Loss of the scavenger receptor MARCO results in uncontrolled vomocytosis of fungi from macrophages

Vomocytosis, also known as nonlytic exocytosis, is a process whereby fully phagocytosed microbes are expelled from phagocytes without discernible damage to either the phagocyte or microbe. Although this phenomenon was first described in the opportunistic fungal pathogen Cryptococcus neoformans in 2006, to date, mechanistic studies have been hampered by an inability to reliably stimulate or inhibit vomocytosis. Here we present the fortuitous discovery that macrophages lacking the scavenger receptor MAcrophage Receptor with COllagenous domain (MARCO), exhibit near-total vomocytosis of internalised cryptococci within a few hours of infection. Marco-/- macrophages also showed elevated vomocytosis of a yeast-locked C. albicans strain, suggesting this to be a broadly relevant observation. We go on to show that MARCO's role in modulating vomocytosis is independent of its role as a phagocytic receptor, suggesting that this protein may play an important and hitherto unrecognised role in modulating macrophage behaviour.

Animal board invited review: The contribution of red meat to adult nutrition and health beyond protein

Red meat has been a critical part of human diets for millennia, providing a source of high-quality protein, micronutrients and essential fatty acids. However, as societies evolved and industrialisation reshaped our food systems, there has been a noticeable shift in meat-eating trends driven by concerns about the environmental impact of meat production and its potential risk to health. Yet, despite falling out of favour with some dietary experts and influencers, meat has an important role in a healthy diet and most adults still consume it. This article explores the nutritional value of red meat, authorised nutrition and health claims, how red meat fits into diet, providing the example of the United Kingdom (UK), and the health benefits and risks associated with both eating and avoiding red meat. Benefits of red meat include nutrient density and bioavailability while risks include colorectal cancer at high intakes of processed meats, based on observational studies. Benefits of meat-free diets include a lower risk of chronic diseases, based on observational studies, while risks include nutrient inadequacy, higher bone fracture risk and low protein quality. Hence, a wholesale shift to plant-based diets may not benefit adults who are vulnerable to sub-optimal nutrient intakes, such as women of child-bearing age and the elderly. More evidence from randomised controlled trials is recommended to fully understand the benefits and risks of both meat-containing and meat-free diets.

Pacemaker-lead-associated thrombosis in dogs: a multicenter retrospective study

INTRODUCTION

Pacemaker implantation is the treatment of choice for clinically relevant bradyarrhythmias. Pacemaker-lead-associated thrombosis (PLAT) occurs in 23.0-45.0% of people with permanent transvenous pacemakers. Serious thromboembolic complications are reported in 0.6-3.5%. The incidence of PLAT in dogs is unknown.

ANIMALS, MATERIALS AND METHODS

multicenter retrospective study of seven centers with 606 client-owned dogs undergoing permanent pacemaker implantation between 2012 and 2019. 260 dogs with a transvenous pacemaker with echocardiographic follow-up, 268 dogs with a transvenous pacemaker without echocardiographic follow-up and 78 dogs with an epicardial pacemaker.

RESULTS

10.4% (27/260) of dogs with transvenous pacemakers and echocardiographic follow-up had PLAT identified. The median time to diagnosis was 175 days (6-1853 days). Pacemaker-lead-associated thrombosis was an incidental finding in 15/27 (55.6%) dogs. Of dogs with a urine protein:creatinine ratio measured at pacemaker implantation, dogs with PLAT were more likely to have proteinuria at pacemaker implantation vs. dogs without PLAT (6/6 (100.0%) vs. 21/52 (40.4%), P=0.007). Urine protein:creatinine ratio was measured in 12/27 (44.4%) dogs at PLAT diagnosis, with proteinuria identified in 10/12 (83.3%) dogs. Anti-thrombotic drugs were used following the identification of PLAT in 22/27 (81.5%) dogs. The thrombus resolved in 9/15 (60.0%) dogs in which follow-up echocardiography was performed. Dogs with PLAT had shorter survival times from implantation compared to those without PLAT (677 days [9-1988 days] vs. 1105 days [1-2661 days], P=0.003).

CONCLUSIONS

Pacemaker-lead-associated thrombosis is identified in 10.4% (27/260) of dogs following transvenous pacing, is associated with proteinuria, can cause significant morbidity, and is associated with reduced survival times.

Toll-like receptor 4 and macrophage scavenger receptor 1 crosstalk regulates phagocytosis of a fungal pathogen

The opportunistic fungal pathogen Cryptococcus neoformans causes lethal infections in immunocompromised patients. Macrophages are central to the host response to cryptococci; however, it is unclear how C. neoformans is recognised and phagocytosed by macrophages. Here we investigate the role of TLR4 in the non-opsonic phagocytosis of C. neoformans. We find that loss of TLR4 function unexpectedly increases phagocytosis of non-opsonised cryptococci by murine and human macrophages. The increased phagocytosis observed in Tlr4-/- cells was dampened by pre-treatment of macrophages with oxidised-LDL, a known ligand of scavenger receptors. The scavenger receptor, macrophage scavenger receptor 1 (MSR1) (also known as SR-A1 or CD204) was upregulated in Tlr4-/- macrophages. Genetic ablation of MSR1 resulted in a 75% decrease in phagocytosis of non-opsonised cryptococci, strongly suggesting that it is a key non-opsonic receptor for this pathogen. We go on to show that MSR1-mediated uptake likely involves the formation of a multimolecular signalling complex involving FcγR leading to SYK, PI3K, p38 and ERK1/2 activation to drive actin remodelling and phagocytosis. Altogether, our data indicate a hitherto unidentified role for TLR4/MSR1 crosstalk in the non-opsonic phagocytosis of C. neoformans.

Single-centre experience with peptide receptor radionuclide therapy for neuroendocrine tumours (NETs): results using a theranostic molecular imaging-guided approach

AIM

To summarise our centre's experience managing patients with neuroendocrine tumours (NETs) in the first 5 years after the introduction of peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-octreotate (LUTATE). The report emphasises aspects of the patient management related to functional imaging and use of radionuclide therapy.

METHODS

We describe the criteria for treatment with LUTATE at our centre, the methodology for patient selection, and the results of an audit of clinical measures, imaging results and patient-reported outcomes. Subjects are treated initially with four cycles of ~ 8 GBq of LUTATE administered as an outpatient every 8 weeks.

RESULTS

In the first 5 years offering LUTATE, we treated 143 individuals with a variety of NETs of which approx. 70% were gastroentero-pancreatic in origin (small bowel: 42%, pancreas: 28%). Males and females were equally represented. Mean age at first treatment with LUTATE was 61 ± 13 years with range 28-87 years. The radiation dose to the organs considered most at risk, the kidneys, averaged 10.6 ± 4.0 Gy in total. Median overall survival (OS) from first receiving LUTATE was 72.5 months with a median progression-free survival (PFS) of 32.3 months. No evidence of renal toxicity was seen. The major long-term complication seen was myelodysplastic syndrome (MDS) with a 5% incidence.

CONCLUSIONS

LUTATE treatment for NETs is a safe and effective treatment. Our approach relies heavily on functional and morphological imaging informing the multidisciplinary team of NET specialists to guide appropriate therapy, which we suggest has contributed to the favourable outcomes seen.

Proteinase 3 promotes formation of multinucleated giant cells and granuloma-like structures in patients with granulomatosis with polyangiitis

OBJECTIVES

Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are autoimmune vasculitides associated with antineutrophil cytoplasm antibodies that target proteinase 3 (PR3) or myeloperoxidase (MPO) found within neutrophils and monocytes. Granulomas are exclusively found in GPA and form around multinucleated giant cells (MGCs), at sites of microabscesses, containing apoptotic and necrotic neutrophils. Since patients with GPA have augmented neutrophil PR3 expression, and PR3-expressing apoptotic cells frustrate macrophage phagocytosis and cellular clearance, we investigated the role of PR3 in stimulating giant cell and granuloma formation.

METHODS

We stimulated purified monocytes and whole peripheral blood mononuclear cells (PBMCs) from patients with GPA, patients with MPA or healthy controls with PR3 or MPO and visualised MGC and granuloma-like structure formation using light, confocal and electron microscopy, as well as measuring the cell cytokine production. We investigated the expression of PR3 binding partners on monocytes and tested the impact of their inhibition. Finally, we injected zebrafish with PR3 and characterised granuloma formation in a novel animal model.

RESULTS

In vitro, PR3 promoted monocyte-derived MGC formation using cells from patients with GPA but not from patients with MPA, and this was dependent on soluble interleukin 6 (IL-6), as well as monocyte MAC-1 and protease-activated receptor-2, found to be overexpressed in the cells of patients with GPA. PBMCs stimulated by PR3 formed granuloma-like structures with central MGC surrounded by T cells. This effect of PR3 was confirmed in vivo using zebrafish and was inhibited by niclosamide, a IL-6-STAT3 pathway inhibitor.

CONCLUSIONS

These data provide a mechanistic basis for granuloma formation in GPA and a rationale for novel therapeutic approaches.

Microglia states and nomenclature: A field at its crossroads

Microglial research has advanced considerably in recent decades yet has been constrained by a rolling series of dichotomies such as "resting versus activated" and "M1 versus M2." This dualistic classification of good or bad microglia is inconsistent with the wide repertoire of microglial states and functions in development, plasticity, aging, and diseases that were elucidated in recent years. New designations continuously arising in an attempt to describe the different microglial states, notably defined using transcriptomics and proteomics, may easily lead to a misleading, although unintentional, coupling of categories and functions. To address these issues, we assembled a group of multidisciplinary experts to discuss our current understanding of microglial states as a dynamic concept and the importance of addressing microglial function. Here, we provide a conceptual framework and recommendations on the use of microglial nomenclature for researchers, reviewers, and editors, which will serve as the foundations for a future white paper.

GPR97 triggers inflammatory processes in human neutrophils via a macromolecular complex upstream of PAR2 activation

Neutrophils play essential anti-microbial and inflammatory roles in host defense, however, their activities require tight regulation as dysfunction often leads to detrimental inflammatory and autoimmune diseases. Here we show that the adhesion molecule GPR97 allosterically activates CD177-associated membrane proteinase 3 (mPR3), and in conjugation with several protein interaction partners leads to neutrophil activation in humans. Crystallographic and deletion analysis of the GPR97 extracellular region identified two independent mPR3-binding domains. Mechanistically, the efficient binding and activation of mPR3 by GPR97 requires the macromolecular CD177/GPR97/PAR2/CD16b complex and induces the activation of PAR2, a G protein-coupled receptor known for its function in inflammation. Triggering PAR2 by the upstream complex leads to strong inflammatory activation, prompting anti-microbial activities and endothelial dysfunction. The role of the complex in pathologic inflammation is underscored by the finding that both GPR97 and mPR3 are upregulated on the surface of disease-associated neutrophils. In summary, we identify a PAR2 activation mechanism that directs neutrophil activation, and thus inflammation. The PR3/CD177/GPR97/PAR2/CD16b protein complex, therefore, represents a potential therapeutic target for neutrophil-mediated inflammatory diseases.

Effects of recording device, body position, electrode placement, and sedation on electrocardiogram intervals in dogs

Selected electrocardiograph (ECG) intervals may be useful when incorporated into prediction models for cardiac risk assessment in dogs. Standard recommendations for ECG acquisition may not be adhered to in practice. Study objectives were to compare duration of P, PR, QRS, QT, and R wave peak time intervals in: (1) lead II ECGs vs. single lead precordial ECGs in conscious dogs; (2) lead II ECGs with electrodes placed in proximal limb (PL) vs. distal limb (DL) positions with dogs in right lateral (RL) recumbency, left lateral (LL) recumbency and standing positions; (3) single lead precordial ECGs from dogs in RL, LL and standing positions; and (4) before and after sedation with butorphanol in lead II ECGs obtained in RL recumbency. All intervals could be measured in all dogs (conscious and sedated) from a RL lead II ECG with both PL and DL electrode positioning. This was reduced to 98% for lead II ECGs with dogs in LL and standing positions. Intervals that were not different regardless of recording device, dog position, electrode limb position or sedation included P, QRS and P+QRS, suggesting that these intervals have the greatest clinical utility across a variety of recording conditions. The main impact of positioning in healthy dogs was the lack of ability to consistently measure all intervals in standing dogs, particularly P wave duration. Further investigation is needed to determine if this is applicable to dogs with cardiac disease.

Polygenic risk score as a determinant of risk of keratinocyte cancer in an Australian population-based cohort

BACKGROUND

Keratinocyte cancer (KC) risk is determined by genetic and environmental factors. Genetic risk can be quantified by polygenic risk scores (PRS), which sum the combined effects of single nucleotide polymorphisms (SNPs).

OBJECTIVES

Our objective here was to evaluate the contribution of the summed genetic score to predict the KC risk in the phenotypically well-characterised Nambour population.

METHODS

We used PLINK v1.90 to calculate PRS for 432 cases, 566 controls, using 78 genome-wide independent SNPs that are associated with KC risk. We assessed the association between PRS and KC using logistic regression, stratifying the cohort into 3 risk groups (high 20%, intermediate 60%, low 20%).

RESULTS

The fully adjusted model including traditional risk factors (phenotypic and sun exposure-related), showed a significant 50% increase in odds of KC per standard deviation of PRS (odds ratio (OR) =1.51; 95% confidence interval (CI) =1.30-1.76, P=5.75 × 10^-8 ). Those in the top 20% PRS had over three times the risk of KC of those in the lowest 20% (OR=3.45; 95% CI=2.18-5.50, P=1.5×10^-7 ) and higher absolute risk of KC per 100 person-years of 2.96 compared with 1.34. Area under the ROC curve increased from 0.72 to 0.74 on adding PRS to the fully adjusted model.

CONCLUSIONS

These results show that PRS can enhance the prediction of KC above traditional risk factors.

POS0707 POTENTIAL USE OF BELIMUMAB IN LUPUS PATIENTS FROM ARGENTINE COHORT ACCORDING DISEASE ACTIVITY STATE

Background

The goal of targeted treatment in patients with Systemic Lupus Erythematosus (SLE) is to achieve clinical remission or low disease activity, with the best quality of life, low damage rates and better survival 1-4. RELESSAR is a multicenter, cross-sectional study registry of ≥18 years SLE (ACR 97) patients 5.

Objectives

To describe demographic, clinical characteristics and treatments in SLE patients according to disease activity state. To evaluate the proportion of SLE and refractory SLE patients that are potentially candidates for Belimumab treatment (Active SLE despite standard treatment including increased acDNA autoantibodies and low complement).

Methods

We evaluated demographic and clinical data, treatments, score of damage (SLICC), activity (SLEDAI) and comorbidity (Charlson), hospital admissions and severe infections. The patients were compared according to disease activity: remission (SLEDAI = 0 and without corticosteroids), low disease activity (LDA, SLEDAI> 0 and ≤4 and without corticosteroids) and non-optimal control (SLEDAI> 4 and any dose of corticosteroids). Refractory SLE was defined according to Rituximab (RTX) use, non-response to cyclophosphamide or two or more immunosuppressant or splenectomized patients. Potential use of Belimumab according approved prescription in Argentina was analyzed.

Results

Overall, 1277 patients were analyzed: 299 (23.4%) were in remission, 162 (12.7%) in LDA and 816 (63.9%) with non-optimal control of the disease.

Patients in non-optimal control group were younger, less frequently female and they showed less time of disease and lower socioeconomic status (p < 0.001). They were also more prevalent mestizos (p= 0.004), had higher SLEDAI and SLICC indexes (p <0.001) and higher use of immunosuppressant therapy (p <0.001). There was no difference regarding biologic treatment (RTX p= 0.547 and Belimumab p= 0.08). This group had higher proportion of hospital admissions and severe infections (p<0.001, respectively).

Two hundred and one SLE patients fulfilled the use of Belimumab prescription criteria but only 45/201 patients (22,3%) received it in the last visit. Malar rash was the only clinical variable associated with the use of Belimumab (72.7% vs 29.8% p= 0.005).

Seventy-six patients classified as refractory SLE (15.7%) and 56/76 (75.7%) never received Belimumab. Patients on Belimumab therapy were associated to treatment with lower doses of corticoids (p= 0.018) and lower rate of hospital admission caused by SLE flare (p= 0.027).

Conclusion

A high percentage of patients had uncontrolled disease upon entry into the registry and were potential candidates for treatment with Belimumab. The patients who received biologic treatment showed the benefit of requiring fewer doses of corticosteroids and having a lower rate of hospitalizations.

References

[1]Mok CC. Treat-to-target in systemic lupus erythematosus: Are we there yet? Expert Rev Clin Pharmacol. 2016;9(5).

[2]Morand EF, Mosca M. Treat to target, remission and low disease activity in SLE. Vol. 31, Best Practice and Research: Clinical Rheumatology. 2017.

[3]Golder V, Tsang-A-Sjoe MWP. Treatment targets in SLE: Remission and low disease activity state. Rheumatol (United Kingdom). 2020;59.

[4]Ruiz-Irastorza G, Bertsias G. Treating systemic lupus erythematosus in the 21st century: new drugs and new perspectives on old drugs. Vol. 59, Rheumatology (United Kingdom). 2021.

[5]Hochberg MC. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum [Internet]. 1997;40(9):1725. Available from: http://www.ncbi.nlm.nih.gov/pubmed/9324032

Disclosure of Interests

Rosana Quintana: None declared, Lucila Garcia: None declared, Paula Alba: None declared, Susana Roverano: None declared, Analia Alvarez: None declared, Cesar Graf: None declared, Cecilia Pisoni: None declared, Alberto Spindler: None declared, Catalina Gomez: None declared, Heber Matias Figueredo: None declared, Silvia Papasidero: None declared, Raul Horacio Paniego: None declared, Maria DeLaVega: None declared, Emma Estela Civit De Garignani: None declared, Luciana Gonzalez Lucero: None declared, Victoria Martire: None declared, Rodrigo Águila Maldonado: None declared, Sergio Gordon: None declared, Carla Gobbi: None declared, Romina Nieto: None declared, Gretel Rausch: None declared, Vanina Góngora: None declared, Maria Agustina D´Amico: None declared, Diana Dubinsky: None declared, Alberto Omar Orden: None declared, Johana Zacariaz: None declared, Julia Romero: None declared, Mariana Alejandra Pera: None declared, Oscar Rillo: None declared, Roberto Baez: None declared, Valeria Arturi: None declared, Andrea Gonzalez: None declared, Florencia Vivero: None declared, Marcela Schmid: None declared, Victor Caputo: None declared, Maria Silvia Larroude: None declared, Graciela Gomez: None declared, Graciela Rodriguez: None declared, Josefina Marin: None declared, Maria Victoria Collado: None declared, Marisa Jorfen: None declared, Zaida Bedran: None declared, Judith Sarano: None declared, David Zelaya: None declared, MONICA SACNUN: None declared, Pablo Finucci: None declared, Romina Rojas Tessel: None declared, Maria Emilia Sattler: None declared, MAXIMILIANO MACHADO ESCOBAR: None declared, Pablo Astesana: None declared, Ursula Vanesa Paris: None declared, Alberto Allievi: None declared, Juan Manuel Vandale: None declared, Bernardo Pons-Estel: None declared, Guillermo Pons-Estel: None declared, Mercedes García Grant/research support from: GSK grant

Foam Cell Macrophages in Tuberculosis

Mycobacterium tuberculosis infects primarily macrophages in the lungs. Infected macrophages are surrounded by other immune cells in well organised structures called granulomata. As part of the response to TB, a type of macrophage loaded with lipid droplets arises which we call Foam cell macrophages. They are macrophages filled with lipid laden droplets, which are synthesised in response to increased uptake of extracellular lipids, metabolic changes and infection itself. They share the appearance with atherosclerosis foam cells, but their lipid contents and roles are different. In fact, lipid droplets are immune and metabolic organelles with emerging roles in Tuberculosis. Here we discuss lipid droplet and foam cell formation, evidence regarding the inflammatory and immune properties of foam cells in TB, and address gaps in our knowledge to guide further research.

SARS-CoV-2 Variants, Vaccines, and Host Immunity

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new beta coronavirus that emerged at the end of 2019 in the Hubei province of China. SARS-CoV-2 causes coronavirus disease 2019 (COVID-19) and was declared a pandemic by the World Health Organization (WHO) on 11 March 2020. Herd or community immunity has been proposed as a strategy to protect the vulnerable, and can be established through immunity from past infection or vaccination. Whether SARS-CoV-2 infection results in the development of a reservoir of resilient memory cells is under investigation. Vaccines have been developed at an unprecedented rate and 7 408 870 760 vaccine doses have been administered worldwide. Recently emerged SARS-CoV-2 variants are more transmissible with a reduced sensitivity to immune mechanisms. This is due to the presence of amino acid substitutions in the spike protein, which confer a selective advantage. The emergence of variants therefore poses a risk for vaccine effectiveness and long-term immunity, and it is crucial therefore to determine the effectiveness of vaccines against currently circulating variants. Here we review both SARS-CoV-2-induced host immune activation and vaccine-induced immune responses, highlighting the responses of immune memory cells that are key indicators of host immunity. We further discuss how variants emerge and the currently circulating variants of concern (VOC), with particular focus on implications for vaccine effectiveness. Finally, we describe new antibody treatments and future vaccine approaches that will be important as we navigate through the COVID-19 pandemic.

Lipid-loaded tumor-associated macrophages sustain tumor growth and invasiveness in prostate cancer

Tumor-associated macrophages (TAMs) are correlated with the progression of prostatic adenocarcinoma (PCa). The mechanistic basis of this correlation and therapeutic strategies to target TAMs in PCa remain poorly defined. Here, single-cell RNA sequencing was used to profile the transcriptional landscape of TAMs in human PCa, leading to identification of a subset of macrophages characterized by dysregulation in transcriptional pathways associated with lipid metabolism. This subset of TAMs correlates positively with PCa progression and shorter disease-free survival and is characterized by an accumulation of lipids that is dependent on Marco. Mechanistically, cancer cell–derived IL-1β enhances Marco expression on macrophages, and reciprocally, cancer cell migration is promoted by CCL6 released by lipid-loaded TAMs. Moreover, administration of a high-fat diet to tumor-bearing mice raises the abundance of lipid-loaded TAMs. Finally, targeting lipid accumulation by Marco blockade hinders tumor growth and invasiveness and improves the efficacy of chemotherapy in models of PCa, pointing to combinatorial strategies that may influence patient outcomes.

Non-cardiogenic pulmonary oedema complicating balloon valvuloplasty and stent angioplasty of severe pulmonary valve stenosis in four dogs

In dogs, balloon valvuloplasty is considered the treatment of choice for severe pulmonary valve stenosis, and this technique is currently performed routinely in specialist referral practices with low morbidity and mortality. Stent angioplasty has also been recently proposed as a viable treatment option. The present case series describes the clinical course of four dogs with severe pulmonary valve stenosis, treated with balloon valvuloplasty or stent angioplasty at four different institutions, which developed non-cardiogenic pulmonary oedema perioperatively after apparently successful dilation of the pulmonary valve. In three cases, there was evidence of some degree of pulmonary hypertension before ballooning. Despite intensive care, the complication proved fatal in three cases. Clinicians should therefore be aware of this life-threatening complication, previously undescribed in dogs.

COVID-19 Is a Multi-Organ Aggressor: Epigenetic and Clinical Marks

The progression of coronavirus disease 2019 (COVID-19), resulting from a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, may be influenced by both genetic and environmental factors. Several viruses hijack the host genome machinery for their own advantage and survival, and similar phenomena might occur upon SARS-CoV-2 infection. Severe cases of COVID-19 may be driven by metabolic and epigenetic driven mechanisms, including DNA methylation and histone/chromatin alterations. These epigenetic phenomena may respond to enhanced viral replication and mediate persistent long-term infection and clinical phenotypes associated with severe COVID-19 cases and fatalities. Understanding the epigenetic events involved, and their clinical significance, may provide novel insights valuable for the therapeutic control and management of the COVID-19 pandemic. This review highlights different epigenetic marks potentially associated with COVID-19 development, clinical manifestation, and progression.

Remembering Metchnikoff in the time of COVID-19

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CSF1R defines the mononuclear phagocyte system lineage in human blood in health and COVID-19

Mononuclear phagocytes defend tissues, present antigens, and mediate recovery and healing. To date, we lack a marker to unify mononuclear phagocytes in humans or that informs us about their origin. Here, we reassess mononuclear phagocyte ontogeny in human blood through the lineage receptor CSF1R, in the steady state and in COVID-19. We define CSF1R as the first sensitive and reproducible pan-phagocyte lineage marker, to identify and enumerate all conventional monocytes, and the myeloid dendritic cells. In the steady state, CSF1R is sufficient for sorting and immuno-magnetic isolation. In pathology, changes in CSF1R are more sensitive than CD14 and CD16. In COVID-19, a significant drop in membrane CSF1R is useful for stratifying patients, beyond the power of cell categories published thus far, which fail to capture COVID-19 specific events. Importantly, CSF1R defines cells which are neither conventional monocytes nor DCs, which are missed in published analysis. CSF1R decrease can be linked ex vivo to high CSF1 levels. Blood assessment of CSF1R+ cells opens a developmental window to the Mononuclear Phagocyte System in transit from bone marrow to tissues, supports isolation and phenotypic characterisation, identifies novel cell types, and singles out CSF1R inhibition as therapeutic target in COVID-19 and other diseases.

Stimulation of Vibratory Urticaria-Associated Adhesion-GPCR, EMR2/ADGRE2, Triggers the NLRP3 Inflammasome Activation Signal in Human Monocytes

EMR2/ADGRE2 is an adhesion G protein-coupled receptor differentially expressed by human myeloid cells. It modulates diverse cellular functions of innate immune cells and a missense EMR2 variant is directly responsible for vibratory urticaria. Recently, EMR2 was found to activate NLRP3 inflammasome in monocytes via interaction with FHR1, a regulatory protein of complement Factor H. However, the functional involvement of EMR2 activation and its signaling mechanisms in eliciting NLRP3 inflammasome activation remain elusive. In this study, we show that EMR2-mediated signaling plays a critical role in triggering the activation (2^nd) signal for the NLRP3 inflammasome in both THP-1 monocytic cell line and primary monocytes. Stimulation of EMR2 by its agonistic 2A1 monoclonal antibody elicits a Gα₁₆-dependent PLC-β activation pathway, inducing the activity of downstream Akt, MAPK, NF-κB, and Ca²⁺ mobilization, eventually leading to K⁺ efflux. These results identify EMR2 and its associated signaling intermediates as potential intervention targets of NLRP3 inflammasome activation in inflammatory disorders.

A Multicenter Study of the Clinical Utility of Nontargeted Systematic Transperineal Prostate Biopsies in Patients Undergoing Pre-Biopsy Multiparametric Magnetic Resonance Imaging

PURPOSE

The added value of nontargeted systematic prostate biopsies when performed alongside magnetic resonance imaging targeted biopsies in men referred with a suspicion of prostate cancer is unclear. We aimed to determine the clinical utility of transperineal nontargeted systematic prostate biopsies, when performed alongside targeted systematic prostate biopsies, using pre-biopsy multiparametric magnetic resonance imaging.

MATERIALS AND METHODS

Consecutive patients referred with a suspicion of prostate cancer (April 2017 to October 2019) underwent pre-biopsy multiparametric magnetic resonance imaging. A transperineal biopsy was advised if multiparametric magnetic resonance imaging PI-RADS® (v.2.0) score was 4 or 5, and score 3 required a prostate specific antigen density 0.12 ng/ml or greater. Primary threshold for clinically significant prostate cancer was defined as any Gleason 3+4 or greater. Multivariable logistic regression analysis identified pre-biopsy predictors of clinically significant prostate cancer in nontargeted systematic prostate biopsies, regardless of targeted pathology (p <0.05, R, version 3.5.1).

RESULTS

A total of 1,719 men underwent a pre-biopsy multiparametric magnetic resonance imaging, with 679 (39.5%) proceeding to combined targeted systematic prostate biopsies and nontargeted systematic prostate biopsies. In these men clinically significant prostate cancer was detected in 333 (49%) and 139 (20.5%) with targeted systematic prostate biopsies and nontargeted systematic prostate biopsies, respectively. In those men with clinically significant prostate cancer in targeted systematic prostate biopsies, clinically significant prostate cancer was also present in nontargeted systematic prostate biopsies in 117 (17.2%); Gleason 3+3 was present in 50 (7.4%). In 287 men without any cancer in the targeted systematic prostate biopsies, 13 (1.9%) had clinically significant prostate cancer in nontargeted systematic prostate biopsies. In addition 18/679 (2.7%) had Gleason 3+3 disease and no Gleason greater than 4+3 was detected. Predictors associated with clinically significant prostate cancer in nontargeted systematic prostate biopsies were prostate specific antigen 5 ng/ml or greater (OR 2.05, 95% CI 1.13-3.73, p=0.02), PI-RADS score 5 (OR 2.26, 95% CI 1.51-3.38, p <0.001) and prostate volume less than 50 cc (OR 2.47, 95% CI 1.57-3.87, p <0.001).

CONCLUSIONS

Detection of clinically significant prostate cancer in exclusively nontargeted transperineal systematic biopsies in a pre-biopsy multiparametric magnetic resonance imaging pathway was low (1.9%).

Meta-analysis of computed tomography and magnetic resonance imaging for diagnosing mycotic aneurysms

Background

Mycotic aneurysms are a serious complication of infective endocarditis and bloodstream infection with high mortality and morbidity. Computed tomography (CT) and magnetic resonance (MRI) play major roles in detecting mycotic aneurysms, but their accuracy is not well established warranting this meta-analysis.

Purpose

We aimed to assess the diagnostic performance of CT and MRI for mycotic aneurysms in this meta-analysis.

Methods

Pubmed, Cochrane and Embase were searched from 1 January 1980–30 June 2019 for diagnostic studies reporting both sensitivity and specificity of CT and/or MRI for detecting mycotic aneurysms, and pooled using random effects models and Meta-DiSc 1.4 software.

Results

Amongst 1507 articles searched, 15 studies with 622 scans for 249 mycotic aneurysms included. CT was performed in 13 studies and MRI in 5 studies, looking at aortic and cerebral mycotic aneurysm in 12 and 3 studies respectively. The pooled sensitivities and specificities for all mycotic aneurysms with 95% confidence intervals were for CT 0.82 (0.77–0.87) and 0.93 (0.89–0.95) respectively, and for MRI 0.79 (0.61–0.91) and 0.89 (0.81–0.95) (Figure). CT or MRI had pooled sensitivities and specificities of 0.84 (0.78–0.89) and 0.92 (0.89–0.95) for aortic and 0.71 (0.54–0.85) and 0.90 (0.83–0.95) for cerebral mycotic aneurysms. Heterogeneity and publication bias was observed in some pooled analysis.

Conclusion

CT and MRI had moderately high diagnostic accuracy for mycotic aneurysms. Sensitivity was numerically higher for detecting aortic than cerebral mycotic aneurysms, with similar specificity. Study heterogeneity, publication bias and modest sample size from the literature were important limitations, warranting larger and higher quality studies.

Forrest plots for CT and MRI pooled data

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): National Heart Foundation of New Zealand - Overseas Clinical and Research Fellowship

Corrigendum: Foam Cells Control Mycobacterium tuberculosis Infection

[This corrects the article DOI: 10.3389/fmicb.2020.01394.].

Monocyte activation in systemic Covid-19 infection: Assay and rationale

Mononuclear phagocytes are a widely distributed family of cells contributing to innate and adaptive immunity. Circulating monocytes and tissue macrophages participate in all stages of SARS COVID-19. They contribute to comorbidities predisposing to clinical infection, virus resistance and dissemination, and to host factors that determine disease severity, recovery and sequelae. Assays are available to detect viral infection and antibody responses, but no adequate tests have been developed to measure the activation level of monocytes and tissue macrophages, and the risk of progression to a fatal hyperinflammatory syndrome. Blood monocytes provide a window on the systemic immune response, from production to tissue recruitment, reflecting the impact of infection on the host. Ready availability of blood makes it possible to monitor severity and the risk of potentially lethal complications, by developing tests to assess the status of monocyte activation and its potential for further inflammatory dysregulation after recruitment to tissues and during recovery.

Civil-military relations: a review of major guidelines and their relevance during public health emergencies

The operational and policy complexity of civil-military relations (CMR) during public health emergencies, especially those involving militaries from outside the state concerned, is addressed in several guiding international documents. Generally, these documents reflect humanitarian perspectives and doctrine at the time of their drafting, and primarily address foreign military involvement in natural and humanitarian disasters. However, in the past decade, there have been significant changes in the geopolitical environment and global health landscapes. Foreign militaries have been increasingly deployed to public health emergencies with responses grounded in public health (rather than humanitarian) approaches, while public health issues are of increasing importance in other deployments. This paper reviews key international policy documents that regulate, guide or otherwise inform CMR in the context of recent events involving international CMR during public health emergency responses, grounded in analysis of a March 2017 Chatham House roundtable event on the subject. Major thematic concerns regarding the application of existing CMR guiding documents to public health emergencies became evident. These include a lack of consideration of public health factors as distinct from a humanitarian approach; the assertion of state sovereignty vis-à-vis the deployment of national militaries; the emergence of new armed, military and security groups and a lack of consensus surrounding the 'principle of last resort'. These criticisms and gaps-in particular, a consideration for public health contexts and approaches therein-should form the basis of future CMR drafting or revision processes to ensure effective, safe, and sustainable CMR during public health emergency response.

Foam Cells Control Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis (Mtb) infects macrophages and macrophage-derived foam cells, a hallmark of granulomata in tuberculous lesions. We analyzed the effects of lipid accumulation in human primary macrophages and quantified strong triglyceride and phospholipid remodeling which depended on the dietary fatty acid used for the assay. The enrichment of >70% in triglyceride and phospholipids can alter cell membrane properties, signaling and phagocytosis in macrophages. In conventional macrophage cultures, cells are heterogeneous, small or large macrophages. In foam cells, a third population of 30% of cells with increased granularity can be detected. We found that foam cell formation is heterogenous and that lipid accumulation and foam cell formation reduces the phagocytosis of Mtb. Under the conditions tested, cell death was highly prevalent in macrophages, whereas foam cells were largely protected from this effect. Foam cells also supported slower Mtb replication, yet this had no discernible impact on the intracellular efficacy of four different antitubercular drugs. Foam cell formation had a significant impact in the inflammatory potential of the cells. TNF-α, IL-1β, and prototypical chemokines were increased. The ratio of inflammatory IL-1β, TNF-α, and IL-6 vs. anti-inflammatory IL-10 was significantly higher in response to Mtb vs. LPS, and was increased in foam cells compared to macrophages, suggestive of increased pro-inflammatory properties. Cytokine production correlated with NF-κB activation in our models. We conclude that foam cell formation reduces the host cell avidity for, and phagocytosis of, Mtb while protecting the cells from death. This protective effect is associated with enhanced inflammatory potential of foam cells and restricted intracellular growth of Mtb.

Enhanced Immunogenicity of Mitochondrial-Localized Proteins in Cancer Cells

Epitopes derived from mutated cancer proteins elicit strong antitumor T-cell responses that correlate with clinical efficacy in a proportion of patients. However, it remains unclear whether the subcellular localization of mutated proteins influences the efficiency of T-cell priming. To address this question, we compared the immunogenicity of NY-ESO-1 and OVA localized either in the cytosol or in mitochondria. We showed that tumors expressing mitochondrial-localized NY-ESO-1 and OVA proteins elicit significantdly higher frequencies of antigen-specific CD8+ T cells in vivo. We also demonstrated that this stronger immune response is dependent on the mitochondrial location of the antigenic proteins, which contributes to their higher steady-state amount, compared with cytosolic localized proteins. Consistent with these findings, we showed that injection of mitochondria purified from B16 melanoma cells can protect mice from a challenge with B16 cells, but not with irrelevant tumors. Finally, we extended these findings to cancer patients by demonstrating the presence of T-cell responses specific for mutated mitochondrial-localized proteins. These findings highlight the utility of prioritizing epitopes derived from mitochondrial-localized mutated proteins as targets for cancer vaccination strategies.

Plasma membrane receptors of tissue macrophages: functions and role in pathology

The cells of the mononuclear phagocyte system (MPS) constitute a dispersed organ, which is distributed throughout the body. Macrophages in different tissues display distinctive mosaic phenotypes as resident and recruited cells of embryonic and bone marrow origin, respectively. They help to maintain homeostasis during development and throughout adult life, yet contribute to the pathogenesis of many disease processes, including inflammation, innate and adaptive immunity, metabolic disorders, and cancer. Heterogeneous tissue macrophage populations display a wide variety of surface molecules to recognise and respond to host, microbial, and exogenous ligands in their environment; their receptors mediate the uptake and destruction of effete and dying host cells and pathogens, as well as contribute trophic and secretory functions within every organ in the body. Apart from local cellular interactions, macrophage surface molecules and products serve to mobilise and coordinate systemic humoral and cellular responses. Their use as antigen markers in pathogenesis and as potential drug targets has lagged in clinical pathology and human immunotherapy. In this review, we summarise the properties of selected surface molecules expressed on macrophages in different tissues and disease processes, to provide a functional basis for diagnosis, further research, and treatment. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

The Mononuclear Phagocytic System. Generation of Diversity

We are living through an unprecedented accumulation of data on gene expression by macrophages, reflecting their origin, distribution, and localization within all organs of the body. While the extensive heterogeneity of the cells of the mononuclear phagocyte system is evident, the functional significance of their diversity remains incomplete, nor is the mechanism of diversification understood. In this essay we review some of the implications of what we know, and draw attention to issues to be clarified in further research, taking advantage of the powerful genetic, cellular, and molecular tools now available. Our thesis is that macrophage specialization and functions go far beyond immunobiology, while remaining an essential contributor to innate as well as adaptive immunity.

Volumetric laser endomicroscopy and its application to Barrett's esophagus: results from a 1,000 patient registry

Volumetric laser endomicroscopy (VLE) uses optical coherence tomography (OCT) for real-time, microscopic cross-sectional imaging. A US-based multi-center registry was constructed to prospectively collect data on patients undergoing upper endoscopy during which a VLE scan was performed. The objective of this registry was to determine usage patterns of VLE in clinical practice and to estimate quantitative and qualitative performance metrics as they are applied to Barrett's esophagus (BE) management. All procedures utilized the NvisionVLE Imaging System (NinePoint Medical, Bedford, MA) which was used by investigators to identify the tissue types present, along with focal areas of concern. Following the VLE procedure, investigators were asked to answer six key questions regarding how VLE impacted each case. Statistical analyses including neoplasia diagnostic yield improvement using VLE was performed. One thousand patients were enrolled across 18 US trial sites from August 2014 through April 2016. In patients with previously diagnosed or suspected BE (894/1000), investigators used VLE and identified areas of concern not seen on white light endoscopy (WLE) in 59% of the procedures. VLE imaging also guided tissue acquisition and treatment in 71% and 54% of procedures, respectively. VLE as an adjunct modality improved the neoplasia diagnostic yield by 55% beyond the standard of care practice. In patients with no prior history of therapy, and without visual findings from other technologies, VLE-guided tissue acquisition increased neoplasia detection over random biopsies by 700%. Registry investigators reported that VLE improved the BE management process when used as an adjunct tissue acquisition and treatment guidance tool. The ability of VLE to image large segments of the esophagus with microscopic cross-sectional detail may provide additional benefits including higher yield biopsies and more efficient tissue acquisition. Clinicaltrials.gov NCT02215291.

The Elusive Role of Placental Macrophages: The Hofbauer Cell

In this review, we discuss the often overlooked tissue-resident fetal macrophages, Hofbauer cells, which are found within the chorionic villi of the human placenta. Hofbauer cells have been shown to have a phenotype associated with regulatory and anti-inflammatory functions. They are thought to play a crucial role in the regulation of pregnancy and in the maintenance of a homeostatic environment that is crucial for fetal development. Even though the numbers of these macrophages are some of the most abundant immune cells in the human placenta, which are sustained throughout pregnancy, there are very few studies that have identified their origin, their phenotype, and functions and why they are maintained throughout gestation. It is not yet understood how Hofbauer cells may change in function throughout normal pregnancy, and especially in those complicated by maternal gestational diabetes, preeclampsia, and viral infections, such as Zika, cytomegalovirus, and human immunodeficiency virus. We review what is known about the origin of these macrophages and explore how common complications of pregnancy dysregulate these cells leading to adverse birth outcomes in humans. Our synthesis sheds light on areas for human studies that can further define these innate regulatory cells.

Common signalling pathways in macrophage and osteoclast multinucleation

Macrophage cell fusion and multinucleation are fundamental processes in the formation of multinucleated giant cells (MGCs) in chronic inflammatory disease and osteoclasts in the regulation of bone mass. However, this basic cell phenomenon is poorly understood despite its pathophysiological relevance. Granulomas containing multinucleated giant cells are seen in a wide variety of complex inflammatory disorders, as well as in infectious diseases. Dysregulation of osteoclastic bone resorption underlies the pathogenesis of osteoporosis and malignant osteolytic bone disease. Recent reports have shown that the formation of multinucleated giant cells and osteoclast fusion display a common molecular signature, suggesting shared genetic determinants. In this Review, we describe the background of cell-cell fusion and the similar origin of macrophages and osteoclasts. We specifically focus on the common pathways involved in osteoclast and MGC fusion. We also highlight potential approaches that could help to unravel the core mechanisms underlying bone and granulomatous disorders in humans.

Macrophage Heterogeneity in the Immunopathogenesis of Tuberculosis

Macrophages play a central role in tuberculosis, as the site of primary infection, inducers and effectors of inflammation, innate and adaptive immunity, as well as mediators of tissue destruction and repair. Early descriptions by pathologists have emphasized their morphological heterogeneity in granulomas, followed by delineation of T lymphocyte-dependent activation of anti-mycobacterial resistance. More recently, powerful genetic and molecular tools have become available to describe macrophage cellular properties and their role in host-pathogen interactions. In this review we discuss aspects of macrophage heterogeneity relevant to the pathogenesis of tuberculosis and, conversely, lessons that can be learnt from mycobacterial infection, with regard to the immunobiological functions of macrophages in homeostasis and disease.