Therapeutic Induction of Interleukin-10 by Theophylline Administration for the Treatment of Hyposmia

Objective: To determine changes in nasal mucus Interleukin-10 (IL-10) before and after theophylline treatment in hyposmic patients, related to changes in age and diagnoses.

Design: IL-10 was measured in nasal mucus samples of 17 normal subjects and 36 patients with hyposmia of multiple etiologies by use of a sensitive spectrophotometric ELISA assay. Hyposmia is defined clinically by standardized evaluation of impaired gustometry and olfactometry, as well as subjectively self reported by the patient.

Results: Prior to treatment, IL-10 levels in nasal mucus was increased in hyposmic patients compared to controls. Following theophylline administration, IL-10 in hyposmic patients’ nasal mucus increased further, correlating with improved subjective taste and smell function. Epithelial IL-10 in the nasal secretions increased linearly with the dosage of theophylline.

Conclusion: Nasal mucus IL-10 increases after theophylline treatment, consistent with IL-10 acting as a taste bud growth co-factor which reduces inflammation locally to maintain the structural integrity of olfactory and taste bud receptors. Measurements of nasal mucus IL-10 provide an important marker for the presence of taste and smell dysfunction and their improvement with theophylline treatment, as well as their return to cytokine homeostasis once the dysfunction is normalized.

Keywords: Hyposmia; Hypogeusia; IL-10; Interleukin-10; Theophylline; Inflammation; Nasal mucus; Nasal secretion