Circulation Research | EHD1 Exacerbates Atherosclerosis by Promoting TNFR2 Endocytic Recycling and Stabilizing Sortilin

This study reveals the critical regulatory role of EHD1 in macrophage inflammatory responses, providing new experimental design insights into the immune mechanisms of atherosclerosis, suggesting that targeting membrane trafficking pathways may represent a novel strategy for intervening in chronic inflammation.

 

Literature Overview

The study, 'Macrophage EHD1 Promotes Inflammation and Stabilizes Sortilin to Accelerate Atherosclerosis,' published in the journal Circulation Research, systematically investigates the role of the endocytic membrane trafficking regulator EHD1 in atherosclerosis progression. The research reveals that EHD1 is highly expressed in pro-inflammatory macrophages and promotes inflammation through a dual mechanism: first, by accelerating the endocytic recycling of TNFR2 to activate the NF-κB signaling pathway, and second, by interacting with the retromer complex to stabilize sortilin, thereby exacerbating plaque formation. This work is the first to link EHD family proteins to atherosclerotic pathology, expanding the molecular understanding of macrophage polarization regulation.

Background Knowledge

Atherosclerosis is a vascular disease centered on chronic inflammation, where macrophages—being the predominant immune cells in plaques—play a key role in disease progression through sustained activation and secretion of pro-inflammatory factors. Although the NF-κB pathway is widely recognized as a central hub in inflammation, the dynamic regulation of upstream receptors such as TNFR2 at the cell membrane remains poorly understood. Additionally, genome-wide association studies (GWAS) have identified sortilin as a risk factor for cardiovascular disease, yet its regulatory mechanisms in immune cells remain unclear. A major research bottleneck lies in the lack of systematic analysis of membrane protein trafficking in immune-metabolic diseases. This study focuses on EHD1, an evolutionarily conserved regulator of endocytic trafficking, to explore whether it influences macrophage function by modulating the subcellular localization of TNFR2 or sortilin, thus bridging the gap between genetic risk and functional mechanisms.

 

 

Research Methods and Experiments

The authors used the Ldlr−/− mouse model, generating systemic or hematopoietic-specific Ehd1 knockout animals via bone marrow transplantation, and induced atherosclerosis with a Western diet to assess plaque size and inflammatory status. Single-cell RNA sequencing (scRNA-seq) was performed on aortic CD45+ immune cells to analyze transcriptomic changes and to reveal the impact of EHD1 deficiency on macrophage subsets and intercellular communication. In vitro experiments utilized bone marrow-derived macrophages (BMDMs) with siRNA knockdown or gene knockout, stimulated with LPS or oxLDL, to evaluate inflammatory cytokine expression and signaling pathway activation. Pulse-chase assays were conducted to measure TNFR2 endocytic recycling efficiency, while co-immunoprecipitation and cycloheximide (CHX) chase experiments assessed the effect of EHD1 on sortilin protein stability.

Key Conclusions and Perspectives

• EHD1 is specifically upregulated in pro-inflammatory macrophages in both human and mouse atherosclerotic plaques, and its expression increases with disease progression, suggesting its potential as a biomarker for disease staging and future classification studies.
• Ehd1 deficiency significantly reduces plaque area without affecting fibrous cap thickness or necrotic core size, indicating that EHD1 primarily regulates plaque growth rather than stability, making it more suitable as an early intervention target than a strategy for late-stage plaque stabilization.
• scRNA-seq analysis shows that EHD1 deficiency suppresses NF-κB signaling and inflammatory pathways such as IL-6 in macrophages, and weakens their interactions with T cells and neutrophils, highlighting EHD1’s central role in shaping the pro-inflammatory immune microenvironment and suggesting future studies should explore its regulatory network in intercellular communication.
• EHD1 enhances TNFα signaling and NF-κB activation by promoting TNFR2 endocytic recycling and maintaining its surface expression, offering a new perspective for targeting TNFR2 signaling—namely, by modulating its membrane trafficking rather than directly blocking ligand binding.
• EHD1 interacts with the retromer complex to stabilize sortilin and prevent its lysosomal degradation, thereby enhancing IL-6 secretion and foam cell formation. This establishes a regulatory axis from the genetic risk factor sortilin to functional phenotypes, suggesting that drug development could target the EHD1-sortilin protein interaction interface.

Research Significance and Prospects

This study incorporates membrane trafficking regulation into the core pathogenic mechanisms of atherosclerosis, positioning EHD1 as a key node linking genetic risk to inflammatory phenotypes, and providing a theoretical basis for developing novel anti-inflammatory therapies. Given that existing anti-inflammatory treatments, such as IL-1β targeting, have shown clinical benefits, targeting EHD1 may enable broader upstream suppression with higher intervention efficiency.

From a drug development perspective, small molecules inhibiting the ATPase domain of EHD1 or its protein-protein interaction with the retromer complex may represent viable future strategies. Moreover, EHD1 is also expressed in B cells and dendritic cells, suggesting potential roles in adaptive immunity, warranting further investigation in autoimmune diseases.

In clinical monitoring, measuring EHD1 expression in peripheral blood monocytes or plaque macrophages may help identify patients with high inflammatory burden, enabling precise risk stratification. Additionally, this mechanism may extend to other chronic inflammatory conditions such as metabolic syndrome or non-alcoholic fatty liver disease, indicating broad pathophysiological relevance.

 

 

Conclusion

This study establishes the critical role of EHD1 in macrophage-mediated atherosclerosis progression, revealing its dual mechanism—promoting TNFR2 recycling to activate NF-κB and stabilizing sortilin to enhance inflammatory secretion—in driving chronic inflammation. This discovery not only deepens our understanding of endocytic membrane trafficking in immune-metabolic diseases but also provides a new paradigm for re-evaluating inflammatory diseases from the perspective of 'receptor dynamic regulation.' From bench to bedside, EHD1 may emerge as a target with both diagnostic and therapeutic potential: its expression could serve as a biomarker of inflammatory activity, while its function could be targeted by small molecules or protein-protein interaction inhibitors. In combination with existing lipid-lowering therapies, targeting EHD1 may enable dual 'lipid-lowering + anti-inflammatory' intervention, potentially significantly reducing residual cardiovascular risk. Future studies should develop tissue-specific Ehd1 knockout models to clarify its roles in different immune cell subsets and explore its expression patterns and prognostic associations in human patients, advancing its translation into clinical applications.

 

Fanglin Ma, Yu Liu, Yang Xu, Xin Huang, and Bishuang Cai. Macrophage EHD1 Promotes Inflammation and Stabilizes Sortilin to Accelerate Atherosclerosis. Circulation research.