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Autotaxin, also known as ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2), is a secreted enzyme that has lysophospholipase D activity, which converts lysophosphatidylcholine to bioactive lysophosphatidic acid. Lysophosphatidic acid activates at least six G-protein coupled recpetors, which promote cell proliferation, survival, migration and muscle contraction. These physiological effects become dysfunctional in the pathology of cancer, fibrosis, and pain. To date, several autotaxin/ENPP2 inhibitors have been reported; however, none were able to completely and continuously inhibit autotaxin/ENPP2 in vivo. In this study, we report the discovery of a highly potent autotaxin/ENPP2 inhibitor, ONO-8430506, which decreased plasma lysophosphatidic acid formation. The IC50 values of ONO-8540506 for lysophospholipase D activity were 6.4–19 nM for recombinant autotaxin/ENPP2 proteins and 4.7–11.6 nM for plasma from various animal species. Plasma lysophosphatidic acid formation during 1-h incubation was almost completely inhibited by the addition of >300 nM of the compound to human plasma. In addition, when administered orally to rats at a dose of 30 mg/kg, the compound demonstrated good pharmacokinetics in rats and persistently inhibited plasma lysophosphatidic acid formation even at 24 h after administration. Smooth muscle contraction is a known to be promoted by lysophosphatidic acid. In this study, we showed that dosing rats with ONO-8430506 decreased intraurethral pressure accompanied by urethral relaxation. These findings demonstrate the potential of this autotaxin/ENPP2 inhibitor for the treatment of various diseases caused by lysophosphatidic acid, including urethral obstructive disease such as benign prostatic hyperplasia. [ABSTRACT FROM AUTHOR]

Abstract: We investigated whether P2X7 antagonists rescue retinal ganglion cells (RGCs) in culture and after optic nerve crush (ONC) injury. Rats were sacrificed 7 days after retrograde labeling of RGCs with 4′,6-diamidino-2-phenylindole (DAPI), and the retinas were enzymatically dissociated in vitro and incubated with P2X7 antagonists or agonists for 3 days. Adenosine triphosphate (ATP) and benzoylbenzoyl ATP were used as P2X7 agonists, and oxidized ATP and brilliant blue G were used as P2X7 antagonists. DAPI-positive and calcein-positive RGCs were counted to determine the number of living cells. We observed that RGCs were preserved when treated with P2X7 antagonists, as compared with the controls. In contrast, P2X7 agonists significantly decreased the number of viable RGCs. In vivo, P2X7 antagonists at various doses were injected into the vitreous body immediately after ONC injuries in rats. Surviving RGCs were stained with anti-neuron-specific β-tubulin antibody in flat-mounted retinas. RGCs were observed to decrease to 61% of baseline 7 days after ONC injury, whereas RGCs were significantly preserved when P2X7 antagonists were applied. When P2X7 receptor expression was examined immunohistochemically in rat retinas after ONC, the retinal expression of the P2X7 receptors was observed to be upregulated after ONC and peaked on day 3. Meanwhile, P2X7 antagonists suppressed this upregulation. Collectively, these results suggest that P2X7 antagonists prevent loss of RGCs after ONC, and that this protective effect is possibly mediated through suppressing the upregulation of retinal P2X7 expression. [Copyright &y& Elsevier]

Purpose: To report the short-term efficacy and safety of the transfer of an Ahmed™ glaucoma valve (AGV™) tube from the vitreous into the anterior chamber, in a patient with neovascular glaucoma who had undergone pars plana AGV™ implantation and ultimately needed a silicone oil tamponade. Case: A 41-year-old male with proliferative diabetic retinopathy in both eyes was referred to us for treatment in December 2009. Although the patient previously underwent several surgeries, he ultimately lost vision in his right eye. His left eye suffered from neovascular glaucoma after undergoing a pars plana vitrectomy for tractional retinal detachment. After several vitreous and glaucoma surgeries, the patient underwent implantation of a pars plana AGV™. Postoperatively, although his intraocular pressure was stabilized at approximately 10 mmHg, he had repeated vitreous hemorrhage and hyphema without improvement. He ultimately underwent PPV with a silicone oil tamponade and at the same time, the AGV™ tube was pulled out from the vitreous and inserted into the anterior chamber in order to avoid complications caused by the silicone oil. Results: At 19 months postoperative, the patient's intraocular pressure had stabilized at 10 mmHg with no recurrence of vitreous hemorrhage and hyphema. Eventually, he lost vision in his left eye because of cerebral hemorrhage. Conclusion: The findings show that insertion of a pars plana AGV™ tube into the anterior chamber in a patient undergoing a silicone oil tamponade is both effective and safe in the short-term. [ABSTRACT FROM AUTHOR]

EAU in mice is a model of human posterior uveitis. EAU is a Th1-dependent disease that has been assumed to target the neural retina and related tissues; however, in situ effector cells and the target have not yet been clearly demonstrated. In the present study, we induced EAU in B10R mice by immunizing them with human interphotoreceptor retinoid-binding protein peptide 161–180. Histological examinations revealed that EAU occurred approximately 11 days after the immunization and reached a peak on day 14. Retinae from normal or EAU mice were treated with proteases to obtain mono-dispersed cells. The mono-dispersed cells thus obtained were separated into three to four fractions by discontinuous Percoll density-gradient (e.g. PBS/40/60) centrifugation. In normal mice, 94% of the total cells were recovered in two fractions (i.e. PBS/40 and pellet); and these fractions mainly contained inner and outer segments and cell bodies of photoreceptor cells and RPE cells, respectively. In EAU mice, additional cells (i.e. inflammatory cells) were obtained at the 40/60 interface. Electron microscopic examination showed that tissue damage during EAU was initiated by non-phagocytic destruction of inner segments by Mac-1+ mononuclear cells on day 11, followed by phagocytic activity of macrophages against outer segments and RPE cells on day 14. In vitro culturing of normal retinal cells with EAU infiltrates suggested the involvement of TNF-α and NO in the tissue damage. These results indicate that EAU was initiated by non-phagocytic destruction of inner segments of photoreceptor cells by Mac-1+ mononuclear cells. [ABSTRACT FROM AUTHOR]

The purpose if this study was to elucidate how extracellular ATP causes cell death in the retinal microvasculature. Although ATP appears to serve as a vasoactive signal acting via P2X7 and P2Y4 purinoceptors, this nucleotide can kill microvascular cells of the retina. Because P2X7 receptor activation causes transmembrane pores to form and microvascular cells to die, we initially surmised that pore formation accounted for ATP's lethality. To test this hypothesis, we isolated pericyte-containing microvessels from rat retinas, assessed cell viability using Trypan blue dye exclusion, detected pores by determining the uptake of the fluorescent dye YO-PRO-1, measured intracellular Ca2+ with the use of fura-2, and monitored ionic currents via perforated patch pipettes. As predicted, ATP-induced cell death required P2X7 receptor activation. However, we found that pore formation was minimal because ATP's activation of P2Y4 receptors prevented P2X7 pores from forming. Rather than opening lethal pores, ATP kills via a mechanism involving voltage-dependent Ca2+ channels (VDCC). Our experiments suggest that when high concentrations of ATP caused nearly all microvascular P2X7 receptor channels to open, the resulting profound depolarization opened VDCC. Consistent with lethal Ca2+ influx via VDCC. ATP-induced cell death was markedly diminished by the VDCC blocker nifedipine or a nitric oxide (NO) donor that inhibited microvascular VDCC. We propose that purinergic vasotoxicity is normally prevented in the retina by NO-mediated inhibition of VDCC and P2Y4-mediated inhibition of P2X7 pore formation. Conversely, dysfunction of these protective mechanisms may be a previously unrecognized cause of cell death within the retinal microvasculature. [ABSTRACT FROM AUTHOR]

Purpose. Two pathways for the formation of angiotensin II (Ang II) in local tissues are known to exist, one involving angiotensin-converting enzyme (ACE), and the other in which chymase plays a role. It has been shown that chymase activity is present in monkey, dog, and hamster eyes. Because chymase activates various cytokines by increasing Ang II formation, thereby promoting the production of extracellular matrix, the role of Ang II in wound healing has attracted much interest. In this work, we created sclerocorneal wounds in hamster eyes and measured the levels of ACE and chymase activities in the eye during the wound healing process. Methods. Sclerocorneal wounds were made at 6 locations on the corneal limbus of one eye in each of 36 hamsters. Using the contralateral eyes as controls, we measured levels of chymase and ACE activities in the overall eye at 3, 7, and 21 days postoperatively. Histopathological evaluations of the sclerocorneal wounds in the treated eyes were also carried out for samples stained with toluidine blue. Results. Chymase activity in the treated eyes tended to be higher than that in the control at 21 days. ACE activity in the treated eyes was significantly higher than that in the control at 3, 7, and 21 days postoperatively. Histopathological examination revealed increased mast cells in the subconjunctival tissue and around the tunnel opening in the sclerocornea. Conclusions. These findings show that not only ACE but also chymase contributes to the formation of Ang II in the healing of sclerocorneal wounds in hamster eyes. This leads to the suggestion that ACE inhibitors or chymase inhibitors could potentially inhibit scarring in glaucoma filtering surgery. [ABSTRACT FROM AUTHOR]

Purpose. To study the effects of topically applied nipradilol, an α-B blocker recently developed in Japan as an ocular hypotensive drug, on retinal blood flow (RBF) in healthy volunteers. Methods. Seven healthy volunteers (mean age, 33 years) underwent measurement of RBF using a newly developed stabilized laser Doppler velocimetry system. In a double-blind trial, retinal arterial blood flow, intraocular pressure (IOP), and blood pressure (BP) were measured before and after the instillation of nipradilol or saline every hour for 5 hours. Results. Retinal arterial blood flow and the diameter of the retinal artery significantly (p < 0.05) increased at 4 hours after installation in nipradilol-treated eyes. Retinal blood velocity did not change in significantly. Nipradilol evoked a significant (p < 0.05) bilateral decrease in IOP. Mean BP decreased significantly (p < 0.05) 3 hours after installation. Ocular perfusion pressure (OPP), calculated from the mean BP and IOP, did not change significantly during the study. Conclusion. Topical nipradilol significantly increased retinal arterial blood flow in healthy volunteers, not through a secondary effect dependent on a change in OPP, but likely through the vasodilatory action of the drug. [ABSTRACT FROM AUTHOR]

We examined the effects of lomerizine, a new diphenylmethylpiperazine Ca[sup 2+] channel blocker, on the normal circulation in the optic nerve head and long posterior ciliary artery, and on endothelin-1-induced hypoperfusion in the optic nerve head in anesthetized rabbits using a hydrogen gas clearance method and laser Doppler flowmetry. These effects were compared with those of nilvadipine and pranidipine. Lomerizine (0.1 and 0.3 mg/kg, i.v.) significantly increased tissue blood flow in the optic nerve head and the putative blood flow in the long posterior ciliary artery with smaller reduction of blood pressure (0.3 mg/kg, i.v.) and without change in heart rate. On the other hand, nilvadipine (0.003 and 0.01 mg/kg, i.v.) and pranidipine (0.003 and 0.01 mg/kg, iv.) each significantly increased blood flow and lowered blood pressure. Moreover, lomerizine (0.1 and 0.3 mg/kg, i.v.) and nilvadipine (0.01 mg/kg, i.v.), when administered 5 min before an endothelin-1 injection (10[sup -6] M, 100 μl), inhibited the hypoperfusion in the optic nerve head. These results suggest that lomerizine improves the ocular circulation with minimal cardiovascular side effects. Therefore, lomerizine may have clinical potential for the treatment of eye diseases associated with local circulatory disturbances, such as normal-tension glaucoma. [ABSTRACT FROM AUTHOR]

Purpose. To assess the influence of the blood glucose level on ocular capillary circulation, we induced clinically significant hyperglycemia (200-300mg/dl) in rabbits and investigated the changes in the optic nerve head (ONH) circulation. Methods. Hyperglycemia was induced by injection of glucose (5.6mmol/kg) into an auricular vein of healthy albino rabbits and changes in the ONH circulation were measured by the laser speckle method. In order to examine the role of nitric oxide (NO), glucose was administered after intravenous injection of an NO synthetase inhibitor (N[sup G]nitro-L-arginine methyl ester, L-NAME, l mg/kg), then changes in the ONH circulation were measured. Results. The blood glucose level reached a peak at 30 min after glucose loading and returned to its initial level by 2 hours. ONH circulation showed a 60% increase compared with its initial level at 15 min after glucose loading and subsequently remained almost unchanged throughout the 2-hour observation period. There were no significant changes of the blood pressure, heart rate, or intraocular pressure. The glucose-induced increase of ONH circulation was completely inhibited by pretreatment with L-NAME. Conclusions. ONH circulation was increased by administration of glucose to healthy rabbits. A high blood glucose level seems to promote ocular capillary circulation and NO as well as insulin appear to have a role in this process. [ABSTRACT FROM AUTHOR]

PURPOSE. To investigate the effect of topical iganidipine,a new dihydropyridine derivative calcium channel blocker, on impairment ofthe ocular circulation caused by endothelin-1 (ET-1), we examined modificationof the effect of ET-1 on visual-evoked potential (VEP) in albino rabbits. METHODS. To clarify whether VEP could be used to indicate the extent ofocular circulatory impairment, we evaluated the dose dependency of changesin VEP over 2 hours after intravitreal injection of 3 ET-1 doses (1.0, 3.3,or 10 pmol) and the vehicle. Then modification of the effect of ET-1 on theVEP by iganidipine was examined. One hour after the topical instillation of0.1% iganidipine (20 μl) or its vehicle, 10 pmol of ET-1 was injected intothe vitreous in rabbits. The VEP was measured for 2 hours after ET-1 application,and the response was compared between the eyes with iganidipine and vehiclepretreatment. RESULTS. Intravitreal injection of ET-1 dose-dependently reduced the VEPamplitude. Topical administration of 0.1% iganidipine significantly suppressedthe reduction of VEP amplitude for the entire 2-hour monitoring period afterintravitreal injection of 10 pmol ET-1. There was no significant change ofthe systemic blood pressure as well as intraocular pressure after topicaladministration of iganidipine. CONCLUSIONS. Iganidipine eyedrops may be useful for the treatment of ischemicretinal and optic nerve disorders related to abnormal ET-1 production forthe maintenance of visual function. [ABSTRACT FROM AUTHOR]

This case report describes a case of Alagille syndrome with developing intraocular lens subluxation and rhegmatogenous retinal detachment 4 years after cataract surgery. A 15-year-old female patient with Alagille syndrome-associated cataracts in both eyes underwent phacoemulsification aspiration and intraocular lens implantation. Four years postoperative, intraocular lens subluxation developed in her left eye. For treatment, extraction of the dislocated intraocular lens, anterior vitrectomy, and intraocular lens fixation was performed. Three weeks later, the patient developed rhegmatogenous retinal detachment, which was well-treated by pars plana vitrectomy. Cataract surgery needs to be performed carefully in patients with Alagille syndrome due to the weakness of the zonule of Zinn. Careful postoperative observation is necessary for patients with Alagille syndrome who have undergone intraocular surgery in order to facilitate early detection of a possible rhegmatogenous retinal detachment. [ABSTRACT FROM AUTHOR]

Regorafenib eye drops were developed for treating age-related macular degeneration. This study aimed to investigate the effects of this multi-kinase inhibitor on intraocular pressure (IOP), bleb formation, and conjunctival changes in a canine filtration surgery model. Glaucoma filtration surgery models were created in 24 eyes of 24 beagles. In experiment 1 (Ex 1), regorafenib eye drops (regorafenib group: n = 6) or a vehicle (control group, n = 6) were instilled twice daily for 4 weeks postoperatively. In experiment 2 (Ex 2), regorafenib eye drops were instilled as in Ex 1 (regorafenib group: n = 6) for 12 weeks while conventional intraoperative mitomycin-C (MMC) was utilized (MMC group: n = 6), In Ex 1, only the regorafenib group showed significant IOP reduction with a significantly higher bleb score. Subconjunctival area, collagen density, vessels, and cells showing proliferation and differentiation were lower in subconjunctival tissue in the regorafenib group. In Ex 2, no significant difference was found in IOP reduction and bleb formation between the regorafenib and MMC groups; bleb walls were significantly thicker and collagen density and vessels were higher in the regorafenib group; and no differences were observed in the above-mentioned cells. Thus, regorafenib might be a better alternative to MMC for creating thicker and less ischemic blebs in glaucoma filtration surgery. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate regional cerebral blood flow (rCBF) in normal-tension glaucoma patients (NTGs) compared with normal volunteers (controls) in a pilot study. Design: Observational cohort study. Methods: The Iodine-123-IMP single photon emission computed tomography (SPECT) scans were acquired in 31 NTGs and 18 age-matched controls. The SPECT images in NTGs were classified and the quantitative rCBF data were compared with controls. Results: Seven of 31 NTGs (22.6%) exhibited an Alzheimer's disease (AD)-like perfusion pattern although none of them were clinically diagnosed with AD. The visual field defect of NTGs with an AD-like pattern progressed more rapidly than NTGs with a normal pattern (P=.132). The rCBF in left parietal regions of NTGs with senile sclerotic or focal ischemic disk was significantly lower than controls (P<.05). Conclusions: A number of NTGs exhibited an AD-like perfusion pattern, suggesting that some of NTGs and AD patients might have a common pathologic mechanism. [ABSTRACT FROM AUTHOR]