Abstract
Purpose:
Pterygium is an overgrowth of fibrovascular tissue, often with a wing-like appearance, from the conjuctiva over the cornea. There is much debate surround the pathogenesis of pterygium and a number of theories have been put forward including genetic instability, cellular proliferation, inflammatory influence, and degeneration of connective tissue, angiogenesis, aberrant apoptosis and viral infection. At present, the involvement of human papillomavirus (HPV) in the genesis of pterygium is controversial, as have reported that HPV is present in 58% of cases, while others have failed to detect HPV in pterygium. It also has been described that HPV proteins can regulate apoptosis. In this study, we evaluated the presence of HPV in pterygia and healthy conjunctiva samples, and analyze the HPV effect over apoptotic proteome in pterygia.
Methods:
Forty primary pterygia samples and 12 healthy conjunctiva samples were analyzed to HPV DNA presence by polymerase chain reaction, using MY09/MY11 primers of HPV-L1 gene. Viral genotype was identified by DNA sequence analysis of this amplicon. Apoptotic proteome was evaluated in four HPV positive and negative pterygia using human apoptosis protein array. Two hundred micrograms of total proteins were incubated with arrays. After protein incubation and washes, arrays were revealed with ECL and spots were captured in Dyversity System and analyzed with GeneTools Software. Spot densitometry data were normalized respect to internal control. Differences between arrays between pterygium and healthy conjunctiva were analyzed.
Results:
Presence of HPV was observed in 19 of the 40 pterygia samples. In contrast, healthy conjunctiva samples were negative. To determine virus type, sequence analyses were performed. Interestingly, 11 out of the 19-pterygium samples were identified as HPV-11 type, meanwhile, the remaining 8 pterygum samples were identified as HPV-18. Apoptotic proteome was analyzed and comparative analysis showed that cIAP-1, clusterin and XIAP were overexpressed and hsp70 and PON2 were underexpressed in HPV positive pterygia in contrast to HPV negative pterygia.
Conclusions:
Taken together these results suggest that viral presence in pterygium and an overexpression of apoptotic inhibitor proteins such as cIAP-1, clusterin and XIAP, could explain in part the etiopathology of this disease.
Keywords: 665 pterygium •
426 apoptosis/cell death •
474 conjunctiva