The role of CRABP2, FABP5, AND PPARD genes in pterygium

Pterygium is a wing shaped fibrovascular tissue, characterized by abnormal fibrovascular proliferation, matrix remodeling, and invasion. The pathogenesis of pterygium remains unknown. Retinoid acid (RA) is carried by two different lipid binding proteins cellular retinoic acid-binding protein 2 (CRABP2) and fatty acid-binding protein 5 (FABP5) in cells. The RA signalling can be transduced by two pathways that are mediated by RA receptors (RAR) as a tumor-suppressive pathway and peroxisome proliferatör activated receptors β/δ (PPARβ/δ) as a tumor-promoting pathway. The deregulated RA signaling may also contribute to the development and/or recurrence of pterygium. The aim of our study was to determine mRNA and protein expressions of CRABP2, FABP5, PPARD and ratio of CRABP2/FABP5 in primer and recurrent pterygium tissues. In our study, pterygial and healthy conjunctival tissues were obtained from 30 patients undergoing pterygium excision. CRABP2, FABP5, and PPARD mRNA and protein expression were assessed using Real-time PCR and Western blotting through examination of excised specimens from pterygium and normal conjunctival tissues. The expressions of CRABP2 and FABP5 were not altered when primary pterygium tissues compared normal conjunctival tissues (1,03±0,22- fold change, p=0,895; 1,02±0,19 p=0,917, respectively). Whereas the expressions of CRABP2 and FABP5 were decreased when recurrent pterygium tissues compared normal conjunctival tissues (0,71±0,39- fold change, p=0,577; 0,88±0,43 p=0,577, respectively). The expression of PPARD wasn't altered when both primary and recurrent pterygium tissues compared normal conjunctival tissues (1,08±0,28-fold change, p=0,784; 1,10±0,71 p=0,095, respectively). Understanding etiopathogenesis of pterygium will aid in find of more promising treatments to prevent pterygium in earlier stages. Key words: CRABP2, CRABP2/FABP5 ratio,FABP5, PPAR β/δ, retinoic acid signaling pathway