[Effects of simvastatin on lipopolysaccharide induced α-subunit epithelial sodium channel mRNA in rat lung alveolar type II epithelial cells].

Objective: To study the impact of simvastatin on α-subunit epithelial sodium channel (α-ENaC) mRNA expression in primary culture alveolar typeII (ATII) epithelial cell of rats induced by lipopolysaccharide (LPS) in vitro.

Methods: ATII of primary generation were isolated from adult Sprague-Dawley (SD) rats. The cells were randomly divided into five groups: blank control group, LPS injured group (final concentration of LPS 1 mg/L), simvastatin low and high concentration groups (final concentration of simvastatin 20 μmol/L, 30 μmol/L, respectively), solution control group. Then, after being intervened for 1, 12 and 24 hours, the level of human tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were monitored by enzyme-linked immunosorbent assay (ELISA), and α-ENaC mRNA expression was tested by reverse transcription-polymerase chain reaction (RT-PCR).

Results: After being intervened for 1, 12 and 24 hours, expressions of TNF-α and IL-1β in LPS injured group were obviously higher than those in blank control group. Expressions of TNF-α and IL-1β at 1, 12 and 24 hours in simvastatin low concentration group were significantly decreased compared with those in LPS injured group (TNF-α 1 hour: 1178.80±127.43 ng/L vs. 2336.00±170.04 ng/L, 12 hours: 1003.60±59.61 ng/L vs. 2479.80±210.41 ng/L, 24 hours: 695.80±25.24 ng/L vs. 1167.60±132.72 ng/L; IL-β 1 hour: 285.00±42.60 ng/L vs. 429.60±27.39 ng/L, 12 hours: 238.60±24.12 ng/L vs. 822.20±12.74 ng/L, 24 hours: 213.40±17.87 ng/L vs. 637.60±22.96 ng/L, all P<0.05). Expressions of TNF-α and IL-1β in high concentration group were decreased more obviously than those in low concentration group (TNF-α 1 hour: 965.60±24.45 ng/L vs. 1178.80±127.43 ng/L, 12 hours: 522.80±16.89 ng/L vs. 1003.60±59.61 ng/L, 24 hours: 252.40±17.64 ng/L vs. 695.80±25.24 ng/L; IL-1β 1 hour: 225.60±34.44 ng/L vs. 285.00±42.60 ng/L, 12 hours: 190.60±17.64 ng/L vs. 238.60±24.12 ng/L, 24 hours: 152.80±14.70 ng/L vs. 213.40±17.87 ng/L, all P<0.05), but increased compared with those in blank control group. After being intervened for 1 hour, no evident changes were observed in expression of α-ENaC mRNA in all groups. After being intervened for 12 hours and 24 hours, evident decrease in expression of α-ENaC mRNA (A value) was observed in LPS injured group compared with blank control group (12 hours: 0.211±0.021 vs. 0.496±0.027, 24 hours: 0.253±0.030 vs. 0.482±0.030, both P<0.05). Expressions of α-ENaC mRNA in simvastatin low concentration group evidently increased compared with those in LPS injured group (12 hours: 0.363±0.030 vs. 0.211±0.021, 24 hours: 0.309±0.024 vs. 0.253±0.030, both P<0.05). Expressions of α-ENaC mRNA in simvastatin high concentration group increased more obviously compared with those in low concentration group (12 hours: 0.413±0.034 vs. 0.363±0.030, 24 hours: 0.346±0.024 vs. 0.309±0.024, both P<0.05), but decreased compared with blank control group. No evident difference in expressions of all indexes in solution control group was observed compared with those in blank control group.

Conclusions: High dose simvastatin could improve α-ENaC mRNA expression in primary culture ATII epithelial cells of rats. This may act by modulation the level of TNF-α and IL-1β.