In vivo imaging of the effect of LPS on arterial endothelial cells: molecular imaging of heat shock protein 60 expression.

Bacterial endotoxins are known as stress factors for endothelial cells. In 20 normocholesterolemic New Zealand White (NZW) rabbits, endothelial stress was induced by intravenous (i.v.) injection of lipopolysaccharide (LPS), while eight NZW rabbits were sham-treated or served as untreated controls. In vivo molecular imaging was performed using co-registered computer tomography and positron emission tomography 24 h after i.v. injection of (124)I-labeled monoclonal anti-HSP60 or (124)I-radiolabelled isotype control antibodies. Compared to control animals, in vivo images of rabbit aortae revealed significantly increased endothelial binding of (124)I-labeled anti-HSP60 antibodies upon LPS, especially at sites of aortal branching. This was confirmed by immunohistochemistry and autoradiography data. Our results showed, as proof-of-principle, that HSP60-expression in normocholesterolemic rabbits is significantly increased after induction of endothelial stress and that non-invasive in vivo molecular imaging of early aortal HSP60-expression using (124)I-labeled anti-HSP60 monoclonal antibodies is possible.