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Thrombospondin-1 expression in RPE and choroidal neovascular membranes
Shikun He1, Francesca Incardona, Manlin Jin
1Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles 90033, USA.
Purpose:
To investigate the expression of thrombospondin 1 (TSP-1) in retinal pigment epithelium (RPE) and choroidal neovascular membranes (CNVMs) from patients with age-related macular degeneration (AMD).
Methods:
Tissue sections from normal human fetal and adult eyes and surgically removed CNVMs were immunostained for TSP-1 localization. Polymerase chain reaction and Western blotting were used to analyze TSP-1 mRNA and protein from human RPE cells, respectively. TSP-1 in the supernatant of cultured RPE cells and eye explants were measured using enzyme-linked immunosorbent assay. MTT assay was used to evaluate the RPE survival after TSP-1 treatment.
Results:
The strongest immunostaining for TSP-1 was observed in the RPE monolayer around drusen in early AMD. The intensity of TSP-1 staining in normal eye sections was much weaker than that of early AMD and CNVM. TSP-1 mRNA was positive in cultured fetal and adult RPE cells. There was increasing secretion of TSP-1 into the supernatant of cultured RPE and eye explants. The specific band of TSP-1 was identified by Western blot. No significant inhibition of RPE survival was found with the exposure to TSP-1.
Conclusions:
TSP-1 expression in drusen and CNVM was upregulated and associated with RPE monolayer. TSP-1 may be a natural negative regulator for choroidal neovascularization.
