The significance of microglia and astrocytes in neural development,
in maintaining synaptic connections and homeostasis in the healthy
brain is well established. Microglia are dynamic immune cells of the brain
that elicit an immune response during brain damage and also participate in
tissue repair and regeneration, while astrocytes contribute to the local inflammatory
response by producing proinflammatory cytokines and resolving
neuronal damage through production of anti-inflammatory cytokines and
neurotrophic factors. Recent efforts have focused on elucidating the epigenetic
mechanisms which regulate glial cell behavior in normal and pathologic
states. An important class of epigenetic regulators is microRNAs (miRNAs)
which are small non-coding RNA molecules that regulate gene expression posttranscriptionally.
Certain dysregulated miRNAs contribute to chronic microglial inflammation
in the brain, thereby leading to progression of neurological diseases like Alzheimer’s
disease, traumatic injury, amyotrophic lateral sclerosis and stroke. Further, several miRNAs
are differentially expressed in astrocytes after ischemia and spinal cord injury. Despite
knowledge about miRNAs in neuroinflammation, little is known about effective delivery
routes and pharmacokinetic data for miRNA based therapeutics. This review summarizes the
current research on the role of miRNAs in promoting and inhibiting inflammatory response of
microglia and astrocytes in a disease-specific manner. In addition, miRNA delivery as a
therapeutic strategy to treat neuroinflammation is discussed.
Keywords: Neuroinflammation, microglia, astrocytes, microRNAs, CNS pathologies, neurodegenerative disorders.
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