ARECA NUT EXTRACT ENHANCED M2-LIKE MACROPHAGE POLARIZATION AND fiBROBLAST ACTIVATION

Abstract

Objectives Areca nut chewing habit is popular in Taiwan and is closely related to oral squamous cell carcinoma (OSCC). Both activated fibroblasts expressing alpha-smooth muscle actin (α-SMA) and tumor-associated macrophages showing M2 polarization in stroma are supposed to be crucial in tumor progression. The purpose of the study was to examine the profile of stromal fibroblasts and macrophages in areca-associated oral cancer tissues, thein viro effects of areca nut extract (ANE) and two common oral insults, nicotine (NT) and lipopolysaccharides (LPS), on primary oral fibroblasts and human macrophages were also investigated. The study was approved by institutional Review Board of Taipei Veterans General Hospital, Taipei, Taiwan. Oral tissues were obtained with informed consent from patients undergoing routine surgical treatment. Findings Tissue sections showed that compared to the tumor-adjacent normal tissues (ANT), OSCC revealed a higher expression of pan-macrophage marker CD68, M2 markers CD163 and arginase-1 and activated fibroblast marker α-SMA, but not M1 marker CD86. In in vitro cell experiments, all of ANE, NT and/or LPS treatments could increase α-SMA expression and collagen production by oral fibroblasts. But only ANE treatment group, not NT or LPS group, enhanced the expression of M2 marker arginase-1 by macrophages. Furthermore, conditioned media acquired from macrophages (CM-Mac) of ANE treatment group increased the collagen production and IL-6 secretion by fibroblasts. CM-Mac of LPS treatment group also increased IL-6 secretion. Taken together, fibroblasts could be activated by ANE, NT and LPS, but only ANE could enhance macrophage M2-like polarization which in turn further increased fibroblast protein production. Conclusions Areca nut might compromise oral health by the setup of tumor-promoting microenvironment with local immune dysregulation via the enrichment of activated fibroblasts and M2-like macrophages.