Fumonisin B1-induced localized activation of cytokine network in mouse liver

Fumonisin B1 (FB1), a mycotoxin produced primarily by Fusarium veticillioides and related fungi, is a carcinogen and causative agent of various animal diseases. Our previous studies indicated the involvement of tumor necrosis factor-α (TNFα) in FB1-induced hepatotoxicity. Male B6,129 mice (five/group) were injected subcutaneously with vehicle or 2.25 mg/kg/day of FB1 for 5 days and sampled 1 day after the last treatment. FB1 treatment caused an increased expression of TNFα, interferon γ (IFNγ) and interleukin (IL)-12 p40 in liver without any changes in kidney or spleen, suggesting the localized site of their production. IL-1β cytokine expression was increased in liver and kidney after FB1 exposure. Cells involved in TNFα production after FB1 treatment in liver were identified as Kupffer cells. FB1 increased alanine aminotransferase in plasma and increased apoptotic cells in liver. Selective increase in proinflammatory T helper (Th)1-cytokines (IL-12 and IFNγ) and TNFα with no alteration in Th2-cytokines (IL-4, IL-6 and IL-10) suggest the involvement of IL-12, produced by Kupffer cells, in induction of IFNγ production by natural killer (NK) cells and/or NK1+ T cells, which can undergo a positive amplification loop with TNFα produced by macrophages or other hepatic cells to elicit the toxic reaction.