Therapeutic advantage of anti-VAP-1 over anti-α4 integrin antibody in concanavalin a-induced hepatitis

Hepatitis induced by concanavalin A (Con A) in mice is well known to be a T-lymphocyte-mediated injury. It has been reported that T helper (Th)1 and Th2 lymphocytes use α4 integrin and vascular adhesion protein (VAP)−1, respectively, to adhere within the hepatic sinusoids. Therefore, we investigated whether inhibition of these molecules ameliorates or worsens the Con A-induced hepatic injury in vivo. Vehicle or antibody to α4 integrin or VAP-1 was intravenously administered 30 minutes before Con A administration. In control mice Con A markedly increased the serum alanine aminotransferase (ALT) level in a dose-dependent manner, and induced a massive infiltration of CD3, particularly interleukin (IL)−4 producing CD4 T cells and liver injury. Both parameters were reduced by anti-VAP-1 antibody despite antibody only blocking the adhesion, not the amine oxidase activity of VAP-1. Both activities of VAP-1 were eliminated in VAP-1-deficient mice and both Con A-induced liver injury and CD4 T-cell infiltration were eradicated. In contrast to anti-VAP-1, anti-α4 integrin antibody reduced interferon-gamma (IFN-γ)-producing CD3 T cells but this worsened Con A hepatitis, suggesting inhibition of a suppressor cell. Con A induced the recruitment of CD49d+ monocytic myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) into the liver. Anti-α4 integrin dramatically blocked the influx of MDSCs but not Tregs. Conclusion: Our findings show that VAP-1 and α4 integrin have opposing effects in Con A-induced hepatic injury, which is associated with blocking the recruitment of CD4 lymphocytes and monocytic MDSCs, respectively. Moreover, these data provide the rationale for a potential therapeutic approach to target adhesion molecules in autoimmune hepatitis. (Hepatology 2013;58:1413–1423)