Non-alcoholic fatty liver disease: Immunological mechanisms and current treatments

Figure 3 Overview of innate and adaptive immune cells involved in non-alcoholic fatty liver disease (NAFLD). Activation of immune cells can promote inflammation and liver injury in NAFLD. The innate immune system cells include Kupffer cells, monocytes, and macrophages as well as hepatic dendritic cells, neutrophils and natural killer cells. Natural killer T cells provide a bridge between both the innate and adaptive immune system. The adaptive immune system includes T cells such as CD8 T cells and CD4 T cells (Th1, Th17 and regulatory T cells). The adaptive immune system also comprises of B1 and B2 cells as well as platelets. Although the contribution of immune cells to the development of NAFLD has been explored, the crosstalk between the distinctive immune cell subsets in the pathogenesis of NAFLD requires further investigation (created with BioRender.com). KC: Kupffer cells; TNF-α: Tumour necrosis factor-alpha; IFN-γ: Interferon-γ; IL: Interleukin; ROS: Reactive oxygen species; NO: Nitric oxide; NETs: Neutrophil extracellular traps; NF-κB: Nuclear factor-kappa B; HDC: Hepatic dendritic cells; MPO: Myeloperoxidase; HSC: Hepatic stellate cells ; CXCL: C-X-C motif chemokine ligand; BAFF: B cell activating factor; TGF-β: Transforming growth factor-β; NK: Natural killer; NKT: Natural killer T cells; Treg: Regulatory T cells.