von Boyen Georg B T, Steinkamp Martin, Geerling Irmlind, Reinshagen Max, Schäfer Karl H, Adler Guido, Kirsch Joachim
Department of Medicine I, Gastroenterology, University of Ulm, Ulm, Germany.
Inflamm Bowel Dis. 2006 May;12(5):346-54. doi: 10.1097/01.MIB.0000219350.72483.44.
Imbalanced apoptosis of enterocytes is likely to be 1 of the mechanisms underlying Crohn's disease (CD). Apoptosis of enterocytes is regulated by glial-derived neurotrophic factor (GDNF), which is increased in CD. The cellular source of GDNF during gut inflammation is unclear. The aim of the study was to identify the source of GDNF in CD during gut inflammation.
Glial fibrillary acidic protein (GFAP), GDNF, and smooth muscle actin (SMA) was detected in the gut from patients with CD by immunohistochemistry. Cultured enteric glia cells (EGC) were labeled with anti-GFAP, anti-GDNF, and antibodies and a Golgi marker (anti-58K antibodies) after blocking Golgi export with monensin. Cultured EGCs were treated with interleukin-1beta (IL-1beta), tumor necrosis factor-alpha, and lipopolysaccharides. Secretion of neurotrophic factors was detected by enzyme-linked immunosorbent assay.
Mucosal GFAP-positive EGCs are increased in the colon of patients with CD. This type of glia but not subepithelial myofibroblasts expresses significant amounts of GDNF. In vitro GDNF is continuously secreted from cultured EGCs. The neurotrophic factor secretion could be stimulated by IL-1beta, tumor necrosis factor-alpha, and lipopolysaccharides in a time- and dose-dependent manner. The increased GDNF secretion by EGCs sustained for>12 hours after withdrawal of the proinflammatory cytokines.
A mucosal GFAP expressing EGC population is dramatically increased in CD. This population is a major cellular source of the upregulated GDNF in the inflamed gut. Therefore, mucosal EGC may play a key role in protecting the gut epithelium and may contribute to reestablish the integrity of the injured epithelium.
肠上皮细胞凋亡失衡可能是克罗恩病（CD）的潜在发病机制之一。肠上皮细胞凋亡受胶质细胞源性神经营养因子（GDNF）调控，在CD中GDNF水平升高。肠道炎症时GDNF的细胞来源尚不清楚。本研究旨在确定肠道炎症时CD中GDNF的来源。
采用免疫组化法检测CD患者肠道中胶质纤维酸性蛋白（GFAP）、GDNF和平滑肌肌动蛋白（SMA）。用莫能菌素阻断高尔基体输出后，用抗GFAP、抗GDNF抗体和高尔基体标记物（抗58K抗体）标记培养的肠神经胶质细胞（EGC）。用白细胞介素-1β（IL-1β）、肿瘤坏死因子-α和脂多糖处理培养的EGC。采用酶联免疫吸附测定法检测神经营养因子的分泌。
CD患者结肠黏膜中GFAP阳性的EGC增多。这类神经胶质细胞而非上皮下肌成纤维细胞表达大量GDNF。体外培养的EGC持续分泌GDNF。IL-1β、肿瘤坏死因子-α和脂多糖可时间和剂量依赖性刺激神经营养因子分泌。促炎细胞因子撤除后，EGC分泌GDNF增加持续超过12小时。
CD中表达GFAP的黏膜EGC群体显著增加。该群体是炎症肠道中GDNF上调的主要细胞来源。因此，黏膜EGC可能在保护肠上皮中起关键作用，并可能有助于重建受损上皮的完整性。
