Mechanism of Icariin in anti-inflammatory and immunomodulatory effects on THP-1 human monocytes
LIU Shuang,AN Hui-rong,ZHANG Jun-long
Abstract:
Objective To investigate the regulatory effects of Icariin (ICA) on lipopolysaccharide (LPS)-induced inflammatory response in THP-1 human monocytic cell line and its underlying mechanisms. Methods The safe concentration of ICA was screened using the CCK-8 method. Then THP-1 cells were divided into control, LPS(5 μg/mL), ICA(1000 nmol/L), and ICA+LPS(LPS added after ICA pretreatment for 1 h). The effects of ICA on phagocytic function (fluorescent latex beads), CCR2 chemokine receptor expression, and macrophage polarization markers (CD86/CD206) were evaluated by flow cytometry. qPCR and Western blot were used to analyze mRNA expression levels of pro-inflammatory cytokines (IL-6、IL-1β and TNF-α). Results The optimal concentration of ICA in this experimental system was determined to be 1000 nmol/L. The fluorescent latex bead phagocytosis assay showed that compared with the control group, the phagocytic capacity of monocytes was significantly increased after LPS stimulation for 24 h; compared with the LPS group, the phagocytic capacity was further significantly enhanced in the ICA+LPS group (P <0.05). Flow cytometry results revealed that compared with the control group, LPS stimulation upregulated the expression of CCR2 (indicating enhanced chemotactic ability) as well as CD86 and CD206 (indicating differentiation toward macrophages); compared with the LPS group, the ICA+LPS group significantly reversed the LPS-induced upregulation of CCR2, CD86, and CD206. qPCR and Western blot results demonstrated that compared with the control group, LPS stimulation markedly increased the mRNA and protein expression levels of IL-6, IL-1β, and TNF-α in monocytes; compared with the LPS group, the ICA+LPS group significantly reduced the expression levels of these pro-inflammatory cytokines (P <0.05). Conclusion ICA exerts anti-inflammatory effects by regulating monocyte phagocytosis, chemotaxis, and macrophage polarization. These experimental findings provide direct evidence for ICA′s potential anti-inflammatory therapeutic application in monocyte/macrophage-mediated inflammatory diseases, suggesting it could serve as a candidate drug to modulate monocyte/macrophage functions for further studies.
