Department of Clinical Chemistry, VU University Medical Center Amsterdam, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
Glia. 2010 Aug;58(10):1235-46. doi: 10.1002/glia.21004.
Intracerebral accumulation of amyloid-beta (A beta) leading to A beta plaque formation, is the main hallmark of Alzheimer's disease and might be caused by defective A beta-clearance. We previously found primary human astrocytes and microglia able to bind and ingest A beta 1-42 in vitro, which appeared to be limited by A beta 1-42 fibril formation. We now confirm that astrocytic A beta-uptake depends on size and/or composition of A beta-aggregates as astrocytes preferably take up oligomeric A beta over fibrillar A beta. Upon exposure to either fluorescence-labelled A beta 1-42 oligomers (A beta(oligo)) or fibrils (A beta(fib)), a larger (3.7 times more) proportion of astrocytes ingested oligomers compared to fibrils, as determined by flow cytometry. A beta-internalization was verified using confocal microscopy and live-cell imaging. Neither uptake of A beta(oligo) nor A beta(fib), triggered proinflammatory activation of the astrocytes, as judged by quantification of interleukin-6 and monocyte-chemoattractant protein-1 release. Amyloid-associated proteins, including alpha1-antichymotrypsin (ACT), serum amyloid P component (SAP), C1q and apolipoproteins E (ApoE) and J (ApoJ) were earlier found to influence A beta-aggregation. Here, astrocytic uptake of A beta(fib) increased when added to the cells in combination with SAP and C1q (SAP/C1q), but was unchanged in the presence of ApoE, ApoJ and ACT. Interestingly, ApoJ and ApoE dramatically reduced the number of A beta(oligo)-positive astrocytes, whereas SAP/C1q slightly reduced A beta(oligo) uptake. Thus, amyloid-associated proteins, especially ApoJ and ApoE, can alter A beta-uptake in vitro and hence may influence A beta clearance and plaque formation in vivo.
脑内淀粉样蛋白-β（Aβ）的积累导致 Aβ斑块的形成，是阿尔茨海默病的主要标志，可能是由于 Aβ清除缺陷引起的。我们之前发现原代人星形胶质细胞和小胶质细胞能够在体外结合和摄取 Aβ1-42，这似乎受到 Aβ1-42 纤维形成的限制。我们现在证实星形胶质细胞摄取 Aβ依赖于 Aβ聚集物的大小和/或组成，因为星形胶质细胞更倾向于摄取寡聚体 Aβ而不是纤维状 Aβ。在用荧光标记的 Aβ1-42 寡聚体（Aβ（oligo））或纤维（Aβ（fib））暴露后，通过流式细胞术测定，摄取寡聚体的星形胶质细胞比例（比纤维高 3.7 倍）更大。使用共聚焦显微镜和活细胞成像验证了 Aβ内化。无论是摄取 Aβ（oligo）还是 Aβ（fib），都没有触发星形胶质细胞的促炎激活，这可以通过白细胞介素-6 和单核细胞趋化蛋白-1 释放的定量来判断。淀粉样相关蛋白，包括α1-抗胰凝乳蛋白酶（ACT）、血清淀粉样蛋白 P 成分（SAP）、C1q 和载脂蛋白 E（ApoE）和 J（ApoJ），先前被发现会影响 Aβ聚集。在这里，当与 SAP 和 C1q（SAP/C1q）一起添加到细胞中时，星形胶质细胞摄取 Aβ（fib）增加，但在存在 ApoE、ApoJ 和 ACT 时没有变化。有趣的是，ApoJ 和 ApoE 显著减少了 Aβ（oligo）阳性星形胶质细胞的数量，而 SAP/C1q 则略微减少了 Aβ（oligo）的摄取。因此，淀粉样相关蛋白，特别是 ApoJ 和 ApoE，可以改变体外的 Aβ摄取，从而可能影响体内的 Aβ清除和斑块形成。
