Peptidoglycan (PGN) is a cell wall component of both Gram-positive and Gram-negative bacteria. Signature fragments of PGN are proinflammatory through engagement of pattern recognition receptors (PRR) on resident tissue cells and circulating leukocytes. Despite its abundance in the gut microbiota, there is limited recognition that PGN could contribute to chronic neuroinflammation. This review highlights current insights into the roles of PGN as a determinant of brain inflammation, notably in multiple sclerosis (MS) and its experimental autoimmune encephalomyelitis (EAE) models. Recent studies demonstrate PGN in blood of healthy adult humans. PGN amplifies autoimmune pathology via activation of innate immune cells. Novel uptake routes through (altered) gut mucosa by myeloid leukocyte subsets promote PGN transport to the brain.

肽聚糖（PGN）是革兰氏阳性细菌和革兰氏阴性细菌的细胞壁成分。PGN的特征性片段通过模式识别受体（PRR）与常驻组织细胞和循环白细胞的结合而促炎。尽管其在肠道菌群中丰富，但人们对PGN可能导致慢性神经炎症的认识有限。这篇综述重点介绍了PGN作为决定大脑炎症的作用的最新见解，尤其是在多发性硬化症（MS）及其实验性自身免疫性脑脊髓炎（EAE）模型中。最近的研究表明健康成年人血液中的PGN。PGN通过激活先天免疫细胞来放大自身免疫病理。髓样白细胞亚群通过（改变的）肠粘膜的新摄取途径促进了PGN向大脑的转运。