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Updated: May 15, 2025
Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation
Published on: April 3, 2017
Adipose Tissue Macrophages in Metabolic Dysfunction-Associated Steatohepatitis Secrete Extracellular Vesicles That
Theresa V Rohm1, Felipe Castellani Gomes Dos Reis1, Karina Cunha E Rocha1
1Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, La Jolla, California.
Background & Aims:
Given the need for effective interventions in metabolic dysfunction-associated steatohepatitis (MASH), understanding the role of adipose tissue macrophage (ATM)-derived small extracellular vesicles (sEVs) is important. We aimed to evaluate the contribution of MASH-ATM-sEVs to the development of liver fibrosis in obese male mice.
Methods:
Using flow cytometry and nanoparticle tracking analysis, we characterized MASH-ATMs and their secreted sEVs. We assessed the fibrogenic effects of sEVs from MASH-ATMs or anti-inflammatory macrophages on stellate cells in vitro and in mice in vivo. In addition, we isolated Dicer knockdown microRNA (miRNA)-depleted sEVs from MASH-ATMs and cotreated stellate cells with MASH-ATM-sEVs and miR-155 or miR-34a antagomirs.
Results:
MASH-ATMs exhibited a pro-inflammatory and lipid-associated phenotype, secreting sEVs enriched in the fibrogenic miRNAs, miR-155 and miR-34a, which also down-regulate Pparg. In vitro, MASH-ATM-sEVs induced hepatic stellate cell activation and fibrogenesis and exacerbated liver fibrosis when administered to obese mice. In addition, anti-inflammatory macrophage sEVs mitigated fibrosis both in vitro and in vivo. miRNA-free Dicer knockdown-MASH-ATM-sEVs were without effects and cotreatment with miR-155/miR-34a antagomirs blocked the effects of MASH-ATM-sEVs to induce hepatic stellate cell activation.
Conclusions:
This study demonstrated the role of MASH-ATM-sEVs in promoting liver fibrosis in obesity. Identification of the fibrogenic miRs, miR-155, and miR-34a, within MASH-ATM-sEVs, highlights the mechanistic importance of extrahepatic signals in MASH. These findings showed the therapeutic potential of modulating macrophage phenotypes and their sEV cargo to ameliorate MASH.
Insights
Small extracellular vesicles (sEVs) from metabolic dysfunction-associated steatohepatitis (MASH) adipose tissue macrophages promote liver fibrosis. Targeting fibrogenic miRNAs within these MASH-ATM-sEVs offers therapeutic potential for MASH.
Area of Science:
- Cell biology
- Immunology
- Hepatology
Background:
- Metabolic dysfunction-associated steatohepatitis (MASH) requires effective interventions.
- Adipose tissue macrophage (ATM)-derived small extracellular vesicles (sEVs) may play a role in MASH pathogenesis.
- Understanding MASH-ATM-sEVs is crucial for developing new therapies.
Purpose of the Study:
- To evaluate the contribution of MASH-ATM-sEVs to liver fibrosis development in obese mice.
- To identify specific miRNAs within MASH-ATM-sEVs that drive fibrogenesis.
- To explore the therapeutic potential of targeting MASH-ATM-sEVs.
Main Methods:
- Characterization of MASH-ATMs and their secreted sEVs using flow cytometry and nanoparticle tracking analysis.
- In vitro and in vivo assessment of fibrogenic effects of sEVs on hepatic stellate cells.
- Isolation of miRNA-depleted sEVs and cotreatment with specific miRNA antagomirs.
Main Results:
- MASH-ATMs secreted sEVs enriched in fibrogenic miRNAs (miR-155, miR-34a) that down-regulate Pparg.
- MASH-ATM-sEVs induced hepatic stellate cell activation and exacerbated liver fibrosis in obese mice.
- Anti-inflammatory macrophage sEVs mitigated fibrosis, while miRNA-free MASH-ATM-sEVs had no effect.
Conclusions:
- MASH-ATM-sEVs promote liver fibrosis in obesity through fibrogenic miRNAs.
- Extrahepatic signals, specifically miRNAs in sEVs, are mechanistically important in MASH.
- Modulating macrophage phenotypes and their sEV cargo holds therapeutic promise for MASH.
