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B. Ovodenko, A. Rostagno, J.M. Liebmann, L.M. Bley, M.A. Jofe, R.M. Smolyak, D. Pinhas, J.A. Ghiso, R. Ritch; Complement Activation in Exfoliation Syndrome . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3763.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To identify components of exfoliation material (XFM) in eyes with XFS Methods: Anterior lens capsules from patients with and without XFS were divided into two groups, homogenized in formic acid, and subjected to cyanogen bromide (CNBr). Aliquots of resultant peptides were separated on SDS–PAGE and silver stained. Differentially stained bands were excised from the gel, digested with trypsin, and sequenced using Quadrupole Time–of–Flight mass spectrometry (Q–TOF MS). The resultant deconvoluted MS/MS spectra were directly used to search the NCBI nonredundant protein database using the Mascot search program (Matrix Science, UK). The remainder of CNBr–fragmented material was digested with either trypsin or elastase and analyzed with liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). The resultant MS/MS spectra were analyzed by Bioworks 3.1 (Thermo Finnigan, USA) utilizing the SEQUEST database. Immunohistochemical analysis for the components of the complement pathways was performed in XFS vs. control samples using conventional horseradish peroxidase–based immunohistochemistry. Results:Both biochemical approaches yielded similar results. Specifically, components involved in inhibition of complement activation (e.g., clusterin and vitronectin) were identified. Immunohistochemistry revealed very strong staining of XFM with anti–clusterin antibody and moderate staining with antibodies against normal components and activation products of the classical complement pathway: C1q, C3c, and C4c. In the samples examined, there was no staining of XFM with anti–apolipoprotein–E, anti–Bb, and anti–C5b–9 antibodies. Conclusions: Deposition of normal components and activation products of the classical complement pathway in XFM could be due to ocular ischemia and/or inflammatory process. Clusterin, a ubiquitous extracellular protein, is found in a wide variety of lesions and has multiple functions, such as protection against apoptosis and oxidative stress, inhibition of the membrane attack complex of complement proteins, and inhibition of amyloid aggregation. The apparently great abundance of clusterin in XFM, along with the presence of complement activation products is intriguing and warrants further study. Complement inhibition should be investigated as a potential therapy for mitigating cytotoxicity in the anterior segment in XFS.
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