副猪嗜血杆菌和PCV2共感染对猪肺泡巨噬细胞免疫分子表达的影响

Effects of Haemophilus parasuis and Porcine Circovirus Type 2 Coinfection on mRNA Expression of Immune Molecules in Porcine Alveolar Macrophages

副猪嗜血杆菌(Hps)是猪上呼吸道常见条件致病菌之一,在临床上Hps和圆环病毒2型(PCV2)混合感染加剧了断奶仔猪多系统衰竭综合征的症状。为探讨Hps和PCV2共感染的致病机制,本试验建立了体外Hps和PCV2共感染猪肺泡巨噬细胞(PAM)的模型,分别检测感染12、24 h和36 h后的PAM细胞因子(IL-1β、TNF-α、IL-4和IL-10)、猪白细胞抗原(SLA)分子SLA-DR、SLA-DM以及共刺激分子CD 80和CD 86的mRNA转录水平,以探讨其动态变化规律。结果显示,与单一感染相比,Hps和PCV2共感染的PAM在感染24 h内,IL-1β和TNF-α表达水平显著上升(P<0.05),而IL-4和IL-10表达显著下降(P<0.05);在感染36 h内,CD 80、CD 86及SLA-DM、SLA-DR的表达水平显著下降(P<0.05)。结果表明,Hps和PCV2共感染增进了PAM促炎症因子表达,抑制了PAM抑炎因子表达及外源性抗原加工和递呈相关分子表达,从而消弱了其免疫功能。

Haemophilus parasuis(Hps)is a common opportunistic pathogen of swine upper respiratory tract.In clinical setting,co-infection with Hps and porcine circovirus type 2(PCV2)exacerbates the symptoms of multiple system failure syndrome(PMWS)in weaned piglets.To study the pathogenic mechanism of Hps and PCV2 infections,co-infection with Hps and PCV2 was established in vitro using swine alveolar macrophages(PAM).The expression levels of PAM cytokines(IL-1β,TNF-α,IL-4 and IL-10),swine leukocyte antigen(SLA–DR,SLA-DM)and stimulating molecules CD 80 and CD 86 were detected using real time PCR at 12,24 h and 36 h post infection(hpi).The results showed that compared with single infections,Hps and PCV2 co-infection significantly increased the expression levels of IL-1βand TNF-α(P<0.05),but significantly decreased the expression levels of IL-4 and IL-10(P<0.05)within 24 hpi.Further,Hps and PCV2 co-infection significantly decreased the expression levels of CD 80,CD 86,SLA-DM and SLA-DR(P<0.05)within 36 hpi.Thus,by increasing the expression of proinflammatory factors,but inhibiting the expression of anti-inflammatory factors,the exogenous antigen processing and related molecules,Hps and PCV2 co-infection ultimately weakens the immune function of porcine alveolar macrophages.