Molecular Mechanism Of Glutamine In The Regulation Of Swine Intestinal Antiviral Innate Immunity

Innate immunity plays an important role in the homeostasis of human and animals.In recent years,research on vitamins,plant extracts,nutrients such as amino acid,etc.in regulating immunity has received increasing attention.Glutamine,as the most abundant amino acid in the body,has numerous physiological functions.However,whether glutamine regulates innate immunity and its underlying mechanisms are little known.In this study,we employed porcine intestinal cells(IPECJ2)as the research model,qRT-PCR showed that the expression of RIG-I(P <0.01)and IFNβ(P <0.01)were significantly up-regulated by glutamine.Antiviral experiments showed that virus replication and virus titer were attenuated by glutamine.Further exploring the molecular mechanism of glutamine antiviral,Western blot results showed that glutamine activated TBK1 and IRF3.In addition,the results showed that the expression of RIG-I and IFNβ were both down-regulated by experiments that were constructed IRF3 knockdown cell line and used TBK1 inhibitor,respectively.Since the important role of mTORC1 in the amino acid sensing signal pathway,we investigated whether mTORC1 involves in glutamine-activated antiviral signaling pathway.The phosphorylation of s6 k,the mTORC1 downstream protein,was detected by Western blot,and the expression of glutamine induced RIG-I and IFNβ were significantly reduced by mTORC1 inhibitor and mTORC1 knockdown cell line.These results demonstrated that mTORC1 was indeed involved in the glutamine-activated antiviral innate immune signaling pathway.To further explore the upstream and downstream relationship between TBK1/IRF3 and mTORC1 involved in the glutamine antiviral signaling pathway,we used mTORC1 inhibitor and mTORC1 knockdown cell line to detect IRF3 and TBK1 activation,respectively.It was found that the level of phosphorylation IRF3 and phosphorylation TBK1 were obviously reduced by inhibited or decreased the expression of mTORC1,indicated that activation weakened.The results proved that mTORC1 was located upstream of TBK1/IRF3 signaling pathway.Taken together,this study indicated that glutamine activates the antiviral innate immunity through mTORC1-mediated TBK1-IRF3 signaling pathway to up-regulate the expression of interferon genes.The results reveal that glutamine activates antiviral innate immunity and its mechanism,providing theoretical and experimental basis for nutritional regulation strategies of antiviral innate immunity.