Anti-neutrophil cytoplasmic antibodies in a rat model of trinitrobenzenesulphonic acid-induced liver injury.

In sera from patients with autoimmune liver diseases, e. g. primary sclerosing cholangitis (PSC) and autoimmune hepatitis, anti-neutrophil cytoplasmic antibodies (ANCAs) can be found. Until now, no animal model of ANCA induction in liver disease has been described. In this study, we describe a novel rat model of acute liver injury and subsequent ANCA production. The hapten reagent 2,4,6-trinitrobenzenesulphonic acid (TNBS) was injected into the portal vein of female Lewis rats. Two experimental groups were studied: group A (TNBS/ethanol) received different TNBS concentrations; control animals of group B (ethanol) were injected with 10% (v/v) ethanol/0.9% (w/v) NaCl. A dose-dependent acute necrotizing liver injury occurred after injection of TNBS. Histopathological examination revealed acute hepatic injury with confluent parenchymal necrosis, mild bile duct proliferation and periportal infiltration. The periportal infiltration consisted mainly of macrophages and T lymphocytes. ANCAs were found in an allogenic test system between 1 and 8 weeks after TNBS injection in 11 out of 28 (39%) TNBS-treated rats (group A) and did not correlate with the extent of liver injury or TNBS dose. Autoantibody specificities of IgG type were directed against catalase (29%), myeloperoxidase (14%) and actin (7%), as detected by enzyme-linked immunosorbent assay and Western blotting. Moreover, autoantibodies against the asialoglycoprotein receptor were observed. Peripheral blood mononuclear cells and spleen lymphocytes from TNBS-treated rats were shown to produce ANCAs. In summary, we were able to show that intraportal administration of the hapten reagent TNBS induces an acute necrotizing liver injury with subsequent ANCA production in Lewis rats. ANCA specificities were mainly directed against catalase, an autoantigen that has recently been identified in sera from patients with primary sclerosing cholangitis and autoimmune hepatitis. This animal model offers the opportunity to study the pathomechanisms of ANCA production in necrotizing liver injury.