Diquafosol Improves Corneal Wound Healing by Inducing NGF Expression in an Experimental Dry Eye Model.

Dry eye disease (DED) is caused by inflammation and damage to the corneal surface due to tear film instability and hyperosmolarity. Various eye drops are used to treat this condition. Each eye drop has different properties and mechanisms of action, so the appropriate drug should be used according to clinical phenotypes. This study aims to compare the therapeutic mechanisms of cyclosporine A (CsA) and diquafosol tetrasodium (DQS). An experimental in vivo/in vitro model of DED using hyperosmolarity showed decreased cell viability, inhibited wound healing, and corneal damage compared to controls. Treatment with cyclosporine or diquafosol restored cell viability and wound healing and reduced corneal damage by hyperosmolarity. The expression of the inflammation-related genes il-1ß, il-1α, and il-6 was reduced by cyclosporine and diquafosol, and the expression of Tnf-α, c1q, and il-17a was reduced by cyclosporine. Increased apoptosis in the DED model was confirmed by increased Bax and decreased Bcl-2 and Bcl-xl expression, but treatment with cyclosporine or diquafosol resulted in decreased apoptosis. Diquafosol increased NGF expression and translocation into the extracellular space. DED has different damage patterns depending on the progression of the lesion. Thus, depending on the type of lesion, eye drops should be selected according to the therapeutic target, focusing on repairing cellular damage when cellular repair is needed or reducing inflammation when inflammation is high and cellular damage is severe.

Multifunctional Cerium Oxide Nanozyme for Synergistic Dry Eye Disease Therapy.

Dry eye disease (DED) is a chronic multifactorial ocular surface disease mainly caused by the instability of tear film, characterized by a series of ocular discomforts and even visual disorders. Oxidative stress has been recognized as an upstream factor in DED development. Diquafosol sodium (DQS) is an agonist of the P2Y2 receptor to restore the integrity/stability of the tear film. With the ability to alternate between Ce3+ and Ce4+, cerium oxide nanozymes could scavenge overexpressed reactive oxygen species (ROS). Hence, a DQS-loaded cerium oxide nanozyme was designed to boost the synergistic treatment of DED. Cerium oxide with branched polyethylenimine-graft-poly(ethylene glycol) as nucleating agent and dispersant was fabricated followed with DQS immobilization via a dynamic phenylborate ester bond, obtaining the DQS-loaded cerium oxide nanozyme (defined as Ce@PBD). Because of the ability to mimic the cascade processes of superoxide dismutase and catalase, Ce@PBD could scavenge excessive accumulated ROS, showing strong antioxidant and anti-inflammatory properties. Meanwhile, the P2Y2 receptors in the conjunctival cells could be stimulated by DQS in Ce@PBD, which can relieve the incompleteness and instability of the tear film. The animal experiments demonstrated that Ce@PBD significantly restored the defect of the corneal epithelium and increased the number of goblet cells, with the promotion of tear secretion, which was the best among commercial DQS ophthalmic solutions.

Silencing NTPDase3 activity rehabilitates the osteogenic commitment of post-menopausal stem cell bone progenitors.

BACKGROUND: Endogenously released adenine and uracil nucleotides favour the osteogenic commitment of bone marrow-derived mesenchymal stromal cells (BM-MSCs) through the activation of ATP-sensitive P2X7 and UDP-sensitive P2Y6 receptors. Yet, these nucleotides have their osteogenic potential compromised in post-menopausal (Pm) women due to overexpression of nucleotide metabolizing enzymes, namely NTPDase3. This prompted us to investigate whether NTPDase3 gene silencing or inhibition of its enzymatic activity could rehabilitate the osteogenic potential of Pm BM-MSCs. METHODS: MSCs were harvested from the bone marrow of Pm women (69 ± 2 years old) and younger female controls (22 ± 4 years old). The cells were allowed to grow for 35 days in an osteogenic-inducing medium in either the absence or the presence of NTPDase3 inhibitors (PSB 06126 and hN3-B3s antibody); pre-treatment with a lentiviral short hairpin RNA (Lenti-shRNA) was used to silence the NTPDase3 gene expression. Immunofluorescence confocal microscopy was used to monitor protein cell densities. The osteogenic commitment of BM-MSCs was assessed by increases in the alkaline phosphatase (ALP) activity. The amount of the osteogenic transcription factor Osterix and the alizarin red-stained bone nodule formation. ATP was measured with the luciferin-luciferase bioluminescence assay. The kinetics of the extracellular ATP (100 µM) and UDP (100 µM) catabolism was assessed by HPLC RESULTS: The extracellular catabolism of ATP and UDP was faster in BM-MSCs from Pm women compared to younger females. The immunoreactivity against NTPDase3 increased 5.6-fold in BM-MSCs from Pm women vs. younger females. Selective inhibition or transient NTPDase3 gene silencing increased the extracellular accumulation of adenine and uracil nucleotides in cultured Pm BM-MSCs. Downregulation of NTPDase3 expression or activity rehabilitated the osteogenic commitment of Pm BM-MSCs measured as increases in ALP activity, Osterix protein cellular content and bone nodule formation; blockage of P2X7 and P2Y6 purinoceptors prevented this effect. CONCLUSIONS: Data suggest that NTPDase3 overexpression in BM-MSCs may be a clinical surrogate of the osteogenic differentiation impairment in Pm women. Thus, besides P2X7 and P2Y6 receptors activation, targeting NTPDase3 may represent a novel therapeutic strategy to increase bone mass and reduce the osteoporotic risk of fractures in Pm women.

Diquafosol sodium reduces neuronal activity in trigeminal subnucleus caudalis in a rat model of chronic dry eye disease.

Patients with persistent and severe dry eye disease (DED) have corneal hypersensitivity, resulting in ocular pain, and diquafosol sodium, a potent P2Y2 receptor agonist, is commonly used to improve the resultant tear film stability. This study determined the effects of diquafosol instillation on the suppression of trigeminal subnucleus caudalis (Vc) neuronal activity and ocular pain by enhancing tear film stability in the model for chronic DED. The effects of diquafosol on the ocular surface were assessed by the topical application for 28 days, starting from the 14th day since unilateral exorbital gland removal (chronic DED). Loss of tear volume secretion in chronic DED rats was significantly reversed by diquafosol instillation after 28 days, compared with saline treatment. The number of eyeblinks and pERK-IR neurons in the superficial laminae of Vc following hypertonic saline administration to the ocular surface was lower in diquafosol-treated chronic DED rats than in saline-treated rats. The neuronal activity evoked by hypertonic saline and mechanical stimulation along with the spontaneous neuronal activity in the superficial laminae of the Vc were suppressed in diquafosol-treated chronic DED rats. These findings suggest that ocular surface instillation of diquafosol for 28 days attenuates the neuronal hyperactivity in the Vc and the ocular pain that often occurs in chronic DED.

Adipocyte purinergic receptors activated by uracil nucleotides as obesity and type 2 diabetes targets.

Extracellular uridine nucleotides regulate physiological and pathophysiological metabolic processes through the activation of P2Y2, P2Y4, P2Y6 and P2Y14 purinergic receptors, which play a key role in adipogenesis, glucose uptake, lipolysis and adipokine secretion. Using adipocyte-specific knockout mouse models, it has been demonstrated that lack of the P2Y6R or P2Y14R can protect against diet-induced obesity and improve whole-body glucose metabolism. The P2Y2R facilitated adipogenesis and inflammation, and the loss of P2Y4R or P2Y14R raised the levels of the protective endocrine factor adiponectin. Hence, potent antagonists for these receptors may be tested to identify drug candidates for the treatment of obesity and type 2 diabetes. However, future studies are required to provide insight into purinergic regulation of brown adipocytes and their role in thermogenesis. This review summarizes the current studies on uridine nucleotide-activated P2YRs and their role in adipocyte function, diet-induced obesity and associated metabolic deficits.

4'-Fluorouridine is an oral antiviral that blocks respiratory syncytial virus and SARS-CoV-2 replication.

The COVID-19 pandemic has underscored the critical need for broad-spectrum therapeutics against respiratory viruses. Respiratory syncytial virus (RSV) is a major threat to pediatric patients and older adults. We describe 4'-fluorouridine (4'-FlU, EIDD-2749), a ribonucleoside analog that inhibits RSV, related RNA viruses, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with high selectivity index in cells and human airway epithelia organoids. Polymerase inhibition within in vitro RNA-dependent RNA polymerase assays established for RSV and SARS-CoV-2 revealed transcriptional stalling after incorporation. Once-daily oral treatment was highly efficacious at 5 milligrams per kilogram (mg/kg) in RSV-infected mice or 20 mg/kg in ferrets infected with different SARS-CoV-2 variants of concern, initiated 24 or 12 hours after infection, respectively. These properties define 4'-FlU as a broad-spectrum candidate for the treatment of RSV, SARS-CoV-2, and related RNA virus infections.

A randomised, prospective study of the effects of 3% diquafosol on ocular surface following cataract surgery.

There is still no established therapeutic solution for postoperative Dry Eye Syndrome (DES) after cataract surgery, in spite of progress in surgical techniques. Diquafosol tetrasodium (DQS), a recently developed ophthalmic solution, has been reported to be effective in DES, but no study evaluated post-cataract surgery lipid layer thickness (LLT) changes in healthy patients who used DQS postoperatively. We randomly divided participants into two groups; the DQS group was treated six times daily with DQS after cataract surgery, and the sodium hyaluronate (HA) group was treated with HA in the same way. Throughout study period, the DQS group showed significantly higher tear break up time (TBUT) and LLT than HA group. In multivariate analysis, better preoperative TBUT, Schirmer's I test score, ocular surface disease index (OSDI) score, and LLT were significantly associated with improved postoperative outcomes in each parameter. Also, the postoperative use of DQS served as an independent parameter of better TBUT, OSDI score, and LLT in postoperative 15 weeks. Treatment with 3% DQS following cataract surgery showed more improvement in TBUT and LLT, compared with 0.1% HA. Improving TBUT and LLT preoperatively and using 3% DQS postoperatively, could be a reliable choice for managing DES after cataract surgery.Trial Registration: ISRCTN registry with ISRCTN 18755487.

Diquafosol tetrasodium elicits total cholesterol release from rabbit meibomian gland cells via P2Y2 purinergic receptor signalling.

Diquafosol tetrasodium (DQS), a purinergic P2Y2 receptor agonist, stimulates secretion of both water and mucins from the conjunctiva into tears. Hence, DQS-containing eye drops have been approved as a therapeutic option for dry eye disease in some Asian countries, including Japan. Recent clinical reports state that instilling DQS-containing eye drops significantly increases the lipid layer thickness in tears. Therefore, we examined this compound's direct actions on holocrine lipid-secreting meibomian gland cells and their function. Isolated meibomian gland cells (meibocytes) were procured from rabbits and cultivated in serum-free culture medium. Differentiated meibocytes with pioglitazone were used for the subsequent experiments. Intracellular Ca2+ signalling of the cells was dramatically elevated with DQS addition in a dose-dependent manner. This DQS-induced elevation was almost completely cancelled by the coexistence of the selective P2Y2 receptor antagonist AR-C118925XX. DQS treatment also facilitated total cholesterol (TC) release from cells into the medium. This effect of DQS on TC was suppressed significantly by the intracellular Ca2+ chelator BAPTA-AM as well as by AR-C118925XX. DNA fragmentation analysis revealed that DQS may have enhanced the apoptotic DNA fragmentation caused spontaneously by cells. Thus, DQS could stimulate meibocytes to release lipids through the P2Y2 receptor and possibly facilitate holocrine cell maturation.

Synthesis and biological evaluation of 5'-C-methyl nucleotide prodrugs for treating HCV infections.

Nucleotide prodrugs are of great clinical interest for treating a variety of viral infections due to their ability to target tissues selectively and to deliver relatively high concentrations of the active nucleotide metabolite intracellularly. However, their clinical successes have been limited, oftentimes due to unwanted in vivo metabolic processes that reduce the quantities of nucleoside triphosphate that reach the site of action. In an attempt to circumvent this, we designed novel nucleosides that incorporate a sterically bulky group at the 5'-carbon of the phosphoester prodrug, which we reasoned would reduce the amounts of non-productive PO bond cleavage back to the corresponding nucleoside by nucleotidases. Molecular docking studies with the NS5B HCV polymerase suggested that a nucleotide containing a 5'-methyl group could be accommodated. Therefore, we synthesized mono- and diphosphate prodrugs of 2',5'-C-dimethyluridine stereoselectively and evaluated their cytotoxicity and anti-HCV activity in the HCV replicon assay. All four prodrugs exhibited anti-HCV activity with IC50 values in the single digit micromolar concentrations, with the 5'(R)-C-methyl prodrug displaying superior potency relative to its 5'(S)-C-methyl counterpart. However, when compared to the unmethylated prodrug, the potency is poorer. The poorer potency of these prodrugs may be due to unfavorable steric interactions of the 5'-C-methyl group in the active sites of the kinases that catalyze the formation of active triphosphate metabolite.

Effect of Diquafosol on Hyperosmotic Stress-induced Tumor Necrosis Factor-α and Interleukin-6 Expression in Human Corneal Epithelial Cells.

PURPOSE: Diquafosol is a pharmaceutical drug used for dry eye treatment with a novel mechanism of action. It is a purinergic P2Y2 receptor agonist that promotes the secretion of tears and healing of corneal epithelial wounds. However, its inhibitory effect on hyperosmotic stress-induced inflammation in human corneal epithelial cells (HCECs) remains unclear. METHODS: A hyperosmotic stress model was established by transferring HCECs from isosmotic (312 mOsm/kg to hyperosmotic medium (500 mOsm/kg). HCECs were incubated with 500 mOsm/kg hyperosmotic medium for 30 minutes, and then treated with diquafosol (0.6-6 mg/mL) for 4 or 24 hours. Cells were then harvested and analyzed by western blot, immunocytochemistry, and real-time polymerase chain reaction to evaluate the expression of interleukin-6, tumor necrosis factor-alpha, and the phosphorylation status of nuclear factor-kappa B. RESULTS: Diquafosol significantly decreased the mRNA and protein expression of hyperosmotic stress-induced tumor necrosis factor-alpha and interleukin-6. These results were supported by immunofluorescence staining and quantitative real-time polymerase chain reaction analysis. Furthermore, diquafosol inhibits nuclear factor-kappa B activation by suppressing the phosphorylation and degradation of the inhibitor of кB. CONCLUSIONS: This study shows that diquafosol inhibits nuclear factor-kappa B signaling and inflammatory factors induced by hyperosmotic stress in HCECs. This suggests that using diquafosol for the improvement of dry eye syndrome could be effective in the treatment of inflammation-related corneal and conjunctival diseases.

Effects of Preservative-free 3% Diquafosol in Patients with Pre-existing Dry Eye Disease after Cataract Surgery: A Randomized Clinical Trial.

Dry eye disease (DED) after cataract surgery has become a critical concern, and various therapeutic options have been developed. Recently, preservative-free diquafosol ophthalmic solution has been introduced; however, its therapeutic effect on DED after cataract surgery has not been reported. We investigated the efficacy of preservative-free diquafosol in patients with pre-existing DED after cataract surgery. We divided subjects who were diagnosed with DED and scheduled to undergo cataract surgery, into 3 groups (preservative-free diquafosol, group 1; preservative-containing diquafosol, group 2; preservative-free hyaluronate, group 3), and each eye drops was administered 6 times daily after surgery. Tear break up time (TBUT), Ocular Surface Disease Index (OSDI), corneal staining score, lid margin abnormality, and meibum quality improved over time in group 1. Groups 1 and 2 had significantly superior TBUT, meibomian gland dysfunction grade, and meibomian gland expressibility throughout the study period than group 3. Meibum quality of group 1 was significantly better than group 2 at 1 and 3 months after surgery. Preservative-free diquafosol showed better efficacy in treating DED after cataract surgery than preservative-containing diquafosol or preservative-free hyaluronate. Preservative-free diquafosol may serve as a reliable option for the management of patients with pre-existing DED after phacoemulsification.

Tear film lipid layer increase after diquafosol instillation in dry eye patients with meibomian gland dysfunction: a randomized clinical study.

Diquafosol promotes secretion of tear fluid and mucin at the ocular surface and is administered for treatment of dry eye (DE). Tear film lipid layer is secreted from meibomian glands and stabilizes the tear film. We recently showed that diquafosol administration increased lipid layer thickness (LLT) for up to 60 min in normal human eyes. We here evaluated tear film lipid layer in DE patients (n = 47) with meibomian gland dysfunction (MGD) before as well as 30, 60, and 90 min after diquafosol administration. One drop of artificial tears or one drop of diquafosol was applied randomly to the eyes of each patient. Diquafosol significantly increased LLT at 30 (P < 0.001) and 60 (P = 0.042) min and noninvasive tear film breakup time for at least 90 min (P < 0.001 at each assessment point). Artificial tears had no such effect. Diquafosol significantly improved the tear interferometric pattern compared with artificial tears (P < 0.001 at each assessment point). A single topical administration of diquafosol thus improved LLT and tear film stability in DE patients with MGD, suggesting that diquafosol is a potential treatment not only for aqueous-deficient DE but also for evaporative DE associated with MGD.

Synthesis and Anti-HCV Activities of 4'-Fluoro-2'-Substituted Uridine Triphosphates and Nucleotide Prodrugs: Discovery of 4'-Fluoro-2'- C-methyluridine 5'-Phosphoramidate Prodrug (AL-335) for the Treatment of Hepatitis C Infection.

We report the synthesis and biological evaluation of a series of 4'-fluoro-2'- C-substituted uridines. Triphosphates of the uridine analogues exhibited a potent inhibition of hepatitis C virus (HCV) NS5B polymerase with IC50 values as low as 27 nM. In an HCV subgenomic replicon assay, the phosphoramidate prodrugs of these uridine analogues demonstrated a very potent activity with EC50 values as low as 20 nM. A lead compound AL-335 (53) demonstrated high levels of the nucleoside triphosphate in vitro in primary human hepatocytes and Huh-7 cells as well as in dog liver following a single oral dose. Compound 53 was selected for the clinical development where it showed promising results in phase 1 and 2 trials.

Comparison of Ocular Surface Mucin Expression After Topical Ophthalmic Drug Administration in Dry Eye-Induced Mouse Model.

PURPOSE: To determine the mucinogenic effect of dry eye (DE) treatment drugs currently in use, we compared the levels of mucin production and inflammatory cytokine expression on the ocular surfaces using a DE-induced mice model. METHODS: C57BL/6 mice were separated into 6 groups: a control group, DE-induced mice with the vehicle and treated with cyclosporine A (CsA), rebamipide (Reb), diquafosol tetrasodium (DQS), or prednisolone (Pred). The mRNA expression of MUC 1, 4, 16, 5AC, and proinflammatory cytokines on the corneal epithelia were determined by quantitative real-time polymerase chain reaction. Expression of each MUC was evaluated using flow cytometry and immunohistostaining. Conjunctival goblet cells were analyzed through periodic acid-Schiff (PAS) staining. RESULTS: Desiccating stress significantly decreased both mRNA and protein levels of all MUCs in the cornea. CsA mainly enhanced MUC5AC, with an increase in PAS-positive cells, whereas DQS chiefly increased membrane-associated mucins (MM). However, Reb only minimally increased expression of MUC5AC and Pred only increased MUC4. MUC16 did not show any significant change in any group. On the contrary, the mRNA levels of interleukin (IL)-1ß, -6, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ were increased in the DE corneas of the control mice and were reduced by all treatments; in particular, IL-6 was significantly suppressed. CONCLUSION: Topical DQS and CsA not only ameliorated ocular surface inflammation under desiccating stress but also upregulated both MM and secretory mucins (SM) and contributed to conjunctival goblet cell recovery, compared to Reb and Pred. Both anti-inflammatory and secretory factors should be considered simultaneously when measuring the treatment effect of DE drugs.

Highly Selective and Potent Ectonucleotide Pyrophosphatase-1 (NPP1) Inhibitors Based on Uridine 5'-Pα,α-Dithiophosphate Analogues.

Ectonucleotide pyrophosphatase/phosphodiesterase-1 (NPP1) hydrolyzes phosphodiester bonds of nucleotides such as ATP, resulting mainly in the formation of AMP and pyrophosphate. NPP1 activity plays a deleterious function in calcified aortic valve disease and calcium pyrophosphate deposition disease. Thus, inhibitors of NPP1 represent a medical need. We developed novel NPP1 inhibitors based on uridine 5'-Pα,α-dithiophosphate analogues, 9-12. All these analogues potently inhibited hNPP1 (80-100% inhibition) at 100 µM, with no, or minimal, inhibition of NPP3 and other ectonucleotidases (NTPDase1,2,3,8). These compounds showed nearly no activity at uracil-nucleotide sensitive P2Y2,4,6-receptors and thus represent highly selective NPP1 inhibitors. The most promising inhibitor was diuridine 5'-Pα,α,5″-Pα,α-tetrathiotetraphosphate, 12, exhibiting Ki of 27 nM. Analogues 9-12 proved to be highly stable to air oxidation and to acidic and basic pH. Docking simulations suggested that the enhanced NPP1 inhibitory activity and selectivity of analogue 12 could be attributed to the simultaneous occupancy of two sites (the AMP site and an alternative site) of NPP1 by this compound.

2',3'-Dideoxyuridine triphosphate conjugated to SiO2 nanoparticles: Synthesis and evaluation of antiproliferative activity.

A conjugate of triphosphorylated 2',3'-dideoxyuridine (ddU) with SiO2 nanoparticles was obtained via the CuAAC click chemistry between a γ-alkynyl ddU triphosphate and azido-modified SiO2 nanoparticles. Assessment of cytotoxicity in human breast adenocarcinoma MCF7 cells demonstrated that ddU triphosphate conjugated to SiO2 nanoparticles exhibited a 50% decrease in cancer cell growth at a concentration of 183 ±â€¯57 µg/mL, which corresponds to 22 ±â€¯7 µM of the parent nucleotide, whereas the parent nucleoside, nucleotide and alkynyl triphosphate precursor do not show any cytotoxicity. The data provide an example of remarkable potential of novel conjugates of SiO2 nanoparticles with phosphorylated nucleoside analogues, even those, which have not been used previously as therapeutics, for application as new anticancer agents.

Diquafosol Delivery from Silicone Hydrogel Contact Lenses: Improved Effect on Tear Secretion.

PURPOSE: The aim of this study was to evaluate the ability to uptake and to deliver diquafosol from commercial contact lenses (CLs) and its effect on tear secretion. METHODS: For both in vitro and in vivo experiments, two commercial silicone hydrogel (Si-Hy) CLs (comfilcon A and balafilcon A) were used. The CLs were soaked overnight for 12 h in diquafosol solution and control CLs were soaked in saline solution (NaCl 0.9%). The CLs were introduced into a new well container with 1 mL of saline solution, and aliquots of 100 µL were extracted at different times during a period of 6 h to measure the diquafosol release. For in vivo experiments, nine male New Zealand white rabbits were used. CLs soaked in diquafosol were inserted in the eye and compared with control CLs and diquafosol topical instillation. Schirmer's tests were performed to evaluate tear secretion and diquafosol release at different times during the 6-h period. RESULTS: For in vitro experiments, the largest amount of diquafosol was released during the first 24 h for both CL materials under study, without statistical differences between them (P < 0.05). The topical application showed the maximum release at 1 min after instillation, meanwhile the release from both CL materials was at 30 min of insertion. The effect on tear secretion was higher with CL delivery compared with topical instillation (P < 0.05), being 300 min for both CLs and 90 min for topical application. CONCLUSION: The use of CLs increases the residence time of diquafosol on the ocular surface with a concomitant enhancement in tear secretion during longer periods.

Comparison of the efficacy between topical diquafosol and artificial tears in the treatment of dry eye following cataract surgery: A meta-analysis of randomized controlled trials.

BACKGROUND: The prevalence of dry eye following cataract surgery was reported as high as 55.7%, this acute and iatrogenic disorder urgently required appropriate clinical management. The purpose of this study is to compare the efficacy of diquafosol sodium ophthalmic solution (DQS) and conventional artificial tears (AT) for the treatment of dry eye following cataract surgery. METHODS: The PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from their earliest entries through June 2017 to obtain the studies, which evaluated the efficacy of DQS for patients with dry eye after cataract surgery. The relevant data were analyzed using StataSE 12.0 software. The PRISMA checklist was used as protocol of the meta-analysis and the guideline was followed. The weighted mean difference, relative risk, and their 95% confidence interval were used to assess the strength of the association. RESULTS: The authors identified 21 references of which 4 studies evaluating the efficacy of DQS for patients with dry eye after cataract surgery were included. The dataset consisted of 291 patients of dry eye following cataract surgery (371 postoperative eyes). The pooling result of our study suggested that the DQS could significantly better improve the indices like corneal and conjunctival fluorescein staining scores, tear breakup time, and Schirmer I test than AT (P < .05). Although the scores of symptom questionnaire could not be pooled, the results of each study also proved that DQS could significantly better relieve the symptoms of postoperative dry eye. CONCLUSION: Based on the available evidence, topical DQS has a superior efficacy than AT in the management of dry eye after cataract surgery; however, further researches with larger sample sizes and focus on indicators such as higher-order aberrations, symptom questionnaire scores, and cost-effective ratio are required to reach a firmer conclusion.

The Orphan Receptor GPR17 Is Unresponsive to Uracil Nucleotides and Cysteinyl Leukotrienes.

Pairing orphan G protein­coupled receptors (GPCRs) with their cognate endogenous ligands is expected to have a major impact on our understanding of GPCR biology. It follows that the reproducibility of orphan receptor ligand pairs should be of fundamental importance to guide meaningful investigations into the pharmacology and function of individual receptors. GPR17 is an orphan receptor characterized by some as a dualistic uracil nucleotide/cysteinyl leukotriene receptor and by others as inactive toward these stimuli altogether. Whereas regulation of central nervous system myelination by GPR17 is well established, verification of activity of its putative endogenous ligands has proven elusive so far. Herein we report that uracil nucleotides and cysteinyl leukotrienes do not activate human, mouse, or rat GPR17 in various cellular backgrounds, including primary cells, using eight distinct functional assay platforms based on labelfree pathway-unbiased biosensor technologies, as well as canonical second-messenger or biochemical assays. Appraisal of GPR17 activity can neither be accomplished with co-application of both ligand classes, nor with exogenous transfection of partner receptors (nucleotide P2Y12, cysteinyl-leukotriene CysLT1) to reconstitute the elusive pharmacology. Moreover, our study does not support the inhibition of GPR17 by the marketed antiplatelet drugs cangrelor and ticagrelor, previously suggested to antagonize GPR17. Whereas our data do not disagree with a role of GPR17 per se as an orchestrator of central nervous system functions, they challenge the utility of the proposed (ant)agonists as tools to imply direct contribution of GPR17 in complex biologic settings.

Comparison of Short-Term Effects of Diquafosol and Rebamipide on Mucin 5AC Level on the Rabbit Ocular Surface.

PURPOSE: To investigate the short-term effects of 2 new secretagogue eye drops for dry eye, 3% diquafosol tetrasodium ophthalmic solution (diquafosol) and 2% rebamipide ophthalmic suspension (rebamipide), on the concentration of mucin 5AC (MUC5AC) in rabbit tear fluid and conjunctival goblet cells. METHODS: One dose of artificial tears, diquafosol or rebamipide, was instilled into 8 eyes of Japanese white rabbits. MUC5AC concentration in the tear fluid was examined using the enzyme-linked immunosorbent assay 15 min after instillation and compared with 8 untreated controls. Impression cytology was performed to measure the number of periodic acid Schiff (PAS)-positive cells and the ratio of the PAS-positive area using image analysis software. Statistical comparison was performed using ANOVA with post hoc analysis with the Tukey's test. RESULTS: After 15 min, only diquafosol significantly (P ≤ 0.01) increased the MUC5AC level in the tear fluid. Although no drug affected the number of PAS-positive cells, the ratio of the PAS-positive area decreased significantly (P ≤ 0.01) only in the diquafosol group. CONCLUSIONS: These data indicated that more PAS-positive MUC5AC was released into the tear fluid from the goblet cells by diquafosol than by rebamipide. There is a difference in the induction pattern of MUC5AC into the tears from the goblet cells between these eye drops.