RESUMEN
TIAM Rac1-associated GEF 2 short form (TIAM2S) as an oncoprotein alters the immunity of peripheral immune cells to construct an inflammatory tumor microenvironment. However, its role in the activation of microglia, the primary innate immune cells of the brain, and neuroinflammation remains unknown. This study investigated the mechanism underlying TIAM2S shapes immune properties of microglia to facilitate neuron damage. Human microglial clone 3 cell line (HMC3) and human brain samples were applied to determine the presence of TIAM2S in microglia by western blots and double immunostaining. Furthermore, TIAM2S transgenic mice combined with multiple reconstituted primary neuron-glial culture systems and a cytokine array were performed to explore how TIAM2S shaped immune priming of microglia and participated in lipopolysaccharide (LPS)-induced neuron damage. TIAM2S protein was detectable in HMC3 cells and presented in a small portion (~11.1%) of microglia in human brains referred to as TIAM2S-positive microglia. With the property of secreted soluble factor-mediated immune priming, TIAM2S-positive microglia enhanced LPS-induced neuroinflammation and neural damage in vivo and in vitro. The gain- and loss-of-function experiments showed soluble intercellular adhesion molecule-1 (sICAM-1) participated in neurotoxic immune priming of TIAM2S+ microglia. Together, this study demonstrated a novel TIAM2S-positive microglia subpopulation enhances inflammation and neurotoxicity through sICAM-1-mediated immune priming.
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Inflamación , Molécula 1 de Adhesión Intercelular , Microglía , Microambiente Tumoral , Animales , Humanos , Ratones , Inflamación/metabolismo , Molécula 1 de Adhesión Intercelular/genética , Molécula 1 de Adhesión Intercelular/metabolismo , Lipopolisacáridos/farmacología , Ratones Transgénicos , Microglía/metabolismo , Enfermedades Neuroinflamatorias/inmunología , Microambiente Tumoral/inmunologíaRESUMEN
Epidemiologic studies have indicated that chronic hypertension may facilitate the progression of abnormal behavior, such as emotional irritability, hyperactivity, and attention impairment. However, the mechanism of how chronic hypertension affects the brain and neuronal function remains unclear. In this study, 58-week-old male spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) control rats were used. Their locomotor activity and neuronal function were assessed by the open field test, novel object, and Y maze recognition test. Moreover brain tissues were analyzed. We found that the aged SHR exhibited significant locomotor hyperactivity when compared to the WKY rats. However, there was no significant difference in novel object and novel arm recognition between aged SHR and the WKY rats. In the analysis of synaptic membrane protein, the expression of glutamatergic receptors, such as the N-methyl-D-aspartate (NMDA) receptor receptors subunits 2B (GluN2B) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor 1 (GluA1) in the hippocampus of SHR were significantly higher than those of WKY rats. In addition, in the synaptic membrane of SHR's hippocampus and medial prefrontal cortex (mPFC), a down-regulation of astrocytes was found, though the excitatory amino acid transporter 2 (EAAT2) remained constant. Moreover, a down-regulation of microglia in the hippocampus and mPFC was seen in the SHR brain. Long-term exposure to high blood pressure causes upregulation of glutamate receptors. The upregulation of glutamatergic receptors in hippocampus may contribute to the hyper-locomotor activity of aged rodents and may as a therapeutic target in hypertension-induced irritability and hyperactivity.
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Trastorno por Déficit de Atención con Hiperactividad , Hipertensión , Animales , Ácido Glutámico , Hipocampo , Masculino , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Receptores AMPA , Receptores de N-Metil-D-Aspartato , Regulación hacia ArribaRESUMEN
TIAM2S, the short form of human T-cell lymphoma invasion and metastasis 2, can have oncogenic effects when aberrantly expressed in the liver or lungs. However, it is also abundant in healthy, non-neoplastic brain tissue, in which its primary function is still unknown. Here, we examined the neurobiological and behavioral significance of human TIAM2S using the human brain protein panels, a human NT2/D1-derived neuronal cell line model (NT2/N), and transgenic mice that overexpress human TIAM2S (TIAM2S-TG). Our data reveal that TIAM2S exists primarily in neurons of the restricted brain areas around the limbic system and in well-differentiated NT2/N cells. Functional studies revealed that TIAM2S has no guanine nucleotide exchange factor (GEF) activity and is mainly located in the nucleus. Furthermore, whole-transcriptome and enrichment analysis with total RNA sequencing revealed that TIAM2S-knockdown (TIAM2S-KD) was strongly associated with the cellular processes of the brain structural development and differentiation, serotonin-related signaling, and the diseases markers representing neurobehavioral developmental disorders. Moreover, TIAM2S-KD cells display decreased neurite outgrowth and reduced serotonin levels. Moreover, TIAM2S overexpressing TG mice show increased number and length of serotonergic fibers at early postnatal stage, results in higher serotonin levels at both the serum and brain regions, and higher neuroplasticity and hyperlocomotion in latter adulthood. Taken together, our results illustrate the non-oncogenic functions of human TIAM2S and demonstrate that TIAM2S is a novel regulator of serotonin level, brain neuroplasticity, and locomotion behavior.
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Encéfalo/metabolismo , Factores de Intercambio de Guanina Nucleótido/metabolismo , Locomoción , Serotonina/metabolismo , Animales , Encéfalo/crecimiento & desarrollo , Encéfalo/fisiología , Línea Celular Tumoral , Células Cultivadas , Factores de Intercambio de Guanina Nucleótido/genética , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Células 3T3 NIH , Proyección Neuronal , Plasticidad NeuronalRESUMEN
Chronic neuroinflammation contributes to the pathogenesis of Parkinson's disease (PD). However, cellular and molecular mechanisms by which chronic neuroinflammation is formed and maintained remain elusive. This study aimed to explore detailed mechanisms by which anti-inflammatory cytokine interleukin-10 (IL-10) prevented chronic neuroinflammation and neurodegeneration. At 24 h after an intranigral injection of lipopolysaccharide (LPS), levels of NLRP3, pro-caspase-1, pro-IL-1ß, active caspase-1, and mature IL-1ß in the midbrain were much higher in IL-10-/- mice than wildtype mice. Mechanistically, IL-10-/- microglia produced more intracellular reactive oxygen species (iROS) and showed more profound activation of NADPH oxidase (NOX2) than wildtype microglia. Meanwhile, suppression of NOX2-derived iROS production blocked LPS-elicited caspase-1 activation and IL-1ß maturation in IL-10-/- microglia in vitro and in vivo. One month after intranigral LPS injection, IL-10-/- mice revealed more profound microglial activation and dopaminergic neurodegeneration in the substantia nigra than wildtype mice. Importantly, such PD-like pathological changes were prevented by IL-1ß neutralization. Collectively, IL-10 inhibited LPS-elicited production of NOX2-derived iROS thereby suppressing synthesis of NLRP3, pro-caspase-1 and pro-IL-1ß and their activation and cleavage. By this mechanism, IL-10 prevented chronic neuroinflammation and neurodegeneration. This study suggested boosting anti-inflammatory effects of IL-10 and suppressing NLRP3 inflammasome activation could be beneficial for PD treatment.
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Caspasa 1/metabolismo , Neuronas Dopaminérgicas/metabolismo , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Animales , Células Cultivadas , Neuronas Dopaminérgicas/efectos de los fármacos , Femenino , Interleucina-10/genética , Lipopolisacáridos/toxicidad , Masculino , Ratones , Ratones Endogámicos C57BL , Microglía/efectos de los fármacos , Microglía/metabolismo , NADPH Oxidasa 2/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Sustancia Negra/citología , Sustancia Negra/metabolismoRESUMEN
Malformed α-Synuclein (α-syn) aggregates in neurons are released into the extracellular space, activating microglia to induce chronic neuroinflammation that further enhances neuronal damage in α-synucleinopathies, such as Parkinson's disease. The mechanisms by which α-syn aggregates activate and recruit microglia remain unclear, however. Here we show that α-syn aggregates act as chemoattractants to direct microglia toward damaged neurons. In addition, we describe a mechanism underlying this directional migration of microglia. Specifically, chemotaxis occurs when α-syn binds to integrin CD11b, leading to H2O2 production by NADPH oxidase. H2O2 directly attracts microglia via a process in which extracellularly generated H2O2 diffuses into the cytoplasm and tyrosine protein kinase Lyn, phosphorylates the F-actin-associated protein cortactin after sensing changes in the microglial intracellular concentration of H2O2. Finally, phosphorylated cortactin mediates actin cytoskeleton rearrangement and facilitates directional cell migration. These findings have significant implications, given that α-syn-mediated microglial migration reaches beyond Parkinson's disease.
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Movimiento Celular , Peróxido de Hidrógeno/metabolismo , Microglía/metabolismo , alfa-Sinucleína/metabolismo , Familia-src Quinasas/metabolismo , Animales , Animales Recién Nacidos , Antígeno CD11b/genética , Antígeno CD11b/metabolismo , Células Cultivadas , Factores Quimiotácticos/metabolismo , Cortactina/metabolismo , Peróxido de Hidrógeno/farmacología , Immunoblotting , Glicoproteínas de Membrana/deficiencia , Glicoproteínas de Membrana/genética , Ratones Endogámicos C57BL , Ratones Noqueados , Microglía/citología , Microglía/efectos de los fármacos , Microscopía Confocal , NADPH Oxidasa 2 , NADPH Oxidasas/deficiencia , NADPH Oxidasas/genética , Neuronas/citología , Neuronas/metabolismo , Oxidantes/metabolismo , Oxidantes/farmacología , Fosforilación , Interferencia de ARN , Ratas , Transducción de Señal , alfa-Sinucleína/genética , alfa-Sinucleína/farmacología , Familia-src Quinasas/genéticaRESUMEN
BACKGROUND: Misfolded α-synuclein (α-Syn) aggregates participate in the pathogenesis of synucleinopathies, such as Parkinson's disease. Whereas much is known about how the various domains within full-length α-Syn (FL-α-Syn) contribute to the formation of α-Syn aggregates and therefore to their neurotoxicity, little is known about whether the individual peptides that can be generated from α-syn, possibly as intermediate metabolites during degradation of misfolded α-Syn aggregates, are neurotoxic themselves. METHODS: A series of synthesized α-Syn peptides, corresponding to the locus in FL-α-Syn containing alanine 30, substitution of which with a proline causes a familial form of Parkinson's disease, were examined for their capacity of inducing release of microglial superoxide. The neurotoxicity of these peptides was measured according to their influence on the ability of neuroglial cultures deficient in gp91 (phox) , the catalytic unit of NADPH oxidase (Nox2), or wild-type cultures to take up (3)H-labeled dopamine and on the number of tyrosine hydroxylase-staining-positive neurons. Western blots and confocal images were utilized to analyze membrane translocation of p47 (phox) and p67 (phox) , phosphorylation of p47 (phox) and Erk1/2 kinase, and binding of α-Syn peptides to gp91 (phox) . Activation of brain microglia in mice injected with α-Syn peptides was demonstrated by immunostaining for major histocompatibility complex (MHC)-II along with qPCR for Iba-1 and MHC-II. RESULTS: We report α-Syn (29-40) as a specific peptide capable of activating microglial Nox2 to produce superoxide and cause dopaminergic neuronal damage. Administered to mice, this peptide also activated brain microglia to increase expression of MHC-II and Iba-1 and stimulated oxidation reaction. Exploring the underlying mechanisms showed that α-Syn (29-40) peptide triggered Nox2 to generate extracellular superoxide and its metabolite H2O2 by binding to the catalytic unit gp91 (phox) of Nox2; diffusing into cytosol, H2O2 activated Erk1/2 kinase to phosphorylate p47 (phox) and p67 (phox) and further activated Nox2, establishing a positive feedback loop to amplify the Nox2-mediated response. CONCLUSIONS: Collectively, our study suggests novel information regarding how α-Syn causes neuronal injury, possibly including mechanisms involving abnormal metabolites of α-Syn aggregates.
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Neuronas Dopaminérgicas/efectos de los fármacos , Neuroglía/efectos de los fármacos , Superóxidos/metabolismo , Superóxidos/toxicidad , alfa-Sinucleína/farmacología , Animales , Animales Recién Nacidos , Proteínas de Unión al Calcio/metabolismo , Células Cultivadas , Modelos Animales de Enfermedad , Embrión de Mamíferos , Antígenos de Histocompatibilidad Clase II/metabolismo , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas de Microfilamentos/metabolismo , NADPH Oxidasa 2 , NADPH Oxidasas/metabolismo , Neuroglía/metabolismo , Fragmentos de Péptidos/farmacología , Transporte de Proteínas/efectos de los fármacos , Receptores Inmunológicos/deficiencia , Receptores Inmunológicos/genética , Tirosina 3-Monooxigenasa/metabolismo , alfa-Sinucleína/química , alfa-Sinucleína/genéticaRESUMEN
OBJECTIVE: Emerging evidence suggests that inflammation and neurodegeneration underlies bipolar disorder. To investigate biological markers of cytokines and brain-derived neurotrophic factor between bipolar I, bipolar II, and other specified bipolar disorder with short duration hypomania may support the association with inflammatory dysregulation and bipolar disorder and, more specifically, provide evidence for other specified bipolar disorder with short duration hypomania patients were similar to bipolar II disorder patients from a biological marker perspective. METHODS: We enrolled patients with bipolar I disorder (n=234), bipolar II disorder (n=260), other specified bipolar disorder with short duration hypomania (n=243), and healthy controls (n=140). Their clinical symptoms were rated using the Hamilton Depression Rating Scale and Young Mania Rating Scale. Inflammatory cytokine (tumor necrosis factor-α, C-reactive protein, transforming growth factor-ß1, and interleukin-8) and brain-derived neurotrophic factor levels were measured in each group. Multivariate analysis of covariance and linear regression controlled for possible confounders were used to compare cytokine and brain-derived neurotrophic factor levels among the groups. RESULTS: Multivariate analysis of covariance adjusted for age and sex and a main effect of diagnosis was significant (P<.001). Three of the 5 measured biomarkers (tumor necrosis factor-α, transforming growth factor-ß1, and interleukin-8) were significantly (P=.006, .01, and <.001) higher in all bipolar disorder patients than in controls. Moreover, covarying for multiple associated confounders showed that bipolar I disorder patients had significantly higher IL-8 levels than did bipolar II disorder and other specified bipolar disorder with short duration hypomania patients in multivariate analysis of covariance (P=.03) and linear regression (P=.02) analyses. Biomarkers differences between bipolar II disorder and other specified bipolar disorder with short duration hypomania patients were nonsignificant. CONCLUSION: The immunological disturbance along the bipolar spectrum was most severe in bipolar I disorder patients. Other specified bipolar disorder with short duration hypomania patients and bipolar II disorder patients did not differ in these biological markers.
Asunto(s)
Trastorno Bipolar/sangre , Factor Neurotrófico Derivado del Encéfalo/sangre , Proteína C-Reactiva/metabolismo , Interleucina-8/sangre , Factores de Crecimiento Transformadores/sangre , Factor de Necrosis Tumoral alfa/sangre , Adulto , Biomarcadores/sangre , Biomarcadores/metabolismo , Trastorno Bipolar/diagnóstico , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
Endotoxin tolerance (ET) is a reduced responsiveness of innate immune cells like macrophages/monocytes to an endotoxin challenge following a previous encounter with the endotoxin. Although ET in peripheral systems has been well studied, little is known about ET in the brain. The present study showed that brain immune cells, microglia, being different from peripheral macrophages, displayed non-cell autonomous mechanisms in ET formation. Specifically, neurons and astroglia were indispensable for microglial ET. Macrophage colony-stimulating factor (M-CSF) secreted from these non-immune cells was essential for governing microglial ET. Neutralization of M-CSF deprived the neuron-glia conditioned medium of its ability to enable microglia to form ET when microglia encountered two lipopolysaccharide (LPS) treatments. Recombinant M-CSF protein rendered enriched microglia refractory to the second LPS challenge leading to microglial ET. Activation of microglial M-CSF receptor (M-CSFR; also known as CSF1R) and the downstream ERK1/2 signals was responsible for M-CSF-mediated microglial ET. Endotoxin-tolerant microglia in neuron-glia cultures displayed M2-like polarized phenotypes, as shown by upregulation of M2 marker Arg-1, elevated production of anti-inflammatory cytokine interleukin 10, and decreased secretion of pro-inflammatory mediators (tumor necrosis factor α, nitric oxide, prostaglandin E2 and interleukin 1ß). Endotoxin-tolerant microglia protected neurons against LPS-elicited inflammatory insults, as shown by reduced neuronal damages in LPS pre-treatment group compared with the group without LPS pre-treatment. Moreover, while neurons and astroglia became injured during chronic neuroinflammation, microglia failed to form ET. Thus, this study identified a distinct non-cell autonomous mechanism of microglial ET. Interactions of M-CSF secreted by neurons and astroglia with microglial M-CSFR programed microglial ET. Loss of microglial ET could be an important pathogenetic mechanism of inflammation-associated neuronal damages.
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Astrocitos/metabolismo , Endotoxinas , Inflamación/metabolismo , Sistema de Señalización de MAP Quinasas/fisiología , Microglía/metabolismo , Neuronas/metabolismo , Neuroprotección/fisiología , Receptor de Factor Estimulante de Colonias de Macrófagos/metabolismo , Animales , Células Cultivadas , Ratones , Ratones Endogámicos C57BLRESUMEN
Nicotinamide adenine dinucleotide phosphate oxidase, a key superoxide-producing enzyme, plays a critical role in microglia-mediated chronic neuroinflammation and subsequent progressive dopaminergic neurodegeneration in Parkinson's disease. Although nicotinamide adenine dinucleotide phosphate oxidase-targeting anti-inflammatory therapy for Parkinson's disease has been proposed, its application in translational research remains limited. The aim of this study was to obtain preclinical evidence supporting this therapeutic strategy by testing the efficacy of an ultra-low dose of the nicotinamide adenine dinucleotide phosphate oxidase inhibitor diphenyleneiodonium in both endotoxin (lipopolysaccharide)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice using post-treatment regimens. Our data revealed that post-treatment with diphenyleneiodonium significantly attenuated progressive dopaminergic degeneration and improved rotarod activity. Remarkably, post-treatment with diphenyleneiodonium 10 months after lipopolysaccharide injection when mice had 30% loss of nigral dopaminergic neurons, showed high efficacy in protecting the remaining neuronal population and restoring motor function. Diphenyleneiodonium-elicited neuroprotection was associated with the inhibition of microglial activation, a reduction in the expression of proinflammatory factors and an attenuation of α-synuclein aggregation. A pathophysiological evaluation of diphenyleneiodonium-treated mice, including assessment of body weight, organs health, and neuronal counts, revealed no overt signs of toxicity. In summary, infusion of ultra-low dose diphenyleneiodonium potently reduced microglia-mediated chronic neuroinflammation by selectively inhibiting nicotinamide adenine dinucleotide phosphate oxidase and halted the progression of neurodegeneration in mouse models of Parkinson's disease. The robust neuroprotective effects and lack of apparent toxic side effects suggest that diphenyleneiodonium at ultra-low dose may be a promising candidate for future clinical trials in Parkinson's disease patients.
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Neuronas Dopaminérgicas/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Microglía/efectos de los fármacos , NADPH Oxidasas/antagonistas & inhibidores , Degeneración Nerviosa/tratamiento farmacológico , Compuestos Onio/farmacología , Enfermedad de Parkinson/tratamiento farmacológico , Animales , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Ratones Endogámicos C57BL , NADPH Oxidasas/metabolismo , Degeneración Nerviosa/patología , Fármacos Neuroprotectores/uso terapéutico , Enfermedad de Parkinson/patología , Sustancia Negra/metabolismoRESUMEN
BACKGROUND: Different drug dependencies may have unique genetic vulnerabilities. Changes in serotonin availability and function have been linked to addiction. We investigated whether 2 serotonergic polymorphisms, TPH1 A218C (rs1800532) and 5-HTT-linked promoter region (5-HTTLPR) (rs25531), are differently associated with alcohol or opiate dependence. METHODS: Alcohol-dependent patients (n = 292), opiate-dependent patients (n = 309), and healthy controls (n = 301) were recruited from the Han Chinese population in Taiwan. Genotypes of TPH1 A218C and 5-HTTLPR polymorphisms were analyzed using a polymerase chain reaction with restriction fragment length polymorphism. RESULTS: The genotype frequencies of the TPH1 A218C polymorphisms were not significantly different in the 3 groups. The genotype frequencies of the 5-HTTLPR S+ (S/S, S/LG, LG/LG) polymorphisms were significantly higher in opiate-dependent patients (x03C7;2 = 8.77, p = 0.01), but not after controlling for the covariates of age, gender, and interaction effect in logistic regression analysis. Moreover, there was a significant interaction between the TPH1 A218C A/C and 5-HTTLPR S+ gene polymorphisms in opiate-dependent (OR 2.72, p = 0.01), but not in alcohol-dependent patients. CONCLUSIONS: Our data suggested that there may be a differential genetic vulnerability in serotonergic genes for alcohol and opiate addiction. However, replications of our findings are still needed.
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Alcoholismo/genética , Trastornos Relacionados con Opioides/genética , Proteínas de Transporte de Serotonina en la Membrana Plasmática/genética , Triptófano Hidroxilasa/genética , Adulto , Epistasis Genética , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido SimpleRESUMEN
Although dysregulated substance P (SP) has been implicated in the pathophysiology of Parkinson's disease (PD), how SP affects the survival of dopaminergic neurons remains unclear. Here, we found that mice lacking endogenous SP (TAC1(-/-)), but not those deficient in the SP receptor (neurokinin-1 receptor, NK1R), were more resistant to lipopolysaccharide (LPS)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigral dopaminergic neurodegeneration than wild-type controls, suggesting a NK1R-independent toxic action of SP. In vitro dose-response studies revealed that exogenous SP enhanced LPS- and 1-methyl-4-phenylpyridinium (MPP(+))-induced dopaminergic neurodegeneration in a bimodal manner, peaking at submicromolar and subpicomolar concentrations, but was substantially less effective at intermediate concentrations. Mechanistically, the actions of submicromolar levels of SP were NK1R-dependent, whereas subpicomolar SP-elicited actions required microglial NADPH oxidase (NOX2), the key superoxide-producing enzyme, but not NK1R. Subpicomolar concentrations of SP activated NOX2 by binding to the catalytic subunit gp91(phox) and inducing membrane translocation of the cytosolic subunits p47(phox) and p67(phox). The importance of NOX2 was further corroborated by showing that inhibition or disruption of NOX2 blocked subpicomolar SP-exacerbated neurotoxicity. Together, our findings revealed a critical role of microglial NOX2 in mediating the neuroinflammatory and dopaminergic neurodegenerative effects of SP, which may provide new insights into the pathogenesis of PD.
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Dopamina/metabolismo , Neuronas Dopaminérgicas/metabolismo , Microglía/metabolismo , NADPH Oxidasas/metabolismo , Trastornos Parkinsonianos/metabolismo , Receptores de Neuroquinina-1/metabolismo , Sustancia P/metabolismo , Animales , Activación Enzimática , Lipopolisacáridos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Trastornos Parkinsonianos/inducido químicamente , Trastornos Parkinsonianos/patologíaRESUMEN
Although the peripheral anti-inflammatory effect of norepinephrine (NE) is well documented, the mechanism by which this neurotransmitter functions as an anti-inflammatory/neuroprotective agent in the central nervous system (CNS) is unclear. This article aimed to determine the anti-inflammatory/neuroprotective effects and underlying mechanisms of NE in inflammation-based dopaminergic neurotoxicity models. In mice, NE-depleting toxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) was injected at 6 months of lipopolysaccharide (LPS)-induced neuroinflammation. It was found that NE depletion enhanced LPS-induced dopaminergic neuron loss in the substantia nigra. This piece of in vivo data prompted us to conduct a series of studies in an effort to elucidate the mechanism as to how NE affects dopamine neuron survival by using primary midbrain neuron/glia cultures. Results showed that submicromolar concentrations of NE dose-dependently protected dopaminergic neurons from LPS-induced neurotoxicity by inhibiting microglia activation and subsequent release of pro-inflammatory factors. However, NE-elicited neuroprotection was not totally abolished in cultures from ß2-adrenergic receptor (ß2-AR)-deficient mice, suggesting that novel pathways other than ß2-AR are involved. To this end, It was found that submicromolar NE dose-dependently inhibited NADPH oxidase (NOX2)-generated superoxide, which contributes to the anti-inflammatory and neuroprotective effects of NE. This novel mechanism was indeed adrenergic receptors independent since both (+) and (-) optic isomers of NE displayed the same potency. We further demonstrated that NE inhibited LPS-induced NOX2 activation by blocking the translocation of its cytosolic subunit to plasma membranes. In summary, we revealed a potential physiological role of NE in maintaining brain immune homeostasis and protecting neurons via a novel mechanism.
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Encéfalo/inmunología , Neuronas Dopaminérgicas/inmunología , Microglía/enzimología , NADPH Oxidasas/metabolismo , Norepinefrina/metabolismo , Animales , Bencilaminas/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/patología , Células COS , Línea Celular , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Chlorocebus aethiops , Técnicas de Cocultivo , Neuronas Dopaminérgicas/efectos de los fármacos , Neuronas Dopaminérgicas/patología , Homeostasis/fisiología , Lipopolisacáridos/toxicidad , Masculino , Ratones Endogámicos BALB C , Ratones Noqueados , Microglía/efectos de los fármacos , Microglía/patología , Inhibidores de la Captación de Neurotransmisores/farmacología , Ratas Endogámicas F344 , Receptores Adrenérgicos beta 2/genética , Receptores Adrenérgicos beta 2/metabolismoRESUMEN
Microglia and astroglia play critical roles in the development, function, and survival of neurons in the CNS. However, under inflammatory conditions the role of astrogliosis in the inflammatory process and its effects on neurons remains unclear. Here, we used several types of cell cultures treated with the bacterial inflammogen LPS to address these questions. We found that the presence of astroglia reduced inflammation-driven neurotoxicity, suggesting that astrogliosis is principally neuroprotective. Neutralization of supernatant glial cell line-derived neurotrophic factor (GDNF) released from astroglia significantly reduced this neuroprotective effect during inflammation. To determine the immunological role of astroglia, we optimized a highly-enriched astroglial culture protocol and demonstrated that LPS failed to induce the synthesis and release of TNF-α and iNOS/NO. Instead we found significant enhancement of TNF-α and iNOS expression in highly-enriched astroglial cultures required the presence of 0.5-1% microglia, respectively. Thus suggesting that microglial-astroglial interactions are required for LPS to induce the expression of pro-inflammatory factors and GDNF from astroglia. Specifically, we found that microglia-derived TNF-α plays a pivotal role as a paracrine signal to regulate the neuroprotective functions of astrogliosis. Taken together, these findings suggest that astroglia may not possess the ability to directly recognize the innate immune stimuli LPS, but rather depend on crosstalk with microglia to elicit release of neurotrophic factors as a counterbalance to support neuronal survival from the collateral damage generated by activated microglia during neuroinflammation.
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Astrocitos/inmunología , Astrocitos/metabolismo , Microglía/metabolismo , Neuronas/metabolismo , Animales , Células Cultivadas , Femenino , Factor Neurotrófico Derivado de la Línea Celular Glial/metabolismo , Gliosis/metabolismo , Lipopolisacáridos/farmacología , Microglía/inmunología , Ratas Endogámicas F344 , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND: Low-dose dextromethorphan (DM) might have anti-inflammatory and neurotrophic effects mechanistically remote from an NMDA receptor. In a randomized, double-blind, controlled 12 week study, we investigated whether add-on dextromethorphan reduced cytokine levels and benefitted opioid-dependent patients undergoing methadone maintenance therapy (MMT). METHODS: Patients were randomly assigned to a group: DM60 (60mg/day dextromethorphan; n = 65), DM120 (120mg/day dextromethorphan; n = 65), or placebo (n = 66). Primary outcomes were the methadone dose required, plasma morphine level, and retention in treatment. Plasma tumor necrosis factor (TNF)-α, C-reactive protein, interleukin (IL)-6, IL-8, transforming growth factor-ß1, and brain-derived neurotrophic factor (BDNF) levels were examined during weeks 0, 1, 4, 8, and 12. Multiple linear regressions with generalized estimating equation methods were used to examine the therapeutic effect. RESULTS: After 12 weeks, the DM60 group had significantly longer treatment retention and lower plasma morphine levels than did the placebo group. Plasma TNF-α was significantly decreased in the DM60 group compared to the placebo group. However, changes in plasma cytokine levels, BDNF levels, and the methadone dose required in the three groups were not significantly different. CONCLUSIONS: We provide evidence-decreased concomitant heroin use-of low-dose add-on DM's efficacy for treating opioid-dependent patients undergoing MMT.
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Dextrometorfano/uso terapéutico , Metadona/uso terapéutico , Morfina/toxicidad , Trastornos Relacionados con Opioides/tratamiento farmacológico , Retención en Psicología/efectos de los fármacos , Adulto , Analgésicos Opioides/toxicidad , Factor Neurotrófico Derivado del Encéfalo/sangre , Proteína C-Reactiva , Dextrometorfano/administración & dosificación , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Quimioterapia Combinada/métodos , Antagonistas de Aminoácidos Excitadores/administración & dosificación , Antagonistas de Aminoácidos Excitadores/uso terapéutico , Femenino , Humanos , Interleucina-6/sangre , Interleucina-8/sangre , Masculino , Metadona/administración & dosificación , Persona de Mediana Edad , Trastornos Relacionados con Opioides/sangre , Trastornos Relacionados con Opioides/psicología , Factores de Tiempo , Factor de Crecimiento Transformador beta1/sangre , Resultado del Tratamiento , Factor de Necrosis Tumoral alfa/sangreRESUMEN
It is hypothesized that dopaminergic genes-dopamine type-2 receptor (DRD2), aldehyde dehydrogenase 2 (ALDH2), and catechol-O-methyltransferase (COMT)-are associated with bipolar disorder (BP) and anxiety disorder (AD). Bipolar II (BP-II) is reported to be highly comorbid with AD. We examined whether interactions among these three genes are susceptibility factors in BP-II with AD (BP-II(+AD)) and without AD (BP-II(-AD)). In this study, we hypothesize that the interaction of the dopaminergic genes between BP-II(+AD) and BP-II(-AD) is significant different. We recruited 1260 participants: 495 with BP-II(-AD), 170 with BP-II(+AD), and 595 healthy controls without BP-II or AD. Genotyping was done using polymerase chain reactions plus restriction fragment length polymorphism analysis. Genotypic frequencies of the DRD2TaqIA, COMT, and ALDH2 polymorphisms between the two BP-II groups were nonsignificant. In logistic regression, the ALDH2 and DRD2TaqIA genes showed a main effect that was protective against BP-II(-AD) (odds ratio [OR] = 0.497, p = 0.010, and OR = 0.415, p = 0.017, respectively). The interaction of DRD2TaqIA A1/A1 and ALDH2*1/*1 had a significant risk effect on the BP-II(-AD) group (OR = 7.177, p < 0.001). However, the interaction of DRD2TaqIA A1/A1, ALDH2*1/*1, and COMTMet/Met&Val/Met become a weak protective factor against BP-II(-AD) (OR = 0.205, p = 0.047). All of the significant results described above are found only in BP-II(-AD). This study supports the hypothesis the interaction of the dopaminergic genes between BP-II(+AD) and BP-II(-AD) is significant different,, and provides additional evidence that the DRD2TaqIA A1/A1, ALDH2*1/*1 and COMT genes interact in BP-II(-AD) but not in BP-II(+AD).
Asunto(s)
Aldehído Deshidrogenasa/genética , Trastornos de Ansiedad/genética , Pueblo Asiatico/genética , Trastorno Bipolar/genética , Catecol O-Metiltransferasa/genética , Receptores de Dopamina D2/genética , Adulto , Aldehído Deshidrogenasa Mitocondrial , Trastornos de Ansiedad/diagnóstico , Trastornos de Ansiedad/epidemiología , Trastorno Bipolar/diagnóstico , Trastorno Bipolar/epidemiología , Comorbilidad , Epistasis Genética/genética , Femenino , Humanos , Masculino , Persona de Mediana Edad , Taiwán/epidemiología , Adulto JovenRESUMEN
Activation of microglial NADPH oxidase (NOX2) plays a critical role in mediating neuroinflammation, which is closely linked with the pathogenesis of a variety of neurodegenerative diseases, including Parkinson's disease (PD). The inhibition of NOX2-generated superoxide has become an effective strategy for developing disease-modifying therapies for PD. However, the lack of specific and potent NOX2 inhibitors has hampered the progress of this approach. Diphenyleneiodonium (DPI) is a widely used, long-acting NOX2 inhibitor. However, due to its non-specificity for NOX2 and high cytotoxicity at standard doses (µM), DPI has been precluded from human studies. In this study, using ultra-low doses of DPI, we aimed to: (1) investigate whether these problems could be circumvented and (2) determine whether ultra-low doses of DPI were able to preserve its utility as a potent NOX2 inhibitor. We found that DPI at subpicomolar concentrations (10(-14) and 10(-13) M) displays no toxicity in primary midbrain neuron-glia cultures. More importantly, we observed that subpicomolar DPI inhibited phorbol myristate acetate (PMA)-induced activation of NOX2. The same concentrations of DPI did not inhibit the activities of a series of flavoprotein-containing enzymes. Furthermore, potent neuroprotective efficacy was demonstrated in a post-treatment study. When subpicomolar DPI was added to neuron-glia cultures pretreated with lipopolysaccharide, 1-methyl-4-phenylpyridinium or rotenone, it potently protected the dopaminergic neurons. In summary, DPI's unique combination of high specificity toward NOX2, low cytotoxicity and potent neuroprotective efficacy in post-treatment regimens suggests that subpicomolar DPI may be an ideal candidate for further animal studies and potential clinical trials.
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Inhibidores Enzimáticos/farmacología , Microglía/efectos de los fármacos , NADPH Oxidasas/metabolismo , Compuestos Onio/farmacología , Animales , Proteínas de Unión al Calcio/metabolismo , Recuento de Células , Células Cultivadas , Dopamina/metabolismo , Complejo I de Transporte de Electrón/metabolismo , Proteína Ácida Fibrilar de la Glía/metabolismo , Mesencéfalo/citología , Proteínas de Microfilamentos/metabolismo , NADPH-Ferrihemoproteína Reductasa/metabolismo , Neuronas/efectos de los fármacos , Neuronas/fisiología , Óxido Nítrico Sintasa de Tipo II/metabolismo , Nitritos/metabolismo , Superóxidos/metabolismo , Reductasa de Tiorredoxina-Disulfuro/metabolismo , Tirosina 3-Monooxigenasa/metabolismo , Xantina Oxidasa/metabolismoRESUMEN
Major depressive disorder (MDD), one of the most common psychiatric disorders in the world, is a serious, recurrent and chronic mental disorder, which is associated with significant psychosocial disability and economic burden. Until recently, short-term effectiveness of antidepressants has been measured in terms of patients' response to the medications in significantly reduced depressive symptoms. Remission, a long-term elimination of symptoms and the restoration of normal functioning, has become the primary outcome of therapy. In the current study, the efficacy of three frequently prescribed antidepressants, venlafaxine (75-225 mg/day), paroxetine (20 mg/day) and milnacipran (100 mg/day), used in treating 249 MDD patients with Hamilton Rating Scale of Depression (HRSD17) scores higher than 16 was compared. Each patient was evaluated at week 0, 1, 2, 4, 8, 12, 16, 20 and 24 in a 24-week open-label study. Eighty-two patients took venlafaxine, 97 took paroxetine and 70 patients took milnacipran. No significant differences were found between the three groups in the response condition (HRSD17 scores decreased more than 50%) after 24 weeks of follow-up. For remission, the paroxetine was the least efficacious medication than either the milnacipran (HRSD17 ≤ 7) or the venlafaxine (HRSD17 ≤ 5) by the last observation carried forward (LOCF) analysis. Our results suggest that the absence of depressive symptoms alone may not be an indicator for MDD remission, but the duration of absent depressive symptoms may be a better indicator.
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Ciclohexanoles/administración & dosificación , Ciclopropanos/administración & dosificación , Trastorno Depresivo Mayor/tratamiento farmacológico , Paroxetina/administración & dosificación , Adulto , Antidepresivos de Segunda Generación/administración & dosificación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Milnaciprán , Inducción de Remisión , Inhibidores Selectivos de la Recaptación de Serotonina/administración & dosificación , Resultado del Tratamiento , Clorhidrato de VenlafaxinaRESUMEN
TIAM Rac1 associated GEF 2 short-form protein (TIAM2S) is abundant in specific brain tissues, especially in the hippocampus, a brain region critical for processing and consolidation of spatial memory. However, how TIAM2S plasticizes the microstructure and circuits of the hippocampus to shape spatial memory as a neuroplastic regulator during aging, remains to be determined. In this study, transgenic mice overexpressing human TIAM2S protein (TIAM2S-TG mice) were included, and interdisciplinary approaches, such as spatial memory tests and multiparametric magnetic resonance imaging sequences, were conducted to determine the role and the mechanism of TIAM2S in age-related spatial memory deficits. Despite no changes in their neural and glial markers and neuropathological hallmarks expression of the hippocampus, behavioral tests showed that the TIAM2S-TG mice, and not wild-type (WT) mice, developed spatial memory impairment at 18 months old. The T2-weighted and diffusion tensor images analysis were performed to further study the possible role of TIAM2S overexpression in altering the hippocampal structure or neuronal circlets of the mice, increasing their vulnerability to developing spatial memory deficits during aging. The results revealed that the 12-month-old TIAM2S-TG mice had hippocampal dysplasticity, with larger volume, increased fiber numbers, and changed mean fractional anisotropy compared to those in the age-matched WT mice. The fiber tractography analysis exhibited significantly attenuated structural connectivity between the hippocampus and medial prefrontal cortex in the TIAM2S-TG mice. In conclusion, overexpression of TIAM2S, a detrimental factor affecting hippocampus plasticity, causes attenuation of the connectivity within hippocampus-mPFC circuits, leading to age-related spatial memory impairment.
RESUMEN
BACKGROUND: Dendritic spine dysfunction is a key feature of Alzheimer's disease (AD) pathogenesis. Human T-cell lymphoma invasion and metastasis 2 (TIAM2) is expressed in two isoforms, the full length (TIAM2L) and a short transcript (TIAM2S). Compared to TIAM2L protein, which is undetectable, TIAM2S protein is abundant in human brain tissue, especially the hippocampus, and can promote neurite outgrowth in our previous findings. However, whether enhanced hippocampal TIAM2S expression can alleviate cognitive deficits in Alzheimer's disease model mice remains unclear. METHODS: We crossbred 3xTg-AD with TIAM2S mice to generate an AD mouse model that carries the human TIAM2S gene (3xTg-AD/TIAM2S mice). The Morris water maze and object location tests assessed hippocampus-dependent spatial memory. Lentiviral-driven shRNA or cDNA approaches were used to manipulate hippocampal TIAM2S expression. Golgi staining and Sholl analysis were utilized to measure neuronal dendrites and dendritic spines in the mouse hippocampi. RESULTS: Compared to 3xTg-AD mice, 3xTg-AD/TIAM2S mice displayed improved cognitive functions. According to the hippocampus is one of the earliest affected brain regions by AD, we further injected TIAM2S shRNA or TIAM2S cDNA into mouse hippocampi to confirm whether manipulating hippocampal TIAM2S expression could affect AD-related cognitive functions. The results showed that the reduced hippocampal TIAM2S expression in 3xTg-AD/TIAM2S mice abolished the memory improvement effect, whereas increased hippocampal TIAM2S levels alleviated cognitive deficits in 3xTg-AD mice. Furthermore, we found that TIAM2S-mediated memory improvement was achieved by regulating dendritic plasticity. CONCLUSIONS: These results will provide new insights into connecting TIAM2S with AD and support the notion that TIAM2S should be investigated as potential AD therapeutic targets.
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The development of microglial endotoxin tolerance (ET) is a critical event in protecting neurons against excessive immune responses when microglia are administered two consecutive lipopolysaccharide (LPS) challenges. However, the intrinsic mechanisms of microglia shape ET programs and protect neurons remain unclear. This study aimed to determine whether extracellular autocrine cascades or intracellular signaling pathways are involved in ET microglia-mediated tumor necrosis factor-alpha (TNF-α) reduction and neuroprotection. Neuron-glia cultures composed of astroglia, neurons, and microglia were performed in different conditions: with or without serum or LPS-binding proteins (LBP), along with an induction approach of ET. Enzyme-linked immunosorbent assay results revealed that LPS induced TNF-α tolerance of microglia in an LBP-dependent manner. Furthermore, we determined whether the early pro-inflammatory cytokines induced by LPS might contribute to the development of microglial ET. Our data showed that the neutralization of TNF-α using an anti-TNF-α antibody had no change in the TNF-α tolerance of microglia during the ET challenge. Furthermore, pre-incubation of TNF-α, interleukin-1 beta, and prostaglandin E2 failed to induce any TNF-α tolerance in microglia after LPS treatment. Moreover, using three specific chemical inhibitors that respectively blocked the activities of the mitogen-activated protein kinases (MAPKs) namely p38, c-Jun N-terminal kinase and extracellular signal-related kinases revealed that inhibition of p38 MAPK by SB203580 disrupted the tolerated microglia-mediated TNF-α reduction and neuroprotection. In summary, our findings demonstrated that the LPS pre-treatment immediately programmed the microglial ET to prevent endotoxin-induced TNF-α production and neuronal damage through the intracellular p38 MAPK signaling pathway.