Lnc RNA MALAT 1 regulates inflammatory cytokine production in lipopolysaccharide‐stimulated human gingival fibroblasts through sponging miR‐20a and activating TLR 4 pathway

Background and Objective It has been reported that long non‐coding RNA s (lnc RNA s), such as metastasis‐associated lung adenocarcinoma transcript 1 ( MALAT 1), act as key regulators of the development of inflammatory diseases. However, it is unclear whether MALAT 1 regulates the function of human gingival fibroblasts ( HGF s) in periodontitis. This study is to explore the role of MALAT 1 on inflammatory cytokine production of HGF s. Material and Methods Primary HGF s were harvested from human gingiva. MALAT 1 was detected in inflammatory and healthy gingival tissues via quantitative real‐time PCR ( qRT ‐ PCR ). Bioinformatics analysis, dual‐luciferase reporter assay, and RNA ‐binding protein immunoprecipitation ( RIP ) were used to detect the relationship among MALAT 1, toll‐like receptor 4 ( TLR 4), and micro RNA (miR) ‐20a. After transfection LPS ‐treated HGF s with MALAT 1 si RNA (si‐ MALAT 1), miR‐20a mimic or overexpression MALAT 1 plasmid (sno‐ MALAT 1), the levels of MALAT 1, miR‐20a, TLR 4, IL ‐6 and IL ‐8 were analyzed by qRT ‐ PCR , enzyme‐linked immunosorbent assay, or western blot assay. Results MALAT 1 up‐regulated in inflammatory gingival tissues of chronic periodontitis. MiR‐20a was bound with MALAT 1 and TLR 4 3′‐ UTR in RNA ‐protein complex with Ago2, respectively. Moreover, MALAT 1, TLR 4, IL ‐6, and IL ‐8 increased while miR‐20a decreased after 1 μg/mL Porphyromonas gingivalis lipopolysaccharide ( LPS ) or Escherichia coli LPS stimulation. MiR‐20a inhibited the expression of proinflammatory cytokines via binding to TLR 4 3′‐ UTR . In addition, MALAT 1 increased TLR 4 level and the secretion of inflammatory cytokines. Conclusion MALAT 1 enhances inflammatory cytokine production through sponging miR‐20a and releasing TLR 4, indicating a regulatory role of MALAT 1 in periodontal inflammation.