Induction of Heme Oxygenase-1 by Sodium 9-Hydroxyltanshinone IIA Sulfonate Derivative Contributes to Inhibit LPS-Mediated Inflammatory Response in Macrophages

BACKGROUND/AIM: Sodium 9-acetoxyltanshinone IIA sulfonate (ZY-1A4), a novel compound derived from sodium 9-hydroxyltanshinone IIA sulfonate, was synthesized with potential biological activities. This study aimed to explore the effects of ZY-1A4 on lipopolysaccharide (LPS)-triggered inflammatory response and the underlying mechanisms. METHODS: Activation of RAW264.7 macrophages was induced by LPS. The effects of ZY-1A4 on inducible nitric oxide synthase (iNOS) expression, nitric oxide (NO) generation, nuclear factor-κB (NF-κB) activation, heme oxygenase-1 (HO-1) expression, and nuclear factor-erythroid 2 related factor 2 (Nrf2) pathway were evaluated to elucidate its underlying mechanisms on inflammatory responses. RESULTS: ZY-1A4 concentration-dependently reduced iNOS expression and NO production, and inhibited c-Jun-N-terminal kinase 1/2 (JNK1/2) phosphorylation and NF-κB activation in LPS-stimulated macrophages. In addition, ZY-1A4 concentration- and time-dependently induced HO-1 expression associated with degradation of Kelch-like ECH-associated protein 1 (Keap1) and nuclear translocation of Nrf2, while the effect of ZY-1A4 was abolished by a phosphoinositide 3-kinase (PI3K) inhibitor LY294002. Intriguingly, pharmacological inactivation of HO-1 with zinc protoporphyrin IX reversed anti-inflammatory effect of ZY- 1A4, but the anti-inflammatory effect of ZY-1A4 was largely mimicked by HO-1 by-products carbon monoxide and bilirubin. Furthermore, the inhibitory effect of ZY-1A4 on LPS-induced iNOS expression and NO release was abolished by HO-1 siRNA or LY294002. CONCLUSION: Our results demonstrated that ZY-1A4 suppressed LPS-induced iNOS expression and NO generation via modulation of NF-κB activation and HO-1 expression. This new finding might shed light to the prevention and therapy of cardiovascular diseases.