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.