Erhöhter Intraokulardruck induziert primär zelluläre Reaktionen in den retinalen Kapillaren

Zusammenfassung

Hintergründe In der Frühdiagnostik des klinischen Glaukoms sind peripapilläre Blutungen fast pathognomonisch für eine Schädigung von Kapillaren. Auch in der Perfusionsdiagnostik herrscht überwiegend die Meinung, dass Perfusionsstörungen und Gefäßveränderungen vorliegen, die im Circulus vitiosus der IOD-Erhöhung (IOD: Intraokulardruck) eine wesentliche Rolle spielen. Damit sind wahrscheinlich die biomechanischen Besonderheiten der Papille sowie die zellulären Reaktionen von Astrozyten, Müller-Zellen, Endothelzellen, Mikroglialzellen und Perizyten assoziiert.

Material und Methoden Wir stellen In-vivo- und Ex-vivo-Modelle für IOD-Erhöhungen vor, um die Auflösung unserer Betrachtungsweise bis hin zur zellulären und gar molekularen Reaktion zu erhöhen und Mechanismen der Kapillarzellveränderungen als Folge von IOD-Erhöhung zu verifizieren.

Ergebnisse Als Tiermodell diente die kauterisationsbedingte Erhöhung des IOD im Rattenauge. Es wurden 2–3 Episkleralvenen kauterisiert, um den Abflusswiderstand zu erhöhen. Nach Analyse der Netzhäute einige Wochen danach fanden wir eine anormale Expression des ansonsten neuronalspezifischen Moleküls Beta-III-Tubulin in den Kapillarendothelzellen und in den Gefäß- und Kapillarperizyten. Kombinierte immunhistochemische Anfärbungen mit verschiedenen Markern für unterschiedliche Zelltypen bestätigten die Befunde. Die Isolierung von kapillären Endothelzellen und Perizyten aus Rattengehirnen (BMECs) und Retinae (RMECs) und deren In-vitro-Kultivierung unter erhöhten Druckbedingungen in einer eigens konstruierten Druckkammer bestätigten den In-vivo-Befund.

Schlussfolgerung Die unerwartete kapilläre Reaktion auf die Erhöhung des IOD in vivo bzw. des Kultivierungsdrucks in vitro kann gegenwärtig als eine frühe Reaktion der Zellen mit Expression anormaler Proteine gedeutet werden. Dieser Befund mag bisherige klinische Beobachtungen erklären, die als peripapilläre Blutungen oder Mikroinfarkte imponieren und wahrscheinlich mit der Optikopathie einhergehen.

Abstract

Background In the early diagnosis of clinical glaucoma, peripapillary bleedings were almost pathognomonic for a capillary insult. In the perfusion diagnostics, it is predominantly accepted that perfusion imbalances and IOP-induced changes occur and play a crucial role. Biomechanical peculiarities of the optic nerve head and cellular responses to astrocytes are also likely involved.

Material and Methods We present in vivo and ex vivo models of IOP-elevation to enhance the resolution of examining cellular and molecular changes and to understand the mechanisms of capillary changes due to IOP-elevation.

Results The in vivo model consists of cauterization-caused elevation of IOP in rat eyes. Two to 3 veins were cauterized to increase outflow resistance. The retinas were analyzed several weeks later and we found an abnormal expression of the neuron-specific molecule beta-III-tubulin in the capillary endothelium cells and in the vascular pericytes. Combined immunohistochemical stainings with different markers for various retinal cells confirmed the findings. The isolation of capillary endothelium cells and pericytes from rat brains (BMECs) and retinas (RMECs), and their cultivation under elevated IOP in vitro, confirmed the in vivo results.

Conclusion The unexpected capillary response to elevation of IOP in vivo and in vitro could be seen as an early response of cells with expression of abnormal proteins. This result may explain clinical observations which dominate as peripapillary bleedings or microinfarctions and are likely associated with the glaucoma-induced opticopathy.

Schlüsselwörter

Glaukom - Retina - Kapillaren - Perizyten - Endothelzellen

Key words

glaucoma - retina - capillaries - pericytes - endothelial cells

• Literatur

• 1 Jonas JB, Berenstein E, Holbach L. Lamina cribrosa thickness and spatial relationships between intraocular space and cerebrospinal fluid space in highly myopic eyes. Invest Ophthalmol Vis Sci 2004; 45: 2660-2665
• 2 Jonas JB, Martus P, Budde WM. et al. Morphologic predictive factors for development of optic disc hemorrhages in glaucoma. Invest Ophthalmol Vis Sci 2002; 43: 2956-2961
• 3 Kornzweig AL, Eliasoph I, Feldstein M. Selective atrophy of the radial peripapillary capillaries in chronic glaucoma. Arch Ophthalmol 1968; 80: 696-702
• 4 Kur J, Newman EA, Chan-Ling T. Cellular and physiological mechanisms underlying blood flow regulation in the retina and choroid in health and disease. Prog Retin Eye Res 2012; 31: 377-406
• 5 Kutcher ME, Kolyada AY, Surks HK. et al. Pericyte Rho GTPase mediates both pericyte contractile phenotype and capillary endothelial growth state. Am J Pathol 2007; 171: 693-701
• 6 Murfee WL, Rehorn MR, Skalak TC. et al. Perivascular cells along venules upregulate NG2 expression during microvascular remodeling. Microcirculation 2006; 13: 261-273
• 7 Ozerdem U, Monosov E, Stallcup WB. NG2 proteoglycan expression by pericytes in pathological microvasculature. Microvasc Res 2002; 63: 129-134
• 8 Pournaras CJ, Rungger-Brändle E, Riva CE. et al. Regulation of retinal blood flow in health and disease. Progr Ret Eye Res 2008; 27: 284-330
• 9 Prasanna G, Krishnamoorthy R, Yorio T. Endothelin, astrocytes and glaucoma. Exp Eye Res 2011; 93: 170-177
• 10 Resch H, Garhofer G, Fuchsjäger-Mayrl G. et al. Endothelial dysfunction in glaucoma. Acta Ophthalmol 2009; 87: 4-12
• 11 Downs JC, Roberts MD, Burgoyne CF. Mechanical environment of the optic nerve head in glaucoma. Optom Vis Sci 2008; 85: 425-435
• 12 Trost A, Lange S, Schroedl F. et al. Brain and retinal pericytes: origin, function and role. Front Cell Neurosci 2016; 10: 20
• 13 Trost A, Motloch K, Bruckner D. et al. Time-dependent retinal ganglion cell loss, microglial activation and blood-retina-barrier tightness in an acute model of ocular hypertension. Exp Eye Res 2015; 136: 59-71
• 14 Bianchi E, Ripandelli G, Feher J. et al. Occlusion of retinal capillaries caused by glial cell proliferation in chronic ocular inflammation. Folia Morphol (Warsz) 2015; 74: 33-41
• 15 Funk RH. [Functional differences in the microcirculatory units of the eye]. Klin Monatsbl Augenheilkd 2015; 232: 133-140
• 16 Flammer J. The vascular concept of glaucoma. Surv Ophthalmol 1994; 38: 3-6
• 17 Flammer J, Haefliger IO, Orgül S. et al. Vascular dysregulation: a principal risk factor for glaucomatous damage?. J Glaucoma 1999; 8: 212-219
• 18 Chauhan BC, LeVatte TL, Jollimore CA. et al. Model of endothelin-1-induced chronic optic neuropathy in rat. Invest Ophthalmol Vis Sci 2004; 45: 144-152
• 19 Sugiyama T, Moriya S, Oku H. et al. Association of endothelin-1 with normal tension glaucoma clinical and fundamental studies. Surv Ophthalmol 1995; 39: 49-56
• 20 Kaiser HJ, Flammer J, Wenk M. et al. Endothelin-1 plasma levels in normal-tension glaucoma: abnormal response to postural changes. Graefes Arch Clin Exp Ophthalmol 1995; 233: 484-488
• 21 Voelzmann A, Hahn I, Pearce SP. et al. A conceptual view at microtubule plus end dynamics in neuronal axons. Brain Res Bull 2016; 126: 226-237
• 22 Anderson DR, Davis EB. Glaucoma, capillaries and pericytes. 2. Identification and characterization of retinal pericytes in culture. Ophthalmologica 1996; 210: 263-268
• 23 Ponce AM, Price RJ. Angiogenic stimulus determines the positioning of pericytes within capillary sprouts in vivo. Microvasc Res 2003; 65: 45-48
• 24 Puro DG. Physiology and pathobiology of the pericyte-containing retinal microvasculature: new developments. Microcirculation 2007; 14: 1-10
• 25 Chakraborti S, Natarajan K, Curiel J. et al. The emerging role of the tubulin code: from the tubulin molecule to neuronal function and disease. Cytoskeleton (Hoboken) 2016; 73: 521-550
• 26 Piermarini E, Cartelli D, Pastore A. et al. Frataxin silencing alters microtubule stability in motor neurons: implications for Friedreichʼs ataxia. Hum Mol Genet 2016; 25: 4288-4301
• 27 Vinores SA, Derevjanik NL, Mahlow J. et al. Class III beta-tubulin in human retinal pigment epithelial cells in culture and in epiretinal membranes. Exp Eye Res 1995; 60: 385-400
• 28 Sharma RK, Netland PA. Early born lineage of retinal neurons express class III beta-tubulin isotype. Brain Res 2007; 1176: 7-11
• 29 Katsetos CD, Legido A, Perentes E. et al. Class III beta-tubulin isotype: a key cytoskeletal protein at the crossroads of developmental neurobiology and tumor neuropathology. J Child Neurol 2003; 18: 851-866
• 30 Stapor PC, Murfee WL. Identification of class III β-tubulin as a marker of angiogenic perivascular cells. Microvasc Res 2012; 83: 257-262
• 31 Weinstein BM. Vessels and nerves: marching to the same tune. Cell 2005; 120: 299-302
• 32 Tischfeld MA, Baris HN, Wu C. et al. Human TUBB3 mutations perturb microtubule dynamic, kinesin interactions, and axon guidance. Cell 2010; 140: 74-87
• 33 Furuyoshi N, Furuyoshi M, May CA. et al. Vascular and glial changes in the retrolaminar optic nerve in glaucomatous monkey eyes. Ophthalmologica 2000; 214: 24-32
• 34 Gerhardt H, Betsholtz C. Endothelial-pericyte interactions in angiogenesis. Cell Tissue Res 2003; 314: 15-23
• 35 Hirschi KK, DʼAmore PA. Pericytes in the microvasculature. Cardiovasc Res 1996; 32: 687-698
• 36 Findl O, Rainer G, Dallinger S. et al. Assessment of optic disk blood flow in patients with open-angle glaucoma. Am J Ophthalmol 2000; 130: 589-596
• 37 Prokosch V, Fink J, Heiduschka P. et al. VEGF, Ang-2 and SRIF associated abnormal postnatal development of the retinal capillary network in the Royal College of Surgeons rat. Exp Eye Res 2011; 92: 128-137