Molecular Mechanisms in Peptidoglycan-Induced Human Umbilical Vascular Endothelial Cell Apoptosis

肽聚醣誘導人類臍靜脈內皮細胞凋亡之機轉

張藏能(Tsrang-Neng Jang) ； 邱佩婷(Pei-Ting Chiu) ； 陳威銓(Wei-Chuan Chen) ； 許銘仁(Ming-Jen Hsu)

《藥物食品分析》 19卷2期 (2011/06) Pp. 159-166

摘要

革蘭氏陽性菌細胞壁成分肽聚醣(PGN)被認爲是革蘭氏陽性菌誘導敗血症相關併發症的主要分子，然而肽聚醣誘導血管內皮層功能喪失的致病機轉仍未完全釐清。此外ASK1蛋白被報導在許多不同刺激誘導細胞凋亡的過程中扮演重要角色，因此本研究主要是想探討革蘭氏陽性菌細胞壁成分肽聚醣是否可攫由活化細胞內ASK1蛋白而導致人類臍靜脈血管內皮細胞凋亡。我們發現肽聚醣可隨著濃度增加而降低細胞存活率，流式細胞儀分析更說明了肽聚醣可誘導血管內皮細胞凋亡，肽聚醣被證實可活化細胞內ASK1蛋白及其下游訊息分子p38MAPK蛋白，同時肽聚醣也會增加細胞內凋亡蛋白Bax的表現。另一方面，由於肤聚醣會結合至細胞上的TLR2受髓，因此我們也使用細胞TLR2受髓的致效劑Pam3CSK4，實驗發現Pam3CSK4和肽聚醣的作用相似，可誘導人類臍靜脈血管內皮細胞ASK1和p38MAPK的磷酸化以及細胞凋亡。由這些結果推測革蘭氏陽性菌細胞壁成分肽聚醣可能經由活化細胞內ASK1-p38MAPK訊息傳遁路徑，誘導凋亡蛋白Bax的表現，最終使得細胞凋亡。藉由了解肽聚醣誘導血管內皮細胞功能喪失的作用機棒，如果可以使用藥物或是其他方式阻斷細胞內ASK1-p38MAPK訊息傳遞路徑，將有助於發展臨床上治療因革蘭氏陽性菌感染所導致的血管相關疾病的有效治療策略。

關鍵字

敗血症 ； 血管滲漏症狀 ； 肽聚醣 ； 革蘭氏陽性菌

並列摘要

Peptidoglycan (PGN), a component of the outer membrane of Gram-positive bacteria has been implicated in the pathological process of sepsis. However, the molecular mechanism of PGN-induced vascular endothelium dysfunction has not been fully elucidated. Apoptosis signal regulating kinase 1 (ASK1) has been recently reported to play a crucial role in cell apoptosis under various cellular stresses. The purpose of thin study was thus to investigate whether PGN-activated ASK1 results in cell apoptosis in human umbilical vascular endothelial cells (HUVECs). PGN was shown to cause a decrease in cell viability in a concentration-dependent manner. Flow cytometric analysis demonstrated that PGN increased the percentage of apoptotic cells. PGN induced ASK1 activation was accompanied by the increased phosphorylation of p38MAPK, a major downstream signaling molecule of ASK1. In addition, PGN was shown to increase apoptotic protein, Bax, expression in HUVECs. Inhibitor of p38MAPK signaling abrogated the P/IN-increased DNA fragmentation and Bax expression, suggesting functional crosstalk. The toll-like receptor 2 (TLR2) agonist, Pam3CSK4, was also shown to induce ASK1 activation and p38MAPK phosphorylation, and subsequent cell apoptosis in HUVECs. Our data suggest that ASKI-p38MAPK cascade activation, followed by Bax expression, contributes to P/IN-induced cell apoptosis.

並列關鍵字

sepsis ； vascular leak syndromes ； peptidoglycan PGN ； ASK1 Apoptosis signal regulating kinase 1