Abstract
Purpose:
Biomarkers for age-related macular degeneration (AMD) are urgently needed. Previously we reported a key role for Rho kinase (ROCK) signaling in choroidal neovascularization (CNV). CD163 is a M2- macrophage surface marker, the expression of which in CNV has not been known. We investigate the regulatory role of ROCK in CD163 expression and their potential as biomarkers in AMD.
Methods:
CNV was induced in C57BL/6J mice using a 532-nm laser (100mW, 50µm, 100ms).<br /> Western Blot was performed for CD163, CCR7, CD80 and β-tubulin . Choroids were harvested at different time points (4 h, 1, 3, 7 and 14 days) after CNV induction.<br /> On day 7 mice were treated with dual ROCK1/2- and a ROCK 2 selective inhibitor.<br /> For histology frozen sections of the posterior segment, including the central portion of CNV lesions (10 lesions per eye), were prepared. The number of CD163 positive macrophages was counted.
Results:
The time course of protein expression showed significantly elevated CD163 levels in CNV through day 14. CCR7 was unchanged while CD80 was moderately higher in the first three days. CD 163 was only found in CNV lesions, but not in unlasered mice. ROCK inhibition significantly reduced CD163 in CNV lesions compared with vehicle treated animals. Immunohistochemistry confirmed that CD163(+) macrophages were increased in CNV lesions, while normal unlasered retinas did not show CD163(+) staining.
Conclusions:
CD163 expression was exclusive to CNV, while it was not found in the normal eyes. ROCK inhibition suppressed CD163 expression. The current results indicate that CD163 could become a biomarker for exudative AMD. CD163 expression in CNV lesions is effectively reduced by ROCK inhibition, making CD163 a sensitive marker for evaluation of therapeutic success.<br />