Immunomodulatory effects of tacrolimus-loaded lipid-core nanocapsules in autoimmune hepatitis

Liver damage in autoimmune hepatitis (AIH) is perpetrated by T-effector lymphocytes that are not adequately restrained by regulatory T cells (Tregs). The goal of AIH treatment is to control inflammation and induce disease remission through administration of immunosuppressive drugs including corticosteroids, azathioprine, and, in difficult-to-treat cases, mycophenolate mofetil or tacrolimus (TAC). Despite TAC being a potent immunosuppressant, its use has been hampered by a narrow therapeutic window and systemic toxicity. In this study, we have tested the effects of lipid-core nanoformulations encapsulating TAC (NC-TAC) as a novel drug delivery system that would enable potentially favorable immunomodulatory effects compared with unencapsulated TAC. NC-TAC properties were assessed in vitro, in CD4 T cells and Tregs isolated from the peripheral blood of AIH patients and controls; and in vivo through a model of T cell-mediated liver injury induced by Concanavalin-A (Con-A) in NOD/scid/gamma mice, pre-emptively reconstituted with human CD4 T lymphocytes. Compared to unencapsulated TAC, NC-TAC favored a regulatory phenotype in CD4 T cells of AIH patients, enhanced the suppressive function and preserved AIH Treg phenotype in the presence of an inflammatory stimulus. Systemic administration of NC-TAC ameliorated liver injury in vivo, as indicated by decreased ALT levels, reduced lymphocyte infiltration on histology, and an increased frequency of intrahepatic CD4⁺FOXP3⁺ lymphocytes. NC-TAC could therefore be considered as a novel drug delivery system to be possibly explored for the treatment of AIH, having a beneficial immunomodulatory profile and effectively favoring Treg immune responses.