The Effect Of Early-life Environmental Microbial Exposure On Mice Intestinal Microbiota And Asthma Development

Objective: The aim of this study was to investigate the effect of early life different microbial exposures on mice intestinal microflora colonization and airway inflammation of asthma,for better understanding of window of opportunity when early life intestinal microflora colonization influences asthma development and getting access to preventing and treating asthma by establishing a model of asthma coupled to early life different microbial exposures.Method: 24 adult SPF BALB / c mice 24(male: 8,female:16),male and female 2:1 caged,after conception,parents and offsprings are divided into three periods(fetal period,lactation and childhood),and reared in different environments(16 female mice offsprings every group).Group A: Offsprings were kept in SPF laboratory animal environmental facilities during fetal period,lactation and childhood;group B: Offsprings were kept in SPF environment during fetal period,lactation and kept in the general environment during childhood;group C: Offsprings were kept in SPF environment during fetal period,and kept in the general environment during lactation and childhood;group D: Offsprings were kept in general environment during fetal period,lactation and childhood;Feces samples were collected at 3 week and 5 week,followed by high throughput analysis for gut microbiota.Mice were sensitized with ovalbumin(OVA)beginning at day 43 after birth,Then,four groups were divided into asthma(group AI,BI,CI,DI)and control goup(group AII,BII,CII,DII);And pathological changes of lung tissue were observed by HE staining;at the same time,transcription-polymerase chain reaction(RT-PCR)was used to detect GATA-3 m RNA and T-bet m RNA and Enzyme Linked Immunosorbent Assay(ELISA)were used to detect Ig E in the mice lung tissue.Result: 1.High throughput analysis for gut microbiota Our analysis revealed a strong negative correlation between the environmental cleanliness and intestinal microbial diversity in the gut(P<0.05).More environmental cleanliness got access to less gut microbiota.It suggested that mice housed in conventional environment showed a dominance of Firmicutes and Lactobacillus.Furthermore,there were significant differences in Akkermansia between different environmental cleanliness whatever in mice at three week or five week.2.Both group A and B showed a higher level of airway inflammation than group C and D(P <0.001)while Group AI and BI showed on significant difference by HE staining(P>0.05);Group AI and BI showed no difference(P>0.05)while the level of airway inflammation in group CI show a small increase compared with group DI(P<0.05);3.Compared with group A and B,the level of Ig E in the pulmonary of group C and D showed a significant decrease(P<0.05);Group A and B showed no difference(P>0.05)while the level of Ig E in group C show a small increase compared with group DI(P<0.05);4.The levels of GATA-3 m RNA in group AI and BI were significantly higher in lung than group CI and DI(P<0.001);Group AI and BI showed no difference(P>0.05)while the level of GATA-3 m RNA in group CI showed a small increase in comparison with group DI(P<0.05);5.The levels of T-bet m RNA in group AI and BI were significantly lower in lung than group CI and DI(P<0.001);Group A and B showed no difference(P>0.05)while the level of T-bet m RNA in group CI showed a small decrease in comparison with group DI(P<0.05);Conclusion: Early life exposure to different living environment has an obvious impact on the early life colonization of mice intestinal microflora and the more diverse early life intestinal living environment microbiota is,the more diverse microflora is,which will relieve asthma development.Furthermore,the window of opportunity in which perturbations of the intestine microbiota have effects on asthma development seems to be related to fetal period and lactation.