Biomedical subjects
Publications and source records attributed to C Desgranges.
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8-(N,N-Diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), a putative inhibitor of intracellular calcium mobilization, causes a dose-dependent inhibition of serum-induced proliferation of arterial smooth muscle cells in culture. Neither early rise in cytosolic calcium concentration nor induction of early induced cell cycle dependent genes (c-fos, ornithine decarboxylase) are inhibited after serum stimulation in presence of 100 microM TMB-8. In contrast, expression of thymidine kinase, a gene normally induced in late-G1 phase, is entirely inhibited by TMB-8. Taken together with flow cytometry studies, these results indicate that TMB-8 blocks cell cycle progression in mid- or late-G1 phase by a mechanism not directly related to early responses to serum stimulation since TMB-8 is also effective when introduced several hours after serum stimulation.
We have analyzed the heavy-chain variable (VH) region genes expressed by a panel of human monoclonal antibodies derived from an immunized volunteer, an AIDS patient and seropositive asymptomatic donors, and specific for HIV-1 env, pol and gag gene products. The third complementarity-determining regions show a high complexity with unconventional gene recombination events. Most of the VH genes utilized are also frequently encountered in other immune responses. Their sequences are, in general, typical of an antigen-driven immune response. Molecular mechanisms that generate high-affinity antibodies are then effective during HIV infection. Remarkably, VH3 family, which dominates the human antibody repertoire, is barely encountered among anti-HIV antibodies.
Sera from 11 perinatally HIV1-infected Rwandan children with prolonged survival were tested in vitro for the presence of neutralizing antibodies against different HIV1 strains. These 11 sera from long survivor (LS) children were compared with 16 sera from Rwandan children with AIDS. Sera from HIV1-infected children exhibited the greatest neutralizing activity against HIV1MN cell-free infection. They also inhibited HIV1RII and HIV1LAI cell-free infection with lower titres. Higher neutralization titres were observed in sera from LS compared to the AIDS group, with a significant difference for HIV1MN and HIV1LAI strains. Sera from LS children also inhibited syncytium formation induced by HIV1MN-infected cells with higher titres than AIDS children. Sera from the HIV1-infected children showed reactivity to the HIV1MN V3 peptide, as well as to both the US/European and the African consensus V3 peptides. Higher reactivity was observed in sera from LS than from AIDS children, and the difference was significant toward the African consensus peptide. The LS children also had significantly higher V3MN IgG avidity than the AIDS children. These data support the notion that the humoral response to the V3 domain, associated with a broadly neutralizing activity, may be an important factor in the prolonged survival of these children. The specificity against HIV1MN also suggests that an antigenically MN-related strain may be prevalent in Rwanda, and that an MN-related principal neutralizing domain sequence could be an important determinant for candidate vaccines in this part of Africa.
Human epidermal Langerhans cells (LC) isolated from normal skin were infected in vitro with human immunodeficiency virus type 1 (HIV1). To control the permissivity of LC for HIV1, cells isolated from the epidermal sheet of normal skin by trypsinization were cocultured with HIV1-carrying promonocytic cells (U937) and observed by electron microscopy. An early sign of infection occurring in the coculture was the formation of retroviral type buds from LC membrane. Different steps in the process of viral budding up to virus release into the extracellular space were observed by electron microscopy. Treatment with either coupled phorbol esters/bacterial lipopolysaccharide or a recombinant cytokine (tumour necrosis factor alpha) did not significantly enhance viral production. The ability of in vitro infected LC to transmit virus to other haematopoietic cells and the consequences of such an infection on antigen-presenting function of LC remain to be elucidated.
Human spleen cells from an HIV-seropositive donor were immunized in vitro with the aa583-599 peptide conjugated to an heptalysyl core. This sequence was derived from the putatively HIV-immunosuppressive region of HIV1 gp41. The same conjugated peptide was used to immunize mice. One human and one mouse IgM monoclonal antibody (mAb) directed against the aa583-599 peptide were obtained. The two mAb had distinct patterns of reactivity against a panel of 42 peptides with modified sequences. Neither of the mAb inhibited the immunosuppressive effect of aa583-599 octopus-lys-conjugated peptide on anti-CD3 Ab-induced lymphoproliferation. In addition, both mAb did not neutralize cell-free virus transmission or enhance HIV infection. However, HmAb inhibited formation of syncytia between HIV1-infected (but not HIV2-infected cells) and non-infected target cells at concentrations above 20 micrograms/ml, whereas MmAb did not have any effect. The degree of conservation of the aa583-599 region makes HmAb a candidate for use as a group-specific reagent in future HIV1 passive immunotherapy protocols.
Apoptosis of arterial smooth muscle cells (ASMCs) could play an important role in the pathogenesis of atherosclerosis and restenosis. Recent studies have demonstrated that extracellular adenosine induces apoptosis in various cell types. Our aim was to delineate the capacity of this nucleoside to induce ASMC apoptosis in arterial diseases. We demonstrate that adenosine dose-dependently triggers apoptosis of cultured human ASMCs. Apoptotic cell death was quantified by analysis of nuclear chromatin morphology and characterized by DNA laddering. The involvement of adenosine receptors was suggested, because neither an adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride, nor an inhibitor of cellular nucleoside transport, dipyridamole, was able to inhibit adenosine-induced ASMC apoptosis. In contrast, an A(1)/A(2)-adenosine receptor antagonist, xanthine amine congener, totally inhibited adenosine-induced apoptosis. Furthermore, among more selective inhibitors of P(1) purinoceptor subtypes, only alloxazine, an antagonist of A(1)- and A(2)-adenosine receptors, completely inhibited adenosine-induced ASMC apoptosis, suggesting that adenosine triggers ASMC apoptosis via either 1 or both of these receptors. However, 8-cyclopentyl-1,3-dipropylxanthine, 8-(3-chlorostyryl) caffeine, and 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1, 4-(+/-)-dihydropyridine-3,5-dicarboxylate, which are A(1)-, A(2a)-, and A(3)-adenosine receptor antagonists, did not inhibit adenosine-induced apoptosis, suggesting an involvement of the A(2b)-receptor in this process. Moreover, the cAMP increase followed by cAMP-dependent protein kinase activation appears essential to mediate adenosine-induced ASMC apoptosis, thus confirming the previous hypothesis. These results indicate that adenosine-induced apoptosis of ASMCs is essentially mediated via A(2b)-adenosine receptor and involves a cAMP-dependent pathway.