The imbalance of liver resident macrophages polarization promotes chronic autoimmune hepatitis development in mice

BACKGROUND: Autoimmune hepatitis (AIH) is a chronic immune-mediated inflammatory liver disease. At present, it is largely unknown how the innate immune cells influence AIH development. OBJECTIVE: To inquiry about mechanism of liver resident macrophages in AIH development, thus offering a new direction for AIH targeted treatment. METHODS: The liver resident macrophages were eliminated by clodronate liposomes in AIH liver tissues, followed by HE and Picrosirius assay to detect liver fibrosis and lymphocyte infiltration. The liver resident macrophages polarization was detected by Immunohistochemistry and qPCR. The collagenase digestion was used to isolate Kupffer cells from AIH mice liver tissues and pro-/anti-inflammatory cytokines were determined by qPCR. RESULTS: M2 macrophages were the dominant phenotype at early immune response stage and hepatic inflammation was progressively aggravated after depletion of liver resident macrophages. M2 macrophages could effectively delay the development of AIH and could be polarized to M1 macrophages at the disease progresses. TLR2 ligands could promote M2 macrophages producing anti-inflammatory cytokines, whereas TLR4 ligands could promote M1 macrophages producing proinflammatory cytokines. The change of TLR2 and TLR4 ligands could lead to continuous high expression of TLR4 and decreased expression of TLR2 in macrophages to further affect liver resident macrophages polarization state. CONCLUSION: TLR2 and TLR4 ligands mediated liver resident macrophages polarization to favor chronic autoimmune hepatitis development.