Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8528, Japan; Research Center for Animal Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
Poult Sci. 2020 Jul;99(7):3385-3392. doi: 10.1016/j.psj.2020.03.016. Epub 2020 Apr 15.
The aim of this study was to confirm whether the expression of innate immune molecules in the chick cecum is altered in association with changes in the composition of the intestinal microbiome that are regulated by treatment with antibiotics. Broiler chicks were administered with antibiotics (penicillin and streptomycin) daily, and the composition of the microbiota, expression of innate immune molecules, and localization of antimicrobial peptides in the chick cecum were examined at day 7 and day 14 using real-time PCR and immunohistochemistry. The oral administration of antibiotics caused an increase in the relative frequency of the Enterobacteriaceae family and a decrease in some gram-negative (Barnesiellaceae) and gram-positive bacterial (Clostridiaceae and Erysipelotrichaceae) families. The gene expression levels of immune molecules, including 4 Toll-like receptors (TLR) (TLR 2, 4, 5, and 21), inflammation-related cytokines (IL-1β, TGFβ3, TGFβ4, and IL-8), and antimicrobial peptides (avian β-defensins and cathelicidins) showed a tendency to decrease with antibiotic treatment at day 7. However, expression levels of TLR21 and some cytokines (IL-1β, TGFβ3, and IL-8) were higher in the cecum or cecal tonsils of the antibiotic-treated group than in those of the control at day 14. The immunoreactive avian β-defensin 2 and cathelicidin 1 proteins were localized in the leukocyte-like cells in the lamina propria, and they were aggregated in the form of small islands. We conclude that the expression of innate immune molecules, including TLR, inflammation-related cytokines, and antimicrobial peptides, in the cecum are altered in association with changes in the density or composition of the luminal microbiota during the early phase of life in chicks.
本研究旨在确认在鸡盲肠中，固有免疫分子的表达是否会因抗生素处理调节的肠道微生物群落组成的变化而发生改变。将肉鸡雏鸡每天给予抗生素（青霉素和链霉素），并在第 7 天和第 14 天使用实时 PCR 和免疫组织化学检查鸡盲肠中微生物群落的组成、固有免疫分子的表达和抗菌肽的定位。抗生素的口服给药导致肠杆菌科家族的相对频率增加，而一些革兰氏阴性（Barnesiellaceae）和革兰氏阳性（Clostridiaceae 和 Erysipelotrichaceae）细菌家族的相对频率减少。包括 4 种 Toll 样受体（TLR）（TLR2、4、5 和 21）、炎症相关细胞因子（IL-1β、TGFβ3、TGFβ4 和 IL-8）和抗菌肽（禽 β-防御素和 cathelicidins）在内的免疫分子的基因表达水平在第 7 天抗生素处理时呈下降趋势。然而，在第 14 天，抗生素处理组的盲肠或盲肠扁桃体中的 TLR21 和一些细胞因子（IL-1β、TGFβ3 和 IL-8）的表达水平高于对照组。免疫反应性禽 β-防御素 2 和 cathelicidin 1 蛋白定位于固有层中的白细胞样细胞中，并以小岛屿的形式聚集。我们得出结论，在鸡生命早期阶段，盲肠中固有免疫分子（包括 TLR、炎症相关细胞因子和抗菌肽）的表达会因腔内微生物群落密度或组成的变化而发生改变。
