Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 May 20;26(3):119-128.
doi: 10.1080/19768354.2022.2077438. eCollection 2022.

Cynarin attenuates LPS-induced endothelial inflammation via upregulation of the negative regulator MKP-3

Affiliations

Cynarin attenuates LPS-induced endothelial inflammation via upregulation of the negative regulator MKP-3

Da Bin Kim et al. Anim Cells Syst (Seoul). .

Abstract

Clinical observations have revealed that non-resolving low-grade inflammation is linked to the pathogenesis of chronic inflammatory diseases, for example arthritis, atherosclerosis, Alzheimer's disease, diabetes, and chronic kidney disease. Interestingly, low levels of circulating lipopolysaccharides (LPS) derived from the outer membrane of gram-negative bacteria appear to be one of the primary causes of persistent low-grade inflammation. The inner surface of the blood vessels is lined with endothelial cells; therefore, even low levels of circulating LPS can directly activate these cells and elicit specific cellular responses, such as an increase in the expression levels of cell adhesion molecules and proinflammatory mediators. In endothelial cells, LPS exposure results in an inflammatory response through activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases. Cynarin, a phytochemical found in artichokes, has several pharmacological properties against endothelial inflammation. In the present study, we discovered that cynarin suppressed the LPS-induced increase in the expression levels of vascular cell adhesion molecule-1 and proinflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and interleukin-1β in EA.hy926 cells. Further, cynarin inhibited the activation of p38 and NF-κB pathways by inducing the negative regulator mitogen-activated protein kinase phosphatase 3 (MKP-3) in LPS-stimulated EA.hy926 cells. In conclusion, cynarin alleviates inflammation by upregulating MKP-3, a negative regulator of p38 and NF-κB, and it may be a therapeutic option for treating endothelial inflammation-related diseases.

Keywords: Cynarin; MKP-3; endothelial inflammation; endotoxin.

PubMed Disclaimer

Conflict of interest statement

No potential conflict of interest was reported by the author(s).

Figures

Figure 1.
Figure 1.
Chemical structure and cytotoxicity induced by cynarin. (A) Chemical structure of cynarin. (B) Cell viability of EA.hy926 cells after treatment with different cynarin concentrations as determined using the cell counting kit-8 assay. The results are presented as the mean ± standard error of the mean (SEM) of three independent experiments. **P < 0.01, compared to the vehicle control group.
Figure 2.
Figure 2.
Effects of cynarin on lipopolysaccharide (LPS)-induced proinflammatory molecule expression in EA.hy926 cells. EA.hy926 cells were treated with cynarin for 4 h before adding LPS (1 μg/mL) for another 24 h. (A + B) VCAM-1 expression level was measured via western blotting. β-actin was considered as a loading control. Data are presented as the mean ± SEM (n = 3). **P < 0.01, compared to the LPS-only group. (C–E) The mRNA expression levels of inflammatory genes [monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor (TNF-α), and interleukin (IL)−1β] as detected via real-time PCR. 18S rRNA was used as an internal control. Data are presented as the mean ± SEM (n = 3). Asterisks indicate significant differences (P <   0.01).
Figure 3.
Figure 3.
Effects of cynarin on LPS-stimulated phosphorylation of p38 and NF-κB p65 in EA.hy926 cells. (A + B) The cells were treated with cynarin for 1 h before adding LPS (1 μg/mL) for another 30 min. Relative protein expressions were analyzed via western blotting. The data show the mean ± SEM of three independent experiments. *P < 0.05 and **P < 0.01, compared to the vehicle control group. ##P < 0.01, compared to the LPS-only group.
Figure 4.
Figure 4.
Effects of cynarin on nuclear translocation of NF-κB p65 in LPS-stimulated EA.hy926 cells. The cells were treated with cynarin (5 µM) for 1 h before adding LPS (1 μg/mL) for another 30 min. (A) Representative immunofluorescence staining images showing NF-κB p65 (green) and the nucleus (blue). Scale bars: 50 µm. (B) Quantitation of NF-κB p65 nuclear translocation in the indicated groups. Results are shown as the mean ± SEM (n = 3). Asterisks indicate significant differences (P <   0.01).
Figure 5.
Figure 5.
Effects of cynarin on MKP-3 expression in EA.hy926 cells. (A + B) The cells were treated with cynarin (5 µM) for 1 h before adding LPS (1 μg/mL) for another 30 min. MKP-3 expression was measured via western blotting analysis. β-actin was considered as an internal control. Data are presented as the mean ± SEM (n = 3). **P < 0.01, compared to the LPS-only group. #P < 0.05 and ##P < 0.01, compared to the vehicle control group. The cells were treated with cynarin (5 µM) for 1, 4, 8, or 24 h. Protein expression of MKP-3 was determined using western blotting analysis (C + D). MKP-3 mRNA expression was analyzed using real-time PCR (E). The data show the mean ± SEM of three independent experiments. *P < 0.05 and **P < 0.01, compared to the vehicle control group.
Figure 6.
Figure 6.
Diagram of the possible mechanisms of cynarin-induced effects in LPS-stimulated EA.hy926 cells. Cynarin may function as an MKP-3 inducer to suppress LPS-stimulated inflammation by inhibiting p38 and NF-κB activation.

References

    1. Bierhaus A, Chen J, Liliensiek B, Nawroth PP.. 2000. LPS and cytokine-activated endothelium. Semin Thromb Hemost. 26(5):571–588. - PubMed
    1. Buss H, Handschick K, Jurrmann N, Pekkonen P, Beuerlein K, Muller H, Wait R, Saklatvala J, Ojala PM, Schmitz ML, et al. . 2012. Cyclin-dependent kinase 6 phosphorylates NF-κB P65 at serine 536 and contributes to the regulation of inflammatory gene expression. PLoS One. 7(12):e51847. - PMC - PubMed
    1. Chan DW, Liu VW, Tsao GS, Yao KM, Furukawa T, Chan KK, Ngan HY.. 2008. Loss of MKP3 mediated by oxidative stress enhances tumorigenicity and chemoresistance of ovarian cancer cells. Carcinogenesis. 29(9):1742–1750. - PubMed
    1. Chen X, Xiu M, Xing J, Yu S, Min D, Guo F.. 2017. Lanthanum chloride inhibits LPS mediated expressions of pro-inflammatory cytokines and adhesion molecules in HUVECs: Involvement of NF-κB-Jmjd3 signaling. Cell Physiol Biochem. 42(5):1713–1724. - PubMed
    1. Chen Y, Chen X, Luo G, Zhang X, Lu F, Qiao L, He W, Li G, Zhang Y.. 2018. Discovery of potential inhibitors of squalene synthase from traditional Chinese medicine based on virtual screening and in vitro evaluation of lipid-lowering effect. Molecules. 23(5):1040. - PMC - PubMed