Expression of membrane-associated mucins in limbal stem cell deficiency and after transplantation of cultivated limbal epithelium.
OBJECTIVE
Membrane-associated mucins are important components of the ocular tear film. Our objective was to characterize the expression of membrane-associated mucins MUC1, MUC4, and MUC16 in healthy cornea, healthy conjunctiva, fibrovascular tissue (pannus) covering the corneal surface in limbal stem cell deficiency (LSCD), human limbal epithelial cells cultivated on intact amniotic membrane (HLEC-AM), and corneal epithelium after transplantation of cultivated limbal epithelium (TCLE).


METHODS
Total RNA was isolated from six samples of healthy human cornea, healthy conjunctiva, pannus, limbal epithelial cell cultures, and four corneal samples after TCLE. The expression of MUC1, MUC4, and MUC16 was evaluated by real-time polymerase chain reaction (PCR), Western blotting, and immunofluorescence.


RESULTS
Conjunctiva showed a significantly higher expression of MUC1 and MUC4 than cornea, but the expression of MUC16 was similar in both tissues. The expression of MUC1 in HLEC-AM increased, MUC16 decreased, and MUC4 showed no significant difference when compared to cornea. The expression of all studied mucins in conjunctiva was significantly higher than in HLEC-AM. Pannus revealed a similar expression pattern of membrane-associated mucins to conjunctiva. The expression of all studied mucins in pannus was significantly higher than in cornea or HLEC-AM. A corneal expression pattern of membrane-associated mucins was found in all four samples of cornea after TCLE.


CONCLUSIONS
A tissue-specific expression of MUC1 and MUC4 but not MUC16 was found in human cornea and conjunctiva. LSCD led to a conjunctival expression pattern of mucins on the corneal surface. A corneal phenotype could be restored after TCLE, confirming the potential of this method to reconstruct the corneal surface.
Pauklin
Mikk
M
Department of Ophthalmology, University of Duisburg-Essen, Essen, Germany.
Kakkassery
Vinodh
V
Steuhl
Klaus-P
KP
Meller
Daniel
D
D000328:Adult; D000650:Amnion / Q000166:cytology; D015153:Blotting, Western; D018394:CA-125 Antigen / Q000235:genetics / Q000378:metabolism; D017690:Cell Transplantation; D018920:Coculture Techniques; D003228:Conjunctiva / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000378:metabolism* / Q000637:transplantation; D019573:Epithelium, Corneal / Q000378:metabolism* / Q000637:transplantation; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D016850:Limbus Corneae / Q000473:pathology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D018396:Mucin-1 / Q000235:genetics / Q000378:metabolism; D055264:Mucin-4 / Q000235:genetics / Q000378:metabolism; D009077:Mucins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000473:pathology
D018394:CA-125 Antigen; C060192:MUC1 protein, human; C451759:MUC16 protein, human; C524658:MUC4 protein, human; D008565:Membrane Proteins; D018396:Mucin-1; D055264:Mucin-4; D009077:Mucins