P. Barrera

Role of nitric oxide in D-galactosamine-induced cell death and its protection by PGE1 in cultured hepatocytes.

Prostaglandin E(1) (PGE(1)) reduces cell death in experimental and clinical manifestations of liver dysfunction. Nitric oxide (NO) has been shown to exert a protective or noxious effect in different experimental models of liver injury. The aim of the present study was to investigate the role of NO during PGE(1) protection against D-galactosamine (D-GalN) citotoxicity in cultured hepatocytes. PGE(1) was preadministered to D-GalN-treated hepatocytes. The role of NO in our system was assessed by iNOS inhibition and a NO donor. Different parameters related to apoptosis and necrosis, NO production such as nitrite+nitrate (NO(x)) release, iNOS expression, and NF-kappaB activation in hepatocytes were evaluated. The inhibition of iNOS reduced apoptosis induced by D-GalN in hepatocytes. PGE(1) protection against D-GalN injury was associated with its capacity to reduce iNOS expression and NO production induced by D-GalN. Nevertheless, iNOS inhibition showed that protection by PGE(1) was also mediated by NO. Low concentrations of a NO donor reduced D-GalN injury with a decrease in the extracellular NO(x) concentration. High concentrations of the NO donor enhanced NO(x) concentration and increased cell death by D-GalN. The present study suggests that low NO production induced by PGE(1) preadministration reduces D-GalN-induced cell death through its capacity to reduce iNOS expression and NO production caused by the hepatotoxin.

The reduction of cell death and proliferation by p27Kip1 minimizes DNA damage in an experimental model of genotoxicity

Hepatocellular carcinoma (HCC) is the fifth most commonly occurring cancer worldwide. The expression of p27 has been related to reduced severity of tumor grade and recurrence of HCC. The study assessed the role of p27 on the cell proliferation and death, and DNA mutagenesis in experimental genotoxicity induced by aflatoxin B1 (AFB1) in cultured hepatocytes obtained from control and p27Kip1 deficient mice. The overexpression of p27 was assessed with wild type p27Kip1 expression vector in HepG2 cells. The expression of p27, p21 and p53 was assessed in well and poorly‐differentiated liver tumors. DNA damage and cell death induced by AFB1 were related to a reduction of p27 and p21 expression in cultured hepatocytes. AFB1‐induced nuclear phosphorylated (Ser 10) p27 degradation was related to a rise of nuclear KIST, Rsk‐1 and Rsk‐2 expression and cytoplasm phosphorylated (Thr 198) p27 expression. The overexpression of p27 reduced cell proliferation, cell death and DNA damage in AFB1‐treated hepatocytes. The enhanced survival of patients with well differentiated compared to poorly‐differentiated tumors was related to high expression of p27, p21 and p53 in liver sections. The study showed that the p27 reduced cell proliferation and death, as well as the accumulation of DNA damage in hepatocarcinogenesis.

Lack of agreement for defining 'clinical suspicion of rejection' in liver transplantation: a model to select candidates for liver biopsy.

The gold standard to diagnose acute cellular rejection (ACR) after liver transplantation (LT) is histological evaluation, but there is no consensus to select patients for liver biopsy. We aimed to evaluate the agreement among clinicians to select candidates for liver biopsy early after LT. From a protocol biopsy population (n = 690), we randomly selected 100 LT patients in whom the biopsy was taken 7–10 days after LT. The clinical information between LT and protocol biopsy was given to nine clinicians from three transplant centres who decided whether a liver biopsy was needed. The agreement among clinicians to select candidates for liver biopsy was poor: κ = 0.06–0.62, being κ < 0.40 in 76% of comparisons. The concordance between indication for liver biopsy and moderate–severe ACR in the protocol biopsy was κ < 0.30 in all cases. A multivariate model based on the product age‐by‐MELD (OR = 0.81; P = 0.013), delta eosinophils (OR = 1.5; P = 0.002) and mean tacrolimus trough concentrations <6 ng/ml within the prior 4 days (OR = 11.4; P = 0.047) had an AUROC = 0.84 to diagnose moderate–severe histological ACR. In conclusion, the agreement among clinicians to select patients for liver biopsy is very poor. If further validated the proposed model would provide an objective method to select candidates for liver biopsy after LT.

Calcium-dependent nitric oxide production is involved in the cytoprotective properties of n-acetylcysteine in glycochenodeoxycholic acid-induced cell death in hepatocytes

The intracellular oxidative stress has been involved in bile acid-induced cell death in hepatocytes. Nitric oxide (NO) exerts cytoprotective properties in glycochenodeoxycholic acid (GCDCA)-treated hepatocytes. The study evaluated the involvement of Ca2+ on the regulation of NO synthase (NOS)-3 expression during N-acetylcysteine (NAC) cytoprotection against GCDCA-induced cell death in hepatocytes. The regulation of Ca2+ pools (EGTA or BAPTA-AM) and NO (L-NAME or NO donor) production was assessed during NAC cytoprotection in GCDCA-treated HepG2 cells. The stimulation of Ca2+ entrance was induced by A23187 in HepG2. Cell death, Ca2+ mobilization, NOS-1, -2 and -3 expression, AP-1 activation, and NO production were evaluated. GCDCA reduced intracellular Ca2+ concentration and NOS-3 expression, and enhanced cell death in HepG2. NO donor prevented, and l-NAME enhanced, GCDCA-induced cell death. The reduction of Ca2+ entry by EGTA, but not its release from intracellular stores by BAPTA-AM, enhanced cell death in GCDCA-treated cells. The stimulation of Ca2+ entrance by A23187 reduced cell death and enhanced NOS-3 expression in GCDCA-treated HepG2 cells. The cytoprotective properties of NAC were related to the recovery of intracellular Ca2+ concentration, NOS-3 expression and NO production induced by GCDCA-treated HepG2 cells. The increase of NO production by Ca2+-dependent NOS-3 expression during NAC administration reduces cell death in GCDCA-treated hepatocytes.

Mitochondrial-driven ubiquinone enhances extracellular calcium-dependent nitric oxide production and reduces glycochenodeoxycholic acid-induced cell death in hepatocytes.

Ca(2+) mobilization, nitric oxide (NO), and oxidative stress have been involved in cell death induced by hydrophobic bile acid in hepatocytes. The aim of the study was the elucidation of the effect of the antioxidant mitochondrial-driven ubiquinone (Mito Q) on the intracellular Ca(2+) concentration, NO production, and cell death in glycochenodeoxycholic acid (GCDCA)-treated HepG2 cells. The role of the regulation of the intracellular Ca(2+) concentration by Ca(2+) chelators (EGTA or BAPTA-AM), agonist of Ca(2+) entrance (A23187) or NO (L-NAME or NO donor), was assessed during Mito Q cytoprotection in GCDCA-treated HepG2 cells. Cell death, NO synthase (NOS)-1, -2, and -3 expression, Ca(2+) mobilization, and NO production were evaluated. GCDCA reduced the intracellular Ca(2+) concentration and NOS-3 expression and enhanced cell death in HepG2. NO donor prevented and L-NAME enhanced GCDCA-induced cell death. The reduction of Ca(2+) entry by EGTA, but not its release from intracellular stores by BAPTA-AM, reduced the expression of NOS-3 and enhanced cell death in control and GCDCA-treated cells. Mito Q prevented the reduction of intracellular Ca(2+) concentration, NOS-3 expression, NO production, and cell death in GCDCA-treated HepG2 cells. The conclusion is that the recovery of Ca(2+)-dependent NOS-3 expression by Mito Q may be considered an additional cytoprotective property of an antioxidant.

Factores pronósticos de complicaciones postoperatorias en el trasplante hepático

OBJECTIVES the postoperative evolution of patients submitted to orthotopic liver transplant (OLT) is frequently associated with the appearance of different types of complications such as renal failure, graft rejection, infections, and neurological disorders. These complications are the most significant causes of early morbidity and mortality in patients undergoing OLT. The purpose of the present study was the identification of factors related to the different postoperative complications after OLT. EXPERIMENTAL DESIGN a prospective study was carried out. PATIENTS seventy-eight variables were analyzed in 32 consecutive patients undergoing OLT. The factors independently associated with the appearance of postoperative complications were identified using a stepwise logistic regression analysis. RESULTS the multivariate analysis showed that malondialdehyde and creatinine pretransplant serum levels were associated with the development of renal dysfunction. The pretransplant levels of haemoglobin and the units of platelets administered during surgery were prognostic factors of infections. Acute graft rejection was predicted by ?-glutamyl transpeptidase and total bilirubin serum levels. The pretransplant sodium and glutaredoxin levels in serum were associated with neurological complications. CONCLUSIONS we propose these markers for the identification of high-risk patients allowing an early surveillance and/or treatment to improve morbidity and survival in patients submitted to OLT.

Everolimus is safe within the first month after liver transplantation.

BACKGROUND & AIMS Sirolimus should not be started within the first month after liver transplantation (LT) because of an increased risk of adverse outcomes. The evidence regarding everolimus is lacking but the manufacturer transposed the same warning. We aimed to evaluate the safety of everolimus started within the first month after LT. METHODS A consecutive cohort 187 LT patients (2009-2013) with a tacrolimus-based immunosuppression was evaluated. Patients starting everolimus within the first month after LT (n = 33; 17.6%) were compared with those starting everolimus thereafter (n = 25; 13.4%) or not receiving everolimus (n = 129; 69%). The median follow-up after LT was 21 months (IQR 7-36). Prospective outcomes were evaluated by using Kaplan-Meier curves and Coxs regression. RESULTS The incidence of hepatic artery thrombosis was not significantly different in patients early treated with everolimus when compared with the remaining cohort (0% vs 9.1%; p = 0.12). Other vascular complications occurred in 9.1% of patients with early everolimus vs 7.3% in the remaining cohort (p = 0.72). No wound healing complications were detected with early everolimus. There were similar rates of incisional hernia (p = 0.31), infections (p = 0.15), renal impairment (p = 0.37), and histologically-proven acute rejection (p = 0.24) between groups. The rates of hyperlipidemia were increased with early everolimus (29.9% vs 16.5% at 3 years; p = 0.018). Graft loss and mortality rates were similar between groups (p = 0.34 and p = 0.94 respectively), after adjusting for possible confounding factors. CONCLUSIONS Everolimus combined with reduced tacrolimus proved to be safe within the first month after LT. Future trials may be allowed to implement everolimus early after LT.

Impacto del sistema MELD en la selección de candidatos para trasplante hepático

La tasa de mortalidad en la lista de espera de trasplante hepático se sitúa en España en torno al 10%. Sin embargo, este porcentaje puede aumentar en un 5-10% más si se añaden las exclusiones de esta lista por gravedad extrema y muy baja probabilidad de sobrevivir al trasplante, y los pacientes con hepatocarcinoma (CHC) que progresan y rebasan los límites de extensión aceptados. No existe un consenso bien definido sobre los criterios de distribución de órganos, es decir, sobre la gestión de la lista de espera, que pasa a ser un factor determinante de la tasa de mortalidad pretrasplante. Frente al modelo de priorizar a los pacientes más graves, que reduciría la mortalidad pretrasplante, se propone la selección de los candidatos con mayores probabilidades de supervivencia. La defensa de cualquiera de estas estrategias introduce sesgos de índole ética de difícil evaluación. No hay en definitiva un modelo universalmente aceptado para la distribución de donantes, de tal modo que algunos centros optan por seguir un criterio cronológico en el que, respetando el grupo sanguíneo, los pacientes son trasplantados de acuerdo con el orden de inclusión.

Trasplante hepático en pacientes con infección VIH

: During the few last years, after the introduction of high activity antiretroviral therapy (HAART), liver diseases, particularly those related to HCV infection, have emerged as one of the most important causes of mortality in patients with HIV infection. Consequently, liver transplantation is increasingly indicated in this population. Post-transplantation survival in HIV-positive patients with non-hepatitis C virus (HCV) liver diseases is adequate and similar to that in HIV-negative patients. In contrast, survival in patients coinfected with HIV and HCV is only moderate (around 50% at 5 years after transplantation). The main cause of mortality in these patients is HCV recurrence. In almost all patients, HIV infection remains controlled with HAART after liver transplantation. Other issues of interest in this setting are the selection of liver transplantation candidates and the frequent interactions between HAART and immunosuppressive drugs.