磷酸二酯酶抑制劑pentoxifylline對人類內皮細胞功能的影響

The effects of phosphodiesterase inhibitor,pentoxifylline, on human endothelial function

蔡靜瑋(Ching-Wei Tsai)

指導教授 ： 陳永銘

國立臺灣大學/醫學院/臨床醫學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03051

摘要

內皮細胞功能失調(endothelial dysfunction)和慢性腎臟病(chronic kidney
disease )之間的關係近年來備受注視。內皮細胞功能失調被認為在慢性腎臟病的產生與惡化扮演關鍵的角色，並且也可能是增加心血管疾病的風險之一。相較於健康族群，在中度及嚴重的慢性腎臟病患者，其代表內皮細胞功能失調之生物標記(biomarkers)的量是增加的。在一個根據人口作抽樣的大型研究，Hoorn研究發現內皮細胞功能失調的生物標記增加與腎功能惡化有相關性。因此，研究慢性腎臟病內皮細胞功能失調的機轉對於改善腎臟和心血管預後可能是很重要的。
磷酸二酯酶[Cyclic nucleotide phosphodiesterases (PDE)]在調控各式各樣的細胞功能上扮演重要角色。內皮細胞上有PDE2、PDE3、PDE4和PDE5的表現。PDE抑制劑能夠抑制PDE之酵素活性，因此可以防止細胞內cyclic nucleotides(cAMP及cGMP)的分解。Pentoxifylline是一種非選擇性PDE抑制劑，具有廣泛的作用，能減緩慢性腎臟病的蛋白尿，並可有效的抑制細胞增生、發炎反應及細胞外間質的囤積。先前台大腎臟科細胞研究主要集中在pentoxifylline對腎膈細胞、腎小管細胞、和纖維母細胞的作用。近年來內皮細胞的功能失調被認為在慢性腎病惡化過程扮演重要的角色，然而pentoxyfilline是否會改善內皮細胞功能失調，目前並不清楚。過去在非內皮細胞上，pentoxifylline被發現可減少多種細胞激素的表現量，另一種選擇性PDE抑制劑cilostazol則可抑制黏附分子(adhesion molecules)的表現和中性球的黏附，基於這些結果，吾人假設pentoxifylline可影響內皮細胞表現發炎細胞激素(inflammatory cytokines)和黏附分子, 進而減輕內皮細胞功能失調。
本研究以體外培養之人類臍靜脈內皮細胞(HUVEC)為模式，首先以MTT和LDH兩種方法決定pentoxifylline對HUVEC最合適的實驗濃度，其次觀察tumor necrosis factor-alpha (TNF-α)是否刺激HUVEC分泌發炎細胞激素和黏附分子(代表內皮細胞功能失調之生物標記)，最後評估pentoxifylline對這些發炎指標的調控作用。實驗結果發現pentoxifylline可有效地抑制TNF-α 所刺激的soluble ICAM-1、VCAM-1，並抑制TNF-α 所誘發的CCL2/MCP-1、CX3CL1/fractalkine mRNA。這些結果顯示pentoxifylline可能具有減輕內皮細胞發炎，緩和血管內皮功能失調的作用，顯示pentoxifylline未來有潛力作為調節內皮細胞失調或發炎的藥物，甚至用來預防與治療動脈粥樣硬化。

關鍵字

磷酸二酯酶抑制劑 ； pentoxifylline ； 內皮細胞功能失調 ； 黏附分子 ； 趨化因子

並列摘要

Endothelial dysfunction is thought to play a key role in the evolution and progression of CKD and may be one major culprit for the development of cardiovascular disease. Biomarkers of endothelial dysfunction are higher in patients with CKD and correlate inversely with glomerular filtration rate. Thus, understanding of the mechanisms responsible for endothelial dysfunction in association with CKD is important for the development of novel renoprotective therapeutic strategies.
Cyclic nucleotide phosphodiesterases (PDEs) play a critical role in regulating cellular functions through modulation of cyclic nucleotides, cAMP and cGMP. Endothelial cells are known to contain PDE2, PDE3, PDE4, and PDE5. Previously, a nonselective PDE inhibitor, pentoxifylline, has shown its anti-inflammatory, anti-proliferative, and anti-fibrotic effects in renal mesangial cells, tubular cells, and fibroblasts. Whether or not pentoxifylline can modulate endothelial dysfunction in endothelial cells has never been investigated.
In this study, the optimal working concentration of pentoxifylline on human umbilical vein endothelial cells (HUVECs) was first determined by MTT and lactate dehydrogenase assays; next, tumor necrosis factor-alpha (TNF-α)-elicited expression of adhesion molecules and inflammatory cytokines in HUVECs were measured and used as biomarkers of endothelial dysfunction. Finally, the effectiveness of pentoxifylline on biomarkers of endothelial dysfunction was investigated. Our results showed that TNF-α could induce the secretion of soluble ICAM-1 and VCAM-1, and augment the expression of CCL2/MCP-1 and CX3CL1/fractalkine mRNAs. These inflammatory biomarkers of HUVECs could be siginificantly suppressed by pentoxifylline. As such, pentoxifylline can antagonize TNF-α-induced endothelial dysfunction through inhibition of the expression of adhesion molecules and chemotactic cytokines. These results imply a potential therapeutic role of pentoxifylline in the treatment of vascular disorders characterized by endothelial dysfunction, such as atherosclerosis.

並列關鍵字

pentoxifylline ； Endothelial dysfunction ； phosphodiesterases inhibitor ； adhesion molecules ； chemokine

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