The role of tenascin-C in fibrovascular membrane formation in diabetic retinopathy

Abstract

Purpose: We have previously demonstrated that tenascin-C was highly expressed in the fibrovascular membranes (FVMs) from patients with proliferative diabetic retinopathy (PDR). However, its exact roles in the pathogenesis of FVMs remain elusive. The purpose of this study was to investigate the role of tenascin-C in the formation of FVMs.

Methods: We measured the levels of tenascin-C, periostin and VEGF by sandwich enzyme linked immunosorbent assay in vitreous samples collected from patients with macular hole, epiretinal membrane, PDR, and proliferative vitreoretinopathy (PVR). The location of tenascin-C, αSMA, CD34, and GFAP was also determined by immunohistochemistry. The oxygen-induced retinopathy (OIR) model was generated by exposing the neonatal mice to 75% oxygen from postnatal day (P)7 until P12 and returned to room air. Retinal cryostat sections were made and immunohistochemistry was performed using anti-tenascin-C, anti-αSMA, and anti-CD31 antibodies. In vitro, Cell proliferation, migration, and tube formation assay was performed using human retinal endothelial cells (HRECs).

Results: The mean vitreous levels of tenascin-C were significantly higher in patients with PDR and PVR than in macular hole patients (P <0.001). There was a significant correlation between the vitreous concentrations of tenascin-C and periostin in patients with PDR (r=0.439, P <0.0001), but low correlation between tenascin-C and VEGF (r=0.181, P =0.0027). Double immunofluorescence analyses of FVMs from PDR patients showed that tenascin-C was co-stained with both αSMA and CD34, but not with GFAP. Immunohistochemical analysis of OIR retinas showed that tenascin-C was co-stained with αSMA in the hypoxic retina and with CD31 in the neovascular tufts. Moreover, recombinant tenascin-C promoted proliferation, migration, and tube formation of HRECs in a dose-dependent manner.

Conclusions: Tenascin-C may be produced by vascular smooth muscle cells and promote the formation of FVMs in a paracrine fashion.