Effect of orexin-A on phagocytic activity of peritoneal macrophage in starved rats

The aim of this study was to investigate the effect of fasting-induced orexin-A (OXA) on inflammation and macrophage phagocytic activity. Fifty six male wistar rats were fasted for 36 h to stimulate OXA synthesis. In 24 rats, air pouches were induced subcutaneously in the intrascapular area. After (6 h) carrageenan injection into the pouches, the contents of the air pouches were removed. The exudate volume, protein content and cell count were measured. After the determination of fasting on inflammation, the peritoneal macrophages were collected from 32 rats to investigate the effect of fasting-induced OXA on macrophage phagocytic activity. Plasma OXA levels were markedly higher in fasted rats compared with control rats. The phagocytic capability of peritoneal macrophages was obtained as a percentage of phagocytosing macrophages and number of phagocytosed particles per cell. In spite of increased blood OXA level SB-334867, selective orexin type 1 receptor antagonist (10 mg/kg) did not change phagocytic activity of peritoneal macrophages. These findings indicate that 36 h fasting-induced OXA has no significant effect to phagocytosis of peritoneal macrophages.     

Analysis of macrophage heterogeneity by their phagocytic activity

Heterogeneity of resident peritoneal macrophages was studied as revealed by their phagocytosis and binding of sheep erythrocytes opsonized by specific rabbit IgG. It has been shown that the macrophage heterogeneity is due to the presence of active and inactive cellular subpopulations. A mathematical model, based on the Poisson fitting of experimental histograms, was elaborated for the analysis of subpopulation composition of macrophage pool in the test of rosette formation and phagocytosis. The validity of the model was supported by physicochemical isolation of the macrophage subpopulation which was inactive in erythrocyte binding. The macrophage pool was separated into fractions by absorption--elution at different temperatures. Active and inactive macrophage subpopulations were found in all the fractions but in different ratios.     

Suppressing action of splenic cells on macrophage phagocytic activity]

The culture media withdrawn from 18-hour cultures of live spleen cells suppressed the phagocytic activity of peritoneal macrophages in mice. The level of suppression, as estimated for an equal number of spleen cells, varied in individual animals, which seemed to be connected with the level of normal infection in the animals. In the process of development of Ehrlich's carcinoma in mice suppressors were produced in the spleen in an increased amount, but only in connection with the total increase in the number of spleen cells, and not due to the selective accumulation of suppressor cells.     

Effect of isoproterenol on the plasma C-peptide and insulin levels in humans

There are conflicting reports on the effect of stimulation of the beta-adrenergic receptors on insulin removal by the liver. It was, therefore, the aim of the present study to clarify that problem. Four experiments have been carried out on a group of 8 healthy female volunteers: (1) isoproterenol was infused intravenously, (2) glucose was infused intravenously, (3) isoproterenol was infused with glucose, and (4) infusion of isoproterenol and glucose was preceded by administration of propranolol (the beta-adrenergic blocking agent). The concentration of C-peptide and insulin was determined in plasma from the antecubital vein. It has been found that stimulation of the beta-adrenergic receptors with isoproterenol reduces insulin removal by the human liver. This effect of isoproterenol is prevented by blockade of the beta-adrenergic receptors with propranolol.     

Intracellular glutathione status regulates mouse bone marrow monocyte-derived macrophage differentiation and phagocytic activity

Although a redox shift can regulate the development of cells, including proliferation, differentiation, and survival, the role of the glutathione (GSH) redox status in macrophage differentiation remains unclear. In order to elucidate the role of a redox shift, macrophage-like cells were differentiated from the bone marrow-derived monocytes that were treated with a macrophage colony stimulating factor (M-CSF or CSF-1) for 3 days. The macrophagic cells were characterized by a time-dependent increase in three major symptoms: the number of phagocytic cells, the number of adherent cells, and the mRNA expression of c-fms, a M-CSF receptor that is one of the macrophage-specific markers and mediates development signals. Upon M-CSF-driven macrophage differentiation, the GSH/GSSG ratio was significantly lower on day 1 than that observed on day 0 but was constant on days 1-3. To assess the effect of the GSH-depleted and -repleted status on the differentiation and phagocytosis of the macrophages, GSH depletion by BSO, a specific inhibitor of the de novo GSH synthesis, inhibited the formation of the adherent macrophagic cells by the down-regulation of c-fms, but did not affect the phagocytic activity of the macrophages. To the contrary, GSH repletion by the addition of NAC, which is a GSH precursor, or reduced GSH in media had no effect on macrophage differentiation, and led to a decrease in the phagocytic activity. Furthermore, we observed that there is checkpoint that is capable of releasing from the inhibition of the formation of the adherent macrophagic cells according to GSH depletion by BSO. Summarizing, these results indicate that the intracellular GSH status plays an important role in the differentiation and phagocytosis of macrophages.     

Translocation of VP1686 upregulates RhoB and accelerates phagocytic activity of macrophage through actin remodeling

Here, we report that Vibrio parahaemolyticus induces a rapid remodeling of macrophage actin and activates RhoB GTPase. Mutational analysis revealed that the effects depend on type III secretion system 1 regulated translocation of a V. parahaemolyticus effector protein, VP1686, into the macrophages. Remodeling of actin is shown to be necessary for increased bacterial uptake followed by initiation of apoptosis in macrophages. This provides evidence for functional association of the VP1686 in triggering an eat-me-and-die signal to the host.     

ICAM-1 facilitates alveolar macrophage phagocytic activity through effects on migration over the AEC surface

We postulate that intercellular adhesion molecule-1 (ICAM-1) on type I alveolar epithelial cells (AEC) facilitates phagocytic activity of alveolar macrophages (AM) in the alveolus. When wild-type and ICAM-1-deficient mice were inoculated intratracheally with FITC-labeled microspheres, AM phagocytosis of beads (after 1 and 4 h) was significantly reduced in ICAM-1-/- mice compared with controls. To focus on ICAM-1-mediated interactions specifically involving AM and AEC, rat AM were placed in culture with rat AEC treated with neutralizing anti-ICAM-1 F(ab')(2) fragments. Blocking ICAM-1 significantly decreased the AM phagocytosis of beads. Planar chemotaxis of AM over the surface of AEC was also significantly impaired by neutralization of AEC ICAM-1. ICAM-1 in rat AEC is associated with the actin cytoskeleton. Planar chemotaxis of AM was also significantly reduced by pretreatment of the AEC monolayer with cytochalasin B to disrupt the actin cytoskeleton. These studies indicate that ICAM-1 on the AEC surface promotes mobility of AM in the alveolus and is critically important for the efficient phagocytosis of particulates by AM.     

Effect of thrombin on macrophage and lymphocyte functional activity

It has been shown that thrombin induces blast transformation of lymphocytes, stimulates the phagocytic activity of macrophages and limits their migration.     

Effect of irradiation on proteins and phagocytic activity of rat blood leukocytes

The method of chromatography on DEAE-cellulose was used to study the effect of radiation (180.6 mC/kg) on the physicochemical properties of rat leukocyte proteins. The qualitative changes were noted in the protein spectrum of leukocytes which were indicative of the substantial changes in the cell proteins. A fraction was isolated which caused a 44% inhibition of the phagocytic activity of intact leukocytes in vitro.     

Enhancement of colony-stimulating-factor--dependent clonal growth of murine macrophage progenitors and their phagocytic activity by retinoic acid

The effect of retinoic acid (RA) on the colony-stimulating-factor-dependent clonal growth of myeloid progenitors was assessed in semisolid agar cultures of mouse bone marrow cells using L-cell-conditioned medium that gave rise to macrophage colonies, granulocyte colonies, and mixed macrophage-granulocyte colonies and clusters. RA was found to enhance the overall formation of myeloid colonies (about 50%) and clusters in 7-day cultures. The increase was due to an enhanced formation of macrophage colonies (70-250%) and clusters which reached a maximal value at about 3 microM RA. In 4-day cultures, the effect of RA on macrophage colony formation was biphasic with a maximal enhancement at 10 nM. RA suppressed granulocyte-colony formation in 4-day cultures. RA increased the phagocytic activity of bone-marrow-derived macrophages at all stages of differentiation and/or maturation in culture. The Fc-receptor-mediated erythrophagocytosis as well as the phagocytosis of heat-killed yeast cells (HK-yeast) and starch particles increased by RA treatment in a dose-dependent manner, reaching an increase of 100-200% of the activity expressed in the absence of RA. Peritoneal exudate macrophages likewise exhibited an increased phagocytic response to a variety of particles, at both physiological and pharmacological concentrations of RA. Expression of an RA-mediated increase in phagocytic activity required a prolonged incubation with RA (greater than 19 hr). The data suggest that RA may be of physiological relevance in the regulation of proliferation and function of hemopoietic cells. Therapeutic doses of RA may potentiate macrophage proliferation and function, elements that are crucial at all phases of the various defense mechanisms that the organism possesses.     

Phospholipid methyltransferase activity in diabetic rat fat cells: effect of isoproterenol and insulin

The effects of isoproterenol and insulin on phospholipid methyltransferase (PLMT) activity were investigated in adipocytes from control and streptozotocin-diabetic rats. PLMT activity was assayed by measuring the rate of incorporation of ³H-methyl groups from S-adenosyl-L-[methyl-³H] methionine into phospholipids. Basal PLMT activity was higher in adipocytes from diabetic animals. Treatment of adipocytes with isoproterenol induced a concentration-dependent stimulation of PLMT activity. In control adipocytes, the maximal effect was obtained at 100 nM isoproterenol with 2.3 fold increase in PLMT activity and a half maximal effect at 25 nM. In adipocytes from diabetic rats, a lower dose of isoproterenol (10 nM), caused 1.2 fold increase with a half maximal effect at 4 nM. Addition of 100 nM insulin inhibited basal PLMT activity and the stimulatory effect of isoproterenol in both types of adipocytes. The -adrenergic blocking agent propranolol inhibited the stimulatory effect of isoproterenol on PLMT activity in control and diabetic adipocytes. Intracellular concentration of cAMP was higher in diabetic adipocytes but decreased to normal values after incubation in the presence of insulin.     

Inhibition of macrophage phagocytic activity by selective sensitization to alloantigens of the H-2 system

The action exerted by selective sensitizations to alloantigens coded by the Major Histocompatibility System of the mouse, H-2, on the phagocytic ability of the mouse peritoneal macrophages has been studied. The results suggest that when immunizations are performed between completely incompatible animals for the H-2k haplotype, after the third immunization the total number of macrophages able to carry out phagocytosis decreases very significantly. When the incompatibilities, however, are due to the left half of the H-2 system or to minor histocompatibility antigens, such an inhibition does not appear.     

Effect of chronic isoproterenol exposure on insulin binding and insulin-stimulated hexose transport in isolated rat adipocytes

The effect of chronic exposure of isolated rat adipocytes to the beta-adrenergic agonist isoproterenol has been studied with respect to insulin binding and insulin-stimulated hexose uptake. Isoproterenol exposure led to a progressive decrease in both the number of surface insulin receptors and the stimulation of hexose uptake. The effect on insulin binding was reversible by removal of the beta-agonist within an hour of its addition. Later exposures of adipocytes to isoproterenol resulted in an irreversible cellular defect by leading to a progressive inability of the cells to regain their normal level of insulin-stimulated hexose uptake and insulin binding.     

Electrophysiology of phagocytic membranes: intracellular K+ activity and K+ equilibrium potential in macrophage polykaryons

The role of K⁺ as current carrier during the slow membrane hyperpolarizations (SH) elicited by iontophoretic Ca²⁺ injections into macrophage polykaryons is studied. The intracellular K⁺ activity (a_K) and the K⁺ equilibrium potential (E_K) are measured using ion-sensitive microelectrodes. The mean value of a_K is 84 ± 5 mM in a culture medium containing 5.3 mM K⁺, but increases to 100 ± 8 mM when the extracellular K⁺ concentration is raised to 30.3 mM. Under the same conditions the values of E_K obtained from the Nernst equation are −81 ± 2 mV and −40 ± 2 mV, respectively. The reversal potentials (E_R) of the SH are calculated from changes observed in transmembrane potential and input resistance, according to an equivalent model based only on passive ionic fluxes. The mean E_R values obtained are −74 ± 8 mV in the presence of low K⁺ concentration and −37 ± 3 mV for the high K⁺ medium. These values are significantly smaller than the estimated E_K for the corresponding situations. Evidence for the existence of an electrogenic (Na⁺ + K⁺)-ATPase activity is also presented. The evidence indicates that an increase in the membrane potassium permeability can account for about 90% of the total permeability change occurring during the SH.