HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Reduced innervation in the human pharynx in patients with obstructive sleep apnea

Félix de Carlos1,2,*, Juan Cobo1,2,*, Emilio Macías2, Jorge Feito3,4, Mónica González5, Teresa Cobo2, María P. Fernández-Mondragón2, Olivia García-Suárez3 and José A. Vega3,6

Departments of 1Surgical Sciences and 3Morphology and Cell Biology, University of Oviedo, Spain, 2Instituto Asturiano de Odontología, Oviedo, Spain, 4Surgical Pathology Department, Asturias Central University Hospital, Oviedo, Spain, 5Sleep and Ventilation Unit, Marqués de Valdecilla University Hospital, Santander, Spain and 6Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Chile
*Both authors contributed equally to this paper

Offprint requests to: José A. Vega, MD, PhD, Departamento de Morfología y Biología Celular, Facultad de Medicina, Universidad de Oviedo, Avd Julián Clavería 6, 33006 Oviedo, Spain. e-mail: javega@uniovi.es


Summary. Obstructive sleep apnea is a disease characterized by repetitive breathing during sleep that lead to reduced oxygen saturation and sleep disturbance among other symptoms. Obstructive sleep apnea is caused by blockade of the upper respiratory airway, although the pathogenic mechanism underlying this occlusion remains unknown. In these studies we explored the hypothesis that alterations in the innervation, especially mechanosensory innervation, of the pharynx may contribute to obstructive sleep apnea. We tested this hypothesis by analyzing the innervation of the human pharynx in normal individuals and in subjects clinically diagnosed with obstructive sleep apnea. Using immunohistochemistry for axon and Schwann cells, as well as for two putative mechanoproteins (ASIC2 and TRPV4), we observed a significant reduction in the density of nerve fibers in the submucosa of patients with obstructive sleep apnea as well as morphological abnormalities in mechanosensory corpuscles. Importantly, while ASIC2 and TRPV4 expression was regularly found in the axons of mechanosensory corpuscles distributed throughout the muscular layer in the control subjects, it was absent in patients with obstructive sleep apnea. These findings support that neurological alterations are important contributors to the pathogenesis of obstructive sleep apnea. Histol Histopathol 30, 865-874 (2015)

Key words: Upper airways, Nerve fibres, Mechano-sensory innervation, Mechanoproteins

DOI: 10.14670/HH-11-593