Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

Epigallocatechin gallate (EGCG) restores 25-hydroxy vitamin D levels in rheumatoid arthritis patients by attenuating ROS-mediated activation of NF-κB

Yuhong Liu¹, Yidun Xie², Mailing Liu³, Junfeng Yang⁴

¹Department of Outpatient, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061; ²Department of Stomatology, Ninth Hospital of Xi 'an, Xi'an 710054; ³Department of Pediatrics, Pucheng County Hospital. Pucheng 715500; ⁴Department of Rheumatology and Immunology, Xi'an Fifth Hospital, Xi'an, Shaanxi 710082, China.

For correspondence:- Junfeng Yang Email: yinshiyi@163.com Tel:+862984696442

Accepted: 21 June 2021 Published: 29 July 2021

Citation: Liu Y, Xie Y, Liu M, Yang J. Epigallocatechin gallate (EGCG) restores 25-hydroxy vitamin D levels in rheumatoid arthritis patients by attenuating ROS-mediated activation of NF-κB. Trop J Pharm Res 2021; 20(7):1395-1402 doi: 10.4314/tjpr.v20i7.11

© 2021 The authors.
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Abstract

Purpose: To investigate the mechanism by which epigallocatechin gallate (EGCG) attenuates ROS-induced pathogenesis in a rheumatoid arthritis (RA) patients.

Methods: Fifty patients (33 male and 17 female) aged between 25 and 60 years who satisfied ACR 1987 criteria for active RA, and thirty healthy individuals were recruited. Total peripheral blood mononuclear cells (PBMCs), neutrophils and monocytes were isolated from the blood samples of RA patients and healthy donors using commercial extraction kits. Levels of reactive oxygen species (ROS) and superoxide radical (O^2-) in isolated cells were measured using fluorescence spectroscopy while the levels of the associated inflammatory cytokines (TNF-α and IL-6) were determined in PBMCs isolated from RA patients using enzyme-linked immunosorbent assay (ELISA). These parameters were monitored in EGCG-treated and untreated cells. Moreover, the status of 25(OH) vitamin D and NK-κB were investigated in lipopolysaccharide (LPS)-challenged PBMCs in the presence and absence of EGCG.

Results: Elevated levels of superoxide radical and ROS were observed in neutrophils from RA patients in the absence of ECGC, but in the presence of EGCG, the levels of the two parameters were significantly reduced (p < 0.05). Similarly, EGCG treatment downregulated the ROS-mediated increases in TNF-α and IL-6 in the PBMCs from RA patients (p < 0.05). Treatment of PBMCs with the ROS-inducing agent, LPS, resulted in the activation of NK-κB via phosphorylation, and also depletion of 25(OH) vitamin D levels (p < 0.05). However, pre-treatment of the LPS-challenged cells with EGCG inhibited NK-κB activation and 25(OH)-vitamin D depletion (p < 0.05). Moreover, 25(OH)vitamin D levels were restored in the presence of NK-κB inhibitor, flavopiridol, thereby confirming the direct regulatory role of NK-κB in 25(OH) vitamin D levels.

Conclusion: EGCG restores 25(OH) vitamin D levels by attenuating ROS-mediated NK-κB activation. Thus, EGCG may be a promising drug candidate for RA.

Keywords: Rheumatoid arthritis, Vitamin D, Epigallocatechin gallate, Oxidative stress, NK-κB