Expression of Cathelin-Related Antimicrobial Peptide in the Eustachian Tube Epithelium of Mouse

Chae, Sung Won; Kim, Dae Hyung; Cho, Jae Gu; Park, Il Ho; Jung, Hak Hyun; Hwang, Soon Jae

Abstract

BACKGROUND AND OBJECTIVES
Antimicrobial peptides and proteins play an important role in innate host defense, and this may be particularly important at mucosal surfaces that form the initial barrier between the host and the external environment. Epithelial cells are the first line of defense mechanism against microorganisms, where antimicrobial peptides are the major participants. Cathelicidins are the precursors of potent antimicrobial peptides that have been identified in several mammalian species. Cathelin-related antimicrobial peptide (CRAMP) is one of the antimicrobial peptides and is the only member of cathelicidin family identified so far in mouse. The present study was undertaken to investigate the expression of CRAMP in the eustachian tube epithelium of mouse. MATERIALS AND METHOD: Tissue samples from the mouse eustachian tube were recovered from its pharyngeal, middle, and distal segments. CRAMP was localized by immunohistochemical staining and mRNA expression was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: By immunohistochemical study, CRAMP was detected in epithelial cells and submucosal glands of the eustachian tube, but not in the negative control. Using RT-PCR, CRAMP mRNA was detected in the eustachian tube epithelium. CONCLUSION: The expression and localization of CRAMP in the epithelial cells and submucosal glands of the eustachian tube of mouse were defined. We found that CRAMP is one of the antimicrobial peptides found in the eustachian tube epithelium of mouse, and that it participates in the innate immune system of the eustachian tube.