Chronic low level complement activation within the eye is controlled by intraocular complement regulatory proteins

J. H. Sohn, H. J. Kaplan, H. J. Suk, P. S. Bora, N. S. Bora

Research output: Contribution to journalArticle

112 Scopus citations

Abstract

Purpose. To explore the role the complement system and complement regulatory proteins in an immune-privileged organ, the eye. Methods. Eyes of normal Lewis rats were analyzed for the expression of complement regulatory proteins, membrane cofactor protein (MCP), decay-acceleration factor (DAF), membrane inhibitor of reactive lysis (MIRL, CD59), and cell surface regulator of complement (Crry), using immunohistochemistry, Western blot analysis, and reverse transcription-polymerase chain reaction (RT-PCR). Zymosan, a known activator of the alternative pathway of complement system was injected into the anterior chamber of the eye of Lewis rats. Animals were also injected intracamerally with 5 μl (25 μg) of neutralizing monoclonal antibody (mAb) against rat Crry (512) or CD59 (6D1) in an attempt to develop antibody-induced anterior uveitis; control animals received 5 μl of sterile phosphate-buffered saline (PBS), OX-18 (25 μg), G-16-510E3 (25 μg), or MOPC-21 (25 μg). The role of complement system in antibody-induced uveitis was explored by intraperitoneal injection of 35 U cobra venom factor (CVF), 24 hours before antibody injection. Immunohistochemical staining and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with Western blot analysis were used to detect the presence of membrane attack complex (MAC) and C3 activation products, respectively, in normal and antibody-injected rat eyes. Results. Complement activation product MAC was present in the normal rat eye, and intraocular injection of zymosan induced severe anterior uveitis. The complement regulatory proteins, MCP, DAF, CD59, and Crry, were identified in the normal rat eye. Soluble forms of Crry and CD59 were also detected in normal rat aqueous humor. Severe anterior uveitis developed in Lewis rats injected with a neutralizing mAb against Crry, with increased formation of C3 split products. Systemic complement depletion by CVF prevented the induction of anterior uveitis by anti-Crry mAb. Intracameral injection of anti-rat CD59 (6D1), anti-rat MHC class I antigen (OX-18), anti-rat Ig (G-16-510E3), or MOPC-21 caused no inflammatory reaction. Conclusions. The results suggest that the complement system is continuously active at a low level eye and is tightly regulated by intraocular complement regulatory proteins.

Original languageEnglish (US)
Pages (from-to)3492-3502
Number of pages11
JournalInvestigative Ophthalmology and Visual Science
Volume41
Issue number11
StatePublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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