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Comparison of gene- and protein expression profiles of a standarized willow bark extract with Quercetin and non-steroidal antiinflammatory drugs in human chondrocytes
Willow bark extracts are indicated in the treatment of rheumatic pain and inflammation. Their efficacy is primarily attributed to the content of salicin and its derivates as pro-drugs for salicylates. However, based on clinical experience and experimental pharmacological evidences, the fraction of total salicin cannot fully explain the clinical efficacy of willow bark. To further elucidate this issue we compared the gene- and protein-expression-profiles of a standarized willow bark extract (Proaktiv®, WB) with the ones of quercetin (Q), acetylsalicyclic acid (ASS) and diclofenac (D) in human chondrocytes. We stimulated synchronized chondrocytes for 6 hrs with WB (30µg/ml, 50µg/ml), Q (10µM), ASS (30µg/ml) and D (50µg/ml). Gene microarrays (Agilent Whole Human Genome Microarray, ˜41 000 genes) revealed an overall significant modulation of 9002 genes. Interexperimental correlation- and cluster analyses of filtered data revealed specific RNA expression profiles for each substance. The RNA expression profile of WB was closer to Q than to ASS and D. Selected protein expression profiling (cytokine (23) and matrixmetalloproteinase (10) antibody microarrays) of cell lysates in parallel experiments (n=3) revealed a significant modulation of IL-5, IL-6, IL-7, IL-10; MCP-1, MCP-3, Groa, GCSF, GMCSF, MIG, RANTES, MMMP-2, MMP-3, MMP-8 for WB (30µg/ml) and additionally IL1a, TNF-α, TNF-ß, TGF-ß, MCP-2 for WB (50µg/ml); Q modulated IL-2, IL-7, IL-10, IL13, IL-15, MCP-3; MIG, RANTES, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10 and TIMP-4 supporting gene-expression data. Polyphenols may contribute to the overall effect of willow bark. However in vivo gene- and protein expression profiling, considering bioavailability, are essential to further substantiate these findings.