Th17 Response and Inflammatory Autoimmune Diseases

The proinflammatory activity of T helper 17 (Th17) cells can be beneficial to the host during infection. However, uncontrolled or inappropriate Th17 activation has been linked to several autoimmune and autoinflammatory pathologies. Indeed, preclinical and clinical data show that Th17 cells are associated with several autoimmune diseases such as arthritis, multiple sclerosis, psoriasis, and lupus. Furthermore, targeting the interleukin-17 (IL-17) pathway has attenuated disease severity in preclinical models of autoimmune diseases. Interestingly, a recent report brings to light a potential role for Th17 cells in the autoinflammatory disorder adult-onset Still's disease (AOSD). Whether Th17 cells are the cause or are directly involved in AOSD remains to be shown. In this paper, we discuss the biology of Th17 cells, their role in autoimmune disease development, and in AOSD in particular, as well as the growing interest of the pharmaceutical industry in their use as therapeutic targets

Etude des propriétés biochimiques et immunomodulatrices des exosomes d'origine mastocytaire

Les mastocytes sont essentiellement connus comme étant des cellules cibles impliquées dans les mécanismes effecteurs de la réponse allergique. Il s'est révélé que cette cellule peut aussi jouer un rôle actif dans le contexte des réponses immunitaires innée et acquise. Au cours de ce travail, nous avons montré que le mastocyte peut utiliser un nouveau mode de communication intercellulaire en plus du contact cellulaire direct et de la sécrétion des cytokines, qui consiste en la libération de petites vésicules membranaires de 60 à 100 nm de diamètres appelés exosomes. Les exosomes sécrétés par les mBMMC et les lignées mastocytaires et libérés dans le surnageant de culture sont capables d'activer les lymphocytes B et T in vitro et in vivo indépendamment de l'antigène.PARIS5-BU-Necker : Fermée (751152101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Increased Immunogenicity of Mast Cell-Associated Antigens

International audienceBackground: Mouse bone marrow mast cells (BMMC) have been shown to induce lymphocyte activation through the release of membrane vesicles called exosomes stored in intracytoplasmic granules. The aim of this study is to characterize further the immunostimulatory properties of these exosomes in vivo. Methods: Exosomes isolated from BMMC loaded with bovine serum albumin (BSA) were injected into mice in the absence of adjuvants and antigen-specific antibody responses were measured. Results: Exosomes are located in the endocytic pathway since BSA, under its native as well as degraded form, was found to be associated with these compartments. Exosomes were highly efficient in inducing primary and secondary IgG1 and IgG2a antibody responses, suggesting that naturally occurring adjuvants are present in these compartments. Among several routes of immunization tested, intradermal and subcutaneous injections were found to be the most efficient. Conclusion: This new mechanism may account for a potential role of MC in the monitoring of tissue environment for the presence of non-self-antigens and in the development of specific immunity

Mast Cell-Derived Exosomes Induce Phenotypic and Functional Maturation of Dendritic Cells and Elicit Specific Immune Responses In Vivo

International audienceMast cells (MCs) are considered major players in IgE-mediated allergic responses, but have also recently been recognized as active participants in innate as well as specific immune responses. Recent work provided evidence that MCs are able to activate B and T lymphocytes through the release of vesicles called exosomes. Here we demonstrate that exosomes, which are located in the endocytic pathway, harbor exogenous Ags that associate with other molecules endowed with immunomodulatory functions, including 60- and 70-kDa heat shock proteins. Administration to naive mice of Ag-containing exosomes in the absence of conventional adjuvants elicits specific Ab responses across the MHC II haplotype barrier. We demonstrate that MC-exosomes induce immature dendritic cells (DCs) to up-regulate MHC class II, CD80, CD86, and CD40 molecules and to acquire potent Ag-presenting capacity to T cells. Uptake and processing of Ag-associated exosomes by endogenous DCs were also demonstrated. Finally, exosome-associated heat shock proteins are critical for the acquisition by DCs of the Ag-presenting function. This work demonstrates a heretofore unrecognized collaborative interaction between MCs and DCs leading to the elicitation of specific immune responses

Id1 represses osteoclast-dependent transcription and affects bone formation and hematopoiesis.

The bone-bone marrow interface is an area of the bone marrow microenvironment in which both bone remodeling cells, osteoblasts and osteoclasts, and hematopoietic cells are anatomically juxtaposed. The close proximity of these cells naturally suggests that they interact with one another, but these interactions are just beginning to be characterized.An Id1(-/-) mouse model was used to assess the role of Id1 in the bone marrow microenvironment. Micro-computed tomography and fracture tests showed that Id1(-/-) mice have reduced bone mass and increased bone fragility, consistent with an osteoporotic phenotype. Osteoclastogenesis and pit formation assays revealed that loss of Id1 increased osteoclast differentiation and resorption activity, both in vivo and in vitro, suggesting a cell autonomous role for Id1 as a negative regulator of osteoclast differentiation. Examination by flow cytometry of the hematopoietic compartment of Id1(-/-) mice showed an increase in myeloid differentiation. Additionally, we found increased expression of osteoclast genes, TRAP, Oscar, and CTSK in the Id1(-/-) bone marrow microenvironment. Lastly, transplantation of wild-type bone marrow into Id1(-/-) mice repressed TRAP, Oscar, and CTSK expression and activity and rescued the hematopoietic and bone phenotype in these mice.In conclusion, we demonstrate an osteoporotic phenotype in Id1(-/-) mice and a mechanism for Id1 transcriptional control of osteoclast-associated genes. Our results identify Id1 as a principal player responsible for the dynamic cross-talk between bone and bone marrow hematopoietic cells

Id1 suppresses anti-tumour immune responses and promotes tumour progression by impairing myeloid cell maturation

A central mechanism of tumour progression and metastasis involves the generation of an immunosuppressive 'macroenvironment' mediated in part through tumour-secreted factors. Here we demonstrate that upregulation of the Inhibitor of Differentiation 1 (Id1), in response to tumour-derived factors, such as TGFβ, is responsible for the switch from dendritic cell (DC) differentiation to myeloid-derived suppressor cell expansion during tumour progression. Genetic inactivation of Id1 largely corrects the myeloid imbalance, whereas Id1 overexpression in the absence of tumour-derived factors re-creates it. Id1 overexpression leads to systemic immunosuppression by downregulation of key molecules involved in DC differentiation and suppression of CD8 T-cell proliferation, thus promoting primary tumour growth and metastatic progression. Furthermore, advanced melanoma patients have increased plasma TGFβ levels and express higher levels of ID1 in myeloid peripheral blood cells. This study reveals a critical role for Id1 in suppressing the anti-tumour immune response during tumour progression and metastasis.We thank the members of our laboratories for their helpful discussions. We thank Dr. Sergei Rudchenko and Mihaela Barbu-Stevanovic at the Hospital for Special Surgery Fannie E. Rippel Foundation Flow Cytometry Core Facility for expert cell sorting. Our work was supported by grants from the UK-US Fulbright Commission (M.P.), the Garrett B. Smith Foundation (M.P.), 5th District AHEPA Cancer Research Foundation (M.P. and D.L.), the Children's Cancer and Blood Foundation (D.L.), The Hartwell Foundation (D.L.), The Manning Foundation (D.L.), Pediatric Oncology Experimental Therapeutics Investigator's Consortium (D.L.), Stavros S. Niarchos Foundation (D.L.), Champalimaud Foundation (D.L.), The Nancy C. and Daniel P. Paduano Foundation (D.L. and H.P.), The Mary Kay Foundation (D.L.), The Malcolm Hewitt Wiener Foundation (D.L.), National Foundation for Cancer Research (D.L.), Susan G. Komen for the Cure (D.L.), Luso-American Development Foundation (M.d.R.A.), American Portuguese Biomedical Research Fund (M.d.R.A.) and D.L. Fundacao para a Ciencia e a Tecnologia (D.L.), Beth Tortolani Foundation (D.L. and J.B.) and Theodore A Rapp Foundation (D.L.).S

Evaluation of the capacities of mouse TCR profiling from short read RNA-seq data.

Profiling T cell receptor (TCR) repertoire via short read transcriptome sequencing (RNA-Seq) has a unique advantage of probing simultaneously TCRs and the genome-wide RNA expression of other genes. However, compared to targeted amplicon approaches, the shorter read length is more prone to mapping error. In addition, only a small percentage of the genome-wide reads may cover the TCR loci and thus the repertoire could be significantly under-sampled. Although this approach has been applied in a few studies, the utility of transcriptome sequencing in probing TCR repertoires has not been evaluated extensively. Here we present a systematic assessment of RNA-Seq in TCR profiling. We evaluate the power of both Fluidigm C1 full-length single cell RNA-Seq and bulk RNA-Seq in characterizing the repertoires of different diversities under either naïve conditions or after immunogenic challenges. Standard read length and sequencing coverage were employed so that the evaluation was conducted in accord with the current RNA-Seq practices. Despite high sequencing depth in bulk RNA-Seq, we encountered difficulty quantifying TCRs with low transcript abundance (<1%). Nevertheless, top enriched TCRs with an abundance of 1-3% or higher can be faithfully detected and quantified. When top TCR sequences are of interest and transcriptome sequencing is available, it is worthwhile to conduct a TCR profiling using the RNA-Seq data