Background and Objectives : Epithelial cells are the first line of defense in the innate immune system against microorganisms. The antimicrobial peptides are major participants in this system. LL-37, a kind of antimicrobial peptide, is the only
cathelicidin protein so far identified in humans. Since the level of the peptide is known to increase in inflamed areas, we tried to find the correlation of the peptide with inflammation nasal mucosa by examining the expression level of LL-37.
Furthermore, we determined the mRNA expression level of IL-1β and IL-8, both of which are known to be involved in inflammation. Materials and Methods : Nasal mucosa specimens were obtained from nasal polyps, chronic infective rhinitis, and
normal
inferior turbinate mucosa. The LL-37 protein was localized by immunohistochemical staining and mRNA expression of LL-37, IL-1β, IL-8 were determined by reverse transcriptase polymerase chain reaction (RT-PCR). Results : In immunohistochemical
study,
LL-37 immunoreactive cells were primarily localized in the surface epithelia, the serous and mucous cells of the submucosal glands, and some stromal inflammatory cells. In normal tissue, 2 out of 6 samples (33%) studied exhibited immunoreactivity
against LL-37 antibody, but in nasal polyps, 5 out of 8 (63%) and in infective rhinitis, 6 out of 7 (85%) showed positive reaction to the antibody. The number of positive cells were increased in inflammatory specimens, but there was no
statistical
difference between the normal and inflammatory specimens in epithelial layer, submucosal gland, and stromal inflammatory cells (p<0.05). In RT-PCR, LL-37 mRNA was detected in three of the six normal turbinate samples, but in all fifteen cases of
inflammatory nasal tissues. The expression of LL-37 mRNA was correlated with the proinflammatory cytokines, IL-1β and IL-8 mRNA. Conclusions : Our results suggest that LL-37 is one of antimicrobial peptides found in the human nasal mucosa, and
participates in the innate immune system of the nasal mucosa.
|