Cardiovascular pharmacology
Oridonin inhibits vascular inflammation by blocking NF-κB and MAPK activation

https://doi.org/10.1016/j.ejphar.2018.02.044Get rights and content

Abstract

Oridonin, an active diterpenoid compound isolated from the plant Rabdosia Rrubescens, has various pharmacological activities, including antioxidant, anti-tumor capacities and anti-inflammation. In the present study, we explore the role of oridonin in regulating endothelial inflammation and its underlying mechanism. Endothelial cell-monocyte interaction was detected by Leukocyte-endothelium Adhesion Assay. The protein expression was measured by Western blot. NF-κB p65 translocation was measured by immunofluorescence. Acute lung inflammation model was used to evaluate leukocyte infiltration in vivo. The endothelial-leukocyte adhesion and the leukocyte transmigration were profoundly reduced by oridonin. Oridonin dramatically inhibited the expression of TNF-α-induced endothelial adhesion molecules (intercellular adhesion molecule-1 (ICAM-1); vascular cell adhesion molecule-1 (VCAM-1) and E-selectin) and the pro-inflammatory cytokine (IL-6, IL-8 and monocyte chemoattractant protein-1(MCP-1)). Oridonin suppressed the penetration of the leukocyte in the acute lung injury mice model. Furthermore, Oridonin also suppressed the TNF-α-activated MAPK and Nuclear factor kappa B (NF-κB) activation. Our results suggest that oridonin has the anti-inflammatory properties in endothelial cells, at least in part, through the suppression of MAPK and NF-κB activation, which may have a potential therapeutic use for inflammatory vascular diseases.

Introduction

The endothelium forms a barrier between the vessel lumen and the surrounding tissue. Vascular endothelial cells play an important role in the regulation of vascular permeability, vascular tone, vascular inflammatory response and angiogenesis (Cines et al., 1998; Pober and Sessa, 2007). Endothelial dysfunction is associated with the development of inflammatory disorders states, including tumor, atherosclerosis, rheumatoid arthritis, inflammatory bowel disease and sepsis (Aird, 2007; Gareus et al., 2008; Khan et al., 2010; Roifman et al., 2009). Activation of the endothelium at sites of inflammation aggravates endothelial dysfunction and produces adhesion molecules and multiple cytokines, which could promote angiogenesis (Tian et al., 2009). A series of adhesion molecules, particularly vascular cell adhesion molecule1(VCAM-1), intercellular adhesion molecule 1 (ICAM-1), E-selectin and cytokines such as MCP-1, IL-6 and IL-8 (Robinson, 2014) are expressed in inflammatory disorders, by which the blockade reduces disease in models of multiple sclerosis, inflammatory bowel

disease, and asthma (Cook-Mills et al., 2011). Therefore, medications that suppressing the expression of pro-inflammatory cytokines and adhesion molecules are promising candidates for the treatment and prevention of chronic inflammatory diseases.

Oridonin, an active diterpenoid compound isolated from the plant Rabdosia Rrubescens, was found to possesses various physiological and pharmacological outcomes, such as anti-tumor, anti-bacteria, anti-inflammation, scavenging active oxygen free radicals and antimutagenetic effects (Han et al., 2004). Many studies have showed that oridonin was able to induce autophagy of a number of human cancer cell types, and have demonstrated remarkable anti-poliferative and pro-apoptotic effects against leukemia and some solid tumors (Guo et al., 2012), including hepatocellular carcinoma, gastric cancer, colorectal cancer, breast cancer, anrd pancreatic cancer (Bao et al., 2014; Kuo et al., 2014). Recent studies have demonstrated that oridonin was beneficial influences on immune balance and inhibits the release of proinflammatory mediators (Al-Amran et al., 2014; Ku and Lin, 2013). However, whether oridonin could have a potential role to affect vascular inflammation has not been clarified. In the current study, we investigated whether oridonin could inhibit TNF-α–induced vascular inflammation in human umbilical vein endothelial cells (HUVECs).

Section snippets

Cell culture

The human umbilical vein endothelial cells (HUVECs) had been isolated from umbilical veins which were obtained from the first affiliated hospital of sun yat-sen university, and cultivated as described previously. Cell isolation was approved by the first affiliated hospital of Sun Yat-sen University ethics committee. HUVECs were cultured in EBM2 media supplemented with various growth factors and 2% FBS (Lonza,CA, USA) when the cells reached 80–90% confluence. To avoid cell aging, all experiments

The effect of oridonin on HUVECs viability

The effect of oridonin on cell viability was confirmed by MTT assay. HUVECs were cultured until 90% confluent and exposed to oridonin at different concentrations and for 48 h. As shown in Fig. 1, we observed no significant inhibition in cell viability when cells were treated with oridonin at different concentrations for 48 h, compared to DMSO-treated cells, suggested no short-term toxicity to oridonin.

Oridonin reduced leukocyte adhesion to activated HUVEC monolayers

To explore the potential role of oridonin in endothelial activation, we measured the adhesion

Discussion

Vascular inflammation plays a key role in the pathogenesis of atherosclerosis, and the importance of adhesion molecules in atherosclerosis has been examined in many studies (Hoefen and Berk, 2002). The present study has demonstrated that oridonin, an effective component isolated from Rabdosia Rubescens, suppressed TNF-α-induced monocyte/HUVECs interactions by downregulating the expression of the adhesion molecules ICAM-1, VCAM-1, E-selectin and cytokines such as MCP-1, IL-6 and IL-8. Our

Conclusions

We have identified that oridonin modulates TNF-α-induced HUVECs activation by modulating the MAPK/NF-κB signaling pathway. Oridonin has great potential in the treatment of vascular inflammation diseases.

Acknowledgements

This work was supported by National Natural Science Foundation of China (Less Developed regions) (Grant No. 81560817).; the Guizhou Provinceial Science and Technology Funds, China (Grant No. [2013]2074); the Research Foundation for Young Scholars of Education Bureau of guizhou Province (Grant No. [2015]438); Project supported by the State Key Program for Basic Research of Guizhou Province (Grant No. [2015]2002).

Competing interests

No Conflict of Interest has been declared by authors.

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    WH, MH and HO contributed equally to this work.

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