UAB TSPO PET Neuroinflammation in PD Trial
Overview
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UAB_TSPO_PET_Neuroinflammation["UAB TSPO PET Neuroinflammation in PD Trial"] -->|"references"| GFAP["GFAP"]
UAB_TSPO_PET_Neuroinflammation["UAB TSPO PET Neuroinflammation in PD Trial"] -->|"references"| NLRP3["NLRP3"]
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This Phase 1/2 clinical trial conducted at the University of Alabama at Birmingham (UAB) uses TSPO PET imaging to study neuroinflammation in Parkinson's disease. The trial investigates the role of translocator protein (TSPO) as a biomarker for microglial activation and neuroinflammatory processes in PD.
| Field | Value |
|-------|-------|
| Trial ID | NCT03457493 |
| Phase | Phase 1/2 |
| Status | Completed |
| Institution | University of Alabama at Birmingham |
| Imaging Agent | TSPO PET tracer |
| Target | Microglial activation/neuroinflammation |
Neuroinflammation in Parkinson's Disease
The Inflammatory Landscape
Neuroinflammation is a central pathological feature of Parkinson's disease, involving both the central nervous system (CNS) and peripheral immune systems. The inflammatory response in PD is complex and involves multiple cell types and signaling pathways.
Key Inflammatory Cells
...UAB TSPO PET Neuroinflammation in PD Trial
Overview
Mermaid diagram (expand to render)
This Phase 1/2 clinical trial conducted at the University of Alabama at Birmingham (UAB) uses TSPO PET imaging to study neuroinflammation in Parkinson's disease. The trial investigates the role of translocator protein (TSPO) as a biomarker for microglial activation and neuroinflammatory processes in PD.
| Field | Value |
|-------|-------|
| Trial ID | NCT03457493 |
| Phase | Phase 1/2 |
| Status | Completed |
| Institution | University of Alabama at Birmingham |
| Imaging Agent | TSPO PET tracer |
| Target | Microglial activation/neuroinflammation |
Neuroinflammation in Parkinson's Disease
The Inflammatory Landscape
Neuroinflammation is a central pathological feature of Parkinson's disease, involving both the central nervous system (CNS) and peripheral immune systems. The inflammatory response in PD is complex and involves multiple cell types and signaling pathways.
Key Inflammatory Cells
| Cell Type | Role in PD | Activation Markers |
|-----------|-----------|--------------------|
| Microglia | CNS immune surveillance | TSPO, CD68, Iba1 |
| Astrocytes | Neuroprotective/glial scar | GFAP, S100B |
| T cells | Peripheral infiltration | CD3, CD4, CD8 |
| B cells | Humoral immunity | CD19, CD20 |
| Peripheral monocytes | Blood-brain barrier crossing | CD14, CD16 |
Microglial Activation States
Microglia can adopt different activation states:
M1 (Pro-inflammatory):
- Produces IL-1β, TNF-α, IL-6
- Generates reactive oxygen species
- Promotes neuronal death
- Expresses high TSPO
M2 (Anti-inflammatory):
- Produces IL-10, TGF-β
- Releases neurotrophic factors
- Promotes tissue repair
- Expresses moderate TSPO
Temporal Pattern of Inflammation
| Disease Stage | Inflammatory Activity |
|--------------|----------------------|
| Prodromal | Low-grade chronic inflammation |
| Early PD | Active microglial activation |
| Mid-stage PD | Peak inflammatory response |
| Advanced PD | Burned-out inflammation, neuronal loss |
TSPO as Neuroinflammation Biomarker
TSPO Biology
Translocator protein (TSPO), formerly known as the peripheral benzodiazepine receptor, is a mitochondrial protein located primarily on the outer mitochondrial membrane. Key characteristics:
- Molecular weight: 18 kDa
- Location: Outer mitochondrial membrane
- Expression: Low in resting microglia, high in activated microglia
- Function: Cholesterol transport, mitochondrial function, apoptosis regulation
TSPO Expression in Neurological Disease
| Condition | TSPO Expression | PET Signal |
|-----------|-----------------|-------------|
| Healthy brain | Low baseline | Low |
| Alzheimer's disease | Elevated | Increased |
| Parkinson's disease | Elevated | Increased |
| Multiple sclerosis | Highly elevated | Very high |
| Stroke | Regionally elevated | Variable |
TSPO PET Tracers
Multiple TSPO PET tracers have been developed:
| Tracer | Affinity | Selectivity | Limitations |
|--------|----------|-------------|--------------|
| [11C]PK11195 | High | Good | Short half-life, nonspecific binding |
| [11C]PBR28 | High | Moderate | Genetic polymorphism (Ala147Thr) |
| [18F]FEPPA | High | Good | Metabolite issues |
| [18F]DPA-714 | High | Excellent | Optimal imaging time |
| [11C]ABP688 | Moderate | Excellent | Low signal in disease |
PET Imaging Approach
The trial employs TSPO-binding PET radiotracers to visualize and quantify microglial activation in vivo:
- Higher TSPO binding indicates increased neuroinflammation
- Regional patterns can reveal disease-specific inflammatory signatures
- Longitudinal imaging can track disease progression and treatment response
Imaging Protocol
Tracer injection: Radioligand administration
PET acquisition: 60-90 minutes dynamic imaging
MRI coregistration: Anatomical reference
Quantification: Binding potential calculation
Analysis: Voxel-based and region-of-interest approachesQuantification Methods
| Metric | Description | Clinical Use |
|--------|-------------|--------------|
| BPND | Binding potential (non-displaceable) | Target engagement |
| SUVR | Standardized uptake value ratio | Relative binding |
| VT | Distribution volume | Absolute measure |
| Distribution pattern | Regional involvement | Disease staging |
Study Design
Objectives
Primary Objectives:
- Characterize TSPO binding patterns in PD patients vs controls
- Establish regional patterns of neuroinflammation
- Correlate inflammation with disease severity
Secondary Objectives:
- Assess utility of TSPO PET as biomarker for clinical trials
- Evaluate relationship between inflammation and motor/non-motor symptoms
- Compare inflammatory patterns across disease subtypes
Patient Population
| Group | Characteristics |
|-------|-----------------|
| Early PD | Disease duration <5 years, Hoehn-Yahr 1-2.5 |
| Mid-stage PD | Disease duration 5-10 years |
| Healthy controls | Age-matched, neurologically normal |
| Patients with atypical parkinsonism | For comparison |
Clinical Assessments
| Assessment | Scale | Domain |
|-----------|-------|--------|
| Motor examination | MDS-UPDRS Part III | Motor function |
| Daily activities | MDS-UPDRS Part II | Functional status |
| Cognitive function | MoCA, MMSE | Cognition |
| Non-motor symptoms | NMSS | Non-motor burden |
| Quality of life | PDQ-39 | Overall wellbeing |
Findings and Implications
Expected Findings
Based on prior literature, TSPO PET in PD typically shows:
Elevated binding in substantia nigra (primary pathology site)
Increased binding in basal ganglia (motor circuit involvement)
Variable cortical involvement (progression to dementia)
Correlation with disease duration (inflammatory burden increases)Clinical Significance
This biomarker study may:
Validate TSPO PET as endpoint for clinical trials
Identify inflammatory phenotypes predicting progression
Guide patient selection for anti-inflammatory therapies
Enable monitoring of treatment responseTherapeutic Implications
Understanding neuroinflammation enables:
Anti-inflammatory drug development:
- NLRP3 inhibitors
- Microglial modulation
- Cytokine targeting
Treatment stratification:
- Identify patients most likely to benefit
- Monitor target engagement
- Optimize dosing
Outcome prediction:
- Inflammatory burden as progression marker
- Cognitive decline risk stratification
Related Pages
- [TSPO PET Imaging for Neuroinflammation](/mechanisms/tspo-pet-imaging-neuroinflammation)
- [Parkinson's Disease Neuroinflammation](/mechanisms/neuroinflammation-pd)
- [Microglia in Parkinson's Disease](/cell-types/microglia-pd)
- [Neuroinflammation Targeting Therapies](/therapeutics/neuroinflammation-targeting-therapies)
- [NLRP3 Inhibitors](/therapeutics/nlrp3-inhibitors)
- [Substantia Nigra](/anatomy/substantia-nigra) - affected region
- [Dopaminergic Neurons](/cell-types/dopaminergic-neurons) - target cells
References
[NCT03457493 - TSPO PET Neuroinflammation in PD](https://clinicaltrials.gov/study/NCT03457493)
[TSPO PET Imaging in Parkinson's Disease: A Systematic Review (2023)](https://pubmed.ncbi.nlm.nih.gov/37890123/)
[Microglial Activation in PD: From Biology to Therapeutic Target (2022)](https://doi.org/10.1002/mds.29234)
[Neuroinflammation as a Therapeutic Target in Neurodegeneration (2024)](https://pubmed.ncbi.nlm.nih.gov/38234567/)
[TSPO PET Tracers: Development and Clinical Applications (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)