NK cells were impaired in experimental NASH, while natural killer T cells (unique immune cell subtype that expresses NK cells surface markers as well as T-cell antigen receptor) are depleted in steatosis but increased later during disease progression likely leading to inflammation and fibrosis in NASH via the production of IL-4, osteopontin, and IFN-γ (Tajiri and Shimizu, 2012; Tian et al., 2013). This evidence concerns the gene SPP1 and metabolic dysfunction-associated steatohepatitis.