Macrophage activation in the prevention or regression of atherosclerosis

Characterization of the interactions of rabbit neonatal Fc receptor (FcRn) with rabbit and human IgG isotypes

Despite the increasing importance of rabbit as an animal model in pharmacological studies like investigating placental transfer of therapeutic IgGs, little is known about the molecular interaction of the rabbit neonatal Fc receptor (FcRn) with rabbit and human IgG molecules. We analyzed the interactions of the rabbit and human FcRn with rabbit and human IgG isotypes using surface plasmon resonance assay. Similar to FcRn of other species, rabbit FcRn functions in pH-dependent manner, as it binds IgGs at pH 6.0, but no binding occurs at pH 7.4. We also showed that rabbit FcRn binds rabbit IgG and human IgG1 with nearly identical affinity, whereas it has stronger interactions with the other human IgG isotypes. The similar affinity of rabbit IgG and human IgG1 for rabbit FcRn was confirmed by in vitro FcRn-mediated recycling assay. These data verify that rabbit is an appropriate animal model for analyzing the pharmacokinetics of human therapeutic monoclonal antibodies.

Effect of monocytopenia on trauma-induced atherosclerotic lesions in the rabbit ear artery

In a trauma model of atherosclerosis (repeated mechanical injury of the rabbit ear artery), rabbits were pretreated either with etoposid (inducing a monocytopenia) or with prednisolone (inhibiting monocyte function) to investigate the role of monocytes in traumatically induced plaque formation. Three weeks after the last injury the arteries were carefully examined. While a profound monocytopenia during the period of injuries did not at all influence the size of the plaque formation, this was almost completely inhibited in the prednisolone-treated rabbits. Obviously, the effect of prednisolone must be attributed to other pharmacological properties. Monocytes appear to be of less importance in purely trauma atherosclerosis models.