Background Gliostatin (GLS) is known to have angiogenic and arthritogenic activities¹. We also reported a decrease in serum GLS levels in RA patient responders treated with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs)². Tacrolimus (TAC), an orally available calcineurin inhibitor, is a potent immunosuppressant. The efficacy of TAC monotherapy and the combination therapy with TAC and methotrexate in the treatment of RA has been previously described³. Although the principal TAC action is thought to be the inhibition of T cell activation, its beneficial effect on RA synoviocytes has not been yet elucidated.

Objectives To determine the inhibitory effects of TAC on GLS production in RA, we investigated the modulation of serum GLS by TAC therapy and the effect of TAC on the production of GLS in cultured fibroblast-like synoviocytes (FLSs).

Methods Serum samples were collected from eleven RA patients with active disease at baseline and after 12 weeks of TAC treatment. These RA patients had a history of unsatisfied response with at least one csDMARD or biological DMARD. Serum concentrations of GLS and matrix metalloproteinase (MMP)-3 were measured by enzyme immunoassay (EIA). Synovial specimens were obtained from RA patients at the time of total knee arthroplasty. FLSs were cultured and stimulated by TNF alfa with or without TAC. The expression levels of GLS were determined using RT-PCR and EIA. MMP-3 protein in conditioned media was measured by using EIA.

Results Six patients fulfilled good and moderate responder and the other five patients fulfilled no responder with EULAR response criteria. DAS28, serum GLS, CRP and MMP-3 were significantly down-regulated in TAC responders. In RA FLSs, GLS mRNA and protein were significantly induced after treatment with TNF alfa alone (GLS mRNA 21.9-fold, protein 1.5-fold compared to control). These inductions were suppressed by TAC in a dose-dependent manner. MMP-3 protein was induced by TNF alfa and was similarly suppressed by TAC in a dose-dependent manner (MMP-3 protein 2.9-fold compared to control).

Conclusions This study is the first to demonstrate that TAC down-regulates GLS mRNA and protein in FLSs treated by TNF alfa. Our data suggests that the beneficial effect of TAC in RA might be due to, at least in part, to anti-angiogenic and anti-arthritogenic activity following the down-regulation of GLS.

References

1. Asai K, et al. High concentration of immunoreactive gliostatin/ platelet-derived endothelial cell growth factor in synovial fluid and serum of rheumatoid arthritis. Clin Chim Acta 1993;218:1–4.

2. Kusabe T, et al. The inhibitory effect of disease-modifying anti-rheumatic drugs and steroids on gliostatin/platelet-derived endothelial cell growth factor production in human fibroblast-like synoviocytes. Rheumatol Int 2005;25:625–630.

3. Kremer JM, et al. Tacrolimus in rheumatoid arthritis patients receiving concomitant methotrexate: a six-month, open-label study. Arthritis Rheum 2003;48:2763–2768.

References

Acknowledgements This research was supported by Grand-in-Aid for Scientific Research(C) (26462309) and 16K10913 from the Japan Society for the Promotion of Science.

Disclosure of Interest K. Ikuta: None declared, Y. Waguri-Nagaya Grant/research support from: Biomet Japan, Inc, Chugai Pharmaceutical Co., Ltd., Astellas Pharma Inc., Merck Sharp & Dohme Co., AbbVie Japan Co., Ltd., Ono Pharmaceutical Co., Ltd., T. Yamagami: None declared, N. Tatematsu: None declared, Y. Kawaguchi: None declared, Y. Oguri: None declared, T. Terazawa: None declared, M. Kobayashi: None declared, K. Asai: None declared, T. Otsuka: None declared