Signal transduction mechanisms of neuroprotective substances in animal models of glaucoma and the role of the protein high-mobility group box-1 (HMGB-1)
Final Report Abstract
The objective of this proposal was to study neuroprotection as a challenge to understand and treat in glaucoma. Neuroprotection if offered as an additional treatment to IOP-lowering procedures. Different substances have been shown to be neuroprotective such as hemopoietic factor GM-CSF and α2-adrenergic agonist brimonidine. However, the signal transduction mechanisms of these substances remain unknown in the retina. We found that the nuclear protein high-mobility group-1 (HMGB-1) is expressed in the degenerating retina and operates through the receptors advanced glycation end products (RAGE), and in brain through toll-like receptor 2 (TLR-2) and TLR-4. Our studies performed with proteomic analysis revealed a strong expression of HMGB-1 in the retina exposed to either IOP-elevation or to injury induced ganglion cell death. We generated both in vivo glaucoma models and in vitro organotypic culture models and showed that progressive ganglion cells death is associated with HMGB-1 regulation. We applied immunohistochemistry, western blotting, and the quantitative real-time PCR to examine the expression levels of immunological factors (eg, HMGB-1, receptor for advanced glycation end products (RAGE)), Toll-like receptors 2 and 4 (TLR-2, TLR-4), apoptosis-related factors (eg, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated death promoter (Bad)) as well as cytokine expression (eg, tumor necrosis factor alpha (TNF-α), interleukin (IL)-4, IL-6, and vascular endothelial growth factor (VEGF)). The data revealed increased the expression of HMGB-1 and its receptors RAGE, TLR-2, and TLR-4, and TNF-α as well as pro-apoptotic factors (eg, Bad) as well as apoptosis in 661W cells exposed to elevated pressure. Co-cultivation of 661W cells with rHMGB-1 increased the expression levels of pro-apoptotic Bad and cleaved Caspase-3 resulting in apoptosis. Cytokine array studies revealed an increased release of TNF-α, IL-4, IL-6, and VEGF after incubation of 661W cells with rHMGB-1. Upregulation of HMGB-1, TLR-2, and RAGE as well as anti-apoptotic Bcl-2 expression levels was found in the retinal explants exposed to rHMGB-1 or elevated pressure. The results suggest that HMGB-1 promotes an inflammatory response and mediates apoptosis in the pathology of photoreceptors and retinal homeostasis. HMGB-1 may have a key role in ongoing damage of retinal cells under conditions of elevated intraocular pressure. In addition, we studied further neuroprotective molecules, and in particular crystallins in the retina and discussed their potential mechanisms of activity within the retina.
Publications
- Macula-less rat and macula-bearing monkey retinas exhibit common lifelong proteomic changes. Neurobiol Aging. 2013 Nov;34(11):2659-75
Böhm MR, Mertsch S, König S, Spieker T, Thanos S
(See online at https://doi.org/10.1016/j.neurobiolaging.2013.04.020) - Role of crystallins in ocular neuroprotection and axonal regeneration. Prog Retin Eye Res. 2014 Sep;42:145-61
Thanos S, Böhm MR, Meyer zu Hörste M, Prokosch-Willing V, Hennig M, Bauer D, Heiligenhaus A
(See online at https://doi.org/10.1016/j.preteyeres.2014.06.004) - Life-time expression of the proteins peroxiredoxin, beta-synuclein, PARK7/DJ-1, and stathmin in the primary visual and primary somatosensory cortices in rats. Front Neuroanat. 2015 Mar 4; 9-16; eCollection 2015
Böhm MR, Melkonyan H, Thanos S
(See online at https://doi.org/10.3389/fnana.2015.00016) - βB2-Crystallin Promotes Axonal Regeneration in the Injured Optic Nerve in Adult Rats. Cell Transplant. 2015;24(9):1829-44
Böhm MR, Prokosch V, Brückner M, Pfrommer S, Melkonyan H, Thanos S
(See online at https://doi.org/10.3727/096368914X684583) - Is Angiostatin Involved in Physiological Foveal Avascularity? Invest Ophthalmol Vis Sci. 2016 Sep 1;57(11):4536-52
Böhm MR, Hodes F, Brockhaus K, Hummel S, Schlatt S, Melkonyan H, Thanos S
(See online at https://doi.org/10.1167/iovs.16-19286) - The pro-inflammatory role of high-mobility group box 1 protein (HMGB-1) in photoreceptors and retinal explants exposed to elevated pressure. Lab Invest. 2016 Apr;96(4):409-27
Böhm MR, Schallenberg M, Brockhaus K, Melkonyan H, Thanos S
(See online at https://doi.org/10.1038/labinvest.2015.156) - Analysis of Histone Deacetylase-Dependent Effects on Cell Migration Using the Stripe Assay. Methods Mol Biol. 2017;1510:61-75
Mertsch S, Thanos S
(See online at https://doi.org/10.1007/978-1-4939-6527-4_5) - Elevated Intraocular Pressure Induces Cellular Responses in the Retinal Capillaries. Klin Monbl Augenheilkd. 2017 May 3
Brockhaus K, Melkonyan H, Prokosch V, Thanos S
(See online at https://dx.doi.org/10.1055/s-0043-105270) - The Aging Retina in the Context of Cerebral Neurodegenerative Diseases. Klin Monbl Augenheilkd. 2017 Jun 9
Böhm MRR, Thanos S
(See online at https://dx.doi.org/10.1055/s-0043-105266)
