Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.976
Filtrar
1.
J Toxicol Sci ; 45(9): 569-579, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32879256

RESUMO

Indoxyl, a derivative of indole originating from tryptophan, may undergo phase-II sulfate-conjugation pathway, thereby forming indoxyl sulfate (IS) in vivo. We previously reported that IS, a well-known uremic toxin, can increase the intracellular oxidation level and decrease the phagocytic activity in a differentiated HL-60 human macrophage cell model. Using the same cell model, the current study aimed to investigate whether indole and indoxyl (the metabolic precursors of indoxyl and IS, respectively) may cause macrophage immune dysfunction. Results obtained indicated that intracellular oxidation level and cytotoxicity markedly increased upon treatment with indole and indoxyl, in comparison with IS. Incubation of the cells with indole and indoxyl also resulted in attenuated phagocytic activity. Human serum albumin (HSA)-binding assay confirmed that tryptophan and IS, but not indole and indoxyl, could selectively bind to the site II in HSA. Collectively, the results indicated that indole and indoxyl may strongly down-regulate the phagocytic immune function of macrophages, whereas IS, formed upon sulfate conjugation of indoxyl, may exhibit enhanced HSA-binding capability, thereby reducing the adverse effects of indoxyl.


Assuntos
Indóis/efeitos adversos , Macrófagos/imunologia , Macrófagos/metabolismo , Oxirredução/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Fagocitose/imunologia , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Células HL-60 , Humanos , Indicã/metabolismo , Macrófagos/efeitos dos fármacos , Ligação Proteica , Albumina Sérica/metabolismo , Triptofano/metabolismo
2.
Nat Commun ; 11(1): 4880, 2020 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-32978375

RESUMO

Through advanced mechanistic modeling and the generation of large high-quality datasets, machine learning is becoming an integral part of understanding and engineering living systems. Here we show that mechanistic and machine learning models can be combined to enable accurate genotype-to-phenotype predictions. We use a genome-scale model to pinpoint engineering targets, efficient library construction of metabolic pathway designs, and high-throughput biosensor-enabled screening for training diverse machine learning algorithms. From a single data-generation cycle, this enables successful forward engineering of complex aromatic amino acid metabolism in yeast, with the best machine learning-guided design recommendations improving tryptophan titer and productivity by up to 74 and 43%, respectively, compared to the best designs used for algorithm training. Thus, this study highlights the power of combining mechanistic and machine learning models to effectively direct metabolic engineering efforts.


Assuntos
Aprendizado de Máquina , Engenharia Metabólica/métodos , Saccharomyces cerevisiae/metabolismo , Triptofano/metabolismo , Algoritmos , Aminoácidos/metabolismo , Fenômenos Bioquímicos , Técnicas Biossensoriais , Genótipo , Redes e Vias Metabólicas , Modelos Biológicos , Fenótipo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento
3.
PLoS One ; 15(8): e0232643, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790737

RESUMO

Serotonin is a neurotransmitter synthesized by the amino acid tryptophan, that has the potential to impact the behaviour and activity of dogs. The objective of this study was to assess the effects of supplemental tryptophan and a 12-week incremental training regimen on the voluntary activity and behaviour of client-owned Siberian Huskies. Sixteen dogs were blocked for age, BW and sex and then randomly allocated to either the control or treatment group. Both groups were fed the same dry extruded diet; however, the treatment group were supplemented with tryptophan to achieve a tryptophan: large neutral amino acid ratio of 0.075:1. Once a week, a 5-minute video recording was taken immediately pre- and post- exercise to evaluate dogs' behaviours. Activity monitors were used to record voluntary activity on both training and rest days. Linear regression analysis was used to assess the relationship between training week and time spent performing each behaviour. Additionally, a repeated measure mixed model was used to test differences between diet groups and training week for both behavioural and activity count data. The time spent performing agonistic behaviours prior to exercise was negatively associated with week for treatment dogs (ß = -0.32, 95% CI [-0.55, -0.10], P < 0.05) and no change was observed for control dogs (ß = -0.13, 95% CI [-0.41, 0.15], P > 0.10). Treatment did not have any effect on activity levels (P > 0.10). For all dogs, locomotive behaviours decreased prior to exercise as weeks progressed (P < 0.05), while run day voluntary activity depended on the distance run that day (P < 0.05). These data suggest that sled dogs experience an exercise-induced reduction in voluntary locomotion in response to both single bouts and repetitive bouts of exercise. Additionally, tryptophan supplementation may decrease agonistic behaviours, without having any effect on voluntary activity.


Assuntos
Suplementos Nutricionais , Cães/fisiologia , Condicionamento Físico Animal/métodos , Triptofano/administração & dosagem , Animais , Comportamento Animal/fisiologia , Cães/psicologia , Treino Aeróbico/métodos , Treino Aeróbico/veterinária , Feminino , Humanos , Modelos Lineares , Masculino , Atividade Motora/fisiologia , Condicionamento Físico Animal/fisiologia , Corrida/fisiologia , Serotonina/biossíntese , Serotonina/fisiologia , Esportes na Neve , Fatores de Tempo , Triptofano/metabolismo
4.
Nat Commun ; 11(1): 4316, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859932

RESUMO

Plants utilize a UV-B (280 to 315 nm) photoreceptor UVR8 (UV RESISTANCE LOCUS 8) to sense environmental UV levels and regulate gene expression to avoid harmful UV effects. Uniquely, UVR8 uses intrinsic tryptophan for UV-B perception with a homodimer structure containing 26 structural tryptophan residues. However, besides 8 tryptophans at the dimer interface to form two critical pyramid perception centers, the other 18 tryptophans' functional role is unknown. Here, using ultrafast fluorescence spectroscopy, computational methods and extensive mutations, we find that all 18 tryptophans form light-harvesting networks and funnel their excitation energy to the pyramid centers to enhance light-perception efficiency. We determine the timescales of all elementary tryptophan-to-tryptophan energy-transfer steps in picoseconds to nanoseconds, in excellent agreement with quantum computational calculations, and finally reveal a significant leap in light-perception quantum efficiency from 35% to 73%. This photoreceptor is the first system discovered so far, to be best of our knowledge, using natural amino-acid tryptophans to form networks for both light harvesting and light perception.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/metabolismo , Fotorreceptores de Plantas/química , Fotorreceptores de Plantas/metabolismo , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas Cromossômicas não Histona/genética , Transferência de Energia , Fluorescência , Cinética , Luz , Modelos Moleculares , Mutação , Conformação Proteica , Multimerização Proteica , Triptofano/metabolismo , Raios Ultravioleta
5.
Proc Natl Acad Sci U S A ; 117(32): 19376-19387, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32719140

RESUMO

Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, are associated with dysbiosis of the gut microbiome. Emerging evidence suggests that small-molecule metabolites derived from bacterial breakdown of a variety of dietary nutrients confer a wide array of host benefits, including amelioration of inflammation in IBDs. Yet, in many cases, the molecular pathways targeted by these molecules remain unknown. Here, we describe roles for three metabolites-indole-3-ethanol, indole-3-pyruvate, and indole-3-aldehyde-which are derived from gut bacterial metabolism of the essential amino acid tryptophan, in regulating intestinal barrier function. We determined that these metabolites protect against increased gut permeability associated with a mouse model of colitis by maintaining the integrity of the apical junctional complex and its associated actin regulatory proteins, including myosin IIA and ezrin, and that these effects are dependent on the aryl hydrocarbon receptor. Our studies provide a deeper understanding of how gut microbial metabolites affect host defense mechanisms and identify candidate pathways for prophylactic and therapeutic treatments for IBDs.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Microbioma Gastrointestinal/fisiologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Receptores de Hidrocarboneto Arílico/metabolismo , Triptofano/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Células CACO-2 , Colite Ulcerativa/dietoterapia , Colite Ulcerativa/microbiologia , Colite Ulcerativa/patologia , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Modelos Animais de Doenças , Humanos , Inflamação , Mucosa Intestinal/patologia , Camundongos , Camundongos Knockout , Miosina não Muscular Tipo IIA/metabolismo , Permeabilidade , Receptores de Hidrocarboneto Arílico/genética , Triptofano/administração & dosagem
6.
PLoS One ; 15(6): e0233979, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32492052

RESUMO

BACKGROUND: Exposure to maternal stress during pregnancy can have adverse effects on the fetus, which has potential long-term effects on offspring´s development and health. We investigated the kinetics and metabolism of the hormones and amino acids: cortisol, cortisone, tryptophan and serotonin in the term placenta in an ex vivo human placental perfusion model. The placentas used in the experiments were donated from families participating in the Maternal Stress and Placental Function project with a known maternal stress background. METHOD: Cortisol, cortisone, tryptophan and serotonin were added simultaneously to the maternal side in the 6 hour ex vivo term human recirculating placental perfusion model, in four experimental set-ups: without inhibitors, with carbenoxolone -that inhibits cortisol metabolism into cortisone, with fluoxetine that inhibits the serotonin transporter, and with PCPA that inhibits metabolism of tryptophan into serotonin. The concentration of cortisol and cortisone, and tryptophan and serotonin were quantified using UPLC and HPLC-MS respectively. RESULTS: Cortisol was rapidly metabolized into cortisone in the placenta, to a somewhat lesser degree when adding the inhibitor carbenoxolone, resulting in higher fetal exposure to cortisol. Serotonin was also rapidly metabolized in the placenta. When adding fluoxetine a peak of fetal serotonin levels was seen in the first hour of the perfusion. No effect was seen of the maternal stress levels on placental transport kinetics in this study. CONCLUSION: Inhibiting the metabolism of cortisol in the placenta increased fetal exposure to cortisol as expected. Unexpectedly we saw an increased fetal exposure to serotonin when inhibiting the serotonin transporter, which may be related to the increased serotonin concentration on the maternal side of the placenta. No effect on placental kinetics were evident on maternal stress levels during the pregnancy as the majority of participating mothers had normal stress levels.


Assuntos
Feto/metabolismo , Troca Materno-Fetal , Placenta/metabolismo , Estresse Psicológico/metabolismo , Adulto , Cortisona/metabolismo , Feminino , Humanos , Hidrocortisona/metabolismo , Perfusão , Gravidez , Serotonina/metabolismo , Triptofano/metabolismo
7.
Psychiatry Res ; 291: 113198, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32535509

RESUMO

An option currently being explored for the treatment of COVID-19 is the use of interferons (INFs), either alone or in combination with other antiviral agents. INFs are known to shift the metabolism of tryptophan (TRP) away from its role as a precursor of serotonin. For some patients, reduction in TRP levels may either expose an underlying vulnerability to depression or trigger a de novo episode of depression. This Commentary discusses the pathway involved and recommends in-hospital augmentation with foods or supplements that increase TRP levels for COVID-19 patients treated with INFs. Selective serotonin reuptake inhibitors may also be tried if the depressive symptomatology is not short-lived.


Assuntos
Betacoronavirus , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/psicologia , Depressão/metabolismo , Interferons/metabolismo , Pneumonia Viral/metabolismo , Pneumonia Viral/psicologia , Depressão/psicologia , Humanos , Pandemias , Serotonina/metabolismo , Triptofano/metabolismo
8.
JCI Insight ; 5(14)2020 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-32559180

RESUMO

BACKGROUNDReprogramming of host metabolism supports viral pathogenesis by fueling viral proliferation, by providing, for example, free amino acids and fatty acids as building blocks.METHODSTo investigate metabolic effects of SARS-CoV-2 infection, we evaluated serum metabolites of patients with COVID-19 (n = 33; diagnosed by nucleic acid testing), as compared with COVID-19-negative controls (n = 16).RESULTSTargeted and untargeted metabolomics analyses identified altered tryptophan metabolism into the kynurenine pathway, which regulates inflammation and immunity. Indeed, these changes in tryptophan metabolism correlated with interleukin-6 (IL-6) levels. Widespread dysregulation of nitrogen metabolism was also seen in infected patients, with altered levels of most amino acids, along with increased markers of oxidant stress (e.g., methionine sulfoxide, cystine), proteolysis, and renal dysfunction (e.g., creatine, creatinine, polyamines). Increased circulating levels of glucose and free fatty acids were also observed, consistent with altered carbon homeostasis. Interestingly, metabolite levels in these pathways correlated with clinical laboratory markers of inflammation (i.e., IL-6 and C-reactive protein) and renal function (i.e., blood urea nitrogen).CONCLUSIONIn conclusion, this initial observational study identified amino acid and fatty acid metabolism as correlates of COVID-19, providing mechanistic insights, potential markers of clinical severity, and potential therapeutic targets.FUNDINGBoettcher Foundation Webb-Waring Biomedical Research Award; National Institute of General and Medical Sciences, NIH; and National Heart, Lung, and Blood Institute, NIH.


Assuntos
Infecções por Coronavirus/metabolismo , Ácidos Graxos/metabolismo , Interleucina-6/metabolismo , Cinurenina/metabolismo , Estresse Oxidativo , Pneumonia Viral/metabolismo , Insuficiência Renal/metabolismo , Adulto , Idoso , Aminoácidos/metabolismo , Betacoronavirus , Glicemia/metabolismo , Estudos de Casos e Controles , Creatina/metabolismo , Creatinina/metabolismo , Cistina , Ácidos Graxos não Esterificados/metabolismo , Feminino , Humanos , Masculino , Metaboloma , Metabolômica , Metionina/análogos & derivados , Pessoa de Meia-Idade , Pandemias , Poliaminas/metabolismo , Proteólise , Triptofano/metabolismo
9.
Food Chem ; 331: 127192, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32569963

RESUMO

Melatonin and serotonin are bioactive compounds present in foods and beverages and related to neuroprotection and anti-angiogenesis, among other activities. They have been described in wines and the role of yeast in their formation is clear. Thus, this study evaluates the content of these bioactives and other related indolic compounds in beer. For this purpose, commercial beers were analyzed by a validated UHPLC-HRMS method and sample treatment optimized due to the low concentrations expected. Moreover, a wort was fermented with different commercial beer yeast (Abbaye, Diamond, SafAle, SafLager) in order to monitor the formation of these bioactives during the elaboration process. Results show that indolic compounds such as N-acetylserotonin and 3-indoleacetic acid are produced during the alcoholic fermentation of wort. Moreover, the occurrence of four indolic compounds (5-hydroxytryptophan, N-acetylserotonin, 3-indoleacetic acid, l-tryptophan ethyl ester) in commercial beers is reported for the first time.


Assuntos
Cerveja/análise , Cerveja/microbiologia , Indóis/metabolismo , Melatonina/metabolismo , Triptofano/metabolismo , Bebidas , Cromatografia Líquida de Alta Pressão/métodos , Fermentação , Análise de Alimentos/métodos , Armazenamento de Alimentos , Indóis/análise , Melatonina/análise , Saccharomyces cerevisiae/metabolismo , Serotonina/análogos & derivados , Temperatura , Triptofano/análogos & derivados
10.
Proc Natl Acad Sci U S A ; 117(22): 11916-11922, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32414932

RESUMO

Lytic polysaccharide monooxygenases (LPMOs) have been proposed to react with both [Formula: see text] and [Formula: see text] as cosubstrates. In this study, the [Formula: see text] reaction with reduced Hypocrea jecorina LPMO9A (CuI-HjLPMO9A) is demonstrated to be 1,000-fold faster than the [Formula: see text] reaction while producing the same oxidized oligosaccharide products. Analysis of the reactivity in the absence of polysaccharide substrate by stopped-flow absorption and rapid freeze-quench (RFQ) electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) yields two intermediates corresponding to neutral tyrosyl and tryptophanyl radicals that are formed along minor reaction pathways. The dominant reaction pathway is characterized by RFQ EPR and kinetic modeling to directly produce CuII-HjLPMO9A and indicates homolytic O-O cleavage. Both optical intermediates exhibit magnetic exchange coupling with the CuII sites reflecting facile electron transfer (ET) pathways, which may be protective against uncoupled turnover or provide an ET pathway to the active site with substrate bound. The reactivities of nonnative organic peroxide cosubstrates effectively exclude the possibility of a ping-pong mechanism.


Assuntos
Aminoácidos/metabolismo , Peróxido de Hidrogênio/metabolismo , Oxigenases de Função Mista/química , Polissacarídeos/metabolismo , Sítios de Ligação , Biocombustíveis , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Hypocrea/metabolismo , Cinética , Espectroscopia de Ressonância Magnética/métodos , Oxigenases de Função Mista/metabolismo , Oxirredução , Peróxidos/metabolismo , Triptofano/metabolismo , Tirosina/metabolismo
11.
Chemosphere ; 254: 126715, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334245

RESUMO

Perinatal exposure to bisphenol A (BPA) contributes to neurological disorders in offspring, but the underlying mechanisms are still poorly understood. The abnormal release of neuroactive metabolites in the tryptophan (TRP) and dopamine (DA) pathways is considered to be closely associated with some disorders. Thus, in this study, TRP and DA pathways in adult female mouse offspring were investigated when the pregnant mice were given either vehicle or BPA (2, 10, or 100 µg/kg/d) from day 6 of gestation until weaning. Then, the serum and brain samples of offspring were collected at 3, 6 and 9 months, and 12 neuroactive metabolites in the TRP and DA pathways were detected. The results showed that, in the TRP pathway, TRP levels decreased, whereas kynurenine (KYN) levels and TRP turnover increased in the brain. In the serum, TRP, KYN and 5-hydroxytryptamine (5-HT) levels decreased significantly. For the DA pathway, DA and DA metabolites, including 3,4-dihydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT) and homovanillic acid (HVA), reduced significantly in the brain and serum. DA turnover decreased dramatically in the brain but enhanced in the serum. The disturbance of these two metabolic pathways might be one of the potential mechanisms of BPA-induced neuropsychiatric disorders.


Assuntos
Compostos Benzidrílicos/toxicidade , Dopamina/metabolismo , Poluentes Ambientais/toxicidade , Neurotransmissores/metabolismo , Fenóis/toxicidade , Triptofano/metabolismo , Ácido 3,4-Di-Hidroxifenilacético , Animais , Encéfalo/metabolismo , Dopamina/análogos & derivados , Feminino , Masculino , Redes e Vias Metabólicas , Camundongos , Gravidez , Serotonina/metabolismo
12.
PLoS One ; 15(4): e0230813, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267860

RESUMO

Lung macrophages (LM) are in the first line of defense against inhaled pathogens and can undergo phenotypic polarization to the proinflammatory M1 after stimulation with Toll-like receptor agonists. The objective of the present work was to characterize the metabolic alterations occurring during the experimental M1 LM polarization. Human LM were obtained from resected lungs and cultured for 24 hrs in medium alone or with 10 ng.mL-1 lipopolysaccharide. Cells and culture supernatants were subjected to extraction for metabolomic analysis with high-resolution LC-MS (HILIC and reverse phase -RP- chromatography in both negative and positive ionization modes) and GC-MS. The data were analyzed with R and the Worklow4Metabolomics and MetaboAnalyst online infrastructures. A total of 8,741 and 4,356 features were detected in the intracellular and extracellular content, respectively, after the filtering steps. Pathway analysis showed involvement of arachidonic acid metabolism, tryptophan metabolism and Krebs cycle in the response of LM to LPS, which was confirmed by the specific quantitation of selected compounds. This refined analysis highlighted a regulation of the kynurenin pathway as well as the serotonin biosynthesis pathway, and an involvement of aspartate-arginosuccinate shunt in the malate production. Macrophages M1 polarization is accompanied by changes in the cell metabolome, with the differential expression of metabolites involved in the promotion and regulation of inflammation and antimicrobial activity. The analysis of this macrophage immunometabolome may be of interest for the understanding of the pathophysiology of lung inflammatory disesases.


Assuntos
Ácido Argininossuccínico/metabolismo , Ácido Aspártico/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos Alveolares/efeitos dos fármacos , Macrófagos Alveolares/metabolismo , Triptofano/metabolismo , Idoso , Células Cultivadas , Feminino , Humanos , Inflamação/metabolismo , Ativação de Macrófagos/efeitos dos fármacos , Ativação de Macrófagos/fisiologia , Masculino , Pessoa de Meia-Idade , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia
13.
J Headache Pain ; 21(1): 35, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32316909

RESUMO

BACKGROUND: The neurochemical background of the evolution of headache disorders, still remains partially undiscovered. Accordingly, our aim was to further explore the neurochemical profile of Complete Freund's adjuvant (CFA)-induced orofacial pain, involving finding the shift point regarding small molecule neurotransmitter concentrations changes vs. that of the previously characterized headache-related neuropeptides. The investigated neurotransmitters consisted of glutamate, γ-aminobutyric acid, noradrenalin and serotonin. Furthermore, in light of its influence on glutamatergic neurotransmission, we measured the level of kynurenic acid (KYNA) and its precursors in the kynurenine (KYN) pathway (KP) of tryptophan metabolism. METHODS: The effect of CFA was evaluated in male Sprague Dawley rats. Animals were injected with CFA (1 mg/ml, 50 µl/animal) into the right whisker pad. We applied high-performance liquid chromatography to determine the concentrations of the above-mentioned compounds from the trigeminal nucleus caudalis (TNC) and somatosensory cortex (ssCX) of rats. Furthermore, we measured some of these metabolites from the cerebrospinal fluid and plasma as well. Afterwards, we carried out permutation t-tests as post hoc analysis for pairwise comparison. RESULTS: Our results demonstrated that 24 h after CFA treatment, the level of glutamate, KYNA and that of its precursor, KYN was still elevated in the TNC, all diminishing by 48 h. In the ssCX, significant concentration increases of KYNA and serotonin were found. CONCLUSION: This is the first study assessing neurotransmitter changes in the TNC and ssCX following CFA treatment, confirming the dominant role of glutamate in early pain processing and a compensatory elevation of KYNA with anti-glutamatergic properties. Furthermore, the current findings draw attention to the limited time interval where medications can target the glutamatergic pathways.


Assuntos
Dor Facial/metabolismo , Ácido Glutâmico/metabolismo , Ácido Cinurênico/metabolismo , Norepinefrina/metabolismo , Serotonina/metabolismo , Triptofano/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Dor Facial/induzido quimicamente , Adjuvante de Freund , Masculino , Ratos , Ratos Sprague-Dawley , Núcleo Inferior Caudal do Nervo Trigêmeo/metabolismo , Vibrissas/efeitos dos fármacos
14.
Adv Clin Chem ; 95: 165-218, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32122523

RESUMO

Tryptophan (TRP), an essential amino acid in mammals, is involved in several physiological processes including neuronal function, immunity, and gut homeostasis. In humans, TRP is metabolized via the kynurenine and serotonin pathways, leading to the generation of biologically active compounds, such as serotonin, melatonin and niacin. In addition to endogenous TRP metabolism, resident gut microbiota also contributes to the production of specific TRP metabolites and indirectly influences host physiology. The variety of physiologic functions regulated by TRP reflects the complex pattern of diseases associated with altered homeostasis. Indeed, an imbalance in the synthesis of TRP metabolites has been associated with pathophysiologic mechanisms occurring in neurologic and psychiatric disorders, in chronic immune activation and in the immune escape of cancer. In this chapter, the role of TRP metabolism in health and disease is presented. Disorders involving the central nervous system, malignancy, inflammatory bowel and cardiovascular disease are discussed.


Assuntos
Doenças Cardiovasculares/metabolismo , Doenças do Sistema Nervoso Central/metabolismo , Saúde , Doenças Inflamatórias Intestinais/metabolismo , Neoplasias/metabolismo , Triptofano/metabolismo , Animais , Humanos
16.
PLoS Biol ; 18(3): e3000618, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32182233

RESUMO

Botulinum neurotoxins (BoNTs) are a family of bacterial toxins with seven major serotypes (BoNT/A-G). The ability of these toxins to target and bind to motor nerve terminals is a key factor determining their potency and efficacy. Among these toxins, BoNT/B is one of the two types approved for medical and cosmetic uses. Besides binding to well-established receptors, an extended loop in the C-terminal receptor-binding domain (HC) of BoNT/B (HC/B) has been proposed to also contribute to toxin binding to neurons by interacting with lipid membranes (termed lipid-binding loop [LBL]). Analogous loops exist in the HCs of BoNT/C, D, G, and a chimeric toxin DC. However, it has been challenging to detect and characterize binding of LBLs to lipid membranes. Here, using the nanodisc system and biolayer interferometry assays, we find that HC/DC, C, and G, but not HC/B and HC/D, are capable of binding to receptor-free lipids directly, with HC/DC having the highest level of binding. Mutagenesis studies demonstrate the critical role of consecutive aromatic residues at the tip of the LBL for binding of HC/DC to lipid membranes. Taking advantage of this insight, we then create a "gain-of-function" mutant HC/B by replacing two nonaromatic residues at the tip of its LBL with tryptophan. Cocrystallization studies confirm that these two tryptophan residues do not alter the structure of HC/B or the interactions with its receptors. Such a mutated HC/B gains the ability to bind receptor-free lipid membranes and shows enhanced binding to cultured neurons. Finally, full-length BoNT/B containing two tryptophan mutations in its LBL, together with two additional mutations (E1191M/S1199Y) that increase binding to human receptors, is produced and evaluated in mice in vivo using Digit Abduction Score assays. This mutant toxin shows enhanced efficacy in paralyzing local muscles at the injection site and lower systemic diffusion, thus extending both safety range and duration of paralysis compared with the control BoNT/B. These findings establish a mechanistic understanding of LBL-lipid interactions and create a modified BoNT/B with improved therapeutic efficacy.


Assuntos
Toxinas Botulínicas Tipo A/metabolismo , Toxinas Botulínicas Tipo A/farmacologia , Membrana Celular/metabolismo , Animais , Sítios de Ligação , Toxinas Botulínicas Tipo A/química , Toxinas Botulínicas Tipo A/genética , Células Cultivadas , Cristalografia por Raios X , Feminino , Gangliosídeos/metabolismo , Lipídeos de Membrana/metabolismo , Camundongos , Músculo Esquelético/efeitos dos fármacos , Mutação , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Paralisia/induzido quimicamente , Engenharia de Proteínas , Ratos Transgênicos , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/farmacologia , Sinaptotagminas/metabolismo , Triptofano/química , Triptofano/metabolismo
17.
Artigo em Inglês | MEDLINE | ID: mdl-32208989

RESUMO

Tryptophan catabolism through the kynurenine pathway generates a variety of bioactive metabolites. Physical exercise can modulate kynurenine pathway metabolism in skeletal muscle and thus change the concentrations of select compounds in peripheral tissues and in the central nervous system. Here we review recent advances in our understanding of how exercise alters tryptophan-kynurenine metabolism in muscle and its subsequent local and distal effects. We propose that the effects of kynurenine pathway metabolites on skeletal muscle, adipose tissue, immune system, and the brain suggest that some of these compounds could qualify as exercise-induced myokines. Indeed, some of the more recently discovered biological activities for kynurenines include many of the best-known benefits of exercise: improved energy homeostasis, promotion of an anti-inflammatory environment, and neuroprotection. Finally, by considering the tissue expression of the different membrane and cytosolic receptors for kynurenines, we discuss known and potential biological activities for these tryptophan metabolites.


Assuntos
Sistema Nervoso Central/metabolismo , Cinurenina/metabolismo , Redes e Vias Metabólicas/fisiologia , Músculo Esquelético/metabolismo , Encéfalo/metabolismo , Encéfalo/fisiologia , Sistema Nervoso Central/fisiologia , Exercício Físico/fisiologia , Homeostase/genética , Homeostase/fisiologia , Humanos , Sistema Imunitário/metabolismo , Sistema Imunitário/fisiologia , Cinurenina/genética , Metabolismo/fisiologia , Músculo Esquelético/fisiologia , PPAR gama/genética , Triptofano/metabolismo
18.
Nat Rev Gastroenterol Hepatol ; 17(4): 223-237, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32076145

RESUMO

A key role of the gut microbiota in the establishment and maintenance of health, as well as in the pathogenesis of disease, has been identified over the past two decades. One of the primary modes by which the gut microbiota interacts with the host is by means of metabolites, which are small molecules that are produced as intermediate or end products of microbial metabolism. These metabolites can derive from bacterial metabolism of dietary substrates, modification of host molecules, such as bile acids, or directly from bacteria. Signals from microbial metabolites influence immune maturation, immune homeostasis, host energy metabolism and maintenance of mucosal integrity. Alterations in the composition and function of the microbiota have been described in many studies on IBD. Alterations have also been described in the metabolite profiles of patients with IBD. Furthermore, specific classes of metabolites, notably bile acids, short-chain fatty acids and tryptophan metabolites, have been implicated in the pathogenesis of IBD. This Review aims to define the key classes of microbial-derived metabolites that are altered in IBD, describe the pathophysiological basis of these associations and identify future targets for precision therapeutic modulation.


Assuntos
Microbioma Gastrointestinal/fisiologia , Doenças Inflamatórias Intestinais/microbiologia , Animais , Ácidos e Sais Biliares/metabolismo , Ácidos Graxos Voláteis/fisiologia , Transplante de Microbiota Fecal/métodos , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/microbiologia , Humanos , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/metabolismo , Doenças Inflamatórias Intestinais/terapia , Metabolômica/métodos , Probióticos/uso terapêutico , Triptofano/metabolismo
19.
Proc Natl Acad Sci U S A ; 117(7): 3848-3857, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32024760

RESUMO

l-tryptophan (Trp), an essential amino acid for mammals, is the precursor of a wide array of immunomodulatory metabolites produced by the kynurenine and serotonin pathways. The kynurenine pathway is a paramount source of several immunoregulatory metabolites, including l-kynurenine (Kyn), the main product of indoleamine 2,3-dioxygenase 1 (IDO1) that catalyzes the rate-limiting step of the pathway. In the serotonin pathway, the metabolite N-acetylserotonin (NAS) has been shown to possess antioxidant, antiinflammatory, and neuroprotective properties in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). However, little is known about the exact mode of action of the serotonin metabolite and the possible interplay between the 2 Trp metabolic pathways. Prompted by the discovery that NAS neuroprotective effects in EAE are abrogated in mice lacking IDO1 expression, we investigated the NAS mode of action in neuroinflammation. We found that NAS directly binds IDO1 and acts as a positive allosteric modulator (PAM) of the IDO1 enzyme in vitro and in vivo. As a result, increased Kyn will activate the ligand-activated transcription factor aryl hydrocarbon receptor and, consequently, antiinflammatory and immunoregulatory effects. Because NAS also increased IDO1 activity in peripheral blood mononuclear cells of a significant proportion of MS patients, our data may set the basis for the development of IDO1 PAMs as first-in-class drugs in autoimmune/neuroinflammatory diseases.


Assuntos
Encefalomielite Autoimune Experimental/enzimologia , Encefalomielite Autoimune Experimental/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/química , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Regulação Alostérica , Sítio Alostérico , Animais , Biocatálise , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/genética , Feminino , Humanos , Indolamina-Pirrol 2,3,-Dioxigenase/genética , Cinurenina/metabolismo , Leucócitos Mononucleares/metabolismo , Masculino , Camundongos Knockout , Esclerose Múltipla/enzimologia , Esclerose Múltipla/genética , Esclerose Múltipla/metabolismo , Serotonina/análogos & derivados , Serotonina/química , Serotonina/metabolismo , Triptofano/metabolismo
20.
PLoS One ; 15(1): e0227384, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923274

RESUMO

Chronic cancer-related fatigue (CF) is a common and distressing condition in a subset of cancer survivors and common also after successful treatment of malignant lymphoma. The etiology and pathogenesis of CF is unknown, and lack of biomarkers hampers development of diagnostic tests and successful therapy. Recent studies on the changes of amino acid levels and other metabolites in patients with chronic fatigue syndrome/myalgic encephalopathy (CFS/ME) have pointed to possible central defects in energy metabolism. Here we report a comprehensive analysis of serum concentrations of amino acids, including metabolites of tryptophan, the kynurenine pathway and vitamin B6 in a well characterized national Norwegian cohort of lymphoma survivors after high-dose therapy and autologous stem cell transplantation. Among the 20 standard amino acids in humans, only tryptophan levels were significantly lower in both males and females with CF compared to non-fatigued survivors, a strikingly different pattern than seen in CFS/ME. Markers of tryptophan degradation by the kynurenine pathway (kynurenine/tryptophan ratio) and activation of vitamin B6 catabolism (pyridoxic acid/(pyridoxal + pyridoxal 5'-phosphate), PAr index) differed in survivors with or without CF and correlated with known markers of immune activation and inflammation, such as neopterin, C-reactive protein and Interleukin-6. Among personal traits and clinical findings assessed simultaneously in participating survivors, higher neuroticism score, obesity and higher PAr index were significantly associated with increased risk of CF. Collectively, these data point to low grade immune activation and inflammation as a basis for CF in lymphoma survivors.


Assuntos
Aminoácidos/metabolismo , Síndrome de Fadiga Crônica/etiologia , Linfoma/complicações , Vitamina B 6/metabolismo , Adolescente , Adulto , Idoso , Aminoácidos/sangue , Sobreviventes de Câncer , Criança , Síndrome de Fadiga Crônica/sangue , Síndrome de Fadiga Crônica/metabolismo , Síndrome de Fadiga Crônica/psicologia , Feminino , Humanos , Inflamação/sangue , Linfoma/metabolismo , Linfoma/psicologia , Linfoma/terapia , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Triptofano/metabolismo , Vitamina B 6/sangue , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA