Dendritic Cells from HIV Controllers Have Low Susceptibility to HIV-1 Infection In Vitro but High Capacity to Capture HIV-1 Particles

ANRS CO21 CODEX cohortInternational audienceHIV controllers (HICs), rare HIV-1 infected individuals able to control viral replication without antiretroviral therapy, are characterized by an efficient polyfunctional and cytolytic HIV-specific CD8+ T cell response. The mechanisms underlying the induction and maintenance of such response in many HICs despite controlled viremia are not clear. Dendritic cells play a crucial role in the generation and reactivation of T cell responses but scarce information is available on those cells in HICs. We found that monocyte derived dendritic cells (MDDCs) from HICs are less permissive to HIV-1 infection than cells from healthy donors. In contrast MDDCs from HICs are particularly efficient at capturing HIV-1 particles when compared to cells from healthy donors or HIV-1 patients with suppressed viral load on antiretroviral treatment. MDDCs from HICs expressed on their surface high levels of syndecan-3, DC-SIGN and MMR, which could cooperate to facilitate HIV-1 capture. The combination of low susceptibility to HIV-1 infection but enhanced capacity to capture particles might allow MDDCs from HICs to preserve their function from the deleterious effect of infection while facilitating induction of HIV-specific CD8+ T cells by cross-presentation in a context of low viremia

One Step Closer to HIV Eradication?

International audienceIn the global fight against HIV/AIDS, the persistence of viral reservoirs, established early during primary infection by the Human Immunodeficiency virus (HIV), is probably the biggest challenge to finding a cure for HIV, despite the major progress provided by antiviral treatments. This persistence reflects virus latency in the immune system and imposes the prospect of life-long treatment with risk of toxicities, and major costs for society. Innovative strategies aimed at purging these viral reservoirs are therefore required, but the complexity of the latency mechanisms has made a sterilization cure difficult to realize until now. However, recent cases of HIV remission have encouraged the research community, and a functional cure seems to be a more realistic goal to attempt. A better understanding of the mechanisms responsible for such latency has been provided by basic research, although recent attempts at purging the reservoirs by disrupting latency have been somewhat disappointing. In contrast, the early initiation of anti-retroviral treatment appears to be extremely beneficial for HIV remission, as recently suggested by the Mississippi baby case or by the series of post-treatment controllers, respectively. Early treatment initiation can indeed rapidly limit the size of viral reservoirs, or hamper their formation and preserve the host’s immune responses. Despite these encouraging results, it is nevertheless important to deploy more effort toward a better understanding of latency mechanisms and to the development of innovative approaches and molecules in the hope of achieving a cure for HIV

Les Contrôleurs du VIH-1 (rôle des cellules dendritiques myéloïdes et de la réponse T CD8 dans le contrôle de l infection par le VIH-1)

Les patients contrôleurs du VIH (HIC) sont capables de contrôler durablement l infection VIH sans traitement. Certains HIC (forts répondeurs :SR) ont des réponses TCD8 quantitativement et qualitativement fortes. Comprendre comment ces réponses sont générées et maintenues pourrait orienter les recherches vaccinales. D autres HIC (faibles répondeurs :WR) contrôlent la charge virale en dépit de faibles réponses TCD8, suggèrant l existence d autres mécanismes de contrôle. Cependant, la faible réponse TCD8 peut être in vivo suffisante pour le contrôle viral. Pour comprendre les mécanismes de génération et de maintien de la réponse TCD8 chez les SR, j ai fait une étude phénotypique, transcriptomique et fonctionnelle des mDC. Nos résultats révèlent un faible profil inflammatoire des mDC des HIC sans altération de leurs capacité à stimuler les LT CD8. D autre part, les mDC des HIC ont une forte capacité à capturer le VIH-1 mais une faible susceptibilité à l infection. Ceci suggère une résistance des mDC des HIC à l infection VIH et une capacité efficace à d induire des réponses T CD8 dans un contexte peu inflammatoire. Pour explorer le rôle de la réponse TCD8 dans contrôle viral chez les HIC WR, nous avons éliminé in vivo les cellules CD8 chez des macaques contrôleurs du SIV(SIC), présentant de faibles réponses TCD8. La déplétion a causé une perte du contrôle viral chez la majorité des SIC mais la reprise du contrôle n est pas associée à une expansion importante, ni une augmentation des fonctions cytotoxiques de LT CD8. L expansion homéostatique des LT CD4 en réponse à une élévation cytokiniques pourrait expliquer la perte du contrôle virale. Nos résultats suggèrent que la réponse TCD8 n explique pas à elle seule le contrôle viral chez les WR, impliquant la contribution d autres mécanismes. Dans ce contexte, nous démontrons une susceptibilité réduite des LT CD4 et les macrophages des HIC à l infection VIH-1, ce qui pourrait contribuer à limiter le réservoir et aider contrôle viralHIV-controllers (HIC) are rare patients able to control HIV replication for several years without therapy, Some HIC (strong responders: SR) have robust CD8 T response which should be induced by a vaccine, hence the importance of understanding how this response is generated and maintained in SR. However, other HICs (Weak Responders:WR) control viral load without strong CD8 T response. This suggest the presence of other mechanisms of HIV control, although it cannot be excluded the presence of an effective memory CD8 T response in WR contributing to the viral control. To understand the mechanisms of the generation and the maintenance of such strong CD8 T response in SR, we studied a phenotypic and transcriptomic profil of myeloid dendritic cells (mDC). Our results suggest a low inflammatory profil of mDC and absence of defects in pathways relevant to CD8 T response induction. Functional studies showed a strong capacity of mDC to capture HIV but low susceptibility of these cells to infection. At all, our data suggest an resistance of HIC mDC s to HIV infection with a high capacity to induce an effective CD8 T response in low infammation context. To explore the role of CD8 T response in viral control in WR, we used simien model of SIV-Controllers macaques (SIC) with weak CD8 T response. We depleted in vivo CD8+ cells of these SIC. The depletion induced a transient loss of viral control in majority of SIC. The regain of the control has not been associated with a major expansion, nor an increase of cytotoxic functions of CD8 T cells. The loss of viral control has been associated with the homeostatic expansion of CD4 T cells in response to an increase of plasma cytokines. Our results suggest that the CD8 T response can not explain alone the viral control in WR. Other mechanisms could contribute to viral control. In these lines, we have demonstrated that CD4 T cells and macrophages from HIC are relatively resistant to HIV-1 infection, which could contribute to limit the viral reservoir and help for viral controlPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Will it be possible to live without antiretroviral therapy?

International audiencePURPOSE OF REVIEW:Some individuals are able to control HIV infection (either viral replication or chronic immune activation) in the absence of therapy. We will consider recent insights into the mechanisms underlying control in these patients and how this has already encouraged the search for therapeutic approaches to induce a similar HIV functional cure in other patients.RECENT FINDINGS:Spontaneous reduction of HIV viremia to undetectable levels as observed in a few HIV-infected patients is associated with an efficient HIV-specific CD8 T-cell response, the characteristics of which are now better understood. However, maintenance of such control may involve alternative mechanisms. In particular, the presence of a very small viral reservoir seems necessary, although not sufficient, to ensure HIV control in the long term. Approaches designed to limit the early establishment of these reservoirs, to eliminate infected cells, or to avoid replenishment of the reservoirs have led to HIV remission in the absence of therapy in a few cases. Alternatively, other rare patients seem to deal with HIV infection by controlling immune activation despite high levels of viremia like the natural African monkey hosts do with SIV. These observations suggest that regulation of immune activation should be considered as a serious complement to conventional therapies targeting the virus itself.SUMMARY:A better understanding of the mechanisms underlying control of HIV infection or disease in some patients has already led to successful approaches in certain individuals. However, much work is still needed to generalize these results to the global population of HIV-infected patients

Antibodies attenuate the capacity of dendritic cells to stimulate HIV-specific cytotoxic T lymphocytes

International audienceBACKGROUND: Control of HIV is suggested to depend on potent effector functions of the virus-specific CD8(+) T-cell response. Antigen opsonization can modulate the capture of antigen, its presentation, and the priming of specific CD8(+) T-cell responses. OBJECTIVE: We have previously shown that opsonization of retroviruses acts as an endogenous adjuvant for dendritic cell (DC)-mediated induction of specific cytotoxic T lymphocytes (CTLs). However, in some HIV-positive subjects, high levels of antibodies and low levels of complement fragments coat the HIV surface. METHODS: Therefore we analyzed the effect of IgG opsonization on the antigen-presenting capacity of DCs by using CD8(+) T-cell proliferation assays after repeated prime boosting, by measuring the antiviral activity against HIV-infected autologous CD4(+) T cells, and by determining IFN-γ secretion from HIV-specific CTL clones. RESULTS: We find that DCs exposed to IgG-opsonized HIV significantly decreased the HIV-specific CD8(+) T-cell response compared with the earlier described efficient CD8(+) T-cell activation induced by DCs loaded with complement-opsonized HIV. DCs exposed to HIV bearing high surface IgG levels after incubation in plasma from HIV-infected subjects acted as weak stimulators for HIV-specific CTL clones. In contrast, HIV opsonized with plasma from patients exhibiting high complement and low IgG deposition on the viral surface favored significantly higher activation of HIV-specific CD8(+) T-cell clones. CONCLUSION: Our ex vivo and in vitro observations provide the first evidence that IgG opsonization of HIV is associated with a decreased CTL-stimulatory capacity of DCs

Long-Term Control of Simian Immunodeficiency Virus (SIV) in Cynomolgus Macaques Not Associated with Efficient SIV-Specific CD8 + T-Cell Responses.

International audienceThe spontaneous control of human and simian immunodeficiency viruses (HIV/SIV) is typically associated with specific major histocompatibility complex (MHC) class I alleles and efficient CD8(+) T-cell responses, but many controllers maintain viral control despite a nonprotective MHC background and weak CD8(+) T-cell responses. Therefore, the contribution of this response to maintaining long-term viral control remains unclear. To address this question, we transiently depleted CD8(+) T cells from five SIV-infected cynomolgus macaques with long-term viral control and weak CD8(+) T-cell responses. Among them, only one carried the protective MHC allele H6. After depletion, four of five controllers experienced a transient rebound of viremia. The return to undetectable viremia was accompanied by only modest expansion of SIV-specific CD8(+) T cells that lacked efficient SIV suppression capacity ex vivo. In contrast, the depletion was associated with homeostatic activation/expansion of CD4(+) T cells that correlated with viral rebound. In one macaque, viremia remained undetectable despite efficient CD8(+) cell depletion and inducible SIV replication from its CD4(+) T cells in vitro. Altogether, our results suggest that CD8(+) T cells are not unique contributors to the long-term maintenance of low viremia in this SIV controller model and that other mechanisms, such as weak viral reservoirs or control of activation, may be important players in control

Antigen uptake and degradation by MDDC.

<p>Dextran uptake <b>(A)</b> and ovalbumine uptake and degradation <b>(B)</b> by MDDC from HDs, HICs and cARTs. Top panels are examples with cells from three representative individuals of each group (light grey is the negative control, blue is one HD, red one HIC and dark grey is a cART). Bottom panels present the summary of all the experiments performed. Each circle represents one individual, and the horizontal lines represent the median ± interquartile values for each group (HD n = 31, HIC n = 23 and cART n = 16).</p

Susceptibility of MDDCs from HIC and HD to HIV-1 infection.

<p><b>(A)</b> Kinetic of HIV-1 BaL replication in MDDC from three HIC (red) and three HD (blue) in three independent and representative examples. p24 production in culture supernatants is represented as the mean ± SD of 3 independent cultures for each individual. <b>(B)</b> Kinetic of HIV-1 Bal production in supernatant of HIC and HD MDDC’s. p24 production in culture supernatants is represented as the mean ± IQR of 34 HD and 42 HIC. (* p<0.05; ** p<0.01; *** p<0.001) <b>(C)</b> Viral production at peak of infection in culture supernatants. Symbols represent the average (n = 3 independent experiments) of p24 values detected in culture supernatants for each subject (HD n = 34 and HIC n = 42). Horizontal lines represent median ± interquartile values for each group.</p

Expression of surface receptors on MDDC.

<p><b>(A)</b> Expression levels of CD4, CXCR4 and CCR5 on MDDC from HDs (n = 11), HICs (n = 12) and cARTs (n = 18). <b>(B)</b> Idem for DC-SIGN, MMR and Syndecan-3 (HDs n = 19, HICs n = 14 and cARTs (n = 13). Each symbol represents one individual and horizontal lines represent the median ± interquartile for each group. * represents p<0.05; ** represents p<0.01. <b>(C)</b> Correlations between the levels of p24 captured by MDDC and their surface expression of MMR, DC-SIGN and Syndecan-3. Each symbol represents data obtained with cells from one patients (n = 29).</p