Visualisation of the kinetics of macrophage infiltration during experimental autoimmune encephalomyelitis by magnetic
Kurt Baeten1, Jerome Ja Hendriks, Niels Hellings
1Hasselt University, Biomedical Research Institute and School of Life Sciences, Transnational University Limburg, Belgium.
Abstract:
Macrophages are considered to be the predominant effector cells in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Ultra small particles of iron oxide (USPIO) can be used to detect macrophage infiltrates in the CNS with magnetic resonance imaging (MRI). Here, we investigated whether the kinetics of lesion formation in EAE can be visualised by altering the time point of USPIO injection and the time interval between particle injection and MRI. When USPIO are systemically injected 24 h before MRI, hypo intense regions are detected in different brain regions depending on the disease stage. These regions correspond to sites of macrophage infiltration. A more complete visualisation of sites of inflammation is accomplished by USPIO injection at disease onset and postponing MRI to top of disease. This study demonstrates that the distribution pattern and amount of inflammatory lesions detected with USPIO, depends on timing of USPIO administration and subsequent MRI. These findings are important for a correct application and interpretation of USPIO dependent contrast imaging of CNS inflammation.
Insights
Timing of ultra-small iron oxide particle (USPIO) injection and MRI timing impacts visualization of macrophage infiltration in experimental autoimmune encephalomyelitis (EAE). This is crucial for interpreting USPIO-enhanced MRI of central nervous system (CNS) inflammation in diseases like multiple sclerosis (MS).
Area of Science:
- Neuroimmunology
- Neuroinflammation
- Medical Imaging
Background:
- Macrophages are key effector cells in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE).
- Ultra-small particles of iron oxide (USPIO) enable detection of macrophage infiltrates in the central nervous system (CNS) using magnetic resonance imaging (MRI).
Purpose of the Study:
- To investigate if altering USPIO injection timing and MRI acquisition intervals can visualize lesion development kinetics in EAE.
- To determine the optimal timing for USPIO administration and MRI for comprehensive imaging of CNS inflammation.
Main Methods:
- Systemic injection of USPIO at different time points relative to MRI acquisition in EAE models.
- Magnetic resonance imaging (MRI) to detect USPIO-enhanced hypo intense regions indicative of macrophage infiltration.
Main Results:
- USPIO injection 24 hours before MRI revealed hypo intense regions in various brain areas, correlating with disease stage and macrophage infiltration.
- USPIO injection at disease onset with delayed MRI acquisition (at peak disease) provided more complete visualization of inflammatory lesions.
- The observed distribution and extent of inflammatory lesions detected by USPIO-enhanced MRI were dependent on the timing of both USPIO administration and MRI.
Conclusions:
- The timing of USPIO administration and subsequent MRI significantly influences the detection and visualization of inflammatory lesions in EAE.
- These findings are critical for the accurate application and interpretation of USPIO-enhanced MRI in the context of CNS inflammatory diseases like MS.
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