A traditional herbal formula restrains bone erosion in experimental models of rheumatoid arthritis

Rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease, is characterized by synovial hyperplasia and bone erosion. Current therapies have limitations. A traditional herbal formula (RL) comprising Rosae Multiflorae Fructus and Lonicerae Japonicae Flos, is traditionally used for treating RA in China. We have previously shown that an ethanolic extract of RL (RLE) possesses anti-RA properties. Recently, we determined whether RLE attenuates bone erosion by inhibiting osteoclastogenesis, and investigated the involvement of NF-κB, MAPK and STAT3 pathways in RLE’s anti-osteoclastogenic effects.

On bovine bone slides seeded with RANKL-stimulated macrophages, RLE inhibits bone resorption. Micro-CT analyses showed that RLE attenuates bone erosion in CIA rats. Further assays showed that RLE decreases osteoclasts in the joints of CIA rats, and inhibits osteoclastogenesis in RANKL-stimulated macrophages and a co-culture system (IL-6/sIL-6R-stimulated RA-FLS/PBMCs). RNA-seq analysis of rat synovia tissues and molecular analyses demonstrated that inhibition of NF-κB, MAPK and STAT3 pathways is involved in the anti-osteoclastogenic effects of RLE.
In conclusion, our novel findings demonstrate that RLE attenuates bone erosion in CIA rats; inhibition of osteoclastogensis is one of the cellular anti-RA mechanisms of RLE and suppression of NF-κB, MAPK and STAT3 pathways is involved in RLE’s molecular anti-RA mechanisms.

This study provides pharmacological justifications for the use of the formula RL in treating RA, and suggests that RLE has the potential to be developed into a modern anti-RA agent.