Genda Tomomi, Sasaki Yuta, Kondo Takashi, Hino Shingo, Nishimura Naomichi, Tsukahara Takamitsu, Sonoyama Kei, Morita Tatsuya
Graduate School of Science and Technology and.
College of Agriculture, Academic Institute, Shizuoka University, Shizuoka, Japan.
J Nutr. 2017 Oct;147(10):1900-1908. doi: 10.3945/jn.117.253955. Epub 2017 Aug 23.
The mechanism underlying transient increases in immunoglobulin (Ig) A concentrations in the cecal contents of rats fed fructo-oligosaccharide (FOS) is unclear. This study was designed to test whether increased IgA concentrations represent one aspect of the inflammatory response to increased permeability induced by FOS in the cecum. Seven-week-old male Wistar rats were fed a fiber-free semipurified diet (FFP) with or without supplemental FOS (60 g/kg diet) for 9 or 58 d [experiment (expt.) 1], 7 d (expt. 2), or 7 or 56 d (expt. 3). In addition to measuring IgA concentrations in cecal content, we assessed gut permeability, inflammatory responses (expt. 1), the number of IgA plasma cells in the cecal lamina propria, polymeric Ig receptor (pIgR) expression in the cecal mucosa (expt. 2), and the condition of the cecal mucus layer (expt. 3). The cecal IgA concentration in the FOS-fed rats was 15-fold higher than that of the rats fed FFP for 9 d ( < 0.05). Gut permeability estimated by urinary chromium-EDTA excretion, bacterial translocation to mesenteric lymph nodes, myeloperoxidase activity, and expression of inflammatory cytokine genes in the cecal mucosa was greater in the FOS-fed rats than in the rats fed FFP for 9 d. These effects were not observed in the rats fed FOS for 58 d (expt. 1). Accompanying the higher cecal IgA concentration, pIgR protein and the number of IgA plasma cells in the cecal mucosa were higher in the FOS-fed rats than in the rats fed FFP for 7 d (expt. 2). Destruction of the mucus layer on the epithelial surface, as evidenced by Alcian blue staining in the cecal sections, was evident in the rats fed FOS for 7 d, but the mucus layer appeared normal in the rats fed FOS for 56 d (expt. 3). These findings suggest that transient increases in cecal IgA concentrations induced by FOS in rats are associated with mucosal inflammation in response to increased gut permeability; these are presumably evoked by disruption of the cecal mucus barrier. The observed responses could contribute to the maturation of the gut immune system.
喂食低聚果糖（FOS）的大鼠盲肠内容物中免疫球蛋白（Ig）A浓度出现短暂升高，其潜在机制尚不清楚。本研究旨在测试IgA浓度升高是否代表了FOS诱导的盲肠通透性增加所引发的炎症反应的一个方面。将7周龄雄性Wistar大鼠喂食不含纤维的半纯化日粮（FFP），添加或不添加FOS（60克/千克日粮），持续9天或58天[实验（expt.）1]、7天（expt. 2）或7天或56天（expt. 3）。除了测量盲肠内容物中的IgA浓度外，我们还评估了肠道通透性、炎症反应（实验1）、盲肠固有层中IgA浆细胞的数量、盲肠黏膜中聚合免疫球蛋白受体（pIgR）的表达（实验2）以及盲肠黏液层的状况（实验3）。喂食FOS的大鼠盲肠IgA浓度比喂食FFP 9天的大鼠高15倍（<0.05）。通过尿铬-乙二胺四乙酸排泄量估计的肠道通透性、细菌向肠系膜淋巴结的移位、髓过氧化物酶活性以及盲肠黏膜中炎症细胞因子基因的表达，在喂食FOS的大鼠中比喂食FFP 9天的大鼠更高。在喂食FOS 58天的大鼠中未观察到这些影响（实验1）。伴随着较高的盲肠IgA浓度，喂食FOS的大鼠盲肠黏膜中pIgR蛋白和IgA浆细胞的数量比喂食FFP 7天的大鼠更高（实验2）。通过盲肠切片中的阿尔辛蓝染色证明，喂食FOS 7天的大鼠上皮表面黏液层遭到破坏，但喂食FOS 56天的大鼠黏液层看起来正常（实验3）。这些发现表明，FOS诱导的大鼠盲肠IgA浓度短暂升高与肠道通透性增加所引发的黏膜炎症有关；这些可能是由盲肠黏液屏障的破坏引起的。观察到的这些反应可能有助于肠道免疫系统的成熟。
