Recently mannan from Saccharomyces cerevisiae has been
shown to be able to induce psoriasis and psoriatic arthritis in mice, and the
phenotypes resemble the corresponding human diseases. To investigate the
pathological processes, we set out to label mannan with fluorine-18 (18F)
and study the 18F-labeled mannan in vitro and in vivo with positron emission
tomography (PET). Accordingly, mannan has been transformed into 18F-
fluoromannan with 18F-bicyclo[6.1.0]nonyne. In mouse aorta, the binding
of [18F]fluoromannan to the atherosclerotic lesions was clearly visualized
and was significantly higher compared to blocking assays (P < 0.001) or
healthy mouse aorta (P < 0.001). In healthy rats the [18F]fluoromannan
radioactivity accumulated largely in the macrophage-rich organs such as
liver, spleen, and bone marrow and the excess excreted in urine.
Furthermore, the corresponding 19F-labeled mannan has been used to
induce psoriasis and psoriatic arthritis in mice, which indicates that the biological function of mannan is preserved after the
chemical modifications.
KEYWORDS: Fluorine-18