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Introduction: Prostate cancer (PC) is the second most common cancer and the fifth most frequent cause of cancer death among men. Prostate-specific membrane antigen (PSMA) expression is associated with aggressive PC, with expression in over 90% of patients with metastatic disease. Those characteristics have led to its use for PC diagnosis and therapies with radiopharmaceuticals, antibody-drug conjugates, and nanoparticles. Despite these advancements, none of the current therapeutics are curative and show some degree of toxicity. Here we present the synthesis and preclinical evaluation of a multimodal, PSMA-targeted dendrimer-drug conjugate (PT-DDC), synthesized using poly(amidoamine) (PAMAM) dendrimers. PT-DDC was designed to enable imaging of drug delivery, providing valuable insights to understand and enhance therapeutic response. Methods: The PT-DDC was synthesized through consecutive conjugation of generation-4 PAMAM dendrimers with maytansinoid-1 (DM1) a highly potent antimitotic agent, Cy5 infrared dye for optical imaging, 2,2',2"-(1,4,7-triazacyclononane-1,4,7-triyl)triacetic acid (NOTA) chelator for radiolabeling with copper-64 and positron emission tomography tomography/computed tomography (PET/CT), lysine-urea-glutamate (KEU) PSMA-targeting moiety and the remaining terminal primary amines were capped with butane-1,2-diol. Non-targeted control dendrimer-drug conjugate (Ctrl-DDC) was formulated without conjugation of KEU. PT-DDC and Ctrl-DDC were characterized using high-performance liquid chromatography, matrix assisted laser desorption ionization mass spectrometry and dynamic light scattering. In vitro and in vivo evaluation of PT-DDC and Ctrl-DDC were carried out in isogenic human prostate cancer PSMA+ PC3 PIP and PSMA- PC3 flu cell lines, and in mice bearing the corresponding xenografts. Results: PT-DDC was stable in 1×PBS and human blood plasma and required glutathione for DM1 release. Optical, PET/CT and biodistribution studies confirmed the in vivo PSMA-specificity of PT-DDC. PT-DDC demonstrated dose-dependent accumulation and cytotoxicity in PSMA+ PC3 PIP cells, and also showed growth inhibition of the corresponding tumors. PT-DDC did not accumulate in PSMA- PC3 flu tumors and did not inhibit their growth. Ctrl-DDC did not show PSMA specificity. Conclusion: In this study, we synthesized a multimodal theranostic agent capable of delivering DM1 and a radionuclide to PSMA+ tumors. This approach holds promise for enhancing image-guided treatment of aggressive, metastatic subtypes of prostate cancer.
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Antígenos de Superficie , Dendrímeros , Glutamato Carboxipeptidasa II , Neoplasias de la Próstata , Dendrímeros/química , Dendrímeros/farmacocinética , Dendrímeros/farmacología , Masculino , Humanos , Glutamato Carboxipeptidasa II/metabolismo , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/metabolismo , Antígenos de Superficie/metabolismo , Línea Celular Tumoral , Animales , Ratones , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Sistemas de Liberación de Medicamentos/métodosRESUMEN
Neuroinflammation through enhanced innate immunity is thought play a role in the pathogenesis of Parkinson's disease (PD). Methods for monitoring neuroinflammation in living patients with PD are currently limited to positron emission tomography (PET) ligands that lack specificity in labeling immune cells in the nervous system. The colony stimulating factor 1 receptor (CSF1R) plays a crucial role in microglial function, an important cellular contributor to the nervous system's innate immune response. Using immunologic methods, we show that CSF1R in human brain is colocalized with the microglial marker, ionized calcium binding adaptor molecule 1 (Iba1). In PD, CSF1R immunoreactivity is significantly increased in PD across multiple brain regions, with the largest differences in the midbrain versus controls. Autoradiography revealed significantly increased [3H]JHU11761 binding in the inferior parietal cortex of PD patients. PET imaging demonstrated that higher [11C]CPPC binding in the striatum was associated with greater motor disability in PD. Furthermore, increased [11C]CPPC binding in various regions correlated with more severe motor disability and poorer verbal fluency. This study finds that CSF1R expression is elevated in PD and that [11C]CPPC-PET imaging of CSF1R is indicative of motor and cognitive impairments in the early stages of the disease. Moreover, the study underscores the significance of CSF1R as a promising biomarker for neuroinflammation in Parkinson's disease, suggesting its potential use for non-invasive assessment of disease progression and severity, leading to earlier diagnosis and targeted interventions.
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Recently developed molecular imaging approaches can be used to visualize specific host responses and pathology in a quest to image infections where few microbe-specific tracers have been developed and in recognition that host responses contribute to morbidity and mortality in their own right. Here we highlight several recent examples of these imaging approaches adapted for imaging infections. The early successes and new avenues described here encompass diverse imaging modalities and leverage diverse aspects of the host response to infection-including inflammation, tissue injury and healing, and key nutrients during host-pathogen interactions. Clearly, these approaches merit further preclinical and clinical study as they are complementary and orthogonal to the pathogen-focused imaging modalities currently under investigation.
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Interacciones Huésped-Patógeno , Inflamación , HumanosRESUMEN
PURPOSE: Macrophages represent an essential means of sequestration and immune evasion for Mycobacterium tuberculosis. Pulmonary tuberculosis (TB) is characterized by dense collections of tissue-specific and recruited macrophages, both of which abundantly express CSF1R on their outer surface. 4-Cyano-N-(5-(1-(dimethylglycyl)piperidin-4-yl)-2',3',4',5'-tetrahydro-[1,1'-biphenyl]-2-yl)-1H-imidazole-2-carboxamide (JNJ-28312141) is a reported high affinity, CSF1R-selective antagonist. We report the radiosynthesis of 4-cyano-N-(5-(1-(N-methyl-N-([11C]methyl)glycyl)piperidin-4-yl)-2',3',4',5'-tetrahydro-[1,1'-biphenyl]-2-yl)-1H-imidazole-2-carboxamide ([11C]JNJ-28312141) and non-invasive detection of granulomatous and diffuse lesions in a mouse model of TB using positron emission tomography (PET). METHODS: Nor-methyl-JNJ-28312141 precursor was radiolabeled with [11C]iodomethane to produce [11C]JNJ-28312141. PET/CT imaging was performed in the C3HeB/FeJ murine model of chronic pulmonary TB to co-localize radiotracer uptake with granulomatous lesions observed on CT. Additionally, CSF1R, Iba1 fluorescence immunohistochemistry was performed to co-localize CSF1R target with reactive macrophages in infected and healthy mice. RESULTS: Radiosynthesis of [11C]JNJ-28312141 averaged a non-decay-corrected yield of 18.7 ± 2.1%, radiochemical purity of 99%, and specific activity averaging 658 ± 141 GBq/µmol at the end-of-synthesis. PET/CT imaging in healthy mice showed hepatobiliary [13.39-25.34% ID/g, percentage of injected dose per gram of tissue (ID/g)] and kidney uptake (12.35% ID/g) at 40-50 min post-injection. Infected mice showed focal pulmonary lesion uptake (5.58-12.49% ID/g), hepatobiliary uptake (15.30-40.50% ID/g), cervical node uptake, and renal uptake (11.66-29.33% ID/g). The ratio of infected lesioned lung/healthy lung uptake is 5.91:1, while the ratio of lesion uptake to adjacent infected radiolucent lung is 2.8:1. Pre-administration of 1 mg/kg of unlabeled JNJ-28312141 with [11C]JNJ-28312141 in infected animals resulted in substantial blockade. Fluorescence microscopy of infected and uninfected whole lung sections exclusively co-localized CSF1R staining with abundant Iba1 + macrophages. Healthy lung exhibited no CSF1R staining and very few Iba1 + macrophages. CONCLUSION: [11C]JNJ-28312141 binds specifically to CSF1R + macrophages and delineates granulomatous foci of disease in a murine model of pulmonary TB.
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Tomografía Computarizada por Tomografía de Emisión de Positrones , Tuberculosis , Animales , Compuestos de Bifenilo , Modelos Animales de Enfermedad , Imidazoles , Ratones , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Tomografía de Emisión de Positrones/métodos , Receptores de Factor Estimulante de Colonias de Granulocitos y Macrófagos , Tomografía Computarizada por Rayos X , Tuberculosis/diagnóstico por imagenRESUMEN
Tuberculous meningitis (TB meningitis) is the most severe form of tuberculosis (TB), requiring 12 months of multidrug treatment for cure, and is associated with high morbidity and mortality. High-dose rifampin (35 mg/kg/d) is safe and improves the bactericidal activity of the standard-dose (10 mg/kg/d) rifampin-containing TB regimen in pulmonary TB. However, there are conflicting clinical data regarding its benefit for TB meningitis, where outcomes may also be associated with intracerebral inflammation. We conducted cross-species studies in mice and rabbits, demonstrating that an intensified high-dose rifampin-containing regimen has significantly improved bactericidal activity for TB meningitis over the first-line, standard-dose rifampin regimen, without an increase in intracerebral inflammation. Positron emission tomography in live animals demonstrated spatially compartmentalized, lesion-specific pathology, with postmortem analyses showing discordant brain tissue and cerebrospinal fluid rifampin levels and inflammatory markers. Longitudinal multimodal imaging in the same cohort of animals during TB treatment as well as imaging studies in two cohorts of TB patients demonstrated that spatiotemporal changes in localized blood-brain barrier disruption in TB meningitis are an important driver of rifampin brain exposure. These data provide unique insights into the mechanisms underlying high-dose rifampin in TB meningitis with important implications for developing new antibiotic treatments for infections.
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Rifampin , Tuberculosis Meníngea , Animales , Antituberculosos , Humanos , Inflamación/complicaciones , Inflamación/tratamiento farmacológico , Ratones , Modelos Animales , Conejos , Rifampin/uso terapéutico , Tuberculosis Meníngea/complicaciones , Tuberculosis Meníngea/tratamiento farmacológicoRESUMEN
PURPOSE: Molecular imaging has provided unparalleled opportunities to monitor disease processes, although tools for evaluating infection remain limited. Coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is mediated by lung injury that we sought to model. Activated macrophages/phagocytes have an important role in lung injury, which is responsible for subsequent respiratory failure and death. We performed pulmonary PET/CT with 124I-iodo-DPA-713, a low-molecular-weight pyrazolopyrimidine ligand selectively trapped by activated macrophages cells, to evaluate the local immune response in a hamster model of SARS-CoV-2 infection. PROCEDURES: Pulmonary 124I-iodo-DPA-713 PET/CT was performed in SARS-CoV-2-infected golden Syrian hamsters. CT images were quantified using a custom-built lung segmentation tool. Studies with DPA-713-IRDye680LT and a fluorescent analog of DPA-713 as well as histopathology and flow cytometry were performed on post-mortem tissues. RESULTS: Infected hamsters were imaged at the peak of inflammatory lung disease (7 days post-infection). Quantitative CT analysis was successful for all scans and demonstrated worse pulmonary disease in male versus female animals (P < 0.01). Increased 124I-iodo-DPA-713 PET activity co-localized with the pneumonic lesions. Additionally, higher pulmonary 124I-iodo-DPA-713 PET activity was noted in male versus female hamsters (P = 0.02). DPA-713-IRDye680LT also localized to the pneumonic lesions. Flow cytometry demonstrated a higher percentage of myeloid and CD11b + cells (macrophages, phagocytes) in male versus female lung tissues (P = 0.02). CONCLUSION: 124I-Iodo-DPA-713 accumulates within pneumonic lesions in a hamster model of SARS-CoV-2 infection. As a novel molecular imaging tool, 124I-Iodo-DPA-713 PET could serve as a noninvasive, clinically translatable approach to monitor SARS-CoV-2-associated pulmonary inflammation and expedite the development of novel therapeutics for COVID-19.
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Acetamidas/química , COVID-19/diagnóstico por imagen , COVID-19/veterinaria , Radioisótopos de Yodo/química , Tomografía de Emisión de Positrones , Pirazoles/química , Pirimidinas/química , SARS-CoV-2/fisiología , Animales , Chlorocebus aethiops , Cricetinae , Modelos Animales de Enfermedad , Pulmón/diagnóstico por imagen , Pulmón/patología , Pulmón/virología , Tomografía Computarizada por Tomografía de Emisión de Positrones , Células VeroRESUMEN
Surgery is an efficient way to treat localized prostate cancer (PCa), however, it is challenging to demarcate rapidly and accurately the tumor boundary intraoperatively, as existing tumor detection methods are seldom performed in real-time. To overcome those limitations, we develop a fluorescent molecular rotor that specifically targets the prostate-specific membrane antigen (PSMA), an established marker for PCa. The probes have picomolar affinity (IC50 = 63-118 pM) for PSMA and generate virtually instantaneous onset of robust fluorescent signal proportional to the concentration of the PSMA-probe complex. In vitro and ex vivo experiments using PCa cell lines and clinical samples, respectively, indicate the utility of the probe for biomedical applications, including real-time monitoring of endocytosis and tumor staging. Experiments performed in a PCa xenograft model reveal suitability of the probe for imaging applications in vivo.
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Antígenos de Superficie/metabolismo , Glutamato Carboxipeptidasa II/metabolismo , Sondas Moleculares/metabolismo , Imagen Óptica/métodos , Neoplasias de la Próstata/metabolismo , Animales , Antígenos de Superficie/química , Sitios de Unión , Línea Celular Tumoral , Endocitosis , Glutamato Carboxipeptidasa II/química , Humanos , Masculino , Ratones Endogámicos BALB C , Ratones Desnudos , Modelos Moleculares , Sondas Moleculares/química , Células PC-3 , Neoplasias de la Próstata/diagnóstico , Unión Proteica , Dominios Proteicos , Espectrometría de Fluorescencia/métodos , Trasplante HeterólogoRESUMEN
Prostate-Specific Membrane Antigen (PSMA) is an established biomarker for the imaging and experimental therapy of prostate cancer (PCa), as it is strongly upregulated in high-grade primary, androgen-independent, and metastatic lesions. Here, we report on the development and functional characterization of recombinant single-chain Fv (scFv) and Fab fragments derived from the 5D3 PSMA-specific monoclonal antibody (mAb). These fragments were engineered, heterologously expressed in insect S2 cells, and purified to homogeneity with yields up to 20 mg/L. In vitro assays including ELISA, immunofluorescence and flow cytometry, revealed that the fragments retain the nanomolar affinity and single target specificity of the parent 5D3 antibody. Importantly, using a murine xenograft model of PCa, we verified the suitability of fluorescently labeled fragments for in vivo imaging of PSMA-positive tumors and compared their pharmacokinetics and tissue distribution to the parent mAb. Collectively, our data provide an experimental basis for the further development of 5D3 recombinant fragments for future clinical use.
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Anticuerpos Monoclonales/inmunología , Antígenos de Superficie/inmunología , Glutamato Carboxipeptidasa II/inmunología , Neoplasias de la Próstata/inmunología , Animales , Línea Celular , Línea Celular Tumoral , Fluorescencia , Humanos , Insectos , Masculino , Ratones , Ratones Desnudos , Células PC-3 , Proteínas Recombinantes/inmunología , Anticuerpos de Cadena Única/inmunología , Ensayos Antitumor por Modelo de Xenoinjerto/métodosRESUMEN
PURPOSE: Imaging is limited in the evaluation of bacterial infection. Direct imaging of in situ bacteria holds promise for noninvasive diagnosis. We investigated the ability of a bacterial thymidine kinase inhibitor ([124I]FIAU) to image pulmonary and musculoskeletal infections. METHODS: Thirty-three patients were prospectively accrued: 16 with suspected musculoskeletal infection, 14 with suspected pulmonary infection, and 3 with known rheumatoid arthritis without infection. Thirty-one patients were imaged with [124I]FIAU PET/CT and 28 with [18F]FDG PET/CT. Patient histories were reviewed by an experienced clinician with subspecialty training in infectious diseases and were determined to be positive, equivocal, or negative for infection. RESULTS: Sensitivity, specificity, positive-predictive value, negative-predictive value, and accuracy of [124I]FIAU PET/CT for diagnosing infection were estimated as 7.7% to 25.0%, 0.0%, 50%, 0.0%, and 20.0% to 71.4% for musculoskeletal infections and incalculable-100.0%, 51.7% to 72.7%, 0.0% to 50.0%, 100.0%, and 57.1% to 78.6% for pulmonary infections, respectively. The parameters for [18F]FDG PET/CT were 75.0% to 92.3%, 0.0%, 23.1% to 92.3%, 0.0%, and 21.4% to 85.7%, respectively, for musculoskeletal infections and incalculable to 100.0%, 0.0%, 0.0% to 18.2%, incalculable, and 0.0% to 18.2% for pulmonary infections, respectively. CONCLUSIONS: The high number of patients with equivocal clinical findings prevented definitive conclusions from being made regarding the diagnostic efficacy of [124I]FIAU. Future studies using microbiology to rigorously define infection in patients and PET radiotracers optimized for image quality are needed.
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Arabinofuranosil Uracilo/análogos & derivados , Infecciones Bacterianas/diagnóstico por imagen , Radioisótopos de Yodo/química , Enfermedades Musculoesqueléticas/diagnóstico por imagen , Enfermedades Musculoesqueléticas/microbiología , Tomografía Computarizada por Tomografía de Emisión de Positrones , Infecciones del Sistema Respiratorio/diagnóstico por imagen , Infecciones del Sistema Respiratorio/microbiología , Adulto , Anciano , Anciano de 80 o más Años , Arabinofuranosil Uracilo/química , Femenino , Fluorodesoxiglucosa F18/química , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Sensibilidad y EspecificidadRESUMEN
DO (HLA-DO, in human; murine H2-O) is a highly conserved nonclassical major histocompatibility complex class II (MHC II) accessory molecule mainly expressed in the thymic medulla and B cells. Previous reports have suggested possible links between DO and autoimmunity, Hepatitis C (HCV) infection, and cancer, but the mechanism of how DO contributes to these diseases remains unclear. Here, using a combination of various in vivo approaches, including peptide elution, mixed lymphocyte reaction, T-cell receptor (TCR) deep sequencing, tetramer-guided naïve CD4 T-cell precursor enumeration, and whole-body imaging, we report that DO affects the repertoire of presented self-peptides by B cells and thymic epithelium. DO induces differential effects on epitope presentation and thymic selection, thereby altering CD4 T-cell precursor frequencies. Our findings were validated in two autoimmune disease models by demonstrating that lack of DO increases autoreactivity and susceptibility to autoimmune disease development.
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Enfermedades Autoinmunes/genética , Predisposición Genética a la Enfermedad/genética , Antígenos de Histocompatibilidad Clase II/genética , Animales , Células Presentadoras de Antígenos/inmunología , Enfermedades Autoinmunes/inmunología , Autoinmunidad/genética , Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Colágeno/administración & dosificación , Colágeno/inmunología , Modelos Animales de Enfermedad , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Glicoproteína Mielina-Oligodendrócito/inmunología , Péptidos/inmunología , Células Precursoras de Linfocitos T/inmunología , Timo/inmunologíaRESUMEN
Analysis of human pathology led Braak to postulate that α-synuclein (α-syn) pathology could spread from the gut to brain via the vagus nerve. Here, we test this postulate by assessing α-synucleinopathy in the brain in a novel gut-to-brain α-syn transmission mouse model, where pathological α-syn preformed fibrils were injected into the duodenal and pyloric muscularis layer. Spread of pathologic α-syn in brain, as assessed by phosphorylation of serine 129 of α-syn, was observed first in the dorsal motor nucleus, then in caudal portions of the hindbrain, including the locus coeruleus, and much later in basolateral amygdala, dorsal raphe nucleus, and the substantia nigra pars compacta. Moreover, loss of dopaminergic neurons and motor and non-motor symptoms were observed in a similar temporal manner. Truncal vagotomy and α-syn deficiency prevented the gut-to-brain spread of α-synucleinopathy and associated neurodegeneration and behavioral deficits. This study supports the Braak hypothesis in the etiology of idiopathic Parkinson's disease (PD).
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Transporte Axonal , Trastornos Parkinsonianos/etiología , Agregado de Proteínas , Nervio Vago/metabolismo , alfa-Sinucleína/farmacocinética , Animales , Química Encefálica , Neuronas Dopaminérgicas/metabolismo , Neuronas Dopaminérgicas/patología , Duodeno/inervación , Duodeno/metabolismo , Humanos , Inyecciones Intramusculares , Cuerpos de Lewy/metabolismo , Aprendizaje por Laberinto , Trastornos de la Memoria/etiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Modelos Neurológicos , Músculo Liso/inervación , Músculo Liso/metabolismo , Comportamiento de Nidificación/fisiología , Trastornos Parkinsonianos/metabolismo , Trastornos Parkinsonianos/prevención & control , Trastornos Parkinsonianos/psicología , Fosforilación , Procesamiento Proteico-Postraduccional , Píloro/inervación , Píloro/metabolismo , Prueba de Desempeño de Rotación con Aceleración Constante , Vagotomía , alfa-Sinucleína/administración & dosificación , alfa-Sinucleína/deficiencia , alfa-Sinucleína/toxicidadRESUMEN
The prostate-specific membrane antigen (PSMA) is a validated target for detection and management of prostate cancer (PC). It has also been utilized for targeted drug delivery through antibody-drug conjugates and polymeric micelles. Polyamidoamine (PAMAM) dendrimers are emerging as a versatile platform in a number of biomedical applications due to their unique physicochemical properties, including small size, large number of reactive terminal groups, bulky interior void volume, and biocompatibility. Here, we report the synthesis of generation 4 PSMA-targeted PAMAM dendrimers [G4(MP-KEU)] and evaluation of their targeting properties in vitro and in vivo using an experimental model of PC. A facile, one-pot synthesis gave nearly neutral nanoparticles with a narrow size distribution of 5 nm in diameter and a molecular weight of 27.3 kDa. They exhibited in vitro target specificity with a dissociation constant ( Kd) of 0.32 ± 0.23 µm and preferential accumulation in PSMA+ PC3 PIP tumors versus isogenic PSMA- PC3 flu tumors. Positron emission tomography-computed tomography imaging and ex vivo biodistribution studies of dendrimers radiolabeled with 64Cu, [64Cu]G4(MP-KEU), demonstrated high accumulation in PSMA+ PC3 PIP tumors at 24 h post-injection (45.83 ± 20.09% injected dose per gram of tissue, %ID/g), demonstrating a PSMA+ PC3 PIP/PSMA- PC3 flu ratio of 7.65 ± 3.35. Specific accumulation of G4(MP-KEU) and [64Cu]G4(MP-KEU) in PSMA+ PC3 PIP tumors was inhibited by the known small-molecule PSMA inhibitor, ZJ-43. On the contrary, G4(Ctrl), control dendrimers without PSMA-targeting moieties, showed comparable low accumulation of â¼1%ID/g in tumors irrespective of PSMA expression, further confirming PSMA+ tumor-specific uptake of G4(MP-KEU). These results suggest that G4(MP-KEU) may represent a suitable scaffold by which to target PSMA-expressing tissues with imaging and therapeutic agents.
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Dendrímeros/química , Nanopartículas/química , Neoplasias de la Próstata/diagnóstico por imagen , Animales , Masculino , Ratones , Micelas , Imagen Molecular/métodos , Tomografía de Emisión de PositronesRESUMEN
PURPOSE: Prostate carcinoma consists of tumor epithelium and malignant stroma. Until recently, diagnostic and therapeutic efforts have focused exclusively on targeting characteristics of the tumor epithelium, ignoring opportunities to target inflammatory infiltrate and extracellular matrix components. Prostate tumors are rich in tumor-associated macrophages (TAMs), which can be either of the cytotoxic M1 or protumorigenic M2 phenotype. We have quantified the proportion of each in seven common human prostate tumor lines grown subcutaneously in athymic nude mice and have imaged macrophage densities in vivo in xenografts derived from these lines. PROCEDURES: A panel of seven human prostate cancer xenografts was generated in intact male athymic nude mice reflecting variable expression of the androgen receptor (AR) and prostate-specific membrane antigen (PSMA). Mice were imaged ex vivo using near-infrared fluorescence (NIRF) imaging for PSMA expression and total macrophage densities to enable direct comparison between the two. Tumors were harvested for sectioning and additional staining to delineate M1 and M2 phenotype along with vascular density. RESULTS: Macrophage polarization analysis of sections revealed that all xenografts were > 94% M2 phenotype, and the few M1-polarized macrophages present were confined to the periphery. Xenografts displaying the fastest growth were associated with the highest densities of macrophages while the slowest growing tumors were characterized by focal, tumor-infiltrating macrophage densities. Xenograft sections displayed a strong positive spatial relationship between macrophages, vasculature, and PSMA expression. CONCLUSIONS: Prostate TAM disposition can be imaged ex vivo and is associated with growth characteristics of a variety of tumor subtypes regardless of PSMA or AR expression.
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Diagnóstico por Imagen , Macrófagos/patología , Neoplasias de la Próstata/patología , Acetamidas/química , Acetamidas/metabolismo , Animales , Bencenosulfonatos/química , Bencenosulfonatos/metabolismo , Línea Celular Tumoral , Proliferación Celular , Modelos Animales de Enfermedad , Epitelio/patología , Humanos , Indoles/química , Indoles/metabolismo , Masculino , Ratones Desnudos , Fenotipo , Antígeno Prostático Específico/metabolismo , Neoplasias de la Próstata/irrigación sanguínea , Pirazoles/química , Pirazoles/metabolismo , Pirimidinas/química , Pirimidinas/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
While neuroinflammation is an evolving concept and the cells involved and their functions are being defined, microglia are understood to be a key cellular mediator of brain injury and repair. The ability to measure microglial activity specifically and noninvasively would be a boon to the study of neuroinflammation, which is involved in a wide variety of neuropsychiatric disorders including traumatic brain injury, demyelinating disease, Alzheimer's disease (AD), and Parkinson's disease, among others. We have developed [11C]CPPC [5-cyano-N-(4-(4-[11C]methylpiperazin-1-yl)-2-(piperidin-1-yl)phenyl)furan-2-carboxamide], a positron-emitting, high-affinity ligand that is specific for the macrophage colony-stimulating factor 1 receptor (CSF1R), the expression of which is essentially restricted to microglia within brain. [11C]CPPC demonstrates high and specific brain uptake in a murine and nonhuman primate lipopolysaccharide model of neuroinflammation. It also shows specific and elevated uptake in a murine model of AD, experimental allergic encephalomyelitis murine model of demyelination and in postmortem brain tissue of patients with AD. Radiation dosimetry in mice indicated [11C]CPPC to be safe for future human studies. [11C]CPPC can be synthesized in sufficient radiochemical yield, purity, and specific radioactivity and possesses binding specificity in relevant models that indicate potential for human PET imaging of CSF1R and the microglial component of neuroinflammation.
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Factor Estimulante de Colonias de Macrófagos/metabolismo , Microglía/metabolismo , Receptores de Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Enfermedad de Alzheimer/metabolismo , Animales , Encéfalo/metabolismo , Modelos Animales de Enfermedad , Inflamación/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Placa Amiloide/metabolismo , Tomografía de Emisión de Positrones/métodos , Primates , Radiofármacos/metabolismoRESUMEN
PURPOSE: Diagnosis and therapeutic monitoring of chronic bacterial infection requires methods to detect and localize sites of infection accurately. Complement C3 activation fragments are generated and covalently bound to selective bacterial pathogens during the immune response and can serve as biomarkers of ongoing bacterial infection. We have developed several probes for detecting tissue-bound C3 deposits, including a monoclonal antibody (mAb 3d29) that recognizes the tissue-bound terminal processing fragments iC3b and C3d but does not recognize native circulating C3 or tissue-bound C3b. PROCEDURES: To determine whether mAb 3d29 could be used to detect chronic Mycobacterium tuberculosis infection non-invasively, aerosol-infected female C3HeB/FeJ mice were injected with [125I]3d29 mAb and either imaged using single-photon emission computed tomography (SPECT)/X-ray computed tomography (CT) imaging at 24 and 48 h after radiotracer injection or being subjected to biodistribution analysis. RESULTS: Discrete lesions were detected by SPECT/CT imaging in the lungs and spleens of infected mice, consistent with the location of granulomas in the infected animals as detected by CT. Low-level signal was seen in the spleens of uninfected mice and no signal was seen in the lungs of healthy mice. Immunofluorescence microscopy revealed that 3d29 in the lungs of infected mice co-localized with aggregates of macrophages (detected with anti-CD68 antibodies). 3d29 was detected in the cytoplasm of macrophages, consistent with the location of internalized M. tuberculosis. 3d29 was also present within alveolar epithelial cells, indicating that it detected M. tuberculosis phagocytosed by other CD68-positive cells. Healthy controls showed very little retention of fluorescent or radiolabeled antibody across tissues. Radiolabeled 3d29 compared with radiolabeled isotype control showed a 3.5:1 ratio of increased uptake in infected lungs, indicating specific uptake by 3d29. CONCLUSION: 3d29 can be used to detect and localize areas of infection with M. tuberculosis non-invasively by 24 h after radiotracer injection and with high contrast.
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Anticuerpos Monoclonales/metabolismo , Complemento C3/inmunología , Radioisótopos de Yodo/química , Mycobacterium tuberculosis/fisiología , Tomografía Computarizada por Tomografía Computarizada de Emisión de Fotón Único , Tuberculosis/diagnóstico por imagen , Animales , Femenino , Inmunoglobulina G/metabolismo , Pulmón/diagnóstico por imagen , Pulmón/microbiología , Pulmón/patología , Ratones , Distribución Tisular , Tuberculosis/microbiología , Tuberculosis/patologíaRESUMEN
PURPOSE: Foreign body reactions elicit granulomatous inflammation composed of reactive macrophages. We hypothesized that [125I]iodo-DPA-713 single-photon emission computed tomography (SPECT), a low-molecular-weight pyrazolopyrimidine ligand selectively trapped by phagocytes, could be used to detect foreign body reactions in a murine model. PROCEDURES: C57BL/6 mice intratracheally inoculated with dextran beads, which developed foreign body lesions, were imaged after injection of [125I]iodo-DPA-713 or DPA-713-IRDye800CW using SPECT and optical imaging, respectively. RESULTS: Foreign body lesions were clearly observed in the lungs of the dextran-treated mice on computer tomography imaging and demonstrated significantly higher [125I]iodo-DPA-713 uptake compared with control animals (p < 0.01). Ex vivo studies demonstrated granulomatous reactions in the lungs of dextran-treated mice and localization of DPA-713-IRDye800CW at the diseased sites confirming the imaging findings. CONCLUSION: Radioiodinated DPA-713 may be used as a noninvasive biomarker for the detection of pulmonary foreign body reactions.
Asunto(s)
Acetamidas/química , Reacción a Cuerpo Extraño/diagnóstico por imagen , Radioisótopos de Yodo/química , Pirazoles/química , Pirimidinas/química , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos X , Animales , Femenino , Pulmón/diagnóstico por imagen , Pulmón/patología , Ratones Endogámicos C57BL , Imagen ÓpticaRESUMEN
Whole-body PET/CT was performed using 124I-DPA-713, a radioligand for the 18-kDa translocator protein (TSPO), to determine biodistribution and radiation dosimetry. Methods: Healthy subjects aged 18-65 y underwent whole-body PET/CT either at 4, 24, and 48 h or at 24, 48, and 72 h after intravenous injection of 124I-DPA-713. Time-activity curves were generated and used to calculate organ time-integrated activity coefficients for each subject. The resulting time-integrated activity coefficients provided input data for calculation of organ absorbed doses and effective dose for each subject using OLINDA. Subjects were genotyped for the TSPO polymorphism rs6971, and plasma protein binding of 124I-DPA-713 was measured. Results: Three male and 3 female adults with a mean age of 40 ± 19 y were imaged. The mean administered activity and mass were 70.5 ± 5.1 MBq (range, 62.4-78.1 MBq) and 469 ± 34 ng (range, 416-520 ng), respectively. There were no adverse or clinically detectable pharmacologic effects in any of the 6 subjects. No changes in vital signs, laboratory values, or electrocardiograms were observed. 124I-DPA-713 cleared rapidly (4 h after injection) from the lungs, with hepatic elimination and localization to the gastrointestinal tract. The mean effective dose over the 6 subjects was 0.459 ± 0.127 mSv/MBq, with the liver being the dose-limiting organ (0.924 ± 0.501 mGy/MBq). The percentage of free radiotracer in blood was approximately 30% at 30 and 60 min after injection. Conclusion:124I-DPA-713 clears rapidly from the lungs, with predominantly hepatic elimination, and is safe and well tolerated in healthy adults.
Asunto(s)
Acetamidas , Inflamación/diagnóstico por imagen , Inflamación/inmunología , Macrófagos/inmunología , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Pirazoles , Pirimidinas , Radiofármacos , Acetamidas/administración & dosificación , Acetamidas/farmacocinética , Adulto , Femenino , Genotipo , Voluntarios Sanos , Humanos , Inflamación/metabolismo , Radioisótopos de Yodo/administración & dosificación , Radioisótopos de Yodo/farmacocinética , Macrófagos/metabolismo , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Pirazoles/administración & dosificación , Pirazoles/farmacocinética , Pirimidinas/administración & dosificación , Pirimidinas/farmacocinética , Dosis de Radiación , Ensayo de Unión Radioligante , Radiofármacos/administración & dosificación , Radiofármacos/farmacocinética , Receptores de GABA/genética , Receptores de GABA/metabolismo , Distribución Tisular , Imagen de Cuerpo Entero/métodos , Adulto JovenRESUMEN
Macrophages belong to the mononuclear phagocyte system comprising closely related cells of bone marrow origin. Activated macrophages are critical in several diseases such as tuberculosis, sarcoidosis, Crohn's disease, and atherosclerosis. Noninvasive imaging techniques that can specifically image activated macrophages could therefore help in differentiating various forms of inflammatory diseases and to monitor therapeutic responses.
Asunto(s)
Inflamación/diagnóstico por imagen , Inflamación/inmunología , Macrófagos/metabolismo , Imagen Molecular/métodos , Animales , HumanosRESUMEN
Intracerebral hemorrhage (ICH) is a fatal stroke subtype with significant public health impact. Although neuroinflammation is a leading cause of neurological deficits after ICH, no imaging tool is currently available to monitor brain inflammation in ICH patients. Given the role of TSPO in neuroinflammation, herein we investigate whether a second-generation TSPO ligand, [125 I]IodoDPA-713 can be used to monitor the changes in TSPO expression in a preclinical model of intracerebral hemorrhage. Male CD1 mice were subjected to ICH/Sham. The brain sections, collected at different time points were incubated with [125 I]IodoDPA-713 and the brain uptake of [125 I]IodoDPA-713 was estimated using autoradiography. The specificity of [125 I]IodoDPA-713 binding was confirmed by a competitive displacement study with an unlabeled TSPO ligand, PK11195. [125 I]IodoDPA-713 binding was higher in the ipsilateral striatum with an enhanced binding observed in the peri-hematomal brain region after ICH, whereas the brain sections from sham as well as contralateral brain areas of ICH exhibited marginal binding of [125 I]IodoDPA-713. PK11195 completely reversed the [125 I] IodoDPA-713 binding to brain sections suggesting a specific TSPO-dependent binding of [125 I]IodoDPA-713 after ICH. This was further confirmed with immunohistochemistry analysis of adjacent sections, which revealed a remarkable expression of TSPO in the areas of high [125 I]IodoDPA-713 binding after ICH. The specific as well as enhanced binding of [125 I]IodoDPA-713 to the ipsilateral brain areas after ICH as assessed by autoradiography analysis provides a strong rationale for testing the applicability of [125 I]IodoDPA-713 for non-invasive neuroimaging in preclinical models of ICH.
RESUMEN
Changes in inflammatory cascades have been implicated in the underlying pathophysiology of psychosis. Translocator protein 18â¯kDa (TSPO) has been used to assess neuroinflammatory processes in psychotic disorders. Nonetheless, it is unclear whether TSPO, a mitochondrial protein, can be interpreted as a general marker for inflammation in diseases involving psychosis. To address this question, we investigated TSPO signaling in representative mouse models for psychosis with inflammatory disturbances. The maternal immune activation and cuprizone short-term exposure models show different TSPO signaling. Furthermore, we observed similarities and differences in their respective stress pathways including stress hormone signaling and oxidative stress that are functionally interconnected with the inflammatory responses. We propose that more careful studies of TSPO distribution in neuroinflammation and other stress cascades associated with psychotic symptoms will allow us to understand the biological mechanisms underlying psychosis-related behaviors.