In vitro effects of acid and pepsin on mouse middle ear epithelial cell viability and MUC5B gene expression
Block, Bradley B; Kuo, Elaine; Zalzal, Habib G; Escobar, Hugo; Rose, Mary; Preciado, Diego
OBJECTIVE:To examine whether in vitro exposure of mouse middle ear epithelial cells (mMEECs) to conditions that mimic physiologic reflux upregulates Muc5b gene expression and alters cell viability. DESIGN/METHODS:In vitro mMEEC model. SETTING/METHODS:Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC. PARTICIPANTS/METHODS:Cells from the immortalized mMEEC line. MAIN OUTCOME MEASURES/METHODS:Cell viability, the quantity of Muc5b messenger RNA abundance, and Muc5b promoter activity. RESULTS:The 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide assays demonstrated an acidic dose-dependent decrease in cell survival, with pH less than 4 significantly decreasing viability at 1 hour. Pepsin had a mild protective effect up to 8 hours, with greater cell viability, in the pH range of 5.0 to 7.6. Reverse-transcriptase polymerase chain reaction demonstrated induction of Muc5b messenger RNA levels over controls after exposure to acidic pH levels of 5.7, and 4 with and without pepsin. Similarly, a pH of 4.0 significantly increased Muc5b promoter activation 5.4-fold. Pepsin at neutral or acidic pH values did not significantly alter Muc5b expression or promoter activity. CONCLUSIONS:Despite decreasing cell viability, acidic pH drives middle ear epithelial Muc5b gene expression in vitro, which perhaps explains how laryngopharyngeal reflux can contribute to otitis media. Pepsin at neutral or acidic pH levels had minimal effects on Muc5b gene expression; thus, although pepsin may be a useful marker for detecting the presence of reflux, our results suggest that acid itself is a more likely pathologic component of gastric juice in the middle ear.
Hoarseness in children: the role of laryngopharyngeal reflux
Block, Bradley B; Brodsky, Linda
OBJECTIVE:The role of laryngopharyngeal reflux (LPR) in hoarseness in children is not well studied. The purpose of this study was to determine the prevalence of LPR in hoarse children. METHODS:Retrospective chart review identified 337 children with hoarseness over a 3-year period. DATA COLLECTED/METHODS:mode of presentation, associated symptoms, endoscopic findings, laboratory testing, and therapeutic interventions and their outcomes. RESULTS:Mean age at presentation was 7.2+/-4.3 years with a male:female ratio of 1.7:1. Of the 295/337 (88%) children who underwent endoscopy, 107/295 (36%) had LPR changes alone, 86/295 (29%) had vocal fold nodules, 63/295 (20%) had both LPR and vocal fold nodules; and 22/295 (7%) had a finding other than LPR or nodules. Of the children diagnosed with LPR by endoscopy (with or without nodules), 93/170 (55%) underwent at least one additional test for reflux with 69/93 (74%) having a positive test. Of the children diagnosed with LPR by endoscopy, neither cough nor throat clearing was identified in 82/170 (48%) of children. At the first follow-up visit, an average of 3 months from initial presentation, 50% of 169 children who were treated for reflux had improved or resolved. By the second follow-up visit, 4.5 months later, 68% of those children had improved or resolved. CONCLUSIONS:LPR appears to be a very common cause of hoarseness in children, and is an increasingly important symptom in identifying children with LPR. Treatment of LPR often results in improvement of hoarseness.