Effectiveness of 8- or 12-weeks of ledipasvir and sofosbuvir in real-world treatment-naïve, genotype 1 hepatitis C infected patients

BACKGROUND

Treatment of genotype 1 hepatitis C virus (HCV) infection with combination direct acting anti-virals is associated with very high rates of sustained virological response (SVR). Daily combination of ledipasvir and sofosbuvir for 12 weeks is approved for the treatment of genotype 1 HCV patients, though noncirrhotic patients who are naïve to treatment with a baseline HCV RNA <6 million IU/mL can be treated for 8 weeks. This guidance stemmed from a post hoc analysis of the ION 3 clinical trial, which demonstrated similar SVR for patients treated with ledipasvir and sofosbuvir with or without ribavirin for 8 or 12 weeks.

AIM

To compare the SVR for 8 weeks vs 12 weeks of ledipasvir and sofosbuvir in HCV infected patients in a real-world setting.

METHODS

We performed an observational real-world cohort study of treatment success following 8 or 12 weeks of ledipasvir and sofosbuvir for treatment-naïve genotype 1 HCV patients.

RESULTS

A total of 826 patients were treated for either 8 (n=252) or 12 weeks (n=574) with ledipasvir and sofosbuvir and achieved SVR rate of 95.3% and there was no statistical difference in SVR rates in the two groups irrespective of any clinical or virological variables.

CONCLUSIONS

In treatment-naïve HCV genotype 1 patients, SVR was 95% in those treated for either 8 weeks or 12 weeks with ledipasvir and sofosbuvir. 8 week ledipasvir and sofosbuvir can reduce costs without compromising outcomes for those patients who qualify for such regimen.

Real-world effectiveness for 12 weeks of ledipasvir-sofosbuvir for genotype 1 hepatitis C: the Trio Health study

Early data regarding the "real-world" experience with novel therapies for hepatitis C (HCV) are encouraging. Data are still limited, however, regarding real-world rates of sustained virologic response (SVR) for ledipasvir-sofosbuvir (LDV-SOF), particularly for patients with prior treatment failure. We performed a retrospective cohort study of 1597 patients with chronic genotype 1 HCV who were treated using 12 weeks of the following regimens LDV-SOF±ribavirin (RBV) (n=1521 without RBV, n=76 with RBV). The primary outcome was SVR-determined at 12 weeks in an intention-to-treat design. Prescription according to Food and Drug Administration (FDA) approved labelling (adding RBV for patients with cirrhosis and treatment failure) was assessed in multivariate models. The study population was aged 60 years on average (range 19-89), 60% male, 50% Caucasian, 43% cared for at an academic centre and 30% cirrhotic. Overall, LDV-SOF resulted in a 94% SVR rate. Only 44 (2.9%) patients relapsed. LDV-SOF+RBV yielded SVR in 97% with 0 viral relapses. While cirrhosis and thrombocytopenia were associated with lower odds of SVR, in a multivariable regression model, only treatment at an academic centre and prescriptions contrary to FDA labelling were significantly associated with lower SVR-odds ratios, 0.56 95% CI (0.35-0.87) and 0.29 95% CI(0.12-0.68), respectively. The real-world experience with LDV-SOF mirrors the SVR rates observed in clinical trials. Efforts to promote prescription within FDA recommendations are warranted.

Direct costs of first-generation protease inhibitors for the treatment of genotype 1 chronic hepatitis C viral infection

To evaluate the cost-effectiveness of Hepatitis C therapy, robust real-world data are needed to understand the costs and benefits of treatment alternatives. The objective of this study was to evaluate the true direct cost of treatment in an unselected sequential population of patients treated at a tertiary care centre for hepatitis C virus genotype 1. A total of 200 consecutive patients were treated with interferon, ribavirin and a first-generation direct-acting antiviral agent (DAA) between 2011 and 2013. A total of 41% had cirrhosis, 31% were prior relapsers, and 41% were prior partial or null responders. Costs used were wholesale acquisition cost prices for medications, average hospital costs per day for each diagnosis code based on US inpatient hospital charges. All costs were adjusted to 2013 dollars. Sustained virologic response (SVR) was achieved in 97 patients (48.5%). A total of 14% experienced relapse, 19% breakthrough or nonresponse, and 18.5% discontinued secondary to side effects. Twenty per cent of patients had at least one hospitalization attributable to a complication of therapy. Thirty-seven per cent of patients required erythropoietin-stimulating agents, 16% received filgastrim, and 15% needed a red blood cell transfusion. The mean overall cost of treatment was $83,851 per patient. The cost per SVR was $172,889; $266,670 for patients with cirrhosis. The costs per SVR after treatment with first-generation DAAs are dependent on the stage of disease and therapy side effects. These real-world costs significantly exceed those described in prior cost-effectiveness assessments and should be used instead for future studies.

Treatment cessation in noncirrhotic, e-antigen negative chronic hepatitis B is safe and effective following prolonged anti-viral suppression with nucleosides/nucleotides

BACKGROUND

The treatment of HBeAg-negative chronic hepatitis B (CHB) is considered to be open-ended, with no guidelines for treatment cessation.

AIM

To evaluate biochemical and virological relapse requiring retreatment in noncirrhotic HBeAg-negative CHB in patients who stopped treatment following a period of prolonged viral suppression with nucleotides/nucleosides.

METHODS

We performed a single-centre retrospective chart review of patients with HBeAg-negative CHB who maintained viral suppression for 4-5 years on anti-viral treatment, and thus subsequently stopped treatment. The primary end point of composite relapse was defined by an increase in HBV DNA >2000 IU/mL, ALT elevation above 1.25 × normal or doubling of ALT from cessation, and re-initiation of anti-viral therapy.

RESULTS

We identified 33 patients with HBeAg-negative CHB who stopped treatment following viral suppression. Mean treatment duration was 5.28 ± 2.73 years. Patients were treated with lamivudine (3), adefovir (14), entecavir (4), and tenofovir (12). Eleven (33%) patients met the primary end point of composite relapse. For individual end points, 21 (63%) patients had a viral relapse, 16 (48%) had a biochemical relapse, and 16 (48%) restarted treatment, leaving 17 (52%) patients who remained treatment-free over a median 36 months of follow-up. Lower pre-treatment ALT and detectable HBV DNA within the first month after treatment discontinuation were associated with increased rates of composite relapse (HR 1.01; P = 0.022 for ALT and HR 1.01; P = 0.038 for HBV DNA).

CONCLUSION

Patients with noncirrhotic HBeAg-negative CHB can stop treatment after greater than 4-5 years of suppressive therapy with nucleosides/nucleotides with more than 50% remaining treatment-free.

The new paradigm of hepatitis C therapy: integration of oral therapies into best practices

Emerging data indicate that all-oral antiviral treatments for chronic hepatitis C virus (HCV) will become a reality in the near future. In replacing interferon-based therapies, all-oral regimens are expected to be more tolerable, more effective, shorter in duration and simpler to administer. Coinciding with new treatment options are novel methodologies for disease screening and staging, which create the possibility of more timely care and treatment. Assessments of histologic damage typically are performed using liver biopsy, yet noninvasive assessments of histologic damage have become the norm in some European countries and are becoming more widespread in the United States. Also in place are new Centers for Disease Control and Prevention (CDC) initiatives to simplify testing, improve provider and patient awareness and expand recommendations for HCV screening beyond risk-based strategies. Issued in 2012, the CDC recommendations aim to increase HCV testing among those with the greatest HCV burden in the United States by recommending one-time testing for all persons born during 1945-1965. In 2013, the United States Preventive Services Task Force adopted similar recommendations for risk-based and birth-cohort-based testing. Taken together, the developments in screening, diagnosis and treatment will likely increase demand for therapy and stimulate a shift in delivery of care related to chronic HCV, with increased involvement of primary care and infectious disease specialists. Yet even in this new era of therapy, barriers to curing patients of HCV will exist. Overcoming such barriers will require novel, integrative strategies and investment of resources at local, regional and national levels.

Is 3 the new 1: perspectives on virology, natural history and treatment for hepatitis C genotype 3

Affecting 2-3% of the world's population, hepatitis C is a common viral infection which is a significant cause of morbidity and mortality. Hepatitis C genotype 1 is the dominant viral genotype among Western patients. For the last 20 years, in the era of interferon-based therapy, it was far more difficult to treat relative to genotypes 2 and 3. Accordingly, a significant focus of research was on new antiviral agents for the dominant genotype 1 patient. Now, as promising specific treatments are being introduced for genotype 1, the attention of clinicians and researchers has turned back to the 50-70 million patients infected with a nongenotype 1 hepatitis C. Furthermore, after recent, larger randomized trials, we have realized that genotype 2 is truly interferon sensitive while genotype 3 patients are far less successful with therapy. In this fundamentally altered landscape, genotype 3 is now potentially the most difficult to treat genotype and an area of intense research for new drug development. Herein we review the virology, natural history and the treatment of genotype 3 hepatitis C.

A practical guide for the use of boceprevir and telaprevir for the treatment of hepatitis C

The aim of this study is to review clinical trial data on the newly approved protease inhibitors boceprevir and telaprevir to develop consensus recommendations on the optimal use of these agents for the treatment of patients with chronic hepatitis C virus (HCV) infection. An expert panel of seven leading authorities in viral hepatitis was convened to establish and disseminate a practical guide on best practices for incorporating boceprevir and telaprevir into therapy for HCV infection in both treatment-naive and treatment-experienced patients. The topics covered include selecting candidates for boceprevir- or telaprevir-based treatments, predictors of response and early viral kinetics, response-guided therapy approaches, on-treatment management strategies to optimize the likelihood of response and minimize the risk of drug resistance, management of adverse effects during therapy and key considerations for special populations. The expert panel incorporated the best available clinical evidence into recommendations on how boceprevir and telaprevir should be used in the clinical setting. They indicated how treatment regimens may differ according to the baseline factors, such as presence of cirrhosis and when therapy may need to be modified or stopped altogether because of adverse events or poor virologic response. This practical guide will serve as a valuable resource for clinicians embarking on the new treatment paradigm of boceprevir or telaprevir in combination with peginterferon/ribavirin for chronic genotype 1 HCV infection.

Transient elastography for predicting clinical outcomes in patients with chronic liver disease

There is increasing interest in developing noninvasive means to evaluate liver fibrosis in patients with chronic liver disease to determine disease severity, prognosis and optimal treatment. Transient elastography (TE) has previously been demonstrated to predict the presence or absence of advanced fibrosis. The current study was conducted to determine whether TE can identify patients with chronic liver disease at risk of clinical decompensation. A total of 667 patients underwent TE and were followed for a median of 861 days and 57 patients achieved the primary outcome, a composite of clinical endpoints including death, ascites, encephalopathy, increased Child Score ≥ 2, variceal bleed, hepatocellular carcinoma or listing for transplant. Overall, TE had an area under the receiver operating characteristic curve of 0.87 for predicting clinical outcome. Using a cut-off of 10.5 kPa, TE has a sensitivity, specificity, positive predictive value and negative predictive value (NPV) of 94.7%, 63.0%, 19.3% and 99.2%, respectively. A predictive model for clinical events was developed using generalized cross-validation for clinical endpoints considering TE, liver biopsy results and multiple other predictors. Individually, TE performed better than biopsy, or any other variable, for predicting clinical outcome [Harrell's C Statistic 0.86 for TE, 0.78 for stage]. Patients with a TE score of >12.5 kPa were found to have a relative hazard for clinical event of 18.99 compared with patients with TE score <10.5. A combined variable model including TE, aspartate aminotransferase/alanine aminotransferase ratio and model for end-stage liver disease (MELD) yielded the highest predictive accuracy with Harrell's C value of 0.93. In the subset of patients with cirrhosis, TE was not found to be independently associated with clinical outcomes in univariate or multivariate analysis although it retained a high sensitivity and NPV of 97.5% and 92.3%, respectively, at a kPa cut-off of 10.5. TE can successfully identify patients with chronic liver disease who are at low risk of clinical decompensation over a time period of 2 years.

The safety and efficacy of oral docosahexaenoic acid supplementation for the treatment of primary sclerosing cholangitis - a pilot study

BACKGROUND

Primary sclerosing cholangitis (PSC) is characterised by progressive inflammatory and fibrotic destruction of the biliary ducts. There are no effective medical therapies and presently high dose ursodeoxycholic acid is no longer recommended due to significant adverse events in a recent clinical trial. Cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction is associated with PSC in both children and adults. Since CFTR dysfunction leads to altered fatty acid metabolism, specifically reduced docosahexaenoic acid (DHA), we hypothesised that DHA supplementation might be an effective therapy for patients with PSC.

AIM

To determine the safety and efficacy of oral DHA supplementation for the treatment of PSC.

METHODS

We conducted a 12 month open-label pilot study to evaluate safety of oral DHA and its effects on serum alkaline phosphatase as a primary outcome measure in 23 patients with PSC. DHA was administered orally at 800 mg twice per day. Secondary outcomes included changes in other liver function tests and fibrosis biomarkers.

RESULTS

A 1.7-fold increase in serum DHA levels was observed with supplementation. The mean alkaline phosphatase level (±S.E.) at baseline was 357.8 ± 37.1 IU compared to 297.1 ± 23.7 IU (P < 0.05) after 12 months of treatment. There were no changes in other liver function tests and fibrosis biomarkers. No adverse events were reported.

CONCLUSIONS

Oral DHA supplementation is associated with an increase in serum DHA levels and a significant decline in alkaline phosphatase levels in patients with PSC. These data support the need for a rigorous trial of DHA therapy in PSC.

The optimal cut-off for predicting large oesophageal varices using transient elastography is disease specific

The diagnosis of cirrhosis requires screening for oesophageal varices by upper gastrointestinal endoscopy. In many countries, serological tests and elastography are replacing liver biopsy for diagnosing cirrhosis. The aims of this study were to see whether there was an optimal cut-off of liver stiffness that could predict the presence of large (>F2) oesophageal varices and whether this was disease specific. A total of two hundred and twenty-two patients with all cause cirrhosis (Child class A) were screened, and 211 had successful elastography and are included in the analysis. Of the patients studied, one hundred and thirty-two patients had no or small F1 varices and 79 had large varices. Liver stiffness of 19.8 kPa had a negative predictive value of 91% and a positive predictive value of 55% with an area under the curve (AUC) on receiver operating characteristics (ROC) of 0.73 in differentiating between small and large varices. Seven patients with large varices would have been incorrectly classified. In the 157 patients with hepatitis C as the aetiology of cirrhosis, the negative predictive value was 98% and only one patient was misclassified. Liver stiffness was superior in diagnostic accuracy to platelet count in all patients. A liver stiffness of >19.8 kPa could be utilized as a cut-off for endoscopy and beta blocker utilization, particularly in patients with hepatitis C.

Review article: pharmacological approaches for the treatment of thrombocytopenia in patients with chronic liver disease and hepatitis C infection

BACKGROUND

Patients with chronic liver disease and hepatitis C virus (HCV) frequently experience thrombocytopenia that complicates the management of their disease. Traditional therapy for thrombocytopenia consists of platelet transfusion, which can be associated with significant safety and economic issues. Consequently, efforts have been directed toward developing novel approaches for the treatment of thrombocytopenia.

AIM

To summarize the available data on the limitations of traditional therapies and the effects of novel therapies currently in clinical development for the treatment of thrombocytopenia.

RESULTS

Recent research has begun to reveal the complex mechanisms that regulate thrombopoiesis. Cytokines and growth factors, such as interleukin-11 and thrombopoietin (TPO), play a key role in the production of platelets. A number of recent clinical studies have provided evidence that pharmacologic agents that target megakaryocyte precursors and stimulate thrombopoiesis can effectively reverse thrombocytopenia. Here, we review the regulation of thrombopoiesis, the role of TPO, and a number of novel compounds that stimulate platelet production by acting through the TPO receptor. Agents that stimulate TPO include the orally available nonpeptidic agonists eltrombopag and AKR-501, peptidic agonists AMG-531 and Peg-TPOmp, and small engineered antibodies.

CONCLUSION

Results from clinical trials with these agents in healthy subjects confirm that activation of thrombopoiesis via the TPO pathway is an effective method of stimulating platelet production. This approach may provide safer, more effective treatment for thrombocytopenia in patients with chronic liver disease. Several of these agents are currently being tested in large scale trials.

Introduction: thrombocytopenia in chronic liver disease -- treatment implications and novel approaches

BACKGROUND

Thrombocytopenia is a common hematologic toxicity among patients with chronic liver disease.

AIM

To give a brief overview of thrombocytopenia and its effects on patients with chronic liver disease.

RESULTS

Thrombocytopenia is generally mild to moderate in severity and can thus be managed relatively easily. Severe thrombocytopenia (platelet count <50,000 /microL), however, may present significant challenges to patient management. Thrombocytopenia can increase the risk of bleeding associated with invasive or surgical procedures. Therefore, while perhaps less widely appreciated than the impact of anemia or neutropenia, effective prevention and management of thrombocytopenia is also critical for patients with liver disease.

CONCLUSIONS

This supplement to Alimentary Pharmacology & Therapeutics provides a comprehensive review of the significance of thrombocytopenia in patients with chronic liver disease, its pathophysiology and relationship to coagulation disorders, impact on clinical care and resource utilization, and novel therapies that may be able to supplant platelet transfusions.

Randomised double-blinded trial evaluating silymarin for chronic hepatitis C in an Egyptian village: study description and 12-month results

BACKGROUND/AIMS

A double-blinded trial evaluating silymarin, an herbal supplement for liver disease, to prevent complications of chronic hepatitis C virus infection has not been done.

SUBJECTS

One hundred and seventy-seven consenting residents of an Egyptian village with chronic hepatitis C virus were randomly assigned to receive either silymarin or multivitamin supplements.

METHODS

Participants had baseline and follow-up clinical, ultrasound, blood tests and quality-of-life assessments. Community nurses visited weekly to ascertain compliance, distribute supplements and record adverse effects.

RESULTS

At 12 months almost all of 141 remaining subjects reported feeling better, although symptoms and quality-of-life scores did not differ between the silymarin and multivitamin groups. Both the silymarin and vitamins were tolerated equally well; and >95% of supplements were taken by >95% of subjects. One in each group had no detectable hepatitis C virus antibodies while two in the silymarin group and three receiving multivitamins had undetectable hepatitis C virus RNA. Serum alanine aminotransferase elevations did not differ between groups. Serum hepatic fibrosis marker, hyaluronic acid and YKL-40, and abdominal ultrasound results were similar in both groups and may have progressed slightly at 12 months.

CONCLUSIONS

The recommended dose of silymarin can be safely taken for 1 year and improves symptoms and general well-being, but has no effect upon hepatitis C virus viremia, serum ALT, or serum and ultrasound markers for hepatic fibrosis. More prolonged evaluation and a higher dose may be required to ascertain whether milk thistle supplements prevent complications of chronic hepatitis C virus.

Hepatic fibrosis: are any of the serum markers useful?

There is a clinical need for noninvasive measurement of liver fibrosis both to diagnose significant liver fibrosis and to monitor the effects of therapy on fibrogenesis and fibrolysis. Multiple clinical markers have been evaluated over the years, and as our understanding of the molecular process of liver scarring has advanced, newer markers have appeared. Serum markers include extracellular matrix proteins such as the N-terminal propeptide of collagen III, hyaluronan, YKL-40, laminin, metalloproteinases, and their inhibitors. Use of multiple markers has led to 90% sensitivity in diagnosing cirrhosis, but specificity is variable at about 60%. Automated systems to measure these markers are under development and are being evaluated for their ability to monitor fibrosis during and after therapy in multiple liver diseases, including hepatitis B and C. Although no individual fibrosis marker is clinically applicable today, we foresee a future in which monitoring fibrosis markers will replace sequential liver biopsy as a standard of care.

An assessment of digital image analysis to measure fibrosis in liver biopsy specimens of patients with chronic hepatitis C

The aim was to assess the validity of a digitally computed fibrosis ratio as a measure of fibrosis stage in liver biopsy specimens. We scored 230 liver biopsy specimens from patients with chronic hepatitis C for fibrosis using modified Knodell criteria; fibrosis ratios were computed from digital images that encompassed the complete trichrome-stained section of each case. Although an overall correlation between fibrosis ratio and ordinal score was present, subset analysis showed that this correlation existed only among biopsy specimens with high scores (3-6, early bridging fibrosis to established cirrhosis). There was no correlation or difference between category means found among biopsy specimens with low scores (0-3, normal to early bridging fibrosis). Furthermore, concordance by both estimates in direction of fibrosis change among serial liver biopsy specimens was found in only 11 (30%) of 37 pairs compared. The findings suggest that a qualitative assessment of the computerized fibrosis pattern is necessary for the interpretation of computerized fibrosis ratio measurements, particularly in patients with early stage fibrosis.

Xenogeneic transplantation of porcine hepatocytes into the CCl4 cirrhotic rat model

Liver support using extracorporeal devices and hepatocyte transplantation has received renewed interest for the management of acute and chronic liver failure. The aim of this study was to determine whether xenogeneic porcine hepatocytes could integrate into the liver parenchyma of cirrhotic Lewis rats when administered by an intrasplenic route. Cirrhosis was induced by carbon tetrachloride (CCl4) inhalation and confirmed histologically. Freshly isolated porcine hepatocytes were infused directly into the splenic pulp at laparotomy over a 5-15-min interval. Using (111)In-labeled hepatocytes, the degree of localization of porcine hepatocytes to the spleen and liver was found to be greater than 60% in both control and cirrhotic rats. Integration of porcine hepatocytes into the rat liver parenchyma was determined by immunohistochemical staining for porcine albumin in rat liver sections. Further confirmation was provided by in situ hybridization using a porcine-specific probe that binds to a distinct repetitive element (PRE) in porcine DNA. Evidence of integrated porcine hepatocytes was seen for over 50 days in animals under cyclosporine immunosuppression. These data demonstrate the integration of xenogeneic porcine hepatocytes into the liver of the cirrhotic rat and their ability to produce porcine albumin for up to 50 days.

A recombinant bovine gallbladder mucin polypeptide binds biliary lipids and accelerates cholesterol crystal appearance time

BACKGROUND & AIMS

Mucin has a central role in the pathogenesis of cholesterol gallstones, in part because of its ability to bind biliary lipids and accelerate cholesterol crystal appearance time. Previous studies have localized these properties to nonglycosylated mucin domains, and we have recently shown that these domains contain a series of 127-amino acid, cysteine-rich repeats. The aim of this study was to express a recombinant mucin polypeptide containing these repeats and investigate its lipid-binding and pronucleating properties.

METHODS

A recombinant mucin polypeptide was expressed as a glutathione S-transferase fusion protein in Escherichia coli, purified by affinity chromatography, and compared with native bovine gallbladder mucin in lipid-binding and cholesterol crystal appearance time assays.

RESULTS

The recombinant mucin polypeptide bound a hydrophobic fluorescent probe and cholesterol in a concentration-dependent manner. It accelerated the appearance of cholesterol crystals from lithogenic model bile, an effect that was both time and concentration dependent.

CONCLUSIONS

The cysteine-rich repeats in the recombinant mucin polypeptide correspond to the protease-sensitive hydrophobic domains identified in earlier biochemical studies. Further delineation of the lipid-binding site(s) in these repeats will provide new insights into the mechanism of cholesterol crystal nucleation and stone growth.

pH-dependent conformational change of gastric mucin leads to sol-gel transition

We present dynamic light scattering (DLS) and hydrophobic dye-binding data in an effort to elucidate a molecular mechanism for the ability of gastric mucin to form a gel at low pH, which is crucial to the barrier function of gastric mucus. DLS measurements of dilute mucin solutions were not indicative of intermolecular association, yet there was a steady fall in the measured diffusion coefficient with decreasing pH, suggesting an apparent increase in size. Taken together with the observed rise in depolarized scattering ratio with decreasing pH, these results suggest that gastric mucin undergoes a conformational change from a random coil at pH >/= 4 to an anisotropic, extended conformation at pH < 4. The increased binding of mucin to hydrophobic fluorescent with decreasing pH indicates that the change to an extended conformation is accompanied by exposure of hydrophobic binding sites. In concentrated mucin solutions, the structure factor S(q, t) derived from DLS measurements changed from a stretched exponential decay at pH 7 to a power-law decay at pH 2, which is characteristic of a sol-gel transition. We propose that the conformational change facilitates cross-links among mucin macromolecules through hydrophobic interactions at low pH, which in turn leads to a sol-gel transition when the mucin solution is sufficiently concentrated.

The amino-terminal sequence of MUC5B contains conserved multifunctional D domains: implications for tissue-specific mucin functions

The MUC5B mucin gene product is expressed in a wide variety of secretory epithelia including the gallbladder, salivary glands, trachea, and colon. Previous studies by us and others have described the C-terminal region as well as the central tandem repeating domain of this mucin. In an effort to understand the functional role of MUC5B in diverse human tissues, the sequence encoding the N-terminal region of this mucin was determined from the sequences of exons in three overlapping genomic clones. Primer extension mapped the site of transcription initiation 25 bp downstream from a putative TATA box element. The N-terminal region of MUC5B contained 1321 amino acids organized into a signal peptide, a short serine-threonine rich region, and three von Willebrand factor-like D domains. Comparison of this sequence with the N-terminal sequences of MUC2 and MUC5AC revealed a much higher degree of identity (46-59%) than that observed in the C-terminal regions of these mucins (33%). The N-terminal sequence of MUC5B also contains a number of sequence motifs common to several groups of extracellular ligand binding and adhesion proteins not previously recognized in mammalian gel-forming mucins. The N-terminal D domains in MUC5B are likely to have important roles in both mucin assembly and in the protective functions of the secreted mucin.

Liver-derived CTL in hepatitis C virus infection: breadth and specificity of responses in a cohort of persons with chronic infection

Hepatitis C virus (HCV)-specific CTL have been found within the inflammatory infiltrate of the liver of chronically infected individuals, but the breadth and specificity of the CTL response in relation to viral load are less well characterized. In this study, we analyzed the intrahepatic CTL response in liver biopsy specimens from 44 chronically infected subjects. Liver-infiltrating lymphocytes were expanded polyclonally in bulk cultures, and multiple clones were derived by limiting dilution. HCV-specific CTL responses directed at genotype 1a structural proteins were assessed in all subjects, and 22 subjects were tested more comprehensively using vectors expressing all structural and nonstructural HCV Ags. CTL responses were further characterized to determine the HLA restriction and optimal epitopes recognized. In those persons screened for recognition of all HCV Ags, HLA class I-restricted CTL were detected in 45%. Nineteen different CTL epitopes were identified, which were distributed throughout the genome; only one epitope was targeted by more than one person. In those persons with CTL responses, the breadth of response ranged from one to five epitopes. There was no correlation between the presence of a detectable CTL response and viral load. These results indicate considerable heterogeneity in detectable HCV-specific CTL responses in chronically infected persons. The mechanisms by which HCV persists during chronic infection remain to be clarified.

Urinary assays for desmosine and hydroxylysylpyridinoline in the detection of cirrhosis

BACKGROUND/AIMS

Non-invasive markers of liver fibrosis have great potential for both the diagnosis and therapy of liver disease and cirrhosis. The aim of this study was to evaluate the potential of urinary amino acids desmosine (DES) and isodesmosine (IDES) derived from the breakdown of elastin and hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) derived from fibrillar collagen in diagnosing chronic liver disease.

METHODS

We studied 48 patients with chronic liver disease who had varying degrees of liver fibrosis, graded 0-6 using a modified Knodell score, and 20 control subjects without liver disease. Urinary DES (microg/g creatinine) and HP (nmol/mmol creatinine) were measured by an isotope dilution, high performance liquid chromatography method. For liver disease patients, aminoterminal propeptide of type III procollagen (PIIINP) and alanine aminotransferase were determined. The urine and serum markers were correlated to degree of fibrosis and inflammation on liver biopsies. Differences between groups were analyzed by ANOVA and multiple linear regression was applied to determine independence of variables. Sensitivity, specificity and receiver operating curves were derived for each marker.

RESULTS

In the 17 patients with liver fibrosis score of 5-6, mean urinary DES, IDES, HP and LP were all significantly greater than in the control group (p<0.05). Urinary DES and IDES correlated best with fibrosis score, r=0.61 for both markers. The correlation coefficient between serum PIIINP and fibrosis score was 0.47. Urinary DES and HP each had an overall diagnostic accuracy of 77% for fibrosis. Combining markers improved accuracy to over 80%. No correlation was seen between the urinary markers and inflammation scores.

CONCLUSIONS

Urinary DES and HP are potentially useful clinical markers for liver fibrosis, especially when used in combination or in association with PIIINP.

Diffusion behavior of lipid vesicles in entangled polymer solutions

Dynamic light scattering was used to follow the tracer diffusion of phospholipid/cholesterol vesicles in aqueous polyacrylamide solutions and compared with the diffusive behavior of polystyrene (PS) latex spheres of comparable diameters. Over the range of the matrix concentration examined (Cp = 0.1-10 mg/ml), the diffusivities of the PS spheres and the large multilamellar vesicles exhibited the Stokes-Einstein (SE) relation, while the diffusivity of the unilamellar vesicles did not follow the increase of the solution's viscosity caused by the presence of the matrix molecules. The difference between the diffusion behaviors of unilamellar vesicles and hard PS spheres of similar size is possibly due to the flexibility of the lipid bilayer of the vesicles. The unilamellar vesicles are capable of changing their shape to move through the entangled polymer solution so that the hindrance to their diffusion due to the presence of the polymer chains is reduced, while the rigid PS spheres have little flexibility and they encounter greater resistance. The multilamellar vesicles are less flexible, thus their diffusion is similar to the hard PS spheres of similar diameter.

Molecular cloning of a major human gall bladder mucin: complete C-terminal sequence and genomic organization of MUC5B

Gall bladder mucin has been shown to play a central role in the pathogenesis of cholesterol gallstone disease. While cloning and sequencing studies have provided a wealth of information on the structure of other gastrointestinal and respiratory mucins, nothing is known about the primary structure of human gall bladder mucin. In this study, we show that the tracheobronchial mucin MUC5B is a major mucin gene product expressed in the gall bladder. Antibodies directed against deglycosylated human gall bladder mucin were used to screen a gall bladder cDNA expression library, and most of the isolated clones contained repetitive sequences nearly identical with those in the tandem repeat region of MUC5B. An additional clone (hGBM2-3) contained an open reading frame coding for a 389 residue cysteine-rich sequence. The arrangement of cysteine residues in this sequence was very similar to that in the C-terminal regions of MUC2, MUC5AC and human von Willebrand factor. This cysteine-rich sequence was connected to a series of degenerate MUC5B tandem repeats in a 7.5 kb HincII genomic DNA fragment. This fragment, with ten exons and nine introns, contained MUC5B repeats in exon 1 and a 469 residue cysteine-rich sequence in exons 2-10 that provided a 152 nucleotide overlap with cDNA clone hGBM2-3. Interestingly, the exon-intron junctions in the MUC5B genomic fragment occurred at positions equivalent to those in the D4 domain of human von Willebrand factor, suggesting that these proteins evolved from a common evolutionary ancestor through addition or deletion of exons encoding functional domains.

Nitric oxide and gallbladder motility in prairie dogs

In this study we evaluated the role of nitric oxide (NO) on gallbladder motility in the normal prairie dog by 1) immunohistochemistry, 2) an enzymatic assay for NO synthase (NOS), and 3) an in vivo model to measure whole gallbladder tone and contractility. NOS was localized to gallbladder mucosal cells by NADPH-diaphorase and polyclonal antibodies to a constitutive brain NOS. Gallbladder mucosal homogenates demonstrated total NOS activity in the range of 578 +/- 115 pmol x mg protein(-1) x 30 min(-1). Blockade of NOS activity in vivo using N(omega)-nitro-L-arginine methyl ester resulted in an up to 80% increase in gallbladder tone from basal. A 40% increase in tone was seen with methylene blue, suggesting that tone was maintained by both NO activation of guanylate cyclase and possibly direct effects on Ca2+ channels. An exogenous nitrosothiol, S-nitroso-N-acetyl-cysteine, abolished cholecystokinin (CCK) octapeptide and bethanechol-stimulated gallbladder contraction. We conclude that the prairie dog gallbladder contains constitutive NOS and synthesizes NO, which is important for the maintenance of basal gallbladder tone and is an inhibitor of the contractile response of the gallbladder to agonists such as CCK and bethanechol.

The pronase resistance of cholesterol-nucleating glycoproteins in human bile

BACKGROUND & AIMS

Many putative pronucleating proteins have been isolated from the biliary concanavalin A (con A)-binding fraction. The pronase resistance of the overall nucleating-promoting activity was almost never taken into consideration. The aim of this study was to identify the major pronase-resistant con A-binding glycoproteins.

METHODS

Pronase-treated and -untreated con A-binding glycoproteins were separated on a Superose 12 gel permeation column (Pharmacia, Uppsala, Sweden) and tested in a crystal growth assay. Proteins were identified by amino-terminal sequencing.

RESULTS

Con A-binding pronucleating activity eluted in two peaks on the Superose column. This activity was unaltered after pronase treatment. Activity peak I contained too little protein to allow amino-terminal sequencing. In activity peak II, the major pronase-resistant con A-binding glycoproteins were identified as alpha 1-antitrypsin and alpha 1-antichymotrypsin. The 130-kilodalton nucleation promoter was identified as aminopeptidase N, but the full pronase resistance of this protein, reported earlier, was not confirmed. Immunoabsorptive removal of alpha 1-antitrypsin and alpha 1-antichymotrypsin and immunopurification showed that only alpha 1-antichymotrypsin had pronucleating activity.

CONCLUSIONS

The pronase resistance of the nucleating-promoting activity of the con A-binding glycoprotein fraction was confirmed. An important part of this activity could be attributed to alpha 1-antichymotrypsin. It is an acute-phase protein, as are many other pronucleating proteins, which might indicate a general mechanism of action in gallstone formation.

Interaction of bovine gallbladder mucin and calcium-binding protein: effects on calcium phosphate precipitation

BACKGROUND & AIMS

Gallstones consist of calcium salts and cholesterol crystals, arrayed on a matrix of gallbladder mucin (GBM), and regulatory proteins like calcium-binding protein (CBP). To determine if interactions between CBP and GBM follow a biomineralization scheme, their mutual binding and effects on CaHPO4 precipitation were studied.

METHODS

Binding of CBP to GBM was assessed by inhibition of the fluorescence of the complex of GBM with bis-1,8-anilinonaphthalene sulfonic acid (bis-ANS). The effects of the proteins on precipitation of CaHPO4 were assessed by nephelometry and gravimetry. Precipitates were analyzed for calcium, phosphate, and protein.

RESULTS

CBP and bis-ANS competitively displaced each other from 30 binding sites on mucin, with a 1:1 stoichiometry and similar affinity. The rate of precipitation of CaHPO4 was retarded by mucin and CBP. Precipitate mass was unaffected by GBM alone but decreased with the addition of CBP. Complexing CBP with GBM abolished or moderated this latter effect, altered precipitate morphology, and changed the stoichiometric ratios of Ca to PO4 in the precipitates from 1:1 to 3:2. Mucin and CBP were incorporated into the precipitates.

CONCLUSIONS

These studies suggest that the formation of calcium-containing gallstones is a biomineralization process regulated by both GBM and CBP.

Mucin-vesicle interactions in model bile: evidence for vesicle aggregation and fusion before cholesterol crystal formation

Nucleation of cholesterol monohydrate crystals from bile is a critical step in the formation of cholesterol gallstones. Measurement of nucleation in model bile system and the characteristics of the initial nucleus have proven elusive. In this study we have used three separate physical chemical techniques to examine vesicle aggregation and fusion, including dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescent biochemical assays. These assays enabled us to quantify the effect of biliary proteins, such as gallbladder mucin, on vesicle fusion and aggregation. In the absence of mucin, fusion is a relatively slow process occurring over 24 hours, whereas physiological concentrations of mucin are able to accelerate almost complete fusion of vesicles within 6 hours. Vesicle fusion and aggregation as characterized by TEM result in the formation of aggregates of multilamellar vesicles and giant fusion bodies associated with a background of mucin. These mucin-vesicle aggregate bodies may represent true nuclei and precede cholesterol monohydrate crystal nucleation. In future studies, these vesicle fusion assays can be used to quantitatively examine the effect of putative pro- and anti-nucleating proteins on the earliest steps of cholesterol crystal nucleation.

Bovine gall-bladder mucin contains two distinct tandem repeating sequences: evidence for scavenger receptor cysteine-rich repeats

Gall-bladder mucin is a densely glycosylated macromolecule which is the primary secretory product of the gall-bladder epithelium. It has been shown to bind cholesterol and other biliary lipids and to promote cholesterol crystal nucleation in vitro. In order to understand the molecular basis for mucin-lipid interactions, bovine gall-bladder mucin cDNAs were identified by expression cloning and were isolated and sequenced. The nucleotide sequences of these cDNAs revealed two distinct tandem repeating domains. One of these domains contained a 20-amino acid tandem repeating sequence enriched in threonine, serine and proline. This sequence was similar to, but not identical with, the short tandem repeating sequences identified previously in other mammalian mucins. The other domain contained a 127-amino acid tandem repeating sequence enriched in cysteine and glycine. This repeat displayed considerable sequence similarity to a family of receptor- and ligand-binding proteins containing scavenger receptor cysteine-rich repeats. By analogy with other proteins containing these cysteine-rich repeats, it is possible that, in gall-bladder mucin, this domain serves as a binding site for hydrophobic ligands such as bilirubin, cholesterol and other biliary lipids.

Identification of a 130-kilodalton human biliary concanavalin A binding protein as aminopeptidase N

BACKGROUND/AIMS

Human gallbladder bile contains a group of nonmucin glycoproteins that binds to the lectin concanavalin A (con A) and has been reported to promote cholesterol monohydrate crystal nucleation, an event preceding the formation of gallstones. Several of these proteins, including a 130-kilodalton protein, have been isolated and shown to promote nucleation in vitro. The aim of this study was to identify this and other major biliary con A binding glycoproteins.

METHODS

Gallbladder bile was chromatographed on con A agarose, and the eluted proteins were electrophoresed, blotted, and subjected to amino-terminal sequence analysis.

RESULTS

The major con A binding proteins were identified as aminopeptidase N (a 130-kilodalton protein), alpha 2 macroglobulin, hemopexin, immunoglobulin heavy chains, and the beta chain of haptoglobin. After further purification, aminopeptidase N was found to be enzymatically active and to promote cholesterol crystallization at its approximate physiological concentration in bile.

CONCLUSIONS

It is likely that aminopeptidase N is the previously characterized 130-kilodalton biliary crystallization promoting protein. Aminopeptidase N is probably released from the biliary canalicular membrane by the detergent activity of bile salts and may be one factor that promotes cholesterol crystallization in the gallbladder.

Bovine gallbladder mucin accelerates cholesterol monohydrate crystal growth in model bile

BACKGROUND

Gallbladder mucin accelerates cholesterol crystal nucleation, an early step in the pathogenesis of gallstones. To examine the role of gallbladder mucin in postnucleation gallstone maturation, the influence of mucin on cholesterol monohydrate crystal growth was studied in a novel model system.

METHODS

Cholesterol crystals of a uniform size were incubated in model biles at 37 degrees C with varying cholesterol saturation indices. Crystal size was quantitated by measuring the width and length of individual crystals under polarizing light microscopy and calculating average crystal area.

RESULTS

Crystal growth was dependent on the degree of cholesterol supersaturation of bile. Bovine gallbladder mucin (0.5-8 mg/mL) accelerated crystal growth in supersaturated model bile in a concentration- and time-dependent fashion compared with control incubations with bovine serum albumin or model bile alone (P < 0.05). Cholesterol crystal growth was accompanied by a progressive decrease in cholesterol saturation and an increase in total cholesterol crystal mass. Crystal growth was also accompanied by a decrease in total crystal number, suggesting net transfer of cholesterol to larger crystals.

CONCLUSIONS

The acceleration of cholesterol crystal growth by gallbladder mucin may be of pathophysiological importance in the postnucleation maturation of cholesterol gallstones.

Squamous metaplasia of extrahepatic biliary system in an AIDS patient with cryptosporidia and cholangitis

AIDS-related cholangiopathy is an increasingly recognized syndrome associated with significant morbidity and mortality. The mechanism of cholangiopathy is unknown but is assumed to be related to infectious pathogens such as CMV and cryptosporidia. The case of a Haitian with HIV and long-standing intestinal cryptosporidiosis who presented with cholangitis and protuberant intrabiliary filling defects is reported. Histopathological examination of biliary biopsies revealed previously unreported extensive squamous metaplasia of the bile duct epithelium, and the histogenesis of this condition is discussed. Chronic cryptosporidial infestation may be directly pathogenic resulting in squamous metaplasia that mimics biliary malignancy.

Cholesterol cholelithiasis in the prairie dog: role of mucin and nonmucin glycoproteins

The aims of this study were to examine the effect of exogenous prostaglandin on mucin secretion and to determine the role of nonmucin glycoproteins on gallstone formation in the prairie dog model of cholesterol cholelithiasis. The concentration of total glycoprotein and nonmucin glycoproteins was measured in gallbladder bile from four groups of prairie dogs fed a control diet or a diet supplemented with 1.2% cholesterol with or without simultaneous subcutaneous administration of prostaglandin E1. Cholesterol feeding resulted in an increased concentration of concanavalin-A binding-proteins in gallbladder bile associated with an increase in pronucleating activity in vitro. Treatment with prostaglandin E1 and cholesterol feeding was associated with a significant increase in the incidence of cholesterol gallstone formation. Prostaglandin E1 treatment in the cholesterol-fed animals increased biliary concentrations of total glycoprotein and concanavalin-A-binding glycoproteins. Therefore the increased biliary glycoprotein level in cholesterol-fed, prostaglandin E1-treated prairie dogs, which reflects higher levels of mucin and nonmucin glycoproteins, appears to be an important factor in gallstone formation.

Controlled trial of antimycobacterial therapy in Crohn's disease. Clofazimine versus placebo

In order to study the effect of clofazimine, a powerful antimycobacterial and antiinflammatory agent, 49 patients with active Crohn's disease were randomized to either corticosteroids plus clofazimine 100 mg daily (N = 25) or to steroids and matching placebo (N = 24). A total of 28 patients (58%) went into disease remission (clofazimine 16, placebo 12; P = NS) with a fall in disease activity score from 10.5 +/- 4.4 to 3.3 +/- 3.5. Patients were treated for a further eight months with clofazimine or placebo and 18 of 28 maintained their remission and completed the study (clofazimine 12, placebo 6; P = NS). Side effects were minor and consisted of skin rash and increased pigmentation. Clofazimine as a solitary antimycobacterial agent appears ineffective in inducing remission in Crohn's disease but may have a role in either disease maintenance or combination chemotherapy.

Characterization of bovine gallbladder mucin. Amino acid sequences of tryptic peptides from the glycosylated domain of the protein core

Gallbladder mucin is a densely glycosylated macro-molecule that promotes cholesterol gallstone formation in experimental animals and in humans. Bovine gallbladder mucin structure was studied after chemical deglycosylation by treatment with anhydrous hydrogen fluoride at 23 degrees C for 3 hours. Deglycosylated mucin contained less than 5% of the amino sugar and neutral hexose content of native mucin. Electrophoretic and molecular sieve chromatographic analyses indicated that significant cleavage of the mucin polypeptide core had occurred during deglycosylation. Deglycosylated mucin was separated into three major fractions by reverse-phase chromatography, one of which was enriched with respect to threonine and proline. Tryptic peptides prepared from this fraction were purified by molecular sieve and reverse-phase chromatography, and the amino acid sequences (8-20 residues) of the four principal tryptic peptides were determined. These peptides contained 65%-75% threonine and proline residues and demonstrated 80%-100% sequence similarity. These data provide the first information on the primary structure of gallbladder mucin and suggest that repeating amino acid sequences occur in this protein. Comparison of gallbladder mucin peptide structure with the consensus repeat sequence of human intestinal mucin showed approximately 60% sequence similarity. It was concluded that mammalian gastrointestinal mucins may be derived from a common ancestral gene.

Isolation and characterization of peptides from the protein core of bovine gallbladder mucin

Gallbladder mucin may promote cholesterol gallstone formation by accelerating cholesterol monohydrate crystal nucleation in supersaturated bile. In this study, peptides were isolated from the mucin protein core by protease digestion and molecular-sieve high-performance liquid chromatography. Tryptic peptides were purified by anion exchange or reverse-phase high-performance liquid chromatography, and amino acid compositions were determined. Tryptic peptides were (a) nonglycosylated, (b) selectively enriched in serine, glutamic acid plus glutamine, and glycine, and (c) depleted in threonine and proline compared with native gallbladder mucin. Bilirubin derivatized with Woodward's reagent K covalently bound to purified mucin. Tryptic digestion of the mucin-bilirubin complex yielded low-molecular-weight nonglycosylated peptides with covalently bound bilirubin. These data indicate that the mucin protein core contains at least two distinct domains. One domain is rich in threonine and proline and contains the majority of covalently bound carbohydrate. A second domain, possibly internally located, is nonglycosylated, enriched in serine, glutamic acid plus glutamine, and glycine, and binds hydrophobic ligands such as bilirubin and 1-anilino-8-naphthalene sulfonate. Hydrophobic domains on the mucin protein core may contribute to the pathogenesis of cholesterol cholelithiasis.

Remission induction in refractory Crohns disease using a high calorie whole diet

Eleven patients with severe refractory Crohns disease were treated with a high calorie, whole diet. Eight patients achieved remission with a drop in DAS from 13 to 4 (t = 6.31, p less than 0.001) and reversal of subacute obstruction in all cases. Nutritional parameters including weight, triceps skinfold thickness, arm muscle area, and serum albumin increased in all patients. The diet was well tolerated with a mean treatment period of 20 days. Clinical relapse of disease occurred in all cases within 9 months (mean 6 +/- 2 months). The mechanism of action of a high calorie diet (HCD) is unclear and warrants further study but antigen or specific food exclusion does not appear to be required as judged by this study.

Immunohistochemical Cal9-9 in primary colonic polyps and polyps synchronous with colorectal cancer

A prospective study was undertaken to examine the immunohistochemical expression of tumor antigen Cal9-9 in 56 colorectal cancers and 95 colonic adenomas, divided into 65 primary polyps and 30 polyps synchronous with colorectal cancer. Seventy five per cent of tumours were positive for Cal9-9. Antigen was expressed more frequently in advanced Duke's C and D and poorly differentiated colorectal cancer. Overall 51% of adenomas were positive for Cal9-9. Antigen expression correlated significantly with increasing size (p less than 0.001), synchronicity with colorectal cancer (p less than 0.001), severe dysplasia (p less than 0.001) and villous typing (p less than 0.003). Discriminate analysis using the first three variables correctly classified 79% of positive and 89% of negative Cal9-9 results. The similar frequency of antigen expression seen in colorectal cancers and their synchronous adenoma suggests a field change in the tumour bearing colon. Adenomas positive for Cal9-9 may have a greater malignant potential for carcinomatous change.