Mucin gene expression in human laryngeal epithelia: effect of laryngopharyngeal reflux.

OBJECTIVES

We sought to document the mucin gene profile in normal human laryngeal epithelium and compare it with that in patients with reflux-attributed laryngeal injury or disease. We also investigated the effect of low pH with or without pepsin on mucin messenger RNA levels in vitro.

METHODS

Laryngeal biopsy specimens were obtained from 3 patients with clinically diagnosed laryngopharyngeal reflux and from 2 control subjects who had no signs or symptoms of reflux. Signs and symptoms were assessed by the Reflux Finding Score and the Reflux Symptom Index, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to establish the mucin gene profile. Human hypopharyngeal epithelial cells were exposed to pH 7, 5, 4, and 2 with and without pepsin (0.1 mg/mL) for 20 minutes at 37 degrees C, and expression of selected mucins was analyzed via real-time RT-PCR.

RESULTS

Mucin 1-5, 7, 9, 13, 15, 16, and 18-20 transcripts were detected in normal laryngeal epithelium, whereas mucin 6, 8, and 17 transcripts were not. Mucins 2, 3, and 5 were expressed at reduced levels in patients with reflux-attributed laryngeal injury or disease. These mucin genes were up-regulated after exposure to low pH in vitro (p < 0.005). Pepsin inhibited this up-regulation (p <0.001).

CONCLUSIONS

Reflux laryngitis is associated with down-regulation of mucin gene expression.