Cu-Doping Layered Double Hydroxides Nanozyme Integrated with Nitric Oxide Donor for Enhanced Antioxidant Therapy in Retinopathy.

The prevalence of retinal neovascular diseases necessitates novel treatments beyond current therapies like laser surgery or anti-VEGF treatments, which often carry significant side effects. A novel therapeutic approach is introduced using copper-containing layered double hydroxides (Cu-LDH) nanozymes integrated with nitric oxide-releasing molecules (GSHNO), forming Cu-LDH@GSHNO aimed at combating oxidative stress within the retinal vascular system. Combination of synthetic chemistry and biological testing, Cu-LDH@GSHNO are synthesized, characterized, and assessed for curative effect in HUVECs and an oxygen-induced retinopathy (OIR) mouse model. The results indicate that Cu-LDH@GSHNO demonstrates SOD-CAT cascade catalytic ability, accompanied with GSH and nitric oxide-releasing capabilities, which significantly reduces oxidative cell damage and restores vascular function, presenting a dual-function strategy that enhances treatment efficacy and safety for retinal vascular diseases. The findings encourage further development and clinical exploration of nanozyme-based therapies, promising a new horizon in therapeutic approaches for managing retinal diseases driven by oxidative stress.

Mitochondria-targeted nanozymes eliminate oxidative damage in retinal neovascularization disease.

Retinal neovascularization is typically accompanied by hypoxia-induced oxidative injury in the vascular system. This study developed an ultrasmall (6-8 nm) platinum (Pt) nanozyme loaded mitochondria-targeted liposome (Pt@MitoLipo) to alleviate hypoxia and eliminate excess reactive oxygen species (ROS) for effective retinal neovascularization disease therapy. Pt nanozymes possess superoxide dismutase (SOD) and catalase (CAT) cascade enzyme-like activities, which convert cytotoxic O2•- and H2O2 into nontoxic H2O and O2. Triphenylphosphonium (TPP)-conjugated liposomes were coated on the surface of Pt nanozymes to increase their biocompatibility and help them penetrate the cell membrane, escape from the lysosomal barrier, and target mitochondria, thus achieving precise scavenging of mitochondrial O2•- and relief from hypoxia. Using an oxygen-induced retinopathy (OIR) mouse model, we demonstrated that Pt@MitoLipo nanozymes significantly suppressed hypoxia-induced abnormal neovascularization and facilitated avascular normalization of the retina in vivo without any noticeable toxicity. This study provides a promising way to break through cellular barriers and target scavenging mitochondrial O2•- and illustrates the potential of ROS-scavenging and hypoxia relief in retinal neovascularization disease therapy.

OCT of Outer Retinal Hyperreflectivity, Neovascularization, and Pigment in Macular Telangiectasia Type 2.

PURPOSE: To investigate whether outer retina hyperreflectivity (ORHR) and outer retina neovascularization (ORNV) are visible in eyes with macular telangiectasia type 2 (MacTel 2) before pigment proliferation is visible. DESIGN: Retrospective study in a cohort of patients from the MacTel Project. PARTICIPANTS: Thirty-nine MacTel 2 eyes without pigment on color fundus photography (CFP) at presentation were studied over a mean of 36.6 months (range, 13.8-50.4 months; standard deviation, ±10 months). METHODS: All patients routinely underwent Snellen best-corrected visual acuity (VA) measurement, CFP, spectral-domain OCT, and OCT angiography (OCTA). MAIN OUTCOME MEASURES: Pigment in the macula on CFP, best-corrected VA, presence of ORHR, presence of ORNV, presence and surface of ellipsoid zone (EZ) loss, and occurrence of ORHR, ORNV, and pigment. RESULTS: At presentation, 13 eyes showed no EZ loss, and no ORHR nor change was observed during the follow-up. In the 19 eyes with only EZ loss at baseline, ORHR appeared in 6 eyes, and one of them also showed visible pigment on CFP. Among the 7 eyes with ORHR and ORNV at baseline, pigment proliferation became visible in 4 eyes. Overall, at the end of follow-up, 14 eyes showed ORNV and 13 showed ORHR, of which 5 showed pigment on CFP. In all cases, ORHR on spectral-domain OCT corresponded to ORNV on OCTA. Hyperreflectivity and neovascularization developed within an EZ loss area or at its edge. At the end of follow-up, although the EZ loss area was larger in eyes with ORHR, pigment, or both than in eyes without any pigment migration (0.33 mm2 vs. 0.94 mm2; P = 0.01), VA was similar in both groups (0.32 logarithm of the minimum angle of resolution [logMAR] vs. 0.35 logMAR; Snellen equivalent, 20/40 vs. 20/50; P = 0.64). CONCLUSIONS: Spectral-domain OCT and OCTA showed that in MacTel 2 eyes, ORHR was associated with ORNV on OCTA and most often did not correspond to pigmentation on CFP. When ORNV developed, hyperreflectivity appeared along the abnormal capillary tracts after a mean follow-up of 36 months. In most cases, the presence of ORHR was not associated with rapid vision loss.

Safety and tolerability evaluation after repeated intravitreal injections of a humanized anti-VEGF-A monoclonal antibody (PRO-169) versus ranibizumab in New Zealand white rabbits.

BACKGROUND: To evaluate the retinal toxicity after repeated intravitreal injections of a humanized anti-VEGF-A monoclonal antibody (PRO-169) versus ranibizumab in New Zealand white (NZW) rabbit eyes. METHODS: NZW rabbits were injected intravitreally with PRO-169 (n = 12), 1.25 mg/0.05 ml or ranibizumab (n = 12), 0.5 mg/0.05 ml into the right eye (OD), whereas the left eye (OS) of each rabbit was used as control. Three consecutive injections were administered at 30-days intervals. An electroretinogram (ERG) was recorded 30 days after each injection. Clinical examination was conducted before and after injections, including intraocular pressure determination and eye fundus exploration. Eyes were enucleated and retina, cornea, conjunctiva, ciliary body and optic nerve were prepared for histopathology assessment. RESULTS: ERG of the experimental and control eyes in PRO-169 and ranibizumab groups were similar in amplitude and pattern throughout the follow-up period. Clinical examination found no alterations of intraocular pressure (IOP). No retinal damage was observed in both, the experimental and control eyes, of all the rabbits. The histopathologic studies showed similar results in both groups, showing no signs of structural damage. CONCLUSIONS: Our study did not find evidence of retinal toxicity from a repeated intravitreal injection of PRO-169 or ranibizumab (Lucentis®) in NZW rabbits. These findings support intravitreal PRO-169 as a safe candidate to develop as a future alternative for the treatment of retinal neovascularization diseases.

Pharmacology study of a chimeric decoy receptor trap fusion protein on retina neovascularization by dual blockage of VEGF and FGF-2.

BACKGROUND: Clinical anti-vascular epithelial growth factor (VEGF) therapy trials faced a major challenge due to upregulated expression of other pro-angiogenic factors, such as fibroblast growth factor-2 (FGF-2). RC28, a novel recombinant dual decoy receptor IgG1 Fc-fusion protein, can block VEGFA and FGF-2 simultaneously. It is designed for the treatment of neovascular age-related macular degeneration and other pathological ocular neovascularization. The present study investigated the prevention efficacy of RC28 on choroidal neovascularization (CNV) in a monkey model and compared to the other mono VEGF antagonists; biodistribution and pharmacokinetics performance were also investigated. METHODS: ELISA and endothelial cell proliferation, migration, and tubule formation assay evaluated the bioactivity of RC28 in vitro, and an initial comparison was made among the mono target antagonists, Bevacizumab (Avastin), Ranibizumab (Lucentis), Aflibercept (EYLEA), Conbercept (KH902), and Ranibizumab (Lucentis). Laser-induced CNV in monkeys, and both VEGF and FGF-2 serum levels were detected in animals before and after the CNV model were induced. RC28 prevention efficacy was compared to other VEGF antagonists on CNV with respect to the incidence of CNV and several ophthalmic examinations. Ocular and systemic levels of RC28 were analyzed by 89Zr-labeled RC28 after single intravitreal administration for the biodistribution and pharmacokinetic profiles. RESULTS: RC28 is a unique fusion protein with high affinity to both VEGF and FGF-2, and beneficial to in vitro and in vivo bioactivity. The in vivo pharmacological studies demonstrated that the incidence of CNV formation was largely reduced in RC28 treatment groups with a low dosage as compared to other VEGF antagonist control groups. Furthermore, traces of RC28 were detected as dispersing from eyeballs to the liver after 20 days, and a prolonged half-time pharmacokinetic profile was exhibited.

Prion protein is essential for diabetic retinopathy-associated neovascularization.

Diabetic retinopathy (DR), a major complication of diabetes caused by vascular damage and pathological proliferation of retinal vessels, often progresses to vision loss. Vascular endothelial growth factor (VEGF) signaling plays a pivotal role in the development of DR, but the exact underlying molecular mechanisms remain ill-defined. Cellular prion protein (PrPc) is a surface protein expressed by vascular endothelial cells, and the increased expression of PrPc is associated with physiological and pathological vascularization. Nevertheless, a role for PrPc in the development of DR has not been appreciated. Here, we addressed this question. We found that the development of streptozocin (STZ)-induced DR, but not the STZ-induced hyperglycemia/diabetes itself, was significantly attenuated in PrPc-KO mice, compared to control wildtype (WT) mice, evident by measurement of retinal vascular leakage, retinal neovascularization, a retinopathy score and visual acuity assessment. Moreover, the attenuation of DR severity seemingly resulted from attenuation of retinal neovascularization via VEGF/ras/rac signaling. Together, our study suggests a previously unappreciated role for PrPc in the development of DR.

Molecular regulation of ERK5 in development of diabetic retinopathy.

Diabetic retinopathy (DR) is a major complication of diabetes, and causes pathological changes in retina blood vessels, as the most common cause of vision loss. Extracellular-signal-regulated kinase 5 (ERK5) is the newest discovered member in the mitogen-activated protein kinases (MAPKs) family, and recent evidence demonstrates an essential role of ERK5 signaling in the angiogenesis. However, whether ERK5 signaling may regulate DR development is unknown. Here, we used a streptozocin (STZ)-induce mouse DR model to investigate this question. We detected significant increases in the phosphorylation of ERK5, a signature of ERK5 activation in the purified retinal endothelial cells in DR mice, compared to control mice. In vivo suppression of ERK5 phosphorylation through administration of a specific inhibitor of ERK5 activation, BIX02189, did not prevent the occurrence of STZ-induced diabetes in mice, but significantly alleviated the severity of DR, seemingly through attenuating the retina neovascularization. Thus, our study suggests a previously unappreciated role of ERK5 signaling in DR development.

Metformin inhibits development of diabetic retinopathy through microRNA-497a-5p.

Metformin is an AMP-activated protein kinase activator that is widely prescribed for treating type 2 diabetes. Recently, metformin was reported to slow down the development and alleviate the severity of diabetic retinopathy (DR). However, the underlying mechanisms remain unclear. Here, we used an alloxan-induced diabetes mouse model to study the effects of metformin on the development of DR as well as the mechanisms. We found that DR was induced in alloxan-treated mice 10 weeks after alloxan treatment, and treatment of metformin did not prevent the occurrence of alloxan-induced diabetes. However, metformin significantly alleviated the severity of DR, seemingly through attenuating the retina neovascularization. Moreover, the total vascular endothelial cell growth factor A (VEGF-A) mRNA in mouse eyes was not altered by metformin, but the protein levels was decreased. Further analysis showed that metformin may inhibit the VEGF-A protein translation through inducing a VEGF-A-targeting microRNA, microRNA-497a-5p, resulting in reduced retina neovascularization. Thus, our study suggests a previously unappreciated role of metformin in the prevention of development of DR.