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Immune response after intermittent minimally invasive intraocular pressure elevations in an experimental animal model of glaucoma.

Gramlich OW, Teister J, Neumann M, Tao X, Beck S, von Pein HD, Pfeiffer N, Grus FH - J Neuroinflammation (2016)

Bottom Line: A wavelike IOP profile led to a significant neurodegeneration of optic nerve axons (-10.6 %, p < 0.001) and RGC (-19.5 %, p = 0.02) in iOHT eyes compared with fellow eyes.Belimumab-treated animals only showed slightly higher axonal survival and reduced serum IgG concentration (-29 %) after iOHT.Neuroinflammatory events, indicated by significantly upregulated microglia activation and IgG autoantibody depositions, were shown in all injured retinas.

View Article: PubMed Central - PubMed

Affiliation: Experimental Ophthalmology, Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstr. 1, 55131, Mainz, Germany.

ABSTRACT

Background: Elevated intraocular pressure (IOP), as well as fluctuations in IOP, is a main risk factor for glaucoma, but its pathogenic effect has not yet been clarified. Beyond the multifactorial pathology of the disease, autoimmune mechanisms seem to be linked to retinal ganglion cell (RGC) death. This study aimed to identify if intermittent IOP elevations in vivo (i) elicit neurodegeneration, (ii) provokes an immune response and (iii) whether progression of RGC loss can be attenuated by the B lymphocyte inhibitor Belimumab.

Methods: Using an intermittent ocular hypertension model (iOHT), Long Evans rats (n = 21) underwent 27 unilateral simulations of a fluctuating pressure profile. Nine of these animals received Belimumab, and additional seven rats served as normotensive controls. Axonal density was analyzed in PPD-stained optic nerve cross-sections. Retinal cross-sections were immunostained against Brn3a, Iba1, and IgG autoantibody depositions. Serum IgG concentration and IgG reactivities were determined using ELISA and protein microarrays. Data was analyzed using ANOVA and Tukey HSD test (unequal N) or student's independent t test by groups.

Results: A wavelike IOP profile led to a significant neurodegeneration of optic nerve axons (-10.6 %, p < 0.001) and RGC (-19.5 %, p = 0.02) in iOHT eyes compared with fellow eyes. Belimumab-treated animals only showed slightly higher axonal survival and reduced serum IgG concentration (-29 %) after iOHT. Neuroinflammatory events, indicated by significantly upregulated microglia activation and IgG autoantibody depositions, were shown in all injured retinas. Significantly elevated serum autoantibody immunoreactivities against glutathione-S-transferase, spectrin, and transferrin were observed after iOHT and were negatively correlated to the axon density.

Conclusions: Intermittent IOP elevations are sufficient to provoke neurodegeneration in the optic nerve and the retina and elicit changes of IgG autoantibody reactivities. Although the inhibition of B lymphocyte activation failed to ameliorate axonal survival, the correlation between damage and changes in the autoantibody reactivity suggests that autoantibody profiling could be useful as a biomarker for glaucoma.

No MeSH data available.


Related in: MedlinePlus

Analysis of IgG autoantibody depositions. a Autoantibody depositions were analyzed as immunoglobulin G (IgG)-positive depositions per mm retina in naso-temporal cross-sections of the eye. A significant increase of IgG autoantibody depositions could be observed in fellow and injured eyes of the iOHT group (p < 0.05 and p < 0.01, respectively) compared with control eyes, but not in iOHT + Belimumab group. Significant values are indicated as follows: *p < 0.05, **p < 0.01. b–f Representative images of retinal cross-sections (×20 magnification) show distinct IgG-positive depositions (arrows) in the ganglion cell layer of the retina. Magnifications highlight the dense morphology of these depositions (b, d, and f). Triangles indicate IgG-positive blood vessels containing erythrocytes, which must not be confused with IgG depositions. Abbreviations: GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer, CHO choroid. Scale bar represents 100 μm. Significant values are indicated as follows: *p < 0.05, **p < 0.01
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Fig5: Analysis of IgG autoantibody depositions. a Autoantibody depositions were analyzed as immunoglobulin G (IgG)-positive depositions per mm retina in naso-temporal cross-sections of the eye. A significant increase of IgG autoantibody depositions could be observed in fellow and injured eyes of the iOHT group (p < 0.05 and p < 0.01, respectively) compared with control eyes, but not in iOHT + Belimumab group. Significant values are indicated as follows: *p < 0.05, **p < 0.01. b–f Representative images of retinal cross-sections (×20 magnification) show distinct IgG-positive depositions (arrows) in the ganglion cell layer of the retina. Magnifications highlight the dense morphology of these depositions (b, d, and f). Triangles indicate IgG-positive blood vessels containing erythrocytes, which must not be confused with IgG depositions. Abbreviations: GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer, CHO choroid. Scale bar represents 100 μm. Significant values are indicated as follows: *p < 0.05, **p < 0.01

Mentions: The analysis of retinal IgG autoantibody depositions revealed twice the amount of autoantibodies in the eyes of iOHT animals compared with controls and a more modest increase of autoantibody deposits in eyes of animals that received Belimumab (Fig. 5a, Table 1). The majority of these were located in the ganglion cell layer, and extravasal IgG autoantibody depositions were easily identified based upon their dense formations in the absence of blood vessel. No IgG autoantibody depositions were observed in the outer nuclear layer. In comparison to control eyes with 0.5 ± 0.4 IgG autoantibody depositions per mm retina, the number of IgG autoantibody depositions was significantly higher in eyes that underwent iOHT (1.3 ± 0.6, p = 0.002) as well as in fellow eyes (1.1 ± 0.4, p = 0.045). Animals that received Belimumab showed higher, though not statistically significant, levels of IgG autoantibody depositions in iOHT eyes (0.9 ± 0.4, p = 0.3) as well as in their fellow eyes (0.9 ± 0.2, p = 0.3, Fig. 5b–f) compared with control eyes.Fig. 5


Immune response after intermittent minimally invasive intraocular pressure elevations in an experimental animal model of glaucoma.

Gramlich OW, Teister J, Neumann M, Tao X, Beck S, von Pein HD, Pfeiffer N, Grus FH - J Neuroinflammation (2016)

Analysis of IgG autoantibody depositions. a Autoantibody depositions were analyzed as immunoglobulin G (IgG)-positive depositions per mm retina in naso-temporal cross-sections of the eye. A significant increase of IgG autoantibody depositions could be observed in fellow and injured eyes of the iOHT group (p < 0.05 and p < 0.01, respectively) compared with control eyes, but not in iOHT + Belimumab group. Significant values are indicated as follows: *p < 0.05, **p < 0.01. b–f Representative images of retinal cross-sections (×20 magnification) show distinct IgG-positive depositions (arrows) in the ganglion cell layer of the retina. Magnifications highlight the dense morphology of these depositions (b, d, and f). Triangles indicate IgG-positive blood vessels containing erythrocytes, which must not be confused with IgG depositions. Abbreviations: GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer, CHO choroid. Scale bar represents 100 μm. Significant values are indicated as follows: *p < 0.05, **p < 0.01
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4836145&req=5

Fig5: Analysis of IgG autoantibody depositions. a Autoantibody depositions were analyzed as immunoglobulin G (IgG)-positive depositions per mm retina in naso-temporal cross-sections of the eye. A significant increase of IgG autoantibody depositions could be observed in fellow and injured eyes of the iOHT group (p < 0.05 and p < 0.01, respectively) compared with control eyes, but not in iOHT + Belimumab group. Significant values are indicated as follows: *p < 0.05, **p < 0.01. b–f Representative images of retinal cross-sections (×20 magnification) show distinct IgG-positive depositions (arrows) in the ganglion cell layer of the retina. Magnifications highlight the dense morphology of these depositions (b, d, and f). Triangles indicate IgG-positive blood vessels containing erythrocytes, which must not be confused with IgG depositions. Abbreviations: GCL ganglion cell layer, INL inner nuclear layer, ONL outer nuclear layer, CHO choroid. Scale bar represents 100 μm. Significant values are indicated as follows: *p < 0.05, **p < 0.01
Mentions: The analysis of retinal IgG autoantibody depositions revealed twice the amount of autoantibodies in the eyes of iOHT animals compared with controls and a more modest increase of autoantibody deposits in eyes of animals that received Belimumab (Fig. 5a, Table 1). The majority of these were located in the ganglion cell layer, and extravasal IgG autoantibody depositions were easily identified based upon their dense formations in the absence of blood vessel. No IgG autoantibody depositions were observed in the outer nuclear layer. In comparison to control eyes with 0.5 ± 0.4 IgG autoantibody depositions per mm retina, the number of IgG autoantibody depositions was significantly higher in eyes that underwent iOHT (1.3 ± 0.6, p = 0.002) as well as in fellow eyes (1.1 ± 0.4, p = 0.045). Animals that received Belimumab showed higher, though not statistically significant, levels of IgG autoantibody depositions in iOHT eyes (0.9 ± 0.4, p = 0.3) as well as in their fellow eyes (0.9 ± 0.2, p = 0.3, Fig. 5b–f) compared with control eyes.Fig. 5

Bottom Line: A wavelike IOP profile led to a significant neurodegeneration of optic nerve axons (-10.6 %, p < 0.001) and RGC (-19.5 %, p = 0.02) in iOHT eyes compared with fellow eyes.Belimumab-treated animals only showed slightly higher axonal survival and reduced serum IgG concentration (-29 %) after iOHT.Neuroinflammatory events, indicated by significantly upregulated microglia activation and IgG autoantibody depositions, were shown in all injured retinas.

View Article: PubMed Central - PubMed

Affiliation: Experimental Ophthalmology, Department of Ophthalmology, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstr. 1, 55131, Mainz, Germany.

ABSTRACT

Background: Elevated intraocular pressure (IOP), as well as fluctuations in IOP, is a main risk factor for glaucoma, but its pathogenic effect has not yet been clarified. Beyond the multifactorial pathology of the disease, autoimmune mechanisms seem to be linked to retinal ganglion cell (RGC) death. This study aimed to identify if intermittent IOP elevations in vivo (i) elicit neurodegeneration, (ii) provokes an immune response and (iii) whether progression of RGC loss can be attenuated by the B lymphocyte inhibitor Belimumab.

Methods: Using an intermittent ocular hypertension model (iOHT), Long Evans rats (n = 21) underwent 27 unilateral simulations of a fluctuating pressure profile. Nine of these animals received Belimumab, and additional seven rats served as normotensive controls. Axonal density was analyzed in PPD-stained optic nerve cross-sections. Retinal cross-sections were immunostained against Brn3a, Iba1, and IgG autoantibody depositions. Serum IgG concentration and IgG reactivities were determined using ELISA and protein microarrays. Data was analyzed using ANOVA and Tukey HSD test (unequal N) or student's independent t test by groups.

Results: A wavelike IOP profile led to a significant neurodegeneration of optic nerve axons (-10.6 %, p < 0.001) and RGC (-19.5 %, p = 0.02) in iOHT eyes compared with fellow eyes. Belimumab-treated animals only showed slightly higher axonal survival and reduced serum IgG concentration (-29 %) after iOHT. Neuroinflammatory events, indicated by significantly upregulated microglia activation and IgG autoantibody depositions, were shown in all injured retinas. Significantly elevated serum autoantibody immunoreactivities against glutathione-S-transferase, spectrin, and transferrin were observed after iOHT and were negatively correlated to the axon density.

Conclusions: Intermittent IOP elevations are sufficient to provoke neurodegeneration in the optic nerve and the retina and elicit changes of IgG autoantibody reactivities. Although the inhibition of B lymphocyte activation failed to ameliorate axonal survival, the correlation between damage and changes in the autoantibody reactivity suggests that autoantibody profiling could be useful as a biomarker for glaucoma.

No MeSH data available.


Related in: MedlinePlus