Triptolide, a novel diterpenoid triepoxide fromTripterygium wilfordii Hook. f., suppresses the production and gene expression of pro-matrix metalloproteinases 1 and 3 and augments those of tissue inhibitors of metalloproteinases 1 and 2 in human synovial fibroblasts

Abstract

Objective Various extracts of the Chinese herbal remedy Tripterygium wilfordii Hook. f. (TWHF) have been reported to be therapeutically efficacious in rheumatoid arthritis (RA) in China, but their mechanism of action remains unclear. We investigated the effect of triptolide, a diterpenoid triepoxide from TWHF, on the production of pro–matrix metalloproteinase 1 (proMMP‐1; or procollagenase 1 or pro–interstitial collagenase 1), proMMP‐3 (or prostromelysin 1), tissue inhibitors of metalloproteinases (TIMPs), and proinflammatory cytokines in human synovial fibroblasts and J774A.1 mouse macrophages. Methods Human synovial fibroblasts and mouse macrophages were cultured with interleukin‐1α (IL‐1α) or lipopolysaccharide (LPS) in the presence or absence of triptolide. The production of proMMPs 1 and 3, TIMPs 1 and 2, cyclooxygenase 1 (COX‐1) and COX‐2, prostaglandin E2 (PGE2), IL‐1β, and IL‐6 was assayed by Western blot analysis and enzyme‐linked immunosorbent assay. Gene expression of proMMPs 1 and 3, TIMPs 1 and 2, COX‐1 and COX‐2, IL‐1α, IL‐1β, tumor necrosis factor α (TNFα), and IL‐6 was also monitored by Northern blot analysis and reverse transcriptase–polymerase chain reaction. Results Triptolide suppressed the IL‐1α–induced production of proMMPs 1 and 3 and decreased their messenger RNA levels in human synovial fibroblasts. In contrast, the IL‐1α–induced gene expression and production of TIMPs 1 and 2 were further augmented by triptolide in the synovial cells. Triptolide also inhibited the IL‐1α–induced production of PGE2 by selectively suppressing the gene expression and production of COX‐2, but not those of COX‐1. In addition, triptolide suppressed the LPS‐induced production of PGE2 in mouse macrophages. Furthermore, the gene expression of IL‐1α, IL‐1β, TNFα, and IL‐6, as well as the production of IL‐1β and IL‐6, were inhibited by triptolide in the LPS‐treated mouse macrophages. Conclusion We have demonstrated for the first time that the therapeutic effects of TWHF in RA are due in part to the novel chondroprotective effect of triptolide via the direct suppression of the production of proMMPs 1 and 3 and the simultaneous up‐regulation of TIMPs in IL‐1–treated synovial fibroblasts. Triptolide's interference with gene expression of proinflammatory cytokines and its known inhibitory effects on PGE2 production are also probably very effective.

Triptolide Attenuates Endotoxin- and Staphylococcal Exotoxin-Induced T-Cell Proliferation and Production of Cytokines and Chemokines

“…Previous studies showed that triptolide inhibited transcriptional activation through NFkB [28] and suppressed TNFa production by LPS-stimulated macrophages [23] and IL-2 production by PHA-activated T cells. [28] Our results extend these observations by showing inhibition of multiple inflammatory mediators in staphylococcal exotoxin-activated PBMC at both transcriptional and protein level.…”

“…[22] In human synovial fibroblasts, triptolide suppresses the production and expression of prometalloproteinases 1 and 3 and inhibits the expression of COX-2 and IL-1-induced PGE 2 production. [23] Triptolide also inhibits vascular endothelial cell growth factor expression in phorbol 12-myristate 13-acetate (PMA)-activated endothelial cells [24] and attenuates the expression of IL-6, IL-8, and cell adhesion molecule ICAM-1 by PMA-stimulated human bronchial epithelial cells. [25] The effects of triptolide on other cell types include the inhibition of the expression of C3, CD40, and B7H in TNFa-activated human proximal tubular epithelial cells [26] and suppression of LPS-induced TNFa, IL1b, and nitric oxide production by microglial cells.…”

Medicinal chemistry and pharmacology of genus Tripterygium (Celastraceae)

“…The inhibition of PGE 2 production was due to suppression of COX-2 . COX-1 expression was not affected (Lin et al, 2001a). As with the extracts, the inhibitory effects of 1 on PGE 2 production varied depending on the cell line studied .…”

“…Similarly, triptolide (1) suppressed expression of COX-2 and the precursor forms of MMP-1 and -3, and inhibited production of PGE 2 and NO and activity of lipoxygenase Lin et al, 2001a;Zhou et al, 2003). The inhibition of PGE 2 production was due to suppression of COX-2 .…”

“…Consistent with the effect on the proinflammatory signals, extracts strongly inhibited proliferation of T and B cells (Tao et al, 1991(Tao et al, , 1995. Pure triptolide (1) also inhibited T cell proliferation and production of TNF-α, IL-1, IL-2, IL-6, and IL-8 (Tao et al, 1995;Chan et al, 1999;Qiu et al, 1999;Lin et al, 2001a;Zhou et al, 2003). The suppression of metabolic activity in T cells was not due solely to reduction in cell viability (Chan et al, 1999).…”