Nasal Pathology and infrastructure in Patients with Chronic Airway Inflammation (RADS and RUDS) Following an Irritant Exposure

Abstract

Background: Reactive airways dysfunction syndrome is a chronic asthma-like condition developing after an acute irritant exposure, and chronic inflammation has been seen on endobronchial biopsy. Reactive upper-airways dysfunction syndrome is chronic rhinitis developing in temporal association with a toxic inhalation exposure, but the pathophysiology is unknown. Objectives: To study biopsies of the nasal mucosa in patients with reactive upper-airways dysfunction syndrome and in some cases reactive airways dysfunction syndrome developing in temporal association with a chlorine dioxide exposure, to see if a histologic basis for the persistent rhinitis and sensitivity to chemical irritants could be determined. Methods: Specimens were stained with hematoxylin-eosin and immunoperoxidase stains for substance P, vasointestinal peptide, and S-100 (nerve fibers), and fixed in glutaraldehydefor electron microscopy. Biopsies of three nonexposed subjects were performed for comparison. A pathologist blinded to clinical data interpreted the specimens. Results: Inflammation ratings of exposed individuals were higher than for the nonexposed individuals. The number of nerve fibers stained was greater for patients vs controls. Substance P and vasointestinal peptide staining was nonspecific. Electron microscopy showed desquamation of the epithelium and permeability of epithelial cell junctions. Conclusion: This study suggests a mechanism by which ongoing low level exposures perpetuate airway inflammation after an inducing toxic inhalation. A possible overlap between reactive airways dysfunction syndrome, reactive upper-airway dysfunction syndrome and the multiple chemical sensitivity syndrome is suggested.