Important Metabolites in Maintaining Folate Cycle, Homocysteine, and Polyamine Metabolism Associated with Ranibizumab Treatment in Cultured Human Tenon's Fibroblasts.

The anti-fibrotic properties of ranibizumab have been well documented. As an antagonist to vascular endothelial growth factor (VEGF), ranibizumab works by binding and neutralizing all active VEGF-A, thus limiting progressive cell growth and proliferation. Ranibizumab application in ocular diseases has shown remarkable desired effects; however, to date, its antifibrotic mechanism is not well understood. In this study, we identified metabolic changes in ranibizumab-treated human Tenon's fibroblasts (HTFs). Cultured HTFs were treated for 48 h with 0.5 mg/mL of ranibizumab and 0.5 mg/mL control IgG antibody which serves as a negative control. Samples from each group were injected into Agilent 6520 Q-TOF liquid chromatography/mass spectrometer (LC/MS) system to establish the metabolite expression in both ranibizumab treated cells and control group. Data obtained was analyzed using Agilent Mass Hunter Qualitative Analysis software to identify the most regulated metabolite following ranibizumab treatment. At p-value < 0.01 with the cut off value of two-fold change, 31 identified metabolites were found to be significantly upregulated in ranibizumab-treated group, with six of the mostly upregulated having insignificant role in fibroblast cell cycle and wound healing regulations. Meanwhile, 121 identified metabolites that were downregulated, and seven of the mostly downregulated are significantly involved in cell cycle and proliferation. Our findings suggest that ranibizumab abrogates the tissue scarring and wound healing process by regulating the expression of metabolites associated with fibrotic activity. In particular, we found that vitamin Bs are important in maintaining normal folate cycle, nucleotide synthesis, and homocysteine and spermidine metabolism. This study provides an insight into ranibizumab's mechanism of action in HTFs from the perspective of metabolomics.

Ocular Permeation of Topical Tazocin and Its Effectiveness in the Treatment of Pseudomonas aeruginosa Induced Keratitis in Rabbits.

PURPOSE: Pseudomonas aeruginosa is the most common causative organism for contact lens-associated corneal ulcer and is commonly treated with fluoroquinolones. With the emergence of resistant strains, it is important to investigate alternative therapies. Despite well-established efficacy of tazocin against systemic Pseudomonas infections, its topical use for the treatment of Pseudomonas keratitis has not been described, hence this study was aimed to find the ocular permeation of Tazocin and its efficacy in treating keratitis in rabbit eyes. METHODS: We investigated the ocular permeation of topical tazocin after single drop application in normal rabbit eyes by estimating piperacillin and tazobactam concentrations in cornea, aqueous, and vitreous using a validated LC-MS/MS method. Furthermore, we determined the efficacy of repeated dose administration of tazocin against experimentally induced P. aeruginosa keratitis in rabbits in comparison to moxifloxacin. To determine the efficacy, clinical examination, histopathological examination, and estimation of bacterial load and inflammatory cytokines in cornea were done. RESULTS: Significant corneal concentration of piperacillin and tazobactam was detected in normal rabbit corneas after single dose treatment with tazocin. In rabbits with Pseudomonas-induced keratitis, topical tazocin caused significant clinical and histopathological improvement. This improvement was associated with reduction in corneal bacterial load and inflammatory cytokines. Compared to moxifloxacin 0.5%, tazocin treated group showed greater clinical response which was associated with higher interleukin (IL)-1ß, lower tumor necrosis factor (TNF)-α, a comparable level of IL-8, greater reduction in corneal bacterial load, and lesser inflammatory cell infiltration. CONCLUSION: Tazocin showed good ocular penetration and was effective in treatment of Pseudomonas induced keratitis in rabbits.

Reduction of oxidative-nitrosative stress underlies anticataract effect of topically applied tocotrienol in streptozotocin-induced diabetic rats.

Cataract, a leading cause of blindness, is of special concern in diabetics as it occurs at earlier onset. Polyol accumulation and increased oxidative-nitrosative stress in cataractogenesis are associated with NFκB activation, iNOS expression, ATP depletion, loss of ATPase functions, calpain activation and proteolysis of soluble to insoluble proteins. Tocotrienol was previously shown to reduce lens oxidative stress and inhibit cataractogenesis in galactose-fed rats. In current study, we investigated anticataract effects of topical tocotrienol and possible mechanisms involved in streptozotocin-induced diabetic rats. Diabetes was induced in Sprague Dawley rats by intraperitoneal injection of streptozotocin. Diabetic rats were treated with vehicle (DV) or tocotrienol (DT). A third group consists of normal, non-diabetic rats were treated with vehicle (NV). All treatments were given topically, bilaterally, twice daily for 8 weeks with weekly slit lamp monitoring. Subsequently, rats were euthanized and lenses were subjected to estimation of polyol accumulation, oxidative-nitrosative stress, NFκB activation, iNOS expression, ATP levels, ATPase activities, calpain activity and total protein levels. Cataract progression was delayed from the fifth week onwards in DT with lower mean of cataract stages compared to DV group (p<0.01) despite persistent hyperglycemia. Reduced cataractogenesis in DT group was accompanied with lower aldose reductase activity and sorbitol level compared to DV group (p<0.01). DT group also showed reduced NFκB activation, lower iNOS expression and reduced oxidative-nitrosative stress compared to DV group. Lenticular ATP and ATPase and calpain 2 activities in DT group were restored to normal. Consequently, soluble to insoluble protein ratio in DT group was higher compared to DV (p<0.05). In conclusion, preventive effect of topical tocotrienol on development of cataract in STZ-induced diabetic rats could be attributed to reduced lens aldose reductase activity, polyol levels and oxidative-nitrosative stress. These effects of tocotrienol invlove reduced NFκB activation, lower iNOS expression, restoration of ATP level, ATPase activities, calpain activity and lens protein levels.

Effects of ranibizumab on TGF-ß1 and TGF-ß2 production by human Tenon's fibroblasts: An in vitro study.

PURPOSE: Inhibiting exaggerated wound healing responses, which are primarily mediated by human Tenon's fibroblast (HTF) migration and proliferation, has become the major determining factor for a successful trabeculectomy. Antivascular endothelial growth factor (anti-VEGF) has showed promising results as a potential antifibrotic candidate for use concurrently in trabeculectomy. Preliminary cohort studies have revealed improved bleb morphology following trabeculectomy augmented with ranibizumab. However, the effects on HTFs remain unclear. This study was conducted to understand the effects of ranibizumab on transforming growth factor (TGF)-ß1 and transforming growth factor (TGF)-ß2 expression by HTFs. METHODS: The effect of ranibizumab on HTF proliferation and cell viability was determined using 3-(4,5-dimethylthiazone-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. Ranibizumab at concentrations ranging from 0.01 to 0.5 mg/ml were administered for 24, 48, and 72 h in serum and serum-free conditions. Supernatants and cell lysates from samples were assessed for TGF-ß1 and TGF-ß2 mRNA and protein levels using quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). RESULTS: At 48 h, 0.5 mg/ml of ranibizumab significantly induced cell death under serum-free culture conditions (p<0.05). Ranibizumab caused a significant reduction in TGF-ß1 mRNA, but not for TGF-ß2. However, the total protein production of TGF-ß1 and TGF-ß2 was unaffected by this anti-VEGF treatment. CONCLUSIONS: Exposure of HTFs to an intravitreal dose of ranibizumab significantly suppresses cell viability in vitro; however, the application seemed unable to affect the ultimate production of TGF-ß. Therefore, we highlighted ranibizumab as a potential antiscarring agent that acts via a different mechanism when used synergistically with another antifibrotic agent. Understanding the mechanism of actions of ranibizumab offers an additional view of a possible new rational therapeutic strategy.

Nasal chondroma presenting as hypertelorism.

PURPOSE: To report a rare case of nasal chondroma presenting as hypertelorism. CASE REPORT: We report a case of a 16-year-old boy with a large calcified mass arising from the posterior nasal cavity presenting as hypertelorism. Surgical excision was done, and the histopathological examination revealed a chondroma. The hypertelorism resolved postoperatively. CONCLUSIONS: Nasal chondroma may also present innocuously as hypertelorism as in this case.

Role of adenosine receptors in resveratrol-induced intraocular pressure lowering in rats with steroid-induced ocular hypertension.

BACKGROUND: Steroid-induced ocular hypertension is currently treated in the same way as primary open-angle glaucoma. However, the treatment is often suboptimal and is associated with adverse effects. We evaluated the oculohypotensive effects of topical trans-resveratrol in rats with steroid-induced ocular hypertension and involvement of adenosine receptors (AR) in intraocular pressure (IOP) lowering effect of trans-resveratrol. METHODS: The oculohypotensive effect of unilateral single-drop application of various concentrations of trans-resveratrol was first studied in oculonormotensive rats. Concentration with maximum effect was similarly studied in rats with steroid-induced ocular hypertension. Involvement of AR was studied by observing the alterations of IOP in response to trans-resveratrol after pretreating animals with AR subtype-specific antagonists. Additionally, we used computational methods, including 3D modelling, 3D structure generation and protein-ligand interaction, to determine the AR-trans-resveratrol interaction. RESULTS: All concentrations of trans-resveratrol produced significant IOP reduction in normotensive rat eyes. Maximum mean IOP reduction of 15.1% was achieved with trans-resveratrol 0.2%. In oculohypertensive rats, trans-resveratrol 0.2% produced peak IOP reduction of 25.2%. Pretreatment with A1 antagonist abolished the oculohypotensive effect of trans-resveratrol. Pretreatment with A3 and A2A AR antagonists produced significant IOP reduction in both treated and control eyes, which was further augmented by trans-resveratrol application in treated eyes. Computational studies showed that trans-resveratrol has highest affinity for A2B and A1, followed by A2A and A3 AR. CONCLUSION: Topically applied trans-resveratrol reduces IOP in rats with steroid-induced ocular hypertension. Trans-resveratrol-induced oculohypotension involves its agonistic activity at the A1 AR.

Effects of ranibizumab on the extracellular matrix production by human Tenon's fibroblast.

Anti-Vascular Endothelial Growth Factors (Anti-VEGF) agents have received recent interest as potential anti-fibrotic agents for their concurrent use with trabeculectomy. Preliminary cohort studies have revealed improved bleb morphology following trabeculectomy augmented with ranibizumab. The effects of this humanized monoclonal antibody on human Tenon's fibroblast (HTF), the key player of post trabeculectomy scar formation, are not fully understood. This study was conducted to understand the effects of ranibizumab on extracellular matrix production by HTF. The effect of ranibizumab on HTF proliferation and cell viability was determined using MTT assay (3-(4,5-dimethylthiazone-2-yl)-2,5-diphenyl tetrazolium). Ranibizumab at concentrations ranging from 0.01 to 0.5 mg/mL were administered for 24, 48 and 72 h in serum and serum free conditions. Supernatants and cell lysates from samples were assessed for collagen type 1 alpha 1 and fibronectin mRNA and protein level using quantitative real time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). After 48-h, ranibizumab at 0.5 mg/mL, significantly induced cell death under serum-free culture conditions (p < 0.05). Ranibizumab caused significant reduction of collagen type 1 alpha 1 (COL1A1) mRNA, but not for fibronectin (FN). Meanwhile, COL1A1 and FN protein levels were found upregulated in treated monolayers compared to control monolayers. Ranibizumab at 0.5 mg/mL significantly reduced cell viability in cultured HTF. From this study, we found that single application of ranibizumab is inadequate to induce the anti-fibrotic effects on HTF, suggesting the importance of adjunctive therapy. Further studies are underway to understand mechanism of actions of ranibizumab on HTF.

Effects of topically applied tocotrienol on cataractogenesis and lens redox status in galactosemic rats.

PURPOSE: Oxidative and nitrosative stress underlies cataractogenesis, and therefore, various antioxidants have been investigated for anticataract properties. Several vitamin E analogs have also been studied for anticataract effects due to their antioxidant properties; however, the anticataract properties of tocotrienols have not been investigated. In this study, we investigated the effects of topically applied tocotrienol on the onset and progression of cataract and lenticular oxidative and nitrosative stress in galactosemic rats. METHODS: In the first part of this study, we investigated the effects of topically applied microemulsion formulation of tocotrienol (TTE) using six concentrations ranging from 0.01% to 0.2%. Eight groups of Sprague-Dawley rats (n = 9) received distilled water, vehicle, or one of the six TTE concentrations as pretreatment topically twice daily for 3 weeks while on a normal diet. After pretreatment, animals in groups 2-8 received a 25% galactose diet whereas group 1 continued on the normal diet for 4 weeks. During this 4-week period, topical treatment continued as for pretreatment. Weekly slit-lamp examination was conducted to assess cataract progression. At the end of the experimental period, the animals were euthanized, and the proteins and oxidative stress parameters were estimated in the lenses. In the second part of the study, we compared the anticataract efficacy of the TTE with the liposomal formulation of tocotrienol (TTL) using five groups of Sprague-Dawley rats (n = 15) that received distilled water, TTE, TTL, or corresponding vehicle. The mode of administration and dosing schedule were the same as in study 1. Weekly ophthalmic examination and lens protein and oxidative stress estimates were performed as in study 1. Lens nitrosative stress was also estimated. RESULTS: During the 4-week treatment period, the groups treated with 0.03% and 0.02% tocotrienol showed slower progression of cataract compared to the vehicle-treated group (p<0.05), whereas the group treated with 0.2% tocotrienol showed faster progression of cataract compared to the vehicle-treated group (p<0.05). The lenticular protein content, malondialdehyde, superoxide dismutase, and catalase levels were normalized in the groups that received 0.03% and 0.02% tocotrienol. The lenticular reduced glutathione also showed a trend toward normalization in these groups. In contrast, the group treated with 0.2% tocotrienol showed increased lenticular oxidative stress. When the microemulsion and liposomal formulations were compared, the effects on cataract progression, lens oxidative and nitrosative stress, and lens protein content did not show significant differences. CONCLUSIONS: Topically applied tocotrienol within the concentration range of less than 0.05% and more than 0.01% tends to delay the onset and progression of cataract in galactose-fed rats by reducing lenticular oxidative and nitrosative stress. However, topical tocotrienol at a concentration of 0.2% and higher aggravates cataractogenesis in galactose-fed rats by increasing lens oxidative stress. The anticataract efficacy of 0.03% microemulsion of tocotrienol did not differ from its liposomal formulations at the same concentration.

Acute primary angle closure attack does not cause an increased cup-to-disc ratio.

PURPOSE: To determine if an increased cup-to-disc ratio (CDR) and retinal nerve fiber layer (RNFL) loss occur after acute primary angle closure (APAC). DESIGN: Prospective, observational case series. PARTICIPANTS: Twenty participants with unilateral APAC provided 20 affected eyes and 20 fellow eyes (controls) for analysis. METHODS: After initial presentation, participants attended 3 further assessments over a 12-month period (visit 2, within 2 weeks; visit 3, 2-3 months; and visit 4, 6-12 months), in which they underwent the following investigations: Heidelberg Retinal Tomography (Heidelberg Engineering, Dossenheim, Germany), optical coherence tomography of the RNFL and macula, and automated perimetry. MAIN OUTCOME MEASURES: Cup-to-disc ratio, optic cup area, neuroretinal rim area, RNFL thickness, macular thickness, and volume. RESULTS: There was no change from visits 2 to 4 in CDR (0.46 ± 0.17 vs. 0.47 ± 0.20; P = 0.94), neuroretinal rim area (1.64 ± 0.55 vs. 1.64 ± 0.57; P = 0.96), or other optic nerve head parameters analyzed in eyes with APAC. The mean overall RNFL thickness decreased from 106.6 ± 17.9 µm to 92.9 ± 18.3 µm between visits 2 and 3 (P<0.01) in affected eyes. The superior quadrant RNFL thickness decreased from 134.8 ± 25.9 µm to 113 ± 25.7 µm (P<0.01), and the inferior quadrant RNFL thickness decreased from 139.1 ± 28.4 µm to 115.6 ± 24.9 µm (P<0.01). There was no significant change in macular thickness or volume. CONCLUSIONS: This study demonstrated that an increase in CDR does not occur after APAC that is treated promptly, although RNFL loss does occur.

Posterior revision for failed blebs: long-term outcomes.

AIM: To report the long-term efficacy and safety of same site revision trabeculectomy with mitomycin application via a posterior approach. METHODS: A noncomparative retrospective case series of consecutive revision trabeculectomies performed for inadequate bleb function between March 2003 and March 2007 by a single surgeon. Surgery involved a posterior/fornix incision with opening of the scleral flap posteriorly at the same site as previous surgery and application of 0.2 to 0.4 mg/mL mitomycin. RESULTS: Fifty-seven eyes were followed for an average of 33 ± 15 months. Mean baseline intraocular pressure (IOP) reduced from 21.5 ± 6.5 to 11.2 ± 4.4 and 8 ± 3.6 mm Hg at 1 and 5 years, respectively (P<0.001). On Kaplan-Meier survival analysis the probability of maintaining IOP ≤ 15 mm Hg without medication at the end of 1 year was 95% (n=57) and at 3 (n=36) and 5 years (n=7) was 84%. Eighty-five percent of patients were on no antiglaucoma drops at last follow-up. Four cases required a second procedure (7%), transient choroidal effusions occurred in 4 eyes (7%), corneal decompensation in 1 eye (1.7%), and ptosis in 1 (1.7%). CONCLUSIONS: Posterior approach to surgical revision of failed filtration surgery is an effective procedure with good long-term control of IOP.

Neuroprotection in glaucoma.

Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells and their axons. Recent evidence suggests that intraocular pressure (IOP) is only one of the many risk factors for this disease. Current treatment options for this disease have been limited to the reduction of IOP; however, it is clear now that the disease progression continues in many patients despite effective lowering of IOP. In the search for newer modalities in treating this disease, much data have emerged from experimental research the world over, suggesting various pathological processes involved in this disease and newer possible strategies to treat it. This review article looks into the current understanding of the pathophysiology of glaucoma, the importance of neuroprotection, the various possible pharmacological approaches for neuroprotection and evidence of current available medications.

Antifibrotic activity of bevacizumab on human Tenon's fibroblasts in vitro.

PURPOSE: To evaluate the effect of the anti-VEGF-A monoclonal antibody bevacizumab on primary human Tenon's capsule fibroblasts (HTFs) in an in vitro model of wound healing. METHODS: Fibroblasts were cultured in RPMI media, and bevacizumab was administered at a concentration ranging from 0.25 to 12.5 mg/mL. Fibroblast viability and cell death were assessed using the MTT colorimetric assay, lactate dehydrogenase assay, BrdU assay, and live/dead assay. Fibroblast contractility was assessed in floating collagen gels. Morphologic changes were assessed by transmission electron microscopy. Antifibrosis activities were compared with 5-fluorouracil. RESULTS: Bevacizumab induced a significant dose-related reduction of HTF cell number at 12.5 mg/mL at 72 hours (P < 0.05). Under serum-free conditions, bevacizumab induced significant fibroblast cell death at concentrations greater than 7.5 mg/mL (P < 0.05). Bevacizumab caused a moderate inhibition of fibroblast gel contraction from baseline (P < 0.05). Scanning electron microscopy revealed marked vacuolization in bevacizumab-treated fibroblasts. CONCLUSIONS: Bevacizumab disrupted fibroblast proliferation, inhibited collagen gel contraction ability, and induced fibroblast cell death at concentrations greater than 7.5 mg/mL in serum-free conditions. These results demonstrated that bevacizumab inhibited a number of fibrosis activities in culture. These activities may underpin the antifibrosis effect proposed in vivo.