Toll Like Receptors in the Larynx: Implications for Laryngeal Immunology.

RATIONALE: Although optimal epithelial barrier function is essential to laryngeal health and disease, there is a surprising paucity of literature on the underlying immunological mechanisms in laryngeal epithelia. Toll like receptors (TLR) are a class of pattern-recognition receptor (PRR) proteins that are essential for regulating the innate and adaptive immune response in mucosal epithelia. Identifying the presence of TLR receptors in laryngeal epithelia and delineating their role in laryngeal inflammation will contribute to our understanding of innate and adaptive immune responses in the vocal fold mucosa. OBJECTIVE: (1) To delineate TLR expression in human and murine vocal fold epithelium, (2) to elucidate the mechanisms of TLR-dependent inflammation in primary human vocal fold epithelial cell cultures. METHODS: In our first experiment, we histologically characterized normal TLR 1-9 expression in human and murine laryngeal epithelium. In our second experiment, we quantified transcript expression of TLR 1-9 and IL8 in primary human vocal fold epithelial cell cultures, incubated with and without LPS. RESULTS: TLR were identified in the murine and human vocal fold epithelium with slight differences in localization from true to false vocal folds in humans. In primary human vocal fold epithelial cell cultures, there was a significant increase in relative gene expression at 24 h for TLRs 2, 3, and 6, as well as IL8 with LPS stimulation. CONCLUSIONS: This is the first study to identify the presence of TLR receptors in the human and murine vocal fold epithelium. These data lay the groundwork for delineating the role of TLR in the laryngeal immune response in both healthy and pathological states. LEVEL OF EVIDENCE: NA.