Detection of natural peptide antibiotics in human nasolacrimal ducts

PURPOSE. To determine the expression and production of antimicrobial peptid es by mucosal cells of the lacrimal passage in healthy and pathologic state s., METHODS. Detection of bactericidal-permeability-increasing protein (BPI), h eparin-binding protein (CAP37), human cationic antimicrobial protein (IL-37 ), human alpha -defensin 5 (HD5), human alpha -defensin 6 (HD6), human beta -defensin 1 (HBD-1), and human beta -defensin 2 (HBD-2) was performed by r everse transcription-polymerase chain reaction (RT-PCR). Intracellular depo sition of lysozyme, lactoferrin, secretory phospholipase A, human neutrophi l defensins (HNP-1, -2, and -3), human beta -defensin 1 (HBD-1), and human beta -defensin 2 (HBD-2) was analyzed immunohistochemically. Samples were o btained from 15 patients by surgery and from 10 cadavers. RESULTS. RT-PCR revealed BPI, CAP37, and HBD-1 mRNA in samples of healthy n asolacrimal duct epithelium. Additionally, HBD-2 mRNA was detected in epith elial samples from patients with dacryocystitis. Messenger RNAs for LL-37 a nd a-defensin 5 and 6 were absent in all samples investigated. Immunohistoc hemistry revealed lysozyme, lactoferrin, secretory phospholipase A(2), and HNP-1, -2, and -3 to be present in all samples, whereas HBD-1 was present o nly in some of the healthy and inflamed samples. Immunoreactive HBD-2 pepti de was visible only in some of the inflamed samples. CONCLUSIONS. The data suggest that the human efferent tear ducts produce a broad spectrum of antimicrobial peptides. Under inflammatory conditions, ch anges in the expression pattern occurred, revealing induction of the human inducible defensin HBD-2 and in some cases downregulation of HBD-1 and CAP3 7. Antimicrobial peptides have a therapeutic potential in dacryocystitis, i n that they have a broad spectrum of antimicrobial activity and accelerate epithelial healing. However, caution is appropriate, because defensins also promote fibrin formation and cell proliferation, which are key elements in scarring processes, such as dacryostenosis.