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BACKGROUND: It is well established that traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function and that systemic immune changes contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined. METHODS: To further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham (i.e., 90 days post-surgery) congenic donor mice into otherwise healthy, age-matched, irradiated CD45.2 C57BL/6 (WT) hosts. Immune changes were evaluated by flow cytometry, multiplex ELISA, and NanoString technology. Moderate-to-severe TBI was induced by controlled cortical impact injury and neurological function was measured using a battery of behavioral tests. RESULTS: TBI induced chronic alterations in the transcriptome of BM lineage-c-Kit+Sca1+ (LSK+) cells in C57BL/6 mice, including modified epigenetic and senescence pathways. After 8 weeks of reconstitution, peripheral myeloid cells from TBIâWT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBIâWT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI at 8 weeks and 8 months post-reconstitution showed that longer reconstitution periods (i.e., time post-injury) were associated with increased microgliosis and leukocyte infiltration. Pre-treatment with a senolytic agent, ABT-263, significantly improved behavioral performance of aged C57BL/6 mice at baseline, although it did not attenuate neuroinflammation in the acutely injured brain. CONCLUSIONS: TBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in hematopoiesis, innate immunity, and neurological function, as well as altered sensitivity to subsequent brain injury.
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Lesões Encefálicas Traumáticas , Lesões Encefálicas , Camundongos , Animais , Doenças Neuroinflamatórias , Camundongos Endogâmicos C57BL , Lesões Encefálicas Traumáticas/patologia , Lesões Encefálicas/patologia , Encéfalo/metabolismoRESUMO
DNA damage and type I interferons (IFNs) contribute to inflammatory responses after traumatic brain injury (TBI). TBI-induced activation of microglia and peripherally-derived inflammatory macrophages may lead to tissue damage and neurological deficits. Here, we investigated the role of IFN-ß in secondary injury after TBI using a controlled cortical impact model in adult male IFN-ß-deficient (IFN-ß-/-) mice and assessed post-traumatic neuroinflammatory responses, neuropathology, and long-term functional recovery. TBI increased expression of DNA sensors cyclic GMP-AMP synthase and stimulator of interferon genes in wild-type (WT) mice. IFN-ß and other IFN-related and neuroinflammatory genes were also upregulated early and persistently after TBI. TBI increased expression of proinflammatory mediators in the cortex and hippocampus of WT mice, whereas levels were mitigated in IFN-ß-/- mice. Moreover, long-term microglia activation, motor, and cognitive function impairments were decreased in IFN-ß-/- TBI mice compared with their injured WT counterparts; improved neurological recovery was associated with reduced lesion volume and hippocampal neurodegeneration in IFN-ß-/- mice. Continuous central administration of a neutralizing antibody to the IFN-α/ß receptor (IFNAR) for 3 d, beginning 30 min post-injury, reversed early cognitive impairments in TBI mice and led to transient improvements in motor function. However, anti-IFNAR treatment did not improve long-term functional recovery or decrease TBI neuropathology at 28 d post-injury. In summary, TBI induces a robust neuroinflammatory response that is associated with increased expression of IFN-ß and other IFN-related genes. Inhibition of IFN-ß reduces post-traumatic neuroinflammation and neurodegeneration, resulting in improved neurological recovery. Thus, IFN-ß may be a potential therapeutic target for TBI.SIGNIFICANCE STATEMENT TBI frequently causes long-term neurological and psychiatric changes in head injury patients. TBI-induced secondary injury processes including persistent neuroinflammation evolve over time and can contribute to chronic neurological impairments. The present study demonstrates that TBI is followed by robust activation of type I IFN pathways, which have been implicated in microglial-associated neuroinflammation and chronic neurodegeneration. We examined the effects of genetic or pharmacological inhibition of IFN-ß, a key component of type I IFN mechanisms to address its role in TBI pathophysiology. Inhibition of IFN-ß signaling resulted in reduced neuroinflammation, attenuated neurobehavioral deficits, and limited tissue loss long after TBI. These preclinical findings suggest that IFN-ß may be a potential therapeutic target for TBI.
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Dano Encefálico Crônico/fisiopatologia , Lesões Encefálicas Traumáticas/fisiopatologia , Interferon beta/fisiologia , Degeneração Neural/etiologia , Animais , Dano Encefálico Crônico/etiologia , Lesões Encefálicas Traumáticas/complicações , Córtex Cerebral/metabolismo , Comportamento Exploratório/fisiologia , Regulação da Expressão Gênica , Hipocampo/metabolismo , Inflamação , Interferon beta/biossíntese , Interferon beta/deficiência , Interferon beta/genética , Masculino , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/etiologia , Transtornos da Memória/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Microglia/fisiologia , Transtornos dos Movimentos/etiologia , Transtornos dos Movimentos/fisiopatologia , Distribuição Aleatória , Receptor de Interferon alfa e beta/imunologia , Transdução de Sinais , Regulação para CimaRESUMO
Chronic neuroinflammation with sustained microglial activation occurs following severe traumatic brain injury (TBI) and is believed to contribute to subsequent neurodegeneration and neurological deficits. Microglia, the primary innate immune cells in brain, are dependent on colony stimulating factor 1 receptor (CSF1R) signaling for their survival. In this preclinical study, we examined the effects of delayed depletion of chronically activated microglia on functional recovery and neurodegeneration up to 3 months postinjury. A CSF1R inhibitor, Plexxikon (PLX) 5622, was administered to adult male C57BL/6J mice at 1 month after controlled cortical impact to remove chronically activated microglia, and the inhibitor was withdrawn 1-week later to allow for microglial repopulation. Following TBI, the repopulated microglia displayed a ramified morphology similar to that of Sham uninjured mice, whereas microglia in vehicle-treated TBI mice showed the typical chronic posttraumatic hypertrophic morphology. PLX5622 treatment limited TBI-associated neuropathological changes at 3 months postinjury; these included a smaller cortical lesion, reduced hippocampal neuron cell death, and decreased NOX2- and NLRP3 inflammasome-associated neuroinflammation. Furthermore, delayed depletion of chronically activated microglia after TBI led to widespread changes in the cortical transcriptome and altered gene pathways involved in neuroinflammation, oxidative stress, and neuroplasticity. Using a variety of complementary neurobehavioral tests, PLX5622-treated TBI mice also had improved long-term motor and cognitive function recovery through 3 months postinjury. Together, these studies demonstrate that chronic phase removal of neurotoxic microglia after TBI using CSF1R inhibitors markedly reduce chronic neuroinflammation and associated neurodegeneration, as well as related motor and cognitive deficits.SIGNIFICANCE STATEMENT Traumatic brain injury (TBI) is a debilitating neurological disorder that can seriously impact the patient's quality of life. Microglial-mediated neuroinflammation is induced after severe TBI and contributes to neurological deficits and on-going neurodegenerative processes. Here, we investigated the effect of breaking the neurotoxic neuroinflammatory loop at 1-month after controlled cortical impact in mice by pharmacological removal of chronically activated microglia using a colony stimulating factor 1 receptor (CSF1R) inhibitor, Plexxikon 5622. Overall, we show that short-term elimination of microglia during the chronic phase of TBI followed by repopulation results in long-term improvements in neurological function, suppression of neuroinflammatory and oxidative stress pathways, and a reduction in persistent neurodegenerative processes. These studies are clinically relevant and support new concepts that the therapeutic window for TBI may be far longer than traditionally believed if chronic and evolving microglial-mediated neuroinflammation can be inhibited or regulated in a precise manner.
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Lesões Encefálicas Traumáticas/patologia , Microglia/efeitos dos fármacos , Degeneração Neural/patologia , Fármacos Neuroprotetores/farmacologia , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/antagonistas & inibidores , Animais , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/fisiopatologia , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Degeneração Neural/metabolismo , Degeneração Neural/fisiopatologiaRESUMO
Traumatic brain injury (TBI) can cause progressive neurodegeneration, sustained neuroinflammation and chronic neurological dysfunction. Few experimental studies have explored the long-term neurobehavioral and functional cellular changes beyond several months. The present study examined the effects of a single moderate-level TBI on functional outcome 8 months after injury. Male C57BL/6 mice were subjected to controlled cortical impact injury and followed for changes in motor performance, learning and memory, as well as depressive-like and social behavior. We also used a novel flow cytometry approach to assess cellular functions in freshly isolated neurons and microglia from the injured tissue. There were marked and diverse, sustained neurobehavioral changes in injured mice. Compared to sham controls, chronic TBI mice showed long-term deficits in gait dynamics, nest building, spatial working memory and recognition memory. The tail suspension, forced swim, and sucrose consumption tests showed a marked depressive-like phenotype that was associated with impaired sociability. At the cellular level, there were lower numbers of Thy1+Tuj1+ neurons and higher numbers of activated CD45loCD11b+ microglia. Functionally, both neurons and microglia exhibited significantly higher levels of oxidative stress after injury. Microglia exhibited chronic deficits in phagocytosis of E. coli bacteria, and increased uptake of myelin and dying neurons. Living neurons showed decreased expression of synaptophysin and postsynaptic density (PSD)-95, along with greater numbers of microtubule-associated protein light chain 3 (LC3)-positive autophagosomes and increased mitochondrial mass that suggest dysregulation of autophagy. In summary, the late neurobehavioral changes found after murine TBI are similar to those found chronically after moderate-severe human head injury. Importantly, such changes are associated with microglial dysfunction and changes in neuronal activity.
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Lesões Encefálicas/fisiopatologia , Lesões Encefálicas/psicologia , Transtornos Mentais/fisiopatologia , Transtornos Mentais/psicologia , Microglia/patologia , Neurônios/patologia , Animais , Lesões Encefálicas/complicações , Masculino , Aprendizagem em Labirinto/fisiologia , Transtornos Mentais/etiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Interação Social , Fatores de TempoRESUMO
OBJECTIVES: Respiratory infections in the postacute phase of traumatic brain injury impede optimal recovery and contribute substantially to overall morbidity and mortality. This study investigated bidirectional innate immune responses between the injured brain and lung, using a controlled cortical impact model followed by secondary Streptococcus pneumoniae infection in mice. DESIGN: Experimental study. SETTING: Research laboratory. SUBJECTS: Adult male C57BL/6J mice. INTERVENTIONS: C57BL/6J mice were subjected to sham surgery or moderate-level controlled cortical impact and infected intranasally with S. pneumoniae (1,500 colony-forming units) or vehicle (phosphate-buffered saline) at 3 or 60 days post-injury. MAIN RESULTS: At 3 days post-injury, S. pneumoniae-infected traumatic brain injury mice (TBI + Sp) had a 25% mortality rate, in contrast to no mortality in S. pneumoniae-infected sham (Sham + Sp) animals. TBI + Sp mice infected 60 days post-injury had a 60% mortality compared with 5% mortality in Sham + Sp mice. In both studies, TBI + Sp mice had poorer motor function recovery compared with TBI + PBS mice. There was increased expression of pro-inflammatory markers in cortex of TBI + Sp compared with TBI + PBS mice after both early and late infection, indicating enhanced post-traumatic neuroinflammation. In addition, monocytes from lungs of TBI + Sp mice were immunosuppressed acutely after traumatic brain injury and could not produce interleukin-1ß, tumor necrosis factor-α, or reactive oxygen species. In contrast, after delayed infection monocytes from TBI + Sp mice had higher levels of interleukin-1ß, tumor necrosis factor-α, and reactive oxygen species when compared with Sham + Sp mice. Increased bacterial burden and pathology was also found in lungs of TBI + Sp mice. CONCLUSIONS: Traumatic brain injury causes monocyte functional impairments that may affect the host's susceptibility to respiratory infections. Chronically injured mice had greater mortality following S. pneumoniae infection, which suggests that respiratory infections even late after traumatic brain injury may pose a more serious threat than is currently appreciated.
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Lesões Encefálicas Traumáticas/epidemiologia , Monócitos/metabolismo , Infecções Respiratórias/epidemiologia , Infecções Estafilocócicas/epidemiologia , Animais , Lesões Encefálicas Traumáticas/fisiopatologia , Modelos Animais de Doenças , Mediadores da Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pneumonia Estafilocócica , Infecções Respiratórias/mortalidade , Infecções Estafilocócicas/mortalidadeRESUMO
OBJECTIVE: Chronic systemic inflammation contributes to the pathogenesis of many age-related diseases. Although not well understood, alterations in the gut microbiota, or dysbiosis, may be responsible for age-related inflammation. METHODS: Using stroke as a disease model, we tested the hypothesis that a youthful microbiota, when established in aged mice, produces positive outcomes following ischemic stroke. Conversely, an aged microbiota, when established in young mice, produces negative outcomes after stroke. Young and aged male mice had either a young or an aged microbiota established by fecal transplant gavage (FTG). Mice were subjected to ischemic stroke (middle cerebral artery occlusion; MCAO) or sham surgery. During the subsequent weeks, mice underwent behavioral testing and fecal samples were collected for 16S ribosomal RNA analysis of bacterial content. RESULTS: We found that the microbiota is altered after experimental stroke in young mice and resembles the biome of uninjured aged mice. In aged mice, the ratio of Firmicutes to Bacteroidetes (F:B), two main bacterial phyla in gut microbiota, increased â¼9-fold (p < 0.001) compared to young. This increased F:B ratio in aged mice is indicative of dysbiosis. Altering the microbiota in young by fecal gavage to resemble that of aged mice (â¼6-fold increase in F:B ratio, p < 0.001) increased mortality following MCAO, decreased performance in behavioral testing, and increased cytokine levels. Conversely, altering the microbiota in aged to resemble that of young (â¼9-fold decrease in F:B ratio, p < 0.001) increased survival and improved recovery following MCAO. INTERPRETATION: Aged biome increased the levels of systemic proinflammatory cytokines. We conclude that the gut microbiota can be modified to positively impact outcomes from age-related diseases. Ann Neurol 2018;83:23-36.
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Envelhecimento , Microbioma Gastrointestinal , Inflamação/microbiologia , Acidente Vascular Cerebral/microbiologia , Fatores Etários , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Comportamento Exploratório , Transplante de Microbiota Fecal/métodos , Inflamação/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Força Muscular/fisiologia , Exame Neurológico , RNA Ribossômico 16S/metabolismo , Acidente Vascular Cerebral/fisiopatologiaRESUMO
Alzheimer's disease (AD) affects over 6 million people over the age of 65. The advent of new anti-amyloid monoclonal antibodies as treatment for early Alzheimer's disease these immunotherapeutics may slow disease progression but also pose significant risks. Amyloid related imaging abnormalities (ARIA) identified on MRI following administration of these new monoclonal antibodies can cause both brain edema (ARIA-E) and hemorrhage (ARIA-H). While most ARIA is asymptomatic, some patients can develop headache, confusion, nausea, dizziness, seizures and in rare cases death. By analyzing lecanemab, aducanumab, gantenerumab, donanemab, and bapineuzumab clinical trials; risk factors for developing ARIA can be identified to mitigate some of the ARIA risk. Risk factors for developing ARIA-E are a positive Apoε4 carrier status and prior multiple cerebral microhemorrhages. Risk factors for ARIA-H are age, antithrombotic use, and history of prior strokes. With lecanemab, ARIA-E and ARIA-H were seen at lower rates 12 and 17%, respectively, compared to aducanumab (ARIA-E 35% and ARIA-H 19%) in treated patients. ARIA risk factors have impacted inclusion and exclusion criteria, determining who can receive lecanemab. In some clinics, almost 90% of Alzheimer's patients are excluded from receiving these new anti-amyloid therapeutics. This review aims to discuss risk factors of ARIA and highlight important areas for further research. With more anti-amyloid monoclonal antibodies approved by the Food and Drug Administration, considering patient risk factors for developing ARIA is important to identify to minimize patient's risk while receiving these new therapies.
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Traumatic brain injury (TBI) causes complex, time-dependent molecular and cellular responses, which include adaptive changes that promote repair and recovery, as well as maladaptive processes such as chronic inflammation that contribute to chronic neurodegeneration and neurological dysfunction. Hormesis is a well-established biological phenomenon in which exposure to low-dose toxins or stressors results in protective responses to subsequent higher-level stressors or insults. Hormetic stimuli show a characteristic U-shaped or inverted J-shaped dose-response curve, as well as being time and exposure-frequency dependent, similar to pre-conditioning and post-conditioning actions. Voluntary exercise interventions, before or after injury, appear to follow these general hormetic principles. But the molecular alterations associated with exercise interventions or more general hormetic responses have received only limited attention. In this study, we used a well-characterized mouse TBI model to assess the effects of different post-conditioning exercise-intervention paradigms on diverse molecular pathways, including neuroinflammation regulators, and post-traumatic neurological deficits. We generated high-throughput gene expression data and associated molecular pathway analyses to assess the potential molecular mechanisms associated with time- and duration-dependent voluntary exercise intervention, as well as time after treatment. Importantly, we also used newer analytical methods to more broadly assess the impact of exercise on diverse molecular pathways. TBI caused long-term changes in multiple neuroinflammation markers and chronic cognitive dysfunction. Notably, all delayed, post-conditioning exercise interventions reduced post-traumatic neuroinflammation and/or attenuated the related cognitive changes, albeit with different pathway specificity and effects magnitude. Exercise comprehensively reversed injury-associated effects in the hippocampus across both activated inflammatory and inhibited neuronal pathways, consistent with a return toward the noninjured, homeostatic state. In contrast, the cortex showed a less consistent pattern with more limited attenuation of inflammatory pathway activation and an amplification in the injury-dependent inhibition of select noninflammatory pathways, indicating less effective and potentially detrimental responses to exercise. Exercise intervention beginning 2 weeks after injury and lasting 2 weeks was less effective than exercise continuing for 4 weeks. Exercise initiated at a more delayed timepoint of 6 weeks after injury and continuing for 4 weeks was more effective than that during the acute phase. The delayed paradigm was also more effective than exercise initiated at 10 weeks after injury and continuing for 8 weeks, consistent with hormetic responses in other models and species. Overall, our study delineates regional and interventional parameters, as well as related molecular pathway changes, associated with post-conditioning exercise treatment, which may help inform future translational interventional strategies.
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Traumatic brain injury (TBI) causes acute and chronic alterations in systemic immune function which contribute to posttraumatic neuroinflammation and neurodegeneration. However, how TBI affects bone marrow (BM) hematopoietic stem/progenitor cells chronically and to what extent such changes may negatively impact innate immunity and neurological function has not been examined. To further understand the role of BM cell derivatives on TBI outcome, we generated BM chimeric mice by transplanting BM from chronically injured or sham congenic donor mice into otherwise healthy, age-matched, irradiated hosts. After 8 weeks of reconstitution, peripheral myeloid cells from TBIâWT mice showed significantly higher oxidative stress levels and reduced phagocytic activity. At eight months after reconstitution, TBIâWT chimeric mice were leukopenic, with continued alterations in phagocytosis and oxidative stress responses, as well as persistent neurological deficits. Gene expression analysis revealed BM-driven changes in neuroinflammation and neuropathology after 8 weeks and 8 months of reconstitution, respectively. Chimeric mice subjected to TBI showed that longer reconstitution periods were associated with increased microgliosis and leukocyte infiltration. Thus, TBI causes chronic activation and progressive dysfunction of the BM stem/progenitor cell pool, which drives long-term deficits in innate immunity and neurological function, as well as altered sensitivity to subsequent brain injury.
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Lipofuscin is an autofluorescent (AF) pigment formed by lipids and misfolded proteins, which accumulates in postmitotic cells with advanced age. Here, we immunophenotyped microglia in the brain of old C57BL/6 mice (>18 months old) and demonstrate that in comparison to young mice, one-third of old microglia are AF, characterized by profound changes in lipid and iron content, phagocytic activity, and oxidative stress. Pharmacological depletion of microglia in old mice eliminated the AF microglia following repopulation and reversed microglial dysfunction. Age-related neurological deficits and neurodegeneration after traumatic brain injury (TBI) were attenuated in old mice lacking AF microglia. Furthermore, increased phagocytic activity, lysosomal burden, and lipid accumulation in microglia persisted for up to 1 year after TBI, were modified by APOE4 genotype, and chronically driven by phagocyte-mediated oxidative stress. Thus, AF may reflect a pathological state in aging microglia associated with increased phagocytosis of neurons and myelin and inflammatory neurodegeneration that can be further accelerated by TBI.
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Lesões Encefálicas Traumáticas , Lesões Encefálicas , Animais , Camundongos , Microglia/metabolismo , Camundongos Endogâmicos C57BL , Lesões Encefálicas/complicações , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Lesões Encefálicas Traumáticas/complicações , Encéfalo/metabolismo , Fenótipo , LipídeosRESUMO
Ischemic stroke triggers a series of complex pathophysiological processes including autophagy. Differential activation of autophagy occurs in neurons derived from males versus females after stressors such as nutrient deprivation. Whether autophagy displays sexual dimorphism after ischemic stroke is unknown. We used a cerebral ischemia mouse model (middle cerebral artery occlusion, MCAO) to evaluate the effects of inhibiting autophagy in ischemic brain pathology. We observed that inhibiting autophagy reduced infarct volume in males and ovariectomized females. However, autophagy inhibition enhanced infarct size in females and in ovariectomized females supplemented with estrogen compared to control mice. We also observed that males had increased levels of Beclin1 and LC3 and decreased levels of pULK1 and p62 at 24 h, while females had decreased levels of Beclin1 and increased levels of ATG7. Furthermore, the levels of autophagy markers were increased under basal conditions and after oxygen and glucose deprivation in male neurons compared with female neurons in vitro. E2 supplementation significantly inhibited autophagy only in male neurons, and was beneficial for cell survival only in female neurons. This study shows that autophagy in the ischemic brain differs between the sexes, and that autophagy regulators have different effects in a sex-dependent manner in neurons.
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Autofagia/genética , Proteína Beclina-1/genética , Isquemia Encefálica/genética , AVC Isquêmico/genética , Proteínas Associadas aos Microtúbulos/genética , Neurônios/metabolismo , Adenina/análogos & derivados , Adenina/farmacologia , Animais , Autofagia/efeitos dos fármacos , Proteína 7 Relacionada à Autofagia/genética , Proteína 7 Relacionada à Autofagia/metabolismo , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/genética , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo , Proteína Beclina-1/metabolismo , Isquemia Encefálica/metabolismo , Isquemia Encefálica/patologia , Hipóxia Celular/genética , Sobrevivência Celular , Feminino , Regulação da Expressão Gênica , Glucose/deficiência , Infarto da Artéria Cerebral Média/cirurgia , AVC Isquêmico/metabolismo , AVC Isquêmico/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Associadas aos Microtúbulos/metabolismo , Neurônios/patologia , Ovariectomia/métodos , Proteína Sequestossoma-1/genética , Proteína Sequestossoma-1/metabolismo , Índice de Gravidade de Doença , Fatores Sexuais , Transdução de SinaisRESUMO
BACKGROUND: Ischemic stroke is a devastating disease, often resulting in death or permanent neurological deficits. EMMPRIN/CD147 is a plasma membrane protein that induces the production of matrix metalloproteinases (MMPs), which contribute to secondary damage after stroke by disrupting the blood brain barrier (BBB) and facilitating peripheral leukocyte infiltration into the brain. RESULTS: CD147 surface expression increased significantly after stroke on infiltrating leukocytes, astrocytes and endothelial cells, but not on resident microglia. Inhibition of CD147 reduced MMP levels, decreased ischemic damage, and improved functional, cognitive and histological outcomes after experimental ischemic stroke in both young and aged mice. In stroke patients, high levels of serum CD147 24 hours after stroke predicted poor functional outcome at 12 months. Brain CD147 levels were correlated with MMP-9 and secondary hemorrhage in post-mortem samples from stroke patients. CONCLUSIONS: Acute inhibition of CD147 decreases levels of MMP-9, limits tissue loss, and improves long-term cognitive outcomes following experimental stroke in aged mice. High serum CD147 correlates with poor outcomes in stroke patients. This study identifies CD147 as a novel, clinically relevant target in ischemic stroke.
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Basigina/metabolismo , AVC Isquêmico/metabolismo , Idoso , Idoso de 80 Anos ou mais , Animais , Astrócitos/metabolismo , Barreira Hematoencefálica/metabolismo , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Feminino , Humanos , Masculino , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Pessoa de Meia-IdadeRESUMO
The inflammatory response to moderate-severe controlled cortical impact (CCI) in adult male mice has been shown to exhibit greater glial activation compared with age-matched female mice. However, the relative contributions of resident microglia and infiltrating peripheral myeloid cells to this sexually dimorphic neuroinflammatory responses remains unclear. Here, 12-week-old male and female C57Bl/6 mice were subjected to sham or CCI, and brain samples were collected at 1, 3, or 7 days post-injury for flow cytometry analysis of cytokines, reactive oxygen species (ROS), and phagocytosis in resident microglia (CD45intCD11b+) versus infiltrating myeloid cells (CD45hiCD11b+). Motor (rotarod, cylinder test), affect (open field), and cognitive (Y-maze) function tests also were performed. We demonstrate that male microglia had increased phagocytic activity and higher ROS levels in the non-injured brain, whereas female microglia had increased production of tumor necrosis factor (TNF) α and interleukin (IL)-1ß. Following CCI, males showed a significant influx of peripheral myeloid cells by 1 day post-injury followed by proliferation of resident microglia at 3 days. In contrast, myeloid infiltration and microglial activation responses in female CCI mice were significantly reduced. No sex differences were observed for TNFα, IL-1ß, transforming growth factor ß, NOX2, ROS production, or phagocytic activity in resident microglia or infiltrating cells at any time. However, across these functions, infiltrating myeloid cells were significantly more reactive than resident microglia. Female CCI mice also had improved motor function at 1 day post-injury compared with male mice. Thus, we conclude that sexually dimorphic responses to moderate-severe CCI result from the rapid activation and infiltration of pro-inflammatory myeloid cells to brain in male, but not female, mice.
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Lesões Encefálicas Traumáticas/complicações , Inflamação/etiologia , Células Mieloides/patologia , Caracteres Sexuais , Animais , Comportamento Animal/fisiologia , Encéfalo/metabolismo , Encéfalo/patologia , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/patologia , Cognição/fisiologia , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Inflamação/metabolismo , Inflamação/patologia , Masculino , Camundongos , Microglia/metabolismo , Microglia/patologia , Células Mieloides/metabolismo , Fagocitose/fisiologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
Neonatal hypoxic ischemia encephalopathy (HIE) leads to major deficits in language development. While clinically there is a known correlation in the degree of HIE injury and subsequent language disability, there are no treatments beyond speech and language therapy; therefore, experimental studies with a HIE animal model to test new interventions and therapeutics are warranted. Neonatal rodents normally ultrasonically vocalize at postnatal day 7 (PND 7) to PND 14 in response to removal from their mothers. At 6-8 weeks of age juvenile male rodents ultrasonically vocalize in response to exposure to a mature female mouse. Changes in ultrasonic vocalization (USV) production after neonatal brain injury, such ashypoxic ischemia (HI), have not been studied. This study examines the acute and long-term ultrasonic vocalization ability of mice after HI at PND 10. Pups were subjected to HI, sham, or naïve conditions; where in HI and sham surgeries the right common carotid artery was exposed, in the HI this artery was double ligated. The HI and sham pups were then exposed to60minof hypoxia. Naïve pups did not undergo surgery and were subjected to60minof room air. At 3 days following surgery, HI and sham pups vocalize less than nonsurgical naïve controls; yet "juvenile" mice of 6-8 weeks old that underwent HI at PND 10 vocalize less than sham and naïve mice. We conclude that HI injury has significant impact on later adult vocalization.
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Hipóxia-Isquemia Encefálica/fisiopatologia , Vocalização Animal/fisiologia , Animais , Animais Recém-Nascidos , Encéfalo/metabolismo , Lesões Encefálicas/fisiopatologia , Modelos Animais de Doenças , Hipóxia/metabolismo , Hipóxia/fisiopatologia , Isquemia/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Ondas UltrassônicasRESUMO
Micro-RNAs (miRs) are short, noncoding RNAs that negatively regulate gene expression at the post-transcriptional level and have been implicated in the pathophysiology of secondary damage after traumatic brain injury (TBI). Among miRs linked to inflammation, miR-155 has been implicated as a pro-inflammatory factor in a variety of organ systems. We examined the expression profile of miR-155, following experimental TBI (controlled cortical impact) in adult male C57Bl/6 mice, as well as the effects of acute or delayed administration of a miR-155 antagomir on post-traumatic neuroinflammatory responses and neurological recovery. Trauma robustly increased miR-155 expression in the injured cortex over 7 days. Similar TBI-induced miR-155 expression changes were also found in microglia/macrophages isolated from the injured cortex at 7 days post-injury. A miR-155 hairpin inhibitor (antagomir; 0.5 nmol), administered intracerebroventricularly (ICV) immediately after injury, attenuated neuroinflammatory markers at both 1 day and 7 days post-injury and reduced impairments in spatial working memory. Delayed ICV infusion of the miR-155 antagomir (0.5 nmol/day), beginning 24 h post-injury and continuing for 6 days, attenuated neuroinflammatory markers at 7 days post-injury and improved motor, but not cognitive, function through 28 days. The latter treatment limited NADPH oxidase 2 expression changes in microglia/macrophages in the injured cortex and reduced cortical lesion volume. In summary, TBI causes a robust and persistent neuroinflammatory response that is associated with increased miR-155 expression in microglia/macrophages, and miR-155 inhibition reduces post-traumatic neuroinflammatory responses and improves neurological recovery. Thus, miR-155 may be a therapeutic target for TBI-related neuroinflammation.
Assuntos
Antagomirs/administração & dosagem , Lesões Encefálicas Traumáticas , MicroRNAs/antagonistas & inibidores , Inflamação Neurogênica , Animais , Lesões Encefálicas Traumáticas/genética , Lesões Encefálicas Traumáticas/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Inflamação Neurogênica/genética , Recuperação de Função Fisiológica/efeitos dos fármacos , Recuperação de Função Fisiológica/genéticaRESUMO
After traumatic brain injury (TBI), individuals aged over 65 years show increased mortality and worse functional outcomes compared with younger persons. As neuroinflammation is a key pathobiological mechanism of secondary injury after TBI, we examined how aging affects post-traumatic microglial responses and functional outcomes. Young (3-month-old) and aged (18-month-old) male C57Bl/6 mice were subjected to moderate-level controlled cortical impact or sham surgery, and neurological function was evaluated. At 72 hours after injury, brain, blood, and spleen leukocyte counts were assessed ex vivo using flow cytometry. Aged mice demonstrated more severe deficits in forelimb grip strength, balance and motor coordination, spontaneous locomotor activity, and anxiety-like behavior. These animals also exhibited more robust microglial proliferation and significantly higher numbers of brain-infiltrating leukocytes. Microglia in aged mice showed impairments in phagocytic activity and higher production of interleukin-1ß (IL-1ß). Infiltrating myeloid cells in aged TBI mice also had deficits in phagocytosis but showed diminished proinflammatory cytokine production and greater reactive oxygen species production. Expression of several senescence markers (Bcl-2, p16ink4a, p21cip1a, lipofuscin, and H2AX [pS139]) was increased with age and/or TBI in both microglia and injured cortex. Although there was no difference in the number of circulating blood neutrophils as a function of age, young mice exhibited more pronounced TBI-induced splenomegaly and splenic myeloid cell expansion. Thus, worse post-traumatic behavioral outcomes in aged animals are associated with exaggerated microglial responses, increased leukocyte invasion, and upregulation of senescence markers.
Assuntos
Envelhecimento/patologia , Lesões Encefálicas/patologia , Senescência Celular , Microglia/patologia , Animais , Ansiedade , Comportamento Animal , Encéfalo/patologia , Lesões Encefálicas/fisiopatologia , Senescência Celular/genética , Força da Mão , Inflamação , Interleucina-1beta/metabolismo , Leucócitos/patologia , Masculino , Camundongos Endogâmicos C57BL , Microglia/imunologia , Microglia/metabolismo , Atividade Motora , Fagocitose , Desempenho Psicomotor , Espécies Reativas de Oxigênio/metabolismo , Fatores de TempoRESUMO
There is a compelling link between severe brain trauma and immunosuppression in patients with traumatic brain injury (TBI). Although acute changes in the systemic immune compartment have been linked to outcome severity, the long-term consequences of TBI on systemic immune function are unknown. Here, adult male C57Bl/6 mice underwent moderate-level controlled cortical impact (CCI) or sham surgery, and systemic immune function was evaluated at 1, 3, 7, 14, and 60 days post-injury. Bone marrow, blood, thymus, and spleen were examined by flow cytometry to assess changes in immune composition, reactive oxygen species (ROS) production, phagocytic activity, and cytokine production. Bone marrow derived macrophages (BMDMs) from sham and 60-day CCI mice were cultured for immune challenge studies using lipopolysaccharide (LPS) and interleukin-4 (IL-4) models. Acutely, TBI caused robust bone marrow activation and neutrophilia. Neutrophils and monocytes exhibited impairments in respiratory burst, cytokine production, and phagocytosis; in contrast, ROS levels and pro-inflammatory cytokine production were chronically elevated at 60 days post-injury. Cultures of BMDMs from chronic CCI mice demonstrated defects in LPS- and IL-4-induced polarization when compared with stimulated BMDMs from sham mice. TBI also caused thymic involution, inverted CD4:CD8 ratios, chronic T lymphopenia, greater memory conversion, increased T cell activation, impaired interferon γ induction, and chronically elevated Th1 cytokine and ROS production. Collectively, our in-depth phenotypic and functional analyses demonstrate that TBI induces widespread suppression of innate and adaptive immune responses after TBI. Moreover, at chronic time points, TBI mice exhibit hallmarks of accelerated immune aging, displaying chronic deficits in systemic immune function.
Assuntos
Imunidade Adaptativa/imunologia , Lesões Encefálicas Traumáticas/imunologia , Imunidade Inata/imunologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Speech impairments affect one in four stroke survivors. However, animal models of post-ischemic vocalization deficits are limited. Male mice vocalize at ultrasonic frequencies when exposed to an estrous female mouse. In this study we assessed vocalization patterns and quantity in male mice after cerebral ischemia. FOXP2, a gene associated with verbal dyspraxia in humans, with known roles in neurogenesis and synaptic plasticity, was also examined after injury. Using a transient middle cerebral artery occlusion (MCAO) model, we assessed correlates of vocal impairment at several time-points after stroke. Further, to identify possible lateralization of vocalization deficits induced by left and right hemispheric strokes were compared. Significant differences in vocalization quantity were observed between stroke and sham animals that persisted for a month after injury. Injury to the left hemisphere reduced early vocalizations more profoundly than those to the right hemisphere. Nuclear expression of Foxp2 was elevated early after stroke (at 6h), but significantly decreased 24h after injury in both the nucleus and the cytoplasm. Neuronal Foxp2 expression increased in stroke mice compared to sham animals 4 weeks after injury. This study demonstrates that quantifiable deficits in ultrasonic vocalizations (USVs) are seen after stroke. USV may be a useful tool to assess chronic behavioral recovery in murine models of stroke.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Proteínas Repressoras/metabolismo , Acidente Vascular Cerebral/fisiopatologia , Vocalização Animal/fisiologia , Animais , Encéfalo/patologia , Encéfalo/fisiopatologia , Núcleo Celular/metabolismo , Citosol/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Lateralidade Funcional , Infarto da Artéria Cerebral Média , Nervos Laríngeos/patologia , Nervos Laríngeos/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Neurônios/patologia , Neurônios/fisiologia , Distribuição Aleatória , Acidente Vascular Cerebral/patologia , Fatores de Tempo , UltrassomRESUMO
Social isolation prior to stroke leads to poorer outcomes after an ischemic injury in both animal and human studies. However, the impact of social isolation following stroke, which may be more clinically relevant as a target for therapeutic intervention, has yet to be examined. In this study, we investigated both the sub-acute (2 weeks) and chronic (7 weeks) effects of social isolation on post-stroke functional and histological outcome. Worsened histological damage from ischemic injury and an increase in depressive-like behavior was observed in isolated mice as compared to pair-housed mice. Mice isolated immediately after stroke showed a decrease in the levels of brain-derived neurotrophic factor (BDNF). These changes, both histological and behavioral, suggest an overall negative effect of social isolation on stroke outcome, potentially contributing to post-stroke depression and anxiety. Therefore, it is important to identify patients who have perceived isolation post-stroke to hopefully prevent this exacerbation of histological damage and subsequent depression.