Notch Signaling Regulates Inflammatory Response Induced By HP-PRRSV Infection

Highly pathogenic porcine reproductive and respiratory syndrome virus(HP-PRRSV)is an important pathogen,which causes severe reproductive problems in pigs and clinically causes respiratory diseases,which has brought a great loss to the pig industry in our country.In the lungs,HP-PRRSV causes lung disease by infecting porcine alveolar macrophages in pigs,the main manifestation is interstitial pneumonia.During HP-PRRSV infection the host produce certain enhanced and induced inflammatory responses and these induced responses are the underlying main cause of interstitial pneumonia.The underlying specific mechanism how this induced inflammatory response leads to progression of HP-PRRSV infection are less known and further research is required to gain more specific answers.Therefore,the goal of this research is to bring answer to some unrevealed mechanism related to HP-PRRSV infection.Studies have reported that Notch signaling pathway plays a necessary role in host development by affecting cell differentiation,proliferation and survival as well as the Notch signaling pathway also plays an important role in the immune system.According to a published data related to macrophage cell activation,TLR signaling pathway affects the expression of receptors and ligands in the Notch signaling pathway,which in turn regulates the secretion of inflammatory factors and the activation of macrophages.Additionally,NF-κB signaling pathway and MAPK signaling pathway are also involved in the regulation of receptors and ligands expression in the Notch signaling pathway.Previous studies also have shown that HP-PRRSV infection regulates the production of inflammatory factors through signaling pathways such as TLR4,NF-κB and MAPK.The reported data of RNA-seq and our preliminary experiment showed that virus infection up-regulates the expression of Jagged1.Therefore,these results prompted us to hypothesize that HP-PRRSV infection activates the Notch signaling pathway,which in turn regulates the inflammatory response through Notch signaling pathway.Therefore,the goal of this project is to gain insight knowledge related to the mechanism by which HP-PRRSV infection regulates inflammatory responses through the Notch signaling pathway and to fulfill this goal:First,we set up HP-PRRSV infection and used qPCR to examine the effect of HP-PRRSV infection on the Notch signaling pathway and we found that HP-PRRSV infection activates the Notch signaling pathway and up-regulate the expression levels of several ligands such as Jagged1,Dll3 and Dll4 and also up-regulate certain downstream target Hes1 and Hey1 molecules respectively.Further we have used DAPT treatment and silencing of nuclear regulatory molecule RBP-J by using RNA interference technology to analyze the expression level of inflammatory factors including both TNF-α and IL-1β,and we identify that Notch signaling pathway plays a crucial role in the inflammatory responses induced by HP-PRRSV infection.Then,we have used silencing of Jagged1 by using RNA interference technology to analyze the role of Jagged1 in the inflammatory responses induced by HP-PRRSV infection.Our results suggest that the Jagged1-Notch signaling pathway regulates the inflammatory responses induced by HP-PRRSV infection.Finally,we studied the expression mechanism of Jagged1 up-regulation by using inhibitors treatment and RNA interference technology and we found that Jagged1 is regulated by NF-κB,MAPK and Notch signaling pathways during HP-PRRSV infection.Taken together,our results showed that HP-PRRSV infection regulates the production of inflammatory factors and responses by activating the Notch signaling pathway.Further analysis answered us that HP-PRRSV infection can regulate the expression of ligand Jagged1 by activating NF-κB,MAPK and Notch signaling pathway.Therefore Jagged1-Notch signaling pathway plays an important role in the HP-PRRSV-induced inflammatory response.Moreover our results not only clarify the role of Notch signaling pathway in HP-PRRSV infection,but also lay the foundation for further studies related to the mechanism of HP-PRRSV infection that how it induces inflammatory response.