Terminal NK cell maturation is controlled by concerted actions of T-bet and Zeb2 and is essential for melanoma rejection

Natural killer (NK) cell maturation is a tightly controlled process that endows NK cells with functional competence and the capacity to recognize target cells. Here, we found that the transcription factor (TF) Zeb2 was the most highly induced TF during NK cell maturation. Zeb2 is known to control epithelial to mesenchymal transition, but its role in immune cells is mostly undefined. Targeted deletion of Zeb2 resulted in impaired NK cell maturation, survival, and exit from the bone marrow. NK cell function was preserved, but mice lacking Zeb2 in NK cells were more susceptible to B16 melanoma lung metastases. Reciprocally, ectopic expression of Zeb2 resulted in a higher frequency of mature NK cells in all organs. Moreover, the immature phenotype of Zeb2(-/-) NK cells closely resembled that of Tbx21(-/-) NK cells. This was caused by both a dependence of Zeb2 expression on T-bet and a probable cooperation of these factors in gene regulation. Transgenic expression of Zeb2 in Tbx21(-/-) NK cells partially restored a normal maturation, establishing that timely induction of Zeb2 by T-bet is an essential event during NK cell differentiation. Finally, this novel transcriptional cascade could also operate in human as T-bet and Zeb2 are similarly regulated in mouse and human NK cells

Caractérisation de la détoxification et de l'immunogénicité d'un mutant de la protéine Tat du VIH-1

Parmi les antigènes du VIH-1, Tat représente une cible prometteuse dans le cadre d une formulation vaccinale. Cependant, outre sa fonction de transactivation de la transcription du génome viral, Tat a la capacité de modifier l expression de nombreux gènes cellulaires dont certains impliqués dans la réponse immunitaire. Ainsi, l utilisation de Tat sauvage comme antigène vaccinal est susceptible d induire des effets secondaires pouvant notamment altérer les capacités immunitaires de l organisme vacciné. Dans ce contexte, le but de notre projet a été de caractériser un mutant de Tat ayant perdu les fonctions dérégulatrices de la protéine sauvage, et ayant conservé son immunogénicité. Pour cette étude, nous avons choisi la forme mutée Tat STLA de la protéine virale, comportant quatre substitutions ponctuelles. Les expériences menées in vitro et in vivo ont montré que, contrairement à la protéine virale sauvage, le mutant Tat STLA n'altère pas les fonctions de l'hôte impliquées dans la réponse immunitaire. Par ailleurs, l'antigène Tat STLA a conservé les propriétés immunogènes de la protéine virale sauvage. L'immunisation par Tat STLA induit la production d'anticorps anti-Tat capables de reconnaître la protéine injectée mais aussi la protéine Tat sauvage d'une autre souche de VIH-1. De plus, associée à un adjuvant particulaire, Tat STLA induit une réponse anticorps ciblant un spectre plus large d épitopes de Tat que dans le cas de l injection de Tat sauvage. Ainsi, le candidat Tat STLA, détoxifié pour certaines fonctions de la protéine sauvage et immunogène, s avère être un antigène susceptible d être inclus dans un cocktail vaccinal anti-VIH-1Among HIV-1 proteins, Tat is a promising antigen for consideration as a component of anti-HIV-1 vaccine formulation. Nevertheless, in addition to its role in the replication of the viral genome, this protein is able to affect the expression of several cellular genes that are implicated in immune response. The use of wild-type Tat as a vaccine antigen may thus induce harmful secondary effects in the vaccinated individual. In this context, the main purpose of our proposal was to characterize a mutated form of Tat that had lost the deleterious functions observed for wild-type Tat and kept its immunogenicity. For this study, we choose the STLA Tat mutant, which contains four point substitutions. The experiments conducted in vitro and in vivo showed that in opposition to the wild-type protein, STLA Tat does not affect the host functions implicated in the immune response. Furthermore, the STLA Tat antigen kept the immunogenic properties of the wildtype protein. The immunization with STLA Tat induce the production of anti-Tat antibodies able to recognize the protein injected, but also the wild-type Tat protein from another HIV-1 strain. Moreover, in association with a particulate adjuvant, STLA Tat induces an antibody response targeting a wider spectrum of Tat epitopes than in the case of immunization with wild-type Tat. Therefore, STLA Tat mutant, detoxified for some functions of the wild-type protein and immunogenic, appears to be a promising antigen as part of a cocktail anti-HIV-1 vaccine.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Homéostasie des cellules

Les cellules natural killer (NK) forment une composante importante de l’immunité innée, dédiée à la défense de l’hôte contre les virus et également impliquée dans l’immunosurveillance des tumeurs. Les cellules NK sont distribuées dans tout l’organisme et leur nombre peut augmenter localement au site d’une infection. Elles se développent principalement dans la moelle osseuse et sont perpétuellement renouvelées à partir de ce tissu. Cette revue fait le point sur les facteurs qui régulent l’homéostasie des cellules NK, leur développement, leur différenciation et leur export vers la périphérie. L’accent est mis sur les éléments qui participent à leur homéostasie, en particulier leur renouvellement et leur prolifération. Enfin, nous discutons l’homéostasie des cellules NK dites « mémoire », récemment décrites

Design and characterization of an HIV-1 Tat mutant: Inactivation of viral and cellular functions but not antigenicity

International audienc

Formulation of HIV-1 Tat and p24 antigens by PLA nanoparticles or MF59 impacts the breadth, but not the magnitude, of serum and faecal antibody responses in rabbits

International audienc

UV and X-ray structural studies of a 101-residue long Tat protein from a HIV-1 primary isolate and of its mutated, detoxified, vaccine candidate.

International audienceThe 101-residue long Tat protein of primary isolate 133 of the human immunodeficiency virus type 1 (HIV-1), wt-Tat(133) displays a high transactivation activity in vitro, whereas the mutant thereof, STLA-Tat(133), a vaccine candidate for HIV-1, has none. These two proteins were chemically synthesized and their biological activity was validated. Their structural properties were characterized using circular dichroism (CD), fluorescence emission, gel filtration, dynamic light scattering, and small angle X-ray scattering (SAXS) techniques. SAXS studies revealed that both proteins were extended and belong to the family of intrinsically unstructured proteins. CD measurements showed that wt-Tat(133) or STLA-Tat(133) underwent limited structural rearrangements when complexed with specific fragments of antibodies. Crystallization trials have been performed on the two forms, assuming that the Tat(133) proteins might have a better propensity to fold in supersaturated conditions, and small crystals have been obtained. These results suggest that biologically active Tat protein is natively unfolded and requires only a limited gain of structure for its function

T inflammatory memory CD8 T cells participate to antiviral response and generate secondary memory cells with an advantage in XCL1 production

International audienc