Laboratory of Veterinary Pharmacokinetics and Pharmacodynamics, College of Veterinary Medicine, Kyungpook National University, Bukgu, Daegu, South Korea.
PLoS One. 2019 Sep 6;14(9):e0221386. doi: 10.1371/journal.pone.0221386. eCollection 2019.
Nymphaea tetragona Georgi (Nymphaceae) is traditionally used in Asia for the treatment of diarrhea, dysentery and fever. The plant contains various active compounds, including methyl gallate (MG) which are reported to inhibit bacterial virulence mechanisms. This study aimed to evaluate the alterations on viability, membrane potential and integrity of Salmonella enterica Serovar Typhimurium exposed to MG in combination with Tylosin (Ty), which is relatively inactive against Gram-negative bacteria, but it is commonly used as a feed additive in livestock. Besides, the effects of sub-inhibitory concentrations of the combination (MT) on the interaction between S. Typhimurium and the host cell, as well as on the indirect host responses, were characterized. Flow cytometry, confocal and electron microscopic examinations were undertaken to determine the effects of MT on S. Typhimurium. The impacts of sub-inhibitory concentrations of MT on biofilm formation, as well as on the adhesion, invasion and intracellular survival of S. Typhimurium were assessed. The result demonstrated significant damage to the bacterial membrane, leakage of cell contents and a reduction in the membrane potential when treated with MT. Sub-inhibitory concentrations of MT significantly reduced (P < 0.05) the biofilm-forming, adhesive and invasive abilities of S. Typhimurium. Exposure to MT drastically reduced the bacterial count in macrophages. Up-regulation of interleukin (IL)-6, IL-8 and IL-10 cytokine genes were detected in intestinal epithelial cells pre-treated with MT. This report is the first to describe the effects of MT against S. Typhimurium. The result indicates a synergistic interaction between MG and Ty against S. Typhimurium. Therefore, the combination may be a promising option to combat S. Typhimurium in swine and, indirectly, safeguard the health of the public.
芡实属（Nymphaceae）植物四叶萍被亚洲传统医学用于治疗腹泻、痢疾和发热。该植物含有多种活性化合物，包括被报道能够抑制细菌毒力机制的甲基没食子酸（MG）。本研究旨在评估在暴露于 MG 与泰乐菌素（Ty）的混合物时，鼠伤寒沙门氏菌（Salmonella enterica Serovar Typhimurium）的活力、膜电位和完整性的变化，Ty 相对来说对革兰氏阴性菌没有活性，但它通常被用作牲畜的饲料添加剂。此外，还研究了亚抑菌浓度组合（MT）对宿主细胞相互作用以及间接宿主反应的影响。采用流式细胞术、共聚焦和电子显微镜检查来确定 MT 对鼠伤寒沙门氏菌的影响。研究了 MT 对生物膜形成以及鼠伤寒沙门氏菌的黏附、侵袭和细胞内存活的影响。结果表明，MT 处理会导致细菌膜严重受损、细胞内容物泄漏和膜电位降低。亚抑菌浓度的 MT 显著降低了鼠伤寒沙门氏菌的生物膜形成、黏附能力和侵袭能力（P<0.05）。MT 暴露使巨噬细胞中的细菌数量明显减少。在 MT 预处理的肠上皮细胞中检测到细胞因子白细胞介素（IL）-6、IL-8 和 IL-10 的基因表达上调。这是首次描述 MT 对鼠伤寒沙门氏菌的作用。结果表明 MG 和 Ty 对鼠伤寒沙门氏菌具有协同作用。因此，该组合可能是对抗猪源鼠伤寒沙门氏菌的一种有前途的选择，并间接地保护公众健康。
