Pulmonary Infection Induced By Mouse Oral Microflora Transfer Under Cold Stimulation

Objective To establish a mouse model of lung infection in cold environment,and to explore the new way of lung infection.To provide the basis for the followup human body research,so as to provide the theoretical basis for the prevention or reduction of lung infection rate by regulating the oral flora.Methods Thirty C57 / BL6 J clean mice(5 weeks)were randomly divided into three groups: group A(initial control group),group B(terminal control group)and group C(experimental group).All mice were first placed in a clean environment for three weeks.Three weeks later,venous blood was extracted from the orbital venous plexus of group A mice.After the blood was collected,the oral lavage fluid,trachea and lung tissues were removed from the cervical vertebra and killed.Blood routine examination was performed first.A part of lung tissues were stored in 4% polyformaldehyde for subsequent lung pathological specimens and the production of neutrophil immunohistochemistry.Oral lavage solution,trachea and a part of lung tissue were placed in a special sequencing tube and then frozen(-80℃)for subsequent bacterial population determination.Mice in group B were fed in a clean environment(22 ± 1℃,humidity 50 ± 5%)every day,mice in group C were fed in a clean environment(4℃,humidity 50 ± 5%)every day for 8 hours(9 a.m-5 p.m.),and then transferred to the same environment as mice in group B.After 30 days,the orbital vein of each mouse was taken from blood,oral lavage fluid,trachea and lung tissue.1.Detect the percentage of neutrophils in the blood,draw a chart after the statistical data to compare whether there is statistical difference in the percentage of neutrophils in the blood of each group of mice;2.Each mouse’s lung specimen stored in 4% paraformaldehyde is made for pathological specimen,at the same time,take pictures to observe the changes in the lungs of each group of mice,and at the same time,take a branch of neutrophil immunohistochemistry to observe under the microscope Observe whether there is statistical difference in the number of neutrophils in the lungs of each group of mice;3.The oral lavage solution,trachea and lung tissues of each mouse placed in the sequencing tube were sequenced with 16 Sr DNA high-throughput sequencing technology to determine the types of bacteria,observe the changes of bacteria in various parts of each group of mice,and find out the possible translocated pathogens by drawing comparison.Results 1.There was no significant difference in the percentage of neutrophils(P> 0.05)and the immunohistochemistry of neutrophils between group A and group B(P4 > 0.05).The percentage of neutrophils in group C was significantly higher than that in group A and B(P< 0.05),and the number of neutrophils in lung tissue of group C was significantly higher than that in group A and B(P < 0.05);2.There was no significant change in the lung pathology of group A and group B.There was obvious inflammatory cell infiltration in the lung pathology of group c mice,bleeding and hyperemia in the trachea,and disappearance of the alveolar structure.3.By comparing the results of the bacterial groups in different parts of the mice in each group,it was found that the proportion of Morganella in the oral cavity of the mice in group C was significantly higher than that of the mice in group A and B,and Morganella,which did not exist in the trachea and lung tissue of the mice in group C,appeared in the trachea and lung of the mice in group C,and became the dominant bacterial group.Conclusion The model of pulmonary infection in mice can be successfully established in cold environment,and it is found that the normal colonized bacteria in mouse mouth can move to the lungs of mice to cause pulmonary infection in cold environment.