Longitudinal evaluation of hepatitis C viral persistence in HIV-infected patients with spontaneous hepatitis C clearance

Hepatitis C virus (HCV) viral persistence in patients with spontaneous viral clearance is controversial. Several studies have shown HCV-RNA in peripheral blood mononuclear cells (PBMCs) and/or liver tissue among patients who have cleared the virus spontaneously, suggesting that viral persistence is a common situation that could involve the entire population studied. Thus, our aim was to evaluate HCV-RNA persistence in PBMCs and hepatocytes in subjects infected with the human immunodeficiency virus (HIV). A total of 1508 patients were prospectively followed and tested for anti-HCV antibodies and HCV-RNA to identify the patients who achieved spontaneous viral clearance. In all of the patients, the persistence of HCV-RNA in PBMCs was evaluated longitudinally during 2 years of follow-up. Fifty-nine patients fulfilled the inclusion/exclusion criteria and were included in the study. HCV-RNA was not detected in the PBMCs at baseline [59 PBMCs samples tested; 0 %; 95 % confidence interval (CI): 0-3.3 %] or during the follow-up (147 PBMCs samples tested; 0 %; 95 % CI: 0-2.02 %). Our study shows that HCV viral persistence is not a frequent occurrence in HIV-infected patients who have spontaneously resolved an HCV infection. Thus, the lack of serum HCV-RNA should continue to be addressed as the standard of healing.

Maraviroc, a CCR5 antagonist, ameliorates the development of hepatic steatosis in a mouse model of non-alcoholic fatty liver disease (NAFLD)

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the general population. The NAFLD spectrum ranges from simple steatosis to cirrhosis. The chemokine CCL5/RANTES plays an important role in the progression of hepatic inflammation and fibrosis. The objective of this study was to examine the effects of maraviroc, a CCR5 antagonist, on liver pathology in a NAFLD mouse model.

METHODS

A total of 32 male C57BL/6 mice were randomly assigned to one of four groups: (i) control group (chow diet plus tap water); (ii) maraviroc group (chow diet plus maraviroc in drinking water); (iii) high-fat diet (HFD) group (HFD plus tap water); and (iv) maraviroc/HFD group (HFD plus maraviroc). All mice were sacrificed 16 weeks after the beginning of the experiment. Biochemical analyses and liver examinations were performed.

RESULTS

Mice in the HFD group showed a tendency towards increased body mass gain and liver damage compared with the maraviroc/HFD group. Moreover, liver weight in the HFD group was significantly higher than in the maraviroc/HFD group. Hepatic triglyceride concentration in the maraviroc/HFD group was significantly lower than in the HFD group. Interestingly, the maraviroc/HFD group exhibited a lower degree of steatosis. Furthermore, hepatic CCL5/RANTES expression was significantly lower in the maraviroc/HFD group than in the HFD group. Overall, no differences were observed between the control group and the maraviroc group.

CONCLUSIONS

Maraviroc ameliorates hepatic steatosis in an experimental model of NAFLD.

Polyene Macrolide Antibiotic Biosynthesis

Polyenes constitute a large class of natural metabolites produced by giant multifunctional enzymes in a process resembling fatty acid biosynthesis. Like fatty acids, polyene macrolides and other polyketides are assembled by decarboxylative condensations of simple carboxylic acids. But while fatty acid intermediates are fully reduced, polyene macrolide intermediates suffer the suppression of reduction or dehydration reactions at given biosynthetic steps. In the last years, much progress has been made in our understanding of the linear and modular organization of the gene clusters, and the enzymes encoded by them, responsible for the biosynthesis of these macrocyclic metabolites. This know-how about the rules that govern polyene chain growth has provided the basis for the first rational manipulations of these fascinating systems for the production of engineered derivatives and promises a new era of novel polyene development, which will hopefully yield new molecules with improved pharmacological properties.

Characterization of the ask?asd operon in aminoethoxyvinylglycine-producing Streptomyce s sp. NRRL 5331

The first two genes of the threonine pathway, ask and asd, were cloned and sequenced from the aminoethoxyvinylglycine-producing Streptomyces sp. NRRL 5331. The two genes are organized in a bicistronic operon. ask, encoding the apartokinase (ASK), is located upstream from asd. The presence of a ribosome-binding site within the ask sequence suggests that this open reading frame encodes two overlapping proteins. The formation of both subunits of the aspartokinase from a single gene was studied using antibodies raised against the C-terminal end of the aspartokinase subunits. Disruption of asd results in a significant decrease of aminoethoxyvinylglycine production, thus supporting the involvement of the ask-asd operon in the biosynthesis of this metabolite. This is the first report in which a gene cluster for the first two steps of aminoethoxyvinylglycine biosynthesis is characterized.

Engineered biosynthesis of novel polyenes: a pimaricin derivative produced by targeted gene disruption in Streptomyces natalensis

BACKGROUND

The post-polyketide synthase biosynthetic tailoring of polyene macrolides usually involves oxidations catalysed by cytochrome P450 monooxygenases (P450s). Although members from this class of enzymes are common in macrolide biosynthetic gene clusters, their specificities vary considerably toward the substrates utilised and the positions of the hydroxyl functions introduced. In addition, some of them may yield epoxide groups. Therefore, the identification of novel macrolide monooxygenases with activities toward alternative substrates, particularly epoxidases, is a fundamental aspect of the growing field of combinatorial biosynthesis. The specific alteration of these activities should constitute a further source of novel analogues. We investigated this possibility by directed inactivation of one of the P450s belonging to the biosynthetic gene cluster of an archetype polyene, pimaricin.

RESULTS

A recombinant mutant of the pimaricin-producing actinomycete Streptomyces natalensis produced a novel pimaricin derivative, 4,5-deepoxypimaricin, as a major product. This biologically active product resulted from the phage-mediated targeted disruption of the gene pimD, which encodes the cytochrome P450 epoxidase that converts deepoxypimaricin into pimaricin. The 4,5-deepoxypimaricin has been identified by mass spectrometry and nuclear magnetic resonance following high-performance liquid chromatography purification.

CONCLUSIONS

We have demonstrated that PimD is the epoxidase responsible for the conversion of 4,5-deepoxypimaricin to pimaricin in S. natalensis. The metabolite accumulated by the recombinant mutant, in which the epoxidase has been knocked out, constitutes the first designer polyene obtained by targeted manipulation of a polyene biosynthetic gene cluster. This novel epoxidase could prove to be valuable for the introduction of epoxy substituents into designer macrolides.