The blood–brain barrier (BBB) is a vital interface that supports normal brain functions. Endothelial cells (ECs) are the main component of the BBB and are highly specialized to govern the transfer of substances into brain. The EC lumen is enmeshed with an extracellular matrix (ECM), known as the endothelial glycocalyx layer (EGL). The lumen-facing EGL is primarily comprised of proteoglycans (PGs) and glycosaminoglycans (GAGs), which function as the first line of defense for blood-to-brain transfer of substances. Circulating factors must first penetrate the EGL before interacting with the EC. The abundance and composition of the PG and GAGs can dictate EGL function, and determine which circulating substances communicate with the ECs. The EGL can interact with circulating factors through physio-chemical interactions with the EC. Some disease states reveal a “thinning” of the EGL that may increase EC interactions with components of the systemic circulation and alter BBB function. EGL changes may also contribute to the cognitive complications of systemic diseases, such as sepsis and diabetes. For decades, researchers have measured how genetic and environmental factors influence the peripheral EGL constituents; however, much less is known about the neurovascular EGL. In this mini-review, we introduce components of the EGL and innovative ways to measure their abundance and composition that may contribute to BBB dysfunction.

血脑屏障 (BBB) 是支持正常大脑功能的重要界面。内皮细胞 (ECs) 是 BBB 的主要成分，高度专业化以控制物质向大脑的转移。EC 腔与细胞外基质 (ECM) 交织在一起，称为内皮糖萼层 (EGL)。面向管腔的 EGL 主要由蛋白聚糖 (PG) 和糖胺聚糖 (GAG) 组成，它们是物质从血液到大脑转移的第一道防线。在与 EC 相互作用之前，循环因子必须首先穿透 EGL。PG 和 GAG 的丰度和组成可以决定 EGL 功能，并确定哪些循环物质与 EC 通信。EGL 可以通过与 EC 的物理化学相互作用与循环因子相互作用。一些疾病状态揭示了 EGL 的“变薄”，这可能会增加 EC 与体循环成分的相互作用并改变 BBB 功能。EGL 变化也可能导致全身性疾病的认知并发症，例如败血症和糖尿病。几十年来，研究人员一直在测量遗传和环境因素如何影响周围的 EGL 成分；然而，人们对神经血管 EGL 知之甚少。在这篇迷你评论中，我们介绍了 EGL 的组成部分和创新方法来测量可能导致 BBB 功能障碍的丰度和组成。几十年来，研究人员一直在测量遗传和环境因素如何影响周围的 EGL 成分；然而，人们对神经血管 EGL 知之甚少。在这篇迷你评论中，我们介绍了 EGL 的组成部分和创新方法来测量可能导致 BBB 功能障碍的丰度和组成。几十年来，研究人员一直在测量遗传和环境因素如何影响周围的 EGL 成分；然而，人们对神经血管 EGL 知之甚少。在这篇迷你评论中，我们介绍了 EGL 的组成部分和创新方法来测量可能导致 BBB 功能障碍的丰度和组成。