Study of the protease dipeptidyl peptidase IV in the nasal mucosa

Introduction: The endothelial serine protease dipeptidyl peptidase IV (DPP IV) cleaves the tyrosin-prolin dipeptide of several inflammatory mediators and neuropeptides, including neuropeptide Y (NPY), yielding the endogenous Y2-receptor agonist NPY (3-36) which modulates sensory and parasympathetic nerve activity. The aims of the study were to investigate the localisation of DPP IV in human nasal mucosa and to measure in vitro activity of DPP IV in nasal mucosa biopsies from patients suffering from chronic rhinosinusiti s. Patients and methods: Using immunohistochemistry we have studied the locali sation of DPP IV in human nasal biopsies. The activity of DPP IV was measur ed in vitro in nasal mucosa samples obtained from 45 patients suffering fro m chronic rhinosinusitis and compared with the density of inflammatory cell infiltration. Results: Positive immunoreactivity for DPP IV was observed in the human nas al mucosa. Low activity of DPP IV was associated with high density of infla mmatory cells in the mucosa of patients suffering from chronic rhinosinusit is. The regressive correlation was statistically significant (p <0.001). Conclusion: Low level DPP IV activity is associated with inflammation of th e nasal mucosa. This enzyme may be involved in the pathophysiological mecha nism of nasal hyperreactivity and chronic rhinosinusitis.