HSK31679 alleviates MASLD by suppressing monoglucosylation of gut microbial sphingolipids

Background: As the first approved medication for metabolic dysfunction-associated steatohepatitis (MASH), thyroid hormone receptor β (THR-β) agonist MGL-3196 (Resmetirom) has been highly spotlighted as the liver-directed, bioactive oral drug. However, it was also identified with remarkable heterogeneity of individual clinical efficacy and its interference with gut microbiota in host hepatoenteral circulation was still undocumented. Methods: We compared MASH attenuation by MGL-3196 and its derivative drug HSK31679 in germ-free (GF) and specific-pathogen free (SPF) mice to evaluate the role of gut microbiota. Then deep cross-omics analyses of microbial metagenome, metabolome and single-cell RNA-sequencing were clinically applied into the randomized, double-blind, placebo-controlled multiple-ascending-dose (MAD) cohort of HSK31679 treatment (n = 50), to comprehensively investigate the altered gut microbiota metabolism and circulating immune signatures. Results: HSK31679 outperformed MGL-3196 in ameliorating MASH diet-induced steatohepatitis of SPF mice but not GF mice. In the MAD cohort of HSK31679, relative abundance of B. thetaiotaomicron was significantly enriched to impair glucosylceramide synthase (GCS)-catalyzed monoglucosylation of microbial Cer(d18:1/16:0) and Cer(d18:1/24:1). In stark contrast to the non-inferiority MASH resolution between MGL-3196 and HSK31679 for GFBT△GCS mice, HSK31679 manifested superior steatohepatitis alleviation than MGL-3196 for GFBTWT mice, which may attribute to its steric hindrance with R123 and Y401 of gut microbial GCS. In stool samples with high GCS activity, the administration of 160 mg HSK31679 has induced a shift in peripheral compartments towards an immunosuppressive niche, characterized by the down-regulation of CD8α+ dendritic cells and MINCLE+ macrophages. Conclusions: This study has provided novel insights into the indispensable gut microbiota for HSK31679 treatment, which revealed microbial GCS may serve as its prognostic biomarker of MASH treatment, as well as the new target for further strategies of microbiota-based MASH therapeutics.