Inhibition of SIRT1 promotes taste bud stem cell survival and mitigates radiation-induced oral mucositis in mice

Taste loss is one of the debilitating complications in radiation-induced oral mucositis (RIOM), as occurs in head and neck cancer patients undergoing radiotherapy. We report here a radio-mitigation effect of Sirtuin 1 (SIRT1) inhibitors in taste bud organoids and a mouse model of radiation-induced taste bud injury. The organoids, developed from circumvallate (CV) papilla, were irradiated with single dose of X-rays and inhibitors of SIRT1 or SIRT2 were added 24 h later. The survival was evaluated by measuring the number and size of regenerated organoids after irradiation (IR). Oral mucositis (OM) was induced by IR of the oral region of Lgr5-lacZ transgenic mice. The surviving Lgr5+ taste bud stem cells were identified after lacZ-staining and the mucosal ulceration on tongue dorsal surface was determined by histological methods. Results showed that SIRT1 inhibitors (nicotinamide, EX527, salermide and sirtinol), but not SIRT2 inhibitors, significantly improve taste bud organoid survival after IR. Remarkably, administration of nicotinamide (NAM), a recognized inhibitor of SIRT1 to mice 24 h after IR promotes the survival of Lgr5+ taste bud stem cells, resulting in alleviated tongue mucositis. In conclusion, SIRT1 inhibitors promote Lgr5+ taste bud stem cell survival and mitigate RIOM in mice. These observations have important implications for efforts to develop therapeutic strategies against taste dysfunction and mucosal ulceration in RIOM.