ROCK inhibition reduces morphological and functional damage to rod synapses after retinal injury

Abstract

Retinal detachment (RD) causes damage, including disjunction, of the rod photoreceptor-bipolar synapse, which disrupts vision and may contribute to the poor visual recovery observed after retinal reattachment surgery. We created a model of iatrogenic RD in adult female pigs to study damage to the rod-bipolar synapse after injury and the ability of a highly specific Rho-kinase (ROCK) inhibitor to preserve synaptic structure and function. This model mimics procedures used in humans when viral vectors or cells are injected subretinally for treatment of retinal disease. Synaptic disjunction by retraction of rod spherules, quantified by image analysis of confocal sections, was present 2 h after detachment and remained 2 days later even though the retina had spontaneously reattached by then. Moreover, spherule retraction occurred in attached retina 1–2 cms from detached retina. Synaptic damage was significantly reduced by ROCK inhibition in detached retina whether injected subretinally or intravitreally. Dark-adapted full-field electroretinograms were recorded in reattached retinas to assess rod-specific function. Reduction in synaptic injury correlated with increases in rod-driven responses in drug-treated eyes. Thus, ROCK inhibition helps prevent synaptic damage and improves functional outcomes after retinal injury and may be a useful adjunctive treatment in iatrogenic RD and other retinal degenerative diseases.

Retinal damage extends beyond the border of the detached retina in fovea‐on retinal detachment

“…This prospective study showed that the retinal damage induced by a RD is not restricted to the detached retina, but extends beyond the border to the attached retina in patients with fovea‐on retinal detachment. This supports the findings of previous animal studies by Halász, Lee and Francke who demonstrated that retinal damage is found not only in the detached retina but in lesser extent also in the attached retina (Francke et al, 2005; Halász et al, 2021; Lee et al, 2021).…”

“…Hence, we hypothesize that the loss of retinal function in the attached retina is due to cellular damage mechanisms in the detached retina which spreads into the attached retina. Our hypothesis is supported by previous animal studies which have reported damage to the synapse between photoreceptor and bipolar cells in both attached and detached retina (Halász et al, 2021; Townes‐Anderson et al, 2017; Wang et al, 2016). This synaptic damage is due to rods retracting their presynaptic terminals and cones losing their synaptic invaginations (Halász et al, 2020).…”

“…Animal studies reported that within 12 h of RD, photoreceptor degeneration occurs in the detached retina and peaks at 2 days after RD (Arroyo et al, 2005; Wickham et al, 2018). Furthermore, animal models have also shown that photoreceptor damage is not restricted to the detached retina, but is also present at the border of the RD and in a lesser extent in the attached retina (Francke et al, 2005; Halász et al, 2021; Lee et al, 2021). These results suggest that retinal damage induced by the RD extends beyond the detached retina and can proceed towards the fovea.…”

Effects of Rho-Associated Kinase (Rock) Inhibitors (Alternative to Y-27632) on Primary Human Corneal Endothelial Cells

“…At the concentration of 1 µM of AR-13503, statistical significance was achieved when the proliferation rates were compared against untreated CECs (p < 0.05). A recent study reported a lower dose of AR-13503 to be effective at greater than 1000 times than Y-27632, and suggested the efficacy of this lower dosage to be highly specific for the effects against ROCK [66]; it is currently assessed as an implantable in subjects with neovascular age-related macular degeneration or diabetic macular edema (NCT03835884). Indeed, the results observed in the current study suggests that when used at a higher concentration of 10 µM, AR-13503 may be a suitable molecule for the purpose of corneal endothelial cell expansion protocols and cellular therapeutics, and it is currently the subject of further investigation.…”

Small-Molecule-Directed Endogenous Regeneration of Visual Function in a Mammalian Retinal Degeneration Model

“…The following kinases were inhibited by more than 75% with 5 µM CompA: PKG1α, ROCK-I, p70S6K, and PKA (Supplementary Figure S1A). In addition to the roles in the aforementioned signaling pathways, these kinases have been implicated in retinal cell proliferation, function, and pathophysiology [24][25][26][27].…”