RESUMEN
Despite as yet limited clinical effectiveness, dendritic cell (DC)-based immunotherapy remains a promising approach for the treatment of cancer, but requires further improvement in its immunostimulatory effectiveness. Potent anti-tumor immunity often depends on the induction of type 1 (T(H)1) immune responses. Therefore, we combined different DC maturation stimuli that are known to induce T(H)1 immunity [anti-CD40, interleukin (IL)-12, IL-18], with the aim to trigger a T(H)1 driven anti-tumor CTL response. When compared with untreated DC or DC treated with anti-CD40 alone, DC matured with anti-CD40 plus IL-12 and IL-18 expressed significantly more IFN-gamma and IL-12, induced enhanced CD8(+) T-cell proliferation, prolonged synaptic interaction with T cells and increased CD8(+) T-cell-mediated cytotoxicity. To analyse if these DC are able to induce efficient anti-tumor immunity, mice carrying a B16-OVA tumor were treated with tumor antigen (TA)-loaded DC that had been exposed to anti-CD40 or to anti-CD40 plus IL-12 and IL-18. Our data show that anti-CD40 plus IL-12 and IL-18 matured DC are superior to controls in retarding tumor growth. These data indicate that maturation of DC with anti-CD40 plus IL-12 and IL-18 potently stimulates the generation of an anti-tumor immune response and may lead to improved immunotherapeutic capacity of DC vaccination.
Asunto(s)
Antineoplásicos/farmacología , Antígenos CD40/metabolismo , Células Dendríticas/metabolismo , Inmunoterapia/métodos , Interleucina-12/metabolismo , Interleucina-18/metabolismo , Animales , Antígenos de Neoplasias/metabolismo , Linfocitos T CD8-positivos/metabolismo , Células Dendríticas/citología , Sistema Inmunológico , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Modelos Biológicos , Células TH1/metabolismoRESUMEN
Neuropathological, epidemiological and experimental data indicate a potential interrelationship between Alzheimer's disease and prion diseases. Proteolytic processing of amyloid precursor protein (APP) by beta-secretase was recently suggested to be controlled by prion protein expression. Here, we characterized the prion infection of Tg2576 mice, which overexpress the human APP(Swe) protein. Prion infection of Tg2576-mice led to an early death of the animals, which was preceded by a relatively short symptomatic stage. However, disease-associated gliosis and deposition of misfolded prion protein PrP(Sc) were identical in infected Tg2576-mice and non-transgenic littermate controls. To analyze the effect of prion infection on APP processing and generation of beta-amyloid we determined cortical levels of SDS- and formic acid (FA)-extractable forms of beta-amyloid (1-40) and (1-42) by ELISA. Formic acid-extractable Abeta (1-42) levels were 10-fold higher in infected versus uninfected Tg2576 mice whereas other forms of Abeta were essentially unaffected by the prion infection. Hence, the experimental model demonstrates that a prion infection of the CNS promotes selectively formation of FA-extractable Abeta(1-42) in Tg2576 mice.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Corteza Cerebral/metabolismo , Fragmentos de Péptidos/metabolismo , Priones/metabolismo , Scrapie/metabolismo , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides/química , Péptidos beta-Amiloides/genética , Precursor de Proteína beta-Amiloide/genética , Animales , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Formiatos/química , Gliosis/genética , Gliosis/metabolismo , Gliosis/patología , Humanos , Ratones , Ratones Transgénicos , Degeneración Nerviosa/genética , Degeneración Nerviosa/metabolismo , Degeneración Nerviosa/fisiopatología , Neuroquímica/métodos , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Placa Amiloide/genética , Placa Amiloide/metabolismo , Placa Amiloide/patología , Proteínas PrPSc/genética , Proteínas PrPSc/metabolismo , Enfermedades por Prión/genética , Enfermedades por Prión/metabolismo , Enfermedades por Prión/fisiopatología , Scrapie/genética , Scrapie/fisiopatología , Tasa de Supervivencia , Regulación hacia Arriba/genéticaRESUMEN
UV radiation-induced immunosuppression contributes significantly to the development of UV-induced skin cancer by inhibiting protective immune responses. IL-10 has been shown to be a key mediator of UV-induced immunosuppression. To investigate the role of IL-10 during photocarcinogenesis, groups of IL-10(+/+), IL-10(+/-), and IL-10(-/-) mice were chronically irradiated with UV. IL-10(+/+) and IL-10(+/-) mice developed skin cancer to similar extents, whereas IL-10(-/-) mice were protected against the induction of skin malignancies by UV. Because UV is able to induce regulatory T cells, which play a role in the suppression of protective immunity, UV-induced regulatory T cell function was analyzed. Splenic regulatory T cells from UV-irradiated IL-10(-/-) mice were unable to confer immunosuppression upon transfer into naive recipients. UV-induced CD4+CD25+ T cells from IL-10(-/-) mice showed impaired suppressor function when cocultured with conventional CD4+CD25- T cells. CD4+CD25- T cells from IL-10(-/-) mice produced increased amounts of IFN-gamma and enhanced numbers of CD4+TIM-3+ T cells were detectable within UV-induced tumors in IL-10(-/-) mice, suggesting strong Th1-driven immunity. Mice treated with CD8+ T cells from UV-irradiated IL-10(-/-) mice rejected a UV tumor challenge significantly faster, and augmented numbers of granzyme A+ cells were detected within injected UV tumors in IL-10(-/-) animals, suggesting marked antitumoral CTL responses. Together, these findings indicate that IL-10 is critically involved in antitumoral immunity during photocarcinogenesis. Moreover, these results point out the crucial role of Th1 responses and UV-induced regulatory T cell function in the protection against UV-induced tumor development.
Asunto(s)
Interleucina-10/fisiología , Neoplasias Inducidas por Radiación/inmunología , Neoplasias Cutáneas/inmunología , Rayos Ultravioleta , Animales , Citocinas/biosíntesis , Tolerancia Inmunológica/genética , Tolerancia Inmunológica/efectos de la radiación , Interleucina-10/deficiencia , Interleucina-10/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Desnudos , Neoplasias Inducidas por Radiación/genética , Neoplasias Inducidas por Radiación/patología , Neoplasias Inducidas por Radiación/prevención & control , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/prevención & control , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/patología , Linfocitos T Reguladores/efectos de la radiaciónRESUMEN
Regulatory CD4(+)CD25(+) T cells are important in suppressing immune responses. The requirements for the maintenance of peripheral CD4(+)CD25(+) T cells remain incompletely understood. Receptor activator of NF-kappaB (RANK) and its ligand (RANKL; also known as CD254, OPGL and TRANCE) are key regulators of bone remodeling, mammary gland formation, lymph node development and T-cell/dendritic cell communication. Here we report that RANKL is expressed in keratinocytes of the inflamed skin. RANKL overexpression in keratinocytes resulted in functional alterations of epidermal dendritic cells and systemic increases of regulatory CD4(+)CD25(+) T cells. Thus, epidermal RANKL expression can change dendritic cell functions to maintain the number of peripheral CD4(+)CD25(+) regulatory T cells. Epidermal RANKL mediated ultraviolet-induced immunosuppression and overexpression of epidermal RANKL suppressed allergic contact hypersensitivity responses and the development of systemic autoimmunity. Therefore, environmental stimuli at the skin can rewire the local and systemic immune system by means of RANKL.
Asunto(s)
Células Dendríticas/fisiología , Epidermis/fisiología , Ligando RANK/fisiología , Linfocitos T Reguladores/citología , Animales , Autoinmunidad , Recuento de Células , Células Epidérmicas , Epidermis/metabolismo , Tolerancia Inmunológica/efectos de la radiación , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Transgénicos , Ligando RANK/genética , Ligando RANK/metabolismo , Rayos UltravioletaRESUMEN
Increased expression of interleukin (IL)-1beta has been found in Alzheimer brain, raising the question whether plaque-associated up-regulation of IL-1beta may contribute to neurodegeneration. IL-1beta is capable to induce a number of events that also occur in Alzheimer's disease such as stimulation of the amyloidogenic pathway of amyloid precursor protein processing. However, less is known on participation of IL-1beta in specific cholinergic cell loss. To reveal whether IL-1beta affects muscarinic acetylcholine receptor (mAChR)-mediated intracellular signaling, cholinergically differentiated SH-SY5Y cells were exposed to IL-1beta for various periods of time followed by stimulation of mAChR with carbachol for 1 h, and key molecules of cholinergic signaling cascades were determined including phosphoinositide hydrolysis, DNA-binding capacity of NFkappaB and AP-1, and activity of acetylcholinesterase (AChE). Carbachol stimulation of SH-SY5Y cells dose-dependently stimulated the activation of the transcription factors NFkappaB and AP-1 as revealed by electrophoretic mobility shift assay (EMSA), while pre-exposure of SH-SY5Y cells for 24 h with 1 ng/ml IL-1beta completely suppressed the carbachol response. mAChR-mediated enhancements of AChE activity by carbachol were impaired following pre-exposure of SH-SY5Y cells with IL-1beta, already detectable at a concentration of 1 ng/ml and 1 h of exposure time. The data indicate that IL-1beta may interfere with the cholinergic signal transduction cascade by inhibiting transcription factor activation, thus providing another mechanism by which IL-1beta may induce cholinergic dysfunction in Alzheimer's disease.
Asunto(s)
Interleucina-1beta/metabolismo , Neuronas/metabolismo , Receptores Muscarínicos/metabolismo , Sistemas de Mensajero Secundario/fisiología , Transducción de Señal/fisiología , Acetilcolinesterasa/metabolismo , Enfermedad de Alzheimer/metabolismo , Carbacol/administración & dosificación , Agonistas Colinérgicos/administración & dosificación , Relación Dosis-Respuesta a Droga , Humanos , Hidrólisis , FN-kappa B/metabolismo , Neuroblastoma , Neuronas/citología , Neuronas/efectos de los fármacos , Fosfatidilinositoles/metabolismo , Receptores Muscarínicos/efectos de los fármacos , Sistemas de Mensajero Secundario/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Factor de Transcripción AP-1/metabolismo , Células Tumorales CultivadasRESUMEN
Autoimmunity results from loss of mechanisms controlling self-reactivity. Autoimmune disorders play an increasingly important role and CD40-CD40 ligand (CD40L) interaction on immunocompentent cells is able to break established immunotolerance. To study the effects of the calcineurin-inhibitor FK506 on CD40L-induced systemic autoimmunity, CD40L transgenic (tg) mice, which spontaneously develop a mixed connective tissue-like disease, were treated with FK506 after onset of overt autoimmunity. Interestingly, FK506-treated CD40L tg mice showed significantly reduced autoimmune dermatitis scores and markedly decreased numbers of lesional infiltrating leukocytes. This finding was associated with diminished lymphadenopathy induced by FK506 treatment. Furthermore, FK506 suppressed the development of cytotoxic/autoreactive CD8(+) T cells as evidenced by the reduced expression of T cell activation markers in treated CD40L tg mice. Importantly, FK506 induced a significant reduction in autoantibody titers in the serum of CD40L tg animals. As CD40L tg mice develop nephritis leading to loss of renal function proteinuria was determined after FK506 injections. Notably, FK506 treatment re-established renal function as indicated by significantly reduced uric protein concentrations of treated CD40L tg mice. Together, these findings show the beneficial therapeutic effects of FK506 for the treatment of CD40L-induced autoimmunity. Additionally, these results demonstrate that FK506 is able to suppress ongoing severe autoimmune responses.
Asunto(s)
Enfermedades Autoinmunes/prevención & control , Ligando de CD40/genética , Dermatitis/prevención & control , Inmunosupresores/uso terapéutico , Tacrolimus/uso terapéutico , Animales , Autoanticuerpos/sangre , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/inmunología , Autoinmunidad/efectos de los fármacos , Autoinmunidad/genética , Autoinmunidad/inmunología , Ligando de CD40/inmunología , Inhibidores de la Calcineurina , Núcleo Celular/inmunología , Dermatitis/genética , Dermatitis/inmunología , Femenino , Ratones , Ratones Transgénicos , Linfocitos T Citotóxicos/efectos de los fármacosRESUMEN
The molecular mechanisms of beta-amyloidogenesis in sporadic Alzheimer's disease are still poorly understood. To reveal whether aging-associated increases in brain oxidative stress and inflammation may trigger onset or progression of beta-amyloid deposition, a transgenic mouse (Tg2576) that express the Swedish double mutation of human amyloid precursor protein (APP) was used as animal model to study the developmental pattern of markers of oxidative stress and APP processing. In Tg2576 mouse brain, cortical levels of soluble beta-amyloid (1-40) and (1-42) steadily increased with age, but significant deposition of fibrillary beta-amyloid in cortical areas did not occur before postnatal age of 10 months. The slope of increase in cerebral cortical beta-secretase (BACE1) activities in Tg2576 mice between ages of 9 and 13 months was significantly higher as compared to that of the alpha-secretase, while the expression level of BACE1 protein and mRNA did not change with age. The activities of superoxide dismutase and glutathione peroxidase in cortical tissue from Tg2576 mice steadily increased from postnatal age 9-12 months. The levels of cortical nitric oxide, and reactive nitrogen species demonstrated peak values around 9 months of age, while the level of interleukin-1beta steadily increased from postnatal month 13 onwards. The developmental temporal coincidence of increased levels of reactive nitrogen species and antioxidative enzymes with the onset of beta-amyloid plaque deposition provides further evidence that developmentally and aging-induced alterations in brain oxidative status exhibit a major factor in triggering enhanced production and deposition of beta-amyloid, and potentially predispose to Alzheimer's disease.
Asunto(s)
Envejecimiento/metabolismo , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Encéfalo/metabolismo , Endopeptidasas/metabolismo , Placa Amiloide/metabolismo , Secretasas de la Proteína Precursora del Amiloide , Precursor de Proteína beta-Amiloide/genética , Animales , Animales Recién Nacidos , Antioxidantes/metabolismo , Ácido Aspártico Endopeptidasas , Ratones , Ratones Transgénicos , Mutación , Estrés Oxidativo , Oxidorreductasas/metabolismo , Estadística como AsuntoRESUMEN
IL-15 is involved in lymphocyte homeostasis. To investigate the role of IL-15 in the skin in vivo, mice were generated that overexpress IL-15 in keratinocytes, resulting in increased IL-15 protein levels in the skin but not elevated IL-15 serum concentrations. Keratin 14 (K14)-IL-15 transgenic (tg) mice showed increased contact hypersensitivity (CHS) responses. Transfer of primed wild-type (wt) and tg T cells into naive wt or tg recipients indicated that skin-derived IL-15 enhanced the induction but not the elicitation phase of CHS. Tg mice could be sensitized even by suboptimal hapten concentrations. Accordingly, Langerhans cells (LC) from tg skin were identified as potent allostimulators, suggesting the involvement of IL-15-stimulated LC in the induction of adaptive immunity. Overexpression of IL-15 also strengthened innate immunity since tg mice infected with human HSV type I developed significantly smaller HSV skin lesions. In addition, tg mice resisted re-infection with HSV more effectively than wt mice did, which was associated with an elevated anti-HSV Ab production. Accordingly, injection of serum from re-infected tg mice protected naive recipients significantly from epicutaneous HSV infection, indicating that anti-HSV Ab produced by tg mice play an important role in resistance in vivo. Together, our results show that overexpression of IL-15 in the epidermis enhances both innate and adaptive cutaneous immunity.
Asunto(s)
Dermatitis por Contacto/inmunología , Herpes Simple/inmunología , Herpesvirus Humano 1/inmunología , Interleucina-15/genética , Interleucina-15/inmunología , Queratinocitos/metabolismo , Piel/inmunología , Traslado Adoptivo , Alérgenos/inmunología , Animales , Presentación de Antígeno/inmunología , Dermatitis por Contacto/sangre , Dermatitis por Contacto/genética , Expresión Génica , Herpes Simple/sangre , Herpes Simple/prevención & control , Herpes Simple/virología , Herpesvirus Humano 1/fisiología , Humanos , Inmunidad Innata/inmunología , Memoria Inmunológica/inmunología , Interleucina-15/sangre , Interleucina-15/metabolismo , Células de Langerhans/inmunología , Ratones , Ratones Transgénicos , Fenotipo , Piel/citología , Piel/metabolismo , Linfocitos T Colaboradores-Inductores/inmunologíaRESUMEN
Cholinergic deficits in Alzheimer's disease are accompanied by a number of alterations in other transmitter systems including glutamate, noradrenaline and serotonin, suggesting the involvement also of other neurotransmitter systems in the pathogenesis of the disease. To address the question whether beta-amyloid may contribute to these deficits, brain tissue from transgenic Tg2576 mice with Alzheimer plaque pathology at ages of 5 (still no significant plaque load) and 17 months (moderate to high cortical beta-amyloid plaque load) were examined for a number of cholinergic and non-cholinergic markers. Transgenic mice with no significant plaque load demonstrated reduced hemicholinium-3 (HCh-3) binding to choline uptake sites in anterior brain regions as compared to non-transgenic littermates, while in aged transgenic mice with high number of plaque deposits decreased HCh-3 binding levels were accompanied by increased vesicular acetylcholine transporter binding in selected cortical brain regions. In aged transgenic mice GABA(A), NMDA, AMPA, kainate, and beta-adrenergic as well 5-HT(1A)- and 5-HT(2A)-receptor binding levels were hardly affected, whereas alpha(1)- and alpha(2)-adrenoceptor binding was increased in selected cerebral cortical regions as compared to non-transgenic littermates. The development of changes in both cholinergic and non-cholinergic markers in transgenic Tg2576 mouse brain already before the onset of progressive plaque deposition provides in vivo evidence of a modulatory role of soluble beta-amyloid on cortical neurotransmission and may be referred to the deficits in learning and memory observed in these mice also before significant plaque load.
Asunto(s)
Envejecimiento , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides/metabolismo , Corteza Cerebral/metabolismo , Neurotransmisores/metabolismo , Receptores Colinérgicos/metabolismo , Acetilcolina/metabolismo , Péptidos beta-Amiloides/genética , Animales , Colina/metabolismo , Síndrome de Adaptación General , Ratones , Ratones Transgénicos , Receptores Adrenérgicos/metabolismo , Receptores de GABA/metabolismo , Receptores de Glutamato/metabolismo , Receptores de Neurotransmisores/metabolismo , Transmisión Sináptica , Distribución TisularRESUMEN
Increased expression and altered processing of the amyloid precursor protein (APP) and generation of beta-amyloid peptides is important in the pathogenesis of amyloid plaques in Alzheimer's disease (AD). Transgenic Tg2576 mice overexpressing the Swedish mutation of human APP exhibit beta-amyloid deposition in the neocortex and limbic areas, accompanied by gliosis and dystrophic neurites. However, murine plaques appear to be less cross-linked and the mice show a lower degree of inflammation and neurodegeneration than AD patients. 'Advanced glycation endproducts (AGEs)', formed by reaction of proteins with reactive sugars or dicarbonyl compounds, are able to cross-link proteins and to activate glial cells, and are thus contributing to plaque stability and plaque-induced inflammation in AD. In this study, we analyze the tissue distribution of AGEs and the pro-inflammatory cytokines IL-1beta and TNF-alpha in 24-month-old Tg2576 mice, and compare the AGE distribution in these mice with a younger age group (13 months old) and a typical Alzheimer's disease patient. Around 70% of the amyloid plaque cores in the 24-month-old mice are devoid of AGEs, which might explain their solubility in physiological buffers. Plaque associated glia, which express IL-1beta and TNF-alpha, contain a significant amount of AGEs, suggesting that plaques, i.e. Abeta as its major component, can induce intracellular AGE formation and the expression of the cytokines on its own. In the 13-month-old transgenic mice, AGEs staining can neither be detected in plaques nor in glial cells. In contrast, AGEs are present in high amounts in both plaques and glia in the human AD patient. The data obtained in this show interesting differences between the transgenic mouse model and AD patients, which should be considered using the transgenic approach to test therapeutical strategies to eliminate plaques or to attenuate the inflammatory response in AD.
Asunto(s)
Enfermedad de Alzheimer/genética , Citocinas/metabolismo , Productos Finales de Glicación Avanzada/metabolismo , Placa Amiloide/metabolismo , Placa Amiloide/patología , Precursor de Proteína beta-Amiloide/genética , Animales , Encéfalo/metabolismo , Encéfalo/patología , Modelos Animales de Enfermedad , Humanos , Interleucina-1/metabolismo , Ratones , Ratones Transgénicos , Neuroglía/metabolismo , Neuroglía/patología , Neuronas/metabolismo , Neuronas/patología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Cholinergic dysfunction is a consistent feature of Alzheimer's disease, and the interrelationship between beta-amyloid deposits, inflammation and early cholinergic cell loss is still not fully understood. To characterize the mechanisms by which beta-amyloid and pro-inflammatory cytokines may exert specific degenerating actions on cholinergic cells ultrastructural investigations by electron microscopy were performed in brain sections from transgenic Tg2576 mice that express the Swedish double mutation of the human amyloid precursor protein and progressively develop beta-amyloid plaques during aging. Both light and electron microscopical investigations of the cerebral cortex of 19-month-old transgenic mice revealed a number of pathological tissue responses in close proximity of beta-amyloid plaques, such as activated microglia, astroglial proliferation, increased number of fibrous astrocytes, brain edema, degeneration of nerve cells, dendrites and axon terminals. Ultrastructural detection of choline acetyl transferase (ChAT)-immunostaining in cerebral cortical sections of transgenic mice clearly demonstrated degeneration of ChAT-immunoreactive fibres in the environment of beta-amyloid plaques and activated glial cells suggesting a role of beta-amyloid and/or inflammation in specific degeneration of cholinergic synaptic structures.
Asunto(s)
Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Corteza Cerebral/patología , Enfermedad de Alzheimer/metabolismo , Animales , Corteza Cerebral/metabolismo , Corteza Cerebral/ultraestructura , Colina O-Acetiltransferasa/metabolismo , Modelos Animales de Enfermedad , Espacio Extracelular/metabolismo , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Electrónica , Placa Amiloide/patología , Placa Amiloide/ultraestructuraRESUMEN
Pathological accumulation of cortical beta-amyloid is an early and consistent feature of Alzheimer's disease. Brain level of beta-amyloid is determined both by its production and by its catabolism. Neprilysin, a zinc metalloproteinase has been suggested as potential candidate of beta-amyloid-degrading enzyme in vivo. To address the question whether pathological accumulation of beta-amyloid peptides in transgenic Tg2576 mice with Alzheimer-like pathology may affect beta-amyloid catabolism, the expression of neprilysin was studied during postnatal maturation and aging. Neprilysin protein but mRNA levels decreased in mouse cerebral cortex with age (2-22 months), independently of transgene status. Immunocytochemistry revealed few neprilysin-positive dystrophic neurites around beta-amyloid plaques and an upregulation of neprilysin in plaque-surrounding reactive astrocytes which may suggest a role of plaque-mediated astrogliosis in beta-amyloid degradation.
Asunto(s)
Envejecimiento/fisiología , Enfermedad de Alzheimer/enzimología , Péptidos beta-Amiloides/metabolismo , Astrocitos/enzimología , Neprilisina/metabolismo , Placa Amiloide/enzimología , Envejecimiento/genética , Enfermedad de Alzheimer/genética , Péptidos beta-Amiloides/genética , Animales , Encéfalo/enzimología , Regulación hacia Abajo/fisiología , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Neprilisina/genética , Placa Amiloide/genética , Regulación hacia Arriba/fisiologíaRESUMEN
The beta-site APP-cleaving enzyme (BACE1) is a prerequisite for the generation of beta-amyloid peptides, which give rise to cerebrovascular and parenchymal beta-amyloid deposits in the brain of Alzheimer's disease patients. BACE1 is neuronally expressed in the brains of humans and experimental animals such as mice and rats. In addition, we have recently shown that BACE1 protein is expressed by reactive astrocytes in close proximity to beta-amyloid plaques in the brains of aged transgenic Tg2576 mice that overexpress human amyloid precursor protein carrying the double mutation K670N-M671L. To address the question whether astrocytic BACE1 expression is an event specifically triggered by beta-amyloid plaques or whether glial cell activation by other mechanisms also induces BACE1 expression, we used six different experimental strategies to activate brain glial cells acutely or chronically. Brain sections were processed for the expression of BACE1 and glial markers by double immunofluorescence labeling and evaluated by confocal laser scanning microscopy. There was no detectable expression of BACE1 protein by activated microglial cells of the ameboid or ramified phenotype in any of the lesion paradigms studied. In contrast, BACE1 expression by reactive astrocytes was evident in chronic but not in acute models of gliosis. Additionally, we observed BACE1-immunoreactive astrocytes in proximity to beta-amyloid plaques in the brains of aged Tg2576 mice and Alzheimer's disease patients.
Asunto(s)
Enfermedad de Alzheimer/enzimología , Péptidos beta-Amiloides/metabolismo , Ácido Aspártico Endopeptidasas/metabolismo , Astrocitos/enzimología , Encéfalo/enzimología , Gliosis/enzimología , Envejecimiento/metabolismo , Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/fisiopatología , Secretasas de la Proteína Precursora del Amiloide , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Animales Recién Nacidos , Astrocitos/citología , Encéfalo/patología , Encéfalo/fisiopatología , Isquemia Encefálica/enzimología , Isquemia Encefálica/patología , Isquemia Encefálica/fisiopatología , Células Cultivadas , Modelos Animales de Enfermedad , Encefalomielitis Autoinmune Experimental/enzimología , Encefalomielitis Autoinmune Experimental/patología , Encefalomielitis Autoinmune Experimental/fisiopatología , Endopeptidasas , Femenino , Gliosis/patología , Gliosis/fisiopatología , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Ratas , Ratas Endogámicas Lew , Ratas Endogámicas SHRRESUMEN
To address the question of whether beta-amyloid peptides also affect cholinergic neurotransmission in vivo, brain tissue from transgenic Tg2576 mice with Alzheimer plaque pathology at ages ranging from 7 to 24 months were examined by immuno- and histochemical staining for choline acetyltransferase (ChAT) and acetycholinesterase (AChE), by assaying cholinergic enzyme activities and high-affinity choline uptake as well muscarinic and nicotinic cholinergic receptor binding levels by quantitative autoradiography. Cortical and hippocampal activities of AChE and ChAT were not different between transgenic mice and non-transgenic littermates regardless of the postnatal ages examined. However, high-affinity choline uptake was reduced in the hippocampus of 21-month-old transgenic mice. In brains of 8-month-old transgenic mice which do not yet demonstrate cortical beta-amyloids, reduced binding levels of cortical and hippocampal M1-muscarinic cholinergic receptors were observed, which were still reduced in 17-month-old transgenic mouse brains with high plaque load as compared to non-transgenic littermates. M2-muscarinic cholinergic receptor binding was hardly affected in brains from 8-month-old transgenic mice, but in 17-month-old transgenic mice reduced cortical and hippocampal binding levels were observed as compared to non-transgenic controls. Decreased cortical nicotinic cholinergic receptor binding was detected in 17-month-old transgenic mice. The development of changes in cholinergic synaptic markers in transgenic Tg2576 mouse brain before the onset of progressive plaque deposition provides in vivo evidence of a modulatory role of soluble beta-amyloid on cholinergic neurotransmission and may be referred to the deficits in learning and memory also observed in these mice before significant plaque load.
Asunto(s)
Precursor de Proteína beta-Amiloide/genética , Encéfalo/enzimología , Mutación Puntual , Receptores Muscarínicos/metabolismo , Receptores Nicotínicos/metabolismo , Acetilcolinesterasa/análisis , Acetilcolinesterasa/metabolismo , Factores de Edad , Animales , Colina O-Acetiltransferasa/análisis , Colina O-Acetiltransferasa/metabolismo , Humanos , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Suecia , Transmisión Sináptica/genéticaRESUMEN
To study the relationship of beta-amyloid-mediated micro- and astrogliosis and inflammation-induced proteins including intercellular adhesion molecule (ICAM-1), brain tissue from transgenic Tg2576 mice expressing the Swedish mutation of the human amyloid precursor protein were examined for ICAM-1 expression. Immunocytochemistry demonstrated a diffuse immunostaining of ICAM-1 in the corona around fibrillary beta-amyloid plaques and an upregulation of ICAM-1 in activated microglial cells located in close proximity to the plaques, an ICAM-1 distribution pattern that partly mimics the situation in the brain of Alzheimer patients. The developmental time course revealed that the rate of cortical ICAM-1 induction was somewhat behind that of the progression of beta-amyloid plaque deposition. The microglial expression of ICAM-1 is a further indicator of the presence of inflammatory reactions in aged transgenic Tg2576 mouse brain, and may be a result of plaque-mediated astrocytic interleukin-1beta upregulation.