猪结肠源分离菌对结肠炎小鼠肠道细胞因子和转录因子表达的调节

Bacteria from porcine colon regulate cytokine and transcription factor expression in the gut of the mouse model of colitis

摘要:

【背景】哺乳动物消化道中的微生物对肠道稳态的维持十分重要，但肠道细菌在调节细胞因子表达等方面发挥的调节作用还有待研究。【目的】探究猪肠道不同分离菌株在结肠炎模型中对细胞因子和转录因子的调节差异。【方法】从猪结肠分离培养单菌，在脂多糖(lipopolysaccharides,LPS)诱导的Caco-2细胞炎症模型中，用细菌上清液孵育细胞；进一步试验采用葡聚糖硫酸钠诱导的结肠炎小鼠模型，用细菌悬浮液进行灌胃，检测细菌处理后Caco-2细胞和小鼠结肠组织中细胞因子和转录因子基因表达、细胞生长率、小鼠体重等指标。【结果】从猪结肠中分离得到6株菌，分别属于Enterococcus、Lactobacillus、Sharpea和Mitsuokella。在LPS诱导炎症Caco-2细胞炎症模型中，Lactobacillus amylovorus LGM显著下调白细胞介素(interleukin,IL)-4和IL-17的mRNA表达(P<0.05)；Enterococcus cecorum LGM处理显著下调T盒子转录因子(T-box expressed in T cells,T-bet)、叉状头转录因子3(forkhead box P3,Foxp3)、IL-17和转化生长因子-β(transforming growth factor β,TGF-β) mRNA表达(P<0.05)。在菌液灌胃结肠炎小鼠试验中，只有Lactobacillus amylovorus LGM能够明显改善结肠炎症，恢复结肠长度，结肠组织中Foxp3、GATA结合蛋白3(GATA binding protein 3,GATA-3)和干扰素-γ(interferon-gamma,IFN-γ) mRNA表达上升(P<0.05)。相反地，Mitsuokella jalaludinii LGM处理加重结肠损伤，组织中干扰素-γ mRNA表达水平升高(P<0.05)。【结论】6株分离菌对猪肠道结肠炎的调节作用不同，这与不同菌株对细胞因子基因表达的调节有关。Lactobacillus amylovorus LGM通过上调结肠中的转录因子Foxp3和GATA-3可以发挥一定程度的抗炎症作用。

关键词:肠道微生物;猪;乳酸菌;结肠炎;细胞因子

Abstract:

[Background] Microorganisms in the mammalian digestive tract are important for maintaining gut homeostasis, while the regulatory role of gut bacteria in cytokine expression remains unclarified. [Objective] To compare the regulatory effects of different isolated from porcine intestinal tract on the expression of cytokines and transcription factors in the model of colitis. [Methods] Bacteria were isolated from the porcine colon, and the culture supernatant of each isolate was used to treat the Caco-2 cell model of lipopolysaccharide-induced inflammation. Furthermore, a mouse model of colitis was induced by dextran sodium sulfate (DSS) and then administrated with bacterial suspension by gavage. The gene expression of cytokines and transcription factors in Caco-2 cells and mouse colon tissue, the cell growth rate, and the mouse weight after bacterial treatment were determined. [Results] Six strains of bacteria were isolated from porcine colon, belonging to Enterococcus, Lactobacillus, Sharpea, and Mitsuokella. In the Caco-2 cell model of inflammation, Lactobacillus amylovorus LGM down-regulated the mRNA levels of interleukin (IL)-4 and IL-17 (P<0.05); Enterococcus cecorum LGM down-regulated the mRNA levels of T-box expressed in T cells (T-bet), forkhead box P3 (Foxp3), IL-17, and transforming growth factor-β (TGF-β) (P<0.05). In the mouse model of colitis, only L. amylovorus LGM alleviated the colon inflammation, restored the colon length, and up-regulated the mRNA levels of Foxp3, GATA Binding Protein 3 (GATA-3), and interferon-γ (IFN-γ) in the colon tissue (P<0.05). However, Mitsuokella jalaludinii LGM aggravated colon injury and up-regulated the mRNA level of interferon-γ in the tissue (P<0.05). [Conclusion] The bacterial isolates have different regulatory effects on porcine colitis, which is related to the regulation of cytokine gene expression. L. amylovorus LGM exerts an anti-inflammatory effect by up-regulating the expression of Foxp3 and GATA-3 in the colon.

Key words:gut microorganisms;pigs;lactic acid bacteria;colitis;cytokines