- 學位論文
探討天然物LHZ-7在活化的膠質細胞中抗發炎之作用機轉
Investigate the Anti-inflammatory Mechanisms of the Natural Compound LHZ-7 in Activated BV2 Microglial Cells
摘要
在神經發炎性疾病或神經退化性疾病中，都和發炎反應與氧化壓力有著密切的關係，而其中神經膠細胞的過度活化在疾病發展中扮演重要的角色。過度活化的神經膠細胞所分泌的各種前發炎細胞激素(例如一氧化氮) 會導致神經細胞的死亡，因此藉由抑制神經膠細胞的過度活化所產生的一氧化氮可達到減緩神經性疾病的發展。 本篇研究顯示，在小膠質細胞中，Nectria balsamea真菌萃取出的天然物LHZ-7可依濃度效應抑制脂多醣 (LPS) 所引發的發炎介質一氧化氮合成酶 (iNOS) 和一氧化氮的表現。此外，LHZ-7 對於小膠質細胞並沒有明顯細胞毒性。LPS刺激下訊息傳遞結果顯示LHZ-7會抑制inhibitor-?羠-?? (I?羠-??) 的降解，但對於AKT 和MAPK 路徑 (如 ERK，JNK，p38) 並沒有影響。有趣的是我們發現，單獨給予LHZ-7 即會促進小膠質細胞heme oxygenase-1 (HO-1) 大量表現。進一步研究指出，ERK抑制劑、Nrf2 siRNA 以及抗氧化劑NAC 可以阻斷LHZ-7所誘導的HO-1表現。此外，前處理HO-1活性抑制劑SnPP可反轉LPS刺激下，LHZ-7抑制小膠質細胞釋放一氧化氮的效果。綜合以上結果，我們認為LHZ-7可能是透過誘導HO-1表現並且抑制NFκB的活化而降低LPS所引發的一氧化氮生成。
並列摘要
Oxidative stress and inflammation have been implicated in many neuro-inflammatory and neuro-degenerative diseases. The glial activation plays an important role in the progression of these diseases. Over-activated glial cells can secrete various proinflammatory mediators, such as Nitric oxide (NO) and Interleukin-1 (IL-1???w, which may contribute to neuron death. Inhibition of glial activation may alleviate neurodegeneration under these conditions. In this study, we found that the natural compound LHZ-7 (1–20 ?嵱), ioslated from Nectria balsamea, significantly inhibited LPS-induced iNOS expression and NO production in LPS-activated BV2 cells. In addition, cell viability was slightly affected by LHZ-7. In signaling pathways, LHZ-7 decreased the degradation of inhibitor-?羠-?? (I?羠??) but had no effects on the activation of AKT and MAPK (such as ERK, JNK, p38) in LPS-activated BV2 cells. Notably, we found that LHZ-7 alone strongly up-regulated the expression of heme oxygenase-1 (HO-1) in BV2 cells. ERK inhibitor (PD98059), knockdown of Nrf2, or antioxidant (NAC) could block the LHZ-7-induced HO-1 expression. Furthermore, blocking HO-1 activity by treatment of SnPP abrogated the inhibitory effect of LHZ-7 on the NO production in LPS-activated BV2 cells. Taken together, LHZ-7 up-regulated the expression of HO-1 protein and inhibited the LPS-induced NO production through NF?羠 inhibition.