Dermcidin Expression in the Eye - Potential Protective Mechanisms Against Ocular Bacterial Invasion

Abstract

Purpose: : Dermcidin (DCD) is a recently discovered antimicrobial peptide (AMP) with no homology to other known AMPs. We have recently detected its presence in the aqueous humor of rabbits. Detection of peptides with antibacterial properties may lead to their further isolation as therapeutic agents. The purpose of this study was to analyze human eye explants to determine whether DCD could be detected in particular intraocular tissues.

Methods: : Normal eye, skin and prostate samples were obtained from Autopsy Pathology Division of Johns Hopkins Hospital from two healthy individuals (37 and 51 y-o). Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded 5-µm tissue sections of the human globe and skin, which were prepared and immediately processed, using a mouse monoclonal antibody raised against human DCD. In addition, reverse transcription-polymerase chain reaction (rt-PCR) experiments were carried out to determine whether DCD mRNA could be detected in corneal endothelium and ciliary body.

Results: : DCD was constitutively expressed in human sweat glands of all skin biopsies, and immunoreactivity was observed in human corneal endothelium and ciliary body. Human corneal endothelium and ciliary body express DCD gene constitutively.

Conclusions: : These results indicate that, unlike human cathelicidins and b-defensins which are inducible peptides that primarily function in response to injury and inflammation, DCD is part of the constitutive innate defense of human eye.

Keywords: immunohistochemistry • protective mechanisms • bacterial disease