RESUMEN
Toxicodendron dermatitis is an underappreciated disease seen in the emergency department. Although self-limiting, symptoms can be distressing and can last for weeks if untreated, particularly with re-exposure. Continuing research has improved our understanding of specific inflammatory markers that are associated with exposure to urushiol-the compound responsible for Toxicodendron dermatitis-although consensus for treatment remains varied and poorly supported. Owing to the lack of recent primary literature on the topic, many providers rely on historical precedent, expert opinion, and personal experience when treating this disease. This article provides a narrative review of the literature currently available on the effects of urushiol on key molecular and cellular functions and the prevention and treatment of Toxicodendron dermatitis.
Asunto(s)
Dermatitis por Toxicodendron , Toxicodendron , Dermatitis por Toxicodendron/prevención & control , Catecoles , Servicio de Urgencia en HospitalRESUMEN
Screening of 100 acylsulfonamides from the Bristol-Myers Squibb compound collection identified the C3-cyclohexyl indole 6 as a potent Nav1.7 inhibitor. Replacement of the C2 furanyl ring of 6 with a heteroaryl moiety or truncation of this group led to the identification of 4 analogs with hNav1.7 IC50 values under 50â¯nM. Fluorine substitution of the truncated compound 12 led to 34 with improved potency and isoform selectivity. The inverted indole 36 also maintained good activity. Both 34 and 36 exhibited favorable CYP inhibition profiles, good membrane permeability and a low efflux ratio and, therefore, represent new leads in the search for potent and selective Nav1.7 inhibitors to treat pain.
Asunto(s)
Descubrimiento de Drogas , Indoles/química , Canal de Sodio Activado por Voltaje NAV1.7/efectos de los fármacos , Sulfonamidas/farmacología , Humanos , Concentración 50 Inhibidora , Relación Estructura-Actividad , Sulfonamidas/químicaRESUMEN
Replacement of the piperidine ring in the lead benzenesulfonamide Nav1.7 inhibitor 1 with a weakly basic morpholine core resulted in a significant reduction in Nav1.7 inhibitory activity, but the activity was restored by shortening the linkage from methyleneoxy to oxygen. These efforts led to a series of morpholine-based aryl sulfonamides as isoform-selective Nav1.7 inhibitors. This report describes the synthesis and SAR of these analogs.
Asunto(s)
Morfolinas/farmacología , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Sulfonamidas/farmacología , Bloqueadores del Canal de Sodio Activado por Voltaje/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Estructura Molecular , Morfolinas/química , Relación Estructura-Actividad , Sulfonamidas/síntesis química , Sulfonamidas/química , Bloqueadores del Canal de Sodio Activado por Voltaje/síntesis química , Bloqueadores del Canal de Sodio Activado por Voltaje/químicaRESUMEN
The NaV1.7 voltage-gated sodium channel is implicated in human pain perception by genetics. Rare gain of function mutations in NaV1.7 lead to spontaneous pain in humans whereas loss of function mutations results in congenital insensitivity to pain. Hence, agents that specifically modulate the function of NaV1.7 have the potential to yield novel therapeutics to treat pain. The complexity of the channel and the challenges to generate recombinant cell lines with high NaV1.7 expression have led to a surrogate target strategy approach employing chimeras with the bacterial channel NaVAb. In this report we describe the design, synthesis, purification, and characterization of a chimera containing part of the voltage sensor domain 2 (VSD2) of NaV1.7. Importantly, this chimera, DII S1-S4, forms functional sodium channels and is potently inhibited by the NaV1.7 VSD2 targeted peptide toxin ProTx-II. Further, we show by [125I]ProTx-II binding and surface plasmon resonance that the purified DII S1-S4 protein retains high affinity ProTx-II binding in detergent. We employed the purified DII S1-S4 protein to create a scintillation proximity assay suitable for high-throughput screening. The creation of a NaV1.7-NaVAb chimera with the VSD2 toxin binding site provides an important tool for the identification of novel NaV1.7 inhibitors and for structural studies to understand the toxin-channel interaction.
Asunto(s)
Proteínas Bacterianas/química , Canal de Sodio Activado por Voltaje NAV1.7/fisiología , Proteínas Recombinantes de Fusión/química , Venenos de Araña/metabolismo , Canales de Sodio Activados por Voltaje/química , Proteínas Bacterianas/fisiología , Sitios de Unión , Células HEK293 , Humanos , Resonancia por Plasmón de Superficie , Canales de Sodio Activados por Voltaje/fisiologíaRESUMEN
Since zwitterionic benzenesulfonamide Nav1.7 inhibitors suffer from poor membrane permeability, we sought to eliminate this characteristic by replacing the basic moiety with non-basic bicyclic acetals and monocyclic ethers. These efforts led to the discovery of the non-zwitterionic aryl sulfonamide 49 as a selective Nav1.7 inhibitor with improved membrane permeability. Despite its moderate cellular activity, 49 exhibited robust efficacy in mouse models of neuropathic and inflammatory pain and modulated translational electromyogram measures associated with activation of nociceptive neurons.
Asunto(s)
Descubrimiento de Drogas , Modelos Biológicos , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Neuronas/efectos de los fármacos , Nocicepción/efectos de los fármacos , Sulfonamidas/farmacología , Administración Oral , Animales , Dolor Crónico/inducido químicamente , Dolor Crónico/tratamiento farmacológico , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Adyuvante de Freund , Células HEK293 , Humanos , Inflamación/inducido químicamente , Inflamación/tratamiento farmacológico , Masculino , Ratones , Estructura Molecular , Neuronas/metabolismo , Relación Estructura-Actividad , Sulfonamidas/administración & dosificación , Sulfonamidas/químicaRESUMEN
In vitro phenotypic assays of sensory neuron activity are important tools for identifying potential analgesic compounds. These assays are typically characterized by hyperexcitable and/or abnormally, spontaneously active cells. Whereas manual electrophysiology experiments provide high-resolution biophysical data to characterize both in vitro models and potential therapeutic modalities (e.g., action potential characteristics, the role of specific ion channels, and receptors), these techniques are hampered by their low throughput. We have established a spontaneously active dorsal root ganglia (DRG) platform using multiwell multielectrode arrays (MEAs) that greatly increase the ability to evaluate the effects of multiple compounds and conditions on DRG excitability within the context of a cellular network. We show that spontaneous DRG firing can be attenuated with selective Na(+) and Ca(2+) channel blockers, as well as enhanced with K(+) channel blockers. In addition, spontaneous activity can be augmented with both the transient receptor potential cation channel subfamily V member 1 agonist capsaicin and the peptide bradykinin and completely blocked with neurokinin receptor antagonists. Finally, we validated the use of this assay by demonstrating that commonly used neuropathic pain therapeutics suppress DRG spontaneous activity. Overall, we have optimized primary rat DRG cells on a multiwell MEA platform to generate and characterize spontaneously active cultures that have the potential to be used as an in vitro phenotypic assay to evaluate potential therapeutics in rodent models of pain.
Asunto(s)
Ganglios Espinales/citología , Neuronas/fisiología , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Animales , Bradiquinina/farmacología , Bloqueadores de los Canales de Calcio/farmacología , Capsaicina/farmacología , Células Cultivadas , Embrión de Mamíferos , Femenino , Calor , Moduladores del Transporte de Membrana/farmacología , Mibefradil/farmacología , Neuronas/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Fármacos del Sistema Sensorial/farmacología , Bloqueadores de los Canales de Sodio/farmacología , Cloruro de Sodio/farmacología , Sustancia P/metabolismo , Tetrodotoxina/farmacologíaRESUMEN
Extensive evidence implicates GluN2B-containing NMDA receptors (GluN2B-NMDARs) in excitotoxic-insult-induced neurodegeneration and amyloid ß (Aß)-induced synaptic dysfunction. Therefore, inhibiting GluN2B-NMDARs would appear to be a potential therapeutic strategy to provide neuroprotection and improve cognitive function in Alzheimer's disease (AD). However, there are no reports of long-term in vivo treatment of AD mouse models with GluN2B antagonists. We used piperidine18 (Pip18), a potent and selective GluN2B-NMDAR antagonist with favorable pharmacokinetic properties, for long-term dosing in AD mouse models. Reduced freezing behavior in Tg2576 mice during fear conditioning was partially reversed after subchronic (17 d) Pip18 treatment. However, analysis of freezing behavior in different contexts indicated that this increased freezing likely involves elevated anxiety or excessive memory generalization in both nontransgenic (NTG) and Tg2576 mice. In PS2APP mice chronically fed with medicated food containing Pip18 for 4 months, spatial learning and memory deficits were not rescued, plaque-associated spine loss was not affected, and synaptic function was not altered. At the same time, altered open field activity consistent with increased anxiety and degraded performance in an active avoidance task were observed in NTG after chronic treatment. These results indicate that long-term treatment with a GluN2B-NMDAR antagonist does not provide a disease-modifying benefit and could cause cognitive liabilities rather than symptomatic benefit in AD mouse models. Therefore, these results challenge the expectation of the therapeutic potential for GluN2B-NMDAR antagonists in AD.
Asunto(s)
Enfermedad de Alzheimer/complicaciones , Déficit de la Atención y Trastornos de Conducta Disruptiva/inducido químicamente , Trastornos de la Memoria/etiología , Trastornos de la Memoria/patología , Sinapsis/patología , Enfermedad de Alzheimer/genética , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animales , Conducta Animal/efectos de los fármacos , Modelos Animales de Enfermedad , Femenino , Células HEK293 , Humanos , Técnicas In Vitro , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Aprendizaje por Laberinto/fisiología , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutación/genética , Piperidinas/farmacologíaRESUMEN
The voltage-gated potassium channels Kv2.1 and Kv2.2 are highly expressed in pancreatic islets, yet their contribution to islet hormone secretion is not fully understood. Here we investigate the role of Kv2 channels in pancreatic islets using a combination of genetic and pharmacologic approaches. Pancreatic ß-cells from Kv2.1(-/-) mice possess reduced Kv current and display greater glucose-stimulated insulin secretion (GSIS) relative to WT ß-cells. Inhibition of Kv2.x channels with selective peptidyl [guangxitoxin-1E (GxTX-1E)] or small molecule (RY796) inhibitors enhances GSIS in isolated wild-type (WT) mouse and human islets, but not in islets from Kv2.1(-/-) mice. However, in WT mice neither inhibitor improved glucose tolerance in vivo. GxTX-1E and RY796 enhanced somatostatin release in isolated human and mouse islets and in situ perfused pancreata from WT and Kv2.1(-/-) mice. Kv2.2 silencing in mouse islets by adenovirus-small hairpin RNA (shRNA) specifically enhanced islet somatostatin, but not insulin, secretion. In mice lacking somatostatin receptor 5, GxTX-1E stimulated insulin secretion and improved glucose tolerance. Collectively, these data show that Kv2.1 regulates insulin secretion in ß-cells and Kv2.2 modulates somatostatin release in δ-cells. Development of selective Kv2.1 inhibitors without cross inhibition of Kv2.2 may provide new avenues to promote GSIS for the treatment of type 2 diabetes.
Asunto(s)
Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Canales de Potasio Shab/metabolismo , Somatostatina/metabolismo , Adulto , Animales , Proteínas de Artrópodos , Benzamidas/farmacología , Células Cultivadas , Fenómenos Electrofisiológicos , Femenino , Glucosa/farmacología , Humanos , Secreción de Insulina , Células Secretoras de Insulina/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Persona de Mediana Edad , Técnicas de Placa-Clamp , Péptidos/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Unión Proteica , Receptores de Somatostatina/genética , Receptores de Somatostatina/metabolismo , Canales de Potasio Shab/antagonistas & inhibidores , Canales de Potasio Shab/genética , Venenos de Araña/farmacología , Adulto JovenRESUMEN
Background: The World Health Organization has promoted "test and treat" guidelines for malaria since 2010, recommending all suspected malaria cases be confirmed with a parasitological test, typically a rapid diagnostic test (RDT), prior to treatment with antimalarial medications. However, many fevers at private drug shops in Uganda continue to be treated presumptively as malaria without diagnostic testing. Methods: The purpose of this study was to document private sector malaria case management in rural Uganda through a cross-sectional survey of drug shop clients in Bugoye sub-county. Drug shop vendors (n = 46) recorded information about sales interactions with clients reporting fever or requesting antimalarials and collected capillary blood samples from clients who purchased medications without an RDT. We estimated the proportion of clients who purchased an RDT, adhered to the RDT result, and received antimalarials without having laboratory-confirmed malaria. Results: Most drug shops were unlicensed (96%) and sold RDTs (98%). Of 934 clients with suspected malaria who visited study drug shops during the data collection period, only 25% bought an RDT. Since some clients reported previous RDTs from the public sector, 40% of clients were aware of their malaria status at the drug shop. Among those with negative tests, 36% still purchased antimalarials. Sixty-five percent of clients who purchased an antimalarial without an RDT subsequently tested negative. Conclusions: Despite national guidelines, drug shop clients who purchase antimalarials from drug shops in Bugoye are often not tested to confirm a malaria diagnosis prior to treatment. Most clients treated presumptively with antimalarials did not have malaria. Interventions are needed to improve malaria case management and rational drug use in the private sector.
Asunto(s)
Antimaláricos , Malaria , Humanos , Antimaláricos/uso terapéutico , Estudios Transversales , Uganda , Sector Privado , Malaria/diagnóstico , Malaria/tratamiento farmacológico , FiebreRESUMEN
Intracanal medicaments with maximal antimicrobial efficacy and minimal damage to resident stem cells are essential for successful regenerative endodontic procedures. 2-Hydroxyisocaproic acid (HICA) could have the attributes of a potential intracanal medicament. This study evaluates its cytotoxicity, genotoxicity, and effects on the odontogenic and osteogenic differentiation of the stem cells of the apical papilla (SCAP). Cytotoxicity and cell viability assays were performed on cells treated for 24, 48, and 72 h with varying concentrations of HICA and compared to the standard intracanal medicament, calcium hydroxide. The genotoxicity was assessed via immunofluorescence for two markers of DNA double-strand breaks: phosphorylated γH2AX and 53BP1. The SCAP differentiation was evaluated based on the alkaline phosphatase activity, Alizarin Red staining, and expression of odontogenic and osteogenic genes (DSPP1, BSP1, OCN, RUNX2) in the presence of selected HICA concentrations. HICA was not cytotoxic at concentrations up to 10 mg/mL, regardless of the exposure time, although it was cytostatic at all tested concentrations. HICA was not genotoxic at concentrations below 5 mg/mL. No difference in cytotoxicity or genotoxicity was found between HICA and calcium hydroxide at 1 mg/mL. HICA retained about 70% of the osteogenic differentiation potential at 1 mg/mL. Within the limitations of this in vitro study, we show that HICA at 1 mg/mL could be a potential intracanal medicament for REPs.
RESUMEN
Biological, genetic, and clinical evidence provide validation for N-type calcium channels (Ca(V)2.2) as therapeutic targets for chronic pain. A state-dependent Ca(V)2.2 inhibitor may provide an improved therapeutic window over ziconotide, the peptidyl Ca(V)2.2 inhibitor used clinically. Supporting this notion, we recently reported that in preclinical models, the state-dependent Ca(V)2 inhibitor (3R)-5-(3-chloro-4-fluorophenyl)-3-methyl-3-(pyrimidin-5-ylmethyl)-1-(1H-1,2,4-triazol-3-yl)-1,3-dihydro-2H-indol-2-one (TROX-1) has an improved therapeutic window compared with ziconotide. Here we characterize TROX-1 inhibition of Cav2.2 channels in more detail. When channels are biased toward open/inactivated states by depolarizing the membrane potential under voltage-clamp electrophysiology, TROX-1 inhibits Ca(V)2.2 channels with an IC(50) of 0.11 µM. The voltage dependence of Ca(V)2.2 inhibition was examined using automated electrophysiology. TROX-1 IC(50) values were 4.2, 0.90, and 0.36 µM at -110, -90, and -70 mV, respectively. TROX-1 displayed use-dependent inhibition of Ca(V)2.2 with a 10-fold IC(50) separation between first (27 µM) and last (2.7 µM) pulses in a train. In a fluorescence-based calcium influx assay, TROX-1 inhibited Ca(V)2.2 channels with an IC(50) of 9.5 µM under hyperpolarized conditions and 0.69 µM under depolarized conditions. Finally, TROX-1 potency was examined across the Ca(V)2 subfamily. Depolarized IC(50) values were 0.29, 0.19, and 0.28 µM by manual electrophysiology using matched conditions and 1.8, 0.69, and 1.1 µM by calcium influx for Ca(V)2.1, Ca(V)2.2, and Ca(V)2.3, respectively. Together, these in vitro data support the idea that a state-dependent, non-subtype-selective Ca(V)2 channel inhibitor can achieve an improved therapeutic window over the relatively state-independent Ca(V)2.2-selective inhibitor ziconotide in preclinical models of chronic pain.
Asunto(s)
Bloqueadores de los Canales de Calcio/química , Canales de Calcio Tipo N/efectos de los fármacos , Indoles/química , Triazoles/química , Bloqueadores de los Canales de Calcio/farmacología , Línea Celular , Humanos , Indoles/farmacología , Concentración 50 Inhibidora , Potenciales de la Membrana/efectos de los fármacos , Técnicas de Placa-Clamp , Triazoles/farmacologíaRESUMEN
The World Health Organization recommends all suspected malaria cases be confirmed with a parasitological test, typically a rapid diagnostic test (RDT), prior to treatment. Despite recommendations, many fevers presenting at private drug shops are treated presumptively as malaria without diagnostic testing. The purpose of this qualitative study was to describe community perceptions of RDTs and explore ways to improve malaria case management at drug shops in Bugoye, western Uganda. A total of 63 in-depth interviews were conducted between September and December 2021 with 24 drug shop clients, 19 drug shop vendors, 12 community health workers, and 8 health and community officials. Data was analyzed using thematic content analysis and narrative techniques. While drug shop clients valued RDTs, the cost of the test limited their use. Further, mistrust in negative results and fear about treatment options for conditions other than malaria led to nonadherence to negative RDTs. Improvement with antimalarials after a negative RDT, or no RDT at all, was seen as proof an individual had malaria, reinforcing the acceptability of liberal antimalarial use. Drug shop vendors were knowledgeable about malaria case management but financially conflicted between recommending best practices and losing business. While clients viewed drug shop vendors as trusted health professionals, health officials distrusted them as business owners focused on maximizing profits. Study results suggest public-private partnerships that recognize the essential role of drug shops, better incorporate them into the healthcare system, and leverage the high levels of community trust in vendors, could provide greater opportunities for oversight and training to improve private-sector malaria case management. Interventions that address financial barriers to RDT use, emphasize the financial benefits of malaria testing, increase vendor knowledge about illnesses confused with malaria, and improve the quality of vendor-client counseling could increase RDT uptake and improve adherence to RDT results.
RESUMEN
Mitogen-activated protein kinase (MAPK) phosphatase 5 (MKP5) is responsible for regulating the activity of the stress-responsive MAPKs and has been put forth as a potential therapeutic target for a number of diseases, including dystrophic muscle disease a fatal rare disease which has neither a treatment nor cure. In previous work, we identified Compound 1 (3,3-dimethyl-1-((9-(methylthio)-5,6-dihydrothieno[3,4-h]quinazolin-2-yl)thio)butan-2-one) as the lead compound of a novel class of MKP5 inhibitors. In this work, we explore the structure-activity relationship for inhibition of MKP5 through modifications to the scaffold and functional groups present in 1. A series of derivative compounds was designed, synthesized, and evaluated for inhibition of MKP5. In addition, the X-ray crystal structures of six enzyme-inhibitor complexes were solved, further elucidating the necessary requirements for MKP5 inhibition. We found that the parallel-displaced π-π interaction between the inhibitor three-ring core and Tyr435 is critical for modulating potency, and that modifications to the core and functionalization at the C-9 position are essential for ensuring proper positioning of the core for this interaction. These results lay the foundation from which more potent MKP5 allosteric inhibitors can be developed for potential therapeutics towards the treatment of dystrophic muscle disease.
Asunto(s)
Relación Estructura-ActividadRESUMEN
Identification of selective ion channel inhibitors represents a critical step for understanding the physiological role that these proteins play in native systems. In particular, voltage-gated potassium (K(V)2) channels are widely expressed in tissues such as central nervous system, pancreas, and smooth muscle, but their particular contributions to cell function are not well understood. Although potent and selective peptide inhibitors of K(V)2 channels have been characterized, selective small molecule K(V)2 inhibitors have not been reported. For this purpose, high-throughput automated electrophysiology (IonWorks Quattro; Molecular Devices, Sunnyvale, CA) was used to screen a 200,000-compound mixture (10 compounds per sample) library for inhibitors of K(V)2.1 channels. After deconvolution of 190 active samples, two compounds (A1 and B1) were identified that potently inhibit K(V)2.1 and the other member of the K(V)2 family, K(V)2.2 (IC(50), 0.1-0.2 µM), and that possess good selectivity over K(V)1.2 (IC(50) >10 µM). Modeling studies suggest that these compounds possess a similar three-dimensional conformation. Compounds A1 and B1 are >10-fold selective over Na(V) channels and other K(V) channels and display weak activity (5-9 µM) on Ca(V) channels. The biological activity of compound A1 on native K(V)2 channels was confirmed in electrophysiological recordings of rat insulinoma cells, which are known to express K(V)2 channels. Medicinal chemistry efforts revealed a defined structure-activity relationship and led to the identification of two compounds (RY785 and RY796) without significant Ca(V) channel activity. Taken together, these newly identified channel inhibitors represent important tools for the study of K(V)2 channels in biological systems.
Asunto(s)
Descubrimiento de Drogas/métodos , Bloqueadores de los Canales de Potasio/química , Bloqueadores de los Canales de Potasio/farmacología , Canales de Potasio Shab/antagonistas & inhibidores , Animales , Células CHO , Cricetinae , Cricetulus , Humanos , Ratas , Canales de Potasio Shab/fisiología , Relación Estructura-ActividadRESUMEN
N-type calcium channels (Ca(v)2.2) have been shown to play a critical role in pain. A series of low molecular weight 2-aryl indoles were identified as potent Ca(v)2.2 blockers with good in vitro and in vivo potency.
Asunto(s)
Bloqueadores de los Canales de Calcio/uso terapéutico , Canales de Calcio Tipo N/metabolismo , Indoles/uso terapéutico , Dolor/tratamiento farmacológico , Animales , Bloqueadores de los Canales de Calcio/farmacocinética , Bloqueadores de los Canales de Calcio/farmacología , Perros , Haplorrinos , Humanos , Indoles/farmacocinética , Indoles/farmacología , RatasRESUMEN
Glioblastoma (GBM) is the most common primary malignant tumor of the central nervous system with a dismal prognosis. Locoregional failure is common despite high doses of radiation therapy, which has prompted great interest in developing novel strategies to radiosensitize these cancers. Our group previously identified a calcium channel blocker (CCB), mibefradil, as a potential GBM radiosensitizer. We discovered that mibefradil selectively inhibits a key DNA repair pathway, alternative non-homologous end joining. We then initiated a phase I clinical trial that revealed promising initial efficacy of mibefradil, but further development was hampered by dose-limiting toxicities, including CCB-related cardiotoxicity, off-target hERG channel and cytochrome P450 enzymes (CYPs) interactions. Here, we show that mibefradil inhibits DNA repair independent of its CCB activity, and report a series of mibefradil analogues which lack CCB activity and demonstrate reduced hERG and CYP activity while retaining potency as DNA repair inhibitors. We present in vivo pharmacokinetic studies of the top analogues with evidence of brain penetration. We also report a targeted siRNA-based screen which suggests a possible role for mTOR and Akt in DNA repair inhibition by this class of drugs. Taken together, these data reveal a new class of mibefradil-based DNA repair inhibitors which can be further advanced into pre-clinical testing and eventually clinical trials, as potential GBM radiosensitizers.
RESUMEN
Voltage-gated calcium channel (Ca(v))2.2 (N-type calcium channels) are key components in nociceptive transmission pathways. Ziconotide, a state-independent peptide inhibitor of Ca(v)2.2 channels, is efficacious in treating refractory pain but exhibits a narrow therapeutic window and must be administered intrathecally. We have discovered an N-triazole oxindole, (3R)-5-(3-chloro-4-fluorophenyl)-3-methyl-3-(pyrimidin-5-ylmethyl)-1-(1H-1,2,4-triazol-3-yl)-1,3-dihydro-2H-indol-2-one (TROX-1), as a small-molecule, state-dependent blocker of Ca(v)2 channels, and we investigated the therapeutic advantages of this compound for analgesia. TROX-1 preferentially inhibited potassium-triggered calcium influx through recombinant Ca(v)2.2 channels under depolarized conditions (IC(50) = 0.27 microM) compared with hyperpolarized conditions (IC(50) > 20 microM). In rat dorsal root ganglion (DRG) neurons, TROX-1 inhibited omega-conotoxin GVIA-sensitive calcium currents (Ca(v)2.2 channel currents), with greater potency under depolarized conditions (IC(50) = 0.4 microM) than under hyperpolarized conditions (IC(50) = 2.6 microM), indicating state-dependent Ca(v)2.2 channel block of native as well as recombinant channels. TROX-1 fully blocked calcium influx mediated by a mixture of Ca(v)2 channels in calcium imaging experiments in rat DRG neurons, indicating additional block of all Ca(v)2 family channels. TROX-1 reversed inflammatory-induced hyperalgesia with maximal effects equivalent to nonsteroidal anti-inflammatory drugs, and it reversed nerve injury-induced allodynia to the same extent as pregabalin and duloxetine. In contrast, no significant reversal of hyperalgesia was observed in Ca(v)2.2 gene-deleted mice. Mild impairment of motor function in the Rotarod test and cardiovascular functions were observed at 20- to 40-fold higher plasma concentrations than required for analgesic activities. TROX-1 demonstrates that an orally available state-dependent Ca(v)2 channel blocker may achieve a therapeutic window suitable for the treatment of chronic pain.
Asunto(s)
Analgésicos/farmacología , Bloqueadores de los Canales de Calcio/farmacología , Canales de Calcio Tipo N/fisiología , Indoles/farmacología , Triazoles/farmacología , Analgésicos/efectos adversos , Analgésicos/farmacocinética , Animales , Barorreflejo/efectos de los fármacos , Disponibilidad Biológica , Bloqueadores de los Canales de Calcio/efectos adversos , Bloqueadores de los Canales de Calcio/farmacocinética , Canales de Calcio Tipo N/genética , Canales de Calcio Tipo R/fisiología , Proteínas de Transporte de Catión/fisiología , Línea Celular , Perros , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/fisiología , Hiperalgesia/tratamiento farmacológico , Hipotensión Ortostática/inducido químicamente , Indoles/efectos adversos , Indoles/farmacocinética , Masculino , Ratones , Ratones Noqueados , Neuronas/efectos de los fármacos , Neuronas/fisiología , Dolor/tratamiento farmacológico , Dolor/etiología , Técnicas de Placa-Clamp , Ratas , Ratas Sprague-Dawley , Triazoles/efectos adversos , Triazoles/farmacocinéticaRESUMEN
CXCL13 is the cognate chemokine agonist of CXCR5, a class A G-protein-coupled receptor (GPCR) that is essential for proper humoral immune responses. Using a `methionine scanning' mutagenesis method on the N-terminus of CXCL13, which is the chemokine signaling region, it was shown that minor length alterations and side-chain substitutions still result in CXCR5 activation. This observation indicates that the orthosteric pocket of CXCR5 can tolerate these changes without severely affecting the activity. The introduction of bulk on the ligand was well tolerated by the receptor, whereas a loss of contacts was less tolerated. Furthermore, two crystal structures of CXCL13 mutants were solved, both of which represent the first uncomplexed structures of the human protein. These structures were stabilized by unique interactions formed by the N-termini of the ligands, indicating that CXCL13 exhibits substantial N-terminal flexibility while the chemokine core domain remains largely unchanged. Additionally, it was observed that CXCL13 harbors a large degree of flexibility in the C-terminal extension of the ligand. Comparisons with other published structures of human and murine CXCL13 validate the relative rigidity of the core domain as well as the N- and C-terminal mobilities. Collectively, these mutants and their structures provide the field with additional insights into how CXCL13 interacts with CXCR5.
Asunto(s)
Quimiocina CXCL13 , Receptores CXCR5 , Quimiocina CXCL13/química , Quimiocina CXCL13/metabolismo , Cristalografía por Rayos X , Humanos , Modelos Moleculares , Unión Proteica , Dominios Proteicos , Estructura Secundaria de Proteína , Receptores CXCR5/metabolismoRESUMEN
The mitogen-activated protein kinase (MAPK) phosphatases (MKPs) have been considered "undruggable," but their position as regulators of the MAPKs makes them promising therapeutic targets. MKP5 has been suggested as a potential target for the treatment of dystrophic muscle disease. Here, we identified an inhibitor of MKP5 using a p38α MAPK-derived, phosphopeptide-based small-molecule screen. We solved the structure of MKP5 in complex with this inhibitor, which revealed a previously undescribed allosteric binding pocket. Binding of the inhibitor to this pocket collapsed the MKP5 active site and was predicted to limit MAPK binding. Treatment with the inhibitor recapitulated the phenotype of MKP5 deficiency, resulting in activation of p38 MAPK and JNK. We demonstrated that MKP5 was required for TGF-ß1 signaling in muscle and that the inhibitor blocked TGF-ß1-mediated Smad2 phosphorylation. TGF-ß1 pathway antagonism has been proposed for the treatment of dystrophic muscle disease. Thus, allosteric inhibition of MKP5 represents a therapeutic strategy against dystrophic muscle disease.
Asunto(s)
Fosfatasas de Especificidad Dual/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Ensayos Analíticos de Alto Rendimiento/métodos , Fosfatasas de la Proteína Quinasa Activada por Mitógenos/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/farmacología , Sitio Alostérico/genética , Secuencia de Aminoácidos , Animales , Diferenciación Celular/efectos de los fármacos , Línea Celular , Fosfatasas de Especificidad Dual/química , Fosfatasas de Especificidad Dual/metabolismo , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/metabolismo , Femenino , Humanos , Cinética , Ratones , Ratones Noqueados , Fosfatasas de la Proteína Quinasa Activada por Mitógenos/química , Fosfatasas de la Proteína Quinasa Activada por Mitógenos/metabolismo , Mioblastos/citología , Mioblastos/efectos de los fármacos , Mioblastos/metabolismo , Unión Proteica/efectos de los fármacos , Homología de Secuencia de Aminoácido , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/metabolismoRESUMEN
Falsified and substandard medicines are associated with tens of thousands of deaths, mainly in young children in poor countries. Poor-quality drugs exact an annual economic toll of up to US$200 billion and contribute to the increasing peril of antimicrobial resistance. The WHO has emerged recently as the global leader in the battle against poor-quality drugs, and pharmaceutical companies have increased their roles in assuring the integrity of drug supply chains. Despite advances in drug quality surveillance and detection technology, more efforts are urgently required in research, policy, and field monitoring to halt the pandemic of bad drugs. In addition to strengthening international and national pharmaceutical governance, in part by national implementation of the Model Law on Medicines and Crime, a quantifiable Sustainable Development Goal target and an international convention to insure drug quality and safety are urgent priorities.