Department of Animal Science, Oklahoma State University , Stillwater, OK , USA.
Hubei Key Laboratory of Animal Nutrition and Feed Science, Wuhan Polytechnic University , Wuhan , China.
Front Vet Sci. 2015 Nov 23;2:57. doi: 10.3389/fvets.2015.00057. eCollection 2015.
Intestinal barrier function is achieved primarily through regulating the synthesis of mucins and tight junction (TJ) proteins, which are critical for maintaining optimal gut health and animal performance. An aberrant expression of TJ proteins results in increased paracellular permeability, leading to intestinal and systemic disorders. As an essential component of innate immunity, host defense peptides (HDPs) play a critical role in mucosal defense. Besides broad-spectrum antimicrobial activities, HDPs promotes inflammation resolution, endotoxin neutralization, wound healing, and the development of adaptive immune response. Accumulating evidence has also indicated an emerging role of HDPs in barrier function and intestinal homeostasis. HDP deficiency in the intestinal tract is associated with barrier dysfunction and dysbiosis. Several HDPs were recently shown to enhance mucosal barrier function by directly inducing the expression of multiple mucins and TJ proteins. Consistently, dietary supplementation of HDPs often leads to an improvement in intestinal morphology, production performance, and feed efficiency in livestock animals. This review summarizes current advances on the regulation of epithelial integrity and homeostasis by HDPs. Major signaling pathways mediating HDP-induced mucin and TJ protein synthesis are also discussed. As an alternative strategy to antibiotics, supplementation of exogenous HDPs or modulation of endogenous HDP synthesis may have potential to improve intestinal barrier function and animal health and productivity.
肠道屏障功能主要通过调节黏蛋白和紧密连接（TJ）蛋白的合成来实现，这对于维持最佳肠道健康和动物生产性能至关重要。TJ 蛋白的异常表达会导致细胞旁通透性增加，从而导致肠道和全身紊乱。作为先天免疫的重要组成部分，宿主防御肽（HDP）在黏膜防御中发挥着关键作用。除了广谱的抗菌活性外，HDP 还能促进炎症的解决、内毒素中和、伤口愈合和适应性免疫反应的发展。越来越多的证据也表明，HDP 在屏障功能和肠道稳态中具有新兴作用。肠道中 HDP 的缺乏与屏障功能障碍和菌群失调有关。最近有研究表明，几种 HDP 通过直接诱导多种黏蛋白和 TJ 蛋白的表达来增强黏膜屏障功能。同样，在畜牧动物中，日粮中添加 HDP 通常会改善肠道形态、生产性能和饲料效率。本综述总结了 HDP 调节上皮完整性和稳态的最新进展。还讨论了介导 HDP 诱导黏蛋白和 TJ 蛋白合成的主要信号通路。作为抗生素的替代策略，补充外源性 HDP 或调节内源性 HDP 合成可能具有改善肠道屏障功能和动物健康和生产力的潜力。
