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Biomedical subjects

M E Goldyne

Publications and source records attributed to M E Goldyne.

At least 37 records · Page 2Linked to original sources

A novel eicosanoid is the major arachidonic acid metabolite of cultured human monocytes.

Human peripheral blood monocyte-macrophages (M phi) generate a novel eicosanoid during in vitro culture. The metabolite is generated during incubation of the cells with 14C - arachidonic acid (AA). Lack of prior recognition of this metabolite probably results from the facts that: 1) on thin-layer chromatography (TLC) in two standard solvent systems, the novel metabolite co-chromatographed with either prostaglandin D2 or thromboxane B2, and 2) its generation, under the conditions studied, does not occur until between 90 and 180 minutes after culture initiation which is a time period beyond that used for most leukocyte studies. The generation of the metabolite is inhibited by nordihydroguaiaretic acid (NDGA) but not by indomethacin. Base hydrolysis did not alter its migration on TLC. On both reversed phase and straight phase high pressure liquid chromatography (HPLC), the novel peak isolated by TLC elutes as a single major peak of radioactivity with a retention time different from the known leukotrienes, hydroxy acids, or their metabolites. Furthermore, the peak isolated on HPLC has a single ultraviolet absorption maximum at 270 nm. M phi cultured for 1 week prior to a 24 hour incubation with 14C-AA generated proportionally less of the novel eicosanoid (roughly 68% of total radiolabeled product) than did M phi cultured for 3 weeks prior to a similar incubation with 14C-AA (roughly 86% of total radiolabeled product). Under the conditions studied, the novel eicosanoid is the major AA metabolite generated from exogenous AA by cultured M phi and it appears to be generated in increasing quantity as the M phi differentiate.

Arachidonic Acid↗

Arachidonic acid metabolism among human mononuclear leukocytes. Lipoxygenase-related pathways.

Human peripheral blood mononuclear cells were isolated and assessed for the presence of contaminating polymorphonuclear leukocytes and platelets. Incubations of these cell isolates were performed in the presence or absence of the calcium ionophore A23187 and/or 1-14C-labeled or unlabeled arachidonic acid. Using reverse phase high pressure liquid chromatography with simultaneous monitoring of ultraviolet light absorption at 229 and 280 nm and, where appropriate, of radioactivity, our studies reveal that human peripheral blood mononuclear cells generate leukotrienes C4 and B4 (LTC4 and LTB4) and 5-hydroxyeicosatetraenoic acid (5-HETE) following stimulation with A23187. The ratio of LTC4 to LTB4 was approximately 10-fold greater among the mononuclear cells than among similar incubations of polymorphonuclear leukocytes. Furthermore, the mononuclear cells failed to metabolize LTB4 into the omega-hydroxy or omega-carboxy derivatives that were always present in, and very characteristic of incubations of polymorphonuclear leukocytes. Depletion of monocytes from the mononuclear cells by double adherence resulted in virtual loss of the generation of 5-lipoxygenase-derived products by the remaining nonadherent cells, supporting the conclusion that the monocytes and not the lymphocytes were the source of LTC4, LTB4, and 5-HETE. The presence of both 12-HETE and the cyclooxygenase-derived 12-hydroxyheptadecatrienoic acid correlated with the degree of platelet contamination, suggesting that the platelets account for the presence of these compounds.

Arachidonic Acids↗

Heterogeneity in leukocyte preparations: effects on defining eicosanoid metabolism by human lymphocytes and monocytes.

The capacity of preparations of human monocytes and lymphocytes to generate lipoxygenase products of arachidonic acid is largely attributable to platelet and occasionally to neutrophil contamination. Removal of platelets by several techniques eliminates the lipoxygenase activity of lymphocytes and substantially diminishes that of monocytes. The definition of profiles of lipoxygenation for each type of leukocyte will increase the meaning of studies of cell-cell interactions.

Arachidonate Lipoxygenases↗

Leukotrienes: clinical significance.

The leukotrienes, so named because of their initial identification in leukocyte preparations and the presence of three conjugated double bonds (a conjugated triene), are metabolites of the same polyunsaturated fatty acids (e.g., arachidonic acid) that give rise to the prostaglandins, thromboxanes, and several other families of biologically active lipids. Their potential clinical importance derives from their effects on vascular and other smooth muscle reactivity and on leukocyte function. Several leukotrienes may markedly influence the cellular and vascular responses that constitute an integral part of hypersensitivity and inflammatory reactions of the skin. Preliminary data from several laboratories have been presented that implicate a specific leukotriene in the evolution of the lesions of psoriasis.

Arachidonic Acid↗

Prostaglandin E is required for the augmentation of procoagulant activity of LPS-stimulated rabbit alveolar macrophages.

We demonstrated previously that rabbit alveolar macrophages stimulated in vitro by bacterial lipopolysaccharide (LPS) have markedly enhanced procoagulant activity (PCA), caused by increased production of a cell-associated tissue thromboplastin. The present study examined the role of arachidonic acid metabolites in modulating the expression of this PCA. Alveolar macrophages lavaged from normal rabbits were incubated in vitro with LPS, indomethacin, and purified prostaglandins, and the resultant PCA was measured. LPS stimulated a significant increase in macrophage PCA relative to unstimulated controls (p less than 0.01). Indomethacin suppressed the ability of LPS to stimulate PCA in a dose-related fashion. The addition of PGE2 or PGE1 reversed the suppressive action of indomethacin (p less than 0.01), whereas PGF2 alpha, PGD2, TXB2, and 6-keto PGF1 alpha had no such effect. PGE2 did not affect PCA unless the macrophages were also stimulated with LPS. A significant correlation (rs = 0.72, p less than 0.01) existed between the level of LPS-stimulated macrophage PCA and the corresponding amount of immunoreactive PGE2 released into the culture medium. The results of this study demonstrate that PGE is required for the LPS-mediated enhancement of rabbit alveolar macrophage-associated tissue thromboplastin and that PGE can stimulate the expression of PCA by appropriately conditioned cells.

Animals↗

Human monocytes synthesize eicosanoids from T lymphocyte-derived arachidonic acid.

T lymphocytes prelabeled with [14C] arachidonic acid failed to synthesize any eicosanoids even following stimulation with phytohemagglutinin, but they did release free [14C] arachidonic acid. Co-culture of unlabeled monocytes with the prelabeled T lymphocytes resulted in the synthesis of [14C] thromboxane B2, a major monocyte-derived eicosanoid. These data show that monocytes can utilize T lymphocyte-derived arachidonic acid for the synthesis of eicosanoids.

Arachidonic Acid↗

In vitro synthesis of prostaglandins and related lipids by populations of human peripheral blood mononuclear cells.

This report focuses on the identification of the human peripheral blood mononuclear cells that do or do not produce prostaglandins (PGs) and related arachidonic acid metabolites. Our results, using two different assay systems, indicate that the monocyte/macrophage (Mphi) is the major and possibly sole source of thromboxane (TXB2) and prostaglandin E2 (PGE2) among peripheral blood mononuclear cells. Adherent peripheral blood monocytes (> 95% esterase positive) produced substantial amounts of these compounds. Quantitation of products which had incorporated exogenous 14C-arachidonic acid and radioimmunoassay of adherent cell culture fluids demonstrated that the amount of TXB2 produced by these cells was appreciably greater than the amount of PGE2 produced. Additional confirmation of TXB2 synthesis was shown by abolishing the TXB2 peak on TLC and TXB2 activity detected by RIA by treating cells with a specific inhibitor of thromboxane synthetase. In contrast, non-adherent T cells failed to synthesize either PGE2 or TXB2. Non-adherent B cells (95% Ig positive) incubated with 14C-arachidonic acid produced a small peak of radioactivity co-chromatographing with TXB2, and no PGE. All three cell populations incorporated similar amounts of 14C-arachidonic acid into hydroxy-fatty acids. We were unable to detect 6-keto-F1 alpha, the hydrolysis product of prostacyclin (PGI2) in any of the cell types tested. The absence of PG synthesis among normal peripheral blood T and B cells was also noted among established human lymphoid cell lines. Neither a human T (CCRF), nor a human B-cell line (GM-130), produced PGE2 or TXB2. Three murine macrophage cell lines, P388D1, J774.2, and WEHI-3 produced PGE2 and the latter TXB2 as well.

Animals↗

Endogenous synthesis of prostaglandins E1 and I2 in 3T3 fibroblasts transformed by polyoma virus. Effects on adenosine 3':5'-monophosphate production.

Prostaglandins (PG)E1, E2 and I2 were produced by polyoma virus transformed (py) 3T3 fibroblasts. The levels of PGE1, PGE2 and 6-keto-PGF1 alpha (degradation product of PGI2) were 22.7, 225 and 33.2 ng/ml medium, respectively, 72 h after medium change. The stimulatory potencies of exogenous PGE1, PGE2 and PGI2 on adenosine 3':5'-monophosphate (cyclic AMP) formation were similar. Therefore, the prostaglandin mediated increase in cyclic AMP levels observed during growth of these cells (Claesson, H.-E., Lindgren, J.A. and Hammarström, S. (1977) Eur. J. Biochem. 74, 13) is largely (greater than 80%) mediated by PGE2 and to lesser extents by PGE1 and PGI2.

8,11,14-Eicosatrienoic Acid↗

Prostaglandin E2 as a modulator of macrophage-T lymphocyte interactions.

Sufficient data exist to implicate the monocyte-macrophage as the major source of prostaglandins in monocyte-macrophage-T lymphocyte interactions. Prostaglandin (PG) E2, a major prostaglandin synthesized by human monocyte-macrophages is able to modulate a variety of T lymphocyte reactivities including blastogenesis, lymphokine secretion, and cytotoxicity. The effect of PGE2 on T lymphocyte function varies according to the primary activating stimulus, the specific response under investigation, as well as the population of T lymphocytes involved. Some immunologic abnormalities found in clinical disease may in part derive from alterations occurring in the synthesis of PGE2 by monocyte-macrophages or in the response of T lymphocytes to PGE2.

Humans↗

Synthesis of prostaglandins by subpopulations of human peripheral blood monocytes.

The ability of monocytes/macrophages to regulate various aspects of immunologic responses may in part depend on their release of soluble substances such as prostaglandins. Using quantitative gas-liquid chromatography/mass spectrometry, prostaglandin E2 was found to be the major prostaglandin synthesized in culture by human peripheral blood monocytes. Subjecting these cells to discontinuous density gradient fractionation demonstrated significant differences in the synthesis of prostaglandins E2 and E1 among the resulting monocyte subpopulations.

Cells, Cultured↗

Prostaglandin E modulation of the mitogenic response of human T cells. Differential response of T-cell subpopulations.

Prostaglandins (PG) of the E series, PGE(1) and PGE(2) (PGEs), can induce elevations of intracellular cyclic AMP (cAMP) among thymus-derived (T) lymphocytes (T cells) and inhibit their reactivity. For example, 0.1 muM of PGEs induces a two- to threefold increase of intracellular cAMP among human peripheral blood T cells and a 20-30% suppression of their blastogenic response to phytohemagglutinin. However, this suppression actually represents the net reactivity of T-cell populations demonstrating quite different responses to PGEs. Fractionation of T-enriched populations on a discontinuous density gradient yields a population of high density cells whose phytohemagglutinin-induced blastogenic response is suppressed 60%; a population of intermediate density cells whose response is suppressed 20%; and a population of low density T cells whose response is not suppressed, but is enhanced 20% by both of the PGEs. The diametrically opposite responses of low and high density T cells to the PGEs is not related to any difference in their intrinsic mitogen reactivity nor is it influenced by interactions with other T cells, bone marrow-derived (B) cells, or monocytes. Moreover, the distinct blastogenic response of low and high density T cells to PGEs does not simply correlate with PGE-mediated activation of adenylate cyclase. PGE(2) induced comparable absolute and identical relative increases of intracellular cAMP among the low and high density T cells. Cholera toxin, a potent activator of adenylate cyclase, and exogenous 8-bromo cAMP mimicked the effects of the PGEs on these two T-cell populations. These data demonstrate that T cells are heterogeneous with regard to their response to the PGEs. Thus, PGEs should be considered as potential regulators rather than as universal suppressors for T-cell reactivity. Moreover, the effect of PGEs on the blastogenic response of a given T-cell population depends upon intracellular events which occur subsequent to elevations of cAMP.

Cell Count↗