| Part I : Effects of Dexmerhasone on Toll-like receptor(TLR)2 and 4 in CD14+ monocyte of patients during and after Cardiac surgery with cardiopulmonary bypassObjective: To investigate the kinetics processes of TLR2 and TLR4 in CD 14+ monocyte of patients during and after Cardiac surgery with cardiopulmonary bypass(CPB) and the effects of dexamethasone(DXM) on the regulation of TLR2 and 4 in CD14+ monocyte. Methods: Twenty patients undergoing elective atrial/ventricaular septal defect correction were randomized to received 1mg.kg-1 dexamethasone(DXM) or placebo(CON) before induction of anesthesia. The CD 14+ monocyte surface TLR2 and TLR4 and the intracellular HSP70 stained and analyzed by flow cytometry, and plasma level of TNF- a, IL-6, IL-10, NO and MDA were measured at the following times:before the dexamethasone or placebo were administer(Tl), before starting CPB(T2), immediately aortic declamping(T3), 30min after aortic declamping(T4), 5h after skin closure(T5) and 24h after skin closure(T6) Result: (1). The expression of CD 14+ monocyte surface TLR4 and the intracellular HSP70 of CD 14+ monocyte were upregulated after, with peak concentration T4; DXM could decrease the upregulation of TLR4 and HSP70.(2) The expression of CD14+ monocyte surface TLR2 gradually upregulated after and peaked at T6, DXM reduced the regulation significantly at T5 and T6(P<0.05). (3)Both the CD14+HSP70+TLR2+ monocytes and CD14+HSP70+TLR4+ monocytes were enhanced after induction of anesthesia, and peaked at T4. DXM decreased the expression of CD14+HSP70+TLR2+ monocytes and CD14+HSP70+TLR4+ monocytes(4)In the CON group, there was a significant elevation in TNF-a and IL-6 relative to the DXM group, The predominant changes occurred at T3~T4. IL-10 increased in both groups, with peak concentration at T4and lower values in CON than in DXM, the ratio of IL-10 to TNF-a was greater in DXM than in CON ㎞O in plasma increased in both groups with peak concentration at T4, MDA in plasma gradually increased with peak concentration at T6. There were lower values of both NO and MDA in DXM group than in CON group. Conclusion:(1)The release of endogenous danger signals such as HSP7O from damaged cells triggers signaling through TLR2 and TLR4 may contribute to the systemic inflammatory response syndrome after extracorporeal circulation (2)Dexamethasone may inhibit the release of endogenous danger signals such as HSP70 from damaged cells, and/or directly inhibit the upregulation of TLR2 and TLR4, then reduce the release of proinflammatory mediators such as TNF- a , IL-6 and NO, Dexamethasone may also suppress the immune response by increasing the anti-inflammatory mediators such as IL-10. (3) Blocking TLR2 and TLR4 function may become a potential therapeutic option for the systemic inflammatory response syndrome after extracorporeal circulation.Part II: Dexamethasone regulation of TLR2 and TLR4 gene expression in dog heart, lung, spleen and PBMC during cardiopulmonary bypassObjective: Further investigation the kinetics progress of TLR2 and TLR4 in tissues expression, especially in heart, lung, spleen and PBMC, during and after cardiopulmonary bypass (CPB) and the effects of dexamethasone (DXM) on the regulation of TLR2 and TLR4 in tissues by a dog experimental model with method of the real-time PCR based on SYBR Green I fluorescense. Methods: Ten healthy dogs were randomized to received 1mg.kg-1 dexamethasone(DXM) or saline solution (CON) before induction of anesthesia. After induction of anesthesia, a midline stemotomy began to open heart under sterile condition. And then systemicheparinizated(400 ug/kg), and the right atrium(RA) and aorta were cannulated. CPB was performed with no cardioplegic arresting and no mechanical ventilation, pump , flow of 3.5~4.5L.min-1 and mean arterial blood pressures of 50~70mmHg. 2 hour later, recovered, and stop CPB as maintaining a stabile hemodynamic. killed the animal after maintaining 2 hour. Tissues of heart, lung and spleen were cut with a size of 0.5cm3 and artery blood samples were taken... |
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