Antiviral immunity, Biotherapy and Vaccines   

  HEADDr. GOUGEON Marie-Lise /
  MEMBERSDr. Héla SAIDI, Post-doc / Marie-Thérèse MELKI, PhD Student / Pauline FORMAGLIO, M2 Training/PhD / Dr. Maxime BATTISTELLA, M2 Training / Dr. POIRIER-BEAUDOUIN Béatrice, IP Engineer / SEFFER Valérie, IP Technician / CAMU Isabelle, Trainee / ROSSIGNOL Evelyne, IP Laboratory assistant / BRANDT Maryse, Secretary

  Annual Report

Our Unit is involved in the study of the interplay between innate and adaptive immunity in chronic viral infections, in order to identify the mechanisms responsible for the lack of immune control of some viruses, such as HIV. In particular, we dissect the modalities of the cross-talk between dendritic cells (DCs) and natural killer (NK) cells, and its impact on the induction of virus-specific immunity. Moreover, we are deeply involved in clinical immunology, participating to phase I/II vaccine and immunotherapy trials, some of them evaluating in healthy volunteers new vaccine candidates, developed at Institut Pasteur, against malaria, shigellosis, anthrax or cancer.

Interplay between innate and adaptive immunity against viruses.

NK-DC cross-talk promotes HIV replication in infected DCs. Role of HMGB1

HIV-1 has evolved ways to exploit DCs, thereby facilitating viral dissemination and allowing evasion of antiviral immunity. The fate of DCs has been found to be extremely dependent on the interaction with autologous NK cells, but the mechanisms by which NK-DC interaction controls viral infections remain unclear. We have investigated the impact of NK-DC cross-talk on maturation and functions of HIV-infected immature DCs. We have shown that activated NK cells are required for the induction of maturation of DCs, whether uninfected or HIV-1-infected, and this process involves HMGB1. However, the cross-talk between HIV-1-infected DCs and activated NK cells is functionally defective, as demonstrated by the strong impairment ofDCs to induce Th1 polarization of naïve CD4 T cells. This is associated with the defective production of IL-12 and IL-18 by infected DCs. Moreover, the crosstalk between activated NK cells and HIV-infected DCs results in a dramatic increase in viral replication and proviral DNA expression in DCs. HMGB1, produced both by NK cells and DCs, has a pivotal role in this process, and inhibition of HMGB1 activity by glycyrrhizin, known to bind specifically to HMGB1, abrogates NK-dependent HIV-1 replication in DCs.

These observations provide evidence for the crucial role of NK-DC cross-talk in promoting viral dissemination, and challenge the question of the in vivo involvement of HMGB1 in the triggering of HIV-1 replication and replenishment of viral reservoirs in AIDS.

HIV-infected DCs are resistant to killing by NK cells. Consequences on viral persistence

NK cells are able to kill virus-infected cells without previous sensitization, and during viral infections they are rapidly recruited to inflamed tissues and meet with immature DC (iDC). NK-DC interaction is bidirectional and may lead to DC maturation and priming for Th1 responses, or may enhance NK-cell cytotoxicity through IL-12 release. We recently addressed the question of the impact of HIV-infection of iDCs on their elimination by NK cells. We found that NK cells are able to uninfected iDCs at high NK:DC ratio. This process is very rapid and DCs display typical features of apoptosis following contacts with aNK cells (Figure). Following HIV infection, iDCs become resistant to NK-dependent killing, and blocking HIV replication with AZT restores DCs sensitivity to aNK-induced cell death. These observations show that following HIV-1 infection, NK-dependent killing of iDCs is altered, leading to the survival of infected cells, thus contributing to viraldissemination.

Immunomonitoring Platform for the evaluation of new vaccine candidates and biotherapies

The objectives are to follow-up innate and adaptive immunity in healthy volunteers or patients involved respectively in the evaluation of new vaccine candidates or in biotherapies. The laboratory is equipped with a FACSCalibur, an ELISPOT device, qRT-PCR, P2+facility, etc…It is involved in the monitoring of specific effector cells using multicolor flow cytometry, intracellular cytokine staining, ELISPOT, or multiplex analyses to quantify the frequency of cells specific for a given antigen and determine the cytokine/chemokine signature of these effectors. Monitoring the antibody response induced by the vaccine candidates with adapted ELISA tests and quantifying the frequency of Ig-producing B cells by ELISPOT is also performed by our laboratory. In addition, we characterize innate effectors, such as NK cells and DC, and analyze their stage of differentiation and their effectors/regulatory functions. This platform has recently evaluated in a phase II trial the effectiveness of an oral vaccine (developed by the laboratory of P. Sansonetti at Institut Pasteur) against Shigella dysenteriae serotype 1, the bacterium responsible for the epidemic form of Shigellosis or bacillary dysentery. This vaccine proved to be well tolerated and to elicit a specific immune response that may confer protection against the most severe symptoms of Shigellosis after a single oral administration (Launay O et al. Vaccine, 2009, 27:1184-91)

Keywords: HIV, adaptive immunity, NK cells, dendritic cells, apoptosis, AIDS, Immunomonitoring, Clinical trials



1- Saïdi H, Melki MT, Gougeon M-L. (2008) HMGB1-dependent triggering of HIV-1 replication and persistence in dendritic cells as a consequence of NK-DC cross-talk. PLoS ONE3(10):e3601 (PMID: 18974890)

2 -Bristeau-Leprince A, Mateo V, Lim A, Magerus-Chatinet A, Solary E, Fischer A, Rieux-Laucat F, Gougeon ML (2008) Human TCR alpha/beta+double-negative T cells in patients with autoimmune lymphoproliferative syndrome express restricted Vbeta TCR diversity and are clonally related to CD8+T cells. J Immunol. 181(1):440-8 (PMID: 18566410)

3- Lecoeur H, Melki M-T, Saïdi H, Gougeon M-L (2008) Analysis of apoptotic pathways by multiparametric flow cytometry: application to HIV infection. Methods Enzymol. 442:51-82 (PMID: 18662564)

4- Perfettini JL, Nardacci R, Bourouba M, Subra F, Gros L, Séror C, Manic G, Rosselli F, Amendola A, Masdehors P, Chessa L, Novelli G, Ojcius DM, Siwicki JK, Chechlinska M, Auclair C, Regueiro JR, de Thé H, Gougeon ML, Piacentini M, Kroemer G (2008) Critical involvement of the ATM-dependent DNA damage response in the apoptotic demise of HIV-1-elicited syncytia. PLoS ONE 3(6):e2458 (PMID: 18560558)

5- Fazilleau N, Bachelez H, Gougeon M-L, Viguier M (2007) Cutting edge: size and diversity of CD4+CD25highFoxp3+ regulatory T cell repertoire in humans: evidence for similarities and partial overlapping with CD4+CD25- T cells. J Immunol.179(6):3412-6 (PMID: 17785774)

Activity Reports 2009 - Institut Pasteur
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