Biology subjects

Thomas, S. N.

Publications and source records attributed to Thomas, S. N..

6 recordsLinked to original sources

bioRxiv2026

Confined T cell migration controls programmed cell death 1 expression

T cell immune checkpoint expression and dysfunction are attributed solely to molecular cues. We discover using microphysiological systems and in vivo models that transmigration through confined pores induces acute loss of programmed cell death 1 within minutes of surface immune checkpoint markers on CD8+ T cells through ubiquitin-mediated proteasomal degradation, corresponding with enhanced fitness and function. Such imprints and its underlying mechanism of programmed cell death 1 loss are conserved across species and applicable to human TIL and CAR T cells, and are correlative with disease outcomes in human melanoma. Our findings establish the diverse tissues landscapes that T cells traverse during immunosurveillance, and specifically transmigration, as a form of mechanical immune regulation, and reveal a mechano-modulatory strategy to improve the quality and persistence of engineered or patient-derived T cells for adoptive immunotherapy.

immunology↗

bioRxiv2025

Global proteomic analysis of Cryptococcus neoformans clinical strains reveals significant differences between latent and lethal infection

To predict the outcomes of disseminated fungal disease, a deeper understanding of host-pathogen interactions at the site of infection is needed to identify targets for clinical intervention and diagnostic development. Cryptococcus neoformans is the causative agent of cryptococcosis, the largest infectious killer of individuals living with HIV. Cryptococcal infection begins in the lungs, with loss of immunological control leading to disseminated central nervous system disease and death. Using advanced mass spectrometry-based proteomic techniques, in vivo infection models, and patient-derived clinical strains, we explored the proteomic profiles of C. neoformans infections related to differences in strain virulence. Our findings reveal that non-lethal latent infection produces a proteomic response that differs significantly from the response caused by lethal infections, and that the proteomic profiles of typical and hypervirulent infections are markedly similar despite differences in time-to-death. Overall, the mouse pulmonary proteomic response in latent infection is defined by enrichment of proteins and pathways involved in extracellular matrix organization, cell adhesion, and structural changes, while the lethal infection is dominated by host-defense, translation, and metabolic processes. These results provide clinically relevant information on how infections caused by different Cryptococcus strains may produce significantly different outcomes. We also identified abundant fungal proteins that could be future drug targets in latent and lethal cryptococcal infection. IMPORTANCECryptococcus neoformans is a fungal pathogen that causes substantial morbidity and mortality in immunocompromised individuals. The initial infection begins in the lungs after exposure to inhaled spores after which local immune cells respond by either killing or containing the fungal cells. Immunosuppression weakens the immune system and allows fungal cells in the lungs to escape through the circulatory system and invade the central nervous system and cause fatal disease. However, differences between fungal strains influence the severity of disease manifestation. Our group has previously described genetic differences that contribute to strain-specific disease manifestations. In this study, we expanded our analysis to investigate the proteomic differences between strains of C. neoformans to identify candidate proteins and pathways that contribute to disease manifestation. We found that latent infection differs significantly from lethal disease from both the host and pathogen proteomic perspectives and have identified several fungal protein targets for future study.

microbiology↗

bioRxiv2023

The retinal RNA editome is concentrated in photoreceptor-specific genes and genetically linked to vision loss

BACKGROUNDConversion of adenosine in RNA to inosine by ADAR enzymes, termed RNA editing, occurs at thousands of sites across the transcriptome, and is required for healthy development of the central nervous system. RNA editing can modify protein sequences, and dampen the innate immune response. RNA editing is tissue-specific and partly genetically determined. Modifications of RNA editing sites contribute to multiple diseases, particularly neurodevelopmental and neuropsychiatric diseases. Despite the importance of RNA editing in the brain, nothing is known about this process in the human retina. We describe the landscape of retinal editing revealing its importance in key biological processes that underpin vision. METHODS & RESULTSWe analysed the transcriptomes of >500 donor retinae and identified [~]153,000 high-confidence RNA editing sites. Some 80% of editing sites occurred within protein-coding RNA, with the majority in intronic Alu repeats, and 3 UTR sequence. Novel retina-specific sites were concentrated in genes related to photoreceptor function and which cause retinitis pigmentosa, most notably in PDE6A. Exonic, protein recoding sites were enriched in zinc-finger domains. AMD subjects exhibit relatively few differences in RNA editing compared to controls, consistent with limited gene expression differences. We identified [~]10,000 editing QTLs. The genetic architecture of editing in the retina resembles the brain, whereas editing and expression QTLs in the retina show modest genetic overlap. We report colocalization between edQTLs and retinal disease GWAS peaks for age-related macular degeneration, glaucoma and macular telangiectasia. These findings provide new insights into epi-transcriptomic regulation of genes critical for vision, and elaborate putative genetic disease driver mechanisms that appear to be independent of changes in gene expression.

genomics↗

bioRxiv2022

Tumor microenvironments impair T cell receptor affinity and function

CD8+ T cells underpin effective anti-tumor immune responses in melanoma; however, their functions are attenuated due to various immunosuppressive factors in the tumor microenvironment (TME), resulting in disease progression. T cell function is elicited by the T cell receptor (TCR), which recognizes antigen peptide-major histocompatibility complex (pMHC) expressed on tumor cells via direct physical contact, i.e., two-dimensional (2D) interaction. TCR-pMHC 2D affinity plays a central role in antigen recognition and discrimination, and is sensitive to both the conditions of the T cell and the microenvironment in which it resides. Herein, we demonstrate that CD8+ T cells residing in TME have lower 2D TCR-pMHC bimolecular affinity and TCR-pMHC-CD8 trimolecular avidity, pull fewer TCR-pMHC bonds by endogenous forces, flux lower level of intracellular calcium in response to antigen stimulation, exhibit impaired in vivo activation, and show diminished anti-tumor effector function. These detrimental effects are localized in the tumor and tumor draining lymph node (TdLN), and affect both antigen-inexperienced and antigen-experienced CD8+ T cells irrespective of their TCR specificities. These findings implicate impaired antigen recognition as a mechanism of T cell dysfunction in the TME.

immunology↗

bioRxiv2019

Cell type and cortex-specific RNA editing in single human neurons informs neuropsychiatric disorders

BACKGROUNDConversion of adenosine to inosine in RNA by ADAR enzymes occurs at thousands of sites in the human transcriptome, and is essential for healthy brain development. This RNA editing process is dysregulated in many neuropsychiatric diseases, but is little understood at the level of individual neurons. METHODSWe quantified RNA editing sites in full-length capture nuclear transcriptomes of 3055 neurons from six cortical regions of a neurotypical post-mortem female donor. Putative editing sites were intersected with sites in bulk human tissue transcriptomes including healthy and neuropsychiatric brain tissue, and sites identified in single nuclei from unrelated brain donors. Differential editing between cell types and cortical regions, and individual sites and genes therein, was quantified using linear models. Associations between gene expression and editing were also tested. RESULTSWe identified 41,930 RNA editing sites with robust read coverage in at least ten neuronal nuclei. Most sites were located within Alu repeats in introns or 3 UTRs, and approximately 80% were catalogued in published RNA editing databases. We identified 9285 putative novel RNA editing sites, 29% of which were also detectable neuronal transcriptomes from unrelated donors. Inhibitory neurons showed higher overall transcriptome editing than excitatory neurons. Among the strongest correlates of global editing rates were snoRNAs from the SNORD115 and SNORD116 cluster (15q11), known to modulate serotonin receptor processing and to colocalize with ADAR2. We identified 29 genes preferentially edited in excitatory neurons and 44 genes edited more heavily in inhibitory neurons including RBFOX1, its target genes and small nucleolar RNA-associated genes in the autism-associated Prader-Willi locus 15q11. These results provide cell-type and spatial context for 1730 and 910 sites that are also edited in the brains of schizophrenic and autistic patients respectively, and a reference for future studies of RNA editing in single brain cells from these cohorts. CONCLUSIONSRNA editing, including thousands of previously unreported sites, is robustly detectable in single neuronal nuclei, where gene editing differences are stronger between cell subtypes than between cortical regions. Insufficient editing of ASD-related genes in inhibitory neurons may manifest in the specific perturbation of these cells in autism.

neuroscience↗

bioRxiv2019

Orthogonal proteomic platforms and their implications for the stable classification of high-grade serous ovarian cancer subtypes

The National Cancer Institute (NCI) Clinical Proteomic Tumor Analysis Consortium (CPTAC) has established a two-dimensional liquid chromatography-tandem mass spectrometry (2DLC-MS/MS) workflow using isobaric tagging to compare protein abundance across samples. The workflow has been used for large-scale clinical proteomic studies with deep proteomic coverage within and outside of CPTAC. SWATH-MS, an instance of data-independent acquisition (DIA) proteomic methods, was recently developed as an alternate proteomic approach. In this study, we analyzed remaining aliquots of peptides using SWATH-MS from the original retrospective TCGA samples generated for the CPTAC ovarian cancer proteogenomic study (Zhang et al., 2016). The SWATH-MS results indicated that both methods confidently identified differentially expressed proteins in enriched pathways associated with the robust Mesenchymal subtype of high-grade serous ovarian cancer (HGSOC) and the homologous recombination deficient tumors also present in the original study. The results demonstrated that SWATH/DIA-MS presents a promising complementary or orthogonal alternative to the CPTAC harmonized proteomic method, with the advantages of simpler, faster, and cheaper workflows, as well as lower sample consumption. However, the SWATH/DIA-MS workflow resulted in shallower proteome coverage. Overall, we concluded that both analytical methods are suitable to characterize clinical samples such as in the high-grade serous ovarian cancer study, providing proteomic workflow alternatives for cancer researchers depending on the specific goals and context of the studies.

cancer biology↗