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Grainger, J. R.

Publications and source records attributed to Grainger, J. R..

5 recordsLinked to original sources

CellTypeAI: Automated cell identification for scRNA-seq using local generative-AI

Single-cell RNA sequencing (scRNA-seq) cell annotation techniques rely on the matching of known defining marker genes to a given cell population. However, these methods may lack robustness to dynamic fluctuations in cell marker expression between patients, samples and pathologies. The advent of easy-to-implement predictive technologies, like generative-AI (gen-AI), has facilitated the introduction of computational workflows that improve otherwise inaccurate context-dependent cell type annotation. Here, we introduce CellTypeAI, a streamlined, scalable program developed for tissue context-dependent cell annotation of scRNA-seq datasets using modern gen-AI models, enhanced by retrieval augmented generation methods. Our implementation builds upon local gen-AI hosting technologies and directly integrates into scRNA-seq analysis pipelines. We show that CellTypeAI provides improved annotation accuracy compared to current conventional annotation methods and nascent cloud-based gen-AI approaches. As CellTypeAI leverages locally-run AI models, it can be applied to sensitive datasets, unlike approaches utilising online gen-AI tools such as ChatGPT, DeepSeek, or Claude. CellTypeAI presents a novel solution for tissue-specific cell type identification, overcoming traditional marker-based limitations via locally-deployed generative-AI models. Contactjohn.grainger-2@manchester.ac.uk; magnus.rattray@manchester.ac.uk

bioinformatics↗

Comprehensive analysis of myeloid reporter mice

Macrophages are a pivotal cell type within the synovial lining and sub-lining of the joint, playing a crucial role in maintaining homeostasis of synovium. Although fate-mapping techniques have been employed to differentiate synovial macrophages from other synovial myeloid cells, no comprehensive study has yet been conducted within the mouse synovial macrophage compartment. In this study, we present, for the first time, lineage tracing results from 18 myeloid-specific fate-mapping models in mouse peripheral blood (PB) and synovial tissue. The identification of synovial macrophages and monocyte-lineage cells through flow cytometry was further validated using cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) datasets. These findings provide a valuable methodological tool for researchers to select appropriate models for studying the function of synovial myeloid cells and serve as a reference for investigations in other tissue types.

immunology↗

CD163 and Tim-4 identify resident intestinal macrophages across sub-tissular regions that are spatially regulated by TGF-β

In bodily organs, macrophages are localised in poorly understood tissular and sub-tissular niches associated with defined macrophage ontogeny and activity. In the intestine, a paradigm is emerging that long-lived macrophages are dominantly present in the muscular layer, while highly monocyte-replenished populations are found in the lamina propria beneath the epithelial barrier. Whether longevity is restricted in such a simplified manner has not been well explored. Moreover, the impact of specific gut-associated factors on long-lived macrophage functionality and niche occupancy is unknown. We generated sc-RNA-Seq data from wild-type and Ccr2-/- mice to identify phenotypic features of long-lived macrophage populations in distinct intestinal niches and identified CD163 as a useful marker to distinguish submucosal/muscularis (S/M) from lamina propria (LP) macrophages. Challenging the emerging paradigm, long-lived macrophages, identified by Tim-4 expression, were found in the LP and S/M. Long-lived LP macrophages are restrained in their response to proinflammatory stimulation compared to short-lived populations in the same location, and to the long-lived population within the S/M. Employing a novel Timd4creTgfbr2fl/fl mouse line we demonstrate distinct functions of TGF-{beta} on long-lived macrophages in these two compartments. Importantly, in Timd4creTgfbr2fl/fl mice, zonation of CD163+ macrophages in the S/M was lost, suggesting TGF-{beta} plays an unappreciated role in positioning of macrophages in the tissue. These data highlight the importance of considering ontogeny and niche when assessing the action of key intestinal regulatory signals.

immunology↗

Distinct eosinophil subsets are modulated by agonists of the commensal-metabolite and vitamin B3 receptor GPR109A during allergic-type inflammation

Eosinophils are key contributors to allergic pathology, however, increasingly eosinophils are described to have important roles in organ health and immunoregulation. Factors that impact these diverse functions of eosinophils are not understood. Here we show in allergic-type lung inflammation, metabolically distinct populations of eosinophils can be identified based on expression of Siglec-F (Siglec-Fhi and Siglec-Fint). Notably, the lung Siglec-Fhi population was responsive to the commensal microbiome, expressing the short-chain fatty acid receptor GPR109A. Animals deficient in GPR109A displayed augmented eosinophilia during allergy. Moreover, transferred GPR109A-deficient eosinophils released more eosinophil peroxidase than controls. Treatment with butyrate or vitamin B3, both GPR109A ligands, reduced Siglec-Fhi eosinophil frequency and activation, which was associated with apoptosis of Siglec-Fhi eosinophils. These findings identify GPR109A as an unappreciated regulator of glycolytic Siglec-Fhi eosinophils, raising the possibility of depleting pathological eosinophil populations in disease states while sparing those with homeostatic functions.

immunology↗

Treatment with IgM-enriched intravenous immunoglobulins (IgM-IVIg) enhances clearance of stroke-associated bacterial lung infection

Post-stroke infection is a common complication of stroke that is associated with increased mortality and morbidity. We previously found that experimental stroke induces an ablation of multiple sub-populations of B cells and reduced levels of IgM antibody that coincide with the development of spontaneous bacterial pneumonia. Reduced circulating IgM concentrations were also observed in acute stroke patients. The loss of IgM antibody after stroke could be an important determinant of infection susceptibility and highlights this pathway as an important target for intervention. We treated mice with a low (replacement), dose of IgM-enriched intravenous immunoglobulin (IgM-IVIg) prior to and 24 h after experimental stroke induced by middle cerebral artery occlusion (MCAO) or sham surgery, then recovered mice for 2 d or 5 d. The effect of treatment on lung bacterial burden, lung pathology, brain infarct volume, antibody levels and both lung and systemic cellular and cytokine immune profiles was determined. Treatment with IgM-IVIg enhanced bacterial clearance from the lung after MCAO and improved pathology but did not impact infarct volume. IgM-IVIg treatment induced immunomodulatory effects systemically including rescue of splenic plasma B cell numbers and endogenous mouse IgM and IgA circulating immunoglobulin concentrations that were reduced by MCAO, and treatment also reduced concentrations of pro-inflammatory cytokines in the lung. The effects of MCAO and IgM-IVIg treatment on the immune system were tissue specific as no impact on B cells or mouse immunoglobulins were found within the lung. However, the presence of human immunoglobulins from the IgM-IVIg treatment led to increased total lung immunoglobulin concentration. IgM-IVIg treatment did not increase the number of lung mononuclear phagocytes or directly modulate macrophage phagocytic capacity but enhanced their capability to phagocytose Staphylococcus aureus bioparticles in vitro by increasing opsonisation. Low dose IgM-IVIg contributes to increased clearance of spontaneous lung bacteria after MCAO likely via increasing availability of antibody in the lung to enhance phagocytic activity. Immunomodulatory effects of IgM-IVIg treatment, including reduced pro-inflammatory cytokine production, may also contribute to reduced levels of damage in the lung after MCAO. IgM-IVIg shows promise as an antibacterial and immunomodulatory agent to use in the treatment of post-stroke infection. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/472965v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1c8684forg.highwire.dtl.DTLVardef@384688org.highwire.dtl.DTLVardef@9eb7f7org.highwire.dtl.DTLVardef@3fe58e_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗