脂蛋白（a）对肾小球系膜细胞的作用

目的探讨脂蛋白（ａ）［Ｌｐ（ａ）］对肾小球系膜细胞（ＧＭＣ）的作用。方法将体外培养的系膜细胞，加脂蛋白（ａ）刺激后，测定细胞生长率和细胞上清中血小板活化因子（ＰＡＦ）、肿瘤坏死因子（ＴＮＦ）、乳酸脱氢酶（ＬＤＨ）及纤维连结蛋白（ＦＮ）水平，并以未经刺激者作对照。结果经脂蛋白（ａ）刺激４８小时，在终浓度５～２０ｍｇ／Ｌ时细胞生长率轻度增加，而在５０～４００ｍｇ／Ｌ时细胞生长率明显下降。刺激１８小时，细胞上清中ＰＡＦ的水平明显高于对照，且与脂蛋白（ａ）浓度呈明显正相关（ｒ＝０．９３７，Ｐ＜０．０１）；Ｌ９２９细胞的杀伤率有所增加，但未达５０％；ＬＤＨ的水平在脂蛋白（ａ）１００ｍｇ／Ｌ以下时有所增加；刺激１８、４８、７２小时后的细胞上清纤维连结蛋白均为阴性。结论脂蛋白（ａ）对系膜细胞体外增殖有低浓度轻度促进、高浓度抑制的双向作用，对细胞ＰＡＦ的产生具有浓度依赖的促进作用，并能增加细胞上清中ＬＤＨ及ＴＮＦ水平，因而可通过多种途径介导肾小球损伤。     

Anti-inflammatory effects of hydroalcoholic extract and two biflavonoids from Garcinia gardneriana leaves in mouse paw oedema

Garcinia gardneriana (Planch. & Triana) Zappi (Clusiaceae) is widely distributed in Brazil and used in folk medicine to treat inflammation, pain, and urinary tract and other infections. However, very few studies have analyzed these therapeutic effects. In this study, the anti-inflammatory effects of the hydroalcoholic extracts from Garcinia gardneriana (HEGG) and some of its isolated biflavonoids were evaluated. The results showed that HEGG from the leaves, bark and seeds reduced carrageenan-induced mouse paw inflammation, in addition to diminishing the myeloperoxidase activity in the stimulated tissues. The reduction of neutrophil infiltration by treatment with the HEGG from leaves was confirmed by histology. The leaf extract also reduced the paw oedema evoked by bradykinin, histamine, prostaglandin E2 and 12-O-tetradecanoylphorbol acetate. However, it partially decreased substance P and compound 48/80-caused paw oedema, without any influence on the arachidonic acid-induced oedema. Both of the isolated compounds, fukugetin and GB-2a, prevented the carrageenan-induced paw oedema. In conclusion, this study showed important anti-inflammatory effects of HEGG through its interaction with different intracellular signaling pathways, without interfering with the formation of arachidonic acid (AA) metabolites. These characteristics, in addition to the wide distribution and culturing ease of the plant, confirm its popular use and highlight its promise in the development of new anti-inflammatory drugs.     

The effect of the selective PAF antagonist CIS-19 on PAF- and antigen-induced bronchoconstriction, microvascular leakage and bronchial hyperreactivity in guinea-pigs

We investigated the effects of a novel platelet-activating factor (PAF) receptor antagonist, CIS-19 [cis-2-(3, 4-dimethoxyphenyl)-6-isopropoxy-7-methoxy-1-(N-methylformamido)-1, 2, 3, 4-tetrahydronaphthalene], on PAF-, histamine-, substance P- and antigen-induced bronchoconstriction and microvascular leakage, as well as PAF- and antigen-induced bronchial hyperreactivity to methacholine in urethane-anesthetized guinea-pigs. Administration of CIS-19 (0.5–5 mg/kg, i.v.) inhibited the increase in lung resistance induced by PAF (30 ng/kg, i.v.) in a dose-dependent manner, but failed to inhibit the increase induced by histamine (30 μg/kg, i.v.) or substance P (6.5 μg/kg, i.v.). CIS-19 (5 mg/kg, i.v.) did not inhibit the increase in lung resistance induced by ovalbumin (2 mg/kg, i.v.) in actively sensitized guinea-pigs. PAF (30 ng/kg, i.v.)-induced microvascular leakage, measured by the extravasation of Evans blue dye, was dose-dependently inhibited by CIS-19 (0.5–5 mg/kg, i.v.) in the trachea, main bronchi and intrapulmonary airways, but it did not affect histamine (30 μg/kg, i.v.)- or substance P (6.5 μg/kg, i.v.)-induced microvascular leakage at all airway levels. CIS-19 (2.5 and 5 mg/kg) did not affect ovalbumin (2 mg/kg, i.v.)-induced microvascular leakage in all airway levels in actively sensitized guinea-pigs. CIS-19 (2.5 and 5 mg/kg, i.v.) significantly inhibited PAF-induced enhancement of the bronchial response to methacholine, but had no effect on ovalbumin (0.05 mg/kg, i.v.)-induced bronchial hyperreactivity in actively sensitized guinea-pigs. It is concluded that CIS-19 is a potent PAF receptor antagonist which inhibits PAF- but not antigen-induced bronchoconstriction, microvascular leakage and bronchial hyperreactivity. These results suggest that PAF plays little or no role in early airway responses following antigen challenge. Received: 29 April 1996 / Accepted: 10 October 1996     

PAF antagonistic activity of 2-hydroxy-3-methoxybenzoic acid glucose ester fromGentiana scabra

In order to find out anti-platelet activating factor (PAF) from natural resources, Korean medicinal plants used for the treatments of peripheral circulation disorders were tested for their possible protective effects on PAF-induced anaphylactic shock. From the above screening, the methanol extract ofGentiana scabra showed a potent antagonistic activity against PAF. Water suspension of the extract was partitioned with CH₂Cl₂ and EtOAc, successively. The EtOAc fraction which showed the highest activity was chromatographed on silica gel to yield 6 fractions. From the fraction which showed higher PAF-antagonistic activity than the other fractions, compound1 was isolated by recrystallization. On the basis of spectral data, compound1 was identified as 2-hydroxy-3-methoxybenzoic acid glucose ester. The compound prevented the mice from the PAF-induced death at a dose of 300 μg/mouse.     

Immunoregulatory Effect of Substance P in Human Eosinophil Migratory Function

Substance P (SP) is a tachykinin involved in the regulation of inflammatory processes. To investigate a modulatory role of the neuropeptide SP in allergic inflammation, we studied its priming effect on human eosinophil chemotaxis and kinetic responses towards platelet activating factor (PAF) and recombinant human interleukin 5 (rhlL-5). Blood was obtained from normal subjects and eosinophils were separated by Percoll discontinuous density gradient centrifugation. High purification was obtained by negative selection procedure (CD16-beads) and the experiments were performed in a 48-well microchemotaxis Boyden chamber. In the present study we demonstrate a potent synergistic effect of 100nM dose of SP on the migratory function of human eosinophils stimulated by PAF and rhIL-5. This synergism was chemotaxis specific and was abolished by NK-1 receptor antagonist (FK888). The results suggest that neurogenic stimuli may play a significant role in eosinophil infiltration via its priming effect on the cell.     

Eosinophil migration in response to three molecular species of platelet activating factor

Multiple molecular species of the eosinophil chemoattractant platelet activating factor (PAF) are produced as a result of inflammatory processes. We therefore compared the ability of three naturally occurring PAF species (C160, C180, and C181), which only varied at carbon 1, to induce eosinophil chemotaxis through naked 3-m pore polycarbonate filters. Timecourse experiments indicated that all species of PAF tested induced significant and equivalent eosinophil migration at 1 h which peaked at 2 h. Overall, the rank order of chemotactic potency for the PAF species was relatively equivalent. The specific PAF antagonist WEB 2086 inhibited eosinophil migration induced by all three PAF species equally. We conclude that the degree of PAF-induced eosinophil migration is not dependent upon the molecular species of PAF.accepted by G. W. CarterThis work was supported in part by a Veterans Administration Merit Review Award.     

Generation of the eosinophil chemotactic factor (ECF) from various cell types by melittin

The peptide melittin, the main constituent of bee venom is a potent stimulus for the generation of an eosinophil chemotactic factor (ECF) from human polymorphonuclear neutrophils, rat mast cells and rat peritoneal cells depleted in mast cells. Optimal EFC induction required a sublytic activation of the cells. With each cell type the kinetics of ECF generation were similar in that after an early rise in activity a steep fall off occurred at later times of incubation suggesting a mechanism of inactivation. The induction of ECF by melittin is increased in the presence of calcium. The polar portion of the melittin molecule (aminoacids 20–26) is responsible for the generation of the chemotactic activity. Other peptides of honey bee venom such as the mast cell degranulating peptide (MCD) or apamine do not initiate ECF release. It appears that melittin leads to ECF induction via the phospholipase A₂-arachidonic acid dependent pathway of cell activation. Our data suggests that the lipid mediator ECF can be obtained from phagocytes and mast cells thus indicating the interdependence of inflammatory reactions.     

Release of histamine in whole blood by oxygen radicals: Division between specific and unspecific processes

Oxygen derived free radicals are involved in many pathological processes such as postischemic reperfusion injuries, hepatotoxicity of drugs and inflammatory processes. Thereby these oxygen radicals induce lipid peroxidation and perturbation of cellular membranes. The aim of our present study was to determine whether oxygen radicals generated by the xanthine oxidase/hypoxanthine system cause a release of histamine in human blood cell cultures. Stimulation of blood cell cultures with oxygen radicals induced a histamine liberation which was mainly due to calcium independent processes during the first 30 min, whereas then calcium requiring processes took part in the release of histamine. The regulation of the leukocyte selectin LECAM-1 was altered by oxygen radicals whereas histamine, which is known to modulate vascular selectin expression, did not affect the expression of LECAM-1. Our data indicate that oxygen radicals induce a direct calcium independent release of histamine which is due to membrane pertubating processes during the first phase but also induce a specific reaction leading to a further indirect histamine liberation which is probably mediated by PAF.accepted by W. LorenzThe first two authors contributed equally to this paper.     

TCV-309, a novel platelet activating factor antagonist,inhibits leukocyte accumulation and protects against splanchnic artery occlusion shock

The aim of this study was to evaluate: (1) the accumulation of leukocytes in the ileum and the lung during splanchnic artery occlusion (SAO) shock; (2) the role of platelet-activating factor (PAF) and tumor necrosis factor (TNF-) in this phenomenon. Untreated anesthetized rats subjected to total occlusion of the celiac, superior and inferior mesenteric arteries for 45 min, followed by reperfusion, uniformly died within 90 min after reperfusion. The mean survival time was 93±7 min. The neutrophilic infiltrate was quantitated in the ileum and in the lung using a myeloperoxidase (MPO) assay. MPO activity in the ileum and in the lung averaged 0.05±0.03 and 0.4±0.02 U×10^–3/g protein in animals killed before occlusion. MPO activity did not change in rats killed immediately before reperfusion and was significantly elevated (0.11±0.02 and 1.7±0.6 U×10^–3/g protein in the ileum and the lung, respectively) in those killed 80 min after the beginning of the reperfusion. The histological examination confirmed the accumulation of leukocytes in the mucosa of the ileum and the lung over the 80 min. SAO shocked rats exhibited leukopenia and increased serum levels of TNF-. In order to evaluate the role of PAF and TNF- in SAO shock, a powerful PAF receptor antagonist, TCV-309 (5 g/kg i.v.), was injected 5 min after reperfusion. TCV-309 increased survival time, lowered serum TNF-, reduced MPO activity in both the ileum and the lung and ameliorated leukopenia induced by SAO shock. In addition, the drug significantly reduced ileal necrosis and pulmonary morphological alterations induced by shock. These results suggest an important role for PAF in the adhesion of leukocytes in SAO shock.     

细胞因子对肾小球系膜细胞合成PAF的影响

本文首先建立了血小板活化因子（ＰＡＦ）的生物活性检测法，并通过体外细胞培养技术，测定了肾小球系膜细胞在经ＬＰＳ、ＩＬ-１β、ＩＬ-６和ＴＮＦα的短暂刺激后，其培养上清中ＰＡＦ的活性。结果发现，它们均能诱导系膜细胞合成和分泌ＰＡＦ，ＩＬ-１β、ＩＬ-６和ＴＮＦα的诱生作用并呈一定的剂量依赖关系。实验提示上述因子在肾小球免疫病理损伤中，除直接作用外，也可通过诱生ＰＡＦ而间接发挥作用。应用ＰＡＦ拮抗剂来阻断这一途径，可能具有一定的临床应用价值。