Abstract:
Objective： To investigate the expression of β-Catenin，transforming growth factor beta 1(TGF-beta 1), Clara cell secretory protein 16 (cc16), and surface antigen 6 of alveolar epithelial cell Ⅱ(KL-6) in bronchoalveolar lavage fluid(BALF) of children with bronchial pulmonary dysplasia(BPD) and its significance.
Method : Of 70 cases of premature infants with mechanical ventilation, 40 cases diagnosed with BPD were included in observation group, 30 cases of non-BPD patients were as control group. Detect the levels of β-Catenin, TGF-beta 1, cc16 and KL-6 in BALF of two groups of children respectively after 1, 24, 48 and 72 h of mechanical ventilation using enzyme-linked immunosorbent assay method. 
Result : Average gestational age and birth body mass of observation group were significantly lower than those of the control group, the difference being statistically significant (P＜0.05).The time of mechanical ventilation and oxygen therapy were significantly longer than the control group, the difference being statistically significant(P＜0.01). With longer duration of mechanical ventilation, the levels of cc16 of observation group showed a downward trend, and β-Catenin, TGF-beta 1 and KL-6 levels showed an upward trend, and the level difference of each index in time point of 48 and 72 h was statistically significant compared with that of 1 h(P＜0.01). The difference of the level of TGF-beta 1 and cc16 of control group at time point 1 h and 72 h of mechanical ventilation was statistically significant (P＜0.01), but the differences of level of beta protein and KL-6 at various time points had no statistical significance (P>0.05). Index levels of β-Catenin and TGF-beta 1 of observation group with mechanical ventilation at each time point were significantly higher than control group in the corresponding time point, but cc16 was significantly lower than the control group, the difference being statistically significant (P＜0.05), while the KL-6 of observation group was higher than the control group in the corresponding time point of 48 and 72 h, the difference being statistically significant(P＜0.05).There was no statistically significant difference at other time points(P>0.05). Comparing each time point,β-catenin, TGF-β1 and KL-6 levels in the moderate and severe BPD group were significantly higher than mild group (P＜0.05), but cc16 level was significantly lower than mild group (P＜0.05). Multiple stepwise regression analysis results showed that the longer duration of mechanical ventilation time and oxygen and the low cc16 levels are a risk factor for the occurrence of BPD(P＜0.01).
Conclusion： The occurrence of premature BPD is closely related to longer duration of mechanical ventilation and oxygen and low cc16 levels. Monitoring the level of β-Catenin, TGF-beta 1 and cc16 of BALF of premature infants in initial mechanical ventilation can provide the basis for predicting the occurrence of premature BPD and its classification.

Key words: bronchial pulmonary dysplasia, β-Catenin, transforming growth factor beta 1, Clara cell secretory protein 16, Krebs Von den Lungen-6, infant, newborn