Mammalian life depends on two distinct pathways of DNA damage tolerance.

DNA damage threatens genomic integrity and instigates stem cell failure. To bypass genotoxic lesions during replication, cells employ DNA damage tolerance (DDT), which is regulated via PCNA ubiquitination and REV1. DDT is conserved in all domains of life, yet its relevance in mammals remains unclear. Here, we show that inactivation of both PCNA-ubiquitination and REV1 results in embryonic and adult lethality, and the accumulation of DNA damage in hematopoietic stem and progenitor cells (HSPCs) that ultimately resulted in their depletion. Our results reveal the crucial relevance of DDT in the maintenance of stem cell compartments and mammalian life in unperturbed conditions.

Transfusion of Adult, but Not Neonatal, Platelets Promotes Monocyte Trafficking in Neonatal Mice.

BACKGROUND: Thrombocytopenia is common in preterm neonates. Platelet transfusions are sometimes given to thrombocytopenic neonates with the hope of reducing the bleeding risk, however, there are little clinical data to support this practice, and platelet transfusions may increase the bleeding risk or lead to adverse complications. Our group previously reported that fetal platelets expressed lower levels of immune-related mRNA compared with adult platelets. In this study, we focused on the effects of adult versus neonatal platelets on monocyte immune functions that may have an impact on neonatal immune function and transfusion complications. METHODS: Using RNA sequencing of postnatal day 7 and adult platelets, we determined age-dependent platelet gene expression. Platelets and naive bone marrow-isolated monocytes were cocultured and monocyte phenotypes determined by RNA sequencing and flow cytometry. An in vivo model of platelet transfusion in neonatal thrombocytopenic mice was used in which platelet-deficient TPOR (thrombopoietin receptor) mutant mice were transfused with adult or postnatal day 7 platelets and monocyte phenotypes and trafficking were determined. RESULTS: Adult and neonatal platelets had differential immune molecule expression, including Selp. Monocytes incubated with adult or neonatal mouse platelets had similar inflammatory (Ly6Chi) but different trafficking phenotypes, as defined by CCR2 and CCR5 mRNA and surface expression. Blocking P-sel (P-selectin) interactions with its PSGL-1 (P-sel glycoprotein ligand-1) receptor on monocytes limited the adult platelet-induced monocyte trafficking phenotype, as well as adult platelet-induced monocyte migration in vitro. Similar results were seen in vivo, when thrombocytopenic neonatal mice were transfused with adult or postnatal day 7 platelets; adult platelets increased monocyte CCR2 and CCR5, as well as monocyte chemokine migration, whereas postnatal day 7 platelets did not. CONCLUSIONS: These data provide comparative insights into adult and neonatal platelet transfusion-regulated monocyte functions. The transfusion of adult platelets to neonatal mice was associated with an acute inflammatory and trafficking monocyte phenotype that was platelet P-sel dependent and may have an impact on complications associated with neonatal platelet transfusions.

ß2M Signals Monocytes Through Non-Canonical TGFß Receptor Signal Transduction.

RATIONALE: Circulating monocytes can have proinflammatory or proreparative phenotypes. The endogenous signaling molecules and pathways that regulate monocyte polarization in vivo are poorly understood. We have shown that platelet-derived ß2M (ß-2 microglobulin) and TGF-ß (transforming growth factor ß) have opposing effects on monocytes by inducing inflammatory and reparative phenotypes, respectively, but each bind and signal through the same receptor. We now define the signaling pathways involved. OBJECTIVE: To determine the molecular mechanisms and signal transduction pathways by which ß2M and TGF-ß regulate monocyte responses both in vitro and in vivo. METHODS AND RESULTS: Wild-type- (WT) and platelet-specific ß2M knockout mice were treated intravenously with either ß2M or TGF-ß to increase plasma concentrations to those in cardiovascular diseases. Elevated plasma ß2M increased proinflammatory monocytes, while increased plasma TGFß increased proreparative monocytes. TGF-ßR (TGF-ß receptor) inhibition blunted monocyte responses to both ß2M and TGF-ß in vivo. Using imaging flow cytometry, we found that ß2M decreased monocyte SMAD2/3 nuclear localization, while TGF-ß promoted SMAD nuclear translocation but decreased noncanonical/inflammatory (JNK [jun kinase] and NF-κB [nuclear factor-κB] nuclear localization). This was confirmed in vitro using both imaging flow cytometry and immunoblots. ß2M, but not TGF-ß, promoted ubiquitination of SMAD3 and SMAD4, that inhibited their nuclear trafficking. Inhibition of ubiquitin ligase activity blocked noncanonical SMAD-independent monocyte signaling and skewed monocytes towards a proreparative monocyte response. CONCLUSIONS: Our findings indicate that elevated plasma ß2M and TGF-ß dichotomously polarize monocytes. Furthermore, these immune molecules share a common receptor but induce SMAD-dependent canonical signaling (TGF-ß) versus noncanonical SMAD-independent signaling (ß2M) in a ubiquitin ligase dependent manner. This work has broad implications as ß2M is increased in several inflammatory conditions, while TGF-ß is increased in fibrotic diseases. Graphic Abstract: A graphic abstract is available for this article.

Exclusive enteral nutrition: An optimal care pathway for use in children with active luminal Crohn's disease.

AIM: Exclusive enteral nutrition (EEN) is recommended as a first-line therapy for active luminal paediatric Crohn's disease, by many contemporary consensus guidelines. However, EEN protocols vary internationally. A key enabler for the use of EEN therapy has been identified as the standardisation of protocols. The aim of this study was to develop an optimal care pathway for use of EEN in children with active luminal Crohn's disease. METHODS: A working group of 11 paediatric gastroenterology dietitians and one paediatric gastroenterologist from Australia and New Zealand was convened to develop a standard optimal care pathway. Seven key areas were identified; clinical indications, workup assessments, EEN prescription, monitoring, food reintroduction, partial enteral nutrition and maintenance enteral nutrition. Recent literature was reviewed, assessed according to the National Health and Medical Research Council guidelines, and consensus statements were developed and voted on. Consensus opinion was used where literature gaps existed. RESULTS: A total of nineteen consensus statements from the seven key areas were agreed upon. The consensus statements informed the optimal care pathway for children with active luminal undertaking EEN in Australia and New Zealand. CONCLUSION: This study developed an EEN optimal care pathway to facilitate standardisation of clinical care for children with active luminal Crohn's disease, and hopefully improve clinical outcomes and identify areas for future research.

Kit ligand has a critical role in mouse yolk sac and aorta-gonad-mesonephros hematopoiesis.

Few studies report on the in vivo requirement for hematopoietic niche factors in the mammalian embryo. Here, we comprehensively analyze the requirement for Kit ligand (Kitl) in the yolk sac and aorta-gonad-mesonephros (AGM) niche. In-depth analysis of loss-of-function and transgenic reporter mouse models show that Kitl-deficient embryos harbor decreased numbers of yolk sac erythro-myeloid progenitor (EMP) cells, resulting from a proliferation defect following their initial emergence. This EMP defect causes a dramatic decrease in fetal liver erythroid cells prior to the onset of hematopoietic stem cell (HSC)-derived erythropoiesis, and a reduction in tissue-resident macrophages. Pre-HSCs in the AGM require Kitl for survival and maturation, but not proliferation. Although Kitl is expressed widely in all embryonic hematopoietic niches, conditional deletion in endothelial cells recapitulates germline loss-of-function phenotypes in AGM and yolk sac, with phenotypic HSCs but not EMPs remaining dependent on endothelial Kitl upon migration to the fetal liver. In conclusion, our data establish Kitl as a critical regulator in the in vivoAGM and yolk sac endothelial niche.

A framework to support quality of care for patients with chronic intestinal failure requiring home parenteral nutrition.

BACKGROUND AND AIM: Chronic intestinal failure requiring home parenteral nutrition (HPN) is a disabling condition that is best facilitated by a multidisciplinary approach to care. Variation in care has been identified as a key barrier to achieving quality of care for patients on HPN and requires appropriate strategies to help standardize management. METHOD: The Australasian Society for Parenteral and Enteral Nutrition (AuSPEN) assembled a multidisciplinary working group of 15 clinicians to develop a quality framework to assist with the standardization of HPN care in Australia. Obstacles to quality care specific to Australia were identified by consensus. Drafts of the framework documents were based on the available literature and refined by two Delphi rounds with the clinician work group, followed by a further two involving HPN consumers. The Oxford Centre for Evidence-Based Medicine Levels of Evidence was used to assess the strength of evidence underpinning each concept within the framework documents. RESULTS: Quality indicators, standards of care, and position statements have been developed to progress the delivery of quality care to HPN patients. CONCLUSION: The quality framework proposed by AuSPEN is intended to provide a practical structure for clinical and organizational aspects of HPN service delivery to reduce variation in care and improve quality of care and represents the initial step towards development of a national model of care for HPN patients in Australia. While developed for implementation in Australia, the evidence-based framework also has relevance to the international HPN community.

National Parent Survey 2017: Worries, hopes, and child well-being.

Sociopolitical events impact population health; parents' perspective of such events crosses demographics, geography, and generations. We elicited changes in U.S. parents' hopes and worries for their children 1 year after the 2016 election via an online survey of school climate, discrimination against child, family health care and security, and macrolevel/future concerns (e.g., environment, postsecondary options). Among n = 1189 respondents, national security (39%), the environment (30.5%), and "continued place in America" (25.7%) were most worrisome. In general linear mixed models, employment buffered against social and material stressors such as discrimination (odds ratio [OR] = 0.67; 95% confidence interval [CI] = 0.49-0.92), and family health care/security (OR = 0.62; 95% CI = 0.45-0.86) while being of a dominant religion and ethnicity buffered future macrolevel (Christianity, OR = 70; 95% CI = 0.54-0.92/non-Hispanic, OR = 59; 95% CI = 0.39-0.90) and existential "continued place in America" (Christianity, OR = 69; 95% CI = 0.51-0.94/non-Hispanic, OR = 56; 95% CI = 0.36-0.88) worries. Qualitative comments underscored macrolevel worries. Parents represent a unique vantage for gauging how sociopolitical events impact health and well-being.

Parenteral nutrition use in children with cancer.

Multiple disease and treatment-related factors contribute to intestinal insult and influence the nutritional status of children with cancer. Many children with cancer will experience intestinal dysfunction during their cancer journey and children with cancer are a common referral group for inpatient parenteral nutrition. Appropriate use of parenteral nutrition in children with cancer and intestinal failure may alleviate malnutrition and associated risks. However, proper selection of patients, correct parenteral nutrition prescription, and close monitoring is important to avoid unnecessary intestinal failure or parenteral nutrition-related complications, minimize long-term nutritional sequelae or additional costs to health services, and optimize intestinal rehabilitation.

Gastrostomy tube use in children with cancer.

Children with cancer are at risk of malnutrition, which can impair critical childhood processes of growth and development and contribute to poor health outcomes. Enteral nutrition can effectively ameliorate malnutrition or weight loss in children with cancer; however, published nutrition support algorithms contain minimal specific information on gastrostomy tube use, and current literature is limited. Decisions about gastrostomy tube insertion in children with cancer can be challenging. Consideration of gastrostomy tube insertion is only appropriate in children with long-term dependence on enteral nutrition, particularly when nasogastric tube insertion is predicted or proven to be problematic. Specific indications for patient selection are unclear, and referring clinicians may be unaware of important absolute and relative contraindications. Complications are predominantly minor in nature; however, reported rates are high. Morbidity must be weighed carefully against the need and anticipated duration of enteral nutrition support, and further research in this area is needed.

Early hematopoiesis and macrophage development.

The paradigm that all blood cells are derived from hematopoietic stem cells (HSCs) has been challenged by two findings. First, there are tissue-resident hematopoietic cells, including subsets of macrophages that are not replenished by adult HSCs, but instead are maintained by self-renewal of fetal-derived cells. Second, during embryogenesis, there is a conserved program of HSC-independent hematopoiesis that precedes HSC function and is required for embryonic survival. The presence of waves of HSC-independent hematopoiesis as well as fetal HSCs raises questions about the origin of fetal-derived adult tissue-resident macrophages. In the murine embryo, historical examination of embryonic macrophage and monocyte populations combined with recent reports utilizing genetic lineage-tracing approaches has led to a model of macrophage ontogeny that can be integrated with existing models of hematopoietic ontogeny. The first wave of hematopoiesis contains primitive erythroid, megakaryocyte and macrophage progenitors that arise in the yolk sac, and these macrophage progenitors are the source of early macrophages throughout the embryo, including the liver. A second wave of multipotential erythro-myeloid progenitors (EMPs) also arises in the yolk sac. EMPs colonize the fetal liver, initiating myelopoiesis and forming macrophages. Lineage tracing indicates that this second wave of macrophages are distributed in most fetal tissues, although not appreciably in the brain. Thus, fetal-derived adult tissue-resident macrophages, other than microglia, appear to predominately derive from EMPs. While HSCs emerge at midgestation and colonize the fetal liver, the relative contribution of fetal HSCs to tissue macrophages at later stages of development is unclear. The inclusion of macrophage potential in multiple waves of hematopoiesis is consistent with reports of their functional roles throughout development in innate immunity, phagocytosis, and tissue morphogenesis and remodeling. Understanding the influences of developmental origin, as well as local tissue-specific signals, will be necessary to fully decode the diverse functions and responses of tissue-resident macrophages.

Zap it track it: the application of Lean Six Sigma methods to improve the screening system of low-grade mucinous neoplasms of the appendix in an acute hospital setting.

OBJECTIVE: To improve the number of patients receiving annual computed tomography (CT) scan and tumour markers, who are diagnosed with low-grade mucinous neoplasms (LAMN). DESIGN: A pre-/post-intervention design was employed using Lean Six Sigma methods to identify gaps in the screening system and to develop and implement solutions for a more robust, auditable screening programme. SETTING: The patients diagnosed with LAMN of the appendix referred to the acute hospital and are enrolled in the screening service. PARTICIPANTS: Consultant colorectal surgeons, cancer nurse specialist, colorectal medical team and quality improvement staff. INTERVENTIONS: Diagnostic tools identified gaps in the current process. A set of improvements were implemented to standardize the pathway for referral and surveillance of patients, provide information on the condition and treatment and standardize and track information received by patients and their referring hospital. MAIN OUTCOME MEASURE(S): Pre and post-intervention outcome measures were taken for the number of patients who receive an annual CT of thoracic, abdomen and peritoneum and tumour markers and number of patients who receive information and contact details. RESULTS: At baseline, of the 28 patients that met the inclusion criteria only 61% had a correct follow-up. Following the implementation of improvements, 78% of patients had correct follow-up and 90% had received information. CONCLUSIONS: Gaps in the current cancer screening system were identified and improvements implemented a reduced number of patients having an incorrect follow-up. Findings are applicable across all precancerous screening systems irrespective of the type of malignancy. The methods used empowered patients and fostered an interdisciplinary team approach to care.

Phylogenomic support for evolutionary relationships of New World direct-developing frogs (Anura: Terraranae).

Phylogenomic approaches have proven able to resolve difficult branches in the tree of life. New World direct-developing frogs (Terraranae) represent a large evolutionary radiation in which interrelationships at key points in the phylogeny have not been adequately determined, affecting evolutionary, biogeographic, and taxonomic interpretations. We employed anchored hybrid enrichment to generate a data set containing 389 loci and >600,000 nucleotide positions for 30 terraranan and several outgroup frog species encompassing all major lineages in the clade. Concatenated maximum likelihood and coalescent species-tree approaches recover nearly identical topologies with strong support for nearly all relationships in the tree. These results are similar to previous phylogenetic results but provide additional resolution at short internodes. Among taxa whose placement varied in previous analyses, Ceuthomantis is shown to be the sister taxon to all other terraranans, rather than deeply embedded within the radiation, and Strabomantidae is monophyletic rather than paraphyletic with respect to Craugastoridae. We present an updated taxonomy to reflect these results, and describe a new subfamily for the genus Hypodactylus.

EKLF/KLF1-regulated cell cycle exit is essential for erythroblast enucleation.

The mechanisms regulating the sequential steps of terminal erythroid differentiation remain largely undefined, yet are relevant to human anemias that are characterized by ineffective red cell production. Erythroid Krüppel-like Factor (EKLF/KLF1) is a master transcriptional regulator of erythropoiesis that is mutated in a subset of these anemias. Although EKLF's function during early erythropoiesis is well studied, its role during terminal differentiation has been difficult to functionally investigate due to the impaired expression of relevant cell surface markers in Eklf(-/-) erythroid cells. We have circumvented this problem by an innovative use of imaging flow cytometry to investigate the role of EKLF in vivo and have performed functional studies using an ex vivo culture system that enriches for terminally differentiating cells. We precisely define a previously undescribed block during late terminal differentiation at the orthochromatic erythroblast stage for Eklf(-/-) cells that proceed beyond the initial stall at the progenitor stage. These cells efficiently decrease cell size, condense their nucleus, and undergo nuclear polarization; however, they display a near absence of enucleation. These late-stage Eklf(-/-) cells continue to cycle due to low-level expression of p18 and p27, a new direct target of EKLF. Surprisingly, both cell cycle and enucleation deficits are rescued by epistatic reintroduction of either of these 2 EKLF target cell cycle inhibitors. We conclude that the cell cycle as regulated by EKLF during late stages of differentiation is inherently critical for enucleation of erythroid precursors, thereby demonstrating a direct functional relationship between cell cycle exit and nuclear expulsion.

A Systems Approach Identifies Essential FOXO3 Functions at Key Steps of Terminal Erythropoiesis.

Circulating red blood cells (RBCs) are essential for tissue oxygenation and homeostasis. Defective terminal erythropoiesis contributes to decreased generation of RBCs in many disorders. Specifically, ineffective nuclear expulsion (enucleation) during terminal maturation is an obstacle to therapeutic RBC production in vitro. To obtain mechanistic insights into terminal erythropoiesis we focused on FOXO3, a transcription factor implicated in erythroid disorders. Using an integrated computational and experimental systems biology approach, we show that FOXO3 is essential for the correct temporal gene expression during terminal erythropoiesis. We demonstrate that the FOXO3-dependent genetic network has critical physiological functions at key steps of terminal erythropoiesis including enucleation and mitochondrial clearance processes. FOXO3 loss deregulated transcription of genes implicated in cell polarity, nucleosome assembly and DNA packaging-related processes and compromised erythroid enucleation. Using high-resolution confocal microscopy and imaging flow cytometry we show that cell polarization is impaired leading to multilobulated Foxo3-/- erythroblasts defective in nuclear expulsion. Ectopic FOXO3 expression rescued Foxo3-/- erythroblast enucleation-related gene transcription, enucleation defects and terminal maturation. Remarkably, FOXO3 ectopic expression increased wild type erythroblast maturation and enucleation suggesting that enhancing FOXO3 activity may improve RBCs production. Altogether these studies uncover FOXO3 as a novel regulator of erythroblast enucleation and terminal maturation suggesting FOXO3 modulation might be therapeutic in disorders with defective erythroid maturation.

Definitive Hematopoiesis in the Yolk Sac Emerges from Wnt-Responsive Hemogenic Endothelium Independently of Circulation and Arterial Identity.

Adult-repopulating hematopoietic stem cells (HSCs) emerge in low numbers in the midgestation mouse embryo from a subset of arterial endothelium, through an endothelial-to-hematopoietic transition. HSC-producing arterial hemogenic endothelium relies on the establishment of embryonic blood flow and arterial identity, and requires ß-catenin signaling. Specified prior to and during the formation of these initial HSCs are thousands of yolk sac-derived erythro-myeloid progenitors (EMPs). EMPs ensure embryonic survival prior to the establishment of a permanent hematopoietic system, and provide subsets of long-lived tissue macrophages. While an endothelial origin for these HSC-independent definitive progenitors is also accepted, the spatial location and temporal output of yolk sac hemogenic endothelium over developmental time remain undefined. We performed a spatiotemporal analysis of EMP emergence, and document the morphological steps of the endothelial-to-hematopoietic transition. Emergence of rounded EMPs from polygonal clusters of Kit(+) cells initiates prior to the establishment of arborized arterial and venous vasculature in the yolk sac. Interestingly, Kit(+) polygonal clusters are detected in both arterial and venous vessels after remodeling. To determine whether there are similar mechanisms regulating the specification of EMPs with other angiogenic signals regulating adult-repopulating HSCs, we investigated the role of embryonic blood flow and Wnt/ß-catenin signaling during EMP emergence. In embryos lacking a functional circulation, rounded Kit(+) EMPs still fully emerge from unremodeled yolk sac vasculature. In contrast, canonical Wnt signaling appears to be a common mechanism regulating hematopoietic emergence from hemogenic endothelium. These data illustrate the heterogeneity in hematopoietic output and spatiotemporal regulation of primary embryonic hemogenic endothelium.

Molecular characterization of blaESBL-producing Escherichia coli cultured from pig farms in Ireland.

OBJECTIVES: To characterize ESBL-encoding Escherichia coli cultured from pigs and their plasmids carrying these genes following conjugation into recipient strains. METHODS: Six ESBL-producing E. coli were recovered from faecal samples taken from pigs along with a further isolate from the environment of a farrowing house on three pig farms in Ireland. These isolates were characterized by phylogenetic grouping, MLST and ESBL genotype analyses. Conjugation experiments were carried out in broth mating assays. S1-nuclease PFGE was used to determine the plasmid profiles. Whole-genome sequences of the seven E. coli were determined and subsequently analysed. RESULTS: Phylogenetic groups and the corresponding MLST STs identified among the seven tested E. coli isolates included A/ST10, A/ST34, C/ST23 and C/ST1629. All seven isolates carried one or more high-molecular-weight plasmids and demonstrated the ability to transfer their cefotaxime resistance phenotype at high frequencies. Five transmissible plasmid replicon types were detected, including IncK/B (n = 3), IncI1 (n = 2), IncFIA (n = 1), IncFIB (n = 1) and IncN (n = 1). ESBL-encoding genes, including blaCTX-M-14, blaCTX-M-15 and blaTEM-20, were identified. CONCLUSIONS: As the first report from pig sources in Ireland, characterization of these ESBL-encoding isolates and their transmissible plasmids extends our understanding on these resistance markers from porcine E. coli.

Red cell island dances: switching hands.

In this issue of Blood, Toda et al present a shift in the paradigm of erythroid enucleation and provide novel tools to further study and optimize terminal erythroid maturation in vitro.

SDF-1 dynamically mediates megakaryocyte niche occupancy and thrombopoiesis at steady state and following radiation injury.

Megakaryocyte (MK) development in the bone marrow progresses spatially from the endosteal niche, which promotes MK progenitor proliferation, to the sinusoidal vascular niche, the site of terminal maturation and thrombopoiesis. The chemokine stromal cell-derived factor-1 (SDF-1), signaling through CXCR4, is implicated in the maturational chemotaxis of MKs toward sinusoidal vessels. Here, we demonstrate that both IV administration of SDF-1 and stabilization of endogenous SDF-1 acutely increase MK-vasculature association and thrombopoiesis with no change in MK number. In the setting of radiation injury, we find dynamic fluctuations in marrow SDF-1 distribution that spatially and temporally correlate with variations in MK niche occupancy. Stabilization of altered SDF-1 gradients directly affects MK location. Importantly, these SDF-1-mediated changes have functional consequences for platelet production, as the movement of MKs away from the vasculature decreases circulating platelets, while MK association with the vasculature increases circulating platelets. Finally, we demonstrate that manipulation of SDF-1 gradients can improve radiation-induced thrombocytopenia in a manner additive with earlier TPO treatment. Taken together, our data support the concept that SDF-1 regulates the spatial distribution of MKs in the marrow and consequently circulating platelet numbers. This knowledge of the microenvironmental regulation of the MK lineage could lead to improved therapeutic strategies for thrombocytopenia.

Evaluations of intergroup resource allocations: The role of theory of mind.

The purpose of this study was to investigate the relations between children's social cognitive skills and their evaluations of resource allocations in intergroup contexts (N=73, 3-6years of age). Participants evaluated three snack-time resource allocation scenarios (self-disadvantaged, self-advantaged, and other-disadvantaged) in either a school ingroup or outgroup context. They evaluated the acceptability of the resource allocation and provided reasoning about their evaluation. Participants who had false belief theory of mind (FB ToM) competence were more likely than participants who did not have FB ToM to evaluate inequality as unacceptable. In addition, participants without FB ToM evaluated unequal allocations to another child as more okay in an outgroup condition than participants with FB ToM. Participants reasoned about their allocations differently depending on the context. Results reveal the importance of FB ToM for recognizing unfair resource allocations, especially in intergroup contexts.