Cu(II) Attenuates Oligomeric and Fibrillar Aβ-Induced Activation of BV-2 Microglia Cells

Aβ is one of the main components of senile plaques, a pathological hallmark of Alzheimer's disease. Activated microglia represents a major source of inflammatory factors in Alzheimer's disease and a possible source of cytotoxic factors. Aβ has been shown to activate microglia and stimulate to produce inflammatory factors. Mounting evidence has shown that Cu(II) can modulate the physiochemical properties of Aβ. This article is aim to evaluate the effect of Cu(II) on the oligomeric and fibrillar Aβ in microglia activation. Oligomeric and fibrilliar Aβ were prepared by incubate at 4 °C for 24h and at 37 °C for 7days, respectively. Aβ assemblies were extensively characterized by CD, TH-T fluorescence and sedimentation assay. For the Aβ-Cu(II) complex preparation, the above oligomeric and fibrillar Aβ were incubated with Cu(II) for 1h to form the Aβ-Cu(II) complexes, respectively. The immortalized murine BV-2 cells were grown and maintained in Dulbecco's Modified Eagles Medium (DMEM) (supplemented with 10% fetal bovine serum and 100 mg/mL streptomycin and 10 U/mL penicillin) at 37 °C in a humidified incubator with 5% CO2. 1μM concentration of oligomeric or fillbrillar Aβ was chosen. LPS was chosen as positive control and PBS as Vehicle control. Cell viability was quantitively determined using the MTT assay.After BV-2 cells co-incubated with different forms of Aβ or their Aβ-Cu(II) complexes for 24 h, real-time PCR detected TNFα and iNOS mRNA expression levels of BV-2 cells. The production of nitric oxide (NO) was quantified by measuring the released NO metabolites(nitrate and nitrite) with Griess reagent. Cu(II) has an important effect on the oligomeric and filbrillar Aβ secondary structure and aggregation, and will disrupts β-sheet structure and converts β aggregates into non-β aggregates. Both oligomeric and filbrillar Aβ can induce microglial activation, however the cellular signal ways are different due to the TNFα and iNOS mRNA expression levels, and NO metabolites activity are different when the BV2 cells were co-incubated with oligomeric and filbrillar Aβ40, respectively.Aβ-Cu(II) complexs play less roles on the activation of microglial than both oligomeric and fibrillar Aβ. These results indicated that oligomeric and fibrillar Aβ induce differentially activation of BV-2 cells and which were dramatically attenuated by Cu(II).