Regulative Effects Of Gut Microbiome On The Lung Injury Of Influenza Virus Infected Mice

Pandemic and seasonal epidemic influenza brings a huge threat to the development of breeding industry and human health.It has brought many difficulties to the research and development of vaccines and antiviral drugs due to the frequent mutation of virus and emergence of drug-resistant strains.Therefore,it is naturally for people to explore new measures to control influenza from the host reaction.A/WSN/1933(WSN,H1N1)is isolated from humans in 1933,it has high replication capacity and pathogenicity on cells and mice after continuous laboratory habituated culture,it has become model virus which is widely used in the research of pathogenic mechanism of influenza virus and the interaction between virus and host.Influenza virus will replicate in the upper respiratory tract after infects host,which can activate the immune response and cause lung tissue damage,excessive immune response will be in charge for "cytokine storm",clinical cases showed that most patients who died from influenza often have a "cytokine storm" symptom.Influenza virus can also cause intestinal damage for dysbiosis of intestinal flora.Influenza virus was not detected in the intestines of infected humans and mice,but a large number of Th17 cells differentiated,the diversity and richness of intestinal flora decreased,and the relative abundance of Enterobacteria increased.When intestinal stool of influenza-infected mice was transplanted into healthy mice,the healthy mice also showed damaged intestine just like symptoms after infection,revealing the important role of intestinal flora in the process of intestinal injury after influenza infection.Therefore,scholars are trying to explore the regulation of intestinal flora on lung injury after influenza virus infection from a new perspective.This study used molecular biology technology,morphology technology and 16S rDNA sequencing technology to investigate the regulatory effect of intestinal flora on lung injury in influenza-infected mice.ExperimentⅠ Effects of advanced treatment with antibiotics and advanced treatment with prebiotics on the phenomenal characteristics of influenza virusinfected mice.In this study,the effects of WSN infection on the phenomenal characteristic of mice under different intestinal environment were investigated using PCR,HE staining,and reticular fiber staining techniques.The results showed that WSN virus can replicate in lung tissues but not in colon tissues.Advanced treatment with antibiotics and advanced treatment with prebiotics can alleviate the rapid weight loss of mice caused by WSN,and can relieve pulmonary congestion,alveolar structure damage and inflammatory cell infiltrate.The phenomenon of shortness of the colon,shedding of intestinal epithelial cells,and inflammatory cell infiltration can be also relieved.ExperimentⅡ Effects of advanced treatment with antibiotics and advanced treatment with prebiotics on intestinal flora of influenza-infected mice.This study used 16s rDNA technology to detect the effects of advanced treatment with antibiotics and advanced treatment with prebiotics on colonic flora of WSN-infected mice.The results showed that the normal dominant colon flora of mice were Bacteroides,Proteobacteria and Firmicutes;advanced treatment with antibiotics mice showed dysregulated colon flora,and the diversity of bacteria decreased significantly,the relative abundance of Proteobacteria was as high as 99%;the diversity of colonic flora decreased in mice advanced treatment with prebiotic,and the relative abundance of Bacleroides increased significantly;mice infected with WSN appeared dysbiosis of colonic flora,the relative abundance of TM7 increased,and the relative abundance of Firmicutes decreased;mice advanced treated with antibiotics infected WSN virus,dominant colon flora was still Proteobacteria.Mice advanced treated with prebiotics infected WSN virus compared with the pure WSN infected mice,the abundance of Bacteroidia still had a tendency to increase,the abundance of Paraprevotellaceae and Porphyromonadaceae increased significantly.ExperimentⅢ Regulators of colon and lung tissue injury in influenza virus infected mice advanced treatment with antibiotics and advanced treatment with prebiotics.This study used quantitative-PCR and western blot techniques to investigate the colon and lung injury regulators.The results showed that WSN infected mice advanced treated with antibiotics compared with the WSN infected mice displayed more Treg cells differentiation,fewer Th17 cells,more PPAR-y expression,less NFκB expression,and more expression of inflammatory cytokine such as IL-6、TNF-α and IFN-y,more expression of TGF-β.Advanced treatment with prebiotics mice can lead to increased differentiation of Treg cells,reduced Th17 cells,increased expression of PPAR-y,decreased expression of NFκB,decreased expression of inflammatory cytokines such as IL-6,TNF-α,and IFN-y,and increased expression of TGF-β in the colon.In summary,this study proved that advanced treatment with combination antibiotics and advanced treatment with prebiotic affected the colonic flora of mice.Most of colonic flora in mice were widely killed because of the advanced treatment with combination antibiotics,resulting in intestinal damage not happen because intestinal flora can’t be changed for influenza infection,which prevent colonic Treg cells from being reduced,thereby protecting the intestinal tract.Advanced treatment with prebiotics increased the relative abundance of Bacteroides in mice,which is beneficial to Treg cell differentiation and protects the intestinal tract.Advanced treatment with antibiotics and advanced treatment with prebiotics are beneficial for the differentiation and proliferation of Treg cells in the lung,thereby alleviating lung injury in mice after WSN virus infection.