The Characterization Of Sickness Conditions And RNA Sequencing Of Lung In Animal Model With Inflammatory Response At Early Stage

Objective:The nature character of sepsis is severe inflammatory response which is incontrollable by the host.Lung is one of the most vulnerable organs and the outcome of the sepsis-induced acute lung injury is poor.However,the characterizations of severe inflammatory response at the early stage has been poorly studied.The present study aimed to explore the characterizations of sickness conditions and RNA sequencing of lung in animal models with different levels of inflammation.Materials and methods:Male Wistar rats were used in our study.Control group received intraperitoneal injection of saline(2ml).Mild and severe inflammatory response groups received Lipopolysaccharide(LPS)(5mg/kg,10mg/kg)through the same way.1.Three groups completed the behavioral tests including the temperature test,sweet mild intake test and open-field test at 1 hour(h),2h,3h and 4h after injection.2.The arterial blood and organs including lung,liver,heart,kidney,spleen and brain from three groups were collected at above four time points,which were used to complete the laboratory tests including the routine blood tests,blood biochemical tests,blood gas analysis,cytokine and hormones tests and HE stain.3.At those four time points,lung tissues were collected and used to complete the RNA sequencing.Results:1.The temperature of rats in mild and severe inflammation groups decreased at 1h,2h and 3h after injection.The food intake and locomotion in those two groups were also reduced at four time points.However,the models of sickness behavior in those two inflammation groups presented no significant difference.2.The mild and severe inflammation groups presented different manifestations.Specifically,the concentrations of IL-1β,CRP in severe group were much higher than those in mild group at 3h and the concentration of PCT in severe group was significant higher than that in mild group at 3h and 4h.3.At the early stage of the inflammation(at the 2h),the differentially expressed genes of the lung in mild and severe groups were enriched in several signaling pathways including TNF signaling pathway,IL-17 signaling pathway and NF-κB signaling pathway.Compared with mild group,the differentially expressed genes in severe group were involved in the biological processes of response to hypoxia and immune regulation.The most significant genes in above processes were Eln,Trafd1,Aim2,P2rx7 and IL-12α.Conclusion:1.At the early stage of the inflammation,the rats in mild and severe inflammation groups would present sickness behaviors which might be helpful for the host to fight against the pathogens.However,the level of the inflammation didn’t have impact on the model of the sickness behavior.2.IL-1β might be the initial element in the development of the systematic inflammation and sepsis.PCT and CRP would be used to identify the severe inflammation at the early stage.3.At the 2h of the inflammation,the differentially expressed genes of the lung in mild and severe groups were enriched in several signaling pathways which were associated with regulation of the immune function.These signaling pathways were involved in the development of the inflammation.What’s more,the injury of lung elastin caused by the up-regulation gene of Eln and the imbalance of the immune system of the host caused by the downregulation genes of Trafdl,Aim2,P2rx7 and IL-12α might be the reason that the severe inflammatory response developed into the sepsis and sepsis-induced acute lung injury.