Differential expression of vascular endothelial growth factor implies the limbal origin of pterygia.
OBJECTIVE
To study the distribution of isoforms of vascular endothelial growth factor (VEGF) and its receptors VEGFR1 and VEGFR2 in pterygia and to compare it with that in healthy conjunctivas.


METHODS
Nonrandomized comparative (cadaver controlled) study with histopathologic correlations.


METHODS
Tissue specimens from 75 patients treated for primary pterygia were analyzed using immunohistochemical studies as well as different molecular biological examinations. Healthy conjunctivas from 33 patients treated for cataracts as well as specimens from the conjunctiva, limbus, and lens of both eyes of 12 body donors served as controls.


METHODS
Surgical specimens of pterygia and normal conjunctiva specimens were processed with paraffin, sectioned, stained using specific antibodies against VEGF and its receptors, and examined by light microscopy. The other part of both groups of specimens as well as specimens from body donors were prepared and analyzed by means of reverse-transcription polymerase chain reaction (RT-PCR), real-time RT-PCR, enzyme-linked immunosorbent assay, and Western blots.


METHODS
Vascular endothelial growth factor and VEGFR1 and VEGFR2 were analyzed to indentify the splice variants of VEGF as well as the distribution and amount of VEGF and both receptors in pterygia and the control tissues.


RESULTS
In analysis of specimens from pterygium patients as well as normal conjunctivas, VEGF121 and VEGF165 were identified as the only VEGF splice forms expressed. In addition to VEGF, VEGFR1 and VEGFR2 were detected in pterygia and conjunctivas and immunostained within the epithelium of pterygia and conjunctivas and on intrapterygial and intraconjunctival endothelial cells. Levels of VEGFR1 and VEGFR2 mRNA were lower in pterygia than in conjunctivas but similar in limbal and pterygium samples. Vascular endothelial growth factor levels were higher in pterygia than in conjunctivas, but were similar in the limbus and pterygia.


CONCLUSIONS
The results reveal similar behaviors in limbal and pterygium epithelial cells in terms of VEGF and VEGFR expression, with the presumption that pterygia arise from limbal epithelial cells and that human conjunctivas are not a suitable control for the analysis of pterygia. Moreover, the results suggest that VEGF might play an active role in the physiology of conjunctival epithelial cells.
Gebhardt
Matthias
M
Department of Anatomy, Christian Albrecht University of Kiel, Kiel, Germany.
Mentlein
Rolf
R
Schaudig
Ulrich
U
Pufe
Thomas
T
Recker
Kristin
K
Nölle
Bernhard
B
Al-Samir
Kais
K
Geerling
Gerd
G
Paulsen
Friedrich P
FP
D015153:Blotting, Western; D003228:Conjunctiva / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007124:Immunoenzyme Techniques; D007908:Lens, Crystalline / Q000378:metabolism; D016850:Limbus Corneae / Q000378:metabolism*; D008297:Male; D011625:Pterygium / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*
D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2