Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of mouse C57Bl/6 brain response to LPS

ABSTRACT: The study was designed in order to identify genes differentially expressed when glucocorticoid signaling is blocked by a glucocorticoid-receptor antagonist (RU486 â?? mifepristone) in the context of brain inflammation induced by bacterial lipopolysaccharide (LPS). LPS is only able to cause murine brain damage in our experimental conditions upon RU486 pre-treatment. Hence, the study may reveal potential candidate genes to mediate neuroprotection or neurotoxicity. Due to the factorial design of the experiment, RU486 main-effect could be dissociated from the effects resultant of RU486/inflammation interaction. In addition, brain dissection was conducted to verify the effects in the brain side ipsilateral or contralateral to the site of intracerebral LPS infusion. Experiment Overall Design: C57Bl/6 mice received an i.p. injection of vehicle (DMSO - 50 microliters) or RU486 (50 mg/kg) and were submitted to surgery 4 h later. The mice receiving intraparenchymal injections were anesthetized and the right caudate putamen was reached, using a small cannula at the coordinates 0.0 mm anteroposterior, -2.0 mm lateral, and -3.0 mm dorsoventral according to a mouse brain atlas. The animals received an infusion of sterile pyrogen-free saline (1 microliter) or LPS (from Eschericia coli; serotype O55:B5; Sigma L2880 - 2.5 micrograms) over 2 min by means of a microinjection 18 pump. Animals were killed 12 h after the intracerebral infusion. The mice were anesthetized under isofluorane and blood was drawn via cardiac puncture before head decapitation. Brains were removed rapidly from the skulls and placed in cold phosphate buffered saline (PBS) solution. A brain region limited at plane anteroposterior +1.5 to -1.5 and dorsoventral -4.0 was dissected, separated in ipsilateral side and quickly immersed in liquid nitrogen. The tissue was stored at -80 oC until RNA extraction was performed. A total of 37 chips (MOE430A â?? Affymetrix, Santa Clara, CA) were used for oligonucleotide array analysis [one chip per biological sample; 8 groups (contralateral dmso/saline, dmso/LPS, RU486/saline, RU486/LPS and ipsilateral dmso/saline, dmso/LPS, RU486/saline, RU486/LPS) with 4 â?? 6 biological replicates each]. Expression values from the CEL files generated from scanning were obtained using RMA algorithm, available at http://www.bioconductor.org. The expression values were also inspected with GeneSpring software (Silicon Genetics). Statistical analysis was performed considering a factorial linear model according to the methods implemented in Limma package (R project packages are available at http://www.cran.r-project.org).

ORGANISM(S): Mus musculus

SUBMITTER: Ariel Chernomoretz

PROVIDER: E-GEOD-6509 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Genes involved in the balance between neuronal survival and death during inflammation.

Glezer Isaias I Chernomoretz Ariel A David Samuel S Plante Marie-Michèle MM Rivest Serge S

PloS one 20070321 3

Glucocorticoids are potent regulators of the innate immune response, and alteration in this inhibitory feedback has detrimental consequences for the neural tissue. This study profiled and investigated functionally candidate genes mediating this switch between cell survival and death during an acute inflammatory reaction subsequent to the absence of glucocorticoid signaling. Oligonucleotide microarray analysis revealed that following lipopolysaccharide (LPS) intracerebral administration at striat ...[more]

PMID: 17375196

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Project description:Alzheimer’s disease (AD) is a major neurodegenerative disease characterized by extracellular amyloid β (Aβ) plaques and intracellular hyperphosphorylated tau (P-tau). Increasing evidence indicates that extracellular vesicles (EVs) play an important role in AD pathogenesis. We previously reported that the choroid plexus epithelial (CPE) cells, present at the interface between blood and cerebrospinal fluid (CSF), show increased secretion of EVs into the CSF in response to peripheral inflammation. Here, we studied the importance of CP-derived EVs in AD pathogenesis. We observed increased EV levels in the CSF of 7 weeks old transgenic APP/PS1 mice, correlating with higher Aβ CSF levels at this age, while levels normalized with age. To study whether the elevated Aβ CSF levels might be responsible for this increase, mice were intracerebroventricularly (icv) injected with Aβ oligomers (AβO) which revealed a significant increase in the amount of CD9 and CD81 positive EVs in the CSF. The importance of the CPE cells as EV source was shown by in vitro analysis of AβO stimulated primary CPE cells and in vivo analysis of the CP by transmission electron microscopy (TEM). Evaluation of EV marker immunostaining, both from AβO icv injected mice and APP/PS1 mice, confirmed the upregulation of EV biogenesis in the CP. Interestingly, AβO-induced, CP-derived EVs induced pro-inflammatory effects in mixed cortical cultures (MCC) whereas proteome analysis revealed the presence of complement protein C3, amongst other inflammatory proteins. Additionally, we could show for the first time that AβO induce an upregulation of C3 in CPE cells. These data highlight the CP and CP-derived, C3-containing EVs as novel players in the emerging importance of the complement pathway in the pathogenesis of AD. Strikingly, inhibition of EV production using GW4869 resulted in protection against the AβO-induced cognitive decline. In conclusion, our results show that intraventricular AβO induce both C3 activation and EV secretion by the CP and that these EVs contain pro-inflammatory molecules, including C3, which play a role in neuroinflammation and loss of cognition. This suggests that inhibition of EV production by the CP might be an interesting therapeutic approach to be explored in the prevention or treatment of AD.

Dataset Information

Transcription profiling of mouse C57Bl/6 brain response to LPS

Publications

Genes involved in the balance between neuronal survival and death during inflammation.

Similar Datasets

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