PRRSV-induced Inflammatory Response And Its Regulatory Mechanism

Porcine reproductive and respiratory syndrome (PRRS) is a viral infection disease caused by porcine reproductive and respiratory syndrome virus (PRRSV), has a serious hazard to the swine industry, mainly represents a serious sow reproductive failure and respiratory system disease and growth stagnatim of piglets. PRRSV is a single-stranded RNA virus, since the outbreak in the late1980s, PRRSV has been a serious threat to the global development of pig industry, and caused huge economic losses. Since China reported the disease at1995, it has become one of the most important viral diseases in swine production in China. Especially in China at2006, the appearance of highly pathogenic PRRS, resulting in a large number of pigs were killed across the country, causing huge economic losses to the swine industry in our country. PRRSV can cause a strong interstitial pneumonia in infected pigs, suggesting that the inflammatory response plays a very important role in PRRSV infection and pathogenicity, however, it is poorly understood. For this new PRRSV, we analyzed the signal transduction mechanism of inflammatory response in PRRSV-infected host cell to provide a theoretical basis in order to clarify the pathogenesis of PRRSV. The specific studies include:1. The molecular mechanism of highly pathogenic PRRSV infection activate IL-ip and its biological significanceIL-1β is a pro inflammatory cytokines primarily produced by monocytes, macrophages and lymphocytes, the center medium of body regulating immune and inflammatory responses, can mediate a variety of inflammatory reactions, induces other inflammatory cytokines expression and secretion, plays a very important role in the pathogenesis of inflammatory diseases. Previous studies have found out that PRRSV can induce high levels of IL-1β, but the molecular mechanisms are not yet elucidated. In this study, we used PAMs, the target cells of PRRSV-infected pigs, found PRRSV activates IL-1β both at mRNA expression and protein secretion level. We also analyzed several pattern recognition receptor and its adapter molecule, found out that TLR4/MyD88signal cascade and its downstream signaling pathways including NF-κB, ERK1/2and p38MAPK are involved in the the PRRSV activation of IL-1β. The siRNA interference and specific inhibitor treatment indicated that NLRP3inflammasome involved in PRRSV-induced IL-1β secretion, but didn’t affect the activation of the expression of IL-1β mRNA levels. We also found that the activator to induce NLRP3inflammasome formation-ROS and K+efflux is also involved in PRRSV-induced IL-1β secretion. We also found TLR4/MyD88/NF-KB signaling pathway involved in PRRSV-induced NLRP3inflammasome component expression. In addition, we also analyzed the biological significance of PRRSV-induced IL-1β. Treatment of purified IL-1β protein and its neutralizing antibody on PAMs had no significant effect on the proliferation of PRRSV, but IL-1β neutralizing antibodies can inhibit the the PRRSV activation of other proinflammatory (IL-6, IL-8), indicating the centrol role of IL-1β in PRRSV-induced inflammatory response.2. The molecular mechanism of highly pathogenic PRRSV infection activate IL-6IL-6is a pleiotropic cytokine regulating a variety of biological processes, including the nervous system, the hematopoietic system, stress response, inflammation and immune response. Usually, produced together with the pro-inflammatory cytokines TNF-a and IL-1, IL-6is usually induced in the case of the body in acute reaction, is primarily be used to maintain cell homeostasis, and is also involved in the regulation of inflammation, cytokines and tissue inflammation reaction. As a pro-inflammatory cytokines, IL-6plays a very important role in viral infection. PRRSV infection is also capable of activating the expression of IL-6, but its specific molecular mechanisms are still unclear. Our study found that, PRRSV can induce high levels of IL-6, either on the mRNA or protein levels. We also found that TLR4/MyD88signaling cascade and its downstream signaling pathway of NF-κB, ERK1/2and p38MAPK are involved in PRRSV-induced IL-6. The siRNA interference and specific inhibitor treatment indicated that NLRP3inflammasome involved in PRRSV-induced IL-6production. We also found that ROS and K+efflux is also involved in PRRSV-induced IL-6secretion. In addition, we also analyzed the impact of IL-6on PRRSV proliferation. Treatment of purified IL-6protein on PAMs had no significant effect on the proliferation of PRRSV.3. The molecular mechanism of highly pathogenic PRRSV infection activate IL-8IL-8, or referred to CXCL8, is a CXC family pro-inflammatory chemokine. IL-8production mainly regulated by NF-κB, meanwhile NF-IL-6transcription binding sites is also involved in the regulation of the activity of the IL-8promoter. A variety of stimuli such as inflammatory response signal (IL-1(3and TNF-a generation), chemical and environmental stress (chemotherapy and hypoxia) and steroids can produce IL-8. As a pro-inflammatory chemokine IL-8plays a very important role in the inflammatory response summary. PRRSV is able to induce high level of IL-8in different organization. We used the PAMs, the target cells of PRRSV-infected pigs, to analyze the molecular mechanism of PRRSV infection activats IL-8. Our study found that, PRRSV can induce high levels of IL-8, either the mRNA or protein levels. We also found that TLR4/MyD88 signaling cascade and its downstream signaling pathway of NF-κB, ERK1/2and p38MAPK are involved in PRRSV-induced IL-8. The siRNA interference and specific inhibitor treatment indicated that NLRP3inflammasome involved in PRRSV-induced IL-8production. We also found that ROS and K+efflux is also involved in PRRSV-induced IL-8secretion. In addition, we also analyzed the impact of IL-8on PRRSV proliferation. Treatment of purified IL-8protein on PAMs had no significant effect on the proliferation of PRRSV.