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Biomedical subjects

Pascal Clayette

Publications and source records attributed to Pascal Clayette.

At least 19 recordsLinked to original sources
PubMed2007

Comparative effects of two type I interferons, human IFN-alpha and ovine IFN-tau on indoleamine-2,3-dioxygenase in primary cultures of human macrophages.

Type I interferons (IFNs) are widely used to treat viral diseases. Depressive symptoms and suicide attempts are common neuropsychiatric side-effects during treatment with type I IFNs. Activation of indoleamine-2,3-dioxygenase (IDO), the first and rate-limiting enzyme of the kynurenine pathway by IFNs, leads to an increase in tryptophan (Trp) catabolism. Low levels of Trp lead to decrease of serotonin synthesis, which is likely to be related to the depressive symptoms. Ovine type I interferon-tau (IFN-tau) has a more potent antiretroviral effect and is less toxic than human type I IFN-alpha. Effects of IFN-tau and IFN-alpha on IDO expression and activity in primary cultures of human macrophages were compared in parallel to those of IFN-gamma, considered as one of the most potent IDO inducer. We found that both IFN-alpha and IFN-tau were poor inducers of IDO compared with IFN-gamma. However, IDO activation was slightly and significantly lower with ovine IFN-tau than human IFN-alpha, suggesting that ovine IFN-tau might have a lower impact on serotoninergic pathway compared with human IFN-alpha.

Animals↗
PubMed2006

Structure-activity relationships in platelet-activating factor. Part 14: synthesis and biological evaluation of piperazine derivatives with dual anti-PAF and anti-HIV-1 activity.

As HIV-associated dementia prevalence has risen with the lifespan of HIV-infected individuals, there is an important need for antiretroviral and anti-inflammatory drugs targeting the central nervous system. Platelet-activating factor, a mediator of inflammation, is an HIV-induced neurotoxin secreted in the infected brain. In this work, we developed piperazine derivatives bearing a heterocyclic moiety as PAF-antagonists and HIV-1 replication inhibitors with micromolar potency.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Synthesis and anti-HIV properties of new hydroxyquinoline-polyamine conjugates on cells infected by HIV-1 LAV and HIV-1 BaL viral strains.

To find new derivatives that block different virus strains entry in cells bearing specific surface receptors represent an interesting challenge for medicinal chemists. Here, we report the synthesis and the anti-HIV properties of a new series of analogues based on the introduction of quinoline moiety on various polyamine backbones, including polyazamacrocycles. Three compounds 7, 8, and 10 of this series were found active on PBMCs cells infected by HIV-1 LAV or by HIV-1 BaL, in contrast the well-known reference compound 1a (AMD 3100) was found only active on HIV-1 LAV strain.

Anti-HIV Agents↗
PubMed2006

Structure-activity relationships in platelet-activating factor. Part 13: synthesis and biological evaluation of piperazine derivatives with dual anti-PAF and anti-HIV-1 or pure antiretroviral activity.

HIV-1 infection of the brain and PAF neurotoxicity are implicated in AIDS dementia complex. We previously reported that a trisubstituted piperazine derivative is able to diminish both HIV-1 replication in monocyte-derived macrophages and PAF-induced platelet aggregation. We report in this work new compounds obtained by modifying its piperazine substituents. The structure-activity relationship study shows that a better dual activity or even pure antiretroviral compounds can be obtained in this series.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Squalenoyl nanomedicines as potential therapeutics.

Nucleoside analogues display significant anticancer or antiviral activity by interfering with DNA synthesis. However, there are some serious restrictions to their use, including their rapid metabolism and the induction of resistance. We have discovered that the linkage of nucleoside analogues to squalene leads to amphiphilic molecules that self-organize in water as nanoassemblies of 100-300 nm, irrespective of the nucleoside analogue used. The squalenoyl gemcitabine exhibited superior anticancer activity in vitro in human cancer cells and gemcitabine-resistant murine leukemia cells, and in vivo in experimental leukemia both after intravenous and oral administration. The squalenoylation of other antiretroviral nucleosides also led to more potent drugs when tested in primary cultures of HIV-infected lymphocytes. Thus, the squalenoylation is an original technology platform for generating more potent anticancer and antiviral nanomedicines.

Administration, Oral↗
PubMed2005

Involvement of IL-6 in the anti-human immunodeficiency virus activity of IFN-tau in human macrophages.

IFN-tau is a non-cytotoxic type I IFN responsible for maternal recognition of the foetus in ruminants. IFN-tau has been found to inhibit HIV replication more strongly than human IFN-alpha, particularly in human monocyte-derived macrophages, without associated toxicity. Ovine IFN-tau uses the same anti-viral cellular pathways as human IFN-alpha in human macrophages, principally inhibiting the early steps of the biological cycle of HIV, preventing the integration of HIV DNA into the host-cell genome. In this study, we investigated the immunomodulatory properties of IFN-tau in human macrophages. We found that IFN-tau increased the production of IL-10 and IL-6, but not of IL-1beta or tumour necrosis factor alpha, in unstimulated, LPS-stimulated and HIV-1/Ba-L-infected macrophages. We also found that treatment with IL-6 inhibited HIV replication. Moreover, the neutralization of IL-6 activity in the cell culture supernatants of IFN-tau-treated macrophages led to a decrease in the anti-retroviral effects of IFN-tau, suggesting that IL-6 was involved in the anti-viral activity induced by IFN-tau. By focusing on the very early steps of the biological cycle of HIV, we showed that IL-6 co-operated with IFN-tau to decrease intracellular HIV RNA levels 2 h after infection.

Animals↗
PubMed2005

Mechanisms involved in the low-level regeneration of CD4+ cells in HIV-1-infected patients receiving highly active antiretroviral therapy who have prolonged undetectable plasma viral loads.

BACKGROUND: Persistent low CD4(+) cell counts are observed in 5%-27% of patients treated for human immunodeficiency virus (HIV)-1 infection despite their having prolonged undetectable plasma viral loads. METHODS: To understand the possible mechanisms of this discordant immunological situation, a prospective transsectional case-control study was designed. HIV-1-infected subjects who had a plasma viral load <200 copies/mL for >1 year were considered to be case patients if their CD4(+) cell count was <250/mm(3); control patients had CD4(+) cell counts >500/mm(3) and were matched by sex, age, and nadir CD4(+) cell count to case patients. T cell proliferation after stimulation with various antigens, T cell subset counts, T cell rearrangement excision circles (TRECs), T cells undergoing apoptosis, cytokines influencing apoptosis, and cellular proviral DNA and plasma viral RNA persistence were assessed. RESULTS: Compared with the 19 control patients, the 19 case patients had undistinguishable lymphoproliferative responses to candidin and cytomegalovirus, fewer naive CD4(+) cells (CD45RA(+)62L(+), 23%+/-13% vs. 47%+/-14%; P<.0001), lower thymic output (1.28 vs. 3.95 TRECs/microL of blood; P=.0015), increased cell death by apoptosis (spontaneous, 23.2%+/-8.3% vs. 11.9%+/-8.4% [P=.02]; Fas induced, 38.6%+/-13.7% vs. 16.4%+/-8.0% [P=.004]), higher levels of plasma soluble tumor necrosis factor receptor II (9.6 vs. 5.3 ng/mL; P=.0058), and undistinguishable plasma HIV-1 and cellular proviral DNA loads. CONCLUSIONS: The mechanisms responsible for the low-level regeneration of CD4(+) cells involve, at least, deficiency in the regeneration of central CD4(+) cells and excessive apoptosis.

Adult↗
PubMed2005

Lack of IFN-gamma production in response to antigenic stimulation in human IFN-tau-treated lymphocytes.

Interferon-tau (IFN-tau) is a type I IFN responsible for maternal recognition of the fetus in ruminants. In addition to its physiologic role, IFN-tau also inhibits HIV replication in human lymphocytes and macrophages and displays immunomodulatory effects but lacks the toxicity associated with other type I IFNs. Human IFN-alpha promotes a Th1 response, whereas IFN-tau has anti-inflammatory properties, inducing the production of Th2 cytokines in murine models of experimental autoimmune encephalitis (EAE) or fetal loss. We compared the effects of ovine IFN-tau (OvIFN-tau) and human IFN-alpha (HuIFN-alpha) on cytokine mRNA and protein production in human peripheral blood mononuclear cells (PBMCs) activated with a recall antigen, such as purified protein derivative (PPD) of tuberculin or with a proinflammatory stimulus, such as lipopolysaccharide (LPS). In both cases, IFN-alpha increased IFN-gamma production, whereas IFN-tau did not and thereby promoted Th2 cytokine production. This original property renders IFN-tau a potential candidate for therapeutic applications in immune disorders, such as multiple sclerosis (MS), but its therapeutic use in the treatment of HIV infection should be considered with caution.

Cell Proliferation↗
PubMed2004

Structure-activity relationships in platelet-activating factor. 12. Synthesis and biological evaluation of platelet-activating factor antagonists with anti-HIV-1 activity.

The HIV-1 central nervous system infection leads to the onset of neurological impairments called AIDS dementia complex (ADC). PAF plays an important role in this pathology, as it is an HIV-1-induced neurotoxin produced by infected or activated macrophages and microglia, in the brain. We previously reported that PAF-antagonists bearing a trisubstituted piperazine presented in vitro anti-HIV-1 activity in human macrophages. To improve the pharmacological activities of our lead compound, 1a, we modified its carbamate function and evaluated both its antiretroviral and anti-PAF activities. One carbamate derivative (10c) demonstrated a similar antiviral activity but a higher anti-PAF potency, whereas 4a, with an ureide function, presents an increased antiviral activity and can be considered as a pure antiretroviral drug, as it does not present PAF-antagonism. Moreover, we measured the ability of 1a to cross the blood-brain barrier, using the in situ mouse brain perfusion method and its plasmatic concentrations after iv and po administration. The transport parameter measured (K(in)) proves that 1a is able to cross this biological barrier, but a pharmacokinetic study reveals its weak bioavailability in rats.

Animals↗
PubMed2004

Hydrolysis of the amyloid prion protein and nonpathogenic meat and bone meal by anaerobic thermophilic prokaryotes and streptomyces subspecies.

Transmissible spongiform encephalopathies are caused by accumulation of highly resistant misfolded amyloid prion protein PrPres and can be initiated by penetration of such pathogen molecules from infected tissue to intact organism. Decontamination of animal meal containing amyloid prion protein is proposed thanks to the use of proteolytic enzymes secreted by thermophilic bacteria Thermoanaerobacter, Thermosipho, and Thermococcus subsp. and mesophilic soil bacteria Streptomyces subsp. Keratins alpha and beta, which resemble amyloid structures, were used as the substrates for the screening for microorganisms able to grow on keratins and producing efficient proteases specific for hydrolysis of beta-sheeted proteic structures, hence amyloids. Secretion of keratin-degrading proteases was evidenced by a zymogram method. Enzymes from thermophilic strains VC13, VC15, and S290 and Streptomyces subsp. S6 were strongly active against amyloid recombinant ovine prion protein and animal meal proteins. The studied proteases displayed broad primary specificities hydrolyzing low molecular mass peptide model substrates. Strong amyloidolytic activity of detected proteases was confirmed by experiments of hydrolysis of PrPres in SAFs produced from brain homogenates of mice infected with the 6PB1 BSE strain. The proteases from Thermoanaerobacter subsp. S290 and Streptomyces subsp. S6 are the best candidates for neutralization/elimination of amyloids in meat and bone meal and other protein-containing substances and materials.

Amyloid↗
PubMed2004

Aluminum hydroxide adjuvant induces macrophage differentiation towards a specialized antigen-presenting cell type.

Aluminum hydroxide (AlOOH) has been used for many years as a vaccine adjuvant, but little is known about its mechanism of action. We investigated in this study the in vitro effect of aluminum hydroxide adjuvant on isolated macrophages. We showed that AlOOH-stimulated macrophages contain large and persistent intracellular crystalline inclusions, a characteristic property of muscle infiltrated macrophages described in animal models of vaccine injection, as well as in the recently described macrophagic myofasciitis (MMF) histological reaction in humans. AlOOH-loaded macrophages exhibited phenotypical and functional modifications, as they expressed the classical markers of myeloid dendritic cells (HLA-DR(high)/CD86(high)/CD83(+)/CD1a(-)/CD14(-)) and displayed potent ability to induce MHC-II-restricted antigen specific memory responses, but kept a macrophage morphology. This suggests a key role of macrophages, in the reaction to AlOOH-adjuvanted vaccines and these mature antigen-presenting macrophages may therefore be of particular importance in the establishment of memory responses and in vaccination mechanisms leading to long-lasting protection.

Adjuvants, Immunologic↗
PubMed2004

Synthesis and biological evaluation in human monocyte-derived macrophages of N-(N-acetyl-L-cysteinyl)-S-acetylcysteamine analogues with potent antioxidant and anti-HIV activities.

We synthesized a series of N-(N-acetyl-L-cysteinyl)-S-acetylcysteamine (10) analogues bearing various acyl groups on thiol cysteine or cysteamine residues, to investigate the structure-activity relationship for pro-GSH and anti-HIV properties in human macrophages. The S-substituents were ranked in the following order of efficacy: H > or = acetyl > isobutyryl > pivaloyl > benzoyl. We found that none of these derivatives had pro-GSH or antiviral activities in vitro higher than that of 10, but several displayed similar levels of anti-HIV activity, making them possible candidates for use as adjuvant therapies in conjunction with HAART, for treating neurological aspects of HIV infection.

Acetylcysteine↗
PubMed2004

Potent nonclassical nucleoside antiviral drugs based on the N,N-diarylformamidine concept.

New formamidine-3TC (3TC = 2',3'-dideoxy-3'-thiacytidine) analogues have been synthesized through various methods, and their antiviral activities (HIV, HBV) have been evaluated in vitro. Anti-HIV-1 in acutely infected MT-4 cells and peripheral blood monocellular cells (PBMCs) showed that compounds substituted by N,N-diarylformamidine side chains at the 4-N nucleic base position (compounds 3 and 8-11) had at least equivalent anti-HIV activity as 3TC (EC50 = 0.5 and 11.6 microM, respectively). Moreover, the newly synthesized compounds demonstrated higher anti-HBV activity (EC50 ranging from 0.01 to 0.05 microM) compared to the parent nucleoside 3TC (EC50 = 0.2 microM). It should be underlined that these new promising derivatives inhibited HIV in cells of a macrophage lineage, which are known to be cellular reservoir for HIV. These results were particularly of interest, since the antiviral activities appeared not to be mediated through the formamidine bond hydrolysis and consequently the release of free 3TC. These new analogue series were found to be highly stable to hydrolysis even after prolonged incubation in different biological media (t(1/2) ranged from 48 to 120 h). This enzymatic stability, coupled to the fact that no delay in the antiviral response was observed compared to the free 3TC antiviral response, suggest that this new N,N-diarylformamidine nucleoside series should not be considered as classical prodrugs.

Amidines↗
PubMed2004

Inhibitors of CTP biosynthesis potentiate the anti-human immunodeficiency virus type 1 activity of 3TC in activated peripheral blood mononuclear cells.

Unlike hydroxyurea, the CTP synthetase inhibitor acivicin and, to a lesser extent, two other inhibitors of CTP synthesis, increased the phosphorylation and anti-HIV-1 activity of 3TC in PHA-P-activated PBMC. These data suggest that to improve the antiretroviral activity of 3TC, it may be worth focusing on inhibition of CTP synthesis.

Anti-HIV Agents↗
PubMed2004

Differential expression levels of MRP1, MRP4, and MRP5 in response to human immunodeficiency virus infection in human macrophages.

Multidrug resistance proteins (MRPs) have been reported to be involved in the efflux of some anti-human immunodeficiency virus (HIV) drugs. We show here that MRP1, MRP4, and MRP5 are expressed at the mRNA level in human monocyte-derived macrophages. HIV infection caused increased transcription of these MRPs; however, temporal differences in stimulation are reported.

Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)↗
PubMed2004

ATP binding cassette multidrug transporters limit the anti-HIV activity of zidovudine and indinavir in infected human macrophages.

OBJECTIVES: To investigate whether P-glycoprotein (P-gp) and multidrug resistance proteins (MRPs), which limit the bioavailability of HIV protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NRTIs), modulate the anti-HIV activity of NRTIs, non-NRTIs and PIs in vitro. DESIGN: We used primary cultures of major HIV target cells: human monocyte-derived macrophages (MDMs) and lymphocytes. METHODS: P-gp and MRP expression in response to long-term zidovudine (3'-azido-3'-deoxythymidine; AZT) or indinavir treatment was quantified by RT-PCR. MDM and lymphocytes were infected in vitro with HIV-1/Ba-L and HIV-1-LAI, respectively, and treated with antiretroviral drugs. We evaluated the activity of these drugs in combination with PSC833, a P-gp inhibitor, and/or probenecid, an MRP1 inhibitor. Intracellular AZT triphosphate derivative (AZT-TP) was quantified by HPLC-MSMS. P-gp ATPase activity was measured with inside-out native membrane vesicles enriched in P-gp. RESULTS: Levels of MDR1, mrp4 and mrp5 mRNA were high following AZT treatment. In infected MDM, PSC833 and probenecid increased the anti-HIV activity of AZT and indinavir. AZT (5 nM) decreased HIV replication by 34% alone and by 72% in combination with P-gp/MRP inhibitors. Indinavir (10 nM) gave 14% inhibition alone and 81% in combination. The increase in anti-HIV activity of AZT was correlated with an increase in intracellular AZT-TP concentration. However, unlike PIs, neither AZT nor its metabolites interacted with P-gp. CONCLUSION: AZT increases the expression of multidrug transporters, thereby decreasing its pharmacological activity. The cellular efflux of AZT probably involves MRP4 or MRP5. In contrast, increases in indinavir anti-HIV activity require the inhibition of both P-gp and MRP1.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2003

Inhibition of HIV-1 replication by cell-penetrating peptides binding Rev.

New therapeutic agents able to block HIV-1 replication are eagerly sought after to increase the possibilities of treatment of resistant viral strains. In this report, we describe a rational strategy to identify small peptide sequences owning the dual property of penetrating within lymphocytes and of binding to a protein target. Such sequences were identified for two important HIV-1 regulatory proteins, Tat and Rev. Their association to a stabilizing domain consisting of human small ubiquitin-related modifier-1 (SUMO-1) allowed the generation of small proteins named SUMO-1 heptapeptide protein transduction domain for binding Tat (SHPT) and SUMO-1 heptapeptide protein transduction domain for binding Rev (SHPR), which are stable and efficiently penetrate within primary lymphocytes. Analysis of the antiviral activity of these proteins showed that one SHPR is active in both primary lymphocytes and macrophages, whereas one SHPT is active only in the latter cells. These proteins may represent prototypes of new therapeutic agents targeting the crucial functions exerted by both viral regulatory factors.

Anti-HIV Agents↗