Involvement of ER Stress in Human Primary Pterygium

Purpose: The aim of this study was to investigate the ER stress activation in human primary pterygium. Methods and materials: Human primary pterygium or normal Tenon's capsule tissues were obtained from patients with primary pterygium following surgical excision or from normal human fresh cadaver eyes. The tissues were processed within 2 hours. The mRNA or protein specimens were extracted from those tissues for analysis, cryosections of those tissues were prepared for immunohistochemical staining. The mRNA levels of endoplasmic reticulum (ER) stress-related factors in those tissues were detected by qPCR analysis and the related proteins levels were detected by qPCR analysis and immunohistochemical staining or western blotting. Results: The ER stress-related gene transcription levels of GRP78，spliced XBP-1, ATF4 and ATF6 and the protein expression levels of GRP78, p-IRE1α, p-eIF2α and ATF6 were all increased in the human primary pterygium tissues when compared with the normal control tissues. Conclusion: The results in this study suggest that the three unfolded protein response pathways are all activated in the human primary pterygium tissues, which indicates that the ER stress is involved in the progression of pterygium, and also suggests a potential mechanism of ER stress-induced inflammation in the human primary pterygium tissues.