Michael VanElzakker

[Hutan]

To save others googling -
[11C]PBR28 is a TSPO radiotracer
TSPO is translocator protein, a marker of activated glial cells expressed on mitochondrial membranes
TSPO is a commonly used marker used to investigate neuroinflammation

Elevated levels have been associated with migraine, and with poor short-term memory performance in set of twins discordant for memory performance, and with post-stroke patients and multiple sclerosis. There looks to be a flurry of studies using this technique.

It's not without its difficulties though:

Although TSPO imaging demonstrates great promise, its signal exhibits substantial interindividual variability, which needs to be accounted for to uncover group effects that are truly reflective of neuroimmune activation.

 

[SNT Gatchaman]

Expanding on @Hutan's comments on the difficulties with TPSO — from Integrated MRI and [11C]-PBR28 PET Imaging in Amyotrophic Lateral sclerosis

[11C]-PBR28 is a positron emission tomography (PET) radiotracer that binds to a 18pkD translocator protein (TSPO), which is expressed in activated microglia, reactive astrocytes, vascular endothelium, and to a much lower degree in neurons.

There's probably a baseline expression of TSPO also, e.g. in vascular endothelium, but this sounds to be sparse. See Cellular Sources and Regional Variations in the Expression of the Neuroinflammatory Marker Translocator Protein (TSPO) in the Normal Brain.

An endothelitis or BBB disruption might also contribute to increased avidity. See Impact of Endothelial 18-kDa Translocator Protein on the Quantification of 18F-DPA-714 (which is discussing a different tracer).

See also [1] and [2] for more papers on TPSO.

 

[SNT Gatchaman]

Related to the imaging of neuroinflammation that might overcome some of the limitations of PET-CT with TPSO —
Mapping microglia and astrocyte activation in vivo using diffusion MRI, 2022

 

[Mij]

The study is enrolling people with ME/CFS, LC and chronic Lyme as well as healthy controls.

Enrollment for this study is expected to close on Tuesday, April 1, 2025

What we are studying

Why do some people recover from viruses and others don't? What happens biologically that make viral illnesses turn into chronic illnesses in some people but not in others? To find out, we hope to compare brains of those with ME/CFS to brains of healthy controls. Specifically, we are looking for the presence or absence of neuroinflammation (an immune response in the brain) which we will measure using a PET/MRI scan.

Our lab is trying to uncover the biological mechanisms behind post-viral chronic illnesses like ME/CFS and we need your help to do so!
LINK