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Updated: Jun 19, 2026
Characterization and Isolation of Mouse Primary Microglia by Density Gradient Centrifugation
Published on: February 16, 2018
M2 microglial exosomal miR-1949 ameliorates sepsis-associated encephalopathy through DKK1/Wnt/β-catenin-mediated
Yue Cao1, Zhaoyang Li1, Xiangqi Liu1
1Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, 110016, People's Republic of China.
Abstract:
Sepsis-associated encephalopathy (SAE), the most common neurological complication of sepsis with high mortality, lacks effective treatments. Although microglia play a significant role in SAE pathogenesis, the mechanisms of M2 microglial exosomes (M2-EXOs) and their microRNAs (miRNAs) remain unclear. The present study demonstrated that both M2 microglial conditioned media (M2-CM) and M2-EXO promote the phenotypic transformation of M1 microglia toward the M2 phenotype. In M2-EXO, among the differentially expressed miRNAs, miR-1949 exhibited the most significant difference. The dual-luciferase assay showed that miR-1949 could bind to the 3'UTR of Dickkopf-related protein 1 (DKK1). Further experiments confirmed that M2-EXO-miR-1949 mimic mediated microglial phenotypic transformation by inhibiting DKK1 and activating the Wnt/β-catenin pathway. Notably, a single injection of M2-EXO (10 μg/mouse, i.c.v.) or M2-EXO-miR-1949 mimic (0.1 nmol/mouse, i.c.v.) significantly reduced the mouse sepsis score (MSS), decreased cortical neural cell damage in SAE mice induced by lipopolysaccharide (LPS), inhibiting abnormal microglial activation and alleviating neuroinflammation. Meanwhile, M2-EXO-miR-1949 mimic markedly inhibited DKK1 and activated the Wnt/β-catenin pathway in vivo. What's more, the effects of M2-EXO-miR-1949 mimic were reversed by the Wnt/β-catenin pathway inhibitor XAV939. In contrast, the effect of M2-EXO-miR-1949 inhibitor (0.1 nmol/mouse, i.c.v.) was opposite to that of M2-EXO-miR-1949 mimic. Furthermore, co-transfection of the M2-EXO-miR-1949 mimic and inhibitor mutually neutralized their opposing effects, resulting in no significant changes in the expression of inflammatory and pathway-related markers, thereby confirming the functional specificity of exosomal miR-1949. In summary, the present study indicates that M2-EXO, especially its contained miR-1949, ameliorates LPS-induced SAE in mice through inhibiting DKK1 to activate the Wnt/β-catenin pathway, thereby leading to microglial phenotypic transformation and neuroinflammation inhibition. This study reveals a novel mechanism by which M2-EXO and miRNA ameliorate SAE, providing a theoretical basis for further studies.
Insights
M2 microglial exosomes (M2-EXOs) carrying miR-1949 can treat sepsis-associated encephalopathy (SAE) by inhibiting DKK1 and activating the Wnt/β-catenin pathway. This reduces neuroinflammation and protects brain cells in mice.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Sepsis-associated encephalopathy (SAE) is a common, high-mortality neurological complication of sepsis with limited treatment options.
- Microglia are implicated in SAE pathogenesis, but the precise mechanisms involving M2 microglial exosomes (M2-EXOs) and their microRNAs (miRNAs) are not fully understood.
Purpose of the Study:
- To investigate the therapeutic potential of M2-EXOs and their specific miRNA cargo in ameliorating SAE.
- To elucidate the molecular mechanisms by which M2-EXOs influence microglial phenotype and neuroinflammation in SAE.
Main Methods:
- M2 microglial conditioned media (M2-CM) and M2-EXOs were used to induce microglial phenotypic transformation.
- MiRNA profiling identified miR-1949 as significantly altered in M2-EXOs.
- Dual-luciferase assays confirmed miR-1949 binding to DKK1.
- In vivo studies involved LPS-induced SAE mouse models treated with M2-EXOs or M2-EXO-miR-1949 mimics/inhibitors, with analysis of neurological scores, cell damage, microglial activation, neuroinflammation, and Wnt/β-catenin pathway markers.
Main Results:
- M2-EXOs promoted M1 to M2 microglial phenotypic transformation.
- miR-1949 in M2-EXOs directly targets DKK1, inhibiting its expression and activating the Wnt/β-catenin pathway.
- M2-EXO-miR-1949 mimic treatment significantly reduced SAE severity, cortical neuron damage, microglial activation, and neuroinflammation in mice.
- Inhibition of the Wnt/β-catenin pathway reversed the therapeutic effects of M2-EXO-miR-1949 mimic.
Conclusions:
- M2-EXOs, particularly via exosomal miR-1949, offer a novel therapeutic strategy for SAE.
- The mechanism involves miR-1949-mediated inhibition of DKK1, leading to Wnt/β-catenin pathway activation, microglial M2 polarization, and suppression of neuroinflammation.
- This study provides a mechanistic basis for developing exosome-based therapies for sepsis-associated encephalopathy.
