A novel antimicrobial peptide on the ocular surface shows decreased expression in inflammation and infection.
OBJECTIVE
Antimicrobial peptides (AMPs) are cationic host defense peptides with microbicidal and cell-signaling properties. They show promise as potential therapeutic agents. In the present study, a beta-defensin AMP gene was isolated from the ocular surface for the first time, and its expression was characterized in the presence of ocular inflammation and/or infection.


METHODS
Total RNA was obtained from impression cytology samples of the conjunctiva and cornea of normal patients and of those with bacterial, viral, acanthamoeba, or dry eye disease. The expression of the beta-defensin AMP DEFB-109 was determined by using reverse transcription-polymerase chain reaction (RT-PCR). Relative quantification of the gene in the various groups was performed by means of real-time PCR.


RESULTS
DEFB-109 was constitutively expressed in all samples. The gene showed significantly decreased expression in the presence of all types of inflammation/infection. Reduced expression featured most prominently in acanthamoeba infection; the least change from normal was in dry eye.


CONCLUSIONS
The discovery of DEFB-109 on the ocular surface enhances our knowledge of the profile of AMPs at this important mucosal surface. The fact that its expression is significantly reduced in both inflammatory and infective ocular surface disease reflects not only an intimate balance between this host defense gene and microbes but indicates a role other than purely microbicidal. This discovery will enable the mechanisms behind the intriguing phenomenon of reduced gene expression of an AMP in disease states to be uncovered.
Abedin
Asiya
A
Larry A. Donoso Laboratory for Eye Research, Academic Division of Ophthalmology, University of Nottingham, Nottingham, United Kingdom.
Mohammed
Imran
I
Hopkinson
Andrew
A
Dua
Harminder S
HS
D015823:Acanthamoeba Keratitis / Q000235:genetics* / Q000378:metabolism; D000890:Anti-Infective Agents / Q000378:metabolism*; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D003228:Conjunctiva / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D015352:Dry Eye Syndromes / Q000235:genetics / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D015817:Eye Infections / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023083:beta-Defensins / Q000096:biosynthesis / Q000235:genetics*
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; C526629:DEFB-109 peptide, human; D012333:RNA, Messenger; D023083:beta-Defensins