Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2026 Apr;38(4):
353-361
OBJECTIVE: To investigate the protective effect of kynurenine 3-monooxygenase (KMO) inhibitor GSK180 against trauma-induced sepsis (TIS)-induced acute kidney injury (AKI) and to explore its underlying mechanism.
METHODS: Male SPF healthy Sprague-Dawley (SD) rats were randomly divided into groups using a random number table. (1) A normal control group, a sham-operated (Sham) group, and TIS groups at 12, 24, and 48 hours were established, and 6 surviving rats were finally retained in each group for statistical analysis. The normal control group received no treatment. The Sham group was subjected only to laparotomy exploration and gentle cecal palpation followed by abdominal closure, and 40 mL/kg normal saline was injected subcutaneously for fluid resuscitation after surgery until the rats recovered voluntary movement. TIS groups were treated with combined injury to establish the TIS-induced AKI model, and postoperative management was identical to that of the Sham group. Samples were collected at each time point to detect inflammatory indicators such as white blood cell count (WBC), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP), as well as serum creatinine (SCr) and blood urea nitrogen (BUN) to evaluate inflammatory response and renal injury. Based on the severity of renal injury, renal tissues of the corresponding groups were harvested for proteomic analysis to screen candidate target proteins for related mechanistic intervention experiments. (2) In the KMO inhibitor intervention experiment, rats were randomly divided into the Sham group, TIS group, and KMO inhibitor intervention group, with 6 surviving rats retained in each group for statistical analysis. Procedures in the Sham and TIS groups were the same as described above; the KMO inhibitor intervention group was intraperitoneally injected with the KMO inhibitor GSK180 (10 mg/kg) at 2 hours after model establishment, while the Sham and TIS groups were intraperitoneally injected with an equal volume of normal saline. The above inflammatory and renal function indicators were detected at 24 hours after surgery. Periodic acid-Schiff (PAS) staining was used to observe histopathological changes of renal tissues. Terminal-deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) staining was adopted to observe cell apoptosis in renal tissues. Mitochondrial ultrastructure changes were examined by transmission electron microscopy. Mitochondrial reactive oxygen species (ROS) and membrane potential were detected by flow cytometry. Western blotting was performed to determine the expression of KMO, mitochondrial dynamics-related proteins [dynamin-related protein 1 (DRP1) and its phosphorylated form at Ser616 (p-DRP1 Ser616), mitofusin 2 (MFN2), optic atrophy protein 1 (OPA1)], and the apoptosis-inducing protein Bcl-2-associated X protein (BAX).
RESULTS: (1) Compared with the normal control group, significant inflammatory response and renal function injury were observed in TIS groups at all-time points, and peaked at the 24 hours, indicating the most severe renal injury at this time point. Proteomic analysis showed that KMO expression was upregulated in renal tissues of the TIS 24-hour group compared with the normal control group, which was thus selected as the target for subsequent intervention. (2) The KMO inhibitor intervention experiment showed that compared with the Sham group, the rats in the TIS group exhibited systemic inflammatory response and renal dysfunction. Pathological observations revealed aggravated renal damage, increased cell apoptosis, and ultrastructural damage. The level of intracellular ROS was elevated, mitochondrial membrane potential was decreased, and mitochondrial dynamics were imbalanced. Compared with the TIS group, KMO inhibition could improve both systemic inflammatory response and renal function, the levels of WBC, TNF-α, IL-6, CRP, SCr, and BUN were decreased [WBC (×109/L): 9.87±2.74 vs. 25.10±3.55, TNF-α (ng/L): 213.61±81.47 vs. 820.59±105.13, IL-6 (ng/L): 986.98±105.54 vs. 2 376.28±211.80, CRP (ng/L): 1 149.55±405.60 vs. 3 355.76±439.79, SCr (μmol/L): 57.67±12.36 vs. 129.67±10.52, BUN (mmol/L): 11.63±2.60 vs. 21.53±4.31, all P<0.05], alleviated histopathological changes in the kidney, ameliorated mitochondrial ultrastructural damage in renal cells, reduced mitochondrial ROS levels and stabilized membrane potential, and both cell apoptosis and mitochondrial dynamics balance had been improved, the phosphorylation level of DRP1 Ser616 and BAX expression were both decreased [p-DRP1 Ser616 protein (p-DRP1 Ser616/DRP1): 0.88±0.15 vs. 1.63±0.13, BAX protein (BAX/GAPDH): 1.24±0.13 vs. 2.40±0.26, both P<0.05], accompanied by upregulated expression of MFN2 and OPA1 [MFN2 protein (MFN2/GAPDH): 1.09±0.08 vs. 0.64±0.03, OPA1 protein (OPA1/GAPDH): 1.13±0.07 vs. 0.74±0.14, both P<0.05].
CONCLUSIONS: KMO is upregulated in TIS-induced AKI and serves as a key factor mediating renal injury. The KMO inhibitor GSK180 exerts renal protective effects by inhibiting DRP1-mediated mitochondrial fission, promoting MFN2/OPA1-dependent mitochondrial fusion, improving mitochondrial function, and alleviating inflammation, oxidative stress and cell apoptosis.