Tmem16a Protein Attenuates Lipopolysaccharide-Mediated Inflammatory Response Of Human Lung Epithelial Cell Line A549

Objective: To observe the expression of endogenous TMEM16A in rat alveolar type II epithelial cells (AT-II) and A549, and study the effect of TMEM16A on lipopolysaccharide (LPS)-induced proinflammatory cytokine secretion. Methods: Rat AT-II cells were isolated and TMEM16A protein expression in rat AT-II cells was measured by Western blot. TMEM16A mRNA and protein expressions in A549 were measured by real-time quantitative polymerase chain reaction (PCR) and Western blot, respectively. TMEM16A gene was transfected into A549 using Lipofectamine 2000. Transfected cells were selected in the presence of G418 to create a stable TMEM16A overexpression A549 cell line. The expression of TMEM16A in A549 was knocked down by lentiviral vector-mediated RNA interference. TNF-alpha and IL-8 levels were determined by enzyme-linked immunosorbent assay (ELISA). A dual-luciferase reporter assay system was used to measure the transcriptional activity of NF-kappa B. Results: (1) Endogenous TMEM16A was expressed in rat AT-II and A549. (2) TMEM16A expression in A549 significantly increased at 24 hours and 36 hours, and then decreased at 48 hours after LPS treatment. (3) TMEM16A mRNA and protein expressions were increased in the stable TMEM16A overexpression A549 cell line. (4) TMEM16A overexpression decreased the LPS-induced TNF-alpha and IL-8 secretions. (5) TMEM16A mRNA and protein expressions were knocked down in TMEM16A-siRNA lentivirus transfected A549. (6) TMEM16A knockdown increased the LPS-induced TNF-alpha and IL-8 secretions. (7) TMEM16A overexpression inhibited LPS-induced NF-kappa B activation. Conclusions: TMEM16A is expressed in AT-II. TMEM16A in A549 inhibits LPS-induced NF-kappa B activation and decreases proinflammatory cytokines release, protecting A549 from acute LPS-mediated damage.