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Background Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TH17 cells may be beneficial in psoriasis. We found that Cav1.4, encoded by CACNA1F, was the only Cav1 calcium channel expressed in TH17 cells. Objective We sought to investigate the role of Cav1.4 expression in early TH17-activation events and effector functions, as well as its association with TH17 signature genes in lesional psoriatic (LP) skins. Methods Transcriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. Cav1 inhibitor and/or shRNA lentivectors were used to assess the contribution of Cav1.4 in TH17 activation and effector functions in a 3-dimensional skin reconstruction model. Results CACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4+ and CD4− cells from LP biopsies. Nicardipine, a Cav1 channel antagonist, markedly reduced inflammatory cytokine production by TH17 cells from blood or LP skin. This was associated with decreased TCR-induced early calcium events at cell membrane and proximal signaling events. The knockdown of Cav1.4 in TH17 cells impaired cytokine production. Finally, Cav1 inhibition reduced the expression of the keratinocyte genes characteristic of TH17-mediated psoriasis inflammation in human skin equivalents. Conclusions Cav1.4 channels promote TH17-cell functions both at the periphery and in inflammatory psoriatic skin.

Plasmacytoid dendritic cells (pDCs) express TLR7, a ssRNA-sensor encoded on the X chromosome, which escapes X chromosome inactivation (XCI) in females. pDCs are specialized in the production of type 1 interferons (IFN-I) through TLR7 activation which mediates both immune cell activation and also reactivation of latent HIV-1. The effect of HIV-1 infection in women under antiretroviral therapy (ART) on pDC functional responses remains poorly understood. Here, we show that pDCs from HIV/ART women exhibit exacerbated production of IFN-α and TNF-α compared with uninfected controls (UC) upon TLR7 activation. Because TLR7 can escape XCI in female pDCs, we measured the contribution of TLR7 allelic expression using SNP haplotypic markers to rigorously tag the allele of origin of TLR7 gene at single-cell resolution. Herein, we provide evidence that the enhanced functional response of pDCs in HIV/ART women is associated with higher transcriptional activity of the TLR7 locus from both X chromosomes, rather than differences in the frequency of TLR7 biallelic cells. These data reinforce the interest in targeting the HIV-1 reservoir using TLR7 agonists in women.

Plasmacytoid dendritic cells (pDCs) express TLR7, a ssRNA-sensor encoded on the X chromosome, which escapes X chromosome inactivation (XCI) in females. pDCs are specialized in the production of type 1 interferons (IFN-I) through TLR7 activation which mediates both immune cell activation and also reactivation of latent HIV-1. The effect of HIV-1 infection in women under antiretroviral therapy (ART) on pDC functional responses remains poorly understood. Here, we show that pDCs from HIV/ART women exhibit exacerbated production of IFN-α and TNF-α as compared to uninfected controls (UC) upon TLR7-activation. Because TLR7 can escape XCI in female pDCs, we measured the contribution of TLR7 allelic expression using SNP haplotypic markers to rigorously tag the allele of origin of TLR7 gene at single cell resolution. Herein, we provide evidence that the functional reprogramming of pDCs in HIV/ART women is associated with enhanced transcriptional activity of the TLR7 locus from both X chromosomes, rather than differences in the frequency of TLR7 bi-allelic cells. These data reinforce the interest in targeting the HIV-1 reservoir using TLR7 agonists in women.

Serological tests are important for understanding the physiopathology and following the evolution of the Covid-19 pandemic. Assays based on flow cytometry (FACS) of tissue culture cells expressing the spike (S) protein of SARS-CoV-2 have repeatedly proven to perform slightly better than the plate-based assays ELISA and CLIA (chemiluminescent immuno-assay), and markedly better than lateral flow immuno-assays (LFIA).Here, we describe an optimized and very simple FACS assay based on staining a mix of two Jurkat cell lines, expressing either high levels of the S protein (Jurkat-S) or a fluorescent protein (Jurkat-R expressing m-Cherry, or Jurkat-G, expressing GFP, which serve as an internal negative control). We show that the Jurkat-S&R-flow test has a much broader dynamic range than a commercial ELISA test and performs at least as well in terms of sensitivity and specificity. Also, it is more sensitive and quantitative than the hemagglutination-based test HAT, which we described recently. The Jurkat-flow test requires only a few microliters of blood; thus, it can be used to quantify various Ig isotypes in capillary blood collected from a finger prick. It can be used also to evaluate serological responses in mice, hamsters, cats and dogs. Whilst the Jurkat-flow test is ill-suited and not intended for clinical use, it offers a very attractive solution for laboratories with access to tissue culture and flow cytometry who want to monitor serological responses in humans or in animals, and how these relate to susceptibility to infection, or re-infection, by the virus, and to protection against Covid-19.NoteThis manuscript has been refereed by Review Commons, and modified thanks to the comments and suggestions from two referees. Those comments, and our replies, are provided at the end of the manuscript’s pdf, and can also be accessed by clicking on the box with a little green number found just above the “Abstract “ tab in the medRXiv window.

Tissue-resident innate lymphoid cells (ILCs) regulate tissue homeostasis, protect against pathogens at mucosal surfaces and are key players at the interface of innate and adaptive immunity. How ILCs adapt their phenotype and function to environmental cues within tissues remains to be fully understood. Here, we show that Mycobacterium tuberculosis infection alters the phenotype and function of immature lung ILC2 toward a protective interferon-γ-producing ILC1-like population. This differentiation is controlled by type 1 cytokines and is associated with a glycolytic program involving the transcription factor HIF1α. Collectively, our data reveal how tissue-resident ILCs adapt to type 1 inflammation toward a pathogen tailored immune response.

Toll-like receptor 7 (TLR7) triggers antiviral immune responses through its capacity to recognize single-stranded RNA. Proteolytic cleavage of TLR7 protein is required for its functional maturation in the endosomal compartment. Structural studies demonstrated that the N- and C-terminal domains of TLR7 are connected and involved in ligand binding after cleavage. Hydroxychloroquine (HCQ), an antimalarial drug, has been studied for its antiviral effects. HCQ increases pH in acidic organelles and has been reported to potently inhibit endosomal TLR activation. Whether HCQ can prevent endogenous TLR7 cleavage in primary immune cells, such as plasmacytoid dendritic cells (pDCs), had never been examined. Here, using a validated anti-TLR7 antibody suitable for biochemical detection of native TLR7 protein, we show that HCQ-treatment of fresh PBMCs, CAL-1 leukemic and primary human pDCs inhibits TLR7 cleavage and results in accumulation of full-length protein. As a consequence, we observe an inhibition of pDC activation in response to TLR7 stimulation with synthetic ligands and viruses including inactivated SARS-CoV2, which we show herein activates pDCs through TLR7-signaling. Together, our finding suggests that the major pathway by which HCQ inhibits ssRNA-sensing by pDCs may rely on its capacity to inhibit endosomal acidification and the functional maturation of TLR7 protein.

Tissue-resident innate lymphoid cells (ILCs) regulate tissue homeostasis, protect against pathogens at mucosal surfaces, and are key players at the interface of innate and adaptive immunity. How ILCs adapt their phenotype and function to environmental cues within tissues remains to be fully understood. Here, we show that Mycobacterium tuberculosis (Mtb) infection alters the phenotype and function of lung IL-18Rα

International audience; Background Voltage-gated calcium (Ca(v)1) channels contribute to T-lymphocyte activation. Ca(v)1.2 and Ca(v)1.3 channels are expressed in Th2 cells but their respective roles are unknown, which is investigated herein. Methods We generated mice deleted for Ca(v)1.2 in T cells or Ca(v)1.3 and analyzed TCR-driven signaling. In this line, we developed original fast calcium imaging to measure early elementary calcium events (ECE). We also tested the impact of Ca(v)1.2 or Ca(v)1.3 deletion in models of type 2 airway inflammation. Finally, we checked whether the expression of both Ca(v)1.2 and Ca(v)1.3 in T cells from asthmatic children correlates with Th2-cytokine expression. Results We demonstrated non-redundant and synergistic functions of Ca(v)1.2 and Ca(v)1.3 in Th2 cells. Indeed, the deficiency of only one channel in Th2 cells triggers TCR-driven hyporesponsiveness with weakened tyrosine phosphorylation profile, a strong decrease in initial ECE and subsequent reduction in the global calcium response. Moreover, Ca(v)1.3 has a particular role in calcium homeostasis. In accordance with the singular roles of Ca(v)1.2 and Ca(v)1.3 in Th2 cells, deficiency in either one of these channels was sufficient to inhibit cardinal features of type 2 airway inflammation. Furthermore, Ca(v)1.2 and Ca(v)1.3 must be co-expressed within the same CD4(+) T cell to trigger allergic airway inflammation. Accordingly with the concerted roles of Ca(v)1.2 and Ca(v)1.3, the expression of both channels by activated CD4(+) T cells from asthmatic children was associated with increased Th2-cytokine transcription. Conclusions Thus, Ca(v)1.2 and Ca(v)1.3 act as a duo, and targeting only one of these channels would be efficient in allergy treatment.

Voltage-gated calcium (CaWe generated mice deleted for CaWe demonstrated non-redundant and synergistic functions of CaThus, Ca

Type-17 inflammation characterizes psoriasis, a chronic skin disease. Because several inflammatory cytokines contribute to psoriasis pathogenesis, inhibiting the simultaneous production of these cytokines in TWe sought to investigate the role of CaTranscriptional gene signatures associated with CACNA1F expression were examined in LP skins by RT-PCR and in situ hybridization. CaCACNA1F expression correlated with inflammatory cytokine expression that characterizes LP skins and was preferentially associated with RORC expression in CD4Ca

International audience; Les femmes représentent 80 % des personnes affectées par les maladies auto-immunes. Le rôle des hormones sexuelles sur la réponse immune est bien documenté, résultant en particulier de la fixation des œstrogènes sur leurs récepteurs nucléaires exprimés par nombre de cellules immunitaires. En plus de l’action des hormones stéroïdes sexuelles, des preuves s’accumulent en faveur d’un rôle des facteurs génétiques liés au chromosome X. Chez la femme, suite aux mécanismes d’inactivation de l’X (ICX), un des deux chromosomes X est inactivé de manière aléatoire, générant ainsi une mosaïque de cellules exprimant des gènes de l’X hérités, soit de la mère, soit du père portés par l’X actif. Cependant, 15 à 23 % de gènes de l’X inactif (Xi) échappent à l’ICX, contribuant à l’émergence d’une autre population hétérogène de cellules exprimant le même gène à partir des deux chromosomes X. Parmi ces gènes, certains gènes de l’immunité ont été récemment identifiés. Si la contribution directe de ce mécanisme de dosage génétique dans la susceptibilité à l’auto-immunité reste encore à être explorée en profondeur, le mosaïsme cellulaire résultant de l’ICX et de l’échappement à l’ICX induit une plasticité fonctionnelle unique au sein des cellules immunitaires de femmes.

Tissue-resident innate lymphoid cells (ILCs) regulate tissue homeostasis and protect against pathogens at mucosal surfaces and are key players at the interface of innate and adaptive immunity. How ILCs adapt their phenotype and function to environmental cues in their tissue of residence remains to be fully understood. Here we show that Mycobacterium tuberculosis infection alters the biology of lung ILCs and, in particular, induces the emergence of a non-classical, protective, interferon-γ-producing ILC1-like population. Adoptive transfer, fate-mapping and in vitro differentiation experiments revealed that ILC1-like cells originate from immature ILC2 rather than from mature ILC2. This plasticity is controlled by type 1 cytokines and a glycolytic program involving the transcription factor HIF1α. Collectively, our data reveal how tissue-resident ILCs adapt to their inflammatory and metabolic environment to undergo phenotypic and functional changes toward a pathogen-adapted immune response.

Asthma and allergy: what about the differences between men and women? Allergic asthma is a chronic pulmonary disease characterized by bronchial hyper responsiveness, hyper production of mucus and remodeling of the airways. Asthma, which often begins before the age of 5, is the most common chronic disease in children and affects approximately 10% of the population in affluent societies. As it is the case for many allergic diseases, asthma affects men and women differently. In childhood, pathology is more common in boys, but this trend reverses at puberty, suggesting a regulation by sex hormones. In this review, we summarize the current knowledge on how sex hormones impact allergic inflammation and particularly describe the protective actions of androgens on the development and function of key immune cell subsets involved in allergic responses.Asthme et allergie : qu’en est-il des différences entre les hommes et les femmes ? L’asthme allergique est une maladie inflammatoire chronique des voies aériennes caractérisée par une hyperréactivité bronchique, une hyperproduction de mucus et un remodelage des voies aériennes. L’asthme, qui débute souvent avant l’âge de 5 ans, est la maladie chronique la plus fréquente chez l’enfant et touche environ 10 % de la population dans les pays industrialisés. Comme c’est le cas pour de nombreuses maladies allergiques, à l’âge adulte l’asthme touche préférentiellement les femmes comparées aux hommes. Paradoxalement, la pathologie est plus fréquente chez les garçons dans l’enfance, mais ce dimorphisme s’inverse à la puberté, suggérant une régulation par les hormones sexuelles. Dans cette mise au point, nous résumerons les données de la littérature concernant le biais de sexe dans l’asthme allergique et les données expérimentales en faveur d’un rôle protecteur des androgènes, sur le développement et la fonction de cellules immunitaires clés dans le développement des réponses allergiques.

International audience; Type I IFN (IFN-I) production by plasmacytoid DCs (pDCs) occurs during acute HIV-1 infection in response to TLR7 stimulation, but the role of pDC-derived IFN-I in controlling or promoting HIV-1 infection is ambiguous. We report here a sex-biased interferogenic phenotype for a frequent single-nucleotide polymorphism of human TLR7, rs179008, displaying an impact on key parameters of acute HIV-1 infection. We show allele rs179008 T to determine lower TLR7 protein abundance in cells from women, specifically — likely by diminishing TLR7 mRNA translation efficiency through codon usage. The hypomorphic TLR7 phenotype is mirrored by decreased TLR7-driven IFN-I production by female pDCs. Among women from the French ANRS PRIMO cohort of acute HIV-1 patients, carriage of allele rs179008 T associated with lower viremia, cell-associated HIV-1 DNA, and CXCL10 (IP-10) plasma concentrations. RNA viral load was decreased by 0.85 log10 (95% CI, −1.51 to −0.18) among T/T homozygotes, who also exhibited a lower frequency of acute symptoms. TLR7 emerges as an important control locus for acute HIV-1 viremia, and the clinical phenotype for allele rs179008 T, carried by 30%–50% of European women, supports a beneficial effect of toning down TLR7-driven IFN-I production by pDCs during acute HIV-1 infection.

International audience; Innate lymphoid cell (ILC) subsets at barrier surfaces contribute to maintain tissue homeostasis and appropriate responses to infection. ILCs respond to environmental factors produced by non-hematopoietic cells within tissues, but also circulating cytokines or dietary compounds which allow them to adapt to organ milieu. Among these extrinsic signals, evidence is emerging that sex steroid hormones may act in a cell-intrinsic manner to regulate the development, maintenance in tissues and effector functions of specific subsets of ILCs. Understanding the nature and molecular mechanisms of sex steroid hormone actions on ILCs is important to unravel the cause of sexual disparity in human diseases and could lead to new drug development for the treatment of chronic inflammatory diseases or cancers. This review discusses the recent development in our understanding of the cell-intrinsic actions of sex steroid hormones on ILCs and their consequences on tissue-specific immunity with a particular focus on group 2 innate lymphoid cells and NK cells.

Women develop stronger immune responses than men, with positive effects on the resistance to viral or bacterial infections but magnifying also the susceptibility to autoimmune diseases like systemic lupus erythematosus (SLE). In SLE, the dosage of the endosomal Toll-like receptor 7 (TLR7) is crucial. Murine models have shown that TLR7 overexpression suffices to induce spontaneous lupus-like disease. Conversely, suppressing TLR7 in lupus-prone mice abolishes SLE development. TLR7 is encoded by a gene on the X chromosome gene, denoted TLR7 in humans and Tlr7 in the mouse, and expressed in plasmacytoid dendritic cells (pDC), monocytes/macrophages, and B cells. The receptor recognizes single-stranded RNA, and its engagement promotes B cell maturation and the production of pro-inflammatory cytokines and antibodies. In female mammals, each cell randomly inactivates one of its two X chromosomes to equalize gene dosage with XY males. However, 15 to 23% of X-linked human genes escape X chromosome inactivation so that both alleles can be expressed simultaneously. It has been hypothesized that biallelic expression of X-linked genes could occur in female immune cells, hence fostering harmful autoreactive and inflammatory responses. We review here the current knowledge of the role of TLR7 in SLE, and recent evidence demonstrating that TLR7 escapes from X chromosome inactivation in pDCs, monocytes, and B lymphocytes from women and Klinefelter syndrome men. Female B cells where TLR7 is thus biallelically expressed display higher TLR7-driven functional responses, connecting the presence of two X chromosomes with the enhanced immunity of women and their increased susceptibility to TLR7-dependent autoimmune syndromes.

Resume L’asthme allergique est une maladie inflammatoire chronique caracterisee par une hyperreativite bronchique, une hyperproduction de mucus et un remodelage des voies aeriennes. L’asthme, qui debute souvent avant l’âge de 5 ans, est la maladie chronique la plus frequente chez l’enfant et touche environ 10 % de la population dans les pays industrialises. Comme c’est le cas pour de nombreuses maladies allergiques, l’asthme touche differentiellement les hommes et les femmes. La pathologie est plus frequente chez les garcons dans l’enfance, mais ce dimorphisme s’inverse a la puberte, suggerant une regulation par les hormones sexuelles. Dans cette revue, les donnees de la litterature au sujet de l’impact des hormones sexuelles sur l’asthme allergique sont resumees. Nous discutons en particulier de l’impact des androgenes sur le developpement et la fonction d’acteurs centraux des reponses allergiques recemment decrits, les cellules lymphoides innees du groupe 2.

Allergic asthma is a chronic pulmonary inflammatory disease initiated by exposure to normally harmless allergens and marked by bronchial hyperreactivity. It affects more than 300 million people worldwide. Asthma often starts in childhood. Epidemiological studies show that there are sexual disparities in the prevalence and severity of asthma. Before the age of 10, the disease is more common in boys. This tendency reverses at puberty suggesting a regulating role of the sex hormones. In this synthesis, we summarize current knowledge on the role of sex hormones in allergic inflammation, with a particular focus on the impact of androgens on the development and function of recently introduced group 2 innate lymphoid cell subsets (ILC2) as critical actors in the initiation of allergic responses.♢.

Introduction Les canaux calciques Cav1.2 et Cav1.3, sont selectivement presents sur les lymphocytes Th2 (LTh2) murins et humains (et non sur les Th1). Ils sont essentiels in vitro pour la reponse calcique et la production des cytokines Th2 (IL-4, -5 et -13) et in vivo pour l’induction d’un asthme allergique. Nous suspectons la proteine kinase C alpha (PKCα) d’etre un partenaire pour l’activation des canaux Cav1 dans les LTh2 et donc une nouvelle cible therapeutique dans l’asthme allergique. Methodes Les LTh2 sont stimules avec le PMA (activateur des PKCs) en presence ou pas de nicardipine, un inhibiteur des canaux calciques Cav1. Apres transfections des LTh2 avec des oligonucleotides (ODN) antisens PKCα (AS-PKCα), la secretion des cytokines Th2 a ete quantifiee par ELISA dans les surnageants et le signal calcique est analyse au champ large apres stimulation du TCR. L’effet de l’AS-PKCα a ete etudie dans deux modeles d’asthme : – Les souris BALB/c recoivent de l’ovalbumine (OVA) en alum par voie intraperitoneale (i.p.) puis inhalent l’OVA avec l’AS-PKCα ou un ODN controle ; – Les LTh2 prealablement transfectes avec l’AS-PKCα sont injectees en i.v. a des souris Balb/c qui inhalent l’OVA. Les lavages bronchoalveolaires (LBA), les IgE seriques, ainsi que les lesions histologiques pulmonaires sont analyses. Resultats Le PMA induit un signal calcique et la production des cytokines Th2 dans les LTh2, qui sont inhibes par la nicardipine. L’AS-PKCα diminue in vitro le signal calcique et la production de cytokines dans les LTh2 suite a l’engagement du TCR. In vivo, le nombre total de cellules dans le LBA, le score histologique et la concentration d’IgE seriques sont diminues dans le groupe AS-PKCα, dans le modele d’asthme actif comme dans le modele passif. Conclusions L’activation directe des PKCs induit la production des cytokines Th2 de facon dependante des canaux calciques Cav1. La PKCα joue un role preponderant dans la fonction des LTh2 et in vivo dans l’induction de l’asthme allergique. Du fait d’une large surface permettant les echanges alveolocapillaires, le poumon est l’organe ideal pour tester le potentiel therapeutique de ces ODN antisens PKCα inhales dans l’inflammation de l’asthme allergique.

At the onset of adolescence, asthma becomes less prevalent in males than in females, suggesting a protective role of male sex hormones. Here, Laffont et al. show that androgens negatively control ILC2 development and ILC2-driven lung inflammation in male mice., Prevalence of asthma is higher in women than in men, but the mechanisms underlying this sex bias are unknown. Group 2 innate lymphoid cells (ILC2s) are key regulators of type 2 inflammatory responses. Here, we show that ILC2 development is greatly influenced by male sex hormones. Male mice have reduced numbers of ILC2 progenitors (ILC2Ps) and mature ILC2s in peripheral tissues compared with females. In consequence, males exhibit reduced susceptibility to allergic airway inflammation in response to environmental allergens and less severe IL-33–driven lung inflammation, correlating with an impaired expansion of lung ILC2s. Importantly, orchiectomy, but not ovariectomy, abolishes the sex differences in ILC2 development and restores IL-33–mediated lung inflammation. ILC2Ps express the androgen receptor (AR), and AR signaling inhibits their differentiation into mature ILC2s. Finally, we show that hematopoietic AR expression limits IL-33–driven lung inflammation through a cell-intrinsic inhibition of ILC2 expansion. Thus, androgens play a crucial protective role in type 2 airway inflammation by negatively regulating ILC2 homeostasis, thereby limiting their capacity to expand locally in response to IL-33.

Plasmacytoid dendritic cells (pDCs) are found in the CNS during neuroinflammation and have been reported to exert regulatory functions in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). However, the mechanisms of entry of pDCs into the CNS as well as their phenotype and innate functional properties, once recruited into the CNS, have not been thoroughly examined. Herein, we show that pDCs rapidly accumulate into the brain and spinal cord during the acute phase of EAE, and maintain the expression of numerous phenotypic markers typical of peripheral pDCs. Functionally, CNS-pDCs constitutively expressed IRF7 and were able to rapidly produce type I IFNs and IL-12p40 upon ex vivo TLR-9 stimulation. Using adoptive transfer experiments, we provide evidence that CNS-pDC are recruited from the blood and accumulate into the CNS during the acute phase of EAE. Accumulation of pDCs into the CNS was strongly inhibited in the absence of CD29, but not CD18, suggesting a major role for ß1 but not ß2 integrins. Indeed, blocking the CD49d α4-integrins during acute EAE drastically diminished CNS-pDC numbers. Together, our results demonstrate that circulating pDCs are actively recruited into the CNS during acute EAE through a mechanism largely dependent on CD49d/CD29-integrins.

Men and women differ in their susceptibility to develop autoimmunity and allergy but also in their capacity to cope with infections. Mechanisms responsible for this sexual dimorphism are still poorly documented and probably multifactorial. This review discusses the recent development in our understanding of the cell-intrinsic actions of biological factors linked to sex, sex hormones and sex chromosome complement, on immune cells, which may account for the sex differences in the enhanced susceptibility of women to develop immunological disorders, such as allergic asthma or systemic lupus erythematosus (SLE). We choose to more specifically discuss the impact of sex hormones on the development and function of immune cell populations directly involved in type-2 immunity, and the role of the X-linked Toll like receptor 7 (TLR7) in anti-viral immunity and in SLE. We will also elaborate on the recent evidence demonstrating that TLR7 escapes from X chromosome inactivation in the immune cells of women, and how this may contribute to endow woman immune system with enhanced responsiveness to RNA-virus and susceptibility to SLE.

17β-Estradiol (E2) suppresses the development of experimental autoimmune encephalomyelitis (EAE) through estrogen receptor (ER) α, yet the cellular targets remain elusive. We have used an adoptive transfer model of myelin oligodendrocyte glycoprotein–specific CD4+ T cells from 2D2 TCR transgenic mice. We show that in the recipient mice, ERα expression in bystander CD4+ T cells, rather than in cognate 2D2 T cells, is required for the inhibition of Th17 cell differentiation by E2. Coadministration of estrogen-primed WT, but not ERα-deficient CD4+ T cells, with naive 2D2 T cells lacking ERα inhibited the development of Th17 cell–mediated EAE. Suppression of Th17 cells and protection from EAE were maintained when ERα was deleted in Foxp3+ regulatory T cells. We showed that in vivo PD-L1 blockade alleviated the anti-inflammatory action of E2 and that PD-1 expression on cognate but not bystander T cells was required for the E2-dependent inhibition of Th17 differentiation. In cotransfer experiments, we found that only WT but not PD-1KO 2D2 T cells were amenable to E2-dependent inhibition of Th17 differentiation. These results support the conclusion that the restriction of Th17 cell development by E2-primed bystander CD4+ T cells requires cell-intrinsic PD-1 signaling within cognate T cells rather than induction of regulatory 2D2 T cells through PD-1 engagement. Altogether, our results indicate that pregnancy-level concentrations of estrogen signal in conventional Foxp3neg CD4+ T cells to limit the differentiation of cognate Th17 cells through a trans-acting mechanism of suppression that requires a functional PD-1/PD-L1 regulatory axis.

17β-Estradiol (E2) suppresses the development of experimental autoimmune encephalomyelitis (EAE) through estrogen receptor (ER) α, yet the cellular targets remain elusive. We have used an adoptive transfer model of myelin oligodendrocyte glycoprotein-specific CD4

Allergic asthma is a chronic pulmonary inflammatory disease initiated by exposure to normally harmless allergens and marked by bronchial hyperreactivity. It affects more than 300 million people worldwide. Asthma often starts in childhood. Epidemiological studies show that there are sexual disparities in the prevalence and severity of asthma. Before the age of 10, the disease is more common in boys. This tendency reverses at puberty suggesting a regulating role of the sex hormones. In this synthesis, we summarize current knowledge on the role of sex hormones in allergic inflammation, with a particular focus on the impact of androgens on the development and function of recently introduced group 2 innate lymphoid cell subsets (ILC2) as critical actors in the initiation of allergic responses.♢.

Toll-like receptor 7 (TLR7) is critical to the induction of antiviral immunity, but TLR7 dosage is also a key pathogenic factor in systemic lupus erythematosus (SLE), an autoimmune disease with strong female bias. SLE prevalence is also elevated in individuals with Klinefelter syndrome, who carry one or more supernumerary X chromosomes, suggesting that the X chromosome complement contributes to SLE susceptibility. TLR7 is encoded by an X chromosome locus, and we examined here whether the TLR7 gene evades silencing by X chromosome inactivation in immune cells from women and Klinefelter syndrome males. Single-cell analyses of TLR7 allelic expression demonstrated that substantial fractions of primary B lymphocytes, monocytes, and plasmacytoid dendritic cells not only in women but also in Klinefelter syndrome males express TLR7 on both X chromosomes. Biallelic B lymphocytes from women displayed greater TLR7 transcriptional expression than the monoallelic cells, correlated with higher TLR7 protein expression in female than in male leukocyte populations. Biallelic B cells were preferentially enriched during the TLR7-driven proliferation of CD27+ plasma cells. In addition, biallelic cells showed a greater than twofold increase over monoallelic cells in the propensity to immunoglobulin G class switch during the TLR7-driven, T cell-dependent differentiation of naive B lymphocytes into immunoglobulin-secreting cells. TLR7 escape from X inactivation endows the B cell compartment with added responsiveness to TLR7 ligands. This finding supports the hypothesis that enhanced TLR7 expression owing to biallelism contributes to the higher risk of developing SLE and other autoimmune disorders in women and in men with Klinefelter syndrome.

CD4+ T cells polarize into effector Th subsets characterized by signature transcription factors and cytokines. Although T-bet drives Th1 responses and represses the alternative Th2, Th17, and Foxp3+ regulatory T cell fates, the role of the T-bet–related transcription factor eomesodermin (Eomes) in CD4+ T cells is less well understood. In this study, we analyze the expression and effects of Eomes in mouse CD4+ T lymphocytes. We find that Eomes is readily expressed in activated CD4+ Th1 T cells in vivo. Eomes+ CD4+ T cells accumulated in old mice, under lymphopenic conditions in a T cell transfer model of colitis, and upon oral Ag administration. However, despite its expression, genetic deletion of Eomes in CD4+ T cells did not impact on IFN-γ production nor increase Th2 or Th17 responses. In contrast, Eomes deficiency favored the accumulation of Foxp3+ cells in old mice, after in vivo differentiation of Eomes-deficient naive CD4+ T cells, and in response to oral Ag in a cell-intrinsic way. Enforced Eomes expression during in vitro regulatory T cell induction also reduced Foxp3 transcription. Likewise, bystander Eomes-deficient CD4+ T cells were more efficient at protecting from experimental autoimmune encephalitis compared with wild-type CD4+ T cells. This enhanced capacity of Eomes-deficient CD4+ T cells to inhibit EAE in trans was associated with an enhanced frequency of Foxp3+ cells. Our data identify a novel role for Eomes in CD4+ T cells and indicate that Eomes expression may act by limiting Foxp3 induction, which may contribute to the association of EOMES to susceptibility to multiple sclerosis.

International audience; BACKGROUND: T-lymphocytes express not only the cell membrane calcium ORAI1 but also voltage-dependent Cav1 channels. In excitable cells, these channels are composed of the ion forming pore α1 and auxiliary subunits (β and α2δ) needed for proper trafficking and activation of the channel. We previously disclosed the role of Cav1.2 α1 in mouse and human Th2- but not Th1-cell functions and showed that knocking-down Cav1 α1 prevents experimental asthma OBJECTIVE: We investigated the role of β and α2δ auxiliary subunits on Cav1 α1 function in Th2 lymphocytes and on the development of acute allergic airway inflammation. METHODS: We used antisense oligonucleotides (CavβAS) to knockdown Cavβ and gabapentin, a drug that binds to and inhibits α2δ1 and α2δ2, to test their effects on Th2 functions and their capacity to reduce allergic airway inflammation. RESULTS: Mouse and human Th2-cells express mainly Cavβ1, β3 and α2δ2 subunits. CavβAS reduces TCR-driven calcium responses and cytokine production by mouse and human Th2, with no effect on Th1-cells. Cavβ is mainly involved in restraining Cav1.2 α1 degradation through the proteasome as a proteasome inhibitor partially restores the α1 protein level. Gabapentin impairs TCR-driven calcium response and cytokine production associated with the loss of α2δ2 protein in Th2-cells. CONCLUSIONS: These results stress the role of Cavβ and α2δ2 auxiliary subunits in the stability and activation of Cav1.2 channels in Th2 lymphocytes both in vitro and in vivo as demonstrated by the beneficial effect of CavβAS and gabapentin in allergic airway inflammation. CLINICAL IMPLICATIONS: The demonstration that auxiliary subunits are involved in calcium signaling through Cav1 channels and function of mouse and human Th2-lymphocytes supports their potential beneficial effect on allergic asthma.

T lymphocytes express not only cell membrane ORAI calcium release-activated calcium modulator 1 but also voltage-gated calcium channel (CaWe investigated the role of β and α2δ auxiliary subunits on CaWe used CaMouse and human TThese results stress the role of Ca

Autoimmunity, infectious diseases and cancer affect women and men differently. Because they tend to develop more vigorous adaptive immune responses than men, women are less susceptible to some infectious diseases but also at higher risk of autoimmunity. The regulation of immune responses by sex-dependent factors probably involves several non-redundant mechanisms. A privileged area of study, however, concerns the role of sex steroid hormones in the biology of innate immune cells, especially dendritic cells (DCs). In recent years, our understanding of the lineage origin of DC populations has expanded, and the lineage-committing transcription factors shaping peripheral DC subsets have been identified. Both progenitor cells and mature DC subsets express estrogen receptors (ERs), which are ligand-dependent transcription factors. This suggests that estrogens may contribute to the reported sex differences in immunity by regulating DC biology. Here, we review the recent literature and highlight evidence that estrogen-dependent activation of ERα regulates the development or the functional responses of particular DC subsets. The in vitro model of GM-CSF-induced DC differentiation shows that CD11c+ CD11bint Ly6cneg cells depend on ERα activation by estrogen for their development, and for the acquisition of competence to activate naive CD4+ T lymphocytes and mount a robust pro-inflammatory cytokine response to CD40 stimulation. In this model, estrogen signaling in conjunction with GM-CSF is necessary to promote early interferon regulatory factor (Irf)-4 expression in macrophage-DC progenitors and their subsequent differentiation into IRF-4hi CD11c+ CD11bint Ly6cneg cells, closely related to the cDC2 subset. The Flt3L-induced model of DC differentiation in turn shows that ERα signaling promotes the development of conventional DC (cDC) and plasmacytoid DC (pDC) with higher capability of pro-inflammatory cytokine production in response to TLR stimulation. Likewise, cell-intrinsic ER signaling positively regulates the TLR-driven production of type I interferons (IFNs) in mouse pDCs in vivo. This effect of estrogens likely contributes to the greater proficiency of women’s pDCs than men’s as regards the production of type I IFNs elicited by TLR7 ligands. In summary, evidence is emerging in support of the notion that estrogen signaling regulates important aspects of cDC and pDC development and/or effector functions, in both mice and humans.

Human plasmacytoid dendritic cells (pDCs) play a major role in innate immunity through the production of type I IFNs after TLR engagement by pathogens. Sex-based differences in the innate function of human pDCs have been established, with pDCs from women exhibiting enhanced TLR7-mediated IFN-α production as compared with pDCs from males. In mice, we recently provided evidence for a role of estrogens as a positive regulator of pDC innate functions through cell-intrinsic estrogen receptor α signaling, but did not exclude a role for other X-linked factors, particularly in human pDCs. In this study, we investigated the respective contribution of X chromosome dosage and sex hormones using a humanized mouse model in which male or female NOD-SCID-β2m−/− were transplanted with human progenitor cells purified from either male or female cord blood cells. We showed that, in response to TLR7 ligands, the frequency of IFN-α– and TNF-α–producing pDCs from either sex was greater in female than in male host mice, suggesting a positive role for estrogens. Indeed, blockade of estrogen receptor signaling during pDC development in vitro inhibited TLR7-mediated IFN-α production by human pDCs, which expressed both ESR1 and ESR2 genes. Interestingly, we also found that X chromosome dosage contributed to this sex bias as female pDCs have an enhanced TLR7-mediated IFN-α response as compared with male ones, irrespective of the sex of the recipient mice. Together, these results indicate that female sex hormones, estrogens, and X chromosome complement independently contribute to the enhanced TLR7-mediated IFN-α response of pDCs in women.

The recognition of multiple ligands by a single TCR is an intrinsic feature of T cell biology, with important consequences for physiological and pathological processes. Polyspecific T cells targeting distinct self-antigens have been identified in healthy individuals as well as in the context of autoimmunity. We have previously shown that the 2D2 TCR recognizes the myelin oligodendrocyte glycoprotein epitope (MOG)35–55 as well as an epitope within the axonal protein neurofilament medium (NF-M15–35) in H-2b mice. In this study, we assess whether this cross-reactivity is a common feature of the MOG35–55-specific T cell response. To this end, we analyzed the CD4 T cell response of MOG35–55-immunized C57BL/6 mice for cross-reactivity with NF-M15–35. Using Ag recall responses, we established that an important proportion of MOG35–55-specific CD4 T cells also responded to NF-M15–35 in all mice tested. To study the clonality of this response, we analyzed 22 MOG35–55-specific T cell hybridomas expressing distinct TCR. Seven hybridomas were found to cross-react with NF-M15–35. Using an alanine scan of NF-M18–30 and an in silico predictive model, we dissected the molecular basis of cross-reactivity between MOG35–55 and NF-M15–35. We established that NF-M F24, R26, and V27 proved important TCR contacts. Strikingly, the identified TCR contacts are conserved within MOG38–50. Our data indicate that due to linear sequence homology, part of the MOG35–55-specific T cell repertoire of all C57BL/6 mice also recognizes NF-M15–35, with potential implications for CNS autoimmunity.

Brown Norway rats injected with aurothiopro-panolsulfonate sodium salt develop systemic autoimmunity. The aim of this study was to assess the influence of the sulfur-containing group in this experimental model of gold-induced autoimmunity. It was shown that the sulfur-containing group does not induce autoimmunity of itself, but potentiates the immunotoxic effects of gold.

Th2 cells orchestrate allergic asthma and the cytokines they produce (IL-4, IL-5, and IL-13) are deleterious in allergy. Therefore, it is important to identify key signaling molecules expressed by Th2 cells that are essential for their function. We have previously shown that dihydropyridines selectively modulate Th2 cell functions.Because dihydropyridines bind to and modulate voltage-dependent calcium (Ca(v)1) channel in excitable cells, we aimed at showing that Th2 cells selectively express functional Ca(v)1-related channels, the inhibition of which may prevent asthma.We looked for Ca(v)1 channel expression in Th2 and Th1 cells by real-time polymerase chain reaction and Western blotting. We sequenced the isoforms expressed by Th2 cells and tested whether Ca(v)1 antisense oligodeoxynucleotides (Ca(v)1AS) affected Ca(2+) signaling and cytokine production. Finally, we tested the effect of Ca(v)1AS in the passive asthma model by injection of ovalbumin-specific Th2 cells transfected with Ca(v)1AS into BALB/c mice challenged with intranasal ovalbumin and in the active model of asthma by intranasal delivery of Ca(v)1AS together with soluble ovalbumin in BALB/c mice previously immunized with ovalbumin in alum.We show that mouse Th2 but not Th1 cells expressed Ca(v)1.2 and Ca(v)1.3 channels. Th2 cells transfected with Ca(v)1AS had impaired Ca(2+) signaling and cytokine production, and lost their ability to induce airway inflammation on adoptive transfer. Furthermore, intranasal administration of Ca(v)1AS suppressed airway inflammation and hyperreactivity in an active model of asthma.These results indicate that Th2 cells selectively express Ca(v)1 channels that may be efficiently targeted in T lymphocytes to prevent experimental asthma.

Asthma is a chronic airway disease resulting from inappropriate Th2-cell biased activation. Interleukin (IL)-4, IL-5 and IL-13 produced by Th2 cells contribute to the inflammatory process. Attempts for inhibiting interleukin-4 or IL-5 gave disappointing results. The simultaneous inhibition of several Th2-cytokines could be a more promising issue. Several arguments support the concept that Th2-cells express selective markers that could be targeted in asthma. Our group showed that Th2-cells selectively up-regulated dihydropyridine-sensitive Ca(2+) (DHP-Ca) channels essential for Ca(2+) signaling and type-2 cytokine production. Indeed, DHP-Ca antagonist effectively prevented or even reverted airway inflammation, airway remodeling and airway hyperresponsiveness in experimental models of asthma. Although it remains to be formally demonstrated that human lung infiltrating T-lymphocytes in asthmatic patients express DHP- Ca(2+) channels, we hypothesize that targeting DHP-Ca channels in T-lymphocytes could represent an efficient strategy in the treatment of asthma.This review article also discussed patents relevant to the field.