3,5-Di-C-β-(d)-glucopyranosyl phloroacetophenone, a major component of Melicope ptelefolia, suppresses fibroblast activation and alleviates arthritis in a mouse model: Potential therapeutics for rheumatoid arthritis

Melicope ptelefolia has been traditionally used to treat rheumatism and fever. The present study aimed to investigate the therapeutic effect of 3,5-di-C-β-(d)-glucopyranosyl phloroacetophenone (βGP), a main component of M. ptelefolia, on rheumatoid arthritis (RA). A model of collagen-induced arthritis (CIA) was established in mice using the RAW 264.7 murine macrophage cell line and mouse embryonic fibroblasts (MEFs). The clinical scores of arthritis, swelling, histopathological findings, and micro-computed tomography in CIA mouse paws were assessed. The levels of anti-type II collagen antibody and cytokines were determined in the plasma and cell culture supernatant, respectively. Protein and gene expression levels were analyzed by western blot and reverse transcription-quantitative polymerase chain reaction analyses. βGP significantly decreased the gross arthritic scores of CIA mice and joint swelling, and decreased articular inflammation, cartilage degradation and bone erosion. However, βGP did not exert any effect on anti-type II collagen immunoglobulin G plasma levels or inflammatory cytokine expression in macrophages. βGP significantly suppressed the expression of interleukin-6 and leukemia inhibitory factor and decreased the phosphorylation of signal transducer and activator of transcription 3, and expression of receptor activator of nuclear factor-κB ligand in tumor necrosis factor-α-stimulated MEFs and in CIA mouse paws. Osteoclast-related gene expression was significantly reduced in CIA mouse paws. Taken together, βGP suppressed the development of RA by regulating the activation of synovial fibroblasts.