once-confirmed) together with new antiviral drugs are of interest. This review aims to help clinicians have a global overview of post-transplant HCV recurrence and strategies to reduce its impact on our patients.

Hepatic preservation injury: severity of hepatitis C recurrence and survival after liver transplantation

BACKGROUND

Preservation injury in the HCV liver transplant population has been reported to correlate with poorer survival outcomes compared to preservation injury in the non-HCV liver transplant population. However, determinants of progression to cirrhosis in HCV infection remain poorly defined in this population.

AIM

This study aimed to determine if the presence and severity of preservation injury impact the acceleration of HCV recurrence and survival after liver transplant.

METHODS

We retrospectively reviewed liver transplant HCV patients over a 10-year period. Biopsies from postoperative day 7 were assessed for preservation injury and 4- and 12-month biopsies were assessed for fibrosis. Patients with Ishak fibrosis >0.8 Units/year were considered rapid fibrosers.

RESULTS

Our study group consisted of 255 patients. The mean age was 49.3 years old, 180 (70.6 %) were male, and 221 (86.7 %) were Caucasian. The incidence of preservation injury on the 7-day biopsy was 69.0 %. A strong correlation between postoperative peak AST within the first week and preservation injury was found. The overall prevalence of rapid fibrosers at 4 months, 1 and 2 years was 47.4, 75.2, and 58.9 %, respectively. The prevalence of rapid fibrosers at 4 months, 1 and 2 years between patients with or without preservation injury was not statistically significant (p = 0.39, p = 0.46, and p = 0.53, respectively). No differences were seen between patients with and without PI in terms of patient and graft survival.

CONCLUSION

In this study, the presence and severity of preservation injury were not associated with development of rapid HCV recurrence or worsening in survival.

The beneficial impact of temporary porto-caval shunt in orthotopic liver transplantation: a single center analysis

The use of temporary porto-caval shunt (TPCS) has been shown to improve hemodynamic stability and renal function in patients undergoing orthotopic liver transplantation (OLT). We evaluated the impact of TPCS in OLT and analyzed the differences according to model for end-stage liver disease (MELD), donor risk index (DRI) and D-MELD. This is a retrospective single-center analysis of 148 consecutive OLT. Fifty-eight OLT were performed using TPCS and 90 without TPCS. Donor and recipient data with pre-OLT, intraoperative and postoperative variables were reviewed. Overall graft survival was 89.9% at 3 months and 81.7% at 1 year. Graft survival at 3 months and 1 year was 93.1% and 79.2%, respectively, in TPCS group versus 85.6% and 82.2%, respectively, in non-TPCS group (P = NS). Intraoperative packed red blood cells requirement was lower in TPCS group (7.5 ± 5.8 vs. 12.2 ± 14.2, P = 0.006) and non-TPCS group required higher intraoperative total dose of phenylephrine (16% vs. 28%, P = 0.04). TPCS group had lower 30-day postoperative mortality (1.7% vs. 10%, P = 0.04), no difference was observed at 90 days. Graft survival was lower in patients with high DRI; in this group graft loss was higher at 1 month (25% vs. 4.3%, P = 0.005) and 3 months (25% vs. 4.3%, P = 0.005) when TPCS was not used. TPCS improves perioperative outcome, this being more evident when high-risk grafts are placed into high-risk patients.

Molecular and cellular aspects of hepatitis C virus reinfection after liver transplantation: how the early phase impacts on outcomes

Hepatitis C virus (HCV)-related liver disease postliver transplantation is associated with an accelerated course in comparison with that observed in the nonimmunosuppressed individual. Outcomes in transplantation for this indication have, therefore, been a major area of clinical interest in the field of liver transplantation. The factors underlying the rapid progression of HCV-related liver disease posttransplantation are complex and multifactorial. Nevertheless, recent data indicate a range of parameters assessable early posttransplantation that may be useful in the prediction of outcome of transplantation for this condition. This overview, therefore, concentrates on the early events occurring postliver transplantation in the HCV-infected patient, and the implications of these recent observations for the pathogenesis of the various forms of HCV-related allograft injury.