title: Tumor necrosis factor-alpha inhibitors suppress CCL2 chemokine in monocytes via epigenetic modification.
abstract: The treatment of rheumatoid arthritis (RA) with tumor necrosis factor-alpha (TNF-α) inhibitors could lead to adverse effects. Therefore, the identification of downstream therapeutic targets is important. Monocyte chemoattractant protein-1 (MCP-1, also called CCL2) is related to RA disease activity, and epigenetic modifications are hypothesized to regulate gene expression in RA pathogenesis. We studied the effects of two TNF-α inhibitors, etanercept and adalimumab, on CCL2 expression and the potentially associated intracellular mechanisms, including epigenetic regulation. Etanercept and adalimumab decreased CCL2 production in THP-1 cells and human primary monocytes, as detected using enzyme-linked immunosorbent assays, and these changes in the CCL2 levels were independent of the TNF-α levels. Etanercept and adalimumab suppressed mitogen-activated protein kinase (MAPK) phospho-p38, phospho-JNK, phospho-ERK and nuclear factor-κB (NF-κB) phospho-p65, as demonstrated using western blot analyses. The investigation of epigenetic modifications using chromatin immunoprecipitation revealed that etanercept and adalimumab down-regulated acetylation of histone (H)3 and H4 in the CCL2 promoter region by decreasing the recruitment of the NF-κB associated acetyltransferases p300, CBP and PCAF. Etanercept and adalimumab also down-regulated trimethylation of H3K4, H3K27, H3K36 and H3K79 in the CCL2 promoter region by decreasing the expression of the related methyltransferases WDR5 and Smyd2. We demonstrated that TNF-α inhibitors exert immunomodulatory effects on CCL2 expression in human monocytes via MAPKs, NF-κB and epigenetic modifications. These findings broaden the mechanistic knowledge related to TNF-α inhibitors and provide novel therapeutic targets for RA.
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Laboratory Medicine, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yi-Ching
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Division of General Internal Medicine, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Ming-Yii
authors.initials: MY
authors.lastname: Huang
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Institute of Medical Science and Technology, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Po-Lin
authors.initials: PL
authors.lastname: Kuo
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Cheng-Chin
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Min-Sheng
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chong-Chao
authors.initials: CC
authors.lastname: Hsieh
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hsuan-Fu
authors.initials: HF
authors.lastname: Kuo
authors.affiliation: Ta-Kuo Clinic, Kaohsiung, Taiwan.
authors.forename: Chang-Hung
authors.initials: CH
authors.lastname: Kuo
authors.affiliation: Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Division of Rheumatology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: d740094@cc.kmu.edu.tw.
authors.forename: Wen-Chan
authors.initials: WC
authors.lastname: Tsai
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Pediatrics, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan; Department of Pediatrics, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: pedhung@gmail.com.
authors.forename: Chih-Hsing
authors.initials: CH
authors.lastname: Hung
mesh_terms: D000068879:Adalimumab / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000276:immunology*; D015153:Blotting, Western; D018932:Chemokine CCL2 / Q000096:biosynthesis* / Q000235:genetics; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D000068800:Etanercept / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D006657:Histones; D014409:Tumor Necrosis Factor-alpha; D000068879:Adalimumab; D000068800:Etanercept
keywords: CCL2; Epigenetic regulation; Monocyte; Rheumatoid arthritis; TNF-α inhibitors