Abstract
Purpose :
Here, we describe analyses linking the presence of different phenotypical subtypes of macrophages, including inflammatory M1-like macrophages and inflammation-attenuating M2-like macrophages, with pro-lymphangiogenic Vegfc expression as well as lymphangiogenesis in pterygium specimens, relatively compared to subject-matched normal conjunctival tissue.
Methods :
We included pterygium body stromal specimens and the subject-matched conjunctival tenon’s tissue from 21 subjects. First, the involvement of myeloid cells was verified by markers and cytokines for pan-macrophage (Cd68, Itgxa [CD11c]), myeloid cell (Itgam [CD11b]), pro-inflammatory M1 (Cd80, Il1b), and anti-inflammatory M2 (Mrc1 [CD206], Cd163, Il10, Tgfb1). Then, the expression of pro-lymphangiogenic Vegfc and their receptor Flt4 (Vegfr3) and lymphatic endothelial Lyve1 expression was compared between in pterygium and conjunctiva and the their relative expression in pterygium was correlated with macrophage markers. Specifically, the role of M1 on the induction of inflammation and Vegfc activation in pterygium fibroblasts using in vitro co-culture and exosome transfer model. In histology, the localization of macrophages with VEGFC- or LYVE1-expressing cells were evaluated. Macrophage marker expression in pterygium was analyzed according to clinical severity of pterygium.
Results :
Cd68, Itgxa, Cd80, Il1b, and a monocyte chemoattractant Ccl2 were activated in pterygium stromal tissue and Ccl2 was specifically correlated with Cd68. In pterygium tissues, Vegfc and Lyve1 were activated compared to the subject-matched normal conjunctival tissues. Vegfc was positively correlated with M1 marker Cd86. By contrast, Lyve1 was positively correlated with M2 marker Mrc1 and Cd163. In both co-culturing system and M1-derived exosome delivery model, M1 clearly activated inflammatory signal and Vegfc in pterygium fibroblasts. In specimens, LYVE1 and CD206 was co-localized in pterygium stromal tissues. M2 marker Cd163 was inversely correlated with pterygium severity grades and scales.
Conclusions :
M1-like cells are activated in pterygium stroma compared to conjunctiva. The activation of pro-lymphangiogenic VEGFC/VEGFR-3 axis is linked to the M1-like myeloid cells in pterygium. However, M2-like myeloid cells may participate in the lymphatic vessel formation in pterygium body stroma and may be linked to the less severe clinical features of pterygium.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.