Low-power laser irradiation inhibits arecoline-induced fibrosis: an in vitro study

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Oral submucous fibrosis (OSF) is a potentially malignant disorder that is characterized by a progressive fibrosis in the oral submucosa. Arecoline, an alkaloid compound of the areca nut, is reported to be a major aetiological factor in the development of OSF. Low-power laser irradiation (LPLI) has been reported to be beneficial in fibrosis prevention in different damaged organs. The aim of this study was to investigate the potential therapeutic effects of LPLI on arecoline-induced fibrosis. Arecoline-stimulated human gingival fibroblasts (HGFs) were treated with or without LPLI. The expression levels of the fibrotic marker genes alpha-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF/CCN2) were analysed by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) and western blots. In addition, the transcriptional activity of CCN2 was further determined by a reporter assay. The results indicated that arecoline increased the messenger RNA and protein expression of CCN2 and α-SMA in HGF. Interestingly, both LPLI and forskolin, an adenylyl cyclase activator, reduced the expression of arecoline-mediated fibrotic marker genes and inhibited the transcriptional activity of CCN2. Moreover, pretreatment with SQ22536, an adenylyl cyclase inhibitor, blocked LPLI’s inhibition of the expression of arecoline-mediated fibrotic marker genes. Our data suggest that LPLI may inhibit the expression of arecoline-mediated fibrotic marker genes via the cAMP signalling pathway. Low-power laser irradiation (LPLI) could treat a debilitating pre-malignant, fibrotic condition of the mouth. Most cases of oral submucous fibrosis (OSF) are in South Asia and are associated with areca nut chewing. The compound arecoline in the nut is thought to be involved in its development. Yan-Hsiung Wang, Huey-Er Lee and colleagues of Taiwan’s Kaohsiung Medical University tested the effects of LPLI on fibroblasts, cells producing connective tissue, from the human gum, which they stimulated with arecoline. Applying LPLI can activate a key cell-regulating enzyme, adenylyl cyclase, reduced the expression of fibrosis-related genes. LPLI’s effect was blocked when the cells were pretreated with an adenylyl cyclase inhibitor. LPLI may inhibit the effects of arecoline via adenylyl cyclase and could be used as an antifibrotic therapy in the future.