Abstract
Microglia play an important role in the pathogenesis of multiple sclerosis and the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). To more fully understand the role of microglia in EAE we characterized microglial transcriptomes before the onset of motor symptoms (pre-onset) and during symptomatic EAE. We compared the transcriptome in brain, where behavioral changes are initiated, and spinal cord, where damage is revealed as motor and sensory deficits. We used a RiboTag strategy to characterize ribosome-bound mRNA only in microglia without incurring possible transcriptional changes after cell isolation. Brain and spinal cord samples clustered separately at both stages of EAE, indicating regional heterogeneity. Differences in gene expression were observed in the brain and spinal cord of pre-onset and symptomatic animals with most profound effects in the spinal cord of symptomatic animals. Canonical pathway analysis revealed changes in neuroinflammatory pathways, immune functions and enhanced cell division in both pre-onset and symptomatic brain and spinal cord. We also observed a continuum of many pathways at pre-onset stage that continue into the symptomatic stage of EAE. Our results provide additional evidence of regional and temporal heterogeneity in microglial gene expression patterns that may help in understanding mechanisms underlying various symptomology in MS.
Highlights
Microglia play an important role in the pathogenesis of multiple sclerosis and the mouse model of Multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE)
This technology allowed us to isolate ribosome-bound mRNA from the frozen brains by immunoprecipitation, without tissue dissociation methods, which has been shown to induce microglial activation markers and has the potential to be associated with cargo contaminations and transcripts that are sequestered from the r ibosomes[30]
While there has been a previous study on microglial transcriptomics in EAE32—it used pooled spinal cord and CNS tissues, not differentiating between microglial functions associated with the motor and sensory changes involving the spinal cord, and those associated with the behavioral changes that would be more evident in higher brain regions
Summary
Microglia play an important role in the pathogenesis of multiple sclerosis and the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). Later stages of the disease, (associated with profound motor impairment) feature the wellknown T cell invasion, synaptic impairment and associated demyelination[18] This continuum of innate (in early EAE) and acquired (late EAE) immune response provides an opportunity to characterize microglial phenotype under different inflammatory conditions. In order to better understand the microglial activation state during pre-onset and symptomatic stages of a disease, we have conducted a transcriptomic profile of the microglia in the brain and spinal cord from EAE animals using RiboTag technology This technology allowed us to isolate ribosome-bound mRNA from the frozen brains by immunoprecipitation, without tissue dissociation methods, which has been shown to induce microglial activation markers and has the potential to be associated with cargo contaminations and transcripts that are sequestered from the r ibosomes[30]. To the best of our knowledge, this is the first study comparing the transcriptomic profile of microglia in the pre-onset and symptomatic brain and spinal cord in EAE
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
