Biology subjects

Smith, N. P.

Publications and source records attributed to Smith, N. P..

9 recordsLinked to original sources

bioRxiv2026

Type 2 conventional dendritic cells and regulatory T cells form a barrier tissue circuit to control allergic inflammation

Chronic allergic diseases are driven by T helper type 2 (Th2) cells in barrier tissues. Despite their profound effects on tissue physiology, Th2 cells represent a rare cell population within tissues, suggesting mechanisms restraining Th2 cell expansion at barrier sites that remain ill defined. Using a murine model of allergic asthma, we demonstrate that effector Th2 cells promote cDC2 activation within the lungs, including expression of the CCR4 ligands that attract Foxp3+ regulatory T cells (Tregs). Selective deletion of Ccr4 in Tregs during the effector Th2 cell response led to increased lung Th2 cells, activated cDC2s, and allergic inflammation. Mechanistically, CCR4 promoted Treg trafficking efficiency and was required to specifically control tissue cDC2 co-stimulatory molecule expression. Lastly, in the airways of humans with allergy, the expression of the CCR4 ligands in activated cDCs correlated with Treg enrichment. In sum, we define a cDC2-Treg feedback circuit within a barrier tissue that restrains effector Th2 cell expansion, revealing a novel role for tissue cDC2s in controlling Th2 cell biology.

immunology↗

bioRxiv2025

Sensory neuronal mTORC1 signaling establishes neuroimmune memory that initiates allergic immunity

Environmental allergens are enriched in protease activity, a feature that directly activates cutaneous sensory neurons, triggering itch and Substance P release, which promotes Th2-skewing CD301b+ dendritic cell migration and initiates allergic immunity. However, allergens are typically encountered as repeated, subthreshold exposures, and how these cumulatively induce sensitization is unknown. We identify a sensory neuron-intrinsic mechanism of neuroimmune memory that enables this process. Initial activation by protease allergens induces sustained mTORC1 signaling and PGC-1-associated mitochondrial remodeling, establishing a metabolically primed state that amplifies neuroimmune responses upon allergen re-exposure. This heightened state, independent of adaptive immunity, drives enhanced itch, increased CD301b+ dendritic cell migration, and augmented Th2 differentiation. Disrupting neuronal mTORC1 signaling or mitochondrial stability abrogates this amplification while leaving primary responses intact. Importantly, this mechanism generalizes across distinct protease allergens, revealing mTORC1-driven metabolic reprogramming in sensory neurons as a form of innate neuroimmune memory underlying allergen cross-sensitization and polysensitization.

immunology↗

bioRxiv2025

Diverse modes of T cell receptor sequence convergence define unique functional and cellular phenotypes

Single-cell techniques allow concurrent study of gene activity and T cell receptor (TCR) sequences, identifying connections between TCR structure and cell traits. Expanding on our CoNGA software, we present a "metaCoNGA" analysis of 6 million T cells from 91 diverse studies, mapping TCR sequence similarity across tissues and diseases. This approach exposes shared TCR features within specific T cell subsets, including those associated with infection, cancer, and autoimmunity. We introduce a method to identify T cell groups with similar gene expression and biased TCR amino acid composition, providing a systematic framework for classifying diverse unconventional T cells, including KIR+ CD8+ T cells, CD4+ regulatory T cells, and subsets of NKT and MAIT cells. A new TCR clustering approach identifies thousands of convergent TCR sequence clusters hypothesized to target shared antigens. These clusters show coherent gene expression, highlighting the role of antigen exposure in shaping T cell behavior. Finally, we provide a tool for users to merge new data with this resource and rapidly identify T cell features in their data sets. This resource empowers investigations into the complex relationship between TCR sequence and T cell function in human health.

immunology↗

bioRxiv2025

Distinct phenotypes and repertoires of bronchoalveolar and airway mucosal T cells in health and allergic asthma

BackgroundT cells play a central role in host protection against respiratory pathogens, but a maladaptive T cell response can lead to pulmonary diseases. Defining the biology of protective versus pathogenic T cell responses in the lungs of humans will be critical to nominate novel approaches to improve respiratory health. Previous studies have examined T cells from the lungs captured via bronchoalveolar lavage (BAL), endobronchial brushings, or biopsies. However, whether these different approaches are capturing distinct T cell phenotypes and/or clonotypes remains unclear. ObjectiveTo evaluate and compare the transcriptional signatures of T cells isolated via BAL versus endobronchial brushings in healthy controls (HCs) and allergic asthmatics (AAs). MethodsFlexible bronchoscopy was performed to obtain BAL and endobronchial brushings from 3 HC and 3 AA subjects. CD3+ T cells were sorted and single cell RNA- and T cell receptor (TCR)-sequencing was performed using the 10X Chromium platform. Unbiased clustering, differential gene expression analysis and TCR repertoire analysis was performed. ResultsUnbiased clustering analysis allowed us to define 7 CD8 and 6 CD4 T cell subsets. The most significant difference in T cell subsets abundance between AAs and HCs was the enrichment of CD4 T helper type 2 (Th2) cells when comparing endobronchial brush samples (OR=26.2, P=0.002), but not when examining BAL (OR=1.7, P=0.46), indicating differences in the T cell subsets captured from the BAL versus airway mucosa specimen processing. In further support of this observation, comparing the BAL and brush T cells across all subjects revealed an up-regulation of resident-memory T cell markers (i.e. ITGAE, CD69) in brush T cells versus BAL T cells in both CD4 and CD8 lineages. In contrast, BAL CD8 and CD4 T cells exhibited an enriched type I and II interferon signatures compared to brush T cells. Lastly, TCR repertoire analysis revealed that brush T cells contained dramatically expanded TCR clones. Expanded T cell clones from the brush expressed high levels of resident-memory markers, suggesting the airway mucosa is enriched for TRM cells with unique TCR specificity. ConclusionsSampling T cells via BAL versus airway brushings yielded distinct T cell phenotypes and clonotypes with important implications for future research in lung immunology.

immunology↗

bioRxiv2024

Airway basal stem cells are necessary for the maintenance of functional intraepithelial airway macrophages.

Adult stem cells play a crucial role in tissue homeostasis and repair through multiple mechanisms. In addition to being able to replace aged or damaged cells, stem cells provide signals that contribute to the maintenance and function of neighboring cells. In the lung, airway basal stem cells also produce cytokines and chemokines in response to inhaled irritants, allergens, and pathogens, which affect specific immune cell populations and shape the nature of the immune response. However, direct cell-to-cell signaling through contact between airway basal stem cells and immune cells has not been demonstrated. Recently, a unique population of intraepithelial airway macrophages (IAMs) has been identified in the murine trachea. Here, we demonstrate that IAMs require Notch signaling from airway basal stem cells for maintenance of their differentiated state and function. Furthermore, we demonstrate that Notch signaling between airway basal stem cells and IAMs is required for antigen-induced allergic inflammation only in the trachea where the basal stem cells are located whereas allergic responses in distal lung tissues are preserved consistent with a local circuit linking stem cells to proximate immune cells. Finally, we demonstrate that IAM-like cells are present in human conducting airways and that these cells display Notch activation, mirroring their murine counterparts. Since diverse lung stem cells have recently been identified and localized to specific anatomic niches along the proximodistal axis of the respiratory tree, we hypothesize that the direct functional coupling of local stem cell-mediated regeneration and immune responses permits a compartmentalized inflammatory response.

cell biology↗

bioRxiv2024

Human research islet cell culture outcomes at the Alberta Diabetes Institute IsletCore

Human islets from deceased organ donors have made important contributions to our understanding of pancreatic endocrine function and continue to be an important resource for research studies aimed at understanding, treating, and preventing diabetes. Understanding the impacts of isolation and culture upon the yield of human islets for research is important for planning research studies and islet distribution to distant laboratories. Here we examine islet isolation and cell culture outcomes at the Alberta Diabetes Institute (ADI) IsletCore (n=197). Research-focused isolations typically have a lower yield of islet equivalents (IEQ), with a median of 252,876 IEQ, but a higher purity (median 85%) than clinically-focused isolations before culture. The median recovery of IEQs after culture was 75%, suggesting some loss. This was associated with a shift towards smaller islet particles, indicating possible islet fragmentation, and occurred within 24 hours with no further loss after longer periods of culture (up to 136 hours). No overall change in stimulation index as a measure of islet function was seen with culture time. These findings were replicated in a representative cohort of clinical islet preparations from the Clinical Islet Transplant Program at the University of Alberta. Thus, loss of islets occurs within 24 hours of isolation and there is no further impact of extended culture prior to islet distribution for research.

cell biology↗

bioRxiv2023

Resident memory T cell development is associated with AP-1 transcription factor upregulation across anatomical niches.

Tissue-resident memory T (TRM) cells play a central role in immune responses to pathogens across all barrier tissues after infection. However, the underlying mechanisms that drive TRM differentiation and priming for their recall effector function remains unclear. In this study, we leveraged both newly generated and publicly available single-cell RNA-sequencing (scRNAseq) data generated across 10 developmental time points to define features of CD8 TRM across both skin and small-intestine intraepithelial lymphocytes (siIEL). We employed linear modeling to capture temporally-associated gene programs that increase their expression levels in T cell subsets transitioning from an effector to a memory T cell state. In addition to capturing tissue-specific gene programs, we defined a consensus TRM signature of 60 genes across skin and siIEL that can effectively distinguish TRM from circulating T cell populations, providing a more specific TRM signature than what was previously generated by comparing bulk TRM to naive or non-tissue resident memory populations. This updated TRM signature included the AP-1 transcription factor family members Fos, Fosb and Fosl2. Moreover, ATACseq analysis detected an enrichment of AP-1-specific motifs at open chromatin sites in mature TRM. CyCIF tissue imaging detected nuclear co-localization of AP-1 members Fosb and Junb in resting CD8 TRM >100 days post-infection. Taken together, these results reveal a critical role of AP-1 transcription factor members in TRM biology and suggests a novel mechanism for rapid reactivation of resting TRM in tissue upon antigen encounter.

immunology↗

bioRxiv2023

Immune Responses in Checkpoint Myocarditis Across Heart, Blood, and Tumor

Immune checkpoint inhibitors (ICIs) are widely used anti-cancer therapies that can cause morbid and potentially fatal immune-related adverse events (irAEs). ICI-related myocarditis (irMyocarditis) is uncommon but has the highest mortality of any irAE. The pathogenesis of irMyocarditis and its relationship to anti-tumor immunity remain poorly understood. We sought to define immune responses in heart, tumor, and blood during irMyocarditis and identify biomarkers of clinical severity by leveraging single-cell (sc)RNA-seq coupled with T cell receptor (TCR) sequencing, microscopy, and proteomics analysis of 28 irMyocarditis patients and 23 controls. Our analysis of 284,360 cells from heart and blood specimens identified cytotoxic T cells, inflammatory macrophages, conventional dendritic cells (cDCs), and fibroblasts enriched in irMyocarditis heart tissue. Additionally, potentially targetable, pro-inflammatory transcriptional programs were upregulated across multiple cell types. TCR clones enriched in heart and paired tumor tissue were largely non-overlapping, suggesting distinct T cell responses within these tissues. We also identify the presence of cardiac-expanded TCRs in a circulating, cycling CD8 T cell population as a novel peripheral biomarker of fatality. Collectively, these findings highlight critical biology driving irMyocarditis and putative biomarkers for therapeutic intervention.

immunology↗

bioRxiv2020

Identification of antigen-specific TCR sequences using a strategy based on biological and statistical enrichment in unselected subjects

Recent advances in high-throughput T cell receptor (TCR) sequencing have allowed for new insights into the TCR repertoire. However, methods for capturing antigen-specific repertoires remain an area of development. Here, we describe a novel approach that utilizes both a biological and statistical enrichment to define putatively antigen-specific complementarity-determining region 3 (CDR3) repertoires in unrelated individuals. The biological enrichment entails fluorescence-activated cell sorting of in vitro antigen-activated memory CD4+ T cells followed by TCR{beta} sequencing. The resulting TCR{beta} sequences are then filtered by selecting those that are statistically enriched when compared to their frequency in the autologous resting T cell compartment. Applying this method to define putatively peanut protein-specific repertoires in 27 peanut-allergic individuals resulted in a library of 7345 unique CDR3 amino acid sequences that had similar characteristics to validated antigen-specific repertoires in terms of homology and diversity. In-depth analysis of these CDR3s revealed 36 public sequences that demonstrated high levels of convergent recombination. In a network analysis, the public CDR3s unveiled themselves as core sequences with more edges than their private counterparts. This method has the potential to be applied to a wide range of T cell mediated disorders, and to yield new biomarkers and biological insights.

immunology↗