Identification of a Spectrum of Therapeutic Targets of a New Treatment for Osteoarthritis Composed by Curcuminoids Extract, Hydrolyzed Collagen and Green Tea Extract

Purpose: The goal of treatment in OA is to reduce pain and improve function. There is no cure for the disease, but some attempts to slow the progression of the disease. We have previously demonstrated that a mixture of curcuminoids extract, hydrolyzed collagen and green tea extract (COT) inhibited inflammatory and catabolic mediator’s synthesis by osteoarthritic human chondrocytes in monolayer. The objective of this study was to identify new targets of COT using genomic and proteomic approaches. Methods: Enzymatically isolated primary human chondrocytes were cultured in monolayer until confluence and then incubated for 24 or 48 hours in the absence or in the presence of human interleukin-1β (10−11 M) and with or without COT, each compound at the concentration of 4 μg/ml. Microarray gene expression profiling between control (ctrl), COT, IL-1β and COT IL-1β conditions was performed. The biological relevance of regulated genes was determined with Ingenuity Pathway Analysis. Immunoassays (ELISA) were used to confirm the identified genes that were differentially expressed. Results: 2549 genes were differentially expressed between ctrl and IL-1β conditions, 2280 genes were differentially expressed between IL-1β and COT IL-1β conditions and 1907 genes were differentially expressed between ctrl and COT conditions. The key regulated pathways were related to inflammation, cartilage metabolism and angiogenesis. In the inflammatory pattern, the IL 1β stimulated chemokine (C-X-C motif) ligand 6 (CXCL6) gene expression and protein production were strongly down-regulated by COT (p<0.001). The most IL-1β up-regulated enzyme in the catabolic pattern was matrix metalloproteinase-13 (MMP-13). Both gene and protein were significantly down regulated by COT (p<0.001). The IL 1β-stimulated bone morphogenetic protein-2 (BMP-2) gene expression and protein production were down-regulated by COT (p=0.001). In the angiogenesis pathway, one of the most up-regulated factor by IL-1β was stanniocalcin 1 (STC1) (p=0.005). This IL 1β stimulating effect was significantly down regulated by COT (p<0.001). Moreover, COT significantly decreased STC1 production in basal condition (p=0.030). Finally, serpin E1 gene expression and protein production were down-regulated by IL 1β (p<0.001). COT fully reversed the inhibitory effect of IL-1β (p=0.028). Serpin E1 gene expression was up-regulated by COT in basal condition (p<0.001). Conclusions: The mixture COT has beneficial effect on OA physiopathology by regulating the synthesis of key catabolic, inflammatory and angiogenesis factors. These findings give a scientific rationale to assess these natural ingredients in human clinical trials.