Biology subjects

Kerfoot, S. M.

Publications and source records attributed to Kerfoot, S. M..

7 recordsLinked to original sources

bioRxiv2025

B cell subsets have different capacities for phagocytosis and subsequent presentation of antigen to cognate T cells

B cells have been shown to be phagocytic under some circumstances. However, the phagocytic capacity of different B cell subsets and how this is linked to Antigen (Ag) presentation or other functions has not been characterized. To address this, we developed 2 {micro}m phagocytic Ag conjugated bead targets that target phagocytic pathways including the BCR, scavenger, Fc, and complement receptors to study potential pathways by which B cells phagocytose both cognate and non-cognate Ags. We found that while follicular B2 (Fo B), marginal zone, and B1 B cells are highly phagocytic of BCR-engaging targets through their BCR, only peritoneal cavity B1 cells could uptake non-cognate Ag-coated beads or bacteria. Despite this, B1 cells were not effective at presenting Ag to activate cognate T cells or at killing phagocytosed bacteria. Finally, analysis of scRNA-seq data revealed that these differences in phagocytic capacity could not be explained by differential expression of relevant phagocytic receptors, implying that there is likely some form of regulation in place preventing non-cognate Ag uptake by Fo B cells. Our work will help contribute to a better understanding of non-classical Ag uptake mechanisms employed by B cells and their relevance to inflammation.

immunology↗

bioRxiv2024

Integrative Data Analysis to Uncover Transcription Factors Involved in Gene Dysregulation of Nine Autoimmune and Inflammatory Diseases

Autoimmune and inflammatory diseases are a group of > 80 complex diseases caused by loss of immune tolerance for self-antigens. The biological mechanisms of autoimmune diseases are largely unknown, preventing the development of effective treatment options. Integrative analysis of genome-wide association studies and chromatin accessibility data has shown that the risk variants of autoimmune diseases are enriched in open chromatin regions of immune cells, supporting their role in gene regulation. However, we still lack a systematic and unbiased identification of transcription factors involved in disease gene regulation. We hypothesized that for some of the disease-relevant transcription factors, their binding to DNA is affected at multiple genomic sites rather than a single site, and these effects are cell-type specific. We developed a statistical approach to assess enrichment of transcription factors in being affected by disease risk variants at multiple genomic sites. We used genetic association data of nine autoimmune diseases and identified 99% credible set SNPs for each trait. We then integrated the credible SNPs and chromatin accessibility data of 376 samples comprising 35 unique cell types, and employed a probabilistic model to identify the SNPs that are likely to change binding probability of certain transcription factors at specific cell types. Finally, for each transcription factor, we used a statistical test to assess whether the credible SNPs show enrichments in terms of changing the binding probability of that transcription factor at multiple sites. Our analysis resulted in identification of significantly enriched transcription factors and their relevant cell types for each trait. The prioritized immune cell types varied across the diseases. Our analysis proved that our predicted regulatory sites are active enhancers or promoters in the relevant cell types. Additionally, our pathway analysis showed that the majority of the significant biological pathways are immune-related. In summary, our study has identified disease-relevant transcription factors and their relevant cell types, and will facilitate discovering specific gene regulatory mechanisms of autoimmune diseases.

genomics↗

bioRxiv2023

Global Pannexin 1-deletion increases tumor-infiltrating lymphocytes in the BRAF/Pten mouse melanoma model.

Immunotherapies for malignant melanoma seek to boost the anti-tumoral response of CD8+ T cells but have a limited patient response rate, in part due to limited tumoral immune cell infiltration. Genetic or pharmacological inhibition of Pannexin 1 (PANX1) channel-forming protein is known to decrease melanoma cell tumorigenic properties in vitro and ex vivo. Here, we crossed Panx1 knockout (Panx1-/-) mice with the inducible melanoma model: BrafCA, PtenloxP, Tyr::CreERT2 (BPC). We found that deleting the Panx1 gene in mice does not reduce BRAF(V600E)/Pten-driven primary tumor formation or improve survival. However, BPC-Panx1-/- mice tumors exhibited a significant increase in infiltration of CD8+ T lymphocytes with no changes in the expression of early T cell activation marker CD69, LAG-3 checkpoint receptor or PD-L1 in tumors when compared to BPC-Panx1+/+ genotype. Our results suggest that although a Panx1 deletion does not overturn the aggressive BRAF/Pten-driven melanoma progression in vivo, it does increase the infiltration of effector immune T cell populations in the tumor microenvironment. We propose that PANX1-targeted therapy could be explored as a strategy to increase tumor-infiltrating lymphocytes to boost anti-tumor immunity.

cancer biology↗

bioRxiv2022

Pre-Germinal Center Interactions with T Cells are Natural Checkpoints to Limit Autoimmune B Cell Responses

Interactions with antigen-specific T cells drive B cells activation and fate choices that ultimately determine the quality of high-affinity antibody responses. As such, thse interactions, and especially the long-lived interactions that occur prior to germinal center formation, may be important checkpoints to regulate undesirable responses. We directly observed interactions between T and B cells responding to the self-antigen Myelin Oligodendrocyte Glycoprotein (MOG) and found that they are of lower quality compared to interactions between cells responding to the model foreign antigen NP-ovalbumin (NP-OVA). This was associated with reduced expression of molecules that facilitate these interactions on the B cells but not on T cells. B cell expression of these molecules was not dictated by the T cell partner, nor could the relative lack of expression on MOG-sp. B cells be reversed by a multivalent antigen. Instead, MOG-sp. B cells were inherently less responsive to B cell Receptor stimulation than MOG-non-sp. cells. However, the phenotype of MOG-sp. B cells was not consistent with previous descriptions of autoimmune B cells that had been tolerized via regular exposure to systemically-expressed self-antigen. This suggests that alternate anergy pathways may exist to limit B cell responses to tissue-restricted self-antigens.

immunology↗

bioRxiv2021

Superantigens promote Staphylococcus aureus bloodstream infection by eliciting pathogenic interferon-gamma (IFNγ) production that subverts macrophage function

Staphylococcus aureus is a foremost bacterial pathogen responsible for a vast array of human diseases. Staphylococcal superantigens (SAgs) constitute a family of potent exotoxins secreted by S. aureus, and SAg genes are found ubiquitously in human isolates. SAgs bind directly to MHC class II molecules and T cell receptors, driving extensive T cell activation and cytokine release. Although these toxins have been implicated in serious disease including toxic shock syndrome, we aimed to further elucidate the mechanisms by which SAgs contribute to staphylococcal pathogenesis during septic bloodstream infections. As most conventional mouse strains respond poorly to staphylococcal SAgs, we utilized transgenic mice encoding humanized MHC class II molecules (HLA-DR4) as these animals are much more susceptible to SAg activity. Herein, we demonstrate that SAgs contribute to the severity of S. aureus bacteremia by increasing bacterial burden, most notably in the liver. We established that S. aureus bloodstream infection severity is mediated by CD4+ T cells and interferon-gamma (IFN{gamma}) is produced to very high levels during infection in a SAg-dependent manner. Bacterial burden and disease severity were reduced by antibody blocking of IFN{gamma}, phenocopying isogenic SAg deletion mutant strains. Additionally, cytokine analysis demonstrated that the immune system was skewed towards a proinflammatory response that was reduced by IFN{gamma} blocking. Infection kinetics and flow cytometry analyses suggested this was a macrophage driven mechanism, which was confirmed through macrophage depletion experiments. Further validation with human leukocytes indicated that excessive IFN{gamma} allowed S. aureus to replicate at a higher rate within macrophages. Together, this suggests that SAgs promote S. aureus survival by manipulating immune responses that would otherwise be effective at clearing S. aureus. This work implicates SAg toxins as critical targets for preventing persistent or severe S. aureus disease.

microbiology↗

bioRxiv2021

Systemic administration of anti-CD20 indirectly reduces B cells in the inflamed meninges in a chronic model of central nervous system autoimmunity

Anti-CD20 B cell depleting therapies have demonstrated that B cells are important drivers of disease progress in Multiple Sclerosis, although the pathogenic mechanisms are not well understood. A population of B cells accumulates in the inflamed meninges in MS and also some chronic animal models of disease, typically adjacent to demyelinating lesions. The role of these meningeal B cells in disease is not known, nor is their susceptibility to anti-CD20 therapy. Here, we administered anti-CD20 to 2D2 IgHMOG spontaneous experimental autoimmune encephalomyelitis mice in the chronic phase of disease, after the establishment of meningeal B cell clusters. Compared to the circulation, lymph nodes, and spleen, B cell depletion from the CNS was delayed and not evident until 7d post administration of anti-CD20. Further, we did not find evidence that anti-CD20 accessed meningeal B cells directly, but rather that depletion was indirect and the result of ongoing turnover of the meningeal population and elimination of the peripheral pool from which it is sustained. The reduction of B cell numbers in the CNS coincided with less demyelination of the spinal cord white matter and also, surprisingly, an increase in the number of T cells recruited to the meninges but not parenchyma.

immunology↗

bioRxiv2018

Autoreactive T cells preferentially drive differentiation of non-responsive memory B cells at the expense of germinal center maintenance.

B cell fate decisions within a germinal center (GC) are critical to determining the outcome of the immune response to a given antigen. Here, we characterize GC kinetics and B cell fate choices in a response to the autoantigen myelin oligodendrocyte glycoprotein (MOG), and compare them the response to a standard model foreign antigen (NP-haptenated ovalbumin, NPOVA). Both antigens generated productive primary responses, as evidenced by GC development, circulating antigen-specific antibodies, and differentiation of memory B cells. However, in the MOG response the status of the cognate T cell partner drove preferential B cell differentiation to a memory phenotype at the expense of GC maintenance, resulting in a truncated GC. Reduced plasma cell differentiation was largely independent of T cell influence. Interestingly, memory B cells formed in the MOG GC were unresponsive to secondary challenge and this could not be overcome with T cell help.

immunology↗