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Humans are exposed to numerous synthetic foreign particles in the form of drug delivery systems and diagnostic agents. Specialized immune cells (phagocytes) clear these particles by phagocytosing and attempting to degrade them. The process of recognition and internalization of the particles may trigger changes in the function of phagocytes. Some of these changes, especially the ability of a particle-loaded phagocyte to take up and neutralize pathogens, remains poorly studied. Herein, we demonstrate that the uptake of non-stimulatory cargo-free particles enhances the phagocytic ability of monocytes, macrophages and neutrophils. The enhancement in phagocytic ability was independent of particle properties, such as size or the base material constituting the particle. Additionally, we show that the increased phagocytosis was not a result of cellular activation or cellular heterogeneity but was driven by changes in cell membrane fluidity and cellular compliance. A consequence of the enhanced phagocytic activity was that particulate-laden immune cells neutralize Escherichia coli (E. coli) faster in culture. Moreover, when administered in mice as a prophylactic, particulates enable faster clearance of E. coli and Staphylococcus epidermidis. Together, we demonstrate that the process of uptake induces cellular changes that favor additional phagocytic events. This study provides insights into using non-stimulatory cargo-free particles to engineer immune cell functions for applications involving faster clearance of phagocytosable abiotic and biotic material. [Display omitted] • Uptake of particulate matter drives sequential phagocytosis in macrophages, monocytes, and neutrophils. • Increased sequential phagocytosis is not a result of Toll-like receptor driven activation or cellular heterogeneity. • Sequential phagocytosis is likely driven by changes to the fluidity of the cell membrane and cellular compliance. • One application of the enhanced phagocytosis driven by particulates is to increase the clearance rates of bacteria. [ABSTRACT FROM AUTHOR]

Atopic bronchial asthma based on allergy history and chronic inflammation is hazardous to patients due to the risk of exacerbation. The sign of severe exacerbation is considered an abundant number and high activity of granulocytes in respiratory system and blood. Relationships between the ability of cells in blood to produce reactive radicals and their metabolites and the severity of asthma remain largely unclear. Kinetics of respiratory burst evoked by microbe particles in blood samples of patients was studied to reveal the most significant predictors distinguishing states of moderate exacerbation and out of exacerbation. Asthmatic patients with exacerbation (n = 18) or out of exacerbation (n = 62) and healthy individuals (n = 43) were characterized on respiratory function, cell count in blood and kinetics of generation of reactive radicals and their metabolites during phagocytosis. Mean values of respiratory parameters forced expiratory volume in 1 s and peak expiratory flow rate in patients with exacerbation were significantly differed compared with same of patients out of exacerbation and healthy individuals. Mean values of cell count in blood did not significantly differed in patients with exacerbation and out of exacerbation. Receiver operating characteristic analysis showed that both cell count and respiratory indexes did not discriminate patients with exacerbation from out of exacerbation. A delayed response to opsonized zymosan was revealed in patients with exacerbation compared to other examinees: lengthened lag-time and T max , reduced production of reactive species. T max was the most statistically significant predictor to discriminate bronchial asthma exacerbation from bronchial asthma out of exacerbation (area under curve >90%, p < 10−5) and controls (area under curve >80%, p < 10−5). Thus kinetic parameters of the phagocyte response to opsonized zymosan in the whole blood are the best predictors of bronchial asthma exacerbation in comparison with respiratory parameters and blood cell count. This test can be used for immunological monitoring of bronchial asthma status to prevent exacerbation. Image 1 • Reactive species are key players in inflammation leading to exacerbations of asthma. • Kinetics of respiratory burst in blood is the sensitive test to reveal exacerbation. • In exacerbation the kinetic parameters as lag-time and T max are lengthened. • T max is the most sensitive and specific index to distinguish moderate exacerbation. [ABSTRACT FROM AUTHOR]

Macrophage hyperfunction or dysfunction is tightly associated with various diseases, such as osteoporosis, inflammatory disorder, and cancers. However, nearly all conventional drug delivery system (DDS) nanocarriers utilize endocytosis for entering target cells; thus, the development of macrophage-targeting and phagocytosis-inducing DDS nanocarriers for treating these diseases is required. In this study, we developed a hepatitis B virus (HBV) envelope L particle ( i.e. , bio-nanocapsule (BNC)) outwardly displaying a tandem form of protein G-derived IgG Fc-binding domain and protein L-derived IgG Fab-binding domain (GL-BNC). When conjugated with the macrophage-targeting ligand, mouse IgG2a (mIgG2a), the GL-BNC itself, and the liposome-fused GL-BNC ( i.e. , GL-virosome) spontaneously initiated aggregation by bridging between the Fc-binding domain and Fab-binding domain with mIgG2a. The aggregates were efficiently taken up by macrophages, whereas this was inhibited by latrunculin B, a phagocytosis-specific inhibitor. The mIgG2a-GL-virosome containing doxorubicin exhibited higher cytotoxicity toward macrophages than conventional liposomes and other BNC-based virosomes. Thus, GL-BNCs and GL-virosomes may constitute promising macrophage-targeting and phagocytosis-inducing DDS nanocarriers. Statement of Significance We have developed a novel macrophage-targeting and phagocytosis-inducing bio-nanocapsule (BNC)-based nanocarrier named GL-BNC, which comprises a hepatitis B virus envelope L particle outwardly displaying protein G-derived IgG Fc- and protein L-derived IgG Fab-binding domains in tandem. The GL-BNC alone or liposome-fused form (GL-virosomes) could spontaneously aggregate when conjugated with macrophage-targeting IgGs, inducing phagocytosis by the interaction between IgG Fc of aggregates and FcγR on phagocytes. Thereby these aggregates were efficiently taken up by macrophages. GL-virosomes containing doxorubicin exhibited higher cytotoxicity towards macrophages than ZZ-virosomes and liposomes. Our results suggested that GL-BNCs and GL-virosomes would serve as promising drug delivery system nanocarriers for targeting delivery to macrophages. [ABSTRACT FROM AUTHOR]

In phagocytes, superoxide anion (O 2 −), the precursor of reactive oxygen species, is produced by the NADPH oxidase complex to kill pathogens. Phagocyte NADPH oxidase consists of the transmembrane cytochrome b 558 (cyt b 558) and four cytosolic components: p40phox, p47phox, p67phox, and Rac1/2. The phagocyte activation by stimuli leads to activation of signal transduction pathways. This is followed by the translocation of cytosolic components to the membrane and their association with cyt b 558 to form the active enzyme. To investigate the roles of membrane-interacting domains of the cytosolic proteins in the NADPH oxidase complex assembly and activity, we used giant unilamellar phospholipid vesicles (GUV). We also used the neutrophil-like cell line PLB-985 to investigate these roles under physiological conditions. We confirmed that the isolated proteins must be activated to bind to the membrane. We showed that their membrane binding was strengthened by the presence of the other cytosolic partners, with a key role for p47phox. We also used a fused chimera consisting of p47phox(aa 1–286), p67phox(aa 1–212) and Rac1Q61L, as well as mutated versions in the p47phox PX domain and the Rac polybasic region (PB). We showed that these two domains have a crucial role in the trimera membrane-binding and in the trimera assembly to cyt b 558. They also have an impact on O 2.- production in vitro and in cellulo : the PX domain strongly binding to GUV made of a mix of polar lipids; and the PB region strongly binding to the plasma membrane of neutrophils and resting PLB-985 cells. [Display omitted] • Lipid-protein interactions are crucial for the assembly of the NADPH oxidase. • P47phox helps for p67phox and Rac binding to lipid membrane. • Rac PB region and p47phox PX domain targets different membrane. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are important in bronchial asthma (BA) pathogenesis owing to accumulation of activated granulocytes in the lungs. But the ROS-producing activity of the cells is insufficiently understood in the blood of BA patients. This study analyzes the kinetics of phagocyte respiratory burst in the blood to improve the methods of BA patients monitoring. Patients with atopic BA out of exacerbation (n = 60) and healthy controls (n = 43) were recruited. The time-course of respiratory response to opsonized zymosan (OZ) was recorded in the whole blood using luminol-dependent chemiluminescence (CL), and its activation kinetics (lag-time, rate, amplitude, ROS production) was calculated. The discriminative power of ROS generation kinetics was defined by Receiver Operating Characteristic (ROC) curve analysis. Standard physiological respiratory parameters of patients did not differ from the controls. More rapid response to OZ was recorded in BA patient samples versus the controls. The primed state of phagocytes in the blood of BA patients was corroborated by significant weakening formyl peptide priming effect. The adhesion of granulocytes to cultured human endothelial cells was two-fold higher in BA patients versus controls. ROC curve analysis exhibited good discriminative effectiveness of the CL kinetics to compare BA individuals with the controls. The highest power (86% sensitivity and 90% specificity) was achieved at a linear combination of the parameters. We assume that the assessment of phagocyte reactivity based on the analysis of the response kinetic profile is a good test for monitoring of the state in BA patients. [ABSTRACT FROM AUTHOR]

Chemotherapeutic drugs, such as cyclophosphamide, are one of the most vital means to kill tumors, meanwhile however, inevitable to impair the gastrointestinal (GI) tract. Secretory immunoglobulin A (SIgA) is a keystone anti-inflammatory antibody shielding the intestinal mucosal surfaces by spatially disengaging pathogens and commensals in the gut lumen. In this animal based study, we unraveled that squid ink polysaccharide (SIP) extracted from Ommastrephes bartrami is the predominantly functional polysaccharide featured to promote secretion of intestinal SIgA by increasing the expression of each of its constituents, including IgA, J chain and pIgR. Furthermore, SIP activated phenotypic transformation of monocytes to macrophages, leading to higher expression levels of IL-6, IL-10 and TNF-α, resulting in enhanced syntheses of IgA and J chain in IgA + cells and that of pIgR in epithelial cells. Our study paves a basis for the implication of the dietary polysaccharide in amelioration of mucosal injuries. [ABSTRACT FROM AUTHOR]

Therapeutic nanoparticles (NPs) can deliver cytotoxic chemotherapeutics and other drugs more safely and efficiently to patients; furthermore, selective delivery to target tissues can theoretically be accomplished actively through coating NPs with molecular ligands, and passively through exploiting physiological “enhanced permeability and retention” features. However, clinical trial results have been mixed in showing improved efficacy with drug nanoencapsulation, largely due to heterogeneous NP accumulation at target sites across patients. Thus, a clear need exists to better understand why many NP strategies fail in vivo and not result in significantly improved tumor uptake or therapeutic response. Multicolor in vivo confocal fluorescence imaging (intravital microscopy; IVM) enables integrated pharmacokinetic and pharmacodynamic (PK/PD) measurement at the single-cell level, and has helped answer key questions regarding the biological mechanisms of in vivo NP behavior. This review summarizes progress to date and also describes useful technical strategies for successful IVM experimentation. [ABSTRACT FROM AUTHOR]

Fish immune systems must be able to cope with pathogens over a wide temperature range. Earlier research suggest that fish are more dependent on innate immune responses based on pattern recognition than acquired functions with specific recognition. If this applies to phagocytes, then opsonins (serum factors that augment phagocytosis e.g. immunoglobulins and complement proteins) attached on zymosan (Z) particles should be recognized better at higher temperatures than Z only. Z is recognized by glucan receptor representing pattern recognition. In this study perch were acclimated to 5 °C or 16 °C for 3–5 weeks. The recognition and activation of respiratory burst reaction of peripheral blood phagocytes was examined at seven different measurement temperatures (5, 10, 16, 20, 24 27, and 30 °C) when the cells were stimulated with Z and serum opsonized zymosan (OZ). Respiratory burst was measured as luminol chemiluminescence (CL) from diluted whole blood. OZ-induced CL per volume of blood was on average approximately 4.6 times higher in 16 °C acclimated fish than 5 °C acclimated perch ( P <0.0001). Z-induced CL was approximately 3 times higher at lower temperatures in 16 °C acclimated perch than 5 °C acclimated fish and 6–9 times higher at 27 °C and 30 °C ( P <0.001), respectively. CL reaction kinetics were faster in perch acclimated to 5 °C than 16 °C -acclimated fish, especially at low temperatures ( P <0.001). Thermal acclimation caused a 3–4 °C shift in temperature response curves of CL towards the acclimation temperature ( P <0.0001 and P <0.053 in Z and OZ-induced CL, respectively). Serum opsonins activated perch phagocytes substantially better at higher temperatures in both acclimation groups, which is consistent with an earlier study in rainbow trout ( O. mykiss ). However, opsonin recognition was significantly better in 16 °C acclimated perch than 5 °C acclimated fish, which was seen as higher CLs for OZ compared to Z, especially at higher temperatures. This is opposite to previously reported results in rainbow trout. Differences between rainbow trout and perch in opsonin recognition by blood phagocytes suggest that the living habits of perch, which prefers approximately a 10 °C higher temperature than rainbow trout, may be reflected in immune cell functions. Results of the present examination suggest that also in fish phagocytes pattern recognition is the prevailing system at low temperatures, and specific recognition is more effective at high temperatures. [ABSTRACT FROM AUTHOR]

Aim Neutrophil extracellular traps (NETs) are mesh-like DNA fibers clad with intracellular proteins that are cast out from neutrophils in response to certain stimuli. The process is thought to depend on reactive oxygen species (ROS) generated by the phagocyte NADPH-oxidase and the ROS-modulating granule enzyme myeloperoxidase (MPO), but when, how, and where these factors contribute is so far uncertain. The neutrophil NADPH-oxidase can be activated at different cellular sites and ROS may be produced and processed by MPO within intracellular granules, even in situations where a phagosome is not formed, e.g., upon stimulation with phorbol myristate acetate (PMA). Objectives We investigated the subcellular location of ROS production and processing by MPO in the context of PMA-induced NET formation. Results Complete neutralization of extracellular ROS was not sufficient to block NET formation triggered by PMA, indicating that intragranular ROS are critical for NETosis. Employing a set of novel MPO-inhibitors, inhibition of NET formation correlated with inhibition of intragranular MPO activity. Also, extracellular addition of MPO was not sufficient to rescue NET formation in completely MPO-deficient neutrophils and specific neutralization by luminol of MPO-processed ROS within intracellular granules led to a complete block of PMA-triggered NET formation. Conclusion We show for the first time that inhibition of intragranular MPO activity, or neutralization of intragranular MPO-processed ROS by luminol effectively block NET formation. Our data demonstrate that ROS must be formed and processed by MPO in order to trigger NET formation, and that these events have to occur within intracellular granules. [ABSTRACT FROM AUTHOR]

Phago-lysosome formation is important for cell-autonomous immunity to intracellular pathogens, antigen presentation and metabolism. A hallmark feature of phago-lysosomal compartments is that they undergo progressive luminal acidification controlled by the activation of vacuolar V-ATPase. Acidification is required for many enzymatic processes taking place in phago-lysosomes, like proteolysis, and supports the microbicidal activity of macrophages. Here we present a new quantitative methodology to assess phagosome acidification by flow cytometry based on the use of bi-fluorescent particles. This method relies on the use of UV polystyrene beads labelled with the acid sensor pHrodo-succinimidyl ester (pHrodo TM SE red) and enables us to dissociate particle association with phagocytes from their engulfment in acidified compartments. This methodology is well suited to monitor the acidification of phagosomes formed in vivo after fluorescent bead administration. [ABSTRACT FROM AUTHOR]

Abstract: The pathogenic mechanisms of Brucellosis used to adapt to the harsh intracellular environment of the host cell are not fully understood. The present study investigated the in vitro and in vivo characteristics of B. abortus betaine aldehyde dehydrogenase (BetB) (Gene Bank ID: 006932) using a betB deletion mutant constructed from virulent B. abortus 544. In test under stress conditions, including osmotic- and acid stress-resistance, the betB mutant had a lower osmotic-resistance than B. abortus wild-type. In addition, the betB mutant showed higher internalization rates compared to the wild-type strain; however, it also displayed replication failures in HeLa cells and RAW 264.7 macrophages. During internalization, compared to the wild-type strain, the betB mutant was more adherent to the host surface and showed enhanced phosphorylation of protein kinases, two processes that promote phagocytic activity, in host cells. During intracellular trafficking, colocalization of B. abortus-containing phagosomes with LAMP-1 was elevated in betB mutant-infected cells compared to the wild-type cells. In mice, the betB mutant was predominantly cleared from spleens compared to the wild-type strain after 2 weeks post-infection, and the vaccination test with the live betB mutant showed effective protection against challenge infection with the virulent wild-type strain. These findings suggested that the B. abortus betB gene substantially affects the phagocytic pathway in human phagocytes and in host cells in mice. Furthermore, this study highlights the potential use of the B. abortus betB mutant as a live vaccine for the control of brucellosis. [Copyright &y& Elsevier]

Abstract: Objectives: Despite medical advances, infectious diseases are still a major cause of mortality and morbidity, disability and socio-economic upheaval worldwide. Early diagnosis, appropriate choice and immediate initiation of antibiotic therapy can greatly affect the outcome of any kind of infection. Phagocytes play a central role in the innate immune response of the organism to infection. They comprise the first-line of defense against infectious intruders in our body, being able to produce large quantities of reactive oxygen species, which can be detected by means of chemiluminescence (CL). The data preparation approach implemented in this work corresponds to a dynamic assessment of phagocytic respiratory burst localization in a luminol-enhanced whole blood CL system. We have previously applied this approach to the problem of identifying various intra-abdominal pathological processes afflicting peritoneal dialysis patients in the Nephrology department and demonstrated 84.6% predictive accuracy with the C4.5 decision-tree algorithm. In this study, we apply the CL-based approach to a larger sample of patients from two departments (Nephrology and Internal Medicine) with the aim of finding the most effective and interpretable feature sets and classification models for a fast and accurate identification of several infectious diseases. Materials and methods: Whole blood samples were collected from 78 patients (comprising 115 instances) with respiratory infections, infections associated with renal replacement therapy and patients without infections. CL kinetic parameters were calculated for each case, which was assigned into a specific clinical group according to the available clinical diagnostics. Feature selection wrapper and filter methods were applied to remove the irrelevant and redundant features and to improve the predictive performance of disease classification algorithms. Three data mining algorithms, C4.5 (J48) decision tree, support vector machines and naive Bayes classifier were applied for inducing disease classification models and their performance in classifying three clinical groups was evaluated by 10 runs of a stratified 10-fold cross-validation. Results and conclusions: The results demonstrate that the predictive power of the best models obtained with the three evaluated algorithms after feature selection was found to be in the range of 63.38±2.18–70.68±1.43%. The highest disease classification accuracy was reached by C4.5, which also provides the most informative model in the form of a decision tree, and the lowest accuracy was obtained with naive Bayes. The feature selection method attaining the best classification performance was the wrapper method in forward direction. Moreover, the classification models exposed biological patterns specific to the clinical states and the predictive features selected were found to be characteristic of a specific disorder. Based on these encouraging results, we believe that the CL-based data pre-processing approach combined with the wrapper forward feature selection procedure and the C4.5 decision-tree algorithm has a clear potential to become a fast, informative, and sensitive tool for predictive diagnostics of infectious diseases in clinics. [Copyright &y& Elsevier]

Abstract: Objectives: M-ficolin (ficolin-1) is a complement-activating pattern-recognition molecule structurally related to mannan-binding lectin. It is produced by monocytes and neutrophils, and is found in serum. Its biological role is largely unknown. We assessed M-ficolin concentration in serum from pediatric cancer patients. The aim of this study was to explore association of M-ficolin with clinical and hematological parameters, and to investigate whether the risk of chemotherapy-related infections was related to M-ficolin concentrations in serum. Methods: M-ficolin was measured by time-resolved immunofluorometric assay in serum taken at cancer diagnosis and was correlated with peripheral blood counts and bone marrow examinations performed at the same time. Results: Median M-ficolin concentration in 94 children with cancer was 1.6μg/mL (interquartile range, 0.57–2.7; range, 0.055–25.8), and was not different from age-matched controls (median, 1.7μg/mL; p =0.92). M-ficolin was strongly associated with absolute counts of neutrophils (Spearman''s rho, 0.45; 95%-CI, 0.26–0.65; p <0.001), monocytes (0.34; 0.12–0.55; p <0.001), and thus phagocytes (0.42; 0.20–0.63; p <0.001) in peripheral blood. Similarly, M-ficolin correlated strongly with neutrophils (0.36; 0.14–0.59; p =0.002) and phagocytes (0.31; 0.08–0.54; p =0.009) in bone marrow. Low serum M-ficolin (≤0.5μg/mL) was not associated with an increased incidence of fever in neutropenia during chemotherapy (multivariate Poisson rate ratio, 1.04; 95%-CI, 0.68–1.60; p =0.85). Conclusions: The concentration of M-ficolin in serum from children with cancer was strongly associated with neutrophil and monocyte counts in blood and bone marrow. These results suggest that M-ficolin concentrations in serum reflect the pool of phagocytes. [Copyright &y& Elsevier]

Abstract: Professional phagocytes increase their consumption of molecular oxygen during the phagocytosis of microbes or when encountering a variety of nonparticulate stimuli. In these circumstances, oxygen is reduced by the phagocyte NADPH oxidase, and reactive oxygen species (ROS), which are important for the microbicidal activity of the cells, are generated. The structure and function of the NADPH oxidase have been resolved in part by studying cells from patients with chronic granulomatous disease (CGD), a condition characterized by the inability of phagocytes to assemble a functional NADPH oxidase and thus to produce ROS. As a result, patients with CGD have a predisposition to infections as well as a variety of inflammatory symptoms. A long-standing paradigm has been that NADPH oxidase assembly occurs exclusively in the plasma membrane or invaginations thereof (phagosomes). A growing body of evidence points to the possibility that phagocytes are capable of NADPH oxidase assembly in nonphagosomal intracellular membranes, resulting in ROS generation within intracellular organelles also in the absence of phagocytosis. The exact nature of these ROS-producing organelles is yet to be determined, but granules are prime suspects. Recent clinical findings indicate that the generation of intracellular ROS by NADPH oxidase activation is important for limiting inflammatory reactions and that intracellular and extracellular ROS production are regulated differently. Here we discuss the accumulating knowledge of intracellular ROS production in phagocytes and speculate on the precise role of these oxidants in regulating the inflammatory process. [ABSTRACT FROM AUTHOR]

Summary: The dissemination of Mycobacterium tuberculosis from the primary focus of infection is central to the pathogenesis of tuberculosis. Trafficking of bacteria to the regional lymph nodes is essential to the development of a protective T-cell mediated immune response, but bacteria trafficked within the bloodstream can lead to extra-pulmonary dissemination and some of the most devastating clinical consequences of tuberculosis. Yet how M. tuberculosis leaves the lungs is poorly understood. Here, we review the potential pathways and molecular mechanisms behind the dissemination of M. tuberculosis and consider the consequences to both host and bacteria. To disseminate M. tuberculosis must breach the alveolar epithelium and various bacterial factors have been implicated in this process. Heparin binding haemagglutinin adhesin (HBHA) enables M. tuberculosis to bind to sulphated glycoconjugates on epithelial cells; disruption of its synthesis severely impairs the ability of bacteria to disseminate from the lungs to the spleen. Two products of the M. tuberculosis RD1 gene locus, early secretory antigenic target 6 kDa (ESAT-6) and culture filtrate protein 10 kDa (CFP-10), have been linked to cell lysis and may enable bacteria to invade and spread within the alveolar epithelium. Recent studies in embryonic zebrafish indicate ESAT-6 may also stimulate the trafficking of infected macrophages within granulomas, thereby promoting the early dissemination of bacteria. These findings challenge conventional notions of the protective role of granulomas in mycobacterial infection and indicate M. tuberculosis has evolved specific mechanisms which utilise granulomas as foci of macrophage recruitment, infection, and subsequent bacterial dissemination. Further understanding of the pathways, mechanisms and consequences of M. tuberculosis dissemination could have a major impact in designing novel vaccines and therapeutic strategies. [Copyright &y& Elsevier]

Abstract: During brain or cardiac ischemia/reperfusion neutrophils are recruited and activated contributing to inflammation and tissue damage. Neutrophils are removed from inflamed tissues by phosphatidylserine-dependent phagocytosis. Production of reactive oxygen species by the neutrophil NADPH-oxidase is known to affect phosphatidylserine externalization. Amiloride derivatives are inhibitors of the sodium–proton exchanger providing substantial protection in animal models of brain and cardiac ischemia/reperfusion injury; however their effects on neutrophils remain incompletely known. We investigated the effect of 5-(N,N-hexomethylene)amiloride (HMA) on phosphatidylserine externalization in wild type and NADPH-oxidase deficient PLB-985 cells differentiated into neutrophils. We show that HMA had a dual effect: (1) 60μM HMA induced phosphatidylserine externalization in at least 40% of the cells; (2) 20μM HMA had no direct effect but enhanced phosphatidylserine externalization induced by cell activation with PMA or calcium ionophore A23187. Both effects were independent of the NADPH-oxidase and were not due to changes in intracellular pH. 60μM HMA induced a capacitative calcium entry which was necessary for phosphatidylserine externalization. The HMA-induced PS externalization was inhibited by salubrinal, an inhibitor of ER-stress-linked apoptosis. Lower HMA concentration enhanced PMA or A23187 effects through PKC and calcium dependent pathways. The caspase inhibitor Z-VAD-FMK weakly diminished phosphatidylserine externalization, suggesting that activation of caspases 7, 8, 9 and 3 was not involved. Increasing phosphatidylserine externalization by low concentrations of HMA improved the engulfment of PMA-activated PLB-985 cells by macrophages, providing a novel therapeutic strategy to limit the accumulation of neutrophils in injured tissues. [ABSTRACT FROM AUTHOR]

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Abstract: The immunomodulatory role of endogenous opioid peptides released during stress has been extensively studied in mammals, but least explored in lower vertebrates. The present in vitro study for the first time reports the specific opioid receptor-mediated immunomodulatory role of dynorphin-A(1–17) in ectotherms. Dynorphin-A(1–17) had pleiotropic effects on phagocyte functions, stimulatory on phagocytosis and superoxide production while inhibitory on the nitrite release. However, the effect of dynorphin-A(1–17), whether stimulatory or inhibitory, markedly declined at high (10−5 M) concentration. Dynorphin-A(1–17) seems to mediate its action through opioid receptors since non-selective opioid receptor antagonist, naltrexone, completely blocked the effect of dynorphin-A(1–17) on phagocytosis, superoxide production and nitrite release. Moreover, among specific opioid receptors antagonists, only selective κ (kappa)-opioid receptor antagonist norbinaltorphimine was capable to antagonize the pleiotropic effects on phagocyte functions. The present study provides the direct evidence of immunomodulatory role of dynorphin-A(1–17) via κ-opioid receptor in freshwater teleost Channa punctatus. [Copyright &y& Elsevier]

Abstract: It is well documented that the polysaccharide glucomannan (GM), an abundant constituent of the fungal cell wall, in the form of particulate induces strong activation of phagocytes, however, the effects of soluble GM are not known. Activation of phagocyte anti-microbial mechanisms is a crucial part of the innate host defense against invading pathogens. However, under uncontrolled inflammatory conditions they contribute to damage of surrounding tissues. Thus, to prevent these deleterious effects, the activation of phagocytes is a tightly regulated process. Therefore, in this study we analyzed the effect of soluble GM on some neutrophil functions such as reactive oxygen species production, degranulation, and receptor mobilization at the plasma membrane. Soluble GM at the tested concentrations did not stimulate oxidative burst of phagocytes directly but significantly potentiated oxidative burst in response to opsonized zymosan particles. GM induced significant phosphorylation of p47phox subunit of NADPH oxidase on Ser345. This priming effect of GM was accompanied by time and concentration dependent degranulation characterized by increased surface expression of receptors stored in neutrophil granules (CD10, CD11b, CD14, CD35, and CD66b). Degranulation was further confirmed by increase of elastase activity in media. Thus, it could be suggested that soluble GM induces priming of phagocytes connected with their degranulation, the increase of surface receptor expression, and potentiation of oxidative burst response to opsonized particles through the activation of NADPH oxidase. [Copyright &y& Elsevier]

Abstract: The immunoregulatory role of methionine-enkephalin (Met-enk) is well studied in mammals, but has not been explored in ectotherms despite the fact that this peptide is highly conserved in vertebrates. The present study demonstrates the diverse effects of Met-enk depending on its concentration and specific function of splenic phagocytes in the freshwater fish Channa punctatus. Although Met-enk increased both phagocytic as well as respiratory burst activity, the concentration-related response was opposite to each other. It had the maximum stimulatory effect on phagocytosis at 10−9 M, while the same concentration was least effective in increasing superoxide production. Similarly, Met-enk at concentrations lower or higher than 10−9 M was either ineffective or less effective in case of phagocytosis, while highly effective in stimulating superoxide production. On the other hand, concentration-independent inhibitory effect of Met-enk was observed in case of nitrite production. Nonetheless, Met-enk regulated all the functions of phagocyte through opioid receptors since non-specific opioid receptor antagonist naltrexone completely blocked the effect of Met-enk on phagocytosis, superoxide and nitrite production by splenic phagocytes of C. punctatus. Among selective opioid receptor antagonists, δ-opioid receptor antagonist naltrindole completely antagonized the effect of Met-enk on phagocytosis, superoxide and nitrite production, while μ- and κ-opioid receptor antagonist, CTAP and norbinaltorphimine, respectively, were ineffective in influencing any of the functions. This suggests that Met-enk modulates splenic phagocyte functions in the fish C. punctatus via δ-opioid receptor. This is further substantiated by using highly selective δ-opioid receptor agonist, SNC80. [Copyright &y& Elsevier]

Superoxide-producing NADPH oxidase, gp91 phox /NOX2, in phagocytes plays a critical role in the host defenses against pathogens. Moreover, gp91 phox /NOX2 contributes to the oxidative stress in endothelial cells. Therefore, investigating the level of gp91 phox /NOX2 with immunoblotting is important for estimating the amount of superoxide produced. Here, we showed that the epitopes in human gp91 phox /NOX2 recognized by monoclonal antibodies (mAbs) CL-5 and 48 were in amino acids 132–147 and 136–144, respectively. Although the epitopes were close to the N -glycosylation sites, N -glycan maturation did not affect mAbs recognition. When Pro-136 was substituted with Arg, the corresponding mouse residue, human gp91 phox /NOX2 was not recognized by mAbs CL-5 and 48; however, the substitution did not affect gp91 phox /NOX2-based oxidase activity. This finding explains why these mAbs specifically recognize the human but not mouse gp91 phox /NOX2. Hence, these mAbs are useful for investigating the level of gp91 phox /NOX2 without amino acid substitutions in the epitopes. • The epitope in human gp91 phox /NOX2 recognized by mAb CL-5 is in amino acids 132–147. • The epitope in human gp91 phox /NOX2 recognized by mAb 48 is in amino acids 136–144. • Pro-136 is responsible for the recognition by both mAbs CL-5 and 48. • N -glycans are unnecessary for the recognition by mAbs CL-5 and 48. [ABSTRACT FROM AUTHOR]

Abstract: The activity of hematopoietic cell kinase (Hck), a member of the Src family kinases, is modulated by regulatory mechanisms leading to distinct protein conformations with gradual levels of activity. Hck is mostly expressed in phagocytes as two isoforms, p59Hck and p61Hck, which show distinct subcellular localizations and trigger distinct phenotypes when expressed ectopically in fibroblasts. Hck has been reported to be involved in phagocytosis, adhesion and migration, and to regulate formation of membrane protrusions, lysosome exocytosis, podosome formation, and actin polymerization. The present review focuses on the mechanisms regulating Hck activity as well as on the functions of Hck isoforms in phagocytes, and presents selected examples of Hck substrates and/or adaptors shown to interact with the kinase in myeloid cells. Deciphering Hck signaling pathways is a challenge to progress in the understanding of innate immune responses and pathologies involving phagocytes such as inflammatory diseases, leukemia, and human immunodeficiency virus-1 (HIV-1) infection. [Copyright &y& Elsevier]

Abstract: In this in vitro study, the role of β-endorphin in the control of phagocytic and cytotoxic activities of fish splenic phagocytes was investigated. Further, the involvement of specific opioid receptor was explored. β-Endorphin stimulated phagocytosis, whereas inhibited nitric oxide production as assessed by nitrite release. However, it had concentration-related biphasic effects on superoxide production, stimulatory at low and inhibitory at high concentration. Naltrexone, non-selective opioid receptor antagonist, antagonized the effect of β-endorphin on phagocyte functions. Moreover, CTAP, selective μ-receptor antagonist, completely blocked the effect of β-endorphin on phagocytosis and nitrite release. With regard to superoxide production, CTAP blocked the stimulatory effect of β-endorphin at low concentration, while the inhibitory effect at high concentration was completely antagonized by selective δ-receptor antagonist, NTI. In conclusion, β-endorphin acting via μ-receptor stimulated phagocytosis and inhibited nitric oxide production, while its biphasic effect on superoxide production seems to be mediated by μ- and δ-receptors. [Copyright &y& Elsevier]

Abstract: We investigated the effects of the 5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b] pyridin-3-yl]-pyrimidin-4-ylamine (BAY 41-2272) on the NADPH oxidase activity, gp91 phox gene expression, cyclic guanosine-3′,5′-monophosphate (cGMP) and cyclic adenosine-3′,5′-monophosphate (cAMP) levels in the human myelomonocytic THP-1 cell line. THP-1 cells treated with BAY 41-2272 (0.3–10 μM) for 48 h significantly increased the superoxide anion (O2 •−) release. This increase was not affected when cells were pre-treated with the specific cGMP-phosphodiesterase inhibitor zaprinast, the soluble guanylate cyclase inhibitor 1H-[1,2,4] oxidiazolo[4,3-α] quinoxalin-1-one (ODQ), the adenylate cyclase inhibitor 9-(tetrahydro-2-furanyl) adenine (SQ 22,536) or the nitric oxide synthase inhibitor N ω-nitro-l-arginine methyl ester (l-NAME). In addition, BAY 41-2272 (3 and 10 μM; 48 h) was able to increase gp91 phox gene expression on THP-1 cells. The pre-treatment with zaprinast, 3-isobutyl-l-methyl-xanthine (IBMX; 0.5 mM), ODQ, SQ 22,536 or l-NAME caused no additional effect on the expression of gp91 phox evoked by BAY 41-2272. Treatment of THP-1 cells with BAY 41-2272 caused a significant increase in cGMP and cAMP levels. Our findings show that BAY 41-2272 caused a significant increase on the O2 •− release and gp91 phox gene expression by THP-1 cells, and an elevation of intracellular cGMP and cAMP levels. However, we could not detect a clear correlation between both O2 •− release and gp91 phox gene expression with activation of cGMP and cAMP signaling pathways. [Copyright &y& Elsevier]

Abstract: The phagocyte NADPH oxidase produces superoxide anion (O2 ·−) by the electrogenic process of moving electrons across the cell membrane. This charge translocation must be compensated to prevent self-inhibition by extreme membrane depolarization. Examination of the mechanisms of charge compensation reveals that these mechanisms perform several other vital functions beyond simply supporting oxidase activity. Voltage-gated proton channels compensate most of the charge translocated by the phagocyte NADPH oxidase in human neutrophils and eosinophils. Quantitative modeling of NADPH oxidase in the plasma membrane supports this conclusion and shows that if any other conductance is present, it must be miniscule. In addition to charge compensation, proton flux from the cytoplasm into the phagosome (a) helps prevent large pH excursions both in the cytoplasm and in the phagosome, (b) minimizes osmotic disturbances, and (c) provides essential substrate protons for the conversion of O2 ·− to H2O2 and then to HOCl. A small contribution by K+ or Cl− fluxes may offset the acidity of granule contents to keep the phagosome pH near neutral, facilitating release of bactericidal enzymes. In summary, the mechanisms used by phagocytes for charge compensation during the respiratory burst would still be essential to phagocyte function, even if NADPH oxidase were not electrogenic. [Copyright &y& Elsevier]

Abstract: We describe herein the construction of a novel computerized multi-sample temperature-controlled luminometer for a fiber array-based biosensor to monitor circulating phagocyte activity. It can perform simultaneously integral measurements of chemiluminescence emitted from up to six samples containing less than 0.5μl whole blood while the samples and detector do not change their position during the measurement cycle. The optical fibers in this luminometer are used as both light guides and solid phase sample holders. The latter feature of the instrument design simplifies the assessment process of both the extra-cellular and the intra-cellular parts of the phagocyte-emitted chemiluminescence using the same system. We describe some examples or proof of principle for the use of the biosensor. This new technology may find use in a wide range of analytical luminescence applications in biology, biophysics, biochemistry, toxicology and clinical medicine. [Copyright &y& Elsevier]

Abstract: The time course of select phagocyte and natural killer activities to short days was determined. In advance of testes regression, circulating granulocyte and monocyte cell numbers in hamsters decreased while lymphocyte numbers increased; phagocytosis and oxidative burst activity also decreased. To determine whether the pineal gland influences these innate immune cell functions, hamsters were exposed to constant light. Photoperiod control of testes weight and basal oxidative burst activity was abolished by treatment with constant light; other phagocyte activities and leukocyte proportions in circulation were not affected. The findings suggest that photoperiod and pineal gland function may regulate certain innate immune activities. [Copyright &y& Elsevier]

Co-stimulatory factors are involved in different forms of brain pathology and play an important role in the activation of T-cells. In the current study, we explored the regulation of B7.2, a prominent member of the B7 family of costimulatory factors, in the facial motor nucleus (FMN) following facial axotomy and systemic application of lipopolysaccharide (LPS, endotoxin) using light and electron immunohistochemistry and cytokine-receptor-deficient mice.Facial axotomy led to a gradual increase of B7.2 immunoreactivity (IR) on microglial cell surface; similar effects were also observed following application of LPS, but both effects were not additive, suggesting overlapping or saturated signaling pathways. Some B7.2-IR was already present on activated microglia surrounding injured neurons at days 1–4 after injury, but became particularly intense during neuronal cell death, peaking at day 14. Previous studies revealed that these late microglial changes are accompanied by a strong increase in the expression of proinflammatory cytokines such as interleukin-1 beta (IL1β) tumor necrosis factor-alpha (TNFα) and interferon gamma (IFNγ) [J. Neurosci. 18 (1998a) 5804]. Here, deletion of the receptors for these cytokines—IL1R1, TNFR1 or TNFR2, but not IFNγR1—caused a strong and significant reduction in B7.2-IR in reactive microglial cells, compared with their wild type (WT) controls on the same genetic strain background, with a 31% decrease in IL1R1−/− , 39% in TNFR1−/− and 49% in TNFR2−/− mice.These data underscore the significance of IL1β, TNFα and LPS, and their receptors, as potent inflammatory signals that regulate the cellular response in the injured brain as well as the interaction with the rapidly recruited immune system. The broad susceptibility of B7.2 regulation to a wide range of different inflammatory signals also points to its role as a sensor of molecular pathology, and a factor that plays an important accessory role in allowing and shaping the microglia/T-cell interaction in the injured central nervous system. [Copyright &y& Elsevier]

Adhesion of phagocytes to endothelial cells constitutes a crucial step in atherogenesis. Oxidized low density lipoproteins (LDL) are supposed to facilitate the adhesion process. We investigated the molecular mechanisms by which mildly and extensively hypochlorite-oxidized LDL force adhesion of murine macrophages and human neutrophils to human umbilical venous endothelial cells. After 1 h of co-incubation of macrophages, endothelial cells, and lipoproteins adhesion significantly increased to 160±13% (S.E.M., n=5) in the presence of mildly oxidized lipoprotein, and 210±11% (S.E.M., n=5) in the presence of extensively oxidized lipoprotein. Similar results were obtained with neutrophils. CD36 antibody (FA6-152) significantly reduced adhesion to 102±7% (S.E.M., n=5) using mildly oxidized low density lipoprotein and to 179±16% (S.E.M., n=5) using extensively oxidized low density lipoprotein. Native high density lipoprotein and to a lesser extent methionine-oxidized high density lipoprotein significantly counteracted the effects of low density lipoprotein. Prior incubation of endothelial cells with modified lipoproteins followed by their removal and subsequent incubation with macrophages or neutrophils resulted in only minor changes of adhesion. This suggests that the direct contact of low density lipoprotein with phagocytes followed by activation of a respiratory burst with release of reactive oxygen species facilitates the adhesion process. Accordingly, the addition of antioxidants (superoxide dismutase and catalase) to the co-incubation medium was followed by a significant decrease in phagocyte adhesion. It is concluded that oxidized low density lipoprotein-induced respiratory burst activation of phagocytes with subsequent release of oxidants constitutes a crucial step in promoting the adhesion of phagocytes to endothelial cells. [Copyright &y& Elsevier]

Malnutrition contributes to increased morbidity and mortality through reduced phagocyte function. Dietary restriction impairs neutrophil migration through reduced cytokine and chemokine production by macrophages. Dietary restriction also decreased neutrophil phagocytosis. Intracellular signal transduction is responsible for cytokine/chemokine production and migration and phagocytosis of phagocytes. This article focuses on effects of nutrition on the intracellular signaling of phagocytes.Either tyrosine kinase inhibition or extracellular signal-regulated kinase (ERK) inhibition decreased survival of ad labium, but not for diet-restricted mice in the cercal ligation and puncture model. Peritoneal cells harvested from diet-restricted mice could not increase tyrosine phosphorylation in response to N-formyl-methionyl-leucyl-phenylalanine (fMLP) stimulation. Laser scanning of cytometers revealed that tyrosine phosphorylation is mainly localized in the cytoplasm of the resident macrophages. ERK was activated in peritoneal exudative cells (PECs) from ad libitum mice after fMLP stimulation, whereas the cells of diet-restricted animals did not show any increase in ERK phosphorylation. Dietary restriction impaired tumor necrosis factor alpha (TNF-α)-induced nuclear factor kappa B (NFκB) activation in the peritoneal resident cells (PRCs). Refeeding for only 1 day recovered the impaired NFκB activation.In conclusion, deranged tyrosine phosphorylation, ERK activation and NFκB activation of phagocytes by diet restriction, at least in part, account for the impaired host defense during malnutrition. Detailed information concerning the molecular mechanisms involved in regulation of host defense by malnutrition may help to develop new strategies for nutritional support. [Copyright &y& Elsevier]

Are advanced oxidation protein products potential uremic toxins? Oxidative stress, defined as a disruption of the equilibrium between the generation of oxidants and the activity of anti-oxidant systems, plays a significant role in the development of the inflammatory syndrome associated with chronic renal failure and hemodialysis. In our recent work, the aim of which was to better characterize oxidative stress in dialysis patients, we described the presence of oxidized protein products, which we have termed advanced oxidation protein products (AOPP), in the plasma of dialysis patients and we proposed AOPP as new markers of oxidative stress and potential inflammatory mediators. AOPP represent an exquisite marker of phagocyte-derived oxidative stress, and their role in the pathophysiology of chronic renal failure and dialysis-related complications might be of great importance. Regarding the mechanisms of generation of AOPP, we pointed out the importance of myeloperoxidase and the subsequent generation of chlorinated oxidants, previously considered solely as microbicidal agents, in the formation of AOPP. Indeed, AOPP appear to act as true inflammatory mediators since they are able to trigger the oxidative burst and the synthesis of inflammatory cytokines in neutrophils, as well as in monocytes. Thus, it could be hypothesized that the AOPP, which arise from the reaction between chlorinated oxidants and plasma proteins, constitute new uremic toxins with pro-inflammatory effects. [ABSTRACT FROM AUTHOR]

Phagocytic myeloid cells provide the principle line of immune defence during early embryogenesis in lower vertebrates. They may also have important functions during normal embryo morphogenesis, not least through the phagocytic clearance of cell corpses arising from apoptosis. We have identified two cDNAs that provide sensitive molecular markers of embryonic leukocytes in the early Xenopus embryo. These encode a peroxidase (XPOX2) and a Ly-6/uPAR-related protein (XLURP-1). We show that myeloid progenitors can first be detected at an antero-ventral site in early tailbud stage embryos (a region previously termed the anterior ventral blood island) and transiently express the haematopoetic transcription factors SCL and AML. Phagocytes migrate from this site along consistent routes and proliferate, becoming widely distributed throughout the tadpole long before the circulatory system is established. This migration can be followed in living embryos using a 5 kb portion of the XLURP-1 promoter to drive expression of EGFP specifically in the myeloid cells. Interestingly, whilst much of this migration occurs by movement of individual cells between embryonic germ layers, the rostral-most myeloid cells apparently migrate in an anterior direction along the ventral midline within the mesodermal layer itself. The transient presence of such cells as a strip bisecting the cardiac mesoderm immediately prior to heart tube formation suggests that embryonic myeloid cells may play a role in early cardiac morphogenesis. [Copyright &y& Elsevier]

Chronic granulomatous disease (CGD) is an inherited immunodeficiency disease caused by defects in leukocyte NADPH oxidase. Various inherited defects in one of the membrane-bound components of NADPH oxidase, gp91-phox, cause X-linked (X91) CGD. Analysis of three patients with X91 CGD revealed that different mechanisms of molecular quality control lead to the common phenotype of absence of mature membrane-bound NADPH oxidase complex in leukocytes. In the first patient, aberrant intron splicing created a premature stop codon. However, the mutant mRNA was degraded prematurely, which prevented the production of truncated protein. In the second patient, a frameshift mutation with the potential to generate a gp91-phox polypeptide, with an aberrant and elongated C-terminus, led to barely detectable levels of gp91-phox, even though the reported functional domains of the protein appeared unaffected. In the third patient, a point mutation created a single amino acid change in the predicted FAD-binding site of gp91-phox. Although gp91-phox was detectable with Western blotting, no cytochrome b558 was expressed on the cell surface. These analyses showed that molecular quality control machinery plays an important role in the pathogenesis of CGD, not only in the X910 but also in the X91− form of this X-linked disease. [Copyright &y& Elsevier]

The sterile inflammation caused by damage-associated molecular patterns (DAMPs) worsens the prognosis following primary injury such as ischemic stroke. However, there are no effective treatments to regulate DAMPs. Here, we report that AIM (or CD5L) protein reduces sterile inflammation by attenuating DAMPs and that AIM administration ameliorates the deleterious effects of ischemic stroke. AIM binds to DAMPs via charge-based interactions and disulfide bond formation. This AIM association promotes the phagocytic removal of DAMPs and neutralizes DAMPs by impeding their binding to inflammatory receptors. In experimental stroke, AIM-deficient mice exhibit severe neurological damage and higher mortality with greater levels of DAMPs and associated inflammation in the brain than wild-type mice, in which brain AIM levels increase following stroke onset. Recombinant AIM administration reduces sterile inflammation in the infarcted region, leading to a profound reduction of animal mortality. Our findings provide a basis for the therapies targeting DAMPs to improve ischemic stroke. [Display omitted] • AIM markedly increases in the infarcted brain, expressed by recruited macrophages • AIM associates with DAMPs via charge-based interaction and disulfide bond formation • AIM reduces or attenuates DAMPs, thereby suppressing cerebral inflammation • Administration of AIM improves the post-stroke prognosis in mice Maehara et al. show that AIM (or CD5L) is increased in the infarcted brain and associates with DAMPs. The association decreases DAMPs, and therefore, AIM improves post-stroke prognosis in mice by reducing cerebral inflammation. AIM may be a useful therapy for ischemic stroke targeting DAMP-mediated sterile inflammation. [ABSTRACT FROM AUTHOR]

Abstract: It has been claimed that, in contrast to most opioids, tramadol does not suppress immune functions. We therefore, studied the effects of tramadol in comparison to morphine, on the number of phagocytes and the number of sheep red blood cells (SRBCs) engulfed by each individual cell (phagocytic index) of mouse peritoneal phagocyte. In an experimental study, 63 BALB/c mice received morphine, tramadol or saline intraperitoneally. On days 3, 5, and 10, the peritoneal phagocytes were incubated with an equal number of SRBCs. The cells were then cytocentrifuged onto gelatin-coated slides and examined microscopically. Ten days after the start of drug administration, the number of phagocytes and the phagocytic index reduced in morphine group (P <0.05), and enhanced in tramadol group (P <0.05). In conclusion, tramadol stimulation of immune system may offer a good alternative to morphine for the treatment of patients in whom immunosuppression might be hazardous or in patients who cannot tolerate the side effects of morphine. [Copyright &y& Elsevier]

Objectives: To characterize peritoneal dendritic cells (DCs) in endometriosis and to clarify their role in its etiology.Design: Experimental.Setting: University hospital.Patient(s): Sixty-three women (35 patients with endometriosis and 28 control women) who had undergone laparoscopic surgery.Intervention(s): Peritoneal DCs from endometriosis and control samples were analyzed for the expression of cell surface markers. Monocyte-derived dendritic cells (Mo-DCs) were cultured with dead endometrial stromal cells (dESCs) to investigate changes in phagocytic activity and cytokine expression.Main Outcome Measure(s): Cell surface markers and cytokine expression and identification with the use of flow cytometry or reverse-transcription polymerase chain reaction (RT-PCR). Changes in cytokine expression and phagocytic activity of Mo-DCs cultured with dESCs and d-mannan were measured with the use of flow cytometry and RT-PCR.Result(s): The proportion of mannose receptor (MR)-positive myeloid DC type 1 was higher in endometriosis samples than in control samples. The blocking of MR reduced phagocytosis of dESCs by Mo-DCs. Mo-DCs cultured with dESCs expressed higher levels of interleukin (IL) 1β and IL-6 than control samples.Conclusion(s): Peritoneal DCs in endometriosis tissue express high levels of MR, which promotes phagocytosis of dead endometrial cells and thereby contributes to the etiology of endometriosis. [ABSTRACT FROM AUTHOR]