Abstract:Objective To analyze the expression changes of peripheral blood Toll-like receptor 4（TLR4），nuclear factor-κB（NF-κB），NOD-like receptor thermal protein domain associated protein 3（NLRP3）mRNA in patients with severe acute pancreatitis（SAP）at different clinical disease stages ，and to explore their predictive value for in-hospital death risk in SAP patients. Methods A prospective cohort study was conducted. A total of 100 SAP patients admitted to the Department of Critical Care Medicine，Affiliated Hospital of Inner Mongolia Medical University from January 2024 to January 2025 were enrolled. They were divided according to clinical stages into the acute response phase（n=50），systemic infection phase（n=30），and residual infection phase（n=20）. Based on in-hospital prognosis，patients were categorized into an in-hospital death group（n=24）and an in-hospital survival group（n=76）. The mRNA expression levels of TLR4，NF-κB，and NLRP3 were compared among different groups. Multivariate logistic regression was used to assess the correlation of these indicators with in - hospital death，and receiver operating characteristic（ROC）curves were used to evaluate their predictive efficacy for in-hospital death. Results The expression levels of peripheral blood TLR4，NF-κB，and NLRP3 mRNA were significantly different among SAP patients at different disease stages（P＜0.01）. Levels in the systemic infection phase were significantly higher than those in the acute response and residual infection phases（P＜0.05）. Multivariate logistic regression showed that high Acute Physiology and Chronic Health Evaluation Ⅱ (APACHEⅡ) score within 24 h，high Sequential Organ Failure Assessment (SOFA) score within 24 h，systemic infection phase，low serum calcium level，high CRP level，and high expression of TLR4 mRNA（OR =1.893，95%CI：1.365-2.637)，NF-κB mRNA（OR =1.278，95%CI：1.046-1.560），and NLRP3 mRNA（OR =1.962，95%CI：1.379-2.791）were independent risk factors for in-hospital death（P＜0.05）. ROC curve analysis showed that the areas under the curve（AUCs）for predicting in-hospital death risk in SAP patients based on peripheral blood TLR4，NF-κB，and NLRP3 mRNA expression levels were 0.736，0.708，and 0.782，respectively. The AUC for combined detection of the three indicators was 0.892，which was significantly higher than that of any single indicator（P＜0.05）. Conclusion The expression levels of TLR4，NF-κB，and NLRP3 mRNA in peripheral blood significantly differ across disease stages in SAP patients，and the expression levels are significantly elevated in patients in the systemic infection phase. This elevated expression is closely associated with an increased risk of in-hospital death. Combined detection of these three markers demonstrates higher predictive efficacy for death risk compared to any single indicator.