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‐κB. 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‐κB luciferase reporter system, TNF‐α‐induced NF‐κB 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 IκB‐α, as well as nuclear translocation of NF‐κB heterodimer induced by TNF‐α. This suggests that rosmarinic acid downregulates the expression of CCL11 and CCR3 via the inhibition of NF‐κB activation signaling. 4 Using the NF‐κB luciferase reporter system, Western blot analysis, and IKK‐β activity assay, we determined that rosmarinic acid inhibits IKK‐β activity in NF‐κB 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‐κB activation signaling. Further, these results suggest that rosmarinic acid might inhibit the expression of NF‐κB promoter‐related genes. British Journal of Pharmacology (2006) 148, 366–375. doi:10.1038/sj.bjp.0706728