title: Coexpression of heparanase activity, cathepsin L, tissue factor, tissue factor pathway inhibitor, and MMP-9 in proliferative diabetic retinopathy.
abstract: OBJECTIVE
  Heparanase cleaves heparan sulfate side chains of heparan sulfate proteoglycans, activity that is implicated in angiogenesis. Proteolytic cleavage of proheparanase by cathepsin L leads to the formation of catalytically active heparanase. We investigated the expression levels of heparanase enzymatic activity and correlated these with the levels of cathepsin L, the angiogenic factors tissue factor (TF) and matrix metalloproteinase-9 (MMP-9), and the angiostatic factor tissue factor pathway inhibitor (TFPI) in proliferative diabetic retinopathy (PDR).
  
  
  METHODS
  Vitreous samples from 25 patients with PDR and 20 nondiabetic patients and epiretinal membranes from 12 patients with PDR were studied with enzyme-linked immunosorbent assay, western blot analysis, and immunohistochemistry.
  
  
  RESULTS
  We observed a significant increase in the expression of heparanase activity in vitreous samples from patients with PDR compared to the nondiabetic controls (p=0.027). Significant positive correlations were found between the levels of heparanase activity and the levels of cathepsin L (r=0.51; p=0.001), TF (r=0.6; p<0.0001), and TFPI (r=0.49; p=0.001). The expression levels of cathepsin L (p=0.019), TF (p<0.0001), TFPI (p<0.0001), and MMP-9 (p=0.029) were significantly higher in the vitreous samples with detected heparanase activity compared to the vitreous samples with undetected heparanase activity. Western blot analysis demonstrated proteolytic cleavage of TFPI in the vitreous samples from patients with PDR. In the epiretinal membranes, cathepsin L, TF, and TFPI were expressed in vascular endothelial cells and CD45-expressing leukocytes. Significant positive correlations were detected between the number of blood vessels that expressed CD31 and the number of blood vessels that expressed TF (r=0.9; p<0.0001) and TFPI (r=0.81; p=0.001).
  
  
  CONCLUSIONS
  The coexpression of these angiogenesis regulatory factors suggests cross-talk between these factors and pathogenesis of PDR angiogenesis.
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia; Dr. Nasser Al-Rashid Research Chair in Ophthalmology.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Abu El-Asrar
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Mohammad Mairaj
authors.initials: MM
authors.lastname: Siddiquei
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Mohd Imtiaz
authors.initials: MI
authors.lastname: Nawaz
authors.affiliation: Laboratory of Histochemistry and Cytochemistry, University of Leuven, KU Leuven, Leuven, Belgium.
authors.forename: Gert
authors.initials: G
authors.lastname: De Hertogh
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Ghulam
authors.initials: G
authors.lastname: Mohammad
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Kaiser
authors.initials: K
authors.lastname: Alam
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Mousa
authors.affiliation: Rega Institute for Medical Research, Department of Microbiology and Immunology, University of Leuven, KU Leuven, Leuven, Belgium.
authors.forename: Ghislain
authors.initials: G
authors.lastname: Opdenakker
mesh_terms: D000328:Adult; D000368:Aged; D015153:Blotting, Western; D056668:Cathepsin L / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D019773:Epiretinal Membrane / Q000378:metabolism; D005260:Female; D005966:Glucuronidase / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008074:Lipoproteins / Q000378:metabolism*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008875:Middle Aged; D014822:Vitreous Body / Q000378:metabolism*; D000099175:Heparanase
chemical_list: D056668:Cathepsin L; D005966:Glucuronidase; D008074:Lipoproteins; D020780:Matrix Metalloproteinase 9; D000099175:Heparanase; C051928:lipoprotein-associated coagulation inhibitor; C579270:MMP9 protein, human