The Effect Of Neonatal Maternal Separation On Airway Inflammation In Adult Asthma Mice

[Objective]The study is to investigate the effect and the mechanism of neonatal maternal separation on airway inflammation of asthma by establishing a model of asthma coupled to neonatal maternal separation(NMS).This study sets up the experimental foundation for a better understanding of the relationship between the clinical early life stress events and asthma;provides a reliable basis for promoting family holistic nursing;and also provides a new strategy for the prevention and treatment of asthma exacerbation by stress.[Methods]Balb/c neonatal male mice were assigned to NMS and non-NMS groups.Neonatal mice were born as PNDO and mice from NMS group separated from their mothers for 3 hours daily,at the same time each day from postnatal day(PND)2 to PND14 while the others were not separated.The number of fecal pellets was counted on PND21,28,35 and 42(one week,two weeks,three weeks after weaning)to analyze the microbiota and short-chain fatty acids(SCFAs)by denaturing gradient gel electrophoresis(DGGE)technique and liquid chromatography.Mice were sensitized with ovalbumin(OVA)on PND43.Then,non-NMS group was divided into control(group A)and asthma groups(group B)while NMS group was assigned to neonatal maternal separation+asthma(group C)and neonatal maternal separation+asthma+SCFAs groups(group D).The count of the inflammatory cells and eosinophils(EOS)were assessed by bronchoalveolar lavage fluid(BALF).And pathological changes of lung tissue were observed by HE staining;at the same time,Enzyme Linked Immunosorbent Assay(ELISA)was used to detect the number of cytokines in the mice lung tissue(IL-13,IL-25,IL-33).Last,protein expression of Occludin and E-cadherin in airway epithelial of mice lung was examined by Western blot.[Results]1.The change of the microbiota and SCFAs after NMS:The number of S’,diversity index H’ and dominance index D\of NMS group were lower than those of non-NMS group at the first,the second and the third week after weaning(P<0.05),and these indexes were not statistically significant on the day of weaning.The content of propionic acid and acetic acid was different from two groups but was not statistically significant,while the content of butyric acid was increased significantly compared with NMS group(P<0.01).2.The change of the airway inflammation in adult asthma mice after NMS:The number of inflammatory cells and EOS in group C was higher than these in group A,B and D.Group C showed that more EOS soaked in the pulmonary interstitial by HE staining while the pathological changes in group B and group D were alleviated;but group A had no change.The levels of cytokines in group C were significantly higher in lung.3.The possibly mechanism of airway inflammation in asthma induced by NMS:Group C showed that bronchial epithelium goblet cells increased slightly and a small amount of visceral secretions while these changes reduced in group B and group D.But group A had no changes.Western blot showed that both B,C and D groups’ protein levels of Occludin and E-cadherin were depressed in lung compared with group A.The level of protein in group C was lower than that of group B,but group D was higher than that of group C,and the difference was statistically significant.[Conclusions]The neonatal maternal separation can effect the diversity of intestinal microflora and the content of butyric acid.And male mice suffered NMS can also result in the phenomenon exacerbating the inflammation of adult asthma,and the possible mechanism of this phenomenon is that the changes in the diversity of intestinal microflora in the early life cause a decrease in the content of short chain fatty acids,which further damage the airway epithelial barrier and eventually aggravate asthma.