Recognition of enteroinvasive Escherichia coli and Shigella flexneri by dendritic cells: distinct dendritic cell activation states

The innate and adaptive immune responses of dendritic cells (DCs) to enteroinvasive Escherichia coli (EIEC) infection were compared with DC responses to Shigella flexneri infection. EIEC triggered DCs to produce interleukin (IL)-10, IL-12 and tumour necrosis factor (TNF)-α, whereas S. flexneri induced only the production of TNF-α. Unlike S. flexneri, EIEC strongly increased the expression of toll like receptor (TLR)-4 and TLR-5 in DCs and diminished the expression of co-stimulatory molecules that may cooperate to inhibit CD4+ T-lymphocyte proliferation. The inflammation elicited by EIEC seems to be related to innate immunity both because of the aforementioned results and because only EIEC were able to stimulate DC transmigration across polarised Caco-2 cell monolayers, a mechanism likely to be associated with the secretion of CC chemokine ligands (CCL)20 and TNF-α. Understanding intestinal DC biology is critical to unravelling the infection strategies of EIEC and may aid in the design of treatments for infectious diseases.

Inhibitory receptors specific for MHC class I educate murine NK cells but not CD8αα intestinal intraepithelial T lymphocytes.

The engagement of inhibitory receptors specific for major histocompatibility complex class I (MHC-I) molecules educates natural killer (NK) cells, meaning the improvement of the response of activation receptors to subsequent stimulation. It is not known whether inhibitory MHC-I receptors educate only NK cells or whether they improve the responsiveness of all cell types, which express them. To address this issue, we analyzed the expression of inhibitory MHC-I receptors on intestinal intraepithelial lymphocytes (iIELs) and show that T-cell receptor (TCR)-αβ CD8αα iIELs express multiple inhibitory receptors specific for MHC-I molecules, including CD94/NKG2A, Ly49A, and Ly49G2. However, the presence of MHC-I ligand for these receptors did not improve the response of iIELs to activation via the TCR. The absence of iIEL education by MHC-I receptors was not related to a lack of inhibitory function of these receptors in iIELs and a failure of these receptors to couple to the TCR. Thus, unlike NK cells, iIELs do not undergo an MHC-I-guided education process. These data suggest that education is an NK cell-specific function of inhibitory MHC-I receptors.

Distinct cytokine profiles of circulating mononuclear cells stimulated with Staphylococcus aureus enterotoxin A in vitro during early and late episodes of chronic osteomyelitis

We investigated the cytokine profile of peripheral mononuclear cells from chronic osteomyelitis (OST) patients following in vitro stimulation with staphylococcal enterotoxin A (SEA). We demonstrate that stimulation with SEA induced prominent lymphocyte proliferation and high levels of tumour necrosis factor (TNF)-α, interleukin (IL)-4 and IL-10 secretion in both OST and non-infected individuals (NI). Even though stimulation with SEA had no impact on IL-6 production in either patient group, the baseline level of IL-6 production by cells from OST patients was always significantly less than that produced by cells from NI. After classifying the osteomyelitic episodes based on the time after the last reactivation event as "early" (1-4 months) or "late" osteomyelitis (5-12 months), we found that increased levels of TNF-α and IL-4 in combination with decreased levels of IL-6 were observed in the early episodes. By contrast, increased levels of IL-10, IL-2 and IL-6 were hallmarks of late episodes. Our data demonstrate that early osteomyelitic episodes are accompanied by an increased frequency of "high producers" of TNF-α and IL-4, whereas late events are characterised by increased frequencies of "high producers" of IL-10, IL-6 and IL-2. These findings demonstrate the distinct cytokine profiles in chronic osteomyelitis, with a distinct regulation of IL-6 production during early and late episodes.

Primary resistance of HIV to antiretrovirals among individuals recently diagnosed at voluntary counselling and testing centres in the metropolitan region of Recife, Pernambuco

Determining the prevalence and type of antiretroviral (ARV) resistance among ARV-naïve individuals is important to assess the potential responses of these individuals to first-line regimens. The prevalence of primary resistance and the occurrence of recent infections among individuals with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) were identified among recently diagnosed patients at five sexually transmitted disease/AIDS testing and counselling centres in the metropolitan region of Recife (RMR), Pernambuco, Brazil, between 2007-2009. One-hundred and eight samples were analysed using the Calypte® BED assay. Males predominated (56%), as did patients aged 31-50 years. Twenty-three percent presented evidence of a recent HIV infection. The median CD4+ T lymphocyte count was 408 cells/mm³ and the median viral load was 3.683 copies/mL. The prevalence of primary resistance was 4.6% (confidence interval 95% = 1-8.2%) based on criteria that excluded common polymorphisms in accordance with the surveillance drug resistance mutation criteria. The prevalence of resistance to non-nucleoside reverse transcriptase, nucleoside/nucleotide reverse transcriptase and protease inhibitors were 3.8%, 1.5% and 0.8%, respectively. Fifty-seven percent of strains were from clade B, 37.7% were clade F and 3.1% were clade C; there were no statistically significant differences with respect to resistance between clades. Recent infection tended to be more common in men (p = 0.06) and in municipalities in the south of the RMR (Jaboatão dos Guararapes and Cabo de Santo Agostinho) (p = 0.046). The high prevalence of recent infection and the high prevalence of non-B strains in this poor Brazilian region merit further attention.

Efficient in vivo induction of CTL by cell-associated covalent H-2Kd-peptide complexes.

A novel procedure is presented describing the induction of antigen-specific cytolytic T lymphocytes (CTL) in vivo, that uses as immunogen syngeneic Concanavalin A stimulated spleen cells expressing H-2Kd (Kd) molecules photocrosslinked with a photoreactive peptide derivative. The Kd restricted Plasmodium berghei circumsporozoite (PbCS) peptide 253-260 (YIPSAEKI) was conjugated with photoreactive iodo-4-azidosalicylic acid (IASA) at the NH2-terminus and with 4-azidobenzoic acid (ABA) at the TCR contact residue Lys259 to make IASA-YIPSAEK(ABA)I. Selective photoactivation of the IASA group allowed specific photoaffinity labeling of cell-associated Kd molecules. Optimal peptide derivative binding to Kd molecules of concanavalin A stimulated spleen cells was obtained upon 4-6 h incubation at 26 degrees C in the presence of human beta 2 microglobulin. Photocrosslinking prevented the rapid dissociation of cell-associated Kd-peptide derivative complexes at 37 degrees C. The photoaffinity labeled cells were injected i.p. into syngeneic recipients. After 10 days, the peritoneal exudate lymphocytes were harvested and in vitro stimulated with peptide derivative pulsed P815 mastocytoma cells. The resulting bulk cultures displayed high cytolytic activity that was specific for IASA-YIPSAEK(ABA)I and YIPSAEK(ABA)I. In contrast, peritoneal exudate lymphocytes from mice inoculated with concanavalin A blasts that were pulsed, but not photocrosslinked, with IASA-YIPSAEK(ABA)I expressed only marginal levels of IASA-YIPSAEK(ABA)I-specific cytolytic activity. This immunization strategy, using neither adjuvants nor potentially hazardous transfected/transformed cells, is safe and should be universally applicable.

Fatal and nonfatal AIDS and non-AIDS events in HIV-1-positive individuals with high CD4 cell counts according to viral load strata.

BACKGROUND: This study compared the incidence of fatal and nonfatal AIDS and non-AIDS events in HIV-positive individuals with a CD4 cell count more than 350  cells/μl among viral load strata: low (<500  copies/ml), intermediate (500-9999.9  copies/ml) and high (≥ 10000  copies/ml). METHODS: Individuals contributed person-years at risk if their most recent CD4 cell count was more than 350  cells/μl. Follow-up was censored if their CD4 cell count dropped below 350  cells/μl. Poisson regression analysis investigated the relationship between viraemia and the incidence of AIDS and non-AIDS events. RESULTS: Three hundred and fifty-four AIDS events occurred during 51 732  person-years of follow-up (PYFU), crude incidence rate of AIDS across the three strata was 0.53, 0.90 and 2.12 per 100 PYFU, respectively. After adjustment, a higher rate of AIDS was observed in individuals with moderate [incidence rate ratio (IRR) 1.44, 1.02-2.05, P = 0.03] and high viraemia had a higher rate (IRR 3.91, 2.89-5.89, P < 0.0001) compared with low viraemia. Five hundred and seventy-two non-AIDS events occurred during 43 784 PYFU, the crude incidence rates were 1.28, 1.52, and 1.38 per 100 PYFU, respectively. After adjustment, particularly for age, region of Europe and starting combination antiretroviral therapy, there was a 61% (IRR 1.61, 1.21-2.14, P = 0.001) and 66% (IRR 1.66, 1.17-2.32, P = 0.004) higher rate of non-AIDS in individuals with intermediate and high viraemia compared with low viraemia. CONCLUSION: In individuals with a CD4 cell count more than 350  cells/μl, an increased incidence of AIDS and a slightly increased incidence of non-AIDS was found in those with uncontrolled viral replication. The association with AIDS was clear and consistent. However, the association with non-AIDS was only apparent after adjustment and no differences were observed between intermediate and high viraemia.

Antigen Receptor Signaling to NF-kappa B via CARMA1, BCL10, and MALT1

The signaling pathway controlling antigen receptor-induced regulation of the transcription factor NF-kappa B plays a key role in lymphocyte activation and development and the generation of lymphomas. Work of the past decade has led to dramatic progress in the identification and characterization of new players in the pathway. Moreover, novel enzymatic activities relevant for this pathway have been discovered, which represent interesting drug targets for immuno-suppression or lymphoma treatment. Here, we summarize these findings and give an outlook on interesting open issues that need to be addressed in the future.

Enhanced T cell activation in Plasmodium falciparum malaria-infected human immunodeficiency virus-1 patients from Mozambique

Human immunodeficiency virus (HIV)-1 infection has an important impact on malaria. Plasmodium falciparum and HIV-1 co-infected patients (Pf/HIV) present with a high degree of anaemia, enhanced parasitaemia and decreased CD4+ T cell counts, which increase the risk of developing severe malaria. In addition, infection with either Pf or HIV-1 alone causes extensive immune activation. Our hypothesis was that lymphocyte activation is potentiated in Pf/HIV co-infected patients, consequently worsening their immunosuppressed state. To test this hypothesis, 22 Pf/HIV patients, 34 malaria patients, 29 HIV/AIDS patients and 10 healthy controls without malaria or HIV/acquired immune deficiency syndrome (AIDS) from Maputo/Mozambique were recruited for this study. As expected, anaemia was most prevalent in the Pf/HIV group. A significant variation in parasite density was observed in the Pf/HIV co-infected group (110-75,000 parasites/µL), although the median values were similar to those of the malaria only patients. The CD4+ T cell counts were significantly lower in the Pf/HIV group than in the HIV/AIDS only or malaria only patients. Lymphocyte activation was evaluated by the percentage of activation-associated molecules [CD38 expression on CD8+ and human leukocyte antigen-DR expression on CD3+ T cells]. The highest CD38 expression was detected in the Pf/HIV co-infected patients (median = 78.2%). The malaria only (median = 50%) and HIV/AIDS only (median = 52%) patients also exhibited elevated levels of these molecules, although the values were lower than those of the Pf/HIV co-infected cases. Our findings suggest that enhanced T-cell activation in co-infected patients can worsen the immune response to both diseases.

CpG-ODN-induced sustained expression of BTLA mediating selective inhibition of human B cells.

BTLA (B- and T-lymphocyte attenuator) is a prominent co-receptor that is structurally and functionally related to CTLA-4 and PD-1. In T cells, BTLA inhibits TCR-mediated activation. In B cells, roles and functions of BTLA are still poorly understood and have never been studied in the context of B cells activated by CpG via TLR9. In this study, we evaluated the expression of BTLA depending on activation and differentiation of human B cell subsets in peripheral blood and lymph nodes. Stimulation with CpG upregulated BTLA, but not its ligand: herpes virus entry mediator (HVEM), on B cells in vitro and sustained its expression in vivo in melanoma patients after vaccination. Upon ligation with HVEM, BTLA inhibited CpG-mediated B cell functions (proliferation, cytokine production, and upregulation of co-stimulatory molecules), which was reversed by blocking BTLA/HVEM interactions. Interestingly, chemokine secretion (IL-8 and MIP1β) was not affected by BTLA/HVEM ligation, suggesting that BTLA-mediated inhibition is selective for some but not all B cell functions. We conclude that BTLA is an important immune checkpoint for B cells, as similarly known for T cells.

Roles of PPARβ and PPARγ in mouse placental development

RESUME Les gènes des PPARs jouent des rôles importants dans la régulation du métabolisme énergétique, lipidique et glucidique. Le présent travail, caractérise et analyse les défauts placentaires responsables de la mort embryonnaire des souris mutantes pour PPARβ et pour PPARγ, entre le jour E9.5 et E10.5. Les placentas issus d'embryons PPARP présentent un sévère retard de croissance, alors que les placentas mutants PPARγ montrent de graves défauts vasculaires. Nous montrons que les placentas issus d'embryons PPARβ-/-, au jour E9.5 présentent une réduction prononcée de la couche de cellules géantes, associée à une diminution des niveaux de protéines exprimées par les cellules géantes, tel que le placenta lactogène-I et la « proliferin ». Par ailleurs, nous montrons que le traitement d'un lignée trophoblastique par un ligand spécifique de PPARP augmente considérablement leur différentiation en cellules géantes. Cette différentiation dépendante de la voie de signalisation P13-kinase, s'accompagne d'une élévation de l'expression de l'ADRP, une protéine de structure associée aux vésicules lipidiques. Ainsi nous démontrons que PPAR5 est un régulateur majeur de la différentiation des cellules géantes, lesquelles sont primordiales aussi bien pour l'établissement de la structure placentaire, que pour la fonction endocrine. Par contre, les placentas PPARγ-/- présentent un défaut de vascularisation. Le niveau d'une protéine anti-angiogénique, la « proliferin-related protein », est très basse et ne peut pas contre-balancer l'élévation normale de la protéine pro-angiogénique « proliferin ». La formation des vaisseaux se trouve alors altérée. Ainsi, PPARγ constitue un régulateur majeur de l'activité anti-angiogénique. En conclusion, ce travail fournit de nouveaux éléments sur le rôle complémentaires de PPARβet PPARγ dans les événements complexes qui régissent le développement placentaire. SUMMARY Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors involved in energy homeostasis and growth. Herein, we characterize the placental defects that cause embryonic lethality around E9.5/E10.5 in PPARβ- and in PPARγ-deficient mouse lines. Most but not all PPARβ-null mutants die around E9.5/E10.5 with severe growth retardation. The placentas from PPARβ-/- embryos at E9.5 exhibit a strongly reduced giant cell layer, associated with reduced levels of proteins expressed by giant cells such as Placental lactogen-I and Proliferin. Ectopic treatment of a rat trophoblast cell line with PPARβ ligand markedly accelerated PI3 kinase-dependent giant cell differentiation. In addition, we demonstrate that ADRP, a pen-related lipid droplet-bound protein, is up-regulated by PPARβ in differentiated Rcho-1 cells. These results indicate that PPARβ is a crucial regulator of the differentiation secondary giant cells, which play a major role in the establishment of the placental structure as well as an important endocrine function. In contrast, the main alteration of the PPARγ-null placentas concerns the vasculogenesis. We show that in these placentas, the level of the anti-angiogenic proliferin-related protein is very low, and cannot balance the normal elevation of the pro-angiogenic proliferin expression, leading to the defective placental vessel formation. Consistently, the dramatic increase of PPARγ expression in late stage of gestation in wild-type mice is likely a major regulator of the anti-angiogenic activity, particularly important at the end of the pregnancy. This work emphasizes the important and complementary roles of PPARβ and PPARγ in mouse placental development and provides new tools for understanding the complex regulatory events that governs placental development and function. Understanding the function of PPARβ and PPARγ are of crucial interest with respect to human placental development and associated pathologies.

In vivo expansion of T reg cells with IL-2-mAb complexes: induction of resistance to EAE and long-term acceptance of islet allografts without immunosuppression.

Via a transcription factor, Foxp3, immunoregulatory CD4(+)CD25(+) T cells (T reg cells) play an important role in suppressing the function of other T cells. Adoptively transferring high numbers of T reg cells can reduce the intensity of the immune response, thereby providing an attractive prospect for inducing tolerance. Extending our previous findings, we describe an in vivo approach for inducing rapid expansion of T reg cells by injecting mice with interleukin (IL)-2 mixed with a particular IL-2 monoclonal antibody (mAb). Injection of these IL-2-IL-2 mAb complexes for a short period of 3 d induces a marked (&gt;10-fold) increase in T reg cell numbers in many organs, including the liver and gut as well as the spleen and lymph nodes, and a modest increase in the thymus. The expanded T reg cells survive for 1-2 wk and are highly activated and display superior suppressive function. Pretreating with the IL-2-IL-2 mAb complexes renders the mice resistant to induction of experimental autoimmune encephalomyelitis; combined with rapamycin, the complexes can also be used to treat ongoing disease. In addition, pretreating mice with the complexes induces tolerance to fully major histocompatibility complex-incompatible pancreatic islets in the absence of immunosuppression. Tolerance is robust and the majority of grafts are accepted indefinitely. The approach described for T reg cell expansion has clinical potential for treating autoimmune disease and promoting organ transplantation.

Role of the epithelial sodium channel (ENaC) and its positive regulator, the channel-activating protease 1 (CAP1) in skin

Summary: The mammalian epidermis is a pluristratified epithelium composed of 90% keratinocytes, and its main function is to serve as barrier for the body. The epithelial sodium channel (ENaC), formed by three homologous subunits α, β and γ is found in a variety of epithelia including epidermis. Previous studies showed that ENaC modulates different aspects of epidermal differentiation, such as synthesis of differentiation-specific proteins and lipid secretion. ENaC plays also a critical role in sodium homeostasis of renal and pulmonary epithelia, and its activity is thereby well controlled by hormones and non-hormonal factors, such as the serine protease CAP1 (channel-activating protease 1), also termed prostasin encoded by Prss8 gene. Serine proteases are proteolytic enzymes involved in numerous physiological and pathological processes in the epidermis. In order to evaluate the role of β and γENaC in epidermis, we analyzed the skin phenotype of β and γENaC null mutant (βENaC-/- and γENaC-/-) mice in comparison with the phenotype of αENaC-deficient mice. Furthermore, keratin14-specific CAP1-deficient mice (Prss8lox/Δ /K14-Cre) were generated in order to unveil the role of the serine protease CAP1 in epidermal development and function. This study reveals that the skin phenotype of βENaC and γENaC null mutant mice is less severe than the one of αENaC-deficient mice. However, all these mice present a common premature lipid secretion in the mid-granular layer of the epidermis. Further, the composition of the lipids of the stratum corneum in αENaC-deficient mice is strongly altered, suggesting that epidermal barrier function is compromised. K14-specific CAP1-deficient newborn mice are born at the expected Mendelian ratio, but die soon after birth, showing that CAP1 is required for postnatal survival. The epidermis of these mice exhibits striking malformations of the stratum corneum showing hyperkeratosis. These defects seriously affect both inward and outward epidermal barrier function, leading to rapid and fatal dehydration. As in αENaC-deficient mice, the lipid composition of the stratum corneum of K14-specific CAP1-deficient mice is disturbed. Furthermore, lack of CAP1 leads to the selective loss of filaggrin monomers, important for keratins aggregation and skin moisturization, and to an increased of aberrant profilaggrin precursors. In conclusion, both ENaC and CAP1 expression in the epidermis are crucial for keratinocyte differentiation processes and/or barrier function. Since the abnormalities in K14-specific CAP1-deficient mice resemble key features of human skin ichthyosis, in particular Harlequin ichthyosis, the study of ENaC and CAP1 mutant mice might allow new insights into mechanisms underlying skin diseases. Résumé: L'épiderme des mammifères est un épithélium pluristratifié, protégeant le corps contre les perturbations extérieures et la déshydratation. Le canal épithélial à sodium (ENaC), formé de trois sous-unités α, β et γ, est exprimé dans de nombreux épithélia, comme l'épiderme. Des études ont montré que l'absence de la sous-unité αENaC modulait différents aspects de la différenciation des kératinocytes de l'épiderme, comme la synthèse de protéines spécifiques ou la sécrétion de lipides dans la couche granulaire de l'épiderme. ENaC joue également un rôle crucial dans l'homéostasie du sodium dans les épithélia électriquement étanches, comme l'épithélium rénal ou pulmonaire. L'activité de ENaC est par conséquent finement régulée, en partie par des hormones, mais aussi par des facteurs non-hormonaux, telle que la sérine protéase CAP1 (« channel-activating protease 1 >>) (nommée également prostasine et codée par le gène Prss8). Le but de ce travail a donc été d'étudier le rôle des sous-unités β et γENaC dans l'épiderme en comparaison avec celui de la sous-unité α en utilisant des souris mutantes βENaC-/- et γENaC-/-. Dans un deuxième temps, le phénotype d'une souris chez qui CAP1 a été spécifiquement invalidé dans l'épiderme (Prsslox/Δ/K14-Cre) a été analysé, dans le but de mettre en évidence le rôle de cette protéase dans l'épiderme. Comme déjà montré pour les souris αENaC-/-, la sécrétion des lipides dans la couche granulaire de l'épiderme des souris βENaC-/- et γENaC-/- est prématurée. Cependant, l'hyperplasie et l'expression anormale des protéines marqueurs de la différenciation présents chez les souris αENaC-/- n'ont pas été observés dans l'épiderme des souris βENaC-/- et γENaC-/-. La composition lipidique de la couche cornée des souris αENaC-/- est fortement altérée suggérant que la fonction de barrière de l'épiderme de ces souris est compromise. Les souris mutantes CAP1 ont quant à elles révélé des malformations sévères de leur couche cornée, affectant la fonction de barrière de leur épiderme et conduisant à la mort de ces souris par déshydratation quelques jours après leur naissance. De plus, la composition en lipides de la couche cornée ainsi que la taille des cellules cornées, les cornéocytes, de ces souris sont modifiées par rapport aux souris contrôles. L'invalidation de la protéine CAP1 dans l'épiderme conduit aussi à la perte de la filaggrine, une protéine cruciale pour l'agrégation des kératines dans la couche cornée et le maintien du niveau d'hydratation de la peau, et à l'accumulation de ses précurseurs. En conclusion, l'expression de ENaC et de CAP1 est cruciale pour la différenciation de l'épiderme et/ou sa fonction de barrière. De plus, le phénotype des souris mutantes CAP1 présente des caractéristiques qui ressemblent à celles observées dans certaines pathologies humaines cutanées, comme l'ichthyose d'Harlequin. L'étude des souris mutantes ENaC et CAP1 pourrait donc apporter de nouvelles connaissances dans les mécanismes impliqués dans l'ichthyose d'Harlequin ou d'autres maladies de la peau chez l'homme. Résumé tout public: La peau est le plus grand organe vital du corps humain. Sa fonction principale est de protéger le corps comme une barrière, contre les agressions extérieures et la déshydratation. De nombreuses maladies de la peau résultent d'une perte de fonction de cette barrière. Bien que les pathologies cutanées soient très bien décrites, leur cause génétique n'est en général pas encore connue. La souris est alors un modèle de choix pour la recherche fondamentale. En effet, grâce aux progrès récents de la science, le génome de la souris peut aujourd'hui être modifié dans le but d'étudier le rôle de nombreuses protéines. Dans différents organes, comme le rein et le poumon, le canal épithélial à sodium (ENaC), composé de trois sous-unités protéiques homologues (α, β, et γ), joue un rôle essentiel dans la réabsorption du sodium. L'activité de ENaC est régulée par de nombreux facteurs hormonaux et non-hormonaux, telle que la protéase CAP1 (« channel-activating protease 1 »). L'invalidation de la sous-unité αENaC chez la souris a permis de montrer que dans la peau, le canal ENaC est impliqué dans la différenciation des cellules de l'épiderme et la croissance des poils. Durant ce travail, le phénotype des souris chez qui la protéine βENaC, γENaC ou CAP1 a été invalidée (souris mutantes), a été étudié dans le but de mieux comprendre le rôle des sous-unités du canal ENaC et de son régulateur CAP1 dans la peau. Les résultats de ce projet ont montré que les souris mutantes βENaC et γENaC présentent un épiderme anormal avec une synthèse prématurée de lipides dans la couche granulaire, suggérant l'implication de ENaC dans la fonction de barrière de la peau. De plus, quand CAP1 est invalidé de manière totale chez les souris, le développement embryonnaire est perturbé et ces souris meurent avant la naissance. CAP1 a donc été invalidé spécifiquement dans l'épiderme des souris. Ces souris mutantes « épiderme-spécifique » naissent normalement, mais meurent peu après la naissance de déshydratation. La couche superficielle de l'épiderme, appelée couche cornée, de ces souris est malformée et ne confère plus à la peau sa fonction de barrière. De plus, les composants de la couche cornée, les cellules cornées entourées de lipides, sont sévèrement altérés. Le phénotype de ces souris ressemble aux caractéristiques présentes chez les patients atteints d'ichthyoses, en particulier l'ichthyose d'Harlequin. En conclusion, le canal ENaC ainsi que son régulateur CAP1 jouent un rôle clé dans les processus de différenciation de l'épiderme et/ou de sa fonction de barrière. De plus, les souris mutantes pour CAP1 et ENaC se révéleront peut-être comme des modèles appropriés dans l'étude de l'ichthyose d'Harlequin ou d'autres maladies cutanées.

A multicenter study confirms CD226 gene association with systemic sclerosis-related pulmonary fibrosis.

INTRODUCTION CD226 genetic variants have been associated with a number of autoimmune diseases and recently with systemic sclerosis (SSc). The aim of this study was to test the influence of CD226 loci in SSc susceptibility, clinical phenotypes and autoantibody status in a large multicenter European population. METHODS A total of seven European populations of Caucasian ancestry were included, comprising 2,131 patients with SSc and 3,966 healthy controls. Three CD226 single nucleotide polymorphisms (SNPs), rs763361, rs3479968 and rs727088, were genotyped using Taqman 5'allelic discrimination assays. RESULTS Pooled analyses showed no evidence of association of the three SNPs, neither with the global disease nor with the analyzed subphenotypes. However, haplotype block analysis revealed a significant association for the TCG haplotype (SNP order: rs763361, rs34794968, rs727088) with lung fibrosis positive patients (PBonf = 3.18E-02 OR 1.27 (1.05 to 1.54)). CONCLUSION Our data suggest that the tested genetic variants do not individually influence SSc susceptibility but a CD226 three-variant haplotype is related with genetic predisposition to SSc-related pulmonary fibrosis.

Gender-Specific Effects of Genetic Variants within Th1 and Th17 Cell-Mediated Immune Response Genes on the Risk of Developing Rheumatoid Arthritis.

The present study was conducted to explore whether single nucleotide polymorphisms (SNPs) in Th1 and Th17 cell-mediated immune response genes differentially influence the risk of rheumatoid arthritis (RA) in women and men. In phase one, 27 functional/tagging polymorphisms in C-type lectins and MCP-1/CCR2 axis were genotyped in 458 RA patients and 512 controls. Carriers of Dectin-2 rs4264222T allele had an increased risk of RA (OR = 1.47, 95%CI 1.10-1.96) whereas patients harboring the DC-SIGN rs4804803G, MCP-1 rs1024611G, MCP-1 rs13900T and MCP-1 rs4586C alleles had a decreased risk of developing the disease (OR = 0.66, 95%CI 0.49-0.88; OR = 0.66, 95%CI 0.50-0.89; OR = 0.73, 95%CI 0.55-0.97 and OR = 0.68, 95%CI 0.51-0.91). Interestingly, significant gender-specific differences were observed for Dectin-2 rs4264222 and Dectin-2 rs7134303: women carrying the Dectin-2 rs4264222T and Dectin-2 rs7134303G alleles had an increased risk of RA (OR = 1.93, 95%CI 1.34-2.79 and OR = 1.90, 95%CI 1.29-2.80). Also five other SNPs showed significant associations only with one gender: women carrying the MCP-1 rs1024611G, MCP-1 rs13900T and MCP-1 rs4586C alleles had a decreased risk of RA (OR = 0.61, 95%CI 0.43-0.87; OR = 0.67, 95%CI 0.47-0.95 and OR = 0.60, 95%CI 0.42-0.86). In men, carriers of the DC-SIGN rs2287886A allele had an increased risk of RA (OR = 1.70, 95%CI 1.03-2.78), whereas carriers of the DC-SIGN rs4804803G had a decreased risk of developing the disease (OR = 0.53, 95%CI 0.32-0.89). In phase 2, we genotyped these SNPs in 754 RA patients and 519 controls, leading to consistent gender-specific associations for Dectin-2 rs4264222, MCP-1 rs1024611, MCP-1 rs13900 and DC-SIGN rs4804803 polymorphisms in the pooled sample (OR = 1.38, 95%CI 1.08-1.77; OR = 0.74, 95%CI 0.58-0.94; OR = 0.76, 95%CI 0.59-0.97 and OR = 0.56, 95%CI 0.34-0.93). SNP-SNP interaction analysis of significant SNPs also showed a significant two-locus interaction model in women that was not seen in men. This model consisted of Dectin-2 rs4264222 and Dectin-2 rs7134303 SNPs and suggested a synergistic effect between the variants. These findings suggest that Dectin-2, MCP-1 and DC-SIGN polymorphisms may, at least in part, account for gender-associated differences in susceptibility to RA.

TLR 2 modulates inflammation in zymosan-induced arthritis in mice

Résumé L'objectif de cette étude est la compréhension des mécanismes sous-jacents à l'inflammation articulaire dans un modèle murin d'arthrite induite par le zymosan (ZIA). En particulier, la participation du récepteur Toll 2 (TLR2) et du complément C3 a été recherchée. L'inflammation articulaire a été quantifiée par l'accumulation de Technetium (Tc) in vivo, et par histologie des articulations arthritiques. Les réponses humorales et cellulaires induites par le zymosan ont été quantifiées par la prolifération lymphocytaire in vitro et par la mesure de la production d'anticorps dirigés contre le zymosan in vivo. L'inflammation associée à l'arthrite induite au zymosan est, d'après le Tc-uptake, d'aspect biphasique, avec un pic après 1 jour, puis une deuxième phase plus tardive. La deuxième phase persiste jusqu'au 24 ème jour et est associée au développement d'une immunité spécifique contre le zymosan. Les souris déficientes pour TLR-2 présentent une réduction significative de l'inflammation articulaire précoce (jour 1) et tardive (jour 24), ainsi qu'une nette diminution de l'infiltrat inflammatoire dans la membrane synoviale. De plus, la prolifération de cellules du ganglion lymphatique ainsi que le taux d'IgG dirigés contre le zymosan sont diminués de façon significative après 25 jour d'arthrite chez les souris déficientes en TLR2 par rapport aux souris sauvages contrôles. Par contraste, chez les souris déficientes pour C3 on n'observe pas de différence dans l'uptake de Tc ou le scoring histologique par rapport à la lignée sauvage. Ces résultats montrent que l'arthrite induite au zymosan n'est pas seulement un modèle d'inflammation aigue, mais que l'inflammation synoviale persiste même après 25 jours. Ce modèle implique à la fois des mécanismes d'immunité innée et acquise. Le signalling via TLR 2 semble jouer in rôle dans l'immunité au zymosan et pourrait être responsable de la nature biphasique de ce modèle d'arthrite. Abstract The interplay between the innate and acquired immune systems in chronic inflammation is not well documented. We have investigated the mechanisms of inflammation in murine zymosan-induced arthritis (ZIA) in the light of recent data on the roles of Toll-like receptor 2 (TLR2) and Dentin-1 in the activation of monocyte/macrophages by zymosan. The severity of inflammation, joint histology, lymphocyte proliferation and antibody production in response to zymosan were analyzed in mice deficient in TLR2 and complement C3, and the effects of Dentin-1 inhibition by laminarin were studied. In comparison with wild-type animals, TLR2-deficient mice showed a significant decrease in the early (day 1) and late phases (day 24) of joint inflammation. C3-deficient mice showed no differences in technetium uptake or histological scoring. TLR2-deficient mice also showed a significant decrease in lymph node cell proliferation in response to zymosan and a lower IgG antibody response to zymosan at day 25 in comparison with wild-type controls, indicating that TLR2 signalling has a role in the development of acquired immune responses to zymosan. Although laminarin, a soluble β-glucan, was able to significantly inhibit zymosan uptake by macrophages in vitro, it had no effect on ZIA in vivo. These results show that ZIA is more prolonged than was originally described and involves both the innate and acquired immune pathways. C3 does not seem to have a major role in this model of joint inflammation.