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Macrophage colony-stimulating factor augments beta-amyloid-induced interleukin-1, interleukin-6, and nitric oxide
G M Murphy1, L Yang, B Cordell
1Neuroscience Research Laboratories, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305-5485, USA. greer.murphy@stanford.edu
Abstract:
In Alzheimer's disease (AD), a chronic cerebral inflammatory state is thought to lead to neuronal injury. Microglia, intrinsic cerebral immune effector cells, are likely to be key in the pathophysiology of this inflammatory state. We showed that macrophage colony-stimulating factor, a microglial activator found at increased levels in the central nervous system in AD, dramatically augments beta-amyloid peptide (betaAP)-induced microglial production of interleukin-1, interleukin-6, and nitric oxide. In contrast, granulocyte macrophage colony-stimulating factor, another hematopoietic cytokine found in the AD brain, did not augment betaAP-induced microglial secretory activity. These results indicate that increased macrophage colony-stimulating factor levels in AD could magnify betaAP-induced microglial inflammatory cytokine and nitric oxide production, which in turn could intensify the cerebral inflammatory state by activating astrocytes and additional microglia, as well as directly injuring neurons.
Insights
Macrophage colony-stimulating factor in Alzheimer's disease (AD) brain exacerbates beta-amyloid's inflammatory effects. This microglial activation may worsen neuroinflammation and neuronal injury in AD patients.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Alzheimer's disease (AD) is characterized by chronic neuroinflammation.
- Microglia, the brain's immune cells, play a crucial role in AD pathogenesis.
- Elevated levels of certain cytokines are observed in the AD brain.
Purpose of the Study:
- To investigate the role of macrophage colony-stimulating factor (M-CSF) in modulating microglial responses in Alzheimer's disease.
- To compare the effects of M-CSF and granulocyte-macrophage colony-stimulating factor (GM-CSF) on beta-amyloid peptide (betaAP)-induced microglial activation.
Main Methods:
- Primary microglial cultures were treated with betaAP in the presence or absence of M-CSF or GM-CSF.
- Production of inflammatory mediators, including interleukin-1, interleukin-6, and nitric oxide, was measured.
Main Results:
- M-CSF significantly augmented betaAP-induced production of interleukin-1, interleukin-6, and nitric oxide by microglia.
- GM-CSF did not augment betaAP-induced microglial secretory activity.
- These findings suggest M-CSF amplifies inflammatory responses in AD.
Conclusions:
- Increased M-CSF levels in the AD brain may potentiate betaAP-induced microglial inflammatory cytokine and nitric oxide production.
- This amplified inflammatory response could intensify neuroinflammation, activate astrocytes and microglia, and contribute to direct neuronal injury in AD.