Pomalidomide減緩在缺血性腦部損傷所產生的發炎反應、氧化壓力及凋亡作用

中風是世界上造成死亡及嚴重殘疾的主要原因之一。在腦部遭受缺血性中風之後，發炎反應對於永久性的神經損傷扮演著一個極度重要的角色。有許多證據指出活性氧 (ROS)參與了中風後的發炎反應。在缺血性中風的初期反應中，活性氧的生成是藉由一些發炎反應及相關的酵素經過被活化後而產生，接著會抑制粒線體的活性，導致更嚴重的組織傷害。Pomalidomide (POM)不僅是一種免疫調節劑也是一種具有抗發炎作用的藥物，但它從未被應用在對於缺血性中風的治療研究。我們利用大鼠的皮質神經初代細胞培養模型，以過氧化氫作為活性氧傷害的來源，藉此實驗我們證明了POM 是具有神經保護的作用，它是經由活化nuclear factor erythroid derived 2 (Nrf2) /superoxide dismutase 2 (SOD2) /catalase 的訊息途徑達到抵抗氧化壓力及減少細胞的死亡的效果。此外，POM 同時也抑制了nuclear factor kappa-light-chain-enhancer (NF-κB)的活化以及緩解了皮質神經細胞經由BCL2 Associated X (BAX)、Cytochrome c (Cyt c)及Poly (ADP-ribose) polymerase (PARP)所調控的細胞凋亡。進一步為了瞭解POM 在動物體內的神經保護作用，我們則使用暫時性大鼠中腦動脈閉塞(MCAo)作為缺血性中風的動物實驗模型，爾後給予POM 治療。結果顯示在經由給予POM 治療後，進行中腦動脈閉塞的大鼠之大腦梗塞區域有明顯的縮小且改善了運動行為的表現。先前細胞研究證明了POM 可減輕氧化壓力及發炎前驅細胞激素的表現，接著我們則使用了POM 治療，作為長期過量表現TNF-a表現活性蛋白?SP?-C 啟動子(SP-C/TNF-a小鼠))評估POM 是可以經由系統性給藥來降低整體的TNF-a表現。在血清的分析中，POM 可有效降低TNF-a表現。在小鼠的藥物動力學實驗中，則測量了腦中POM 表現以評估其是否為全身性藥物。而POM 在腦/血漿中的濃度表現比值為 0.71。因此，我們證實了POM 對於過氧化氫產生的損傷所提供的保護作用是藉由它本身的抗氧化及抗發炎作用。因此，POM 對於缺血性腦部損傷及相關的疾病是一個極具潛力及具有評估意義的治療藥物。

關鍵字

超氧化物歧化酶氧化壓力； pomalidomide ；沙利度胺；大鼠中腦動脈閉塞；神經保護；活性氧；缺血性中風；腫瘤壞死因子-a

並列摘要

Stroke is a major leading cause of death and severe disability worldwide. After cerebral ischemia, inflammation plays a central role in the development of permanent neurological damage. Reactive oxygen species (ROS) are involved in the mechanism of post-ischemic inflammation. The activation of several inflammatory enzymes produces ROS, which subsequently suppress mitochondrial activity, leading to further tissue damage. Pomalidomide (POM) is an immunomodulatory and anti-inflammatory agent that has not been thoroughly investigated in ischemic stroke. Using H2O2-insulted rat primary cortical neuronal cultures, we demonstrated that POM displayed neuroprotective effects against oxidative stress and cell death via the nuclear factor erythroid derived 2 (Nrf2) /superoxide dismutase 2 (SOD2) /catalase. POM also suppressed the nuclear factor kappa-light-chain-enhancer (NF-κB) activation and significantly mitigated cortical neuronal apoptosis by regulating BCL2 Associated X (BAX), Cytochrome c (Cyt c), and Poly (ADP-ribose) polymerase (PARP). To evaluate the neuroprotective effects of POM in vivo, rats were subjected to transient middle cerebral artery occlusion (MCAo) for 60 min, and subsequently treated with POM. The results indicated significant attenuation of the cerebral infarct in treated MCAo rats and improved motor activity. Prior cellular studies demonstrate that POM can mitigate oxidative stress and lower levels of pro-inflammatory cytokines; we then used POM to investigate the inflammatory effect in transgenic mice, which chronically over-expressed TNF-a (surfactant protein (SP)-C promoter (SP-C/TNF-a mice)), to assess whether systemically administered drug could lower systemic TNF-a level. POM significantly lowered serum levels of TNF-a. Pharmacokinetic studies were then undertaken in mice to evaluate brain POM levels following systemic drug administration. POM possessed a brain/plasma concentration ratio of 0.71. We demonstrated that POM exerted neuroprotective effects via its antioxidative and IX anti-inflammatory effects against H2O2-induced injury. Thus, POM may be a potential therapeutic agent against ischemic brain damage and related diseases, and warrant further evaluation.

並列關鍵字

superoxide dismutase 2 ； oxidative stress ； pomalidomide ； thalidomide ； middlecerebral artery occlusion ； neuroprotection ； reactive oxygen species ； ischemia ； TNF-a