| Abstract: | 核轉錄因子-kappa B（nuclear factor-kappa B, NF-κB）藉由多重的檢查及平衡做緊密的調節 以避免持續活化造成宿主的傷害。NF-κB活化及調節基因的表現是藉由轉錄後修飾做調節，例 如細胞受刺激時磷酸化（phosphorylation）、泛素（ubiquitin）的降解及調節、乙醯化（acetylation） 和甲基化（methylation）能改變 NF-κB的活化及作用。泛素-蛋白酶體系統（ubiquitin-proteasome system）存在於所有真核細胞中，具有選擇性降解細胞內不需要的或受損的蛋白質之功能。核 轉錄因子的抑制蛋白（inhibitor of nuclear factor κBα, IκBα）是蛋白酶重要的受質，IκBα是 NF-κB 的抑制劑，會與 NF-κB結合，避免 NF-κB轉至細胞核內促使目標基因表現，蛋白酶體降解 IκB 是 NF-κB活化的必要步驟。P65/RelA 是 NF-κB異源二聚體的次單位，能藉由乙醯化的 lysine 殘基激發或減少 NF-κB的訊息傳導，lysine310 的乙醯化是活化 NF-κB轉錄的關鍵，而 sirtuin1 則可將此去乙醯化。過氧化酶體增殖劑活化受體（peroxisome proliferators-activated receptors， PPARs）是核受體（nuclear receptor）家族成員，亦是轉錄因子之一，PPARγ扮演抗發炎因子主 要藉由干擾發炎反應的轉錄途徑，例如調節 NF-κB的訊息傳導，因此，瞭解 NF-κB的調節機轉 可以找出預防及治療發炎的策略。本研究利用廣東住血線蟲誘發腦膜炎或腦膜腦炎當做動物試 驗模型，探討蛋白酶體、去乙醯化酶-1（sirtuin1）及 PPARγ是否與 NF-κB的訊息傳導及促發炎 基因的調節有關係。第一年我們擬將廣東住血線蟲感染鼷鼠以 sirtuin1 促進劑白黎蘆醇 （resveratrol）處理，檢測去乙醯化酶-1在廣東住血線蟲感染過程的變化，進而分析細胞激素 （cytokines; IL-1β、IL-5、TNF-α）、趨化因子（chemokines; CCL-11）、粘附因子（adhesion molecules; ICAM-1）的變化，探討去乙醯化和 NF-κB活化對腦膜炎或腦膜腦炎的影響。第二年我們擬將廣 東住血線蟲感染鼷鼠分別以 PPARγ促進劑及拮抗劑處理，分析促發炎酵素（proinflammatory enzymes）誘導型一氧化氮合成酶（inducible nitric oxide synthase, iNOS）、環氧化酶-2 （cyclooxygenase-2, COX-2）及基質金屬蛋白酶-9（matrix metalloproteinase-9, MMP-9）的變化， 探討 PPARγ與腦膜炎或腦膜腦炎的關係。第三年擬以廣東住血線蟲感染蛋白酶體基因 knockout 鼷鼠，以血-腦屏障（blood-brain barrier, BBB）相關的結構蛋白閉合蛋白（occludin）、纖維連結 蛋白（fibronectin）及 S100B當做 BBB損傷的指標，探討蛋白酶體與腦膜炎或腦膜腦炎的關係。 本研究的目標是探討廣東住血線蟲感染鼷鼠時調節 NF-κB活化及作用的機轉，進而找出治療廣 東住血線蟲誘發嗜伊紅性腦膜炎或腦膜腦炎之新策略，由此模式提供臨床上治療此症之參考。
Nuclear factor kappa beta (NF-κB) is tightly regulated by multiple checks and balances in order to prevent persistent NF-κB activation that could have deleterious effects on the host. Activation of NF-κB-regulated gene expression is modulated by post-transcriptional modifications, such as phosphorylation, degradative and regulatory ubiquitination, acetylation and methylation, which can be altered upon stimulation. The ubiquitin-proteasome system is the main selective intracellular degradation pathway of unneeded or damaged protein in all eukaryotic cells. Inhibitor of nuclear factor κBα (IκBα) is important proteasome substrate. It is an inhibitor of NF-κB that binds to the nuclear localization domain of transcription factor, preventing it from translocating to the nucleus and promoting target gene expression of NF-κB. Proteasomal degradation of IκBα is required for NF-κB activation. Of particular interest is the acetylation of p65/RelA, a subunit of the heterodimeric NF-κB protein, which can either potentiate or diminish NF-κB signaling depending on the particular acetylated lysine residue. Acetylation of lysine 310 is critical for full activation of NF-κB transcription potential, which can be deacetylated by sirtuin1. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors of the nuclear hormone receptor superfamily. PPARγ act as anti-inflammatory agents by interfering with the transcriptional pathways involved in inflammatory responses, such as the modulation of NF-κB signaling. Therefore, discovery of NF-κB regulation has become a target for the prevention and treatment of inflammation. In this study, we used Angiostrongylus cantonensis induced-meningitis or meningoencephalitis as a model to investigate whether proteasome, sirtuin1 and PPARγ play important roles in the regulation of NF-κB signaling and proinflammatory gene expression. The first year will use sirtuin1 agnoist resveratrol to detect the changes of sirtuin1 during A. cantonensis infection. Further, to examine the changes of cytokines (IL-1β、IL-5、TNF-α), chemokines (CCL-11) and adhesion molecules (ICAM-1) after resveratrol treatment in A. cantonensis-infected mice. We will investigate the association of deacetylation and NF-κB activation in eosinophilic meningitis or meningoencephalitis. The second year will examine the changes of proinflammatory enzymes inducible nitric oxide synthase (iNOS)、cyclooxygenase-2 (COX-2)、matrix metalloproteinase-9 (MMP-9) when mice treated with PPARγ agonist and antagnoist. The third year will use proteasome gene knockout mice to examine the changes of occludin, fibronectin and S100B in the BBB dysfunction during A. cantonensis infection. Further, we will explore the role of proteasome in A. cantonensis-induced eosinophilic meningitis or meningoencephalitis. The present study is to investigate the mechanisms of NF-κB regulation during A. cantonensis infection, further, provide the clinical evaluation on the therapy strategy of A. cantonensis-induced eosinophilic meningitis or meningoencephalitis. |
