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Comparative functional genomic studies of anti-inflammatory phytocompounds on immune signaling mechanisms in human monocytes
To characterize the immunomodulatory activities of three anti-inflammatory phytocompounds (emodin, shikonin, and cytopiloyne), and a defined extract from the Echinacea purpurea (BF/S+L/Ep), we conducted a focused DNA microarray study on selected immune-related genes, using LPS-stimulated THP-1 monocytes. Initially (within 0.5 hour), shikonin and emodin significantly inhibited (>3-fold) the expression of approximately 50 genes, most notably the cytokines TNF-α, IL-1β and IL-4, the chemokines CCL4 and CCL8, and the inflammatory modulators NFATC3 and PTGS2. In contrast, neither cytopiloyne nor BF/S+L/Ep inhibited the early expression of this group of 50 genes, but rather inhibited the late-stage expression (˜12 hours) of many of these genes, including particularly IL-4, NFATC3 and PTGS2, and the cell migration and chemokine molecules CDH1 and ITGA2. Using „key node“ analysis with the TRANSPATH® database, we identified the extracellular signal-regulated kinase (ERK) 1/2 activation pathway as the putative target of BF/S+L/Ep and cytopiloyne. Experiments using western blot analysis subsequently confirmed that a delay inactivation of the ERK pathway was indeed detectable during the mid-term stage (˜4 hours) of LPS stimulation. Using the same algorithm, we also identified the ubiquitin pathway regulators, E6-AP and Rad23A, to be possible key regulators for emodin or shikonin, respectively. The powerful genomic approach provides novel mechanistic insights and suggests molecular targets that distinguish different anti-inflammatory phytocompounds at the molecular and cellular levels, and offers useful information for the future development of phytocompounds or preparations as defined health supplements or herbal medicines.