Penta-acetyl geniposide induces apoptosis of fibroblast-like synoviocytes from adjuvant-induced arthritis rats in vitro, associated with inhibition of NF-κB activation.

Approaches promoting fibroblast-like synoviocytes (FLS) apoptosis are considered as a meaningful strategy for rheumatoid arthritis (RA) treatment. We have previously reported the anti-arthritic effect of penta-acetyl geniposide ((Ac)₅GP, an active derivative of geniposide) on adjuvant-induced arthritis (AIA) rats in vivo. The present study aimed to investigate the pro-apoptotic effect of (Ac)₅GP on AIA FLS in vitro and the underlying molecular mechanisms.

Rat AIA was induced by complete Freund's adjuvant, and FLS were primary-cultured from synovial tissues. AIA FLS were treated with (Ac)₅GP (50, 100 and 200 μM) for 48 h and cell proliferation and apoptosis were respectively examined. The involvement of apoptosis-related proteins (Bax, Bcl-2 and caspase 3) and nuclear factor kappa B (NF-κB) signaling pathway was checked.

(Ac)₅GP inhibited the viability of AIA FLS and reduced the percentage of Ki67-positive cells in AIA FLS. Particularly, (Ac)₅GP promoted AIA FLS apoptosis in vitro by inducing apoptotic nuclear morphology, facilitating DNA ladder formation and increasing percentages of both early and late apoptotic cells. (Ac)₅GP treatment on AIA FLS decreased Bcl-2 protein level whereas increased the levels of Bax and caspase 3 proteins. Moreover, (Ac)₅GP reduced the degradation and phosphorylation of IκBα, down-regulated NF-κB p65 protein level in nucleus and inhibited NF-κB p65 nuclear translocation.

(Ac)₅GP had a potent pro-apoptotic effect on AIA FLS in vitro, which is associated with regulating apoptosis-related proteins and inhibiting NF-κB activation.