Notoginsenoside R1 up-regulates microRNA-132 to protect human lung fibroblast MRC-5 cells from lipopolysaccharide-caused injury.

Pneumonia is a common lung disease in children with high fatality rate. Notoginsenoside R1 (NGR1) is the main active component extracted from the roots of Panax notoginseng (Burk.) F.H. Chen (Araliaceae). Here, we carefully explored the potential anti-inflammatory and protective effects of NGR1 on lipopolysaccharide (LPS)-induced lung fibroblast MRC-5 cell injury. Viability and apoptosis of MRC-5 cells after different treatment or transfection were respectively assessed using CCK-8 assay and Annexin V-FITC/PI staining. The expression levels of microRNA-132 (miR-132), IL-1β, IL-6 and TNF-α in MRC-5 cells were measured using qRT-PCR. MicroRNA transfection was conducted to reduce the expression level of miR-132. Western blotting was used to analyze the protein expression levels of key factors involving in cell proliferation, apoptosis, NF-κB pathway and JNK pathway. LPS treatment caused MRC-5 cell proliferation inhibition, apoptosis and over-production of inflammatory cytokines. NGR1 treatment had no significant effects on MRC-5 cell proliferation, apoptosis and production of inflammatory cytokines, but protected MRC-5 cells from LPS-caused cell proliferation inhibition, apoptosis and over-production of inflammatory cytokines. In addition, NGR1 increased the expression level of miR-132 in MRC-5 cells. Knockdown of miR-132 reversed the protective effects of NGR1 on LPS-treated MRC-5 cells. Furthermore, NGR1 attenuated LPS-activated NF-κB and JNK pathways in MRC-5 cells via up-regulation of miR-132. This research confirmed the protective roles of NGR1 in lung fibroblast cell inflammatory injury. NGR1 protected MRC-5 cells from LPS-caused inflammatory injury through up-regulating miR-132 and then inactivating NF-κB and JNK pathways.