title: Disturbed matrix metalloproteinase activity of Bruch's membrane in age-related macular degeneration.
abstract: OBJECTIVE
  To evaluate the potential role of the matrix metalloproteinase (MMP) system of Bruch's membrane in the pathology of age-related macular degeneration.
  
  
  METHODS
  Free and bound pools of gelatinase activity in Bruch's membrane-choroid preparations were isolated by phosphate-buffered saline (PBS) and sodium dodecyl sulfate (SDS) extraction, respectively. Individual MMP species were separated by gelatin-substrate zymography and the levels were quantified by densitometric techniques. Altogether, 13 control (age range, 71-99 years) and 6 AMD (age range, 71-95 years) donor eyes were used.
  
  
  RESULTS
  All the gelatinase components normally present in control samples were also present in AMD tissue without any significant differences in their molecular masses. Total levels (bound plus free) of active MMP2 and -9 were significantly reduced in AMD donors (P < 0.05). The decrease in active MMP2 may be attributable to a similar reduction in the level of free pro-MMP2, the precursor to the active form. Reduction in active MMP9 occurred despite a nearly 3.5-fold increase in free pro-MMP9. The high-molecular-mass gelatinases denoted by HMW1 and -2 and comprising homo- and heteropolymers of pro-MMP2 and -9 were also raised in AMD (P < 0.05). The sequestration of free pro-MMP2 and -9 by these high-molecular-mass complexes may further contribute to reduced rates of activation of MMPs.
  
  
  CONCLUSIONS
  The reduction in the levels of activated MMP2 and -9 may be responsible for impaired matrix degradation of Bruch's membrane, leading to the pathology associated with AMD. The degradation pathway is therefore a viable therapeutic target for future intervention.
authors.affiliation: Division of Molecular Therapy, UCL Institute of Ophthalmology, University of London, London, United Kingdom.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Hussain
authors.forename: Yunhee
authors.initials: Y
authors.lastname: Lee
authors.forename: Jin-Jun
authors.initials: JJ
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Marshall
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D015153:Blotting, Western; D016570:Bruch Membrane / Q000201:enzymology* / Q000473:pathology; D002829:Choroid / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007124:Immunoenzyme Techniques; D008268:Macular Degeneration / Q000201:enzymology* / Q000473:pathology; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D012720:Severity of Illness Index
chemical_list: D020782:Matrix Metalloproteinases