ABSTRACT
The role of the autoimmune regulator (Aire) in central immune tolerance and thymic self-representation was first described more than 20 years ago, but fascinating new insights into its biology continue to emerge, particularly in the era of advanced single-cell genomics. We briefly describe the role of human genetics in the discovery of Aire, as well as insights into its function gained from genotype-phenotype correlations and the spectrum of Aire-associated autoimmunity-including insights from patients with Aire mutations with broad and diverse implications for human health. We then highlight emerging trends in Aire biology, focusing on three topic areas. First, we discuss medullary thymic epithelial diversity and the role of Aire in thymic epithelial development. Second, we highlight recent developments regarding the molecular mechanisms of Aire and its binding partners. Finally, we describe the rapidly evolving biology of the identity and function of extrathymic Aire-expressing cells (eTACs), and a novel eTAC subset called Janus cells, as well as their potential roles in immune homeostasis.
Subject(s)
AIRE Protein , Autoimmunity , Transcription Factors , Humans , Transcription Factors/metabolism , Transcription Factors/genetics , Animals , Thymus Gland/immunology , Thymus Gland/metabolism , Mutation , Immune Tolerance , Epithelial Cells/metabolism , Epithelial Cells/immunology , Autoimmune Diseases/immunology , Autoimmune Diseases/genetics , Autoimmune Diseases/metabolismABSTRACT
Monogenic autoimmune syndromes provide a rare yet powerful glimpse into the fundamental mechanisms of immunologic tolerance. Such syndromes reveal not only the contribution of an individual breakpoint in tolerance but also patterns in the pathogenesis of autoimmunity. Disturbances in innate immunity, a system built for ubiquitous sensing of danger signals, tend to generate systemic autoimmunity. For example, defects in the clearance of self-antigens and chronic stimulation of type 1 interferons lead to the systemic autoimmunity seen in C1q deficiency, SPENCDI, and AGS. In contrast, disturbances of adaptive immunity, which is built for antigen specificity, tend to produce organ-specific autoimmunity. Thus, the loss of lymphocyte homeostasis, whether through defects in apoptosis, suppression, or negative selection, leads to organ-specific autoimmunity in ALPS, IPEX, and APS1. We discuss the unique mechanisms of disease in these prominent syndromes as well as how they contribute to the spectrum of organ-specific or systemic autoimmunity. The continued study of rare variants in autoimmune disease will inform future investigations and treatments directed at rare and common autoimmune diseases alike.
Subject(s)
Autoimmune Diseases/genetics , Autoimmune Diseases/immunology , Autoimmunity/genetics , Animals , Humans , Immunologic Deficiency Syndromes/genetics , Immunologic Deficiency Syndromes/immunology , Organ Specificity/genetics , Organ Specificity/immunologyABSTRACT
The developmental programs that generate a broad repertoire of regulatory T cells (Treg cells) able to respond to both self antigens and non-self antigens remain unclear. Here we found that mature Treg cells were generated through two distinct developmental programs involving CD25+ Treg cell progenitors (CD25+ TregP cells) and Foxp3lo Treg cell progenitors (Foxp3lo TregP cells). CD25+ TregP cells showed higher rates of apoptosis and interacted with thymic self antigens with higher affinity than did Foxp3lo TregP cells, and had a T cell antigen receptor repertoire and transcriptome distinct from that of Foxp3lo TregP cells. The development of both CD25+ TregP cells and Foxp3lo TregP cells was controlled by distinct signaling pathways and enhancers. Transcriptomics and histocytometric data suggested that CD25+ TregP cells and Foxp3lo TregP cells arose by coopting negative-selection programs and positive-selection programs, respectively. Treg cells derived from CD25+ TregP cells, but not those derived from Foxp3lo TregP cells, prevented experimental autoimmune encephalitis. Our findings indicate that Treg cells arise through two distinct developmental programs that are both required for a comprehensive Treg cell repertoire capable of establishing immunotolerance.
Subject(s)
Cell Differentiation/immunology , Encephalomyelitis, Autoimmune, Experimental/immunology , Lymphoid Progenitor Cells/physiology , T-Lymphocytes, Regulatory/physiology , Thymus Gland/growth & development , Animals , Autoantigens/immunology , Colitis/immunology , Disease Models, Animal , Forkhead Transcription Factors/genetics , Forkhead Transcription Factors/metabolism , Freund's Adjuvant/administration & dosage , Freund's Adjuvant/immunology , Humans , Immune Tolerance/immunology , Interleukin-2 Receptor alpha Subunit/metabolism , Lymphoid Progenitor Cells/transplantation , Mice , Mice, Transgenic , Mycobacterium tuberculosis/immunology , Myelin-Oligodendrocyte Glycoprotein/administration & dosage , Myelin-Oligodendrocyte Glycoprotein/immunology , Peptide Fragments/administration & dosage , Peptide Fragments/immunology , Signal Transduction , Specific Pathogen-Free Organisms , Thymus Gland/cytology , Thymus Gland/immunologyABSTRACT
Although the thymus has long been recognized as a key organ for T cell selection, the intricate details linking these selection events to human autoimmunity have been challenging to decipher. Over the last two decades, there has been rapid progress in understanding the role of thymic tolerance mechanisms in autoimmunity through genetics. Here we review some of the recent progress in understanding key thymic tolerance processes that are critical for preventing autoimmune disease.
Subject(s)
Autoimmunity , Immune Tolerance , Thymus Gland/immunology , Animals , Autoimmune Diseases/immunology , CD8-Positive T-Lymphocytes/immunology , Humans , Mice , Proteasome Endopeptidase Complex/metabolism , T-Lymphocytes, Regulatory/immunology , Transcription Factors/physiology , AIRE ProteinABSTRACT
Here, we introduce the Tabulae Paralytica-a compilation of four atlases of spinal cord injury (SCI) comprising a single-nucleus transcriptome atlas of half a million cells, a multiome atlas pairing transcriptomic and epigenomic measurements within the same nuclei, and two spatial transcriptomic atlases of the injured spinal cord spanning four spatial and temporal dimensions. We integrated these atlases into a common framework to dissect the molecular logic that governs the responses to injury within the spinal cord1. The Tabulae Paralytica uncovered new biological principles that dictate the consequences of SCI, including conserved and divergent neuronal responses to injury; the priming of specific neuronal subpopulations to upregulate circuit-reorganizing programs after injury; an inverse relationship between neuronal stress responses and the activation of circuit reorganization programs; the necessity of re-establishing a tripartite neuroprotective barrier between immune-privileged and extra-neural environments after SCI and a failure to form this barrier in old mice. We leveraged the Tabulae Paralytica to develop a rejuvenative gene therapy that re-established this tripartite barrier, and restored the natural recovery of walking after paralysis in old mice. The Tabulae Paralytica provides a window into the pathobiology of SCI, while establishing a framework for integrating multimodal, genome-scale measurements in four dimensions to study biology and medicine.
Subject(s)
Cell Nucleus , Epigenomics , Multiomics , Neurons , Single-Cell Analysis , Spinal Cord Injuries , Transcriptome , Animals , Female , Male , Mice , Atlases as Topic , Cell Nucleus/metabolism , Neurons/pathology , Neurons/metabolism , Paralysis/genetics , Paralysis/pathology , Paralysis/rehabilitation , Paralysis/therapy , Recovery of Function , Spinal Cord/pathology , Spinal Cord Injuries/genetics , Spinal Cord Injuries/pathology , Spinal Cord Injuries/rehabilitation , Spinal Cord Injuries/therapy , Walking , Anatomy, Artistic , Neural Pathways , Genetic TherapyABSTRACT
Multisystem inflammatory syndrome in children (MIS-C) is a severe, post-infectious sequela of SARS-CoV-2 infection1,2, yet the pathophysiological mechanism connecting the infection to the broad inflammatory syndrome remains unknown. Here we leveraged a large set of samples from patients with MIS-C to identify a distinct set of host proteins targeted by patient autoantibodies including a particular autoreactive epitope within SNX8, a protein involved in regulating an antiviral pathway associated with MIS-C pathogenesis. In parallel, we also probed antibody responses from patients with MIS-C to the complete SARS-CoV-2 proteome and found enriched reactivity against a distinct domain of the SARS-CoV-2 nucleocapsid protein. The immunogenic regions of the viral nucleocapsid and host SNX8 proteins bear remarkable sequence similarity. Consequently, we found that many children with anti-SNX8 autoantibodies also have cross-reactive T cells engaging both the SNX8 and the SARS-CoV-2 nucleocapsid protein epitopes. Together, these findings suggest that patients with MIS-C develop a characteristic immune response to the SARS-CoV-2 nucleocapsid protein that is associated with cross-reactivity to the self-protein SNX8, demonstrating a mechanistic link between the infection and the inflammatory syndrome, with implications for better understanding a range of post-infectious autoinflammatory diseases.
Subject(s)
Antibodies, Viral , Autoantibodies , COVID-19 , Cross Reactions , Epitopes , Molecular Mimicry , SARS-CoV-2 , Systemic Inflammatory Response Syndrome , Child , Humans , Antibodies, Viral/immunology , Autoantibodies/immunology , Coronavirus Nucleocapsid Proteins/chemistry , Coronavirus Nucleocapsid Proteins/immunology , COVID-19/immunology , COVID-19/virology , COVID-19/complications , Cross Reactions/immunology , Epitopes/immunology , Epitopes/chemistry , Molecular Mimicry/immunology , Phosphoproteins/chemistry , Phosphoproteins/immunology , SARS-CoV-2/chemistry , SARS-CoV-2/immunology , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Sorting Nexins/chemistry , Sorting Nexins/immunology , Systemic Inflammatory Response Syndrome/immunology , Systemic Inflammatory Response Syndrome/pathology , Systemic Inflammatory Response Syndrome/virology , T-Lymphocytes/immunologyABSTRACT
Studies of repertoires of mouse monoclonal CD4(+) T cells have revealed several mechanisms of self-tolerance; however, which mechanisms operate in normal repertoires is unclear. Here we studied polyclonal CD4(+) T cells specific for green fluorescent protein expressed in various organs, which allowed us to determine the effects of specific expression patterns on the same epitope-specific T cells. Peptides presented uniformly by thymic antigen-presenting cells were tolerated by clonal deletion, whereas peptides excluded from the thymus were ignored. Peptides with limited thymic expression induced partial clonal deletion and impaired effector T cell potential but enhanced regulatory T cell potential. These mechanisms were also active for T cell populations specific for endogenously expressed self antigens. Thus, the immunotolerance of polyclonal CD4(+) T cells was maintained by distinct mechanisms, according to self-peptide expression patterns.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , Gene Expression , Immune Tolerance , Peptides/genetics , Peptides/immunology , Amino Acid Sequence , Animals , Antigen-Presenting Cells/immunology , Antigen-Presenting Cells/metabolism , Autoantigens/chemistry , Autoantigens/genetics , Autoantigens/immunology , Autoimmunity , Clonal Deletion/genetics , Clonal Deletion/immunology , Epitopes, T-Lymphocyte/chemistry , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Female , Genes, Reporter , Mice , Mice, Transgenic , Peptides/chemistry , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/metabolism , Thymus Gland/immunology , Thymus Gland/metabolismABSTRACT
Regulatory T (Treg) cells maintain immune tolerance through the master transcription factor forkhead box P3 (FOXP3), which is crucial for Treg cell function and homeostasis. We identified an IPEX (immune dysregulation polyendocrinopathy enteropathy X-linked) syndrome patient with a FOXP3 mutation in the domain swap interface of the protein. Recapitulation of this Foxp3 variant in mice led to the development of an autoimmune syndrome consistent with an unrestrained T helper type 2 (Th2) immune response. Genomic analysis of Treg cells by RNA-sequencing, Foxp3 chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-sequencing), and H3K27ac-HiChIP revealed a specific de-repression of the Th2 transcriptional program leading to the generation of Th2-like Treg cells that were unable to suppress extrinsic Th2 cells. Th2-like Treg cells showed increased intra-chromosomal interactions in the Th2 locus, leading to type 2 cytokine production. These findings identify a direct role for Foxp3 in suppressing Th2-like Treg cells and implicate additional pathways that could be targeted to restrain Th2 trans-differentiated Treg cells.
Subject(s)
Forkhead Transcription Factors/immunology , Mutation , T-Lymphocytes, Regulatory/immunology , Th2 Cells/immunology , Animals , Cell Differentiation/genetics , Cell Differentiation/immunology , Child , Cytokines/genetics , Cytokines/immunology , Cytokines/metabolism , Forkhead Transcription Factors/genetics , Forkhead Transcription Factors/metabolism , Gene Expression Regulation , Genetic Diseases, X-Linked/genetics , Genetic Diseases, X-Linked/immunology , Genetic Diseases, X-Linked/metabolism , Humans , Male , Mice, Inbred C57BL , Mice, Knockout , Polyendocrinopathies, Autoimmune/genetics , Polyendocrinopathies, Autoimmune/immunology , Polyendocrinopathies, Autoimmune/metabolism , T-Lymphocytes, Regulatory/metabolism , Th2 Cells/metabolismABSTRACT
The mutualistic relationship of gut-resident microbiota and the host immune system promotes homeostasis that ensures maintenance of the microbial community and of a largely non-aggressive immune cell compartment1,2. The consequences of disturbing this balance include proximal inflammatory conditions, such as Crohn's disease, and systemic illnesses. This equilibrium is achieved in part through the induction of both effector and suppressor arms of the adaptive immune system. Helicobacter species induce T regulatory (Treg) and T follicular helper (TFH) cells under homeostatic conditions, but induce inflammatory T helper 17 (TH17) cells when induced Treg (iTreg) cells are compromised3,4. How Helicobacter and other gut bacteria direct T cells to adopt distinct functions remains poorly understood. Here we investigated the cells and molecular components required for iTreg cell differentiation. We found that antigen presentation by cells expressing RORγt, rather than by classical dendritic cells, was required and sufficient for induction of Treg cells. These RORγt+ cells-probably type 3 innate lymphoid cells and/or Janus cells5-require the antigen-presentation machinery, the chemokine receptor CCR7 and the TGFß activator αv integrin. In the absence of any of these factors, there was expansion of pathogenic TH17 cells instead of iTreg cells, induced by CCR7-independent antigen-presenting cells. Thus, intestinal commensal microbes and their products target multiple antigen-presenting cells with pre-determined features suited to directing appropriate T cell differentiation programmes, rather than a common antigen-presenting cell that they endow with appropriate functions.
Subject(s)
Cell Differentiation , Gastrointestinal Microbiome , Nuclear Receptor Subfamily 1, Group F, Member 3 , T-Lymphocytes, Regulatory , Dendritic Cells/immunology , Gastrointestinal Microbiome/immunology , Homeostasis , Immunity, Innate , Integrin alphaV/metabolism , Nuclear Receptor Subfamily 1, Group F, Member 3/metabolism , Receptors, CCR7/metabolism , T-Lymphocytes, Regulatory/cytology , T-Lymphocytes, Regulatory/immunology , Th17 Cells/immunology , Transforming Growth Factor beta/metabolism , Antigen Presentation/immunology , Antigen-Presenting Cells/cytology , Antigen-Presenting Cells/immunologyABSTRACT
Multiple sclerosis (MS) is a heterogenous autoimmune disease in which autoreactive lymphocytes attack the myelin sheath of the central nervous system. B lymphocytes in the cerebrospinal fluid (CSF) of patients with MS contribute to inflammation and secrete oligoclonal immunoglobulins1,2. Epstein-Barr virus (EBV) infection has been epidemiologically linked to MS, but its pathological role remains unclear3. Here we demonstrate high-affinity molecular mimicry between the EBV transcription factor EBV nuclear antigen 1 (EBNA1) and the central nervous system protein glial cell adhesion molecule (GlialCAM) and provide structural and in vivo functional evidence for its relevance. A cross-reactive CSF-derived antibody was initially identified by single-cell sequencing of the paired-chain B cell repertoire of MS blood and CSF, followed by protein microarray-based testing of recombinantly expressed CSF-derived antibodies against MS-associated viruses. Sequence analysis, affinity measurements and the crystal structure of the EBNA1-peptide epitope in complex with the autoreactive Fab fragment enabled tracking of the development of the naive EBNA1-restricted antibody to a mature EBNA1-GlialCAM cross-reactive antibody. Molecular mimicry is facilitated by a post-translational modification of GlialCAM. EBNA1 immunization exacerbates disease in a mouse model of MS, and anti-EBNA1 and anti-GlialCAM antibodies are prevalent in patients with MS. Our results provide a mechanistic link for the association between MS and EBV and could guide the development of new MS therapies.
Subject(s)
Epstein-Barr Virus Infections , Multiple Sclerosis , Animals , B-Lymphocytes , Cell Adhesion Molecules, Neuron-Glia , Epstein-Barr Virus Nuclear Antigens , Herpesvirus 4, Human , Humans , Mice , Nerve Tissue ProteinsABSTRACT
BACKGROUND: Autoimmune polyendocrine syndrome type 1 (APS-1) is a life-threatening, autosomal recessive syndrome caused by autoimmune regulator (AIRE) deficiency. In APS-1, self-reactive T cells escape thymic negative selection, infiltrate organs, and drive autoimmune injury. The effector mechanisms governing T-cell-mediated damage in APS-1 remain poorly understood. METHODS: We examined whether APS-1 could be classified as a disease mediated by interferon-γ. We first assessed patients with APS-1 who were participating in a prospective natural history study and evaluated mRNA and protein expression in blood and tissues. We then examined the pathogenic role of interferon-γ using Aire-/-Ifng-/- mice and Aire-/- mice treated with the Janus kinase (JAK) inhibitor ruxolitinib. On the basis of our findings, we used ruxolitinib to treat five patients with APS-1 and assessed clinical, immunologic, histologic, transcriptional, and autoantibody responses. RESULTS: Patients with APS-1 had enhanced interferon-γ responses in blood and in all examined autoimmunity-affected tissues. Aire-/- mice had selectively increased interferon-γ production by T cells and enhanced interferon-γ, phosphorylated signal transducer and activator of transcription 1 (pSTAT1), and CXCL9 signals in multiple organs. Ifng ablation or ruxolitinib-induced JAK-STAT blockade in Aire-/- mice normalized interferon-γ responses and averted T-cell infiltration and damage in organs. Ruxolitinib treatment of five patients with APS-1 led to decreased levels of T-cell-derived interferon-γ, normalized interferon-γ and CXCL9 levels, and remission of alopecia, oral candidiasis, nail dystrophy, gastritis, enteritis, arthritis, Sjögren's-like syndrome, urticaria, and thyroiditis. No serious adverse effects from ruxolitinib were identified in these patients. CONCLUSIONS: Our findings indicate that APS-1, which is caused by AIRE deficiency, is characterized by excessive, multiorgan interferon-γ-mediated responses. JAK inhibition with ruxolitinib in five patients showed promising results. (Funded by the National Institute of Allergy and Infectious Diseases and others.).
Subject(s)
AIRE Protein , Interferon-gamma , Janus Kinase Inhibitors , Polyendocrinopathies, Autoimmune , Adult , Animals , Female , Humans , Male , Mice , AIRE Protein/deficiency , AIRE Protein/genetics , AIRE Protein/immunology , Autoantibodies/blood , Autoantibodies/immunology , Chemokine CXCL9/genetics , Interferon-gamma/genetics , Interferon-gamma/immunology , Janus Kinase Inhibitors/therapeutic use , Mice, Knockout , Nitriles/therapeutic use , Polyendocrinopathies, Autoimmune/genetics , Polyendocrinopathies, Autoimmune/drug therapy , Polyendocrinopathies, Autoimmune/immunology , Pyrazoles/therapeutic use , Pyrazoles/pharmacology , Pyrimidines/therapeutic use , T-Lymphocytes/immunology , Transcription Factors/genetics , Transcription Factors/immunology , Pilot Projects , Disease Models, Animal , Child , Adolescent , Middle AgedABSTRACT
CD4+ T cells recognize peptide antigens presented on class II major histocompatibility complex (MHC-II) molecules to carry out their function. The remarkable diversity of T cell receptor sequences and lack of antigen discovery approaches for MHC-II make profiling the specificities of CD4+ T cells challenging. We have expanded our platform of signaling and antigen-presenting bifunctional receptors to encode MHC-II molecules presenting covalently linked peptides (SABR-IIs) for CD4+ T cell antigen discovery. SABR-IIs can present epitopes to CD4+ T cells and induce signaling upon their recognition, allowing a readable output. Furthermore, the SABR-II design is modular in signaling and deployment to T cells and B cells. Here, we demonstrate that SABR-IIs libraries presenting endogenous and non-contiguous epitopes can be used for antigen discovery in the context of type 1 diabetes. SABR-II libraries provide a rapid, flexible, scalable and versatile approach for de novo identification of CD4+ T cell ligands from single-cell RNA sequencing data using experimental and computational approaches.
Subject(s)
CD4-Positive T-Lymphocytes , Epitopes, T-Lymphocyte , Histocompatibility Antigens Class II , CD4-Positive T-Lymphocytes/immunology , Epitopes, T-Lymphocyte/immunology , Animals , Histocompatibility Antigens Class II/immunology , Histocompatibility Antigens Class II/chemistry , Mice , Humans , Diabetes Mellitus, Type 1/immunology , Peptides/immunology , Peptides/chemistry , Antigen Presentation/immunology , Receptors, Antigen, T-Cell/immunology , Mice, Inbred NOD , Single-Cell Analysis/methodsABSTRACT
The development of T cell tolerance in the thymus requires the presentation of host proteins by multiple antigen-presenting cell (APC) types. However, the importance of transferring host antigens from transcription factor AIRE-dependent medullary thymic epithelial cells (mTECs) to bone marrow (BM) APCs is unknown. We report that antigen was primarily transferred from mTECs to CD8α+ dendritic cells (DCs) and showed that CD36, a scavenger receptor selectively expressed on CD8α+ DCs, mediated the transfer of cell-surface, but not cytoplasmic, antigens. The absence of CD8α+ DCs or CD36 altered thymic T cell selection, as evidenced by TCR repertoire analysis and the loss of allo-tolerance in murine allogeneic BM transplantation (allo-BMT) studies. Decreases in these DCs and CD36 expression in peripheral blood of human allo-BMT patients correlated with graft-versus-host disease. Our findings suggest that CD36 facilitates transfer of mTEC-derived cell-surface antigen on CD8α+ DCs to promote tolerance to host antigens during homeostasis and allo-BMT.
Subject(s)
Antigens, Surface/immunology , CD36 Antigens/immunology , Immune Tolerance/immunology , Receptors, Antigen, T-Cell/immunology , T-Lymphocytes, Regulatory/immunology , Thymus Gland/immunology , Animals , Antigens, Surface/metabolism , Bone Marrow Transplantation , CD36 Antigens/genetics , CD36 Antigens/metabolism , CD8 Antigens/immunology , CD8 Antigens/metabolism , Dendritic Cells/immunology , Dendritic Cells/metabolism , Epithelial Cells/immunology , Epithelial Cells/metabolism , Mice, Inbred BALB C , Mice, Knockout , Mice, Transgenic , Receptors, Antigen, T-Cell/metabolism , T-Lymphocytes, Regulatory/metabolism , Thymus Gland/metabolism , Transplantation, HomologousABSTRACT
In the small intestine, type 2 responses are regulated by a signaling circuit that involves tuft cells and group 2 innate lymphoid cells (ILC2s). Here, we identified the microbial metabolite succinate as an activating ligand for small intestinal (SI) tuft cells. Sequencing analyses of tuft cells isolated from the small intestine, gall bladder, colon, thymus, and trachea revealed that expression of tuft cell chemosensory receptors is tissue specific. SI tuft cells expressed the succinate receptor (SUCNR1), and providing succinate in drinking water was sufficient to induce a multifaceted type 2 immune response via the tuft-ILC2 circuit. The helminth Nippostrongylus brasiliensis and a tritrichomonad protist both secreted succinate as a metabolite. In vivo sensing of the tritrichomonad required SUCNR1, whereas N. brasiliensis was SUCNR1 independent. These findings define a paradigm wherein tuft cells monitor microbial metabolites to initiate type 2 immunity and suggest the existence of other sensing pathways triggering the response to helminths.
Subject(s)
Immunity, Mucosal/drug effects , Intestinal Mucosa/cytology , Intestinal Mucosa/immunology , Receptors, G-Protein-Coupled/metabolism , Signal Transduction/drug effects , Succinic Acid/pharmacology , Animals , Cell Line , Female , Intestinal Mucosa/metabolism , Intestine, Small/drug effects , Intestine, Small/immunology , Male , Mice, Inbred C57BL , Mice, Knockout , Nippostrongylus/drug effects , Nippostrongylus/immunology , Nippostrongylus/metabolism , Organ Specificity , Protozoan Infections/immunology , Receptors, G-Protein-Coupled/immunology , Signal Transduction/immunology , Species Specificity , Strongylida Infections/immunology , TRPM Cation Channels/metabolism , Th2 Cells/immunology , Tritrichomonas/drug effects , Tritrichomonas/immunology , Tritrichomonas/metabolismABSTRACT
Spinal cord injury (SCI) induces haemodynamic instability that threatens survival1-3, impairs neurological recovery4,5, increases the risk of cardiovascular disease6,7, and reduces quality of life8,9. Haemodynamic instability in this context is due to the interruption of supraspinal efferent commands to sympathetic circuits located in the spinal cord10, which prevents the natural baroreflex from controlling these circuits to adjust peripheral vascular resistance. Epidural electrical stimulation (EES) of the spinal cord has been shown to compensate for interrupted supraspinal commands to motor circuits below the injury11, and restored walking after paralysis12. Here, we leveraged these concepts to develop EES protocols that restored haemodynamic stability after SCI. We established a preclinical model that enabled us to dissect the topology and dynamics of the sympathetic circuits, and to understand how EES can engage these circuits. We incorporated these spatial and temporal features into stimulation protocols to conceive a clinical-grade biomimetic haemodynamic regulator that operates in a closed loop. This 'neuroprosthetic baroreflex' controlled haemodynamics for extended periods of time in rodents, non-human primates and humans, after both acute and chronic SCI. We will now conduct clinical trials to turn the neuroprosthetic baroreflex into a commonly available therapy for people with SCI.
Subject(s)
Baroreflex , Biomimetics , Hemodynamics , Prostheses and Implants , Spinal Cord Injuries/physiopathology , Spinal Cord Injuries/therapy , Animals , Disease Models, Animal , Female , Humans , Male , Neural Pathways , Primates , Rats , Rats, Inbred Lew , Sympathetic Nervous System/cytology , Sympathetic Nervous System/physiologyABSTRACT
Roughly one-half of mice with partial defects in two immune tolerance pathways (AireGW/+Lyn-/- mice) spontaneously develop severe damage to their retinas due to T cell reactivity to Aire-regulated interphotoreceptor retinoid-binding protein (IRBP). Single-cell T cell receptor (TCR) sequencing of CD4+ T cells specific for a predominate epitope of IRBP showed a remarkable diversity of autoantigen-specific TCRs with greater clonal expansions in mice with disease. TCR transgenic mice made with an expanded IRBP-specific TCR (P2.U2) of intermediate affinity exhibited strong but incomplete negative selection of thymocytes. This negative selection was absent in IRBP-/- mice and greatly defective in AireGW/+ mice. Most P2.U2+/- mice and all P2.U.2+/-AireGW/+ mice rapidly developed inflammation of the retina and adjacent uvea (uveitis). Aire-dependent IRBP expression in the thymus also promoted Treg differentiation, but the niche for this fate determination was small, suggesting differences in antigen presentation leading to negative selection vs. thymic Treg differentiation and a stronger role for negative selection in preventing autoimmune disease in the retina.
Subject(s)
Antigen Presentation , Receptors, Antigen, T-Cell , Animals , Mice , Autoantigens , Disease Models, Animal , Mice, Inbred Strains , Mice, TransgenicABSTRACT
Insulin is a central autoantigen in the pathogenesis of T1D, and thymic epithelial cell expression of insulin under the control of the Autoimmune Regulator (Aire) is thought to be a key component of maintaining tolerance to insulin. In spite of this general working model, direct detection of this thymic selection on insulin-specific T cells has been somewhat elusive. Here, we used a combination of highly sensitive T cell receptor transgenic models for detecting thymic selection and sorting and sequencing of Insulin-specific CD4+ T cells from Aire-deficient mice as a strategy to further define their selection. This analysis revealed a number of unique t cell receptor (TCR) clones in Aire-deficient hosts with high affinity for insulin/major histocompatibility complex (MHC) ligands. We then modeled the thymic selection of one of these clones in Aire-deficient versus wild-type hosts and found that this model clone could escape thymic negative selection in the absence of thymic Aire. Together, these results suggest that thymic expression of insulin plays a key role in trimming and removing high-affinity insulin-specific T cells from the repertoire to help promote tolerance.
Subject(s)
AIRE Protein , Insulin , Receptors, Antigen, T-Cell , Thymus Gland , Animals , Mice , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , Clone Cells , Immune Tolerance , Insulin/metabolism , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Receptors, Antigen, T-Cell/metabolism , Receptors, Antigen, T-Cell/immunology , Thymus Gland/immunology , Thymus Gland/metabolism , Thymus Gland/cytology , Transcription Factors/metabolism , Transcription Factors/geneticsABSTRACT
CaMKII (the multifunctional Ca2+ and calmodulin-dependent protein kinase II) is a highly validated signal for promoting a variety of common diseases, particularly in the cardiovascular system. Despite substantial amounts of convincing preclinical data, CaMKII inhibitors have yet to emerge in clinical practice. Therapeutic inhibition is challenged by the diversity of CaMKII isoforms and splice variants and by physiological CaMKII activity that contributes to learning and memory. Thus, uncoupling the harmful and beneficial aspects of CaMKII will be paramount to developing effective therapies. In the last decade, several targeting strategies have emerged, including small molecules, peptides, and nucleotides, which hold promise in discriminating pathological from physiological CaMKII activity. Here we review the cellular and molecular biology of CaMKII, discuss its role in physiological and pathological signaling, and consider new findings and approaches for developing CaMKII therapeutics.
Subject(s)
Cardiovascular Diseases , Cardiovascular System , Humans , Cardiovascular Diseases/drug therapy , Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Arrhythmias, Cardiac , Cardiovascular System/metabolism , Signal Transduction/physiologyABSTRACT
There is a critical gap in knowledge about how Gram-negative bacterial pathogens, using survival strategies developed for other niches, cause lethal bacteremia. Facultative anaerobic species of the Enterobacterales order are the most common cause of Gram-negative bacteremia, including Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, and Enterobacter hormaechei. Bacteremia often leads to sepsis, a life-threatening organ dysfunction resulting from unregulated immune responses to infection. Despite a lack of specialization for this host environment, Gram-negative pathogens cause nearly half of bacteremia cases annually. Based on our existing Tn-Seq fitness factor data from a murine model of bacteremia combined with comparative genomics of the five Enterobacterales species above, we prioritized 18 conserved fitness genes or operons for further characterization. Mutants were constructed for all genes in all five species. Each mutant was used to cochallenge C57BL/6 mice via tail vein injection along with each respective wild-type strain to determine competitive indices for each fitness gene. Five fitness factor genes, when mutated, attenuated mutants in four or five species in the spleen and liver (tatC, ruvA, gmhB, wzxE, arcA). Five additional fitness factor genes or operons were validated as outcompeted by wild-type in three, four, or five bacterial species in the spleen (xerC, prc, apaGH, atpG, aroC). Overall, 17 of 18 fitness factor mutants were attenuated in at least one species in the spleen or liver. Together, these findings allow for the development of a model of bacteremia pathogenesis that may include future targets of therapy against bloodstream infections.