Objective：To investigate the role of Tyro3 protein tyrosine kinase（Tyro3）in the pathogenesis of endotoxemia and its underlying molecular mechanisms. Methods：The expression profile of Tyro3 in peripheral blood from septic patients was analyzed using the GEO database（GSE54514）. An endotoxemia mouse model was established by intraperitoneal injection of lipopolysaccharide （LPS，10 mg/kg）. Disease severity -including clinical scores，96-hour survival rates，plasma inflammatory cytokine levels，and acute hepatic inflammatory pathology -was evaluated and compared between systemic Tyro3 knockout（Tyro3-/-）and wild -type（Tyro3 +/+） mice. Additionally，bone marrow-derived macrophages（BMDMs）were isolated from Tyro3+/+ and Tyro3-/- mice and stimulated with LPS （100 ng/mL）to establish an in vitro acute inflammation model. Activation of the nuclear factor kappa -B（NF-κB）signaling pathway was assessed. Results：Clinical data analysis revealed a significant downregulation of Tyro3 expression in the peripheral blood of septic patients. In vivo experiments demonstrated that Tyro3-/- mice exhibited exacerbated endotoxemia compared to Tyro3 +/+ mice，as evidenced by significantly worsened clinical scores，reduced survival rates，elevated plasma inflammatory cytokine levels，more severe acute liver injury，and increased inflammatory cell infiltration. In vitro studies showed that Tyro3 deficiency led to hyperactivation of the NF-κB pathway in macrophages，characterized by enhanced phosphorylation of inhibitor of kappa B kinase（IKK）and the p65 subunit of NF-κB，along with accelerated degradation of NF-kappa-B inhibitor alpha（IB-α）. Pharmacological activation of Tyro3 using protein S（Pros1）effectively suppresses NF - κB pathway activation. Conclusion：Tyro3 attenuates endotoxemia - induced inflammatory responses and hepatic injury by negatively regulating the NF - κB signaling pathway in macrophages，suggesting that pharmacological targeting of the Tyro3-NF-κB axis may represent a novel therapeutic strategy for endotoxemia management