This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Little, F. F. Articles by Cruikshank, W. W. Search for Related Content PubMed PubMed Citation Articles by Little, F. F. Articles by Cruikshank, W. W.

Tumor Necrosis Factor-–Induced Synthesis of Interleukin-16 in Airway Epithelial Cells

Priming for Serotonin Stimulation

Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts

Address correspondence to: Dr. Frédéric F. Little, Pulmonary Center R-304, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118. E-mail: flittle{at}lung.bumc.bu.edu

Epithelial cells from individuals with asthma or from allergen-sensitized mice contain intracellular interleukin (IL)-16 protein, not present in epithelial cells from individuals without asthma or unsensitized mice. IL-16 is only present in the bronchoalveolar lavage (BAL) fluid following airway challenge with either allergen or vasoactive amine. This suggests that the initial response to allergen (sensitization) results in synthesis but not secretion of IL-16. In this study, we investigated what factors produced during the sensitization phase are responsible for epithelial cell priming for IL-16 production. We determined that ovalbumin (OVA)-sensitized mice have an increase in systemic tumor necrosis factor- levels, and that serum or BAL fluid stimulation of bronchial epithelial cells results in production of IL-16 that is subsequently secreted only following serotonin stimulation. The mechanism for IL-16 production was shown to be caspase-3–dependent, and serotonin-induced secretion of IL-16 required binding of the serotonin type 2 receptor. The relevance of the priming effect associated with sensitization for IL-16 production and storage was confirmed in vivo by serotonin airway challenge of OVA-sensitized mice, resulting in rapid secretion of IL-16 into BAL fluid. As IL-16 has been shown to regulate CD4+ cell recruitment and activation, and is detected early following airway challenge of individuals with asthma, this two-step process for IL-16 production by epithelial cells may represent a rapid response mechanism in the orchestration of allergic airway inflammation.

Abbreviations: serotonin, 5-HT • antibody, Ab • bronchoalveolar lavage, BAL • bronchial epithelial cell, BEC • enzyme-linked immunosorbent assay, ELISA • interleukin, IL • ovalbumin, OVA • phosphate-buffered saline, PBS • regulated on activation, normal T-cell expressed and secreted, RANTES • T-helper 2, T_H2 • tumor necrosis factor-, TNF-