Sensory purinergic receptor P2X3 is elevated in burning mouth syndrome

Recent studies show that P2X3 may play a role in neuropathic pain, including orofacial pain. Burning mouth syndrome (BMS) is a chronic neuropathic pain condition affecting 0.6–12% of post-menopausal women in the Western world. This study evaluates, for the first time, P2X3 immunoreactivity levels in lingual mucosa in BMS patients. Patients diagnosed with BMS (n = 9) in accordance with International Association for the Study of Pain criteria and patients attending for wisdom tooth removal (n = 10, controls), were involved in this study. A pain history and score was recorded on a visual analogue scale (VAS) prior to obtaining a lingual biopsy. Immunohistochemistry and image analysis were used to quantify submucosal nerve fibres expressing P2X3 and the structural marker neurofilaments. P2X3 positive fibres were significantly increased in BMS compared with controls (p = 0.024). In contrast, neurofilament-staining fibres were reduced in BMS, and when expressed as a ratio of the neurofilament percentage area, there was a trend for an increase of P2X3 positive fibres in the BMS group. Increased P2X3 immunoreactivity in the trigeminal sensory system may play a role in the symptoms observed in BMS. P2X3 may therefore be a therapeutic target for treating BMS and trigeminal neuropathic pain.