Abstract:Objective To investigate the diagnostic value of serum Toll-like receptor 9（TLR9）and uncoupling protein 2（UCP2）for sepsis patients complicated with acute kidney injury（AKI），and to provide a reference for clinical diagnosis and treatment. Methods From October 2022 to September 2024，193 sepsis patients admitted to the Intensive Care Unit（ICU）of Sir Run Run Hospital，Nanjing Medical University，were regarded as the sepsis group，and 215 healthy volunteers who underwent physical checkups during the same period were included as the control group. According to whether the patients complicated with AKI，the sepsis patients were assigned into non-AKI group（n=125）and AKI group（n=68）. According to the severity of AKI，the AKI patients were assigned into mild group（n=34），moderate group（n=23），and severe group（n=11）. Enzyme-linked immunosorbent assay（ELISA）was used to detect serum levels of procalcitonin（PCT），tumor necrosis factor-α（TNF-α），interleukin-1β（IL-1β），TLR9，andUCP2. Fully automated biochemical analyzer was used to detect serum levels of creatinine（Scr），blood urea nitrogen（BUN），cystatin C（CysC），C-reactive protein（CRP），and the fully automated chemiluminescence immunoassay analyzer was used to detect interleukin-6（IL-6）. The Sequential Organ Failure Assessment（SOFA）score was performed to evaluate the degree of organ dysfunction in patients，while the Acute Physiology and Chronic Health Evaluation Ⅱ（APACHE Ⅱ）score was performed to evaluate the severity of the patient??s condition. Receiver operating characteristic（ROC）curve was used to analyze the diagnostic value of TLR9 and UCP2 for AKI in sepsis patients.Results Compared with the control group，the levels of TLR9［（1.98±0.62）pg/mL vs（1.45±0.34）pg/mL，t=10.849，P<0.05］and UCP2［（104.72±28.45）pg/mL vs（75.68±21.67）pg/mL，t=11.665，P<0.05］were higher in the sepsis group. The SOFA score，APACHE Ⅱ score，renal function indicators（Scr，BUN，CysC），inflammatory factors（CRP，PCT，TNF-α，IL-6，IL-1β），TLR9 and UCP2 levels in the AKI group were higher than those in the non-AKI group（P<0.05）. The levels of TLR9 and UCP2 gradually increased with the aggravation of AKI（P<0.05）. The AUC of TLR9 combined UCP2 in the diagnosis of AKI in sepsis patients was 0.917，which was superior to their individual diagnoses（0.806，0.814）（P<0.05）. Conclusion The levels of serum TLR9 and UCP2 are higher in sepsis patients and increase with the severity of AKI. The combined diagnosis of the two is valuable for sepsis complicated with AKI.