Bone Marrow Phagocytes Research Articles

Chemical composition and phagocyte immunomodulatory activity of Ferula iliensis essential oils.

Essential oil extracts from Ferula iliensis have been used traditionally in Kazakhstan for treatment of inflammation and other illnesses. Because little is known about the biologic activity of these essential oils that contributes to their therapeutic properties, we analyzed their chemical composition and evaluated their phagocyte immunomodulatory activity. The main components of the extracted essential oils were (E)-propenyl sec-butyl disulfide (15.7-39.4%) and (Z)-propenyl sec-butyl disulfide (23.4-45.0%). Ferula essential oils stimulated [Ca2+]i mobilization in human neutrophils and activated ROS production in human neutrophils and murine bone marrow phagocytes. Activation of human neutrophil [Ca2+]i flux by Ferula essential oils was dose-dependently inhibited by capsazepine, a TRPV1 channel antagonist, indicating that TRPV1 channels mediate this response. Furthermore, Ferula essential oils stimulated Ca2+ influx in TRPV1 channel-transfected HEK293 cells and desensitized the capsaicin-induced response in these cells. Additional molecular modeling with known TRPV1 channel agonists suggested that the active component is likely to be (Z)-propenyl sec-butyl disulfide. Our results provide a cellular and molecular basis to explain at least part of the beneficial therapeutic properties of FEOs.

Infection-Mediated Priming of Phagocytes Protects against Lethal Secondary Aspergillus fumigatus Challenge.

Phagocytes restrict the germination of Aspergillus fumigatus conidia and prevent the establishment of invasive pulmonary aspergillosis in immunecompetent mice. Here we report that immunecompetent mice recovering from a primary A. fumigatus challenge are protected against a secondary lethal challenge. Using RAGγc knock-out mice we show that this protection is independent of T, B and NK cells. In protected mice, lung phagocytes are recruited more rapidly and are more efficient in conidial phagocytosis and killing. Protection was also associated with an enhanced expression of CXCR2 and Dectin-1 on bone marrow phagocytes. We also show that protective lung cytokine and chemokine responses are induced more rapidly and with enhanced dynamics in protected mice. Our findings support the hypothesis that following a first encounter with a non-lethal dose of A. fumigatus conidia, the innate immune system is primed and can mediate protection against a secondary lethal infection.

Voltage-gated proton channels maintain pH in human neutrophils during phagocytosis

Phagocytosis of microbial invaders represents a fundamental defense mechanism of the innate immune system. The subsequent killing of microbes is initiated by the respiratory burst, in which nicotinamide adenine dinucleotide phosphate (NADPH) oxidase generates vast amounts of superoxide anion, precursor to bactericidal reactive oxygen species. Cytoplasmic pH regulation is crucial because NADPH oxidase functions optimally at neutral pH, yet produces enormous quantities of protons. We monitored pH(i) in individual human neutrophils during phagocytosis of opsonized zymosan, using confocal imaging of the pH sensing dye SNARF-1, enhanced by shifted excitation and emission ratioing, or SEER. Despite long-standing dogma that Na(+)/H(+) antiport regulates pH during the phagocyte respiratory burst, we show here that voltage-gated proton channels are the first transporter to respond. During the initial phagocytotic event, pH(i) decreased sharply, and recovery required both Na(+)/H(+) antiport and proton current. Inhibiting myeloperoxidase attenuated the acidification, suggesting that diffusion of HOCl into the cytosol comprises a substantial acid load. Inhibiting proton channels with Zn(2+) resulted in profound acidification to levels that inhibit NADPH oxidase. The pH changes accompanying phagocytosis in bone marrow phagocytes from HVCN1-deficient mice mirrored those in control mouse cells treated with Zn(2+). Both the rate and extent of acidification in HVCN1-deficient cells were twice larger than in control cells. In summary, acid extrusion by proton channels is essential to the production of reactive oxygen species during phagocytosis.

Roles of Retinoic Acid in Induction of Immunity and Immune Tolerance

It has long been recognized that vitamin A and its metabolites have immune-regulatory roles but the mechanism has been unclear. Recently, there has been a significant progress in elucidating the functions of retinoic acid in regulation of immune cell development. Retinoic acid (all-trans and 9-cis retinoic acid) is produced from the cells of the intestine such as dendritic cells and provides an intestine-specific environmental cue to differentiating immune cells. When T cells and B cells are activated in the intestine and associated-lymphoid tissues, gut homing receptors are induced on the cells in a retinoic acid and antigen-dependent manner. Retinoic acid, produced by gut dendritic cells, is also an important signal that induces IgA-producing B cells. The gut homing T cells and B cells play essential roles in protecting the digestive tract from pathogens. Retinoic acid is required also for production of mature phagocytes in bone marrow. On the other hand, retinoic acid induces a subset of FoxP3+ regulatory T cells which is important for maintaining immune tolerance in the gut. Therefore, retinoids provide both positive and negative regulatory signals to fine-control the mucosal immune system.

Effect of Lysosomotropic Form of Amphotericin B on Functional State of Phagocytes in Experimental Candidiasis

Effect of antifungal preparation amphotericin B and its lysosomotropic composition with dialdehyde-dextran on functional state of phagocytizing cells in the dynamics of granulomatous inflammation induced by C. albicans was studied on CBA mice. A stimulating effect of amphotericin B on the production of reactive oxygen species by peritoneal and bone marrow phagocytes was observed, while lysosomotropic form of the antibiotic did not stimulate generation of oxygen radicals.

Dendritic Cell immuno‐activating receptor 1 – Characterization of a novel member of the C‐type Lectin family

C‐type lectins (CLEC) comprise a superfamily of cell surface proteins, whose multifunctional capacity has been shown to address both, innate and adaptive immune response. Here, we describe mDCAR1 a novel CLEC belonging to the recently defined murine dendritic cell (DC) immuno‐receptor (mDCIR)/DC immuno‐activating receptor (mDCAR) family.mDCAR1 expression was found to be restricted to mononuclear phagocytes in bone marrow. Extensive phenotypical characterization defined them as CCR2−CD62L−CX3CR1+Ly6C− cells, thereby belonging to the recently described ‘resident’ monocytes, which correspond to CD14+ CD16+ human monocytes. In contrast, the CCR2+CD62L+CX3CR1lowLy6C+ ‘inflammatory’ monocytes were mDCAR1−. Noteworthy, in thymus, mDCAR1 expression was found on CD11chighCD8alpha+CD205+CD11b−B220−BP‐1+ lymphoid‐related DC, which play an important role in central tolerance induction.With respect to the classical function of CLEC as antigen uptake receptors for pathogens and self‐proteins, mimicking the ligation of mDCAR1 by labeling with specific mAb shows the internalization of the mDCAR1/ligand complex. Crosslinking of mDCAR1 further initiates signal transduction resulting in tyrosine‐phosphorylation of proteins.The expression pattern of mDCAR1 and the evidence of a classical antigen‐uptake mechanism are first steps to uncover the role of this representative of the CLEC receptor family.

Distinct actions of benzene and its metabolites on nitric oxide production by bone marrow leukocytes.

Benzene is a widely used industrial solvent known to cause bone marrow depression. This is associated with increased production of reactive oxygen metabolites and nitric oxide by bone marrow phagocytes, which have been implicated in hematotoxicity. Benzene metabolism to phenolic intermediates appears to be an important factor in bone marrow toxicity. In the present studies, we compared the effects of benzene and several of its metabolites on nitric oxide production by murine bone marrow leukocytes. Bone marrow cells readily produced nitric oxide in response to the inflammatory mediators lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Treatment of mice with benzene (800 mg/kg), or its metabolites hydroquinone (100 mg/kg), 1,2,4-benzenetriol (25 mg/kg), or p-benzoquinone (2 mg/kg), at doses that impair hematopoiesis, sensitized bone marrow leukocytes to produce increased amounts of nitric oxide in response to LPS and IFN-gamma. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) augmented bone marrow leukocyte production of nitric oxide induced by inflammatory mediators. Benzene, as well as its metabolites, markedly increased the sensitivity of the cells to both GM-CSF and M-CSF. Cells from hydroquinone- or 1,2,4-benzenetriol-treated mice were significantly more responsive to the inflammatory cytokines and growth factors than cells isolated from benzene- or p-benzoquinone-treated mice, suggesting that the phenolic metabolites of benzene are important biological reactive intermediates. Because nitric oxide suppresses cell growth and can be metabolized to mutagens and carcinogens, the ability of benzene and its metabolites to modulates its production in the bone marrow may be important in their mechanism of action.

Alterations in the morphology and functional activity of bone marrow phagocytes following benzene treatment of mice

Benzene is a well-established hematotoxin that affects developing leukocytes and erythrocytes as well as bone marrow stromal cells. In the present studies we analyzed the effects of benzene on the morphology and functional activity of bone marrow phagocytes. Male Balb c mice were treated with benzene (660 mg/kg) once per day for 3 days. Bone marrow cells were then isolated and fractionated by density gradient centrifugation. Using highly sensitive techniques in flow cytometry/cell sorting, we found that we could separate three distinct populations of bone marrow cells that differed with respect to size and density. Monoclonal antibody binding and cell sorting revealed a large, dense population that consisted predominantly of granulocytes, a smaller, less dense population of lymphocytes, and a population of intermediate size and density consisting of mononuclear phagocytes and precursor cells. Differential staining of sorted mononuclear phagocytes revealed that benzene treatment of mice caused a marked increase in the number of mature, morphologically activated macrophages in the bone marrow. Benzene treatment of mice also resulted in enhanced chemotaxis and production of hydrogen peroxide by bone marrow granulocytes and mononuclear phagocytes. In contrast, treatment of mice with the combination of hydroquinone and phenol (50 mg/kg each, 1×/day, 3 days), two metabolites of benzene, resulted in a significant ( p ≤ 0.02) depression of granulocyte chemotaxis and had no effect on hydrogen peroxide production by bone marrow phagocytes compared to cells from control animals. Taken together these results demonstrate that benzene causes increased differentiation and/or activation of phagocytes in the bone marrow.

Activation of bone marrow phagocytes following benzene treatment of mice.

Techniques in flow cytometry/cell sorting were used to characterize the effects of benzene and its metabolites on subpopulations of bone marrow cells. Treatment of male Balb/c mice with benzene (880 mg/kg) or a combination of its metabolites, hydroquinone and phenol (50 mg/kg), resulted in a 30 to 40% decrease in bone marrow cellularity. Flow cytometric analysis revealed two subpopulations of bone marrow cells that could be distinguished by their size and density or granularity. The larger, more dense subpopulation was found to consist predominantly of macrophages and granulocytes as determined by monoclonal antibody binding and by cell sorting. Benzene treatment had no selective cytotoxic effects on subpopulations of bone marrow cells. To determine if benzene treatment activated bone marrow phagocytes, we quantified production of hydrogen peroxide by these cells using the fluorescent indicator dye, 2',7'-dichlorofluorescein diacetate. We found that macrophages and granulocytes from bone marrow of treated mice produced 50% more hydrogen peroxide in response to the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate than did cells from control animals. It is hypothesized that phagocyte activation and production of cytotoxic reactive oxygen intermediates may contribute to hematotoxicity induced by benzene.

Activation of Bone Marrow Phagocytes Following Benzene Treatment of Mice

Activation of Bone Marrow Phagocytes Following Benzene Treatment of Mice

Morphological and functional findings of fixed phagocytes in psoriatics.

Twenty-one psoriatics as well as 24 normal healthy adults were studied by functional bone marrow scintigraphy using Tc-99m-labeled human serum albumin millimicrospheres (Tc-99m-HSA-MM). Functional bone marrow scintigraphy is an in vivo test system for the assessment of various functional properties of fixed phagocytes. Of psoriatics who had no systemic drug treatment, 59% demonstrated peripheral extension of the bone marrow space, indicating hyperplasia of bone marrow phagocytes. This phenomenon could be observed only in one normal subject who was a high-performance sportsman. Of psoriatics treated with aromatic retinoid, 83% (n = 6) demonstrated bone marrow extension, as did 100% (n = 3) of psoriatics with cirrhosis of liver. The "capacity' of bone marrow phagocytes to engulf Tc-99m-HSA-MM ("uptake ratio') was diminished in 34% of nontreated as well as 66% of psoriatics treated with aromatic retinoid. The phagocytic and proteolytic turnover of Tc-99m-HSA-MM in the bone marrow, spleen, and liver was found to e accelerated in 66% of nontreated psoriatics, normal (83%) or accelerated (17%) in psoriatics treated with aromatic retinoid, and considerably delayed in all of the psoriatics with cirrhosis of liver. Functional bone marrow scintigraphy proved to be an appropriate in vivo test system for revealing abnormalities of fixed phagocytes in psoriatics. Furthermore, therapeutic effects as well as the influences of preexisting disorders on different phagocyte populations can be assessed.

Maturation and Interrelationship of Mouse Mononuclear Phagocytes in Bone Marrow, Peripheral Blood and Peritoneal Cavity in Terms of Erythrophagocytic Activity

Ingestion by mononuclear cells in bone marrow, peripheral blood and the peritoneal cavity of red cells treated with antibodies and various chemicals was studied in an attempt to characterize these cell lines during development and to clarify the interrelationship among them. Bone marrow mononuclear phagocytes became intensively phagocytic during the second day of culture, indicating that the maturation time from progenitor cells to macrophages was about 48 hr. Blood monocytes exhibited very active erythrophagocytic activity after 24 to 48 hr cell culture. Uptake of sensitized red cells by both the cell lines was markedly inhibited by IgG irrespective of time periods of cell culture. Majority of peritoneal lymphocyte-like cells (LLC) separated from other forms of mononuclear cells were shown to become capable of erythrophagocytosis with maturation time to macrophages between 24 to 48 hrs. Under non-stimulated steady state, uptake of sensitized red cells by peritoneal macrophages was far less sensitive to IgG inhibition than that by bone marrow mononuclear phagocytes and blood monocytes, suggesting that IgG receptor does not play main role for the erythrophagocytosis by peritoneal macrophages. Peritoneal cells collected under inflammatory stimulus exhibited a character similar to bone marrow mononuclear phagocytes and blood monocytes with regard to IgG receptor. It was suggested that under steady state peritoneal macrophages arise and mature from local proliferative pool with some different phagocytic mechanism from that of bone marrow mononuclear phagocytes.

Observations regarding the nature of Howell-Jolly bodies.

Abstract. A study of the distribution and morphology of Howell‐Jolly bodies in blood, bone marrow and spleen aspirates from patients with and without functioning spleen led to the conclusion that most bodies so labelled are not intracellular remnants of the normoblast nuclei. They are in most cases situated on the outside of the erythrocyte membrane and to be regarded as degradation products of nuclei, digested by bone marrow phagocytes and released from these cells at a certain stage of degradation. They are normally removed by the spleen; in the absence of the spleen they may remain for some time in circulating blood with a tendency to adhere to red cells.