Hu Aixin, Huang Wenxia, Shu Xin, Ma Shiyue, Yang Caimei, Zhang Ruiqiang, Xiao Xiao, Wu Yanping
Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology, College of Veterinary Medicine, Zhejiang Agriculture and Forestry University, Hangzhou 311300, China.
Animals (Basel). 2023 Oct 14;13(20):3215. doi: 10.3390/ani13203215.
Our study aimed to explore the effects of postbiotics on protecting against infection in mice and clarify the underlying mechanisms. Eighty 5-week-old C57BL/6 mice were gavaged daily with (LP)-derived postbiotics (heat-killed bacteria, LPB; culture supernatant, LPC) or the active bacteria (LPB), and gavaged with Typhimurium (ST). The Turbidimetry test and agar diffusion assay indicated that LPC directly inhibited growth. Real-time PCR and biofilm inhibition assay showed that LPC had a strong ability in suppressing pathogenicity by reducing virulence genes (, , , , , , and 2), pili genes (, , , ), flagellum genes (, , ) and biofilm formation. LP postbiotics were more effective than LP on attenuating ST-induced intestinal damage in mice, as indicated by increasing villus/crypt ratio and increasing the expression levels of tight junction proteins (Occludin and Claudin-1). Elisa assay showed that LP postbiotics significantly reduced ST-induced inflammation by regulating the levels of inflammatory cytokines (the increased IL-4 and IL-10 and the decreased TNF-α) in serum and ileum ( < 0.05). Furthermore, LP postbiotics inhibited the activation of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome by decreasing the protein expression of NLRP3 and Caspase-1, and the gene expression of -, and -. Meanwhile, both LPC and LPB observably activated autophagy under ST infection, as indicated by the up-regulated expression of LC3 and Beclin1 and the downregulated p62 level ( < 0.05). Finally, we found that LP postbiotics could trigger an AMP-activated protein kinase (AMPK) signaling pathway to induce autophagy. In summary, -derived postbiotics alleviated infection via modulating bacterial pathogenicity, autophagy and NLRP3 inflammasome in mice. Our results confirmed the effectiveness of postbiotics agents in the control of infection.
我们的研究旨在探讨后生元对小鼠抗感染的影响，并阐明其潜在机制。80只5周龄的C57BL/6小鼠每天灌胃给予罗伊氏乳杆菌（LP）来源的后生元（热灭活细菌，LPB；培养上清液，LPC）或活性细菌（LPB），并灌胃给予鼠伤寒沙门氏菌（ST）。比浊法试验和琼脂扩散试验表明，LPC直接抑制ST生长。实时荧光定量PCR和生物膜抑制试验表明，LPC具有很强的抑制ST致病性的能力，可通过降低毒力基因（hilA、invA、spvC、spvR、sseB、sseC、sipA和sopE2）、菌毛基因（fimA、fimC、fimH、mrkA）、鞭毛基因（flhD、flhC、fliC）的表达以及生物膜形成来实现。LP后生元在减轻ST诱导的小鼠肠道损伤方面比LP更有效，表现为绒毛/隐窝比值增加以及紧密连接蛋白（闭合蛋白和Claudin-1）表达水平升高。酶联免疫吸附测定表明，LP后生元通过调节血清和回肠中炎性细胞因子（IL-4和IL-10升高，TNF-α降低）的水平，显著减轻ST诱导的炎症（P<0.05）。此外，LP后生元通过降低NOD样受体热蛋白结构域相关蛋白3（NLRP3）炎性小体的NLRP3和半胱天冬酶-1蛋白表达以及ASC、pro-IL-1β和pro-IL-18的基因表达，抑制NLRP3炎性小体的激活。同时，在ST感染下，LPC和LPB均能明显激活自噬反应，表现为LC3和Beclin1表达上调以及p62水平下调（P<0.05）。最后，我们发现LP后生元可触发AMP激活蛋白激酶（AMPK）信号通路以诱导自噬。综上所述，LP来源的后生元通过调节细菌致病性、自噬和NLRP3炎性小体减轻了ST感染。我们的结果证实了后生元制剂在控制ST感染方面具有有效性。
