TSPO PET Imaging: From Microglial Activation to Peripheral Sterile Inflammatory Diseases?
Table 3
Applications
Population/animal models
Radioligand
Main findings
Ref.
Preclinical
Unilateral instillation of fibrogenic (microcrystalline SiO2, rabbits), nonfibrogenic (amorphous SiO2, rabbits) 5 μm particles into rabbit lungs
11C-PK11195
Significantly increased tracer tissue/plasma ratios from day 3 after instillation in the challenged region, in both silica models, and remaining at least 2 weeks In the amorphous silica model, an extrapulmonary TSPO PET signal appeared at 6 days In the microcrystalline silica model, this extrapulmonary signal is delayed until 3 weeks after instillation
Mean tracer uptake was higher in 4/6 COPD patients and 3/6 asthmatics than the maximum value in HC No statistical correlation was found between binding tracer and either the magnitude of the 18F-FDG signal or the severity of the disease
15 FASSc (10 drug-naive & 5 with immunosuppressive drugs) patients versus 7 HC
11C-PK11195
Tracer lung uptake was decreased in FASSc patients, compared to normal controls Strong negative correlation between tissue radioligand uptake and lung density in FASSc patients Pulmonary tracer binding showed a nonsignificant but progressive decrease from normal in FASSc drug-naive patients to those patients immunosuppressive-treated No significant correlation between tracer uptake and pulmonary function data
