Response to D.M. Marcus's comment on the TRIFRA study (comparison ofTripterygium wilfordiiHook F vs methotrexate in the treatment of active rheumatoid arthritis)

Will Chinese external therapy with compound Tripterygium wilfordii hook F gel safely control disease activity in patients with rheumatoid arthritis: design of a double-blinded randomized controlled trial

BACKGROUND

Chinese external therapy (CET) is a topical application with mainly Chinese herb medicine therapy with thousands of years of historical implications and is a clinical routine that is commonly used for relieving joint-related symptoms in patients with arthritis in Chinese hospitals. However, there is a paucity of modern medical evidence to support its effectiveness and safety. Thus, we propose to implement a randomized, double-blinded, placebo-controlled clinical trial in patients with rheumatoid arthritis (RA) using, as the experimental intervention, topical application of a hospital-compounded gel preparation of Tripterygium wilfordii Hook F (TwHF).

METHODS

This study will be an 8-week double-blinded, randomized, placebo-controlled clinical trial conducted at Guang'anmen Hospital in Beijing, China, and 168 patients with moderately active RA will be randomly assigned with a 1:1 ratio to apply a topical gel preparation containing TwHF or placebo. The primary outcome variable will be the proportion of subjects, by study group, to achieve a 20% improvement in the American College of Rheumatology criteria (ACR20) by week 8. Secondary outcome measures to be assessed at weeks 4 or 8 will include: measurement of ACR20 response rate at week 4, ACR50 response rate, the changes in DAS28 score, and joint synovitis classification assessment monitored by musculoskeletal ultrasound. Safety evaluations conducted at weeks 4, 8 and 12 will be based on spontaneous complaints by the study subjects, but special emphasis will be focused on cutaneous allergy and alterations of menstruation in premenopausal female participants. Statistical analyses will be performed using the intention to treat analysis data set.

DISCUSSION

This proposed clinical trail is designed to evaluate the efficacy and safety of CET based on a single topically-applied agent in a relatively large patient population with RA. This study protocol gives a detailed description of the usage and dosage of the topical compound TwHF gel and the methodology of this study. In addition, it is hoped that the outcomes of this study will be viewed as supporting the generalizability of CET in the setting of inflammatory rheumatic diseases. The results of this study are expected to have important public health implications for Asian RA patients that currently utilize CET as a complimentary treatment.

TRIAL REGISTRATION

Clinical trial gov Identifier: NCT02818361 . Registrated on Jun. 15, 2016.

Celastrol attenuates bone erosion in collagen-Induced arthritis mice and inhibits osteoclast differentiation and function in RANKL-induced RAW264.7

Recently, the traditional Chinese medicine Tripterygium wilfordii Hook f (TwHF) of the Celastraceae family has attracted increasing attention for its potential therapeutic application in patients with rheumatoid arthritis (RA). It is well accepted that TwHF exerts the antirheumatic activity and mainly depends on its potent anti-inflammatory property. To further explore the therapeutic potential of the well-defined TwHF-derived single compound - celastrol in RA, we study the therapeutic efficacy of celastrol on bone erosion in collagen-induced arthritis (CIA) mice and delineate its effects on osteoclast differentiation and functions in RANKL-induced osteoclast precursors RAW264.7 cell line. In CIA mice, daily injection of celastrol (beginning on day 28 after arthritis induction) markedly suppressed arthritis, and reduced bone damage in the joints as demonstrated by histology and bone micro-computed tomography (CT). The effects were accompanied by reductions of osteoclast cells in joints, serum tartrate-resistant acid phosphatase (TRAP) 5b, and expression of osteoclastic genes (Trap, Ctsk, Ctr, Mmp-9) and transcriptional factors (c-Fos, c-Jun and NFATc1). When RAW264.7 cells were treated with RANKL, celastrol inhibited the formation of TRAP+ multinucleated cells and the bone-resorbing activity in dose-dependent manners. Furthermore, celastrol reduced the RANKL-induced expression of osteoclastic genes and transcriptional factors, as well as phosphorylation of NF-kB and mitogen-activated protein kinases (MAPK). These findings show that celastrol could directly inhibit osteoclast formation and function, suggesting a novel therapeutic strategy of celastrol for managing RA, especially in preventing bone destruction.