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Jami Gurley, Daniel J Carr, Stefanie M Hauck, Michael H Elliott; Neuroretina-Specific Caveolin-1 Depletion Blunts Retinal Inflammation: Potential Role of Enhanced TRAF3 Production. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5403.
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© ARVO (1962-2015); The Authors (2016-present)
Uncontrolled immune responses in the eye can lead to ocular tissue dysfunction and vision loss. Previously, we showed that global Caveolin-1 (Cav1) depletion in mice modulates retinal inflammation and immune cell recruitment in response to ocular lipopolysaccharide (LPS). This study evaluated the effects of local, neuroretinal Cav1 ablation on LPS-induced retinal inflammation. We also investigated potential mediators of inflammatory protection in animals with neuroretinal Cav1 depletion.
Neuroretina-specific Cav1 knockout (Chx10-KO) mice were generated by Chx10-driven Cre-mediated recombination. Cav1 deletion efficiency/specificity and TNF receptor-associated factor 3 (TRAF3) levels were assessed by immunohistochemistry, western blotting, and mass spectrometry. Association of TRAF3 with detergent-resistant “raft” fractions from Chx10-KO and control retinas was evaluated by western blotting. Chx10-KO and littermate controls were challenged with intravitreal LPS (0.5 µg/eye) or vehicle. Twenty-four hours post-challenge, retinal cytokine/chemokine (Cxcl1/KC, Ccl2/MCP-1, IL-6) production and immune cell infiltration were measured by multiplex protein suspension array (n=4) and flow cytometry (n=7-9), respectively. Data were represented as mean ± SEM and analyzed by Student’s t-test or 2-way ANOVA.
Chx-10 mediated recombination in retinal Müller glia and neuronal cells (but not in retinal pigmented epithelium or vasculature) resulted in >70% depletion of neuroretinal Cav1. Following LPS challenge, Chx10-KO animals had significantly decreased retinal inflammatory cytokine/chemokine (~30-80%; p<0.05) and infiltrating immune cell (~75-80%; p<0.01) levels compared to controls. TRAF3 protein levels were increased 2.7-fold in Ch10-KO retinas compared to controls (p < 0.001). TRAF3 co-fractionated with Cav1 in detergent-resistant membrane fractions from control retinas but was predominantly detergent-soluble in Chx10-KOs indicating that TRAF3’s association with “rafts” depends on Cav1.
Our results suggest that neuroretinal Cav1 plays a key role in modulating local innate inflammatory responses in the retina and support a role for Cav1 in modulating TRAF3 protein levels. Our results are consistent with the novel hypothesis that Cav1 inflammatory modulation is mediated through control of TRAF3 levels.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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