Microarray and protein analysis of human pterygium.
OBJECTIVE
Pterygium is a sunlight-related, ocular-surface lesion that can obscure vision. In order to identify specific genes that may play a role in pterygium pathogenesis, we analyzed the global gene expression profile of pterygium in relation to autologous conjunctiva.


METHODS
Oligonucleotide microarray hybridization was used to compare the gene expression profile between human whole pterygium and autologous conjunctiva. Selected genes were further characterized by RT-PCR, western blot, and immunohistochemistry, and comparisons were made with limbal and corneal tissues.


RESULTS
Thirty-four genes exhibited a 2 fold or greater difference in expression between human whole pterygium and autologous conjunctiva. Twenty-nine transcripts were increased and five transcripts were decreased in pterygium. Fibronectin, macrophage-inflammatory protein-4 (MIP-4), and lipocalin 2 (oncogene 24p3; NGAL) were increased 9, 5, and 2.4 fold, respectively, while Per1 and Ephrin-A1 were decreased 2 fold in pterygium. Western blots showed that fibronectin and MIP-4 were increased in pterygium compared to limbus, cornea, and conjunctiva. Immunohistochemical analysis showed fibronectin in the stroma; lipocalin 2 in the basal epithelial cells, basement membrane, and extracellular stroma; and MIP-4 in all areas of the pterygium.


CONCLUSIONS
These data show both novel and previously identified extracellular-matrix-related, proinflammatory, angiogenic, fibrogenic, and oncogenic genes expressed in human pterygium. Comparisons of selected genes with limbal and corneal tissues gave results similar to comparisons between pterygium and normal conjunctiva. The increased expression of lipocalin 2, which activates matrix metalloproteinases (MMP), is consistent with our previous findings that MMP-9 and other MMPs are highly expressed in pterygium basal epithelium.
John-Aryankalayil
Molykutty
M
National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. aryankalayilm@mail.nih.gov
Dushku
Nicholas
N
Jaworski
Cynthia J
CJ
Cox
Constance A
CA
Schultz
Gregory
G
Smith
Janine A
JA
Ramsey
Keri E
KE
Stephan
Dietrich A
DA
Freedman
Kenn A
KA
Reid
Ted W
TW
Carper
Deborah A
DA
D000209:Acute-Phase Proteins / Q000378:metabolism; D015153:Blotting, Western; D000075906:Chemokine CCL26; D019742:Chemokines, CC / Q000378:metabolism; D003228:Conjunctiva / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D000071068:Lipocalin-2; D054834:Lipocalins; D020411:Oligonucleotide Array Sequence Analysis; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D011625:Pterygium / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000209:Acute-Phase Proteins; C111792:CCL18 protein, human; C120429:CCL26 protein, human; D000075906:Chemokine CCL26; D019742:Chemokines, CC; D005136:Eye Proteins; D005353:Fibronectins; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins