Pigment epithelium-derived factor decreases outflow facility

High VEGF Concentrations Accelerate Human Trabecular Meshwork Fibrosis in a TAZ-Dependent Manner

We aimed to investigate the effects of different concentrations of vascular endothelial growth factor (VEGF) on the extracellular matrix (ECM) and fibrotic proteins in human trabecular meshwork (TM) cells. We also explored how the Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) signaling pathway modulates VEGF-induced fibrosis. We determined cross-linked actin network (CLAN) formation using TM cells. Changes in fibrotic and ECM protein expression were determined. High VEGF concentrations (10 and 30 ng/mL) increased TAZ and decreased p-TAZ/TAZ expression in TM cells. Western blotting and real-time PCR revealed no YAP expression changes. Fibrotic and ECM protein expression decreased at low VEGF concentrations (1 and 10 ρg/mL) and significantly increased at high VEGF concentrations (10 and 30 ng/mL). CLAN formation increased in TM cells treated with high VEGF concentrations. Moreover, TAZ inhibition by verteporfin (1 μM) rescued TM cells from high-VEGF-concentration-induced fibrosis. Low VEGF concentrations reduced fibrotic changes, whereas high VEGF concentrations accelerated fibrosis and CLAN formations in TM cells in a TAZ-dependent manner. These findings reflect the dose-dependent influences of VEGF on TM cells. Moreover, TAZ inhibition might be a therapeutic target for VEGF-induced TM dysfunction.

Intracameral Injection of AAV-DJ.COMP-ANG1 Reduces the IOP of Mice by Reshaping the Trabecular Outflow Pathway

Purpose

The angiopoietin-1 (ANG1)-TIE signaling pathway orchestrates the development and maintenance of the Schlemm's canal (SC). In this study, we investigated the impact of adeno-associated virus (AAV)-mediated gene therapy with cartilage oligomeric matrix protein-ANG1 (COMP-ANG1) on trabecular outflow pathway.

Methods

Different serotypes of AAVs were compared for transduction specificity and efficiency in the anterior segment. The selected AAVs encoding COMP-ANG1 or ZsGreen1 (control) were delivered into the anterior chambers of wild-type C57BL/6J mice. The IOP and ocular surface were monitored regularly. Ocular perfusion was performed to measure the outflow facility and label flow patterns of the trabecular drainage pathway. Structural features of SC as well as limbal, retinal, and skin vessels were visualized by immunostaining. Ultrastructural changes in the SC and trabecular meshwork were observed under transmission electron microscopy.

Results

AAV-DJ could effectively infect the anterior segment. Intracameral injection of AAV-DJ.COMP-ANG1 lowered IOP in wild-type C57BL/6J mice. No signs of inflammation or angiogenesis were noticed. Four weeks after AAV injection, the conventional outflow facility and effective filtration area were increased significantly (P = 0.005 and P = 0.04, respectively). Consistently, the area of the SC was enlarged (P < 0.001) with increased density of giant vacuoles in the inner wall (P = 0.006). In addition, the SC endothelia lay on a more discontinuous basement membrane (P = 0.046) and a more porous juxtacanalicular tissue (P = 0.005) in the COMP-ANG1 group.

Conclusions

Intracamerally injected AAV-DJ.COMP-ANG1 offers a significant IOP-lowering effect by remodeling the trabecular outflow pathway of mouse eyes.

Therapeutic Drugs and Devices for Tackling Ocular Hypertension and Glaucoma, and Need for Neuroprotection and Cytoprotective Therapies

Damage to the optic nerve and the death of associated retinal ganglion cells (RGCs) by elevated intraocular pressure (IOP), also known as glaucoma, is responsible for visual impairment and blindness in millions of people worldwide. The ocular hypertension (OHT) and the deleterious mechanical forces it exerts at the back of the eye, at the level of the optic nerve head/optic disc and lamina cribosa, is the only modifiable risk factor associated with glaucoma that can be treated. The elevated IOP occurs due to the inability of accumulated aqueous humor (AQH) to egress from the anterior chamber of the eye due to occlusion of the major outflow pathway, the trabecular meshwork (TM) and Schlemm’s canal (SC). Several different classes of pharmaceutical agents, surgical techniques and implantable devices have been developed to lower and control IOP. First-line drugs to promote AQH outflow via the uveoscleral outflow pathway include FP-receptor prostaglandin (PG) agonists (e.g., latanoprost, travoprost and tafluprost) and a novel non-PG EP2-receptor agonist (omidenepag isopropyl, Eybelis^®). TM/SC outflow enhancing drugs are also effective ocular hypotensive agents (e.g., rho kinase inhibitors like ripasudil and netarsudil; and latanoprostene bunod, a conjugate of a nitric oxide donor and latanoprost). One of the most effective anterior chamber AQH microshunt devices is the Preserflo^® microshunt which can lower IOP down to 10–13 mmHg. Other IOP-lowering drugs and devices on the horizon will be also discussed. Additionally, since elevated IOP is only one of many risk factors for development of glaucomatous optic neuropathy, a treatise of the role of inflammatory neurodegeneration of the optic nerve and retinal ganglion cells and appropriate neuroprotective strategies to mitigate this disease will also be reviewed and discussed.

Aqueous Humor Outflow Requires Active Cellular Metabolism in Mice

Purpose

Conventional wisdom posits that aqueous humor leaves the eye by passive bulk flow without involving energy-dependent processes. However, recent studies have shown that active processes, such as cell contractility, contribute to outflow regulation. Here, we examine whether inhibiting cellular metabolism affects outflow facility in mice.

Methods

We measured outflow facility in paired enucleated eyes from C57BL/6J mice using iPerfusion. We had three Experimental Sets: ES1, perfused at 35°C versus 22°C; ES2, perfused with metabolic inhibitors versus vehicle at 35°C; and ES3, perfused at 35°C versus 22°C in the presence of metabolic inhibitors. Inhibitors targeted glycolysis and oxidative phosphorylation (2-deoxy-D-glucose, 3PO and sodium azide). We also measured adenosine triphosphate (ATP) levels in separate murine anterior segments treated like ES1 and ES2.

Results

Reducing temperature decreased facility by 63% [38%, 78%] (mean [95% confidence interval (CI)], n = 10 pairs; P = 0.002) in ES1 after correcting for changes in viscosity. Metabolic inhibitors reduced facility by 21% [9%, 31%] (n = 9, P = 0.006) in ES2. In the presence of inhibitors, temperature reduction decreased facility by 44% [29%, 56%] (n = 8, P < 0.001) in ES3. Metabolic inhibitors reduced anterior segment adenosine triphosphate (ATP) levels by 90% [83%, 97%] (n = 5, P<<0.001), but reducing temperature did not affect ATP.

Conclusions

Inhibiting cellular metabolism decreases outflow facility within minutes. This implies that outflow is not entirely passive, but depends partly on energy-dependent cellular processes, at least in mice. This study also suggests that there is a yet unidentified mechanism, which is strongly temperature-dependent but metabolism-independent, that is necessary for nearly half of normal outflow function in mice.

The vital role for nitric oxide in intraocular pressure homeostasis

Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.

Application of Cell Impedance as a Screening Tool to Discover Modulators of Intraocular Pressure

Purpose: To identify new targets and compounds involved in mediating cellular contractility or relaxation in trabecular meshwork (TM) cells and test their efficacy in an ex vivo model measuring outflow facility. Methods: A low-molecular weight compound library composed of 3,957 compounds was screened for cytoskeletal changes using the Acea xCelligence impedance platform in immortalized human NTM5 TM cells. Hits were confirmed by 8-point concentration response and were subsequently evaluated for impedance changes in 2 primary human TM strains, as well as cross-reactivity in bovine primary cells. A recently described bovine whole eye perfusion system was used to evaluate effects of compounds on aqueous outflow facility. Results: The primary screen conducted was robust, with Z' values >0.5. Fifty-two compounds were identified in the primary screen and confirmed to have concentration-dependent effects on impedance in NTM5 cells. Of these, 9 compounds representing distinct drug classes were confirmed to modulate impedance in both human primary TM cells and bovine cells. One of these compounds, wortmannin, an inhibitor of phosphoinositide 3-kinase, increased outflow facility by 11%. Conclusions: A robust phenotypic assay was developed that enabled identification of contractility modulators in immortalized TM cells. The screening hits were translatable to primary TM cells and modulated outflow facility in an ex vivo perfusion assay.

No flow through the vitreous humor: How strong is the evidence?

When analyzing vitreal drug delivery, or the pharmacological effects of drugs on intraocular pressure, or when interpreting outflow facility measurements, it is generally accepted that the fluid in the vitreous humor is stagnant. It is accepted that for all practical purposes, the aqueous fluid exits the eye via anterior pathways only, and so there is negligible if any posteriorly directed flow of aqueous through the vitreous humor. This assumption is largely based on the interpretation of experimental data from key sources including Maurice (1957), Moseley (1984), Gaul and Brubaker (1986), Maurice (1987) and Araie et al. (1991). However, there is strong independent evidence suggesting there is a substantial fluid flow across the retinal pigment epithelium from key sources including Cantrill and Pederson (1984), Chihara and Nao-i, Tsuboi (1985), Dahrouj et al. (2014), Smith and Gardiner (2017) and Smith et al. (2019). The conflicting evidence creates a conundrum-how can both interpretations be true? This leads us to re-evaluate the evidence. We demonstrate that the data believed to be supporting no aqueous flow through the vitreous are in fact compatible with a significant normal aqueous flow. We identify strong and independent lines of evidence supporting fluid flow across the RPE, including our new outflow model for the eye. On balance it appears the current evidence favors the view that there is normally a significant aqueous flow across the RPE in vivo. This finding suggests that past and future analyses of outflow facility, interpretations of some drug distributions and the interpretation of some drug effects on eye tissues, may need to be revised.

Plexin domain containing 2 (PLXDC2) gene polymorphism rs7081455 may not influence POAG risk in a Saudi cohort

Objective

Plexin domain containing 2 (PLXDC2), a cell surface transmembrane protein receptor for pigment epithelium derived factor, is expressed in many tissues including the eye. Polymorphism rs7081455 flanking PLXDC2 has been associated with primary open angle glaucoma (POAG) and its clinical phenotypes and may have a role in POAG. Rs7081455 was genotyped in POAG cases (n = 188) and non-glaucomatous controls (n = 164) of Saudi origin using Taq-Man^® to determine any association of this variant with POAG and its endophenotypes.

Results

The risk variant, ‘G’ allele, frequency was 0.56 and 0.52 in controls and POAG cases, respectively (p = 0.197) with was no significant deviation from Hardy–Weinberg equilibrium. Genotype analysis between cases and controls revealed no significant distribution under additive (p = 0.482), dominant (p = 0.590) and recessive models (p = 0.228). In addition, glaucoma specific phenotypic traits such as intraocular pressure (IOP) and cup/disc ratio; and number of anti-glaucoma medications, used to assess severity of the disease, were also statistically non-significant. Furthermore, regression analysis showed no significant effect of age, sex and genotype on disease outcome. Rs7081455 was not associated with POAG or its clinical phenotypes such as IOP and cup/disc ratio and hence may not be a significant risk factor for POAG patients of Saudi origin.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3848-x) contains supplementary material, which is available to authorized users.

Genetic Variant Near PLXDC2 Influences the Risk of Primary Open-angle Glaucoma by Increasing Intraocular Pressure in the Japanese Population

PURPOSE

The purpose of this study is to assess the association between the genetic variants that were previously reported to be associated with primary open-angle glaucoma (POAG) in the Japanese population and the phenotypic features.

METHODS

A total of 661 Japanese patients including 417 patients with POAG [normal tension glaucoma (NTG), n=210; high tension glaucoma (HTG), n=207] and 244 control subjects without glaucoma were analyzed for 3 genetic variants: rs547984 (near gene: ZP4), rs7081455 (PLXDC2), and rs7961953 (TMTC2). The allele frequency differences between POAG (NTG or HTG) patients and control subjects were estimated. The association between these genetic variants and the phenotypic features, including the maximum intraocular pressure (IOP) and the vertical cup-to-disc ratio, was evaluated.

RESULTS

There was a significant difference in the rs7081455 (PLXDC2) allele frequencies between the POAG (P=0.0050) patients and the control subjects. An almost 1.5 increase in the risk of POAG (P=0.0042, odds ratio 1.52) was found with a G allele of rs7081455 (PLXDC2). The maximum IOP [23.5±10.3 mm Hg (mean±SD)] in patients with the GG genotype of rs7081455 (PLXDC2) was significantly higher (P=0.0037) than that (19.9±7.4 mm Hg) in patients with the TT genotype.

CONCLUSIONS

The genetic variant near the PLXDC2 gene was found to influence the risk of POAG by increasing IOP in the Japanese population.

Direct measurement of pressure-independent aqueous humour flow using iPerfusion

Reduction of intraocular pressure is the sole therapeutic target for glaucoma. Intraocular pressure is determined by the dynamics of aqueous humour secretion and outflow, which comprise several pressure-dependent and pressure-independent mechanisms. Accurately quantifying the components of aqueous humour dynamics is essential in understanding the pathology of glaucoma and the development of new treatments. To better characterise aqueous humour dynamics, we propose a method to directly measure pressure-independent aqueous humour flow. Using the iPerfusion system, we directly measure the flow into the eye when the pressure drop across the pressure-dependent pathways is eliminated. Using this approach we address i) the magnitude of pressure-independent flow in ex vivo eyes, ii) whether we can accurately measure an artificially imposed pressure-independent flow, and iii) whether the presence of a pressure-independent flow affects our ability to measure outflow facility. These studies are conducted in mice, which are a common animal model for aqueous humour dynamics. In eyes perfused with a single cannula, the average pressure-independent flow was 1 [-3, 5] nl/min (mean [95% confidence interval]) (N = 6). Paired ex vivo eyes were then cannulated with two needles, connecting the eye to both iPerfusion and a syringe pump, which was used to impose a known pressure-independent flow of 120 nl/min into the experimental eye only. The measured pressure-independent flow was then 121 [117, 125] nl/min (N = 7), indicating that the method could measure pressure-independent flow with high accuracy. Finally, we showed that the artificially imposed pressure-independent flow did not affect our ability to measure facility, provided that the pressure-dependence of facility and the true pressure-independent flow were accounted for. The present study provides a robust method for measurement of pressure-independent flow, and demonstrates the importance of accurately quantifying this parameter when investigating pressure-dependent flow or outflow facility.

Anterior chamber perfusion versus posterior chamber perfusion does not influence measurement of aqueous outflow facility in living mice by constant flow infusion

Mice are now routinely utilized in studies of aqueous humor outflow dynamics. In particular, conventional aqueous outflow facility (C) is routinely measured via perfusion of the aqueous chamber by a number of laboratories. However, in mouse eyes perfused ex-vivo, values for C are variable depending upon whether the perfusate is introduced into the posterior chamber (PC) versus the anterior chamber (AC). Perfusion via the AC leads to posterior bowing of the iris, and traction on the iris root/scleral spur, which may increase C. Perfusion via the PC does not yield this effect. But the equivalent situation in living mice has not been investigated. We sought to determine whether AC versus PC perfusion of the living mouse eye may lead to different values for C. All experiments were conducted in C57BL/6J mice (all ♀) between the ages of 20 and 30 weeks. Mice were divided into groups of 3-4 animals each. In all groups, both eyes were perfused. C was measured in groups 1 and 2 by constant flow infusion (from a 50 μL microsyringe) via needle placement in the AC, and in the PC, respectively. To investigate the effect of ciliary muscle (CM) tone on C, groups 3 and 4 were perfused live via the AC or PC with tropicamide (muscarinic receptor antagonist) added to the perfusate at a concentration of 100 μM. To investigate immediate effect of euthanasia, groups 5 and 6 were perfused 15-30 min after death via the AC or PC. To investigate the effect of CM tone on C immediately following euthanasia, groups 7 and 8 were perfused 15-30 min after death via the AC or PC with tropicamide added to the perfusate at a concentration of 100 μM. C in Groups 1 (AC perfusion) and 2 (PC perfusion) was computed to be 19.5 ± 0.8 versus 21.0 ± 2.1 nL/min/mmHg, respectively (mean ± SEM, p > 0.4, not significantly different). In live animals in which tropicamide was present in the perfusate, C in Group 3 (AC perfusion) was significantly greater than C in Group 4 (PC perfusion) (22.0 ± 4.0 versus 14.0 ± 2.0 nL/min/mmHg, respectively, p = 0.0021). In animals immediately following death, C in groups 5 (AC perfusion) and 6 (PC perfusion) was computed to be 21.2 ± 2.0 versus 22.8 ± 1.4 nL/min/mmHg, respectively (mean ± SEM, p = 0.1196, not significantly different). In dead animals in which tropicamide was present in the perfusate, C in group 7 (AC perfusion) was greater than C in group 8 (PC perfusion) (20.6 ± 1.4 versus 14.2 ± 2.6 nL/min/mmHg, respectively, p < 0.0001). C in eyes in situ in living mice or euthanized animals within 15-30 min post mortem is not significantly different when measured via AC perfusion or PC perfusion. In eyes of live or freshly euthanized mice, C is greater when measured via AC versus PC perfusion when tropicamide (a mydriatic and cycloplegic agent) is present in the perfusate.

VEGF as a Paracrine Regulator of Conventional Outflow Facility

Purpose

Vascular endothelial growth factor (VEGF) regulates microvascular endothelial permeability, and the permeability of Schlemm's canal (SC) endothelium influences conventional aqueous humor outflow. We hypothesize that VEGF signaling regulates outflow facility.

Methods

We measured outflow facility (C) in enucleated mouse eyes perfused with VEGF-A₁₆₄a, VEGF-A₁₆₅b, VEGF-D, or inhibitors to VEGF receptor 2 (VEGFR-2). We monitored VEGF-A secretion from human trabecular meshwork (TM) cells by ELISA after 24 hours of static culture or cyclic stretch. We used immunofluorescence microscopy to localize VEGF-A protein within the TM of mice.

Results

VEGF-A₁₆₄a increased C in enucleated mouse eyes. Cyclic stretch increased VEGF-A secretion by human TM cells, which corresponded to VEGF-A localization in the TM of mice. Blockade of VEGFR-2 decreased C, using either of the inhibitors SU5416 or Ki8751 or the inactive splice variant VEGF-A₁₆₅b. VEGF-D increased C, which could be blocked by Ki8751.

Conclusions

VEGF is a paracrine regulator of conventional outflow facility that is secreted by TM cells in response to mechanical stress. VEGF affects facility via VEGFR-2 likely at the level of SC endothelium. Disruption of VEGF signaling in the TM may explain why anti-VEGF therapy is associated with decreased outflow facility and sustained ocular hypertension.

The Soluble Guanylate Cyclase Stimulator IWP-953 Increases Conventional Outflow Facility in Mouse Eyes

PURPOSE

The nitric oxide (NO)-cyclic guanosine-3',5'-monophosphate (cGMP) pathway regulates aqueous humor outflow and therefore, intraocular pressure. We investigated the pharmacologic effects of the soluble guanylate cyclase (sGC) stimulator IWP-953 on primary human trabecular meshwork (HTM) cells and conventional outflow facility in mouse eyes.

METHODS

Cyclic GMP levels were determined in vitro in HEK-293 cells and four HTM cell strains (HTM120/HTM123: predominantly myofibroblast-like phenotype, HTM130/HTM141: predominantly endothelial-like phenotype), and in HTM cell culture supernatants. Conventional outflow facility was measured following intracameral injection of IWP-953 or DETA-NO using a computerized pressure-controlled perfusion system in enucleated mouse eyes ex vivo.

RESULTS

IWP-953 markedly stimulated cGMP production in HEK-293 cells in the presence and absence of DETA-NO (half maximal effective concentrations: 17 nM, 9.5 μM). Similarly, IWP-953 stimulated cGMP production in myofibroblast-like HTM120 and HTM123 cells, an effect that was greatly amplified by the presence of DETA-NO. In contrast, IWP-953 stimulation of cGMP production in endothelial-like HTM130 and HTM141 cells was observed, but was markedly less prominent than in HTM120 and HTM123 cells. Notably, cGMP was found in all HTM culture supernatants, following IWP-953/DETA-NO stimulation. In paired enucleated mouse eyes, IWP-953 at 10, 30, 60, and 100 μM concentration-dependently increased outflow facility. This effect (89.5%) was maximal at 100 μM (P = 0.002) and in magnitude comparable to DETA-NO at 100 μM (97.5% increase, P = 0.030).

CONCLUSIONS

These data indicate that IWP-953, via modulation of the sGC-cGMP pathway, increases aqueous outflow facility in mouse eyes, suggesting therapeutic potential for sGC stimulators as novel ocular hypotensive drugs.

Dose- and time-dependent effects of actomyosin inhibition on live mouse outflow resistance and aqueous drainage tissues

Actomyosin contractility modulates outflow resistance of the aqueous drainage tissues and intraocular pressure, a key pathogenic factor of glaucoma. We established methodology to reliably analyze the effect of latrunculin-B (Lat-B)-induced actin depolymerization on outflow physiology in live mice. A voltage-controlled microperfusion system for delivering drugs and simultaneously analyzing outflow resistance was tested in live C57BL/6 mice. Flow rate and perfusion pressure were reproducible within a coefficient of variation of 2%. Outflow facility for phosphate-buffered saline (0.0027 ± 0.00036 μL/min/mmHg; mean ± SD) and 0.02% ethanol perfusions (Lat-B vehicle; 0.0023 ± 0.0005 μL/min/mmHg) were similar and stable over 2 hours (p > 0.1 for change), indicating absence of a ‘washout’ artifact seen in larger mammals. Outflow resistance changed in graded fashion, decreasing dose- and time-dependently over 2 hours for Lat-B doses of 2.5 μM (p = 0.29), 5 μM (p = 0.039) and 10 μM (p = 0.001). Resulting outflow resistance was about 10 times lower with 10 μM Lat-B than vehicle control. The filamentous actin network was decreased and structurally altered in the ciliary muscle (46 ± 5.6%) and trabecular meshwork (37 ± 8.3%) of treated eyes relative to vehicle controls (p < 0.005; 5 μM Lat-B). Mouse actomyosin contractile mechanisms are important to modulating aqueous outflow resistance, mirroring mechanisms in primates. We describe approaches to reliably probe these mechanisms in vivo.

Administration of Pigment Epithelium-Derived Factor Inhibits Airway Inflammation and Remodeling in Chronic OVA-Induced Mice via VEGF Suppression

Purpose

Pigment epithelium-derived factor (PEDF) is a recently discovered antiangiogenesis protein. PEDF possesses powerful anti-inflammatory, antioxidative, antiangiogenic, and antifibrosis properties. It has been reported that PEDF can regulate vascular endothelial growth factor (VEGF) expression. This study aimed to evaluate whether recombinant PEDF protein could attenuate allergic airway inflammation and airway remodeling via the negative regulation of VEGF using a murine model of chronic ovalbumin (OVA)-induced asthma and BEAS-2B human bronchial epithelial cells.

Methods

In an in vivo experiment, mice sensitized with OVA were chronically airway challenged with aerosolized 1% OVA solution for 8 weeks. Treated mice were given injections of recombinant PEDF protein (50 or 100 µg/kg body weight) via the tail vein. In an in vitro experiment, we investigated the effects of recombinant PEDF protein on VEGF release levels in BEAS-2B cells stimulated with IL-1β.

Results

Recombinant PEDF protein significantly inhibited eosinophilic airway inflammation, airway hyperresponsiveness, and airway remodeling, including goblet cell hyperplasia, subepithelial collagen deposition, and airway smooth muscle hypertrophy. In addition, recombinant PEDF protein suppressed the enhanced expression of VEGF protein in lung tissue and bronchoalveolar lavage fluid (BALF) in OVA-challenged chronically allergic mice. In the in vitro experiment, VEGF expression was increased after IL-1β stimulation. Pretreatment with 50 and 100 ng/mL of recombinant PEDF protein significantly attenuated the increase in VEGF release levels in a concentration-dependent manner in BEAS-2B cells stimulated by IL-1β.

Conclusions

These results suggest that recombinant PEDF protein may abolish the development of characteristic features of chronic allergic asthma via VEGF suppression, providing a potential treatment option for chronic airway inflammation diseases such as asthma.

High-throughput screening for modulators of cellular contractile force

When cellular contractile forces are central to pathophysiology, these forces comprise a logical target of therapy. Nevertheless, existing high-throughput screens are limited to upstream signalling intermediates with poorly defined relationships to such a physiological endpoint. Using cellular force as the target, here we report a new screening technology and demonstrate its applications using human airway smooth muscle cells in the context of asthma and Schlemm's canal endothelial cells in the context of glaucoma. This approach identified several drug candidates for both asthma and glaucoma. We attained rates of 1000 compounds per screening day, thus establishing a force-based cellular platform for high-throughput drug discovery.

The structure of the trabecular meshwork, its connections to the ciliary muscle, and the effect of pilocarpine on outflow facility in mice

PURPOSE

To determine the connections between the ciliary muscle (CM), trabecular meshwork (TM), and Schlemm's canal (SC) and their innervations that allows CM contraction (by pilocarpine) to influence conventional outflow in mice.

METHODS

Sequential sections and whole mounts of murine corneoscleral angles were stained for elastin, α-smooth muscle actin (αSMA), vesicular acetylcholine transporter (VAChT), neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP), and tyrosine hydroxylase (TH). Elastic (EL) fibers between the CM, TM, and SC were examined in ultrathin, sequential sections from different planes. The effect of pilocarpine (100 μM) on conventional outflow facility was measured by perfusion of enucleated mouse eyes.

RESULTS

The mouse TM contains a three-dimensional (3D) net of EL fibers connecting the inner wall of SC to the cornea anteriorly, the ciliary body (CB) internally and the choroid and CM posteriorly. The CM bifurcates near the posterior TM, extending outer tendons to the juxtacanalicular tissue and inner wall of SC and internal connections to the lamellated TM and CB. Ciliary muscle and lamellated TM cells stain with αSMA and are innervated by VAChT-containing nerve fibers, without TH, VIP, or nNOS. Pilocarpine doubled outflow facility.

CONCLUSIONS

Mouse eyes resemble primate eyes not only by their well developed SC and TM, but also by their 3D EL net tethering together the TM and SC inner wall and by the tendinous insertion of the CM into this net. The increase in outflow facility following cholinergic stimulation in mice, as in primates, supports using mice for studies of aqueous humor dynamics and glaucoma.