Objective   To observe the effects of IL-4 on the expression of epithelial sodium channel (ENaC) β-subunit.    Methods   A549 cells were cultured with IL-4 at the concentration of 0

0.1

1 and 10 ng/ml for 12 h or with 1 ng/ml IL-4 for 3

6

12

24 and 48 h. Then β-ENaC protein and mRNA expressions were detected by Western blotting and RT-PCR respectively.    Results   IL-4 decreased the expression of β-ENaC in A549 cells in a time- and dose-dependent manner

via gene transformation. When A549 cells were cultured with IL-4 at the concentration of 1 ng/ml for 3

6

12

24 and 48 h

the expression of β-ENaC protein and mRNA were decreased in a time-dependent manner. Statistical analysis showed culture for 6 h had a significant difference compared with other time points (P0.05). When cells were cultured with different concentration of 0

0.1

1and 10 ng/ml for 12 h

the β-ENaC protein and mRNA showed a dose-dependent manner. Concentration at 0.1 ng/ml showed a significant difference among other concentration.    Conclusion   IL-4 was usually regarded as a anti-inflammatory factor and have a protection in acute lung injury/acute respiratory distress syndrome. But in this experiment it seems have a different role in the disease. IL-4 can decreases the expression of β-ENaC

and down-regulate the active alveolar fluid clearance

which may make the outcome worse.