Biology subjects

Thomas, P.

Publications and source records attributed to Thomas, P..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

RBM39 degrader invigorates natural killer cells to eradicate neuroblastoma despite cancer cell plasticity

The cellular plasticity of neuroblastoma is defined by a mixture of two major cell states, adrenergic (ADRN) and mesenchymal (MES), which may contribute to therapy resistance. However, how neuroblastoma cells switch cellular states during therapy remains largely unknown and how to eradicate neuroblastoma regardless of their cell states is a clinical challenge. To better understand the lineage switch of neuroblastoma in chemoresistance, we comprehensively defined the transcriptomic and epigenetic map of ADRN and MES types of neuroblastomas using human and murine models treated with indisulam, a selective RBM39 degrader. We showed that cancer cells not only undergo a bidirectional switch between ADRN and MES states, but also acquire additional cellular states, reminiscent of the developmental pliancy of neural crest cells. The lineage alterations are coupled with epigenetic reprogramming and dependency switch of lineage-specific transcription factors, epigenetic modifiers and targetable kinases. Through targeting RNA splicing, indisulam induces an inflammatory tumor microenvironment and enhances anticancer activity of natural killer cells. The combination of indisulam with anti-GD2 immunotherapy results in a durable, complete response in high-risk transgenic neuroblastoma models, providing an innovative, rational therapeutic approach to eradicate tumor cells regardless of their potential to switch cell states.

cancer biology↗

bioRxiv2024

Learning predictive signatures of HLA type from T-cell repertoires

T cells recognize a wide range of pathogens using surface receptors that interact directly with pep-tides presented on major histocompatibility complexes (MHC) encoded by the HLA loci in humans. Understanding the association between T cell receptors (TCR) and HLA alleles is an important step towards predicting TCR-antigen specificity from sequences. Here we analyze the TCR alpha and beta repertoires of large cohorts of HLA-typed donors to systematically infer such associations, by looking for overrepresentation of TCRs in individuals with a common allele.TCRs, associated with a specific HLA allele, exhibit sequence similarities that suggest prior antigen exposure. Immune repertoire sequencing has produced large numbers of datasets, however the HLA type of the corresponding donors is rarely available. Using our TCR-HLA associations, we trained a computational model to predict the HLA type of individuals from their TCR repertoire alone. We propose an iterative procedure to refine this model by using data from large cohorts of untyped individuals, by recursively typing them using the model itself. The resulting model shows good predictive performance, even for relatively rare HLA alleles.

immunology↗

bioRxiv2023

Feedback between stochastic gene networks and population dynamics enables cellular decision making

Phenotypic selection occurs when genetically identical cells are subject to different reproductive abilities due to cellular noise. Such noise arises from fluctuations in reactions synthesising proteins and plays a crucial role in how cells make decisions and respond to stress or drugs. We propose a general stochastic agent-based model for growing populations capturing the feedback between gene expression and cell division dynamics. We devise a finite state projection approach to analyse gene expression and division distributions and infer selection from single-cell data in mother machines and lineage trees. We use the theory to quantify selection in multi-stable gene expression networks and elucidate that the trade-off between phenotypic switching and selection enables robust decision-making essential for synthetic circuits and developmental lineage decisions. Using live-cell data, we demonstrate that combining theory and inference provides quantitative insights into bet-hedging-like response to DNA damage and adaptation during antibiotic exposure in Escherichia coli.

systems biology↗

bioRxiv2023

Targeting pediatric High-Grade Gliomas with OAcGD2-CAR Vδ2 T cells

PurposePediatric high-grade gliomas (pHGG) belong to a family of rare childrens cancers which are treated with radiotherapy, based on adult high-grade glioma standard of care. However, new treatments are definitively required since actual ones are unable to extend survival by more than a few months in most patients. In this study, we investigate a Chimeric Antigen Receptor (CAR)-T cell immunotherapy targeting the OAcGD2 ganglioside, using either conventional {beta} or V{delta}2 T cells as effectors. Materials and methodsUsing relevant human primary models of pHGG, we first characterized the innate V{delta}2 T cell immunoreactivity. Then, following the validation of OAcGD2 expression in these tumor cells, we evaluated both {beta} and V{delta}2 OAcGD2-CAR-T cell immunoreactivity using various methods including videomicroscopy, FACS and cytotoxicity assays. ResultsWe showed that pHGG primary cells are not spontaneously recognized and killed by V{delta}2 T cells but significantly expressed the OAcGD2 ganglioside. Accordingly, both {beta} and V{delta}2 T cells engineered to express a CAR against the OAcGD2 efficiently killed pHGG cells in 2D and 3D models. Importantly, only V{delta}2 T cells transduced with the complete OAcGD2-CAR eliminated pHGG cells, in contrast to conventional {beta} CAR-T cells that killed tumor cells even in the absence of CAR expression, highlighting the allogeneic potential of V{delta}2 CAR-T cells. ConclusionOur study demonstrates the preclinical relevance of targeting OAcGD2 in pHGG using CAR-T cells. Furthermore, we also clearly demonstrate the clinical benefits of using V{delta}2 T cells as CAR effectors in allogeneic settings allowing an off-the-shelf immunotherapy.

cancer biology↗

bioRxiv2023

Dynamics of the viral community on the cheese surface during maturation and persistence across production years

The surface of smear-ripened cheeses constitutes a dynamic microbial ecosystem resulting from the successive development of different microbial groups such as lactic acid bacteria, fungi and ripening bacteria. Recent studies indicate that a viral community, mainly composed of bacteriophages, also represents a common and substantial part of the cheese microbiome. However, the composition of this community, its temporal variations and associations between bacteriophages and their hosts remain poorly characterized. Here, we studied a French smear-ripened cheese by both viral metagenomics and 16S metabarcoding approaches to assess both the succession of phages and bacterial communities on the cheese surface during cheese ripening, and their temporal variations in ready-to-eat cheeses over the years of production. We observed a clear transition of the phage community structure during ripening with a decreased relative abundance of viral species (vOTUs) associated with Lactococcus phages, which were replaced by vOTUs associated with phages infecting ripening bacteria such as Brevibacterium, Glutamicibacter, Pseudoalteromonas and Vibrio. The dynamics of the phage community was strongly associated with bacterial successions observed on the cheese surface. Finally, while some variations in the distribution of phages were observed in ready-to-eat cheeses produced at different dates spanning more than 4 years of production, the most abundant phages were detected throughout. This result revealed the long-term persistence of the dominant phages in the cheese production environment. Together, these findings offer novel perspectives on the ecology of bacteriophages in smear-ripened cheese and emphasize the significance of incorporating bacteriophages in the microbial ecology studies of fermented foods. IMPORTANCEThe succession of diverse microbial populations is critical for ensuring the production of high-quality cheese. We observed a temporal succession of phages on the surface of a smear-ripened cheese, with new phage communities showing up at the time when ripening bacteria start covering this surface. Interestingly, the final phage community of this cheese is also consistent over large periods of time, as the same bacteriophages were found in cheese products from the same manufacturer made over 4-years. This research highlights the importance of considering these bacteriophages when studying the microbial life of fermented foods like cheese.

microbiology↗

bioRxiv2023

Longitudinal stability of individual brain plasticity patterns in blindness

The primary visual cortex (V1) in individuals born blind is engaged in a wide spectrum of tasks and sensory modalities, including audition, touch, language, and memory. This widespread involvement raises questions regarding the constancy of its role and whether it might exhibit flexibility in its function over time, connecting to diverse network functions in response to task-specific demands. This would suggest that reorganized V1 takes on a role similar to cognitive multiple-demand system regions. Alternatively, it is possible that the varying patterns of plasticity observed in the blind V1 can be attributed to individual factors, whereby different blind individuals recruit V1 for different functions, highlighting the immense idiosyncrasy of plasticity. In support of this second account, we have recently shown that V1 functional connectivity varies greatly across blind individuals. But do these represent stable individual patterns of plasticity or merely instantaneous changes, for a multiple-demand system now inhabiting V1? Here we tested if individual connectivity patterns from the visual cortex of blind individuals are stable over time. We show that over two years, fMRI functional connectivity from the primary visual cortex is unique and highly stable in a small sample of repeatedly sampled congenitally blind individuals. Further, using multivoxel pattern analysis, we demonstrate that the unique reorganization patterns of these individuals allow decoding of participant identity. Together with recent evidence for substantial individual differences in visual cortex connectivity, this indicates there may be a consistent role for the visual cortex in blindness, which may differ for each individual. Further, it suggests that the variability in visual reorganization in blindness across individuals could be used to seek stable neuromarkers for sight rehabilitation and assistive approaches.

neuroscience↗

bioRxiv2023

Global transcription regulation revealed from dynamical correlations in time-resolved single-cell RNA-sequencing

Single-cell transcriptomics reveals significant variations in the transcriptional activity across cells. Yet, it remains challenging to identify mechanisms of transcription dynamics from static snapshots. It is thus still unknown what drives global transcription dynamics in single cells. We present a stochastic model of gene expression with cell size- and cell cycle-dependent rates in growing and dividing cells that harnesses temporal dimensions of single-cell RNA-sequencing through metabolic labelling protocols and cell cycle reporters. We develop a parallel and highly scalable Approximate Bayesian Computation method that corrects for technical variation and accurately quantifies absolute burst frequency, burst size and degradation rate along the cell cycle at a transcriptome-wide scale. Using Bayesian model selection, we reveal scaling between transcription rates and cell size and unveil waves of gene regulation across the cell cycle-dependent transcriptome. Our study shows that stochastic modelling of dynamical correlations identifies global mechanisms of transcription regulation.

systems biology↗

bioRxiv2023

Diet-induced obesity impacts influenza disease severity and transmission dynamics in ferrets

Obesity, and the associated metabolic syndrome, is a risk factor for increased disease severity with a variety of infectious agents, including influenza virus. Yet the mechanisms are only partially understood. As the number of people, particularly children, living with obesity continues to rise, it is critical to understand the role of host status on disease pathogenesis. In these studies, we use a novel diet-induced obese ferret model and new tools to demonstrate that like humans, obesity resulted in significant changes to the lung microenvironment leading to increased clinical disease and viral spread to the lower respiratory tract. The decreased antiviral responses also resulted in obese animals shedding higher infectious virus for longer making them more likely to transmit to contacts. These data suggest the obese ferret model may be crucial to understanding obesitys impact on influenza disease severity and community transmission, and a key tool for therapeutic and intervention development for this high-risk population. TeaserA new ferret model and tools to explore obesitys impact on respiratory virus infection, susceptibility, and community transmission.

microbiology↗

bioRxiv2023

Spatiotemporal development of the human T follicular helper cell response to Influenza vaccination

We profiled blood and draining lymph node (LN) samples from human volunteers after influenza vaccination over two years to define evolution in the T follicular helper cell (TFH) response. We show LN TFH cells expanded in a clonal-manner during the first two weeks after vaccination and persisted within the LN for up to six months. LN and circulating TFH (cTFH) clonotypes overlapped but had distinct kinetics. LN TFH cell phenotypes were heterogeneous and mutable, first differentiating into pre-TFH during the month after vaccination before maturing into GC and IL-10+ TFH cells. TFH expansion, upregulation of glucose metabolism, and redifferentiation into GC TFH cells occurred with faster kinetics after re-vaccination in the second year. We identified several influenza-specific TFH clonal lineages, including multiple responses targeting internal influenza proteins, and show each TFH state is attainable within a lineage. This study demonstrates that human TFH cells form a durable and dynamic multi-tissue network.

immunology↗

bioRxiv2023

Integrated genomic and functional analyses of human skin-associated Staphylococcus reveals extensive inter- and intra-species diversity

Human skin is stably colonized by a distinct microbiota that functions together with epidermal cells to maintain a protective physical barrier. Staphylococcus, a prominent genus of the skin microbiota, participates in colonization resistance, tissue repair, and host immune regulation in strain specific manners. To unlock the potential of engineering skin microbial communities, we aim to fully characterize the functional diversity of this genus within the context of the skin environment. We conducted metagenome and pan-genome analyses of isolates obtained from distinct body sites of healthy volunteers, providing a detailed biogeographic depiction of staphylococcal species that colonize our skin. S. epidermidis, S. capitis, and S. hominis were the most abundant species present in all volunteers and were detected at all body sites. Pan-genome analysis of these three species revealed that the genus-core was dominated by central metabolism genes. Species-specific core genes were enriched in host colonization functions. The majority ([~]68%) of genes were detected only in a fraction of isolate genomes, underscoring the immense strain-specific gene diversity. Conspecific genomes grouped into phylogenetic clades, exhibiting body site preference. Each clade was enriched for distinct gene-sets that are potentially involved in site tropism. Finally, we conducted gene expression studies of select isolates showing variable growth phenotypes in skin-like medium. In vitro expression revealed extensive intra- and inter-species gene expression variation, substantially expanding the functional diversification within each species. Our study provides an important resource for future ecological and translational studies to examine the role of shared and strain-specific staphylococcal genes within the skin environment. SIGNIFICANCEThe bacterial genus Staphylococcus is a prominent member of the human skin microbiome, performing important and diverse functions such as tuning immunity, driving tissue repair, and preventing pathogen colonization. Each of these functions is carried out by a subset of staphylococcal strains, displaying differences in gene content and regulation. Delineating the genomic and functional diversity of Staphylococcus will enable researchers to unlock the potential of engineering skin communities to promote health. Here, we present a comprehensive multi-omics analysis to characterize the inter- and intra-species diversity present in human skin-associated staphylococci. Our study is the first to conduct a detailed pan-genome comparison between prominent skin staphylococcal species giving a valuable insight into gene sharing and provides an important resource.

microbiology↗

bioRxiv2023

Modeling Antigen-Specific T Cell Dynamics Following Hepatitis B Vaccination indicates differences between conventional and regulatory T cell dynamics

Our study aims to investigate the dynamics of conventional memory T cells (Tconv) and regulatory T cells (Treg) following activation, and to explore potential differences between these two cell types. To achieve this, we developed advanced statistical mixed models based on mathematical models of ordinary differential equations (ODE), which allowed us to transform post-vaccination immunological processes into mathematical formulas. These models were applied on in-house data from a de novo Hepatitis B vaccination trial. By accounting for inter- and intra-individual variability, our models provided good fits for both antigen-specific Tconv and Treg cells, overcoming the challenge of studying these complex processes. Our modeling approach provided a deeper understanding of the immunological processes underlying T cell development after vaccination. Specifically, our analysis revealed several important findings regarding the dynamics of Tconv and Treg cells, as well as their relationship to seropositivity for HSV-1 and EBV, and the dynamics of antibody response to vaccination. Firstly, our modeling indicated that Tconv dynamics suggest the existence of two T cell types, in contrast to Treg dynamics where only one T cell type is predicted. Secondly, we found that individuals who converted to a positive antibody response to the vaccine earlier had lower decay rates for both Tregs and Tconv cells, which may have important implications for the development of more effective vaccination strategies. Additionally, our modeling showed that HSV-1 seropositivity negatively influenced Tconv cell expansion after the second vaccination, while EBV seropositivity was associated with higher Treg expansion rates after vaccination. Overall, this study provides a critical foundation for understanding the dynamic processes underlying T cell development after vaccination.

immunology↗

bioRxiv2023

Ecological monitoring using Collembola metabarcoding with extremely low bycatch amplification.

Collembola are used widely to monitor soil health and functional parameters. Recent developments in high throughput sequencing (especially metabarcoding) have substantially increased their potential for these ends. Collembola are especially amenable to metabarcoding because of their small size, high abundance, and ubiquity in most habitat types. However, most Collembola sampling protocols collect a substantial and highly varied bycatch that can be a considerable impediment to metabarcoding, especially because of data lost to non-target species. We designed a primer set amplifying the D2 expansion segment of ribosomal DNA that is highly conserved across Collembola and successfully excludes from amplification nearly all other invertebrate taxa. We tested the diagnostic power of the primer set by clearly distinguishing Collembola communities between forest sites with differing habitat qualities in Sao Paulo State, Brazil. The oligos successfully amplified targets from all Collembola orders previously encountered in the sampling locations, with no non-target amplification, and also excluded the closely related Protura and Diplura. Alpha diversity (OTU count) and phylogenetic diversity was significantly higher in high quality habitats. Moreover, the beta diversity indices successfully differentiated high and low-quality habitats. This new addition to the biomonitoring toolbox greatly increases the accessibility of Collembola metabarcoding for various types of habitat assessments.

molecular biology↗

bioRxiv2023

Modelling capture efficiency of single cell RNA-sequencing data improves inference of transcriptome-wide burst kinetics

Gene expression is characterised by stochastic bursts of transcription that occur at brief and random periods of promoter activity. The kinetics of gene expression burstiness differs across the genome and is dependent on the promoter sequence, among other factors. Single-cell RNA sequencing (scRNA-seq) has made it possible to quantify the cell-to-cell variability in transcription at a global genome-wide level. However, scRNA-seq data is prone to technical variability, including low and variable capture efficiency of transcripts from individual cells. Here, we propose a novel mathematical theory for the observed variability in scRNA-seq data. Our method captures burst kinetics and variability in both cell size and capture efficiency, which allows us to propose several likelihood-based and simulation-based methods for the inference of burst kinetics from scRNA-seq data. Using both synthetic and real data, we show that the simulation-based methods provide an accurate, robust and flexible tool for inferring burst kinetics from scRNA-seq data. In particular, in supervised manner, a simulation-based inference method based on neural networks proves to be accurate and useful in application to both allele and non-allele specific scRNA-seq data.

bioinformatics↗

bioRxiv2022

Rapid recall and de novo T cell responses during SARS-CoV-2 breakthrough infection

While the protective role of neutralising antibodies against COVID-19 is well-established, questions remain about the relative importance of cellular immunity. Using 6 pMHC-multimers in a cohort with early and frequent sampling we define the phenotype and kinetics of recalled and primary T cell responses following Delta or Omicron breakthrough infection. Recall of spike-specific CD4+ T cells was rapid, with cellular proliferation and extensive activation evident as early as 1 day post-symptom onset. Similarly, spike-specific CD8+ T cells were rapidly activated but showed variable levels of expansion. Strikingly, high levels of SARS-CoV-2-specific CD8+ T cell activation at baseline and peak were strongly correlated with reduced peak SARS-CoV-2 RNA levels in nasal swabs and accelerated clearance of virus. Our study demonstrates rapid and extensive recall of memory T cell populations occurs early after breakthrough infection and suggests that CD8+ T cells contribute to the control of viral replication in breakthrough SARS-CoV-2 infections.

immunology↗

bioRxiv2022

A small molecule RIG-I agonist serves to adjuvant broad multifaceted influenza virus vaccine immunity

Retinoic acid-inducible gene I (RIG-I) is essential for activating host cell innate immunity to regulates the immune response against many RNA viruses. We identified a small molecule compound, KIN1148, that directly binds RIG-I to drive IRF3activation to impart the expression of IRF3-target genes, including specific immunomodulatory cytokines and chemokines. KIN1148 does not lead to ATPase activity or compete with ATP for binding but activates RIG-I to induce antiviral gene expression programs distinct from type I interferon (IFN) treatment. When administered in combination with a vaccine against influenza A virus (IAV), KIN1148 induces both neutralizing antibody and broadly cross-protective IAV-specific T cell responses compared to vaccination alone, which induces comparatively poor responses. This robust KIN1148-adjuvanted immune response protects mice from lethal H1N1 and H5N1 IAV challenge. Importantly, KIN1148 also augments human CD8+ T cell activation. Thus, we have identified a small molecule RIG-I agonist that serves as an effective adjuvant in inducing non-canonical RIG-I activation for induction of innate immune programs that enhance adaptive immune protection of antiviral vaccination. SummaryHemann, et. al. identify a small-molecule RIG-I agonist (KIN1148) that directly binds RIG-I for non-canonical activation and adjuvants pandemic and avian influenza virus vaccination. KIN1148 augments broadly neutralizing antibody and T cell responses in mice and enhances human DC maturation and CD8+ T cell activation.

immunology↗

bioRxiv2022

Patterns of interdivision time correlations reveal hidden cell cycle factors

The time taken for cells to complete a round of cell division is a stochastic process controlled, in part, by intracellular factors. These factors can be inherited across cellular generations which gives rise to, often non-intuitive, correlation patterns in cell cycle timing between cells of different family relationships on lineage trees. Here, we formulate a framework of hidden inherited factors affecting the cell cycle that unifies known cell cycle control models and reveals three distinct interdivision time correlation patterns: aperiodic, alternator and oscillator. We use Bayesian inference with single-cell datasets of cell division in bacteria, mammalian and cancer cells, to identify the inheritance motifs that underlie these datasets. From our inference, we find that interdivision time correlation patterns do not identify a single cell cycle model but generally admit a broad posterior distribution of possible mechanisms. Despite this unidentifiability, we observe that the inferred patterns reveal interpretable inheritance dynamics and hidden rhythmicity of cell cycle factors. This reveals that cell cycle factors are commonly driven by circadian rhythms, but their period may differ in cancer. Our quantitative analysis thus reveals that correlation patterns are an emergent phenomenon that impact cell proliferation and these patterns may be altered in disease.

systems biology↗

bioRxiv2022

MHC-II molecules present RhoC-derived peptides on the surface of tumour cells

RhoC is an important regulator of metastasis and tumour progression across various tumour models. Since RhoC has been found to have no major contribution towards normal embryogenic development, it has emerged as a suitable therapeutic target for effective cancer treatment. Recent evidence has shown that Rho-based peptide vaccines have favourable outcomes in prostate cancer patients, by bringing about activation of CD4+ T-cells. Antigen presentation on the surface of cells is brought about by the MHC-I/MHC-II complex. This work provides conclusive evidence to show that the seemingly cytosolic protein, RhoC, is in fact, present on the surface of tumour cells. This report goes on to prove that the presentation of RhoC peptides is brought about in association with MHC-II, becoming the first piece of scientific evidence to report this phenomenon.

cancer biology↗

bioRxiv2022

Protein Kinase C Delta Regulates Mononuclear Phagocytes and Hinders Response to Immunotherapy in Cancer

Checkpoint immunotherapy unleashes T cell antitumor potential which has revolutionized cancer treatment showing unprecedented long-term responses. However, most patients do not respond to immunotherapy which often correlates with a dysfunctional or immunosuppressive myeloid compartment. The mononuclear phagocyte system (MPS) is a sub-class of myeloid cells comprising monocytes, macrophages and dendritic cells which plays a crucial role in tissue homeostasis. However, accumulating evidence suggests that mononuclear phagocytes contribute to all phases of tumorigenesis including orchestrating inflammatory events during de novo carcinogenesis, contribution to the progression of established tumors and promotion of resistance to checkpoint blockade. Thus, targeting the MPS could be an effective strategy to enhance checkpoint blockade efficacy and promote control of tumors. Here, we found that protein kinase C delta (PKC{delta}), a serine/threonine kinase, is abundantly expressed by mononuclear phagocytes in several human and mouse tumors. PKC{delta}-/- mice were more resistant to growth of various cancers compared to wild-type mice and were more responsive to anti-PD-1 immunotherapy. Furthermore, we found that tumors from PKC{delta}-/- mice harbor a Th-1-skewed immune landscape including increased antigen cross-presentation and T cell activation. Depletion of mononuclear phagocytes in vivo altered tumor growth in wild-type mice, but not in PKC{delta}-/- mice. In addition, coinjection of PKC{delta}-/--deficient M2-like macrophages with cancer cells into wild-type mice markedly delayed tumor growth and significantly increased intratumoral T cell activation compared to wild-type M2-like macrophages coinjected with cancer cells. Finally, intrinsic loss of PKC{delta}-/- functionally reprogrammed macrophages and dendritic cells by promoting their antigen presenting and cross-presenting capacity and triggered type I and type II interferon signaling. Thus, PKC{delta} might be targeted to reprogram mononuclear phagocytes and augment checkpoint blockade efficacy.

immunology↗