MicroRNA-26b protects against MASH development in mice and can be efficiently targeted with lipid nanoparticles

The prevalence of metabolic dysfunction-associated steatohepatitis (MASH) is increasing, urging more research into the underlying mechanisms. MicroRNA-26b (Mir26b) might play a role in several MASH-related pathways. Therefore, we aimed to determine the role of Mir26b in MASH and its therapeutic potential using Mir26b mimic-loaded lipid nanoparticles (LNPs). Apoe^-/-Mir26b^-/-, Apoe^-/-Lyz2^creMir26b^fl/fl mice, and respective controls were fed a Western-type diet to induce MASH. Plasma and liver samples were characterized regarding lipid metabolism, hepatic inflammation, and fibrosis. Additionally, Mir26b mimic-loaded LNPs were injected in Apoe^-/-Mir26b^-/- mice to rescue the phenotype and key results were validated in human precision-cut liver slices. Finally, kinase profiling was used to elucidate underlying mechanisms. Apoe^-/-Mir26b^-/- mice showed increased hepatic lipid levels, coinciding with increased expression of scavenger receptor a and platelet glycoprotein 4. Similar effects were found in mice lacking myeloid-specific Mir26b. Additionally, hepatic TNF and IL-6 levels and amount of infiltrated macrophages were increased in Apoe^-/-Mir26b^-/- mice. Moreover, Tgfb expression was increased by the Mir26b deficiency, leading to more hepatic fibrosis. A murine treatment model with Mir26b mimic-loaded LNPs reduced hepatic lipids, rescuing the observed phenotype. Kinase profiling identified increased inflammatory signaling upon Mir26b deficiency, which was rescued by LNP treatment. Finally, Mir26b mimic-loaded LNPs also reduced inflammation in human precision-cut liver slices. Overall, our study demonstrates that the detrimental effects of Mir26b deficiency in MASH can be rescued by LNP treatment. This novel discovery leads to more insight into MASH development, opening doors to potential new treatment options using LNP technology.