Natural Medicine Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
Key laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China.
J Proteomics. 2017 Aug 23;166:39-47. doi: 10.1016/j.jprot.2017.06.020. Epub 2017 Jul 2.
Haemophilus parasuis, a symbiotic bacteria of upper respiratory tract of swine, is the etiological agent of Glässer's disease, which is characterized by fibrinous polyserositis. Emodin, exhibits antibacterial activity against H. parasuis, yet the action mode has not been fully understood. In present study, isobaric tag for relative and absolute quantification (iTRAQ) method was applied to analyze the global protein alteration of H. parasuis in response to 16μg/mL Emodin. In total, 338 proteins exhibiting significant differential expressions were identified. It was speculated that, through application of bioinformatics analysis to theses differentially expressed proteins, Emodin mainly inhibited some key proteins expression of ABC transport system, carbohydrate metabolism pathway and bacterial cell division by inhibiting the ribosome synthesis, resulting in the growth inhibition of H. parasuis. Remarkably, nine virulence-associated proteins were detected differently expressed, further experiments revealed that after treatment with Emodin, H. parasuis could be inhibited to adhere to and invade into porcine kidney epithelial cells (PK-15 line) and exhibited increased sensitivity to serum complement in a concentration-dependent manner. Phagocytosis assay showed Emodin also could enhance phagocytic activity of porcine alveolar macrophages PAM to H. parasuis. These results indicated that Emodin also can attenuate virulence of H. parasuis and reduce infection.
The Glässer's disease caused by H. parasuis has become a typical bacterial disease and cause serious economic loss to the swine industry around the world. Antibiotics are extensively used to control the infection, but increasing antibiotic resistance has been a severe problem. Hence, novel treatment agents are needed. So far, few antibacterial agents were reported that could control H. parasuis infection. In the present study, the state-of-the-art quantitative proteomic technology was applied to uncover underlying action mechanism of Emodin. This study extends understanding of antibacterial effect of Emodin to H. parasuis at molecular level and provides useful information for further investigations. Moreover, our results provide theoretical foundation for the practical application of Emodin.
猪嗜血杆菌是猪上呼吸道的共生菌，是格拉泽氏病的病原体，其特征为纤维蛋白性多发性浆膜炎。大黄素有抗猪嗜血杆菌的活性，但作用模式尚未完全了解。本研究采用同位素质谱标签相对和绝对定量（iTRAQ）方法分析了大黄素（16μg/ml）作用下猪嗜血杆菌的全蛋白变化。共鉴定出 338 种表达差异显著的蛋白质。推测通过对这些差异表达蛋白进行生物信息学分析，大黄素主要通过抑制核糖体合成，抑制 ABC 转运系统、碳水化合物代谢途径和细菌细胞分裂的一些关键蛋白表达，从而抑制猪嗜血杆菌的生长。值得注意的是，检测到 9 种毒力相关蛋白表达不同，进一步的实验表明，大黄素处理后，猪嗜血杆菌对猪肾上皮细胞（PK-15 系）的黏附和侵袭能力受到抑制，并表现出浓度依赖性的血清补体敏感性增加。吞噬试验表明，大黄素还能增强猪肺泡巨噬细胞 PAM 对猪嗜血杆菌的吞噬活性。这些结果表明，大黄素还能减轻猪嗜血杆菌的毒力，降低感染率。
由猪嗜血杆菌引起的格拉泽氏病已成为一种典型的细菌性疾病，给世界各地的养猪业造成了严重的经济损失。抗生素被广泛用于控制感染，但抗生素耐药性的增加已成为一个严重的问题。因此，需要新型治疗剂。到目前为止，很少有报道称抗菌剂能够控制猪嗜血杆菌感染。本研究采用最先进的定量蛋白质组学技术，揭示了大黄素的作用机制。本研究从分子水平上扩展了对大黄素抗猪嗜血杆菌作用的认识，为进一步研究提供了有用的信息。此外，我们的研究结果为大黄素的实际应用提供了理论基础。
