Epithelial Memory After Respiratory Viral Infection in Mice Results in Prolonged Enhancement of Antigen Presentation.

Background: Viral lower respiratory tract infections (LRTIs) can reduce the severity of subsequent LRTIs but have also been linked to respiratory allergy development and exacerbation. Here, we show that viral LRTI can imprint lung epithelial cells (LECs), leading to prolonged phenotypic and functional changes.

Methods: Mice were infected via intranasal administration of respiratory syncytial virus (RSV).

The long reach of influenza and other respiratory viruses: from acute epithelial injury to post-viral lung disease.

SUMMARYRespiratory viral infections cause extensive cell death in the lung epithelium, resulting from both direct viral action and exuberant immune responses. Recovery following viral infection requires rapid and coordinated repair programs, ensuring the replacement of the damaged tissue through proliferation, migration, and differentiation of respiratory epithelial progenitor cells. Viral infection and the resulting inflammatory milieu alter host gene expression.

Temporal dichotomy of neutrophil function in acute liver injury and repair.

Background & Aims: Acetaminophen (APAP)-induced acute liver injury (APAP-ALI) is the leading cause of acute liver failure-induced death, with host innate immune responses driving outcomes. Neutrophils are activated and increased in APAP-ALI and reported to contribute to liver damage. However, neutrophil dysfunction in patients with acute liver failure is associated with non-survival, and recent reports highlight their importance in hepatic repair.

Early life high fructose impairs microglial phagocytosis and neurodevelopment.

Despite the success of fructose as a low-cost food additive, epidemiological evidence suggests that high fructose consumption during pregnancy or adolescence is associated with disrupted neurodevelopment. An essential step in appropriate mammalian neurodevelopment is the phagocytic elimination of newly formed neurons by microglia, the resident professional phagocyte of the central nervous system. Whether high fructose consumption in early life affects microglial phagocytosis and whether this directly affects neurodevelopment remains unknown.

WNK1 mediates M-CSF-induced macropinocytosis to enforce macrophage lineage fidelity.

Tissue-resident macrophages (TRM) are critical for mammalian organismal development and homeostasis. Here we report that with-no-lysine 1 (WNK1) controls myeloid progenitor fate, with Csf1r-mediated Wnk1 deletion in mice (WNK1-deficient mice) resulting in loss of TRMs and causing perinatal mortality. Mechanistically, absence of WNK1 or inhibition of WNK kinase activity disrupts macrophage colony-stimulating factor (M-CSF)-stimulated macropinocytosis, thereby blocking mouse and human progenitor and monocyte differentiation into macrophages and skewing progenitor differentiation into neutrophils.

Age-related impairment of intestinal inflammation resolution through an eicosanoid-immune-microbiota axis.

Aging manifests a decline of immune function, induces microbiome dysbiosis, drives organ inflammation, and impedes the resolution of inflammation. However, the mechanisms underlying age-related intestinal inflammation remain poorly described. Here, we find that the resolution of T cell-initiated intestinal inflammation is impaired with aging.

Drosophila complement-like Mcr acts as a wound-induced inflammatory chemoattractant.

Sterile tissue injury is accompanied by an acute inflammatory response whereby innate immune cells rapidly migrate to the site of injury guided by pro-inflammatory chemotactic damage signals released at the wound. Understanding this immune response is key to improving human health, and recent advances in imaging technology have allowed researchers using different model organisms to observe this inflammatory response in vivo. Over recent decades, offering a unique combination of live time-lapse microscopy and genetics, the fruit fly Drosophila has emerged as a powerful model system to study inflammatory cell migration within a living animal.

Broad-spectrum antibiotics disrupt homeostatic efferocytosis.

The clearance of apoptotic cells, termed efferocytosis, is essential for tissue homeostasis and prevention of autoimmunity. Although past studies have elucidated local molecular signals that regulate homeostatic efferocytosis in a tissue, whether signals arising distally also regulate homeostatic efferocytosis remains elusive. Here, we show that large peritoneal macrophage (LPM) display impairs efferocytosis in broad-spectrum antibiotics (ABX)-treated, vancomycin-treated and germ-free mice in vivo, all of which have a depleted gut microbiota.

Early life high fructose exposure disrupts microglia function and impedes neurodevelopment.

Despite the success of fructose as a low-cost food additive, recent epidemiological evidence suggests that high fructose consumption by pregnant mothers or during adolescence is associated with disrupted neurodevelopment . An essential step in appropriate mammalian neurodevelopment is the synaptic pruning and elimination of newly-formed neurons by microglia, the central nervous system's (CNS) resident professional phagocyte . Whether early life high fructose consumption affects microglia function and if this directly impacts neurodevelopment remains unknown.

WNK1 enforces macrophage lineage fidelity.

Unlabelled: The appropriate development of macrophages, the body's professional phagocyte, is essential for organismal development, especially in mammals. This dependence is exemplified by the observation that loss-of-function mutations in colony stimulating factor 1 receptor (CSF1R) results in multiple tissue abnormalities owing to an absence of macrophages. Despite this importance, little is known about the molecular and cell biological regulation of macrophage development.

Metabolic adaptation supports enhanced macrophage efferocytosis in limited-oxygen environments.

Apoptotic cell (AC) clearance (efferocytosis) is performed by phagocytes, such as macrophages, that inhabit harsh physiological environments. Here, we find that macrophages display enhanced efferocytosis under prolonged (chronic) physiological hypoxia, characterized by increased internalization and accelerated degradation of ACs. Transcriptional and translational analyses revealed that chronic physiological hypoxia induces two distinct but complimentary states.

Inhibition of Cyclin-Dependent Kinase 9 Downregulates Cytokine Production Without Detrimentally Affecting Human Monocyte-Derived Macrophage Viability.

Cyclin-dependent kinase (CDK) inhibitor drugs (CDKi), such as R-roscovitine and AT7519, induce neutrophil apoptosis and enhance the resolution of inflammation in a number of models. This class of compounds are potential novel therapeutic agents that could promote the resolution of acute and chronic inflammatory conditions where neutrophil activation contributes to tissue damage and aberrant tissue repair. In this study we investigated CDKi effects on macrophage pro-inflammatory mediator production and viability.

Macrophages trigger cardiomyocyte proliferation by increasing epicardial vegfaa expression during larval zebrafish heart regeneration.

Cardiac injury leads to the loss of cardiomyocytes, which are rapidly replaced by the proliferation of the surviving cells in zebrafish, but not in mammals. In both the regenerative zebrafish and non-regenerative mammals, cardiac injury induces a sustained macrophage response. Macrophages are required for cardiomyocyte proliferation during zebrafish cardiac regeneration, but the mechanisms whereby macrophages facilitate this crucial process are fundamentally unknown.

Pannexin 1 drives efficient epithelial repair after tissue injury.

Epithelial tissues such as lung and skin are exposed to the environment and therefore particularly vulnerable to damage during injury or infection. Rapid repair is therefore essential to restore function and organ homeostasis. Dysregulated epithelial tissue repair occurs in several human disease states, yet how individual cell types communicate and interact to coordinate tissue regeneration is incompletely understood.

Pulmonary macrophages and SARS-Cov2 infection.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the largest global pandemic in living memory, with between 4.5 and 15M deaths globally from coronavirus disease 2019 (COVID-19). This has led to an unparalleled global, collaborative effort to understand the pathogenesis of this devastating disease using state-of-the-art technologies.

Live cell tracking of macrophage efferocytosis during embryo development in vivo.

Apoptosis of cells and their subsequent removal through efferocytosis occurs in nearly all tissues during development, homeostasis, and disease. However, it has been difficult to track cell death and subsequent corpse removal in vivo. We developed a genetically encoded fluorescent reporter, CharON (Caspase and pH Activated Reporter, Fluorescence ON), that could track emerging apoptotic cells and their efferocytic clearance by phagocytes.

Tissue Proteomic Analysis Identifies Mechanisms and Stages of Immunopathology in Fatal COVID-19.

Immunopathology occurs in the lung and spleen in fatal coronavirus disease (COVID-19), involving monocytes/macrophages and plasma cells. Antiinflammatory therapy reduces mortality, but additional therapeutic targets are required. We aimed to gain mechanistic insight into COVID-19 immunopathology by targeted proteomic analysis of pulmonary and splenic tissues.

Pannexin 1 channels facilitate communication between T cells to restrict the severity of airway inflammation.

Allergic airway inflammation is driven by type-2 CD4 T cell inflammatory responses. We uncover an immunoregulatory role for the nucleotide release channel, Panx1, in T cell crosstalk during airway disease. Inverse correlations between Panx1 and asthmatics and our mouse models revealed the necessity, specificity, and sufficiency of Panx1 in T cells to restrict inflammation.

Epithelial Cells and Inflammation in Pulmonary Wound Repair.

Respiratory diseases are frequently characterised by epithelial injury, airway inflammation, defective tissue repair, and airway remodelling. This may occur in a subacute or chronic context, such as asthma and chronic obstructive pulmonary disease, or occur acutely as in pathogen challenge and acute respiratory distress syndrome (ARDS). Despite the frequent challenge of lung homeostasis, not all pulmonary insults lead to disease.