PrP^(106-126)及Aβ_(1-42)同步诱导BV-2小胶质细胞趋化及增殖活性的研究

PrP^(106-126) and Aβ_(1-42) Peptides Induce Simultaneously BV-2 Microglia Chemotaxis and Proliferation

通过检测传染性海绵状脑病(TSEs)及阿尔茨海默病(AD)的PrP和Aβ毒性蛋白同步诱导小胶质细胞趋化与增殖活性,旨在初步揭示TSEs及AD的致病机制及重新评估TSEs危害公共卫生安全的风险。以PrP106-126和Aβ1-42为研究对象,以BV-2小胶质细胞为实验细胞,构建25~100μmol·L-1的PrP106-126和2.5~10μmol·L-1的Aβ1-42以及两者不同浓度比例混合物侵染BV-2细胞的实验模型,比较多肽及其混合物诱导BV-2的趋化指数(CI)、增殖指数(PI)以及MCP-1、TGF-β1的表达水平,同步进行上述参数的相关性分析。结果表明:与PBS组及蛋白对照组相比,25~100μmol·L-1的PrP106–126及2.5~10μmol·L-1 Aβ1-42均上调BV-2的CI、PI及表达MCP-1、TGF-β1水平(P<0.05);两种多肽不同浓度混合物同步诱导BV-2的CI、PI值及MCP-1、TGF-β1表达水平均大于单一蛋白分别诱导相同参数值,但却小于两种蛋白分别诱导相同参数值之和;两者诱导BV-2CI、PI及MCP-1表达水平均呈现多肽低浓度依赖性及处理时间依赖性,但当多肽达到高浓度或长诱导时间(PrP106-126>50μmol·L-1;Aβ1-42>5μmol·L-1;诱导时间>12h)时,这3种参数都进入平台期,但BV-2表达TGF-β1水平持续上升;PrP106-126及Aβ1-42对BV-2RCI与MCP-1水平呈正相关。结果提示,两种多肽均能上调BV-2的CI、PI及表达MCP-1、TGF-β1水平,并引起这些参数有规律的变化,两者在蛋白水平同步诱导BV-2上述参数有明显的拮抗作用。

Transmissible spongiform encephalopathies(TSEs)and Alzheimer's disease(AD)belong to a growing family of neurodegenerative disorders that is characterized by the generation of toxic protein aggregates in affected brains(PrPSc and Aβin TSEs and AD,respectively).At present,clinical and experimental evidence indicates the coexistence of PrP and Aβamyloid deposits in affected brain tissues.Based on these pathological and mechanistic similarities,relationship between TSEs and AD should be further investigated.In this study,we examined the activation of BV-2microglial chemotaxis and proliferation as well as BV-2cell secretion of MCP-1and TGF-β1after treatment with aggregated forms of PrP106-126 and Aβ1-42(separately and together)in vitro in an attempt to understand how protein aggregates can modulate microglial processes in TSEs and AD.We treated BV-2microglia with PrP106-126 or Aβ1-42 peptides individually at thee different con-centrations(25-100μmol·L-1 PrP106-126 and 2.5-10μmol·L-1 Aβ1-42)or with a mixture of PrP106-126 and Aβ1-42 peptides at specified concentrations for 6-24 h.BV-2microglia chemotaxis,proliferation,and MCP-1and TGF-β1secretion were measured and compared between treatments.The results demonstrate that PrP106-126 and Aβ1-42 peptides induce increases in all four parameters from 6-12 h.However,the measured indices plateaued beyond 12 hin BV-2cells treated >50μmol·L-1 PrP106-126 or>5μmol·L-1 Aβ1-42,with the exception of TGF-β1secretion,which continued to increase gradually.Overall,the results of this study indicated that PrP106-126 and Aβ1-42 peptides induce increases in all four parameters from 6-12 hand these two peptides have obviously antagonistic effects in inducing microglial chemotaxis and proliferation simultaneously at the protein level.