Abstract

SO.04.10

Analysis of epithelial lineage origin and inflammatory status of human corneal pannus in limbal stem cell deficiency

Pauklin M., Brockmann-Ahmed S., Wettey F. R., Steuhl K.-P., Meller D.
Department of Ophthalmology, University Hospital Essen

Objective: Limbal stem cell deficiency is characterized by ingrowths of conjunctival epithelium into cornea, chronic inflammation and impaired visus. Our aim is to characterize the abnormal pannus tissue and thus the microenvironment into which the graft is introduced.
Methods: Total RNA was isolated from corneal pannus excised from 11 patients with limbal stem cell deficiency. 7 of the patients had injured a chemical burn and 4 had other diseases, namely GvHD, thermal burn, epidermolysis bullosa and perforating injury. Normal human cornea (n=4) and conjunctiva (n=4) was used as control tissue. The expression of epithelial lineage markers (keratin 3 (K3) and MUC5AC), inflammatory cytokines (IL-1a, IL-1b), adhesion molecules (ICAM-1, VCAM-1) and VEGF was analyzed by real-time PCR. Results were normalized to GAPDH and determined relative to normal cornea.
Results: Expression of MUC5AC was increased in conjunctiva compared to cornea, whereas K3 was reduced. Due to its vascularisation the expression of ICAM-1, VCAM-1, IL-1b and VEGF was higher in conjunctiva than in cornea. K3 expression was in significantly reduced pannus samples compared to cornea, while MUC5AC expression was increased up to 100000-fold. The samples of patients with chemical burn showed even higher MUC5AC expression than conjunctiva. All pannus samples exhibited higher expression of ICAM-1, VCAM-1, IL-1b and VEGF compared to cornea. IL-1a was only moderately increased in chemical burn patients, but higher in the other patients.
Conclusions: The analyzed pannus resembled conjunctiva and not cornea. High expression of inflammatory and vascularisation factors confirmed a chronic inflammation in the examined pannus tissues.

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