Fig. 3
Integrin expression in non-arthritic joints. a MOVAT pentachrome staining of the right knee of a CIA mouse from week 2. The immunohistochemistry staining of consecutive slices for integrin α5 (b) and β3 (c), (depicted area corresponds to the inset frame in a). The same mouse was subjected to PET imaging of α5β1-integrin using 68Ga-Aquibeprin (d) and of αvβ3-integrin using 68Ga-Avebetrin (e), wherein the white arrow indicates the knee subjected to staining (a, b, c). No significant α5 expression was found (b), confirming the absence of α5β1. Focal expression of β3 (c, green arrows) originates from the expression of the platelet integrin αIIbβ3 by megakaryocytes (platelet progenitor cells); no significant β3 expression elsewhere confirms the absence of αvβ3. Consistently, both tracers show a low uptake in a non-arthritic knee. Color coding of μPET images (d, e) is similar to Fig. 2