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Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Melatonin regulates microglial M1/M2 polarization via AMPKα2-mediated mitophagy in attenuating sepsis-associated
Yang Yang1, Jinyong Ke1, Yang Cao1
1Department of Anesthesiology, Nanfang Hospital, Southern Medical University; The key Laboratory of Precision Anesthesia & perioperative Organ Protection, Guangzhou, Guangdong, 510515, China.
Background:
Sepsis-associated encephalopathy (SAE) is a disease characterized by neuroinflammation and cognitive dysfunction caused by systemic infection. Inflammation-induced microglial activation is closely associated with neuroinflammation in SAE. It is widely understood that melatonin has strong anti-inflammatory and immunomodulatory properties beneficial for sepsis-related brain damage. However, the mechanism of melatonin action in SAE has not been fully elucidated.
Methods:
The SAE cell model and SAE mouse model were induced by lipopolysaccharide (LPS). Behavioral tests were performed to analyze cognitive function. Microglial markers and M1/M2 markers were measured by immunofluorescence. Mitophagy was assessed by western blot, mt-Keima and transmission electron microscopy experiments. Immunoprecipitation and co-immunoprecipitation assays investigated the interactions between AMP-activated protein kinase α2 (AMPKα2) and PTEN-induced putative kinase 1 (PINK1).
Results:
Melatonin suppresses LPS-induced microglia M1 polarization by enhancing mitophagy, thereby attenuating LPS-induced neuroinflammation and behavioral deficits. However, inhibition or knockdown of AMPKα2 can inhibit the enhancement of melatonin on mitophagy, then weaken its promotion of microglia polarization towards M2 phenotype, and eliminate its protective effect on brain function. Furthermore, melatonin enhances mitophagy through activating AMPKα2, promotes PINK1 Ser495 site phosphorylation, and ultimately regulates microglial polarization from M1 to M2.
Conclusions:
Our findings demonstrate that melatonin facilitates microglia polarization towards M2 phenotype to alleviate LPS-induced neuroinflammation, primarily through AMPKα2-mediated enhancement of mitophagy.
Insights
Melatonin protects the brain from sepsis by enhancing mitophagy, a cellular process that clears damaged mitochondria. This action shifts microglia towards an anti-inflammatory state, improving cognitive function and reducing neuroinflammation.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Sepsis-associated encephalopathy (SAE) involves neuroinflammation and cognitive decline, with microglial activation playing a key role.
- Melatonin is known for its anti-inflammatory effects, but its precise mechanism in SAE remains unclear.
Purpose of the Study:
- To elucidate the mechanism by which melatonin alleviates neuroinflammation and cognitive dysfunction in sepsis-associated encephalopathy.
- To investigate the role of mitophagy and AMP-activated protein kinase α2 (AMPKα2) in melatonin's protective effects against SAE.
Main Methods:
- Established sepsis-associated encephalopathy (SAE) cell and mouse models using lipopolysaccharide (LPS).
- Assessed cognitive function via behavioral tests and analyzed microglial polarization (M1/M2 markers) using immunofluorescence.
- Investigated mitophagy using western blot, mt-Keima, and transmission electron microscopy; examined protein interactions via immunoprecipitation assays.
Main Results:
- Melatonin treatment suppressed LPS-induced M1 microglia polarization by enhancing mitophagy, reducing neuroinflammation and improving behavioral deficits.
- AMPKα2 activation was crucial for melatonin's enhancement of mitophagy and subsequent M2 microglia polarization.
- Melatonin promotes mitophagy via AMPKα2 activation and PINK1 phosphorylation, shifting microglia from M1 to M2 phenotype.
Conclusions:
- Melatonin alleviates LPS-induced neuroinflammation in SAE by promoting M2 microglia polarization.
- This protective effect is primarily mediated by AMPKα2-dependent enhancement of mitophagy.
