Rosmarinic acid as a downstream inhibitor of IKK‐ β in TNF‐ α ‐induced upregulation of CCL11 and CCR3

1 Tumor necrosis factor (TNF)‐ α is known to induce the expression of CCL11 and CCR3 via the activation of NF‐ κ B. CCL11 (eotaxin), the C–C chemokine, is a potent chemoattractant for eosinophils and Th2 lymphocytes, and CCR3 is the receptor for CCL11. 2 In order to determine the effects of rosmarinic acid on the TNF‐ α ‐induced upregulation of CCL11 and CCR3 in human dermal fibroblasts, we performed an enzyme‐linked immunosorbent assay for CCL11 and a Western blot assay for CCR3. The TNF‐ α ‐induced expression of CCL11 and CCR3 genes was attenuated by rosmarinic acid. 3 In our NF‐ κ B luciferase reporter system, TNF‐ α ‐induced NF‐ κ B activation was observed to be reduced by rosmarinic acid. In accordance with this result, rosmarinic acid also inhibited TNF‐ α ‐induced phosphorylation and degradation of I κ B‐ α , as well as nuclear translocation of NF‐ κ B heterodimer induced by TNF‐ α . This suggests that rosmarinic acid downregulates the expression of CCL11 and CCR3 via the inhibition of NF‐ κ B activation signaling. 4 Using the NF‐ κ B luciferase reporter system, Western blot analysis, and IKK‐ β activity assay, we determined that rosmarinic acid inhibits IKK‐ β activity in NF‐ κ B signaling, which upregulates the expression of CCL11 and CCR3 . Additionally, TNF‐ α ‐induced secretion of soluble intercellular adhesion molecule‐1 and soluble vascular cell adhesion molecule‐1 molecules was found to be attenuated by rosmarinic acid. 5 Our results show that rosmarinic acid inhibits the expression of CCL11 and CCR3 by suppressing the IKK‐ β activity in NF‐ κ B activation signaling. Further, these results suggest that rosmarinic acid might inhibit the expression of NF‐ κ B promoter‐related genes.British Journal of Pharmacology (2006) 148 , 366–375. doi: 10.1038/sj.bjp.0706728