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C. Lupien, D. Inman, D. Calkins, P. Horner; Tempering Gliosis by Inhibition of the NFkB Pathway in an Acute Model of Glaucoma. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2781.
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Despite intense study, the mechanism of neurodegeneration in glaucoma is not understood. A specified neuron cell population, the retinal ganglion cell (RGC), is selectively vulnerable to the disease. Identifying extracellular signals that modulate RGC survival are essential for delineating the mechanisms of the disease. The retinal glial cells represent a source of these signals. Coincident with neuronal degeneration, gliosis, the proliferation and hypertrophy of glial cells, occurs in glaucoma. There are numerous signaling pathways involved in gliosis development. The NF-ΚB pathway has been implicated in gliosis by its transcriptional control of cell adhesion molecules. The goal of this study is to determine the role of NF-kB pathway in gliosis by tempering the glial response in a mouse model of glaucoma.
To perform this study, we used an acute mouse model of glaucoma. We carefully measure on a daily basis the rise of intraocular pressure (IOP) with a TonoLab. After one month the animals received an inhibitor of the NF-kB pathway, either UDCA or BMS-345541. After the inhibitor injection we waited 24h to 1 week before harvesting the tissues for analysis. Immunofluorescence and Western blot analysis were performed using antibodies against the native and the active forms (phosphorylated-pNF-kB) of NF-kB, the active form of IkB and GFAP antibody as a marker of gliosis. We also performed quantitative PCR analysis of GFAP, NF-kB and IkB comparing the mRNA expression before and after inhibitor treatment.
We performed the inhibitor treatment as a pre-treatment (before performing the acute model) or a post-treatment and compared the efficiency between both treatments. The immunofluorescence results indicate a decrease in the expression of GFAP, pNF-kB and pIkB for both UDCA and BMS-345541 treatments. This decrease of expression was quantified by western blot and QPCR analysis. The UDCA pre-treatment decreased pNFkB (7x) and pIkB (3.7x) protein expression. The expression of the GFAP protein decreased with both the pre-(1.8x) and post-(3.6x) treatment, but the post treatment was most effective. The BMS-345541 pre-treatment decreased GFAP (2x) but not pNFkB nor pIkB protein expression. The BMS-345541 post-treatment decreased all protein expression, GFAP (5.6x), pNF-kB (2x) and pIkB (3.7x).
Through this study we have demonstrated that it is possible to modulate the NF-kB pathway in order to temper gliosis in an in vivo mouse model of glaucoma.
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