Melatonin alleviates cardiomyocyte necroptosis in diabetic mice by inhibiting the STING signaling pathway

doi:10.12122/j.issn.1673-4254.2026.05.20

Abstract

Abstract:

Objective To investigate the protective effect of melatonin against diabetic cardiomyopathy (DCM) and whether melatonin regulates cardiomyocyte necroptosis and inflammatory response through the stimulator of interferon genes (STING) signaling pathway. Methods C57 mouse models of DCM induced by streptozotocin (STZ) injection were given an intraperitoneal injection of saline or melatonin (n=6), and 24 h later blood and myocardial samples were collected from the mice for analysis. A cell model of DCM was established in HL-1 cells by high glucose treatment (33 mmol/L). Pathological changes in myocardial tissue of the mice were observed using HE staining. Immunofluorescence staining and Western blotting were used to detect the key necroptosis proteins, and the pro-inflammatory factors including IL-1β, IL-6, and TNF-α were detected with Western blotting and ELISA to evaluate cell death and inflammation. The expression levels of the proteins associated with STING pathway activation (P-IRF3 and P-P65) were detected using immunohistochemistry and Western blotting. Results In the diabetic mice and cell models of DCM, the STING signaling pathway was activated with significantly increased protein expressions of STING and P-IRF3. The myocardial tissues of DCM mice showed increased inflammatory infiltration with upregulated serum and myocardial levels of IL-1β, IL-6, and TNF-α and increased levels of necroptosis-related proteins P-MLKL, P-RIPK1, and P-RIPK3. Treatment with melatonin significantly inhibited the activation of the STING signaling pathway and reduced the expression levels of inflammatory factors and necroptosis-related proteins, and the use of the STING agonist DMXAA significantly attenuated the protective effect of melatonin. Conclusion Melatonin effectively alleviates cardiomyocyte necroptosis and inflammatory response in DCM by inhibiting the STING signaling pathway.

Key words: melatonin, diabetic cardiomyopathy, STING signaling pathway, necroptosis, inflammatory response

Dan MA, Shuyuan CAO, Yi JIANG, Yuce PENG, An HE, Minghao LUO, Suxin LUO. Melatonin alleviates cardiomyocyte necroptosis in diabetic mice by inhibiting the STING signaling pathway[J]. Journal of Southern Medical University, 2026, 46(5): 1157-1166.

Figures/Tables 4

Fig.1 Melatonin alleviates myocardial injury in diabetic mice and inhibits the expression of inflammatory factors. A: HE staining of mouse myocardial tissues (Scale bar=50 μm). B: Serum levels of IL-6, IL-1β, and TNF-α of the mice (n=6). C: Western blotting for detecting IL-1β, TNF-α, and iNOS expressions in mouse myocardial tissues (n=3). D: Myocardial expression of iNOS determined by immunofluorescence assay (Scale bar=100 μm; n=3). *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001 vs Sham/CON group; #P<0.05, ##P<0.01, ###P<0.001 vs DM/HG group.

Fig.2 Melatonin inhibits necroptosis in diabetic cardiomyocytes. A: Western blotting for detecting RIPK1/P-RIPK1, RIPK3/P-RIPK3, and P-MLKL expressions in mouse myocardial tissues (n=3). B: Expression of P-RIPK1 in mouse myocardial tissues determined by immunohistochemistry and immunofluorescence staining (Scale bar=100 μm; n=3). C: Western blotting for detecting expressions of RIPK1/P-RIPK1, RIPK3/P-RIPK3, and P-MLKL in the cell models (n=3). *P<0.05, **P<0.01, ***P<0.001 vs Sham/CON group; #P<0.05, ##P<0.01, ###P<0.001 vs DM/HG group.

Fig.3 Melatonin inhibits diabetes-induced activation of the STING signaling pathway. A: Western blotting for detecting P-IRF3 and STING expressions in mouse myocardial tissues (n=3). B: Expression of P-P65 in mouse myocardial tissues determined by immunohistochemistry (Scale bar=100 μm; n=3). C: Western blotting for detecting P-IRF3 and STING expressions in the cell models (n=3). **P<0.01 vs Sham/CON group; #P<0.05,##P<0.01, ###P<0.001 vs DM/HG group.

Fig.4 Activation of STING partially reverses the protective effect of melatonin. A: Western blotting for detecting iNOS, IL-1β, TNF-α, P-RIPK1, P-RIPK3, P-MLKL, P-IRF3, and STING expressions in HL-1 cells with different treatments (n=3). B: Immunofluorescence staining for analysis of extramitochondrial mtDNA (Scale bar=20 μm; n=3). *P<0.05, **P<0.01, ***P<0.001 vs CON group; ##P<0.01, ###P<0.001 vs HG group; &P<0.05, &&P<0.01, &&&P<0.001 vs HG+Mel group.

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