Biology subjects

Sheriff, L.

Publications and source records attributed to Sheriff, L..

4 recordsLinked to original sources

bioRxiv2025

Organ-specific immune responses are strain-dependent in a mouse model of Cryptococcus neoformans brain infection

Cryptococcal meningitis remains the top cause of death from an invasive fungal infection in humans, responsible for [~]100,000 deaths annually of vulnerable patients with underlying immune deficiencies. Animal models of cryptococcal meningitis are important for understanding the immune parameters that correlate with protection. However, modelling this infection in mice is challenging. There is wide variability in infection routes, doses and mouse background used in the field, which makes understanding phenotypes of mutants and immune interventions difficult to broadly apply. Our intention was to create a resource for the field on how Cryptococcus neoformans strain influences analysis of organ-specific immune responses in an intravenous mouse model of cryptococcal meningitis, focusing on impact of the fungal strain while keeping mouse genetic background (C57BL/6J) and infection route constant. We quantified myeloid and lymphoid cell recruitment and fungal-specific CD4 T-cell activation, correlating these results with fungal burdens in mice infected with the commonly used reference strain H99 or with two recently isolated clinical strains that were the same molecular type (VNI) or an unrelated type (VNB). We also analysed how dose used in murine infection models affected brain immune responses during C. neoformans infection. Our work reveals intriguing patterns of organ-specific immunity that are dependent on C. neoformans strain but not always explained by virulence potential, raising important questions for the field regarding the impact of C. neoformans strain on cellular immune responses in experimental animal models.

immunology↗

bioRxiv2024

Vancomycin impairs macrophage fungal killing by disrupting mitochondrial morphology and function

Vancomycin is a widely prescribed antibiotic used in the treatment of Gram-positive bacterial infections. We recently showed that this antibiotic disrupted protective anti-fungal immune responses via microbiome dysbiosis, enhancing susceptibility to invasive candidiasis. Antibiotics are an independent risk factor for developing this life-threatening fungal infection, but whether microbiota-independent mechanisms also drive this association is not clear. Here, we show that vancomycin directly impairs macrophage responses to Candida albicans, the main causative agent of invasive candidiasis. Vancomycin-treated macrophages were less able to kill C. albicans despite normal phagocytosis rates and were hyper-inflammatory and more likely to die during infection. We found that vancomycin bound to macrophage mitochondria, leading to depolarisation, reduced respiratory capacity and a hyper-fragmented morphology associated with increased ROS production. Taken together, this work demonstrates direct effects of vancomycin on mammalian immune cells, helping us to understand pro-inflammatory effects of this drug and how it promotes susceptibility to life-threatening fungal infection.

immunology↗

bioRxiv2024

Interferonγ and IL-27 positively regulate type 1 regulatory T-cell development during adaptive tolerance

Strong T-cell receptor (TCR) and IL-27 signalling influence type-1 regulatory (Tr1) T-cell development but whether other signals determine their differentiation is unclear. Utilising Tg4 TCR transgenic mice we established a model for rapid Tr1 cell induction. A single high dose of [4Y]-MBP peptide drove the differentiation of Il10+ T-cells with bona fide Tr1 cell protein and mRNA signatures. Kinetic transcriptional analysis revealed that the Tr1 cell module was transient and preceded by a burst of Ifng transcription in CD4+ T-cells. Neutralisation of IFN{gamma} reduced Tr1 cell frequency and strong TCR signalling markers, which was correlated with reduced macrophage activation. Antibody depletion experiments inferred that T-cells - but not NK cells - provided the relevant source of IFN{gamma}. Additionally, we show that blocking IL-27 in combination with IFN{gamma} neutralisation additively reduced Tr1 cell frequency in vivo. These findings reveal that during strong tolerogenic TCR signalling IFN-{gamma} has a non-redundant regulatory role in augmenting the differentiation of Tr1 cells in vivo.

immunology↗

bioRxiv2024

Lag3 and PD-L1 govern T cell receptor signal duration in adaptively tolerised CD4+ T cells

Lag3 and PD-1 are immune checkpoints that regulate T cell responses and are current immunotherapy targets. Yet how they function to control early CD4+ T cell activation remains unclear. Here, we show that the PD-1 and Lag3 pathways exhibit layered control of the early CD4+ T cell activation process, with the effects of Lag3 more pronounced in the presence of PD-1 pathway co-blockade (CB). RNA-sequencing revealed that CB drove an early NFAT-dependent transcriptional profile, including promotion of ICOShi T follicular helper (Tfh) cell differentiation. NFAT pathway inhibition abolished CB-induced upregulation of NFAT-dependent co-receptors ICOS and OX40, whilst unaffecting the NFAT-independent gene Nr4a1. Mechanistically, Lag3 and PD-1 pathways functioned additively to regulate the duration of T cell receptor (TCR) signals during CD4+ T cell re-activation. Our data therefore reveal that PD-1 and Lag3 pathways converge to additively regulate TCR signal duration and NFAT-dependent transcriptional activity during early CD4+ T cell re-activation. HighlightsO_LIPD-1 and Lag3 pathways exhibit layered control of early CD4+ T cell activation C_LIO_LITheir co-blockade enhances NFAT-dependent TCR transcriptional programmes C_LIO_LIInhibition of NFAT signalling reverses the functional effects of PD-1 and Lag3 co-blockade C_LIO_LIMechanistically, PD-1 and Lag3 function to additively regulate TCR signal duration during re-activation of CD4+ T cells C_LI

immunology↗