FD03-FGF21

Metabolic dysfunction-associated fatty liver disease (MAFLD), driven by dyslipidemia and hepatic lipid deposition, has become a major public health concern. Angiopoietin-like protein 3 (ANGPTL3), a lipoprotein lipase (LPL) activity inhibitor, can inhibit triglycerides (TGs) decomposition, and fibroblast growth factor 21 (FGF21) enhances fatty acids' β-oxidation in liver. We constructed a novel fusion protein combining the anti-ANGPTL3 nanobody FD03 and FGF21 (FD03-FGF21), which exerted appropriate binding affinities to ANGPTL3 and β-Klotho respectively. Our results showed FD03-FGF21 restored bioactivity of LPL which inhibited by ANGPTL3 and activated downstream pathway of FGF21 in iLite FGF21 assay-ready cells. Next, FD03-FGF21 showed a significant therapeutic effect in MAFLD mice, including attenuation of metabolic dyslipidemia, hepatic lipid accumulation, and impaired glucose tolerance. Compared to other treatments, FD03-FGF21 achieved the most significant therapeutic effect with a 79.78 % attenuation of low-density lipoprotein cholesterol (LDL-C) and a 95.8 % reduction of hepatic lipid accumulation. Mechanistically, transcriptomic analysis revealed that differential expression genes (DEGs) were principally clustered into lipid metabolism and oxidative stress pathways after the fusion protein treatment, especially the key lipid metabolism genes of LDLR and CD36 were significantly upregulated and downregulated respectively, as confirmed by WB. Furthermore, lipidomic and metabolomic analysis indicated the fusion protein ameliorated disorders in lipid and protein metabolism mainly through the downregulation of DG and upregulation of PC. Hepatic oxidative stress and inflammation were significantly reduced after administration of the fusion protein in MAFLD mice. Collectively, FD03-FGF21 represents an effective therapeutic strategy for MAFLD therapy through ameliorating lipid metabolism and oxidative stress.