ABSTRACT Background: The Peripheral Benzodiazepine Receptor (PBR) can be classified as a distinct receptor from the central benzodiazepine receptor. The PBR gene has been located to chromosome 22q13.31 in humans and has been found to consist of four exons, with the first and half of the fourth exon being untranslated to form the PBR protein. PBR is involved in numerous biological conditions including the regulation of cellular proliferation and apoptosis, steroidogenesis, heme biosynthesis, anion and porphyrin transport and mitochondrial functions such as oxidative phosphorylation and translocation of cholesterol from the outer to the inner mitochondrial membrane. Recent studies showed that the expression of PBR correlated with tumour malignancy and patient survival. Aim: The objectives of this research were to determine the expression pattern and level of PBR mRNA in various types of human normal and cancer tissues and to isolate the PBR protein.

Yes / Non-invasive imaging methods are required to monitor the inflammatory content of atherosclerotic plaques. FEDAA1106 (N-(5-fluoro-2-phenoxyphenyl)-N-(2-(2-fluoroethoxy)-5- methoxybenzyl) acetamide) is a selective ligand for TSPO-18kDa (also known as peripheral benzodiazepine receptor), which is expressed by activated macrophages. We compared 18F- FEDAA1106 and 18F-FDG (a marker of glucose metabolism) for PET imaging of vascular inflammation. This was tested using a murine model where focal inflammation was induced in the carotid artery via placement of a constrictive cuff. Immunostaining revealed CD68-positive cells (macrophages) at a disturbed flow site located downstream from the cuff. Dynamic PET imaging using 18F-FEDAA1106 or 18F-FDG was registered to anatomical data generated by CT/CT angiography. Standardized uptake values (SUV) were significantly increased at cuffed compared to contralateral arteries using either 18F-FEDAA1106 (p<0.01) or FDG (p<0.05). However, the 18F-FEDAA1106 signal was significantly higher at the inflamed disturbed flow region compared to the non-inflamed uniform flow regions, whereas differences in FDG uptake were less distinct. We conclude that 18F-FEDAA1106 can be used in vivo for detection of vascular inflammation. Moreover, the signal pattern of 18F-FEDAA1106 correlated with vascular inflammation more specifically than FDG uptake. / : This study was funded by the British Heart Foundation and through a grant from the Swiss National Science Foundation (310030_143343/1 to B.R.K.)