De novo gain-of-function variants in KCNT2 as a novel cause of developmental and epileptic encephalopathy

Variants in several potassium channel genes have been found in developmental and epileptic encephalopathies (DEE). We report on 2 females with de novo variants in KCNT2 with West syndrome followed by Lennox-Gastaut syndrome or with DEE with migrating focal seizures. After in vitro analysis suggested quinidine-responsive gain-of-function effects, we treated 1 of the girls with quinidine add-on therapy and achieved marked clinical improvements. This suggests that the new spectrum of KCNT2-related disorders do not only share similar phenotypic and in vitro functional and pharmacological features with previously known KCNT1-related disorders, but also represents a further example for possible precision medicine approaches. Ann Neurol 2018;83:1198-1204.

Identification of a Potent Tryptophan-Based TRPM8 Antagonist With in Vivo Analgesic Activity

TRPM8 has been implicated in nociception and pain and is currently regarded as an attractive target for the pharmacological treatment of neuropathic pain syndromes. A series of analogues of N, N'-dibenzyl tryptamine 1, a potent TRPM8 antagonist, was prepared and screened using a fluorescence-based in vitro assay based on menthol-evoked calcium influx in TRPM8 stably transfected HEK293 cells. The tryptophan derivative 14 was identified as a potent (IC₅₀ 0.2 ± 0.2 nM) and selective TRPM8 antagonist. In vivo, 14 showed significant target coverage in both an icilin-induced WDS (at 1-30 mg/kg s.c.) and oxaliplatin-induced cold allodynia (at 0.1-1 μg s.c.) mice models. Molecular modeling studies identified the putative binding mode of these antagonists, suggesting that they could influence an interaction network between the S1-4 transmembrane segments and the TRP domains of the channel subunits. The tryptophan moiety provides a new pharmacophoric scaffold for the design of highly potent modulators of TRPM8-mediated pain.

Pharmacological Agents Targeting the Cellular Prion Protein

Prion diseases are associated with the conversion of the cellular prion protein (PrP^C), a glycoprotein expressed at the surface of a wide variety of cell types, into a misfolded conformer (the scrapie form of PrP, or PrP^Sc) that accumulates in brain tissues of affected individuals. PrP^Sc is a self-catalytic protein assembly capable of recruiting native conformers of PrP^C, and causing their rearrangement into new PrP^Sc molecules. Several previous attempts to identify therapeutic agents against prion diseases have targeted PrP^Sc, and a number of compounds have shown potent anti-prion effects in experimental models. Unfortunately, so far, none of these molecules has successfully been translated into effective therapies for prion diseases. Moreover, mounting evidence suggests that PrP^Sc might be a difficult pharmacological target because of its poorly defined structure, heterogeneous composition, and ability to generate different structural conformers (known as prion strains) that can elude pharmacological intervention. In the last decade, a less intuitive strategy to overcome all these problems has emerged: targeting PrP^C, the common substrate of any prion strain replication. This alternative approach possesses several technical and theoretical advantages, including the possibility of providing therapeutic effects also for other neurodegenerative disorders, based on recent observations indicating a role for PrP^C in delivering neurotoxic signals of different misfolded proteins. Here, we provide an overview of compounds claimed to exert anti-prion effects by directly binding to PrP^C, discussing pharmacological properties and therapeutic potentials of each chemical class.

Macrophage-Derived Extracellular Succinate Licenses Neural Stem Cells to Suppress Chronic Neuroinflammation

Neural stem cell (NSC) transplantation can influence immune responses and suppress inflammation in the CNS. Metabolites, such as succinate, modulate the phenotype and function of immune cells, but whether and how NSCs are also activated by such immunometabolites to control immunoreactivity and inflammatory responses is unclear. Here, we show that transplanted somatic and directly induced NSCs ameliorate chronic CNS inflammation by reducing succinate levels in the cerebrospinal fluid, thereby decreasing mononuclear phagocyte (MP) infiltration and secondary CNS damage. Inflammatory MPs release succinate, which activates succinate receptor 1 (SUCNR1)/GPR91 on NSCs, leading them to secrete prostaglandin E2 and scavenge extracellular succinate with consequential anti-inflammatory effects. Thus, our work reveals an unexpected role for the succinate-SUCNR1 axis in somatic and directly induced NSCs, which controls the response of stem cells to inflammatory metabolic signals released by type 1 MPs in the chronically inflamed brain.

Microglia Polarization, Gene-Environment Interactions and Wnt/β-Catenin Signaling: Emerging Roles of Glia-Neuron and Glia-Stem/Neuroprogenitor Crosstalk for Dopaminergic Neurorestoration in Aged Parkinsonian Brain

Neuroinflammatory processes are recognized key contributory factors in Parkinson's disease (PD) physiopathology. While the causes responsible for the progressive loss of midbrain dopaminergic (mDA) neuronal cell bodies in the subtantia nigra pars compacta are poorly understood, aging, genetics, environmental toxicity, and particularly inflammation, represent prominent etiological factors in PD development. Especially, reactive astrocytes, microglial cells, and infiltrating monocyte-derived macrophages play dual beneficial/harmful effects, via a panel of pro- or anti-inflammatory cytokines, chemokines, neurotrophic and neurogenic transcription factors. Notably, with age, microglia may adopt a potent neurotoxic, pro-inflammatory “primed” (M1) phenotype when challenged with inflammatory or neurotoxic stimuli that hamper brain's own restorative potential and inhibit endogenous neurorepair mechanisms. In the last decade we have provided evidence for a major role of microglial crosstalk with astrocytes, mDA neurons and neural stem progenitor cells (NSCs) in the MPTP- (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-) mouse model of PD, and identified Wnt/β-catenin signaling, a pivotal morphogen for mDA neurodevelopment, neuroprotection, and neuroinflammatory modulation, as a critical actor in glia-neuron and glia-NSCs crosstalk. With age however, Wnt signaling and glia-NSC-neuron crosstalk become dysfunctional with harmful consequences for mDA neuron plasticity and repair. These findings are of importance given the deregulation of Wnt signaling in PD and the emerging link between most PD related genes, Wnt signaling and inflammation. Especially, in light of the expanding field of microRNAs and inflammatory PD-related genes as modulators of microglial-proinflammatory status, uncovering the complex molecular circuitry linking PD and neuroinflammation will permit the identification of new druggable targets for the cure of the disease. Here we summarize recent findings unveiling major microglial inflammatory and oxidative stress pathways converging in the regulation of Wnt/β-catenin signaling, and reciprocally, the ability of Wnt signaling pathways to modulate microglial activation in PD. Unraveling the key factors and conditons promoting the switch of the proinflammatory M1 microglia status into a neuroprotective and regenerative M2 phenotype will have important consequences for neuroimmune interactions and neuronal outcome under inflammatory and/or neurodegenerative conditions.

NCp7: targeting a multitask protein for next-generation anti-HIV drug development part 2. Noncovalent inhibitors and nucleic acid binders

Nucleocapsid protein 7 (NCp7) represents a viable target not yet reached by the currently available antiretrovirals. It is a small and highly basic protein, which is essential for multiple stages of the viral replicative cycle, with its structure preserved in all viral strains, including clinical isolates. NCp7 can be inhibited covalently, noncovalently and by shielding the nucleic acid (NA) substrates of its chaperone activity. Although covalent NCp7 inhibitors have already been detailed in the first part of this review series, the focus here is based on noncovalent and NA-binder inhibitors and on the analysis of the NCp7 3D structure to deliver fruitful insights for future drug design strategies.

microRNAs in Parkinson's Disease: From Pathogenesis to Novel Diagnostic and Therapeutic Approaches

Parkinson’s disease (PD) is the most prevalent central nervous system (CNS) movement disorder and the second most common neurodegenerative disease overall. PD is characterized by the progressive loss of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNpc) within the midbrain, accumulation of alpha-synuclein (α-SYN) in Lewy bodies and neurites and excessive neuroinflammation. The neurodegenerative processes typically begin decades before the appearance of clinical symptoms. Therefore, the diagnosis is achievable only when the majority of the relevant DAergic neurons have already died and for that reason available treatments are only palliative at best. The causes and mechanism(s) of this devastating disease are ill-defined but complex interactions between genetic susceptibility and environmental factors are considered major contributors to the etiology of PD. In addition to the role of classical gene mutations in PD, the importance of regulatory elements modulating gene expression has been increasingly recognized. One example is the critical role played by microRNAs (miRNAs) in the development and homeostasis of distinct populations of neurons within the CNS and, in particular, in the context of PD. Recent reports demonstrate how distinct miRNAs are involved in the regulation of PD genes, whereas profiling approaches are unveiling variations in the abundance of certain miRNAs possibly relevant either to the onset or to the progression of the disease. In this review, we provide an overview of the miRNAs recently found to be implicated in PD etiology, with particular focus on their potential relevance as PD biomarkers, as well as their possible use in PD targeted therapy.

NCp7: targeting a multitasking protein for next-generation anti-HIV drug development part 1: covalent inhibitors

The major internal component of the HIV virion core is the nucleocapsid protein 7 (NCp7), a small, highly basic protein that is essential for multiple stages of the viral replicative cycle, and whose structure is preserved in all viral strains, including clinical isolates from therapy-experienced patients. This key protein is recognised as a potential target for an effective next-generation antiretroviral therapy, because it could offer the possibility to develop broad-spectrum agents that are less prone to select for resistant strains. Here, we provide a comprehensive overview of the covalent NCp7 inhibitors that have emerged over the past 25 years of drug discovery campaigns, emphasising, where possible, their structure-activity relationships (SARs) and pharmacophoric features.

A novel community driven software for functional enrichment analysis of extracellular vesicles data

Bioinformatics tools are imperative for the in depth analysis of heterogeneous high-throughput data. Most of the software tools are developed by specific laboratories or groups or companies wherein they are designed to perform the required analysis for the group. However, such software tools may fail to capture “what the community needs in a tool”. Here, we describe a novel community-driven approach to build a comprehensive functional enrichment analysis tool. Using the existing FunRich tool as a template, we invited researchers to request additional features and/or changes. Remarkably, with the enthusiastic participation of the community, we were able to implement 90% of the requested features. FunRich enables plugin for extracellular vesicles wherein users can download and analyse data from Vesiclepedia database. By involving researchers early through community needs software development, we believe that comprehensive analysis tools can be developed in various scientific disciplines.

Pharmacophore-Based Repositioning of Approved Drugs as Novel Staphylococcus aureus NorA Efflux Pump Inhibitors

An intriguing opportunity to address antimicrobial resistance is represented by the inhibition of efflux pumps. Focusing on NorA, the most important efflux pump of Staphylococcus aureus, an efflux pump inhibitors (EPIs) library was used for ligand-based pharmacophore modeling studies. By exploitation of the obtained models, an in silico drug repositioning approach allowed for the identification of novel and potent NorA EPIs.

Tryptamine-Based Derivatives as Transient Receptor Potential Melastatin Type 8 (TRPM8) Channel Modulators

Pharmacological modulation of the transient receptor potential melastatin type 8 (TRPM8) is currently under investigation as a new approach for the treatment of pain and other diseases. In this study, a series of N-substituted tryptamines was prepared to explore the structural requirements determining TRPM8 modulation. Using a fluorescence-based screening assay, we identified two compounds acting as an activator (2-(1H-indol-3-yl)-N-(4-phenoxybenzyl)ethanamine, 21) or an inhibitor (N,N-dibenzyl-2-(1H-indol-3-yl)ethanamine, 12) of calcium influx in HEK293 cells. In patch-clamp recordings, compound 21 displayed a significantly higher potency (EC50 = 40 ± 4 μM) and a similar efficacy when compared to menthol; by contrast, compound 12 produced a concentration-dependent inhibition of menthol-induced TRPM8 currents (IC50 = 367 ± 24 nM). Molecular modeling studies using a homology model of a single rat TRPM8 subunit identified a putative binding site located between the VSD and the TRP box, disclosing differences in the binding modes for the agonist and the antagonist.

Focus on Extracellular Vesicles: Physiological Role and Signalling Properties of Extracellular Membrane Vesicles

Extracellular vesicles (EVs) are a heterogeneous population of secreted membrane vesicles, with distinct biogenesis routes, biophysical properties and different functions both in physiological conditions and in disease. The release of EVs is a widespread biological process, which is conserved across species. In recent years, numerous studies have demonstrated that several bioactive molecules are trafficked with(in) EVs, such as microRNAs, mRNAs, proteins and lipids. The understanding of their final impact on the biology of specific target cells remains matter of intense debate in the field. Also, EVs have attracted great interest as potential novel cell-free therapeutics. Here we describe the proposed physiological and pathological functions of EVs, with a particular focus on their molecular content. Also, we discuss the advances in the knowledge of the mechanisms regulating the secretion of EV-associated molecules and the specific pathways activated upon interaction with the target cell, highlighting the role of EVs in the context of the immune system and as mediators of the intercellular signalling in the brain.

Design and Synthesis of DiselenoBisBenzamides (DISeBAs) as Nucleocapsid Protein 7 (NCp7) Inhibitors with anti-HIV Activity

The interest in the synthesis of Se-containing compounds is growing with the discovery of derivatives exhibiting various biological activities. In this manuscript, we have identified a series of 2,2'-diselenobisbenzamides (DISeBAs) as novel HIV retroviral nucleocapsid protein 7 (NCp7) inhibitors. Because of its pleiotropic functions in the whole viral life cycle and its mutation intolerant nature, NCp7 represents a target of great interest which is not reached by any anti-HIV agent in clinical use. Using the diselenobisbenzoic scaffold, amino acid, and benzenesulfonamide derivatives were prepared and biologically profiled against different models of HIV infection. The incorporation of amino acids such as glycine and glutamate into DISeBAs 7 and 8 resulted in selective anti-HIV activity against both acutely and chronically infected cells as well as an interesting virucidal effect. DISeBAs demonstrated broad antiretroviral activity, encompassing HIV-1 drug-resistant strains including clinical isolates, as well as simian immunodeficiency virus (SIV). Time of addition experiments, along with the observed dose dependent inhibition of the Gag precursor proper processing, confirmed that their mechanism of action is based on NCp7 inhibition.

Acellular approaches for regenerative medicine: on the verge of clinical trials with extracellular membrane vesicles?

Extracellular vesicles (EVs) are a heterogeneous population of naturally occurring secreted small vesicles, with distinct biophysical properties and different functions both in physiology and under pathological conditions. In recent years, a number of studies have demonstrated that EVs might hold remarkable potential in regenerative medicine by acting as therapeutically promising nanodrugs. Understanding their final impact on the biology of specific target cells as well as clarification of their overall therapeutic impact remains a matter of intense debate. Here we review the key principles of EVs in physiological and pathological conditions with a specific highlight on the most recently described mechanisms regulating some of the EV-mediated effects. First, we describe the current debates and the upcoming research on EVs as potential novel therapeutics in regenerative medicine, either as unmodified agents or as functionalized small carriers for targeted drug delivery. Moreover, we address a number of safety aspects and regulatory limitations related to the novel nature of EV-mediated therapeutic applications. Despite the emerging possibilities of EV treatments, these issues need to be overcome in order to allow their safe and successful application in future explorative clinical studies.

p38α MAPK and Type I Inhibitors: Binding Site Analysis and Use of Target Ensembles in Virtual Screening

Mitogen-activated protein kinase p38α plays an essential role in the regulation of pro-inflammatory signaling, and selective blockade of this kinase could be efficacious in many pathological processes. Despite considerable research efforts focused on the discovery and development of p38α MAPK inhibitors, no drug targeting this protein has been approved for clinical use so far. We herein analyze the available crystal structures of p38α MAPK in complex with ATP competitive type I inhibitors, getting insights into ATP binding site conformation and its influence on automated molecular docking results. The use of target ensembles, rather than single conformations, resulted in a performance improvement in both the ability to reproduce experimental bound conformations and the capability of mining active molecules from compound libraries. The information gathered from this study can be exploited in structure-based drug discovery programs having as the ultimate aim the identification of novel p38α MAPK type I inhibitors.

A Comprehensive Structural Overview of p38α MAPK in Complex with Type I Inhibitors

p38α mitogen-activated protein kinase (MAPK) is a well-recognized therapeutic target for the treatment of autoimmune and inflammatory diseases. Over the past two decades, tremendous efforts have been focused on the discovery and development of small-molecule p38α MAPK inhibitors, although currently no drugs targeting this protein are clinically available. Therefore, the identification of novel chemotypes that are able to inhibit p38α MAPK function is still of great therapeutic significance. With the objective to support drug discovery programs aimed at identifying new immunomodulators acting on p38α MAPK, herein we present a complete overview of the available crystal structures of this protein in complex with ATP-site type I inhibitors. The 85 available complexes are classified by chemotype and experimental binding mode, and the ligand-protein interactions are discussed using the most representative inhibitors. The type and frequency of key inhibitor features are analyzed to give a final summary of the chemical requirements of promising p38α MAPK inhibitors. The proposed pharmacophore can be exploited to enhance the opportunities to identify novel type I inhibitors of p38α MAPK.

Extracellular vesicles and their synthetic analogues in aging and age-associated brain diseases

Multicellular organisms rely upon diverse and complex intercellular communications networks for a myriad of physiological processes. Disruption of these processes is implicated in the onset and propagation of disease and disorder, including the mechanisms of senescence at both cellular and organismal levels. In recent years, secreted extracellular vesicles (EVs) have been identified as a particularly novel vector by which cell-to-cell communications are enacted. EVs actively and specifically traffic bioactive proteins, nucleic acids, and metabolites between cells at local and systemic levels, modulating cellular responses in a bidirectional manner under both homeostatic and pathological conditions. EVs are being implicated not only in the generic aging process, but also as vehicles of pathology in a number of age-related diseases, including cancer and neurodegenerative and disease. Thus, circulating EVs-or specific EV cargoes-are being utilised as putative biomarkers of disease. On the other hand, EVs, as targeted intercellular shuttles of multipotent bioactive payloads, have demonstrated promising therapeutic properties, which can potentially be modulated and enhanced through cellular engineering. Furthermore, there is considerable interest in employing nanomedicinal approaches to mimic the putative therapeutic properties of EVs by employing synthetic analogues for targeted drug delivery. Herein we describe what is known about the origin and nature of EVs and subsequently review their putative roles in biology and medicine (including the use of synthetic EV analogues), with a particular focus on their role in aging and age-related brain diseases.

Metabolic reprograming of mononuclear phagocytes in progressive multiple sclerosis

Multiple sclerosis (MS) is an inflammatory and demyelinating disease of the central nervous system (CNS). Accumulation of brain damage in progressive MS is partly the result of mononuclear phagocytes (MPs) attacking myelin sheaths in the CNS. Although there is no cure yet for MS, significant advances have been made in the development of disease modifying agents. Unfortunately, most of these drugs fail to reverse established neurological deficits and can have adverse effects. Recent evidence suggests that MPs polarization is accompanied by profound metabolic changes, whereby pro-inflammatory MPs (M1) switch toward glycolysis, whereas anti-inflammatory MPs (M2) become more oxidative. It is therefore possible that reprograming MPs metabolism could affect their function and repress immune cell activation. This mini review describes the metabolic changes underpinning macrophages polarization and anticipates how metabolic re-education of MPs could be used for the treatment of MS.

KEY POINTS

Inflammation in progressive MS is mediated primarily by MPs.Cell metabolism regulates the function of MPs.DMAs can re-educate the metabolism of MPs to promote healing.

Extracellular vesicles from neural stem cells transfer IFN-γ via Ifngr1 to activate Stat1 signaling in target cells

The idea that stem cell therapies work only via cell replacement is challenged by the observation of consistent intercellular molecule exchange between the graft and the host. Here we defined a mechanism of cellular signaling by which neural stem/precursor cells (NPCs) communicate with the microenvironment via extracellular vesicles (EVs), and we elucidated its molecular signature and function. We observed cytokine-regulated pathways that sort proteins and mRNAs into EVs. We described induction of interferon gamma (IFN-γ) pathway in NPCs exposed to proinflammatory cytokines that is mirrored in EVs. We showed that IFN-γ bound to EVs through Ifngr1 activates Stat1 in target cells. Finally, we demonstrated that endogenous Stat1 and Ifngr1 in target cells are indispensable to sustain the activation of Stat1 signaling by EV-associated IFN-γ/Ifngr1 complexes. Our study identifies a mechanism of cellular signaling regulated by EV-associated IFN-γ/Ifngr1 complexes, which grafted stem cells may use to communicate with the host immune system.