Développement d'un vaccin prophylactique et thérapeutique contre le VIH/SIDA (induction d'anticorps neutralisant le VIH-1 par des peptides synthétiques dérivés de l'épitope CBD1)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

The caveolin-1 binding domain of HIV-1 glycoprotein gp41 (CBD1) contains several overlapping neutralizing epitopes.

International audienceThe CBD1 peptide (SLEQIWNNMTWMQWDK), corresponding to the consensus caveolin-1 binding domain in HIV-1 envelope glycoprotein gp41 (CBD1), elicits the production of antibodies that inhibit infection of primary CD4(+) T lymphocytes by various primary HIV-1 isolates. Here we show that HIV-neutralizing antibodies against CBD1 react with multiple conformational epitopes that overlap the highly conserved caveolin-1 binding motif (CBM) with the N-terminal conserved isoleucine residue. The CBM-based peptides IWNNMTWMQW and IWNNMTW when fused to a T helper epitope are immunogenic by inducing high titer CBM-specific antibodies capable of neutralizing HIV-1 infection in primary T lymphocyte cultures. Interestingly, neutralizing immune sera raised against a given peptide do not cross-react with related CBM-derived peptides, thus suggesting the existence of distinct neutralizing epitopes that probably reflect the dynamic conformational features of CBD1. In accord with this, the mixture of neutralizing immune sera raised against several CBM-derived peptides exerts a synergistic neutralizing activity against HIV-1 infection. Finally, the existence of several distinct overlapping epitopes in CBD1 is confirmed by murine monoclonal antibodies that we generated against the CBM-derived chimeric peptides. Our results indicate that CBD1- and CBM-based peptides mimic distinct dynamic conformations of CBD1, and thus such peptides could provide specific immunogens for an efficient vaccine preparation against HIV/AIDS infection

The CBD1 peptide corresponding to the caveolin-1 binding domain of HIV-1 glycoprotein gp41 elicits neutralizing antibodies in cynomolgus macaques when administered with the tetanus T helper epitope.

International audienceCBD1 peptide (SLEQIWNNMTWMQWDK), corresponding to the consensus caveolin-1 binding domain in HIV-1 envelope glycoprotein gp41, elicits the production of antibodies that inhibit infection of primary CD4(+) T lymphocytes by various primary HIV-1 isolates. Here the immunogenicity of the CBD1 peptide was investigated in cynomolgus macaques using adjuvants that are acceptable for human use. In the first set of studies, macaques were immunized with the CBD1 peptide in association with muramyl dipeptide derivative MDP-Lys(L18) combined with the oil-in-water emulsion, MF-59. After five immunizations at 4 weeks interval, the antibody titer against the CBD1 peptide was found to be either medium, poor, weak or none, thus suggesting that the CBD1 immune response might be restricted by the major histocompatibility complex (MHC) class II molecules. In the second set of studies therefore, macaques were immunized with the CBD1 peptide in association with the 'promiscuous' T cell epitope from the tetanus toxin, either as free peptides or covalently linked with the dilysine linker using CpG ODN and Montanide ISA 51 as adjuvants. This latter immunization procedure boosted markedly the anti-CBD1 antibody response, since even the non-responders generated high-titered peptide-specific antibodies. Moreover, co-immunization of the CBD1 and the T helper epitope as free peptides seemed to be favorable for the production of neutralizing antibodies, with 50% inhibition of HIV-1 infection occurring at 300-400-fold dilution of the immune sera. Finally, neutralizing and non-neutralizing immune macaque sera could be differentiated by the profile of cross-reactivity with overlapping CBD1-related peptides in ELISA. Taken together, our results demonstrate that the CBD1 peptide is immunogenic in macaques and that an eventual MHC-restriction could be overcome by the administration with an appropriate T helper epitope

HIV-1 neutralizing antibodies elicited by the candidate CBD1 epitope vaccine react with the conserved caveolin-1 binding motif of viral glycoprotein gp41.

To date, candidate HIV-1 vaccines that have been tested in clinical trials have failed to induce broadly neutralizing activities and/or antibodies that inhibit infection by primary isolates of HIV-1. We recently identified a conserved caveolin-1 binding motif, WNNMTWMQW, in the ectodomain of HIV-1 transmembrane envelope glycoprotein gp41. We designed the synthetic CBD1 peptide SLEQIWNNMTWMQWDK, corresponding to the consensus caveolin-1 binding domain (CBD) in gp41, and showed that it elicits in rabbits the production of antibodies that inhibit infection of primary CD4(+) T lymphocytes by various primary HIV-1 isolates. Although a conserved and highly homologous caveolin-1 binding motif is present in the transmembrane envelope glycoprotein of different HIV-2 isolates, anti-CBD1 immune sera do not inhibit HIV-2 infection. Here we show that anti-CBD1 antibodies are directed against the conserved caveolin-1 binding motif WNNMTWMQW in the CBD1 epitope. In spite of this, anti-CBD1 antibodies do not react with the CBD2 peptide SLTPDWNNMTWQEWER, corresponding to the potential consensus caveolin-1 binding domain in HIV-2. The presence of a conserved proline residue upstream of the caveolin-1 binding motif in CBD2 might affect the presentation of this motif, and thus account for the lack of reactivity of the immune sera. Anti-CBD1 antibodies therefore appear to be directed against a conformational epitope mimicked by the synthetic CBD1 peptide. In accordance with this, anti-CBD1 immune sera react with the native but not denatured gp41. The reactivity of anti-CBD1 immune sera with a highly conserved conformational epitope could explain the broad inhibitory activity of such antipeptide antibodies against HIV-1 isolates of various clades

Serotonin transporter inhibition prevents and reverses monocrotaline-induced pulmonary hypertension in rats.: 5-HT Transporter Inhibition Prevents PH

9 pagesInternational audienceBACKGROUND: Progression of pulmonary hypertension (PH) is associated with increased lung expression of the serotonin transporter (5-HTT), which leads to hyperplasia of the pulmonary artery smooth muscle cells (PA-SMCs). Given the postulated causal relation between 5-HTT overexpression and PH, we herein investigated whether the highly selective 5-HTT inhibitor fluoxetine prevented and/or reversed PH induced by monocrotaline (MCT) in rats. Selective 5-HT(1B/1D), 5-HT(2A), and 5-HT(2B) receptor antagonists were used for comparative testing. METHODS AND RESULTS: MCT injection (60 mg/kg SC) was followed by an early peak in lung 5-HTT expression on day 1, which preceded the onset of PH. Established PH on day 15 was associated with a sustained 5-HTT increase. Continued fluoxetine treatment completely prevented PA-SMC proliferation and PH development and also suppressed the late 5-HTT increase, without affecting the early peak. The 5-HT receptor antagonists did not affect PH. Fluoxetine (10 mg . kg(-1) . d(-1) PO) started 3 weeks after MCT injection completely reversed established PH, normalizing PA pressure and structure. MCT-induced PH was also associated with increased expression of various cytokines, but only interleukin-1beta and monocyte chemotactic protein-1 increased at the early phase and stimulated 5-HTT expression by cultured PA-SMCs. CONCLUSIONS: Upregulation of lung 5-HTT induced by MCT appears necessary to initiate the development of pulmonary vascular remodeling, whereas a sustained increase in 5-HTT expression may underlie both the progression and the maintenance of MCT-induced PH. Complete reversal of established PH by fluoxetine provides a rationale for new therapeutic strategies in human PH