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PURPOSE OF REVIEW: Lung cancer is one of the most common malignancies in the whole world, and the pulmonologist is generally the first medical professional to meet the patient and decide what method of tumour sampling is preferable in each specific case. It is imperative for pulmonary physicians to be aware of the intricacies of the diagnostic process, and understand the multiple challenges that are encountered, from the moment the tissue specimen leaves their offices and is sent to the pathology laboratory, until the diagnosis reaches the patient and treating physician. RECENT FINDINGS: The new 2021 WHO classification of thoracic tumours recommended a minimum immunohistochemical (IHC) diagnostic panel for nonsmall cell lung cancer (NSCLC), and following publications of different institutional and country-based guidelines, advocated basic molecular testing for epithelial growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) and programmed cell death ligand 1 (PD-L1) to be initiated by the diagnosing pathologist in all cases of biopsy or resection specimens. In general, sequential testing for molecular biomarkers was not recommended due to tissue wastage, instead next generation sequencing (NGS) diagnostic panel was supported. SUMMARY: The lung cancer specimen has to undergo histologic diagnosis through a panel of IHC studies, and -preferably, a reflex molecular study by NGS including several targetable genes. Adequate communication and clinical information preclude the pathologist from "overusing" the tissue for additional studies, while focusing on preservation of material for molecular testing.
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Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Biomarcadores , BiópsiaRESUMO
We report an innovative approach to producing bacteriochlorins (bacs) via formal cycloaddition by subjecting a porphyrin to a trimolecular reaction. Bacs are near-infrared probes with the intrinsic ability to serve in multimodal imaging. However, despite their ability to fluoresce and chelate metal ions, existing bacs have thus offered limited ability to label biomolecules for target specificity or have lacked chemical purity, limiting their use in bio-imaging. In this work, bacs allowed a precise and controlled appending of clickable linkers, lending the porphyrinoids substantially more chemical stability, clickability, and solubility, rendering them more suitable for preclinical investigation. Our bac probes enable the targeted use of biomolecules in fluorescence imaging and Cerenkov luminescence for guided intraoperative imaging. Bacs' capacity for chelation provides opportunities for use in non-invasive positron emission tomography/computed tomography. Herein, we report the labeling of bacs with Hs1a, a (NaV1.7)-sodium-channel-binding peptide derived from the Chinese tarantula Cyriopagopus schmidti to yield Bac-Hs1a and radiolabeled Hs1a, which shuttles our bac sensor(s) to mouse nerves. In vivo, the bac sensor allowed us to observe high signal-to-background ratios in the nerves of animals injected with fluorescent Bac-Hs1a and radiolabeled Hs1a in all imaging modes. This study demonstrates that Bac-Hs1a and [64Cu]Cu-Bac-Hs1a accumulate in peripheral nerves, providing contrast and utility in the preclinical space. For the chemistry and bio-imaging fields, this study represents an exciting starting point for the modular manipulation of bacs, their development and use as probes for diagnosis, and their deployment as formidable multiplex nerve-imaging agents for use in routine imaging experiments.
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Porfirinas , Animais , CamundongosRESUMO
Chronic pelvic pain (CPP) is the primary symptom of endometriosis patients, but adequate treatments are lacking. Modulation of ion channels expressed by sensory nerves innervating the viscera has shown promise for the treatment of irritable bowel syndrome and overactive bladder. However, similar approaches for endometriosis-associated CPP remain underdeveloped. Here, we examined the role of the voltage-gated sodium (NaV ) channel NaV 1.7 in (i) the sensitivity of vagina-innervating sensory afferents and investigated whether (ii) NaV 1.7 inhibition reduces nociceptive signals from the vagina and (iii) ameliorates endometriosis-associated CPP. The mechanical responsiveness of vagina-innervating sensory afferents was assessed with ex vivo single-unit recording preparations. Pain evoked by vaginal distension (VD) was quantified by the visceromotor response (VMR) in vivo. In control mice, pharmacological activation of NaV 1.7 with OD1 sensitised vagina-innervating pelvic afferents to mechanical stimuli. Using a syngeneic mouse model of endometriosis, we established that endometriosis sensitised vagina-innervating pelvic afferents to mechanical stimuli. The highly selective NaV 1.7 inhibitor Tsp1a revealed that this afferent hypersensitivity occurred in a NaV 1.7-dependent manner. Moreover, in vivo intra-vaginal treatment with Tsp1a reduced the exaggerated VMRs to VD which is characteristic of mice with endometriosis. Conversely, Tsp1a did not alter ex vivo afferent mechanosensitivity nor in vivo VMRs to VD in Sham control mice. Collectively, these findings suggest that NaV 1.7 plays a crucial role in endometriosis-induced vaginal hyperalgesia. Importantly, NaV 1.7 inhibition selectively alleviated endometriosis-associated CPP without the loss of normal sensation, suggesting that selective targeting of NaV 1.7 could improve the quality of life of women with endometriosis.
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BACKGROUND: Ischemia-reperfusion injury (IRI) is one of the major risk factors implicated in morbidity and mortality associated with cardiovascular disease. During cardiac ischemia, the buildup of acidic metabolites results in decreased intracellular and extracellular pH, which can reach as low as 6.0 to 6.5. The resulting tissue acidosis exacerbates ischemic injury and significantly affects cardiac function. METHODS: We used genetic and pharmacologic methods to investigate the role of acid-sensing ion channel 1a (ASIC1a) in cardiac IRI at the cellular and whole-organ level. Human induced pluripotent stem cell-derived cardiomyocytes as well as ex vivo and in vivo models of IRI were used to test the efficacy of ASIC1a inhibitors as pre- and postconditioning therapeutic agents. RESULTS: Analysis of human complex trait genetics indicates that variants in the ASIC1 genetic locus are significantly associated with cardiac and cerebrovascular ischemic injuries. Using human induced pluripotent stem cell-derived cardiomyocytes in vitro and murine ex vivo heart models, we demonstrate that genetic ablation of ASIC1a improves cardiomyocyte viability after acute IRI. Therapeutic blockade of ASIC1a using specific and potent pharmacologic inhibitors recapitulates this cardioprotective effect. We used an in vivo model of myocardial infarction and 2 models of ex vivo donor heart procurement and storage as clinical models to show that ASIC1a inhibition improves post-IRI cardiac viability. Use of ASIC1a inhibitors as preconditioning or postconditioning agents provided equivalent cardioprotection to benchmark drugs, including the sodium-hydrogen exchange inhibitor zoniporide. At the cellular and whole organ level, we show that acute exposure to ASIC1a inhibitors has no effect on cardiac ion channels regulating baseline electromechanical coupling and physiologic performance. CONCLUSIONS: Our data provide compelling evidence for a novel pharmacologic strategy involving ASIC1a blockade as a cardioprotective therapy to improve the viability of hearts subjected to IRI.
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Canais Iônicos Sensíveis a Ácido/biossíntese , Canais Iônicos Sensíveis a Ácido/genética , Isquemia Miocárdica/genética , Isquemia Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/genética , Traumatismo por Reperfusão Miocárdica/metabolismo , Animais , Células Cultivadas , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Células-Tronco Pluripotentes Induzidas/metabolismo , Preparação de Coração Isolado/métodos , Masculino , Camundongos , Camundongos Knockout , Isquemia Miocárdica/terapia , Traumatismo por Reperfusão Miocárdica/terapia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Polimorfismo de Nucleotídeo Único/fisiologia , Recuperação de Função Fisiológica/efeitos dos fármacos , Recuperação de Função Fisiológica/fisiologia , Venenos de Aranha/farmacologiaRESUMO
Dravet syndrome is a catastrophic, pharmacoresistant epileptic encephalopathy. Disease onset occurs in the first year of life, followed by developmental delay with cognitive and behavioral dysfunction and substantially elevated risk of premature death. The majority of affected individuals harbor a loss-of-function mutation in one allele of SCN1A, which encodes the voltage-gated sodium channel NaV1.1. Brain NaV1.1 is primarily localized to fast-spiking inhibitory interneurons; thus the mechanism of epileptogenesis in Dravet syndrome is hypothesized to be reduced inhibitory neurotransmission leading to brain hyperexcitability. We show that selective activation of NaV1.1 by venom peptide Hm1a restores the function of inhibitory interneurons from Dravet syndrome mice without affecting the firing of excitatory neurons. Intracerebroventricular infusion of Hm1a rescues Dravet syndrome mice from seizures and premature death. This precision medicine approach, which specifically targets the molecular deficit in Dravet syndrome, presents an opportunity for treatment of this intractable epilepsy.
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Epilepsias Mioclônicas/tratamento farmacológico , Interneurônios/metabolismo , Mutação , Canal de Sódio Disparado por Voltagem NAV1.1/metabolismo , Venenos de Aranha/farmacologia , Transmissão Sináptica/efeitos dos fármacos , Animais , Células CHO , Cricetulus , Epilepsias Mioclônicas/genética , Epilepsias Mioclônicas/metabolismo , Epilepsias Mioclônicas/patologia , Células HEK293 , Humanos , Interneurônios/patologia , Camundongos , Camundongos Mutantes , Canal de Sódio Disparado por Voltagem NAV1.1/genéticaRESUMO
Gating modifier toxins (GMTs) are venom-derived peptides isolated from spiders and other venomous creatures and modulate activity of disease-relevant voltage-gated ion channels and are therefore being pursued as therapeutic leads. The amphipathic surface profile of GMTs has prompted the proposal that some GMTs simultaneously bind to the cell membrane and voltage-gated ion channels in a trimolecular complex. Here, we examined whether there is a relationship among spider GMT amphipathicity, membrane binding, and potency or selectivity for voltage-gated sodium (NaV) channels. We used NMR spectroscopy and in silico calculations to examine the structures and physicochemical properties of a panel of nine GMTs and deployed surface plasmon resonance to measure GMT affinity for lipids putatively found in proximity to NaV channels. Electrophysiology was used to quantify GMT activity on NaV1.7, an ion channel linked to chronic pain. Selectivity of the peptides was further examined against a panel of NaV channel subtypes. We show that GMTs adsorb to the outer leaflet of anionic lipid bilayers through electrostatic interactions. We did not observe a direct correlation between GMT amphipathicity and affinity for lipid bilayers. Furthermore, GMT-lipid bilayer interactions did not correlate with potency or selectivity for NaVs. We therefore propose that increased membrane binding is unlikely to improve subtype selectivity and that the conserved amphipathic GMT surface profile is an adaptation that facilitates simultaneous modulation of multiple NaVs.
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Canal de Sódio Disparado por Voltagem NAV1.7/metabolismo , Venenos de Aranha/farmacologia , Toxinas Biológicas/farmacologia , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/química , Proteínas de Artrópodes/metabolismo , Proteínas de Artrópodes/farmacologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Células HEK293 , Humanos , Bicamadas Lipídicas/metabolismo , Modelos Moleculares , Venenos de Aranha/química , Venenos de Aranha/metabolismo , Aranhas/química , Toxinas Biológicas/química , Toxinas Biológicas/metabolismo , Bloqueadores do Canal de Sódio Disparado por Voltagem/química , Bloqueadores do Canal de Sódio Disparado por Voltagem/metabolismo , Bloqueadores do Canal de Sódio Disparado por Voltagem/farmacologiaRESUMO
Molecular imaging has revolutionised the field of biomedical research by providing a non-invasive means to visualise and understand biochemical processes within living organisms. Optical fluorescent imaging in particular allows researchers to gain valuable insights into the dynamic behaviour of a target of interest in real time. Ion channels play a fundamental role in cellular signalling, and they are implicated in diverse pathological conditions, making them an attractive target in the field of molecular imaging. Many venom peptides exhibit exquisite selectivity and potency towards ion channels, rendering them ideal agents for molecular imaging applications. In this review, we illustrate the use of fluorescently-labelled venom peptides for disease diagnostics and intraoperative imaging of brain tumours and peripheral nerves. Finally, we address challenges for the development and clinical translation of venom peptides as nerve-targeted imaging agents.
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Imagem Molecular , Peptídeos , Humanos , Animais , Imagem Molecular/métodos , Peptídeos/química , Peçonhas/química , Receptores de Peptídeos/metabolismo , Corantes Fluorescentes/químicaRESUMO
In this study, we report the innovative application of whole-cell patch-clamp electrophysiology in assessing broad-spectrum neutralisation by three different antivenoms, of venoms from the medically significant scorpion genus Centruroides. Envenomations by as many as 21 species from the Centruroides genus result in up to 300,000 envenomations per year in Mexico, which poses significant and potentially life-threatening pathophysiology. We first evaluated the in vitro manifestation of envenomation against two human voltage-gated sodium (hNaV) channel subtypes: hNaV1.4 and hNaV1.5, which are primarily expressed in skeletal muscles and cardiomyocytes, respectively. The neutralisation of venom activity was then characterised for three different antivenoms using a direct competition model against the more potent target, hNaV1.4. While broad-spectrum neutralisation was identified, variation in neutralisation arose for Centruroides elegans, C. limpidus, C. noxius and C. suffusus venoms, despite the presence of a number of these venoms within the immunising mixture. This raises questions regarding the truly "broad" neutralisation capacity of the antivenoms. This study not only extends previous validation of the in vitro investigation of antivenom efficacy utilising the whole-cell patch-clamp technique but also underscores the potential of this animal-free model in exploring cross-reactivity, experimental scalability, and most importantly, informing clinical management practices regarding the administration of antivenom in Mexico.
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Antivenenos , Venenos de Escorpião , Escorpiões , Animais , Venenos de Escorpião/toxicidade , Antivenenos/farmacologia , Humanos , Picadas de Escorpião/tratamento farmacológico , Técnicas de Patch-Clamp , Especificidade da Espécie , México , Animais PeçonhentosRESUMO
Surgeries and trauma result in traumatic and iatrogenic nerve damage that can result in a debilitating condition that approximately affects 189 million individuals worldwide. The risk of nerve injury during oncologic surgery is increased due to tumors displacing normal nerve location, blood turbidity, and past surgical procedures, which complicate even an experienced surgeon's ability to precisely locate vital nerves. Unfortunately, there is a glaring absence of contrast agents to assist surgeons in safeguarding vital nerves. To address this unmet clinical need, we leveraged the abundant expression of the voltage-gated sodium channel 1.7 (NaV1.7) as an intraoperative marker to access peripheral nerves in vivo, and visualized nerves for surgical guidance using a fluorescently-tagged version of a potent NaV1.7-targeted peptide, Tsp1a, derived from a Peruvian tarantula. We characterized the expression of NaV1.7 in sensory and motor peripheral nerves across mouse, primate, and human specimens and demonstrated universal expression. We synthesized and characterized a total of 10 fluorescently labeled Tsp1a-peptide conjugates to delineate nerves. We tested the ability of these peptide-conjugates to specifically accumulate in mouse nerves with a high signal-to-noise ratio in vivo. Using the best-performing candidate, Tsp1a-IR800, we performed thyroidectomies in non-human primates and demonstrated successful demarcation of the recurrent laryngeal and vagus nerves, which are commonly subjected to irreversible damage. The ability of Tsp1a to enhance nerve contrast during surgery provides opportunities to minimize nerve damage and revolutionize standards of care across various surgical specialties.
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Introduction: Deep learning (DL) models predicting biomarker expression in images of hematoxylin and eosin (H&E)-stained tissues can improve access to multi-marker immunophenotyping, crucial for therapeutic monitoring, biomarker discovery, and personalized treatment development. Conventionally, these models are trained on ground truth cell labels derived from IHC-stained tissue sections adjacent to H&E-stained ones, which might be less accurate than labels from the same section. Although many such DL models have been developed, the impact of ground truth cell label derivation methods on their performance has not been studied. Methodology: In this study, we assess the impact of cell label derivation on H&E model performance, with CD3+ T-cells in lung cancer tissues as a proof-of-concept. We compare two Pix2Pix generative adversarial network (P2P-GAN)-based virtual staining models: one trained with cell labels obtained from the same tissue section as the H&E-stained section (the 'same-section' model) and one trained on cell labels from an adjacent tissue section (the 'serial-section' model). Results: We show that the same-section model exhibited significantly improved prediction performance compared to the 'serial-section' model. Furthermore, the same-section model outperformed the serial-section model in stratifying lung cancer patients within a public lung cancer cohort based on survival outcomes, demonstrating its potential clinical utility. Discussion: Collectively, our findings suggest that employing ground truth cell labels obtained through the same-section approach boosts immunophenotyping DL solutions.
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Aprendizado Profundo , Imunofenotipagem , Neoplasias Pulmonares , Coloração e Rotulagem , Humanos , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Coloração e Rotulagem/métodos , Biomarcadores Tumorais/metabolismo , Masculino , Linfócitos T/imunologia , FemininoRESUMO
Despite the recent advances in understanding the mechanisms of olfaction, no tools are currently available to noninvasively identify loss of smell. Because of the substantial increase in patients presenting with coronavirus disease 2019-related loss of smell, the pandemic has highlighted the urgent need to develop quantitative methods. Methods: Our group investigated the use of a novel fluorescent probe named Tsp1a-IR800P as a tool to diagnose loss of smell. Tsp1a-IR800P targets sodium channel 1.7, which plays a critical role in olfaction by aiding the signal propagation to the olfactory bulb. Results: Intuitively, we have identified that conditions leading to loss of smell, including chronic inflammation and coronavirus disease 2019, correlate with the downregulation of sodium channel 1.7 expression in the olfactory epithelium, both at the transcript and at the protein levels. We demonstrated that lower Tsp1a-IR800P fluorescence emissions significantly correlate with loss of smell in live animals-thus representing a potential tool for its semiquantitative assessment. Currently available methods rely on delayed subjective behavioral studies. Conclusion: This method could aid in significantly improving preclinical and clinical studies by providing a way to objectively diagnose loss of smell and therefore aid the development of therapeutic interventions.
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Transtornos do Olfato , Transtornos do Olfato/diagnóstico por imagem , Animais , Humanos , Imagem Óptica/métodos , Olfato , Corantes Fluorescentes/química , Camundongos , COVID-19/diagnóstico por imagem , MasculinoRESUMO
Our case is an asymptomatic, non-smoking, East Asian woman in her 40s presenting with a solitary pulmonary nodule (SPN). On imaging, the 1.7 cm solid SPN located in the left upper lobe, was rounded in morphology and moderately fluorodeoxyglucose avid. The clinical pretest probability of malignancy assessed by risk prediction models such as Brock (19.1%), Mayo Clinic (56.2%) and Herder (51.4%) was discordant. She underwent a percutaneous CT-guided needle biopsy, establishing a diagnosis of pulmonary sclerosing pneumocytoma (PSP). PSP is a rare benign lung neoplasm with indolent growth characteristics that has been described predominantly in non-smoking women. Our case illustrates the limitations of applying existing risk prediction models in Asia where the epidemiology and biology of lung cancer differ significantly from the Caucasian derivation cohorts. Additionally, the risk models do not account for tuberculosis, which is endemic in Asia and can mimic malignancy. Non-surgical lung biopsy remains useful in minimising unnecessary thoracotomy.
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Neoplasias Pulmonares , Hemangioma Esclerosante Pulmonar , Nódulo Pulmonar Solitário , Tuberculose , Humanos , Feminino , Nódulo Pulmonar Solitário/diagnóstico por imagem , Nódulo Pulmonar Solitário/patologia , Pulmão/patologia , Hemangioma Esclerosante Pulmonar/diagnóstico por imagem , Hemangioma Esclerosante Pulmonar/cirurgia , Neoplasias Pulmonares/patologia , Tuberculose/patologiaRESUMO
Thoracic SMARCA4-deficient undifferentiated tumour (SMARCA4-UT) is an unusual and aggressive tumour. While there are approximately 100 cases of this tumour reported in the literature, there are very few detailed descriptions of its cytomorphologic characteristics, and only rare cases in which primary diagnosis was made on cytologic material. Herein we present a case with a detailed description of the appearance on three specimen types: transbronchial needle aspiration (TBNA) cytology, transbronchial needle biopsy (TBNB) and effusion cytology. Thoracic SMARCA4-UT is an important diagnosis to clinch in modern pathology because of its prognostic and therapeutic implications. We discuss an integrated approach to clinching the diagnosis with reference to clinical, radiographic, morphologic and immunohistochemical features. We also discuss possible differential diagnoses, and how they can be excluded. Cytologic and/or small biopsy diagnosis is valuable in these cases as these tumours are typically not amenable to surgical resection. With the correct diagnosis, the patient may instead be a candidate for immune checkpoint inhibitors or experimental therapy targeting SWI/SNF deficiency.
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Neoplasias Pulmonares , Neoplasias do Mediastino , Humanos , Neoplasias do Mediastino/diagnóstico , Neoplasias do Mediastino/patologia , Biópsia por Agulha Fina , Mediastino/patologia , Broncoscopia , Aspiração por Agulha Fina Guiada por Ultrassom Endoscópico , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/patologia , Linfonodos/patologia , DNA Helicases , Proteínas Nucleares , Fatores de TranscriçãoRESUMO
In 2006, humans with a congenital insensitivity to pain (CIP) were found to lack functional NaV 1.7 channels. In the subsequent 15 years there was a rush to develop selective inhibitors of NaV 1.7 channels with the goal of producing broadly effective analgesics without the problems of addiction and tolerance associated with opioids. Pharmacologically, this mission has been highly successful, leading to a number of highly potent and selective inhibitors of NaV 1.7 channels. However, there are very few examples where these inhibitors have yielded effective analgesia in preclinical pain models or human clinical trials. In this review, we summarise the role of the NaV 1.7 channel in nociception, its history as a therapeutic target and the quest to develop potent inhibitors of this channel. Finally, we discuss possible reasons why the pain-free state seen in humans with CIP has been so difficult to replicate pharmacologically. LINKED ARTICLES: This article is part of a themed issue on Structure Guided Pharmacology of Membrane Proteins (BJP 75th Anniversary). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.14/issuetoc.
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Analgésicos , Canal de Sódio Disparado por Voltagem NAV1.7/metabolismo , Dor , Analgésicos/farmacologia , Analgésicos/uso terapêutico , Analgésicos Opioides/uso terapêutico , Humanos , Dor/tratamento farmacológico , Dor/metabolismo , Manejo da DorRESUMO
α-Conotoxins that target muscle nicotinic acetylcholine receptors (nAChRs) commonly fall into two structural classes, frameworks I and II containing two and three disulfide bonds, respectively. Conotoxin SII is the sole member of the cysteine-rich framework II with ill-defined interactions at the nAChRs. Following directed synthesis of α-SII, NMR analysis revealed a well-defined structure containing a 310-helix frequently employed by framework I α-conotoxins; α-SII acted at the muscle nAChR with half-maximal inhibitory concentrations (IC50) of 120 nM (adult) and 370 nM (fetal) though weakly at neuronal nAChRs. Truncation of α-SII to a two disulfide bond amidated peptide with framework I disulfide connectivity led to similar activity. Surprisingly, the more constrained α-SII was less stable under mild reducing conditions and displayed a unique docking mode at the nAChR.
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Conotoxinas , Receptores Nicotínicos , Sequência de Aminoácidos , Conotoxinas/farmacologia , Cisteína , Dissulfetos , Músculos/metabolismo , Antagonistas Nicotínicos/farmacologia , Receptores Nicotínicos/metabolismoRESUMO
The sense of smell (olfaction) is one of the most important senses for animals including humans. Despite significant advances in the understanding mechanism of olfaction, currently, there are no objective non-invasive methods that can identify loss of smell. Covid-19-related loss of smell has highlighted the need to develop methods that can identify loss of olfaction. Voltage-gated sodium channel 1.7 (NaV1.7) plays a critical role in olfaction by aiding the signal propagation to the olfactory bulb. We have identified several conditions such as chronic inflammation and viral infections such as Covid-19 that lead to loss of smell correlate with downregulation of NaV1.7 expression at transcript and protein levels in the olfactory epithelium. Leveraging this knowledge, we have developed a novel fluorescent probe Tsp1a-IR800 that targets NaV1.7. Using fluorescence imaging we can objectively measure the loss of sense of smell in live animals non-invasively. We also demonstrate that our non-invasive method is semiquantitative because the loss of fluorescence intensity correlates with the level of smell loss. Our results indicate, that our probe Tsp1a-IR800, can objectively diagnose anosmia in animal and human subjects using infrared fluorescence. We believe this method to non-invasively diagnose loss of smell objectively is a significant advancement in relation to current methods that rely on highly subjective behavioral studies and can aid in studying olfaction loss and the development of therapeutic interventions.
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X-linked hypophosphatemia (XLH) is the most prevalent form of hereditary hypophosphatemic rickets associated with phosphate wasting. However, its diagnosis is often missed, resulting in patients presenting late in the course of the disease when complications such as tertiary hyperparathyroidism and renal failure have already set in. Phosphate and calcitriol replacement, both of which have undesirable consequences of their own, have historically been the main stay of therapy. We describe the case of a 57-year-old gentleman with tertiary hyperparathyroidism, who was mislabelled as having achondroplasia for many years before we made a diagnosis of XLH in him. His XLH was found to be due to a hereto unreported deletion of entire exon 14 with partial deletions of introns 13 and 14 of the PHEX gene. Perioperative management in him was fraught with surgical and medical difficulties including an operation that was technically complicated due to his multiple anatomical deformities. Our case also highlights the critical importance of timely recognition and accurate diagnosis of XLH, as well as the long-term multidisciplinary management that is needed for this disorder.
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The human nociceptor-specific voltage-gated sodium channel 1.7 (hNaV1.7) is critical for sensing various types of somatic pain, but it appears not to play a primary role in acute visceral pain. However, its role in chronic visceral pain remains to be determined. We used assay-guided fractionation to isolate a novel hNaV1.7 inhibitor, Tsp1a, from tarantula venom. Tsp1a is 28-residue peptide that potently inhibits hNaV1.7 (IC50 = 10 nM), with greater than 100-fold selectivity over hNaV1.3-hNaV1.6, 45-fold selectivity over hNaV1.1, and 24-fold selectivity over hNaV1.2. Tsp1a is a gating modifier that inhibits NaV1.7 by inducing a hyperpolarizing shift in the voltage-dependence of channel inactivation and slowing recovery from fast inactivation. NMR studies revealed that Tsp1a adopts a classical knottin fold, and like many knottin peptides, it is exceptionally stable in human serum. Remarkably, intracolonic administration of Tsp1a completely reversed chronic visceral hypersensitivity in a mouse model of irritable bowel syndrome. The ability of Tsp1a to reduce visceral hypersensitivity in a model of irritable bowel syndrome suggests that pharmacological inhibition of hNaV1.7 at peripheral sensory nerve endings might be a viable approach for eliciting analgesia in patients suffering from chronic visceral pain.
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Epilepsy is characterised by spontaneous recurrent seizures that are caused by an imbalance between neuronal excitability and inhibition. Since ion channels play fundamental roles in the generation and propagation of action potentials as well as neurotransmitter release at a subset of excitatory and inhibitory synapses, their dysfunction has been linked to a wide variety of epilepsies. Indeed, these unique proteins are the major biological targets for antiepileptic drugs. Selective targeting of a specific ion channel subtype remains challenging for small molecules, due to the high level of homology among members of the same channel family. As a consequence, there is a growing trend to target ion channels with biologics. Venoms are the best known natural source of ion channel modulators, and venom peptides are increasingly recognised as potential therapeutics due to their high selectivity and potency gained through millions of years of evolutionary selection pressure. Here we describe the major ion channel families involved in the pathogenesis of various types of epilepsy, including voltage-gated Na+, K+, Ca2+ channels, Cys-loop receptors, ionotropic glutamate receptors and P2X receptors, and currently available venom-derived peptides that target these channel proteins. Although only a small number of venom peptides have successfully progressed to the clinic, there is reason to be optimistic about their development as antiepileptic drugs, notwithstanding the challenges associated with development of any class of peptide drug.
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Anticonvulsivantes/farmacologia , Epilepsia/tratamento farmacológico , Ativação do Canal Iônico/efeitos dos fármacos , Canais Iônicos/antagonistas & inibidores , Peptídeos/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Anticonvulsivantes/química , Anticonvulsivantes/metabolismo , Epilepsia/metabolismo , Epilepsia/fisiopatologia , Humanos , Ativação do Canal Iônico/fisiologia , Canais Iônicos/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Conformação Proteica , Venenos de Aranha/metabolismoRESUMO
Dravet syndrome (DS) is a catastrophic epileptic encephalopathy characterised by childhood-onset polymorphic seizures, multiple neuropsychiatric comorbidities, and increased risk of sudden death. Heterozygous loss-of-function mutations in one allele of SCN1A, the gene encoding the voltage-gated sodium channel 1.1 (NaV1.1), lead to DS. NaV1.1 is primarily found in the axon initial segment of fast-spiking GABAergic inhibitory interneurons in the brain, and the principle mechanism proposed to underlie seizure genesis in DS is loss of inhibitory input due to dysfunctional firing of GABAergic interneurons. We hypothesised that DS symptoms could be ameliorated by a drug that activates the reduced population of functional NaV1.1 channels in DS interneurons. We recently identified two homologous disulfide-rich spider-venom peptides (Hm1a and Hm1b) that selectively potentiate NaV1.1, and showed that selective activation of NaV1.1 by Hm1a restores the function of inhibitory interneurons in a mouse model of DS. Here we produced recombinant Hm1b (rHm1b) using an E. coli periplasmic expression system, and examined its selectivity against a panel of human NaV subtypes using whole-cell patch-clamp recordings. rHm1b is a potent and highly selective agonist of NaV1.1 and NaV1.3 (EC50 ~12 nM for both). rHm1b is a gating modifier that shifts the voltage dependence of channel activation and inactivation to hyperpolarised and depolarised potentials respectively, presumably by interacting with the channel's voltage-sensor domains. Like Hm1a, the structure of rHm1b determined by using NMR revealed a classical inhibitor cystine knot (ICK) motif. However, we show that rHm1b is an order of magnitude more stable than Hm1a in human cerebrospinal fluid. Overall, our data suggest that rHm1b is an exciting lead for a precision therapeutic targeted against DS.