Arecoline promotes fibroblast activation and M2-macrophage polarization by up-regulating the expression of IL-4

To determine the biological effects of arecoline on oral submucous fibrosis (OSF).

The differential genes between OSF tissue and normal oral tissue were collected form GSE64216 dataset, analyzed by Gene Expression Omnibus (GEO) database. Real-time PCR and immunohistochemistry were used to analyze the expression of IL-4 gene and protein in oral tissue. Enzyme-linked immunosorbent assay (ELISA) was used to analyze the expression of exocrine IL-4 protein in human oral fibroblasts (HOF) pre-treated by arecoline. Cell Counting Kit-8 (CCK-8) and transwell assays were used to analyze the proliferation and migration of HOF cells, respectively. After IL-4 was knocked down by short hairpin (sh) plasmid, the proliferation and migration of HOF cells were detected. Flow cytometry was used to analyze the proportion of M2-macrophages. Real-time PCR and immunohistochemistry were used to verify the expression of biomarker proteins of macrophages in OSF tissues.

The expression of IL-4 gene and protein were both up-regulated in OSF tissue. Arecoline could enhance the expression of IL-4 gene and exocrine protein in HOF cells, and promote the proliferation and migration of HOF cells. While knockdown of IL-4 could inhibit arecoline-induced proliferation and migration in HOF cells. The results of flow cytometry showed that recombinant human IL-4 (rhIL-4) protein could increase the proportion of M2-macrophages. Similarly, the results of real-time PCR and immunohistochemistry showed the expression of ARG1 (Biomarker proteins of M2-macrophage) was up-regulated in OSF tissues.

Arecoline promotes activation of fibroblasts and polarization of M2-macrophages by up-regulating the expression of IL-4.