Blockade of IL-33R/ST2 Signaling Attenuates Toxoplasma gondii Ileitis Depending on IL-22 Expression

Oral T. gondii infection (30 cysts of 76K strain) induces acute lethal ileitis in sensitive C57BL/6 (B6) mice with increased expression of IL-33 and its receptor ST2 in the ileum. Here we show that IL-33 is involved in ileitis, since absence of IL-33R/ST2 attenuated neutrophilic inflammation and Th1 cytokines upon T. gondii infection with enhanced survival. Blockade of ST2 by neutralizing ST2 antibody in B6 mice conferred partial protection, while rmIL-33 aggravated ileitis. Since IL-22 expression further increased in absence of ST2, we blocked IL-22 by neutralizing antibody, which abrogated protection from acute ileitis in ST2 deficient mice. In conclusion, severe lethal ileitis induced by oral T. gondii infection is attenuated by blockade of ST2 signaling and may be mediated in part by endogenous IL-22

La mitogaligine, protéine de la mort cellulaire programmée : localisation nucléaire, conséquences de modifications post-traductionnelles potentielles et interaction fonctionnelle avec Mcl-1

Mitogaligin is a protein encoded by galig, a cell death gene. Previously, it has been shown in our laboratory, that this mitochondrial protein induces cell death through an alternative pathway of apoptosis. In this report, we show that mitogaligin can also be addressed to the nucleus where it exhibits also a cytotoxic activity. The nuclear localization signal is not conventional, based on a repetition of amino acids, and function only if the mitochondrial localization signal is inactivated. Thus, the cytotoxicity of mitogaligin could be regulated by its subcellular localization. A large number of apoptotic proteins are regulated by post-translational modifications. Mitogaligin has several potential sites of phosphorylation. Some of them have been mutated to highlight the possible role of phosphorylation in the mitogaligin activity. The wild type protein undergoes one or several proteolytic cuts. Replacement of the threonines 29 and 73 by phospho-mimetic residue decrease mitogaligin proteolysis and also mitogaligin cytotoxicity. The same type of mutation on threonine 38 and serine 39 induces a re-localization of mitogaligin outside mitochondria. The last part of the manuscript focuses on the functional interaction between mitogaligin and Mcl-1, an anti-apoptotic protein of the Bcl-2 family. Coexpression of galig and Mcl-1 significantly reduces galig cell death and overexpression of galig reduces production of endogenous Mcl-1. Therefore, galig could represent a therapeutic target in order to restore cell death in cells overexpressing anti-apoptotic proteins of the Bcl-2 family.La mitogaligine est une protéine codée par le gène galig, un gène inducteur de la mort cellulaire. Préalablement, il a été montré au laboratoire que cette protéine mitochondriale pouvait induire la mort cellulaire selon une voie alternative de l’apoptose. Nos études indiquent que la mitogaligine peut également être adressée au noyau où elle exerce aussi une activité cytotoxique. Le signal d’adressage nucléaire est non conventionnel et lié à une répétition d’acides aminés. Il n’est fonctionnel que si le signal de localisation mitochondriale est aboli. La fonction cytotoxique de la mitogaligine pourrait donc être régulée par son adressage subcellulaire. De nombreuses protéines apoptotiques sont régulées par des modifications post-traductionnelles. La mitogaligine possède différents sites de phosphorylation potentiels. Plusieurs d’entre eux ont été mutés afin de mettre en évidence une éventuelle implication de cette fonction dans l’activité de la mitogaligine. La mitogaligine non mutée subit une ou plusieurs coupures protéolytiques. La mutation des résidus thréonines 29 et 73 en résidus phospho-mimétiques diminue cette protéolyse mais aussi la cytotoxicité de la protéine. Le même type de mutations de la thréonine 38 et la sérine 39 provoque une délocalisation de la protéine. La dernière partie de la thèse s’intéresse plus particulièrement à l’interaction fonctionnelle entre la mitogaligine et Mcl-1, une protéine anti-apoptotique de la famille-Bcl-2. La coexpression de galig et Mcl-1 réduit la mort cellulaire induite par l’expression de galig et la surexpression de galig réduit la production endogène de Mcl-1. Ces résultats montrent une implication de galig dans une voie de régulation de l’apoptose. Galig pourrait donc représenter une cible thérapeutique pour restaurer la mort cellulaire dans des cellules surexprimant des protéines antiapoptotiques de la famille Bcl-2

Mitogaligin, a programmed cell death protein : nuclear localization, post˗translational consequences and functional interaction with Mcl-1

La mitogaligine est une protéine codée par le gène galig, un gène inducteur de la mort cellulaire. Préalablement, il a été montré au laboratoire que cette protéine mitochondriale pouvait induire la mort cellulaire selon une voie alternative de l’apoptose. Nos études indiquent que la mitogaligine peut également être adressée au noyau où elle exerce aussi une activité cytotoxique. Le signal d’adressage nucléaire est non conventionnel et lié à une répétition d’acides aminés. Il n’est fonctionnel que si le signal de localisation mitochondriale est aboli. La fonction cytotoxique de la mitogaligine pourrait donc être régulée par son adressage subcellulaire. De nombreuses protéines apoptotiques sont régulées par des modifications post-traductionnelles. La mitogaligine possède différents sites de phosphorylation potentiels. Plusieurs d’entre eux ont été mutés afin de mettre en évidence une éventuelle implication de cette fonction dans l’activité de la mitogaligine. La mitogaligine non mutée subit une ou plusieurs coupures protéolytiques. La mutation des résidus thréonines 29 et 73 en résidus phospho-mimétiques diminue cette protéolyse mais aussi la cytotoxicité de la protéine. Le même type de mutations de la thréonine 38 et la sérine 39 provoque une délocalisation de la protéine. La dernière partie de la thèse s’intéresse plus particulièrement à l’interaction fonctionnelle entre la mitogaligine et Mcl-1, une protéine anti-apoptotique de la famille-Bcl-2. La coexpression de galig et Mcl-1 réduit la mort cellulaire induite par l’expression de galig et la surexpression de galig réduit la production endogène de Mcl-1. Ces résultats montrent une implication de galig dans une voie de régulation de l’apoptose. Galig pourrait donc représenter une cible thérapeutique pour restaurer la mort cellulaire dans des cellules surexprimant des protéines antiapoptotiques de la famille Bcl-2.Mitogaligin is a protein encoded by galig, a cell death gene. Previously, it has been shown in our laboratory, that this mitochondrial protein induces cell death through an alternative pathway of apoptosis. In this report, we show that mitogaligin can also be addressed to the nucleus where it exhibits also a cytotoxic activity. The nuclear localization signal is not conventional, based on a repetition of amino acids, and function only if the mitochondrial localization signal is inactivated. Thus, the cytotoxicity of mitogaligin could be regulated by its subcellular localization. A large number of apoptotic proteins are regulated by post-translational modifications. Mitogaligin has several potential sites of phosphorylation. Some of them have been mutated to highlight the possible role of phosphorylation in the mitogaligin activity. The wild type protein undergoes one or several proteolytic cuts. Replacement of the threonines 29 and 73 by phospho-mimetic residue decrease mitogaligin proteolysis and also mitogaligin cytotoxicity. The same type of mutation on threonine 38 and serine 39 induces a re-localization of mitogaligin outside mitochondria. The last part of the manuscript focuses on the functional interaction between mitogaligin and Mcl-1, an anti-apoptotic protein of the Bcl-2 family. Coexpression of galig and Mcl-1 significantly reduces galig cell death and overexpression of galig reduces production of endogenous Mcl-1. Therefore, galig could represent a therapeutic target in order to restore cell death in cells overexpressing anti-apoptotic proteins of the Bcl-2 family

Obstacle au traitement de l obésité infantile (enquête auprès des familles défavorisées)

[Introduction] Nous avons recherché des obstacles inhérents aux familles d enfants obèses pouvant mettre en échec les stratégies de lutte contre l épidémie d obésité. [Méthodes] Notre enquête était rétrospective, portait sur les familles d enfants obèses vivant en Z.U.S et ayant arrêté précocement leur suivi pluridisciplinaire dans un centre de santé. Critères d inclusion : âge inférieur à 18 ans, obésité selon la définition internationale. Notre hypothèse était qu il existe des obstacles intra-familiaux économiques, psychologiques et culturels au traitement de l obésité. [Résultats] 54.8% des familles éligibles ont été interrogées. L âge moyen au début du suivi était de 9 ans. 42.6% des enfants ont eu un suivi inférieur à 6 mois. L âge de rebond d adiposité se situait entre 2 et 3 ans pour 55.6% des enfants. 13.6% des chefs de famille étaient inactifs. Deux principales causes ont été retrouvées : un découragement pour 48.5% des familles (IC 95% [36.4% ; 60.6%]) et un manque de soutien familial pour 35.3% d entre elle (IC 95% [24.4% ; 47.9%]). Le problème économique touchait 30.8% des familles (IC 95% [20.5% ; 43.4%]). 91% des familles étaient conscientes des conséquences de l obésité à long terme pour leur enfant mais seulement 66% percevaient une gêne quotidienne liée à leur poids. [Conclusion] Une modification de notre environnement obésogène en évitant de stigmatiser les familles est un point de départ de la lutte contre l obésité infantile.[Introduction] Our goal was to find out the factors that make it difficult for families of obese children to pursue strategies against childhood obesity. [Methods] Our investigation was retrospective. It concerned families of obese children living in a ZUS (=Urban deprived zones) and who had stopped prematurely their follow-up in a health center. Two criteria of inclusion: age less than 18-year-old and obesity according to the international definition. Our hypothesis was that there are economic, psychological and cultural intra-family obstacles to the treatment of obesity. [Results] 54.8 % of the eligible families were questioned. At the beginning of the follow-up the average age was 9 years-old. 42.6 % of the children had less than a six-months-follow up. For 55.6% of the children, the age of adiposity rebound was between their 2nd and 3rd of life. 13.6 % of the heads of the parents did not work. Two main causes were found : discouragement for 48.5 % of families ( 95 % CI [36.4 %; 60.6 %]) and lack of family support for 35.3 % of them ( 95 % CI [24.4 %; 47.9 %]). 30.8 % of families (95 % CI [20.5 %; 43.4 %]) stopped care for economic reasons. 91 % of families were conscious of the consequences of long-term obesity for their child but only 66 % perceived a restriction in their daily activities because of their weight. [Conclusion] To fight childhood obesity the focus should be to modify the environment that leads to obesity rather than stigmatizing families.GRENOBLE1-BU Médecine pharm. (385162101) / SudocSudocFranceF

Apoptotic activity of a nuclear form of mitogaligin, a cell death protein

International audienceGalig, an internal gene to the galectin-3 gene, encodes two proteins and induces cell death in human cells. Mitogaligin, one of these proteins, contains a mitochondrial targeting sequence and promotes the release of cytochrome c into the cytosol. Here, we show that mitogaligin can also localize to nucleus. The nuclear form of mitogaligin induced cell death through a pathway exhibiting typical properties of apoptosis. These observations indicate for the first time that mitogaligin expresses cytotoxic properties not only when addressed to mitochondria but also when targeted to the nucleus

The mitogaligin protein is addressed to the nucleus via a non-classical localization signal

Mitogaligin, a protein encoded by galig, an internal cytotoxic gene of the galectin-3 locus, is mostly a mitochondrial protein. Mitochondrial targeting is due to an already identified mitochondrial localization signal. Interaction of mitogaligin with mitochondria leads to cytochrome c cytosolic leakage and ultimately to cell death. We have previously pointed out that mitogaligin can also be directed to the nucleus when the mitochondrial addressing signal is inactivated, indicating a possible dual intracellular localization of the protein. When expressed in the nucleus, mitogaligin exhibits also apoptotic properties leading to cell death. In this report, we show that nuclear addressing of mitogaligin depends on a sequence differing from classical signals containing basic, lysine or proline-tyrosine rich residues. The signal consists of a long sequence of amino acids residues based on a series of a short repetitive degenerated sequence

A polysaccharide virulence factor of a human fungal pathogen induces neutrophil apoptosis via NK cells.

International audienceAspergillus fumigatus is an opportunistic human fungal pathogen that sheds galactosaminogalactan (GG) into the environment. Polymorphonuclear neutrophils (PMNs) and NK cells are both part of the first line of defense against pathogens. We recently reported that GG induces PMN apoptosis. In this study, we show that PMN apoptosis occurs via a new NK cell-dependent mechanism. Reactive oxygen species, induced by the presence of GG, play an indispensable role in this apoptotic effect by increasing MHC class I chain-related molecule A expression at the PMN surface. This increased expression enables interaction between MHC class I chain-related molecule A and NKG2D, leading to NK cell activation, which in turn generates a Fas-dependent apoptosis-promoting signal in PMNs. Taken together, our results demonstrate that the crosstalk between PMNs and NK cells is essential to GG-induced PMN apoptosis. NK cells might thus play a role in the induction of PMN apoptosis in situations such as unexplained neutropenia or autoimmune diseases

First Report of CD4 Lymphopenia and Defective Neutrophil Functions in a Patient with Amebiasis Associated with CMV Reactivation and Severe Bacterial and Fungal Infections

International audienceWe report the case of a patient with acute necrotizing colitis due to invasive amebiasis associated with CD4 lymphopenia and impaired neutrophil responses. The course of the disease was characterized by CMV reactivation and severe and recurrent bacterial and fungal infections, which might be related to the decreased CD4 T cell count and the impaired functional capacities of neutrophils, respectively. The clinical outcome was positive with normalization of both CD4 cell count and neutrophil functions

Blockade of IL-1R signaling diminishes Paneth cell depletion and Toxoplasma gondii induced ileitis in mice

International audienceInterleukin 1 is a critical inflammatory mediator and involved in host defense to several pathogens. Oral T. gondii infection causes lethal ileitis in C57BL/6 (BL6) mice and serves to investigate the mechanisms of acute intestinal inflammation. Here we show that IL-1 is expressed upon oral T. gondii (76K strain) infection in the small intestine and mediates ileitis as IL-1R1 deficient mice have reduced neutrophil recruitment in the lamina propria, parasite invasion, inflammatory lesions and enhanced survival as compared to BL6 infected control mice. Protection in the absence of IL-1R1 signaling was associated with reduced IFN-γ expression and preserved Paneth cells, while these cells were eliminated in infected BL6 mice. Furthermore, blockade of IL-1 by IL-1β antibody attenuated inflammation in BL6 mice. In conclusion, IL-1 signaling contributes to the inflammatory response with increase IFN-γ expression and Paneth cell depletion upon oral T. gondii infection