Leukotriene Pathway may Serve as Target to Block Tonsillar Growth in Children

Are there medical treatment options for children with large tonsils and adenoids leading to obstructive sleep apnea?

Background: Large tonsils and adenoids in children lead to increased airway resistance and sometimes obstructive sleep apnea (OSA). Leukotrienes have been implicated in the molecular pathways leading to the proliferation of tonsillar T and small B lymphocytes. In fat administration of montelukast, a leukotriene inhibitor has been shown to decrease adenoid size and severity of intermittent airway obstruction during sleep. Though this is a clinically attractive hypothesis, the key molecular players in leukotriene synthesis have not been definitely identified within tonsillar tissue.

Study design: Prospective, nonrandomized study at a tertiary care university hospital. Thirteen children with OSA and adenotonsillar hypertrophy undergoing adenotonsillectomy and 12 children without OSA undergoing adenotonsillectomy for recurrent tonsillitis (RT) were recruited to the study. Tonsillar tissues from these patients were examined for the level of expression of several genes in the leukotriene biosynthesis pathway (5-LO, FLAP, LTC4S). Furthermore, the proportion of T-cells and B-cells that expressed these genes were also analyzed.

Setting: Tertiary care academic hospital.

Synopsis: Patients recruited to the study underwent a thorough physical exam. OSA was diagnosed when symptoms of sleep-related breathing disorder (SRBD) were present and the apnea-

hypopnea index in polysomnogram was greater than one episode per hour. Children in the recurrent tonsillitis group had a diagnosis of seven or more bouts of tonsillitis in the prior year and a SRBD score lower than 0.33 by the pediatric sleep questionnaire. All four enzymes were detected in T and B lymphocytes from both the OSA and RT group; however, a higher proportion of the T and B in tonsils from the OSA group expressed LTC4S, compared with the tonsils from the RT group.

Bottom line: This study adds to the accumulating evidence that leukotrienes are present in tonsillar tissue and are endogenously produced. Therefore, the leukotriene pathway may serve as a target to block tonsillar growth in children.

Citation: Tsaoussoglou M, Hatzinikolaou S, Baltatzis GE, et al. Expression of leukotriene biosynthetic enzymes in tonsillar tissue of children with obstructive sleep apnea: a prospective nonrandomized study [published online ahead of print September 11, 2014]. JAMA Otolaryngol Head Neck Surg. doi: 10.1001/jamaoto.2014.1936.

—Ravindhra G. Elluru, MD, PhD