Study of nycthemeral variations in blood pressure in patients with non-arteritic anterior ischemic optic neuropathy.

PURPOSE: The objective of this study was to analyze the nycthemeral variations in blood pressure (BP) in individuals who presented with non-arteritic anterior ischemic optic neuropathy (NAION). METHODS: BP was recorded for 24 h (ambulatory blood pressure monitoring, ABPM) in 65 patients with acute NAION. Three definitions of nighttime periods were used: definition 1, 1 a.m.-6 a.m.; definition 2, 10 p.m.-7 a.m.; and definition 3, 10 p.m.-8 a.m. For each of these definitions, patients were classified according to the value of nocturnal reduction in BP into dippers (10-20%), mild dippers (0-10%), reverse dippers (< 0%), and extreme dippers (> 20%). RESULTS: The proportions of dippers, mild dippers, reverse dippers, and extreme dippers varied significantly depending on the definition chosen. We found the highest number of patients with extreme dipping (23%) when using the strictest definition of nighttime period (definition 1, 1 a.m.-6 a.m.), as compared with 6.2% and 1.5% for the other definitions, respectively. Overall, 13 of 33 patients without known systemic hypertension (39%) were diagnosed with hypertension after ABPM. No risk factor for NAION was associated with the extreme-dipping profile. Finally, the prevalence of systemic hypertension was high (69%). CONCLUSION: In our population of patients who had an episode of NAION, the proportion of extreme dippers was higher than that usually found in the literature. However, extreme dipping is not a frequent feature of patients with NAION as compared to patients with systemic hypertension. ABPM is recommended for all patients with NAION and unknown history of systemic hypertension.

Biochemical and Structural Characterization of a Peptidic Inhibitor of the YAP:TEAD Interaction That Binds to the α-Helix Pocket on TEAD.

The TEAD transcription factors are the most distal elements of the Hippo pathway, and their transcriptional activity is regulated by several proteins, including YAP. In some cancers, the Hippo pathway is deregulated and inhibitors of the YAP:TEAD interaction are foreseen as new anticancer drugs. The binding of YAP to TEAD is driven by the interaction of an α-helix and an Ω-loop present in its TEAD-binding domain with two distinct pockets at the TEAD surface. Using the mRNA-based display technique to screen a library of in vitro-translated cyclic peptides, we identified a peptide that binds with a nanomolar affinity to TEAD. The X-ray structure of this peptide in complex with TEAD reveals that it interacts with the α-helix pocket. Under our experimental conditions, this peptide can form a ternary complex with TEAD and YAP. Furthermore, combining it with a peptide binding to the Ω-loop pocket gives an additive inhibitory effect on the YAP:TEAD interaction. Overall, our results show that it is possible to identify nanomolar inhibitors of the YAP:TEAD interaction that bind to the α-helix pocket, suggesting that developing such compounds might be a strategy to treat cancers where the Hippo pathway is deregulated.

N-terminal ß-strand in YAP is critical for stronger binding to scalloped relative to TEAD transcription factor.

The yes-associated protein (YAP) regulates the transcriptional activity of the TEAD transcription factors that are key in the control of organ morphogenesis. YAP interacts with TEAD via three secondary structure elements: a ß-strand, an α-helix, and an Ω-loop. Earlier results have shown that the ß-strand has only a marginal contribution in the YAP:TEAD interaction, but we show here that it significantly enhances the affinity of YAP for the Drosophila homolog of TEAD, scalloped (Sd). Nuclear magnetic resonance shows that the ß-strand adopts a more rigid conformation once bound to Sd; pre-steady state kinetic measurements show that the YAP:Sd complex is more stable. Although the crystal structures of the YAP:TEAD and YAP:Sd complexes reveal no differences at the binding interface that could explain these results. Molecular Dynamics simulations are in line with our experimental findings regarding ß-strand stability and overall binding affinity of YAP to TEAD and Sd. In particular, RMSF, correlated motion and MMGBSA analyses suggest that ß-sheet fluctuations play a relevant role in YAP53-57 ß-strand dissociation from TEAD4 and contribute to the lower affinity of YAP for TEAD4. Identifying a clear mechanism leading to the difference in YAP's ß-strand stability proved to be challenging, pointing to the potential relevance of multiple modest structural changes or fluctuations for regulation of binding affinity.

A new perspective on the interaction between the Vg/VGLL1-3 proteins and the TEAD transcription factors.

The most downstream elements of the Hippo pathway, the TEAD transcription factors, are regulated by several cofactors, such as Vg/VGLL1-3. Earlier findings on human VGLL1 and here on human VGLL3 show that these proteins interact with TEAD via a conserved amino acid motif called the TONDU domain. Surprisingly, our studies reveal that the TEAD-binding domain of Drosophila Vg and of human VGLL2 is more complex and contains an additional structural element, an Ω-loop, that contributes to TEAD binding. To explain this unexpected structural difference between proteins from the same family, we propose that, after the genome-wide duplications at the origin of vertebrates, the Ω-loop present in an ancestral VGLL gene has been lost in some VGLL variants. These findings illustrate how structural and functional constraints can guide the evolution of transcriptional cofactors to preserve their ability to compete with other cofactors for binding to transcription factors.

Discovery and Optimization of Novel SUCNR1 Inhibitors: Design of Zwitterionic Derivatives with a Salt Bridge for the Improvement of Oral Exposure.

G-protein-coupled receptor SUCNR1 (succinate receptor 1 or GPR91) senses the citric cycle intermediate succinate and is implicated in various pathological conditions such as rheumatoid arthritis, liver fibrosis, or obesity. Here, we describe a novel SUCNR1 antagonist scaffold discovered by high-throughput screening. The poor permeation and absorption properties of the most potent compounds, which were zwitterionic in nature, could be improved by the formation of an internal salt bridge, which helped in shielding the two opposite charges and thus also the high polarity of zwitterions with separated charges. The designed compounds containing such a salt bridge reached high oral bioavailability and oral exposure. We believe that this principle could find a broad interest in the medicinal chemistry field as it can be useful not only for the modulation of properties in zwitterionic compounds but also in acidic or basic compounds with poor permeation.

Structure-Guided Design of Substituted Biphenyl Butanoic Acid Derivatives as Neprilysin Inhibitors.

Inhibition of neprilysin (NEP) is widely studied as a therapeutic target for the treatment of hypertension, heart failure, and kidney disease. Sacubitril/valsartan (LCZ696) is a drug approved to reduce the risk of cardiovascular death in heart failure patients with reduced ejection fraction. LBQ657 is the active metabolite of sacubitril and an inhibitor of NEP. Previously, we have reported the crystal structure of NEP bound with LBQ657, whereby we noted the presence of a subsite in S1' that has not been explored before. We were also intrigued by the zinc coordination made by one of the carboxylic acids of LBQ657, leading us to explore alternative linkers to efficiently engage zinc for NEP inhibition. Structure-guided design culminated in the synthesis of selective, orally bioavailable, and subnanomolar inhibitors of NEP. A 17-fold boost in biochemical potency was observed upon addition of a chlorine atom that occupied the newly found subsite in S1'. We report herein the discovery and preclinical profiling of compound 13, which paved the path to our clinical candidate.

Gabapentin and Memantine for Treatment of Acquired Pendular Nystagmus: Effects on Visual Outcomes.

BACKGROUND: The most common causes of acquired pendular nystagmus (APN) are multiple sclerosis (MS) and oculopalatal tremor (OPT), both of which result in poor visual quality of life. The objective of our study was to evaluate the effects of memantine and gabapentin treatments on visual function. We also sought to correlate visual outcomes with ocular motor measures and to describe the side effects of our treatments. METHODS: This study was single-center cross-over trial. A total of 16 patients with chronic pendular nystagmus, 10 with MS and 6 with OPT were enrolled. Visual acuity (in logarithm of the minimum angle of resolution [LogMAR]), oscillopsia amplitude and direction, eye movement recordings, and visual function questionnaires (25-Item National Eye Institute Visual Functioning Questionnaire [NEI-VFQ-25]) were performed before and during the treatments (gabapentin: 300 mg 4 times a day and memantine: 10 mg 4 times a day). RESULTS: A total of 29 eyes with nystagmus were evaluated. Median near monocular visual acuity improved in both treatment arms, by 0.18 LogMAR on memantine and 0.12 LogMAR on gabapentin. Distance oscillopsia improved on memantine and on gabapentin. Median near oscillopsia did not significantly change on memantine or gabapentin. Significant improvement in ocular motor parameters was observed on both treatments. Because of side effects, 18.8% of patients discontinued memantine treatment-one of them for a serious adverse event. Only 6.7% of patients discontinued gabapentin. Baseline near oscillopsia was greater among those with higher nystagmus amplitude and velocity. CONCLUSIONS: This study demonstrated that both memantine and gabapentin reduce APN, improving functional visual outcomes. Gabapentin showed a better tolerability, suggesting that this agent should be used as a first-line agent for APN. Data from our investigation emphasize the importance of visual functional outcome evaluations in clinical trials for APN.

Identification of FAM181A and FAM181B as new interactors with the TEAD transcription factors.

The Hippo pathway is a key signaling pathway in the control of organ size and development. The most distal elements of this pathway, the TEAD transcription factors, are regulated by several proteins, such as YAP (Yes-associated protein), TAZ (transcriptional co-activator with PDZ-binding motif) and VGLL1-4 (Vestigial-like members 1-4). In this article, combining structural data and motif searches in protein databases, we identify two new TEAD interactors: FAM181A and FAM181B. Our structural data show that they bind to TEAD via an Ω-loop as YAP/TAZ do, but only FAM181B possesses the LxxLF motif (x any amino acid) found in YAP/TAZ. The affinity of different FAM181A/B fragments for TEAD is in the low micromolar range and full-length FAM181A/B proteins interact with TEAD in cells. These findings, together with a recent report showing that FAM181A/B proteins have a role in nervous system development, suggest a potential new involvement of the TEAD transcription factors in the development of this tissue.

Retinal Vessel Phenotype in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy.

PURPOSE: The pathophysiology of nonarteritic anterior ischemic optic neuropathy (NAION) is not completely understood. Studies of the retinal vasculature phenotype in patients with NAION could help us to understand vascular abnormalities associated with the disease. DESIGN: Retrospective case series with matched control subjects. METHODS: Study population: 57 patients with NAION and 57 control subjects matched to NAION patients for sex, age, systemic hypertension, diabetes, and obstructive sleep apnea syndrome between September 2007 and July 2017. MAIN OUTCOME MEASURES: All patients and control subjects underwent a complete ocular examination and 45° funduscopic color photographs. The widths of the 6 largest arteries in zone B (between 0.5 and 1 optic disc diameter from the optic disc), summarized by the central retinal artery equivalent (CRAE), the widths of the 6 largest veins in zone B, summarized by the central retinal vein equivalent (CRVE), the arteriole to venule ratio, tortuosity, and fractal dimension were measured on the 2 groups using Vessel Assessment and Measurement Platform for Images of the Retina, a software tool for efficient semiautomatic quantification of the retinal vasculature morphology in fundus camera images. The Wilcoxon signed-rank test and MacNemar χ2 test for paired sample and generalized estimating equations for modeling the Vessel Assessment and Measurement Platform for Images of the Retina parameters as dependent variables were used. RESULTS: CRVE and fractal dimension (D0a) were significantly higher in the NAION group when compared with the control group, whereas the arteriole to venule ratio and vascular tortuosity were significantly lower. Compared with control subjects, acute NAION yielded an increased CRAE value (174 ± 33 vs 160 ± 13 µm) while resolution NAION yielded a decreased CRAE value (152 ± 12 vs 156 ± 33 µm). Acute NAION yielded an increased CRVE value (244 ± 35 vs 210 ± 21 µm) while resolution NAION yielded an unchanged CRVE value. We found no difference between groups for age, refraction, optic disc diameter, CRAE, or fractal dimension. CONCLUSIONS: Retinal vascular parameters were different in our sample between NAION and control patients, especially at the acute stage of the disease. Our results suggest a normalization of the same parameters at the resolution stage.

An allosteric MALT1 inhibitor is a molecular corrector rescuing function in an immunodeficient patient.

MALT1 paracaspase is central for lymphocyte antigen-dependent responses including NF-κB activation. We discovered nanomolar, selective allosteric inhibitors of MALT1 that bind by displacing the side chain of Trp580, locking the protease in an inactive conformation. Interestingly, we had previously identified a patient homozygous for a MALT1 Trp580-to-serine mutation who suffered from combined immunodeficiency. We show that the loss of tryptophan weakened interactions between the paracaspase and C-terminal immunoglobulin MALT1 domains resulting in protein instability, reduced protein levels and functions. Upon binding of allosteric inhibitors of increasing potency, we found proportionate increased stabilization of MALT1-W580S to reach that of wild-type MALT1. With restored levels of stable MALT1 protein, the most potent of the allosteric inhibitors rescued NF-κB and JNK signaling in patient lymphocytes. Following compound washout, MALT1 substrate cleavage was partly recovered. Thus, a molecular corrector rescues an enzyme deficiency by substituting for the mutated residue, inspiring new potential precision therapies to increase mutant enzyme activity in other deficiencies.

MAA868, a novel FXI antibody with a unique binding mode, shows durable effects on markers of anticoagulation in humans.

A large unmet medical need exists for safer antithrombotic drugs because all currently approved anticoagulant agents interfere with hemostasis, leading to an increased risk of bleeding. Genetic and pharmacologic evidence in humans and animals suggests that reducing factor XI (FXI) levels has the potential to effectively prevent and treat thrombosis with a minimal risk of bleeding. We generated a fully human antibody (MAA868) that binds the catalytic domain of both FXI (zymogen) and activated FXI. Our structural studies show that MAA868 traps FXI and activated FXI in an inactive, zymogen-like conformation, explaining its equally high binding affinity for both forms of the enzyme. This binding mode allows the enzyme to be neutralized before entering the coagulation process, revealing a particularly attractive anticoagulant profile of the antibody. MAA868 exhibited favorable anticoagulant activity in mice with a dose-dependent protection from carotid occlusion in a ferric chloride-induced thrombosis model. MAA868 also caused robust and sustained anticoagulant activity in cynomolgus monkeys as assessed by activated partial thromboplastin time without any evidence of bleeding. Based on these preclinical findings, we conducted a first-in-human study in healthy subjects and showed that single subcutaneous doses of MAA868 were safe and well tolerated. MAA868 resulted in dose- and time-dependent robust and sustained prolongation of activated partial thromboplastin time and FXI suppression for up to 4 weeks or longer, supporting further clinical investigation as a potential once-monthly subcutaneous anticoagulant therapy.

Structure-based design and synthesis of macrocyclic human rhinovirus 3C protease inhibitors.

The design and synthesis of macrocyclic inhibitors of human rhinovirus 3C protease is described. A macrocyclic linkage of the P1 and P3 residues, and the subsequent structure-based optimization of the macrocycle conformation and size led to the identification of a potent biochemical inhibitor 10 with sub-micromolar antiviral activity.

Structure of neprilysin in complex with the active metabolite of sacubitril.

Sacubitril is an ethyl ester prodrug of LBQ657, the active neprilysin (NEP) inhibitor, and a component of LCZ696 (sacubitril/valsartan). We report herein the three-dimensional structure of LBQ657 in complex with human NEP at 2 Å resolution. The crystal structure unravels the binding mode of the compound occupying the S1, S1' and S2' sub-pockets of the active site, consistent with a competitive inhibition mode. An induced fit conformational change upon binding of the P1'-biphenyl moiety of the inhibitor suggests an explanation for its selectivity against structurally homologous zinc metallopeptidases.

Hyperglycemia Interacts with Ischemia in a Synergistic Way on Wound Repair and Myofibroblast Differentiation.

BACKGROUND: Hyperglycemia is known to adversely affect the outcome of ischemic insults, but its interaction with ischemia has not been investigated in wound repair yet. In this study, we develop a new animal model allowing to investigate the interaction between hyperglycemia and ischemia during the wound repair process. We focus on myofibroblast differentiation, a key element of wound repair. METHODS: Ischemia was inflicted in Wistar rats by resection of the femoral to popliteal arteries on the left side, whereas arteries were dissected without resection on the right side. Full-thickness skin wounds (1 cm(2)) were created on both feet. Hyperglycemia was induced by injection of streptozotocin. Normoglycemic animals served as control (n = 23/group). Blood flow, wound closure, and myofibroblast expression were measured. RESULTS: Wound closure was significantly delayed in ischemic compared with nonischemic wounds in all rats. This delay was almost 5-fold exacerbated in hyperglycemic rats compared with normoglycemic rats, while hyperglycemia alone showed only a slight effect on wound repair. Delayed wound repair was associated with impaired wound contraction and myofibroblast differentiation. CONCLUSIONS: Our model allows to specifically quantify the effect of hyperglycemia and ischemia alone or in combination on wound repair. We show that hyperglycemia amplifies the inhibitory effect of ischemia on wound repair and myofibroblast expression. Our data reveal for the first time the synergic aspect of this interaction and therefore stress the importance of a strict glycemic control in the management of ischemic wounds.

Structure-function relationships with spectral-domain optical coherence tomography retinal nerve fiber layer and optic nerve head measurements.

PURPOSE: To evaluate the regional structure-function relationship between visual field sensitivity and retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) measurements using spectral-domain optical coherence tomography (SD-OCT). METHODS: Prospective cross-sectional study conducted on patients with glaucoma, suspected glaucoma, and healthy subjects. Eyes were tested on Cirrus OCT and standard achromatic perimetry. RNFL thickness of 12 peripapillary 30° sectors, neuroretinal rim thickness extracted from 36 neuroretinal rim scans, and Bruch membrane opening minimum rim width (BMO-MRW)-a recently defined parameter-extracted from 36 neuroretinal rim scans were obtained. Correlations between peripapillary RNFL thickness, neuroretinal rim thickness, all six sectors of BMO-MRW, and visual field sensitivity in the six corresponding areas were evaluated using logarithmic regression analysis. Receiver operating curve areas were calculated for each RNFL, ONH, and macular ganglion cell analysis parameter. RESULTS: We included 142 eyes of 142 subjects. The correlations (r(2)) between RNFL thickness, Cirrus-based neuroretinal rim thickness, BMO-MRW and visual field sensitivity ranged from 0.07 to 0.60, 0.15 to 0.49, and 0.24 to 0.66, respectively. The structure-function correlations were stronger with BMO-MRW than with Cirrus-based neuroretinal rim thickness. The largest areas under the receiver operating curve were seen for rim area (0.926 [95% confidence interval 0.875, 0.977]; P < 0.001) in eyes with glaucoma and for average RNFL (0.863 [0.769, 0.957]; P < 0.01) in eyes with suspected glaucoma. CONCLUSIONS: The structure-function relationship was significantly stronger with BMO-MRW than other ONH SD-OCT parameters. The best diagnostic capabilities were seen with rim area and average RNFL.

Structural determinants of MALT1 protease activity.

The formation of the CBM (CARD11-BCL10-MALT1) complex is pivotal for antigen-receptor-mediated activation of the transcription factor NF-κB. Signaling is dependent on MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1), which not only acts as a scaffolding protein but also possesses proteolytic activity mediated by its caspase-like domain. It remained unclear how the CBM activates MALT1. Here, we provide biochemical and structural evidence that MALT1 activation is dependent on its dimerization and show that mutations at the dimer interface abrogate activity in cells. The unliganded protease presents itself in a dimeric yet inactive state and undergoes substantial conformational changes upon substrate binding. These structural changes also affect the conformation of the C-terminal Ig-like domain, a domain that is required for MALT1 activity. Binding to the active site is coupled to a relative movement of caspase and Ig-like domains. MALT1 binding partners thus may have the potential of tuning MALT1 protease activity without binding directly to the caspase domain.

A macrocyclic HCV NS3/4A protease inhibitor interacts with protease and helicase residues in the complex with its full-length target.

Hepatitis C virus (HCV) infection is a global health burden with over 170 million people infected worldwide. In a significant portion of patients chronic hepatitis C infection leads to serious liver diseases, including fibrosis, cirrhosis, and hepatocellular carcinoma. The HCV NS3 protein is essential for viral polyprotein processing and RNA replication and hence viral replication. It is composed of an N-terminal serine protease domain and a C-terminal helicase/NTPase domain. For full activity, the protease requires the NS4A protein as a cofactor. HCV NS3/4A protease is a prime target for developing direct-acting antiviral agents. First-generation NS3/4A protease inhibitors have recently been introduced into clinical practice, markedly changing HCV treatment options. To date, crystal structures of HCV NS3/4A protease inhibitors have only been reported in complex with the protease domain alone. Here, we present a unique structure of an inhibitor bound to the full-length, bifunctional protease-helicase NS3/4A and show that parts of the P4 capping and P2 moieties of the inhibitor interact with both protease and helicase residues. The structure sheds light on inhibitor binding to the more physiologically relevant form of the enzyme and supports exploring inhibitor-helicase interactions in the design of the next generation of HCV NS3/4A protease inhibitors. In addition, small angle X-ray scattering confirmed the observed protease-helicase domain assembly in solution.