Coelonin protects against PM2 .5 -induced macrophage damage via suppressing TLR4/NF-κB/COX-2 signaling pathway and NLRP3 inflammasome activation in vitro

One of the important monitoring indicators of the air pollution is atmospheric fine particulate matter (PM_2.5 ), which can induce lung inflammation after inhalation. Coelonin can alleviate PM_2.5 -induced macrophage damage through anti-inflammation. However, its molecular mechanism remains unclear. We hypothesized that macrophage damage may involve the release of inflammatory cytokines, activation of inflammatory pathways, and pyrosis induced by inflammasome. In this study, we evaluated the anti-inflammation activity of coelonin in PM_2.5 -induced macrophage and its mechanism of action. Nitric oxide (NO) and reactive oxygen species (ROS) production were measured by NO Assay kit and dichlorofluorescein-diacetate (DCFH-DA), and apoptosis were measured by Flow cytometry and TUNEL staining. The concentration of inflammatory cytokines production was measured with cytometric bead arrays and ELISA kits. The activation of NF-κB signaling pathway and NLRP3 inflammasome were measured by immunofluorescence, quantitative reverse transcription-polymerase chain reaction and western blot. As expected, coelonin pretreatment reduced NO production significantly as well as alleviated cell damage by decreasing ROS and apoptosis. It decreased generation of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in PM_2.5 -induced RAW264.7 and J774A.1 cells. Moreover, coelonin markedly inhibited upregulating the expression of toll-like receptor (TLR)4 and cyclo-oxygenase (COX)-2, blocked activation of p-nuclear factor-kappa B (NF-κB) signaling pathway, and suppressed expression of NLRP3 inflammasome, ASC, GSDMD, IL-18 and IL-1β. In conclusion, the results showed that coelonin could protect against PM_2.5 -induced macrophage damage via suppressing TLR4/NF-κB/COX-2 signaling pathway and NLRP3 inflammasome activation in vitro.

Coelonin, an Anti-Inflammation Active Component of Bletilla striata and Its Potential Mechanism

Ethanol extract of Bletilla striata has remarkable anti-inflammatory and anti-pulmonary fibrosis activities in the rat silicosis model. However, its active substances and molecular mechanism are still unclear. To uncover the active ingredients and potential molecular mechanism of the Bletilla striata extract, the lipopolysaccharide (LPS)-induced macrophage inflammation model and phospho antibody array were used. Coelonin, a dihydrophenanthrene compound was isolated and identified. It significantly inhibited LPS-induced interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expression at 2.5 μg/mL. The microarray data indicate that the phosphorylation levels of 32 proteins in the coelonin pre-treated group were significantly down-regulated. In particular, the phosphorylation levels of the key inflammatory regulators factor nuclear factor-kappa B (NF-κB) were significantly reduced, and the negative regulator phosphatase and tensin homologue on chromosome ten (PTEN) was reduced. Moreover, the phosphorylation level of cyclin dependent kinase inhibitor 1B (p27^Kip1), another downstream molecule regulated by PTEN was also reduced significantly. Western blot and confocal microscopy results confirmed that coelonin inhibited LPS-induced PTEN phosphorylation in a dose-dependent manner, then inhibited NF-κB activation and p27^Kip1 degradation by regulating the phosphatidylinositol-3-kinases/ v-akt murine thymoma viral oncogene homolog (PI3K/AKT) pathway negatively. However, PTEN inhibitor co-treatment analysis indicated that the inhibition of IL-1β, IL-6 and TNF-α expression by coelonin was independent of PTEN, whereas the inhibition of p27^Kip1 degradation resulted in cell-cycle arrest in the G1 phase, which was dependent on PTEN. The anti-inflammatory activity of coelonin in vivo, which is one of the main active ingredients of Bletilla striata, deserves further study.

[Comparison of contents of three active ingredients in Bletilla striata from different sources]

In order to understand the difference of contents of coelonin,batatasin Ⅲ and 3'-O-methylbatatasin Ⅲ in 60 different sources of Bletilla striata planted under the same conditions. UPLC method was used and the analysis was performed on a Waters ACQUITY UPLC BEH C18 column( 2. 1 mm×100 mm,1. 7 μm),eluted with acetonitril-0. 1% formic acid solution by gradient. The flow rate was 0. 208 m L·min-1,the detection wavelength was 270 nm,the column temperature was 35 ℃ and the injection volume was 4μL. Under the above chromatographic conditions,the three components can be separated well with good linearity in the range of 0. 156-5. 000 mg·L-1. The average contents of coelonin,batatasin Ⅲ and 3'-O-methylbatatasin Ⅲ were( 0. 116 ± 0. 071) %,( 0. 386 ±0. 185) % and( 0. 086±0. 034) %,respectively. After planting for two years under the same conditions,there was no significant difference in chemical composition among different sources and varieties,but the contents of the three components had some regional differences,which indicated that the western region was higher than the eastern region,while the contents of coelonin and batatasin Ⅲ in B.sinensis were slightly higher than those in B. striata. The chromatographic method above is simple,stable and reproducible,and can be used for quantitative analysis of three components. The content analysis of different sources of B. striata can provide reference for future B. striata breeding and quality control.