Preliminary evidence of the presence of lymphatic vessels immunoreactive for D2-40 and Prox-1 in human pterygium

Abstract

Abstract. Human pterygium is a benign fibrovascular outgrowth of the corneo-conjunctival junction, characterized by tissue remodeling, cellular proliferation, angiogenesis and inflammation. No data are available concerning the presence of lymphatic vessels in this pathological condition. The aim of this study was to evaluate by immunohistochemistry, using antibodies against D2-40, Prox-1 and Ki-67, the presence and the proliferative activity of lymphatic vessels in human pterygium. An increased lymphatic microvessel density was observed in the human pterygium compared to the normal conjunctiva. Moreover, D2-40-positive lymphatic endothelial cells were also actively proliferating, as assessed by Ki-67 immunostaining, while in normal conjunctiva proliferating lymphatic endothelial cells were not detectable. Overall, these data clearly indicate the presence of active proliferating lymphatic vessels in human pterygium, suggesting that active lymphangiogenesis occurs in this pathological condition. IntroductionPterygium is a disease characterized by surface ocular lesions associated with chronic ultraviolet exposure in which the primary effect is a solar actinic elastosis within the stroma and all other changes are secondary to the primary effect (1-7). Pterygium is characterized by cellular proliferation, inflammatory infiltration, fibrosis, angiogenesis, and extracellular matrix breakdown; the lesion begins to grow from limbal epithelium and invades the cornea centripetally followed by conjuntival epithelium, exhibiting degenerative and hyperplastic changes (1-7).Seifert and Sekundo identified intraepithelial capillaries in the optical half of 42.3% pterygia, providing the first evidence of neovascularization in this pathological condition (8). Other reports followed (9,10) and several angiogenic cytokines, such as fibroblast growth factor-2 (FGF-2), vascular endothelial growth factor (VEGF) platelet-derived growth factor (PDGF), transforming growth factor β (TGF-β), tumor necrosis factor α (TNF-α), interleukin-6 and -8 (IL-6 and IL-8) and nerve growth factor (NGF) (11-14) have been implicated as mediators of angiogenesis. Furthermore, the presence of mast cells has been correlated with the degree of angiogenesis in pterygium (15,16).Several antiangiogenic approaches have been proposed for the treatment of petrygium. One case report documented the successful treatment of an early recurrent pterygium using interferon α2β (17) and more recently, bevacizumab, a human monoclonal antibody anti-VEGF, has been proposed in the treatment of pterygium (18)(19)(20)(21)(22)(23).Few data are available concerning lymphangiogenesis in the cornea and the presence of lymphatic vessels in pterygium (24). The aim of this study was to evaluate by immunohistochemistry, by using antibodies against D2-40 and Prox-1, the presence of lymphatic vessels in human pterygium. Materials and methodsThe study group included 20 bioptic specimens of surgical excised primary or recurrent pterygium. Ten nasal epibulbar conjunctival segments, excised d...

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Pterygium Pathology: A Prospective Case-Control Study on Tear Film Cytokine Levels

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Conjunctival Lymphangiogenesis Was Associated with the Degree of Aggression in Substantial Recurrent Pterygia

“…Cimpean et al examined primary pterygium samples using D2-40 immunohistochemistry and reported an increased LMD in human pterygium compared with that in normal conjunctiva [ 29 ]. This report was the first to indicate active lymphangiogenesis in human pterygium.…”