Methotrexate (MTX) is the most important drug for treating rheumatoid arthritis (RA). It has been stated that cytokines play an important role in the pathogenesis of RA, and that cytokine levels increase and show 24-h rhythms in RA patients. Previously, we found that arthritis was relieved after the administration of MTX at specific times in synchronization with the 24-h rhythm of tumor necrosis factor (TNF)-α in collagen-induced arthritis (CIA) animals. Based on our findings in an earlier study of the dosing time-dependent effects of MTX in MRL/lpr mice, which develop autoimmune disorders that share similarities with human RA, we examined here the utility of MTX chronotherapy in Japanese RA patients. In an initial animal modeling study, we collected blood from MRL/lpr mice at different times (2, 6, 10, 14, 18, or 22 hours after the light was turned on [HALO]), and we measured TNF-α mRNA expression in leukocytes. MTX was administered to the mice at two different dosing times (6 or 18 HALO), and various blood parameters were measured to estimate arthritis activity. TNF-α mRNA levels showed a clear 24-h rhythm with a peak at 22 HALO and a trough at 18 HALO after RA had developed. In these MRL/lpr mice, inflammation and TNF-α were markedly reduced when the MTX dosing time was matched to the time (18 HALO) when the TNF-α level began to increase. We then applied these findings to Japanese RA patients by switching them from the standard MTX three times/wk (day 1: after breakfast and supper; day 2: after breakfast schedule), to chronotherapy, in which the dose and number of doses/wk were not changed but MTX was administered once-a-day at bedtime. Disease Activity Score (DAS)28, modified health assessment questionnaire (MHAQ), and adverse effects were assessed. With MTX chronotherapy, DAS28, which is commonly used to quantitatively assess RA symptoms, was significantly improved at all follow-up clinical visit times compared with the baseline (vs. 1 mo: p = .0197, 2 mos: p = .0107, 3 mos: p = .0087). Significant symptom recovery was observed in 41.2% of patients, and 23.5% of patients achieved clinical remission during the 3 mos of follow-up. Functional capacity of RA patients, as indicated by the MHAQ, was markedly improved by chronotherapy. There were no severe adverse effects. Thus, we demonstrated (i) inflammation and plasma TNF-α concentrations were significantly reduced in MRL/lpr mice treated with MTX at 18 HALO, the time when TNF-α mRNA level began to increase; and (ii) MTX bedtime chronotherapy was safe, markedly reduced disease activity, and improved the functional capacity of RA patients. The findings on RA patients show that bedtime MTX chronotherapy can improve RA symptoms compared to the current standard dosing methods.

Objective.: Chemokine ligand 20 (CCL20) is a selective ligand for chemokine receptor 6 (CCR6). We investigated, both in vitro and in vivo, whether CCL20 is critically involved in the disease process of rheumatoid arthritis (RA).Methods.: In vitro study investigated the effect of proinflammatory cytokines and biologic disease-modifying antirheumatic drugs (DMARD) on the production of CCL20 by rheumatoid fibroblast-like synovial cells (FLS). The in vivo role of CCL20 was studied by screening for serum CCL20 concentration in patients with RA during the therapeutic course of biologic DMARD, i.e., infliximab, etanercept, and tocilizumab.Results.: Spontaneous CCL20 production from rheumatoid FLS was minimal; however, its production was significantly stimulated by interleukin 1ß (IL-1ß), tumor necrosis factor-α (TNF-α), or IL-17. IL-1ß was the most potent for stimulating the production of CCL20. CCL20 production was synergistically augmented by a combination of IL-1ß, TNF-α, and IL-17. In contrast, interferon-γ suppressed IL-1ß-induced CCL20 production. IL-6, in combination with soluble IL-6 receptor (sIL-6R), did not modulate CCL20 production, whereas IL-1ß-induced, TNF-α-induced, and IL-17-induced production were increased by IL-6. These production levels were clearly suppressed by biologic DMARD in vitro. Serum CCL20 was significantly higher in RA than in control subjects, and was clearly decreased by the treatment with infliximab, etanercept, and tocilizumab.Conclusion.: Proinflammatory cytokines modulate the production of CCL20 from FLS. Our data suggest that therapeutic efficacy of biologic DMARD may result from the inhibition of CCL20 production in rheumatoid synovium.