Anti-Inflammatory and Anti-oxidant Functions of Cornuside by Regulating NF-κ B, STAT-1, and Nrf2-HO-1 Pathways

Cornuside (CNS), found in the fruit of Cornus officinalis Seib, is a natural bisiridoid glucoside that possesses therapeutic effects by suppressing inflammation. This study aimed to determine whether CNS could inhibit the inflammatory response induced by lipopolysaccharide (LPS) in human umbilical vein endothelial cells (HUVECs) and mice, as well as to decipher the mechanisms. After activating HUVECs with LPS, the cells were treated with CNS. Cells were then isolated for protein or mRNA assays to analyze signaling and inflammatory molecules. In addition, mice received an intraperitoneal injection of LPS, followed by an intravenously administered dose of CNS. CNS inhibited cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) expressions induced by LPS. CNS decreased phosphorylated signal transducer and activator of transcription 1 (STAT1)-1 by promoting HO-1 expression, inhibiting nuclear factor (NF)-κB-luciferase activity, and decreasing COX-2/prostaglandin E2 (PGE2) and iNOS/NO. Furthermore, CNS treatment in LPS-activated HUVECs increased the nuclear translocation of nuclear factor erythrocyte 2-related factor 2 (Nrf2) and combined Nrf2 to anti-oxidant response elements and decreased IL-1β production. Reduced iNOS/NO expression by CNS was restored when HO-1 RNAi inhibited heme oxygenase-1 (HO-1). After CNS treatment in vivo, iNOS levels in lung tissue and tumor necrosis factor (TNF)-α expression in the bronchoalveolar lavage fluid were significantly decreased. The results indicated that CNS increased HO-1 expression, reduced LPS-activated NF-κB-luciferase activity, and inhibited iNOS/NO and COX-2/PGE2, all of which contributed to the inhibition of STAT-1 phosphorylation. Thus, CNS can be a potential new substance for treating inflammatory disorders.