International Session 4 Head and Neck-Clinical 1

Objective: There is currently no treatment for fibrosis in swallowing-related muscle(SM)after irradiation, one of the causes for radiation associated dysphagia.We have previously demonstrated in vivo that vagus nerve stimulation might suppress SM fibrosis in mice after irradiation.The objective of this study is to elucidate this mechanism in vitro.Methods: We used previously established in vitro model of fibrosis induced by irradiation.First, a co-culture system of mouse embryonic fibroblasts and mouse macrophages was established.Second, nicotine, which is known to be able to mimic vagal electrical stimulation in vitro, was added to both wells, in combination with 30 Gy irradiation, one hour later after the treatment.Five days after irradiation, fibroblast was analyzed by immunofluorescence with anti-α-smooth muscle actin(αSMA)antibody and the amount of fluorescence was quantitatively compared to that in the control group (nicotine-free) .Results: There was a clear suppression of αSMA fluorescence in the nicotine-added group compared to the control.Conclusion: It was suggested that nicotine-stimulated macrophages may inhibit fibrosis of fibroblasts induced by irradiation.