Pasteurella multocida is a gram-negative bacterial pathogen, which causes a large number of diseases in mammals, birds and human. Although the bacterium has been known for decades, the pathogenesis and the mechanisms of P. multocida induced host immunity are poorly understood. Recently, we have reported that nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome plays an important role in caspase-1 activation and IL-1β secretion in macrophages infected with P. multocida. In this study, the inflammasome activation and IL-1β secretion were further demonstrated by using high- and low-virulent bovine P. multocida isolates. The results showed that, comparing with macrophages infected with the high-virulent PmCQ2 isolates, the low-virulent PmCQ6 induced higher levels of NLRP3 transcription, caspase-1 activation and mature IL-1β secretion. Furthermore, the capsule of the high-virulent PmCQ2 was much thicker than that of low-virulent PmCQ6, which indicating that capsular thickness might influence the bacteria colonization and NLRP3 inflammasome activation. The results suggested that differences in maturation of IL-1β in macrophages upon high- and low- virulent P. multocida infection are critically dependent on the differential activation of NLRP3 inflammasome. This study provided more understanding for the host immune responses induced by P. multocida and further extended the knowledge of P. multocida virulence from the view of host innate immunity.

多杀性巴斯德氏菌是革兰氏阴性细菌病原体，在哺乳动物，鸟类和人类中引起大量疾病。尽管这种细菌已经知道了几十年，但对多杀毕赤酵母诱导的宿主免疫的发病机理和机制却知之甚少。最近，我们已经报道了核苷酸结合的寡聚化结构域样受体家族，含有3（NLRP3）炎性小体的吡啶结构域在感染多杀性疟原虫的巨噬细胞中的caspase-1激活和IL-1β分泌中起着重要作用。在这项研究中，通过使用高毒力和低毒力的牛多杀性巴氏杆菌进一步证明了炎症小体的活化和IL-1β的分泌。隔离株。结果表明，与感染高毒力PmCQ2分离株的巨噬细胞相比，低毒力PmCQ6诱导了更高水平的NLRP3转录，caspase-1激活和成熟的IL-1β分泌。此外，高毒力的PmCQ2的胶囊比低毒力的PmCQ6的胶囊厚得多，这表明荚膜的厚度可能影响细菌的定殖和NLRP3炎性体的活化。结果表明，在高毒力和低毒力的多杀性毕赤酵母感染后，巨噬细胞中IL-1β成熟的差异主要取决于NLRP3炎性体的差异激活。这项研究提供了更多的了解由多杀性疟原虫诱导的宿主免疫反应，并进一步扩展了对从宿主先天免疫的角度来看，多杀青霉的毒力。