Role of p62/SQSTM1 in lipopolysaccharide (LPS)-induced mucus hypersecretion in bronchial epithelial cells.

AIMS: The aims of this study were to evaluate the effects of p62/SQSTM1 expression levels on lipopolysaccharide (LPS)-induced mucus secretion in BEAS-2B bronchial epithelial cells by measuring expression levels of the MUC5AC gene and the Mucin-5AC (MUC5AC) protein.

MATERIALS AND METHODS: Bronchial epithelial cells, BEAS-2B, were treated with LPS at different time points. Rapamycin, an autophagy agonist, was added to the BEAS-2B cells 30 min before LPS treatment. Lentivirus transfection was then used to knock down the expression of p62/SQSTM1 (Sequestosome 1) to investigate changes in the downstream signaling pathway. Western blotting and immunofluorescence were used to study the expression levels of MUC5AC, and reverse transcription-polymerase chain reaction (RT-PCR) was used to study the expression of MUC5AC mRNA.

KEY FINDINGS: LPS treatment of BEAS-2B cells inhibited autophagy, activated the nuclear factor kappa B (NF-κB) signaling pathway and increased the expression of MUC5AC. The autophagy agonist, rapamycin, activated autophagy, inhibited the NF-κB signaling pathway and decreased LPS-induced expression of MUC5AC. Knockdown of p62/SQSTM1 expression reduced activation of the NF-κB signaling pathway and reduced LPS-induced mucus secretion by BEAS-2B cells in vitro.

SIGNIFICANCE: In this in vitro study, which utilized BEAS-2B bronchial epithelial cells, p62/SQSTM1 was shown to have a role in LPS-induced mucus hypersecretion by activating the NF-κB signaling pathway.