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Updated: May 23, 2026
Isolation, Characterization, and Purification of Macrophages from Tissues Affected by Obesity-related Inflammation
Published on: April 3, 2017
Adipose tissue macrophages: MR tracking to monitor obesity-associated inflammation
Alain Luciani1, Sophie Dechoux, Vanessa Deveaux
1INSERM, U955, Equipe 17, Créteil, 94000, France. alain.luciani@hmn.aphp.fr
Purpose:
To investigate whether cellular imaging by using ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging can allow detection and quantification of adipose tissue macrophage-related inflammation within adipose tissue in a mouse model.
Materials And Methods:
Experimental protocols were conducted in accordance with French government policies. Adipose tissue macrophages were detected and quantified with a 4.7-T MR imager in ob/ob obese mice on the basis of the signal variance of adipose tissue triggered by injection of P904 iron oxide nanoparticles (USPIO). Mice were either intravenously injected with 1000 μmol of iron per kilogram of body weight of P904 (10 ob/ob and 11 ob/+) or used as noninjected control animals (seven ob/ob and six ob/+). Three-dimensional T2*-weighted gradient-echo MR images were acquired 10 days after intravenous injection. MR imaging signal variance in mice was correlated to adipose tissue macrophage quantification by using monoclonal antibody to F4/80 immunostaining, to proinflammatory marker quantification by using reverse transcription polymerase chain reaction (CCl2, Tnfα, Emr1), and to P904 quantification by using electron paramagnetic resonance imaging. Quantitative data were compared by using the Mann-Whitney or Student t test, and correlations were performed by using the Pearson correlation test.
Results:
MR imaging measurements showed a significant increase in adipose tissue signal variance in ob/ob mice compared with ob/+ controls or noninjected animals (P < .0001), which was consistent with increased P904 uptake by adipose tissue in ob/ob mice. There was a significant and positive correlation between adipose tissue macrophage quantification at MR imaging and P904 iron oxide content (r = 0.87, P < .0001), adipose tissue macrophage-related inflammation at immunohistochemistry (r = 0.60, P < .01), and adipose tissue proinflammatory marker expression (r = 0.55, 0.56, and 0.58 for CCl2, Tnfα, and Emr1, respectively; P < .01).
Conclusion:
P904 USPIO-enhanced MR imaging is potentially a tool for noninvasive assessment of adipose tissue inflammation during experimental obesity. These results provide the basis for translation of MR imaging into clinical practice as a marker of patients at risk for metabolic syndrome.
Insights
Ultrasmall superparamagnetic iron oxide-enhanced MRI can detect and quantify adipose tissue inflammation in obese mice. This imaging technique shows promise for assessing metabolic syndrome risk in patients.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Metabolic Research
Background:
- Adipose tissue inflammation is a hallmark of obesity and metabolic syndrome.
- Current methods for assessing adipose tissue inflammation are invasive.
- Novel non-invasive imaging techniques are needed for early detection and monitoring.
Purpose of the Study:
- To evaluate ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging for detecting and quantifying adipose tissue macrophage-related inflammation.
- To assess the correlation between USPIO-enhanced MR imaging findings and established markers of inflammation and macrophage infiltration in a mouse model of obesity.
Main Methods:
- Obese (ob/ob) and lean (ob/+) mice were injected with P904 USPIO nanoparticles.
- Three-dimensional T2*-weighted gradient-echo MR images were acquired 10 days post-injection.
- MR imaging signal variance was correlated with F4/80 immunostaining, inflammatory gene expression (CCl2, Tnfα, Emr1), and USPIO quantification via electron paramagnetic resonance imaging.
Main Results:
- MR imaging demonstrated significantly increased adipose tissue signal variance in obese mice compared to controls.
- A strong positive correlation was observed between MR imaging signal variance and USPIO iron oxide content in adipose tissue.
- Significant correlations were found between MR imaging findings and macrophage quantification, as well as expression of key proinflammatory markers.
Conclusions:
- P904 USPIO-enhanced MR imaging is a viable non-invasive tool for assessing adipose tissue inflammation in experimental obesity.
- These findings support the potential translation of this MR imaging technique into clinical practice for identifying patients at risk for metabolic syndrome.
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