Biology subjects

Tomlinson, G. S.

Publications and source records attributed to Tomlinson, G. S..

5 recordsLinked to original sources

bioRxiv2024

Single-cell transcriptome and T cell receptor profiling of the tuberculin skin test

The tuberculin skin test (TST) is a cutaneous delayed hypersensitivity reaction to antigen from Mycobacterium tuberculosis (Mtb). We provide the first single cell sequencing characterisation of the human TST reaction, based on skin suction blisters induced at the site of the TST on day 2 in 31 individuals. Integrated single cell RNA and TCR sequencing showed the immune response to be dominated by T cells, with smaller populations of NK cells and myeloid cells. T cells comprised CD4, CD8, gamma/delta and NK T cells, with 50% of all T cells identified as cytotoxic and 14% as regulatory. Interferon gamma gene expression was strongest in CD8 T cells, and distinct CD4 T helper lineages could not unambiguously be identified at this time point. Amongst myeloid cells, 63% displayed antimicrobial gene expression and 28% were functionally polarised towards antigen presentation with higher levels of HLA class 2 expression. We derived and validated transcriptional signatures for cell types and cellular functions relevant to the immune landscape of the TST. These data help to improve our understanding of the immune response to Mtb and enable further exploration of bulk transcriptomic data through context-specific cellular deconvolution.

immunology↗

bioRxiv2023

Tribbles1 and Cop1 cooperate to protect the host during in vivo mycobacterial infection

Tuberculosis is a major global health problem and is one of the top 10 causes of death worldwide. There is a pressing need for new treatments that circumvent emerging antibiotic resistance. Mycobacterium tuberculosis parasitises macrophages, reprogramming them to establish a niche in which to proliferate, therefore macrophage manipulation is a potential host-directed therapy if druggable molecular targets could be identified. The pseudokinase Tribbles1 (Trib1) regulates multiple innate immune processes and inflammatory profiles making it a potential drug target in infections. Trib1 controls macrophage function, cytokine production and macrophage polarisation. Despite wide-ranging effects on leukocyte biology, data exploring the roles of Tribbles in infection in vivo are limited. Here, we identify that human Tribbles 1 is expressed in monocytes and is upregulated at the transcript level after stimulation with mycobacterial antigen. To investigate the mechanistic roles of Tribbles in the host response to mycobacteria in vivo, we used a zebrafish Mycobacterium marinum (Mm) infection tuberculosis model. Zebrafish Tribbles family members were characterised and shown to have substantial mRNA and protein sequence homology to their human orthologues. trib1 overexpression was host-protective against Mm infection, reducing burden by approximately 50%. Conversely, trib1 knockdown exhibited increased infection. Mechanistically, trib1 overexpression significantly increased the levels of pro-inflammatory factors il-1{beta} and nitric oxide. The host-protective effect of trib1 was found to be dependent on the E3 ubiquitin kinase Cop1. These findings highlight the importance of Trib1 and Cop1 as immune regulators during infection in vivo and suggest that enhancing macrophage TRIB1 levels may provide a tractable therapeutic intervention to improve bacterial infection outcomes in tuberculosis.

immunology↗

bioRxiv2019

Shigella sonnei infection of zebrafish reveals that O-antigen mediates neutrophil tolerance and dysentery incidence

Shigella flexneri is historically regarded as the primary agent of bacillary dysentery, yet the closely-related Shigella sonnei is replacing S. flexneri, especially in developing countries. The underlying reasons for this dramatic shift are mostly unknown. Using a zebrafish (Danio rerio) model of Shigella infection, we discover that S. sonnei is more virulent than S. flexneri in vivo. Whole animal dual-RNAseq and testing of bacterial mutants suggest that S. sonnei virulence depends on its O-antigen oligosaccharide (which is unique among Shigella species). We show in vivo using zebrafish and ex vivo using human neutrophils that S. sonnei O-antigen can mediate neutrophil tolerance. Consistent with this, we demonstrate that O-antigen enables S. sonnei to resist phagolysosome acidification and promotes neutrophil cell death. Chemical inhibition or promotion of phagolysosome maturation respectively decreases and increases neutrophil control of S. sonnei and zebrafish survival. Strikingly, larvae primed with a sublethal dose of S. sonnei are protected against a secondary lethal dose of S. sonnei in an O-antigen-dependent manner, indicating that exposure to O-antigen can train the innate immune system against S. sonnei. Collectively, these findings reveal O-antigen as an important therapeutic target against bacillary dysentery, and may explain the rapidly increasing S. sonnei burden in developing countries.\n\nAuthor SummaryShigella sonnei is predominantly responsible for dysentery in developed countries, and is replacing Shigella flexneri in areas undergoing economic development and improvements in water quality. Using Shigella infection of zebrafish (in vivo) and human neutrophils (in vitro), we discover that S. sonnei is more virulent than S. flexneri because of neutrophil tolerance mediated by its O-antigen oligosaccharide acquired from the environmental bacteria Plesiomonas shigelloides. To inspire new approaches for S. sonnei control, we show that increased phagolysosomal acidification or innate immune training can promote S. sonnei clearance by neutrophils in vivo. These findings have major implications for our evolutionary understanding of Shigella, and may explain why exposure to P. shigelloides in low and middle-income countries (LMICs) can protect against dysentery incidence.

microbiology↗

bioRxiv2019

Analysis tools to quantify dissemination of pathology in zebrafish larvae

We used the zebrafish larval Mycobacterium marinum infection model of tuberculosis to develop image analysis software called QuantiFish, to enable rapid, objective quantitation of bacterial load and dissemination. Our analysis tools provide novel outcome measures of infection; the proportional distribution of bacteria between sites and their spatial distribution throughout the host. We anticipate the broader application of these parameters to other zebrafish models of infection and metastatic cancer.

microbiology↗

bioRxiv2019

Exaggerated in vivo IL-17 responses discriminate recall responses in active TB

Host immune responses at the site of Mycobacterium tuberculosis (Mtb) infection serve to contain the pathogen, but also mediate the pathogenesis of tuberculosis (TB) and onward transmission of infection. Interferon gamma (IFN{gamma}) responses do not discriminate between protection and pathogenicity, but IL-17A/F responses, known to drive pathology in diverse chronic inflammatory diseases, have also been associated with TB pathogenesis in animal models. At the site of in vivo immune recall responses to Mtb modelled by the tuberculin skin test, we show for the first time that active TB in humans is also associated with exaggerated IL-17A/F expression, accumulation of Th17 cells and IL-17A/F bioactivity, including increased neutrophil recruitment and matrix metalloproteinase-1 expression directly implicated in TB pathogenesis. These features discriminate recall responses in patients with active TB from those with cured or latent infection and are also evident at the site of TB disease. Our data support targeting of this pathway in host-directed therapy for TB.

immunology↗