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F. Garreis, M. Gottschalt, R. Gläser, J. Harder, D. Worlitzsch, F. P. Paulsen; Expression and Regulation of Antimicrobial Peptide Psoriasin (S100A7) in the Lacrimal Apparatus. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5515.
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Psoriasin, originally isolated as an overexpressed molecule of unknown function from psoriasis, has recently been identified as a principal Escherichia coli-killing antimicrobial peptide of healthy skin. The aim of this study was to investigate the possible expression and antimicrobial role of psoriasin at the ocular surface and in the lacrimal apparatus.
Different tissues of the lacrimal apparatus and ocular surface were systematically analysed by means of RT-PCR, Western blot and immunohistochemistry for their ability to express and produce psoriasin. Inducibility and regulation of psoriasin were studied in human corneal (Araki-Sasaki cell line, HCE) and conjunctival epithelial (IOBA-NHC, HCjE) cell lines as well as in a sebocyte (SC) cell line after challenge with frequent ocular pathogens and proinflammatory cytokines. Real-time PCR and ELISA experiments were performed to evaluate the expression and induction of psoriasin. Additionally, we examined tear fluid obtained from different healthy volunteers for its psoriasin concentration by ELISA.
RT-PCR and Western blot analyses revealed a constitutive expression of psoriasin in cornea, conjunctiva and nasolacrimal ducts but not in the human lacrimal gland. Immunohistochemistry revealed strong staining of Meibomian glands for psoriasin and somewhat weaker immunoreactivity in the epithelium of conjunctiva and around the hair follicles of the lid. No induction of psoriasin was observed after stimulation with supernatants of E. coli whereas supernatants of Staphylococcus aureus and Haemophilus influenzae significantly increased the psoriasin mRNA and protein expression. Stimulation with IL-1β and VEGF also strongly increased the psoriasin transcription. Highest amounts of psoriasin were detected in tear fluid (~170 ng/ml) of healthy volunteers.
Our results suggest that psoriasin is produced by the structures of the ocular surface and is part of the innate immune system at the ocular surface and tear film. Current work adresses the question whether psoriasin has a regulatory function in the (anti)angiogenesis at the ocular surface.
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