Abstract
Abstract: :
Purpose: LL-37/hCAP18 (Cathelicdin) is an antimicrobial peptide with broad activity against Gram+ve and -ve bacteria, and fungi. The purpose of this study was to examine the expression of LL-37/hCAP18 in the human corneal epithelium and to determine if conditions such as injury or inflammation modulate its expression. Methods: Human corneas were obtained from an eyebank. Superficial wounds were created by scraping away the epithelium (original epithelial samples) leaving an 1-2mm ring of cells intact around the limbus. The wounded corneas were allowed to re-epithelialise in a serum-free culture environment and 48 hours later, the re-grown epithelium was collected by scraping (re-grown epithelial samples). RNA was extracted and RT-PCR was performed using specific primers for LL-37/hCAP18 and ß-actin. Primary cultured human corneal epithelial cells (HCEC) were treated with 10ng/ml IL-1ß for 30-180min. Cells treated with serum-free culture media acted as controls. At the end of the incubation the culture media was collected and the cells harvested. RT-PCR was performed to detect LL-37/hCAP18 mRNA expression. Immunoblotting was performed to detect LL-37/hCAP18 peptide. Results: All original epithelial samples (n=6) expressed a low level of LL-37/hCAP18 mRNA. All re-grown epithelial samples (n=6) also showed LL-37/hCAP18 mRNA expression and this was upregulated approximately 2.4 fold (p>0.004) compared to the original samples. Untreated HECE also weakly expressed LL-37/hCAP18 mRNA. IL-1ß rapidly (30min) stimulated upregulation of LL-37/hCAP18 mRNA expression in HCEC in a time dependent manner (n=4). IL-1ß also stimulated LL-37/hCAP18 protein production by HCEC and this was strongly detected by 3hrs (n=2). Conclusions: Our data show that LL-37/hCAP18 mRNA and protein are produced by the corneal epithelium, and their expression is increased during wound healing and conditions mimicking inflammation. Thus, LL-37/hCAP18 is another member of the growing family of antimicrobial peptides present at the ocular surface to help protect the cornea from infection.
Keywords: cornea: epithelium • cornea: basic science • wound healing