Michael E. de Vera

NITRIC OXIDE PROTECTS CULTURED RAT HEPATOCYTES FROM TUMOR NECROSIS FACTOR-ALPHA -INDUCED APOPTOSIS BY INDUCING HEAT SHOCK PROTEIN 70 EXPRESSION

Nitric oxide (NO) and tumor necrosis factor-α (TNFα) play important roles in the pathogenesis of liver disease during acute inflammation. The present study was designed to elucidate the effect of NO pre-exposure on TNFα-induced hepatotoxicity. Pretreatment of primary cultures of rat hepatocytes with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) induced the expression of heat shock protein 70 (HSP70) mRNA and protein, which was associated with thermotolerance and cytoprotection from TNFα+actinomycin D-induced hepatotoxicity and apoptosis. SNAP transiently changed the intracellular redox state by inducing glutathione (GSH) oxidation associated with the formation of S-nitrosoglutathione (GSNO). HSP70 mRNA was also induced by the GSH-oxidizing agent diamide and the GSH-conjugating agent N-ethylmaleimide, suggesting that NO induces HSP70 expression through GSH oxidation. The protective effect of SNAP pretreatment on TNFα-induced apoptosis correlated with the level of HSP70 expression. SNAP pretreatment inhibited reactive oxygen intermediate generation and lipid peroxidation effects that were reversed by blocking HSP70 expression using an antisense oligonucleotide to HSP70. Finally, endogenous NO formation, induced in hepatocytes stimulated with interferon-γ and interleukin-1β, led to the formation of GSNO and GSSG, induced HSP70, and attenuated TNFα-mediated cytotoxicity. These findings demonstrated that NO can induce resistance to TNFα-induced hepatotoxicity, possibly through the stimulation of HSP70 expression.

Multiple NF-κB Enhancer Elements Regulate Cytokine Induction of the Human Inducible Nitric Oxide Synthase Gene

The human inducible nitric oxide synthase (iNOS) gene is overexpressed in a number of human inflammatory diseases. Previously, we observed that the human iNOS gene is transcriptionally regulated by cytokines and demonstrated that the cytokine-responsive regions are upstream of −3.8 kilobase pairs (kb). Therefore, the purpose of this study was to further localize the functional enhancer elements and to assess the role of the transcription factor NF-κB in both human liver (AKN-1) and human lung (A549) epithelial cell lines. The addition of NF-κB inhibitors significantly suppressed cytokine-stimulated iNOS mRNA expression and NO synthesis, indicating that NF-κB is involved in the induction of the human iNOS gene. Analysis of the first 4.7 kb of the 5′-flanking region demonstrated basal promoter activity and failed to show any cytokine-inducible activity. However, promoter constructs extending to −5.8 and −7.2 kb revealed 2–3-fold and 4–5-fold induction, respectively, in the presence of cytokines. DNA sequence analysis from −3.8 to −7.2 kb identified five putative NF-κB cis-regulatory transcription factor binding sites upstream of −4.7 kb. Site-directed mutagenesis of these sites revealed that the NF-κB motif at −5.8 kb is required for cytokine-induced promoter activity, while the sites at −5.2, −5.5, and −6.1 kb elicit a cooperative effect. Electromobility shift assays using a site-specific oligonucleotide and nuclear extracts from cells stimulated with cytokine-mixture, tumor necrosis factor-α or interleukin-1β, but not interferon-γ, exhibited inducible DNA binding activity for NF-κB. These data indicate that NF-κB activation is required for cytokine induction of the human iNOS gene and identifies four NF-κB enhancer elements upstream in the human iNOS promoter that confer inducibility to tumor necrosis factor-α and interleukin-1β.

Masquerader: High Mobility Group Box-1 and Cancer

Since its identification a third of a century ago, the high-mobility group box-1 (HMGB1) protein has been linked to varied diverse cellular processes, including release from necrotic cells and secretion by activated macrophages engulfing apoptotic cells. Initially described as solely chromatin-associated, HMGB1 was additionally discovered in the cytoplasm of several types of cultured mammalian cells 6 years later. In addition to its intracellular role, HMGB1 has been identified extracellularly as a putative leaderless cytokine and differentiation factor. In the years since its discovery, HMGB1 has also been implicated in disease states, including Alzheimers, sepsis, ischemia-reperfusion, arthritis, and cancer. In cancer, overexpression of HMGB1, particularly in conjunction with its receptor for advanced glycation end products, has been associated with the proliferation and metastasis of many tumor types, including breast, colon, melanoma, and others. This review focuses on current knowledge and speculation on the role of HMGB1 in the development of cancer, metastasis, and potential targets for therapy.

Pregnancy after liver transplantation with tacrolimus immunosuppression: a single center's experience update at 13 years.

Background. Chronic liver disease often leads to amenorrhea in women of childbearing age. There are several reports of successful pregnancy after liver transplantation (LTx) with cyclosporine A immunosuppression. Tacrolimus has been increasingly used in solid-organ transplantation, and the effect of the drug on pregnancy is still of interest to clinicians. This study updates our single-center experience. Methods. All pregnancies after LTx with tacrolimus immunosuppression were followed prospectively. Patients’ clinical courses during pregnancy and labor along with gestational period and birth weight were catalogued. Changes in liver function, renal function, and immunosuppression also were recorded. The birth weight percentile was calculated on the basis of the gestational period using a standard chart. Results. Thirty-seven mothers delivered 49 babies. Three mothers delivered three times, and six mothers delivered two times. Thirty-six mothers (97%) survived the pregnancy, and 36 allografts (97%) survived. The one death and graft loss was in a patient who demonstrated infra-aortic arterial graft, which clotted by the gravid uterus during labor. The patient developed a gangrenous liver and died before she could undergo retransplantation. The mean gestational period was 36.4±3.2 weeks, excluding two premature deliveries at 23 and 24 weeks gestation. Twenty-two babies (46.9%) were delivered by cesarean section, and the other babies were delivered vaginally. In addition to the two premature babies, one baby, who was born to a mother with Alagille syndrome, died from congenital birth defects. The rest of the newborns survived. The mean birth weight was 2,797±775 g, with 38 babies (78%) weighing more than 2,000 g. The mean birth weight percentile to gestational period was 54±23. Four babies (8.5%) had a birth weight percentile of less than 25, and 28 babies (59.6%) had a birth weight percentile greater than 50. Twelve patients demonstrated an increase in hepatic enzymes without jaundice during the pregnancy. All of them responded to augmentation of immunosuppression. Conclusion. The present report reconfirms the safety of tacrolimus during pregnancy after LTx. Preterm delivery and low birth weight seem to be a persistent problem in all solid-organ transplantation under any form of immunosuppression. However, toxemia of pregnancy and new onset of hypertension seem to be have a low occurrence with the use of tacrolimus.

Bacteremias in liver transplant recipients: Shift toward gram‐negative bacteria as predominant pathogens

During the 1990s, gram‐positive bacteria emerged as major pathogens after liver transplantation. We sought to determine whether the pathogens associated with bacteremias in liver transplant recipients have changed. Patients included 233 liver transplant recipients transplanted between 1989 and 2003. The proportion of all infections due to bacteremias increased significantly over time (P < .0001). Of other major infections, a trend toward a decrease in fungal infections (P = .089) and a significant decrease in cytomegalovirus (CMV) disease (P = .0004) were documented. Whereas the proportion of bacteremias due to gram‐negatives increased from 25% in the period of 1989–1993 to 51.8% in 1998–03, that of gram‐positive bacteria decreased from 75% in the period of 1989–93 to 48.2% in the period of 1998–2003. Methicillin‐resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most frequent pathogens in bacteremic patients. The incidence of bacteremias due to MRSA and Pseudomonas aeruginosa has remained unchanged (P < .20); however, that due to enteric gram‐negative bacteria, particularly Klebsiella pneumoniae has increased (P = .02). Klebsiella pneumoniae isolates in the current quartile were not clonally related. In conclusion, bacteremias as a proportion of all infections in liver transplant recipients have increased significantly over time, due in part to a decline in infections due to other major pathogens, e.g., fungi, primarily Candida species, and CMV. Gram‐negative bacteria have emerged as predominant pathogens in bacteremic liver transplant recipients. (Liver Transpl 2004;10:844–849.)

INTERFERON-?? AND RIBAVIRIN FOR THE TREATMENT OF RECURRENT HEPATITIS C AFTER LIVER TRANSPLANTATION1

BACKGROUND Initial studies utilizing interferon-alpha and ribavirin for the treatment of recurrent hepatitis C virus (HCV) infection after liver transplantation showed promising results. Here we report our single-center experience using this combination therapy. METHODS Liver transplant recipients with recurrent HCV (elevated serum aminotransferases, positive serum HCV RNA, and biopsy-proven hepatitis without rejection) received interferon-alpha (1.5-3 million units subcutaneously three times a week) and ribavirin (400-1000 mg p.o. daily) for 12 months or more. Serum aminotransferases, HCV RNA, and severity of hepatitis were followed. RESULTS Thirty-two patients have been treated for at least 3 months, including 13 who have been on 12 or more months of therapy. Three died from allograft failure due to recurrent HCV. Dose reductions of interferon-alpha and/or ribavirin occurred in 22 patients. Thirteen had their medications permanently discontinued for severe adverse effects. Twenty-six patients (81%) had a biochemical response (BR; normalization of serum aminotransferases) after 3 months. End-of-treatment and sustained BR were 77% and 71%, respectively. Mean viral loads decreased 68-77%; however, only three patients became serum HCV RNA negative. After 12 months of therapy, no histological improvement was observed in 11 patients who were biopsied. Patients who received mycophenolate mofetil or daclizumab had a less likelihood of achieving a BR. CONCLUSIONS A significant number of patients did not tolerate interferon-alpha or ribavirin. Although BR was excellent and mean viral loads decreased significantly, virological clearance was poor and no histological improvement was noted. A more efficacious treatment with less adverse effects for recurrent HCV after liver transplantation is needed.

Inhibiting Systemic Autophagy during Interleukin 2 Immunotherapy Promotes Long-term Tumor Regression

Administration of high-dose interleukin-2 (HDIL-2) has durable antitumor effects in 5% to 10% of patients with melanoma and renal cell carcinoma. However, treatment is often limited by side effects, including reversible, multiorgan dysfunction characterized by a cytokine-induced systemic autophagic syndrome. Here, we hypothesized that the autophagy inhibitor chloroquine would enhance IL-2 immunotherapeutic efficacy and limit toxicity. In an advanced murine metastatic liver tumor model, IL-2 inhibited tumor growth in a dose-dependent fashion. These antitumor effects were significantly enhanced upon addition of chloroquine. The combination of IL-2 with chloroquine increased long-term survival, decreased toxicity associated with vascular leakage, and enhanced immune cell proliferation and infiltration in the liver and spleen. HDIL-2 alone increased serum levels of HMGB1, IFN-γ, IL-6, and IL-18 and also induced autophagy within the liver and translocation of HMGB1 from the nucleus to the cytosol in hepatocytes, effects that were inhibited by combined administration with chloroquine. In tumor cells, chloroquine increased autophagic vacuoles and LC3-II levels inhibited oxidative phosphorylation and ATP production and promoted apoptosis, which was associated with increased Annexin-V(+)/propidium iodide (PI)(-) cells, cleaved PARP, cleaved caspase-3, and cytochrome c release from mitochondria. Taken together, our findings provide a novel clinical strategy to enhance the efficacy of HDIL-2 immunotherapy for patients with cancer.

Liver biopsy findings from healthy potential living liver donors: Reasons for disqualification, silent diseases and correlation with liver injury tests

BACKGROUND/AIMS Liver biopsies detect silent donor disease in potential living liver donors and provide material for studies of subclinical non-alcoholic fatty liver disease (NAFLD). Our primary goal was to determine the contribution of biopsy findings to potential donor evaluation. Factors contributing to pre-clinical NAFLD and correlations between liver injury tests and histopathology have been also determined. METHODS Patient records, laboratory tests and results of the histopathologic examination and diagnoses of 284 patients from 2001 to 2005 were retrospectively extracted from the EDIT database. Hepatic histology was correlated with liver injury tests and with general demographic characteristics in an otherwise normal healthy population. RESULTS A minority (n=119; 42%) of biopsies from this population of 143 males/141 females (average age=36.8years; mean BMI=26.6) were completely normal. The remainder showed steatosis (n=107; 37%), steatohepatitis (n=44; 15%), or unexplained low-grade/early stage chronic hepatitis, primary biliary cirrhosis, or nodular regenerative hyperplasia (n=16; 6%). Biopsy findings disqualified 29/56 donors. Independent risk factors for NAFLD by multivariate modeling, which differed by sex, included: BMI (p=0.0001), age (p=0.003), iron (p=0.01), and ALT (p=0.004). CONCLUSIONS Liver biopsies provide valuable information about otherwise undetectable liver disease in potential liver donors. Obesity, age and iron, which are influenced by sex, contribute to NAFLD pathogenesis. Blood tests other than standard liver profiles are needed to detect early NAFLD.

Cryptococcus neoformans infection in patients with cirrhosis, including liver transplant candidates

Abstract: We reviewed the cases of patients with cirrhosis, including liver transplant candidates, at our institution in the last 3 years (n = 5) and those individually described in the literature (n = 28), to assess unique characteristics and outcome of cryptococcosis in these patients. Sixty-four percent (21/33) of the patients had no other recognized immunosuppression. Peritonitis (in 45%, 15/33 of the patients) with modest pleocytosis in the ascitic fluid, was the most common presenting feature. Median time to detection of Cryptococcus in the ascitic fluid cultures was 6 days. Overall mortality rate was 81% (26/32); death was deemed attributable to cryptococcosis in 24/26 patients who died. Evaluation of culture-negative neutrocytic ascites in febrile cirrhotic patients warrants consideration of cryptococcal peritonitis.

Posttransplant biliary complications in the pre- and post-model for end-stage liver disease era.

Biliary complications remain a cause of morbidity after liver transplantation. The aim of this study was to determine whether changes in clinical practice in the era of the Model for End‐Stage Liver Disease (MELD) has affected biliary complications after liver transplantation. We retrospectively reviewed all deceased donor liver transplants at a single center. Patients were categorized as pre‐ or post‐MELD (transplant before or after February 28, 2002). A total of 1798 recipients underwent deceased donor liver transplants. Biliary stricture was more common in the post‐MELD era (15.4% versus 6.4%, P < 0.001). The strongest risk factors for stricture development were donor age (odds ratio [OR] = 1.01), presence of a prior bile leak (OR = 2.24), use of choledochocholedochostomy (OR = 2.22), and the post‐MELD era (OR = 2.30). Bile leak was more common in the pre‐MELD era (7.5% versus 4.9%, P = 0.02), with use of a T‐tube as the strongest risk factor (OR = 3.38). Surgical factors did not influence the biliary complication rate. In conclusion, even when employing multivariate analysis to allow for factors that may influence biliary strictures, transplant in the post‐MELD era was an independent predictor for stricture development. Further studies are warranted to determine the etiology of this increase. Liver Transpl, 2011.