Savidge Tor C, Newman Paul, Pothoulakis Charalabos, Ruhl Anne, Neunlist Michel, Bourreille Arnaud, Hurst Roger, Sofroniew Michael V
Division of Gastroenterology, The University of Texas Medical Branch, Galveston, Texas, USA.
Gastroenterology. 2007 Apr;132(4):1344-58. doi: 10.1053/j.gastro.2007.01.051. Epub 2007 Feb 1.
BACKGROUND & AIMS: Barrier functions across epithelia and endothelia are essential for homeostatic tissue regulation. Astroglia interact with cerebral endothelia to maintain the blood-brain barrier. Whether similar interactions between astrocyte-like enteric glia and epithelia regulate intestinal barrier function is not known.
Fluorescent permeability markers were used to measure intestinal barrier function in vivo after conditional ablation of enteric glia in transgenic mice. Enteric glial cell regulation of epithelial barrier integrity then was modeled in vitro using coculture. Glial-derived barrier-inducing factors were characterized using size-exclusion chromatography and mass spectrometry. Epithelial barrier integrity was assessed by transepithelial resistance readings and by quantitative measurement of tight-junction-associated protein expression by quantitative polymerase chain reaction and Western blot.
We show that ablation of enteric glial cells in transgenic mice causes intestinal mucosal barrier dysfunction, resulting in inflammation. Glial-derived s-nitrosoglutathione (GSNO) was identified as a potent inducer of mucosal barrier function in vitro and in vivo and of attenuated tissue inflammation after ablation of enteric glia in transgenic mice. GSNO regulation of mucosal barrier function was associated directly with an increased expression of perijunctional F-actin and tight-junction-associated proteins zonula occludens-1 and occludin. GSNO also significantly restored mucosal barrier function in colonic biopsy specimens from patients with Crohn's disease, a well-described inflammatory permeability disorder associated with enteric glial-cell disruption.
Enteric glia therefore share the ability of astrocytes to regulate tight-junction integrity, and cellular interactions comparable with those maintaining blood-brain barrier function also regulate epithelial permeability at mucosal surfaces.
上皮细胞和内皮细胞的屏障功能对于组织稳态调节至关重要。星形胶质细胞与脑内皮细胞相互作用以维持血脑屏障。目前尚不清楚类似的星形胶质细胞样肠神经胶质细胞与上皮细胞之间的相互作用是否调节肠道屏障功能。
在转基因小鼠中对肠神经胶质细胞进行条件性消融后，使用荧光通透性标记物在体内测量肠道屏障功能。然后通过共培养在体外模拟肠神经胶质细胞对上皮屏障完整性的调节。使用尺寸排阻色谱法和质谱法对神经胶质细胞衍生的屏障诱导因子进行表征。通过跨上皮电阻读数以及通过定量聚合酶链反应和蛋白质印迹法对紧密连接相关蛋白表达进行定量测量来评估上皮屏障完整性。
我们发现，转基因小鼠中肠神经胶质细胞的消融会导致肠黏膜屏障功能障碍，进而引发炎症。神经胶质细胞衍生的S-亚硝基谷胱甘肽（GSNO）被鉴定为体外和体内黏膜屏障功能的有效诱导剂，并且在转基因小鼠中肠神经胶质细胞消融后可减轻组织炎症。GSNO对黏膜屏障功能的调节直接与连接周围F-肌动蛋白以及紧密连接相关蛋白闭合蛋白-1和闭合蛋白的表达增加有关。GSNO还显著恢复了克罗恩病患者结肠活检标本中的黏膜屏障功能，克罗恩病是一种与肠神经胶质细胞破坏相关的、已被充分描述的炎症性通透性障碍。
因此，肠神经胶质细胞具有与星形胶质细胞相同的调节紧密连接完整性的能力，并且与维持血脑屏障功能类似的细胞间相互作用也调节黏膜表面的上皮通透性。
