Biology subjects

Magalhaes, M. S.

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

4 recordsLinked to original sources

bioRxiv2023

Bcl2 supports survival and metabolic fitness of quiescent tissue-resident ILC3

Group 3 innate lymphoid cells (ILC3) are potent effector cells with critical roles in enforcing immunity, barrier integrity and tissue homeostasis along the gastrointestinal tract. ILC3 are considered to be primarily tissue-resident cells, seeding the gastrointestinal tract during embryonic stages. However, the mechanisms through which ILC3 are maintained within these tissues are poorly understood. Here, we report that ILC3 are minimally replenished from bone marrow precursors in healthy adult mice, persist in the tissue for extended periods of time in the gut, and display a quiescent phenotype. Strikingly, despite robustly producing cytokines, LTi-like ILC3 remain non-proliferative during enteric bacterial infection. Survival of LTi-like ILC3 was found to be dependent upon the balance of the metabolic activity required to drive effector function and anti-apoptotic programs. Notably, the pro-survival protein Bcl-2 was required for the survival of LTi-like ILC3 but was rendered partially dispensable if mitochondrial respiration was inhibited. Together we demonstrate LTi-like ILC3 are a quiescent-like population that persists independently of haematopoietic replenishment to survive within the tissue microenvironment.

immunology↗

bioRxiv2022

CSF1R-dependent macrophages in the salivary gland are essential for epithelial regeneration following radiation-induced injury

The salivary glands often become damaged in individuals receiving radiotherapy for head and neck cancer, resulting in xerostomia, or chronic dry mouth. This leads to detrimental effects on their health and quality of life, for which there is no regenerative therapy. Macrophages are the predominant cell type in the salivary glands and are attractive therapeutic targets due to their unrivalled capacity to drive tissue repair and regeneration. Yet, the nature and role of macrophages in salivary gland homeostasis and whether or not they contribute to tissue repair/regeneration following injury is not well understood. Here, we have used single cell RNA-seq, multi-parameter flow cytometry and fluorescence microscopy to map the heterogeneity of the salivary gland macrophage compartment throughout development and following radiation-induced injury. We show that there are highly dynamic changes in the composition of the salivary gland macrophage compartment with age, in part due to changes in the ontogeny of these cells, determined using a suite of complementary fate mapping systems. A combination of mutant mice and antibody blockade demonstrates that salivary gland macrophages are dependent on CSF1, but not IL-34 or GM-CSF, for their development and maintenance. Finally, using an in vivo model of radiation-induced salivary gland injury combined with a novel Mafb-specific depletion system, we demonstrate an essential role for macrophages. Without macrophages the clearance of cells with DNA damage, and effective tissue repair following such injury, is severely comprised. Our data, therefore, indicate a strong case for exploring the therapeutic potential of manipulating macrophages in order to promote tissue repair and thus minimise salivary gland dysfunction after radiotherapy.

immunology↗

bioRxiv2019

The pericardium promotes cardiac repair and remodelling post-myocardial infarction

The pericardium is widely recognised for its lubricating and bio-mechanical properties. It also contains fat-associated lymphoid clusters (FALCs) and its immune functions have been widely overlooked. Here we aimed to assess the inflammatory activity of the pericardium in patients who suffered a recent myocardial infarction (MI) and to determine its importance for repair and remodelling in a murine MI model induced by coronary artery ligation (CAL). By comparing 18F-fluorodeoxyglucose (FDG) activity in the pericardium of patients with stable coronary artery disease and patients who had a recent MI, we demonstrate that MI is associated with increased pericardial inflammation. We confirm in mice, that pericardial FALCs undergo a major expansion following CAL. We show that despite similar initial injury, removal of the pericardium prior to MI disrupted subsequent repair, resulting in 50% mortality due to cardiac rupture, while all mice with intact pericardia survived. Removal of the pericardium also led to decreased staining for Ym1, a marker of reparative macrophages and adverse cardiac fibrosis within the infarct area. Together, this work indicates a crucial role for the pericardium in regulating inflammation, macrophage polarisation and tissue remodelling in the heart following MI.

physiology↗

bioRxiv2019

Neutrophils mediate the capture of peritoneal contaminants by fat-associated lymphoid clusters of the omentum

The omentum is a visceral adipose tissue rich in fat-associated lymphoid clusters (FALCs), which collects peritoneal contaminants and provides a first layer of immunological defence within the abdomen. Using single-cell RNA sequencing and spatial analysis of omental stromal cells, we reveal that the surface of FALCs are covered with specialised mesothelial cells, which we name FALC cover cells. We demonstrate that CXCL1 is expressed by FALC cover cells and that CXCL1 is critical for the retention and accumulation of neutrophils within FALCs during peritonitis. We show that protein arginine deiminase 4 mediates the formation of dense neutrophil aggregates, which are required for the neutralisation of particles present in the peritoneal cavity. Finally, we provide confirmatory evidence in humans with acute appendicitis, that the omentum is also a site of neutrophil recruitment and bacterial capture, and is thus an important component of the immunological defence against the propagation of peritoneal contaminants.

immunology↗