title: Clusterin and complement activation in exfoliation glaucoma.
abstract: OBJECTIVE
  The study was done to better understand the biological significance of clusterin co-localization with the exfoliation deposits (XF deposits), and provide insight into a pathogenic mechanism involving activation of the complement system and its pro-inflammatory consequences in patients with exfoliation glaucoma.
  
  
  METHODS
  Exfoliation lens deposits were analyzed by high resolution atomic force microscopy imaging and confocal immunofluorescence. Levels of clusterin and vitronectin, as well as of the complement activation products C3a and soluble C5b-9, were assessed via ELISA.
  
  
  RESULTS
  Atomic-force microscopy examination of lenses with exfoliation syndrome (XFS) revealed a dense fibrillar network on the anterior, aqueous-bathed surface of the lens, while the epithelial side displayed no discernible structural features at the same resolution. Clusterin colocalized with XF deposits, demonstrating integral association with the fibrils. Levels of activation-derived complement components C3a and soluble C5b-9, as well as the complement inhibitors clusterin and vitronectin, were found significantly elevated (1.7-fold, P < 0.05; 4.1-fold, P < 0.05; 1.8-fold, P < 0.01; and 3.0-fold, P < 0.01, respectively) in aqueous humor from glaucoma patients with XFS compared to non-XFS glaucoma controls.
  
  
  CONCLUSIONS
  The data provide compelling evidence for the activation of the complement system in XFS, highlighting the generation of subproducts with potent proinflammatory activity, which are capable of triggering and chronically maintaining levels of subclinical inflammation, suggesting novel targets for therapeutic intervention. The colocalization of clusterin in exfoliation fibrils suggests a failed attempt to prevent tissue accumulation of protein aggregates, as seen in other protein folding disorders, likely due to the abnormal high levels of misfolded proteins overwhelming its chaperone capacity.
authors.affiliation: Department of Pathology, New York University School of Medicine, New York, New York, United States.
authors.forename: Ivo
authors.initials: I
authors.lastname: Doudevski
authors.forename: Agueda
authors.initials: A
authors.lastname: Rostagno
authors.forename: Mary
authors.initials: M
authors.lastname: Cowman
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Liebmann
authors.forename: Robert
authors.initials: R
authors.lastname: Ritch
authors.forename: Jorge
authors.initials: J
authors.lastname: Ghiso
mesh_terms: D001082:Aqueous Humor / Q000378:metabolism*; D051152:Clusterin / Q000378:metabolism*; D003167:Complement Activation / Q000502:physiology*; D003176:Complement C3 / Q000378:metabolism*; D015938:Complement Membrane Attack Complex / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D017889:Exfoliation Syndrome / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D006801:Humans; D007903:Lens Capsule, Crystalline / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism
chemical_list: D051152:Clusterin; D003176:Complement C3; D015938:Complement Membrane Attack Complex; D018832:Molecular Chaperones
keywords: complement system; exfoliation syndrome; extracellular chaperones; protein misfolding disorders