Neuroprotective effects of antibodies on retinal ganglion cells in an adolescent retina organ culture

Abstract

Glaucoma, a neurodegenerative disease, is characterized by a progressive loss of retinal ganglion cells (rgc). Up- and down-regulated autoantibody immunoreactivities in glaucoma patients have been demonstrated. Previous studies showed protective effects of down-regulated antibodies [gamma (γ)-synuclein and glial fibrillary acidic protein [GFAP]) on neuroretinal cells. The aim of this study was to test these protective antibody effects on rgc in an organ culture model and to get a better understanding of cell-cell interactions of the retina in the context of the protective effect. We used an adolescent retinal organ culture (pig) with an incubation time of up to 4 days. Retinal explants were incubated with different antibodies for 24 h (anti-GFAP, anti-γ-synuclein and anti-myoglobin antibody as a control). Brn3a and TUNEL staining were performed. We also conducted glutamine synthetase staining and quantification of the retinal explants. Mass spectrometry analyses were performed as well as protein analyses via microarray. We detected a continuous decrease of rgc/mm in the retinal explants throughout the 4 days of incubation with increased TUNEL rgc staining. Immunohistochemical analyses showed a protective effect of anti-γ-synuclein (increased rgc/mm of 41%) and anti-GFAP antibodies (increased rgc/mm of 37%). Mass spectrometric, microarray and immunohistochemical analyses demonstrated Müller cell involvement and decreased endoplasmic reticulum stress response in the antibody-treated retinae. We could detect that the tested antibodies have a protective effect on rgc which seems to be the result of reduced stress levels in the retina as well as a shift of glutamine synthetase localization in the endfeet of the Müller cells towards the inner retinal layer. Loss of retinal ganglion cells (rgc) in glaucoma leads to blindness. Several antibodies are down-regulated in glaucoma patients. Our aim was to test if these antibodies have a protective effect of rgc in a retinal organ culture. This could be shown with an increase of rgc numbers. This effect results through reduced stress levels and the shift of glutamine synthetase localization.

Establishing a Surgical Procedure for Rhesus Epiretinal Scaffold Implantation with HiPSC-Derived Retinal Progenitors

“…Another previous study showed that the gliosis may impede the migration and integration of transplanted photoreceptors [ 21 ]. Additionally, in vitro studies indicated that anti-inflammation treatment including rapamycin not only reduced local inflammation and proliferation, but also provided a protective effect of neurons [ 22 , 23 ]. Consistently, with weekly intravitreous rapamycin injection, the slight glial reaction induced by retinal tack was notably improved in present surgery.…”

Current Medical Therapy and Future Trends in the Management of Glaucoma Treatment

“…Autoantibodies changes detected include elevated levels of antibodies against α -fodrin, glutathione-S-transferase, spectrin, and Heat Shock Protein (HSP) 70 and decreased levels of antibodies against α B crystalline, vimentin, Glial Fibrillary Acidic Protein (GFAP), and ϒ-Synuclein [ 102 – 105 ]. In vitro studies have shown that antibodies against ϒ-Synuclein and GFAP possess direct and indirect (through Mϋller cells) protective effect on the retinal ganglion cells [ 106 ]. Results from clinical studies revealed altered immunoreactivities against retina and optic nerve in sera and aqueous humour of glaucoma patients which indicates a role of autoimmunity in glaucomatous neurodegeneration and retinal ganglion cells death.…”

Biomarkers for glaucoma: from the lab to the clinic

“…In accordance with previous results, immunohistochemical analysis revealed a protective effect of anti-γ-synuclein and anti-GFAP antibodies on RGC survival (Figure 3) and demonstrated the uptake of γ-synuclein antibodies, as well as the binding of GFAP antibodies to the cell membrane of Müller cells. 47 Furthermore, mass spectrometric results showed Eye increased levels of glutamine synthetase in antibodytreated retinal explants. Glutamine synthetase is expressed exclusively in Müller cells and serves as a specific Müller cell marker.…”

“…These findings suggest that anti-GFAP and anti-γ-synuclein antibodies have a protective effect on RGC which seems to be the result of reduced stress levels in the retina. 47 Possibly the absence or the loss of some autoantibodies in glaucoma patients (eg, anti-GFAP) reflects a loss of natural protective autoimmunity, thus encouraging neurodegenerative processes and making the RGC more vulnerable for stress factors. 12…”