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Updated: Feb 18, 2026
Depletion and Reconstitution of Macrophages in Mice
Published on: August 1, 2012
Muscularis Macrophage-Derived ApoE is Dispensable for Maintaining Gut Motility in Mice
Anissa Zouzaf1, Hyeon Jong Jeong2, Sneha Santhosh1
1Translational Research Center for Gastrointestinal Disorders, Department of Chronic Diseases and Metabolism (CHROMETA), KU Leuven, Leuven, Belgium.
Introduction:
Gastrointestinal (GI) motility is controlled by the coordinated activity of enteric neurons, glial cells, and resident muscularis macrophages (mMφs). Apolipoprotein E (ApoE) is highly expressed in mMφs, but its functional role in the gut remains unclear. We hypothesized that mMφ-derived ApoE regulates intestinal motility under physiological and stress conditions.
Methods:
Global ApoE knockout mice, bone marrow chimeras, and macrophage-specific ApoE-deficient mice were used to assess the impact of ApoE loss on gut transit, immune response, and neuromuscular integrity in both homeostatic and postoperative ileus (POI) settings.
Results:
(1) Single-cell RNA sequencing revealed that muscularis macrophages highly express ApoE, with further upregulation after intestinal manipulation. (2) Bone marrow chimera experiments showed that hematopoietic-derived ApoE only partially contribute to the maintenance of gut motility. (3) Global ApoE deficiency led to mild impairment of intestinal transit and increased glial activation, accompanied by an expansion of the macrophage population and elevated gene expression of inflammatory cytokines. (4) Macrophage-specific deletion of ApoE did not affect gastrointestinal transit or tissue morphology under normal conditions.
Conclusion:
Although highly expressed and dynamically regulated in muscularis macrophages, ApoE is largely dispensable for intestinal neuromuscular function at baseline and during postoperative ileus.
Insights
Apolipoprotein E (ApoE) in gut macrophages is highly expressed but dispensable for intestinal motility. Loss of ApoE in macrophages does not impact gut function during normal conditions or postoperative ileus.
Area of Science:
- Gastroenterology
- Immunology
- Neuroscience
Background:
- Gastrointestinal (GI) motility relies on enteric neurons, glial cells, and muscularis macrophages (mMφs).
- Apolipoprotein E (ApoE) is highly expressed in mMφs, but its role in gut function is unknown.
- This study investigates the function of mMφ-derived ApoE in regulating intestinal motility.
Purpose of the Study:
- To determine the role of Apolipoprotein E (ApoE) derived from muscularis macrophages (mMφs) in regulating intestinal motility.
- To assess the impact of ApoE deficiency in mMφs on gut neuromuscular function under homeostatic and stress conditions, including postoperative ileus (POI).
Main Methods:
- Utilized global ApoE knockout mice, bone marrow chimeras, and macrophage-specific ApoE-deficient mice.
- Assessed gut transit, immune responses, and neuromuscular integrity in homeostatic and POI models.
- Employed single-cell RNA sequencing to analyze ApoE expression in mMφs.
Main Results:
- Single-cell RNA sequencing confirmed high ApoE expression in mMφs, increasing after intestinal manipulation.
- Hematopoietic-derived ApoE partially contributes to gut motility maintenance.
- Global ApoE deficiency caused mild intestinal transit impairment, increased glial activation, macrophage expansion, and elevated inflammatory cytokines.
- Macrophage-specific ApoE deletion did not affect GI transit or tissue morphology under normal conditions.
Conclusions:
- Despite high and dynamic expression in mMφs, ApoE is largely dispensable for intestinal neuromuscular function.
- ApoE in mMφs does not play a critical role in maintaining gut motility at baseline or during POI.
