Yandiev Y¹, Wurm A², Pannicke T², Reichenbach A², Wiedemann P¹, Bringmann A¹.
Glial cell reactivity after experimental detachment of the porcine retina.
Purpose: In the healthy retina the Muller cells play a wealth of crucial roles in supporting the neurons and their functions including potassium and water homeostasis. Detachment of the neural retina from the pigment epithelium causes photoreceptor degeneration and gliotic alterations of Muller cells. In optical coherence tomography carried out before reattachment surgery we observed the presence of cystoid spaces in the detached retina. The presence of the retinal edema was also found in animal model of retinal detachment. The aim of the present study was to determine whether the activation of Muller cells in experimental retinal detachment may contribute to edema formation.
Methods: We investigated the alterations of Muller cell in a porcine model of rhegmatogenous retinal detachment by immunohistochemistry and recording the size of their somata under osmotic stress.
Results: We found that Muller cells in detached retina showed a pronounced gliosis which was associated with a downregulation in the expression of their major potassium channel (Kir4.1). In the normal retina, Muller cells did not alter the size of their somata in response to osmotic stress. However, osmotic stress caused swelling of Muller cells in the detached retina suggesting that the rapid water transport across the Muller cells membrane was altered after retinal detachment. Osmotic swelling of Muller cells was also induced by oxidative stress and by inflammatory mediators such as arachidonic acid and prostaglandins. The swelling of Muller cells was inhibited when the production of inflammatory mediators was prevented or in the presence of triamcinolone acetonide.
Conclusions: Our data suggest that a disturbance in the water transport through Muller cells may contribute to the development of retinal degeneration and edema formation after retinal detachment. Pharmacological activation of the retinal water clearance by Muller cells, e.g. by triamcinolone, may represent an approach for the development of novel edemα-resolving drugs.