Effect of nafamostat on N-methyl-D-aspartate-induced retinal neuronal and capillary degeneration in rats

Cellular communication network factor 1 promotes retinal leakage in diabetic retinopathy via inducing neutrophil stasis and neutrophil extracellular traps extrusion

BACKGROUND

Diabetic retinopathy (DR) is a major cause of blindness and is characterized by dysfunction of the retinal microvasculature. Neutrophil stasis, resulting in retinal inflammation and the occlusion of retinal microvessels, is a key mechanism driving DR. These plugging neutrophils subsequently release neutrophil extracellular traps (NETs), which further disrupts the retinal vasculature. Nevertheless, the primary catalyst for NETs extrusion in the retinal microenvironment under diabetic conditions remains unidentified. In recent studies, cellular communication network factor 1 (CCN1) has emerged as a central molecule modulating inflammation in pathological settings. Additionally, our previous research has shed light on the pathogenic role of CCN1 in maintaining endothelial integrity. However, the precise role of CCN1 in microvascular occlusion and its potential interaction with neutrophils in diabetic retinopathy have not yet been investigated.

METHODS

We first examined the circulating level of CCN1 and NETs in our study cohort and analyzed related clinical parameters. To further evaluate the effects of CCN1 in vivo, we used recombinant CCN1 protein and CCN1 overexpression for gain-of-function, and CCN1 knockdown for loss-of-function by intravitreal injection in diabetic mice. The underlying mechanisms were further validated on human and mouse primary neutrophils and dHL60 cells.

RESULTS

We detected increases in CCN1 and neutrophil elastase in the plasma of DR patients and the retinas of diabetic mice. CCN1 gain-of-function in the retina resulted in neutrophil stasis, NETs extrusion, capillary degeneration, and retinal leakage. Pre-treatment with DNase I to reduce NETs effectively eliminated CCN1-induced retinal leakage. Notably, both CCN1 knockdown and DNase I treatment rescued the retinal leakage in the context of diabetes. In vitro, CCN1 promoted adherence, migration, and NETs extrusion of neutrophils.

CONCLUSION

In this study, we uncover that CCN1 contributed to retinal inflammation, vessel occlusion and leakage by recruiting neutrophils and triggering NETs extrusion under diabetic conditions. Notably, manipulating CCN1 was able to hold therapeutic promise for the treatment of diabetic retinopathy.

Effect of treatment with carteolol and latanoprost in newly diagnosed primary open-angle glaucoma on peripapillary vessel density

BACKGROUND AND AIM

In a previous follow-up of glaucoma patients taking carteolol or latanoprost, we found a greater progression of visual field changes with the prostaglandin than the betablocker. In the present study we compared the impact of carteolol and latanoprost on peripapillary vessel density in newly diagnosed primary open-angle glaucoma (POAG) patients.

METHODS

The study consisted of two groups of POAG patients. There were 46 patient eyes treated with carteolol (Carteol LP 2%) in the first group and 52 eyes treated with latanoprost (Xalatan 0.005%) in the second. Intraocular pressure (IOP), vessel density (VD) and visual field were assessed in all patients. VD was measured peripapillary by optical coherence tomography angiography (OCTA) with the Avanti RTVue XR in eight segments: Inferior Temporal - IT (1); Temporal Inferior -TI (2); Temporal Superior - TS (3); Superior Temporal - ST (4); Superior Nasal - SN (5); Nasal Superior - NS (6); Nasal Inferior - NI (7) and Inferior Nasal - IN (8). The measurements were compared before and after three months of treatment. The visual field was examined with a fast threshold glaucoma program using a Medmont M 700 instrument from Medmont International Pty Ltd. and only when a diagnosis of POAG was done. The overall defect (OD) was assessed.

RESULTS

Before treatment, there was no difference between groups in either OD or VD. After treatment, there was a decrease in IOP in both groups. In the carteolol-treated group, the mean decrease was 5.8 mmHg and in the latanoprost-treated eyes, the mean decrease was 7 mmHg. The difference was not statistically significant (P=0.133). After treatment with carteolol, there was a statistically significant increase in VD in segments 4, 5 and 6. After latanoprost treatment, VD was statistically significantly improved only in segment 5. A greater increase in VD values was found in eyes treated with carteolol than in eyes treated with latanoprost.

CONCLUSION

Carteolol had a better effect on vessel density than latanoprost.

Axons of retinal ganglion cells on the optic nerve disc following vessel density correction at different IOP values

The present study aimed to determine how the vascular density (VD) in each segment peripapillary influences the retinal nerve fiber layer (RNFL) and to eliminate its contribution to RNFL in pathological intraocular pressure (IOP). In a cohort of 69 subjects (mean age, 45±6 years old) with untreated ocular hypertension (122 eyes in total) enrolled in this study, Ocular Response Analyser IOP was measured during routine outpatient care. Its value was >21 (range, 21-36) mmHg in all eyes. Furthermore, peripapillary VD and RNFL were measured using optical coherence tomography in the following eight segments: Inferior temporal (segment 1); temporal inferior (segment 2); temporal superior (segment 3); superior temporal (segment 4); superior nasal (segment 5); nasal superior (segment 6); nasal inferior (segment 7); and inferior nasal (segment 8). The visual field examination was performed with the fast threshold glaucoma program using the Medmont M 700. The overall defect was evaluated. Person's correlation coefficient was used to assess the correlation between VD and IOP. The largest changes were observed in peripapillary segments 1, 4, 5, 6, 7 and 8. The second part of the work was to eliminate the contribution of VD to RNFL. The partial correlation coefficient r was used to adjust RNFL from VD to assess the dependence between the selected parameters. The largest changes in RNFL were in segments 5 and 8 after they had been 'cleaned' of peripapillary VD. In conclusion, the present study revealed that the largest changes in RNFL after VD adjustment were observed for the incipient hypertensive glaucoma in segments 5 and 8.

OCTA and Doppler Ultrasound in Primary Open-Angle Glaucoma and Normal-Tension Glaucoma

The aim of this study was to determine whether the values of vessel density (VD) and perfusion parameters in the ophthalmic artery (OA) and central retinal artery (CRA) of the same eye differ in patients with hypertensive glaucoma (HTG) from patients with normotensive glaucoma (NTG). The first group consisted of 20 HTG patients (40 eyes). Patients with HTG were verified to have primary open-angle glaucoma (POAG). The second group consisted of 20 HTG patients (40 eyes). VD was used to determine the Avanti RTVue XR from Optovue (USA). Peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) were measured in both the central retinal artery (CRA) and ophthalmic artery (OA) using Doppler sonography on the Affinity 70G from Philips (USA). The visual field (VF) was examined by a fast threshold glaucoma program using a Medmont M700 (Australia). We showed no differences in VF, VD, PSV-OA and EDV-CRA between the two groups. Statistically significant differences between the two groups were observed in PSV in CRA (p = 0.04), EDV in OA (p = 0.009) and in RI in both CRA and OA. Other values were without significant differences in both groups. In both HTG and NTG, we observed in PSV-CRA, EDV-OA, RI-CRA and RI-OA.

OCT angiography, RNFL and the visual field at different values of intraocular pressure

The aim of the present study was to investigate the relationship between intraocular pressure (IOP), vessel density (VD), retinal nerve fiber layer (RNFL) parameters and overall defect (OD) of the visual field in eyes where antiglaucoma treatment had not yet been initiated. A total of 61 subjects (122 eyes) who had an IOP of >20 mmHg on several occasions, in at least one eye, in routine outpatient care were included. These were subjects who had never been treated for hypertension glaucoma. The cohort was divided into four subgroups. In the first group, there were 18 eyes with an IOP value of <20 mmHg. In the second group, there were 39 eyes with IOP values of 20-22 mmHg. The third group consisted of 32 eyes with IOP values of 22-24 mmHg and the final group consisted of 33 eyes with IOP values of >24 mmHg. The IOP results were compared with VD, RNFL and OD using Pearson's correlation coefficient to assess the relationship between the selected parameters. RNFL and OD were moderately correlated only in the group of eyes with an IOP value >24 (r=0.48); in the other groups the correlation was very weak. However, changes in visual field were already observed in eyes with IOP 20-22 mmHg (r=-0.27). There was a moderate correlation in eyes with an IOP value >24 mmHg (r=-0.53). The most significant result observed was the relationship between VD and RNFL. In eyes with an IOP value ≤20, a moderate to strong correlation between these parameters was observed. This relationship increased with increasing IOP values up to a very strong correlation in the group with an IOP value >24 mmHg. A moderate to strong dependence between VD and RNFL in eyes with an IOP value ≤20 mmHg was observed, and this dependence was very strongly correlated in the eyes with an IOP value >24 mmHg.

Late Functional and Morphological Findings after Methylalcohol Poisoning

AIM

The aim of the study was to determine the morphological and functional findings in a patient after methanol poisoning. Examination methods: The patient (male, 38 years old) was suffered methanol poisoning in eight years ago (2012). The following tests and examinations were performed: neurological visual field XR test (Medmont M700), retinal nerve fibre layer (RNFL), ganglion cell complex (GCC) and peripapillary vessel density (all using Avanti RTvue, Optovue), pattern electroretinography (PERG) and pattern visual evoked potential (PVEP) examination according to ISCEV methodology (Roland Consult Instrument) and brain MRI examination (Philips Achieva Dstream 3 T).

RESULTS

The biggest changes were found in RNFL and VD. PERG also showed damage to retinal ganglion cell axons. In left eye we determined decrease in oscillations (in comparison with contralateral eye) at N35-P50 and P50-N95. VEPs in both eyes were significantly reduced, almost inconspicuous in the left eye. Extension of latency time of P100 was not identified. Functional MRI showed a bilateral decrease in voxel activity with a greater decrease in the left eye. There were postmalatical changes in the dorsal parts of the putamen on MRI. The width of the optic nerve and chiasm was physiological.

CONCLUSION

Asymmetric damaging of RNFL and cortical centres of the brain were determined. We registered large pathological changes in VD, which are probably responsible for the deepening of optic nerve excavation and further loss of nerve fibers of retinal ganglion cells, which have not yet been described in the literature. Following these results is possible to define direct damage of nerve structures and blood vessels by toxins of methanol metabolism in the acute stage and upcoming reparation processes in following periods.

Nafamostat and sepimostat identified as novel neuroprotective agents via NR2B N-methyl-D-aspartate receptor antagonism using a rat retinal excitotoxicity model

In addition to its role in the treatment of pancreatitis, the serine protease inhibitor nafamostat exhibits a retinal protective effect. However, the exact mechanisms underlying this effect are unknown. In this study, the neuroprotective effects of nafamostat and its orally active derivative sepimostat against excitotoxicity were further characterised in vitro and in vivo. In primary rat cortical neurons, nafamostat completely suppressed N-methyl-D-aspartate (NMDA)-induced cell death. Intravitreal injection of nafamostat and sepimostat protected the rat retina against NMDA-induced degeneration, whereas the structurally related compounds, gabexate and camostat, did not. The neuroprotective effects of nafamostat and the NR2B antagonist ifenprodil were remarkably suppressed by spermidine, a naturally occurring polyamine that modulates the NR2B subunit. Both nafamostat and sepimostat inhibited [³H]ifenprodil binding to fractionated rat brain membranes. Thus, nafamostat and sepimostat may exert neuroprotective effects against excitotoxic retinal degeneration through NMDA receptor antagonism at the ifenprodil-binding site of the NR2B subunit.

Protective Effects of Everolimus against N-Methyl-D-aspartic Acid-Induced Retinal Damage in Rats

We previously demonstrated that rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), protects against N-methyl-D-aspartic acid (NMDA)-induced retinal neurotoxicity, but the mechanism underlying this protection is not fully understood. The present study aimed to examine the effects of everolimus, another inhibitor of mTOR, on neuronal cell loss and inflammation in a rat model of NMDA-induced retinal neurotoxicity, and to determine whether the extracellular signal-regulated kinase (ERK) pathway contributes to the protective effect of everolimus. Intravitreal injection of NMDA (200 nmol) resulted in (1) cell loss in the ganglion cell layer, (2) increase in the numbers of CD45-positive leukocytes and Iba1-positive microglia, and (3) phosphorylation of ribosomal protein S6 (pS6), a downstream indicator of mTOR activity. Simultaneous injection of everolimus with NMDA significantly attenuated these NMDA-induced responses. The neuroprotective effect of everolimus was almost completely prevented by the mitogen-activated protein kinase/ERK kinase inhibitor U0126 (1 nmol). NMDA increased the level of phosphorylated ERK (pERK) in Müller cells, and increase in pERK levels was also observed after co-injection of NMDA and everolimus. These results suggest that everolimus has a neuroprotective effect against NMDA-induced retinal neurotoxicity, an effect that seems to be mediated partly by activation of the ERK pathway in Müller cells.

Protective effects of PF-4708671 against N-methyl-d-aspartic acid-induced retinal damage in rats

We previously demonstrated that rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), protects against N-methyl-d-aspartic acid (NMDA)-induced retinal damage in rats. Rapamycin inhibits mTOR activity, thereby preventing the phosphorylation of ribosomal protein S6, which is a downstream target of S6 kinase. Therefore, we aimed to determine whether PF-4708671, an inhibitor of S6 kinase, protects against NMDA-induced retinal injury. Intravitreal injection of NMDA (200 nmol/eye) caused cell loss in the ganglion cell layer and neuroinflammatory responses, such as an increase in the number of CD45-positive leukocytes and Iba1-positive microglia. Surprisingly, simultaneous injection of PF-4708671 (50 nmol/eye) with NMDA significantly attenuated these responses without affecting phosphorylated S6 levels. These results suggest that PF-4708671 and rapamycin likely protect against NMDA-induced retinal damage via distinct pathways. The neuroprotective effect of PF-4708671 is unlikely to be associated with inhibition of the S6 kinase, even though PF-4708671 is reported to be a S6 kinase inhibitor.

Preventive effects of rapamycin on inflammation and capillary degeneration in a rat model of NMDA-induced retinal injury

Inhibitors of the mammalian target of rapamycin (mTOR) have been shown to protect against neuronal injury, but the mechanisms underlying this effect are not fully understood. The present study aimed to examine the effects of rapamycin, an inhibitor of the mTOR pathway, on inflammation and capillary degeneration in a rat model of N-methyl-D-aspartate (NMDA)-induced retinal neurotoxicity. Inflammation and capillary degeneration were evaluated by counting the numbers of CD45-positive leukocytes and Iba1-positive microglia, and by measuring the length of empty basement membrane sleeves, respectively. Marked increases in the numbers of leukocytes and microglia were observed 1 d after intravitreal injection of NMDA (200 nmol), and significant capillary degeneration was observed after 7 d. These NMDA-induced changes were significantly reduced by the simultaneous injection of rapamycin (20 nmol) with NMDA. These results suggest that rapamycin has preventive effects on inflammation and capillary degeneration during retinal injury.

Design, Virtual Screening, and Synthesis of Antagonists of αIIbβ3 as Antiplatelet Agents

This article describes design, virtual screening, synthesis, and biological tests of novel αIIbβ3 antagonists, which inhibit platelet aggregation. Two types of αIIbβ3 antagonists were developed: those binding either closed or open form of the protein. At the first step, available experimental data were used to build QSAR models and ligand- and structure-based pharmacophore models and to select the most appropriate tool for ligand-to-protein docking. Virtual screening of publicly available databases (BioinfoDB, ZINC, Enamine data sets) with developed models resulted in no hits. Therefore, small focused libraries for two types of ligands were prepared on the basis of pharmacophore models. Their screening resulted in four potential ligands for open form of αIIbβ3 and four ligands for its closed form followed by their synthesis and in vitro tests. Experimental measurements of affinity for αIIbβ3 and ability to inhibit ADP-induced platelet aggregation (IC50) showed that two designed ligands for the open form 4c and 4d (IC50 = 6.2 nM and 25 nM, respectively) and one for the closed form 12b (IC50 = 11 nM) were more potent than commercial antithrombotic Tirofiban (IC50 = 32 nM).

Age-dependent changes in the severity of capillary degeneration in rat retina following N-methyl-D-aspartate-induced neurotoxicity

PURPOSE

Previous studies have shown that injury to the retinal vasculature, including capillary degeneration, occurs following N-methyl-d-aspartate (NMDA)-induced neuronal cell loss, but it is unclear whether there are age-dependent differences in the severity of vascular damage. The purpose of the present study was to determine age-related changes in retinal capillary degeneration in NMDA-induced retinal damage rat model.

MATERIALS AND METHODS

A single intravitreal injection of NMDA (200 nmol/eye) was performed in 1-, 2-, 3-, 7- and 15-week-old male Sprague-Dawley rats. Seven days after NMDA injection, damage to retinal neurons and blood vessels were assessed by measuring the number of cells in the ganglion cell layer and the length of empty basement membrane sleeves, left behind by regressing endothelial cells, respectively.

RESULTS

At all ages examined, the NMDA-induced neurotoxicity exhibited similar levels of ganglion cell death. However, the degeneration of capillaries in NMDA-treated retina was severe during the early stages of retinal vascular development, and the degree of capillary degeneration decreased with age.

CONCLUSION

The degree of retinal capillary degeneration in NMDA-induced retinal damage rat model decreases in an age-dependent manner. Retinal capillaries may be resistant to retinal neuronal damage in young adults.

Rapamycin prevents N-methyl-D-aspartate-induced retinal damage through an ERK-dependent mechanism in rats

Recent studies have demonstrated that inhibition of the mammalian target of rapamycin (mTOR) protects against neuronal injury, but the mechanisms underlying this protection are not fully understood. The present study investigates whether rapamycin, an inhibitor of the mTOR pathway, protects against N-methyl-D-aspartate (NMDA)-induced retinal neurotoxicity and whether the extracellular signal-regulated kinase (ERK) pathway contributes to this protective effect in rats. Significant cell loss in the ganglion cell layer and a reduction in thickness of the inner plexiform layer were observed 7 days after a single intravitreal injection of NMDA (200 nmol/eye). These NMDA-induced morphological changes were significantly reduced by rapamycin (20 nmol/eye). The number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive apoptotic cells had increased 6 hr after NMDA injection, an effect that was significantly attenuated by rapamycin. The ERK inhibitor U0126 (1 nmol/eye) almost completely abolished rapamycin's inhibition of NMDA-induced apoptosis. Immunohistochemical studies showed that NMDA caused a time-dependent increase in levels of the phosphorylated form of the ribosomal protein S6 (pS6), a downstream indicator of mTOR activity. The increased pS6 levels were markedly decreased by rapamycin. Both NMDA and rapamycin increased the level of phosphorylated ERK (pERK) in Müller cells, and coinjection of both agents further increased pERK levels. These results suggest that rapamycin has a neuroprotective effect against NMDA-induced retinal neurotoxicity and that this effect could be patially mediated by activation of the ERK pathway in retinal Müller cells.

ISO-1, a macrophage migration inhibitory factor antagonist, prevents N-methyl-D-aspartate-induced retinal damage

Macrophage migration inhibitory factor (MIF) has been shown to play an important role in a variety of inflammatory and immune-mediated diseases. The inflammatory responses contribute to retinal neuronal degeneration. However, the role of MIF in the progression of retinal degeneration has not yet been elucidated. In this study, we determined whether pharmacological inhibition of MIF protects against the retinal damage induced by N-methyl-D-aspartate (NMDA) in rats. Intravitreal injection of NMDA (200 nmol) resulted in (1) cell loss in the ganglion cell layer and reduction in the thickness of the inner plexiform layer, (2) an increase in apoptotic cells, (3) a decrease in parvalbumin-positive amacrine cells, (4) accumulation of leukocytes, and (5) microglia activation. Injection of (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1, 100 nmol), a MIF antagonist, significantly attenuated these NMDA-induced responses. These findings suggest that ISO-1 exerts protective effects against retinal injuries and that MIF may be a target for neuroprotective intervention in retinal diseases associated with glutamate-induced excitotoxicity.