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Mild traumatic brain injury (mTBI) has emerged as a potential risk factor for the development of neurodegenerative conditions such as Alzheimer's disease and chronic traumatic encephalopathy. Blast mTBI, caused by exposure to a pressure wave from an explosion, is predominantly experienced by military personnel and has increased in prevalence and severity in recent decades. Yet the underlying pathology of blast mTBI is largely unknown. We examined the expression and localization of AQP4 in human post-mortem frontal cortex and observed distinct laminar differences in AQP4 expression following blast exposure. We also observed similar laminar changes in AQP4 expression and localization and delayed impairment of glymphatic function that emerged 28â days following blast injury in a mouse model of repetitive blast mTBI. In a cohort of veterans with blast mTBI, we observed that blast exposure was associated with an increased burden of frontal cortical MRI-visible perivascular spaces, a putative neuroimaging marker of glymphatic perivascular dysfunction. These findings suggest that changes in AQP4 and delayed glymphatic impairment following blast injury may render the post-traumatic brain vulnerable to post-concussive symptoms and chronic neurodegeneration.
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Aquaporina 4 , Traumatismos por Explosões , Sistema Glinfático , Adulto , Idoso , Animais , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Aquaporina 4/metabolismo , Traumatismos por Explosões/complicações , Traumatismos por Explosões/patologia , Traumatismos por Explosões/metabolismo , Concussão Encefálica/metabolismo , Concussão Encefálica/complicações , Concussão Encefálica/patologia , Concussão Encefálica/fisiopatologia , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/patologia , Lobo Frontal/metabolismo , Lobo Frontal/patologia , Lobo Frontal/diagnóstico por imagem , Sistema Glinfático/metabolismo , Sistema Glinfático/patologia , Imageamento por Ressonância Magnética , Camundongos Endogâmicos C57BL , VeteranosRESUMO
Amyotrophic lateral sclerosis (ALS) is a fatal movement disorder involving degeneration of motor neurons through dysfunction of the RNA-binding protein TDP-43. Pericytes, the perivascular cells of the blood-brain, blood-spinal cord, and blood-CSF barriers also degenerate in ALS. Indeed, pericytes are among the earliest cell types to show gene expression changes in pre-symptomatic animal models of ALS. This suggests that pericyte degeneration precedes neurodegeneration and may involve pericyte cell-autonomous TDP-43 dysfunction. Here we determined the effect of TDP-43 dysfunction in human brain pericytes on interleukin 6 (IL-6), a critical secreted inflammatory mediator reported to be regulated by TDP 43. Primary human brain pericytes were cultured from biopsy tissue from epilepsy surgeries and TDP-43 was silenced using siRNA. TDP-43 silencing of pericytes stimulated with pro-inflammatory cytokines, interleukin-1ß or tumour necrosis factor alpha, robustly suppressed the induction of IL-6 transcript and protein. IL-6 regulation by TDP-43 did not involve the assembly of TDP-43 nuclear splicing bodies, and did not occur via altered splicing of IL6. Instead, transcriptome-wide analysis by RNA-Sequencing identified a poison exon in the IL6 destabilising factor HNRNPD (AUF1) as a splicing target of TDP-43. Our data support a model whereby TDP-43 silencing favours destabilisation of IL6 mRNA, via enhanced AU-rich element-mediated decay by HNRNP/AUF1. This suggests that cell-autonomous deficits in TDP-43 function in human brain pericytes would suppress their production of IL-6. Given the importance of the blood-brain and blood-spinal cord barriers in maintaining motor neuron health, TDP-43 in human brain pericytes may represent a cellular target for ALS therapeutics.
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Esclerose Lateral Amiotrófica , Proteínas de Ligação a DNA , Interleucina-6 , Pericitos , Humanos , Esclerose Lateral Amiotrófica/metabolismo , Encéfalo/metabolismo , Citocinas/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Expressão Gênica , Interleucina-6/metabolismo , Pericitos/metabolismo , Pericitos/patologia , Medula Espinal/metabolismoRESUMO
BACKGROUND: Pericytes and endothelial cells are critical cellular components of the blood-brain barrier (BBB) and play an important role in neuroinflammation. To date, the majority of inflammation-related studies in endothelia and pericytes have been carried out using immortalised cell lines or non-human-derived cells. Whether these are representative of primary human cells is unclear and systematic comparisons of the inflammatory responses of primary human brain-derived pericytes and endothelia has yet to be performed. METHODS: To study the effects of neuroinflammation at the BBB, primary brain endothelial cells and pericytes were isolated from human biopsy tissue. Culture purity was examined using qPCR and immunocytochemistry. Electrical cell-substrate impedance sensing (ECIS) was used to determine the barrier properties of endothelial and pericyte cultures. Using immunocytochemistry, cytometric bead array, and ECIS, we compared the responses of endothelia and pericytes to a panel of inflammatory stimuli (IL-1ß, TNFα, LPS, IFN-γ, TGF-ß1, IL-6, and IL-4). Secretome analysis was performed to identify unique secretions of endothelia and pericytes in response to IL-1ß. RESULTS: Endothelial cells were pure, moderately proliferative, retained the expression of BBB-related junctional proteins and transporters, and generated robust TEER. Both endothelia and pericytes have the same pattern of transcription factor activation in response to inflammatory stimuli but respond differently at the secretion level. Secretome analysis confirmed that endothelia and pericytes have overlapping but distinct secretome profiles in response to IL-1ß. We identified several cell-type specific responses, including G-CSF and GM-CSF (endothelial-specific), and IGFBP2 and IGFBP3 (pericyte-specific). Finally, we demonstrated that direct addition of IL-1ß, TNFα, LPS, and IL-4 contributed to the loss of endothelial barrier integrity in vitro. CONCLUSIONS: Here, we identify important cell-type differences in the inflammatory response of brain pericytes and endothelia and provide, for the first time, a comprehensive profile of the secretions of primary human brain endothelia and pericytes which has implications for understanding how inflammation affects the cerebrovasculature.
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Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Células Endoteliais/metabolismo , Mediadores da Inflamação/metabolismo , Pericitos/metabolismo , Barreira Hematoencefálica/citologia , Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Células Endoteliais/efeitos dos fármacos , Humanos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Inflamação/patologia , Mediadores da Inflamação/farmacologia , Pericitos/efeitos dos fármacosRESUMO
BACKGROUND: Brain pericytes ensheathe the endothelium and contribute to formation and maintenance of the blood-brain-barrier. Additionally, pericytes are involved in several aspects of the CNS immune response including scarring, adhesion molecule expression, chemokine secretion, and phagocytosis. In vitro cultures are routinely used to investigate these functions of brain pericytes, however, these are highly plastic cells and can display differing phenotypes and functional responses depending on their culture conditions. Here we sought to investigate how two commonly used culture media, high serum containing DMEM/F12 and low serum containing Pericyte Medium (ScienCell), altered the phenotype of human brain pericytes and neuroinflammatory responses. METHODS: Pericytes were isolated from adult human brain biopsy tissue and cultured in DMEM/F12 (D-pericytes) or Pericyte Medium (P-pericytes). Immunocytochemistry, qRT-PCR, and EdU incorporation were used to determine how this altered their basal phenotype, including the expression of pericyte markers, proliferation, and cell morphology. To determine whether culture media altered the inflammatory response in human brain pericytes, immunocytochemistry, qRT-PCR, cytometric bead arrays, and flow cytometry were used to investigate transcription factor induction, chemokine secretion, adhesion molecule expression, migration, phagocytosis, and response to inflammatory-related growth factors. RESULTS: P-pericytes displayed elevated proliferation and a distinct bipolar morphology compared to D-pericytes. Additionally, P-pericytes displayed lower expression of pericyte-associated markers NG2, PDGFRß, and fibronectin, with notably lower αSMA, CD146, P4H and desmin, and higher Col-IV expression. Nuclear NF-kB translocation in response to IL-1ß stimulation was observed in both cultures, however, P-pericytes displayed elevated expression of the transcription factor C/EBPδ, and lower expression of the adhesion molecule ICAM-1. P-pericytes displayed elevated phagocytic and migratory ability. Both cultures responded similarly to stimulation by the growth factors TGFß1 and PDGF-BB. CONCLUSIONS: Despite differences in their phenotype and magnitude of response, both P-pericytes and D-pericytes responded similarly to all examined functions, indicating that the neuroinflammatory phenotype of these cells is robust to culture conditions.
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Barreira Hematoencefálica/fisiologia , Encéfalo/fisiologia , Regulação da Expressão Gênica/fisiologia , Pericitos/patologia , Pericitos/fisiologia , Barreira Hematoencefálica/patologia , Encéfalo/patologia , Células Cultivadas , Citocinas/metabolismo , Fibronectinas/metabolismo , Humanos , Interleucina-1beta/metabolismoRESUMO
BACKGROUND: Neuroinflammation and blood-brain barrier (BBB) disruption are common features of many brain disorders, including Alzheimer's disease, epilepsy, and motor neuron disease. Inflammation is thought to be a driver of BBB breakdown, but the underlying mechanisms for this are unclear. Brain pericytes are critical cells for maintaining the BBB and are immunologically active. We sought to test the hypothesis that inflammation regulates the BBB by altering pericyte biology. METHODS: We exposed primary adult human brain pericytes to chronic interferon-gamma (IFNγ) for 4 days and measured associated functional aspects of pericyte biology. Specifically, we examined the influence of inflammation on platelet-derived growth factor receptor-beta (PDGFRß) expression and signalling, as well as pericyte proliferation and migration by qRT-PCR, immunocytochemistry, flow cytometry, and western blotting. RESULTS: Chronic IFNγ treatment had marked effects on pericyte biology most notably through the PDGFRß, by enhancing agonist (PDGF-BB)-induced receptor phosphorylation, internalization, and subsequent degradation. Functionally, chronic IFNγ prevented PDGF-BB-mediated pericyte proliferation and migration. CONCLUSIONS: Because PDGFRß is critical for pericyte function and its removal leads to BBB leakage, our results pinpoint a mechanism linking chronic brain inflammation to BBB dysfunction.
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BACKGROUND: Brain inflammation plays a key role in neurological disease. Although much research has been conducted investigating inflammatory events in animal models, potential differences in human brain versus rodent models makes it imperative that we also study these phenomena in human cells and tissue. METHODS: Primary human brain cell cultures were generated from biopsy tissue of patients undergoing surgery for drug-resistant epilepsy. Cells were treated with pro-inflammatory compounds IFNγ, TNFα, IL-1ß, and LPS, and chemokines IP-10 and MCP-1 were measured by immunocytochemistry, western blot, and qRT-PCR. Microarray analysis was also performed on late passage cultures treated with vehicle or IFNγ and IL-1ß. RESULTS: Early passage human brain cell cultures were a mixture of microglia, astrocytes, fibroblasts and pericytes. Later passage cultures contained proliferating fibroblasts and pericytes only. Under basal culture conditions all cell types showed cytoplasmic NFκB indicating that they were in a non-activated state. Expression of IP-10 and MCP-1 were significantly increased in response to pro-inflammatory stimuli. The two chemokines were expressed in mixed cultures as well as cultures of fibroblasts and pericytes only. The expression of IP-10 and MCP-1 were regulated at the mRNA and protein level, and both were secreted into cell culture media. NFκB nuclear translocation was also detected in response to pro-inflammatory cues (except IFNγ) in all cell types. Microarray analysis of brain pericytes also revealed widespread changes in gene expression in response to the combination of IFNγ and IL-1ß treatment including interleukins, chemokines, cellular adhesion molecules and much more. CONCLUSIONS: Adult human brain cells are sensitive to cytokine challenge. As expected 'classical' brain immune cells, such as microglia and astrocytes, responded to cytokine challenge but of even more interest, brain pericytes also responded to such challenge with a rich repertoire of gene expression. Immune activation of brain pericytes may play an important role in communicating inflammatory signals to and within the brain interior and may also be involved in blood brain barrier (BBB) disruption . Targeting brain pericytes, as well as microglia and astrocytes, may provide novel opportunities for reducing brain inflammation and maintaining BBB function and brain homeostasis in human brain disease.
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Encéfalo/patologia , Citocinas/metabolismo , Citocinas/farmacologia , Pericitos/efeitos dos fármacos , Pericitos/metabolismo , Actinas/metabolismo , Adulto , Antígenos/metabolismo , Células Cultivadas , Citocinas/genética , Dura-Máter/efeitos dos fármacos , Dura-Máter/metabolismo , Epilepsia/patologia , Fibronectinas/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Proteína Glial Fibrilar Ácida/metabolismo , Humanos , Prolina Dioxigenases do Fator Induzível por Hipóxia/metabolismo , Antígenos Comuns de Leucócito/metabolismo , Masculino , Pessoa de Meia-Idade , Neuroglia/efeitos dos fármacos , Técnicas de Cultura de Órgãos , Transporte Proteico/efeitos dos fármacos , Proteoglicanas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Fatores de Tempo , Fator de Transcrição RelA/metabolismoRESUMO
Cellular interactions mediated by the neural cell adhesion molecule (NCAM) are critical in cell migration, differentiation and plasticity. Switching of the NCAM-interaction mode, from adhesion to signalling, is determined by NCAM carrying a particular post-translational modification, polysialic acid (PSA). Regulation of cell-surface PSA-NCAM is traditionally viewed as a direct consequence of polysialyltransferase activity. Taking advantage of the polysialyltransferase Ca²âº-dependent activity, we demonstrate in TE671 cells that downregulation of PSA-NCAM synthesis constitutes a necessary but not sufficient condition to reduce cell-surface PSA-NCAM; instead, PSA-NCAM turnover required internalization of the molecule into the cytosol. PSA-NCAM internalization was specifically triggered by collagen in the extracellular matrix (ECM) and prevented by insulin-like growth factor (IGF1) and insulin. Our results pose a novel role for IGF1 and insulin in controlling cell migration through modulation of PSA-NCAM turnover at the cell surface. Neural cell adhesion molecules (NCAMs) are critically involved in cell differentiation and migration. Polysialylation (PSA)/desialylation of NCAMs switches their functional interaction mode and, in turn, migration and differentiation. We have found that the desialylation process of PSA-NCAM occurs via endocytosis, induced by collagen-IV and blocked by insulin-like growth factor (IGF1) and insulin, suggesting a novel association between PSA-NCAM, IGF1/insulin and brain/tumour plasticity.
Assuntos
Matriz Extracelular/metabolismo , Hipoglicemiantes/farmacologia , Fator de Crescimento Insulin-Like I/farmacologia , Insulina/farmacologia , Moléculas de Adesão de Célula Nervosa/metabolismo , Ácidos Siálicos/metabolismo , Western Blotting , Cálcio/metabolismo , Linhagem Celular Tumoral , Colágeno Tipo IV/metabolismo , Endocitose/efeitos dos fármacos , Humanos , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Processamento de Proteína Pós-Traducional , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Significance: The glymphatic system has been described recently as a series of perivascular channels that facilitate fluid exchange and solute clearance in the brain. Glymphatic dysfunction has been implicated in numerous pathological conditions, including Alzheimer's disease, traumatic brain injury, and stroke. Existing methods for assessing glymphatic function have been challenging: dynamic methods, such as two-photon microscopy and contrast-enhanced magnetic resonance imaging require expensive instrumentation and specific technical skills; slice-based fluorescent imaging is more readily implemented but lacks temporal resolution. Aim: To develop a straightforward and adaptable dynamic imaging approach for assessing glymphatic function in vivo in mice. Approach: Using a widely available small animal infrared (IR) imaging system (LICOR Pearl), visualization of IR cerebrospinal fluid tracer distribution over the cortical surface enables time-resolved measurement of the dynamics of glymphatic exchange. Using co-injection of IR and conventional fixable fluorescent tracers, dynamic imaging can be paired with whole-slice fluorescence imaging, permitting the quantification of glymphatic function throughout the brain as well as subsequent histological assessment. Results: These techniques were validated against one another, comparing differences between animals anesthetized with ketamine/xylazine and isoflurane. Conclusions: This technique permits sensitive dynamic imaging of glymphatic function, with the concurrent visualization of resolution of deeper structures.
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BACKGROUND: Alzheimer's disease (AD) is a multifactorial process that takes years to manifest clinically. We propose that brain-derived indicators of cerebrovascular dysfunction and inflammation would inform on AD-related pathological processes early in, and perhaps prior to neurodegenerative disease development. OBJECTIVE: Define the relationship between cerebrospinal fluid (CSF) markers of cerebrovascular dysfunction and neuroinflammation with AD CSF biomarkers in cognitively normal individuals. METHODS: Analytes were measured from CSF and plasma collected at baseline from two randomized control trials. We performed Pearson correlation analysis (adjusting for age, sex, APOE haplotype, and education) between markers of central nervous system (CNS) barrier disruption, cerebrovascular dysfunction, CSF inflammatory cytokines and chemokines, and plasma lipid levels. We then developed a statistical prediction model using machine learning to test the ability of measured CSF analytes and blood lipid profiles to predict CSF AD biomarkers (total tau, phospho-tau (181), Aß42) in this clinical population. RESULTS: Our analysis revealed a significant association between markers of CNS barrier dysfunction and markers of cerebrovascular dysfunction, acute inflammatory responses, and CSF inflammatory cytokines. There was a significant association of blood lipid profiles with cerebrovascular injury markers, and CSF inflammatory cytokine levels. Using machine learning, we show that combinations of blood lipid profiles, CSF markers of CNS barrier disruption, cerebrovascular dysfunction and CSF inflammatory cytokines predict CSF total tau, p-tau, and, to a lesser extent, Aß42 in cognitively normal subjects. CONCLUSION: This suggests that these parallel pathological processes may contribute to the development of AD-related neuropathology in the absence of clinical manifestations.
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Doença de Alzheimer , Traumatismo Cerebrovascular , Doenças Neurodegenerativas , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Biomarcadores/líquido cefalorraquidiano , Citocinas , Humanos , Inflamação/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Proteínas tau/líquido cefalorraquidianoRESUMO
When modeling disease in the laboratory, it is important to use clinically relevant models. Patient-derived human brain cells grown in vitro to study and test potential treatments provide such a model. Here, we present simple, highly reproducible coordinated procedures that can be used to routinely culture most cell types found in the human brain from single neurosurgically excised brain specimens. The cell types that can be cultured include dissociated cultures of neurons, astrocytes, microglia, pericytes and brain endothelial and neural precursor cells, as well as explant cultures of the leptomeninges, cortical slice cultures and brain tumor cells. The initial setup of cultures takes ~2 h, and the cells are ready for further experiments within days to weeks. The resulting cells can be studied as purified or mixed population cultures, slice cultures and explant-derived cultures. This protocol therefore enables the investigation of human brain cells to facilitate translation of neuroscience research to the clinic.
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Células-Tronco NeuraisRESUMO
Platelet-derived growth factor-BB (PDGF-BB):PDGF receptor-ß (PDGFRß) signalling in brain pericytes is critical to the development, maintenance and function of a healthy blood-brain barrier (BBB). Furthermore, BBB impairment and pericyte loss in Alzheimer's disease (AD) is well documented. We found that PDGF-BB:PDGFRß signalling components were altered in human AD brains, with a marked reduction in vascular PDGFB. We hypothesised that reduced PDGF-BB:PDGFRß signalling in pericytes may impact on the BBB. We therefore tested the effects of PDGF-BB on primary human brain pericytes in vitro to define pathways related to BBB function. Using pharmacological inhibitors, we dissected distinct aspects of the PDGF-BB response that are controlled by extracellular signal-regulated kinase (ERK) and Akt pathways. PDGF-BB promotes the proliferation of pericytes and protection from apoptosis through ERK signalling. In contrast, PDGF-BB:PDGFRß signalling through Akt augments pericyte-derived inflammatory secretions. It may therefore be possible to supplement PDGF-BB signalling to stabilise the cerebrovasculature in AD.
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Doença de Alzheimer , Pericitos , Doença de Alzheimer/metabolismo , Becaplermina/metabolismo , Becaplermina/farmacologia , Encéfalo/metabolismo , Humanos , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/farmacologiaRESUMO
CREB is a cAMP- and calcium-responsive transcriptional activator that is required for islet beta cell proliferation and survival. Glucose and incretin hormones elicit beta cell insulin secretion and promote synergistic CREB activity by inducing the nuclear relocalization of TORC2 (also known as Crtc2), a coactivator for CREB. In islet cells under basal conditions when CREB activity is low, TORC2 is phosphorylated and sequestered in the cytoplasm by 14-3-3 proteins. In response to feeding stimuli, TORC2 is dephosphorylated, enters the nucleus, and binds to CREB located at target gene promoters. The dephosphorylation of TORC2 at Ser-171 in response to cAMP is insufficient to account for the dynamics of TORC2 localization and CREB activity in islet cells. Here, we identify Ser-275 of TORC2 as a 14-3-3 binding site that is phosphorylated under low glucose conditions and which becomes dephosphorylated by calcineurin in response to glucose influx. Dephosphorylation of Ser-275 is essential for both glucose and cAMP-mediated activation of CREB in beta cells and islets. Using a cell-based screen of 180 human protein kinases, we identified MARK2, a member of the AMPK family of Ser/Thr kinases, as a Ser-275 kinase that blocks TORC2:CREB activity. Taken together, these data provide the mechanistic underpinning for how cAMP and glucose cooperatively promote a transcriptional program critical for islet cell survival, and identifies MARK2 as a potential target for diabetes treatment.
Assuntos
Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Glucose/metabolismo , Ilhotas Pancreáticas/metabolismo , Fatores de Transcrição/metabolismo , Proteínas 14-3-3/metabolismo , Sítios de Ligação , Calcineurina/metabolismo , Linhagem Celular , AMP Cíclico/metabolismo , Glucose/farmacologia , Humanos , Ilhotas Pancreáticas/efeitos dos fármacos , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Serina/química , Transdução de Sinais , Fatores de Transcrição/químicaRESUMO
Neuroinflammation is a key component of virtually all neurodegenerative diseases, preceding neuronal loss and associating directly with cognitive impairment. Neuroinflammatory signals can originate and be amplified at barrier tissues such as brain vasculature, surrounding meninges and the choroid plexus. We designed a high content screening system to target inflammation in human brain-derived cells of the blood-brain barrier (pericytes and endothelial cells) to identify inflammatory modifiers. Screening an FDA-approved drug library we identify digoxin and lanatoside C, members of the cardiac glycoside family, as inflammatory-modulating drugs that work in blood-brain barrier cells. An ex vivo assay of leptomeningeal and choroid plexus explants confirm that these drugs maintain their function in 3D cultures of brain border tissues. These results suggest that cardiac glycosides may be useful in targeting inflammation at border regions of the brain and offer new options for drug discovery approaches for neuroinflammatory driven degeneration.
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Anti-Inflamatórios/farmacologia , Barreira Hematoencefálica/efeitos dos fármacos , Plexo Corióideo/efeitos dos fármacos , Digoxina/farmacologia , Células Endoteliais/efeitos dos fármacos , Inflamação/tratamento farmacológico , Lanatosídeos/farmacologia , Meninges/efeitos dos fármacos , Pericitos/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/patologia , Células Cultivadas , Plexo Corióideo/metabolismo , Plexo Corióideo/patologia , Avaliação Pré-Clínica de Medicamentos , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Ensaios de Triagem em Larga Escala , Humanos , Inflamação/metabolismo , Inflamação/patologia , Mediadores da Inflamação/metabolismo , Meninges/metabolismo , Meninges/patologia , Pericitos/metabolismo , Pericitos/patologia , Técnicas de Cultura de TecidosRESUMO
Estrogen receptor (ER)-positive breast cancer cells have low levels of constitutive NF-kappaB activity while ER negative (-) cells and hormone-independent cells have relatively high constitutive levels of NF-kappaB activity. In this study, we have examined the aspects of mutual repression between the ERalpha and NF-kappaB proteins in ER+ and ER- hormone-independent cells. Ectopic expression of the ERalpha reduced cell numbers in ER+ and ER- breast cancer cell lines while NF-kappaB-binding activity and the expression of several NF-kappaB-regulated proteins were reduced in ER- cells. ER overexpression in ER+/E2-independent LCC1 cells only weakly inhibited the predominant p50 NF-kappaB. GST-ERalpha fusion protein pull downs and in vivo co-immunoprecipitations of NF-kappaB:ERalpha complexes showed that the ERalpha interacts with p50 and p65 in vitro and in vivo. Inhibition of NF-kappaB increased the expression of diverse E2-regulated proteins. p50 differentially associated directly with the ER:ERE complex in LCC1 and MCF-7 cells by supershift analysis while p65 antibody reduced ERalpha:ERE complexes in the absence of a supershift. ChIP analysis demonstrated that NF-kappaB proteins are present on an endogenous ERE. Together these results demonstrate that the ER and NF-kappaB undergo mutual repression, which may explain, in part, why expression of the ERalpha in ER- cells does not confer growth signaling. Secondly, the acquisition of E2-independence in ER+ cells is associated with predominantly p50:p50 NF-kappaB, which may reflect alterations in the ER in these cells. Since the p50 homodimer is less sensitive to the presence of the ER, this may allow for the activation of both pathways in the same cell.
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Neoplasias da Mama/metabolismo , Receptor alfa de Estrogênio/metabolismo , NF-kappa B/metabolismo , Sítios de Ligação , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Feminino , Humanos , Subunidade p50 de NF-kappa B/metabolismo , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , TransfecçãoRESUMO
BACKGROUND: Microglia play critical roles in the brain during homeostasis and pathological conditions. Understanding the molecular events underpinning microglial functions and activation states will further enable us to target these cells for the treatment of neurological disorders. The transcription factor PU.1 is critical in the development of myeloid cells and a major regulator of microglial gene expression. In the brain, PU.1 is specifically expressed in microglia and recent evidence from genome-wide association studies suggests that reductions in PU.1 contribute to a delayed onset of Alzheimer's disease (AD), possibly through limiting neuroinflammatory responses. METHODS: To investigate how PU.1 contributes to immune activation in human microglia, microarray analysis was performed on primary human mixed glial cultures subjected to siRNA-mediated knockdown of PU.1. Microarray hits were confirmed by qRT-PCR and immunocytochemistry in both mixed glial cultures and isolated microglia following PU.1 knockdown. To identify attenuators of PU.1 expression in microglia, high throughput drug screening was undertaken using a compound library containing FDA-approved drugs. NanoString and immunohistochemistry was utilised to investigate the expression of PU.1 itself and PU.1-regulated mediators in primary human brain tissue derived from neurologically normal and clinically and pathologically confirmed cases of AD. RESULTS: Bioinformatic analysis of gene expression upon PU.1 silencing in mixed glial cultures revealed a network of modified AD-associated microglial genes involved in the innate and adaptive immune systems, particularly those involved in antigen presentation and phagocytosis. These gene changes were confirmed using isolated microglial cultures. Utilising high throughput screening of FDA-approved compounds in mixed glial cultures we identified the histone deacetylase inhibitor vorinostat as an effective attenuator of PU.1 expression in human microglia. Further characterisation of vorinostat in isolated microglial cultures revealed gene and protein changes partially recapitulating those seen following siRNA-mediated PU.1 knockdown. Lastly, we demonstrate that several of these PU.1-regulated genes are expressed by microglia in the human AD brain in situ. CONCLUSIONS: Collectively, these results suggest that attenuating PU.1 may be a valid therapeutic approach to limit microglial-mediated inflammatory responses in AD and demonstrate utility of vorinostat for this purpose.
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Doença de Alzheimer/metabolismo , Regulação da Expressão Gênica/fisiologia , Microglia/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transativadores/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Humanos , Microglia/efeitos dos fármacos , Vorinostat/farmacologiaRESUMO
Brain pericytes are perivascular cells that regulate capillary function, and this localization puts them in a pivotal position for the regulation of central nervous system (CNS) inflammatory responses at the neurovascular unit. Neuroinflammation, driven by microglia and astrocytes or resulting from peripheral leukocyte infiltration, has both homeostatic and detrimental consequences for brain function and is present in nearly every neurological disorder. More recently, brain pericytes have been shown to have many properties of immune regulating cells, including responding to and expressing a plethora of inflammatory molecules, presenting antigen, and displaying phagocytic ability. In this review we highlight the emerging role of pericytes in neuroinflammation and discuss pericyte-mediated neuroinflammation as a potential therapeutic target for the treatment of a range of devastating brain disorders.
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Encéfalo/patologia , Encefalite/patologia , Pericitos/patologia , Animais , Encéfalo/imunologia , Encefalite/tratamento farmacológico , Encefalite/imunologia , Humanos , Pericitos/imunologiaRESUMO
Neuroinflammation contributes to the pathogenesis of several neurological disorders and pericytes are implicated in brain inflammatory processes. Cellular inflammatory responses are orchestrated by transcription factors but information on transcriptional control in pericytes is lacking. Because the transcription factor CCAAT/enhancer binding protein delta (C/EBPδ) is induced in a number of inflammatory brain disorders, we sought to investigate its role in regulating pericyte immune responses. Our results reveal that C/EBPδ is induced in a concentration- and time-dependent fashion in human brain pericytes by interleukin-1ß (IL-1ß). To investigate the function of the induced C/EBPδ in pericytes we used siRNA to knockdown IL-1ß-induced C/EBPδ expression. C/EBPδ knockdown enhanced IL-1ß-induced production of intracellular adhesion molecule-1 (ICAM-1), interleukin-8, monocyte chemoattractant protein-1 (MCP-1) and IL-1ß, whilst attenuating cyclooxygenase-2 and superoxide dismutase-2 gene expression. Altered ICAM-1 and MCP-1 protein expression were confirmed by cytometric bead array and immunocytochemistry. Our results show that knock-down of C/EBPδ expression in pericytes following immune stimulation increased chemokine and adhesion molecule expression, thus modifying the human brain pericyte inflammatory response. The induction of C/EBPδ following immune stimulation may act to limit infiltration of peripheral immune cells, thereby preventing further inflammatory responses in the brain.