Curcumin treatment suppresses CCR7 expression and the differentiation and migration of human circulating fibrocytes

Recent studies have demonstrated that circulating fibrocytes contribute to the formation and development of fibrosis. Curcumin, a polyphenolic compound isolated from turmeric, has been shown to have anti-fibrotic effects in various organs. We and others have demonstrated that curcumin beneficially affects the development of fibrosis. However the effect of curcumin on circulating fibrocytes has not been reported.

Human circulating fibrocytes were isolated from leukocyte concentrates of healthy human donors and identified based on the expression of CD34, CD45, collagen I (COLI), and chemokine receptor CCR7 (CCR7) via flow cytometry. Cell Counting Kit-8 was used to evaluate cell viability. The effect of curcumin on the differentiation and migration of human circulating fibrocytes was evaluated by immunofluorescence staining, flow cytometry and a transwell migration assay. Transforming growth factor (TGF)-β1 secretion was examined by ELISA.

Curcumin treatment (72 h; 20 μM) significantly decreased the expression of COL I, α-SMA and CCR7, as well as TGF-βl secretion, in human circulating fibrocytes. The inhibitory effect of curcumin on the differentiation and migration of human circulating fibrocytes is likely via regulating the CCR7/CCL21 signaling pathway, in particular by reducing CCR7 expression. These observed effects may be beneficial in resolving fibrosis by suppressing TGF-β1 secretion.

Our results suggest that curcumin has the potential to suppress the differentiation and migration of circulating fibrocytes, which would provide new explanation for curcumin's application in the development of fibrosis in various organs.