Overexpression of fractalkine and its histopathological characteristics in primary pterygium

The role of cyclophilin A and VEGF in the pathogenesis and recurrence of pterygium

PURPOSE

Pterygium is defined as overgrowth of abnormal conjunctival tissue on the cornea. Many proinflammatory cytokines and various growth factors have been implicated in the pathogenesis of pterygium. Cyclophilin A (CyPA) is a protein that is used by cyclosporin A (CsA) as the intracellular receptor and is secreted in response to inflammatory stimuli. Vascular endothelial growth factor (VEGF) is the most important angiogenic factor. This study aimed to assessment CyPA and VEGF immunoreactivity in pterygium specimens.

MATERIAL AND METHODS

In this cross-sectional study, 32 primary pterygium samples, 25 recurrent pterygium samples and 25 normal bulbar conjunctiva samples were included. The histopathological features, CyPA and VEGF immunoreactivity of surgically excised pterygium specimens were compared with control conjunctiva specimens obtained from normal bulbar conjunctiva.

RESULTS

CyPA immunoreactivity in vascular endothelial cells, epithelial cells, and stromal cells was remarkably higher in pterygium specimens than control conjunctiva specimens (p = 0.004, p = 0.012, p = 0.001, respectively). Morever, VEGF immunoreactivity in endothelial cells was remarkably higher in pterygium specimens than control conjunctiva specimens (p < 0.001). When recurrent and primary pterygium specimens were compared, CyPA and VEGF immunoreactivity was remarkably higher in recurrent pterygium (p = 0.001, p = 0.001, respectively). Pearson correlation showed that CyPA immunoreactivity correlated with stromal vascularity, stromal inflammation, and mast cell count in pterygium specimens.

CONCLUSION

This study aimed to assess CyPA and VEGF may have a important function in the pathogenesis and recurrence of pterygium.

Pterygium-The Good, the Bad, and the Ugly

Pterygium is a multifaceted pathology that displays apparent conflicting characteristics: benign (e.g., self-limiting and superficial), bad (e.g., proliferative and potentially recurrent) and ugly (e.g., signs of preneoplastic transformation). The natural successive question is: why are we lacking reports showing that pterygium lesions become life-threatening through metastasis, especially since pterygium has considerable similarities with UV-related malignancies on the molecular level? In this review, we consider how our pathophysiological understanding of the benign pterygium pathology overlaps with ocular surface squamous neoplasia and skin cancer. The three UV-related disorders share the same initial insult (i.e., UV radiation) and responsive repair mechanisms to the ensuing (in)direct DNA damage. Their downstream apoptotic regulators and other cellular adaptations are remarkably alike. However, a complicating factor in understanding the fine line between the self-limiting nature of pterygium and the malignant transformation in other UV-related diseases is the prominent ambiguity in the pathological evaluation of pterygium biopsies. Features of preneoplastic transformation (i.e., dysplasia) are used to define normal cellular reactions (i.e., atypia and metaplasia) and vice versa. A uniform grading system could help in unraveling the true nature of this ancient disease and potentially help in identifying the earliest intervention point possible regarding the cellular switch that drives a cell’s fate towards cancer.