David Leonard Williams

Neutrophils are key effectors of innate immunity. Although traditionally regarded as short-lived effector cells, recent evidence suggests they can undergo functional reprogramming after microbial stimulation, leading to trained immunity. We investigated whether lipopolysaccharide (LPS) or Candida albicans β-glucan induces memory-like inflammatory responses in adult peripheral and neonatal cord blood neutrophils. We used complementary molecular and functional approaches to characterize neutrophil responses following in vitro priming with LPS or β-glucan and subsequent LPS restimulation. Cytokine secretion, reactive oxygen species (ROS) production, glycolytic activity (via lactate production and glycolytic enzyme expression), and ERK1/2 and NF-κB signaling pathway activation were assessed. Priming with LPS or β-glucan enhanced neutrophil responsiveness to secondary stimulation, resulting in increased secretion of IL-1β, IL-6, IL-8, CXCL1, and CCL2, together with elevated ROS production. These effects were consistently more pronounced in neonatal than in adult neutrophils. Memory-like neutrophils also exhibited metabolic reprogramming, associated by increased hexokinase-2 and phosphofructokinase-1 mRNA expression, elevated lactate production, and enhanced ERK1/2 and NF-κB activation. Human neutrophils, particularly neonatal cells, develop memory-like characteristics following LPS or β-glucan priming, highlighting their functional and metabolic plasticity and suggesting a role for neutrophil training in early-life immune adaptation.

Mycobacteria have a cell envelope that can act as a shield against host defense. This study shows that mycobacteria survive in host macrophages by targeting the innate host receptor dectin-1 through a noncanonical ligand. Compared with wild-type (WT) mice, dectin-1–deficient mice were more resistant to infection to mycobacteria. Dectin-1–deficient mice presented with substantially reduced bacterial burdens, inflammatory cytokines, and infiltrating myeloid cells, such as neutrophils and macrophages. Intracellular survival of these bacteria was reduced in macrophages derived from dectin-1–deficient mice compared with those from WT mice. Cellular characterization of mycobacteria-infected macrophages indicated that the presence of dectin-1 altered phagosomal maturation and association with markers of autophagy. Activity-based purification and nuclear magnetic resonance spectrometry identified branched α-glucan as the dectin-1 mycobacterial ligand. This branched glucan was essential for activating dectin-1. These results show that mycobacterial α-glucan targets dectin-1 to facilitate intracellular bacterial survival.

Around 12 million people globally are estimated to be blind with age-related cataract and numerous studies have sought to evaluate the causes of this lens opacification, many of these complicated by the difficulty of determining the impacts of varying aetiological factors from daylight through diet, diabetes and many more. While various experimental investigations on laboratory animals have sought to unpick these influences on lens transparency to date none has sought to evaluate age-related cataract across different animal species kept as companion animals. Here we look at a number of studies on companion dogs, cats and horses to determine the effects of daylight, diet, diabetes, dehydration, drugs, genetics (DNA to continue the D alliteration) and trauma (Damage again as a final D).

The eye requires the ability to focus images near and far and throughout evolution numerous mechanisms have developed to allow this accommodation. From primitive organisms which use a small pupil to effect pinhole camera optics without a lens through more complex eyes with a lens that is moved antero-posteriorly along the visual axis or the shape of which is changed, the eye has engineered numerous accommodative mechanisms. Human inventors have developed cameras with remarkable accommodative abilities but none match the remarkable focussing abilities of the four-eyed fish Anableps or the cormorant which similarly manages to focus above and below water, to give just two examples from the animal kingdom, perfectly adapted to their environments and behaviours.

Exposure to pathogen-associated molecular patterns (PAMPs) induces an augmented, broad-spectrum antimicrobial response to subsequent infection, a phenomenon termed innate immune memory. This study examined the effects of treatment with β-glucan, a fungus-derived Dectin-1 ligand, or monophosphoryl lipid A (MPLA), a bacteria-derived TLR4 ligand, on innate immune memory with a focus on identifying common cellular and molecular pathways activated by these diverse PAMPs. Treatment with either PAMP prepared the innate immune system to respond more robustly to Pseudomonas aeruginosa infection in vivo by facilitating mobilization of innate leukocytes into blood, recruitment of leukocytes to the site of infection, augmentation of microbial clearance and attenuation of cytokine production. Examination of macrophages ex vivo showed amplification of metabolism, phagocytosis, and respiratory burst after treatment with either agent, although MPLA more robustly augmented these activities and more effectively facilitated killing of bacteria. Both agents activated gene expression pathways in macrophages that control inflammation, antimicrobial functions and protein synthesis and suppressed pathways regulating cell division. β-glucan treatment minimally altered macrophage differential gene expression in response to LPS challenge whereas MPLA attenuated the magnitude of the LPS-induced transcriptional response, especially cytokine gene expression. These results show that β-glucan and MPLA similarly augment the innate response to infection in vivo. Yet, MPLA more potently induces alterations in macrophage metabolism, antimicrobial functions, gene transcription and the response to LPS.

The importance of the visual system to birds for behaviours from feeding, mate choice, flying, navigation and determination of seasons, together with the presence of photoreceptors in the retina, the pineal and the brain, render the avian visual system a particularly fruitful model for understanding of eye-brain interactions. In this review we will particularly focus on the pigeon, since here we have a brain stereotactically mapped and a genome fully sequenced, together with a particular bird, the homing pigeon, with remarkable ability to navigate over hundreds of miles and return to exactly the same roosting site with exceptional precision. We might denigrate the avian species by the term bird brained, but here are animals with phenomenal abilities to use their exceptional vision, their eagle eyedness, to best advantage.

Glycogen is a highly branched polymer of glucose and is used across the tree of life as an efficient and compact form of energy storage. Whereas glycogen metabolism pathways have been studied in model yeasts, they have not been extensively explored in pathogenic fungi.

High levels of lactate are positively associated with the prognosis and mortality in patients with heart attack. Endothelial-to-mesenchymal transition (EndoMT) plays an important role in cardiac fibrosis. Here, we report that lactate exerts a previously unknown function that increases cardiac fibrosis and exacerbates cardiac dysfunction by promoting EndoMT following myocardial infarction (MI). Treatment of endothelial cells with lactate disrupts endothelial cell function and induces mesenchymal-like function following hypoxia by activating the TGF-β/Smad2 pathway. Mechanistically, lactate induces an association between CBP/p300 and Snail1, leading to lactylation of Snail1, a TGF-β transcription factor, through lactate transporter monocarboxylate transporter (MCT)–dependent signaling. Inhibiting Snail1 diminishes lactate-induced EndoMT and TGF-β/Smad2 activation after hypoxia/MI. The MCT inhibitor CHC mitigates lactate-induced EndoMT and Snail1 lactylation. Silence of MCT1 compromises lactate-promoted cardiac dysfunction and EndoMT after MI. We conclude that lactate acts as an important molecule that up-regulates cardiac EndoMT after MI via induction of Snail1 lactylation.

We determined whether gut microbiota-produced trimethylamine (TMA) is oxidized into trimethylamine N-oxide (TMAO) in nonliver tissues and whether TMAO promotes inflammation via trained immunity (TI). We found that endoplasmic reticulum (ER) stress genes were coupregulated with MitoCarta genes in chronic kidney diseases (CKD); TMAO upregulated 190 genes in human aortic endothelial cells (HAECs); TMAO synthesis enzyme flavin-containing monooxygenase 3 (FMO3) was expressed in human and mouse aortas; TMAO transdifferentiated HAECs into innate immune cells; TMAO phosphorylated 12 kinases in cytosol via its receptor PERK and CREB, and integrated with PERK pathways; and PERK inhibitors suppressed TMAO-induced ICAM-1. TMAO upregulated 3 mitochondrial genes, downregulated inflammation inhibitor DARS2, and induced mitoROS, and mitoTEMPO inhibited TMAO-induced ICAM-1. β-Glucan priming, followed by TMAO restimulation, upregulated TNF-α by inducing metabolic reprogramming, and glycolysis inhibitor suppressed TMAO-induced ICAM-1. Our results have provided potentially novel insights regarding TMAO roles in inducing EC activation and innate immune transdifferentiation and inducing metabolic reprogramming and TI for enhanced vascular inflammation, and they have provided new therapeutic targets for treating cardiovascular diseases (CVD), CKD-promoted CVD, inflammation, transplantation, aging, and cancer.

Introduction: Sepsis impaired vascular integrity results in multiple organ failure. Circulating lactate level is positively correlated with sepsis-induced mortality. We investigated whether lactate plays a role in causing endothelial barrier dysfunction in sepsis. Methods: Polymicrobial sepsis was induced in mice by cecal ligation and puncture (CLP). Lactic acid was injected i.p. (pH 6.8, 0.5 g/kg body weight) 6 h after CLP or sham surgery. To elucidate the role of heat shock protein A12B (HSPA12B), wild-type, HSPA12B-transgenic, and endothelial HSPA12B-deficient mice were subjected to CLP or sham surgery. To suppress lactate signaling, 3OBA (120 μM) was injected i.p. 3 h before surgery. Vascular permeability was evaluated with the Evans blue dye penetration assay. Results: We found that administration of lactate elevated CLP-induced vascular permeability. Vascular endothelial cadherin (VE-cadherin), claudin 5, and zonula occluden 1 (ZO-1) play a crucial role in the maintenance of endothelial cell junction and vascular integrity. Lactate administration significantly decreased VE-cadherin, claudin 5, and ZO-1 expression in the heart of septic mice. Our in vitro data showed that lactate (10 mM) treatment disrupted VE-cadherin, claudin 5, and ZO-1 in endothelial cells. Mechanistically, we observed that lactate promoted VE-cadherin endocytosis by reducing the expression of HSPA12B. Overexpression of HSPA12B prevented lactate-induced VE-cadherin disorganization. G protein–coupled receptor 81 (GPR81) is a specific receptor for lactate. Inhibition of GPR81 with its antagonist 3OBA attenuated vascular permeability and reversed HSPA12B expression in septic mice. Conclusions: The present study demonstrated a novel role of lactate in promoting vascular permeability by decreasing VE-cadherin junctions and tight junctions in endothelial cells. The deleterious effects of lactate in vascular hyperpermeability are mediated via HSPA12B- and GPR81-dependent signaling.