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Lucy Gracen,1 Melanie Aikebuse,2,3 Babak Sarraf,2– 4 Steven M McPhail,5 Anthony W Russell,6 James O’Beirne,7 Katharine M Irvine,8 Suzanne Williams,9 Patricia C Valery,4,* Elizabeth E Powell2– 4,* 1Department of Gastroenterology and Hepatology, Royal Brisbane and Women’s Hospital, Herston, QLD, Australia; 2Department of Gastroenterology and Hepatology, Princess Alexandra Hospital, Woolloongabba, QLD, Australia; 3Centre for Liver Disease Research, Faculty of Medicine, Translational Research Institute, The University of Queensland, Woolloongabba, QLD, Australia; 4QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; 5Australian Centre for Health Services Innovation School of Public Health, Institute of Health and Biomedical Innovation, Queensland University of Technology (QUT), Brisbane, QLD, Australia; 6Endocrinology and Diabetes, the Alfred Hospital, Melbourne, VIC, Australia; 7Department of Gastroenterology and Hepatology, Sunshine Coast University Hospital, Birtinya, QLD, Australia; 8Mater Research, Translational Research Institute, Brisbane, QLD, Australia; 9Inala Primary Care General Practice, Inala, QLD, Australia*These authors contributed equally to this workCorrespondence: Elizabeth E Powell, Centre for Liver Disease Research, Faculty of Medicine, Translational, Research Institute, The University of Queensland, Level 5, West Wing, 37, Kent Street, Woolloongabba, Brisbane, QLD, 4102, Australia, Tel +61 412 014 337, Email e.powell@uq.edu.auBackground: Although clinical guidelines endorse screening for metabolic dysfunction-associated steatotic liver disease (MASLD) with advanced fibrosis in people with type 2 diabetes (T2D), the feasibility of and barriers and considerations relevant to implementing this approach in the community remain unclear.Methods: Sequential adults with T2D attending selected community clinics during 2021– 2023 were invited to receive a “liver health check” (n=543). A further 95 participants were referred directly from their general practitioner (GP) or self-referred to the study. A total of 302 participants underwent a point of care assessment of hepatic steatosis and stiffness (FibroScan) and were advised to see their GP to discuss the results. “Template” letters containing key results, their interpretation and advice about management of cardiometabolic risk, patient follow-up and referral criteria, were sent to participants’ GPs.Results: Referral to a tertiary liver clinic was advised in GP letters for 45 (15%) participants with an increased risk of clinically significant fibrosis (liver stiffness measurement ≥ 8), 15 participants with ‘red flags’ (eg splenomegaly, thrombocytopenia) and 2 with unsuccessful FibroScan examinations. A referral from GPs to the liver clinic was received for 27 (44%) of these 62 participants. Approximately 90% of GPs rated the “template” letters favourably on a Likert rating scale.Conclusion: The low rate of participation in the “liver health check” and liver clinic referral reflects a real-world scenario and may stem from societal under-recognition and engagement with MASLD, competing health priorities or under-appreciation of the link between liver fibrosis severity and mortality risk. Further studies need to address strategies to enhance participation in liver health assessments and determine their impact on liver-related morbidity/mortality and overall survival.Keywords: NAFLD, primary care, chronic liver disease, FibroScan

Novel biomarkers of disease progression after type 1 diabetes onset are needed. We profiled peripheral blood (PB) monocyte gene expression in six healthy subjects and 16 children with type 1 diabetes diagnosed ∼3 months previously and analyzed clinical features from diagnosis to 1 year. Monocyte expression profiles clustered into two distinct subgroups, representing mild and severe deviation from healthy control subjects, along the same continuum. Patients with strongly divergent monocyte gene expression had significantly higher insulin dose-adjusted HbA(1c) levels during the first year, compared with patients with mild deviation. The diabetes-associated expression signature identified multiple perturbations in pathways controlling cellular metabolism and survival, including endoplasmic reticulum and oxidative stress (e.g., induction of HIF1A, DDIT3, DDIT4, and GRP78). Quantitative PCR (qPCR) of a 9-gene panel correlated with glycemic control in 12 additional recent-onset patients. The qPCR signature was also detected in PB from healthy first-degree relatives. A PB gene expression signature correlates with glycemic control in the first year after diabetes diagnosis and is present in at-risk subjects. These findings implicate monocyte phenotype as a candidate biomarker for disease progression pre- and postonset and systemic stresses as contributors to innate immune function in type 1 diabetes. [ABSTRACT FROM AUTHOR]

Macrophage and osteoclast proliferation, differentiation and survival are regulated by colony-stimulating factor 1 receptor (CSF1R) signaling. Osteopetrosis associated with Csf1 and Csf1r mutations has been attributed to the loss of osteoclasts and deficiency in bone resorption. Here, we demonstrate that homozygous Csf1r mutation in rat leads to delayed postnatal skeletal ossification associated with substantial loss of osteal macrophages in addition to osteoclasts. Osteosclerosis and site-specific skeletal abnormalities were reversed by intraperitoneal transfer of wild-type bone marrow cells (bone marrow cell transfer, BMT) at weaning. Following BMT, IBA1+ macrophages were detected before TRAP+ osteoclasts at sites of ossification restoration. These observations extend evidence that osteal macrophages independently contribute to bone anabolism and are required for normal postnatal bone growth and morphogenesis., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology.)

Bacteria adapt to selective pressure in their immediate environment in multiple ways. One mechanism involves the acquisition of independent mutations that disable or modify a key pathway, providing a signature of adaptation via convergent evolution. Extra-intestinal pathogenic Escherichia coli (ExPEC) belonging to sequence type 95 (ST95) represent a global clone frequently associated with severe human infections including acute pyelonephritis, sepsis, and neonatal meningitis. Here, we analysed a publicly available dataset of 613 ST95 genomes and identified a series of loss-of-function mutations that disrupt cellulose production or its modification in 55.3% of strains. We show the inability to produce cellulose significantly enhances ST95 invasive infection in a rat model of neonatal meningitis, leading to the disruption of intestinal barrier integrity in newborn pups and enhanced dissemination to the liver, spleen and brain. Consistent with these observations, disruption of cellulose production in ST95 augmented innate immune signalling and tissue neutrophil infiltration in a mouse model of urinary tract infection. Mutations that disrupt cellulose production were also identified in other virulent ExPEC STs, Shigella and Salmonella, suggesting a correlative association with many Enterobacteriaceae that cause severe human infection. Together, our findings provide an explanation for the emergence of hypervirulent Enterobacteriaceae clones., (© 2024. The Author(s).)

Macrophages regulate metabolic homeostasis in health and disease. Macrophage colony-stimulating factor (CSF1)-dependent macrophages contribute to homeostatic control of the size of the liver. This study aimed to determine the systemic metabolic consequences of elevating circulating CSF1. Acute administration of a CSF1-Fc fusion protein to mice led to monocytosis, increased resident tissue macrophages in the liver and all major organs, and liver growth. These effects were associated with increased hepatic glucose uptake and extensive mobilization of body fat. The impacts of CSF1 on macrophage abundance, liver size, and body composition were rapidly reversed to restore homeostasis. The effects of CSF1 on metabolism were independent of several known endocrine regulators and did not impact the physiological fasting response. Analysis using implantable telemetry in metabolic cages revealed progressively reduced body temperature and physical activity with no change in diurnal food intake. These results demonstrate the existence of a dynamic equilibrium between CSF1, the mononuclear phagocyte system, and control of liver-to-body weight ratio, which in turn controls systemic metabolic homeostasis. This novel macrophage regulatory axis has the potential to promote fat mobilization, without changes in appetence, which may have novel implications for managing metabolic syndrome. NEW & NOTEWORTHY CSF1 administration expands tissue macrophages, which transforms systemic metabolism. CSF1 drives fat mobilization and glucose uptake to support liver growth. The effects of CSF1 are independent of normal hormonal metabolic regulation. The effects of CSF1 are rapidly reversible, restoring homeostatic body composition. CSF1-dependent macrophages and liver size are coupled in a dynamic equilibrium.

Macrophages contribute to many aspects of development and homeostasis, innate and acquired immunity, immunopathology, and tissue repair. Every tissue contains an abundant resident macrophage population. Inflammatory stimuli promote the recruitment of monocytes from the blood and their adaptation promotes the removal of the stimulus and subsequent restoration of normal tissue architecture. Dysregulation of this response leads to chronic inflammation and tissue injury. In many tissues, their differentiation and survival are dependent on the colony stimulating factor 1 receptor (CSF1R) signalling axis, which is highly conserved across all vertebrates. Complete loss of either CSF1R or its cognate ligands, colony stimulating factor 1 (CSF1), and interleukin 34 (IL-34), results in the loss of many tissue-resident macrophage populations. This provides a useful paradigm to study macrophages.There are many tools used to visualize tissue-resident macrophages and their precursors, monocytes, in mice and humans. Particularly in mice there are genetic tools available to delete, enhance and manipulate monocytes and macrophages and their gene products to gain insight into phenotype and function. The laboratory rat has many advantages as an experimental model for the understanding of human disease, but the analytical resources are currently more limited than in mice. Here, we describe available genetic models, antibodies, and immunohistochemistry (IHC) methods that may be used to visualize tissue-resident macrophages in rats., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Introduction and Objectives: Among people with type 2 diabetes (T2D), non-alcoholic fatty liver disease (NAFLD) is very common and has an increased risk of clinically significant liver disease. The use of sodium-glucose co-transporter 2 (SGLT2i) inhibitors and glucagon-like peptide-1 (GLP-1a) receptor agonists is endorsed to reduce major cardiovascular events and/or progression of chronic kidney disease. Their prevalence of use in people with T2D and co-existent NAFLD remains unclear. We sought to determine the prevalence of use of these medications at two different time periods, and their association with prevalence of clinically significant liver disease., Materials and Methods: Consecutive people with type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) were recruited from diabetes clinics between Jun-2021 and Jun-2022 ('current' cohort). Liver stiffness measurements (LSM) using FibroScan were performed. Medication data were collected prospectively at recruitment and verified with the dispensing pharmacy or general practitioner medical records. Data for a historical cohort with NAFLD and T2D recruited from the same clinics during 2015-2017 ('historical' cohort) were available. Logistic regression was used to evaluate factors associated with LSM <8.0 or ≥8 kPa (clinically significant fibrosis)., Results: There were 292 participants, 177 in the historical cohort and 115 in the current cohort. In the current cohort, 57.4% of patients with T2D and NAFLD were taking a GLP-1a and 42.6% were taking a SGLT2i; a 2.6 to 3.4-fold higher prevalence than in 2015-2017. A lower proportion of the current cohort (23.9% compared to 38.4%) had clinically significant fibrosis (LSM ≥8 kPa; p = 0.012). When the cohorts were pooled and differences adjusted for in multivariable logistic regression analysis, patients taking a GLP-1a or a SGLT2i were 2 times more likely to have a lower LSM (<8 kPa) compared to patients not taking these drugs (OR=2.05, 95%CI 1.07-3.94, p = 0.03 and OR 2.07 95%CI 1.04-4.11, p = 0.04, respectively)., Conclusions: The observation of a lower LSM in people taking SGLT2i and/or GLP-1a following adjustment for other relevant clinico-demographic variables provides support for clinical trials to assess their efficacy in reducing the progression of NAFLD., Competing Interests: Declaration of interests None., (Crown Copyright © 2023. Published by Elsevier España, S.L.U. All rights reserved.)

Macrophages are an abundant cell population in the placenta and developing embryo and appear to be involved in processes of vascularization, morphogenesis, organogenesis, and hematopoiesis. The proliferation, differentiation, and survival are dependent on signals from the macrophage colony-stimulating factor receptor, CSF1R. Aside from the role in macrophages, Csf1r mRNA is highly expressed in placental trophoblasts. To explore the function of macrophages and Csf1r in placental and embryonic development, we analyzed the impact of homozygous Csf1r null mutation (Csf1rko) in the rat. In late gestation, IBA1+ macrophages were abundant in control embryos in all tissues, including the placenta, and greatly reduced in the Csf1rko. CSF1R was also detected in stellate macrophage-like cells and in neurons using anti-CSF1R antibody but was undetectable in trophoblasts. However, the neuronal signal was not abolished in the Csf1rko. CD163 was most abundant in cells forming the center of erythroblastic islands in the liver and was also CSF1R dependent. Despite the substantial reduction in macrophage numbers, we detected no effect of the Csf1rko on development of the placenta or any organs, the relative abundance of vascular elements (CD31 staining), or cell proliferation (Ki67 staining). The loss of CD163+ erythroblastic island macrophages in the liver was not associated with anemia or any reduction in the proliferative activity in the liver, but there was a premature expansion of CD206+ cells, presumptive precursors of liver sinusoidal endothelial cells. We suggest that many functions of macrophages in development of the placenta and embryo can be provided by other cell types in their absence., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of Society for Leukocyte Biology.)

Weight loss in overweight or obese individuals with Type 2 diabetes (T2D) can normalize hepatic fat metabolism, decrease fatty acid oversupply to β cells and restore normoglycaemia. One in six people has BMI <27 kg/m2 at diagnosis, and their T2D is assumed to have different aetiology. The Personal Fat Threshold hypothesis postulated differing individual thresholds for lipid overspill and adverse effects on β-cell function. To test this hypothesis, people with Type 2 diabetes and body mass index <27kg/m2 (n = 20) underwent repeated 5% weight loss cycles. Metabolic assessments were carried out at stable weight after each cycle and after 12 months. To determine how closely metabolic features returned to normal, 20 matched normoglycemic controls were studied once. Between baseline and 12 months: BMI fell (mean ± SD), 24.8 ± 0.4 to 22.5 ± 0.4 kg/m2 (P<0.0001) (controls: 21.5 ± 0.5); total body fat, 32.1 ± 1.5 to 27.6 ± 1.8% (P<0.0001) (24.6 ± 1.5). Liver fat content and fat export fell to normal as did fasting plasma insulin. Post-meal insulin secretion increased but remained subnormal. Sustained diabetes remission (HbA1c < 48 mmol/mol off all glucose-lowering agents) was achieved by 70% (14/20) by initial weight loss of 6.5 (5.5-10.2)%. Correction of concealed excess intra-hepatic fat reduced hepatic fat export, with recovery of β-cell function, glycaemic improvement in all and return to a non-diabetic metabolic state in the majority of this group with BMI <27 kg/m2 as previously demonstrated for overweight or obese groups. The data confirm the Personal Fat Threshold hypothesis: aetiology of Type 2 diabetes does not depend on BMI. This pathophysiological insight has major implications for management., (© 2023 The Author(s).)

Homozygous null mutation of the Csf1r gene (Csf1rko) in rats leads to the loss of most tissue macrophage populations and pleiotropic impacts on postnatal growth and organ maturation, leading to early mortality. The phenotype can be reversed by intraperitoneal transfer of WT BM cells (BMT) at weaning. Here, we used a Csf1r-mApple transgenic reporter to track the fate of donor-derived cells. Following BMT into Csf1rko recipients, mApple +ve cells restored IBA1 + tissue macrophage populations in every tissue. However, monocytes, neutrophils, and B cells in the BM, blood, and lymphoid tissues remained of recipient (mApple -ve ) origin. An mApple +ve cell population expanded in the peritoneal cavity and invaded locally in the mesentery, fat pads, omentum, and diaphragm. One week after BMT, distal organs contained foci of mApple +ve , IBA1 -ve immature progenitors that appeared to proliferate, migrate, and differentiate locally. We conclude that rat BM contains progenitor cells that are able to restore, replace, and maintain all tissue macrophage populations in a Csf1rko rat directly without contributing to the BM progenitor or blood monocyte populations., (© 2023 The Authors. European Journal of Immunology published by Wiley-VCH GmbH.)

We have exploited islet-associated macrophages (IAMs) as a model of resident macrophage function, focusing on more physiological conditions than the commonly used extremes of M1 (inflammation) versus M2 (tissue remodeling) polarization. Under steady state, murine IAMs are metabolically poised between aerobic glycolysis and oxidative phosphorylation, and thereby exert a brake on glucose-stimulated insulin secretion (GSIS). This is underpinned by epigenetic remodeling via the metabolically regulated histone demethylase Kdm5a. Conversely, GSIS is enhanced by engaging Axl receptors on IAMs, or by augmenting their oxidation of glucose. Following high-fat feeding, efferocytosis is stimulated in IAMs in conjunction with Mertk and TGFβ receptor signaling. This impairs GSIS and potentially contributes to β-cell failure in pre-diabetes. Thus, IAMs serve as relays in many more settings than currently appreciated, fine-tuning insulin secretion in response to dynamic changes in the external environment. Intervening in this nexus might represent a means of preserving β-cell function during metabolic disease., Competing Interests: M.K. is a consulting scientific editor of iScience., (© 2023 The Author(s).)

Background and Aims: The European Association for the Study of the Liver (EASL) has recently proposed an algorithm for the diagnosis of advanced liver fibrosis. We aimed to evaluate the diagnostic accuracy of this algorithm in nonalcoholic fatty liver disease (NAFLD)., Approach and Results: One thousand fifty-one patients with NAFLD, liver biopsy, and four noninvasive tests (NITs; Fibrosis-4 [FIB4], vibration controlled transient elastography [VCTE], FibroMeter, Fibrotest) were included. The enhanced liver fibrosis (ELF) score was available in 396 patients. A cohort of 230 patients from primary care/diabetes clinics had FIB4, VCTE, and ELF. Compared with the performance of single NITs, agreement between two NITs (FIB4 and VCTE, VCTE and patented serum tests) increased specificity and positive predictive value by 20%, thus justifying the sequential use proposed in the EASL algorithm. The FIB4/VCTE/FibroMeter and FIB4/VCTE/Fibrotest algorithms performed similarly, providing 85% diagnostic accuracy and a liver biopsy requirement rate of only 10%. The FIB4/VCTE/ELF algorithm performed similarly in the subgroup where ELF was available. Simulations of algorithm accuracies at different prevalence showed that positive predictive values rapidly increased, reaching a plateau above 75% starting at 15% prevalence. Negative predictive values remained higher than 90% up to 25% prevalence. The rate of liver biopsy requirement remained stable, increasing by only 5% between low and high prevalence settings. When the EASL algorithm was applied in the primary care/diabetes clinic cohort, liver biopsy requirement was only 3%, and the agreement among the three steps provided 75% positive predictive value., Conclusions: Our study validates the algorithm proposed by the EASL in its latest 2021 guidelines for the diagnosis of advanced fibrosis in the setting of NAFLD., (Copyright © 2023 American Association for the Study of Liver Diseases.)

Background: Non-alcoholic fatty liver disease (NAFLD) is caused by ectopic fat accumulation in the liver as a consequence of metabolic perturbations associated with obesity, type 2 diabetes, dyslipidemia, and insulin resistance. People with NAFLD may develop metabolic and cardiovascular complications and/or liver-related complications, especially fibrosis and hepatocellular carcinoma, associated with high morbidity and mortality. Due to the high and increasing prevalence of NAFLD, there is an urgent need to identify people at risk of developing liver fibrosis and complications. CC-chemokine ligand 2 (CCL2) is chemokine that attracts inflammatory monocytes to stressed or injured tissues. Infiltrating inflammatory monocytes and CCL2 are strongly implicated in the pathogenesis of liver disease in animal models; however, evidence in patient cohorts is conflicting., Methods: We investigated associations between circulating CCL2 and clinical parameters, including fibrosis assessed by liver stiffness measurement, in a cohort of 250 NAFLD patients. We also measured fatty acid binding protein 2 (FABP2), a putative biomarker of intestinal permeability in patients with liver disease, since pro-inflammatory gut-derived microbial products may induce inflammatory chemokines such as CCL2., Results: Serum CCL2 levels were weakly associated with liver stiffness, but the association was no longer significant after accounting for age, diabetes, and BMI in a multivariable model. Consistent with this, girth and BMI were the strongest predictors of elevated circulating CCL2. Serum FABP2 was weakly, but significantly, correlated with CCL2, and negatively correlated with estimated glomerular filtration rate., Conclusion: Circulating CCL2 and FABP2 are associated with NAFLD comorbidities but not liver disease progression in patients with NAFLD., (© 2022 The Author(s). Published by S. Karger AG, Basel.)

Purpose of Review: The purpose of the review is to summarize the expression and function of CSF1R and its ligands in bone homeostasis and constraints on therapeutic targeting of this axis., Recent Findings: Bone development and homeostasis depends upon interactions between mesenchymal cells and cells of the mononuclear phagocyte lineage (MPS), macrophages, and osteoclasts (OCL). The homeostatic interaction is mediated in part by the systemic and local production of growth factors, macrophage colony-stimulating factor (CSF1), and interleukin 34 (IL34) that interact with a receptor (CSF1R) expressed exclusively by MPS cells and their progenitors. Loss-of-function mutations in CSF1 or CSF1R lead to loss of OCL and macrophages and dysregulation of postnatal bone development. MPS cells continuously degrade CSF1R ligands via receptor-mediated endocytosis. As a consequence, any local or systemic increase or decrease in macrophage or OCL abundance is rapidly reversible. In principle, both CSF1R agonists and antagonists have potential in bone regenerative medicine but their evaluation in disease models and therapeutic application needs to carefully consider the intrinsic feedback control of MPS biology., (© 2022. The Author(s).)

Background: The optimal strategy to support primary care practitioners (PCP) to assess fibrosis severity in non-alcoholic fatty liver disease (NAFLD) and thereby make appropriate management decisions remains unclear., Aims: To examine the feasibility of using a two-step pathway that combined simple scores (NAFLD Fibrosis Score and Fibrosis-4 Index) with transient elastography (FibroScan) to streamline NAFLD referrals from a 'routine' primary care population to specialist hepatology management clinics (HMC)., Methods: The two-step 'Towards Collaborative Management of NAFLD' (TCM-NAFLD) fibrosis risk assessment pathway was implemented at two outer metropolitan primary healthcare practices in Brisbane. Patients aged ≥18 years with a new or established PCP-diagnosis of NAFLD were eligible for assessment. The pathway triaged patients at 'high risk' of clinically significant fibrosis to HMC for specialist review, and 'low risk' patients to receive ongoing management and longitudinal follow up in primary care., Results: A total of 162 patient assessments between June 2019 and December 2020 were included. Mean age was 58.7 ± 11.7 years, 30.9% were male, 54.3% had type 2 diabetes or impaired fasting glucose, and mean body mass index was 34.2 ± 6.9 kg/m 2 . A total 122 patients was considered 'low risk' for clinically significant fibrosis, two patients had incomplete assessments and 38 (23.5%) were triaged to HMC. Among 31 completed HMC assessments to date, 45.2% were considered to have clinically significant (or more advanced) fibrosis, representing 9.2% of 153 completed assessments., Conclusion: Implementation of the two-step TCM-NAFLD pathway streamlined hepatology referrals for NAFLD and may facilitate a more cost-effective and targeted use of specialist hepatology resources., (© 2021 Royal Australasian College of Physicians.)

Abstract: Spontaneous bacterial peritonitis (SBP), a common infection in patients with cirrhosis and ascites, is associated with high morbidity and mortality. The aim of this study was to investigate changes in the epidemiology of ascites fluid infections over time in an Australian population, including patient demographics, trends in mortality, length of hospital stay and the nature and antibiotic resistance profile of causative organisms.An observational descriptive population-based epidemiological study of patients with cirrhosis admitted to public hospitals in Queensland during 2008-2017 was performed, linking demographic/clinical and microbiology data.Among 103,165 hospital admissions of patients with cirrhosis, ascites was present in 16,550 and in 60% (9977) a sample of ascitic fluid was tested. SBP was diagnosed in 770 admissions (neutrophil count >250/ml) and bacterascites in 552 (neutrophil count <250/ml with positive culture). The number of admissions with an ascites fluid infection increased by 76% from 2008 to 2017, paralleling an 84% increase in cirrhosis admissions over the same timeframe. Patients with SBP had a longer hospital stay (median 15.7 vs 8.3 days for patients without SBP, P < .001) and higher in-hospital mortality, although this decreased from 39.5% in 2008 to 2010 to 24.8% in 2015 to 2017 (P < .001). Common Gram-positive isolates included coagulase negative staphylococci (37.9%), viridans group streptococci (12.1%), and Staphylococcus aureus (7.2%). Common Gram-negative isolates included Escherichia coli (13.0%), Klebsiella pneumoniae (3.1%) and Enterobacter cloacae (2.6%). The prevalence of resistance to any tested antibiotic was <10%.SBP remains associated with high in-hospital mortality and long hospital stay. Typical skin and bowel pathogens were common, therefore, empirical antibiotic therapy should target these pathogens. This study provides valuable evidence informing infection management strategies in this vulnerable patient population., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Amino acid substitutions in the kinase domain of the human CSF1R gene are associated with autosomal dominant adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). To model the human disease, we created a disease-associated mutation (pGlu631Lys; E631K) in the mouse Csf1r locus. Homozygous mutation (Csf1rE631K/E631K) phenocopied the Csf1r knockout, with prenatal mortality or severe postnatal growth retardation and hydrocephalus. Heterozygous mutation delayed the postnatal expansion of tissue macrophage populations in most organs. Bone marrow cells from Csf1rE631K/+mice were resistant to CSF1 stimulation in vitro, and Csf1rE631K/+ mice were unresponsive to administration of a CSF1-Fc fusion protein, which expanded tissue macrophage populations in controls. In the brain, microglial cell numbers and dendritic arborisation were reduced in Csf1rE631K/+ mice, as in patients with ALSP. The microglial phenotype is the opposite of microgliosis observed in Csf1r+/- mice. However, we found no evidence of brain pathology or impacts on motor function in aged Csf1rE631K/+ mice. We conclude that heterozygous disease-associated CSF1R mutations compromise CSF1R signalling. We speculate that leukoencephalopathy associated with dominant human CSF1R mutations requires an environmental trigger and/or epistatic interaction with common neurodegenerative disease-associated alleles., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

Background: Non-alcoholic fatty liver disease (NAFLD) is an emerging epidemic that affects approximately half of all people with type 2 diabetes. Those with type 2 diabetes are a high-risk NAFLD subgroup because of their increased risk of clinically significant liver-related outcomes from NAFLD which include hepatocellular carcinoma, cirrhosis-related complications and liver disease mortality. They may benefit from early detection of disease as this would allow at risk patients to access hepatocellular carcinoma surveillance, emerging drug trials for NAFLD and specialist hepatology care prior to emergence of liver-related complications., Methods: This is a prospective cohort study aimed at incorporating and assessing a community care pathway for liver fibrosis screening into routine care for type 2 diabetes. Patients undergo a point of care assessment of hepatic steatosis and stiffness using FibroScan at the time of the routine diabetes appointment or when attending the clinic for blood tests in preparation for this appointment., Discussion: We propose that implementation of a community-based NAFLD diagnosis, risk-stratification, and referral pathway for people with type 2 diabetes is feasible, will provide earlier, targeted detection of advanced fibrosis, and reduce unnecessary referrals to hepatology outpatients for fibrosis risk assessment. Our study will provide important information about the feasibility of establishing a NAFLD pathway for people with type 2 diabetes in primary care. Ultimately, our findings will help direct spending and resource allocation for NAFLD in a high-risk population. Regular evaluation by stakeholders during implementation will help to create a reliable and sustainable community care pathway and establish a perpetual cycle of learning in primary care., Trial Registration: ANZCTR, ACTRN12621000330842 . Registered 23 March 2021., (© 2022. The Author(s).)

It remains unclear whether screening for advanced fibrosis in the community can identify the subgroup of people with nonalcoholic fatty liver disease (NAFLD) at higher risk for development of liver-related complications. We aimed to determine the prognostic value of baseline noninvasive fibrosis tests for predicting liver-related outcomes and mortality in patients with NAFLD from type 2 diabetes (T2D) clinics or primary care. Patients (n = 243) who were screened for NAFLD with advanced fibrosis by using NAFLD fibrosis score (NFS), fibrosis 4 score (FIB-4), enhanced liver fibrosis (ELF) test, and liver stiffness measurements (LSMs) were followed up for clinical outcomes by review of electronic medical records. During a median follow-up of 50 months, decompensated liver disease or primary liver cancer occurred in 6 of 35 (17.1%) patients with baseline LSM > 13 kPa, 1 of 17 (5.9%) patients with LSM 9.5-13 kPa, and in no patients with LSM < 9.5 kPa. No patient with low-risk NFS developed liver decompensation or liver-related mortality. Following repeat NFSs at the end of follow-up, all patients with a liver-related complication were in the high-risk NFS category. Patients who developed liver-related complications were also more likely to have baseline high-risk FIB-4 scores or ELF test ≥9.8 compared to patients who did not develop liver outcomes. Conclusion: Liver fibrosis risk stratification in non-hepatology settings can identify the subset of patients at risk of liver-related complications. Although the rate of development of a decompensation event or hepatocellular carcinoma was low (2.1% per year) in our patients with compensated cirrhosis (LSM > 13 kPa), these events are projected to lead to a substantial increase in NAFLD-related disease burden over the next decade due to the high prevalence of NAFLD in people with obesity and T2D., (© 2022 The Authors. Hepatology Communications published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Resident and recruited macrophages control the development and proliferation of the liver. We have previously shown in multiple species that treatment with a macrophage colony stimulating factor (CSF1)-Fc fusion protein initiated hepatocyte proliferation and promoted repair in models of acute hepatic injury in mice. Here, we investigated the impact of CSF1-Fc on resolution of advanced fibrosis and liver regeneration, using a non-resolving toxin-induced model of chronic liver injury and fibrosis in C57BL/6J mice. Co-administration of CSF1-Fc with exposure to thioacetamide (TAA) exacerbated inflammation consistent with monocyte contributions to initiation of pathology. After removal of TAA, either acute or chronic CSF1-Fc treatment promoted liver growth, prevented progression and promoted resolution of fibrosis. Acute CSF1-Fc treatment was also anti-fibrotic and pro-regenerative in a model of partial hepatectomy in mice with established fibrosis. The beneficial impacts of CSF1-Fc treatment were associated with monocyte-macrophage recruitment and increased expression of remodelling enzymes and growth factors. These studies indicate that CSF1-dependent macrophages contribute to both initiation and resolution of fibrotic injury and that CSF1-Fc has therapeutic potential in human liver disease., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

A hallmark of Listeria (L.) monocytogenes pathogenesis is bacterial escape from maturing entry vacuoles, which is required for rapid bacterial replication in the host cell cytoplasm and cell-to-cell spread. The bacterial transcriptional activator PrfA controls expression of key virulence factors that enable exploitation of this intracellular niche. The transcriptional activity of PrfA within infected host cells is controlled by allosteric coactivation. Inhibitory occupation of the coactivator site has been shown to impair PrfA functions, but consequences of PrfA inhibition for L. monocytogenes infection and pathogenesis are unknown. Here we report the crystal structure of PrfA with a small molecule inhibitor occupying the coactivator site at 2.0 Å resolution. Using molecular imaging and infection studies in macrophages, we demonstrate that PrfA inhibition prevents the vacuolar escape of L. monocytogenes and enables extensive bacterial replication inside spacious vacuoles. In contrast to previously described spacious Listeria-containing vacuoles, which have been implicated in supporting chronic infection, PrfA inhibition facilitated progressive clearance of intracellular L. monocytogenes from spacious vacuoles through lysosomal degradation. Thus, inhibitory occupation of the PrfA coactivator site facilitates formation of a transient intravacuolar L. monocytogenes replication niche that licenses macrophages to effectively eliminate intracellular bacteria. Our findings encourage further exploration of PrfA as a potential target for antimicrobials and highlight that intra-vacuolar residence of L. monocytogenes in macrophages is not inevitably tied to bacterial persistence., Competing Interests: The authors declare that no competing interests exist.

Non-alcoholic fatty liver disease (NAFLD) and depression are common disorders and have bidirectional contributing relationships to metabolic syndrome. We aimed to determine whether a fasting serum signature of recent, self-reported depressive symptoms could be identified in a heterogeneous NAFLD cohort using nuclear magnetic resonance (NMR)-based metabolomics integrated with clinical chemistry. Serum nuclear magnetic resonance (NMR) metabolite profiles and corresponding clinical chemistry were compared between patients with depressive symptoms in the last 12-months (n = 81) and patients without recent depressive symptoms (n = 137 controls) using multivariate statistics. Orthogonal partial least squares discriminant analysis (OPLS-DA) of the biochemical and metabolomic data identified NAFLD patients with recent depression with a cross-validated accuracy of 61.5%, independent of age, sex, medication, and other comorbidities. This led to the development of a diagnostic algorithm with AUC 0.83 for future testing in larger clinical cohorts. Serum triglycerides, VLDL cholesterol, and the inflammatory biomarker GlycA were key metabolites increased in patients with recent depressive symptoms, while serum glutamine level was reduced. Here, serum NMR metabolite analysis provides a link between disturbed lipid metabolism, inflammation, and active mental health issues in NAFLD, irrespective of disease severity., Competing Interests: The authors have declared that no competing interests exist.

Objective: Multiple factors predispose patients with cirrhosis to sepsis and/or bacteraemia and this has a high mortality rate. Within different geographical regions there are marked differences in the prevalence of infection with multidrug-resistant organisms (MDR). This study examined risk factors for and outcomes of sepsis/bacteraemia in public hospital admissions with cirrhosis in the state of Queensland, Australia, over the last decade, along with the bacterial pathogens responsible and their antibiotic susceptibility profiles., Design: A population-based retrospective cohort study of public hospital admissions was conducted from 1 January 2008 to 31 December 2017. Hospital admissions for patients with a diagnosis of cirrhosis were categorised by the presence or absence of sepsis/bacteraemia. Clinical and sociodemographic information including cirrhosis aetiology, complications and comorbidities, and in-hospital mortality were examined using bivariate and multivariate analyses. In patients with bacteraemia, the type and prevalence of bacteria and antibiotic resistance was assessed., Results: Sepsis/bacteraemia was present in 3951 of 103 165 hospital admissions with a diagnosis of cirrhosis. Factors associated with sepsis/bacteraemia included disease aetiology, particularly primary sclerosing cholangitis (adj-OR 15.09, 95% CI 12.24 to 18.60), alcohol (adj-OR 2.90, 95% CI 2.71 to 3.09), Charlson Comorbidity Index ≥3 (adj-OR 3.54, 95% CI 3.19 to 3.93) and diabetes (adj-OR 1.87, 95% CI 1.74 to 2.01). Overall case-fatality rate among admissions with sepsis/bacteraemia was 27.7% (95% CI 26.3% to 29.1%) vs 3.7% (95% CI 3.6% to 3.8%) without sepsis/bacteraemia. In-hospital death was significantly associated with sepsis/bacteraemia (adj-OR 6.50, 95% CI 5.95 to 7.11). The most common organisms identified were Escherichia coli and Staphylococcus aureus , present in 22.9% and 18.1%, respectively, of the 2265 admissions with a positive blood culture. The prevalence of MDR bacteria was low (5.6%) CONCLUSION: Morbidity and mortality related to sepsis/bacteraemia in patients with cirrhosis remains a critical clinical problem., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Discrepancies between the medicines consumed by patients and those documented in the medical record can affect medication safety. We aimed to characterize medication discrepancies and medication regimen complexity over time in a cohort of outpatients with decompensated cirrhosis, and evaluate the impact of pharmacist-led intervention on discrepancies and patient outcomes. In a randomized-controlled trial ( n = 57 intervention and n = 57 usual care participants), medication reconciliation and patient-oriented education delivered over a six-month period was associated with a 45% reduction in the incidence rate of 'high' risk discrepancies (IRR = 0.55, 95%CI = 0.31-0.96) compared to usual care. For each additional 'high' risk discrepancy at baseline, the odds of having ≥ 1 unplanned medication-related admission during a 12-month follow-up period increased by 25% (adj-OR = 1.25, 95%CI = 0.97-1.63) independently of the Child-Pugh score and a history of variceal bleeding. Among participants with complete follow-up, intervention patients were 3-fold less likely to have an unplanned medication-related admission (adj-OR = 0.27, 95%CI = 0.07-0.97) compared to usual care. There was no association between medication discrepancies and mortality. Medication regimen complexity, frequent changes to the regimen and hepatic encephalopathy were associated with discrepancies. Medication reconciliation may improve medication safety by facilitating communication between patients and clinicians about 'current' therapies and identifying potentially inappropriate medicines that may lead to harm.

Mouse hematopoietic tissues contain abundant tissue-resident macrophages that support immunity, hematopoiesis, and bone homeostasis. A systematic strategy to characterize macrophage subsets in mouse bone marrow (BM), spleen, and lymph node unexpectedly reveals that macrophage surface marker staining emanates from membrane-bound subcellular remnants associated with unrelated cells. Intact macrophages are not present within these cell preparations. The macrophage remnant binding profile reflects interactions between macrophages and other cell types in vivo. Depletion of CD169 + macrophages in vivo eliminates F4/80 + remnant attachment. Remnant-restricted macrophage-specific membrane markers, cytoplasmic fluorescent reporters, and mRNA are all detected in non-macrophage cells including isolated stem and progenitor cells. Analysis of RNA sequencing (RNA-seq) data, including publicly available datasets, indicates that macrophage fragmentation is a general phenomenon that confounds bulk and single-cell analysis of disaggregated hematopoietic tissues. Hematopoietic tissue macrophage fragmentation undermines the accuracy of macrophage ex vivo molecular profiling and creates opportunity for misattribution of macrophage-expressed genes to non-macrophage cells., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Osteal macrophages (osteomacs) support osteoblast function and promote bone anabolism, but their contribution to osteoporosis has not been explored. Although mouse ovariectomy (OVX) models have been repeatedly used, variation in strain, experimental design and assessment modalities have contributed to no single model being confirmed as comprehensively replicating the full gamut of osteoporosis pathological manifestations. We validated an OVX model in adult C3H/HeJ mice and demonstrated that it presents with human postmenopausal osteoporosis features with reduced bone volume in axial and appendicular bone and bone loss in both trabecular and cortical bone including increased cortical porosity. Bone loss was associated with increased osteoclasts on trabecular and endocortical bone and decreased osteoblasts on trabecular bone. Importantly, this OVX model was characterized by delayed fracture healing. Using this validated model, we demonstrated that osteomacs are increased post-OVX on both trabecular and endocortical bone. Dual F4/80 (pan-macrophage marker) and tartrate-resistant acid phosphatase (TRAP) staining revealed osteomacs frequently located near TRAP + osteoclasts and contained TRAP + intracellular vesicles. Using an in vivo inducible macrophage depletion model that does not simultaneously deplete osteoclasts, we observed that osteomac loss was associated with elevated extracellular TRAP in bone marrow interstitium and increased serum TRAP. Using in vitro high-resolution confocal imaging of mixed osteoclast-macrophage cultures on bone substrate, we observed macrophages juxtaposed to osteoclast basolateral functional secretory domains scavenging degraded bone byproducts. These data demonstrate a role for osteomacs in supporting osteoclastic bone resorption through phagocytosis and sequestration of resorption byproducts. Overall, our data expose a novel role for osteomacs in supporting osteoclast function and provide the first evidence of their involvement in osteoporosis pathogenesis. © 2021 American Society for Bone and Mineral Research (ASBMR)., (© 2021 American Society for Bone and Mineral Research (ASBMR).)

Background & Aims: Fibrosis, the primary cause of morbidity in chronic liver disease, is induced by pro-inflammatory cytokines, immune cell infiltrates, and tissue resident cells that drive excessive myofibroblast activation, collagen production, and tissue scarring. Rho-associated kinase 2 (ROCK2) regulates key pro-fibrotic pathways involved in both inflammatory reactions and altered extracellular matrix remodelling, implicating this pathway as a potential therapeutic target., Methods: We used the thioacetamide-induced liver fibrosis model to examine the efficacy of administration of the selective ROCK2 inhibitor KD025 to prevent or treat liver fibrosis and its impact on immune composition and function., Results: Prophylactic and therapeutic administration of KD025 effectively attenuated thioacetamide-induced liver fibrosis and promoted fibrotic regression. KD025 treatment inhibited liver macrophage tumour necrosis factor production and disrupted the macrophage niche within fibrotic septae. ROCK2 targeting in vitro directly regulated macrophage function through disruption of signal transducer and activator of transcription 3 (STAT3)/cofilin signalling pathways leading to the inhibition of pro-inflammatory cytokine production and macrophage migration. In vivo , KDO25 administration significantly reduced STAT3 phosphorylation and cofilin levels in the liver. Additionally, livers exhibited robust downregulation of immune cell infiltrates and diminished levels of retinoic acid receptor-related orphan receptor gamma (RORγt) and B-cell lymphoma 6 (Bcl6) transcription factors that correlated with a significant reduction in liver IL-17, splenic germinal centre numbers and serum IgG., Conclusions: As IL-17 and IgG-Fc binding promote pathogenic macrophage differentiation, together our data demonstrate that ROCK2 inhibition prevents and reverses liver fibrosis through direct and indirect effects on macrophage function and highlight the therapeutic potential of ROCK2 inhibition in liver fibrosis., Lay Summary: By using a clinic-ready small-molecule inhibitor, we demonstrate that selective ROCK2 inhibition prevents and reverses hepatic fibrosis through its pleiotropic effects on pro-inflammatory immune cell function. We show that ROCK2 mediates increased IL-17 production, antibody production, and macrophage dysregulation, which together drive fibrogenesis in a model of chemical-induced liver fibrosis. Therefore, in this study, we not only highlight the therapeutic potential of ROCK2 targeting in chronic liver disease but also provide previously undocumented insights into our understanding of cellular and molecular pathways driving the liver fibrosis pathology., Competing Interests: The authors declare no competing financial interests. BRB receives remuneration as an advisor to Magenta Therapeutics and BlueRock Therapeutics; received research funding from BlueRock Therapeutics, Rheos Medicines, Childrens' Cancer Research Fund, and KidsFirst Fund; and is a co-founder of Tmunity. MN, WC, and AZZ are full-time employees of Kadmon Pharmaceuticals, LLC. Please refer to the accompanying ICMJE disclosure forms for further details., (© 2021 The Authors.)

Macrophage-targeted therapies, including macrophage colony-stimulating factor 1 (CSF1), have been shown to have pro-repair impacts post-fracture. Preclinical/clinical applications of CSF1 have been expedited by development of chimeric CSF1-Fc which has extended circulating half-life. Here, we used mouse models to investigate the bone regenerative potential of CSF1-Fc in healthy and osteoporotic fracture. We also explored whether combination of CSF1-Fc with interleukin (IL)-4 provided additional fracture healing benefit in osteopenic bone. Micro-computed tomography, in situ histomorphometry, and bone mechanical parameters were used to assess systemic impacts of CSF1-Fc therapy in naive mice (male and female young, adult and geriatric). An intermittent CSF1-Fc regimen was optimized to mitigate undesirable impacts on bone resorption and hepatosplenomegaly, irrespective of age or gender. The intermittent CSF1-Fc regimen was tested in a mid-diaphyseal femoral fracture model in healthy bones with treatment initiated 1-day post-fracture. Weekly CSF1-Fc did not impact osteoclasts but increased osteal macrophages and improved fracture strength. Importantly, this treatment regimen also improved fracture union and strength in an ovariectomy-model of delayed fracture repair. Combining CSF1-Fc with IL-4 initiated 1-week post-fracture reduced the efficacy of CSF1-Fc. This study describes a novel strategy to specifically achieve bone regenerative actions of CSF1-Fc that has the potential to alleviate fragility fracture morbidity and mortality., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Homozygous mutation of the Csf1r locus (Csf1rko) in mice, rats and humans leads to multiple postnatal developmental abnormalities. To enable analysis of the mechanisms underlying the phenotypic impacts of Csf1r mutation, we bred a rat Csf1rko allele to the inbred dark agouti (DA) genetic background and to a Csf1r-mApple reporter transgene. The Csf1rko led to almost complete loss of embryonic macrophages and ablation of most adult tissue macrophage populations. We extended previous analysis of the Csf1rko phenotype to early postnatal development to reveal impacts on musculoskeletal development and proliferation and morphogenesis in multiple organs. Expression profiling of 3-week old wild-type (WT) and Csf1rko livers identified 2760 differentially expressed genes associated with the loss of macrophages, severe hypoplasia, delayed hepatocyte maturation, disrupted lipid metabolism and the IGF1/IGF binding protein system. Older Csf1rko rats developed severe hepatic steatosis. Consistent with the developmental delay in the liver Csf1rko rats had greatly-reduced circulating IGF1. Transfer of WT bone marrow (BM) cells at weaning without conditioning repopulated resident macrophages in all organs, including microglia in the brain, and reversed the mutant phenotypes enabling long term survival and fertility. WT BM transfer restored osteoclasts, eliminated osteopetrosis, restored bone marrow cellularity and architecture and reversed granulocytosis and B cell deficiency. Csf1rko rats had an elevated circulating CSF1 concentration which was rapidly reduced to WT levels following BM transfer. However, CD43hi non-classical monocytes, absent in the Csf1rko, were not rescued and bone marrow progenitors remained unresponsive to CSF1. The results demonstrate that the Csf1rko phenotype is autonomous to BM-derived cells and indicate that BM contains a progenitor of tissue macrophages distinct from hematopoietic stem cells. The model provides a unique system in which to define the pathways of development of resident tissue macrophages and their local and systemic roles in growth and organ maturation., Competing Interests: The authors have declared that no competing interests exist.

While the dire cardiometabolic consequences of the hypercaloric modern 'Western' diet are well known, there is not much information on the health impact of a high sucrose diet not inducing weight gain. Here, we tested the hypothesis that rats reared with intermittent binge access to sucrose in addition to normal chow would develop an inflammatory response in brain. To test this hypothesis, we undertook serial PET/MRI scans with the TSPO ligand [ 18 F]DPA714 in a group of (n=9) rats at baseline and again after voluntarily consuming 5% sucrose solution three days a week for three months. Compared to a control group fed with normal chow (n=9), the sucrose rats indeed showed widespread increases in the availability of cerebral binding sites for the microglial marker, despite normal weight gain compared to the control diet group. Subsequent immunofluorescence staining of the brains confirmed the PET findings, showing a widespread 20% increase in the abundance of IBA-1-positive microglia with characteristic 'semi-activated' morphology in the binge sucrose rats, which had 23% lower density of microglial endpoints and 25% lower mean process length compared to microglia in the control rats with ordinary feeding. GFAP immunofluorescence showed no difference in astroglial coverage in the sucrose rats, except for a slight reduction in hypothalamus. The binge sucrose diet-induced neuroinflammation was associated with a significant elevation of white blood cell counts. Taking these results together, we find that long-term intake of sucrose in a binge paradigm, similar in sucrose content to the contemporary Western diet, triggered a low-grade systemic and central inflammation in non-obese rats. The molecular mechanism of this phenomenon remains to be established.

The laboratory rat continues to be the model of choice for many studies of physiology, behavior, and complex human diseases. Cells of the mononuclear phagocyte system (MPS; monocytes, macrophages, and dendritic cells) are abundant residents in every tissue in the body and regulate postnatal development, homeostasis, and innate and acquired immunity. Recruitment and proliferation of MPS cells is an essential component of both initiation and resolution of inflammation. The large majority of current knowledge of MPS biology is derived from studies of inbred mice, but advances in technology and resources have eliminated many of the advantages of the mouse as a model. In this article, we review the tools available and the current state of knowledge of development, homeostasis, regulation, and diversity within the MPS of the rat., (Copyright © 2021 by The American Association of Immunologists, Inc.)

Collaborative monitoring over broad scales and levels of ecological organization can inform conservation efforts necessary to address the contemporary biodiversity crisis. An important challenge to collaborative monitoring is motivating local engagement with enough buy-in from stakeholders while providing adequate top-down direction for scientific rigor, quality control, and coordination. Collaborative monitoring must reconcile this inherent tension between top-down control and bottom-up engagement. Highly mobile and cryptic taxa, such as bats, present a particularly acute challenge. Given their scale of movement, complex life histories, and rapidly expanding threats, understanding population trends of bats requires coordinated broad-scale collaborative monitoring. The North American Bat Monitoring Program (NABat) reconciles top-down, bottom-up tension with a hierarchical master sample survey design, integrated data analysis, dynamic data curation, regional monitoring hubs, and knowledge delivery through web-based infrastructure. NABat supports collaborative monitoring across spatial and organizational scales and the full annual lifecycle of bats.

Mutations in the human CSF1R gene have been associated with dominant and recessive forms of neurodegenerative disease. Here we describe the impacts of Csf1r mutation in the rat on development of the brain. Diffusion imaging indicated small reductions in major fiber tracts that may be associated in part with ventricular enlargement. RNA-seq profiling revealed a set of 105 microglial markers depleted in all brain regions of the Csf1rko rats. There was no evidence of region or sex-specific expression of microglia-associated transcripts. Other than the microglial signature, Csf1rko had no effect on any neuronal or region-specific transcript cluster. Expression of markers of oligodendrocytes, astrocytes, dopaminergic neurons and Purkinje cells was minimally affected. However, there were defects in dendritic arborization of doublecortin-positive neurogenic precursors and expression of poly-sialylated neural cell adhesion molecule (PS-NCAM) in the dentate gyrus of the hippocampus. Heterozygous Csf1rko rats had no detectable brain phenotype. We conclude that most brain developmental processes occur normally in the absence of microglia and that CSF1R haploinsufficiency is unlikely to cause leukoencephalopathy., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Macrophage colony-stimulating factor (CSF1) is the primary growth factor required for the control of monocyte and macrophage differentiation, survival, proliferation and renewal. Although the cDNAs encoding multiple isoforms of human CSF1 were cloned in the 1980s, and recombinant proteins were available for testing in humans, CSF1 has not yet found substantial clinical application. Here we present an overview of CSF1 biology, including evolution, regulation and functions of cell surface and secreted isoforms. CSF1 is widely-expressed, primarily by cells of mesenchymal lineages, in all mouse tissues. Cell-specific deletion of a floxed Csf1 allele in mice indicates that local CSF1 production contributes to the maintenance of tissue-specific macrophage populations but is not saturating. CSF1 in the circulation is controlled primarily by receptor-mediated clearance by macrophages in liver and spleen. Administration of recombinant CSF1 to humans or animals leads to monocytosis and expansion of tissue macrophage populations and growth of the liver and spleen. In a wide variety of tissue injury models, CSF1 administration promotes monocyte infiltration, clearance of damaged cells and repair. We suggest that CSF1 has therapeutic potential in regenerative medicine., (Copyright © 2021. Published by Elsevier Ltd.)

Non-alcoholic fatty liver disease (NAFLD) affects 25% of the adult population globally. Since liver fibrosis is the most important predictor of liver-related complications in patients with NAFLD, identification of patients with advanced fibrosis among at-risk individuals is an important issue in clinical practice. Transient elastography is the best evaluated non-invasive method used in referral centres to assess liver fibrosis, however serum-based tests, such as the Enhanced Liver Fibrosis (ELF) score, have a practical advantage as first-line tests due to their wider availability and lower cost. We previously identified matrix metalloproteinase 7 (MMP7) as a serum biomarker of histological advanced fibrosis in a mixed-etiology patient cohort. In this study we aimed to determine the association between MMP7 and fibrosis, assessed by transient elastography, in patients with NAFLD. Serum MMP7 levels were measured in a cohort of 228 patients with NAFLD. Associations between MMP7, liver stiffness measurement (LSM), ELF score and clinical parameters were determined using logistic regression modelling. Serum MMP7 was associated with clinically significant fibrosis (LSM ≥ 8.2), independent of age, gender, BMI and diabetes. The addition of MMP7 significantly improved the diagnostic performance of the ELF test, particularly in patients over the age of 60. Combinations of serum biomarkers have the potential to improve the sensitivity and specificity of detection of advanced fibrosis in at-risk patients with NAFLD. We have demonstrated that serum MMP7 is independently associated with clinically significant fibrosis and improves the diagnostic performance of currently available tests in older patients.

The laboratory rat is widely used as a model for human diseases. Many of these diseases involve monocytes and tissue macrophages in different states of activation. Whilst methods for in vitro differentiation of mouse macrophages from embryonic stem cells (ESC) and bone marrow (BM) are well established, these are lacking for the rat. The gene expression profiles of rat macrophages have also not been characterised to the same extent as mouse. We have established the methodology for production of rat ESC-derived macrophages and compared their gene expression profiles to macrophages obtained from the lung and peritoneal cavity and those differentiated from BM and blood monocytes. We determined the gene signature of Kupffer cells in the liver using rats deficient in macrophage colony stimulating factor receptor (CSF1R). We also examined the response of BM-derived macrophages to lipopolysaccharide (LPS). The results indicate that many, but not all, tissue-specific adaptations observed in mice are conserved in the rat. Importantly, we show that unlike mice, rat macrophages express the CSF1R ligand, colony stimulating factor 1 (CSF1)., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Pridans, Irvine, Davis, Lefevre, Bush and Hume.)

The proliferation, differentiation, and survival of cells of the mononuclear phagocyte system (MPS; progenitors, monocytes, macrophages, and classical dendritic cells) are controlled by signals from the M-CSF receptor (CSF1R). Cells of the MPS lineage have been identified using numerous surface markers and transgenic reporters, but none is both universal and lineage restricted. In this article, we report the development and characterization of a CSF1R reporter mouse. A FusionRed (FRed) cassette was inserted in-frame with the C terminus of CSF1R, separated by a T2A-cleavable linker. The insertion had no effect of CSF1R expression or function. CSF1R-FRed was expressed in monocytes and macrophages and absent from granulocytes and lymphocytes. In bone marrow, CSF1R-FRed was absent in lineage-negative hematopoietic stem cells, arguing against a direct role for CSF1R in myeloid lineage commitment. It was highly expressed in marrow monocytes and common myeloid progenitors but significantly lower in granulocyte-macrophage progenitors. In sections of bone marrow, CSF1R-FRed was also detected in osteoclasts, CD169 + resident macrophages, and, consistent with previous mRNA analysis, in megakaryocytes. In lymphoid tissues, CSF1R-FRed highlighted diverse MPS populations, including classical dendritic cells. Whole mount imaging of nonlymphoid tissues in mice with combined CSF1R-FRed/ Csf1r -EGFP confirmed the restriction of CSF1R expression to MPS cells. The two markers highlight the remarkable abundance and regular distribution of tissue MPS cells, including novel macrophage populations within tendon and skeletal muscle and underlying the mesothelial/serosal/capsular surfaces of every major organ. The CSF1R-FRed mouse provides a novel reporter with exquisite specificity for cells of the MPS., (Copyright © 2020 by The American Association of Immunologists, Inc.)