Asthme allergique induit par un allergène d’acarien, House Dust Mite (HDM) : rôles de la caspase-1 et de la protéine kinase C thêta (PKC-θ)

Studies from our laboratory have shown a critical role of NLRP3 inflammasome in response to ovalbumin allergen. In the present study we investigate the role of NLRP3 and caspase-1 in a mouse model of pulmonary inflammation induced by HDM. We have shown a regulatory role of caspase-1 dependant of the NLRP3 inflammasome and the adaptator molecule ASC but not NLRC4. The regulation of the allergic response is characterized by an increase of eosinophilia, bronchial hyperreactivity and Th2 cytokines production (IL-4, IL-5, IL-13 and IL-33) in lungs. We have shown that mechanisms responsible of this regulation are associated with IL-33 production by macrophages and that neutralization of IL-33 by local administration of a fusion protein of the ST2 receptor (muST2-Fc) reduce characteristics of asthma. These results suggest that caspase-1 activation reduce IL-33 production in vivo regulating lung inflammation and Th2 response induced by HDM. Moreover, we investigate the role of the Protein Kinase C theta (PKC-θ) in allergic airway inflammation. We have demonstrated that PKC-θ plays a protective role in allergic asthma but is critical for the activation and proliferation of innate lymphoid cells (ILC2). In addition, in vivo inhibition by oral administration of PKC-θ specific inhibitor C20 (BIX02656) reduces pulmonary inflammation with IL-5 and IL-13 production. We suggest that PKC-θ is implicated in Th2 and ILC2 differenciation by a mechanism dependant on transcription factors IRF4 and NFAT-1. Finally, my thesis projects describe IL-33 and PKC-θ as potential therapeutic targets for allergic lung inflammation.Des études menées au laboratoire avaient démontré un rôle critique de l’inflammasome NLRP3 dans l’asthme allergique en réponse à l’ovalbumine en absence d’adjuvant. Mes travaux de thèse ont porté sur le rôle de NLRP3 et de la caspase-1 dans un modèle murin d’inflammation pulmonaire induite par l’allergène d’acarien HDM. Nous avons montré un rôle régulateur de la caspase-1 dépendant de l’inflammasome NLRP3 et la molécule adaptatrice ASC mais pas de l’inflammasome NLRC4. Cette régulation de la réponse allergique se caractérise par une augmentation de l’infiltration des éosinophiles, de l’hyperréactivité bronchique et de la production des cytokines de type Th2 telles que l’IL-4, l’IL-5, l’IL-13 et l’IL-33 dans les poumons. Nous avons montré que les mécanismes responsables de cette régulation sont associés à l’IL-33 produite par les macrophages et que la neutralisation de l’IL-33 par administration locale de la protéine de fusion au récepteur ST2 (muST2-Fc) atténue les caractéristiques de l’asthme allergique. Ces résultats suggèrent que l’activation de la caspase-1 réduit la production d’IL-33 in vivo et régule ainsi la réponse l’inflammation pulmonaire induite par HDM et la réponse Th2. D’autre part, nous nous sommes intéressés au rôle de la Protéine Kinase C thêta (PKC-θ) dans ce même modèle d’inflammation pulmonaire. Nous avons démontré que PKC-θ joue non seulement un rôle protecteur dans l’asthme allergique mais également un rôle critique pour la prolifération et l’activation des cellules lymphoïdes innées (ILC2). D’autre part, l’inhibition de PKC-θ in vivo par administration orale de son inhibiteur spécifique C20 (BIX02656) atténue l’inflammation pulmonaire et la production d’IL-5 et d’IL-13. Nous suggérons que PKC-θ est impliquée dans la différenciation des Th2 et des ILC2 via un mécanisme dépendant des facteurs de transcription IRF4 et NFAT-1. Au total, mes travaux de thèse mettent en exergue deux molécules IL-33 et PKC-θ qui pourraient constituer des cibles thérapeutiques potentielles

Allergic asthma induced by House Dust Mite allergen (HDM) : roles of caspase-1 and protein kinase C theta (PKC-θ)

Des études menées au laboratoire avaient démontré un rôle critique de l’inflammasome NLRP3 dans l’asthme allergique en réponse à l’ovalbumine en absence d’adjuvant. Mes travaux de thèse ont porté sur le rôle de NLRP3 et de la caspase-1 dans un modèle murin d’inflammation pulmonaire induite par l’allergène d’acarien HDM. Nous avons montré un rôle régulateur de la caspase-1 dépendant de l’inflammasome NLRP3 et la molécule adaptatrice ASC mais pas de l’inflammasome NLRC4. Cette régulation de la réponse allergique se caractérise par une augmentation de l’infiltration des éosinophiles, de l’hyperréactivité bronchique et de la production des cytokines de type Th2 telles que l’IL-4, l’IL-5, l’IL-13 et l’IL-33 dans les poumons. Nous avons montré que les mécanismes responsables de cette régulation sont associés à l’IL-33 produite par les macrophages et que la neutralisation de l’IL-33 par administration locale de la protéine de fusion au récepteur ST2 (muST2-Fc) atténue les caractéristiques de l’asthme allergique. Ces résultats suggèrent que l’activation de la caspase-1 réduit la production d’IL-33 in vivo et régule ainsi la réponse l’inflammation pulmonaire induite par HDM et la réponse Th2. D’autre part, nous nous sommes intéressés au rôle de la Protéine Kinase C thêta (PKC-θ) dans ce même modèle d’inflammation pulmonaire. Nous avons démontré que PKC-θ joue non seulement un rôle protecteur dans l’asthme allergique mais également un rôle critique pour la prolifération et l’activation des cellules lymphoïdes innées (ILC2). D’autre part, l’inhibition de PKC-θ in vivo par administration orale de son inhibiteur spécifique C20 (BIX02656) atténue l’inflammation pulmonaire et la production d’IL-5 et d’IL-13. Nous suggérons que PKC-θ est impliquée dans la différenciation des Th2 et des ILC2 via un mécanisme dépendant des facteurs de transcription IRF4 et NFAT-1. Au total, mes travaux de thèse mettent en exergue deux molécules IL-33 et PKC-θ qui pourraient constituer des cibles thérapeutiques potentielles.Studies from our laboratory have shown a critical role of NLRP3 inflammasome in response to ovalbumin allergen. In the present study we investigate the role of NLRP3 and caspase-1 in a mouse model of pulmonary inflammation induced by HDM. We have shown a regulatory role of caspase-1 dependant of the NLRP3 inflammasome and the adaptator molecule ASC but not NLRC4. The regulation of the allergic response is characterized by an increase of eosinophilia, bronchial hyperreactivity and Th2 cytokines production (IL-4, IL-5, IL-13 and IL-33) in lungs. We have shown that mechanisms responsible of this regulation are associated with IL-33 production by macrophages and that neutralization of IL-33 by local administration of a fusion protein of the ST2 receptor (muST2-Fc) reduce characteristics of asthma. These results suggest that caspase-1 activation reduce IL-33 production in vivo regulating lung inflammation and Th2 response induced by HDM. Moreover, we investigate the role of the Protein Kinase C theta (PKC-θ) in allergic airway inflammation. We have demonstrated that PKC-θ plays a protective role in allergic asthma but is critical for the activation and proliferation of innate lymphoid cells (ILC2). In addition, in vivo inhibition by oral administration of PKC-θ specific inhibitor C20 (BIX02656) reduces pulmonary inflammation with IL-5 and IL-13 production. We suggest that PKC-θ is implicated in Th2 and ILC2 differenciation by a mechanism dependant on transcription factors IRF4 and NFAT-1. Finally, my thesis projects describe IL-33 and PKC-θ as potential therapeutic targets for allergic lung inflammation

Production of Interleukin-20 cytokines limits bacterial clearance and lung inflammation during infection by Streptococcus pneumoniaeResearch in context

Background: Streptococcus pneumoniae is the leading cause of bacterial pneumonia worldwide. Previous reports showed that IL-20 cytokines (IL-19, IL-20 and IL-24) are induced and have an immuno-regulatory function during cutaneous infection. In the current study, our aim was to demonstrate the implication of IL-20 cytokines and their receptors and their role during experimental pneumococcal infection. Methods: C57BL/6 mice were infected with S. pneumoniae by intranasal route. The bacterial burden, the immune response and the cytokine production were evaluated after treatment with an anti-IL-20 receptor-b (IL-20Rb) neutralizing antibody (anti-IL-20Rb). Findings: Of interest, expression of IL-20 cytokines mRNA and protein were transiently increased in the lung tissue during infection. Blocking of the IL-20Rb decreased the bacterial burden both in the bronchoalveolar lavage and the lung whereas there was no significant drop in the blood. This treatment also reduced the pulmonary damages (as shown by the alveolar wall thickening), the recruitment of neutrophils and dendritic cells, and the levels of the pro-inflammatory cytokines IL-1β and IL-6 in the lung. Administration of the anti-IL-20Rb antibody enhanced the synthesis of the antibacterial peptide LCN2. However, this effect is transient and did not affect the survival of the infected mice. Interpretation: Collectively, this study highlights the implication of IL-20 related cytokines during lung infection by S. pneumoniae and might have therapeutic applications in bacterial pneumonia. Fundings: This work was supported by CNRS, INSERM, INSERM-transfert, the University of Lille and the Fondation du Souffle (Paris, France). Keywords: Pneumonia, Cytokines, Cytokine receptor, Immunomodulation, Antimicrobial peptide

Physical interaction between neurofibromin and serotonin 5-HT6receptor promotes receptor constitutive activity

International audienceActive G protein-coupled receptor (GPCR) conformations not only are promoted by agonists but also occur in their absence, leading to constitutive activity. Association of GPCRs with intracellular protein partners might be one of the mechanisms underlying GPCR constitutive activity. Here, we show that serotonin 5 hydroxytryptamine 6 (5-HT6) receptor constitutively activates the Gs/adenylyl cyclase pathway in various cell types, including neurons. Constitutive activity is strongly reduced by silencing expression of the Ras-GTPase activating protein (Ras-GAP) neurofibromin, a 5-HT6 receptor partner. Neurofibromin is a multidomain protein encoded by the NF1 gene, the mutation of which causes Neurofibromatosis type 1 (NF1), a genetic disorder characterized by multiple benign and malignant nervous system tumors and cognitive deficits. Disrupting association of 5-HT6 receptor with neurofibromin Pleckstrin Homology (PH) domain also inhibits receptor constitutive activity, and PH domain expression rescues 5-HT6 receptor-operated cAMP signaling in neurofibromin-deficient cells. Furthermore, PH domains carrying mutations identified in NF1 patients that prevent interaction with the 5-HT6 receptor fail to rescue receptor constitutive activity in neurofibromin-depleted cells. Further supporting a role of neurofibromin in agonist-independent Gs signaling elicited by native receptors, the phosphorylation of cAMP-responsive element-binding protein (CREB) is strongly decreased in prefrontal cortex of Nf1+/− mice compared with WT mice. Moreover, systemic administration of a 5-HT6 receptor inverse agonist reduces CREB phosphorylation in prefrontal cortex of WT mice but not Nf1+/− mice. Collectively, these findings suggest that disrupting 5-HT6 receptor–neurofibromin interaction prevents agonist-independent 5-HT6 receptor-operated cAMP signaling in prefrontal cortex, an effect that might underlie neuronal abnormalities in NF1 patients

T Lymphocyte Serotonin 5-HT7 Receptor Is Dysregulated in Natalizumab-Treated Multiple Sclerosis Patients

International audienceSerotonin (5-HT) is known as a potent immune cell modulator in autoimmune diseases and should be protective in the pathogenesis of multiple sclerosis (MS). Nevertheless, there is limited knowledge about receptors involved in 5-HT effects as well as induced mechanisms. Among 5-HT receptors, the 5-HT7 receptor is able to activate naïve T cells and influence the inflammatory response; however, its involvement in the disease has never been studied so far. In this study, we collected blood sample from three groups: acute relapsing MS patients (ARMS), natalizumab-treated MS patients (NTZ), and control subjects. We investigated the 5-HT7 expression on circulating lymphocytes and evaluated the effects of its activation on cytokine production with peripheral blood mononuclear cell (PBMC) cultures. We found a significant increase in the 5-HT7 surface expression on T lymphocytes and on the different CD4+ T cell subsets exclusively in NTZ-treated patients. We also showed that the selective agonist 5-carboxamidotryptamine (5-CT)-induced 5-HT7R activation significantly promotes the production of IL-10, a potent immunosuppressive cytokine in PBMCs. This study provides for the first time a dysregulation of 5-HT7 expression in NTZ-MS patients and its ability to promote IL-10 release, suggesting its protective role. These findings strengthen the evidence that 5-HT7 may play a role in the immuno-protective mechanisms of NTZ in MS disease and could be considered as an interesting therapeutic target in MS.</jats:p

Safe and Efficient Sigma1 Ligand: A Potential Drug Candidate for Multiple Sclerosis

Multiple Sclerosis (MS) is an autoimmune demyelinating and neurodegenerative disease of the central nervous system (CNS). Current management strategies suppress or modulate immune function, all with consequences and known side effects. They demonstrate a high level of success in limiting new relapses. However, the neurodegenerative process still affects both grey and white matter in the central nervous system. The sigma1 (S1R) ligand-regulated chaperone is implicated in many biological processes in various CNS-targeted diseases, acting on neural plasticity, myelination and neuroinflammation. Among the proteins involved in MS, S1R has therefore emerged as a promising new target. Standard and robust methods have been adopted to analyze the adsorption, distribution, metabolism, excretion (ADME) properties, safety pharmacology and toxicology of a previously synthetized simple benzamide-derived compound with nanomolar affinity for S1R, high selectivity, no cytotoxicity and good metabolic stability. The compound was also characterized as an agonist based on well-validated assays prior to in vivo investigations. Interestingly, we found that the oral administration of this compound resulted in an overall significant reduction in clinical progression in an MS experimental model. This effect is mediated through S1R action. Our results further suggest the potential use of this compound in the treatment of MS

Physical interaction between neurofibromin and serotonin 5-HT 6

International audienceActive G protein-coupled receptor (GPCR) conformations not only are promoted by agonists but also occur in their absence, leading to constitutive activity. Association of GPCRs with intracellular protein partners might be one of the mechanisms underlying GPCR constitutive activity. Here, we show that serotonin 5 hydroxytryptamine 6 (5-HT6) receptor constitutively activates the Gs/adenylyl cyclase pathway in various cell types, including neurons. Constitutive activity is strongly reduced by silencing expression of the Ras-GTPase activating protein (Ras-GAP) neurofibromin, a 5-HT6 receptor partner. Neurofibromin is a multidomain protein encoded by the NF1 gene, the mutation of which causes Neurofibromatosis type 1 (NF1), a genetic disorder characterized by multiple benign and malignant nervous system tumors and cognitive deficits. Disrupting association of 5-HT6 receptor with neurofibromin Pleckstrin Homology (PH) domain also inhibits receptor constitutive activity, and PH domain expression rescues 5-HT6 receptor-operated cAMP signaling in neurofibromin-deficient cells. Furthermore, PH domains carrying mutations identified in NF1 patients that prevent interaction with the 5-HT6 receptor fail to rescue receptor constitutive activity in neurofibromin-depleted cells. Further supporting a role of neurofibromin in agonist-independent Gs signaling elicited by native receptors, the phosphorylation of cAMP-responsive element-binding protein (CREB) is strongly decreased in prefrontal cortex of Nf1+/− mice compared with WT mice. Moreover, systemic administration of a 5-HT6 receptor inverse agonist reduces CREB phosphorylation in prefrontal cortex of WT mice but not Nf1+/− mice. Collectively, these findings suggest that disrupting 5-HT6 receptor–neurofibromin interaction prevents agonist-independent 5-HT6 receptor-operated cAMP signaling in prefrontal cortex, an effect that might underlie neuronal abnormalities in NF1 patients

Serodolin, a β-arrestin–biased ligand of 5-HT 7 receptor, attenuates pain-related behaviors

International audienceTransmembrane signaling through G protein–coupled receptors (GPCRs), originally described as requiring coupling to intracellular G proteins, also uses G protein–independent pathways through β-arrestin recruitment. Biased ligands, by favoring one of the multiple bioactive conformations of GPCRs, allow selective signaling through either of these pathways. Here, we identified Serodolin as the first β-arrestin–biased agonist of the serotonin 5-HT 7 receptor. This new ligand, while acting as an inverse agonist on G s signaling, selectively induces ERK activation in a β-arrestin–dependent way. Importantly, we report that Serodolin decreases pain intensity caused by thermal, mechanical, or inflammatory stimuli. Our findings suggest that targeting the 5-HT 7 R with β-arrestin–biased ligand could be a valid alternative strategy to the use of opioids for the relief of pain

Protein kinase C θ controls type 2 innate lymphoid cell and TH2 responses to house dust mite allergen.

IF 13.081International audienceBACKGROUND:Protein kinase C (PKC) θ, a serine/threonine kinase, is involved in TH2 cell activation and proliferation. Type 2 innate lymphoid cells (ILC2s) resemble TH2 cells and produce the TH2 cytokines IL-5 and IL-13 but lack antigen-specific receptors. The mechanism by which PKC-θ drives innate immune cells to instruct TH2 responses in patients with allergic lung inflammation remains unknown.OBJECTIVES:We hypothesized that PKC-θ contributes to ILC2 activation and might be necessary for ILC2s to instruct the TH2 response.METHODS:PRKCQ gene expression was assessed in innate lymphoid cell subsets purified from human PBMCs and mouse lung ILC2s. ILC2 activation and eosinophil recruitment, TH2-related cytokine and chemokine production, lung histopathology, interferon regulatory factor 4 (IRF4) mRNA expression, and nuclear factor of activated T cells (NFAT1) protein expression were determined. Adoptive transfer of ILC2s from wild-type mice was performed in wild-type and PKC-θ-deficient (PKC-θ-/-) mice.RESULTS:Here we report that PKC-θ is expressed in both human and mouse ILC2s. Mice lacking PKC-θ had reduced ILC2 numbers, TH2 cell numbers and activation, airway hyperresponsiveness, and expression of the transcription factors IRF4 and NFAT1. Importantly, adoptive transfer of ILC2s restored eosinophil influx and IL-4, IL-5 and IL-13 production in lung tissue, as well as TH2 cell activation. The pharmacologic PKC-θ inhibitor (Compound 20) administered during allergen challenge reduced ILC2 numbers and activation, as well as airway inflammation and IRF4 and NFAT1 expression.CONCLUSIONS:Therefore our findings identify PKC-θ as a critical factor for ILC2 activation that contributes to TH2 cell differentiation, which is associated with IRF4 and NFAT1 expression in allergic lung inflammation