Biology subjects

Willment, J. A.

Publications and source records attributed to Willment, J. A..

4 recordsLinked to original sources

bioRxiv2025

Clec7a-mediated regulation of Killer-like Lectin Receptor expression controls T cell immunity

Clec7a is a C-type lectin receptor (CLR) originally defined for its non-redundant role in anti-fungal immunity. Subsequent work has broadened this view, implicating Clec7a in host defense against diverse pathogens and in the pathogenesis of cancer, autoimmunity, neuroinflammation, and developmental disorders. How a single innate receptor orchestrates such wide-ranging outcomes remains unresolved. We previously demonstrated that dendritic cell (DC)-expressed Clec7a is required for protective anti-fungal immunity in the gastrointestinal tract through regulation of fungus-specific CD4 T cell responses. Here, we show that Clec7a controls the expression of multiple C-type lectins in DCs, including a cluster of killer lectin-like receptors (KLRs). Notably, we reveal that these KLRs directly regulate DC function and control CD4 T cell responses. These findings define a novel Clec7a-KLR axis that integrates innate and adaptive immunity, highlighting a regulatory pathway with broad relevance for immune homeostasis, inflammation, and host defense.

immunology↗

bioRxiv2025

Antagonism between bacteriophages and macrophages decreases efficacy of a phage cocktail and increases bacteriophage resistance

Phage therapy, the use of viruses that infect bacteria (bacteriophages), is a promising complement to antibiotics during the antimicrobial resistance crisis, but treatment success is very variable. Evolution of bacterial resistance to bacteriophages and bacteriophage counter-resistance (coevolution) during therapy may explain some of this variation, the dynamics of which may be affected by interactions with the patients immune system. Here, we examine how a pathogenic bacterium, Pseudomonas aeruginosa coevolves with two clinically relevant bacteriophages (14-1 and PNM) when in the presence of macrophages (RAW 264.7 cell line). We show macrophages reduced the rate by which bacteria were killed by bacteriophages, likely by reducing bacteria-bacteriophage contact rates. Over evolutionary time-scales, macrophages increased the proportion of bacteriophage resistant bacteria compared to where macrophages were absent. These differences in resistance rates were likely driven by the early advantage in density offered by macrophages to bacteria, and exclusion of PNM from the bacteriophage cocktail which otherwise increased in frequency in the absence of macrophages. Consequently, macrophages significantly altered the short- and long-term efficacy of a bacteriophage cocktail. In line with a growing body of work, our results suggest that the patients immune system can reduce the efficacy of phage therapy, potentially driving variable outcomes in therapy success in patients. Significance statementPhage therapy, the use of viruses that infect bacteria (bacteriophages), is a promising complement to antibiotics during the antimicrobial resistance crisis. However, treatment success is very variable. One, often overlooked, variable is the immune system and how this influences bacteriophage efficacy, and how bacteria evolve resistance to bacteriophages. We find that macrophages reduce the rate by which bacteria are killed by bacteriophages. Resistance to bacteriophages also increased in the presence of macrophages, showing macrophages affect the short- and long-term efficacy of phage therapy. These results highlight the importance of the immune system in phage therapy, and the need for more research in this area.

evolutionary biology↗

bioRxiv2022

Human Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2

C-type lectin receptors (CLRs) elicit immune responses upon recognition of glycoconjugates present on pathogens and self-components. While Dectin-1 is the best-characterized CLR recognizing {beta}-glucan on pathogens, the endogenous targets of Dectin-1 are not fully understood. Herein, we report that human Dectin-1 is a ligand for CLEC-2, another CLR expressed on platelets. Biochemical analyses revealed that Dectin-1 is a mucin-like protein as its stalk region is highly O-glycosylated. A sialylated core 1 glycan attached to the EDxxT motif of human Dectin-1, which is absent in mouse Dectin-1, provides a ligand moiety for CLEC-2. Strikingly, the expression of human Dectin-1 in mice rescued the lethality and lymphatic defect resulting from a deficiency of Podoplanin, a known CLEC-2 ligand. This finding is the first example of an innate immune receptor also functioning as a physiological ligand to regulate ontogeny upon glycosylation.

immunology↗

bioRxiv2019

Mannan detecting C-type lectin receptor probes recognise immune epitopes with diverse chemical, spatial and phylogenetic heterogeneity in fungal cell walls

During the course of fungal infection, pathogen recognition by the innate immune system is critical to initiate efficient protective immune responses. The primary event that triggers immune responses is the binding of Pattern Recognition Receptors (PRRs), which are expressed at the surface of host immune cells, to Pathogen-Associated Molecular Patterns (PAMPs) located predominantly in the fungal cell wall. Most fungi have mannosylated PAMPs in their cell walls and these are recognized by a range of C-type lectin receptors (CTLs). However, the precise spatial distribution of the ligands that induce immune responses within the cell walls of fungi are not well defined. We used recombinant IgG Fc-CTLs fusions of three murine mannan detecting CTLs, including dectin-2, the mannose receptor (MR) carbohydrate recognition domains (CRDs) 4-7 (CRD4-7), and human DC-SIGN (hDC-SIGN) and the {beta}-1,3 glucan-binding lectin dectin-1 to map PRR ligands in the fungal cell wall. We show that epitopes of mannan-specific CTL receptors can be clustered or diffuse, superficial or buried in the inner cell wall. We demonstrate that PRR ligands do not correlate well with phylogenetic relationships between fungi, and that Fc-lectin binding discriminated between mannosides expressed on different cell morphologies of the same fungus. We also demonstrate CTL epitope differentiation during different phases of the growth cycle of Candida albicans and that MR and DC-SIGN labelled outer chain N-mannans whilst dectin-2 labelled core N-mannans displayed deeper in the cell wall. These immune receptor maps of fungal walls therefore reveal remarkable spatial, temporal and chemical diversity, indicating that the triggering of immune recognition events originates from multiple physical origins at the fungal cell surface.\n\nAuthor SummaryInvasive fungal infections remain an important health problem in immunocompromised patients. Immune recognition of fungal pathogens involves binding of specific cell wall components by pathogen recognition receptors (PRRs) and subsequent activation of immune defences. Some cell wall components are conserved among fungal species while other components are species-specific and phenotypically diverse. The fungal cell wall is dynamic and capable of changing its composition and organization when adapting to different growth niches and environmental stresses. Differences in the composition of the cell wall lead to differential immune recognition by the host. Understanding how changes in the cell wall composition affect recognition by PRRs is likely to be of major diagnostic and clinical relevance. Here we address this fundamental question using four soluble immune receptor-probes which recognize mannans and {beta}-glucan in the cell wall. We use this novel methodology to demonstrate that mannan epitopes are differentially distributed in the inner and outer layers of fungal cell wall in a clustered or diffuse manner. Immune reactivity of fungal cell surfaces did not correlate with relatedness of different fungal species, and mannan-detecting receptor-probes discriminated between cell surface mannans generated by the same fungus growing under different conditions. These studies demonstrate that mannan-epitopes on fungal cell surfaces are differentially distributed within and between the cell walls of fungal pathogens.

microbiology↗