Expression of SLPI in Ocular Host Defense Against S. Aureus Endophthalmitis and Herpes Simplex Virus Keratitis

Abstract

Abstract: : Purpose: Secretory leukocyte protease inhibitor (SLPI) is an antimicrobial protein. Staphylococcus and herpes simplex virus are leading causes of potentially blinding microbial disease. In this study we investigated whether Staphylococcus aureus or HSV infection could induce expression of SLPI in ocular tissues. Methods: An HSV keratitis mouse model (right eye) was developed in forthy BALB/c mice using KOS strains. Endophthalmitis was induced in forthy Lewis rats by intravitreal injection (right eye) of colony–forming units of viable S. aureus. Twenty–four hours post–infection, the animals were sacrificed. Corneal & retinal tissues were excised and processed for histopathology, immunohistochemical staining and Western blot assay studies to determine the site of SLPI production. Results: Our initial studies established that SLPI is expressed abundantly in the cornea after HSV–1 infection. Also, SLPI was detected in endophthalmitis vitreous samples at increased levels. The SLPI expression in retinal tissue was primarily associated with leukocytic inflammatory infiltration. Conclusions: Eyes infected with S. aureus or HSV demonstrated an intense expression of SLPI compared with normal control eyes. These results suggest that SLPI may have an antimicrobial function, promoting up–regulation of local eye innate immunity.

Keywords: inflammation • endophthalmitis • cornea: basic science