Lactoferrin alleviates non-alcoholic steatohepatitis via remodeling gut microbiota to regulate serotonin-related pathways.

INTRODUCTION: Lactoferrin (LF), a multifunctional glycoprotein, has been implicated in the regulation of glucose and lipid metabolism.OBJECTIVES AND METHODS: This study employed in vivo and in vitro models to investigate the direct effects of LF on non-alcoholic steatohepatitis (NASH) and to elucidate its underlying mechanisms.RESULTS: LF intervention alleviated hepatic lipid metabolic disorders and liver injury in high-fat, high-cholesterol cholate-containing diet (HFCCD)-fed mice by mitigating oxidative stress, suppressing the inflammatory cGAS/STING pathway, and reducing M1 proinflammatory macrophage polarization. These effects were validated in free fatty acid (FFA)-treated HepG2 cells and AML12 cells. Furthermore, LF ameliorated HFCCD-induced gut microbiota dysbiosis and increased short-chain fatty acid levels. The critical role of gut microbiota in mediating the hepatoprotective effects of LF was confirmed through antibiotic-induced microbiome depletion and fecal microbiota transplantation. Mechanistically, LF modulated gut-liver serotonin signaling and promoted fatty acid β-oxidation through the HTR2A-PPARα-CPT-1A pathway, an effect abolished by the HTR2A agonist DOI. In a co-culture system, LF treatment of the Caco-2/HT29 monolayer alleviated lipid accumulation and regulated the HTR2A-PPARα-CPT-1A pathway in FFA-treated HepG2 cells.CONCLUSIONS: These findings indicate that LF attenuates NASH by remodeling gut microbiota to modulate microbiota-derived serotonin signaling and enhance fatty acid oxidation.