Induction of heme oxygenase-1 expression by cilostazol contributes to its anti-inflammatory effects in J774 murine macrophages

The effects of cilostazol on stimulating heme oxygenase (HO)-1 expression including signal pathways and suppression of inflammatory cytokines and molecules were studied. Cilostazol stimulation time (1–8 h)- and concentration (1–30 μM)-dependently increased the HO-1 mRNA and protein expression associated with increased HO-1 activity, as did cobalt protoporphyrin IX (1–3 μM) in J774 macrophages. In addition, cilostazol (1–30 μM) concentration-dependently reduced lipopolysaccharide (LPS)-mediated nitrite and TNF-α production, in accordance with the inhibition of LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression in the J774 macrophages, as did CoPP (1 μM). In parallel with these results, LPS-induced IκBα degradation and NF-κB nuclear translocation were significantly decreased after treatment with cilostazol as well as with CoPP. These effects of cilostazol and CoPP were significantly reversed by Zn protoporphyrin IX (ZnPP). The effects of cilostazol on IκBα expression and nitrite production were not manifested in the cells transfected with HO-1 small interfering RNA. In the J774 macrophages, cilostazol time (0–180 min)- and concentration (1–100 μM)-dependently increased the nuclear expression of NF-E2 related factor (Nrf2) and antioxidant response element (ARE) activity (3.70 ± 0.45 fold, P < 0.01). PI3-kinase and Akt play a role in the major signal pathways with cilostazol-induced HO-1 expression. In summary, cilostazol suppressed production of anti-inflammatory cytokines and molecules via inhibition of NF-κB activation, through a mechanism involving up-regulation of cyclic AMP-dependent protein kinase activation-coupled Nrf2-linked HO-1 expression in J774A.1 macrophages.