Early postoperative response of cytokines in liver transplant recipients

OXIDATIVE study: A pilot prospective observational cohort study protocol examining the influence of peri-reperfusion hyperoxemia and immune dysregulation on early allograft dysfunction after orthotopic liver transplantation

Early allograft dysfunction (EAD) is a functional hepatic insufficiency within a week of orthotopic liver transplantation (OLT) and is associated with morbidity and mortality. The etiology of EAD is multifactorial and largely driven by ischemia reperfusion injury (IRI), a phenomenon characterized by oxygen scarcity followed by paradoxical oxidative stress and inflammation. With the expanded use of marginal allografts more susceptible to IRI, the incidence of EAD may be increasing. This necessitates an in-depth understanding of the innate molecular mechanisms underlying EAD and interventions to mitigate its impact. Our central hypothesis is peri-reperfusion hyperoxemia and immune dysregulation exacerbate IRI and increase the risk of EAD. We will perform a pilot prospective single-center observational cohort study of 40 patients. The aims are to determine (1) the association between peri-reperfusion hyperoxemia and EAD and (2) whether peri-reperfusion perturbed cytokine, protein, and hypoxia inducible factor-1 alpha (HIF-1α) levels correlate with EAD after OLT. Inclusion criteria include age ≥ 18 years, liver failure, and donation after brain or circulatory death. Exclusion criteria include living donor donation, repeat OLT within a week of transplantation, multiple organ transplantation, and pregnancy. Partial pressure of arterial oxygen (PaO2) as the study measure allows for the examination of oxygen exposure within the confines of existing variability in anesthesiologist-administered fraction of inspired oxygen (FiO2) and the inclusion of patients with intrapulmonary shunting. The Olthoff et al. definition of EAD is the primary outcome. Secondary outcomes include postoperative acute kidney injury, pulmonary and biliary complications, surgical wound dehiscence and infection, and mortality. The goal of this study protocol is to identify EAD contributors that could be targeted to attenuate its impact and improve OLT outcomes. If validated, peri-reperfusion hyperoxemia and immune perturbations could be targeted via FiO2 titration to a goal PaO2 and/or administration of an immunomodulatory agent by the anesthesiologist intraoperatively.

New Approaches to the Diagnosis of Rejection and Prediction of Tolerance in Liver Transplantation

Immunosuppression after liver transplantation is essential for preventing allograft rejection. However, long-term drug toxicity and associated complications necessitate investigation of immunosuppression minimization and withdrawal protocols. Development of such protocols is hindered by reliance on current paradigms for monitoring allograft function and rejection status. The current standard of care for diagnosis of rejection is histopathologic assessment and grading of liver biopsies in accordance with the Banff Rejection Activity Index. However, this method is limited by cost, sampling variability, and interobserver variation. Moreover, the invasive nature of biopsy increases the risk of patient complications. Incorporating noninvasive techniques may supplement existing methods through improved understanding of rejection causes, hepatic spatial architecture, and the role of idiopathic fibroinflammatory regions. These techniques may also aid in quantification and help integrate emerging -omics analyses with current assessments. Alternatively, emerging noninvasive methods show potential to detect and distinguish between different types of rejection while minimizing risk of adverse advents. Although biomarkers have yet to replace biopsy, preliminary studies suggest that several classes of analytes may be used to detect rejection with greater sensitivity and in earlier stages than traditional methods, possibly when coupled with artificial intelligence. Here, we provide an overview of the latest efforts in optimizing the diagnosis of rejection in liver transplantation.

Progress and challenges in diagnosis and treatment of rejection following liver transplantation

PURPOSE OF REVIEW

Liver biopsy remains the most widely utilized method for diagnosis of allograft rejection following liver transplantation. However, associated risks and limitations present an opportunity for emerging noninvasive diagnostic techniques to improve upon the current standard of care. This review evaluates progress toward development of new noninvasive methods for the monitoring and diagnosing of allograft rejection.

RECENT FINDINGS

Recent studies investigate the potential of a variety of analytes. Quantification of dd-cfDNA and of DSA show potential to indicate status of allograft rejection and aid in immunosuppression modulation. Moreover, mRNA microarray profiling of differentially expressed genes, as well as characterization of cytokine responses and immunophenotypic shifts following liver transplantation, may predict and recognize rejection events.

SUMMARY

Noninvasive methods are not yet ready to replace liver biopsy as the standard of care for diagnosis of allograft rejection, though several assays and biomarkers have shown promising preliminary results. As noninvasive techniques become validated in clinical settings, their integration with current diagnostic methods is likely to foster increased sensitivity, specificity, and reliability of diagnosis.

Cytokines in Liver Transplantation

Cytokines, soluble mediators of the immune system, play a critical role in the pathogenesis of autoimmune, allergic and infectious diseases. They are also implicated in the initiation and development of allograft rejection. During recent years, there have been considerable advances in generating novel anti-cytokine agents with promoted efficacy and safety, which could be administrated for managing dysregulated cytokine secretion; besides, gene therapy for overexpression of immunomodulatory cytokines has shown substantial improvements. Liver transplantation has been established as a life-saving treatment for end-stage hepatic diseases but the growing number of recipients urge for improved post-transplant care including tolerance induction, infection control and resolving immunosuppressant drugs adverse effects. Cytokines with a wide range of proinflammatory and regulatory properties might be considered as potential therapeutic targets for selective suppression or enhancement of the immune responses in recipients. In the present review, we aimed to summarize the positive and negative effects of cytokines on liver allograft in addition to their prognostic and therapeutic values.

Impact of prolonged clamping of the portal vein during liver transplantation in infants with biliary atresia: renewed interest in a long-standing issue

PURPOSE

Various approaches to portal vein (PV) reconstruction have been described; however, there is still scope to improve the safety and efficiency of how PV anastomosis is performed in infants.

METHODS

We analyzed, retrospectively, the predictive factors for PV reanastomosis during living donor liver transplantation (LDLT) in 117 infants (< 1 year old) with biliary atresia (BA).

RESULTS

Twenty-six infants required PV reanastomosis because of intraoperative PV thrombosis in 21 and insufficient PV flow in 5. Univariate analysis identified multiple previous laparotomies and a prolonged anhepatic phase (AHP) as significant risk factors for repeated PV anastomosis. The AHP cutoff value for identifying patients requiring PV reanastomosis was 134 min. Multivariate analysis revealed prolonged AHP > 134 min (odds ratio, 15.98; 95% confidence interval, 5.05-50.6; P < 0.001) as an independent risk factor for repeated PV anastomosis. The plasma D-dimer and fibrinogen degradation product concentration just after reperfusion were significantly higher in patients requiring PV reanastomosis (P < 0.001). Patients requiring reanastomosis of the PV had a higher incidence of PV complications after LDLT than those who did not need PV reanastomosis (P = 0.01).

CONCLUSION

Attempting to minimize the AHP is indispensable for successful LDLT in infants with BA.

Impact of early remote organ dysfunction on long-term survival after liver transplantation

BACKGROUND

Attention is focused on graft function although extrahepatic organ dysfunction often occurs. Renal failure, cardiovascular events and sepsis have individually shown a significant impact on short- and long-term outcomes. The aim of the study was to identify how extrahepatic organ dysfunction (EROD) and allograft dysfunction (EAD) may be associated and their relative impact on long-term survival.

METHODS

A retrospective study was conducted in a unicentric cohort of 294 patients transplanted between 2009 and 2014. The composite endpoint EROD was defined as requirement during the hospitalization of de novo renal replacement therapy, reintubation/ventilation > 7 days or cardiovascular event. Donor and recipient characteristics were evaluated as predictive of EROD in uni- and multivariate analysis. Main endpoint was overall survival evaluated by Kaplan-Meier method.

RESULTS

EROD occurred in 91 patients (31%) among whom 42 also experienced EAD (46%). Predicting factors associated with EROD were IL6 level (P = 0.002) and lab-MELD (P < 0.001). Only patients experiencing both EAD and EROD had a worse survival (P = 0.001). In patients without EAD, time to normalization of bilirubin and INR were longer in patients with EROD compared to those without EROD (P = 0.002 and P = 0.008 respectively).

CONCLUSIONS

The composite endpoint described as early remote organ dysfunction could be used as a predictive factor after transplantation and should be included in future studies together with early allograft dysfunction. Identifying patients in whom EROD and EAD occur together or one after the other could help to better predict long-term outcomes.

Pathophysiologic Implications of Cytokines Secretion during Liver Transplantation Surgery

We introduce the following issues of the cytokines secretion during liver transplantation surgery in this review article; 1) the aspect of cytokines secretion during liver transplantation surgery, 2) the evidences of association of cytokines concentration with post-transplantation graft survival, 3) a variety of factors that may influence the secretion of cytokines during liver transplantation, 4) pro-inflammatory and anti-inflammatory cytokine balance during the surgery, and 5) the issues of T helper 1 and T helper 2, and T helper 17 and regulatory T cell signature cytokines secretion and their ratio during liver transplantation surgery. Primary failure of the liver is associated with the secondary dysfunction of virtually all other organ systems, including the cardiovascular, pulmonary, renal, coagulation and central nervous systems. In addition, liver transplantation surgery itself is a major surgical procedure with accompanying life-threatening hemorrhage, massive transfusion, clamping and unclamping of great vessels and resulting ischemia-reperfusion injury and cardiovascular instability. Both the underlying liver failure and the surgical events act as stressors and promote the secretion of various cytokines. So it is clinically important to understand above issues regarding the cytokines secretion during liver transplantation surgery. As cytokines secretion has clear relationship with post-transplantation clinical outcomes, future study directions for artificially manipulating cytokines secretion is also suggested for enhancing outcomes of the patients.

Modulation of HCV reinfection after orthotopic liver transplantation by fibroblast growth factor-2 and other non-interferon mediators

OBJECTIVE

In HCV infected individuals graft infection occurs shortly after orthotopic liver transplantation (OLT). We aimed to describe the composition of the inflammatory response at this time, how it affects the HCV replication cycle and identify novel proviral and antiviral factors.

DESIGN

We used a Luminex assay to quantify 50 inflammatory mediators in sera before and shortly after OLT. In vitro grown HCV based on the JFH-1 isolate were used to characterise the effects of patient sera and individual mediators on HCV.

RESULTS

Although the mediator composition is highly variable between individuals, sera drawn immediately post-OLT significantly enhance HCV infectivity compared with control sera from before OLT in about half of the cases. Among 27 non-interferon inflammatory mediators fibroblast growth factor (FGF)-2 stood out as it enhanced HCV RNA replication and release of infectious particles. The effect was concentration-dependent and detectable in dividing and non-dividing cells. Moreover, pharmacological inhibition of FGF-2 receptor signalling abrogated the enhancing effect of FGF-2 and inhibited HCV replication in the absence of serum FGF-2 suggesting that HCV replication is dependent on basal activation of the FGF-2 triggered signalling pathway. Finally, in individuals with chronic HCV infection with high viral load, serum FGF-2 was significantly higher compared with those with low viral load.

CONCLUSIONS

Although no single mediator may account for this effect, serum shortly post-OLT enhances HCV infection. FGF-2 is a novel endogenous driver of HCV replication and a potential therapeutic target.

Inferior graft survival of hepatitis B core positive grafts is not influenced by post-transplant hepatitis B infection in liver recipients--5-year single-center experience

Nonoptimal liver grafts, and among them organs from anti-HBc+ donors, are increasingly used for liver transplantation. In this retrospective study including 1065 adult liver transplantations performed between 1977 and 2012, we analyzed long-term patient and graft survival and occurrence of HBV infection. A total of 52 (5.1%) patients received an anti-HBc+ graft. The 10-year graft and patient survival of these recipients were 50.9% and 59.0% compared to 72.0% and 76.5% (P = 0.001; P = 0.004) of patients receiving anti-HBc- grafts, respectively. Cox regression model showed that high urgency allocation (P = 0.003), recipient age (P = 0.027), anti-HCV+ recipients (P = 0.005), and anti-HBc+ organs (P = 0.048) are associated with decreased graft survival. Thirteen of 52 (25.0%) patients receiving anti-HBc+ grafts developed post-transplant HBV infection within a mean of 2.8 years. In this study, antiviral prophylaxis did not have significant impact on HBV infection, but long-term survival (P = 0.008). Development of post-transplant HBV infection did not affect adjusted 10-year graft survival (100% vs. 100%; P = 1). Anti-HBc+ liver grafts can be transplanted with reasonable but inferior long-term patient and graft survival. The inferior graft survival is not, however, related with post-transplant HBV infection as long as early diagnosis and treatment take place.

Interferon-γ, interleukin-10 and interferon-inducible protein 10 (CXCL10) as serum biomarkers for the early allograft dysfunction after liver transplantation

Orthotopic liver transplantation (LTP) is nowadays a standard procedure, and provides the chance of survival of patients with end-stage non-treatable chronic liver disease or acute liver failure. Despite long-term survival with a good quality of life in the majority of patients, about 20% develop early allograft dysfunction (EAD), which leads to death or the need for re-transplantation. Therefore, the early diagnosis of EAD and evaluation of its risk factors are very important. Many primary pathological processes leading to EAD are accompanied by the release of different mediators and by a change of biochemical parameters detectable in the peripheral blood. The aim of this study was to investigate cytokines as well as soluble mediators in the serum of patients with and without EAD from our LTP bank, and to evaluate their predictive and prognostic values for EAD. We demonstrated for the first time that the level of IFNγ during the nearest preoperative period may serve as a predictive parameter for EAD. We additionally found that IL-10 and CXCL10 (IP-10) levels in the early postoperative period can be prognostic for EAD. We believe our data expand the spectrum of predictive and prognostic parameters for EAD in LTP.

Genomic profiles and predictors of early allograft dysfunction after human liver transplantation

Early hepatic allograft dysfunction (EAD) manifests posttransplantation with high serum transaminases, persistent cholestasis, and coagulopathy. The biological mechanisms are poorly understood. This study investigates the molecular mechanisms involved in EAD and defines a gene expression signature revealing different biological pathways in subjects with EAD from those without EAD, a potential first step in developing a molecular classifier as a potential clinical diagnostic. Global gene expression profiles of 30 liver transplant recipients of deceased donor grafts with EAD and 26 recipients without graft dysfunction were investigated using microarrays of liver biopsies performed at the end of cold storage and after graft reperfusion prior to closure. Results reveal a shift in inflammatory and metabolic responses between the two time points and differences between EAD and non-EAD. We identified relevant pathways (PPARα and NF-κB) and targets (such as CXCL1, IL1, TRAF6, TIPARP, and TNFRSF1B) associated with the phenotype of EAD. Preliminary proof of concept gene expression classifiers that distinguish EAD from non-EAD patients, with Area Under the Curve (AUC) >0.80 were also identified. This data may have mechanistic and diagnostic implications for EAD.

Serum cytokine profiles associated with early allograft dysfunction in patients undergoing liver transplantation

Early allograft dysfunction (EAD) occurring in the first week post-liver transplantation is associated with increased graft failure and mortality and is believed to be largely due to ischemia/reperfusion injury. We anticipated that the presence of EAD would be reflected by alterations in expression of serum proteins associated with an inflammatory response in the peri-operative period, and hypothesized that a specific pattern of expression might correlate with the development of EAD. The serum levels of 25 cytokines, chemokines, and immunoreceptors were measured by Luminex multiplex assays pre- and post-liver transplantation. Levels of each cytokine biomarker were compared in adult recipients with or without EAD at serial time points using samples collected pre-operatively and at 1, 7, 14, and 30 days post-transplant. EAD was defined according to standard criteria as maximum alanine transferase (ALT) or aspartate transferase (AST) levels on days 1-7 of >2000 U/ml, day 7 bilirubin level ≥10 mg/dl, or a day 7 international normalized ratio (INR) ≥1.7. Multivariable analyses showed that patients experiencing EAD had lower pre-operative IL-6 and higher IL-2R levels. Patients with EAD also showed higher MCP-1 (CCL2), IL-8 (CXCL8), and RANTES (CCL5) chemokine levels in the early post-operative period, suggesting up-regulation of the NF-kB pathway, in addition to higher levels of chemokines and cytokines associated with T cell immunity, including MIG (CXCL9), IP-10 (CXCL10) and IL-2R. These findings identify several possible biomarkers and pathways associated with EAD, that may guide future validation studies and investigation of specific cellular and molecular mechanisms of graft dysfunction. Furthermore, if validated, our findings may contribute to perioperative prediction of the occurrence of EAD and ultimately lead to identification of potential interventional therapies.

Comparison of the Child-Turcotte-Pugh classification and the model for end-stage liver disease score as predictors of the severity of the systemic inflammatory response in patients undergoing living-donor liver transplantation

The aim of this study was to evaluate and compare the Child-Turcotte-Pugh (CTP) classification system and the model for end-stage liver disease (MELD) score in predicting the severity of the systemic inflammatory response in living-donor liver transplantation patients. Recipients of liver graft were allocated to a recipient group (n = 39) and healthy donors to a donor group (n = 42). The association between the CTP classification, the MELD scores and perioperative cytokine concentrations in the recipient group was evaluated. The pro-inflammatory cytokines measured included interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α; the anti-inflammatory cytokines measured included IL-10 and IL-4. Cytokine concentrations were quantified using sandwich enzyme-linked immunoassays. The IL-6, TNF-α, and IL-10 concentrations in the recipient group were significantly higher than those in healthy donor group patients. All preoperative cytokine levels, except IL-6, increased in relation to the severity of liver disease, as measured by the CTP classification. Additionally, all cytokine levels, except IL-6, were significantly correlated preoperatively with MELD scores. However, the correlations diminished during the intraoperative period. The CTP classification and the MELD score are equally reliable in predicting the severity of the systemic inflammatory response, but only during the preoperative period.

Release of cytokines and hemodynamic instability during the reperfusion of a liver graft

The objectives of this prospective, observational study were (1) to determine whether a transplanted liver graft releases proinflammatory cytokines into the systemic circulation upon reperfusion and (2) to determine whether they contribute to any subsequent hemodynamic instability observed after graft reperfusion (if this release occurs). Blood samples from 17 consecutive patients undergoing liver transplantation were analyzed for cytokines, including tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), IL-2, IL-6, and IL-8. Blood samples were obtained from the radial artery, portal vein, and flush blood (a sample taken from a catheter placed above the infrahepatic inferior vena cava clamp). The amount of catecholamines necessary to maintain a mean arterial pressure between 65 and 75 mm Hg during graft reperfusion was compared with the level of cytokines. A statistical analysis was performed with the least squares method, Kendall's tau-b test, and regression analysis. We demonstrated that flush blood from the liver grafts contained a significant amount and variety of cytokines. Most of these were removed by graft irrigation. The concentration of TNF-α in samples obtained from flush blood at the end of liver irrigation was significantly higher than the concentration in samples obtained from the radial artery (P = 0.0067) or portal vein (P = 0.0003) before reperfusion. This correlated directly with the amount of catecholamines used to treat hemodynamic instability. Although there were increased levels of IL-1β, IL-2, and IL-8 in the flush blood, there was no statistically significant correlation between the levels of these cytokines and the amount of catecholamines used.

The clinical relevance of the anhepatic phase during liver transplantation

This study assesses the relation between the anhepatic phase duration and the outcome after liver transplantation. Of 645 patients who underwent transplantation between 1994 and 2006, 194 were recipients of consecutive adult primary piggyback liver transplants using heart-beating donors. The anhepatic phase was defined as the time from the physical removal of the liver from the recipient to recirculation of the graft. Other noted study variables were the cold and warm ischemia times, donor and recipient age, donor and recipient body mass index, perioperative red blood cell (RBC) transfusion, indication for transplantation, and Model for End-Stage Liver Disease score. The primary outcome parameter was graft dysfunction, which was defined as either primary nonfunction or initial poor function according to the Ploeg-Maring criteria. The median anhepatic phase was 71 minutes (37-321 minutes). Graft dysfunction occurred in 27 patients (14%). Logistic regression analysis showed an anhepatic phase over 100 minutes [odds ratio (OR), 4.28], a recipient body mass index over 25 kg/m(2) (OR, 3.21), and perioperative RBC transfusion (OR, 3.04) to be independently significant predictive factors for graft dysfunction. One-year patient survival in patients with graft dysfunction was 67% versus 92% in patients without graft dysfunction (P < 0.001). A direct relation between the anhepatic phase duration and patient survival could, however, not be established. In conclusion, this study shows that liver transplant patients with an anhepatic phase over 100 minutes have a higher incidence of graft dysfunction. Patients with graft dysfunction have significantly worse 1-year patient survival.