Canonical, deprotonated, or zwitterionic? II. A computational study on amino acid interaction with the TiO2(110) rutile surface: comparison with the anatase (101) surface

The adsorption of 11 amino acids (Gly, Leu, Met, Phe, Ser, Cys, Glu, Gln, Arg, Lys, and His) on the TiO₂(110) rutile surface is investigated adopting a theoretical approach, using the PBE-D2* functional as implemented in the periodic VASP code. The adsorption of the amino acids is considered in their canonical, deprotonated and zwitterionic forms. For all cases, the most stable adsorption mode adopts a bidentate (O,O) binding with surface undercoordinated Ti atoms, in agreement with previous experimental and computational studies using glycine as a test case. Such a binding mode is possible due to the surface morphology, because the Ti-Ti distances match very well with the carboxylic O-O distance. The most stable adsorption states are the deprotonated and the zwitterionic ones, the canonical one lying significantly above in energy. The relative stability between the deprotonated and the zwitterionic states results in a delicate trade-off among dative interactions (O, N, and S atoms of the amino acids with Ti atoms of the surface), H-bond interactions, dispersive forces and, to a lesser extent, steric hindrance of the amino acidic lateral chains. Finally, the difference in the amino acid adsorption between the (110) rutile and the (101) anatase surfaces is discussed both from the energetic and surface morphological standpoints, highlighting the larger reactivity of the rutile polymorph in adsorbing and deprotonating the amino acids compared with the anatase one.

Direct-acting antivirals are effective and safe in HCV/HIV-coinfected liver transplant recipients who experience recurrence of hepatitis C: A prospective nationwide cohort study

Direct-acting antivirals have proved to be highly efficacious and safe in monoinfected liver transplant (LT) recipients who experience recurrence of hepatitis C virus (HCV) infection. However, there is a lack of data on effectiveness and tolerability of these regimens in HCV/HIV-coinfected patients who experience recurrence of HCV infection after LT. In this prospective, multicenter cohort study, the outcomes of 47 HCV/HIV-coinfected LT patients who received DAA therapy (with or without ribavirin [RBV]) were compared with those of a matched cohort of 148 HCV-monoinfected LT recipients who received similar treatment. Baseline characteristics were similar in both groups. HCV/HIV-coinfected patients had a median (IQR) CD4 T-cell count of 366 (256-467) cells/µL. HIV-RNA was <50 copies/mL in 96% of patients. The DAA regimens administered were SOF + LDV ± RBV (34%), SOF + SMV ± RBV (31%), SOF + DCV ± RBV (27%), SMV + DCV ± RBV (5%), and 3D (3%), with no differences between the groups. Treatment was well tolerated in both groups. Rates of SVR (negative serum HCV-RNA at 12 weeks after the end of treatment) were high and similar for coinfected and monoinfected patients (95% and 94%, respectively; P = .239). Albeit not significant, a trend toward lower SVR rates among patients with advanced fibrosis (P = .093) and genotype 4 (P = .088) was observed. In conclusion, interferon-free regimens with DAAs for post-LT recurrence of HCV infection in HIV-infected individuals were highly effective and well tolerated, with results comparable to those of HCV-monoinfected patients.

Portal pressure and liver stiffness measurements in the prediction of fibrosis regression after sustained virological response in recurrent hepatitis C

Sustained virological response (SVR) improves survival in post-liver transplant (LT) recurrent hepatitis C. However, the impact of SVR on fibrosis regression is not well defined. In addition, the performance of noninvasive methods to evaluate the presence of fibrosis and portal hypertension (PH) post-SVR has been scarcely evaluated. We aimed to investigate the degree of fibrosis regression (decrease ≥1 METAVIR stage) after-SVR and its associated factors in recurrent hepatitis C, as well as the diagnostic capacity of noninvasive methods in the assessment of liver fibrosis and PH after viral clearance. We evaluated 112 hepatitis C virus-infected LT recipients who achieved SVR between 2001 and 2015. A liver biopsy was performed before treatment and 12 months post-SVR. Hepatic venous pressure gradient (HVPG), liver stiffness measurement (LSM), and Enhanced Liver Fibrosis (ELF) score were also determined at the same time points. Sixty-seven percent of the cohort presented fibrosis regression: 43% in recipients with cirrhosis and 72%-85% in the remaining stages (P = 0.002). HVPG, LSM, and ELF significantly decreased post-SVR. Liver function significantly improved, and survival was significantly better in patients achieving fibrosis regression. Baseline HVPG and LSM as well as decompensations before therapy were independent predictors of fibrosis regression. One year post-SVR, LSM had a high diagnostic accuracy to discard the presence of advanced fibrosis (AF) and clinically significant PH (AUROC, 0.902 and 0.888).

CONCLUSION

In conclusion, SVR post-LT induces fibrosis regression in most patients, leading to significant clinical benefits. Pretreatment HVPG and LSM are significant determinants of the likelihood of fibrosis regression. Finally, LSM accurately predicts the presence of AF and PH 1 year after SVR and thus can be used to determine monitoring strategies. (Hepatology 2018;67:1683-1694).

Mannose-Binding Lectin-Deficient Donors Increase the Risk of Bacterial Infection and Bacterial Infection-Related Mortality After Liver Transplantation

Mannose-binding lectin (MBL) is synthesized by the liver and binds to microbes. MBL2 gene polymorphisms produce intermediate/low/null or normal MBL serum levels (MBL-deficient or MBL-sufficient phenotypes, respectively). We aimed to evaluate the incidence and severity of infection, rejection, and survival within 1 year after liver transplantation (LT) according to donor and recipient MBL2 gene polymorphisms. A repeated-event analysis for infection episodes (negative binomial regression, Andersen-Gill model) was performed in 240 LTs. Four hundred twenty-eight infectious episodes (310 bacterial, 15 fungal, 65 cytomegalovirus [CMV]-related, and 38 viral non-CMV-related episodes) and 48 rejection episodes were recorded. The main bacterial infections were urinary (n = 82, 26%) and pneumonia (n = 69, 22%). LT recipients of MBL-deficient livers had a higher risk of bacterial infection (incidence rate ratio [IRR] 1.48 [95% confidence interval 1.04-2.09], p = 0.028), pneumonia (IRR 2.4 [95% confidence interval 1.33-4.33], p = 0.013), and septic shock (IRR 5.62 [95% confidence interval 1.92-16.4], p = 0.002) compared with recipients of MBL-deficient livers. The 1-year bacterial infection-related mortality was higher in recipients of MBL-deficient versus MBL-sufficient livers (65.8% vs. 56.1%, respectively; p = 0.0097). The incidence of rejection, viral, or fungal infection was similar in both groups. Recipient MBL2 genotype did not significantly increase the risk of bacterial infection. LT recipients of MBL-deficient livers have a higher risk of bacterial infection, pneumonia, septic shock, and 1-year bacterial infection-related mortality after LT.

Human immunodeficiency virus-infected liver transplant recipients with incidental hepatocellular carcinoma: A prospective multicenter nationwide cohort study

There is a lack of data on incidental hepatocellular carcinoma (iHCC) in the setting of liver transplantation (LT) in human immunodeficiency virus (HIV)-infected patients. This study aims to describe the frequency, histopathological characteristics, and outcomes of HIV+ LT recipients with iHCC from a Spanish multicenter cohort in comparison with a matched cohort of LT patients without HIV infection. A total of 15 (6%) out of 271 patients with HIV infection who received LT in Spain from 2002 to 2012 and 38 (5%) out of the 811 HIV- counterparts presented iHCC in liver explants (P = 0.58). Patients with iHCC constitute the present study population. All patients also had hepatitis C virus (HCV)-related cirrhosis. There were no significant differences in histopathological features of iHCC between the 2 groups. Most patients showed a small number and size of tumoral nodules, and few patients had satellite nodules, microvascular invasion, or poorly differentiated tumors. After a median follow-up of 49 months, no patient developed hepatocellular carcinoma (HCC) recurrence after LT. HIV+ LT recipients tended to have lower survival than their HIV- counterparts at 1 (73% versus 92%), 3 (67% versus 84%), and 5 years (50% versus 80%; P = 0.06). There was also a trend to a higher frequency of HCV recurrence as a cause of death in the former (33% versus 10%; P = 0.097). In conclusion, among LT recipients for HCV-related cirrhosis, the incidence and histopathological features of iHCC in HIV+ and HIV- patients were similar. However, post-LT survival was lower in HIV+ patients probably because of a more aggressive HCV recurrence. Liver Transplantation 23 645-651 2017 AASLD.

IFN-free therapy for HIV/HCV-coinfected patients within the liver transplant setting

OBJECTIVES

IFN-based therapy against hepatitis C recurrence after liver transplantation (LT) has poor effectiveness and tolerability. In HIV/HCV-coinfected liver transplant recipients, the results are even poorer. Here, we report our experience using direct antiviral agents (DAAs) in 11 consecutive coinfected patients within the LT setting.

METHODS

Four patients with compensated cirrhosis and hepatocellular carcinoma were treated while awaiting LT and seven patients received antiviral therapy due to severe hepatitis C recurrence after LT [fibrosing cholestatic hepatitis (n = 1), fibrosis stage ≥F3 (n = 2) and decompensated cirrhosis (n = 4)]. Patients were treated with different sofosbuvir-based regimens with or without ribavirin for 12 or 24 weeks.

RESULTS

Sustained virological response (SVR) was achieved in all patients. Two of the four patients treated while awaiting LT reached the time of transplant with undetectable HCV-RNA that remained undetectable 12 weeks after LT, one patient had detectable HCV-RNA at the time of transplant but achieved SVR after completing 12 weeks of therapy after LT and the last patient is still on the waiting list. Seven patients with severe post-LT hepatitis C recurrence were treated within 11-120 months after LT. In these patients, viral eradication was associated with an improvement in liver function and clinical decompensation. Tolerance to antiviral therapy was good and only four patients reported mild adverse events.

CONCLUSIONS

IFN-free regimens are effective and well tolerated in HIV/HCV-coinfected patients within the LT setting, but more data are needed to confirm our promising results and to establish the best treatment option in this population.

Does Fe(2+) in olivine-based interstellar grains play any role in the formation of H2? Atomistic insights from DFT periodic simulations

Using periodic DFT-D2 methods, atomistic simulations of interstellar H adsorption and H2 formation on a (010) Fe-containing olivine surface are presented. At variance with the (010) Mg2SiO4 surface and key to these processes are the large Fe/H interaction energies, suggesting that olivine surfaces are good reservoirs of H atoms for subsequent recombination to form H2.

Hepatic Infiltrates in Operational Tolerant Patients After Liver Transplantation Show Enrichment of Regulatory T Cells Before Proinflammatory Genes Are Downregulated

Immunosuppression can be discontinued from selected and stable patients after liver transplantation resulting in spontaneous operational tolerance (SOT), although the underlying mechanisms remain elusive. Thus, we analyzed serial liver biopsy specimens from adult liver recipients enrolled in a prospective multicenter immunosuppression withdrawal trial that used immunophenotyping and transcriptional profiling. Liver specimens were collected before the initiation of weaning, at the time of rejection, or at 1 and 3 years after complete drug discontinuation. Unexpectedly, the tolerated grafts developed portal tract expansion with increased T cell infiltration after immunosuppression withdrawal. This was associated with transient and preferential accumulation of CD4(+) FOXP3(+) cells and a trend toward upregulation of immune activation and regulatory genes, without signs of rejection. At the same time, no markers of endothelial damage or activation were noted. Portal infiltrates persisted at 3 years but were characterized by decreased expression of genes associated with chronic immunological damage. Further, SOT was not associated with a progressive liver fibrosis up to 5 years. These data suggest that SOT involves several mechanisms: a long-lasting local immune cell persistence with a transient regulatory T cells accumulation followed by a downregulation of immune-activated genes over years. These results have important implications for designs and follow-up of weaning trials.

Molecular Characterization of Acute Cellular Rejection Occurring During Intentional Immunosuppression Withdrawal in Liver Transplantation

Acute cellular rejection occurs frequently during the first few weeks following liver transplantation. During this period, its molecular phenotype is confounded by peri- and postoperative proinflammatory events. To unambiguously define the molecular profile associated with rejection, we collected sequential biological specimens from 55 patients at least 3 years after liver transplantation who developed rejection during trials of intentional immunosuppression withdrawal. We analyzed liver tissue and blood samples obtained before initiation of drug withdrawal and at rejection, alongside blood samples collected during the weaning process. Gene expression profiling was conducted using whole-genome microarrays and real-time polymerase chain reaction. Rejection resulted in distinct blood and liver tissue transcriptional changes in patients who were either positive or negative for hepatitis C virus (HCV). Gene expression changes were mostly independent from pharmacological immunosuppression, and their magnitude correlated with severity of histological damage. Differential expression of a subset of genes overlapped across all conditions. These were used to define a blood predictive model that accurately identified rejection in HCV-negative, but not HCV-positive, patients. Changes were detectable 1-2 mo before rejection was diagnosed. Our results provide insight into the molecular processes underlying acute cellular rejection in liver transplantation and help clarify the potential utility and limitations of transcriptional biomarkers in this setting.

Human immunodeficiency virus infection does not worsen prognosis of liver transplantation for hepatocellular carcinoma

The impact of human immunodeficiency virus (HIV) infection on patients undergoing liver transplantation (LT) for hepatocellular carcinoma (HCC) is uncertain. This study aimed to assess the outcome of a prospective Spanish nationwide cohort of HIV-infected patients undergoing LT for HCC (2002-2014). These patients were matched (age, gender, year of LT, center, and hepatitis C virus (HCV) or hepatitis B virus infection) with non-HIV-infected controls (1:3 ratio). Patients with incidental HCC were excluded. Seventy-four HIV-infected patients and 222 non-HIV-infected patients were included. All patients had cirrhosis, mostly due to HCV infection (92%). HIV-infected patients were younger (47 versus 51 years) and had undetectable HCV RNA at LT (19% versus 9%) more frequently than non-HIV-infected patients. No significant differences were detected between HIV-infected and non-HIV-infected recipients in the radiological characteristics of HCC at enlisting or in the histopathological findings for HCC in the explanted liver. Survival at 1, 3, and 5 years for HIV-infected versus non-HIV-infected patients was 88% versus 90%, 78% versus 78%, and 67% versus 73% (P = 0.779), respectively. HCV infection (hazard ratio = 7.90, 95% confidence interval 1.07-56.82) and maximum nodule diameter >3 cm in the explanted liver (hazard ratio = 1.72, 95% confidence interval 1.02-2.89) were independently associated with mortality in the whole series. HCC recurred in 12 HIV-infected patients (16%) and 32 non-HIV-infected patients (14%), with a probability of 4% versus 5% at 1 year, 18% versus 12% at 3 years, and 20% versus 19% at 5 years (P = 0.904). Microscopic vascular invasion (hazard ratio = 3.40, 95% confidence interval 1.34-8.64) was the only factor independently associated with HCC recurrence.

CONCLUSIONS

HIV infection had no impact on recurrence of HCC or survival after LT. Our results support the indication of LT in HIV-infected patients with HCC.

Liver Retransplantation in Patients With HIV-1 Infection: An International Multicenter Cohort Study

Liver retransplantation is performed in HIV-infected patients, although its outcome is not well known. In an international cohort study (eight countries), 37 (6%; 32 coinfected with hepatitis C virus [HCV] and five with hepatitis B virus [HBV]) of 600 HIV-infected patients who had undergone liver transplant were retransplanted. The main indications for retransplantation were vascular complications (35%), primary graft nonfunction (22%), rejection (19%), and HCV recurrence (13%). Overall, 19 patients (51%) died after retransplantation. Survival at 1, 3, and 5 years was 56%, 51%, and 51%, respectively. Among patients with HCV coinfection, HCV RNA replication status at retransplantation was the only significant prognostic factor. Patients with undetectable versus detectable HCV RNA had a survival probability of 80% versus 39% at 1 year and 80% versus 30% at 3 and 5 years (p = 0.025). Recurrence of hepatitis C was the main cause of death in the latter. Patients with HBV coinfection had survival of 80% at 1, 3, and 5 years after retransplantation. HIV infection was adequately controlled with antiretroviral therapy. In conclusion, liver retransplantation is an acceptable option for HIV-infected patients with HBV or HCV coinfection but undetectable HCV RNA. Retransplantation in patients with HCV replication should be reassessed prospectively in the era of new direct antiviral agents.

High expression of CD38, CD69, CD95 and CD154 biomarkers in cultured peripheral T lymphocytes correlates with an increased risk of acute rejection in liver allograft recipients

The mayor goal still outstanding into the solid organ transplantation field involves the search of surrogate biomarkers able to predict several clinical events, such as acute rejection (AR) or opportunistic infection. In the present multicenter study, a series of interesting surface antigens with important activator or inhibitory immune functions on cultured peripheral T cells were monitored in liver transplant recipients drawn at baseline and up to one year after transplantation. Sixty-four patients were included in the multicenter study during 3 years. Pre- and post-transplantation surface antigens levels displayed significant differences between AR and non acute rejection (NAR) groups, and also this differential expression was used to construct a risk predictive model based on a composite panel of outcome biomarkers (CD38, CD69, CD95 and CD154). The model was able to stratify these patients at high risk of AR. These preliminary results could provide basic information to improve the immunosuppressive treatment and it might better help to predict AR episodes.

High frequency of central memory regulatory T cells allows detection of liver recipients at risk of early acute rejection within the first month after transplantation

Several studies have analyzed the potential of T regulatory cells (Treg cells) as biomarkers of acute rejection (AR). The aim of the present multicenter study was to correlate the percentage of peripheral Treg cells in liver graft recipients drawn at baseline up to 12 months after transplantation with the presence of AR. The percentage of central memory (cm) Treg cells (CD4(+)CD25(high)CD45RO(+)CD62L(+)) was monitored at pre-transplant and at 1 and 2 weeks, and 1, 2, 3 and 6 months and 1 year post-transplantation. The same validation standard operating procedures were used in all participating centers. Fifteen patients developed AR (23.4%). Hepatitis C virus recurrence was observed in 16 recipients, who displayed low peripheral blood cmTreg levels compared with patients who did not. A steady increase of cmTregs was observed during the first month after transplantation with statistically significant differences between AR and non-AR patients. The high frequency of memory Treg cells allowed us to monitor rejection episodes during the first month post-transplantation. On the basis of these data, we developed a prediction model for assessing risk of AR that can provide clinicians with useful information for managing patients individually and customizing immunosuppressive therapies.

Clinical features and outcomes of tuberculosis in transplant recipients as compared with the general population: a retrospective matched cohort study

There are no previous studies comparing tuberculosis in transplant recipients (TRs) with other hosts. We compared the characteristics and outcomes of tuberculosis in TRs and patients from the general population. Twenty-two TRs who developed tuberculosis from 1996 through 2010 at a tertiary hospital were included. Each TR was matched by age, gender and year of diagnosis with four controls selected from among non-TR non-human immunodeficiency virus patients with tuberculosis. TRs (21 patients, 96%) had more factors predisposing to tuberculosis than non-TRs (33, 38%) (p <0.001). Pulmonary tuberculosis was more common in non-TRs (77 (88%) vs. 12 TRs (55%); p 0.001); disseminated tuberculosis was more frequent in TRs (five (23%) vs. four non-TRs (5%); p 0.005). Time from clinical suspicion of tuberculosis to definitive diagnosis was longer in TRs (median of 14 days) than in non-TRs (median of 0 days) (p <0.001), and invasive procedures were more often required (12 (55%) TRs and 15 (17%) non-TRs, respectively; p 0.001). Tuberculosis was diagnosed post-mortem in three TRs (14%) and in no non-TRs (p <0.001). Rates of toxicity associated with antituberculous therapy were 38% in TRs (six patients) and 10% (seven patients) in non-TRs (p 0.014). Tuberculosis-related mortality rates in TRs and non-TRs were 18% and 6%, respectively (p 0.057). The adjusted Cox regression analysis showed that the only predictor of tuberculosis-related mortality was a higher number of organs with tuberculosis involvement (adjusted hazard ratio 8.6; 95% CI 1.2-63). In conclusion, manifestations of tuberculosis in TRs differ from those in normal hosts. Post-transplant tuberculosis resists timely diagnosis, and is associated with a higher risk of death before a diagnosis can be made.

Outcome and management of HCV/HIV coinfection pre- and post-liver transplantation. A 2015 update

Liver transplantation is increasingly performed in selected HIV-infected patients in most developed countries, with excellent results reported in patients with liver diseases unrelated to HCV. In contrast, survival in HCV/HIV-coinfected liver recipients is poorer than in HCV-monoinfected patients, due to more aggressive recurrence of HCV and consequent graft loss and death. Results from American, French, and Spanish cohort studies showed a 5-year survival rate of only 50-55%. Therefore, it is debated whether liver transplantation should be offered to HCV/HIV-coinfected patients. Studies have shown that the variables more consistently associated with poor outcome are: (1) the use of old or HCV-positive donors, (2) dual liver-kidney transplantation, (3) recipients with very low body mass index and (4) less site experience. However, the most effective factor influencing transplantation outcome is the successful treatment of HCV recurrence with anti-HCV. Survival is 80% in patients whose HCV infection resolves. Unfortunately, the rates of sustained virological response with pegylated-interferon plus ribavirin in coinfected recipients are low, particularly for genotype 1 (only 10%). Here we present a non-systematic review of the literature based on our own experience in different liver transplant scenarios. This review covers selection criteria in HIV-infected patients, pre- and post-LT management, donor selection, anti-HCV treatment, drug interactions with antiretrovirals and anti-HCV direct antiviral agents, hepatocellular carcinoma, and liver retransplantation. Recommendations are rated. Finally, we explain how the introduction of new effective and more tolerable direct antiviral agents may improve significantly the outcome of HCV/HIV-coinfected liver recipients.

HCV-induced immune responses influence the development of operational tolerance after liver transplantation in humans

Pathogen-induced immune responses prevent the establishment of transplantation tolerance in experimental animal models. Whether this occurs in humans as well remains unclear. The development of operational tolerance in liver transplant recipients with chronic hepatitis C virus (HCV) infection allows us to address this question. We conducted a clinical trial of immunosuppression withdrawal in HCV-infected adult liver recipients to elucidate (i) the mechanisms through which allograft tolerance can be established in the presence of an ongoing inflammatory response and (ii) whether anti-HCV heterologous immune responses influence this phenomenon. Of 34 enrolled liver recipients, drug withdrawal was successful in 17 patients (50%). Tolerance was associated with intrahepatic overexpression of type I interferon and immunoregulatory genes and with an expansion of exhausted PD1/CTLA4/2B4-positive HCV-specific circulating CD8(+) T cells. These findings were already present before immunosuppression was discontinued and were specific for HCV infection. In contrast, the magnitude of HCV-induced proinflammatory gene expression and the breadth of anti-HCV effector T cell responses did not influence drug withdrawal outcome. Our data suggest that in humans, persistent viral infections exert immunoregulatory effects that could contribute to the restraining of alloimmune responses, and do not necessarily preclude the development of allograft tolerance.

Pegylated interferon plus ribavirin in HIV-infected patients with recurrent hepatitis C after liver transplantation: a prospective cohort study

BACKGROUND & AIMS

The aim of this study was to evaluate the results of treatment with pegylated interferon and ribavirin for the recurrence of hepatitis C after liver transplantation in HCV/HIV-coinfected patients.

METHODS

This was a prospective, multicentre cohort study, including 78 HCV/HIV-coinfected liver transplant patients who received treatment for recurrent hepatitis C. For comparison, we included 176 matched HCV-monoinfected patients who underwent liver transplantation during the same period of time at the same centres and were treated for recurrent hepatitis C.

RESULTS

Antiviral therapy was discontinued prematurely in 56% and 39% (p = 0.016), mainly because of toxicity (22% and 11%, respectively; p=0.034). Sustained virological response (SVR) was achieved in 21% of the coinfected patients and in 36% of monoinfected patients (p = 0.013). For genotype 1, SVR rates were 10% and 33% (p = 0.002), respectively; no significant differences were observed for the other genotypes. A multivariate analysis based on the whole series identified HIV-coinfection as an independent predictor of lack of SVR (OR, 0.17; 95% CI, 0.06-0.42). Other predictors of SVR were donor age, pretreatment HCV viral load, HCV genotype, and early virological response. SVR was associated with a significant improvement in survival: 5-year survival after antiviral treatment was 79% for HCV/HIV-coinfected patients with SVR vs. 43% for those without (p = 0.02) and 92% vs. 60% in HCV-monoinfected patients (p < 0.001), respectively.

CONCLUSIONS

The response to pegylated interferon and ribavirin was poorer in HCV/HIV-coinfected liver recipients, particularly those with genotype 1. However, when SVR was achieved, survival of coinfected patients increased significantly.

Polyethylene glycol rinse solution: An effective way to prevent ischemia-reperfusion injury

AIM: To test whether a new rinse solution containing polyethylene glycol 35 (PEG-35) could prevent ischemia-reperfusion injury (IRI) in liver grafts.

METHODS: Sprague-Dawley rat livers were stored in University of Wisconsin preservation solution and then washed with different rinse solutions (Ringer’s lactate solution and a new rinse solution enriched with PEG-35 at either 1 or 5 g/L) before ex vivo perfusion with Krebs-Heinseleit buffer solution. We assessed the following: liver injury (transaminase levels), mitochondrial damage (glutamate dehydrogenase activity), liver function (bile output and vascular resistance), oxidative stress (malondialdehyde), nitric oxide, liver autophagy (Beclin-1 and LCB3) and cytoskeleton integrity (filament and globular actin fraction); as well as levels of metalloproteinases (MMP2 and MMP9), adenosine monophosphate-activated protein kinase (AMPK), heat shock protein 70 (HSP70) and heme oxygenase 1 (HO-1).

RESULTS: When we used the PEG-35 rinse solution, reduced hepatic injury and improved liver function were noted after reperfusion. The PEG-35 rinse solution prevented oxidative stress, mitochondrial damage, and liver autophagy. Further, it increased the expression of cytoprotective heat shock proteins such as HO-1 and HSP70, activated AMPK, and contributed to the restoration of cytoskeleton integrity after IRI.

CONCLUSION: Using the rinse solution containing PEG-35 was effective for decreasing liver graft vulnerability to IRI.

Somatostatin therapy protects porcine livers in small-for-size liver transplantation

Small-for-size (SFS) injury occurs in partial liver transplantation due to several factors, including excessive portal inflow and insufficient intragraft responses. We aim to determine the role somatostatin plays in reducing portal hyperperfusion and preventing the cascade of deleterious events produced in small grafts. A porcine model of 20% liver transplantation is performed. Perioperatively treated recipients receive somatostatin and untreated controls standard intravenous fluids. Recipients are followed for up to 5 days. In vitro studies are also performed to determine direct protective effects of somatostatin on hepatic stellate cells (HSC) and sinusoidal endothelial cells (SEC). At reperfusion, portal vein flow (PVF) per gram of tissue increased fourfold in untreated animals versus approximately threefold among treated recipients (p = 0.033). Postoperatively, markers of hepatocellular, SEC and HSC injury were improved among treated animals. Hepatic regeneration occurred in a slower but more orderly fashion among treated grafts; functional recovery was also significantly better. In vitro studies revealed that somatostatin directly reduces HSC activation, though no direct effect on SEC was found. In SFS transplantation, somatostatin reduces PVF and protects SEC in the critical postreperfusion period. Somatostatin also exerts a direct cytoprotective effect on HSC, independent of changes in PVF.

Silent information regulator 1 protects the liver against ischemia-reperfusion injury: implications in steatotic liver ischemic preconditioning

Ischemia-reperfusion (IR) injury is an important problem in liver surgery especially when steatosis is present. Ischemic preconditioning (PC) is the only surgical strategy that has been applied in patients with steatotic livers undergoing warm ischemia. Silent information regulator 1 (SIRT1) is a histone deacetylase that regulates various cellular processes. This study evaluates the SIRT1 implication in PC in fatty livers. Homozygous (Ob) Zucker rats were subjected to IR and IR + PC. An additional group treated with sirtinol or EX527 (SIRT1 inhibitors) before PC was also realized. Liver injury and oxidative stress were evaluated. SIRT1 protein levels and activity, as well as other parameters involved in PC protective mechanisms (adenosine monophosphate protein kinase, eNOS, HSP70, MAP kinases, apoptosis), were also measured. We demonstrated that the protective effect of PC was due in part to SIRT1 induction, as SIRT1 inhibition resulted in increased liver injury and abolished the beneficial mechanisms of PC. In this study, we report for the first time that SIRT1 is involved in the protective mechanisms induced by hepatic PC in steatotic livers.

Formaldehyde chemistry in cometary ices: the case of HOCH2OH formation

Laboratory experiments devoted to simulate the chemistry occurring in interstellar and cometary ice analogues are of paramount importance to understand the formation of complex organic molecules that are detected throughout the universe.

Prospective multicenter clinical trial of immunosuppressive drug withdrawal in stable adult liver transplant recipients

Lifelong immunosuppression increases morbidity and mortality in liver transplantation. Discontinuation of immunosuppressive drugs could lessen this burden, but the safety, applicability, and clinical outcomes of this strategy need to be carefully defined. We enrolled 102 stable liver recipients at least 3 years after transplantation in a single-arm multicenter immunosuppression withdrawal trial. Drugs were gradually discontinued over a 6 to 9-month period. The primary endpoint was the development of operational tolerance, defined as successful immunosuppressive drug cessation maintained for at least 12 months with stable graft function and no histopathologic evidence of rejection. Out of the 98 recipients evaluated, 57 rejected and 41 successfully discontinued all immunosuppressive drugs. In nontolerant recipients rejection episodes were mild and resolved over 5.6 months (two nontolerant patients still exhibited mild gradually improving cholestasis at the end of follow-up). In tolerant recipients no progressive clinically significant histological damage was apparent in follow-up protocol biopsies performed up to 3 years following drug withdrawal. Tolerance was independently associated with time since transplantation (odds ratio [OR] 1.353; P = 0.0001), recipient age (OR 1.073; P = 0.009), and male gender (OR 4.657; P = 0.016). A predictive model incorporating the first two clinical variables identified subgroups of recipients with very high (79%), intermediate (30%-38%), and very low (0%) likelihood of successful withdrawal.

CONCLUSION

When conducted at late timepoints after transplantation, immunosuppression withdrawal is successful in a high proportion of carefully selected liver recipients. A combination of clinical parameters could be useful to predict the success of this strategy. Additional prospective studies are now needed to confirm these results and to validate clinically applicable diagnostic biomarkers.

Bortezomib enhances fatty liver preservation in Institut George Lopez-1 solution through adenosine monophosphate activated protein kinase and Akt/mTOR pathways

OBJECTIVES

The aim of this study is to investigate the protective mechanisms induced by bortezomib added to Institut George Lopez (IGL)-1 preservation solution to protect steatotic livers against cold ischaemia reperfusion injury and to examine whether these mechanisms occur through the activation of adenosine monophosphate activated protein kinase (AMPK), Akt/mTOR pathways.

METHODS

Steatotic livers from obese rats were preserved for 24 h (at 4 °C) in IGL-1 solution with or without bortezomib (100 nM) or pretreated with AMPK inhibitor adenine 9-α-D-arabinofuranoside and preserved in IGL-1 + bortezomib. Livers were then perfused for 2 h at 37 °C. Liver injury (alanine aminotransferase/aspartate aminotransferase) and function (bile production and vascular resistance) were measured. Also, Akt/mTOR, phosphorylated AMPK (pAMPK) and apoptosis were determined by Western blot analyses.

KEY FINDINGS

Bortezomib addition to IGL-1 solution significantly reduced steatotic liver injury, improved graft function and decreased liver apoptosis. These benefits were diminished by the pretreatment of obese rats with AMPK inhibitor Ara. Western blot analyses showed a significant increase in pAMPK after ischaemia and reperfusion. We also observed a significant phosphorylation of Akt in IGL-1 +bortezomib group that, in turn, induced the phosphorylation of mTOR and glycogen synthase kinase 3β.

CONCLUSIONS

Bortezomib, at low and non toxic concentration, is a promising additive to IGL-1 solution for steatotic liver preservation. Its protective effect is due to the activation of AMPK and Akt/mTOR pathways.

Prospective evaluation of single-operator peroral cholangioscopy in liver transplant recipients requiring an evaluation of the biliary tract

In this descriptive study, we examined the role of single-operator cholangioscopy (SOC) in the evaluation of biliary complications after liver transplantation (LT). We prospectively included adult recipients of deceased donor LT who were referred for endoscopic retrograde cholangiopancreatography between June 2009 and July 2011. All patients underwent SOC with biopsy of the biliary anastomosis. Sixteen patients were included: 12 with biliary anastomotic strictures (ASs), 2 with common bile duct stones, 1 with a bile leak, and 1 with sphincter of Oddi dysfunction. Patients with ASs displayed 1 of 2 patterns: (A) mild erythema (n = 9) or (B) edema, ulceration, and sloughing (n = 3). Those without ASs displayed a pale mucosa with mild edema at the anastomosis. Patients with ASs and pattern B required a longer period of stenting than patients with pattern A (457 versus 167 days, P = 0.02). In addition, patients with pattern A had a better response and better resolution of their strictures with endoscopic therapy than those with pattern B (66% versus 33%, P = 0.13). Histological examinations of ASs showed nonspecific intraepithelial inflammation in patients with patterns A and B. Biopsy samples from patients without ASs showed normal columnar epithelial bile duct cells. The total cholangioscopy time for all procedures was 26.8 ± 10.1 minutes. In conclusion, SOC in LT recipients is feasible and allows adequate visualization and tissue sampling of ASs and bile ducts. Two distinct visual patterns that are easily identified with SOC may help to predict the outcomes of endoscopic therapy in patients with biliary complications after LT.

Intracellular IFN-γ and IL-2 expression monitoring as surrogate markers of the risk of acute rejection and personal drug response in de novo liver transplant recipients

Biomarker monitoring is needed in transplantation to reflect individual response to immunosuppressive drugs and graft outcome. We evaluated intracellular expression and soluble production of interferon-(IFN)-γ and interleukin-(IL)-2 as predictive biomarkers of acute rejection (AR) and personal drug response. Pharmacokinetic-pharmacodynamic profiles were determined in 47 de novo liver recipients treated with tacrolimus, mycophenolate mofetil and prednisone. Of the 47 patients, AR occurred in nine. There were no differences in drug concentrations between rejectors and non-rejectors. A pre-transplantation cut-off value of 55.80% for %CD8(+)-IFN-γ(+) identified patients at high risk of AR with a sensitivity of 75% and a specificity of 82%. In the first week post-transplantation, patients with a % inhibition for soluble IFN-γ, %CD8(+)-IFN-γ(+) and %CD8(+)-IL2(+) lower than 40% developed AR, showing low susceptibility to immunosuppressive drugs. Therefore, effector-T-cell response monitoring may help physicians to identify personal response to treatment and patients at high risk of AR.

Tauroursodeoxycholic acid affects PPARγ and TLR4 in Steatotic liver transplantation

Numerous steatotic livers are discarded for transplantation because of their poor tolerance to ischemia-reperfusion (I/R). We examined whether tauroursodeoxycholic acid (TUDCA), a known inhibitor of endoplasmic reticulum (ER) stress, protects steatotic and nonsteatotic liver grafts preserved during 6 h in University of Wisconsin (UW) solution and transplanted. The protective mechanisms of TUDCA were also examined. Neither unfolded protein response (UPR) induction nor ER stress was evidenced in steatotic and nonsteatotic liver grafts after 6 h in UW preservation solution. TUDCA only protected steatotic livers grafts and did so through a mechanism independent of ER stress. It reduced proliferator-activated receptor-γ (PPARγ) and damage. When PPARγ was activated, TUDCA did not reduce damage. TUDCA, which inhibited PPARγ, and the PPARγ antagonist treatment up-regulated toll-like receptor 4 (TLR4), specifically the TIR domain-containing adaptor inducing IFNβ (TRIF) pathway. TLR4 agonist treatment reduced damage in steatotic liver grafts. When TLR4 action was inhibited, PPARγ antagonists did not protect steatotic liver grafts. In conclusion, TUDCA reduced PPARγ and this in turn up-regulated the TLR4 pathway, thus protecting steatotic liver grafts. TLR4 activating-based strategies could reduce the inherent risk of steatotic liver failure after transplantation.

[The biliary complications in live donor liver transplant do not affect the long-term results]

INTRODUCTION

Living donor liver transplantation (LDLT) is an effective treatment for patients with terminal chronic liver disease, despite the high incidence of biliary complications. The objective is to evaluate the results and long-term impact of biliary complications after THDV.

PATIENTS AND METHODS

From 2000 to 2010, 70 right lobe LDLT were performed. Biliary complications (leakage and stenosis) of the 70 LDLT recipients were collected prospectively and analyzed retrospectively.

RESULTS

A total of 39 patients (55.7%) had some type of biliary complication. Twenty nine presented a leak, and of these, 14 subsequently developed a stricture. In addition, 10 patients had a stenosis without prior leakage. The median time to onset of stenosis was almost a year. Patients with previous biliary leakage were more likely to develop stenosis (58% vs. 29.5% at 5 years, P=.05). With a median follow up of 80 months, 70.8% of patients were successfully treated by interventional radiology. After excluding early mortality, there were no differences in survival according to biliary complications. A decrease of biliary complications was observed in the last 35 patients compared with the first 35.

CONCLUSIONS

LDLT is associated with a high incidence of biliary complications. However, long-term outcome of patients is not affected. After a median follow-up time of nearly seven years, no differences were found in survival according to the presence of biliary complications.

Retinol binding protein 4 and retinol in steatotic and nonsteatotic rat livers in the setting of partial hepatectomy under ischemia/reperfusion

Steatotic livers show increased hepatic damage and impaired regeneration after partial hepatectomy (PH) under ischemia/reperfusion (I/R), which is commonly applied in clinical practice to reduce bleeding. The known function of retinol-binding protein 4 (RBP4) is to transport retinol in the circulation. We examined whether modulating RBP4 and/or retinol could protect steatotic and nonsteatotic livers in the setting of PH under I/R. Steatotic and nonsteatotic livers from Zucker rats were subjected to PH (70%) with 60 minutes of ischemia. RBP4 and retinol levels were measured and altered pharmacologically, and their effects on hepatic damage and regeneration were studied after reperfusion. Decreased RBP4 levels were observed in both liver types, whereas retinol levels were reduced only in steatotic livers. RBP4 administration exacerbated the negative consequences of liver surgery with respect to damage and liver regeneration in both liver types. RBP4 affected the mobilization of retinol from steatotic livers, and this revealed actions of RBP4 independent of simple retinol transport. The injurious effects of RBP4 were not due to changes in retinol levels. Treatment with retinol was effective only for steatotic livers. Indeed, retinol increased hepatic injury and impaired liver regeneration in nonsteatotic livers. In steatotic livers, retinol reduced damage and improved regeneration after surgery. These benefits of retinol were associated with a reduced accumulation of hepatocellular fat. Thus, strategies based on modulating RBP4 could be ineffective and possibly even harmful in both liver types in the setting of PH under I/R. In terms of clinical applications, a retinol pretreatment might open new avenues for liver surgery that specifically benefit the steatotic liver.

Liver retransplantation in HIV-infected patients: a prospective cohort study

Information regarding liver retransplantation in HIV-infected patients is scant. Data from 14 HIV-infected patients retransplanted between 2002 and 2011 in Spain (6% retransplantation rate) were analyzed and compared with those from 157 matched HIV-negative retransplanted patients. In HIV-infected patients, early (≤30 days) retransplantation was more frequently indicated (57% vs. 29%; p = 0.057), and retransplantation for HCV recurrence was less frequently indicated (7% vs. 37%; p = 0.036). Survival probability after retransplantation in HIV-positive patients was lower than in HIV-negative patients, 42% versus 64% at 3 years, although not significantly (p = 0.160). Among HIV-infected patients, those with undetectable HCV RNA at retransplantation and those with late (>30 days) retransplantation showed better 3-year survival probability (80% and 67%, respectively), similar to that in their respective HIV-negative counterparts (72% and 70%). In HIV-infected and HIV-negative patients, 3-year survival probability in those with positive HCV RNA at retransplantation was 22% versus 65% (p = 0.008); in those with early retransplantation, 3-year survival probability was 25% versus 56% (p = 0.282). HIV infection was controlled with antiretroviral therapy after retransplantation. In conclusion, HIV-infected patients taken as a whole have unsatisfactory survival after liver retransplantation, although patients with undetectable HCV RNA at retransplantation or undergoing late retransplantation show a more favorable outcome.

New concepts and best practices for management of pre- and post-transplantation cancer

Solid-organ transplant recipients are at increased risk of developing cancer compared with the general population. Tumours can arise de novo, as a recurrence of a preexisting malignancy, or from the donated organ. The ATOS (Aula sobre Trasplantes de Órganos Sólidos; the Solid-Organ Transplantation Working Group) group, integrated by Spanish transplant experts, meets annually to discuss current advances in the field. In 2011, the 11th edition covered a range of new topics on cancer and transplantation. In this review we have highlighted the new concepts and best practices for managing cancer in the pre-transplant and post-transplant settings that were presented at the ATOS meeting. Immunosuppression plays a major role in oncogenesis in the transplant recipient, both through impaired immunosurveillance and through direct oncogenic activity. It is possible to transplant organs obtained from donors with a history of cancer as long as an effective minimization of malignancy transmission strategy is followed. Tumour-specific wait-periods have been proposed for the increased number of transplantation candidates with a history of malignancy; however, the patient's individual risk of death from organ failure must be taken into consideration. It is important to actively prevent tumour recurrence, especially the recurrence of hepatocellular carcinoma in liver transplant recipients. To effectively manage post-transplant malignancies, it is essential to proactively monitor patients, with long-term intensive screening programs showing a reduced incidence of cancer post-transplantation. Proposed management strategies for post-transplantation malignancies include viral monitoring and prophylaxis to decrease infection-related cancer, immunosuppression modulation with lower doses of calcineurin inhibitors, and addition of or conversion to inhibitors of the mammalian target of rapamycin.

Outcome of HCV/HIV-coinfected liver transplant recipients: a prospective and multicenter cohort study

Eighty-four HCV/HIV-coinfected and 252-matched HCV-monoinfected liver transplant recipients were included in a prospective multicenter study. Thirty-six (43%) HCV/HIV-coinfected and 75 (30%) HCV-monoinfected patients died, with a survival rate at 5 years of 54% (95% CI, 42-64) and 71% (95% CI, 66 to 77; p = 0.008), respectively. When both groups were considered together, HIV infection was an independent predictor of mortality (HR, 2.202; 95% CI, 1.420-3.413 [p < 0.001]). Multivariate analysis of only the HCV/HIV-coinfected recipients, revealed HCV genotype 1 (HR, 2.98; 95% CI, 1.32-6.76), donor risk index (HR, 9.48; 95% CI, 2.75-32.73) and negative plasma HCV RNA (HR, 0.14; 95% CI, 0.03-0.62) to be associated with mortality. When this analysis was restricted to pretransplant variables, we identified three independent factors (HCV genotype 1, pretransplant MELD score and centers with <1 liver transplantation/year in HIV-infected patients) that allowed us to identify a subset of 60 (71%) patients with a similar 5-year prognosis (69%[95% CI, 54-80]) to that of HCV-monoinfected recipients. In conclusion, 5-year survival in HCV/HIV-coinfected liver recipients was lower than in HCV-monoinfected recipients, although an important subset with a favorable prognosis was identified in the former.

Risk factors and outcomes of failed endoscopic retrograde cholangiopancreatography in liver transplant recipients with anastomotic biliary strictures: a case-control study

Anastomotic strictures (ASs) of the biliary duct after liver transplantation (LT) are primarily managed with endoscopic retrograde cholangiopancreatography (ERCP), but in some cases, this fails because of difficulties in passing the strictures. The aim of this case-control study was to examine specific risk factors for initial ERCP failure and the outcomes of percutaneous transhepatic cholangiography (PTC) as a second-line approach in LT recipients with ASs. Between January 2002 and December 2010, we identified LT recipients with ASs who experienced initial ERCP failure (which was defined as the inability to traverse the AS with guidewires in 2 or more consecutive procedures). A period-matched control group (ratio = 1:2) with ASs and initial ERCP success was analyzed. Preoperative, intraoperative, postoperative, and endoscopic variables were evaluated as risk factors. The outcomes of PTC and the need for hepaticojejunostomy (HJ) or retransplantation were evaluated. Seventeen cases who experienced initial ERCP failure were compared with 34 controls. The median times from LT to ERCP were similar (8.7 months for cases and 8.6 months for controls, P = not significant). A multivariate analysis revealed that previous bile leaks [odds ratio (OR) = 6.07, 95% confidence interval (CI) = 1.0-36.5] and more than 4 U of intraoperatively transfused red blood cells (OR = 11.51, 95% CI = 1.9-71.2) were independent risk factors for failure. PTC was an effective second-line treatment in only 3 of 12 cases (25%). The need for HJ was more frequent for the cases (13/17 or 76.5%) versus the controls (7/34 or 20.6%, P < 0.001). One patient in each group underwent retransplantation (P = not significant). In conclusion, previous bile leaks and high packed red blood cell transfusion requirements during surgery are risk factors for initial ERCP failure in LT recipients with ASs. A high proportion of these patients will need surgery as their final therapy.

Applicability and results of Maastricht type 2 donation after cardiac death liver transplantation

Maastricht type 2 donation after cardiac death (DCD) donors suffer sudden and unexpected cardiac arrest, typically outside the hospital; they have significant potential to expand the donor pool. Herein, we analyze the results of transplanted livers and all potential donors treated under our type 2 DCD protocol. Cardiac arrest was witnessed; potential donors arrived at the hospital after attempts at resuscitation had failed. Death was declared based on the absence of cardiorespiratory activity during a 5-min no-touch period. Femoral vessels were cannulated to establish normothermic extracorporeal membrane oxygenation, which was maintained until organ recovery. From April 2002 to December 2010, there were 400 potential donors; 34 liver transplants were performed (9%). Among recipients, median age, model for end-stage liver disease and cold and reperfusion warm ischemic times were 55 years (49-60), 19 (14-21) and 380 (325-430) and 30 min (26-35), respectively. Overall, 236 (59%) and 130 (32%) livers were turned down due to absolute and relative contraindications to donate, respectively. One-year recipient and graft survivals were 82% and 70%, respectively (median follow-up 24 months). The applicability of type 2 DCD liver transplant was <10%; however, with better preservation technology and expanded transplant criteria, we may be able to improve this figure significantly.

Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation

Following organ transplantation, lifelong immunosuppressive therapy is required to prevent the host immune system from destroying the allograft. This can cause severe side effects and increased recipient morbidity and mortality. Complete cessation of immunosuppressive drugs has been successfully accomplished in selected transplant recipients, providing proof of principle that operational allograft tolerance is attainable in clinical transplantation. The intra-graft molecular pathways associated with successful drug withdrawal, however, are not well defined. In this study, we analyzed sequential blood and liver tissue samples collected from liver transplant recipients enrolled in a prospective multicenter immunosuppressive drug withdrawal clinical trial. Before initiation of drug withdrawal, operationally tolerant and non-tolerant recipients differed in the intra-graft expression of genes involved in the regulation of iron homeostasis. Furthermore, as compared with non-tolerant recipients, operationally tolerant patients exhibited higher serum levels of hepcidin and ferritin and increased hepatocyte iron deposition. Finally, liver tissue gene expression measurements accurately predicted the outcome of immunosuppressive withdrawal in an independent set of patients. These results point to a critical role for iron metabolism in the regulation of intra-graft alloimmune responses in humans and provide a set of biomarkers to conduct drug-weaning trials in liver transplantation.

Comparison of transcriptional and blood cell-phenotypic markers between operationally tolerant liver and kidney recipients

A proportion of transplant recipients can spontaneously accept their grafts in the absence of immunosuppression (operational tolerance). Previous studies identified blood transcriptional and cell-phenotypic markers characteristic of either liver or kidney tolerant recipients. However, the small number of patients analyzed and the use of different transcriptional platforms hampered data interpretation. In this study we directly compared samples from kidney and liver tolerant recipients in order to identify potential similarities in immune-related parameters. Liver and kidney tolerant recipients differed in blood expression and B-cell immunophenotypic patterns and no significant overlaps were detectable between them. Whereas some recipients coincided in specific NK-related transcripts, this observation was not reproducible in all cohorts analyzed. Our results reveal that certain immune features, but not others, are consistently present across all cohorts of operationally tolerant recipients. This provides a set of reproducible biomarkers that should be explored in future large-scale immunomonitoring trials.

Cyclic adenosine 3',5'-monophosphate in rat steatotic liver transplantation

Numerous steatotic livers are discarded as unsuitable for transplantation (TR) because of their poor tolerance of ischemia/reperfusion (I/R). Cyclic adenosine 3',5'-monophosphate (cAMP)-elevating agents protect against I/R injury both in nonsteatotic livers that have been removed from non-heart-beating donors and subjected to warm ischemia or cold ischemia (CIS) and in perfused, isolated livers. Ischemic preconditioning (PC), which is based on brief periods of I/R, protects steatotic liver grafts, but the mechanism that is responsible is poorly understood. This study examines the role of cAMP in the vulnerability shown by steatotic livers to TR-associated I/R injury and the benefits of PC in this situation. Steatotic livers with or without PC were transplanted into Zucker rats. The hepatic levels of cAMP were measured and altered pharmacologically. Our results indicate that the cAMP levels in the nonsteatotic liver grafts were similar to those found in a sham group. However, high cAMP levels were observed in steatotic liver grafts. The blockage of cAMP generation by adenylate cyclase inhibitor pre-treatment or PC had the following results: reduced hepatic injury and increased survival of steatotic graft recipients; greater preservation of adenosine triphosphate (ATP) and reduced lactate accumulation throughout CI. This blockade of cAMP by a nitric oxide-dependent mechanism protected steatotic liver grafts against oxidative stress and microvascular disorders after reperfusion. In conclusion, cAMP blocking-based strategies could protect patients against the inherent risk of steatotic liver failure after TR.

How long should initiation of calcineurin inhibitors be delayed to protect renal function in liver transplantation?

BACKGROUND AND AIM

Delayed introduction of calcineurin inhibitors (CNI) in liver transplantation (OLT) seeks to protect renal function, although the optimal length of the delay is not well established. The aim of this study was to analyze the effects on renal function of CNI initiation on different days after OLT.

METHODS

We reviewed the charts of 260 OLT recipients. Group D1-a (n = 36) underwent the standard initial immunosuppression at our center: namely, CNI introduction on day 1 with further daily administration to achieve target levels of 8 to 15 ng/mL for tacrolimus or 150 to 300 ng/mL for cyclosporine. Due to renal concerns, 126 patients (group D1-b) had CNI introduced on day 1 either not daily or at doses to achieve less than the target on at least two occasions. In 43 patients (group D2), CNI were introduced on day 2 in 23 on day 3 (group D3), in 12 on day 4 (group D4), and at least at day 5 in 20 others (group D5). In periods without CNI treatment, patients received mycophenolate mofetil. Steroids were administered to all patients. The study period included the first 3 months post-OLT. Renal function was estimated as creatinine clearance (CrCl) using the Cockcroft-Gault equation.

RESULTS

Changes in CrCl from pre-OLT to month 3 were -19% ± 28% in group D1-a; -27% ± 19% in group D1-b; -29% ± 19% in group D2; -23% ± 26% in group D3; -4% ± 38% in group D4, and +4% ± 33% in group D5 (P < .05 vs groups D1-a, D1-b, D2, and D3). On multivariate analysis, CNI introduction at day ≥ 5 was protective for kidneys when adjusted for other variables that potentially influence renal function.

CONCLUSION

CNI should be introduced at day 5 after OLT to protect renal function.

Decompression of the portal bed and twice-baseline portal inflow are necessary for the functional recovery of a "small-for-size" graft

BACKGROUND

In partial liver transplant, a reduction in the intrahepatic vascular bed produces a rise in the portal vein flow and the portal venous pressure gradient, leading to endothelial and, thereby, hepatocellular injury and death in a process known as "small-for-size" (SFS) syndrome.

OBJECTIVE

To demonstrate that a calibrated portocaval shunt prevents superfluous inflow in a porcine model of SFS transplant.

METHODS

Donor pigs (15-20 kg) underwent 70% hepatectomy. In 2 groups, a 6 mm (S6) (n = 6) or 12 mm (S12) (n = 6) Gore-Tex shunt was placed between the portal vein and infrahepatic inferior vena cava. In a third group, no portocaval shunt was placed (SFS) (n = 17). Grafts were stored for 5 hours at 4°C and then transplanted into recipients (30-35 kg).

RESULTS

Five-day survival was 29% in SFS, 100% in S6, and 0 in S12. Postreperfusion portal vein flow was 4-, 2-, and 1-times flow at baseline in SFS, S6, and S12, respectively. With respect to portal venous pressure gradient, both the 6- and 12-mm shunts effectively decompressed the portal bed. Aspartate aminotransferase and bilirubin rose and the Quick prothrombin time fell in all animals after reperfusion but improved significantly by day 5 in S6. Serum levels of endothelin-1 remained elevated in SFS and S12 but returned to baseline by 12 hours in S6: 2.76 (2.05-4.08) and 2.04 (1.97-2.12) versus 0.43 (0.26-0.50) pg/mL, respectively (P < 0.05 for both comparisons).

CONCLUSIONS

A calibrated portocaval shunt that maintains portal vein flow about twice its baseline value produces a favorable outcome after SFS liver transplantation, avoiding endothelial injury due to portal hyperperfusion or to hypoperfusion because of excess shunting.

Targeting cholesterol at different levels in the mevalonate pathway protects fatty liver against ischemia-reperfusion injury

BACKGROUND & AIMS

Liver steatosis enhances ischemia/reperfusion (I/R) injury and is considered a primary factor in graft failure after liver transplantation. Although previous reports have shown a role for qualitative steatosis (macrovesicular vs. microvesicular) in hepatic I/R injury, no studies have compared side by side the specific contribution of individual lipids accumulating in fatty liver to I/R damage.

METHODS

We used nutritional and genetic models of micro and macrovesicular fatty livers exhibiting specific lipid profiles to assess their susceptibility to normothermic I/R injury.

RESULTS

Unlike choline-deficient (CD) diet-fed mice, characterized by predominant liver triglycerides/free fatty acids (TG/FFA) accumulation, mice fed a cholesterol-enriched (HC) diet, which exhibited enhanced hepatic cholesterol loading in mitochondria, were highly sensitive to I/R-induced liver injury. In vivo two-photon confocal imaging revealed enhanced mitochondrial depolarization and generation of reactive oxygen species following hepatic I/R in HC-fed but not in CD-fed mice, consistent with decreased mitochondrial GSH (mGSH) observed in HC-fed mice. Moreover, ob/ob mice, characterized by increased hepatic TG, FFA, and cholesterol levels, were as sensitive to I/R-mediated liver injury as mice fed the HC diet. Livers from ob/ob mice displayed increased StAR expression and mitochondrial cholesterol accumulation, resulting in mGSH depletion. Interestingly, atorvastatin therapy or squalene synthase inhibition in vivo attenuated StAR overexpression, mitochondrial cholesterol loading, and mGSH depletion, protecting ob/ob mice from I/R-mediated liver injury.

CONCLUSIONS

Cholesterol accumulation, particularly in mitochondria, sensitizes to hepatic I/R injury, and thus represents a novel target to prevent the enhanced damage of steatotic livers to I/R-mediated damage.

Retinol-binding protein 4 and peroxisome proliferator-activated receptor-γ in steatotic liver transplantation

Numerous steatotic livers are discarded for transplantation because of their poor tolerance of ischemia-reperfusion (I/R). The injurious effects of retinol-binding protein 4 (RBP4) in various pathologies are well documented. RBP4 levels are reduced by peroxisome proliferator-activated receptor-γ (PPARγ) agonists. Strategies aimed at increasing PPARγ protect steatotic livers under warm ischemia. Ischemic preconditioning (PC) based on brief periods of I/R protects steatotic liver grafts against I/R injury, but the responsible mechanism is poorly understood. We examined the roles of RBP4 and PPARγ in I/R injury associated with steatotic liver transplantation and the benefits of PC in such situations. We report that RBP4 and PPARγ expression levels in nonsteatotic livers were similar to those found in the sham group. However, reduced RBP4 and increased PPARγ levels were observed in steatotic livers. Treatment with either RBP4 or a PPARγ antagonist was effective only in steatotic livers. PC, which increased RBP4 levels, and RBP4 treatment both reduced PPARγ levels and hepatic injury in steatotic livers. When PPARγ was activated, neither RBP4 treatment nor PC (despite RBP4 induction) protected steatotic livers. In conclusion, steatotic liver grafts are more predisposed to down-regulate RBP4 and overexpress PPARγ. RBP4 treatment and PC, through RBP4 induction, reduced PPARγ levels in steatotic liver grafts, thus protecting them from the PPARγ detrimental effects.

Characterization of γδ T cell subsets in organ transplantation

γδ T cells are innate-type lymphocytes that preferentially act as regulators of local effector immune responses. Recent reports found an altered distribution of the two main subpopulations of blood γδ T cells (Vδ1 and Vδ2) in operationally tolerant liver transplant recipients. Based on this, γδ T cells subset quantification was proposed as a biomarker of immunologic risk in liver transplantation. The specific characteristics of γδ T cell subsets in transplantation remain however unknown. We have investigated here the phenotype, repertoire and functional properties of γδ T cell subsets in a large population of allograft recipients. Our results indicate that alterations in the γδ T cell compartment are not restricted to tolerant liver recipients. In fact, most immunosuppressed liver and kidney recipients also display an enlarged peripheral blood γδ T cell pool mainly resulting from an expansion of Vδ1 T cells exhibiting an oligoclonal repertoire and different phenotypic and cytokine production traits than Vδ2 T cells. We propose that persistent viral infections are likely to contribute to these alterations. Our data provide novel insight in the biology of γδ T cells and a rationale for exploring these lymphocytes in more depth into the pathogenesis of viral infections in transplantation.

Insulin like growth factor-1 increases fatty liver preservation in IGL-1 solution

AIM: To investigate the benefits of insulin like growth factor-1 (IGF-1) supplementation to serum-free institut georges lopez-1 (IGL-1)^® solution to protect fatty liver against cold ischemia reperfusion injury.

METHODS: Steatotic livers were preserved for 24 h in IGL-1^® solution supplemented with or without IGF-1 and then perfused “ex vivo” for 2 h at 37°C. We examined the effects of IGF-1 on hepatic damage and function (transaminases, percentage of sulfobromophthalein clearance in bile and vascular resistance). We also studied other factors associated with the poor tolerance of fatty livers to cold ischemia reperfusion injury such as mitochondrial damage, oxidative stress, nitric oxide, tumor necrosis factor-α (TNF-α) and mitogen-activated protein kinases.

RESULTS: Steatotic livers preserved in IGL-1^® solution supplemented with IGF-1 showed lower transaminase levels, increased bile clearance and a reduction in vascular resistance when compared to those preserved in IGL-1^® solution alone. These benefits are mediated by activation of AKT and constitutive endothelial nitric oxide synthase (eNOS), as well as the inhibition of inflammatory cytokines such as TNF-α. Mitochondrial damage and oxidative stress were also prevented.

CONCLUSION: IGL-1^® enrichment with IGF-1 increased fatty liver graft preservation through AKT and eNOS activation, and prevented TNF-α release during normothermic reperfusion.

ATG-Fresenius treatment and low-dose tacrolimus: results of a randomized controlled trial in liver transplantation

We report the results of a prospective randomized controlled trial in liver transplantation assessing the efficacy and safety of antithymocyte globulin (ATG-Fresenius) plus tacrolimus monotherapy at gradually decreasing doses. Patients were randomized to either: (a) standard-dose tacrolimus plus steroids;or (b) peritransplant ATG-Fresenius plus reduced-dose tacrolimus monotherapy followed by weaning of tacrolimus starting 3 months after transplantation. The primary end-point was the achievement of very low-dose tacrolimus (every-other-day or once daily dose with <5 ng/mL trough levels) at 12 months after transplantation. Acute rejection occurring during the first 3 months after transplantation was more frequent in the ATG group (52.4% vs. 25%). Moreover, late acute rejection episodes occurred in all recipients in whom weaning was attempted and no recipients reached the primary end-point. This motivated the premature termination of the trial. Tacrolimus trough levels were lower in the ATG-Fresenius group but no benefits in terms of improved renal function, lower metabolic complications or increased prevalence of tolerance-related biomarkers were observed. In conclusion, the use of ATG-Fresenius and tacrolimus at gradually decreasing doses was associated with a high rate of rejection, did not allow for the administration of very low doses of tacrolimus and failed to provide detectable clinical benefits. ClinicalTrials.gov identifier: NCT00436722.

Biomarkers of immunoregulatory status in stable liver transplant recipients undergoing weaning of immunosuppressive therapy

Biomarkers that reflect immune response recovery and predict clinical events during withdrawal or minimization of immunosuppressive therapy have not been evaluated. This study aimed to evaluate whether immune response recovers after withdrawal of long-term immunosuppressive treatment in stable liver transplant patients and to determine whether specific biomarkers reflect immune response reactivity and predict rejection. Pharmacokinetic-pharmacodynamic profiles were determined in 24 patients and 80 healthy donors before immunosuppressive treatment reduction began, at 50%, and at complete withdrawal. In patients who rejected, effector-T-cell response mediated by soluble IFN-γ, %CD4(+)IFN-γ and %CD8(+)IL-2/IFN-γ were significantly increased, while TGF-β1 production and the TGF-β1/IFN-γ ratio were significantly decreased. In patients with rejection, soluble IFN-γ and %CD8(+)IL-2 were significantly higher before immunosuppressive treatment was reduced. Further studies are required, but this battery of biomarkers performed in whole blood could be a useful tool to monitor immunosuppressive treatment minimization or withdrawal protocols and identify patients at increased risk of rejection.