Impaired autophagy flux by lncRNA NEAT1 is critical for inflammation factors production in human periodontal ligament stem cells with nicotine treatment.

BACKGROUND AND OBJECTIVES: Periodontitis is the top reason for tooth loss, and smoking significantly increases severe periodontitis risk. Defective autophagy has been reported to play a vital role in periodontitis. This study aimed to elucidate the relationship between autophagy and inflammation factors production in nicotine-treated periodontal ligament stem cells (PDLSCs) and the underlying mechanism. METHODS: In this study, transmission electron microscopy, immunofluorescence, and the mCherry-GFP-LC3 plasmid were used to study autophagy flux. The gene levels of inflammation factors and long noncoding RNA nuclear paraspeckle assembly transcript 1 (lncRNA NEAT1) were detected by quantitative real-time PCR (qRT-PCR). Western blot was performed to assess the protein levels of autophagic markers and alpha7 nicotinic acetylcholine receptor (alpha7nAChR). RESULTS: We found that nicotine impaired autophagosome-lysosome fusion and lysosome functions to block autophagy flux, contributing to inflammatory factors production in nicotine-treated PDLSCs. Moreover, nicotine upregulated NEAT1 by activating alpha7nAChR. NEAT1 decreased autophagy flux by downregulating syntaxin 17 (STX17). CONCLUSION: Our data indicate that NEAT1-decreased autophagy flux is pivotal for inflammation factors production in nicotine-treated PDLSCs.