Purchase this article with an account.
Nitza Goldenberg-Cohen, Dana Morzaev, Shirel Weiss, Edith Hochhauser; TLR4 knock-out mice are resistant to optic nerve crush damage. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1426.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The purpose of the study is to investigate the role of inflammation induced damage following optic nerve crush (ONC) in knockout (KO) mice for toll like receptor 4 (TLR4 KO) gene.
ONC was induced in 30 TLR4 KO and 30 C57BL6 wild type (Wt) mice, by compressing the optic nerve immediately posterior to the globe. Histology and molecular analysis for inflammatory, hypoxic and apoptotic gene expression was performed on days 1, 3 and 21. Histological sections of the retina and ON were analyzed to measure the damage and RGCs loss.
In the optic nerves, molecular analysis revealed the increase of TNF-α (7.3, 6.1), the reduction of CD45 (0.8, 1.1) and of GFAP (0.65, 0.4) on day 1 in the TLR4 KO mice and Wt controls, respectively (NS). On day 3, TNF-α, CD45 and GFAP levels decreased in TLR4 KO mice (2.0, 0.6, 0.5) and increased in Wt (6.8, 1.8, 0.6). On day 21, levels of expression of the 3 genes in the TLR4 KO group (4.3, 2.0 1.0), and Wt (4.7, 5.6, 1.2) increased again, except for a mild reduction in the Wt TNF-α levels. In the retina: On day 1, all increased, with higher levels of TNF-α in TLR4 KO and relatively lower CD45 and GFAP levels as compared to Wt (10.3, 1.6, 2.8 TLR4 KO Vs 4.3, 12.1,10.3 Wt, respectively) . On day 3 CD45 and GFAP (but not TNF-α) levels reverted to baseline in both groups: TLR4 KO (2.5 , 0.8, 0.7) and Wt (4.8, 1.5, 1.8). On day 21 only TNF-α was increased in the TLR4 KO (3.6, 1.1, 1.2) and CD45 in the Wt (0.5, 3.9, 0.7). Apoptotic Bax levels in the retina increased from day 1 to 3 in the TLR4 KO (0.4 to 1.3) but was higher in the Wt (1.8 to 6.8). TUNEL staining showed reduced apoptosis in the TLR4 KO retina and optic nerve on days 1 and 3, as compared to the Wt mice. CD45 and Iba1 in the Wt increased more than the TLR4 KO mice (as seen by immuno-staining), showing the infiltration of inflammatory cells, specifically microglia, to the damaged retina. Histological analysis showed a mean 50% cell loss in ONC-injured retina of Wt while only 15% loss was detected in TLR4 KO mice.
Inflammatory reaction plays a role in ONC damage, as shown in Wt. Reduced levels of inflammation and improved RGCs preservation was observed in TLR4 KO mice. However, increased TNF-α expression might bypass the CD45 inflammatory pathway, leading to a 15% RGC loss.
This PDF is available to Subscribers Only