Establishing an analogue population for the most distant galaxies

Lyman break analogues (LBAs) are local galaxies selected to match a more distant (usually z~3) galaxy population in luminosity, UV-spectral slope and physical characteristics, and so provide an accessible laboratory for exploring their properties. However, as the Lyman break technique is extended to higher redshifts, it has become clear that the Lyman break galaxies (LBGs) at z~3 are more massive, luminous, redder, more extended and at higher metallicities than their z~5 counterparts. Thus extrapolations from the existing LBA samples (which match z=3 properties) have limited value for characterising z>5 galaxies, or inferring properties unobservable at high redshift. We present a new pilot sample of twenty-one compact star forming galaxies in the local (0.05<z<0.25) Universe, which are tuned to match the luminosities and star formation volume densities observed in z>~5 LBGs. Analysis of optical emission line indices suggests that these sources have typical metallicities of a few tenths Solar (again, consistent with the distant population). We also present radio continuum observations of a subset of this sample (13 sources) and determine that their radio fluxes are consistent with those inferred from the ultraviolet, precluding the presence of a heavily obscured AGN or significant dusty star formation.Comment: 13 pages, MNRAS accepte

Peritoneal tissue-resident macrophages are metabolically poised to engage microbes using tissue-niche fuels

The importance of metabolism in macrophage function has been reported, but the in vivo relevance of the in vitro observations is still unclear. Here we show that macrophage metabolites are defined in a specific tissue context, and these metabolites are crucially linked to tissue-resident macrophage functions. We find the peritoneum to be rich in glutamate, a glutaminolysis-fuel that is exploited by peritoneal-resident macrophages to maintain respiratory burst during phagocytosis via enhancing mitochondrial complex-II metabolism. This niche-supported, inducible mitochondrial function is dependent on protein kinase C activity, and is required to fine-tune the cytokine responses that control inflammation. In addition, we find that peritoneal-resident macrophage mitochondria are recruited to phagosomes and produce mitochondrially derived reactive oxygen species, which are necessary for microbial killing. We propose that tissue-resident macrophages are metabolically poised in situ to protect and exploit their tissue-niche by utilising locally available fuels to implement specific metabolic programmes upon microbial sensing

Effective In Vivo Gene Modification in Mouse Tissue-Resident Peritoneal Macrophages by Intraperitoneal Delivery of Lentiviral Vectors

Tissue-resident macrophages exhibit specialized phenotypes dependent on their in vivo physiological niche. Investigation of their function often relies upon complex whole mouse transgenic studies. While some appropriate lineage-associated promoters exist, there are no options for tissue-specific targeting of macrophages. We have developed full protocols for in vivo productive infection (defined by stable transgene expression) of tissue-resident macrophages with lentiviral vectors, enabling RNA and protein overexpression, including expression of small RNA species such as shRNA, to knock down and modulate gene expression. These approaches allow robust infection of peritoneal tissue-resident macrophages without significant infection of other cell populations. They permit rapid functional study of macrophages in homeostatic and inflammatory settings, such as thioglycolate-induced peritonitis, while maintaining the cells in their physiological context. Here we provide detailed protocols for the whole workflow: viral production, purification, and quality control; safety considerations for administration of the virus to mice; and assessment of in vivo transduction efficiency and the low background levels of inflammation induced by the virus. In summary, we present a quick and accessible protocol for the rapid assessment of gene function in peritoneal tissue-resident macrophages in vivo

nSeP: immune and metabolic biomarkers for early detection of neonatal sepsis—protocol for a prospective multicohort study

Introduction Diagnosing neonatal sepsis is heavily dependent on clinical phenotyping as culture-positive body fluid has poor sensitivity, and existing blood biomarkers have poor specificity.A combination of machine learning, statistical and deep pathway biology analyses led to the identification of a tripartite panel of biologically connected immune and metabolic markers that showed greater than 99% accuracy for detecting bacterial infection with 100% sensitivity. The cohort study described here is designed as a large-scale clinical validation of this previous work.Methods and analysis This multicentre observational study will prospectively recruit a total of 1445 newborn infants (all gestations)—1084 with suspected early—or late-onset sepsis, and 361 controls—over 4 years. A small volume of whole blood will be collected from infants with suspected sepsis at the time of presentation. This sample will be used for integrated transcriptomic, lipidomic and targeted proteomics profiling. In addition, a subset of samples will be subjected to cellular phenotype and proteomic analyses. A second sample from the same patient will be collected at 24 hours, with an opportunistic sampling for stool culture. For control infants, only one set of blood and stool sample will be collected to coincide with clinical blood sampling. Along with detailed clinical information, blood and stool samples will be analysed and the information will be used to identify and validate the efficacy of immune-metabolic networks in the diagnosis of bacterial neonatal sepsis and to identify new host biomarkers for viral sepsis.Ethics and dissemination The study has received research ethics committee approval from the Wales Research Ethics Committee 2 (reference 19/WA/0008) and operational approval from Health and Care Research Wales. Submission of study results for publication will involve making available all anonymised primary and processed data on public repository sites.Trial registration number NCT0377767

Autocrine IL-10 functions as a rheostat for M1 macrophage glycolytic commitment by tuning nitric oxide production

Inflammatory maturation of M1 macrophages by proinflammatory stimuli such as toll like receptor ligands results in profound metabolic reprogramming resulting in commitment to aerobic glycolysis as evidenced by repression of mitochondrial oxidative phosphorylation (OXPHOS) and enhanced glucose utilization. In contrast, “alternatively activated” macrophages adopt a metabolic program dominated by fatty acid-fueled OXPHOS. Despite the known importance of these developmental stages on the qualitative aspects of an inflammatory response, relatively little is know regarding the regulation of these metabolic adjustments. Here we provide evidence that the immunosuppressive cytokine IL-10 defines a metabolic regulatory loop. Our data show for the first time that lipopolysaccharide (LPS)-induced glycolytic flux controls IL-10-production via regulation of mammalian target of rapamycin (mTOR) and that autocrine IL-10 in turn regulates macrophage nitric oxide (NO) production. Genetic and pharmacological manipulation of IL-10 and nitric oxide (NO) establish that metabolically regulated autocrine IL-10 controls glycolytic commitment by limiting NO-mediated suppression of OXPHOS. Together these data support a model where autocine IL-10 production is controlled by glycolytic flux in turn regulating glycolytic commitment by preserving OXPHOS via suppression of NO. We propose that this IL-10-driven metabolic rheostat maintains metabolic equilibrium during M1 macrophage differentiation and that perturbation of this regulatory loop, either directly by exogenous cellular sources of IL-10 or indirectly via limitations in glucose availability, skews the cellular metabolic program altering the balance between inflammatory and immunosuppressive phenotypes

mSep: investigating physiological and immune-metabolic biomarkers in septic and healthy pregnant women to predict feto-maternal immune health – a prospective observational cohort study protocol

Introduction Maternal sepsis remains a leading cause of death in pregnancy. Physiological adaptations to pregnancy obscure early signs of sepsis and can result in delays in recognition and treatment. Identifying biomarkers that can reliably diagnose sepsis will reduce morbidity and mortality and antibiotic overuse. We have previously identified an immune-metabolic biomarker network comprising three pathways with a >99% accuracy for detecting bacterial neonatal sepsis. In this prospective study, we will describe physiological parameters and novel biomarkers in two cohorts—healthy pregnant women and pregnant women with suspected sepsis—with the aim of mapping pathophysiological drivers and evaluating predictive biomarkers for diagnosing maternal sepsis.Methods and analysis Women aged over 18 with an ultrasound-confirmed pregnancy will be recruited to a pilot and two main study cohorts. The pilot will involve blood sample collection from 30 pregnant women undergoing an elective caesarean section. Cohort A will follow 100 healthy pregnant women throughout their pregnancy journey, with collection of blood samples from participants at routine time points in their pregnancy: week 12 ‘booking’, week 28 and during labour. Cohort B will follow 100 pregnant women who present with suspected sepsis in pregnancy or labour and will have at least two blood samples taken during their care pathway. Study blood samples will be collected during routine clinical blood sampling. Detailed medical history and physiological parameters at the time of blood sampling will be recorded, along with the results of routine biochemical tests, including C reactive protein, lactate and white blood cell count. In addition, study blood samples will be processed and analysed for transcriptomic, lipidomic and metabolomic analyses and both qualitative and functional immunophenotyping.Ethics and dissemination Ethical approval has been obtained from the Wales Research Ethics Committee 2 (SPON1752-19, 30 October 2019).Trial registration number NCT05023954

Prostaglandin E2 promotes intestinal inflammation via inhibiting microbiota-dependent regulatory T cells

The gut microbiota fundamentally regulates intestinal homeostasis and disease partially through mechanisms that involve modulation of regulatory T cells (Tregs), yet how the microbiota-Treg cross-talk is physiologically controlled is incompletely defined. Here, we report that prostaglandin E2 (PGE2), a well-known mediator of inflammation, inhibits mucosal Tregs in a manner depending on the gut microbiota. PGE2 through its receptor EP4 diminishes Treg-favorable commensal microbiota. Transfer of the gut microbiota that was modified by PGE2-EP4 signaling modulates mucosal Treg responses and exacerbates intestinal inflammation. Mechanistically, PGE2-modified microbiota regulates intestinal mononuclear phagocytes and type I interferon signaling. Depletion of mononuclear phagocytes or deficiency of type I interferon receptor diminishes PGE2-dependent Treg inhibition. Together, our findings provide emergent evidence that PGE2-mediated disruption of microbiota-Treg communication fosters intestinal inflammation

The protective effect of inflammatory monocytes during systemic C. albicans infection is dependent on collaboration between C-type lectin-like receptors

Invasive candidiasis, mainly caused by Candida albicans, is a serious healthcare problem with high mortality rates, particularly in immunocompromised patients. Innate immune cells express pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs) that bind C. albicans to initiate an immune response. Multiple CLRs including Dectin-1, Dectin-2 and Mincle have been proposed individually to contribute to the immune response to C. albicans. However how these receptors collaborate to clear a fungal infection is unknown. Herein, we used novel multi-CLR knockout (KO) mice to decipher the individual, collaborative and collective roles of Dectin-1, Dectin-2 and Mincle during systemic C. albicans infection. These studies revealed an unappreciated and profound role for CLR co-operation in anti-fungal immunity. The protective effect of multiple CLRs was markedly greater than any single receptor, and was mediated through inflammatory monocytes via recognition and phagocytosis of C. albicans, and production of C. albicans-induced cytokines and chemokines. These CLRs were dispensable for mediating similar responses from neutrophils, likely due to lower expression of these CLRs on neutrophils compared to inflammatory monocytes. Concurrent deletion of Dectin-1 and Dectin-2, or all three CLRs, resulted in dramatically increased susceptibility to systemic C. albicans infection compared to mice lacking a single CLR. Multi-CLR KO mice were unable to control fungal growth due to an inadequate early inflammatory monocyte-mediated response. In response to excessive fungal growth, the multi-CLR KO mice mounted a hyper-inflammatory response, likely leading to multiple organ failure. Thus, these data reveal a critical role for CLR co-operation in the effective control of C. albicans and maintenance of organ function during infection

IL‐10 differentially controls the infiltration of inflammatory macrophages and antigen‐presenting cells during inflammation

The inflammatory activation and recruitment of defined myeloid populations is essential for controlling the bridge between innate and adaptive immunity and shaping the immune response to microbial challenge. However, these cells exhibit significant functional heterogeneity and the inflammatory signals that differentially influence their effector characteristics are poorly characterized. In this study, we defined the phenotype of discrete subsets of effective antigen-presenting cells (APCs) in the peritoneal cavity during peritonitis. When the functional properties of these cells were compared to inflammatory monocyte-derived macrophages we noted differential responses to the immune-modulatory cytokine IL-10. In contrast to the suppressive actions of IL-10 on inflammatory macrophages, the recruitment of APCs was relatively refractory and we found no evidence for selective inhibition of APC differentiation. This differential response of myeloid cell subsets to IL-10 may thus have limited impact on development of potentially tissue-damaging adaptive immune responses, while restricting the magnitude of the inflammatory response. These findings may have clinical relevance in the context of peritoneal dialysis patients, where recurrent infections are associated with immune-mediated membrane dysfunction, treatment failure, and increased morbidity

Whence honeste vive?

Kant's characterisation of honeste vive as an unenforceable duty of right owed to oneself poses two systematic problems: it conflicts with Kant's claims that (a) duties of right concern the external relation between distinct individuals and (b) duties of right are externally enforceable. Both of these claims speak against the possibility of a duty of right to oneself. This article addresses this interpretative problem. Regarding (a) I suggest that while honeste vive is a duty owed to oneself, the content of the duty concerns one's interaction with others. Regarding (b) I maintain that honeste vive is a general duty of right, and such duties are not externally enforceable. This view both allows for an understanding of the structure of obligation in the Doctrine of Right as a whole and forces us to reconsider two central aspects of Kant's concept of right—namely, that all rights are externally enforceable and owed to others. Not only does honeste vive belong to the Doctrine of Right but understanding the way in which it does can illuminate the significance and scope of duties belonging to Kant's political philosophy