{
  "abstract": "Background Disruption of hepatic lipid metabolism is a hallmark of metabolic dysfunction-associated steatotic liver disease (MASLD), yet the regulatory mechanisms governing triglyceride accumulation remain poorly understood. This study investigates the clinical relevance and therapeutic potential of the conditionally essential amino acid L-proline in MASLD.Methods Serum proline levels were measured in two independent MASLD patient cohorts and in high-fat diet (HFD)-fed mice. The therapeutic efficacy of proline supplementation was evaluated in methionine-choline-deficient (MCD) and choline-deficient high-fat diet (CDHFD) mouse models of MASLD. Hepatic spatial metabolomics and transcriptome sequencing were performed to identify metabolic and transcriptional alterations. In vitro, the effects of proline on lipid accumulation were assessed in oleic acid/palmitate-treated hepatocytes using BODIPY staining, Oil Red O staining, triglyceride assays, and fatty acid uptake assays. The functional involvement of the PPARγ-CD36 axis was investigated using genetic modulation (knockdown/overexpression). Molecular interactions were explored through protein stability and binding assays.Results Serum proline levels were significantly decreased in MASLD patients across two independent cohorts, a finding recapitulated in HFD-fed mice, establishing a clinical association between proline deficiency and disease state. Hepatic spatial metabolomics confirmed an altered proline distribution in steatotic livers. Functionally, proline administration robustly attenuated hepatic steatosis in both MCD and CDHFD dietary models. Notably, this protective effect was lipid species-specific, marked by a significant reduction in hepatic triglycerides without parallel changes in cholesterol. Consistently, in cultured hepatocytes, proline supplementation mitigated oleic acid/palmitate-induced lipid accumulation and reduced fatty acid uptake. Transcriptome sequencing revealed that proline treatment significantly downregulated the PPAR signaling pathway, with the fatty acid translocase CD36 emerging as the most prominently altered target gene. Functional studies confirmed the centrality of this axis, as CD36 knockdown phenocopied, while its overexpression partially abrogated, the effects of proline. Mechanistically, further biophysical assays suggested a potential direct interaction between proline and the CD36 protein, which may underlie its regulatory function.Conclusions Proline alleviates hepatic steatosis by transcriptionally inhibiting the PPARγ-CD36 axis, leading to reduced triglyceride accumulation in hepatocytes. Its lipid-specific effects highlight a targeted role in modulating hepatic lipid metabolism. These findings establish a strong foundation for considering proline supplementation as a nutritional intervention strategy for MASLD.",
  "authors": [
    {
      "affiliations": [
        "NHC Key Laboratory of Molecular Probes and Targeted Diagnosis and Therapy, The Fourth Hospital of Harbin Medical University, Harbin, China"
      ],
      "name": "Yidi Wu"
    },
    {
      "affiliations": [
        "Heilongjiang Provincial Key Laboratory of Panvascular Disease, Harbin Medical University, China"
      ],
      "name": "Dabin Liu"
    }
  ],
  "title": "IDDF2026-ABS-0125 L-proline alleviates metabolic dysfunction-associated steatotic liver disease by modulating hepatic triglyceride accumulation",
  "uid": "104fd714-17b7-5e39-8cbb-5ce60fb8b2a0"
}