Correlation Between Changes Of Lower Respiratory Tract Flora And Lung Injury In Rats After Mechanical Ventilation

BackgroundWith the development of medical careers,ventilator mechanical ventilation technology has been widely used in clinical practice.Mechanical ventilation ensures normal breathing of patients,but mechanical ventilation may also cause lung damage or aggravate existing lung damage.In addition,the process of ventilator therapy is accompanied by an associated inflammatory response.Current research indicates that microbial communities exist in the lungs and that lung flora is altered in respiratory diseases,including asthma and chronic obstructive pulmonary disease.There have been some preliminary explorations of the effects of mechanical ventilation changes in respiratory flora,but the correlation between mechanical ventilation lung injury and respiratory flora in rats remains unclear.Therefore,we designed the present study.ObjectiveTo investigate the species composition analysis and functional analysis of lung injury and lower airway flora in rats under mechanical ventilation with tracheal intubation.MethodsTwenty-eight adult male Sprague-Dawley(SD)rats weighing 280±50 g were selected and randomly divided into seven groups(n=4):control group(group C),autonomic breathing 1 hour group(group SV1),autonomic breathing 3 hours group(group SV3),autonomic breathing 6 hours group(group SV6),mechanical ventilation 1 hour group(group MV1),mechanical ventilation 3 hours group(group MV3),and mechanical ventilation 6 hours group(group MV6).Group C has executed directly after anesthesia tracheal intubation.Rats in the experimental groups were performed at the corresponding time points,lung tissues were calculated the wet-to-dry weight ratio(W/D),and the lung histopathological results were observed under electron microscope after HE was staining and 16S rDNA sequencing was performed.Lung injury and changes in the microbial community of the lower respiratory tract were compared in rats under mechanical ventilation with tracheal intubation.ResultsThe total number of OTUs of respiratory flora in rats in the MV6 and SV6 groups was greater than that in the C group.The β diversity and a diversity of respiratory flora in the seven groups were statistically significant(p<0.05).Species classification analysis revealed that the main dominant phyla of the rat respiratory flora in the seven groups were Proteobacteria,Firmicutes,Bacteroidetes,and Cyanobacteria.Acinetobacter_radioresistens was significantly elevated in the C group,Megaonas was elevated considerably in the MV6 group,and Parvibacter was elevated substantially in the SV6 group and upgraded significantly be necessary for differentiating ventilator-associated acute lung injury from associated pneumonia.In addition,functional prediction analysis yielded that Anaerobic bacteria gene,Biofilm formation gene,and Gram-negative bacteria gene were altered during mechanical ventilation with tracheal intubation.ConclusionTracheal intubation and mechanical ventilation may induce acute lung injury and dysbiosis of lower respiratory tract flora in rats.