Andrographolide抑制LPS/IFN-gamma誘發血管平滑肌細胞轉錄因子NF-kappaB活化之分子機轉探討

先前研究發現穿心蓮萃取物之主要有效成分andrographolide(3-(2-(decahydro-6-hydroxy-5-(hydroxymethyl)-5,8a-dimethyl-2-methylene-1-napthalenyl)ethylidene)dihydro-4-hydroxy-2(3H)-furanone)可以藉由抑制轉錄因子NF-kappaB之活化而降低脂多醣體(lipopolysaccharide，LPS)及干擾素(interferon-gamma，IFN-gamma)引發大鼠血管平滑肌細胞發炎因子NO及MMP-9的表現，並改善氣球擴張術引發大鼠血管內膜過度增生的情形。本篇論文更深入的探討andrographolide抑制大鼠血管平滑肌細胞中轉錄因子NF-kappaB活化之分子機轉。研究結果發現，在大鼠血管平滑肌細胞中事先給予andrographolide (20 microM及50 microM)可有效抑制LPS及IFN-gamma引發轉錄因子NF-kappaB之活化，而其分子機轉並非經由影響NF-kappaB抑制蛋白IkappaB-alpha的降解作用而來，可能是NF-kappaB的組成蛋白p65向細胞核內轉移的現象受到影響造成下游基因活化受阻所致；此外andrographolide亦會抑制LPS/IFN-gamma誘發p65Ser536 磷酸化、JNK及Akt磷酸化之表現，但不影響IKK、p65Ser276、p38磷酸化及ERK磷酸化之表現。接下來的研究更進一步探討andrographolide抑制p65轉移之詳細分子機轉與JNK以及Akt之間的關係，發現在VSMCs使用Akt抑制劑以及JNK抑制劑(SP600125)，皆不影響LPS/ IFN-gamma所引發磷酸化p65Ser536之蛋白表現，然而protein phosphatase抑制劑(okadaic acid)能夠拮抗andrographolide的抑制作用，使得p65Ser536的活化情形回升。本研究發現，andrographolide可藉由增加phosphatase活性去抑制p65Ser536之磷酸化進而影響 NF-kappaB 的活化，但詳細的藥物作用機轉仍有待進一步討論。

關鍵字

血管平滑肌細胞；脂多醣體；干擾素

並列摘要

Andrographolide is the major purified bioactive compound of Andrographis paniculata. It was repeated to attenuate the expression of nitric oxide (NO) and MMP-9 production stumilated by bacterial lipopolysaccharide (LPS) and interferon-gamma(IFN-gamma) on cultured primary vascular smooth muscle cells (VSMCs) though down-regulating transcription factor NF-kappaB signal activation, and is valuable for preventing and treating thrombotic arterial diseases, including neointimal hyperplasia in arterial restenosis. In the present study, we investigated the mechanisms of andrographolide in inhibition of NF-kappaB translocation and inflammatory effects stumilated by bacterial lipopolysaccharide and interferon-gamma on cultured primary VSMCs. We found that andrographolide inhibit p65 translocation into nuclear but no effect on IkappaB-alpha degradation. Andrographolide inhibited phospho-p65Ser536, phospho-JNK, and phospho-Akt but no effect on phospho-IKK、phospho-p65Ser276、phospho-p38 and phospho-ERK. We also investigated the mechanism of andrographolide in inhibition of p65 translocation through Akt and JNK pathway. Akt inhibitor and JNK inhibitor, SP600125, were no effect on phospho-p65Ser536, however, pretreating with protein phosphatase inhibitor, okadaic scid, reversed the inhibition of phospho-p65Ser536 by andrographolide on VSMCs. Additionally, andrographolide enhanced the activity of phosphatase and inhibited NF-kappaB signal activation. The more detailed anti-inflammatory mechanisms of andrographolide in VSMCs remain unclear, and need to be futher investigated.

並列關鍵字

andrographolide ； lipopolysaccharide ； interferon-gamma ； nf-kappa B ； VSMC

參考文獻

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Andrographolide抑制LPS/IFN-gamma誘發血管平滑肌細胞轉錄因子NF-kappaB活化之分子機轉探討

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