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Beta-amyloid peptide secretion by a microglial cell line is induced by beta-amyloid-(25-35) and lipopolysaccharide
L Bitting1, A Naidu, B Cordell
1Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305, USA.
Abstract:
beta-Amyloid protein (betaAP) deposition is a neuropathologic hallmark of Alzheimer's disease (AD). Yet, the source of cerebral betaAP in AD is controversial. We examined the production of betaAP by the BV-2 immortalized microglial cell line using a sensitive enzyme immunoassay. Constitutive production of betaAP was detected in conditioned media from unstimulated BV-2 cells. Further, production of betaAP was induced by treatment of cultures by lipopolysaccharide (LPS) or betaAP-(25-35) and was inhibited by the calpain protease inhibitor MDL 28170. Treatment of BV-2 cells with LPS or betaAP-(25-35) did not affect cell-associated beta-amyloid precursor protein levels. These findings suggest that microglia may be an important source of betaAP in AD, and that microglial production of betaAP may be augmented by proinflammatory stimuli or by betaAP itself.
Insights
Microglia, immune cells in the brain, produce beta-amyloid protein (betaAP), a hallmark of Alzheimer's disease (AD). Their production increases with inflammation or betaAP exposure, suggesting microglia are a key source of betaAP in AD.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- beta-Amyloid protein (betaAP) deposition is a key feature of Alzheimer's disease (AD) neuropathology.
- The precise origin of cerebral betaAP in AD remains a subject of debate.
- Microglia, the resident immune cells of the central nervous system, play critical roles in AD pathogenesis.
Purpose of the Study:
- To investigate the production of betaAP by the BV-2 immortalized microglial cell line.
- To determine if microglial betaAP production is modulated by inflammatory stimuli or betaAP itself.
Main Methods:
- Utilized a sensitive enzyme immunoassay to quantify betaAP in conditioned media from BV-2 cells.
- Treated BV-2 cells with lipopolysaccharide (LPS) and betaAP-(25-35) to assess induction of betaAP production.
- Investigated the effect of the calpain protease inhibitor MDL 28170 on betaAP production.
- Measured cell-associated beta-amyloid precursor protein (APP) levels.
Main Results:
- Constitutive production of betaAP was detected in unstimulated BV-2 microglial cultures.
- Microglial betaAP production was significantly induced by LPS and betaAP-(25-35) treatment.
- The calpain inhibitor MDL 28170 effectively inhibited microglial betaAP production.
- LPS or betaAP-(25-35) treatment did not alter cell-associated APP levels, indicating production rather than release of pre-formed protein.
Conclusions:
- Microglia represent a significant source of betaAP in the context of Alzheimer's disease.
- Proinflammatory stimuli, such as LPS, and betaAP itself can augment microglial betaAP production.
- These findings highlight the potential role of microglial activity in driving AD neuropathology and suggest therapeutic targets for modulating betaAP levels.