Thrombospondin-1 expression in RPE and choroidal neovascular membranes.
OBJECTIVE
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.
He
Shikun
S
Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles 90033, USA.
Incardona
Francesca
F
Jin
Manlin
M
Ryan
Stephen J
SJ
Hinton
David R
DR
D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002460:Cell Line; D020256:Choroidal Neovascularization / Q000378:metabolism* / Q000473:pathology; D005333:Fetus / Q000166:cytology; D006801:Humans; D008268:Macular Degeneration / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D019700:Thrombospondin 1 / Q000378:metabolism*
D019700:Thrombospondin 1