Arecoline stimulates the IL-33/13 axis and upregulates pro-fibrotic CTGF: A possible role in oral submucous fibrosis.

Areca nut chewing is a culturally significant practice shown to cause Oral Submucous Fibrosis (OSMF), which has a high potential for morbidity and malignancy. We postulate that arecoline upregulates production of pro-fibrotic cytokines, IL-33 and IL-13 and aimed to assess both IL-33/IL-13 expression and extracellularisation during arecoline treatment in human gingival fibroblasts (HGF) and mast cells, respectively. Primary HGF cells were exposed to increasing concentrations of arecoline (0 μg/mL, 25 μg/mL, 50 μg/mL, 100 μg/mL, 200 μg/mL) under serum starvation conditions for 16 h. Co-culture transwell systems were used to examine arecoline-induced synergic activation of mast cells. We observed that 100 μg/mL and 200 μg/mL of arecoline is sufficient to induce significant levels of cell toxicity and death, with concurrent release of both pro-fibrotic factor, CTGF and IL-33 from HGF cells and IL-13 from mast cells. We are the first to report that arecoline induces release of IL-13, mast cell degranulation, and increased soluble CTGF. In conclusion, arecoline induces IL-33, IL-13 and CTGF release in HGF and mast cells, highlighting the importance of the IL-33/IL-13 axis in the progressive fibrosis of OSMF. These findings could support the approach of novel therapies targeting the IL-33/IL-13 axis for patients with OSMF.