Department of Anatomy, Inha University School of Medicine, Incheon 400-712, Korea.
Exp Neurobiol. 2013 Dec;22(4):301-7. doi: 10.5607/en.2013.22.4.301. Epub 2013 Dec 31.
High mobility group box 1 (HMGB1) is an endogenous danger signal molecule. In the postischemic brain, HMGB1 is massively released during NMDA-induced acute damage and triggers inflammatory processes. In a previous study, we demonstrated that intranasally delivered HMGB1 binding heptamer peptide (HBHP; HMSKPVQ) affords robust neuroprotective effects in the ischemic brain after middle cerebral artery occlusion (MCAO, 60 minutes). In the present study, we investigated HBHP-induced anti-inflammatory effects on microglia activation. In LPS-treated primary microglia culture, HMGB1 was rapidly released and accumulated in culture media. Furthermore, LPS-conditioned media collected from primary microglia cultures (LCM) activated naïve microglia and markedly induced NO and proinflammatory cytokines. However, the suppression of HMGB1 by siRNA-HMGB1, HMGB1 A box, or anti-HMGB1 antibody significantly attenuated LCM-induced microglial activation, suggesting that HMGB1 plays a critical role in this process. A pull-down assay using biotin-labeled HBHP showed that HBHP binds directly to HMGB1 (more specifically to HMGB1 A box) in LCM. In addition, HBHP consistently inhibited LCM-induced microglial activation and suppressed the inductions of iNOS and proinflammatory cytokines. Together these results suggest that HBHP confers anti-inflammatory effects in activated microglia cultures by forming a complex with HMGB1.
高迁移率族蛋白 B1（HMGB1）是一种内源性危险信号分子。在缺血性脑损伤中，HMGB1 在 NMDA 诱导的急性损伤期间大量释放，并触发炎症反应。在之前的研究中，我们证明了经鼻给予 HMGB1 结合七肽（HBHP；HMSKPVQ）在大脑中动脉闭塞（MCAO，60 分钟）后对缺血性脑具有强大的神经保护作用。在本研究中，我们研究了 HBHP 对小胶质细胞激活的抗炎作用。在 LPS 处理的原代小胶质细胞培养中，HMGB1 迅速释放并在培养基中积累。此外，来自原代小胶质细胞培养物的 LPS 条件培养基（LCM）激活未成熟的小胶质细胞，并显著诱导 NO 和促炎细胞因子。然而，siRNA-HMGB1、HMGB1 A 盒或抗 HMGB1 抗体抑制 HMGB1 的表达显著减弱了 LCM 诱导的小胶质细胞激活，表明 HMGB1 在该过程中起关键作用。使用生物素标记的 HBHP 进行的下拉实验表明，HBHP 直接与 LCM 中的 HMGB1（更具体地说是 HMGB1 A 盒）结合。此外，HBHP 一致抑制了 LCM 诱导的小胶质细胞激活，并抑制了诱导型一氧化氮合酶和促炎细胞因子的诱导。这些结果表明，HBHP 通过与 HMGB1 形成复合物在激活的小胶质细胞培养物中发挥抗炎作用。
