No abstract

Interleukin-6 (IL-6) is a multifunctional cytokine that regulates the immune response, acute phase anaphylactic reaction, and haematopoiesis. Lipopolysaccharide (6–24 μg/ml) significantly induced IL-6 release from murine spleen cells. In cultured rabbit synovial cells interleukin-1 (IL-1, 1–10 U/ml) induced IL-6 production in a concentration-dependent manner. Triazolodiazepine (Tri) is a hetrazepine platelet-activating factor antagonist. In this study we found that Tri (0.1–10 μmol/l) exerted strong inhibitory effects on LPS stimulated IL-6 production in murine spleen cells. Kinetic studies showed that the inhibition of IL-6 release was time-independent. In rabbit synovial cells Tri also reduced IL-6 release induced by IL-1 and tumour necrosis factor. Inhibition of cytokine production by Tri may partially explain its wide and strong anti-inflammatory effects.

Esculentoside A (EsA) is a saponin isolated from the roots of Phytolacca esculenta. Previous experiments have shown that it has strong antiinflammatory effects. To investigate the mechanism of anti-inflammatory effects of esculentoside A (EsA),[3H] arachidonic acid (AA) prelabelled murine macrophage and radioimmunoassay were used to test the effect of EsA on the total release of AA and prostaglandin E2 in culture supernatants. The results showed that EsA had no significant effect on the total release of AA from murine macrophages. EsA (2.5-10 μmol/l), from unstimulated murine peritoneal macrophages and rabbit synovial cells, could decrease the production of prostaglandin E2. In A23187 and LPS-treated macrophages and synovial cells, EsA (10 μmol/l) could significantly decrease the prostaglandin E2 production. These results confirmed that EsA exerted an inhibitory effect on prostaglandin E2 production from murine macrophages and rabbit synovial cells.

Esculentoside A (EsA) is a saponin isolated from the roots of Phytolacca esculenta. Previous experiments have shown that it has strong anti-inflammatory effects. Tumour necrosis factor (TNF) is a very important inflammatory mediator. It is known that there are two types of TNF—TNFα is from macrophages/monocytes and TNFβ is from activated lymphocytes. In order to study the mechanism of the anti-inflammatory effect of EsA, it was determined whether TNFα production from human peripheral monocytes was altered by EsA under lipopolysaccharide (LPS)-stimulated conditions. EsA was found to decrease TNFα production in a dose-dependent manner at concentrations higher than 1 μmol/l EsA. Recent studies have shown that EsA has a curative effect on chocolate cyst and other inflammatory diseases. Our previous studies have shown that EsA could reduce the release of platelet activating factor (PAF) from rat macrophages, and inhibit interleukin-1 and interleukin-6 production from routine macrophages. The reducing effects of EsA on the release of TNFα, IL-1, IL-6 and PAF may explain its anti-inflammatory effect.

In this study it is reported that: (1) the levels of blood platelet-activating factor and serum tumour necrosis factor significantly increased after coronary ligation and reperfusion, compared with sham-ligated controls, in an anaesthetized rat model; (2) compared with vehicle controls, pretreatment with the PAF antagonist BN 50739 (10 mg/kg, i.v.) produced significant decreases in infarct size (from 29.6 ± 4.0% to 22.4 ± 2.1%, p < 0.05 after 3 h ligation, and from 28.5 ± 9.5% to 10.5 ± 4.5%, p < 0.01 after 4 h reperfusion) and the level of serum TNF (from 10.4 ± 7.7 U/ml to 3.9 ± 4.8 U/ml, p < 0.05); and (3) a significan positive correlation was found between the level of blood PAF or serum TNF and infarct size. The present results indicate that PAF and TNF may be important mediators involved in myocardial ischaemia and reperfusion injury, and that PAF antagonists may exert a protective effect on ischaemic or reperfused myocardium by inhibiting the interaction of PAF and TNF.