Histone deacetylase inhibitor suppression of autoantibody-mediated arthritis in mice via regulation of p16INK4a and p21(WAF1/Cip1) expression.
OBJECTIVE
To examine whether depsipeptide (FK228), a histone deacetylase (HDA) inhibitor, has inhibitory effects on the proliferation of synovial fibroblasts from rheumatoid arthritis (RA) patients, and to examine the effects of systemic administration of FK228 in an animal model of arthritis.


METHODS
Autoantibody-mediated arthritis (AMA) was induced in 19 male DBA/1 mice (6-7 weeks old); 10 of them were treated by intravenous administration of FK228 (2.5 mg/kg), and 9 were used as controls. The effects of FK228 were examined by radiographic, histologic, and immunohistochemical analyses and arthritis scores. RA synovial fibroblasts (RASFs) were obtained at the time of joint replacement surgery. In vitro effects of FK228 on cell proliferation were assessed by MTT assay. Cell morphology was examined by light and transmission electron microscopy. The effects on the expression of the cell cycle regulators p16INK4a and p21(WAF1/Cip1) were examined by real-time polymerase chain reaction and Western blot analysis. The acetylation status of the promoter regions of p16INK4a and p21(WAF1/Cip1) were determined by chromatin immunoprecipitation assay.


RESULTS
A single intravenous injection of FK228 (2.5 mg/ml) successfully inhibited joint swelling, synovial inflammation, and subsequent bone and cartilage destruction in mice with AMA. FK228 treatment induced histone hyperacetylation in the synovial cells and decreased the levels of tumor necrosis factor alpha and interleukin-1beta in the synovial tissues of mice with AMA. FK228 inhibited the in vitro proliferation of RASFs in a dose-dependent manner. Treatment of cells with FK228 induced the expression of p16INK4a and up-regulated the expression of p21(WAF1/Cip1). These effects of FK228 on p16INK4a and p21(WAF1/Cip1) were related to the acetylation of the promoter region of the genes.


CONCLUSIONS
Our findings strongly suggest that systemic administration of HDA inhibitors may represent a novel therapeutic target in RA by means of cell cycle arrest in RASFs via induction of p16INK4a expression and increase in p21(WAF1/Cip1) expression.
Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan. knishida@md.okayama-u.ac.jp
Keiichiro
K
Nishida
Takamitsu
T
Komiyama
Shin-Ichi
S
Miyazawa
Zheng-Nan
ZN
Shen
Takayuki
T
Furumatsu
Hideyuki
H
Doi
Aki
A
Yoshida
Jiro
J
Yamana
Masahiro
M
Yamamura
Yoshihumi
Y
Ninomiya
Hajime
H
Inoue
Hiroshi
H
Asahara
D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000473:pathology*; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000473:pathology*; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000032:analysis; D002478:Cells, Cultured; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000032:analysis*; D047630:Depsipeptides / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D005347:Fibroblasts / Q000473:pathology; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D016133:Polymerase Chain Reaction; D013583:Synovial Membrane / Q000473:pathology*
C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D018797:Cell Cycle Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D047630:Depsipeptides; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; C087123:romidepsin