34 research outputs found
Approximation des moments par l'utilisation de la théorie des fonctions analytiques
No full textIn this thesis, I define and explain the notion of punctual analytical uniform development (DUAP) versus moments or cumulants approximation of punctual uniforms analyticals 's class statistics. Hence, I derive "truncated" DUAP's version for numerical computation and implementation which called finite DUAP (F-DUAP). Using F-DUAP approximation lead to an error which was estimated. Due to nature's one of axiom of UAP statistics, the concept extension of DUAP method, to an other class statistic is limited. So, a new local theoretical concept was defined named analytical uniform development (DUA). This generalization let all derived DUAP's theorems become more general. Automatic differentiation and F-DUAP allow the implementation of DUAP or DUA method's on computer: I write the CUMAD and CUMADG codes that make the methods of a practical use. By, the programme CUMAD, I valid the utility of DUAP method, when I applied it to the approximation to moments of "weighted sum of squares statistic".GR-FRSTA
Blood CXCR3+ CD4 T Cells Are Enriched in Inducible Replication Competent HIV in Aviremic Antiretroviral Therapy-Treated Individuals
No full textWe recently demonstrated that lymph nodes (LNs) PD-1+/T follicular helper (Tfh) cells from antiretroviral therapy (ART)-treated HIV-infected individuals were enriched in cells containing replication competent virus. However, the distribution of cells containing inducible replication competent virus has been only partially elucidated in blood memory CD4 T-cell populations including the Tfh cell counterpart circulating in blood (cTfh). In this context, we have investigated the distribution of (1) total HIV-infected cells and (2) cells containing replication competent and infectious virus within various blood and LN memory CD4 T-cell populations of conventional antiretroviral therapy (cART)-treated HIV-infected individuals. In the present study, we show that blood CXCR3-expressing memory CD4 T cells are enriched in cells containing inducible replication competent virus and contributed the most to the total pool of cells containing replication competent and infectious virus in blood. Interestingly, subsequent proviral sequence analysis did not indicate virus compartmentalization between blood and LN CD4 T-cell populations, suggesting dynamic interchanges between the two compartments. We then investigated whether the composition of blood HIV reservoir may reflect the polarization of LN CD4 T cells at the time of reservoir seeding and showed that LN PD-1+ CD4 T cells of viremic untreated HIV-infected individuals expressed significantly higher levels of CXCR3 as compared to CCR4 and/or CCR6, suggesting that blood CXCR3-expressing CD4 T cells may originate from LN PD-1+ CD4 T cells. Taken together, these results indicate that blood CXCR3-expressing CD4 T cells represent the major blood compartment containing inducible replication competent virus in treated aviremic HIV-infected individuals
Active PD-L1 incorporation within HIV virions functionally impairs T follicular helper cells
No full textThe limited development of broadly neutralizing antibodies (BnAbs) during HIV infection is classically attributed to an inadequate B-cell help brought by functionally impaired T follicular helper (Tfh) cells. However, the determinants of Tfh-cell functional impairment and the signals contributing to this condition remain elusive. In the present study, we showed that PD-L1 is incorporated within HIV virions through an active mechanism involving p17 HIV matrix protein. We subsequently showed that in vitro produced PD-L1high but not PD-L1low HIV virions, significantly reduced Tfh-cell proliferation and IL-21 production, ultimately leading to a decreased of IgG1 secretion from GC B cells. Interestingly, Tfh-cell functions were fully restored in presence of anti-PD-L1/2 blocking mAbs treatment, demonstrating that the incorporated PD-L1 proteins were functionally active. Taken together, the present study unveils an immunovirological mechanism by which HIV specifically exploits the regulatory potential of PD-L1 to suppress the immune system during the course of HIV infection
Rapid perturbation in viremia levels drives increases in functional avidity of HIV-specific CD8 T cells.
No full textThe factors determining the functional avidity and its relationship with the broad heterogeneity of antiviral T cell responses remain partially understood. We investigated HIV-specific CD8 T cell responses in 85 patients with primary HIV infection (PHI) or chronic (progressive and non-progressive) infection. The functional avidity of HIV-specific CD8 T cells was not different between patients with progressive and non-progressive chronic infection. However, it was significantly lower in PHI patients at the time of diagnosis of acute infection and after control of virus replication following one year of successful antiretroviral therapy. High-avidity HIV-specific CD8 T cells expressed lower levels of CD27 and CD28 and were enriched in cells with an exhausted phenotype, i.e. co-expressing PD-1/2B4/CD160. Of note, a significant increase in the functional avidity of HIV-specific CD8 T cells occurred in early-treated PHI patients experiencing a virus rebound after spontaneous treatment interruption. This increase in functional avidity was associated with the accumulation of PD-1/2B4/CD160 positive cells, loss of polyfunctionality and increased TCR renewal. The increased TCR renewal may provide the mechanistic basis for the generation of high-avidity HIV-specific CD8 T cells. These results provide insights on the relationships between functional avidity, viremia, T-cell exhaustion and TCR renewal of antiviral CD8 T cell responses
PD-1+ and follicular helper T cells are responsible for persistent HIV-1 transcription in treated aviremic individuals
No full textThe mechanisms responsible for the persistence of HIV-1 after many years of suppressive antiretroviral therapy (ART) have been only partially elucidated. Most of the studies investigating HIV-1 persistence have been performed with blood, although it is well known that germinal centers (GCs) within lymph nodes (LNs) serve as primary sites for HIV-1 replication. We sought to identify the memory CD4 T cell populations in blood and LNs that are responsible for the production of replication-competent and infectious HIV-1, as well as for active and persistent virus transcription in ART-treated (for 1.5-14.0 years), aviremic (<50 HIV RNA copies/ml) HIV-infected individuals. We demonstrate that LN CD4 T cells that express programmed cell death 1 (PDCD1; also known as PD-1), which are composed of about 65% T follicular helper cells as defined by the expression of the cell surface receptors CXCR5 and PD-1, are the major source of replication-competent HIV-1 and of infectious virus, as compared to any other (CXCR5 - PD-1- and CXCR5+ PD-1-) blood or LN memory CD4 T cell populations. LN PD-1+ cells accounted for 46% and 96% of the total pools of memory CD4 T cells containing inducible replication-competent or infectious virus, respectively. Notably, higher levels of cell-associated HIV-1 RNA were present in LN PD-1+ cells after long-term (up to 12 years) ART than in other memory CD4 T cell subpopulations. These results indicate that LN PD-1+ cells are the major CD4 T cell compartment in the blood and LNs for the production of replication-competent and infectious HIV-1, and for active and persistent virus transcription in long-term-ART-treated aviremic individuals. Thus, these cells may represent a major obstacle to finding a functional cure for HIV-1 infection
HIV infection functionally impairs Mycobacterium tuberculosis-specific CD4 and CD8 T-cell responses
No full textHuman immunodeficiency virus (HIV) infection is the major risk factor predisposing for; Mycobacterium tuberculosis; progression from latent tuberculosis infection (LTBI) to tuberculosis disease (TB). Since long-term-treated aviremic HIV-infected individuals remained at higher risk of developing TB than HIV-uninfected individuals, we hypothesized that progression from LTBI to pulmonary TB (PTB) might be due not only to CD4 T-cell depletion but also to; M. tuberculosis; -specific CD4 T-cell functional impairment. To test this hypothesis,; M. tuberculosis; -specific T-cell frequencies and cytokine profiles were investigated in untreated Tanzanian individuals suffering from LTBI (; n; = 20) or PTB (; n; = 67) and compared to those of untreated; M. tuberculosis; /HIV-coinfected individuals suffering from LTBI (; n; = 15) or PTB (; n; = 10). We showed that HIV infection significantly reduced the proportion of Th2 (interleukin 4 [IL-4]/IL-5/IL-13) producing; M. tuberculosis; -specific CD4 T cells and IL-2-producing; M. tuberculosis; -specific CD4 and CD8 T cells in individuals with LTBI or PTB (; P < ; 0.05). Interestingly, the loss of IL-2 production was associated with a significant increase of PD-1 expression on; M. tuberculosis; -specific CD4 and CD8 T cells (; P < ; 0.05), while the loss of Th2 cytokine production was associated with a significant reduction of Gata-3 expression in memory CD4 T cells (; P < ; 0.05). Finally, we showed that the serum levels of IL-1α, IL-6, C-reactive protein (CRP), IL-23, and IP-10 were significantly reduced in; M. tuberculosis; /HIV-coinfected individuals with PTB compared to those in HIV-negative individuals with PTB (; P < ; 0.05), suggesting that HIV infection significantly suppresses; M. tuberculosis; -induced systemic proinflammatory cytokine responses. Taken together, this study suggests that in addition to depleting; M. tuberculosis; -specific CD4 T cells, HIV infection significantly impairs functionally favorable; M. tuberculosis; -specific CD4 T-cell responses in Tanzanian individuals with LTBI or PTB.; IMPORTANCE; Mycobacterium tuberculosis; and human immunodeficiency virus (HIV) infections are coendemic in several regions of the world, and; M. tuberculosis; /HIV-coinfected individuals are more susceptible to progression to tuberculosis disease. We therefore hypothesized that HIV infection would potentially impair; M. tuberculosis; -specific protective immunity in individuals suffering from latent tuberculosis infection (LTBI) or active pulmonary tuberculosis (PTB). In this study, we demonstrated that; M. tuberculosis; /HIV-coinfected individuals have fewer circulating; M. tuberculosis; -specific CD4 T cells and that those that remained were functionally impaired in both LTBI and PTB settings. In addition, we showed that HIV infection significantly interferes with; M. tuberculosis; -induced systemic proinflammatory cytokine/chemokine responses. Taken together, these data suggest that HIV infection impairs functionally favorable; M. tuberculosis; -specific immunity
Influence of PD-L1<sup>+</sup> virions on early TCR mediated signaling of primary CD4 T cells.
No full textCD4 T cells isolated from tonsils of HIV-uninfected individuals (N = 3) were stimulated with anti-CD3/CD28 mAbs for 5 minutes in presence or in absence of in vitro produced PD-L1low HIV virions or PD-L1high HIV virions. As controls, cells remained unstimulated. The phosphorylation of ZAP70 and SLP76 was assessed by mass cytometry on PD-1- and PD-1+ memory (CD45RO+) CD4 T cells and used as markers of early TCR signaling cascade. A. Gating strategy. B. Heatmap representing the mean signal intensity of phospho-ZAP70 and phospho-SLP76 signaling proteins of TCR stimulated PD-1- and PD-1+ memory CD4 T cells in presence or in absence of PD-L1low or PD-L1high HIV virions as compared to unstimulated condition of one representative subject (#111A). The change of color (blue: negative; yellow: positive) indicate the mean signal intensity of phosphorylated signaling proteins. Cumulative data representing the percentage of phopho-ZAP70 (C) or phospho-SLP76 (D) of PD-1- and PD-1+ CD4 T cells stimulated or not in presence or in absence of PD-L1low or PD-L1high HIV virions (N = 3). Histograms correspond to the mean and black error bars correspond to the SEM. Statistical significance (P values) was obtained using one-way ANOVA (Kruskal-Wallis test) followed by a Dunn’s multiple comparison test. (TIF)</p
PD-L1<sup>+</sup> HIV virions represent a major fraction of plasmatic virions of viremic HIV-infected individuals.
No full textPolystyrene beads coated with a pool of anti-gp120/41 mAbs were used to capture HIV virions from plasma of viremic HIV-infected individuals (N = 37). A. Representative histogram of mass cytometry profile of gp120/41+ vesicles from plasma of one HIV-uninfected individual (HS#4252) and one viremic HIV-infected individual (HIV#0178). B. Proportion of beads with captured gp120/41+ vesicles of plasma from HIV-uninfected individuals (N = 10) and viremic HIV-infected individuals (N = 37). C. Representative mass cytometry profile of plasmatic gp120/41+ vesicles captured from one HIV-infected individual (HIV#8226). D. Cumulative data mass cytometry profiles of plasmatic gp120/41+ vesicles captured from HIV-infected individuals (N = 37). E. Proportion of gp120/41+ vesicles captured with beads coated with anti-PD-L1 mAbs or isotype-control as compared to beads coated with the pool of anti-gp120/41 mAbs (considered as reference) from plasma of viremic HIV-infected individual (N = 10). F. Proportion of HIV RNA levels detected in culture supernatants of activated CD4 T cells exposed to vesicles captured using beads coated with anti-PD-L1 mAbs or an isotype-control as compared to beads coated with anti-gp41 F240 mAbs (considered as reference) from plasma of viremic HIV-infected individual (N = 7). MMO; mass-minus one staining. Histograms correspond to the mean and red error bars correspond to SEM (B, D-F). Black stars indicate statistical significance (* = PPPP values) was obtained using Mann Whitney test (B, E-F) or using one-way ANOVA (Friedman test) followed by a Dunn’s multiple comparison test (D).</p
HIV RNA levels detected in culture supernatants of HIV-infected MDM and activated CD4 T cells.
No full textMDM and activated CD4 T cells from HIV-uninfected individuals (N = 4) were infected with HIV-lab-derived variants and cultured for 14 days in absence of emtricitabin. HIV RNA levels were assessed in culture supernatants at day 14 post infection. Some experiments were conducted with three distinct HIV lab-derived variants (Bal, IIIB and JR-CSF). Histograms correspond to the mean and red error bars correspond to the SEM. n.s. indicate no statistical significance (P>0.05). Statistical significance (P values) was obtained using one-way ANOVA (Kruskal-Wallis test) followed by a Dunn’s multiple comparison test. (TIF)</p
Lymph node migratory dendritic cells modulate HIV-1 transcription through PD-1 engagement
No full textT-follicular helper (Tfh) cells, co-expressing PD-1 and TIGIT, serve as a major cell reservoir for HIV-1 and are responsible for active and persistent HIV-1 transcription after prolonged antiretroviral therapy (ART). However, the precise mechanisms regulating HIV-1 transcription in lymph nodes (LNs) remain unclear. In the present study, we investigated the potential role of immune checkpoint (IC)/IC-Ligand (IC-L) interactions on HIV-1 transcription in LN-microenvironment. We show that PD-L1 (PD-1-ligand) and CD155 (TIGIT-ligand) are predominantly co-expressed on LN migratory (CD1chighCCR7+CD127+) dendritic cells (DCs), that locate predominantly in extra-follicular areas in ART treated individuals. We demonstrate that TCR-mediated HIV production is suppressed in vitro in the presence of recombinant PD-L1 or CD155 and, more importantly, when LN migratory DCs are co-cultured with PD-1+/Tfh cells. These results indicate that LN migratory DCs expressing IC-Ls may more efficiently restrict HIV-1 transcription in the extra-follicular areas and explain the persistence of HIV transcription in PD-1+/Tfh cells after prolonged ART within germinal centers.</div
