The Pnpla3 ASO treatment reduced liver steatosis, lipogenesis, and monounsaturated fatty acids in lipid droplets in Pnpla3 mutant knock-in mice and wild-type littermates fed a NASH-inducing diet. Homozygous Pnpla3 mutant knock-in and littermate wild-type mice were fed a NASH-inducing diet for 26 weeks. After 12 weeks of feeding on the NASH diet, Pnpla3 mutant knock-in and wild-type mice were treated with either control or Pnpla3 ASOs (5 mg/kg/week administered by two subcutaneous injections per week, n = 8–9 mice/group) for 14 weeks. (A) Representative images of Oil Red O-stained liver sections (black scale bar represents 100 μm). Liver mRNA expression levels of Acc1 and Scd1 in Pnpla3 mutant knock-in (B) and wild-type (C) mice. Liver lipid droplet fatty acid composition in Pnpla3 mutant knock-in (D) and wild-type (E) mice. Values are presented as the mean ± SEM. P values were calculated using 2-sided t-tests. Abbreviations: Acc1: acetyl-CoA carboxylase 1; ASO: antisense oligonucleotide; Ctrl: control; MUFA: monounsaturated fatty acid; Pnpla3: patatin-like phospholipase domain-containing 3; PUFA: polyunsaturated fatty acid; Rplp0: ribosomal protein large P0; Scd1: stearoyl-CoA desaturase 1; SFA: saturated fatty acid. Mutant knock-in mice are defined as homozygotes for a methionine (M) at position 148 of the Pnpla3 protein, while wild-type littermates are homozygotes for an isoleucine (I) at the same position. WT: wild-type; MUT: mutant.