Project description:Overall, this work describes the largest cohort of patients with RAG mutations and an associated phenotype consisting of combined immunodeficiency and granulomatous lesions and/or autoimmunity (CID-G/AI). By using multiple methods (microarray, ELISA and multiplex bead technology), we have consistently identified a distinctive signature of anti-cytokine antibodies in patients with RAG-dependent immunodeficiencies, especially in those with CID-G/AI and a history of severe viral infections. These autoantibodies were not detected in a large panel of patients with other forms of primary immunodeficiency, and may therefore represent a novel biomarker panel of this condition. Known autoantigens, cytokines, chemokines, growth factors and receptors were printed onto microarrays. All targets were printed in triplicate. Arrays were probed with diluted plasma and autoantibodies were detected with a AF647 conjugated anti-human IgG secondary.
Project description:Overall, this work describes the largest cohort of patients with RAG mutations and an associated phenotype consisting of combined immunodeficiency and granulomatous lesions and/or autoimmunity (CID-G/AI). By using multiple methods (microarray, ELISA and multiplex bead technology), we have consistently identified a distinctive signature of anti-cytokine antibodies in patients with RAG-dependent immunodeficiencies, especially in those with CID-G/AI and a history of severe viral infections. These autoantibodies were not detected in a large panel of patients with other forms of primary immunodeficiency, and may therefore represent a novel biomarker panel of this condition.
Project description:Patients with mutations of the recombination-activating genes (RAG) present with diverse clinical phenotypes, including severe combined immune deficiency (SCID), autoimmunity, and inflammation. However, the incidence and extent of immune dysregulation in RAG-dependent immunodeficiency have not been studied in detail. Here, we have demonstrated that patients with hypomorphic RAG mutations, especially those with delayed-onset combined immune deficiency and granulomatous/autoimmune manifestations (CID-G/AI), produce a broad spectrum of autoantibodies. Neutralizing anti-IFN-? or anti-IFN-? antibodies were present at detectable levels in patients with CID-G/AI who had a history of severe viral infections. As this autoantibody profile is not observed in a wide range of other primary immunodeficiencies, we hypothesized that recurrent or chronic viral infections may precipitate or aggravate immune dysregulation in RAG-deficient hosts. We repeatedly challenged Rag1S723C/S723C mice, which serve as a model of leaky SCID, with agonists of the virus-recognizing receptors TLR3/MDA5, TLR7/-8, and TLR9 and found that this treatment elicits autoantibody production. Altogether, our data demonstrate that immune dysregulation is an integral aspect of RAG-associated immunodeficiency and indicate that environmental triggers may modulate the phenotypic expression of autoimmune manifestations.
Project description:The identification of target antigens recognized by monoclonal antibodies that have been derived from oligoclonal band IgG of CSF samples from multiple sclerosis patients.
Project description:Endogenous retroviruses (ERV), comprising a substantial portion of the vertebrate genome, are remnants of ancient genetic invaders. ERV with near-intact coding potential reactivate in B cell-deficient mice. Here, we employed an antigen-baiting strategy to enrich B cells reactive to ERV surface antigens. We identified ERV-reactive B-1 cells expressing germline-encoded natural IgM antibodies in naïve mice, the level of which further increases upon innate immune sensor stimulation. B cell receptor repertoire profiling of ERV-reactive B-1 cells revealed increased usage of Igh VH gene that gives rise to glycan-specific antibodies targeting terminal N-acetylglucosamine moieties on ERV glycoproteins, which further engage the complement pathway to protect the host from ERV emergence. These same antibodies also recognize glycoproteins of other enveloped viruses, but not self-proteins. These results reveal an innate antiviral mechanism of germline-encoded antibodies with broad reactivity to enveloped viruses, whose absence leads to the emergence of infectious ERV.
Project description:Intratumoral B cell responses are associated with more favorable clinical outcomes in human pancreatic ductal adenocarcinoma cancer (PDAC). However, the antigens driving these B cell responses are largely unknown. We sought to discover these antigens by using single-cell RNA (sc-RNASeq) and immunoglobulin (Ig) sequencing of tumor-infiltrating immune cells from seven primary PDAC samples. We identified activated T and B cell responses and evidence of germinal center reactions. Ig sequencing identified plasma cell (PC) clones expressing isotype-switched and hyper-mutated Igs, suggesting the occurrence of T cell-dependent B cell responses. We assessed the reactivity of 41 recombinant antibodies that represented the products of 235 PCs and 12 B cells toward multiple cell lines and PDAC tissue, and identified frequent staining of intracellular self-antigens. Three of these antigens were identified: the filamentous actin (F-actin), the nucleic protein, RUVBL2, and the mitochondrial protein, HSPD1. Antibody titers to F-actin and HSPD1 were frequently elevated in the plasma of PDAC patients, and also detectable in healthy donors. Thus, PCs in PDAC frequently produce auto-antibodies reacting with intracellular self-antigens, which may result from promotion of pre-existing autoreactive B cell responses. These observations indicate that the chronic inflammatory microenvironment of PDAC can support the adaptive immune responses.
Project description:By their impact on nuclear organisation, enhancers are master regulators of cell fate. We thus developed double Emu-RAG-deficient, 3’RR-RAG-deficient mice and KOKI-RAG-deficient mice to investigate a potential transcriptional cross-talk between Emu and 3'RR enhancers at the pro-B cell stage.
Project description:The genomes of most protozoa encode families of variant surface antigens, whose mutually exclusive changes in expression allow parasitic microorganisms to evade the host immune response1. It is widely assumed that antigenic variation in protozoan parasites is accomplished by the spontaneous appearance within the population of cells expressing antigenic variants that escape antibody-mediated cytotoxicity1,2. Here we show, both in vitro and in animal infections, that antibodies to Variant-specific Surface Proteins (VSPs) of the intestinal parasite Giardia lamblia are not cytotoxic; instead, anti-VSP antibodies induce VSP clustering into microdomains, triggering a massive release of microvesicles carrying the original VSP and switching in expression to different VSPs by a calcium-dependent process. Surface microvesiculization and antigenic switching are also stimulated when Trypanosoma brucei and Tetrahymena thermophila are confronted to antibodies directed to their GPI-anchored variable surface glycoproteins. This novel mechanism of antigen clearance throughout its release into microvesicles coupled to the stochastic induction of new phenotypic variants not only changes the current paradigm of spontaneous antigenic switching but also provides a new framework for understanding the course of infections as a host/parasite adaptive process.
Project description:The Rag GTPases recruit the master kinase mTORC1 to lysosomes to regulate cell growth and proliferation in response to amino acid availability. The nucleotide state of Rag heterodimers is critical for their association with mTORC1. Our cryo-EM structure of RagA/RagC in complex with mTORC1 shows the details of RagA/C binding to the RAPTOR subunit of mTORC1 and explains why only the RagAGTP/RagCGDP nucleotide state binds mTORC1. Previous kinetic studies suggested that GTP binding to one Rag locks the heterodimer to prevent GTP binding to the other. Our crystal structures and dynamics show the mechanism for this locking, and explain how oncogenic hotspot mutations disrupt this process. In contrast to allosteric activation by RHEB, Rag heterodimer binding does not change mTORC1 conformation and activates mTORC1 by targeting it to lysosomes.