Role of IL-1β in experimental cystic fibrosis upon P. aeruginosa Infection

Cystic fibrosis is associated with increased inflammatory responses to pathogen challenge. Here we revisited the role of IL-1β in lung pathology using the experimental F508del-CFTR murine model on C57BL/6 genetic background (Cftrtm1eur or d/d), on double deficient for d/d and type 1 interleukin-1 receptor (d/d X IL-1R1-/-), and antibody neutralization. At steady state, young adult d/d mice did not show any signs of spontaneous lung inflammation. However, IL-1R1 deficiency conferred partial protection to repeated P. aeruginosa endotoxins/LPS lung instillation in d/d mice, as 50% of d/d mice succumbed to inflammation, whereas all d/d x IL-1R1-/- double mutants survived with lower initial weight loss and less pulmonary collagen and mucus production, suggesting that the absence of IL-1R1 signaling is protective in d/d mice in LPS-induced lung damage. Using P. aeruginosa acute lung infection we found heightened neutrophil recruitment in d/d mice with higher epithelial damage, increased bacterial load in BALF, and augmented IL-1β and TNF-α in parenchyma as compared to WT mice. Thus, F508del-CFTR mice show enhanced IL-1β signaling in response to P. aeruginosa. IL-1β antibody neutralization had no effect on lung homeostasis in either d/d or WT mice, however P. aeruginosa induced lung inflammation and bacterial load were diminished by IL-1β antibody neutralization. In conclusion, enhanced susceptibility to P. aeruginosa in d/d mice correlates with an excessive inflammation and with increased IL-1β production and reduced bacterial clearance. Further, we show that neutralization of IL-1β in d/d mice through the double mutation d/d x IL-1R1-/- and in WT via antibody neutralization attenuates inflammation. This supports the notion that intervention in the IL-1R1/IL-1β pathway may be detrimental in CF patients

Etude du rôle de l'interleukine 33 dans l'infection pulmonaire aiguë à Pseudomonas aeruginosa

Pseudomonas aeruginosa est une bactérie pathogène opportuniste pouvant être responsable d infections graves, en particulier pulmonaires, chez les personnes immunodéprimées. Dans la physiopathologie de l infection, la bactérie se fixe à différents récepteurs extra et intracellulaires comme les récepteurs Toll-Like (TLRs) et Nod-Like (NLRs) conduisant à la sécrétion de nombreuses cytokines dont l Interleukine-1b (IL-1b) et l IL-33. Il a été montré que l IL-1b est nécessaire à la mise en place d une réponse immunitaire lors d une infection pulmonaire aiguë à Pseudomonas aeruginosa. L IL-33 a récemment été rattachée à la famille de l IL-1, c est pourquoi nous avons voulu déterminer expérimentalement son implication lors de l infection pulmonaire par P.aeruginosa. In vitro, les macrophages sauvages secrètent une quantité plus importante de LDH ainsi que d IL-1b, IL-6, IL-33 et KC (Keratinocyte Chemoattractant/CXCL1) et in vivo, dans un modèle de souris génétiquement modifiées, les mêmes marqueurs sont retrouvés augmentés. Chez les souris ST2 -/-, ST2 étant le récepteur de l IL-33, nous avons mis en évidence une résistance à l infection par P. aeruginosa. En effet, les souris ST2 -/- présentent des signes cliniques atténués, et sécrètent une plus faible quantité d IL-1b ou d IL-6, malgré une augmentation de la quantité de KC. Il semble que l IL-33 joue un rôle important dans le développement de la maladie pulmonaire liée à P. aeruginosa et que l absence de son récepteur soit un facteur protecteur contre la maladie.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

HDAC/HDACi, IgH 3’RR Enhancers, B-Cells and B-Cell Lymphomas

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Homozygous iMycCα transgenic mice as a model of plasma B-cell lymphomas

International audienceThe 3' regulatory region (3'RR) located downstream from the Cα gene is the conductor of transcription, accessibility, and remodeling of the IgH locus at mature B-cell stages. Convincing demonstrations of the essential contributions of the 3'RR in B-cell lymphomagenesis have been provided by mouse models which bring the oncogene c-Myc under the 3'RR transcriptional control. In this study, we developed a mouse model of CD138+ plasma B-cell lymphomas. If the KI of c-myc directly into Cα just 5' to the 3'RR in iMycCα mice produced B-cell lymphomas with low kinetics, we enforced c-myc production in iMycCα mice by the generation of homozygous c-myc transgenic mice. Our results show that homozygous iMycCα mice lead to a mouse model of plasma CD138+ B-cell lymphomas with interesting and wide transcriptomic similarities to human multiple myeloma and appropriated emergence kinetics that can be used to test new experimental therapeutic approaches

REL deregulation stands as a primary hit for AID-imprinted B-cells along the germinal center competition

Abstract In diffuse large B-cell lymphomas (DLBCLs), gains and amplifications of the 2p15-16 region, which always encompass the REL gene, are mostly restricted to the germinal center (GC) B- cell DLBCL subtype (GCB-DLBCL) for which c-Rel is the pivotal Rel/NF-κB subunit. While REL is also known to play a key role in the GC reaction, its contribution to GCB-DLBCL transformation is still unclear. To understand the role of REL in the very first steps of GCB transformation, i.e when B-cells with deregulated REL are competing with other B-cells during chronic antigenic stimulation, we have created a dual-color mouse that allows to induce REL in a limited pool of AID- imprinted B-cells after immunization and to differentially stain AID-imprinted B-cells cells that overexpress REL or not. Our results demonstrate that dysregulation of REL at the GC B-cell stage promotes GC B-cell expansion and favors both class-switch recombination and plasma cell differentiation. Additionally, although REL overexpression was neutral on post-GC memory B-cell differentiation, it did confer a long-term competitive advantage allowing for GC persistence and continuous recirculation of REL -overexpressing B-cells. Functionally, REL enhanced the protection against apoptosis in the early steps of GCB differentiation. REL - overexpressing B-cells can my occasionally transform into in an aggressive B-cell tumor. Highlighting the role of repeated immune responses, our results confirm the role of REL in the germinal center reaction and provide evidence supporting the fact that genetic deregulation of c-Rel expression is most likely a primary event in the aggressive transformation of GC B-cells. Key points - REL provides a long-term competitive advantage allowing for GC B-cell persistence and continuous recirculation of AID-imprinted B-cells - AID-imprinted B-cells overexpressing REL can occasionally transform into aggressive B-cell lymphomas Explanation of the novelty By showing in a new dual-color mouse model that dysregulation of REL in a very limited pool of AID-imprinted B-cells confers a strong long-term competitive advantage in the context of repeated immune responses and may occasionally lead to transformation into an aggressive B- cell lymphoma, we provide for the first time experimental evidence supporting the fact that that REL is most likely a primary event in the aggressive transformation of germinal center B-cells

NLRP6 negatively regulates type 2 immune responses in mice

International audienceBackground: Inflammasomes are large protein complexes that assemble in the cytosol in response to danger such as tissue damage or infection. Following activation, inflammasomes trigger cell death and the release of biologically active forms of pro-inflammatory cytokines interleukin (IL)-1β and IL-18. NOD-like receptor family pyrin domain containing 6 (NLRP6) inflammasome is required for IL-18 secretion by intestinal epithelial cells, macrophages, and T cells, contributing to homeostasis and self-defense against pathogenic microbes. However, the involvement of NLRP6 in type 2 lung inflammation remains elusive.Methods: Wild-type (WT) and Nlrp6−/− mice were used. Birch pollen extract (BPE)-induced allergic lung inflammation, eosinophil recruitment, Th2-related cytokine and chemokine production, airway hyperresponsiveness, and lung histopathology, Th2 cell differentiation, GATA3, and Th2 cytokines expression, were determined. Nippostrongylus brasiliensis (Nb) infection, worm count in intestine, type 2 innate lymphoid cell (ILC2), and Th2 cells in lungs were evaluated.Results: We demonstrate in Nlrp6−/− mice that a mixed Th2/Th17 immune responses prevailed following birch pollen challenge with increased eosinophils, ILC2, Th2, and Th17 cell induction and reduced IL-18 production. Nippostrongylus brasiliensis infected Nlrp6−/− mice featured enhanced early expulsion of the parasite due to enhanced type 2 immune responses compared to WT hosts. In vitro, NLRP6 repressed Th2 polarization, as shown by increased Th2 cytokines and higher expression of the transcription factor GATA3 in the absence of NLRP6. Exogenous IL-18 administration partially reduced the enhanced airways inflammation in Nlrp6−/− mice.Conclusions: In summary, our data identify NLRP6 as a negative regulator of type 2 immune responses

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

Attempts to evaluate locus suicide recombination and its potential role in B cell negative selection in the mouse

International audienceINTRODUCTION: In mature B cells, activation-induced deaminase reshapes Ig genes through somatic hypermutation and class switch recombination of the Ig heavy chain (IgH) locus under control of its 3’ cis-regulatory region (3’RR). The 3’RR is itself transcribed and can undergo "locus suicide recombination" (LSR), then deleting the constant gene cluster and terminating IgH expression. The relative contribution of LSR to B cell negative selection remains to be determined. METHODS: Here, we set up a knock-in mouse reporter model for LSR events with the aim to get clearer insights into the circumstances triggering LSR. In order to explore the consequences of LSR defects, we reciprocally explored the presence of autoantibodies in various mutant mouse lines in which LSR was perturbed by the lack of Sµ or of the 3’RR. RESULTS: Evaluation of LSR events in a dedicated reporter mouse model showed their occurrence in various conditions of B cell activation, notably in antigen-experienced B cells Studies of mice with LSR defects evidenced increased amounts of self-reactive antibodies. DISCUSSION: While the activation pathways associated with LSR are diverse, in vivo as well as in vitro, this study suggests that LSR may contribute to the elimination of self-reactive B cells

Distinct B-Cell Specific Transcriptional Contexts of the BCL2 Oncogene Impact Pre-Malignant Development in Mouse Models

International audienceSimple Summary Beyond the classical t(14;18) translocation associated with follicular lymphoma, BCL2 is deregulated in multiple B-cell malignancies, including some cases of myeloma, and through diverse genetic anomalies. It is currently unclear how the various deregulation patterns mechanistically impact the phenotype of theses malignancies. We designed two different BCL2 deregulation models in transgenic mice, whereby the oncogene was either associated with the IgH3 ' RR superenhancer, as in t(14;18), or inserted into the kappa light chain locus. We compared the impact of these models on B-cell fate and lymphoid tissues. Linkage to the IgH superenhancer showed a quite specific impact on germinal center B cell populations. The Ig kappa model was much less specific and strongly boosted the plasma cell in-flow and the accumulation of long-lived plasma cells. Upregulated expression of the anti-apoptotic BCL2 oncogene is a common feature of various types of B-cell malignancies, from lymphoma to leukemia or myeloma. It is currently unclear how the various patterns of deregulation observed in pathology eventually impact the phenotype of malignant B cells and their microenvironment. Follicular lymphoma (FL) is the most common non-Hodgkin lymphoma arising from malignant germinal center (GC) B-cells, and its major hallmark is the t(14:18) translocation occurring in B cell progenitors and placing the BCL2 gene under the control of the immunoglobulin heavy chain locus regulatory region (IgH 3 ' RR), thus exposing it to constitutive expression and hypermutation. Translocation of BCL2 onto Ig light chain genes, BCL2 gene amplification, and other mechanisms yielding BCL2 over-expression are, in contrast, rare in FL and rather promote other types of B-cell lymphoma, leukemia, or multiple myeloma. In order to assess the impact of distinct BCL2 deregulation patterns on B-cell fate, two mouse models were designed that associated BCL2 and its full P1-P2 promoter region to either the IgH 3 ' RR, within a "3 ' RR-BCL2" transgene mimicking the situation seen in FL, or an Ig light chain locus context, through knock-in insertion at the Ig kappa locus ("Ig kappa-BCL2" model). While linkage to the IgH 3 ' RR mostly yielded expression in GC B-cells, the Ig kappa-driven up-regulation culminated in plasmablasts and plasma cells, boosting the plasma cell in-flow and the accumulation of long-lived plasma cells. These data demonstrate that the timing and level of BCL2 deregulation are crucial for the behavior of B cells inside GC, an observation that could strongly impact the lymphomagenesis process triggered by secondary genetic hits

Chronic Lung Infection Is IL-1R Independent, but Relies on MyD88 Signaling.

Cystic fibrosis is associated with chronic colonization and inflammation. The role of MyD88, the shared adapter protein of the proinflammatory TLR and IL-1R families, in chronic biofilm lung infection is unknown. We report that chronic lung infection with the clinical RP73 strain is associated with uncontrolled lung infection in complete MyD88-deficient mice with epithelial damage, inflammation, and rapid death. Then, we investigated whether alveolar or myeloid cells contribute to heightened sensitivity to infection. Using cell-specific, MyD88-deficient mice, we uncover that the MyD88 pathway in myeloid or alveolar epithelial cells is dispensable, suggesting that other cell types may control the high sensitivity of MyD88-deficient mice. By contrast, IL-1R1-deficient mice control chronic RP73 infection and IL-1β Ab blockade did not reduce host resistance. Therefore, the IL-1R1/MyD88 pathway is not involved, but other IL-1R or TLR family members need to be investigated. Our data strongly suggest that IL-1 targeted neutralizing therapies used to treat inflammatory diseases in patients unlikely reduce host resistance to chronic infection