Reunanen Justus, Kainulainen Veera, Huuskonen Laura, Ottman Noora, Belzer Clara, Huhtinen Heikki, de Vos Willem M, Satokari Reetta
Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland.
Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
Appl Environ Microbiol. 2015 Jun;81(11):3655-62. doi: 10.1128/AEM.04050-14. Epub 2015 Mar 20.
Akkermansia muciniphila is a Gram-negative mucin-degrading bacterium that resides in the gastrointestinal tracts of humans and animals. A. muciniphila has been linked with intestinal health and improved metabolic status in obese and type 2 diabetic subjects. Specifically, A. muciniphila has been shown to reduce high-fat-diet-induced endotoxemia, which develops as a result of an impaired gut barrier. Despite the accumulating evidence of the health-promoting effects of A. muciniphila, the mechanisms of interaction of the bacterium with the host have received little attention. In this study, we used several in vitro models to investigate the adhesion of A. muciniphila to the intestinal epithelium and its interaction with the host mucosa. We found that A. muciniphila adheres strongly to the Caco-2 and HT-29 human colonic cell lines but not to human colonic mucus. In addition, A. muciniphila showed binding to the extracellular matrix protein laminin but not to collagen I or IV, fibronectin, or fetuin. Importantly, A. muciniphila improved enterocyte monolayer integrity, as shown by a significant increase in the transepithelial electrical resistance (TER) of cocultures of Caco-2 cells with the bacterium. Further, A. muciniphila induced interleukin 8 (IL-8) production by enterocytes at cell concentrations 100-fold higher than those for Escherichia coli, suggesting a very low level of proinflammatory activity in the epithelium. In conclusion, our results demonstrate that A. muciniphila adheres to the intestinal epithelium and strengthens enterocyte monolayer integrity in vitro, suggesting an ability to fortify an impaired gut barrier. These results support earlier associative in vivo studies and provide insights into the interaction of A. muciniphila with the host.
嗜黏蛋白阿克曼氏菌是一种革兰氏阴性的黏蛋白降解细菌，存在于人类和动物的胃肠道中。嗜黏蛋白阿克曼氏菌与肠道健康以及肥胖和2型糖尿病受试者代谢状况的改善有关。具体而言，嗜黏蛋白阿克曼氏菌已被证明可降低高脂饮食诱导的内毒素血症，这种内毒素血症是由于肠道屏障受损而产生的。尽管有越来越多的证据表明嗜黏蛋白阿克曼氏菌具有促进健康的作用，但该细菌与宿主相互作用的机制却很少受到关注。在本研究中，我们使用了几种体外模型来研究嗜黏蛋白阿克曼氏菌与肠上皮的黏附及其与宿主黏膜的相互作用。我们发现，嗜黏蛋白阿克曼氏菌能强烈黏附于Caco-2和HT-29人结肠细胞系，但不黏附于人类结肠黏液。此外，嗜黏蛋白阿克曼氏菌显示出与细胞外基质蛋白层粘连蛋白结合，但不与I型或IV型胶原蛋白、纤连蛋白或胎球蛋白结合。重要的是，嗜黏蛋白阿克曼氏菌改善了肠上皮细胞单层的完整性，这表现为Caco-2细胞与该细菌共培养时跨上皮电阻（TER）显著增加。此外，嗜黏蛋白阿克曼氏菌在细胞浓度比大肠杆菌高100倍时诱导肠上皮细胞产生白细胞介素8（IL-8），这表明上皮细胞中的促炎活性水平非常低。总之，我们的结果表明，嗜黏蛋白阿克曼氏菌在体外黏附于肠上皮并增强肠上皮细胞单层的完整性，这表明它有能力加强受损的肠道屏障。这些结果支持了早期的体内相关性研究，并为嗜黏蛋白阿克曼氏菌与宿主的相互作用提供了见解。
