The Effect of Topical Infliximab on Corneal Neovascularization in Rabbits

Up-to-date molecular medicine strategies for management of ocular surface neovascularization

Ocular surface neovascularization and its resulting pathological changes significantly alter corneal refraction and obstruct the light path to the retina, and hence is a major cause of vision loss. Various factors such as infection, irritation, trauma, dry eye, and ocular surface surgery trigger neovascularization via angiogenesis and lymphangiogenesis dependent on VEGF-related and alternative mechanisms. Recent advances in antiangiogenic drugs, nanotechnology, gene therapy, surgical equipment and techniques, animal models, and drug delivery strategies have provided a range of novel therapeutic options for the treatment of ocular surface neovascularization. In this review article, we comprehensively discuss the etiology and mechanisms of corneal neovascularization and other types of ocular surface neovascularization, as well as emerging animal models and drug delivery strategies that facilitate its management.

Effect of adalimumab on experimental corneal neovascularization model

PURPOSE

To evaluate the efficacy of adalimumab (ADA) on inhibition of experimental corneal neovascularization (CNV) and compare the outcomes with bevacizumab (BEVA).

METHODS

Twenty-four female Winstar rats (48 eyes) were used. Silver/Potassium Nitrate sticks were used for creating CNV. Forty-eight eyes of the rats were separated into 6 groups. The eyes which only NaCl was injected subconjunctivally (SC) formed Group-1. The eyes which CNV was created and NaCl, BEVA (2.5 mg/0.05 mL), ADA (2.5 mg/0.05 mL), respectively, were injected SC formed group-2, 3 and 4. The eyes which only BEVA and ADA, respectively, were injected SC formed group-5 and 6. Five days later the animals were sacrificed. Hematoxylin and eosin staining, Masson trichrome staining, Vascular endothelial growth factor (VEGF), and Platelet-derived growth factor (PDGF) antibodies were performed.

RESULTS

Histochemical results showed that there was no histopathological finding in group-1, 5, and 6. Collagen fiber irregularity was observed in group-2 and there was a significant improvement in collagen fiber irregularity in group-3 and 4. Collagen fiber proliferation was higher in group-2 than in group-3 and 4. VEGF and PDGF stainings were not observed in group-1, 5, and 6. VEGF and PDGF stainings were observed in group-2 and significantly decreased in group-3 and 4 compared to group-2. ADA was found to be superior to BEVA in terms of decreasing VEGF staining.

CONCLUSION

Both BEVA and ADA were effective in inhibiting CNV. Subconjunctival ADA seems to be more effective than BEVA in terms of inhibiting VEGF expression. Further experimental studies about ADA and BEVA are needed.

Intrastromal versus subconjunctival anti-VEGF agents for treatment of corneal neovascularization: a rabbit study

OBJECTIVE

To determine whether subconjunctival or intrastromal administration of anti-VEGF agents is more effective on suture-induced corneal neovascularization (CoNV) in rabbits.

METHODS

CoNV was induced in 48 eyes of 24 New Zealand white rabbits by using an 8/0 silk suture. On the 7th day after suturing, the rabbits were divided into four treatment groups as follows: six rabbits received subconjunctival bevacizumab (group 1), six rabbits received subconjunctival aflibercept (group 2), six rabbits received intrastromal bevacizumab (group 3) and six rabbits received intrastromal aflibercept (group 4). On the 7th and 14th days after suturing, the CoNV area was calculated by standardised analysis of photographs using the Image-J program. On the 14th day after suturing, all rabbits were sacrificed and then corneal tissue was harvested for the analysis of vascular endothelial growth factor (VEGF)-A, VEGF-B and placental growth factor (PIGF) levels.

RESULTS

On the 7th day after suturing, CoNV areas were 17.10 ± 2.98, 18.88 ± 3.78, 17.36 ± 4.52, 18.57 ± 4.16 and 17.31 ± 2.81 mm² in the groups 1-4 and control group, respectively. On the 7th day after intervention and removal of suture, CoNV areas were 4.85 ± 1.99, 6.66 ± 1.73, 2.83 ± 1.08, 2.63 ± 1.16 and 11.93 ± 2.64 mm² in the group 1-4 and control group, respectively. CoNV area was reduced by 88.1% and 82.5% in eyes receiving intrastromal aflibercept and bevacizumab, respectively (both p < 0.001), and by 64.5% and 69.9% in eyes receiving subconjunctival aflibercept and bevacizumab, respectively (both p = 0.001).

CONCLUSION

Intrastromal anti-VEGF therapy regressed CoNV more effectively than subconjunctival therapy regardless of the type of anti-VEGF agent.

Therapeutic measures for sulfur mustard-induced ocular injury

The use of sulfur mustard (SM) in global terrorism is still a relevant threat to both civilian population and military personnel. Casualties exposed to SM may present mild, moderate or severe acute ocular lesions followed by a complete ocular resolution, chronic lesions or re-emerged ocular pathologies after a latent period. Current treatment for SM-induced ocular injury is based mainly on the clinical manifestation at the different stages of the injury and includes pharmaceutical and surgical interventions. These therapeutic measures are beneficial but not sufficient, and the ocular injury remains a continuous challenge for medical professionals. This review focuses on treatment experience carried out in humans and studied in animal models, for both SM-induced ocular acute injury and late pathology. In general, therapeutic measures are based on clinical features of the ocular injury or on the involvement of specific factors during the ocular injury that point out towards potential treatments. Anti-inflammatory treatments and limbal stem cell transplantation techniques were developed based on the clinical manifestation of the ocular injury. Optional therapies for impaired corneal innervation and endothelium are suggested for future research. Additionally, studies on potential treatments with anti-matrix metalloproteinase (MMP), anti-vascular endothelial growth factor (VEGF) and anti-IL-6 agents are discussed. Consequently, future studies may reveal the potential of additional pharmacological and biological treatments or advanced cellular and molecular biology methods to serve as novel therapeutic measures and techniques for this complicated ocular injury.

Current and emerging therapies for corneal neovascularization

The cornea is unique because of its complete avascularity. Corneal neovascularization (CNV) can result from a variety of etiologies including contact lens wear; corneal infections; and ocular surface diseases due to inflammation, chemical injury, and limbal stem cell deficiency. Management is focused primarily on the etiology and pathophysiology causing the CNV and involves medical and surgical options. Because inflammation is a key factor in the pathophysiology of CNV, corticosteroids and other anti-inflammatory medications remain the mainstay of treatment. Anti-VEGF therapies are gaining popularity to prevent CNV in a number of etiologies. Surgical options including vessel occlusion and ocular surface reconstruction are other options depending on etiology and response to medical therapy. Future therapies should provide more effective treatment options for the management of CNV.

Anti-angiogenic effects of biotechnological therapies in rheumatic diseases

Introduction

Angiogenesis plays a key role in the pathogenesis of numerous rheumatic diseases, such as rheumatoid arthritis, psoriatic arthritis, and vasculitides. Therefore, the inhibition of pathological angiogenesis may be considered a useful therapeutical approach in these rheumatic diseases.

Methods

This review article is based on a literature research about the role of biotechnological therapies in angiogenesis inhibition.

Results and conclusions

Several evidences have demonstrated a role for biotechnological therapies in angiogenesis inhibition. Nevertheless, further research and clinical trials are needed to better quantify the real impact of biotechnological therapies on pathological angiogenesis.

Effects of Combined Photodynamic Therapy and Topical Bevacizumab Treatment on Corneal Neovascularization in Rabbits

PURPOSE

To evaluate the effects of combined photodynamic therapy (PDT) and topical bevacizumab treatment on corneal neovascularization in rabbits.

METHODS

Corneal neovascularization was induced by placing a suture for 7 days in both eyes of 15 rabbits. After suture removal, the right eyes of the rabbits were divided into 3 treatment groups (n = 5 each): group 1, 5 mg/mL bevacizumab eye drops; group 2, PDT at 150 J/cm; and group 3, combined PDT and topical bevacizumab treatment. All 15 left eyes formed a control group. After 2 weeks of treatment, digital photographs were obtained and analyzed to determine the area of corneal neovascularization. The rabbits were then killed to measure vascular endothelial growth factor (VEGF) levels in corneal tissues.

RESULTS

The corneal neovascularization area after treatment was significantly smaller in the 3 treatment groups compared with that in the control group. A significant difference was observed between groups 1 and 2 and group 3, but not between groups 1 and 2. VEGF levels were significantly lower in groups 1 and 3 than in the control group. Although group 2 exhibited relatively higher VEGF levels compared with the control group, the difference was not significant.

CONCLUSIONS

Our results suggest that combined PDT and topical bevacizumab treatment is significantly more effective than monotherapy for the treatment of corneal neovascularization in rabbits. Such quantitative comparison in the laboratory is believed to provide the theoretical basis for clinical application of combined PDT and topical bevacizumab treatment.

Sustained Subconjunctival Delivery of Infliximab Protects the Cornea and Retina Following Alkali Burn to the Eye

Purpose

Tumor necrosis factor (TNF)-α is upregulated in eyes following corneal alkali injury and contributes to corneal and also retinal damage. Prompt TNF-α inhibition by systemic infliximab ameliorates retinal damage and improves corneal wound healing. However, systemic administration of TNF-α inhibitors carries risk of significant complications, whereas topical eye-drop delivery is hindered by poor ocular bioavailability and the need for patient adherence. This study investigates the efficacy of subconjunctival delivery of TNF-α antibodies using a polymer-based drug delivery system (DDS).

Methods

The drug delivery system was prepared using porous polydimethylsiloxane/polyvinyl alcohol composite fabrication and loaded with 85 μg of infliximab. Six Dutch-belted pigmented rabbits received ocular alkali burn with NaOH. Immediately after the burn, subconjunctival implantation of anti-TNF-α DDS was performed in three rabbits while another three received sham DDS (without antibody). Rabbits were followed with photography for 3 months.

Results

After 3 months, the device was found to be well tolerated by the host and the eyes exhibited less corneal damage as compared to eyes implanted with a sham DDS without drug. The low dose treatment suppressed CD45 and TNF-α expression in the burned cornea and inhibited retinal ganglion cell apoptosis and optic nerve degeneration, as compared to the sham DDS treated eyes. Immunolocalization revealed drug penetration in the conjunctiva, cornea, iris, and choroid, with residual infliximab in the DDS 3 months after implantation.

Conclusions

This reduced-risk biologic DDS improves corneal wound healing and provides retinal neuroprotection, and may be applicable not only to alkali burns but also to other inflammatory surgical procedures such as penetrating keratoplasty and keratoprosthesis implantation.

Inhibitory Effect of Topical Aflibercept on Corneal Neovascularization in Rabbits

PURPOSE

To examine the inhibitory effect of topical aflibercept [vascular endothelial growth factor (VEGF) trapR1R2] on corneal neovascularization (NV) in rabbits.

METHODS

Corneal NV was induced in 24 eyes of 12 rabbits. Seven days after a silk suture in the corneal stroma, the rabbits were divided into 4 groups of 6 eyes each. Two groups were treated with topical aflibercept at 2 different concentrations: 2 mg/0.5 mL (0.1%, group 1) and 2 mg/5 mL (0.01%, group 2). The other 2 groups were treated with topical bevacizumab 2.5 mg/1 mL (0.1%, group 3) and topical balanced salt solution (group 4, control). The concentration of VEGF and placental growth factor (PIGF) messenger RNA (mRNA) was measured by reverse transcriptase-polymerase chain reaction.

RESULTS

The surface area of NV was significantly smaller in the treatment groups compared with that of the control group. The expression of VEGF mRNA was 0.227 in 0.1% aflibercept (group 1), 0.811 in 0.01% aflibercept (group 2), and 0.495 in 0.1% bevacizumab (group 3). There was a significant decrease in the VEGF concentration in all 3 treatment groups compared with the control group, 1.491 (P = 0.031, <0.05). In the 0.01% aflibercept group, the difference was less than that of the 0.1% aflibercept and 0.1% bevacizumab groups. There was no significant difference in the 0.1% aflibercept and 0.1% bevacizumab groups. The expression of PIGF mRNA was 0.791 in 0.1% aflibercept (group 1), 0.743 in 0.01% aflibercept (group 2), 1.194 in 0.1% bevacizumab (group 3), and 1.458 in the control group. The expression of PIGF mRNA was significantly decreased in the 0.1% aflibercept and 0.01% aflibercept groups.

CONCLUSIONS

Topical aflibercept may have an inhibitory effect on corneal NV in rabbits.

A Drug Delivery System for Administration of Anti-TNF-α Antibody

PURPOSE

To describe the fabrication, evaluation, and preliminary in vivo safety of a new drug delivery system (DDS) for topical anti-TNF-α antibody administration.

METHODS

A DDS was fabricated using inverse template fabrication of a hydrophobic three-dimensional porous scaffold (100-300 μm in diameter porosity) loaded with 10% polyvinyl alcohol hydrogel carrying 5 mg/ml (weight/volume) of anti-TNF-α antibody. Drug-loaded DDS was sterilized with 25 kGy of gamma irradiation. Long-term in vitro antibody affinity and release was evaluated at room temperature or 37°C using enzyme-linked immunosorbent assay (ELISA) and protein fluorescence. In vivo clinical and histolopathological assessment was performed by subcutaneous implantation in BALB/c mice for 3 months.

RESULTS

Gamma irradiation, repeated dry/wet cycles, and storage at room temperature for 1 year or 37°C for 1 month had no deleterious effects on antibody affinity. Anti-TNF-α release was high during the first minutes of aqueous exposure, followed by stabilization and gradual, low-dose, antibody release over the next 30 days. Histopathologic evaluation of explanted DDS showed a fibrous pseudocapsule and a myxoid acute/chronic inflammation without granuloma formation surrounding the implants.

CONCLUSIONS

Sustained local delivery of anti-TNF-α antibody is feasible using the described DDS, which provides stability of the enclosed antibody for up to 1 year of storage. Preliminary results show good in vivo tolerance following subcutaneous placement for 3 months. The proposed fabrication and sterilization process opens new possibilities for the delivery of biologic agents to the anterior surface of the eye.

TRANSLATIONAL RELEVANCE

The described DDS will facilitate the treatment of ocular surface diseases amenable to biologic therapy.

Tumor necrosis factor-α inhibitors as a treatment of corneal hemangiogenesis and lymphangiogenesis

The cornea is normally devoid of blood and lymphatic vessels; however, a number of infectious/inflammatory diseases can induce corneal neovascularization (CNV). Tumor necrosis factor (TNF)-α, a well known pro-inflammatory cytokine, acts on the vascular endothelium by promoting vasodilatation, edema, and leukocyte recruitment, which are all commonly associated with the development of CNV. Corneal neovascularization is the second cause of blindness worldwide; hence, pharmacological TNF-α inhibition might represent an attractive therapeutic option. Although none of the existing TNF-α antagonists has been registered as a CNV inhibitor, three of them (etanercept, adalimumab, and infliximab) have been proposed to control ocular inflammation. More specifically, it has been demonstrated that infliximab is also effective in reducing hemangiogenesis and lymphangiogenesis in different animal models of CNV. In this article, we review the role of TNF-α on the ocular surface and, in particular, its specific role in the process of CNV. Moreover, we review existing literature and speculate on the potential role of TNF-α inhibitors in the treatment of CNV.

Effects of subconjunctival tocilizumab versus bevacizumab in treatment of corneal neovascularization in rabbits

PURPOSE

The aim of this study was to compare the antiangiogenic effects of subconjunctival application of bevacizumab and tocilizumab on the regression of corneal neovascularization (NV) in rabbits.

METHODS

Corneal neovascularization was induced in 48 eyes of 24 rabbits. Seven days after suture placement, the rabbits were divided into 4 groups of 6 rabbits each and treated subconjunctivally with 0.1 mL balanced salt solution (group 1), 0.1 mL tocilizumab (0.25 mg per 0.1 mL and 2.5 mg per 0.1 mL, groups 2 and 3), or 0.1 mL bevacizumab (2.5 mg per 0.1 mL) (group 4). Digital photographs of the eyes were obtained and the surface areas of corneal neovascularization were measured on days 7 and 14 after subconjunctival injections. On days 7 and 14, 3 rabbits were randomly chosen and the eyes were extracted. Half of the corneal specimens were analyzed histopathologically, and the other half were used to measure the concentrations of vascular endothelial growth factor (VEGF) and IL-6 using a multiplex bead assay, and the levels were compared with those of the controls.

RESULTS

The surface areas of induced corneal neovascularization were significantly smaller in groups 3 and 4 (2.5 mg of tocilizumab and 2.5 mg of bevacizumab) compared with the control group on days 7 and 14 (P < 0.05). Group 2 did not show significant difference from the control group on days 7 and 14. There were no differences observed in the reduced neovascularization areas in groups 3 and 4 on days 7 and 14. The concentrations of VEGF in groups 3 and 4 were significantly lower than in the control group, and IL-6 mRNA levels were significantly lower in group 3 than in the other groups (P < 0.001) on days 7 and 14. Immunohistochemical analysis confirmed the reduced expression of VEGF in all 3 experimental groups compared with the control group.

CONCLUSIONS

An antiangiogenic effect was observed after subconjunctival injection of 2.5 mg tocilizumab to an extent similar to that seen with 2.5 mg bevacizumab, which indicates that subconjunctival application of tocilizumab is effective for the inhibition of corneal neovascularization.

Effect of topical epigallocatechin gallate on corneal neovascularization in rabbits

PURPOSE

The aim of this study was to evaluate the efficacy of topical application of epigallocatechin gallate (EGCG) for the treatment of corneal neovascularization in a rabbit model.

METHODS

Corneal neovascularization was induced in 12 rabbits by placing a black silk suture in the corneal stroma (24 eyes) for a week. After suturing, 1 randomly chosen eye of the 12 rabbits was treated with topical EGCG at 2 different concentrations: 0.01% (group 1) and 0.1% (group 2), whereas the contralateral eyes were treated with sterilized balanced salt solution as the control. All eye drops were applied for 2 weeks after suturing. The suture materials were removed from all eyes on day 7. The surface area of corneal neovascularization was measured and analyzed in all eyes on days 7 and 14. On day 14, all eyes were extracted to measure the concentrations of vascular endothelial growth factor (VEGF) messenger RNA and cyclooxygenase-2 (COX-2) protein.

RESULTS

The surface area of induced corneal neovascularization was significantly smaller only in group 2 compared with that of the control group on days 7 and 14 (P < 0.001). The change in surface area of corneal neovascularization after removal of the suture material was not significantly different between all 3 groups. VEGF messenger RNA levels were significantly lower in group 2 than in the control group (P < 0.001). The concentration of COX-2 was significantly lower in group 2 than in the control group (P = 0.043), but no significant difference was observed between group 1 and the control group.

CONCLUSIONS

Topical administration of EGCG effectively inhibits corneal neovascularization in rabbits. This inhibitory effect is probably related to the suppression of VEGF and COX-2 meditated angiogenesis.

Topical infliximab for the suppression of wound healing following experimental glaucoma filtration surgery

Background

The purpose of this work was to look into the effects of infliximab on wound healing in experimental glaucoma filtration surgery and to compare the antifibrotic effects of this agent to that of mitomycin-C (MMC).

Methods

Twenty-eight male New Zealand White rabbits were randomly assigned to four groups, each including seven rabbits: control group, sham group, MMC group, and infliximab group. The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the MMC treatment group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL MMC was applied intraoperatively to the scleral surgical site for three minutes. The rabbits in the infliximab treatment group underwent trabeculectomy and one drop of 10 mg/mL infliximab was instilled four times a day for 14 days after surgery. On day 14 of the experiment, the operated and control eyes were enucleated and histologically and immunohistochemically analyzed.

Results

The mean fibroblast and mononuclear cell (MNC) numbers and the mean immunostaining intensities of transforming growth factor-β (TGF-β), fibroblast growth factor-β (FGF-β), and platelet-derived growth factor (PDGF) in the sham group were higher than those of the control group (P<0.01). The mean fibroblast and MNC numbers and the mean immunostaining intensities of TGF-β, FGF-β, and PDGF in the MMC and infliximab groups were statistically significantly lower than those of the sham group (P<0.01). The mean fibroblast and MNC numbers and the mean TGF-β, FGF-β, and PDGF immunostaining intensities of the MMC and infliximab groups were similar (P>0.05).

Conclusion

Our study suggests that topical infliximab effectively suppresses the subconjunctival wound healing response after experimental glaucoma filtration surgery, reducing the MNC and fibroblast numbers and immunostaining intensities of TGF-β, FGF-β, and PDGF.