[Clinical, biochemical and epidemiological features of macro-AST preceding inflammatory bowel disease diagnosis by several years]

INTRODUCTION

An isolated elevation of aspartate aminotransferase (AST) is a diagnostic issue. Macro-aspartate aminotransferase (macro-AST) corresponds to the formation of complexes between AST and immunoglobulins.

CASE REPORT

We report the case of a patient with macro-AST identified several years before the onset of inflammatory bowel disease (IBD). A 6-year retrospective analysis in our laboratory identified only one case out of 42 540 adult patients.

CONCLUSION

The objective of this work is to increase awareness of this benign disorder among clinicians and biologists, as well as to aid in prescribing only the required tests.

Development and validation of a UPLC-UV method for the quantification of thiopurine methyltransferase enzyme activity in human erythrocytes

Thiopurines are drugs widely used for the treatment of autoimmune conditions, inflammatory bowel disease or acute lymphoblastic leukemia. Determination of thiopurine methyltransferase activity (TPMT), a major determinant of thiopurines toxicity, has been suggested before implementing thiopurine treatment. An ultraperformance liquid chromatography (UPLC) method was developed and validated for the quantification of TPMT enzyme activity based on the conversion of 6-mercaptopurine (6-MP) to 6-methylmercaptopurine (6-MMP) using S-adenosyl-L-methionine (SAM) as methyl donor in red blood cell lysates (RBC). This method was improved from a previous laborious high performance liquid chromatography (HPLC) method, using a lower volume of injection and with a shorter runtime. After incubation and protein precipitation 6-MMP was separated on a HSS-T3 (2.1 × 50 mm, 1.8 μm) column and monitored by UV detection (290 nm). A change on the organic solvent used to dissolve 6-MP resulted in a reduction of interference by endogenous or non-enzymatic methylated 6-MMP. A full validation of the 6-MMP assay was performed according to the FDA and EMA guidelines. The method was linear from 0.125 to 2 nmol/mL, with acceptable values of accuracy and precision. The method was applied in 106 patients treated with thiopurines whose TPMT activity was previously quantified by HPLC. Evaluation through Bland-Altman plot showed that TPMT activities were in agreement between both methods.

Predictive Modeling of Tacrolimus Dose Requirement Based on High-Throughput Genetic Screening

Any biochemical reaction underlying drug metabolism depends on individual gene-drug interactions and on groups of genes interacting together. Based on a high-throughput genetic approach, we sought to identify a set of covariant single-nucleotide polymorphisms predictive of interindividual tacrolimus (Tac) dose requirement variability. Tac blood concentrations (Tac C₀ ) of 229 kidney transplant recipients were repeatedly monitored after transplantation over 3 mo. Given the high dimension of the genomic data in comparison to the low number of observations and the high multicolinearity among the variables (gene variants), we developed an original predictive approach that integrates an ensemble variable-selection strategy to reinforce the stability of the variable-selection process and multivariate modeling. Our predictive models explained up to 70% of total variability in Tac C₀ per dose with a maximum of 44 gene variants (p-value <0.001 with a permutation test). These models included molecular networks of drug metabolism with oxidoreductase activities and the multidrug-resistant ABCC8 transporter, which was found in the most stringent model. Finally, we identified an intronic variant of the gene encoding SLC28A3, a drug transporter, as a key gene involved in Tac metabolism, and we confirmed it in an independent validation cohort.

Interindividual variability in dabigatran and rivaroxaban exposure: contribution of ABCB1 genetic polymorphisms and interaction with clarithromycin

Essentials Rivaroxaban and dabigatran are substrates of the P-glycoprotein (P-gp) encoded by the ABCB1 gene. We tested the effect of ABCB1 polymorphisms and of a P-gp inhibitor on both drugs' pharmacokinetics. The ABCB1 genotype was not a clinically relevant determinant of both drugs' pharmacokinetics. Administration of P-gp inhibitors with dabigatran or rivaroxaban should be exercised with caution.

SUMMARY

Background The direct oral anticoagulants (DOACs) dabigatran and rivaroxaban are both substrates of the P-glycoprotein (P-gp) transporter, encoded by the ABCB1 gene. Rivaroxaban is metabolized by cytochrome P450 A4 (CYP3A4). Interindividual variability in DOAC exposure and frequent P-gp-associated drug-drug interactions have been described in patients. Objective To assess the influence of ABCB1 polymorphisms on the pharmacokinetics of dabigatran and rivaroxaban, associated or not with clarithromycin, a P-gp and CYP3A4 inhibitor. Methods Sixty healthy male volunteers, selected according to ABCB1 genotype (20 homozygous mutated, 20 heterozygous mutated, and 20 wild-type for haplotype 2677-3435), were included in this randomized, two-center, crossover study. All received sequentially a single dose of dabigatran etexilate (300 mg) and rivaroxaban (40 mg) associated or not with clarithromycin. Peak plasma concentration and area under the curve (AUC) were compared across the three ABCB1 genotypes. The effect of clarithromycin on dabigatran or rivaroxaban pharmacokinetics was assessed. Results Interindividual coefficients of variation for AUC were 77% for dabigatran and 51% for rivaroxaban. ABCB1 genotype did not significantly affect drug pharmacokinetics: AUC ratios between mutant-allele carriers and wild-type volunteers were 1.27 (95% confidence interval [CI] 0.84-1.92) and 1.20 (95% CI 0.96-1.51) for dabigatran and rivaroxaban, respectively. Clarithromycin coadministration led to a two-fold increase in both drugs' AUC, irrespective of ABCB1 genotype: ratios of geometric means were 2.0 (95% CI 1.15-3.60) and 1.94 (95% CI 1.42-2.63) for dabigatran and rivaroxaban, respectively. Conclusions ABCB1 genotype is not a significant determinant of interindividual variability in dabigatran and rivaroxaban pharmacokinetics. The levels of one drug did not predict the levels of the other. Coadministration of a P-gp/CYP3A4 inhibitor with dabigatran or rivaroxaban may warrant caution in patients at risk of overexposure.

Long-Term Clinical Impact of Adaptation of Initial Tacrolimus Dosing to CYP3A5 Genotype

Pretransplantation adaptation of the daily dose of tacrolimus to CYP3A5 genotype is associated with improved achievement of target trough concentration (C0 ), but whether this improvement affects clinical outcomes is unknown. In the present study, we have evaluated the long-term clinical impact of the adaptation of initial tacrolimus dosing according to CYP3A5 genotype: The transplantation outcomes of the 236 kidney transplant recipients included in the Tactique study were retrospectively investigated over a period of more than 5 years. In the Tactique study, patients were randomly assigned to receive tacrolimus at either a fixed dosage or a dosage determined by their genotype, and the primary efficacy end point was the proportion of patients for whom tacrolimus C0 was within target range (10-15 ng/mL) at day 10. Our results indicate that the incidence of biopsy-proven acute rejection and graft survival were similar between the control and the adapted tacrolimus dose groups, as well as between the patients who achieve the tacrolimus C0 target ranges earlier. Patients' death, cancer, cardiovascular events, and infections were also similar, and renal function did not change. We conclude that optimization of initial tacrolimus dose using pharmacogenetic testing does not improve clinical outcomes.

Kidney transplant recipients carrying the CYP3A4*22 allelic variant have reduced tacrolimus clearance and often reach supratherapeutic tacrolimus concentrations

CYP3A4*22 is an allelic variant of the cytochrome P450 3A4 associated with a decreased activity. Carriers of this polymorphism may require reduced tacrolimus (Tac) doses to reach the target residual concentrations (Co). We tested this hypothesis in a population of kidney transplant recipients extracted from a multicenter, prospective and randomized study. Among the 186 kidney transplant recipients included, 9.3% (18 patients) were heterozygous for the CYP3A4*22 genotype and none were homozygous (allele frequency of 4.8%). Ten days after transplantation (3 days after starting treatment with Tac), 11% of the CYP3A4*22 carriers were within the target range of Tac Co (10-15 ng/mL), whereas among the CYP3A4*1/*1 carriers, 40% were within the target range (p = 0.02, OR = 0.19 [0.03; 0.69]). The mean Tac Co at day 10 in the CYP3A4*1/*22 group was 23.5 ng/mL (16.6-30.9) compared with 15.1 ng/mL (14-16.3) in the CYP3A4*1/*1 group, p < 0.001. The Tac Co/dose significantly depended on the CYP3A4 genotype during the follow-up (random effects model, p < 0.001) with the corresponding equivalent dose for patients heterozygous for CYP3A4*22 being 0.67 [0.54; 0.84] times the dose for CYP3A4*1/*1 carriers. In conclusion, the CYP3A4*22 allelic variant is associated with a significantly altered Tac metabolism and carriers of this polymorphism often reach supratherapeutic concentrations.

Influence of genetics and non-genetic factors on acenocoumarol maintenance dose requirement in Moroccan patients

WHAT IS KNOWN AND OBJECTIVE

Coumarin derivatives such as acenocoumarol represent the therapy of choice for the long-term treatment and prevention of thromboembolic diseases. Many genetic, clinical and demographic factors have been shown to influence the anticoagulant dosage. Our aim was to investigate the contribution of genetic and non-genetic factors to variability in response to acenocoumarol in Moroccan patients.

METHODS

Our study included 114 adult Moroccan patients, receiving long-term acenocoumarol therapy for various indications. Tests for VKORC1 -1639G>A promoter polymorphism (rs9923231), CYP2C9*2 rs1799853, CYP2C9*3 rs1057910, and CYP4F2 rs2108622 alleles were undertaken using Taq Man(®) Pre-Developed Assay Reagents for allelic discrimination. The statistical analysis was performed using the SAS V9 statistical package.

RESULTS AND DISCUSSION

Genotyping showed that the allele frequencies for the SNPs studied were no different to those found in Caucasians population. A significant association was observed between the weekly maintenance dose and the VKORC1 (P = 0·0027) and CYP2C9 variant genotypes (P = 0·0082). A final multivariate regression model that included the target International Normalized Ratio, VKORC1 and CYP2C9 genotypes explained 36·2% of the overall interindividual variability in acenocoumarol dose requirement.

WHAT IS NEW AND CONCLUSION

Our study shows large interindividual variability in acenocoumarol maintenance dose requirement in our population. VKORC1 and CYP2C9 variants significantly affected acenocoumarol dose, in-line with results in other populations. For the Moroccan population, the SNPs that have the largest effect on acecoumarol dose are CYP2C9 rs1799853, CYP2C9 rs1057910 and VKORC1 rs9923231.

Optimization of initial tacrolimus dose using pharmacogenetic testing

Retrospective studies have demonstrated that patients who are expressors of cytochrome P4503A5 (CYP3A5) require a higher tacrolimus dose to achieve a therapeutic trough concentration (C(0)). The aim of this study was to evaluate this effect prospectively by pretransplantation adaptation. We randomly assigned 280 renal transplant recipients to receive tacrolimus either according to CYP3A5 genotype or according to the standard daily regimen. The primary end point was the proportion of patients within the targeted C(0). Secondary end points included the number of dose modifications and the delay in achieving the targeted C(0). In the group receiving the adapted dose, a higher proportion of patients had values within the targeted C(0) at day 3 after initiation of tacrolimus (43.2% vs. 29.1%; P = 0.03); they required fewer dose modifications, and the targeted C(0) was achieved by 75% of these patients more rapidly. The clinical end points were similar in the two groups. Pharmacogenetic adaptation of the daily dose of tacrolimus is associated with improved achievement of the target C(0). Whether this improvement will affect clinical outcomes requires further evaluation.

Characterisation of novel defective thiopurine S-methyltransferase allelic variants

Human thiopurine S-methyltransferase (TPMT, EC 2.1.1.67) is a key enzyme in the detoxification of thiopurine drugs widely used in the treatment of various diseases, such as inflammatory bowel diseases, acute lymphoblastic leukaemia and rheumatic diseases. The TPMT gene is genetically polymorphic and the inverse relationship between TPMT activity and the risk of developing severe hematopoietic toxicity is well known. In this study, the entire coding sequence of TPMT, together with its 5'-flanking promoter region, was analysed in patients with an intermediate phenotype for thiopurine drug methylation. Four polymorphisms were identified, two previously described, c.356A>C (p.Lys(119)Thr, TPMT*9) and c.205C>G (p.Leu(69)Val, TPMT*21), and two novel missense mutations, c.537G>T (p.Gln(179)His, TPMT*24) and c.634T>C (p.Cys(212)Arg, TPMT*25). Structural investigations, using molecular modeling, were undertaken in an attempt to explain the potential impact of the amino acid substitutions on the structure and activity of the variant proteins. Additionally, in order to determine kinetic parameters (K(m) and V(max)) of 6-thioguanine (6-TG) methylation, the four variants were expressed in a recombinant yeast expression system. Assays were performed by HPLC and the results were compared with those of wild-type TPMT. The p.Leu(69)Val and the p.Cys(212)Arg substitutions encode recombinant enzymes with a significantly decreased intrinsic clearance compared to that of the wild-type protein, and, consequently, characterise non-functional alleles of TPMT. The p.Lys(119)Thr and the p.Gln(179)His substitutions do not affect significantly the catalytic activity of the corresponding variant proteins, which prevents to unambiguously describe these latter alleles as defective TPMT variants.

Pharmacogenetic analysis of toxicity after 5-fluorouracil (5FU) or 5FU/oxaliplatin therapy for metastatic colorectal cancer: Preliminary results in FFCD 2000–05 trial

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Background: The FFCD 2000–05 randomized trial compared simplified LV5FU2 followed by FOLFOX6 (arm 1) to FOLFOX6 followed by FOLFIRI (arm 2) in the treatment of metastatic colorectal cancer. The aim was predicting the toxicity profile of oxaliplatin after the first line treatment using pharmacogenetic data. Methods: Patients (pts) with available blood samples were compared to the other pts for clinical prognostic factors (chi2 test). A logistic model was computed to test the association between polymorphisms and toxicity in each arm. An interaction test was used to assess a differential effect according to treatment (predictive effect), in order to identify a predictive effect of oxaliplatin. Grade 3–4 hematological and non-hematological toxicities (H-tox and NH-tox) at 4 months and grade 2–4 neurological at 6 months were the endpoints of the study. Thirteen genetic variants in 10 candidate genes were selected for pharmacogenetic analysis: ERCC1_04 (rs3212961), ERCC1_05 (rs11615), ERCC1_06 (rs3212948), ERCC1_24 (rs3212955), ERCC2_02 (rs1799793), ERCC2_03 (rs13181), ERCC2_06 ( rs238406 ), ERCC2_09 (rs1799787), GSTM1 (null/present), GSTT1 (null/present), TS (TSER, Ins/del6bp) and UGT1A1 (rs8175347). Genotyping was performed using Taqman probes, QMPSF and fragment analysis. Results: 327 pts (156/171) out of 410 were included (61 had no blood samples, 16 had less than 2 cycles, 3 had incomplete data on toxicity, 3 had insufficient DNA). No difference was found between included and excluded pts in the analysis for gender, age, OMS, number of metastatic organs and adjuvant chemotherapy. Pts received similar 5FU doses in both arms. Number of patients with at least one toxicity in arms 1/2 were as followed: 5/54 grade 3–4 H-tox, 28/47 grade 3–4 NH-tox, and 0/103 grade 2–4 neurological. The genotype CC of ERCC2_02 correlated with higher NH-tox at 4 months in arm 2 (p=0.0008, OR=0.31, 95%CI=[0.15–0.62] versus p=0.87, OR=0.93, CI=[0.39–2.21] in arm 1) compared to genotypes CT and TT, with borderline interaction (p=0.05). Conclusions: These preliminary results on early toxicity in first-line are in favour of an effect of ERCC2_02 on NH-tox of FOLFOX6 and a predictive effect on NH-tox of oxaliplatin.

[Table: see text]

Genetic and environmental risk factors for oral anticoagulant overdose

BACKGROUND

Cytochrome P450 2C9 (CYP2C9) allelic variant carriers have been shown to experience hyper-responsiveness to small doses of oral anticoagulants (OAs) (warfarin or acenocoumarol) and a higher bleeding rate.

OBJECTIVES

To determine the relative frequencies of different risk factors for OA overdose including diet, concomitant diseases, drug interactions, recent increment of OA dose and CYP2C9 genetic polymorphism among hospitalised patients.

MATERIALS AND METHODS

Frequencies of the different risk factors for OA overdose were determined in a prospective case-control study. Seventy-five consecutive patients with an International normalised ratio (INR) greater than 4 were matched with seventy-five control patients with an INR greater than 2 but less than 3.5 with respect to age, prescribed OA and daily dose. Genotyping of CYP2C9*2 and CYP2C9*3 allelic variants was detected by the TaqMan allelic discrimination assay.

RESULTS

Drug interactions and a recent increment of OA dose were the only significant independent risk factors identified in the first analysis with odds ratio 2.13 (95% CI: 1.06-4.28) and 3.38 (95%CI: 1.51-7.57), respectively. A recent increment of OA dose was the only significant independent risk factor identified among the patients treated with coumarin derivatives (acenocoumarol or warfarin), excluding those treated with fluindione; the odds ratio was 4.3 (95% CI: 1.5-12.3). CYP2C9 genetic polymorphism did not significantly predict the increased risk of OA overanticoagulation in this study. However three homozygous CYP2C9*3/CYP2C9*3 genotype patients were found among the cases, whereas no such patients could be identified among controls.

CONCLUSION

This is the first observational study investigating the role of CYP2C9 genetic polymorphism together with other environmental OA overdose risk factors. Our results support the view that although the CYP2C9*3/CYP2C9*3 genotype is associated soon after the introduction of OA with dramatic overanticoagulation, OA overdose is mostly related to environmental factors.

Early acenocoumarol overanticoagulation among cytochrome P450 2C9 poor metabolizers

Cytochrome P450 2C9 (CYP2C9) is the enzyme that terminates the anticoagulant effect of warfarin. The heterozygous carriers of the two allelic variants CYP2C9*2 and CYP2C9*3 have been associated with impaired warfarin metabolism and a higher risk of haemorrhage. Only three CYP2C9 poor metabolizers (CYP2C9*3/CYP2C9*3) initiating warfarin treatment have so far been identified, all of them with a dramatic overdose occurring a few days after treatment initiation. Acenocoumarol, another coumarinic anticoagulant, has recently been shown to be metabolized by CYP2C9. We report, for the first time, two cases of dramatic overanticoagulation occurring in patients starting acenocoumarol treatment while taking recommended doses (4 mg/day). In both cases, the overdose was discovered at the first INR control with values above 9. Genotyping revealed that the two patients were homozygous for the CYP2C9*3 allele. Our report highlights the need for CYP2C9 genotyping before starting oral anticoagulants in order to prevent early overanticoagulation episodes.

Glutathione-associated enzymes in head and neck squamous cell carcinoma and response to cisplatin-based neoadjuvant chemotherapy

Glutathione S-transferases (GSTs) are metabolic phase II enzymes that promote reactive metabolite elimination by conjugating them to glutathione (GSH). Because of their important role in xenobiotic metabolism and detoxification, they have been implicated in carcinogenesis processes, especially epithelium transformation. Moreover, their influence on response to chemotherapy in cancer patients has been demonstrated. Genetic polymorphisms for GSTM1, GSTT1 and GSTP1 have been found in human populations and have been shown to have phenotypic consequences. To investigate the role of GST enzymes in carcinogenesis and in response to chemotherapy in patients with head and neck squamous cell carcinoma (HNSCC), GSTP1, GSTM1 and GSTT1 were studied prospectively in a large series of HNSCC patients. Correlations between GST alterations, p53 mutation status and clinical response to chemotherapy were investigated. We showed that the risk of developing laryngeal cancer was increased by 2.6-fold [95% CI 1.6--6.1] in patients with the GSTM1 null genotype and by 2.8-fold [95% CI 0.9--8.1] in patients with the homozygous GSTP1 val105 genotype. Furthermore, individuals with this latter genotype were over-represented in the p53 mutation group (p = 0.05). After storage duration and hemolysis adjustment, a significantly lower plasmatic GSTP1 level was observed in complete responders compared with partial and non-responders (mean: 4.4 +/- 0.06 microg/l, 4.7 +/- 0.06 microg/l and 4.7 +/- 0.07 microg/l; p = 0.05), respectively. The prevalence of p53-mutated tumors was significantly higher in the group of non-responders (81%) compared with partial (60%) and complete responders (64%) (p = 0.05). Two types of multivariate analysis were performed including parameters that have been shown to influence response to chemotherapy significantly in univariate analysis. p53 mutations and high tumor stage are independent factors of non-response to chemotherapy, whereas plasmatic GSTP1 levels and low tumor stage are independent factors of complete response. Our data suggest that GST enzymes are associated with larynx cancer and that their use as predictive factors and treatment targets should be further explored.

Genetic polymorphisms of cytochrome P450 2A6 in a case-control study on lung cancer in a French population

Cytochrome P450 2A6 (CYP2A6) is involved in the C-oxidation of nicotine and in the metabolic activation of tobacco nitrosamines. Recent data have suggested that CYP2A6 genetic polymorphisms might play a role in tobacco dependence and consumption as well as in lung cancer risk. However, the previously published studies were based on a genotyping method that overestimated the frequencies of deficient alleles, leading to misclassification for the CYP2A6 genotype. In this study, we genotyped DNA from 244 lung cancer patients and from 250 control subjects for CYP2A6 (wild-type allele CYP2A6*1, and two deficient alleles: CYP2A6*2, and CYP2A6*4, the latter corresponding to a deletion of the gene) using a more specific procedure. In this Caucasian population, we found neither a relation between genetically impaired nicotine metabolism and cigarette consumption, nor any modification of lung cancer risk related to the presence of defective CYP2A6 alleles (odds ratio = 1.1, 95% confidence interval = 0.7-1.9).

Is diclofenac a valuable CYP2C9 probe in humans?

INTRODUCTION

Besides the low therapeutic index drug tolbutamide, there is no validated in vivo probe to assess the genetically determined CYP2C9 activity in humans. The in vitro CYP2C9-specific substrate diclofenac might be a valuable, well-tolerated probe candidate. In order to validate diclofenac as an in vivo CYP2C9 probe, we planned to show that urinary 4'-hydroxydiclofenac/diclofenac metabolic ratio (MR) would correlate to the apparent partial metabolic clearance of diclofenac into 4'-hydroxydiclofenac (Clmet).

PATIENTS AND METHODS

Eighteen healthy volunteers received a single oral dose of 50 mg diclofenac in its enteric-coated form. Blood and urinary pharmacokinetics of diclofenac were studied over 48 h. Identification of the CYP2C9 alleles (CYP2C9*1, CYP2C9*2, and CYP2C9*3) was performed with genomic DNA sequencing.

RESULTS

We observed a dramatic inter-individual variability in the delay of diclofenac intestinal absorption since its first detectable blood concentration ranged from 0.5 h to more than 12 h after drug intake. The Clmet of diclofenac could not be determined in two subjects who started to absorb the drug after 12 h. No correlation could be observed between Clmet of diclofenac and the different MRs calculated at 0-4 h, 0-8 h, 0-12 h, 0-24 h and 0-48 h urinary collections. The Clmet of diclofenac in heterozygous subjects tended to be lower than among wild-type homozygous subjects, but this difference did not reach statistical significance due to an insufficient number of subjects studied.

CONCLUSION

Diclofenac, in its enteric-coated form, is not a useful in vivo CYP2C9 probe probably because of its highly variable intestinal absorption rate. However, since we found a lower metabolic clearance of diclofenac in heterozygous CYP2C9 subjects, as observed with other CYP2C9 substrates, diclofenac, in another galenic form, might be a potential probe to quantify CYP2C9 activity in humans.

Prospective evaluation of detoxification pathways as markers of cutaneous adverse reactions to sulphonamides in AIDS

The use of sulphonamides is complicated by a high rate of cutaneous reactions in AIDS. Metabolic risk factors have been suspected for these reactions. We conducted a prospective study to evaluate whether glutathione S-transferase M1 null genotype, glutathione deficiency and acetylator status as risk factors. To explain the high frequency of slow acetylator phenotype in AIDS patients, we compared N-acetyltransferase-2 phenotype and genotype in this population. AIDS patients treated with sulphonamides for Pneumocystis carinii pneumonia or toxoplasmosis were followed up for cutaneous reactions. Glutathione S-transferase genotyping, glutathione level determination, N-acetyltransferase-2 genotyping and phenotyping were performed. One hundred and thirty-six AIDS patients were studied. Glutathione S-transferase M1 and T1 null genotypes, intracellular glutathione level, slow acetylator genotype and phenotype were not risk factors for cutaneous sulphonamides reactions. The association of glutathione S-transferase M1 null genotype and the slow acetylator one was a risk factor [Fisher's exact test, odds ratio (OR) = 2.6, 95% confidence interval (CI) = 1.2-5.9; P = 0.02]. A discordance between acetylator genotype and phenotype was found in 35% of patients. This frequency was significantly higher than the 6-7% expected (Fisher's exact test: OR = 7.5, 95% CI = 4.2-13.4; P < 0.0001). Suspected metabolic risk factors for sulphonamides cutaneous reactions were not confirmed prospectively. However, the association of glutathione S-transferase M1 null genotype and the slow acetylator one appeared to increase the risk of reactions. We clearly showed that the acetylation phenotype measured by caffeine probe could be modified by the disease.

Structural characterization of a new variant of the CYP2A6 gene (CYP2A6*1B) apparently diagnosed as heterozygotes of CYP2A6*1A and CYP2A6*4C

During the course of investigating the frequency of a CYP2A6 whole deletion-type polymorphism (CYP2A6*4C) in Japanese, an unexpectedly large population of heterozygotes for CYP2A6*4C and the wild-type (CYP2A6*1A) was found. Cloning of a cDNA encoding CYP2A6 from the liver of individuals judged as heterozygotes for CYP2A6*4C and the CYP2A6*1A was carried out to identify the causal allele(s) responsible for a possible overestimation. A clone isolated from the liver cDNA library possessed 58 bp sequences in the 3'-untranslated region, which was replaced with the corresponding region of the CYP2A7 gene. The same gene conversion existed in the genomic DNA, indicating that the replacement was not a cloning artifact. Based on the gene structure of the allele (CYP2A6*1B), this variant was thought to be one of the causal alleles responsible for overestimation of heterozygotes for CYP2A6*4C and CYP2A6* A. To investigate this further, we developed a genotyping method which could distinguish the CYP2A6*A, CYP2A6*1B and CYP2A6*4C alleles from each other. The results clearly showed that CYP2A6*1B was the sole allele responsible for the overestimation. We conclude that the new genotyping method allows determination of six genotypes of the CYP2A6 gene, simultaneously and precisely, in both Oriental and Caucasian populations.

Permissiveness of human biliary epithelial cells to infection by hepatitis C virus

The cellular tropism of hepatitis C virus (HCV) is an important but much debated issue. Permissivity to HCV of biliary cells has never been demonstrated. In this context, we used gallbladder epithelial cells (GBEC) as a model of the more proximal biliary epithelium. These cells were isolated from HCV-positive and -negative individuals and cultured for up to 40 days. Biliary cells from HCV-negative subjects were infected in vitro with various inocula. The retention of GBEC functional characteristics was assessed by the expression of cystic fibrosis transmembrane conductance regulator (CFTR). All 12 GBEC tested from HCV-negative patients were successfully infected by HCV. This was assessed by: 1) the detection of HCV-RNA positive and negative strands; 2) the detection of the viral capsid by immunofluorescence; and 3) the combination of single-strand conformation polymorphism (SSCP) and HVR1 sequence analysis demonstrating the distinct majoritary HCV genomes in serum and in GBEC. The level of HCV RNA in cell extracts and supernatants was low, but HCV infection was highly reproducible. Our results expand those showing the cellular tropism of HCV, and demonstrate the sensitivity of biliary cells to HCV infection. This might have an important impact in terms of pathogenesis and pathological features of HCV infection. In addition, given the easy access to these cells and the high reproducibility of in vitro infection, they should constitute an important tool for studies aimed at analyzing the issue of HCV penetration and neutralizing antibodies.

Influence of human immunodeficiency virus infection on chronic hepatitis B in homosexual men

The aim of this study was to assess the influence of human immunodeficiency virus (HIV) infection on chronic hepatitis B. In a series of 132 (65 anti-HIV positive) homosexual non-drug addicted men with chronic hepatitis B, the liver function was assessed with biochemical tests; the degree of hepatitis B virus (HBV) replication was assessed with serum HBV DNA level and with immunoperoxidase staining of hepatitis B core (HBc) antigen on liver specimens; and the severity of liver lesions was assessed with an histology activity index. Anti-HIV-positive and anti-HIV-negative patients were not different for serum aspartate transaminase activity, bilirubin, prothrombin, and histology activity index. Anti-HIV-positive patients had lower serum alanine transaminase activity levels (P =.0001), lower serum albumin levels (P =.0009), and higher serum HBV DNA levels (P =.01). There was a higher prevalence of cirrhosis in anti-HIV-positive patients (P =.04). In homosexual men with chronic hepatitis B, HIV infection is associated with a higher level of HBV replication and a higher risk for cirrhosis without increased liver necrotico-inflammatory process.

Concurrent emergence of hepatitis B e antigen-negative hepatitis B virus variant and autoimmune hepatitis cured by adenine arabinoside monophosphate

We report the case of a hepatitis B virus chronic carrier in whom features of severe autoimmune hepatitis developed concurrently with the emergence of a hepatitis Be antigen-negative variant. Corticosteroid administration failed to normalize serum transaminase activity and resulted in increased viral multiplication. Adenine arabinoside monophosphate treatment allowed simultaneous inhibition of hepatitis B virus multiplication and remission of autoimmune features. This observation indicates that hepatitis Be antigen-negative variants can induce autoimmune hepatitis and adds support to the hypothesis that autoimmune hepatitis can be triggered by hepatotropic viruses. Patients with both features should first be treated with adenine arabinoside monophosphate. This observation indicates that hepatitis Be antigen-negative variants can induce autoimmune hepatitis and adds support to the hypothesis that autoimmune hepatitis can be triggered by hepatotropic viruses. Patients with both features should first be treated with adenine arabinoside monophosphate.

Hepatitis C virus persistence in human hematopoietic cells injected into SCID mice

The issue of infection of peripheral blood mononuclear cells (PBMC) by the hepatitis C virus (HCV) has potentially important implications, but is still debated. We have used the severe combined immunodeficiency (SCID) mouse model to test for the persistence of HCV in PBMC. Hematopoietic cells isolated from 14 subjects infected by HCV were inoculated intraperitoneally into SCID mice. Serum and blood cell samples from these mice were obtained with a mean follow-up of 8 weeks. As controls, human fibroblasts and sheep PBMC, preincubated with a human HCV-positive serum, were inoculated concomitantly into mice and analyzed. HCV-RNA positive strands were detected in 7 of 26 serum samples and 8 of 26 cell fractions from SCID mice inoculated with HCV-positive PBMC, after 8 weeks of follow-up. In contrast, no HCV RNA was detectable in the 10 control mice. HCV-RNA negative strands were detected in only 2 of 10 tested samples from 2 mice, and both positive mice had been inoculated with PBMC from HCV-positive subjects with malignant hematopoietic syndrome. Our study offers strong evidence for the persistence of HCV infection in mononuclear cells. Our results are also consistent with a low rate of HCV multiplication. This SCID mouse model might therefore be useful in analyzing the mechanisms of HCV persistence in mononuclear cells.

[Characterization of liver regeneration in the albumin-urokinase transgenic mouse]

Models of liver regeneration are essential to understand mechanisms of hepatic carcinogenesis, correct genetic diseases by gene transfer or hepatocyte transplantation. The expression in the liver of transgenic mice of a gene coding for a urokinase-type plasminogen activator (uPA mouse) induces hepatotoxicity and prolonged post-native liver regeneration from cellular clones which have inactivated the transgene. This model may have major applications but it remains necessary to characterize the liver regeneration pattern.

METHODS

Histological and immunohistochemical studies of the liver of uPA and non-transgenic mice, 3, 7, 14, 21, 28, 42 and 56 days-old. Markers of cellular proliferation: 5-bromo-2'deoxyuridine (BrdU) and proliferating cell nuclear antigen (PCNA).

RESULTS

Regenerative nodules were seen from day 14. These nodules then grew, became confluent and by 8 weeks constituted the entire liver mass. A semi-quantitative study of BrdU and PCNA showed a maximal labeling at day 7 (300 to 350 labeled cells/10 microscopic fields, mag 400). When the nodules appeared, 60 to 80% of the cells were labeled. The proportion of labeled cells decreased but was still greater than that observed in non transgenic mice up to day 56 (92 to 106 labeled cells vs 10 to 28, on day 28).

CONCLUSIONS

In uPA mouse liver regeneration is significantly expanded, as compared to the regeneration following partial hepatectom. This study therefore has allowed to determine the best conditions for using this model.

Persistence of hepatitis B virus DNA in serum and liver from patients with chronic hepatitis B after loss of HBsAg

BACKGROUND/AIMS

The persistence of serum and liver hepatitis B virus (HBV) sequences in patients with chronic hepatitis B after loss of HBsAg has already been described. We have attempted to elucidate the significance of these HBV sequences after loss of HBsAg.

METHODS

Fifteen patients were studied. We looked for serum and liver HBV DNA, using polymerase chain reaction (PCR) with different sets of primers and in situ hybridization. The sedimentation velocity of serum HBV DNA was measured on a gradient of sucrose in two patients.

RESULTS

Serum HBV DNA was detected by PCR in four of the 14 patients tested at 0 months after loss of HBsAg, two patients remained HBV DNA positive until 12 months, and none was positive at 24 months. The sedimentation velocity of serum HBV DNA in sucrose was relatively similar to that of a chronic HBV carrier with active viral replication. Liver HBV DNA was demonstrated by PCR in all 15 patients and by in situ hybridization in six patients.

CONCLUSIONS

Our results show that: 1) HBV DNA may persist in the serum in a minority of patients and may be associated with circulating viral particles; 2) HBV DNA persists in the liver in all patients and its extrachromosomal localization was shown by in situ hybridization technique in some cases. These results suggest the persistence of low-level HBV replication after loss of HBsAg.

Prolonged interferon-alpha therapy of hepatitis B virus-related decompensated cirrhosis

Interferon alpha therapy of hepatitis B virus-related decompensated cirrhosis with the dose and the duration generally used is frequently associated with severe side-effects and reactivations. Between 1989 and 1996, 15 patients with hepatitis B virus-related decompensated cirrhosis received prolonged (3-48 months) low-dose (3 million units) IFN-alpha therapy. Ten patients (66%) had a sustained loss of serum hepatitis B virus DNA and hepatitis Be antigen (if present initially) associated with a decrease of aminotransferase levels into the normal range. During follow-up of these 10 patients, seven had a marked clinical improvement and are alive and fully active. One has an hepatocellular carcinoma, and two died without reactivation. Among the five other patients, two had a transient loss of serum HBV DNA followed by reactivation and three did not respond to therapy. During follow-up, one of these five patients died and one underwent liver transplantation. Severe complications, possibly related to interferon were uncommon and included bacterial infection in one case and variceal bleeding in two cases. Eleven of the 15 patients treated are alive after 1.5-7 years of follow-up. Hence, in patients with hepatitis B-related cirrhosis, prolonged low-dose IFN-alpha therapy is relatively well tolerated and may induce a sustained inhibition of hepatitis B virus replication with marked clinical improvement.

Hepatitis B virus precore mutations and HBeAg negative reactivation of chronic hepatitis B after interferon therapy

The objective of this study was to look for HBV precore mutations in three patients with chronic active hepatitis B who developed HBV-DNA-positive/HBeAg-negative reactivation after HBe seroconversion induced by interferon therapy. Direct sequencing of polymerase chain reaction products was performed on serum collected before and after HBe seroconversion. In two patients precore sequence showed only wild-type HBV before and after interferon therapy. In one patient, precore sequence showed only wild-type HBV before interferon therapy and a mixed infection by wild-type HBV and precore mutant viruses (1858 and 1896 nucleotide mutations) after treatment. The presence of HBeAg/anti-HBe immune complexes was found after HBe seroconversion in all cases. Our results suggest that: 1) precore mutations are not always found in patients with chronic hepatitis B who develop HBV DNA-positive/HBeAg-negative reactivation; and 2) HBeAg negativity, despite the presence of wild-type HBV, might be due to HBeAg/anti-HBe immune complexes. We speculate that the production of these immune complexes may be favored by interferon therapy.

Adenine arabinoside 5'-monophosphate in patients with chronic hepatitis B: comparison of the efficacy in patients with high and low viral replication

This study compared the response to adenine arabinoside 5'-monophosphate (ARA AMP) in 60 patients with chronic hepatitis B according to the pretreatment serum hepatitis B virus DNA concentration. The level of hepatitis B virus replication was defined as low (30 patients) or high (30 patients) when serum hepatitis B virus DNA concentration was below or above 100 pg/ml, respectively. Patients received a 28 day course of ARA AMP and a second course of ARA AMP was given six months later to patients with persistent hepatitis B virus replication. At the end of the first course of ARA AMP, 11 of the patients (37%) with low replication and one of the patients (3%) with high replication became negative for hepatitis B virus DNA (p = 0.0012); five of the patients (17%) with low replication and none of the patients with high replication had HBe seroconversion (p = 0.06). Two of these five patients lost HBsAg. Kinetics of serum hepatitis B virus DNA during treatment showed a considerable but transient antiviral effect of ARA AMP. Three of 32 retreated patients became negative for hepatitis B virus DNA and one patient had HBe seroconversion. In conclusion, ARA AMP exerts a considerable but transient antiviral effect on hepatitis B virus. Complete and sustained inhibition of hepatitis B virus replication was only obtained in the patients with low hepatitis B virus replication.

Low frequency of precore hepatitis B virus mutants in anti-hepatitis B e-positive reactivation after loss of hepatitis B e antigen in patients with chronic hepatitis B

The objective of this study was to evaluate the role of hepatitis B virus (HBV) precore mutations in patients with anti-HBe-positive chronic hepatitis B with or without previous known HBe antigen (HBeAg) viremic phase, and to assess the potential implication of precore mutants in HBeAg-negative reactivation after loss of HBeAg. Nineteen patients were studied: 7 had a previous HBeAg-positive phase and had spontaneous or therapeutically induced loss of HBeAg (group A); 12 had no previous HBeAg-positive phase (group B). Direct sequencing of PCR products was performed on serum collected during the anti-HBe-positive phase in the two groups. In group A, precore sequencing showed that 5 patients were infected by wild-type virus, 1 patient was infected with a precore mutant, and 1 patient was found to be infected by a mixture of wild-type and precore mutant viruses. In group B, precore sequencing showed that only 1 patient was infected with wild-type virus and that 11 were infected with precore mutants. In a few patients, the presence of HBeAg within immune complexes may explain HBeAg negativity. In conclusion, our results show that, in patients with anti-HBe-positive chronic hepatitis B: (1) precore mutations creating a stop codon are more frequently found in those without known previous HBeAg positivity; (2) after loss of HBeAg, the patients who have anti-HBe-positive reactivation are infected by wild-type virus, which suggests that reactivation is not related to precore mutations; (3) HBeAg negativity may be caused by immune complexes formation.

Pretransplantation interferon treatment and recurrence of hepatitis B virus infection after liver transplantation for hepatitis B-related end-stage liver disease

Orthotopic liver transplantation in patients with hepatitis B-related cirrhosis is commonly complicated by reinfection with the hepatitis B virus, with rapidly progressive liver disease and poor survival rate. We assessed the efficacy of prior therapy with recombinant interferon-alpha on the prevention of posttransplantation hepatitis B virus reinfection. Twenty-two patients with hepatitis B-related cirrhosis waiting for liver transplantation received 3 MU (decreased to 1.5 MU in cases of intolerance) of recombinant interferon-alpha until transplantation. The rates of posttransplantation hepatitis B virus reinfection and survival in this group were compared with those in a group of 26 patients previously given transplants for the same disease but not given interferon therapy. The same protocol of HBs antibody passive immunoprophylaxis was applied after transplantation in both groups. Recombinant interferon-alpha was administered for 14 +/- 7 wk. The treatment had an antiviral effect, with disappearance of serum hepatitis B virus DNA in seven of the eight patients initially positive for hepatitis B virus DNA and disappearance of HBeAg in two of the three patients initially positive for HBeAg. Serum hepatitis B virus DNA remained detectable with polymerase chain reaction at transplantation in 56% of the interferon-treated patients. After transplantation, hepatitis B virus reinfection was more frequent in polymerase chain reaction-positive than in polymerase chain reaction-negative patients (78% vs. 17%, p < 0.05). One patient's condition deteriorated during interferon treatment; this patient was not given a transplant. Two patients (in whom hepatitis B virus DNA disappeared from serum) improved so markedly during treatment that they were not given transplants.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of serum HBV-DNA by polymerase chain reaction (PCR) in patients before reactivation of chronic hepatitis B

Reactivation of chronic hepatitis B is characterized by the reappearance of HBV-DNA in serum. The purpose of the study was to determine whether, before reactivation, HBV-DNA would be detectable in serum, using a sensitive procedure of detection, namely polymerase chain reaction (PCR). We studied 17 patients with chronic hepatitis B who experienced an episode of reactivation, defined by the reappearance of HBV-DNA in serum. None of these 17 sera had HBV-DNA demonstrable by dot-blot hybridization nor liquid hybridization in sera collected before reactivation. Using PCR, HBV-DNA was detected, before reactivation, in 13 of the 17 episodes of reactivation tested with Southern-blot and hybridization. HBV-DNA was not detectable with PCR in the serum of four patients who subsequently experienced an episode of reactivation. In conclusion, our results show low level HBV replication before reactivation in most, but not all, HBs-positive, HBV-DNA-negative patients. This suggests that reactivation may occur even in patients with no HBV-DNA demonstrable in serum with PCR prior to reactivation.

Demonstration of hepatitis B virus DNA by polymerase chain reaction in the serum and the liver after spontaneous or therapeutically induced HBeAg to anti-HBe or HBsAg to anti-HBs seroconversion in patients with chronic hepatitis B

The objective was to determine the proportion of patients with chronic hepatitis B in whom hepatitis B virus DNA is demonstrated by polymerase chain reaction after HBeAg to anti-HBe or HBsAg to anti-HBs spontaneous or therapeutically induced seroconversion. Polymerase chain reaction was performed on serum 6 and 12 mo after HBeAg to anti-HBe seroconversion in 12 patients and 2, 6 and 12 mo after HBsAg to anti-HBs seroconversion in 13 patients. Polymerase chain reaction was performed on liver tissue after HBeAg to anti-HBe seroconversion in five patients and after HBsAg to anti-HBs seroconversion in one patient. Serum HBV DNA was demonstrated by polymerase chain reaction in 83% of patients 6 or 12 mo after HBeAg to anti-HBe seroconversion and in 58%, 31% and 15% of patients at 2, 6 and 12 mo, respectively, after HBsAg to anti-HBs seroconversion. Liver HBV DNA was demonstrated by polymerase chain reaction in all patients tested. Our results show that (a) a reduced level of hepatitis B virus replication persists in most of the patients after HBeAg to anti-HBe seroconversion and might be predictive of reactivation, and (b) in contrast, hepatitis B virus replication progressively disappears in most of the patients after HBsAg to anti-HBs seroconversion.

Anti-pre-S responses and viral clearance in chronic hepatitis B virus infection

Serial sera were collected prospectively during the clinical course of 13 HBsAg carriers with chronic liver disease and analyzed for ALT levels, pre-S1 and pre-S2 antigens and corresponding antibodies and other serological hepatitis B virus markers. In five patients, anti-pre-S1 and anti-pre-S2 antibodies became detectable in multiple serum samples, whereas in eight patients anti-pre-S was never detected or only appeared transiently during the follow-up. The first pattern was associated with normalization of ALT levels and undetectable pre-S antigens and viral DNA by the polymerase chain reaction assay at final follow-up. HBsAg clearance occurred in two of the five patients. The second pattern was one of persistence of HBsAg and pre-S antigens, associated with the presence of serum HBV DNA detectable by spot hybridization or polymerase chain reaction regardless of clinical outcome. These findings demonstrate the occurrence of anti-pre-S antibodies in chronic hepatitis B virus-induced liver disease and associate anti-pre-S appearance with the clearance of hepatitis B virus from serum.

Redevelopment of hepatitis B surface antigen after renal transplantation

A patient with chronic hepatitis B virus (HBV) and chronic renal failure received a renal transplantation. Hepatitis B surface antigen (HBsAg) disappeared, and antibodies to HBsAg appeared 10 months before transplantation. Liver tests showed no abnormality at transplantation. Six months later, chronic hepatitis reactivated, antibodies to HBsAg disappeared, and HBsAg reappeared. Hepatitis B virus DNA was demonstrated with polymerase chain reaction in the serum collected before transplantation. This observation suggests that low level HBV replication was present before transplantation despite the absence of detectable HBsAg and was reactivated under immunosuppressive therapy after transplantation.

Is the response to recombinant alpha interferon related to the presence of antibodies to hepatitis C virus in patients with chronic non-A, non-B hepatitis?

The purpose of this study was to determine whether the response of serum alanine aminotransferase (ALT) to recombinant alpha-interferon was related to the presence or absence of antibodies to hepatitis C virus (anti-HCV) in patients with chronic non-A,non-B hepatitis. A group of 65 patients with chronic non-A, non-B hepatitis was studied. The source of contamination was blood transfusion or administration of blood products in 32, intravenous drug addiction in 14 and unknown in 19. The patients received 1, 3 or 5 MU of recombinant alpha-interferon, three times a week, for 6 months. A complete response was defined as normal ALT by the end of recombinant alpha-interferon treatment. Sera collected before treatment were tested for anti-HCV with an enzyme immunoassay. The overall percentage of anti-HCV positive patients in the study group was 75%. There was no difference between the anti-HCV positive and the anti-HCV negative patients before the treatment with respect to age, sex ratio, source of contamination, serum albumin, prothrombin, bilirubin, ALT or prevalence of cirrhosis. In the anti-HCV positive and the anti-HCV negative groups, there was no difference in the proportion of patients receiving the 1, 3 or 5 MU dosage. The percentage of patients with complete response was not different in anti-HCV positive patients (48%) and in anti-HCV negative patients (50%). There was also no difference in the kinetics of the decrease of mean serum ALT levels between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant human gamma-interferon in patients with chronic active hepatitis B: pharmacokinetics, tolerance and biological effects

Pharmacokinetics, tolerance and biological effects of human recombinant gamma-interferon were studied in 12 patients with chronic active hepatitis B. Serum concentrations of gamma-interferon were measured by radioimmunoassay in four patients after a subcutaneous injection of 10 million U (0.5 mg); the peak serum concentration of gamma-interferon (29 +/- 7 U/ml) was reached after 5 to 8 hr and gamma-interferon remained detectable for 24 to 36 hr. Twelve patients received recombinant gamma-interferon, 2.5 to 10 million U daily, for 4 mo. All suffered from a dose-dependent, flulike syndrome similar to that induced by alpha-interferon. Recombinant gamma-interferon induced a marked increase of serum ALT and a significant decrease of serum hepatitis B virus-DNA. Serum hepatitis B virus-DNA disappeared in one patient during administration of recombinant gamma-interferon. Serum hepatitis B virus-DNA disappeared in four additional patients, and HBeAg disappeared in two patients during the 12 mo after administration of recombinant gamma-interferon. These results indicate that subcutaneous injection is suitable for administration of recombinant gamma-interferon and that recombinant gamma-interferon has an antiviral effect in patients with chronic active hepatitis B.