Rat Polymorphonuclear Cells Research Articles

Matrix metalloproteinase-9 in pneumococcal meningitis: activation via an oxidative pathway.

In experimental bacterial meningitis, matrix metalloproteinases (MMPs) and reactive oxygen species (ROS) contribute to brain damage. MMP-9 increases in cerebrospinal fluid (CSF) during bacterial meningitis and is associated with the brain damage that is a consequence of the disease. This study assesses the origin of MMP-9 in bacterial meningitis and how ROS modulate its activity. Rat brain-slice cultures and rat polymorphonuclear cells (PMNs) that had been challenged with capsule-deficient heat-inactivated Streptococcus pneumoniae R6 (hiR6) released MMP-9. Coincubation with either catalase, with the myeloperoxidase inhibitor azide, or with the hypochlorous acid scavenger methionine almost completely prevented activation, but not the release, of MMP-9, in supernatants of human PMNs stimulated with hiR6. Thus, in bacterial meningitis, both brain-resident cells and invading PMNs may act as sources of MMP-9, and stimulated PMNs may activate MMP-9 via an ROS-dependent pathway. MMP-9 activation by ROS may represent a target for therapeutic intervention in bacterial meningitis.

Evidence that glutamine modulates respiratory burst in stressed rat polymorphonuclear cells through its metabolism into arginine.

Glutamine (GLN) and arginine (ARG) are recognized for their ability to modulate immune cell function. However, the metabolic pathways involved in their action remain unclear. It was recently shown that GLN- or ARG-enriched diets increased radical oxygen species (ROS) production by neutrophils from stressed rats. Since these two amino acids have a tied metabolism, we hypothesized that conversion between GLN and ARG (and its active metabolites NO* and polyamines) might be involved. To test this hypothesis male Sprague-Dawley rats (n 117) were randomized into thirteen groups: rats in eleven groups were rendered catabolic by dexamethasone injection (1.5 mg/kg per d for 5 d) and 6.8 mmol either GLN, ARG or non-essential amino acids (NEAA; glycine, alanine and histidine)/kg per d were given by the enteral route; one group was pair-fed to the treated groups. The regimens of all the groups were rendered isonitrogenous by the addition of NEAA. The last group was not treated and was fed ad libitum. For each supplementation three subgroups were formed, each of which received a specific inhibitor: methionine sulfoximine (inhibitor of GLN synthase; 100 mg/kg per d), S-methylthiourea (inhibitor of inducible NO* synthase (iNOS); 50 mg/kg per d) and difluoromethylornithine (inhibitor of ornithine decarboxylase (ODC); 50 mg/kg per d). Oxidative metabolism, intracellular H2O2, and extracellular O2*- production were measured in unstimulated and phorbol myristate acetate-stimulated polymorphonuclear neutrophils. GLN- and ARG-enriched diets increased respiratory burst by neutrophils (oxidative metabolism of 152 (sem 24) and 138 (sem 45) v. 57 (sem 18) mV for GLN-, ARG- and NEAA-enriched diets respectively, P<0.05). In vivo inhibition of iNOS or ODC decreased ROS production induced by GLN and ARG. In vivo inhibition of GLN synthase did not modify the effect of ARG on ROS production. In conclusion, GLN and ARG modulate ROS production in neutrophils from stressed rats by the same pathway involving polyamine and NO* synthesis.

Cloricromene synergizes with antiplatelet drugs and nitric oxide-like factor derived from rat peritoneal polymorphonuclear cells

We report that cloricromene (5–30 μM) inhibited thrombin-induced platelet aggregation and synergized with other antiplatelet compounds. The antiaggregatory effect of subthreshold concentrations of the prostaglandin (PG)I 2 analogue, iloprost (0.2 nM), or of sodium nitroprusside (1 μm), acting through a nitric oxide (NO)-like mechanism, was significantly potentiated by co-incubation with cloricromene (5 μM). In addition, cloricromene enhanced the antiplatelet activity of the NO-like factor released by peritoneal rat polymorphonuclear cells. Thus, the present results show that cloricromene possesses direct antiplatelet properties and synergizes with other endogenous as well as exogenous antiplatelet compounds.

Chemiluminescence properties of human, canine and rat polymorphonuclear cells

Human as well as canine and rat polymorphonuclear cells (PMN) were separated from whole blood by centrifugation. Two-step discontinuous Percoll gradients with distinct different densities were used. The chemiluminescence properties of the isolated PMN and of phagocytes in small quantities of whole blood were compared in luminol-enhanced assays after stimulation with various agents: non-opsonized zymosan (3.5 g/l), phorbol myristate acetate (PMA, 2.8 x 10(-6) mol/l), calcium ionophore A 23187 (10(-5) mol/l) and N-formyl-methionyl-leucyl-phenylalanine (FMLP, 3.5 x 10(-6) mol/l). The isolated cells of the three species responded to all of the various stimuli. Species-related sensitivity could be ordered: human greater than canine greater than rat. Response to the various agents in the human cells can be ranked: PMA greater than or equal to A 23187 greater than zymosan greater than FMLP; for the dog: A 23187 greater than PMA greater than zymosan greater than FMLP; and for the rat: zymosan greater than or equal to PMA greater than FMLP greater than or equal to A 23187. Time course and peak maximum response were different upon stimulation in the absence and presence of autologous plasma. Distinct soluble stimuli resulted in maximum responses below the baseline in the whole blood assays with canine (FMLP) and rat (FMLP, A 23187) phagocytes.

Polyphosphoinositide metabolism in healthy and burned rat polymorphonuclear cells (PMNs). Effect of the immunomodulator RU 41740

Polyphosphoinositide metabolism in healthy and burned rat polymorphonuclear cells (PMNs). Effect of the immunomodulator RU 41740

Separation and chemiluminescence properties of human, canine and rat polymorphonuclear cells

Human as well as canine and rat polymorphonuclear cells (PMN) were separated from whole blood by centrifugation. Two-step discontinuous Percoll gradients with distinct densities were used. The purity of the preparations was 99.2%, 98.4% and 97.9%, respectively and the corresponding recoveries were 80.1; 66.3% and 69%. The chemiluminescence properties of the isolated PMN and of phagocytes in small quantities of whole blood were compared in luminol-enhanced assays after stimulation with various agents: non-opsonized zymosan (3.5 g/l), phorbol myristate acetate (PMA, 2.8 × 10 −6 M), calcium ionophore A 23187 (10 −5 M) and N-formyl-methionyl-leucyl-phenylalanine (FMLP, 3.5 × 10 −6 M). The isolated cells of the three species responded to all of the various stimuli. Species-related sensitivity followed the order: human > canine > rat. Responses to the various agents in the human cells was ranked: PMA ≥ A 23187 > zymosan > FMLP; for the dog: A 23187 > PMA > zymosan > FMLP; and for the rat: zymosan ≥ PMA > FMLP ≥ A 23187. Time courses and peak maximum responses were different following stimulation in the absence or presence of autologous plasma. Distinct soluble stimuli resulted in maximum responses below the baseline in the whole blood assays with canine (FMLP) and rat (FMLP, A 23187) phagocytes.

11] Purification of PGH-PGD isomerase from rat brain

This chapter describes the isolation and purification of the specific prostaglandin (PG) H-PGD isomerase from rat brain. In purification procedure 60 g of rat brains were cut into small pieces and mixed with 300 ml of 20 mM potassium phosphate buffer, pH 6.0, containing 0.5 mM dithiothreitol. The mixture was homogenized using a Polytron blender homogenizer. Further, steps are (1) acetone fractionation, (2) chromatography on phosphocellulose, (3) chromatography on diethylaminoethyl-cellulose, (4) ammonium sulfate fractionation, and (5) gel filtration on sephadex G-200. Approximately 1500-fold purification was achieved with a yield of 40%. The final preparation has a specific activity of about 1.8 units per milligram of protein. The activity of PGH-PGD isomerase is determined by measuring the production of [1- 14 C]PGD 2 from [1- 14 C]PGH 2 after separation of substrate and product by thin-layer chromatography. In addition to rat brain, PGH-PGD isomerase activity is demonstrated in several other tissues, including rat spleen, rat mastocytoma, rat polymorphonuclear cells, and human blood platelets.

Studies on the phagocytic activity of human and rat polymorphonuclear cells exposed to doxycycline in vivo.

Studies are presented on the in vitro phagocytic activity of rat and human polymorphonuclear leukocytes exposed in vivo to therapeutic concentrations of doxycycline. A 32P-labelled strain of Escherichia coli served as test microbe. No significant reduction of ingestion was observed although untreated AB leukocytes tested together with serum containing doxycycline showed a nonsignificant reduction in ingestive capability (p = 0.1). A similar pattern was observed when rat polymorphonuclear cells were tested omitting serum during the ingestion phase. In the presence of serum no effects were observed. During the elimination phase (3 h) both rat and human PMN eliminated breakdown products more extensively than controls, the effect observed on human PMN being most pronounced by the use of serum containing doxycycline.

The Effect of Eight Antibacterial Agents on the Elimination of32P-Labelled Escherichia Coli by Rat Polymorphonuclear Cells

The effect of 8 antibacterial agents on the elimination of 32P-labelled Escherichia coli from rat polymorphonuclear cells was studied. None of the drugs tested had a detectable influence on the expulsion of labelled products from the cells being exposed to the various drugs during the elimination phase.

The Effect of Eight Antibacterial Agents on the Phagocytosis of32P-Labelled Escherichia coli by Rat Polymorphonuclear Cells

Using 32P-labelled Escherichia coli, the effect of 8 antibacterial agents on the ability of rat polymorphonuclear cells to ingest the labelled bacteria was studied with and without serum present during the ingestion phase. No impairment of ingestion was observed when testing gentamicin, cephalothin and trimethoprim. High doses of oxytetracycline, doxycycline, colistin, erythromycin and chloramphenicol seemed to impair ingestion. The effect was most pronounced when applying 100 mug/ml of doxycycline: the ingestive capability was reduced to 25% without serum and 24% with serum present compared to untreated controls. 83 mug/ml of colistin reduced theingestion to 39% without serum present, this effect being totally eliminated when serum was present during the ingestion phase.