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1.
Proc Natl Acad Sci U S A ; 121(7): e2315069121, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38315851

RESUMO

A key step in drug discovery, common to many disease areas, is preclinical demonstration of efficacy in a mouse model of disease. However, this demonstration and its translation to the clinic can be impeded by mouse-specific pathways of drug metabolism. Here, we show that a mouse line extensively humanized for the cytochrome P450 gene superfamily ("8HUM") can circumvent these problems. The pharmacokinetics, metabolite profiles, and magnitude of drug-drug interactions of a test set of approved medicines were in much closer alignment with clinical observations than in wild-type mice. Infection with Mycobacterium tuberculosis, Leishmania donovani, and Trypanosoma cruzi was well tolerated in 8HUM, permitting efficacy assessment. During such assessments, mouse-specific metabolic liabilities were bypassed while the impact of clinically relevant active metabolites and DDI on efficacy were well captured. Removal of species differences in metabolism by replacement of wild-type mice with 8HUM therefore reduces compound attrition while improving clinical translation, accelerating drug discovery.


Assuntos
Doenças Transmissíveis , Descoberta de Drogas , Camundongos , Animais , Interações Medicamentosas , Modelos Animais de Doenças , Sistema Enzimático do Citocromo P-450/metabolismo , Aceleração
2.
Sci Total Environ ; 888: 164211, 2023 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-37196967

RESUMO

Air pollution can cause a wide range of serious human diseases. For the informed instigation of interventions which prevent these outcomes there is an urgent need to develop robust in vivo biomarkers which provide insights into mechanisms of toxicity and relate pollutants to specific adverse outcomes. We exemplify for a first time the application of in vivo stress response reporters in establishing mechanisms of air pollution toxicity and the application of this knowledge in epidemiological studies. We first demonstrated the utility of reporter mice to understand toxicity mechanisms of air pollutants using diesel exhaust particles compounds. We observed that nitro-PAHs induced Hmox1 and CYP1a1 reporters in a time- and dose-dependent, cell- and tissue-specific manner. Using in vivo genetic and pharmacological approaches we confirmed that the NRF2 pathway mediated this Hmox1-reporter induction stress reporter activity. We then correlated the activation of stress-reporter models (oxidative stress/inflammation, DNA damage and Ah receptor -AhR- activity) with responses in primary human nasal cells exposed to chemicals present in particulate matter (PM; PM2.5-SRM2975, PM10-SRM1648b) or fresh roadside PM10. To exemplify their use in clinical studies, Pneumococcal adhesion was assessed in exposed primary human nasal epithelial cells (HPNEpC). The combined use of HPNEpC and in vivo reporters demonstrated that London roadside PM10 particles induced pneumococcal infection in HPNEpC mediated by oxidative stress responses. The combined use of in vivo reporter models with human data thus provides a robust approach to define the relationship between air pollutant exposure and health risks. Moreover, these models can be used in epidemiological studies to hazard ranking environmental pollutants by considering the complexity of mechanisms of toxicity. These data will facilitate the relationship between toxic potential and the level of pollutant exposure in populations to be established and potentially extremely valuable tools for intervention studies for disease prevention.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Humanos , Camundongos , Animais , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Material Particulado/análise , Emissões de Veículos/análise , Estresse Oxidativo
3.
J Cell Mol Med ; 26(21): 5463-5472, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36201626

RESUMO

Age-related diseases account for a high proportion of the total global burden of disease. Despite recent advances in understanding their molecular basis, there is a lack of suitable early biomarkers to test selected compounds and accelerate their translation to clinical trials. We have investigated the utility of in vivo stress reporter systems as surrogate early biomarkers of the degenerative disease progression. We hypothesized that cellular stress observed in models of human degenerative disease preceded overt cellular damage and at the same time will identify potential cytoprotective pathways. To test this hypothesis, we generated novel accelerated ageing (progeria) reporter mice by crossing the LmnaG609G mice into our oxidative stress/inflammation (Hmox1) and DNA damage (p21) stress reporter models. Histological analysis of reporter expression demonstrated a time-dependent and tissue-specific activation of the reporters in tissues directly associated with Progeria, including smooth muscle cells, the vasculature and gastrointestinal tract. Importantly, reporter expression was detected prior to any perceptible deleterious phenotype. Reporter expression can therefore be used as an early marker of progeria pathogenesis and to test therapeutic interventions. This work also demonstrates the potential to use stress reporter approaches to study and find new treatments for other degenerative diseases.


Assuntos
Progéria , Camundongos , Humanos , Animais , Progéria/genética , Progéria/metabolismo , Dano ao DNA/genética , Estresse Oxidativo , Biomarcadores/metabolismo , Fenótipo
4.
F1000Res ; 11: 1164, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-37427015

RESUMO

Chemical risk assessment ensures protection from the toxic effects of drugs and manmade chemicals. To comply with regulatory guidance, studies in complex organisms are required, as well as mechanistic studies to establish the relevance of any toxicities observed to man. Although in vitro toxicity models are improving, in vivo studies remain central to this process. Such studies are invariably time-consuming and often involve large numbers of animals. New regulatory frameworks recommend the implementation of "smart" in vivo approaches to toxicity testing that can effectively assess safety for humans and comply with societal expectations for reduction in animal use. A major obstacle in reducing the animals required is the time-consuming and complexity of the pathological endpoints used as markers of toxicity. Such endpoints are prone to inter-animal variability, subjectivity and require harmonisation between testing sites. As a consequence, large numbers of animals per experimental group are required. To address this issue, we propose the implementation of sophisticated stress response reporter mice that we have developed. These reporter models provide early biomarkers of toxic potential in a highly reproducible manner at single-cell resolution, which can also be measured non-invasively and have been extensively validated in academic research as early biomarkers of stress responses for a wide range of chemicals at human-relevant exposures. In this report, we describe a new and previously generated models in our lab, provide the methodology required for their use and discuss how they have been used to inform on toxic risk (likelihood of chemical causing an adverse health effect). We propose our in vivo approach is more informative (refinement) and reduces the animal use (reduction) compared to traditional toxicity testing. These models could be incorporated into tiered toxicity testing and used in combination with in vitro assays to generate quantitative adverse outcome pathways and inform on toxic potential.


Assuntos
Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Testes de Toxicidade , Animais , Humanos , Camundongos , Testes de Toxicidade/métodos , Medição de Risco
5.
F1000Res ; 11: 1081, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-37065929

RESUMO

Drug development is an expensive and time-consuming process, with only a small fraction of drugs gaining regulatory approval from the often many thousands of candidates identified during target validation. Once a lead compound has been identified and optimised, they are subject to intensive pre-clinical research to determine their pharmacodynamic, pharmacokinetic and toxicological properties, procedures which inevitably involve significant numbers of animals - mainly mice and rats, but also dogs and monkeys in much smaller numbers and for specific types of drug candidates. Many compounds that emerge from this process, having been shown to be safe and efficacious in pre-clinical studies, subsequently fail to replicate this outcome in clinical trials, therefore wasting time, money and, most importantly, animals. The poor predictive power of animal models in pre-clinical studies is predominantly due to lack of efficacy or safety reasons, which in turn can be attributed mainly to the significant species differences in drug metabolism between humans and animals. To circumvent this, we have developed a complex transgenic mouse model - 8HUM - which faithfully replicates human Phase I drug metabolism (and its regulation), and which will generate more human-relevant data [ REFINEMENT] from fewer animals [ REDUCTION] in a pre-clinical setting and reduce attrition in the clinic. One key area for the pre-clinical application of animals in an oncology setting - almost exclusively mice - is their use in anti-tumour studies. We now further demonstrate the utility of the 8HUM mouse using a murine melanoma cell line as a syngeneic tumour and also present an immunodeficient version 8HUM_Rag2 -/- - for use in xenograft studies. These models will be of significant benefit not only to Pharma for pre-clinical drug development work, but also throughout the drug efficacy, toxicology, pharmacology, and drug metabolism communities, where fewer animals will be needed to generate more human-relevant data.


Assuntos
Neoplasias , Animais , Camundongos , Humanos , Ratos , Cães , Xenoenxertos , Neoplasias/tratamento farmacológico , Animais Geneticamente Modificados , Desenvolvimento de Medicamentos , Desenho de Fármacos
6.
Br J Cancer ; 125(11): 1552-1560, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34621046

RESUMO

BACKGROUND: Simultaneous inhibition of multiple components of the BRAF-MEK-ERK cascade (vertical inhibition) has become a standard of care for treating BRAF-mutant melanoma. However, the molecular mechanism of how vertical inhibition synergistically suppresses intracellular ERK activity, and consequently cell proliferation, are yet to be fully elucidated. METHODS: We develop a mechanistic mathematical model that describes how the mutant BRAF inhibitor, dabrafenib, and the MEK inhibitor, trametinib, affect BRAFV600E-MEK-ERK signalling. The model is based on a system of chemical reactions that describes cascade signalling dynamics. Using mass action kinetics, the chemical reactions are re-expressed as ordinary differential equations that are parameterised by in vitro data and solved numerically to obtain the temporal evolution of cascade component concentrations. RESULTS: The model provides a quantitative method to compute how dabrafenib and trametinib can be used in combination to synergistically inhibit ERK activity in BRAFV600E-mutant melanoma cells. The model elucidates molecular mechanisms of vertical inhibition of the BRAFV600E-MEK-ERK cascade and delineates how elevated BRAF concentrations generate drug resistance to dabrafenib and trametinib. The computational simulations further suggest that elevated ATP levels could be a factor in drug resistance to dabrafenib. CONCLUSIONS: The model can be used to systematically motivate which dabrafenib-trametinib dose combinations, for treating BRAFV600E-mutated melanoma, warrant experimental investigation.


Assuntos
MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , Sistema de Sinalização das MAP Quinases , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Modelos Biológicos , Modelos Químicos , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , MAP Quinases Reguladas por Sinal Extracelular/química , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Imidazóis/química , Imidazóis/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Melanoma/tratamento farmacológico , Melanoma/enzimologia , Melanoma/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/química , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Mutação , Oximas/química , Oximas/farmacologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas B-raf/química , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas B-raf/metabolismo , Piridonas/química , Piridonas/farmacologia , Pirimidinonas/química , Pirimidinonas/farmacologia
7.
Redox Biol ; 47: 102160, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34624602

RESUMO

BACKGROUND: Interleukin-1-dependent increases in glycolysis promote allergic airways disease in mice and disruption of pyruvate kinase M2 (PKM2) activity is critical herein. Glutathione-S-transferase P (GSTP) has been implicated in asthma pathogenesis and regulates the oxidation state of proteins via S-glutathionylation. We addressed whether GSTP-dependent S-glutathionylation promotes allergic airways disease by promoting glycolytic reprogramming and whether it involves the disruption of PKM2. METHODS: We used house dust mite (HDM) or interleukin-1ß in C57BL6/NJ WT or mice that lack GSTP. Airway basal cells were stimulated with interleukin-1ß and the selective GSTP inhibitor, TLK199. GSTP and PKM2 were evaluated in sputum samples of asthmatics and healthy controls and incorporated analysis of the U-BIOPRED severe asthma cohort database. RESULTS: Ablation of Gstp decreased total S-glutathionylation and attenuated HDM-induced allergic airways disease and interleukin-1ß-mediated inflammation. Gstp deletion or inhibition by TLK199 decreased the interleukin-1ß-stimulated secretion of pro-inflammatory mediators and lactate by epithelial cells. 13C-glucose metabolomics showed decreased glycolysis flux at the pyruvate kinase step in response to TLK199. GSTP and PKM2 levels were increased in BAL of HDM-exposed mice as well as in sputum of asthmatics compared to controls. Sputum proteomics and transcriptomics revealed strong correlations between GSTP, PKM2, and the glycolysis pathway in asthma. CONCLUSIONS: GSTP contributes to the pathogenesis of allergic airways disease in association with enhanced glycolysis and oxidative disruption of PKM2. Our findings also suggest a PKM2-GSTP-glycolysis signature in asthma that is associated with severe disease.


Assuntos
Asma , Proteínas de Transporte/metabolismo , Glutationa S-Transferase pi/metabolismo , Proteínas de Membrana/metabolismo , Piruvato Quinase , Hormônios Tireóideos/metabolismo , Animais , Proteínas de Transporte/genética , Glutationa/metabolismo , Glutationa S-Transferase pi/genética , Glutationa Transferase , Glicólise , Humanos , Pulmão/metabolismo , Proteínas de Membrana/genética , Camundongos , Piruvato Quinase/genética , Piruvato Quinase/metabolismo , Hormônios Tireóideos/genética
8.
Commun Biol ; 4(1): 1081, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34526660

RESUMO

Transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) and its main negative regulator, Kelch-like ECH associated protein 1 (Keap1), are at the interface between redox and intermediary metabolism. Nrf2 activation is protective in models of human disease and has benefits in clinical trials. Consequently, the Keap1/Nrf2 protein complex is a drug target. However, in cancer Nrf2 plays a dual role, raising concerns that Nrf2 activators may promote growth of early neoplasms. To address this concern, we examined the role of Nrf2 in development of colorectal adenomas by employing genetic, pharmacological, and metabolomic approaches. We found that colorectal adenomas that form in Gstp-/-: ApcMin/+ mice are characterized by altered one-carbon metabolism and that genetic activation, but not disruption of Nrf2, enhances these metabolic alterations. However, this enhancement is modest compared to the magnitude of metabolic differences between tumor and peri-tumoral tissues, suggesting that the metabolic changes conferred by Nrf2 activation may have little contribution to the early stages of carcinogenesis. Indeed, neither genetic (by Keap1 knockdown) nor pharmacological Nrf2 activation, nor its disruption, affected colorectal adenoma formation in this model. We conclude that pharmacological Nrf2 activation is unlikely to impact the early stages of development of colorectal cancer.


Assuntos
Adenoma/genética , Neoplasias Colorretais/genética , Fator 2 Relacionado a NF-E2/genética , Adenoma/metabolismo , Animais , Carcinogênese , Neoplasias Colorretais/metabolismo , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Fator 2 Relacionado a NF-E2/metabolismo
9.
Environ Pollut ; 270: 116053, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33213951

RESUMO

Inorganic arsenic (iAs) is a naturally occurring metalloid present in drinking water and polluted air exposing millions of people globally. Epidemiological studies have linked iAs exposure to the development of numerous diseases including cognitive impairment, cardiovascular failure and cancer. Despite intense research, an effective therapy for chronic arsenicosis has yet to be developed. Laboratory studies have been of great benefit in establishing the pathways involved in iAs toxicity and providing insights into its mechanism of action. However, the in vivo analysis of arsenic toxicity mechanisms has been difficult by the lack of reliable in vivo biomarkers of iAs's effects. To address this issue we have applied the use of our recently developed stress reporter models to study iAs toxicity. The reporter mice Hmox1 (oxidative stress/inflammation; HOTT) and p21 (DNA damage) were exposed to iAs at acute and chronic, environmentally relevant, doses. We observed induction of the oxidative stress reporters in several cell types and tissues, which was largely dependent on the activation of transcription factor NRF2. We propose that our HOTT reporter model can be used as a surrogate biomarker of iAs-induced oxidative stress, and it constitutes a first-in-class platform to develop treatments aimed to counteract the role of oxidative stress in arsenicosis. Indeed, in a proof of concept experiment, the HOTT reporter mice were able to predict the therapeutic utility of the antioxidant N-acetyl cysteine in the prevention of iAs associated toxicity.


Assuntos
Intoxicação por Arsênico , Arsênio , Animais , Antioxidantes , Arsênio/toxicidade , Biomarcadores , Heme Oxigenase-1/genética , Proteínas de Membrana , Camundongos , Estresse Oxidativo
10.
Food Chem Toxicol ; 142: 111459, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32474023

RESUMO

2-Monochloropropane-1,3-diol (2-MCPD) and its isomer 3-monochloropropane-1,2-diol (3-MCPD) are widespread food contaminants. 3-MCPD has been classified as a non-genotoxic carcinogen, whereas very limited toxicological data are available for 2-MCPD. Animal studies indicate that heart and skeletal muscle are target organs of 2-MCPD. Oxidative stress may play a role in this process, and the potential of 3-MCPD to induce oxidative stress in vivo has already been demonstrated. To investigate the potential of 2-MCPD to induce oxidative stress in vivo, a 28-day oral feeding study in male HOTT reporter mice was conducted. This mouse model allows monitoring substance-induced oxidative stress in various target organs on the basis of Hmox1 promoter activation. Repeated daily doses of up to 100 mg 2-MCPD/kg body weight did not result in substantial toxicity. Furthermore, the highest dose of 2-MCPD had only minor effects on oxidative stress in kidney and testes, whereas brain, heart and skeletal muscle were not affected. Additionally, 2-MCPD caused only mild changes in the expression of Nrf2-dependent genes and only slightly affected the redox status of the redox-sensor protein DJ-1. Thus, the data indicate that 2-MCPD, in contrast to its isomer 3-MCPD, does not lead to a considerable induction of oxidative stress in male mice.


Assuntos
Glicerol/análogos & derivados , Estresse Oxidativo/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Expressão Gênica/efeitos dos fármacos , Glicerol/administração & dosagem , Glicerol/farmacocinética , Glicerol/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Tamanho do Órgão/efeitos dos fármacos , Estresse Oxidativo/genética , Distribuição Tecidual
11.
Arch Toxicol ; 94(1): 219-229, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31606820

RESUMO

Pyrrolizidine alkaloids (PAs) are widely occurring phytotoxins which can induce severe liver damage in humans and other mammalian species by mechanisms that are not fully understood. Therefore, we investigated the development of PA hepatotoxicity in vivo, using an acutely toxic dose of the PA senecionine in mice, in combination with intravital two-photon microscopy, histology, clinical chemistry, and in vitro experiments with primary mouse hepatocytes and liver sinusoidal endothelial cells (LSECs). We observed pericentral LSEC necrosis together with elevated sinusoidal marker proteins in the serum of senecionine-treated mice and increased sinusoidal platelet aggregation in the damaged tissue regions. In vitro experiments showed no cytotoxicity to freshly isolated LSECs up to 500 µM senecionine. However, metabolic activation of senecionine by preincubation with primary mouse hepatocytes increased the cytotoxicity to cultivated LSECs with an EC50 of approximately 22 µM. The cytochrome P450 (CYP)-dependency of senecionine bioactivation was confirmed in CYP reductase-deficient mice where no PA-induced hepatotoxicity was observed. Therefore, toxic metabolites of senecionine are generated by hepatic CYPs, and may be partially released from hepatocytes leading to destruction of LSECs in the pericentral region of the liver lobules. Analysis of hepatic bile salt transport by intravital two-photon imaging revealed a delayed uptake of a fluorescent bile salt analogue from the hepatic sinusoids into hepatocytes and delayed elimination. This was accompanied by transcriptional deregulation of hepatic bile salt transporters like Abcb11 or Abcc1. In conclusion, senecionine destroys LSECs although the toxic metabolite is formed in a CYP-dependent manner in the adjacent pericentral hepatocytes.


Assuntos
Colestase/induzido quimicamente , Sistema Enzimático do Citocromo P-450/metabolismo , Fígado/citologia , Alcaloides de Pirrolizidina/toxicidade , Animais , Células Cultivadas , Colestase/patologia , Sistema Enzimático do Citocromo P-450/genética , Células Endoteliais/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Necrose/induzido quimicamente , Agregação Plaquetária/efeitos dos fármacos , Alcaloides de Pirrolizidina/farmacocinética , Testes de Toxicidade/métodos
12.
Food Chem Toxicol ; 136: 110957, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31712104

RESUMO

3-Chloro-1,2-propanediol (3-MCPD) is a food contaminant which has been classified as a non-genotoxic carcinogen (category 2B). Previous studies suggested that oxidative stress might play a role in 3-MCPD toxicity. To elucidate the impact of 3-MCPD-mediated organ toxicity in more detail, transgenic reporter mice were employed which contain a lacZ reporter under the control of the heme oxygenase 1 (Hmox1) promoter which is responsive to oxidative stress. The mice received daily doses of up to 100 mg/kg body weight 3-MCPD per day in a 28-day feeding study. Subsequently, tissue slices from different organs were subjected to X-Gal staining as the readout for lacZ gene expression. A dose-dependent increase of blue stain was observed in mouse kidney that was exclusively visible in the renal cortex but not in the renal medulla. Moreover, blue-stained regions were detected in the basal membrane of the seminiferous tubules in testes and also in specific brain regions (cerebellum, midbrain and pons). Notably, gene expression of a number of Nrf2-dependent target genes except Hmox1 was not severely affected by 3-MCPD. In all three organs, however, the amount of irreversibly oxidized DJ-1 protein, which is a biomarker for oxidative stress, was significantly increased already by low doses of 3-MCPD.


Assuntos
Encéfalo/efeitos dos fármacos , Rim/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Testículo/efeitos dos fármacos , alfa-Cloridrina/toxicidade , Animais , Biomarcadores/metabolismo , Encéfalo/patologia , Rim/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteína Desglicase DJ-1/metabolismo , Testículo/patologia
13.
Arch Toxicol ; 93(7): 1817-1833, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31139862

RESUMO

Evidence exists that humans are exposed to plastic microparticles via diet. Data on intestinal particle uptake and health-related effects resulting from microplastic exposure are scarce. Aim of the study was to analyze the uptake and effects of microplastic particles in human in vitro systems and in rodents in vivo. The gastrointestinal uptake of microplastics was studied in vitro using the human intestinal epithelial cell line Caco-2 and thereof-derived co-cultures mimicking intestinal M-cells and goblet cells. Different sizes of spherical fluorescent polystyrene (PS) particles (1, 4 and 10 µm) were used to study particle uptake and transport. A 28-days in vivo feeding study was conducted to analyze transport at the intestinal epithelium and oxidative stress response as a potential consequence of microplastic exposure. Male reporter gene mice were treated three times per week by oral gavage with a mixture of 1 µm (4.55 × 107 particles), 4 µm (4.55 × 107 particles) and 10 µm (1.49 × 106 particles) microplastics at a volume of 10 mL/kg/bw. Effects of particles on macrophage polarization were investigated using the human cell line THP-1 to detect a possible impact on intestinal immune cells. Altogether, the results of the study demonstrate the cellular uptake of a minor fraction of particles. In vivo data show the absence of histologically detectable lesions and inflammatory responses. The particles did not interfere with the differentiation and activation of the human macrophage model. The present results suggest that oral exposure to PS microplastic particles under the chosen experimental conditions does not pose relevant acute health risks to mammals.


Assuntos
Macrófagos/efeitos dos fármacos , Microplásticos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Poliestirenos/administração & dosagem , Administração Oral , Animais , Transporte Biológico , Células CACO-2 , Linhagem Celular , Técnicas de Cocultura , Células Caliciformes/metabolismo , Humanos , Absorção Intestinal , Mucosa Intestinal/metabolismo , Masculino , Camundongos , Tamanho da Partícula , Poliestirenos/farmacocinética , Poliestirenos/toxicidade
14.
Toxicol Appl Pharmacol ; 366: 64-74, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30685480

RESUMO

The anticancer drug ellipticine exerts its genotoxic effects after metabolic activation by cytochrome P450 (CYP) enzymes. The present study has examined the role of cytochrome P450 oxidoreductase (POR) and cytochrome b5 (Cyb5), electron donors to P450 enzymes, in the CYP-mediated metabolism and disposition of ellipticine in vivo. We used Hepatic Reductase Null (HRN) and Hepatic Cytochrome b5/P450 Reductase Null (HBRN) mice. HRN mice have POR deleted specifically in hepatocytes; HBRN mice also have Cyb5 deleted in the liver. Mice were treated once with 10 mg/kg body weight ellipticine (n = 4/group) for 24 h. Ellipticine-DNA adduct levels measured by 32P-postlabelling were significantly lower in HRN and HBRN livers than in wild-type (WT) livers; however no significant difference was observed between HRN and HBRN livers. Ellipticine-DNA adduct formation in WT, HRN and HBRN livers correlated with Cyp1a and Cyp3a enzyme activities measured in hepatic microsomes in the presence of NADPH confirming the importance of P450 enzymes in the bioactivation of ellipticine in vivo. Hepatic microsomal fractions were also utilised in incubations with ellipticine and DNA in the presence of NADPH, cofactor for POR, and NADH, cofactor for Cyb5 reductase (Cyb5R), to examine ellipticine-DNA adduct formation. With NADPH adduct formation decreased as electron donors were lost which correlated with the formation of the reactive metabolites 12- and 13-hydroxy-ellipticine in hepatic microsomes. No difference in adduct formation was observed in the presence of NADH. Our study demonstrates that Cyb5 contributes to the P450-mediated bioactivation of ellipticine in vitro, but not in vivo.


Assuntos
Antineoplásicos/metabolismo , Citocromo-B(5) Redutase/deficiência , Citocromos b5/deficiência , Elipticinas/metabolismo , Hepatócitos/enzimologia , Fígado/enzimologia , Ativação Metabólica , Animais , Antineoplásicos/farmacologia , Hidrocarboneto de Aril Hidroxilases/metabolismo , Citocromo P-450 CYP3A , Sistema Enzimático do Citocromo P-450/metabolismo , Citocromo-B(5) Redutase/genética , Citocromos b5/genética , Adutos de DNA/metabolismo , Elipticinas/farmacologia , Genótipo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microssomos Hepáticos/enzimologia , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Fenótipo
15.
Mol Pharmacol ; 95(1): 97-105, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30361333

RESUMO

The constitutive androstane receptor (CAR) is a xenobiotic sensor expressed in hepatocytes that activates genes involved in drug metabolism, lipid homeostasis, and cell proliferation. Much progress has been made in understanding the mechanism of activation of human CAR by drugs and xenobiotics. However, many aspects of the activation pathway remain to be elucidated. In this report, we have used viral constructs to express human CAR, its splice variants, and mutant CAR forms in hepatocytes from Car-/- mice in vitro and in vivo. We demonstrate CAR expression rescued the ability of Car-/- hepatocytes to respond to a wide range of CAR activators including phenobarbital. Additionally, two major splice isoforms of human CAR, CAR2 and CAR3, were inactive with almost all the agents tested. In contrast to the current model of CAR activation, ectopic CAR1 is constitutively localized in the nucleus and is loaded onto Cyp2b10 gene in the absence of an inducing agent. In studies to elucidate the role of threonine T38 in CAR regulation, we found that the T38D mutant was inactive even in the presence of CAR activators. However, the T38A mutant was activated by CAR inducers, showing that T38 is not essential for CAR activation. Also, using the inhibitor erlotinib, we could not confirm a role for the epidermal growth factor receptor in CAR regulation. Our data suggest that CAR is constitutively bound to gene regulatory regions and is regulated by exogenous agents through a mechanism which involves protein phosphorylation in the nucleus.


Assuntos
Cromatina/genética , Hepatócitos/fisiologia , Receptores Citoplasmáticos e Nucleares/genética , Ativação Transcricional/genética , Animais , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/genética , Células Cultivadas , Receptor Constitutivo de Androstano , Receptores ErbB/genética , Cloridrato de Erlotinib/farmacologia , Feminino , Hepatócitos/efeitos dos fármacos , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Fenobarbital/farmacologia , Isoformas de Proteínas/genética , Ativação Transcricional/efeitos dos fármacos
16.
Clin Cancer Res ; 24(9): 2138-2147, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29437786

RESUMO

Purpose: Osimertinib is a third-generation inhibitor of the epidermal growth factor receptor used in treatment of non-small cell lung cancer. A full understanding of its disposition and capacity for interaction with other medications will facilitate its effective use as a single agent and in combination therapy.Experimental Design: Recombinant cytochrome P450s and liver microsomal preparations were used to identify novel pathways of osimertinib metabolism in vitro A panel of knockout and mouse lines humanized for pathways of drug metabolism were used to establish the relevance of these pathways in vivoResults: Although some osimertinib metabolites were similar in mouse and human liver samples there were several significant differences, in particular a marked species difference in the P450s involved. The murine Cyp2d gene cluster played a predominant role in mouse, whereas CYP3A4 was the major human enzyme responsible for osimertinib metabolism. Induction of this enzyme in CYP3A4 humanized mice substantially decreased circulating osimertinib exposure. Importantly, we discovered a further novel pathway of osimertinib disposition involving CPY1A1. Modulation of CYP1A1/CYP1A2 levels markedly reduced parent drug concentrations, significantly altering metabolite pharmacokinetics (PK) in humanized mice in vivoConclusions: We demonstrate that a P450 enzyme expressed in smokers' lungs and lung tumors has the capacity to metabolise osimertinib. This could be a significant factor in defining the outcome of osimertinib treatment. This work also illustrates how P450-humanized mice can be used to identify and mitigate species differences in drug metabolism and thereby model the in vivo effect of critical metabolic pathways on anti-tumor response. Clin Cancer Res; 24(9); 2138-47. ©2018 AACR.


Assuntos
Acrilamidas/farmacologia , Compostos de Anilina/farmacologia , Antineoplásicos/farmacologia , Neoplasias Pulmonares/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Acrilamidas/uso terapêutico , Compostos de Anilina/uso terapêutico , Animais , Antineoplásicos/química , Antineoplásicos/uso terapêutico , Cromatografia Líquida , Família 2 do Citocromo P450/metabolismo , Modelos Animais de Doenças , Metabolismo Energético , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/mortalidade , Masculino , Metaboloma , Metabolômica/métodos , Camundongos , Camundongos Transgênicos , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto
17.
Arch Toxicol ; 92(4): 1625-1638, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29368147

RESUMO

Benzo[a]pyrene (BaP) is an environmental pollutant that, based on evidence largely from in vitro studies, exerts its genotoxic effects after metabolic activation by cytochrome P450s. In the present study, Hepatic Reductase Null (HRN) and Hepatic Cytochrome b 5 /P450 Reductase Null (HBRN) mice have been used to study the role of P450s in the metabolic activation of BaP in vivo. In HRN mice, cytochrome P450 oxidoreductase (POR), the electron donor to P450, is deleted specifically in hepatocytes. In HBRN mice the microsomal haemoprotein cytochrome b 5 , which can also act as an electron donor from cytochrome b 5 reductase to P450s, is also deleted in the liver. Wild-type (WT), HRN and HBRN mice were treated by i.p. injection with 125 mg/kg body weight BaP for 24 h. Hepatic microsomal fractions were isolated from BaP-treated and untreated mice. In vitro incubations carried out with BaP-pretreated microsomal fractions, BaP and DNA resulted in significantly higher BaP-DNA adduct formation with WT microsomal fractions compared to those from HRN or HBRN mice. Adduct formation (i.e. 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP [dG-N2-BPDE]) correlated with observed CYP1A activity and metabolite formation (i.e. BaP-7,8-dihydrodiol) when NADPH or NADH was used as enzymatic cofactors. BaP-DNA adduct levels (i.e. dG-N2-BPDE) in vivo were significantly higher (~ sevenfold) in liver of HRN mice than WT mice while no significant difference in adduct formation was observed in liver between HBRN and WT mice. Our results demonstrate that POR and cytochrome b 5 both modulate P450-mediated activation of BaP in vitro. However, hepatic P450 enzymes in vivo appear to be more important for BaP detoxification than its activation.


Assuntos
Benzo(a)pireno/metabolismo , Citocromo-B(5) Redutase/metabolismo , Adutos de DNA/metabolismo , Hepatócitos/enzimologia , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Animais , Camundongos , Camundongos Knockout , Microssomos Hepáticos/enzimologia
18.
J Physiol ; 596(1): 105-127, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29086419

RESUMO

KEY POINTS: Haem oxygenase 1 (Hmox1) is a cytoprotective enzyme with anti-inflammatory and anti-oxidant properties that is induced in response to multiple noxious environmental stimuli and disease states. Tools to enable its expression to be monitored in vivo have been unavailable until now. In a new Hmox1 reporter model we provide high-fidelity, single-cell resolution blueprints for Hmox1 expression throughout the body of mice. We show for the first time that Hmox1 is constitutively expressed at barrier tissues at the interface between the internal and external environments, and that it is highly induced in muscle cells during systemic inflammation. These data suggest novel biological insights into the role of Hmox1 and pave the way for the use of the model to study the role of environmental stress in disease pathology. ABSTRACT: Hmox1 protein holds great promise as a biomarker of in vivo stress responses as it is highly induced in stressed or damaged cells. However, Hmox1 expression patterns have thus far only been available in simple model organisms with limited relevance to humans. We now report a new Hmox1 reporter line that makes it possible to obtain this information in mice, a premiere model system for studying human disease and toxicology. Using a state-of-the-art strategy, we expressed multiple complementary reporter molecules from the murine Hmox1 locus, including firefly luciferase, to allow long-term, non-invasive imaging of Hmox1 expression, and ß-galactosidase for high-resolution mapping of expression patterns post-mortem. We validated the model by confirming the fidelity of reporter expression, and its responsiveness to oxidative and inflammatory stimuli. In addition to providing blueprints for Hmox1 expression in mice that provide novel biological insights, this work paves the way for the broad application of this model to establish cellular stresses induced by endogenous processes and those resulting from exposure to drugs and environmental agents. It will also enable studies on the role of oxidative stress in the pathogenesis of disease and its prevention.


Assuntos
Genes Reporter , Heme Oxigenase-1/metabolismo , Inflamação/diagnóstico , Proteínas de Membrana/metabolismo , Estresse Oxidativo , Animais , Feminino , Heme Oxigenase-1/genética , Inflamação/genética , Inflamação/metabolismo , Luciferases/metabolismo , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , beta-Galactosidase/metabolismo
20.
J Pharmacol Exp Ther ; 363(1): 12-19, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28882992

RESUMO

Ponatinib, a pan-BCR-ABL tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia (CML), causes severe side effects including vascular occlusions, pancreatitis, and liver toxicity, although the underlying mechanisms remain unclear. Modifications of critical proteins through reactive metabolites are thought to be responsible for a number of adverse drug reactions. In vitro metabolite screening of ponatinib with human liver microsomes and glutathione revealed unambiguous signals of ponatinib-glutathione (P-GSH) adducts. Further profiling of human cytochrome P450 (P450) indicated that CYP1A1 was the predominant P450 enzyme driving this reaction. P-GSH conjugate formation paralleled the disappearance of hydroxylated ponatinib metabolites, suggesting the initial reaction was epoxide generation. Mouse glutathione S-transferase p1 (mGstp1) further enhanced P-GSH adduct formation in vitro. Ponatinib pharmacokinetics were determined in vivo in wild-type (WT) mice and mice humanized for CYP1A1/2 and treated with the CYP1A1 inducers 2,3,7,8-tetrachlorodibenzodioxin or 3-methylcholanthrene. Ponatinib exposure was significantly decreased in treated mice compared with controls (7.7- and 2.2-fold for WT and humanized CYP1A1/2, respectively). Interestingly, the P-GSH conjugate was only found in the feces of CYP1A1-induced mice, but not in control animals. Protein adducts were also identified by liquid chromatography-tandem mass spectrometry analysis of mGstp1 tryptic digests. These results indicate that not only could CYP1A1 be involved in ponatinib disposition, which has not been previously reported, but also that electrophilic intermediates resulting from CYP1A1 metabolism in normal tissues may contribute to ponatinib toxicity. These data are consistent with a recent report that CML patients who smoke are at greater risk of disease progression and premature death.


Assuntos
Biocatálise , Citocromo P-450 CYP1A1/metabolismo , Imidazóis/metabolismo , Piridazinas/metabolismo , Animais , Glutationa/metabolismo , Glutationa S-Transferase pi/metabolismo , Humanos , Imidazóis/toxicidade , Masculino , Camundongos , Piridazinas/toxicidade , Proteínas Recombinantes/metabolismo
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