Single-cell RNA-seq of the human tonsil and blood lymphocytes
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ABSTRACT: Tissue-selective chemotactic mechanisms direct lymphocytes to epithelial surfaces of the body to establish local immune environments, to regulate immune responses to food antigens and commensal organisms, and to protect the body from pathogens. Chemoattractants for small intestines, colon, and skin are known, but chemotropic mechanisms selective for respiratory tract and other non-intestinal mucosal tissues (NIMT) remain poorly understood. Here we leveraged diverse omics datasets to identify GPR25 as a lymphocyte receptor for CXCL17, a chemoattractant cytokine whose expression by epithelial cells of airways, upper gastrointestinal and squamous mucosae unifies the NIMT and distinguishes them from intestinal mucosae. Analyses of single cell transcriptomic data shows that GPR25 is induced on innate lymphocytes prior to emigration to the periphery, and is imprinted in secondary lymphoid tissues on activated B and T cells responding to immune challenge. GPR25 characterizes B and T tissue resident memory and regulatory T lymphocytes in NIMT and lungs in human and we show that it mediates lymphocyte homing to barrier epithelia of the the respiratory tract, stomach and biliary and genitourinary tracts in mouse models. GPR25 is also expressed by T cells in cerebrospinal fluid and CXCL17 by neurons, suggesting a link to CNS immune regulation. We reveal widespread imprinting and expression of GPR25 on regulatory T cells, suggesting a mechanistic link to population genetic evidence that GPR25 is protective in autoimmunity. Our results define a GPR25-CXCL17 chemoaffinity axis with the potential to integrate immunity and tolerance at non-intestinal mucosae and the CNS.
Project description:<p>Approximately 550,000 babies born prematurely each year in the United States suffer from birth at a time in development when the respiratory tract and immune system would normally be protected and maintained in a naïve state. This project is a component of the NIH Prematurity and Respiratory Outcomes Program (PROP) whose goals are the identification of disease mechanisms and biomarkers to stratify premature infants, at the time of discharge, for their risk of subsequent pulmonary morbidity. This Clinical Research Center (CRC) project will investigate prematurity-dependent alterations in cellular innate and adaptive immune systems resulting in increased susceptibility to respiratory infections and environmental irritants, and leading to respiratory morbidity in the first year of life. Prior studies have established developmental (maturity) and disease-related changes in circulating and pulmonary lymphocyte populations, but a comprehensive assessment of their relationship to disease risk/outcome has not been undertaken. We hypothesize that cellular and molecular immuno-maturity is altered due to intrinsic and extrinsic factors presented by premature birth in such a way as to reduce resistance to viral infections and to promote cytotoxic damage to the lung. We will evaluate immunologic maturity by comprehensively phenotyping lymphocyte populations in peripheral blood sampled at premature delivery, at the time of discharge from the hospital and at twelve months corrected age. The lymphocytic phenotype will be analyzed particularly in the context of gestational age and maternal-fetal stressors capable of modulating oxidative stress (oxygen exposure, infection and environmental tobacco smoke exposure). Additionally, we will assess changes in the molecular phenotype of isolated CD8 lymphocytes, a cell type preferentially recruited to the lungs of premature infants and capable of contributing to disease pathogenesis, by genome-wide expression profiling, in order to uncover novel disease pathways and define a gene expression signature associated with disease risk. We propose to build a statistical model, using cellular and molecular phenotypes and additional clinical variables, for stratifying risk of lung morbidity within the first year of life. Finally, we will assess the development of the gut microbiome in the preterm subjects to correlate with the observation of development of the adaptive immune system.</p>
Project description:Intravaginal infection of C57BL/6 mice with Chlamydia muridarum promotes activation and migration of effector lymphocytes to the genital tract mucosa. Among up regulated genes related to the specific immune response 7 days after infection we aimed to detect adhesion molecules associated with migration to this mucosa. We used microarrays to determine the global gene expression changes underlying homing to genital tract mucosa and identified distinct classes of up-regulated genes during effector T lymphocyte migration to this tissue.
Project description:Intestinal lymphocytes are crucial members of the mucosal immune system with impact over outcomes of intestinal health versus dysbiosis. Resolving intestinal lymphocyte complexity and function is a challenge, as the intestine provides cellular snapshots of a diverse spectrum of immune states. In pigs, intestinal lymphocytes are poorly described relative to humans or traditional model species. Enhanced understanding of porcine intestinal lymphocytes will promote food security and improve utility of pigs as a biomedical model for intestinal research. Single-cell RNA sequencing (scRNA-seq) was performed to provide transcriptomic profiles of lymphocytes in porcine ileum, with 31,983 cells annotated into 26 cell types. Deeper interrogation revealed previously undescribed cells in porcine intestine, including SELLhi gd T cells, group 1 and group 3 innate lymphoid cells (ILCs), and four subsets of B cells. Single-cell transcriptomes in ileum were compared to those in porcine blood, and subsets of activated lymphocytes were detected in ileum but not periphery. Comparison to scRNA-seq human and murine ileum data revealed a general consensus of ileal lymphocytes across species. Lymphocyte spatial context in porcine ileum was conferred through differential tissue dissection prior to scRNA-seq. Antibody-secreting cells, B cells, follicular CD4 ab T cells, and cycling T/ILCs were enriched in ileum with Peyer’s patches, while non-cycling gd T, CD8 ab T, and group 1 ILCs were enriched in ileum without Peyer’s patches. scRNA-seq findings were leveraged to develop advanced toolsets for further identification of ILCs in porcine ileum via flow cytometry and in situ staining. Porcine ileal ILCs identified via scRNA-seq did not transcriptionally mirror peripheral porcine ILCs (corresponding to natural killer cells) but instead had gene signatures indicative of tissue- and activation-specific functions, indicating potentially similar roles to intestinal ILCs identified in humans. Overall, the data serve as a highly-resolved transcriptomic atlas of the porcine intestinal immune landscape and will be useful in further understanding intestinal immune cell function.
Project description:The respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with Bordetella bronchiseptica (Bb) as the underlying model to comprehensively address effects on subsequent immune responses. Persistent carriage was associated with the stimulation of Bordetella-specific CD4+, CD8+ and CD4+CD25+Foxp3+ T cell responses and broad transcriptional activation was observed in CD4+CD25+ T cells. Importantly, transfer of lymphocytes from persistent carriers to acutely B. bronchiseptica infected mice resulted in a significantly increased bacterial burden in the recipient’s upper respiratory tract. In contrast, we found that B. bronchiseptica carriage resulted in a significant benefit for the host in systemic infection with Listeria monocytogenes. At the same time, vaccination and influenza A virus infection were unaffected. These data demonstrate that there are significant immune modulatory processes triggered by persistent B. bronchiseptica carriage that differentially affect subsequent immune responses. Thereby our results demonstrate the complexity of immune regulation induced by persistent bacterial carriage in the respiratory tract that can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.
Project description:M cells are special cells in the epithelium of the small intestinal bowel and play an important role during the initiation of a primary, fast immune response. On a Costar-Transwell filter cells of a colon adeno carcinoma cell line (Caco-2) are growing until differentiation. Then on the other side of the Caco cell layer lymphocytes from human venous blood are added. Pores in the filter membrane allow contact between lymphocytes and Caco cells. Therefore some cells of the Caco cell layer are differentiating to "M cell like" cells, showing the morpholgy and function of natural M cells. Experiment Overall Design: Two replicates of non-induced filter-grown Caco cells and three replicates of lymphocyte-induced filter-grown Caco cells (including lymphocyte expression) for the identification of regulated genes; one experiment of bottle-grown Caco cells and one experiment of bottle-grown lymphocytes for baseline expression profiling and control reasons.
Project description:The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. In this study, we used microarrays to uncover the transcriptional responses that occur in small intestinal γδ intraepithelial lymphocytes following bacterial challenge.
Project description:Immune checkpoint inhibitors (CPIs) have revolutionised cancer treatment, with previously untreatable disease now amenable to potential cure. Combination regimens of anti-CTLA-4 and anti-PD-1 show enhanced efficacy but are prone to off-target immune-mediated tissue injury, particularly at the barrier surfaces. To probe the impact of immune checkpoints on intestinal homeostasis, mice were challenged with anti-CTLA-4 and anti-PD-1 immunotherapy and manipulation of the intestinal microbiota. Single-cell RNA-sequencing revealed remodelling of mucosal lymphocytes with induction of polyfunctional lymphocyte responses characterized by increased expression of Ifng, other pro-inflammatory cytokines/chemokines (Il22, Il17a Ccl3, Ccl4 and Ccl9), cytotoxicity molecules (Gzmb, Gzma, Prf1, Nkg7) and the chemokine receptor Cxcr6. In comparison with mucosal lymphocytes in the steady state, polyfunctional lymphocytes from both CD4+ and CD8+ lineages upregulated costimulatory molecules and checkpoint molecules in CPI-colitis, indicating that these cells are tightly regulated.
Project description:The lung is constantly exposed to potentially pathogenic particles and microorganisms. It has recently become evident that not only innate, but also adaptive immune responses to particulates such as crystalline silica (SiO2) entering the respiratory tract are complex and dynamic events. Although the cellular mechanisms and anatomical consequences involved in the development of silicosis have been extensively studied, they still remain poorly understood. Based on their capacity for immune regulation, lymphocytes may play a role in determining the respiratory response to environmental challenge by SiO2. The objective of this study was to characterize the impact of SiO2 exposure on respiratory immune processes, with particular emphasis on evaluating the importance of lymphocytes in the murine silicosis model. Therefore, we utilized lymphopenic mice including NK deficient, Rag1-/- or a combination (Rag1-/- NK depleted) and demonstrated that SiO2-induced fibrosis and inflammation occur independently of T, B, NK T, and NK cells. Studies in Rag1-/- mice further suggest that lymphocytes may participate in controlling SiO2-induced inflammation through modulation of the Nalp3 inflammasome. This observation may have clinical relevance in the treatment of inflammatory and fibrotic lung diseases that are either refractory or respond sub-optimally to current therapeutics.
Project description:The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. In this study, we used microarrays to uncover the transcriptional responses that occur in small intestinal γδ intraepithelial lymphocytes following bacterial challenge. γδ intraepithelial lymphocytes (γδ IEL) were isolated by flow cytometry from the small intestines of germ-free mice, or from age- and sex-matched conventionally-raised counterparts. We extracted RNAs from these purified γδ IEL for analysis on Affymetrix DNA microarrays. The mice were all >8 weeks in age, and each sample represents a pool of RNAs from 5-8 mice.
Project description:IL-15 has critical impact on the homeostasis and activation of NK, NKT, gdT and CD8+T cells, and contributes to antimicrobial defenses particularly at mucosal sites. The respiratory tract also comprises a large mucosal surface and harbors significant amounts of lymphocytes, but the expression pattern of IL-15 in the lung and its role in local immune responses are largely unknown. We therefore analyzed the differential expression of IL-15 and the IL-15 receptor (IL-15R) complex in the lungs of mice, and demonstrated substantial constitutive expression in bronchial and alveolar epithelial cells, alveolar macrophages, and vascular smooth muscle cells, implicating contribution to pulmonary immune cell homeostasis already under normal conditions. The induction of pneumococcal pneumonia but not the infection with Chlamydophila pneumoniae evoked a significant up-regulation of IL-15 on alveolar macrophages and bronchial epithelial cells, with the latter presenting de-novo expression of IL-15 on their basolateral surface and additional up-regulation of IL-15Ra . Transcriptome analysis and semiquantitative PCR indicated at least partial transcriptional regulation. Finally, the increase of IL-15 was accompanied by enhanced expression of CD69, TNFa, IFNg and Bcl-2 by IL-15-dependent lymphocyte populations suggesting functional impact of IL-15 on the pulmonary immune response in pneumococcal pneumonia. Microarray experiments were done as two-color hybridizations. RNA labeling was performed with a Fluorescent Linear Amplification Kit (Agilent Technologies). In order to compensate dye specific effects, and to ensure statistically relevant data, a color swap was performed.