Expression and localization of TRPV1 in human nasal mucosa

Capsaicin is the pungent principle in chili peppers and previous studies reported that topical application of capsaicin to patients with allergic and non-allergic rhinitis produced significant and long-lasting relief of symptoms. The capsaicin receptor (TRPV1, VR1) is a nociceptive transducer and the existence of TRPV1 in non-neuronal cells as well as neuronal cells has been reported. In order to clarify the role of TRPV1 on the upper airway, we examined the localization and the expression of TRPV1 in human nasal mucosa. Surgically obtained human nasal specimens were processed for immunohistochemistry with commercial anti-TRPV1 antibody. We also performed immunofluorescence with anti-TRPV1 antibody and anti-neurofilament antibody or anti-CD31 antibody. Epithelial cells and vascular endothelial cells were cultured from nasal turbinates, respectively. For RT-PCR analysis, total RNA was isolated, and then RT-PCR was performed. Immunohistochemical studies revealed that TRPV1 positive cells were found on epithelial cells, vascular endothelial cells, submucosal glands and nerves in human nasal mucosa. By RT-PCR analysis, the mRNA expression of TRPV1 was confirmed in human nasal mucosa. These results suggest that capsaicin can directly influence the epithelial secretory and various functions via TRPV1 as well as the activation of the sensory neurons.