ABSTRACT
Otitis media is inammation of the mucosa lining of the middle ear and its integuments; this suggests that epithelial integrity is a factor in the course of otitis media. Vitamin A and their derivatives are required for the maintenance of the normal epithelial mucociliary phenotype and secretion of mucus. Vitamin A compounds exert their effects via specic nuclear receptors, retinoic acid receptors, and retinoid X receptors, all of which are members of the steroid/thyroid
Introduction ............................................................................................................ 141 Vitamin A and Pathogenesis of Otitis Media ......................................................... 141 Clinical Evidence Linking Vitamin A and Otitis Media ........................................ 142
Vitamin A and Predisposition to Nasopharyngeal Colonization ....................... 142 Vitamin A and Clinical Course of Otitis Media ................................................ 143
References .............................................................................................................. 145
receptor superfamily [10-14]. Physicochemical injuries alter the respiratory epithelium resulting in a multistep process to squamous metaplasia [15-17]. In vivo, vitamin A deciency has been found to induce replacement of the normal pseudostratied mucociliary epithelium by a metaplastic stratied squamous epithelium [18,19], a process that can be reversed by a dietary vitamin A supplement [20,21]. Vitamin A inhibits the expression of squamous-related genes, such as keratin 13 in rabbit tracheobronchial cells [22], cholesterol sulfate in human epithelial cells [23], and transglutaminase and cornin in human epidermal keratinocytes [24]. RA also induces a mucosecretory phenotype by activating both transcription of specic mucin genes, particularly MUC2, MUC5B, and MUC5AC, and mucin secretion [25,26]. All of these result in alteration of mucin secretion, which could be a factor in persistence of otorrhea and recurrent suppurative otitis media.
