Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany.
Faculty of Chemistry, Technische Universität Dresden, Dresden, Germany.
Front Immunol. 2020 Sep 3;11:1967. doi: 10.3389/fimmu.2020.01967. eCollection 2020.
It has been previously shown that the amyloid precursor protein (APP) support the innate immune defense as an immune receptor. Amyloid β (Aβ) peptides seem to have properties of an antimicrobial peptide and can act as opsonines. In APP-deficient mouse models, a reduced secretion of cytokines has been observed. Still, it is unclear whether this can be attributed to the lack of APP or to the missing secretion of Aβ peptides. We inhibited the secretion of Aβ peptides in primary human monocyte derived macrophages with the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine-t-butyl-ester (DAPT) or the β-secretase inhibitor GL-189. Alternatively, we knocked down APP by transfection with siRNA. We measured tumor necrosis factor α (TNFα), interleukin 6 (IL-6) and interleukin (IL-10) by enzyme linked immunosorbent assay (ELISA) and evaluated the phagocytotic activity by flow cytometry. We observed reduced concentrations of TNFα and IL-6 in the media of APP macrophages and after inhibition of the β-, or γ-secretase, especially after additional immunological activation with lipopolysaccharide (LPS). Secretion of IL-10 was increased after pharmacological inhibition of APP processing when the macrophages were not immunologically activated but was decreased during LPS-induced inflammation in APP macrophages. No changes of the phagocytotic activity were observed. We conclude that macrophage APP and Aβ peptides support the initiation of an immune response and are involved in the regulation of TNFα, IL-6, and IL-10 secretion by human monocyte-derived macrophages.
先前已经表明，淀粉样前体蛋白（APP）作为免疫受体支持先天免疫防御。淀粉样 β（Aβ）肽似乎具有抗菌肽的特性，并可以作为调理素。在 APP 缺陷型小鼠模型中，观察到细胞因子的分泌减少。然而，尚不清楚这是由于缺乏 APP 还是由于 Aβ肽的缺失分泌所致。我们使用 γ-分泌酶抑制剂 N-[N-(3,5-二氟苯乙酰基)-L-丙氨酰]-S-苯甘氨酸叔丁酯（DAPT）或β-分泌酶抑制剂 GL-189 抑制原代人单核细胞衍生的巨噬细胞中 Aβ肽的分泌。或者，我们通过转染 siRNA 敲低 APP。我们通过酶联免疫吸附测定（ELISA）测量肿瘤坏死因子 α（TNFα）、白细胞介素 6（IL-6）和白细胞介素 10（IL-10），并通过流式细胞术评估吞噬活性。我们观察到 APP 巨噬细胞和抑制β-或 γ-分泌酶后培养基中 TNFα 和 IL-6 的浓度降低，特别是在用脂多糖（LPS）进行额外的免疫激活后。在用药物抑制 APP 处理时，当巨噬细胞未被免疫激活时，IL-10 的分泌增加，但在 LPS 诱导的 APP 巨噬细胞炎症中减少。吞噬活性没有变化。我们得出结论，巨噬细胞 APP 和 Aβ 肽支持免疫反应的启动，并参与人单核细胞衍生的巨噬细胞中 TNFα、IL-6 和 IL-10 分泌的调节。
