Defensins are critical components of the innate immune system and play an important role in the integration of innate and adaptive immune responses. Although information on the immunomodulatory properties of peptidoglycan from bacteria is abundant, little is known about the β-defensin induction effect of peptidoglycan from the probiotic Lactobacillus. This study investigated the effect of intact peptidoglycan from L. rhamnosus MLGA on the induction of avian β-defensin 9 in chicken immune cells and intestinal explants. Peptidoglycan from Lactobacillus rhamnosus MLGA dose dependently promoted avian β-defensin 9 mRNA expression in chicken PBMCs, splenocytes, thymocytes, hepatocytes, and chicken embryo jejunum, ileum, and cecum explants and increased the capacity of PBMC or splenocyte lysates to inhibit the growth of Salmonella Enteritidis. In contrast to the effect of L. rhamnosus MLGA-derived peptidoglycan, peptidoglycan derived from pathogenic Staphylococcus aureus reduced avian β-defensin 9 mRNA expression in chicken PBMCs and splenocytes. The inducible effect of peptidoglycan from L. rhamnosus MLGA on avian β-defensin 9 expression in PBMCs and splenocytes was observed without activation of the expression of associated pro-inflammatory cytokines IL-1β, IL-8, and IL-12p40, whereas these cytokine expressions were suppressed by peptidoglycan hydrolysate obtained by lysozyme digestion. The results of the present study show the capability of peptidoglycan derived from L. rhamnosus MLGA to induce the antimicrobial peptide defensin while simultaneously avoiding the deleterious risks of an inflammatory response.

防御素是先天免疫系统的重要组成部分，在先天免疫和适应性免疫反应的整合中发挥重要作用。尽管关于来自细菌的肽聚糖的免疫调节特性的信息很多，但对来自益生菌乳杆菌的肽聚糖的 β-防御素诱导作用知之甚少。本研究调查了来自鼠李糖乳杆菌MLGA的完整肽聚糖对鸡免疫细胞和肠外植体中禽类 β-防御素 9 的诱导作用。鼠李糖乳杆菌肽聚糖MLGA剂量依赖性地促进了禽流β防御素在鸡的PBMC，脾细胞，胸腺细胞，肝细胞，和鸡胚空肠，回肠9 mRNA的表达，和盲肠外植体和增加PBMC或脾细胞裂解物，以抑制生长的能力沙门氏菌肠炎。与鼠李糖乳杆菌MLGA 衍生肽聚糖的作用相反，来自致病性金黄色葡萄球菌的肽聚糖降低了鸡 PBMC 和脾细胞中禽类 β-防御素 9 mRNA 的表达。鼠李糖乳杆菌肽聚糖的诱导作用在 PBMC 和脾细胞中观察到 MLGA 对禽类 β-防御素 9 表达的影响，但没有激活相关促炎细胞因子 IL-1β、IL-8 和 IL-12p40 的表达，而这些细胞因子的表达被溶菌酶获得的肽聚糖水解物抑制消化。本研究的结果表明，鼠李糖乳杆菌MLGA衍生的肽聚糖能够诱导抗菌肽防御素，同时避免炎症反应的有害风险。