Polymeric sialic acid (polysialic acid, polySia) is a remarkable posttranslational modification of only few select proteins. The major, and most prominent polySia protein carrier is the neural cell adhesion molecule NCAM. Here, the key functions of polySia are to regulate interactions of NCAM and to balance cellular interactions in brain development and plasticity. During recent years, however, increasing evidence points towards a role of polySia in the modulation of immune responses. These immunomodulatory functions can be mediated by polySia on proteins other than NCAM, presented either on the cell surface or released into the extracellular space. This perspective review summarizes our current knowledge and addresses major open questions on polySia and polySia receptors in modulating innate immune responses in the brain.

聚合唾液酸 (polysialic acid, polySia) 是仅对少数选定蛋白质进行的显着翻译后修饰。主要且最突出的 polySia 蛋白载体是神经细胞粘附分子 NCAM。在这里，polySia 的关键功能是调节 NCAM 的相互作用并平衡大脑发育和可塑性中的细胞相互作用。然而，近年来，越来越多的证据表明 polySia 在调节免疫反应中的作用。这些免疫调节功能可以由 polySia 介导 NCAM 以外的蛋白质，呈现在细胞表面或释放到细胞外空间。这篇观点综述总结了我们目前的知识，并解决了关于 polySia 和 polySia 受体在调节大脑先天免疫反应方面的主要开放性问题。