To investigate the effect of parthenolide (PAR) on the tumor necrosis factor (TNF)-alpha induced aggrecan catabolism of chondrocytes in osteoarthritis (OA).
Human chondrocytes were obtained from the condyles of femur of OA patients undergoing knee joint replacement during operation, cultured, and randomly divided into 4 groups: control group, TNF group (cultured in medium containing 10 ng/ml TNF-alpha) , PAR group (cultured in medium containing 10 micromol/L PAR), and PAR + TNF group (cultured in medium containing 10 micromol/L PAR and 10 ng/ml TNF-alpha). Eight days later 1, 9-dimethylmethylene blue spectrophotometric assay was used to measure the content of glycosaminoglycan (GAG) , marker of aggrecan catabolism, in the culture fluid and the cells. Using anti-aggrecan monoclonal antibodies Mab 5D4 and 3B3, ELISA was employed to detect the contents of 5D4 and 3B3, aggrecan catabolic fragments. RT-PCR was used to detect the mRNA expression of the aggrecan, ADAMTS-4 and ADAMTS-5, both aggrecanases, tissue inhibitor of metalloprotease (TIMP)-1, mitogen-activated protein kinase (MAPK)-1 and 18S, a marker.
The GAG percentage in the culture fluid of the TNF-alpha was 57.1% +/- 2.0%, significantly higher than those of the control and TNF-alpha + PAR groups (P = 0.001 and 0.02). The 5D4 fragment level of the TNF-alpha group was 509 ng/ml +/- 32 ng/ml, significantly higher than that of the control group (166 ng/ml +/- 15 ng/ml, t = 11.60, P =0.007), and the level of 5D4 fragment of the PAR + TNF-alpha group was 333 ng/ml +/- 15 ng/ml, significantly lower than that of the TNF-alpha group (t = 7.93, P = 0.016). There was not significant difference in the 3B3 fragment level among the 4 groups (F = 1.316, P = 0.335). The aggrecan mRNA expression level of the TNF-alpha group was significantly lower than those of the other 3 groups (F = 133.7, P = 0.000), the mRNA expression levels of ADAMTS-5 and MAPK-1 of the TNF-alpha group were significantly higher than those of the other 3 groups (F = 209. 7, 117.1; P =0. 000), the ADAMTS-5 mRNA expression level of the PAR group was significantly lower than that of the control group (t = 11.1, P= 0.008) , and there was not significant differences in the mRNA expression levels of ADAMTS-4 and TIMP-1 among the 4 groups (F = 1.87, 0.73; P > 0.05) .
PAR inhibits TNF-alpha induced catabolism of aggrecan in the chondrocytes of OA and reduces the mRNA expression of ADAMTS-5 and MAPK-1. PAR may be useful in the treatment of OA and other inflammatory joint diseases.