Secció de Fisiologia, Departament de Bioquímica i Fisiologia, Universitat de Barcelona, Barcelona, Spain.
Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.
Sci Rep. 2019 Feb 14;9(1):2063. doi: 10.1038/s41598-018-38010-7.
Corpora amylacea are spherical bodies of unknown origin and function, which accumulate in the human brain during the aging process and neurodegenerative disorders. In recent work, we reported that they contain some neo-epitopes that are recognized by natural IgMs, revealing a possible link between them and the natural immune system. Here, we performed an ultrastructural study complemented with confocal microscopy in order to shed light on the formation of corpora amylacea and to precisely localize the neo-epitopes. We show that immature corpora amylacea are intracellular astrocytic structures formed by profuse cellular debris and membranous blebs entrapped in a scattered mass of randomly oriented short linear fibers. In mature corpora amylacea, the structure becomes compacted and fibrillary material constitutes the principal component. We also determined that the neo-epitopes were uniformly localized throughout the whole structure. All these observations reinforce the idea that corpora amylacea of human brain are equivalent to another type of polyglucosan bodies named PAS granules, present in mouse brain and originated from degenerative processes. All those findings support the hypothesis that corpora amylacea are involved in the entrapment of damaged materials and non-degradable products and have a role in protective or cleaning mechanisms.
脑淀粉样小体是来源和功能未知的球形结构，它们在人类大脑衰老过程和神经退行性疾病中积累。在最近的工作中，我们报告说它们包含一些被天然 IgM 识别的新表位，这表明它们与天然免疫系统之间可能存在联系。在这里，我们进行了一项超微结构研究，并结合共聚焦显微镜，以阐明脑淀粉样小体的形成，并精确定位新表位。我们表明，未成熟的脑淀粉样小体是由丰富的细胞碎片和膜泡形成的细胞内星形胶质细胞结构，这些细胞碎片和膜泡被困在分散的随机取向的短线性纤维团块中。在成熟的脑淀粉样小体中，结构变得紧凑，纤维状物质构成主要成分。我们还确定，新表位均匀地定位于整个结构中。所有这些观察结果都加强了这样一种观点，即人类大脑中的脑淀粉样小体等同于另一种多葡聚糖体，称为 PAS 颗粒，存在于老鼠大脑中，来源于退行性过程。所有这些发现都支持这样一种假设，即脑淀粉样小体参与捕获受损物质和不可降解产物，并在保护或清洁机制中发挥作用。
