Tag Archives: ARVO

2-nm Resolution Anatomy of Retinal Neuro-Glial-Vascular Architecture

This abstract was presented today, May 2th at the 2016 Association for Research in Vision and Opthalmology (ARVO) meetings in Seattle, Washington by Jefferson R. Brown, Rebecca L. Pfeiffer, Crystal Sigulinsky, Felix Vazquez-Chona, Daniel Emrich, Bryan W. Jones, Robert E. Marc.

Abstract Number: 995

Author Block: Jefferson R. Brown, Rebecca L. Pfeiffer, Crystal Sigulinsky, Felix Vazquez-Chona, Daniel Emrich, Bryan W. Jones, Robert E. Marc
1 Dept of Ophthalmology, University of Utah, Salt Lake City, Utah, United States

Disclosure Block:Jefferson R. Brown, None; Rebecca L. Pfeiffer, None; Crystal Sigulinsky, None; Felix Vazquez-Chona, None; Daniel Emrich, None; Bryan W. Jones, None; Robert E. Marc, Signature Immunologics (Code I (Personal Financial Interest) )

Purpose:Retinal vasculature is strongly affected by degenerative pathologies and in turn, may also contribute to their progression. However, much of what we understand about the normal, healthy interaction between neurons, glia, and blood vessels at the ultrastructural level is limited to single section electron microscopy. The technology of serial section transmission electron microscopy (ssTEM) extends the high definition of TEM imaging into three dimensions to create volumes, allowing for more thorough visualization and analysis of the vascular-glial-neuronal complex.

Methods:RC2 is a 40TB ssTEM volume of over 1,400 horizontal sections of retinal tissue derived from an adult female C57BL/6J mouse. The tissue sample is 250 um in diameter and spans the outer nuclear layer to the vitreal surface. Baseline resolution is 2.18nm per pixel. Visualization, navigation and metadata annotations of the database are made via the Viking software suite.

Results:Much of the retinal vascular basement membrane directly contacts Muller cells. In the ganglion cell layer, direct basement membrane contact with astrocytes is frequent. Microglia commonly contact the basement membrane, and occasionally direct contact of neurons onto basement membrane was observed. Full 3D reconstruction of all vascular pathways with associated endothelia and pericytes within the volume was completed, demonstrating that all the retinal capillary layers are continuous with one another [Figure].

Conclusions:The presence of occasional direct neuronal contact onto vascular basement membrane supports earlier work by Ochs and colleagues (2000) and suggests the blood-retina barrier does not universally involve retinal glia. However, since such contacts are extremely sparse, it remains to be seen whether this finding has biologic significance, though their existence suggests significance. The RC2 volume is a valuable resource to aid in discovery of defining characteristics of wild type neurovascular architecture.

The intro figure is a side view of reconstruction of all vasculature within the RC2 volume. Vessels at the top of the figure correspond to the outer plexiform layer, while those at the bottom correspond to the ganglion cell layer. This capillary plexus is one continuous structure. Visualization by VikingView software.

Retinal Metabolic Response to Cigarette Smoke

This abstract was presented today at the Association for Research in Vision and Opthalmology (ARVO) meetings in Seattle, Washington by Alexandra D. Butler, William D. Ferrell, Alex Woodell, Carl Atkinson, Baerbel Rohrer, Robert E. Marc and Bryan W. Jones.

Purpose:  Smoking is the single largest risk factor for age-related macular degeneration, aside from age. Several of the main genetic risk factors for AMD are polymorphisms occurring in complement genes involved in the alternative, classical and common terminal pathways. To better understand the metabolic impact of smoking on the retina, we used computational molecular phenotyping (CMP) and examined the effects of cigarette smoke on wild type (wt) retinas and mice in which either the alternative pathway (complement factor B, CfB) or the common terminal pathway (complement component 3, C3) was removed.

Methods:  Mice were exposed to either cigarette smoke or filtered air. Cigarette smoke (CS) was generated using an automated cigarette-smoking machine (Model TE-10, Teague Enterprises, Davis, CA) by burning 3R4F reference cigarettes (2.45 mg nicotine per cigarette; purchased from the Tobacco Health Research Institute, University of Kentucky, Lexington, KY). Mice were exposed to CS for 6 hours/day, 5 days/week for 6 months. Age matched room filtered air exposed mice were used as controls. Eyes were enucleated immediately post-mortem, fixed in 1% paraformaldehyde, 2.5% glutaraldehyde, dehydrated in graded methanols, embedded in eponates and histologically analyzed with CMP.

Results:  Alterations in retinal small molecule signatures from mice exposed to cigarette smoke were observed compared to retinas from non-smoked mice in wt, CfB and C3 knockout mice. Signal changes with arginine, glutamine and glutathione progressively increased in the retinas of smoked exposed wt, CfB and C3 knockout mice, indicating increased response profiles to cell stress. Both Müller cells and photoreceptors of wt smoked retinas demonstrated changes relative to non- smoked retinas.

Conclusions:  Arginine, glutamine and glutathione, amino acids known to be involved in cellular stress responses, were increased in retinal neurons and glial cells upon smoke exposure. Eliminating essential components of the complement system, a cascade required for the maintenance of the immune privilege of the eye, appears to exacerbate responses to cigarette smoke in oxidative damage response related pathways. Understanding complement-dependent alterations in the eye will aid in our understanding of AMD pathology and may open new avenues for novel treatment strategies.

Support:  RPB CDA (BWJ), Thome AMD Grant (BWJ), NIH EY02576 (RM), NIH EY015128 (RM), NSF 0941717 (RM), NIH EY014800 Vision Core (RM), NIH EY019320 (BR), VA merit award RX000444 (BR), grant to MUSC from RPB