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1.
Neurobiol Dis ; 193: 106438, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38365045

RESUMO

Huntington's disease (HD) is a progressive neurodegenerative disease affecting motor and cognitive abilities. Multiple studies have found white matter anomalies in HD-affected humans and animal models of HD. The identification of sensitive white-matter-based biomarkers in HD animal models will be important in understanding disease mechanisms and testing the efficacy of therapeutic interventions. Here we investigated the progression of white matter deficits in the knock-in zQ175DN heterozygous (HET) mouse model of HD at 3, 6 and 11 months of age (M), reflecting different states of phenotypic progression. We compared findings from traditional diffusion tensor imaging (DTI) and advanced fixel-based analysis (FBA) diffusion metrics for their sensitivity in detecting white matter anomalies in the striatum, motor cortex, and segments of the corpus callosum. FBA metrics revealed progressive and widespread reductions of fiber cross-section and fiber density in myelinated bundles of HET mice. The corpus callosum genu was the most affected structure in HET mice at 6 and 11 M based on the DTI and FBA metrics, while the striatum showed the earliest progressive differences starting at 3 M based on the FBA metrics. Overall, FBA metrics detected earlier and more prominent alterations in myelinated fiber bundles compared to the DTI metrics. Luxol fast blue staining showed no loss in myelin density, indicating that diffusion anomalies could not be explained by myelin reduction but diffusion anomalies in HET mice were accompanied by increased levels of neurofilament light chain protein at 11 M. Altogether, our findings reveal progressive alterations in myelinated fiber bundles that can be measured using diffusion MRI, representing a candidate noninvasive imaging biomarker to study phenotype progression and the efficacy of therapeutic interventions in zQ175DN mice. Moreover, our study exposed higher sensitivity of FBA than DTI metrics, suggesting a potential benefit of adopting these advanced metrics in other contexts, including biomarker development in humans.


Assuntos
Doença de Huntington , Doenças Neurodegenerativas , Substância Branca , Humanos , Animais , Camundongos , Imagem de Tensor de Difusão , Doença de Huntington/diagnóstico por imagem , Doença de Huntington/genética , Imagem de Difusão por Ressonância Magnética , Substância Branca/diagnóstico por imagem , Modelos Animais de Doenças , Biomarcadores
2.
J Biomed Sci ; 31(1): 37, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38627751

RESUMO

BACKGROUND: Huntington's disease (HD) is marked by a CAG-repeat expansion in the huntingtin gene that causes neuronal dysfunction and loss, affecting mainly the striatum and the cortex. Alterations in the neurovascular coupling system have been shown to lead to dysregulated energy supply to brain regions in several neurological diseases, including HD, which could potentially trigger the process of neurodegeneration. In particular, it has been observed in cross-sectional human HD studies that vascular alterations are associated to impaired cerebral blood flow (CBF). To assess whether whole-brain changes in CBF are present and follow a pattern of progression, we investigated both resting-state brain perfusion and vascular reactivity longitudinally in the zQ175DN mouse model of HD. METHODS: Using pseudo-continuous arterial spin labelling (pCASL) MRI in the zQ175DN model of HD and age-matched wild-type (WT) mice, we assessed whole-brain, resting-state perfusion at 3, 6 and 9 and 13 months of age, and assessed hypercapnia-induced cerebrovascular reactivity (CVR), at 4.5, 6, 9 and 15 months of age. RESULTS: We found increased perfusion in cortical regions of zQ175DN HET mice at 3 months of age, and a reduction of this anomaly at 6 and 9 months, ages at which behavioural deficits have been reported. On the other hand, under hypercapnia, CBF was reduced in zQ175DN HET mice as compared to the WT: for multiple brain regions at 6 months of age, for only somatosensory and retrosplenial cortices at 9 months of age, and brain-wide by 15 months. CVR impairments in cortical regions, the thalamus and globus pallidus were observed in zQ175DN HET mice at 9 months, with whole brain reactivity diminished at 15 months of age. Interestingly, blood vessel density was increased in the motor cortex at 3 months, while average vessel length was reduced in the lateral portion of the caudate putamen at 6 months of age. CONCLUSION: Our findings reveal early cortical resting-state hyperperfusion and impaired CVR at ages that present motor anomalies in this HD model, suggesting that further characterization of brain perfusion alterations in animal models is warranted as a potential therapeutic target in HD.


Assuntos
Doença de Huntington , Humanos , Camundongos , Animais , Lactente , Doença de Huntington/genética , Estudos Transversais , Hipercapnia , Encéfalo , Modelos Animais de Doenças , Perfusão
3.
Neurobiol Dis ; 181: 106095, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36963694

RESUMO

Huntington's disease is an autosomal, dominantly inherited neurodegenerative disease caused by an expansion of the CAG repeats in exon 1 of the huntingtin gene. Neuronal degeneration and dysfunction that precedes regional atrophy result in the impairment of striatal and cortical circuits that affect the brain's large-scale network functionality. However, the evolution of these disease-driven, large-scale connectivity alterations is still poorly understood. Here we used resting-state fMRI to investigate functional connectivity changes in a mouse model of Huntington's disease in several relevant brain networks and how they are affected at different ages that follow a disease-like phenotypic progression. Towards this, we used the heterozygous (HET) form of the zQ175DN Huntington's disease mouse model that recapitulates aspects of human disease pathology. Seed- and Region-based analyses were performed at different ages, on 3-, 6-, 10-, and 12-month-old HET and age-matched wild-type mice. Our results demonstrate decreased connectivity starting at 6 months of age, most prominently in regions such as the retrosplenial and cingulate cortices, pertaining to the default mode-like network and auditory and visual cortices, part of the associative cortical network. At 12 months, we observe a shift towards decreased connectivity in regions such as the somatosensory cortices, pertaining to the lateral cortical network, and the caudate putamen, a constituent of the subcortical network. Moreover, we assessed the impact of distinct Huntington's Disease-like pathology of the zQ175DN HET mice on age-dependent connectivity between different brain regions and networks where we demonstrate that connectivity strength follows a non-linear, inverted U-shape pattern, a well-known phenomenon of development and normal aging. Conversely, the neuropathologically driven alteration of connectivity, especially in the default mode and associative cortical networks, showed diminished age-dependent evolution of functional connectivity. These findings reveal that in this Huntington's disease model, altered connectivity starts with cortical network aberrations which precede striatal connectivity changes, that appear only at a later age. Taken together, these results suggest that the age-dependent cortical network dysfunction seen in rodents could represent a relevant pathological process in Huntington's disease progression.


Assuntos
Doença de Huntington , Doenças Neurodegenerativas , Humanos , Camundongos , Animais , Lactente , Imageamento por Ressonância Magnética/métodos , Doença de Huntington/diagnóstico por imagem , Doença de Huntington/genética , Doença de Huntington/patologia , Doenças Neurodegenerativas/patologia , Encéfalo/patologia , Mapeamento Encefálico , Modelos Animais de Doenças
4.
Eur J Nucl Med Mol Imaging ; 49(4): 1166-1175, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34651228

RESUMO

PURPOSE: As several therapies aimed at lowering mutant huntingtin (mHTT) brain levels in Huntington's disease (HD) are currently being investigated, noninvasive positron emission tomography (PET) imaging of mHTT could be utilized to directly evaluate therapeutic efficacy and monitor disease progression. Here we characterized and longitudinally assessed the novel radioligand [11C]CHDI-626 for mHTT PET imaging in the zQ175DN mouse model of HD. METHODS: After evaluating radiometabolites and radioligand kinetics, we conducted longitudinal dynamic PET imaging at 3, 6, 9, and 13 months of age (M) in wild-type (WT, n = 17) and heterozygous (HET, n = 23) zQ175DN mice. Statistical analysis was performed to evaluate temporal and genotypic differences. Cross-sectional cohorts at each longitudinal time point were included for post-mortem [3H]CHDI-626 autoradiography. RESULTS: Despite fast metabolism and kinetics, the radioligand was suitable for PET imaging of mHTT. Longitudinal quantification could discriminate between genotypes already at premanifest stage (3 M), showing an age-associated increase in signal in HET mice in parallel with mHTT aggregate load progression, as supported by the post-mortem [3H]CHDI-626 autoradiography. CONCLUSION: With clinical evaluation underway, [11C]CHDI-626 PET imaging appears to be a suitable preclinical candidate marker to monitor natural HD progression and for the evaluation of mHTT-lowering therapies.


Assuntos
Doença de Huntington , Animais , Radioisótopos de Carbono , Estudos Transversais , Modelos Animais de Doenças , Humanos , Doença de Huntington/metabolismo , Camundongos , Tomografia por Emissão de Pósitrons/métodos
5.
Eur J Nucl Med Mol Imaging ; 50(1): 48-60, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36001116

RESUMO

PURPOSE: Huntington's disease is caused by a trinucleotide expansion in the HTT gene, which leads to aggregation of mutant huntingtin (mHTT) protein in the brain and neurotoxicity. Direct in vivo measurement of mHTT aggregates in human brain parenchyma is not yet possible. In this first-in-human study, we investigated biodistribution and dosimetry in healthy volunteers of [11C]CHDI-00485180-R ([11C]CHDI-180R) and [11C]CHDI-00485626 ([11C]CHDI-626), two tracers designed for PET imaging of aggregated mHTT in the brain that have been validated in preclinical models. METHODS: Biodistribution and radiation dosimetry studies were performed in 3 healthy volunteers (age 25.7 ± 0.5 years; 2 F) for [11C]CHDI-180R and in 3 healthy volunteers (age 35.3 ± 6.8 years; 2 F) for [11C]CHDI-626 using sequential whole-body PET-CT. Source organs were delineated in 3D using combined PET and CT data. Individual organ doses and effective doses were determined using OLINDA 2.1. RESULTS: There were no clinically relevant adverse events. The mean effective dose (ED) for [11C]CHDI-180R was 4.58 ± 0.65 µSv/MBq, with highest absorbed doses for liver (16.9 µGy/MBq), heart wall (15.9 µGy/MBq) and small intestine (15.8 µGy/MBq). Mean ED for [11C]CHDI-626 was 5.09 ± 0.06 µSv/MBq with the highest absorbed doses for the gallbladder (26.5 µGy/MBq), small intestine (20.4 µGy/MBq) and liver (19.6 µGy/MBq). Decay-corrected brain uptake curves showed promising kinetics for [11C]CHDI-180R, but for [11C]CHDI-626 an increasing signal over time was found, probably due to accumulation of a brain-penetrant metabolite. CONCLUSION: [11C]CHDI-180R and [11C]CHDI-626 are safe for in vivo PET imaging in humans. The estimated radiation burden is in line with most 11C-ligands. While [11C]CHDI-180R has promising kinetic properties in the brain, [11C]CHDI-626 is not suitable for human in vivo mHTT PET due to the possibility of a radiometabolite accumulating in brain parenchyma. TRIAL REGISTRATION: EudraCT number 2020-002129-27. CLINICALTRIALS: gov NCT05224115 (retrospectively registered).


Assuntos
Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Radiometria , Humanos , Adulto , Voluntários Saudáveis , Distribuição Tecidual , Tomografia por Emissão de Pósitrons/métodos
6.
Int J Mol Sci ; 23(14)2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35887162

RESUMO

While blood-brain barrier (BBB) dysfunction has been described in neurological disorders, including Huntington's disease (HD), it is not known if endothelial cells themselves are functionally compromised when promoting BBB dysfunction. Furthermore, the underlying mechanisms of BBB dysfunction remain elusive given the limitations with mouse models and post mortem tissue to identify primary deficits. We established models of BBB and undertook a transcriptome and functional analysis of human induced pluripotent stem cell (iPSC)-derived brain-like microvascular endothelial cells (iBMEC) from HD patients or unaffected controls. We demonstrated that HD-iBMECs have abnormalities in barrier properties, as well as in specific BBB functions such as receptor-mediated transcytosis.


Assuntos
Doença de Huntington , Células-Tronco Pluripotentes Induzidas , Animais , Barreira Hematoencefálica/fisiologia , Diferenciação Celular , Células Endoteliais/fisiologia , Humanos , Células-Tronco Pluripotentes Induzidas/fisiologia , Camundongos
7.
J Immunol ; 203(4): 899-910, 2019 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-31285277

RESUMO

The kynurenine pathway (KP) is a key regulator of many important physiological processes and plays a harmful role in cancer, many neurologic conditions, and chronic viral infections. In HIV infection, KP activity is consistently associated with reduced CD4 T cell counts and elevated levels of T cell activation and viral load; it also independently predicts mortality and morbidity from non-AIDS events. Kynurenine 3-monooxygenase (KMO) is a therapeutically important target in the KP. Using the nonhuman primate model of SIV infection in rhesus macaques, we investigated whether KMO inhibition could slow the course of disease progression. We used a KMO inhibitor, CHDI-340246, to perturb the KP during early acute infection and followed the animals for 1 y to assess clinical outcomes and immune phenotype and function during pre-combination antiretroviral therapy acute infection and combination antiretroviral therapy-treated chronic infection. Inhibition of KMO in acute SIV infection disrupted the KP and prevented SIV-induced increases in downstream metabolites, improving clinical outcome as measured by both increased CD4+ T cell counts and body weight. KMO inhibition increased naive T cell frequency and lowered PD-1 expression in naive and memory T cell subsets. Importantly, early PD-1 expression during acute SIV infection predicted clinical outcomes of body weight and CD4+ T cell counts. Our data indicate that KMO inhibition in early acute SIV infection provides clinical benefit and suggest a rationale for testing KMO inhibition as an adjunctive treatment in SIV/HIV infection to slow the progression of the disease and improve immune reconstitution.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Quinurenina 3-Mono-Oxigenase/antagonistas & inibidores , Receptor de Morte Celular Programada 1/biossíntese , Pirimidinas/farmacologia , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Animais , Antirretrovirais/farmacologia , Peso Corporal/efeitos dos fármacos , Linfócitos T CD4-Positivos/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Macaca mulatta , Receptor de Morte Celular Programada 1/efeitos dos fármacos , Síndrome de Imunodeficiência Adquirida dos Símios/metabolismo
8.
Xenobiotica ; 51(10): 1155-1180, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34496722

RESUMO

The disposition of a novel kynurenine monooxygenase inhibitor, CHDI-340246, was investigated in vitro and in animals.In vitro, there was minimal metabolic turnover of CHDI-340246 in all species. The protein binding was higher in human plasma (99.7%) relative to other species.In all species, blood clearance was low (<20% of liver blood flow) and volume of distribution was small (<0.5 L/kg). The terminal half-life was longer in monkeys (9 hr) than in mice, rats, or dogs (1-2 hr). CHDI-340246 was orally bioavailable (>60%) in all species.In rats, [14C]CHDI-340246 showed wide distribution of radioactivity in all tissues except brain and testes. In rats, the parent drug was the major circulating moiety with minor amounts of a sulphate conjugate of an O-dealkylated metabolite. The elimination occurred via the urinary route and to a lesser extent by biliary route, but mostly as metabolites. In cynomolgus monkeys, the parent drug predominated in plasma with only trace amounts of metabolites detected.Acyl glucuronide conjugate of CHDI-340246 was not detected in plasma of rats or monkeys.Overall, the ADME profile of CHDI-340246 was favourable in rats and monkeys for potential evaluation of KMO inhibition in humans.


Assuntos
Cinurenina , Pirimidinas , Animais , Animais de Laboratório , Cães , Camundongos , Oxigenases de Função Mista , Ratos , Especificidade da Espécie
9.
Hum Mol Genet ; 27(13): 2330-2343, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29912367

RESUMO

The N-terminal fragments of mutant huntingtin (mHTT) misfold and assemble into oligomers, which ultimately bundle into insoluble fibrils. Conformations unique to various assemblies of mHTT remain unknown. Knowledge on the half-life of various multimeric structures of mHTT is also scarce. Using a panel of four new antibodies named PHP1-4, we have identified new conformations in monomers and assembled structures of mHTT. PHP1 and PHP2 bind to epitopes within the proline-rich domain (PRD), whereas PHP3 and PHP4 interact with motifs formed at the junction of polyglutamine (polyQ) and polyproline (polyP) repeats of HTT. The PHP1- and PHP2-reactive epitopes are exposed in fibrils of mHTT exon1 (mHTTx1) generated from recombinant proteins and mHTT assemblies, which progressively accumulate in the nuclei, cell bodies and neuropils in the brains of HD mouse models. Notably, electron microscopic examination of brain sections of HD mice revealed that PHP1- and PHP2-reactive mHTT assemblies are present in myelin sheath and in vesicle-like structures. Moreover, PHP1 and PHP2 antibodies block seeding and subsequent fibril assembly of mHTTx1 in vitro and in a cell culture model of HD. PHP3 and PHP4 bind to epitopes in full-length and N-terminal fragments of monomeric mHTT and binding diminishes as the mHTTx1 assembles into fibrils. Interestingly, PHP3 and PHP4 also prevent the aggregation of mHTTx1 in vitro highlighting a regulatory function for the polyQ-polyP motifs. These newly detected conformations may affect fibril assembly, stability and intercellular transport of mHTT.


Assuntos
Proteína Huntingtina , Motivos de Aminoácidos , Animais , Humanos , Proteína Huntingtina/química , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Camundongos , Camundongos Transgênicos , Agregados Proteicos , Domínios Proteicos
10.
Bioorg Med Chem ; 28(21): 115738, 2020 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-33065433

RESUMO

Inhibition of KEAP1-NRF2 protein-protein interaction is considered a promising strategy to selectively and effectively activate NRF2, a transcription factor which is involved in several pathologies such as Huntington's disease (HD). A library of linear peptides based on the NRF2-binding motifs was generated on the nonapeptide lead Ac-LDEETGEFL-NH2 spanning residues 76-84 of the Neh2 domain of NRF2 with the aim to replace E78, E79 and E82 with non-acidic amino acids. A deeper understanding of the features and accessibility of the T80 subpocket was also targeted by structure-based design. Approaches to improve cell permeability were investigated using both different classes of cyclic peptides and conjugation to cell-penetrating peptides. This insight will guide future design of macrocycles, peptido-mimetics and, most importantly, small neutral brain-penetrating molecules to evaluate whether NRF2 activators have utility in HD.


Assuntos
Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Peptídeos Cíclicos/química , Peptídeos/química , Sequência de Aminoácidos , Sítios de Ligação , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular/efeitos dos fármacos , Desenho de Fármacos , Humanos , Proteína 1 Associada a ECH Semelhante a Kelch/antagonistas & inibidores , Simulação de Dinâmica Molecular , Fator 2 Relacionado a NF-E2/antagonistas & inibidores , Peptídeos/metabolismo , Peptídeos/farmacologia , Peptídeos Cíclicos/metabolismo , Peptídeos Cíclicos/farmacologia , Ligação Proteica , Relação Estrutura-Atividade
11.
Mol Pharm ; 16(5): 2069-2082, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-30916978

RESUMO

Huntington's disease (HD) is a neurodegenerative disease caused by polyglutamine expansion in the huntingtin protein. For drug candidates targeting HD, the ability to cross the blood-brain barrier (BBB) and reach the site of action in the central nervous system (CNS) is crucial for achieving pharmacological activity. To assess the permeability of selected compounds across the BBB, we utilized a two-dimensional model composed of primary porcine brain endothelial cells and rat astrocytes. Our objective was to use this in vitro model to rank and prioritize compounds for in vivo pharmacokinetic and brain penetration studies. The model was first characterized using a set of validation markers chosen based on their functional importance at the BBB. It was shown to fulfill the major BBB characteristics, including functional tight junctions, high transendothelial electrical resistance, expression, and activity of influx and efflux transporters. The in vitro permeability of 54 structurally diverse known compounds was determined and shown to have a good correlation with the in situ brain perfusion data in rodents. We used this model to investigate the BBB permeability of a series of new HD compounds from different chemical classes, and we found a good correlation with in vivo brain permeation, demonstrating the usefulness of the in vitro model for optimizing CNS drug properties and for guiding the selection of lead compounds in a drug discovery setting.


Assuntos
Barreira Hematoencefálica/metabolismo , Fármacos do Sistema Nervoso Central/uso terapêutico , Descoberta de Drogas/métodos , Doença de Huntington/tratamento farmacológico , Modelos Biológicos , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Astrócitos/metabolismo , Permeabilidade Capilar/fisiologia , Células Cultivadas , Córtex Cerebral/citologia , Técnicas de Cocultura , Impedância Elétrica , Células Endoteliais/metabolismo , Permeabilidade , Ratos , Ratos Sprague-Dawley , Proteínas Carreadoras de Solutos/metabolismo , Suínos , Junções Íntimas/metabolismo
12.
Bioorg Med Chem Lett ; 29(1): 83-88, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30463802

RESUMO

We have identified a potent, cell permeable and CNS penetrant class IIa histone deacetylase (HDAC) inhibitor 22, with >500-fold selectivity over class I HDACs (1,2,3) and ∼150-fold selectivity over HDAC8 and the class IIb HDAC6 isoform. Dose escalation pharmacokinetic analysis demonstrated that upon oral administration, compound 22 can reach exposure levels in mouse plasma, muscle and brain in excess of cellular class IIa HDAC IC50 levels for ∼8 h. Given the interest in aberrant class IIa HDAC function for a number of neurodegenerative, neuromuscular, cardiac and oncology indications, compound 22 (also known as CHDI-390576) provides a selective and potent compound to query the role of class IIa HDAC biology, and the impact of class IIa catalytic site occupancy in vitro and in vivo.


Assuntos
Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/metabolismo , Ácidos Hidroxâmicos/farmacologia , Animais , Relação Dose-Resposta a Droga , Inibidores de Histona Desacetilases/síntese química , Inibidores de Histona Desacetilases/química , Humanos , Ácidos Hidroxâmicos/síntese química , Ácidos Hidroxâmicos/química , Camundongos , Estrutura Molecular , Relação Estrutura-Atividade
13.
Arch Biochem Biophys ; 631: 31-41, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28801166

RESUMO

Mechanisms that activate innate antioxidant responses, as a way to mitigate oxidative stress at the site of action, hold much therapeutic potential in diseases, such as Parkinson's disease, Alzheimer's disease and Huntington's disease, where the use of antioxidants as monotherapy has not yielded positive results. The nuclear factor NRF2 is a transcription factor whose activity upregulates the expression of cell detoxifying enzymes in response to oxidative stress. NRF2 levels are modulated by KEAP1, a sensor of oxidative stress. KEAP1 binds NRF2 and facilitates its ubiquitination and subsequent degradation. Recently, compounds that reversibly disrupt the NRF2-KEAP1 interaction have been described, opening the field to a new era of safer NRF2 activators. This paper describes a set of new, robust and informative biochemical assays that enable the selection and optimization of non-covalent KEAP1 binders. These include a time-resolved fluorescence resonance energy transfer (TR-FRET) primary assay with high modularity and robustness, a surface plasmon resonance (SPR) based KEAP1 direct binding assay that enables the quantification and analysis of full kinetic binding parameters and finally a 1H-15N heteronuclear single quantum coherence (HSQC) NMR assay suited to study the interaction surface of KEAP1 with residue-specific information to validate the interaction of ligands in the KEAP1 binding site.


Assuntos
Antioxidantes/farmacologia , Descoberta de Drogas/métodos , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator 2 Relacionado a NF-E2/agonistas , Fator 2 Relacionado a NF-E2/metabolismo , Mapas de Interação de Proteínas/efeitos dos fármacos , Sequência de Aminoácidos , Antioxidantes/química , Sítios de Ligação , Transferência Ressonante de Energia de Fluorescência/métodos , Humanos , Repetição Kelch/efeitos dos fármacos , Proteína 1 Associada a ECH Semelhante a Kelch/química , Ligantes , Espectroscopia de Ressonância Magnética/métodos , Modelos Moleculares , Estresse Oxidativo/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia , Ressonância de Plasmônio de Superfície/métodos
15.
Mov Disord ; 29(11): 1397-403, 2014 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-25155258

RESUMO

Unraveling the pathophysiology and testing candidate therapeutics in neurodegenerative disorders is, necessarily, highly dependent on model systems. Because Huntington's disease (HD) is caused by a single (expanded CAG tract) mutation in the huntingtin (HTT) gene, a richness of model systems, particularly mice, have been engineered to both dissect disease mechanisms and test potential therapeutics. Even so, as with other neurodegenerative diseases, very little success has been achieved in translating HD mouse model drug testing results to the clinic. Because of the considerable costs-human, opportunity, and financial-there is a pressing need to improve the use of existing HD models and also to develop models in higher species beyond rodent, such as sheep, minipig, and nonhuman primate, to bridge the translational gap from preclinical to clinical testing of candidate therapeutics.


Assuntos
Modelos Animais de Doenças , Doença de Huntington/terapia , Pesquisa Translacional Biomédica/métodos , Animais , Humanos , Proteína Huntingtina , Doença de Huntington/genética , Proteínas do Tecido Nervoso/genética , Especificidade da Espécie , Repetições de Trinucleotídeos/genética
16.
Handb Clin Neurol ; 193: 171-184, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36803810

RESUMO

Huntington disease is a highly disabling neurodegenerative disease characterized by psychiatric, cognitive, and motor deficits. The causal genetic mutation in huntingtin (Htt, also known as IT15), located on chromosome 4p16.3, leads to an expansion of a triplet coding for polyglutamine. The expansion is invariably associated with the disease when >39 repeats. Htt encodes for the protein huntingtin (HTT), which carries out many essential biological functions in the cell, in particular in the nervous system. The precise mechanism of toxicity is not known. Based on a one-gene-one-disease framework, the prevailing hypothesis ascribes toxicity to the universal aggregation of HTT. However, the aggregation process into mutant huntingtin (mHTT) is associated with a reduction of the levels of wild-type HTT. A loss of wild-type HTT may plausibly be pathogenic, contributing to the disease onset and progressive neurodegeneration. Moreover, many other biological pathways are altered in Huntington disease, such as in the autophagic system, mitochondria, and essential proteins beyond HTT, potentially explaining biological and clinical differences among affected individuals. As one gene does not mean one disease, future efforts at identifying specific Huntington subtypes are important to design biologically tailored therapeutic approaches that correct the corresponding biological pathways-rather than continuing to exclusively target the common denominator of HTT aggregation for elimination.


Assuntos
Doença de Huntington , Doenças Neurodegenerativas , Humanos , Doença de Huntington/metabolismo , Mutação
17.
J Nucl Med ; 64(10): 1581-1587, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37591545

RESUMO

Huntington disease (HD) is a neurodegenerative disorder caused by an expanded polyglutamine (CAG) trinucleotide expansion in the huntingtin (HTT) gene that encodes the mutant huntingtin protein (mHTT). Visualization and quantification of cerebral mHTT will provide a proxy for target engagement and a means to evaluate therapeutic interventions aimed at lowering mHTT in the brain. Here, we validated the novel radioligand 11C-labeled 6-(5-((5-methoxypyridin-2-yl)methoxy)benzo[d]oxazol-2-yl)-2-methylpyridazin-3(2H)-one (11C-CHDI-180R) using PET imaging to quantify cerebral mHTT aggregates in a macaque model of HD. Methods: Rhesus macaques received MRI-guided intrastriatal delivery of a mixture of AAV2 and AAV2.retro viral vectors expressing an HTT fragment bearing 85 CAG repeats (85Q, n = 5), a control HTT fragment bearing 10 CAG repeats (10Q, n = 4), or vector diluent only (phosphate-buffered saline, n = 5). Thirty months after surgery, 90-min dynamic PET/CT imaging was used to investigate 11C-CHDI-180R brain kinetics, along with serial blood sampling to measure input function and stability of the radioligand. The total volume of distribution was calculated using a 2-tissue-compartment model as well as Logan graphical analysis for regional quantification. Immunostaining for mHTT was performed to corroborate the in vivo findings. Results: 11C-CHDI-180R displayed good metabolic stability (51.4% ± 4.0% parent in plasma at 60 min after injection). Regional time-activity curves displayed rapid uptake and reversible binding, which were described by a 2-tissue-compartment model. Logan graphical analysis was associated with the 2-tissue-compartment model (r 2 = 0.96, P < 0.0001) and used to generate parametric volume of distribution maps. Compared with controls, animals administered the 85Q fragment exhibited significantly increased 11C-CHDI-180R binding in several cortical and subcortical brain regions (group effect, P < 0.0001). No difference in 11C-CHDI-180R binding was observed between buffer and 10Q animals. The presence of mHTT aggregates in the 85Q animals was confirmed histologically. Conclusion: We validated 11C-CHDI-180R as a radioligand to visualize and quantify mHTT aggregated species in a HD macaque model. These findings corroborate our previous work in rodent HD models and show that 11C-CHDI-180R is a promising tool to assess the mHTT aggregate load and the efficacy of therapeutic strategies.


Assuntos
Doença de Huntington , Animais , Doença de Huntington/metabolismo , Proteína Huntingtina/genética , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Macaca mulatta/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Tomografia por Emissão de Pósitrons , Modelos Animais de Doenças
18.
Sci Rep ; 13(1): 10194, 2023 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-37353500

RESUMO

Huntington's disease (HD) is a neurodegenerative disorder caused by expanded (≥ 40) glutamine-encoding CAG repeats in the huntingtin gene, which leads to dysfunction and death of predominantly striatal and cortical neurons. While the genetic profile and clinical signs and symptoms of the disease are better known, changes in the functional architecture of the brain, especially before the clinical expression becomes apparent, are not fully and consistently characterized. In this study, we sought to uncover functional changes in the brain in the heterozygous (HET) zQ175 delta-neo (DN) mouse model at 3, 6, and 10 months of age, using resting-state functional magnetic resonance imaging (RS-fMRI). This mouse model shows molecular, cellular and circuitry alterations that worsen through age. Motor function disturbances are manifested in this model at 6 and 10 months of age. Specifically, we investigated, longitudinally, changes in co-activation patterns (CAPs) that are the transient states of brain activity constituting the resting-state networks (RSNs). Most robust changes in the temporal properties of CAPs occurred at the 10-months time point; the durations of two anti-correlated CAPs, characterized by simultaneous co-activation of default-mode like network (DMLN) and co-deactivation of lateral-cortical network (LCN) and vice-versa, were reduced in the zQ175 DN HET animals compared to the wild-type mice. Changes in the spatial properties, measured in terms of activation levels of different brain regions, during CAPs were found at all three ages and became progressively more pronounced at 6-, and 10 months of age. We then assessed the cross-validated predictive power of CAP metrics to distinguish HET animals from controls. Spatial properties of CAPs performed significantly better than the chance level at all three ages with 80% classification accuracy at 6 and 10 months of age.


Assuntos
Doença de Huntington , Camundongos , Animais , Doença de Huntington/diagnóstico por imagem , Doença de Huntington/genética , Doença de Huntington/metabolismo , Encéfalo/metabolismo , Heterozigoto , Corpo Estriado/metabolismo , Neurônios/metabolismo , Modelos Animais de Doenças
19.
J Med Chem ; 66(1): 641-656, 2023 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-36548390

RESUMO

Therapeutic interventions are being developed for Huntington's disease (HD), a hallmark of which is mutant huntingtin protein (mHTT) aggregates. Following the advancement to human testing of two [11C]-PET ligands for aggregated mHTT, attributes for further optimization were identified. We replaced the pyridazinone ring of CHDI-180 with a pyrimidine ring and minimized off-target binding using brain homogenate derived from Alzheimer's disease patients. The major in vivo metabolic pathway via aldehyde oxidase was blocked with a 2-methyl group on the pyrimidine ring. A strategically placed ring-nitrogen on the benzoxazole core ensured high free fraction in the brain without introducing efflux. Replacing a methoxy pendant with a fluoro-ethoxy group and introducing deuterium atoms suppressed oxidative defluorination and accumulation of [18F]-signal in bones. The resulting PET ligand, CHDI-650, shows a rapid brain uptake and washout profile in non-human primates and is now being advanced to human testing.


Assuntos
Doença de Huntington , Tomografia por Emissão de Pósitrons , Animais , Humanos , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Ligantes , Tomografia por Emissão de Pósitrons/métodos , Doença de Huntington/diagnóstico por imagem , Doença de Huntington/tratamento farmacológico , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo
20.
J Med Chem ; 66(18): 13205-13246, 2023 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-37712656

RESUMO

Huntington's disease (HD) is caused by an expanded CAG trinucleotide repeat in exon 1 of the huntingtin (HTT) gene. We report the design of a series of HTT pre-mRNA splicing modulators that lower huntingtin (HTT) protein, including the toxic mutant huntingtin (mHTT), by promoting insertion of a pseudoexon containing a premature termination codon at the exon 49-50 junction. The resulting transcript undergoes nonsense-mediated decay, leading to a reduction of HTT mRNA transcripts and protein levels. The starting benzamide core was modified to pyrazine amide and further optimized to give a potent, CNS-penetrant, and orally bioavailable HTT-splicing modulator 27. This compound reduced canonical splicing of the HTT RNA exon 49-50 and demonstrated significant HTT-lowering in both human HD stem cells and mouse BACHD models. Compound 27 is a structurally diverse HTT-splicing modulator that may help understand the mechanism of adverse effects such as peripheral neuropathy associated with branaplam.

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