经口给予内毒素对无菌大鼠结肠黏蛋白的影响。

Effects of perorally applied endotoxin on colonic mucins of germfree rats.

作者信息

Enss M L, Müller H, Schmidt-Wittig U, Kownatzki R, Coenen M, Hedrich H J

机构信息

Dept. for Laboratory Animal Science and Animal Facility, Medical School Hanover, Germany.

出版信息

Scand J Gastroenterol. 1996 Sep;31(9):868-74. doi: 10.3109/00365529609051994.

DOI:10.3109/00365529609051994

PMID:8888433

Abstract

BACKGROUND

The intestinal epithelium, with the potential to restrict luminal noxae from the host, secretes a mucous layer with various protective functions. Microbial colonization of germfree (GF) rats stimulates this mucin-secreting tissue. The present study determined the effect of bacterial lipopolysaccharides (LPS) on this process.

METHODS

One, 3, and 5 days after peroral application of 35 micrograms LPS/100 g body weight (from Escherichia coli O55:B5), LPS concentrations were monitored in ingesta, intestinal tissue, and liver. Mucin high molecular weight glycoproteins (HMG), released in response to LPS, were isolated and separated into mucins, i) attached to the colonic epithelium (EM) and ii) mixed to the luminal content (LM), respectively. Subsequently, the binding capacity of both mucin fractions for various lectins and for type-1 pili expressing E. coli was determined.

RESULTS

Ingesta and tissue had maximal LPS concentrations on days 3 (jejunum) and 5 (colon). Maximal EM secretion was found on day 3, release of LM further increased to day 5. Both mucin fractions had altered glycosylation patterns: augmentation of beta-galactose, alpha-N-acetyl galactosamine, and mannose coincided with a decrease in alpha-fucose. Compared with the controls, attachment of E. coli to EM increased slightly on day 1 only; the binding capacity of LM increased continuously up to day 5.

CONCLUSION

Results suggest that mucins, released in response to LPS, in addition to the epithelial protection, support the gut microbial clearance system.

摘要

背景

肠道上皮细胞能够分泌具有多种保护功能的黏液层，从而限制管腔有害物质对宿主的侵害。无菌（GF）大鼠的微生物定植会刺激这种分泌黏蛋白的组织。本研究确定了细菌脂多糖（LPS）对这一过程的影响。

方法

经口给予35微克LPS/100克体重（来自大肠杆菌O55:B5）后1、3和5天，监测摄入物、肠道组织和肝脏中的LPS浓度。分离出因LPS而释放的黏蛋白高分子量糖蛋白（HMG），并分别分离为：i）附着于结肠上皮的黏蛋白（EM）和ii）与管腔内容物混合的黏蛋白（LM）。随后，测定了这两种黏蛋白组分对各种凝集素和表达1型菌毛的大肠杆菌的结合能力。

结果

摄入物和组织中的LPS浓度在第3天（空肠）和第5天（结肠）达到最高。EM的最大分泌量出现在第3天，LM的释放量在第5天进一步增加。两种黏蛋白组分的糖基化模式均发生改变：β-半乳糖、α-N-乙酰半乳糖胺和甘露糖增加，同时α-岩藻糖减少。与对照组相比，大肠杆菌与EM的附着仅在第1天略有增加；LM的结合能力持续增加至第5天。