Involvement of SPARC and MMP-3 in the pathogenesis of human pterygium.
OBJECTIVE
To investigate the expression of SPARC and matrix metalloproteinases (MMPs) in normal conjunctiva and pterygium tissues.


METHODS
This study involved paired control or uninvolved conjunctiva and pterygium tissue from 21 patients. Quantitative real-time PCR was performed to assess SPARC and MMP mRNA expression, whereas Western blot analysis was performed to assess SPARC protein levels in normal conjunctiva and pterygium tissue. Tissue localization of SPARC, extracellular matrix proteins, and MMPs were determined by immunofluorescence analyses.


RESULTS
SPARC transcript and protein levels were upregulated in pterygium compared with normal conjunctiva. Immunofluorescence analyses showed localization of SPARC to the epithelial basement membrane and stroma of normal conjunctiva tissue. Increased SPARC in the pterygium stroma colocalized partially with elevated collagen I, fibronectin, α-SMA, and MMP-3. SPARC and MMP-3 also colocalized in the pterygium epithelium.


CONCLUSIONS
SPARC was upregulated in pterygium and may collaborate with increased MMP-3 in some patients to account for many of the phenotypic properties characteristic of pterygium.
Ocular Wound Healing and Therapeutics Laboratory, Singapore Eye Research Institute, Singapore. seet.li.fong@seri.com.sg
Li-Fong
LF
Seet
Louis
L
Tong
Roseline
R
Su
Tina T
TT
Wong
D015153:Blotting, Western; D002478:Cells, Cultured; D003228:Conjunctiva / Q000378:metabolism / Q000473:pathology; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D020022:Genetic Predisposition to Disease; D006801:Humans; D019278:Matrix Metalloproteinase 3 / Q000096:biosynthesis / Q000235:genetics*; D015676:Osteonectin / Q000096:biosynthesis / Q000235:genetics*; D010641:Phenotype; D011625:Pterygium / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
D015676:Osteonectin; D012333:RNA, Messenger; D019278:Matrix Metalloproteinase 3