Abstract
Purpose: :
Galectin (Gal) -1, -3, and -9 have recently emerged as novel regulators of the inflammatory response. However, systematic study for immune mechanism of Gal molecules in intraocular immune system has not been performed yet. In this report we elucidated expression of Gals in RPE cells in vitro and normal and inflammatory eyes in vivo.
Methods: :
Human RPE cell line, ARPE19 and hTERT (3×105/well) were incubated with or without 10 ng/ml cytokines (interleukin -2, interleukin-12, and IFN - γ) at 37°C for 1, 3, 6, 12, and 24 hours. Expression levels of mRNA coding for Gal-1, -3, and -9 were determined by real -time PCR. Experimental autoimmune uveitis (EAU) was induced in rat by injection of S-antigen. The remaining rats served as controls. Eleven days post injection, the eyes were obtained from normal and EAU group. The samples were cross dissected and stained with antibodies against Gal-1, -3, and -9, respectively. The observation was done with confocal laser scanning microscopy.
Results: :
ARPE and hTERT revealed detectable Gal-1, -3, and -9 at 1, 3, 6, 12, 24 hours of exposure to IL-2, IL12, IFN-γ. The expression level of Gal-1 was not changed by cytokine stimulation. That of Gal-3 was decreased, and that of Gal-9 increased markedly. In normal eyes, immunofluorescence staining for Gal-1 antibody was found in inner layer and outer layer of the retina. Gal-3 and Gal-9 expression were seen weakly in outer layer of retina. On the other hand, Gal- 3 and -9 expression were seen in all retinal layers of the EAU eyes. Gal-9 was expressed extremely high in RPE layer of the EAU eyes compared to the normal eyes.
Conclusions: :
It was suggested that Gal molecules are responsible for the intraocular immune response as well as a cell adhesion cofactor. In addition, it was suggested that Gal-9 has a function as an immunomodulatory molecule of intraocular inflammation.
Keywords: uveitis-clinical/animal model • retinitis • immunomodulation/immunoregulation