Abstract
Activation of macrophages is a key event for the pathogenesis of various inflammatory diseases. Notch signaling pathway recently has been found to be a critical pathway in the activation of proinflammatory macrophages. Salidroside (Sal), one of main bioactive components in Rhodiola crenulata (Hook. F. et Thoms) H. ohba, reportedly possesses anti-inflammatory activity and ameliorates inflammation in alcohol-induced hepatic injury. However, whether Sal regulates the activation of proinflammatory macrophages through Notch signaling pathway remains unknown. The present study investigated the effects of Sal on macrophage activation and its possible mechanisms by using both alcohol and lipopolysaccharide (LPS) to mimic the microenvironment of alcoholic liver. Detection of THP-1-derived macrophages exhibited that Sal could significantly decrease the expression of tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β) and IL-6 in the macrophages at both mRNA and protein levels. Furthermore, Sal significantly suppressed NF-κB activation via Notch-Hes signaling pathway in a dose-dependent manner. Moreover, in the microenvironment of alcoholic liver, the expression of Notch-dependent pyruvate dehydrogenase phosphatase 1 (PDP1) was elevated, and that of M1 gene expression [inducible NO synthase (NOS2)] was up-regulated. These changes could all be effectively ameliorated by Sal. The aforementioned findings demonstrated that Sal could inhibit LPS-ethanol-induced activation of proinflammatory macrophages via Notch signaling pathway.