Intravitreal injection of soluble erythropoietin receptor exacerbates photoreceptor cell apoptosis in a rat model of retinal detachment

Use of erythropoietin in ophthalmology: a review

Erythropoietin (EPO) is a glycoprotein hormone that regulates hematopoiesis in the human body. The presence of EPO and its receptors in different tissues indicates that this hormone has extramedullary effects in other tissues, including the eye. We focus on the biological roles of this hormone in the development and normal physiologic functions of the eye. Furthermore, we explore the role of EPO in the management of different ocular diseases - including diabetic retinopathy, retinopathy of prematurity, inherited retinal degeneration, branch and central retinal vein occlusion, retinal detachment, traumatic optic neuropathy, optic neuritis, methanol optic neuropathy, nonarteritic anterior ischemic optic neuropathy, glaucoma, and scleral necrosis.

Comparison of Long-Term Automated Retinal Layer Segmentation Analysis of the Macula between Silicone Oil and Gas Tamponade after Vitrectomy for Rhegmatogenous Retinal Detachment

PURPOSE

To identify long-term changes in individual retinal layer thickness using automated retinal layer segmentation analysis on high-resolution spectral-domain optical coherence tomography (SD-OCT) scans of eyes with macula-off rhegmatogenous retinal detachment (RRD) treated with vitreoretinal surgery (VRS) and gas or silicone oil tamponade and having single-operation success.

METHODS

A total of 58 patients operated on by VRS for RRD and followed up for 12 months were imaged by SD-OCT. The patients with retinal diseases such as an epiretinal membrane or cystic macular edema in the operated and fellow eyes were excluded. The thicknesses of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor layer, and retinal pigment epithelium were compared to those of the fellow eyes after the 12-month follow-up. Thickness changes in individual layers were quantitatively analyzed in the operated and fellow eyes and correlated with the type of tamponade used in the surgery.

RESULTS

Spectralis OCT automated segmentation software was used for the retinal layer analysis. There were 22 females and 36 males. Their mean age was 60.7 ± 11.2 years. The mean central macular thickness was 214.3 ± 29.5 µm in the operated and 229.7 ± 21.7 µm in the fellow eyes (p = 0.008). There was a statistically significant difference between the operated and the healthy fellow eyes in the following layers: the RNFL (p = 0.017), GCL (p = 0.02), INL (p = 0.005), and ONL (p = 0.008) in the central foveal area; the RNFL (p < 0.001), INL (p = 0.017), and ONL (p = 0.022) in the perifoveal ring; and the RNFL (p < 0.001), IPL (p = 0.042), INL (p = 0.001), and OPL (p = 0.001) in the peripheral ring. The logMAR best corrected visual acuities were 2.51 ± 0.68 and 2.69 ± 0.62 at baseline and 0.60 ± 0.38 and 0.50 ± 0.38 at month 12 in the silicone oil tamponade (n = 28) and the gas tamponade (n = 30) group (p = 0.52 and p = 0.21, respectively). The foveal GCL, OPL, and ONL and the perifoveal GCL and IPL were statistically significantly thinner in the silicone oil tamponade group (p = 0.01, p = 0.046, p = 0.024, p = 0.006, and p = 0.011, respectively).

CONCLUSIONS

Significant changes were observed in the retinal layers after VRS for RRD. Individual retinal layers seem to be affected 1 year after VRS for RRD. The type of tamponade can influence the thickness of the retinal layers. The thickness of the retinal layers was significantly preserved in eyes treated with gas tamponade when compared to those treated with silicone oil tamponade in the long term. Further studies are needed to validate our results.

Interplay between Intravitreal RvD1 and Local Endogenous Sirtuin-1 in the Protection from Endotoxin-Induced Uveitis in Rats

Rat endotoxin-induced uveitis (EIU) is a well-established model of human uveitis. In this model, intravitreal injection of resolvin D1 (RvD1, 10–100–1000 ng/kg) 1 hour after subcutaneous treatment of Sprague-Dawley rats with lipopolysaccharide (LPS, 200 μg/rat) significantly prevented the development of uveitis into the eye. RvD1 dose-dependently increased the expression of sirtuin-1 (SIRT1) within the eye, while it decreased the expression of acetyl-p53 and acetyl-FOXO1. These effects were accompanied by local downregulation of some microRNAs related to the expression and activity of SIRT1. These were miR-195-5p, miR-200a-3p, miR-34a-5p, and miR-145-5p. An increase of manganese superoxide dismutase and decrease of caspase 3 were evident after RvD1 treatment. In another set of experiments, the protective effects of RvD1 (1000 ng/kg) were partly abolished by the pretreatment of the rats with EX527 (10 mg/kg/day, i.p.), a specific inhibitor of SIRT1 activity, for 7 days prior to the induction of EIU in rats. Similarly, the effects of RvD1 (1000 ng/kg) on the SIRT1 protein expression were abolished by Boc2, N-t-butoxycarbonyl-PLPLP, a specific formyl-peptide receptor type 2/lipoxin A receptor antagonist. Therefore, an interplay of the SIRT1 activity on the RvD1 mediated resolution of EIU is argued.

Protection from endotoxic uveitis by intravitreal Resolvin D1: involvement of lymphocytes, miRNAs, ubiquitin-proteasome, and M1/M2 macrophages

This study investigated the protective effects of intravitreal Resolvin D1 (RvD1) against LPS-induced rat endotoxic uveitis (EIU). RvD1 was administered into the right eye at a single injection of 5 μL volume containing 10–100–1000 ng/kg RvD1 1 h post-LPS injection (200 μg, Salmonella minnesota) into thefootpad of Sprague-Dawley rats. 24 h later, the eye was enucleated and examined for clinical, biochemical, and immunohistochemical evaluations. RvD1 significantly and dose-dependently decreased the clinical score attributed to EIU, starting from the dose of 10 ng/kg and further decreased by 100 and 1000 ng/kg. These effects were accompanied by changes in four important determinants of the immune-inflammatory response within the eye: (i) the B and T lymphocytes, (ii) the miRNAs pattern, (iii) the ubiquitin-proteasome system (UPS), and (iv) the M1/M2 macrophage phenotype. LPS+RvD1 treated rats showed reduced presence of B and T lymphocytes and upregulation of miR-200c-3p, miR 203a-3p, miR 29b-3p, and miR 21-5p into the eye compared to the LPS alone. This was paralleled by decreases of the ubiquitin, 20S and 26S proteasome subunits, reduced presence of macrophage M1, and increased presence of macrophage M2 in the ocular tissues. Accordingly, the levels of the cytokine TNF-α, the chemokines MIP1-α and NF-κB were reduced.

Inhibition of retinopathy of prematurity in rat by intravitreal injection of sorafenib

AIM

To investigate the effect of intravitreal injection administered sorafenib, a multikinase inhibitor, in a rat model of oxygen-induced retinopathy (OIR).

METHODS

Seven-day-old Sprague-Dawley rats (n=144) were randomly assigned to six groups. Group A received normal partial oxygen pressure and groups B, C, D, E and F were exposed to hyperoxia (75±2)% from postnatal 7d (P7) to P12 to induce retinopathy of prematurity. The rats in groups C, D, E and F were received intravitreal injections of either vehicle (DMSO) or sorafenib at P12 (5, 20 and 80 µg, respectively). Then they returned to normoxia after P12. The retinas were whole-mounted and imaged with a confocal microscopy. The vascular branching points were counted to quantify neovascularization at P17. Cross-sections of the retina were stained with hematoxylin and eosin (HE). The nuclei of new vessels breaking the internal limiting membrane were counted to quantify the proliferative neovascular response.

RESULTS

The retinal vessel in groups B and C turned into tortuosity and a great deal of neovascularization were observed. Sorafenib-treated rats had significantly less neovascularization as compared with vehicle-treated and control rats in a dose dependent manner (P<0.05). The number of vascular branching points in A, B, C, D, E and F were 16.50±3.90, 37.44±6.47, 37.08±5.10, 30.80±6.85, 26.08±5.08 and 19.83±3.51, respectively. The number of the nuclei of retinal new vessel in A, B, C, D, E and F were 0.22±0.42, 35.66±4.70, 35.30±4.54, 27.30±4.28, 21.41±3.53, and 7.41±2.87, respectively. There were significant difference between each group (P<0.05) except groups B and C.

CONCLUSION

In the rat OIR model, sorafenib could inhibit retinal neovascularization in a dose dependent manner.