Related Experiment Video
Updated: Sep 9, 2025
Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry
Published on: October 18, 2016
Sympathetic Activation Promotes Kidney Fibrosis in Mice via Macrophage-Derived N2ICD-Enriched Extracellular Vesicles
Huiwen Ren1, Yayan Hou1, Chengsen Mu1
1Department of Pharmacology, Tianjin Key Laboratory of Inflammatory Biology, Center for Cardiovascular Diseases, Haihe Laboratory of Cell Ecosystem, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Key Laboratory of Experimental Hematology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, 300070, China.
Abstract:
Persistent overactivation of the renal sympathetic nervous system drives kidney inflammation and fibrosis. Macrophages contribute to fibrogenesis by secreting various pro-fibrogenic mediators. However, whether the sympathetic nervous system regulates renal fibrosis by modulating macrophage-fibroblast interaction remains unclear. Here, it is demonstrated that norepinephrine (NE)-treated macrophages promoted renal fibroblast activation through the transfer of Notch2 intracellular domain (N2ICD)-enriched extracellular vesicles (EVs) to fibroblasts. Depletion of macrophage mitigated kidney fibrosis in mice subjected to unilateral nephrectomy plus contralateral ischemia-reperfusion injury (Npx-IRI) or repeated low-dose cisplatin (RLDC) regimen. Macrophage-specific deletion of Notch2 or α2B-adrenoceptor disrupted N2ICD-EV formation and protected mice from kidney fibrosis. Mechanistically, N2ICD stabilized Smad3 by preventing its ubiquitin-dependent degradation, thereby enhancing TGF-β signaling to promote fibroblast activation. These findings establish a sympathetic nerve-macrophage-fibroblast axis in renal fibrosis and highlight macrophage-specific Notch2 inhibition as a potential therapeutic strategy.
Insights
The sympathetic nervous system activates kidney fibrosis by promoting macrophage communication with fibroblasts. Inhibiting Notch2 in macrophages may offer a new therapeutic approach for kidney disease.
Area of Science:
- Nephrology
- Immunology
- Cell Biology
Background:
- Overactivation of the renal sympathetic nervous system contributes to kidney inflammation and fibrosis.
- Macrophages play a key role in fibrogenesis by releasing pro-fibrogenic factors.
- The precise mechanisms by which the sympathetic nervous system influences macrophage-fibroblast interactions in renal fibrosis are not fully understood.
Purpose of the Study:
- To investigate the role of the sympathetic nervous system in regulating macrophage-fibroblast interactions in kidney fibrosis.
- To elucidate the molecular mechanisms underlying this interaction.
- To identify potential therapeutic targets for mitigating renal fibrosis.
Main Methods:
- Macrophages were treated with norepinephrine (NE) and their effect on renal fibroblasts was assessed.
- Extracellular vesicles (EVs) from NE-treated macrophages were analyzed for Notch2 intracellular domain (N2ICD) content.
- Mouse models of kidney injury (unilateral nephrectomy plus contralateral ischemia-reperfusion injury and repeated low-dose cisplatin) were used to study renal fibrosis.
- Macrophage-specific deletion of Notch2 or α2B-adrenoceptor was performed in mice.
- Mechanistic studies involved assessing Smad3 stabilization and TGF-β signaling.
Main Results:
- Norepinephrine-treated macrophages enhanced renal fibroblast activation via N2ICD-enriched extracellular vesicles (EVs).
- Macrophage depletion reduced kidney fibrosis in injury models.
- Macrophage-specific deletion of Notch2 or α2B-adrenoceptor ameliorated kidney fibrosis.
- N2ICD stabilized Smad3, preventing its degradation and boosting TGF-β signaling, which promotes fibroblast activation.
Conclusions:
- A novel sympathetic nerve-macrophage-fibroblast axis is identified in the pathogenesis of renal fibrosis.
- Macrophage-derived N2ICD-enriched EVs mediate the pro-fibrotic effects of sympathetic activation.
- Targeting macrophage-specific Notch2 presents a promising therapeutic strategy for kidney fibrosis.
