Association of genetic variations with NAFLD in lean individuals.

BACKGROUND & AIMS: How adiposity influences the effect of genetic variants on non-alcoholic fatty liver disease (NAFLD) in the Asian population remains unclear. We aimed to study the association between genetic risk variants and susceptibility/severity of NAFLD in the lean, overweight and obese individuals. METHODS: Nine hundred and four community subjects underwent proton-magnetic resonance spectroscopy and transient elastography examination. Lean (<23 kg/m2 ), overweight (23-24.9 kg/m2 ) and obesity (≥25 kg/m2 ) were defined according to the body mass index cut-offs for Asians. NAFLD was defined as intrahepatic triglycerides ≥5%. PNPLA3, TM6SF2, MBOAT7 and 9 other gene polymorphisms were analysed by rhAMPTM SNP assays. RESULTS: Five hundred and twenty-nine (58.5%), 162 (17.9%) and 213 (23.6%) subjects were lean, overweight and obese, respectively. The prevalence of NAFLD was 12.4%, 41.4% and 59.1% in the three groups (P < .001). Amongst those with NAFLD, lean subjects (30.3%) were more likely to carry the PNPLA3 rs738409 GG genotype than overweight (17.9%) and obese subjects (17.4%) (P = .003). Compared with the CC genotype, the GG genotype was associated with the greatest increase in the risk of NAFLD in lean subjects (odds ratio [OR] 6.04), compared with overweight (OR 3.43, 95% CI [1.06, 11.14]) and obese subjects (OR 2.51, 95% CI [0.93, 6.78]). Additionally, the TM6SF2 rs58542926 TT genotype was associated with reduced serum triglycerides only in lean subjects. A gene-BMI effect was not observed for the other gene polymorphisms. CONCLUSIONS: The PNPLA3 rs738409 gene polymorphism has a greater effect on liver fat in Asian lean individuals than in overweight or obese ones.

Adverse effects of vitamin D deficiency on outcomes of patients with chronic hepatitis B.

BACKGROUND & AIMS: Vitamin D is an immunomodulator that might be involved in the pathogenesis of viral hepatitis. We investigated the effects of vitamin D deficiency on long-term outcomes of patients with chronic hepatitis B (CHB). METHODS: We performed a prospective cohort study of 426 patients with CHB (65% male; mean age, 41 ± 13 years), who were enrolled from 1997 through 2000. Serum levels of 25-hydroxycholecalciferol (25(OH)D3) were measured on study enrollment (baseline). Patients were followed for 159 ± 46 months until last clinic visit or death; approximately 33% received antiviral therapy during the follow-up period. The primary outcome was a clinical event (hepatocellular carcinoma, complications of cirrhosis, or death). RESULTS: At baseline, the patients' mean serum level of hepatitis B virus DNA was 5.0 ± 2.1 log10 IU/mL; their mean level of 25(OH)D3 was 24.3 ± 9.4 ng/mL, and 348 patients (82%) had vitamin D deficiency (<32 ng/mL). Serum levels of 25(OH)D3 did not correlate with cirrhosis or viral load. Ninety-seven patients (22.8%) developed clinical events by a mean time of 118 ± 60 months after study enrollment. Patients who developed clinical events had lower baseline serum levels of 25(OH)D3 (23.2 ± 10.4 ng/mL) than patients who did not (28.2 ± 9.3 ng/mL, P < .001). Low baseline serum 25(OH)D3 was an independent factor associated with clinical events after adjustment for sex, age, and cirrhosis. The adjusted hazard ratio of vitamin D deficiency for clinical events was 1.90 (95% confidence interval [CI], 1.06-2.43; P = .04). The 15-year cumulative incidence rate of clinical events among patients with vitamin D deficiency was 25.5% (95% CI, 23.1%-27.9%), compared with 11.1% (95% CI, 7.4%-14.8%) in patients with normal serum levels of 25(OH)D3. CONCLUSIONS: Vitamin D deficiency is common among patients with CHB and is associated with adverse clinical outcomes.

On-treatment alpha-fetoprotein is a specific tumor marker for hepatocellular carcinoma in patients with chronic hepatitis B receiving entecavir.

UNLABELLED: Alpha-fetoprotein (AFP) is the most widely used biomarker for hepatocellular carcinoma (HCC) surveillance, which is criticized as neither sensitive nor specific in active hepatitis and liver cirrhosis. The aim of this study was to determine the performance of AFP as a tumor marker for HCC in entecavir-treated patients with chronic hepatitis B (CHB). This was a retrospective-prospective cohort study of 1,531 entecavir-treated patients under regular HCC surveillance with AFP and ultrasonography. Mean age was 52 ± 12 years; 1,099 (72%) patients were male and 332 (21.7%) had clinical evidence of cirrhosis. At a mean follow-up of 51 ± 13 months, 57 (2.9%) patients developed HCC (median size: 3.3 cm). AFP fluctuated with alanine aminotransferase (ALT) and peaked at the time of starting entecavir, then gradually decreased after. AFP started to increase 6 months before the diagnosis of HCC. The receiver operator characteristic curve (AUROC) of AFP was highest at the time of HCC diagnosis (0.85; 95% confidence interval [CI]: 0.73-0.98) and remained satisfactory at 3 (0.82; 95% CI: 0.73-0.91) and 6 months (0.79; 95% CI: 0.69-0.89) before the diagnosis. Using the conventional AFP cut-off (20 µg/L) at month 0, the sensitivity and specificity to diagnose HCC were 38.6% and 98.9%, respectively. Adopting the lower cut-off value (6 µg/L) of AFP level at month 0, sensitivity was increased to 80.7%, whereas specificity was decreased to 80.4%. CONCLUSION: On-treatment AFP is a specific tumor marker for HCC in CHB patients receiving entecavir therapy. Adopting a lower cut-off value of AFP level at 6 µg/L would significantly increase the sensitivity for HCC detection.

Noninvasive assessments of liver fibrosis with transient elastography and Hui index predict survival in patients with chronic hepatitis B.

BACKGROUND AND AIMS: The prognostic role of noninvasive assessments of liver fibrosis has been evolving. Our aim was to investigate the prognostic value of liver stiffness measurement (LSM) with transient elastography and serum-based Hui index to predict hepatic events and deaths in chronic hepatitis B (CHB) patients. METHODS: The main prospective cohort included 1555 consecutive CHB patients referred for transient elastography examination; a subgroup of 980 patients underwent follow-up assessments at least 3 years later formed the serial cohort. Cox proportional hazard model was performed to determine the relationship of LSM, Hui index and other clinical variables with hepatic events and deaths. RESULTS: During a mean follow-up of 69 ± 9 months, 119 patients (7.6%) developed hepatic events or deaths. Hepatic event-free survival was significantly decreased with increasing stages of LSM and Hui index. The 5-year cumulative probability of hepatic event-free survival of patients of Stage 1-7 of LSM were 99.3%, 98.8%, 95.7%, 90.9%, 89.6%, 74.6%, and 50.0%, respectively; that of Stage 1 to 3 of Hui index were 98.2%, 93.1%, and 77.5%, respectively. Independent predictors of hepatic event-free survival were age, baseline LSM, and follow-up Hui index. Serum ALT and body mass index affected the accuracy of prediction by LSM. Patients remained early stages of LSM or Hui index at follow-up visit had better survival compared to those remained at late stages. CONCLUSION: Baseline and change in noninvasive parameters of liver fibrosis, LSM and Hui index, are accurate to predict hepatic event-free survival in CHB patients.

Impact of IL28B and PNPLA3 polymorphisms on treatment outcomes in patients infected with genotype 6 hepatitis C virus.

BACKGROUND/AIMS: Interleukin-28B (IL28B) and patatin-like phospholipase domain containing 3 (PNPLA3) gene polymorphisms are associated with hepatitis C virus (HCV) clearance and fatty liver, respectively. We aimed to test if their polymorphisms are associated with virologic responses in Chinese chronic hepatitis C (CHC) patients. METHODS: This was a retrospective-prospective cohort study. Consecutive patients infected by genotype 1 and 6 HCV received antiviral therapy were included. Host IL-28B rs12979860/rs8099917 and PNPLA3 rs738409 genotype were tested. The primary outcome was sustained virologic response (sustained virologic response [SVR]: undetectable HCV RNA 24 weeks post-treatment). RESULTS: From 305 patients had positive antibody to HCV, 52 and 31 patients infected by genotype 1 and 6 HCV, respectively were recruited. Mean age was 58 ± 11 years; 70% were male. Mean baseline HCV RNA was 6.8 ± 2.7 log IU/ml. The SVR for patients infected by genotype 1 and 6 HCV was 67.3% and 90.3%, respectively. The proportions of IL28B genotypes were 78%, 21%, and 1% for TT/TG/GG at rs8099917, and 81%, 18%, and 1% for CC/TC/TT at rs12979860, respectively. The proportions of PNPLA3 rs738409 genotypes were 16%, 36%, and 48% for GG/GC/CC. IL28B genotype was significantly associated with SVR in patients infected by genotype 1 but not genotype 6 HCV, with 80% versus 38% of patients infected by genotype 1 achieved SVR carried TT versus TG/GG at rs8099917, respectively (P=0.003). PNPLA3 genotype was not associated with SVR. CONCLUSIONS: IL28B gene with rs8099917 T allele as an independent predictor of SVR in Chinese CHC patients infected by genotype 1 but not genotype 6 HCV.

Liver fibrosis progression is uncommon in patients with inactive chronic hepatitis B: a prospective cohort study with paired transient elastography examination.

BACKGROUND AND AIMS: The European Association for the Study of the Liver (EASL) defines the inactive hepatitis B virus (HBV) carrier state based on HBV DNA and alanine aminotransferase (ALT) levels. This study aimed to evaluate the risk of disease progression in such patients. METHODS: Three hundred sixty-one patients negative for hepatitis B e antigen (HBeAg) with HBV DNA levels < 20,000 IU/mL and normal ALT and without advanced fibrosis at baseline underwent liver stiffness measurement (LSM) by transient elastography between 2006 and 2008 and again between 2010 and 2012. Liver fibrosis progression was defined as an increase in LSM by 30% or more at the second assessment to levels suggestive of advanced fibrosis. RESULTS: At baseline, the mean age was 48 ± 11 years and 51% were males; ALT level was 28 ± 11 IU/L, HBV DNA level was 2.7 ± 1.0 log10 IU/mL, and LSM was 5.4 ± 1.5 kPa. After an interval of 44 ± 7 months, liver fibrosis progression was observed in 10 (2.8%) patients, and 49 (13.6%) started antiviral therapy. Gender, age, and levels of ALT, HBV DNA, and HBsAg were shown not to be associated with liver fibrosis progression. Among 244 patients with baseline HBV DNA < 2000 IU/mL, 2.9% had liver fibrosis progression, 8.2% started antiviral therapy, and 4.1% had HBV DNA ≥ 20,000 IU/mL during follow-up. Corresponding figures in 117 patients with baseline HBV DNA levels of 2000-20,000 IU/mL were 2.6%, 24.8%, and 7.7%, respectively (P = 1.0, < 0.001 and = 0.21 respectively). CONCLUSIONS: Liver fibrosis progression within 3-4 years is rare in HBeAg-negative patients with HBV DNA <20,000 IU/mL and normal ALT, but a significant proportion of patients develop treatment indications during follow-up. The study supports the EASL's definition of inactive carriers and its recommendation of regular monitoring.

Liver fibrosis progression in chronic hepatitis B patients positive for hepatitis B e antigen: a prospective cohort study with paired transient elastography examination.

BACKGROUND AND AIM: Chronic hepatitis B patients in immune-reactive hepatitis B e antigen (HBeAg)-positive phase may have more rapid progression than those in immune-tolerant phase. We aimed to evaluate the risk of liver fibrosis progression in HBeAg-positive patients at different phases. METHODS: Two hundred forty-seven HBeAg-positive patients without advanced fibrosis at baseline underwent liver stiffness measurement (LSM) by transient elastography in 2006-2008 and again in 2010-2012. Liver fibrosis progression was defined as increase in LSM by 30% or more to levels suggestive of advanced fibrosis at the second assessment. RESULTS: At baseline, the mean age was 38 ± 11 years, 58% were males, alanine aminotransferase (ALT) was 65 ± 52 IU/L, hepatitis B virus DNA was 4.2 ± 1.2 log IU/mL, and LSM was 6.3 ± 2.1 kPa. At an interval of 42 ± 6 months, 13 patients (5.2%) developed liver fibrosis progression, and 106 patients (42.9%) required antiviral therapy. None of the clinical parameters (e.g., gender, age, ALT, hepatitis B virus DNA, hepatitis B surface antigen level, etc.) was associated with liver fibrosis progression. Among 74 and 137 patients in immune-tolerant and immune-reactive phase, 4.1% and 6.6% had liver fibrosis progression, and 12.2% and 67.2% received antiviral therapy respectively (P = 0.45 and P < 0.001). Immune-tolerant patients with low-normal (< 0.5× upper limit of normal) or high-normal ALT (0.5-1× upper limit of normal) also had similar risk of liver fibrosis progression (5.7% vs. 2.6%; P = 0.49). CONCLUSIONS: Liver fibrosis progression is uncommon in HBeAg-positive patients. Patients in immune-reactive phase treated with antiviral therapy did not have increased risk of liver fibrosis progression.

Antiviral drug resistance testing in patients with chronic hepatitis B.

BACKGROUND: Antiviral drugs against hepatitis B virus are limited by the emergence of drug resistance. AIMS: We aimed to study the impact of drug resistance testing on treatment decisions. METHODS: In part 1 of this study, consecutive patients with chronic hepatitis B who had antiviral drug resistance testing were studied. Part 2 was a two-step questionnaire survey including ten characteristic case scenarios. Hepatologists were asked about their treatment decisions before and after the knowledge of drug resistance results. RESULTS: Fifty-one patients underwent drug resistance testing, most of whom were on lamivudine, adefovir dipivoxil or entecavir monotherapy. Thirty-four (67%) patients had drug-resistant mutants detected, 4 (8%) had low viral load, and 13 (25%) harboured wild-type virus. Twenty-nine of 34 (85%) patients harbouring drug-resistant mutants and 9 of 17 (53%) patients with no mutants detected changed their drug regimens (P = 0.038). In part 2, 18 hepatologists completed all two questionnaires. Overall, treatment decision was modified in 52% of cases upon receiving the drug resistance testing results. The detection of rtA181V/I resulted in decision changes in most hepatologists, with the preferred treatment switching from tenofovir to entecavir. When no mutants were detected in partial responders to entecavir monotherapy, most hepatologists chose to increase the dose of entecavir. CONCLUSIONS: Drug-resistant mutations are detected in around two-thirds of chronic hepatitis B patients undergoing drug resistance testing. Drug resistance testing alters management in over half of the cases, and should be considered in all patients with virological breakthrough and suboptimal virological suppression.

Viral determinants of hepatitis B surface antigen seroclearance in hepatitis B e antigen-negative chronic hepatitis B patients.

BACKGROUND: We studied whether quantification of serum HBsAg and HBV DNA levels could predict spontaneous HBsAg clearance in patients with negative hepatitis B e antigen (HBeAg). METHODS: Serum HBsAg and HBV DNA levels were measured at baseline among a longitudinal cohort of 103 HBeAg-negative patients recruited since 1997. RESULTS: Twelve (12%) patients developed HBsAg seroclearance after 88 ± 26 months (range, 21-139) of follow-up. At baseline, the serum HBsAg level among patients who cleared HBsAg (1.30 ± 1.27 log IU/mL) was significantly lower than those who did not clear HBsAg (2.96 ± 0.84 log IU/mL; P < .001). The area under receiver operating characteristics (ROC) curve for serum HBsAg to predict HBsAg seroclearance was 0.90 (95% confidence interval [CI], 0.83-0.97; P < .001). Nine (75%) of 12 patients who had HBsAg seroclearance versus 8 (9%) of 91 who remained HBsAg-positive had serum HBsAg ≤100 IU/mL at the baseline (P < .001). An HBsAg cutoff of ≤100 IU/mL had 75% sensitivity and 91% specificity to predict HBsAg seroclearance. Baseline serum HBV DNA could not predict HBsAg seroclearance; the area under ROC curve was 0.64 (95% CI, 0.46-0.81; P = .13). CONCLUSIONS: Single-point serum HBsAg level can predict the chance of HBsAg seroclearance in chronic hepatitis B patients with negative HBeAg.

A longitudinal study on the natural history of serum hepatitis B surface antigen changes in chronic hepatitis B.

UNLABELLED: Serum hepatitis B surface antigen (HBsAg) quantification has been suggested to reflect the concentration of covalently closed circular DNA in the liver. We aimed to investigate the HBsAg levels at different stages of chronic hepatitis B and the changes in HBsAg level during the natural progression of disease. One hundred seventeen untreated patients with chronic hepatitis B were studied with longitudinal follow-up for 99 ± 16 months. HBsAg quantification was performed at the first visit, the last visit, and three visits at each quartile during the follow-up. At the first visit, HBsAg level was higher among patients who were hepatitis B e antigen (HBeAg)-positive (N = 49) than those who were HBeAg-negative (N = 68) (4.01 ± 0.91 log IU/mL versus 2.73 ± 1.25 log IU/mL, P < 0.001). HBsAg level was persistently high at approximately 5 log IU/mL among patients in the immune tolerance phase (N = 7). The HBsAg levels among patients with HBeAg-positive active disease (N = 25) or sustained HBeAg seroconversion (N = 17) were comparable at approximately 3-4 log IU/mL. The HBsAg levels among patients who were HBeAg-negative tended to be higher among patients with active (N = 46) than those with inactive disease (N = 22). The median HBsAg levels decreased in HBeAg-negative patients with active and inactive disease by 0.041 log IU/mL/year and 0.043 log IU/mL/year, respectively. Twenty-two (17%) patients had HBsAg reduction >1 log IU/mL at the last visit; most of them showed reduced hepatitis B virus DNA, and eight had HBsAg loss. CONCLUSION: HBsAg remained stable in HBeAg-positive patients and tended to reduce slowly in HBeAg-negative patients. Reduction of HBsAg for >1 log IU/mL could reflect improved immune control.

Durability of peginterferon alfa-2b treatment at 5 years in patients with hepatitis B e antigen-positive chronic hepatitis B.

UNLABELLED: Approximately 30%-40% of patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B treated with peginterferon and/or lamivudine achieve HBeAg seroconversion 6 months after the end of treatment. The durability and long-term effect of treatment are unknown. In this study, 85 HBeAg-positive patients who received peginterferon alfa-2b 1.5 microg/kg/week for 32 weeks and lamivudine 100 mg/day for 52 or 104 weeks were prospectively followed for 6.1 +/- 1.7 years posttreatment. Twenty-five (29%) patients had virologic response (HBeAg seroconversion and HBV DNA <10,000 copies/mL) at 5 years. The rate of HBeAg seroconversion rose progressively from 37% at the end of treatment to 60% at 5 years. Twenty-seven (32%) and 11 (13%) patients had undetectable HBV DNA (<100 copies/mL) at the end of peginterferon treatment and at 5 years, respectively. Two (2.4%) patients achieved hepatitis B surface antigen (HBsAg) seroclearance at 2.6 and 84 months posttreatment. Among virologic responders at the end of treatment, 82% and 57% and sustained HBeAg seroconversion and virologic response at 5 years. End-of-treatment serum quantitative HBsAg was significantly lower in patients with sustained virologic response at 5 years (median 1,431 IU/mL versus 2,689 IU/mL [P = 0.041]). At the last follow-up, the liver stiffness measurement by transient elastography was 5.8 +/- 2.7 kPa. Only two patients had liver stiffness suggestive of advanced fibrosis. Week 16 HBV DNA, end-of-treatment HBeAg seroconversion, and undetectable HBV DNA were independent factors associated with virologic response at 5 years. The duration of concomitant lamivudine treatment had no impact on any long-term response. CONCLUSION: Peginterferon has high durability in HBeAg-positive chronic hepatitis B patients with end-of-treatment virologic response.

Hepatitis B virus genotype C is associated with more severe liver fibrosis than genotype B.

BACKGROUND & AIMS: Histologic analyses of liver fibrosis have been limited by small sample sizes and the predominance of samples from patients with active hepatitis. METHODS: We performed a prospective study of transient elastography in treatment-naive patients with chronic hepatitis B, to investigate the relationship between hepatitis B virus (HBV) genotype and liver fibrosis. A validated liver stiffness measurement algorithm was used to define insignificant fibrosis and advanced fibrosis. RESULTS: Of 1106 patients, 711 (64%) were older than age 40, 370 (34%) had positive test results for hepatitis B e antigen (HBeAg), and 386 (35%) had increased serum levels of alanine aminotransferase. Of the patients, 524 (49%) had genotype B and 582 (51%) had genotype C HBV infection. Patients with genotype C infection had insignificant fibrosis less often (42% vs 55%; P < .0001) and advanced fibrosis more often (25% vs 19%; P = .015) than those infected with genotype B HBV. The difference in the severity of liver fibrosis between the 2 HBV genotypes was most marked among patients older than age 40 and those who tested negative for HBeAg. The mean age of patients infected by genotype C was greater than that of patients infected by genotype B HBV (41 vs 36 y). Among patients who were older than age 40 and tested negative for HBeAg, those with genotype C infection had higher levels of HBV DNA and alanine aminotransferase than those with genotype B HBV. CONCLUSIONS: Genotype C HBV was associated with more severe liver fibrosis than genotype B HBV, probably because of delayed HBeAg seroconversion and prolonged active disease.

Genotype-specific genomic markers associated with primary hepatomas, based on complete genomic sequencing of hepatitis B virus.

We aimed to identify genomic markers in hepatitis B virus (HBV) that are associated with hepatocellular carcinoma (HCC) development by comparing the complete genomic sequences of HBVs among patients with HCC and those without. One hundred patients with HBV-related HCC and 100 age-matched HBV-infected non-HCC patients (controls) were studied. HBV DNA from serum was directly sequenced to study the whole viral genome. Data mining and rule learning were employed to develop diagnostic algorithms. An independent cohort of 132 cases (43 HCC and 89 non-HCC) was used to validate the accuracy of these algorithms. Among the 100 cases of HCC, 37 had genotype B (all subgenotype Ba) and 63 had genotype C (16 subgenotype Ce and 47 subgenotype Cs) HBV infection. In the control group, 51 had genotype B and 49 had genotype C (10 subgenotype Ce and 39 subgenotype Cs) HBV infection. Genomic algorithms associated with HCC were derived based on genotype/subgenotype-specific mutations. In genotype B HBV, mutations C1165T, A1762T and G1764A, T2712C/A/G, and A/T2525C were associated with HCC. HCC-related mutations T31C, T53C, and A1499G were associated with HBV subgenotype Ce, and mutations G1613A, G1899A, T2170C/G, and T2441C were associated with HBV subgenotype Cs. Amino acid changes caused by these mutations were found in the X, envelope, and precore/core regions in association with HBV genotype B, Ce, and Cs, respectively. In conclusion, infections with different genotypes of HBV (B, Ce, and Cs) carry different genomic markers for HCC at different parts of the HBV genome. Different HBV genotypes may have different virologic mechanisms of hepatocarcinogenesis.

Lamivudine monoprophylaxis and adefovir salvage for liver transplantation in chronic hepatitis B: a seven-year follow-up study.

In Asia Pacific countries, lamivudine is used frequently as the sole prophylaxis for hepatitis B virus (HBV) recurrence after liver transplantation due to financial consideration. The aim was to evaluate the long-term outcome of lamivudine monoprophylaxis with adefovir salvage for liver transplantation in chronic hepatitis B. Consecutive chronic hepatitis B patients who received liver transplantation from 1999 to 2003 and with at least 12 months follow up were studied. Lamivudine monotherapy was used for antiviral prophylaxis and adefovir was added as salvage treatment for recurrence of HBV. Twenty-four patients were followed up for 272 (76-372) weeks post-liver transplantation. HBV recurrence developed in seven patients with cumulative probabilities of 8%, 13%, 28%, 35%, 35%, and 49% in 1, 2, 3, 4, 5, and 6 years. At the time of recurrence of HBV, the HBV DNA level was 910,244 (363 to 9 x 10(8)) copies/ml. On direct sequencing, four patients had rtM204I mutation and three patients HBV DNA levels were too low for sequencing. Six patients had elevated ALT (two patients had ALT >1,000 IU/L and jaundice) but none had hepatic encephalopathy. After adefovir treatment for 150 (91-193) weeks, six (86%) patients had normal ALT. HBV DNA was undetectable in two (29%) patients, 100-1,000 copies/ml in two (29%) patients and 10,000-100,000 copies/ml in three (43%) patients on last visit. No genotypic resistance to adefovir was detected. Lamivudine followed by adefovir salvage is effective for prophylaxis of recurrence of HBV after liver transplantation up to 7 years.

Affordable Membrane Permeability Calculations: Permeation of Short-Chain Alcohols through Pure-Lipid Bilayers and a Mammalian Cell Membrane.

Determination of membrane permeability to small molecules from first-principles represents a promising approach for screening lead compounds according to their permeation properties upstream in the drug discovery process and prior to their synthesis. Theoretical investigation of permeation events requires, at its core, a molecular model of the membrane, and the choice of this model impacts not only the predicted permeability but also its relation to the experimental measurements commonly performed in pharmaceutical settings with a variety of cell lines capable of mimicking intestinal passive permeation. Homogeneous single-lipid bilayers have traditionally been utilized in computer simulations of membrane permeability predictions due to the ease of sampling all the relevant configurations, as well as the availability of parameters for a range of components of the biological membrane. To assess the influence of the membrane heterogeneity on the permeability to small molecules, we have examined the permeation of ethanol in six different single-lipid bilayers and compared the computed free-energy and diffusivity profiles with those obtained using a mammalian cell membrane model consisting of 26 components. Our results suggest that the membrane permeability only mildly depends on the lipid composition, spanning only 1 order of magnitude between the small phosphoethanolamine and the large phosphocholine head groups, or the short, saturated lauryl and the long, unsaturated oleyl acyl chains, that is, nearly as close as current theoretical estimates can get to experiment. The staggering computer time required to obtain an accurate free-energy profile, devoid of hysteresis between the upper and the lower leaflets of the lipid bilayer, in excess of several microseconds, provides an impetus for the development of approximate routes for membrane permeability predictions. Here, we have modeled the free-energy profile underlying permeation by means of a series of free-energy perturbation calculations, whereby the substrate is reversibly coupled to its environment at fixed values in the direction normal to the lipid bilayer. The diffusivity profile is modeled based on the bulk self-diffusion of the permeant, and the membrane permeability is recovered without significant loss of accuracy. The proposed numerical approach can be seamlessly extended to the determination of the relative membrane permeability to alternate substrates, thereby allowing large sets of permeants to be screened at a fraction of the computational cost of a rigorous determination of their respective free-energy profile.

Link between Membrane Composition and Permeability to Drugs.

Prediction of membrane permeability to small molecules represents an important aspect of drug discovery. First-principles calculations of this quantity require an accurate description of both the thermodynamics and kinetics that underlie translocation of the permeant across the lipid bilayer. In this contribution, the membrane permeability to three drugs, or drug-like molecules, namely, 9-anthroic acid (ANA), 2',3'-dideoxyadenosine (DDA), and hydrocortisone (HYL), are estimated in a pure 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and in a POPC:cholesterol (2:1) mixture. On the basis of independent 2-5-µs free-energy calculations combined with a time-fractional Smoluchowski determination of the diffusivity, the estimated membrane permeabilities to these chemically diverse permeants fall within an order of magnitude from the experimental values obtained in egg-lecithin bilayers, with the exception of HYL in pure POPC. This exception is particularly interesting because the calculated permeability of the sterol-rich bilayer to HYL, in close agreement with the experimental value, is about 600 times lower than that of the pure POPC bilayer to HYL. In contrast, the permeabilities to ANA and DDA differ by less than a factor of 10 between the pure POPC and POPC:cholesterol bilayers. The unusual behavior of HYL, a large, amphiphilic compound, may be linked with the longer range perturbation of the lipid bilayer it induces, compared to ANA and DDA, suggestive of a possibly different translocation mechanism. We find that the tendency of lower permeabilities of the POPC:cholesterol bilayer relative to those of the pure POPC one is a consequence of increased free-energy barriers. Beyond reporting accurate estimates of the membrane permeability, the present contribution also demonstrates that rigorous free-energy calculations and a fractional-diffusion model are key in revealing the molecular phenomena linking the composition of a membrane to its permeability to drugs.

Serum hepatitis B surface antigen quantitation can reflect hepatitis B virus in the liver and predict treatment response.

BACKGROUND & AIMS: We aimed to evaluate serum hepatitis B surface antigen (HBsAg) quantitation as a surrogate marker for covalently closed circular DNA (cccDNA) and intrahepatic hepatitis B virus (HBV) DNA, and as a predictor of sustained virologic response to peginterferon and lamivudine combination therapy. METHODS: Twenty-six hepatitis B e antigen-positive chronic hepatitis B patients receiving combination treatment of 32-week peginterferon alfa-2b and 2-year lamivudine were studied. All patients had liver biopsy before and after treatment for cccDNA and intrahepatic HBV DNA measurement. Sustained virologic response was defined as sustained hepatitis B e antigen seroconversion and HBV DNA less than 10,000 copies/mL at the end of treatment until 1 year posttreatment. RESULTS: Seven patients developed sustained virologic response. At baseline, HBsAg correlated well with both log (cccDNA) (r = 0.54, P = .004) and log [total intrahepatic HBV DNA] (r = 0.43, P = .028). The median reduction of HBsAg was 1287 IU/mL (range, 12,223-26,763 IU/mL). Reduction of HBsAg has good correlation with reduction in log [cccDNA] (r = 0.68, P < .0001) and reduction in log [total intrahepatic HBV DNA] (r = 0.65, P < .0001). Patients with lower baseline cccDNA, intrahepatic HBV DNA, and HBsAg level but not serum HBV DNA level tend to develop sustained virologic response. A baseline HBsAg level of less than 10,000 IU/mL had sensitivity, specificity, and positive and negative predictive values for sustained virologic response of 86%, 56%, 43%, and 92%, respectively. CONCLUSIONS: Serum HBsAg levels correlate well with the cccDNA and intrahepatic HBV DNA. Low pretreatment HBsAg is better than HBV DNA to predict good response to peginterferon and lamivudine treatment.

Serum hepatitis B surface antigen kinetics in severe reactivation of hepatitis B e antigen negative chronic hepatitis B patients receiving nucleoside/nucleotide analogues.

BACKGROUND: Kinetics of serum hepatitis B surface antigen (HBsAg) level in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B patients presented with severe reactivation and received oral antiviral therapy is unknown. We aimed to investigate the kinetics of HBsAg level among these patients. METHODS: HBeAg-negative patients on antiviral therapy with follow-up for 2 years were studied. Those presented with severe reactivation (alanine aminotransferase [ALT] ≥5 times of normal) were compared to those with mild hepatitis. Serum HBsAg level was measured by Elecsys HBsAg II Quant assay (Roche) at baseline and 6-monthly. RESULTS: A total of 192 (74 severe reactivation) patients were studied. Eighty-one (42%), 74 (39%) and 37 (19%) patients were on lamivudine, entecavir and telbivudine, respectively. Forty-four (23%) patients had early HBsAg decline, that is, ≥0.5 log10 reduction, at month 6. Patients with severe reactivation had higher serum baseline ALT (1,415 ±897 versus 73 ±39 IU/l), HBV DNA (6.4 ±1.6 versus 5.2 ±1.2 log10 IU/ml) and HBsAg (3.3 ±1.0 versus 2.9 ±0.6 log10 IU/ml), as well as an earlier HBsAg decline (50% versus 6%; all P<0.001) than those without. The HBsAg change of patients with severe reactivation was higher at months 0-6 (-0.58 ±-1.26 versus -0.01 ±-0.26 log10 IU/ml; P<0.001) but then became comparable from months 6-24 (-0.19 ±-0.60 versus -0.13 ±-0.19 log10 IU/ml; P=0.85), compared to those presented with mild hepatitis. CONCLUSIONS: Patients who presented with severe reactivation of HBeAg-negative hepatitis were more likely to develop early HBsAg decline during antiviral therapy. It may indicate a transient strong immune clearance with rapid initial reduction in serum HBsAg, which cannot be sustained due to a faster clearance of serum HBsAg.

Molecular characterization of the fecal microbiota in patients with nonalcoholic steatohepatitis--a longitudinal study.

BACKGROUND: The human gut microbiota has profound influence on host metabolism and immunity. This study characterized the fecal microbiota in patients with nonalcoholic steatohepatitis (NASH). The relationship between microbiota changes and changes in hepatic steatosis was also studied. METHODS: Fecal microbiota of histology-proven NASH patients and healthy controls was analyzed by 16S ribosomal RNA pyrosequencing. NASH patients were from a previously reported randomized trial on probiotic treatment. Proton-magnetic resonance spectroscopy was performed to monitor changes in intrahepatic triglyceride content (IHTG). RESULTS: A total of 420,344 16S sequences with acceptable quality were obtained from 16 NASH patients and 22 controls. NASH patients had lower fecal abundance of Faecalibacterium and Anaerosporobacter but higher abundance of Parabacteroides and Allisonella. Partial least-square discriminant analysis yielded a model of 10 genera that discriminated NASH patients from controls. At month 6, 6 of 7 patients in the probiotic group and 4 of 9 patients in the usual care group had improvement in IHTG (P=0.15). Improvement in IHTG was associated with a reduction in the abundance of Firmicutes (R(2)=0.4820, P=0.0028) and increase in Bacteroidetes (R(2)=0.4366, P=0.0053). This was accompanied by corresponding changes at the class, order and genus levels. In contrast, bacterial biodiversity did not differ between NASH patients and controls, and did not change with probiotic treatment. CONCLUSIONS: NASH patients have fecal dysbiosis, and changes in microbiota correlate with improvement in hepatic steatosis. Further studies are required to investigate the mechanism underlying the interaction between gut microbes and the liver.