Esen Nilufer, Kielian Tammy
Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, 4301 W. Markham St., Slot 846, Little Rock, AR 72205, USA.
J Neuroimmunol. 2005 Dec 30;170(1-2):93-104. doi: 10.1016/j.jneuroim.2005.09.003. Epub 2005 Oct 17.
Recognition of Staphylococcus aureus and its cell-wall component peptidoglycan (PGN) by microglia is mediated, in part, by Toll-like receptor 2 (TLR2). However, the pattern recognition receptor (PRR) CD14 can also bind PGN and enhance TLR2-mediated signaling in macrophages, suggesting a similar phenomenon might occur in microglia. To assess the functional significance of CD14 on microglial activation, we evaluated the responses of primary microglia isolated from CD14 knockout (KO) and wild type (WT) mice. PGN-dependent microglial activation was partially CD14-dependent as demonstrated by the attenuated expression of TNF-alpha, macrophage inflammatory protein-2 (MIP-2/CXCL2), and the soluble PRR pentraxin-3 in CD14 KO microglia compared to WT cells. In contrast, microglial responses to intact S. aureus occurred primarily via a CD14-independent manner. Collectively, these findings reveal the complex nature of gram-positive bacterial recognition by microglia, which occurs, in part, via CD14.
小胶质细胞对金黄色葡萄球菌及其细胞壁成分肽聚糖（PGN）的识别部分是由Toll样受体2（TLR2）介导的。然而，模式识别受体（PRR）CD14也可以结合PGN并增强巨噬细胞中TLR2介导的信号传导，这表明小胶质细胞中可能发生类似现象。为了评估CD14对小胶质细胞激活的功能意义，我们评估了从CD14基因敲除（KO）和野生型（WT）小鼠分离的原代小胶质细胞的反应。与野生型细胞相比，CD14基因敲除小胶质细胞中TNF-α、巨噬细胞炎性蛋白-2（MIP-2/CXCL2）和可溶性PRR五聚素-3的表达减弱，这表明PGN依赖性小胶质细胞激活部分依赖于CD14。相比之下，小胶质细胞对完整金黄色葡萄球菌的反应主要通过不依赖CD14的方式发生。总的来说，这些发现揭示了小胶质细胞对革兰氏阳性菌识别的复杂性质，其中部分是通过CD14发生的。
