Expression Of MiRNA-155 And IFN-γ In Lung Injury Model Of Neonatal Rats With Acute Respiratory Distress Syndrome

Objective Neonatal acute respiratory distress syndrome is a kind of neonatal respiratory critical disease with high morbidity and mortality,which is a great threat to the prognosis and quality of life of newborns.It is common in full-term and late premature infants.Therefore,in this study,the lung injury model of acute respiratory distress syndrome in neonatal rats was established by intraperitoneal injection of lipopolysaccharide.The pathological changes of lung tissue and the expression of mi RNA-155 and IFN-γ in lung tissue were detected,and the role of mi RNA-155 and IFN-γ in the pathogenesis of NARDS was analyzed.Thus,it is helpful to explore the pathological mechanism and treatment strategy of NARDS.Lung tissue samples were taken at 3h,6h,12 h and 24 h after administration.The surface changes of lung tissue were observed with naked eyes and the W/D ratio was measured.Then the lung tissue was stained by chemical staining(HE staining).The pathological changes of lung tissue were observed under light microscope,and the pathological score of lung injury was calculated.Finally,the expression of mi RNA-155 and IFN-γ in lung tissue was measured by q RT-PCR technique and ELISA technique.Methods Eighty newborn SD rats were randomly divided into experimental group(LPS group)and control group(isotonic Na CL group)on the 7th day after birth,with40 rats in each group.LPS solution was injected into the abdominal cavity of neonatal SD rats in the experimental group with 4mg/kg(LPS 1mg dissolved in 1m L isotonic Na CL solution)to establish the NARDS animal model,and isotonic Na CL solution was injected into the abdominal cavity of neonatal SD rats in the control group with4 m L/kg to set up a healthy control group.Results 1.After the beginning of the experiment,the mental reaction state of the rats in the control group was observed,which showed that their breathing was smooth,the skin and limbs were ruddy,the degree of independent activity was good,and the overall performance was good,while the rats in the experimental group showed mental malaise with the passage of time,sometimes irritability,shortness of breath and apnea alternately,hypothermia,purple lips and limbs,cold skin,white skin,and head tremor.2.According to the general observation of lung tissue,the surface of lung tissue of rats in the control group was flesh pink,soft,smooth and elastic,and no congestion and edema were found.with the passage of time,the lung tissue of rats in the experimental group gradually appeared hyperemia and edema,and the degree is getting worse.3.With the extension of time,the W/D ratio of lung tissue of neonatal rats in the experimental group increased gradually,reached the peak at 12 h,then began to decrease gradually,and was close to that of the control group at 24 h.The results of each phase experiment and control group showed that there was no significant difference in lung tissue W/D ratio between 3h and 24h(P>0.05),but there was significant difference in lung tissue W/D ratio between 6h and 12h(P<0.05).4.The pathological structure of lung tissue was observed under light microscope.the structure of alveolar cavity in the control group was clear,complete,uniform in size and no exudation,but with the extension of time,red and white blood cell infiltration could be seen in the alveolar cavity and interstitial of the experimental group.the continuity of vascular endothelial cells was destroyed and shedding,the structure of alveolar cavity was disordered and contained exudate,and part of the alveolar cavity was filled with exudate and dilated.5.Compared with the control group,the pathological score of lung tissue in the experimental group was significantly different from that in the control group(P<0.05).At the same time,there were significant differences in the pathological scores of lung tissue between the experimental group and the control group(P<0.05).6.The expression of mi RNA-155 and IFN-γ in the lung tissue of the experimental group was significantly higher than that of the control group(P<0 05),and there was significant difference between the experimental group and the control group(P<0 05).At the same time,it was found that the expression of mi RNA-155 and IFN-γ in the lung tissue of the experimental group increased gradually with the extension of time,showing an upward trend.7.Statistical Pearson correlation analysis showed that there was a positive linear correlation between the expression of mi RNA-155 and IFN-γ in the lung tissue of neonatal rats in the experimental group(r=0.962,P<0.05),but there was no significant linear correlation between the expression of mi RNA-155 and IFN-γ in the control group(r=0.177,P>0.05).Conclusion 1.The animal model of NARDS was successfully established by intraperitoneal injection of 4mg/kg LPS in neonatal rats.2.When NARDS occurs in neonatal rats,the expression of mi RNA-155 in lung tissue is significantly increased,and the expression of mi RNA-155 is sequential.mi RNA-155 is expected to be an early biomarker for the diagnosis of NARDS.3.During the development of NARDS in neonatal rats,the expression of IFN-γ in lung tissue increased significantly,and there was a positive linear relationship between the expression of IFN-γ and mi RNA-155.It is speculated that mi RNA-155 may mediate the expression of IFN-γ through some signal pathway or inflammatory response,participate in the molecular regulation and pathogenesis of the disease,and promote the progression of NARDS.