Background: Microglia are considered the resident immune cells of the central nervous system (CNS). In response to harmful stimuli, an inflammatory reaction ensues in which microglia are activated in a sequenced spectrum of pro- and antiinflammatory phenotypes that are akin to the well-characterized polarization states of peripheral macrophages. A "classically" activated M1 phenotype is known to eradicate toxicity. The transition to an "alternatively" activated M2 phenotype encompasses neuroprotection and repair. In recent years, inflammation has been considered an accompanying pathology in response to the accumulation of extracellular amyloid-β (Aβ) in Alzheimer's disease (AD). This study aimed to drive an M2a-biased immune phenotype with IL-4 in vitro and in vivo and to determine the subsequent effects on microglial activation and Aβ pathology. Methods: In vitro, exogenous IL-4 was applied to BV2 microglial cell cultures to evaluate the temporal progression of microglial responses. In vivo, intracranial injections of an adeno-associate-virus (AAV) viral vector were performed to assess long-term expression of IL-4 in the frontal cortex and hippocampus of Aβ-depositing, APP/PS1 transgenic mice. Quantitative real-time PCR was used to assess the fold change in expression of biomarkers representing each of the microglial phenotypes in both the animal tissue and the BV2 cells. ELISAs quantified IL-4 expression and Aβ levels. Histological staining permitted quantification of microglial and astrocytic activity. Results: Both in vitro and in vivo models showed an enhanced M2a phenotype, and the in vivo model revealed a trend toward a decreased trend in Aβ deposition. Conclusions: In summary, this study offers insight into the therapeutic potential of microglial immune response in AD.
|Journal||Journal of Neuroinflammation|
|State||Published - Dec 12 2015|
Bibliographical noteFunding Information:
These studies were funded by NIH grant NS079637 (DMW) and NIH grant P20GM103486 (PI: L.B. Hersh, pilot grant awarded to DMW), assisted by the Viral Core of the COBRE in the Molecular Basis of Human Disease (NCRR 5P20RR020171, MDM and L.B. Hersh, co-PIs) and by the ADC Biostatistics Core (P30AG028383). The contents of this manuscript are solely the responsibility of the authors and do not necessarily represent the official views of the NIH, the NINDS or the NIGMS.
© 2015 Latta et al.
- Alzheimer's disease
ASJC Scopus subject areas
- Neuroscience (all)
- Cellular and Molecular Neuroscience