β2-Adrenergic Receptor Antagonism Attenuates CNV Through Inhibition of VEGF and IL-6 Expression

The effect of combination therapy with intravitreal bevacizumab and topical timolol-dorzolamide eye drops on diabetic macular edema: a double-blind randomized controlled trial

BACKGROUND

The mainstay of treatment in diabetic macular edema (DME) is intravitreal administration of anti-vascular endothelial growth factors (anti-VEGFs). Aqueous depressants may enhance the effects of anti-VEGF agents by prolonging their clearance via aqueous outflow.

PURPOSE

To compare the anatomical and functional outcomes of treatment with intravitreal bevacizumab (IVB) and topical timolol-dorzolamide versus IVB alone.

METHOD

In this randomized placebo-controlled clinical trial, patients with center-involving DME (ci-DME) and best corrected visual acuity (BCVA) of 20/30 or less were enrolled and randomly allocated to two treatment arms. One group received three monthly IVB injections and timolol-dorzolamide eye drops twice a day (IVB + TD group); the other group received three monthly IVB injections and artificial tear drops as placebo (IVB group). Patients underwent ophthalmic evaluations and macular optical coherence tomography scans at baseline and 1 month after the third injection.

RESULT

Forty-six eyes from 46 patients with ci-DME were recruited. There was no intergroup difference regarding age, gender distribution, diabetic retinopathy stage, glycemic indices, BCVA, central macular thickness (CMT), or intraocular pressure at baseline. BCVA was significantly improved in the IVB + TD group (0.46 ± 0.18 to 0.36 ± 0.18 logarithm of the minimum angle of resolution [logMAR], p = 0.002), in contrast to IVB group (0.40 ± 0.17 to 0.35 ± 0.22 logMAR, p = 0.113). Similarly, the IVB + TD group showed a significant reduction in CMT (p < 0.001), unlike the IVB group (p = 0.086); and the CMT change in the former was greater than in the latter (- 0.57 ± 57.67 vs. - 25.52 ± 68.02 μm, p = 0.033).

CONCLUSION

Our findings support the short-term effectiveness of topical timolol-dorzolamide as adjunctive therapy to IVB injections in managing center-involving DME in terms of anatomical and visual outcomes.

TRIAL REGISTRATION

Clinicaltrials.gov NCT05083689 (October 19, 2021).

Polymeric Propranolol Nanoparticles for Intraocular Delivery: Formulation, Characterization, and Vitreous Pharmacokinetics

Purpose

Recent studies have reported the promising effect of intravitreal propranolol on retinal neovascularization. However, rapid clearance and short half-life of the drug in the vitreous are the main drawbacks of this therapeutic approach. This study investigates the extension of the residence time of propranolol in the vitreous by polymeric nanoparticles (NPs) with the prospect of improving choroidal neovascularization treatment.

Methods

The poly (lactic-co-glycolic) acid (PLGA) NPs were fabricated by a modified double emulsion solvent evaporation method and the obtained NPs were characterized for their size, poly dispersity index (PDI), and surface image. The in vitro release, cell cytotoxicity, and uptake of NPs were also evaluated. To investigate the effect of the vitreous pharmacokinetic drug loaded NPs versus that of the free propranolol, they were intravitreally injected into the rabbits' eyes and the drug vitreous concentrations in defined intervals were analyzed by high performance liquid chromatography (HPLC).

Results

The spherical NPs with about 230 nm size, and almost 10% drug loading were obtained. Based on the 3-(4, 5-Dimethylthiazol-2-Yl)-2, 5-Diphenyltetrazolium Bromide (MTT) outcomes, 30 µg/ml of propranolol was considered as the guide dosage in the intravitreal injection. Confocal microscopy images verified the presence of labeled NPs in the posterior segment after five days of receiving the injection. In vivo assay revealed that the vanishing rate of propranolol in rabbits treated with propranolol NPs was reduced at twice the rate as compared to that of the vanishing rate experienced with only the free drug.

Conclusion

PLGA NPs can prolong the existence of propranolol in both vitreous and posterior ocular tissues, and thus, may provide an effective approach in treatment of posterior segment neovascularization.

Engineered Knockout of TRPA1 Inhibits Laser-Induced Choroidal Neovascularization Along With Associated TGFβ1 Expression and Neutrophil Infiltration

We examined the effects of gene ablation and chemical inhibition of transient receptor potential ankyrin 1 (TRPA1) on the growth of experimental argon laser-induced choroidal neovascularization (CNV) in mice. CNV was induced in the eyes of 6- to 8-week-old TRPA1-null (knockout [KO]) and wild-type (WT) mice by argon laser irradiation. Gene expression analysis was performed in laser-injured tissues at days 1 and 3. CNV growth was evaluated at day 14. Reciprocal bone marrow transplantation was performed between each genotype to identify the components responsible for either recipient tissue or bone marrow-derived inflammatory cells. Our results show that laser irradiation successfully induced CNV growth at the site of laser injury. The size of induced CNV was significantly smaller in KO mice than in WT mice at day 14, as determined by angiography with fluorescein isothiocyanate-dextran. Invasion of neutrophils, but not macrophages, was suppressed in association with suppression of the expression of transforming growth factor β1 and interleukin 6 in laser-irradiated KO tissue. Bone marrow transplantation indicated that the genotype of the recipient mouse, but not of inflammatory cells, is attributable to the KO phenotype. Systemic administration of a TRPA1 antagonist also reduced the CNV in a WT mouse. In conclusion, TRPA1 signaling in local cells is involved in growth of laser-induced CNV. The phenotype was not attributable to vascular endothelial cells and inflammatory cells. Blocking TRPA1 signal may therefore be a potential treatment strategy for CNV-related ocular diseases.

Timolol maleate, a β blocker eye drop, improved edema in a retinal vein occlusion model

Purpose

To investigate the therapeutic effects of eye drops, namely, timolol maleate, a β-adrenergic receptor antagonist, and latanoprost, a prostaglandin F2α analog, on retinal edema in a murine retinal vein occlusion (RVO) model.

Methods

An RVO model was established using laser-induced RVO in mice, which were administered timolol maleate and latanoprost eye drops several times after venous occlusion. Subsequently, the thickness of the inner nuclear layer (INL) and the expression levels of such genes as Vegf and Atf4, which are stress markers of the endoplasmic reticulum, were examined. Primary human cultured retinal microvascular endothelial cells (HRMECs) were treated with timolol under hypoxic conditions, after which the gene expression pattern was investigated. Importantly, an integrated stress response inhibitor (ISRIB) was used in the RVO model, he known ISRIB, which suppresses the expression of ATF4 in retinal edema.

Results

Increased INL thickness was suppressed by timolol eye drops, as were the expressions of Vegf and Atf4, in the RVO model. However, latanoprost eye drops did not induce any change in INL thickness. In HRMECs, hypoxic stress and serum deprivation increased the Vegf and Atf4 expressions; in response, treatment with timolol suppressed the Vegf expression. Furthermore, the ISRIB decreased the Vegf expression pattern and edema formation, which are associated with RVO.

Conclusions

These results indicate that timolol eye drops may be a potential option for RVO treatment.

Intravitreal bevacizumab plus propranolol for neovascular age-related macular degeneration (the BEVALOL study): a phase I clinical trial

BACKGROUND

Given the persistently large public health impact of neovascular age-related macular degeneration (nARMD) despite many years of anti-VEGF therapy as the first-line treatment and the demonstrated ability of b-blockers to reduce neovascularization, a synergistic effect between an anti-VEGF agent and an intravitreal beta-blocker is important to investigate in the quest for therapeutic alternatives that maximize efficacy and/or reduce costs. The main purpose of this study is to investigate the safety of a 0.1 ml intravitreal injection of a combination of bevacizumab (1.25 mg/0.05 ml) and propranolol (50 g/0.05 ml) to treat nARMD.

METHODS

Prospective phase I clinical trial that included patients with nARMD. Comprehensive ophthalmic evaluation was performed at baseline and included Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA), biomicroscopy of the anterior and posterior segments, binocular indirect ophthalmoscopy, color fundus photography, spectral domain optical coherence tomography (OCT), OCT angiography (OCT-A), fluorescein angiography (Spectralis, Heidelberg), and full-field electroretinography (ERG). All eyes were treated with a 0.1 ml intravitreal injection of a combination of bevacizumab (1.25 mg/0.05 ml) and propranolol (50 g/0.05 ml) within 1 week of baseline evaluation. The patients were reexamined at weeks 4, 8 and 12, and clinical evaluation and SD-OCT were performed at all follow-up visits. Additional injections of combination bevacizumab (1.25 mg/0.05 ml) and propranolol (50 g/0.05 ml) were administered at weeks 4 and 8. At the final study evaluation (week 12), color fundus photography, OCT-A, fluorescein angiography, and full-field ERG were repeated.

RESULTS

Eleven patients (11 eyes) completed all study visits of the 12 week study. Full field ERG b-waves did not show significant (p < 0.05) changes at week 12 compared to baseline. During the 12 week follow-up period, none of the study eyes developed intraocular inflammation, endophthalmitis or intraocular pressure elevation more than 4 mmHg over baseline. Mean ± SE BCVA (logMAR) was 0.79 ± 0.09 at baseline and was significantly (p < 0.05) improved to 0.61 ± 0.10 at week 4; 0.53 ± 0.10 at week 8; and 0.51 ± 0.09 at week 12. Mean ± SE central subfield thickness (CST) (μm) was 462 ± 45 at baseline and was significantly (p < 0.05) lower at 4, 8 and 12 weeks (385 ± 37; 356 ± 29 and 341 ± 24, respectively).

CONCLUSIONS

In this 12 week trial of a combination of intravitreal bevacizumab and propranolol for treatment of nARMD, no adverse events or signals of ocular toxicity were observed. Further studies using this combination therapy are warranted. Trial Registration Project registered in Plataforma Brasil with CAAE number 28108920.0.0000.5440 and approved in ethics committee of Clinics Hospital of Ribeirao Preto Medicine School of São Paulo University-Ribeirão Preto, São Paulo, Brazil (appreciation number 3.999.989 gave the approval).

Overactivation of Norepinephrine-β2-Adrenergic Receptor Axis Promotes Corneal Neovascularization

Purpose

To investigate the role of the sympathetic nervous system in corneal neovascularization (CNV) and to identify the downstream pathway involved in this regulation.

Methods

Three types of CNV models were constructed with C57BL/6J mice, including the alkali burn model, suture model, and basic fibroblast growth factor (bFGF) corneal micropocket model. Subconjunctival injection of the sympathetic neurotransmitter norepinephrine (NE) was administered in these three models. Control mice received injections of water of the same volume. The corneal CNV was detected using slit-lamp microscopy and immunostaining with CD31, and the results were quantified by ImageJ. The expression of β2-adrenergic receptor (β2-AR) was stained with mouse corneas and human umbilical vein endothelial cells (HUVECs). Furthermore, the anti-CNV effects of β2-AR antagonist ICI-118,551 (ICI) were examined with HUVEC tube formation assay and with a bFGF micropocket model. Additionally, partial β2-AR knockdown mice (Adrb2+/-) were used to establish the bFGF micropocket model, and the corneal CNV size was quantified based on the slit-lamp images and vessel staining.

Results

Sympathetic nerves invaded the cornea in the suture CNV model. The NE receptor β2-AR was highly expressed in corneal epithelium and blood vessels. The addition of NE significantly promoted corneal angiogenesis, whereas ICI effectively inhibited CNV invasion and HUVEC tube formation. Adrb2 knockdown significantly reduced the cornea area occupied by CNV.

Conclusions

Our study found that sympathetic nerves grow into the cornea in conjunction with newly formed vessels. The addition of the sympathetic neurotransmitter NE and activation of its downstream receptor β2-AR promoted CNV. Targeting β2-AR could potentially be used as an anti-CNV strategy.

β-Adrenoreceptors as Therapeutic Targets for Ocular Tumors and Other Eye Diseases-Historical Aspects and Nowadays Understanding

β-adrenoreceptors (ARs) are members of the superfamily of G-protein-coupled receptors (GPCRs), and are activated by catecholamines, such as epinephrine and norepinephrine. Three subtypes of β-ARs (β₁, β₂, and β₃) have been identified with different distributions among ocular tissues. Importantly, β-ARs are an established target in the treatment of glaucoma. Moreover, β-adrenergic signaling has been associated with the development and progression of various tumor types. Hence, β-ARs are a potential therapeutic target for ocular neoplasms, such as ocular hemangioma and uveal melanoma. This review aims to discuss the expression and function of individual β-AR subtypes in ocular structures, as well as their role in the treatment of ocular diseases, including ocular tumors.

Review: The Development of Risk Factors and Cytokines in Retinal Vein Occlusion

Retinal vein occlusion (RVO) is the second most prevalent retinal disease. Despite this, the pathogenic mechanisms and risk factors are not entirely clear. In this article, we review recent publications on the classification, pathogenesis, risk factors, ischemic changes, cytokines, and vital complications of RVO. Risk factors and cytokines are important for exploring the mechanisms and new treatment targets. Furthermore, risk factors are interrelated, making RVO mechanisms more complex. Cytokines act as powerful mediators of pathological conditions, such as inflammation, neovascularization, and macular edema. This review aims to summarize the updated knowledge on risk factors, cytokines of RVO and signaling in order to provide valuable insight on managing the disease.

Fingolimod (FTY720), a Sphinogosine-1-Phosphate Receptor Agonist, Mitigates Choroidal Endothelial Proangiogenic Properties and Choroidal Neovascularization

Neovascular or wet age-related macular degeneration (nAMD) causes vision loss due to inflammatory and vascular endothelial growth factor (VEGF)-driven neovascularization processes in the choroid. Due to the excess in VEGF levels associated with nAMD, anti-VEGF therapies are utilized for treatment. Unfortunately, not all patients have a sufficient response to such therapies, leaving few if any other treatment options for these patients. Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator found in endothelial cells that participates in modulating barrier function, angiogenesis, and inflammation. S1P, through its receptor (S1PR1) in endothelial cells, prevents illegitimate sprouting angiogenesis during vascular development. In the present paper, we show that, in choroidal endothelial cells, S1PR1 is the most abundantly expressed S1P receptor and agonism of S1PR1-prevented choroidal endothelial cell capillary morphogenesis in culture. Given that nAMD pathogenesis draws from enhanced inflammation and angiogenesis as well as a loss of barrier function, we assessed the impact of S1PR agonism on choroidal neovascularization in vivo. Using laser photocoagulation rupture of Bruch’s membrane to induce choroidal neovascularization, we show that S1PR non-selective (FTY720) and S1PR1 selective (CYM5442) agonists significantly inhibit choroidal neovascularization in this model. Thus, utilizing S1PR agonists to temper choroidal neovascularization presents an additional novel use for these agonists presently in clinical use for multiple sclerosis as well as other inflammatory diseases.

Blocking Ocular Sympathetic Activity Inhibits Choroidal Neovascularization

Purpose: To investigate how modulating ocular sympathetic activity affects progression of choroidal neovascularization (CNV), a hallmark feature of wet age-related macular degeneration (AMD).

Methods: In the first of two studies, Brown Norway rats underwent laser-induced CNV and were assigned to one of the following groups: daily eye drops of artificial tears (n = 10; control group); daily eye drops of the β-adrenoreceptor agonist isoproterenol (n = 10); daily eye drops of the β-adrenoreceptor antagonist propranolol (n = 10); sympathetic internal carotid nerve (ICN) transection 6 weeks prior to laser-induced CNV (n = 10). In the second study, rats underwent laser-induced CNV followed by ICN transection at different time points: immediately after the laser injury (n = 6), 7 days after the laser injury (n = 6), and sham surgery 7 days after the laser injury (n = 6; control group). All animals were euthanized 14 days after laser application. CNV development was quantified with fluorescein angiography and optical coherence tomography (in vivo), as well as lesion volume analysis using 3D confocal reconstruction (postmortem). Angiogenic growth factor protein levels in the choroid were measured with ELISA.

Results: In the first study, blocking ocular sympathetic activity through pharmacological or surgical manipulation led to a 75% or 70% reduction in CNV lesion volume versus the control group, respectively (P < 0.001). Stimulating ocular sympathetic activity with isoproterenol also led to a reduction in lesion volume, but only by 27% versus controls (P < 0.05). VEGF protein levels in the choroid were elevated in the three treatment groups (P < 0.01). In the second study, fluorescein angiography and CNV lesion volume analysis indicated that surgically removing the ocular sympathetic supply inhibited progression of laser-induced CNV, regardless of whether ICN transection was performed on the same day or 7 days after the laser injury.

Conclusion: Surgical and pharmacological block of ocular sympathetic activity can inhibit progression of CNV in a rat model. Therefore, electrical block of ICN activity could be a potential bioelectronic medicine strategy for treating wet AMD.

Caffeine Inhibits Choroidal Neovascularization Through Mitigation of Inflammatory and Angiogenesis Activities

Adenosine receptors (AR) are widely expressed in a variety of tissues including the retina and brain. They are involved in adenosine-mediated immune responses underlying the onset and progression of neurodegenerative diseases. The expression of AR has been previously demonstrated in some retinal cells including endothelial cells and retinal pigment epithelial cells, but their expression in the choroid and choroidal cells remains unknown. Caffeine is a widely consumed AR antagonist that can influence inflammation and vascular cell function. It has established roles in the treatment of neonatal sleep apnea, acute migraine, and post lumbar puncture headache as well as the neurodegenerative diseases such as Parkinson and Alzheimer. More recently, AR antagonism with caffeine has been shown to protect preterm infants from ischemic retinopathy and retinal neovascularization. However, whether caffeine impacts the development and progression of ocular age-related diseases including neovascular age-related macular degermation remains unknown. Here, we examined the expression of AR in retinal and choroidal tissues and cells. We showed that antagonism of AR with caffeine or istradefylline decreased sprouting of thoracic aorta and choroid/retinal pigment epithelium explants in ex vivo cultures, consistent with caffeine's ability to inhibit endothelial cell migration in culture. In vivo studies also demonstrated the efficacy of caffeine in inhibition of choroidal neovascularization and mononuclear phagocyte recruitment to the laser lesion sites. Istradefylline, a specific AR 2A antagonist, also decreased choroidal neovascularization. Collectively, our studies demonstrate an important role for expression of AR in the choroid whose antagonism mitigate choroidal inflammatory and angiogenesis activities.

Macrophage-derived interleukin-6 is necessary and sufficient for choroidal angiogenesis

Neovascular age-related macular degeneration (nAMD) commonly causes vision loss from aberrant angiogenesis, termed choroidal neovascularization (CNV). Interleukin-6 (IL6) is a pro-inflammatory and pro-angiogenic cytokine that is correlated with AMD progression and nAMD activity. We hypothesize that anti-IL6 therapy is a potential nAMD therapeutic. We found that IL6 levels were increased after laser injury and expressed by macrophages. Il6-deficiency decreased laser-induced CNV area and exogenous IL6 addition increased choroidal sprouting angiogenesis. Il6-null mice demonstrated equally increased macrophage numbers as wildtype mice. At steady state, IL6R expression was detected on peripheral blood and ocular monocytes. After laser injury, the number of IL6R⁺Ly6C⁺ monocytes in blood and IL6R⁺ macrophages in the eye were increased. In human choroid, macrophages expressed IL6, IL6R, and IL6ST. Furthermore, IL6R⁺ macrophages displayed a transcriptional profile consistent with STAT3 (signal transducer and activator of transcription 3) activation and angiogenesis. Our data show that IL6 is both necessary and sufficient for choroidal angiogenesis. Macrophage-derived IL6 may stimulate choroidal angiogenesis via classical activation of IL6R⁺ macrophages, which then stimulate angiogenesis. Targeting IL6 or the IL6R could be an effective adjunctive therapy for treatment-resistant nAMD patients.

INTRAVITREAL INJECTION OF PROPRANOLOL FOR THE TREATMENT OF RETINAL CAPILLARY HEMANGIOMA IN A CASE OF VON HIPPEL-LINDAU

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of intravitreal propranolol for the management of retinal capillary hemangioma in a patient with Von Hippel-Lindau.

METHODS

Two intravitreal injections of 50 μg/0.05 mL propranolol were administered 6 weeks apart in the left eye of a 26-year-old patient with bilateral multiple retinal capillary hemangiomas. Safety and response to therapy were evaluated using electroretinogram, fluorescein angiography, and measurement of visual acuity. Laser photocoagulation was performed in the right eye.

RESULTS

One month after the second intravitreal injection of propranolol, fluorescein leakage decreased from the tumors located on the optic nerve head and in the inferonasal retinal periphery. Reduction of the retinal capillary hemangioma vascularity and enhancement of its fibrosis associated with the attenuation of the feeder vessel were also observed. Ophthalmic examination showed no adverse effect except for a mild transient vitreous haziness after each injection. Electroretinogram performed 4 weeks after the first injection revealed no retinal toxicity.

CONCLUSION

Intravitreal propranolol showed a therapeutic effect on retinal capillary hemangioma with no short-term adverse effects except a mild transient inflammatory response in a patient with Von Hippel-Lindau.

A Randomized Controlled Pilot Study: Combined 595-nm Pulsed Dye Laser Treatment and Oxymetazoline Hydrochloride Topical Cream Superior to Oxymetazoline Hydrochloride Cream for Erythematotelangiectatic Rosacea

Background and Objectives

We evaluated if oxymetazoline therapy combined with 595‐nm pulsed dye laser (PDL) will be more beneficial than topical oxymetazoline alone for the improvement of erythematotelangiectatic rosacea.

Study Design/Materials and Methods

This was a randomized, controlled, prospective clinical trial approved by an independent Institutional Review Board, which enrolled 34 patients with moderate to severe clinical erythema (CEA) into a two‐arm study of PDL with concomitant oxymetazoline cream (Arm 1) and oxymetazoline cream alone (Arm 2). Patients in Arm 1 were treated with 3 monthly laser sessions, which were started after 1 month of topical oxymetazoline cream. Thirty subjects continued with the study, and 25 subjects (Arm 1: 14, Arm 2: 11) completed the 6‐month follow‐up. With photographic comparison to baseline images, efficacy endpoints were based on clinical on‐site grading by both the investigator and the patient, using the grading tools for CEA, Global Aesthetic Improvement (GAI) assessment, vessel size improvement, and subject self‐assessment. These scales were assessed at baseline and/or at each clinical follow‐up at 1, 2, 3, and 6 months. Subject satisfaction as well as post‐treatment immediate response and treatment‐associated pain scores were also evaluated.

Results

Statistically significant improvement in CEA was seen in both arms at the 1‐, 2‐, and 3‐month post‐baseline visits (P < 0.01). Only Arm 1 presented statistically significant improvement in CEA (P < 0.001) at 6 months post baseline with a mean score of 1.6 (almost clear‐mild) compared with 3.2 at baseline. Arm 1 showed significantly greater mean vessel size improvement at 3 months (P < 0.01) and 6 months (P < 0.05) post baseline compared to Arm 2. Significantly greater improvement (P < 0.05) in the investigator GAI score was reported at the 2‐ and 6‐month follow‐ups compared with Arm 2. Subject GAI scores showed statistically significant greater improvement in Arm 1 compared with Arm 2 at both the 3‐ and 6‐month follow‐ups (P < 0.01). There were no complications or long‐term effects associated with PDL or topical oxymetazoline treatments.

Conclusion

The prospective trial verifies a safe, enhanced clinical outcome with the combination of PDL therapy and topical oxymetazoline for the treatment of erythematotelangiectatic rosacea patients. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Selective β2-Adrenoceptor Blockade Rescues Mandibular Growth Retardation in Adolescent Rats Exposed to Chronic Intermittent Hypoxia

Activation of the sympathoadrenal system is associated with sleep apnea-related symptoms and metabolic dysfunction induced by chronic intermittent hypoxia (IH). IH can induce hormonal imbalances and growth retardation of the craniofacial bones. However, the relationship between IH and β2-adrenergic receptor signaling in the context of skeletal growth regulation is unclear. This study aimed to investigate the role of β2-adrenergic receptors in IH-induced mandibular growth retardation and bone metabolic alterations. Male 7-week-old Sprague–Dawley rats were subjected to IH for 3 weeks. IH conditions were established using original customized hypoxic chambers; IH was induced at a rate of 20 cycles per hour (oxygen levels changed from 4 to 21% in one cycle) for 8 h per day during the 12 h “lights on” period. The rats received intraperitoneal administration of a β2-adrenergic antagonist (butoxamine) or saline. To exclude dietary effects on general growth, the normoxic rats with saline, normoxic rats with butoxamine, and IH rats with butoxamine were subjected to food restriction to match the body weight gains between IH and other three groups. Body weight, heart rate, blood pressure, and plasma concentrations of leptin, serotonin, and growth hormone were measured. Bone growth and metabolism were evaluated using radiography, microcomputed tomography, and immunohistochemical staining. Plasma leptin levels were significantly increased, whereas that of serotonin and growth hormone were significantly decreased following IH exposure. Leptin levels recovered following butoxamine administration. Butoxamine rescued IH-induced mandibular growth retardation, with alterations in bone mineral density at the condylar head of the mandible. Immunohistochemical analysis revealed significantly lower expression levels of receptor activator of nuclear factor-kappa B ligand (RANKL) in the condylar head of IH-exposed rats. Conversely, recovery of RANKL expression was observed in IH-exposed rats administered with butoxamine. Collectively, our findings suggest that the activation of β2-adrenergic receptors and leptin signaling during growth may be involved in IH-induced skeletal growth retardation of the mandible, which may be mediated by concomitant changes in RANKL expression at the growing condyle.

Anti-VEGF-Resistant Retinal Diseases: A Review of the Latest Treatment Options

Anti-vascular endothelial growth factor (anti-VEGF) therapy currently plays a central role in the treatment of numerous retinal diseases, most notably exudative age-related macular degeneration (eAMD), diabetic retinopathy and retinal vein occlusions. While offering significant functional and anatomic benefits in most patients, there exists a subset of 15–40% of eyes that fail to respond or only partially respond. For these cases, various treatment options have been explored with a range of outcomes. These options include steroid injections, laser treatment (both thermal therapy for retinal vascular diseases and photodynamic therapy for eAMD), abbreviated anti-VEGF treatment intervals, switching anti-VEGF agents and topical medications. In this article, we review the effectiveness of these treatment options along with a discussion of the current research into future directions for anti-VEGF-resistant eyes.

Propranolol Specifically Suppresses the Viability of Tumorous Schwann Cells Derived from Plexiform Neurofibromas In Vitro

BACKGROUND/AIM

Plexiform neurofibromas (PNFs) are benign tumors of the periph eral nerves sheath, which can damage neighboring organs, impair functions, cause pain and serious maxillofacial disfigurement, and have a high risk of malignant transformation. Complete resection is usually not possible since PNFs often extend through multiple layers of tissue. Therefore, it is necessary and beneficial to find a reasonable drug treatment for PNFs. Propranolol-treatment is the first-line therapy for infantile hemangiomas and the side effects are reversible and mostly benign. The present study aimed to examine the possible effect of propranolol for suppressing PNFs in vitro.

MATERIALS AND METHODS

Paired primary Schwann-cell-rich cultures and fibroblast-rich cultures were obtained from 4 PNFs of unrelated patients. Human Schwann cells (HSCs) were used as the control. These cultures were treated with propranolol for 7 days at concentrations up to 150 μM. Cells were then measured for their viability and immune-stained with S100 to label the tumorous Schwann cells.

RESULTS

Propranolol inhibited the viability of the tumorous Schwann cells in a dose-dependent manner, while did not substantially suppress viability of the non-tumorous fibroblasts derived from the same PNFs.

CONCLUSION

Propranolol may provide a treatment option for suppressing the growth of PNFs.

Assessment of the safety of intravitreal injection of metoprolol tartrate in rabbits

PURPOSE

To verify the safety of different doses of intravitreal metoprolol tartrate (MT) after intravitreal injection in rabbit eyes.

METHODS

Animals were randomly assigned into 2 groups: group I received 50 µg of MT and group II 100 µg of MT. A volume of 0.05 mL of the drug solution was administered through an intravitreal injection, while the control eyes received an equal volume of saline solution. Safety was assessed by clinical observation, electroretinography (ERG) and histological evaluation.

RESULTS

No evidence of clinical toxicity was observed. ERG waveforms from the MT treated eyes were similar to those recorded from the control eyes in dark-adapted state, amplitude and the implicit time are similar between the groups in light-adapted state, and their retinas had no signs of toxicity by histological evaluation 7 days after intravitreal injection.

CONCLUSIONS

The intravitreal use of metoprolol at 50 and 100 µg dosages does not cause short-term retinal toxicity in rabbits.

EFFICACY OF ADJUVANT TOPICAL DORZOLAMIDE-TIMOLOL IN PATIENTS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION REFRACTORY TO ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY

PURPOSE

To evaluate the efficacy of adjuvant topical dorzolamide-timolol in patients with neovascular age-related macular degeneration unresponsive to anti-vascular endothelial growth factor therapy.

METHODS

This retrospective, interventional study included 15 patients with neovascular age-related macular degeneration refractory to anti-vascular endothelial growth factor. Patients used topical dorzolamide-timolol twice daily in the neovascular age-related macular degeneration eye and received anti-vascular endothelial growth factor therapy at each visit, with the same fixed interval and agent as before the addition of dorzolamide-timolol. Central macular thickness, maximal subretinal fluid height, and maximal pigment epithelial detachment height were measured at baseline and every visit.

RESULTS

The mean follow-up period was 17.2 ± 5.5 weeks. The mean central macular thickness decreased from 383.5 μm at baseline to 298.3 μm at the final visit (P = 0.041). The mean maximal subretinal fluid height decreased from 105.0 μm at baseline to 58.3 μm at the final visit (P = 0.021). Complete resolution of subretinal fluid was observed in 3 of 11 subretinal fluid-type eyes. There was no significant change in the maximal pigment epithelial detachment height. The mean logarithm of the minimum angle of resolution visual acuity decreased from 0.61 (20/81 Snellen) at baseline to 0.66 (20/91 Snellen) at final visit, which was not significant (P = 0.314). The mean intraocular pressure decreased significantly from 14.9 mmHg at baseline to 12.3 mmHg at the final visit (P = 0.005).

CONCLUSION

The use of adjuvant topical dorzolamide-timolol was effective in decreasing central macular thickness and subretinal fluid in patients with neovascular age-related macular degeneration refractory to continual fixed-interval intravitreal anti-vascular endothelial growth factor therapy, but did not result in functional improvement in this short-term study.

Can Beta-2-Adrenergic Pathway Be a New Target to Combat SARS-CoV-2 Hyperinflammatory Syndrome?-Lessons Learned From Cancer

SARS-CoV-2 infection is a new threat to global public health in the 21^st century (2020), which has now rapidly spread around the globe causing severe pneumonia often linked to Acute Respiratory Distress Syndrome (ARDS) and hyperinflammatory syndrome. SARS-CoV-2 is highly contagious through saliva droplets. The structural analysis suggests that the virus enters human cells through the ligation of the spike protein to angiotensin-converting enzyme 2 (ACE₂). The progression of Covid-19 has been divided into three main stages: stage I—viral response, stage II—pulmonary phase, and stage III—hyperinflammation phase. Once the patients enter stage III, it will likely need ventilation and it becomes difficult to manage. Thus, it will be of paramount importance to find therapies to prevent or slow down the progression of the disease toward stage III. The key event leading to hyperinflammation seems to be the activation of Th-17 immunity response and Cytokine storm. B₂-adrenergic receptors (B₂ARs) are expressed on airways and on all the immune cells such as macrophages, dendritic cells, B and T lymphocytes. Blocking (B₂AR) has been proven, also in clinical settings, to reduce Th-17 response and negatively modulate inflammatory cytokines including IL-6 while increasing IFNγ. Non-selective beta-blockers are currently used to treat several diseases and have been proven to reduce stress-induced inflammation and reduce anxiety. For these reasons, we speculate that targeting B₂AR in the early phase of Covid-19 might be beneficial to prevent hyperinflammation.

A Re-Appraisal of Pathogenic Mechanisms Bridging Wet and Dry Age-Related Macular Degeneration Leads to Reconsider a Role for Phytochemicals

Which pathogenic mechanisms underlie age-related macular degeneration (AMD)? Are they different for dry and wet variants, or do they stem from common metabolic alterations? Where shall we look for altered metabolism? Is it the inner choroid, or is it rather the choroid–retinal border? Again, since cell-clearing pathways are crucial to degrade altered proteins, which metabolic system is likely to be the most implicated, and in which cell type? Here we describe the unique clearing activity of the retinal pigment epithelium (RPE) and the relevant role of its autophagy machinery in removing altered debris, thus centering the RPE in the pathogenesis of AMD. The cell-clearing systems within the RPE may act as a kernel to regulate the redox homeostasis and the traffic of multiple proteins and organelles toward either the choroid border or the outer segments of photoreceptors. This is expected to cope with the polarity of various domains within RPE cells, with each one owning a specific metabolic activity. A defective clearance machinery may trigger unconventional solutions to avoid intracellular substrates’ accumulation through unconventional secretions. These components may be deposited between the RPE and Bruch’s membrane, thus generating the drusen, which remains the classic hallmark of AMD. These deposits may rather represent a witness of an abnormal RPE metabolism than a real pathogenic component. The empowerment of cell clearance, antioxidant, anti-inflammatory, and anti-angiogenic activity of the RPE by specific phytochemicals is here discussed.

Microglia Contribution to the Regulation of the Retinal and Choroidal Vasculature in Age-Related Macular Degeneration

The retina is a highly metabolically active tissue with high-level consumption of nutrients and oxygen. This high metabolic demand requires a properly developed and maintained vascular system. The retina is nourished by two systems: the central retinal artery that supplies the inner retina and the choriocapillaris that supplies the outer retina and retinal pigment epithelium (RPE). Pathological neovascularization, characterized by endothelial cell proliferation and new vessel formation, is a common hallmark in several retinal degenerative diseases, including age-related macular degeneration (AMD). A limited number of studies have suggested that microglia, the resident immune cells of the retina, have an important role not only in the pathology but also in the formation and physiology of the retinal vascular system. Here, we review the current knowledge on microglial interaction with the retinal vascular system under physiological and pathological conditions. To do so, we first highlight the role of microglial cells in the formation and maintenance of the retinal vasculature system. Thereafter, we discuss the molecular signaling mechanisms through which microglial cells contribute to the alterations in retinal and choroidal vasculatures and to the neovascularization in AMD.

Nonselective alpha-/beta- AR antagonists can inhibit pericyte proliferation, migration, and secretion in vitro

It has been reported that the beta-adrenergic receptor blocker (propranolol) and the a-adrenergic receptor (AR) blocker (phentolamine) both can inhibit human endothelial cell (EC) angiogenesis in vitro. However, it is unknown whether this inhibition also acts on pericytes. The present study aimed to determine how pericytes react to treatment with an a-/β- AR blocker. In the study, cell proliferation assays and scratch assay were performed to assess the effect of phentolamine or propranolol on cell proliferation and migration. Western blot and ELISA were employed to determine changes in VEGF-A and Ang-1 expression levels. The results indicated that the nonselective a-/β- AR blocker inhibited the proliferation, migration, and secretion of pericytes. The use of the nonselective a-/β- AR blocker might have an impact on vascularization and vascular maturation. Our research suggests the rational use of nonselective a-/β- AR blockers to treat angiogenesis-dependent diseases.

Monocyte-Derived Macrophages Are Necessary for Beta-Adrenergic Receptor-Driven Choroidal Neovascularization Inhibition

Purpose

Beta-adrenergic receptor (AR) antagonists, like propranolol, inhibit angiogenesis in multiple ocular conditions through an unknown mechanism. We previously showed that propranolol reduces choroidal neovascularization (CNV) by decreasing interleukin-6 levels. Since macrophages are one of the central producers of interleukin-6, we examined whether macrophages are required for propranolol-driven inhibition of choroidal angiogenesis.

Methods

We tested the anti-angiogenic properties of propranolol in the choroidal sprouting assay and the laser-induced CNV model. Bone marrow-derived monocytes (BMDMs) were added to the choroidal sprouting assay and Ccr2-/- mice were subjected to laser-induced CNV. Multi-parameter flow cytometry was performed to characterize the ocular mononuclear phagocyte populations after laser injury and during propranolol treatment.

Results

Propranolol reduced choroidal angiogenesis by 41% (P < 0.001) in the choroidal sprouting assay. Similarly, propranolol decreased laser-induced CNV by 50% (P < 0.05) in female mice, with no change in males. BMDMs increased choroidal sprouting by 146% (P < 0.0001), and this effect was ablated by propranolol. Beta-AR inhibition had no effect upon laser-induced CNV area in female Ccr2-/- mice. MHCII+ and MHCII- macrophages increased 20-fold following laser treatment in wildtype mice as compared to untreated mice, and this effect was completely attenuated in lasered Ccr2-/- mice. Moreover, propranolol increased the numbers of MHCII+ and MHCII- macrophages by 1.9 (P = 0.07) and 3.1 (P < 0.05) fold in lasered female mice with no change in macrophage numbers in males.

Conclusions

Our data suggest that propranolol inhibits angiogenesis through recruitment of monocyte-derived macrophages in female mice only. These data show the anti-angiogenic nature of beta-AR blocker-recruited monocyte-derived macrophages in CNV.

Propranolol Attenuates Proangiogenic Activity of Mononuclear Phagocytes: Implication in Choroidal Neovascularization

Purpose

Targeting β-adrenergic receptor signaling with propranolol has emerged as a potential candidate to counteract choroidal neovascularization (CNV). Little is known of its effect on macrophages, which play a critical role in CNV. We investigated the effect of propranolol on angiogenic response of mononuclear phagocytes (MPs).

Methods

The angiogenic effect of propranolol was evaluated in laser-induced CNV model. Mice received intraperitoneal injections of propranolol (6 mg/kg/d) or vehicle. CNV area and inflammatory cells were determined respectively by using lectin staining and an anti-IBA-1 antibody on RPE/choroid flat mounts. Inflammatory gene expression was evaluated by quantitative (q) PCR analysis. Mechanisms of propranolol was studied in MP cell lines J774 and RAW264.7 and in primary peritoneal macrophages. Expression of pro- and antiangiogenic mediators was studied. In addition, effects of propranolol treatment of MPs was assessed on choroidal explant.

Results

CNV was attenuated by propranolol and concomitantly associated with decreased inflammatory mediators IL-6 and TNFα, albeit with accumulation of (β-adrenoceptor harboring) MPs in the CNV area. Conditioned media from MPs preincubated with propranolol exerted antiangiogenic effects. Treatment of J774 confirmed the attenuation of inflammatory response to propranolol and increased cleaved caspase-3 on choroidal explant. We found that propranolol increased pigment epithelium-derived factor (PEDF) expression in MPs. Trapping of PEDF with an antibody abrogated antiangiogenic effects of propranolol. PEDF was also detected in CNV-associated MPs.

Conclusions

We hereby show that propranolol confers on MPs antiangiogenic properties by increasing PEDF expression, which complements its effects on vascular tissue resulting in inhibition of choroidal vasoproliferation in inflammatory conditions. The study supports possible use of propranolol as a therapeutic modality for CNV.

Intravenous anti-VEGF agents with RGD peptide-targeted core cross-linked star (CCS) polymers modified with indocyanine green for imaging and treatment of laser-induced choroidal neovascularization

S-PEG-ICG-RGD-RBZ NPs were synthesized to intravenously deliver anti-VEGF agents to choroidal neovascularization (CNV) areas for the treatment of CNV.

Propranolol inhibits proliferation and invasion of hemangioma-derived endothelial cells by suppressing the DLL4/Notch1/Akt pathway

Infantile hemangioma (IH) is one of the most common benign vascular tumors of infancy. Propranolol has been recently introduced for the treatment of IH. However, the mechanism of protective effect has not been fully understood. In this study, hemangioma-derived endothelial cells (HemECs) were isolated and treated with propranolol. The cell viability was measured by MTT assay, and the cell cycle arrest was detected using flow cytometry. Cell invasion was determined using transwell assay. The expressions of matrix metalloproteinase (MMP)-2, MMP-9, Delta-like 4 (DLL4), Notch1, Akt, p-Akt, and vascular endothelial growth factor (VEGF) were detected using western blot. HemECs were incubated with recombinant human DLL4 (rhDLL4) to investigate the role of DLL4/Notch1 in the effect of propranolol. The results showed that propranolol inhibited cell viability of HemECs in a time-dependent manner. Propranolol suppressed cell proliferation of HemECs by arresting cell progression at G0/G1 phase. Propranolol inhibited the invasion ability of HemECs and reduced the expression levels of MMP-2 and MMP-9 in HemECs. Besides, propranolol treatment blocked the DLL4/Notch1 and Akt signaling and inhibited VEGF expression in HemECs. Treatment with rhDLL4 activated the Akt signaling and attenuated the effect of propranolol on HemECs. Our data indicated that propranolol inhibited the cell proliferation and invasion of HemECs. The effect was possibly involved in the DLL4/Notch1/Akt signaling pathway.

Propranolol for Proliferative Diabetic Retinopathy

BACKGROUND AND OBJECTIVE

To determine the effect of propranolol on retinal neovascularization due to proliferative diabetic retinopathy (PDR).

PATIENTS AND METHODS

For this prospective pilot, interventional, case series, patients with diabetes with PDR (n = 10 subjects; 12 eyes) were recruited at the ophthalmology clinic of the University of Wisconsin - Madison. Subjects were administered oral propranolol for 12 weeks and retinopathy and area of retinal neovascularization were monitored with fundus photography and fluorescein angiography (FA). The study's main outcome measures were photographic area of retinal neovascularization and degree of leakage on FA.

RESULTS

All eyes demonstrated stable degrees of retinal neovascularization by the end of 12 weeks.

CONCLUSION

This dose of oral propranolol during a period of 12 weeks did not demonstrate significant effect on retinal neovascularization due to PDR. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:35-40.].