Mucosal expression of nerve growth factor and brain-derived neurotrophic factor in chronic rhinosinusitis

Allergic rhinitis (AR) is characterized in part by hyperresponsiveness to nonspecific stimuli, a phenomenon that reflects the fundamental role of nasal neural pathways in chronic airway inflammation. Neurotrophins may serve pivotal roles in mediating hyperresponsiveness in allergic airway disease, although the role of such neurogenic mediators in chronic rhinosinusitis (CRS) is not well understood. This study was designed to examine the expression of two potent neurotrophins, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), in CRS.

Inferior turbinate and sinus mucosa were obtained from CRS patients with and without nasal polyps (NPs) and from nonallergic controls. Enzyme-linked immunosorbent assay was used for quantitative determination of tissue concentrations of NGF and BDNF.

Ninety-four tissue samples from 48 patients were included. Mean concentration of NGF in sinus mucosa was significantly higher in CRS than controls. CRS without NPs was associated with a 60% increase in sinus NGF over controls (p < 0.05), and CRS with NPs was associated with a 140% increase (p < 0.05). Mean sinus NGF concentration was significantly elevated in allergic subjects compared with controls (p < 0.01). A similar trend was noted in subjects with nonallergic CRS, although this did not reach significance. Mean BDNF concentration was decreased in CRS compared with controls, with the most significant decrease in patients with polyps (p < 0.05). Mean turbinate concentration of both NGF and BDNF were similar in controls and CRS.

Increased expression of NGF may contribute to neural hyperresponsiveness in CRS sinus mucosa, particularly those patients with NP and/or allergies. BDNF expression is decreased in CRS sinus mucosa. Alterations in neurogenic inflammation may contribute to the pathophysiology of CRS and provide alternative therapeutic targets.