Inhibiting the cGAS‐STING pathway in myeloid cells effectively improves myocardial healing related to TET2 deficiency‐induced DNA damage response

Abstract Background Myeloid cells play critical roles in the regulation of myocardial injury and repair. Clonal hematopoiesis (CH)‐related mutations in genes, such as Ten‐eleven Translocation 2 (TET2), can impair myeloid cells and are associated with increased risk of cardiovascular disease (CVD). How Tet2 loss‐of‐function (LOF) impacts myeloid cells and disrupts normal myocardial repair remains unclear. Methods We established ischemia‐induced myocardial infarction (MI) in a myeloid‐specific Tet2‐deficient mouse model. The echocardiographic assessment was conducted to evaluate the cardiac function. Histological analysis was performed to evaluate morphological changes in infarcted areas and fibrosis. To monitor the dynamic changes of myeloid cells in cardiac tissues during cardiac remodeling after MI, we performed longitudinal analysis on subsets of myeloid cells using flow cytometry. We performed immunofluorescence (IF) staining to examine the DNA damage and genome instability caused by Tet2 LOF. Gene expression was assessed by real‐time qRT‐PCR. Stimulator of Interferon Genes (STING) pathway activation was assessed using various methods, including Western blotting, flow cytometry, ELISA and IF staining of key signaling proteins involved in this pathway. Additionally, H‐151 was used as a pharmacological tool to antagonize augmented STING activation in the murine MI model. Results We observed a substantial increase of neutrophils in the post‐MI mice, which contributes to adverse outcomes during heart repair. Mechanistically, Tet2‐deficient myeloid cells exhibited increased genome instability, accompanied with augmented activation of the STING pathway. Furthermore, the use of H‐151 a covalent STING binder that targets the cysteine residue at position 91 and functions as a potent STING antagonist, led to a substantial decrease in neutrophil populations in Tet2‐deficient mice following myocardial infarction, thereby reversing adverse cardiac outcomes. Conclusion Our novel findings establish the rationale for targeting the cGAS‐STING pathway as a promising therapeutic strategy to mitigate cardiovascular disease risk in individuals with clonal hematopoiesis harboring TET2 loss‐of‐function mutations. Highlights Myeloid‐specific Tet2 depletion promotes neutrophil expansion upon myocardium infarction (MI); Tet2‐deficient myeloid cells exhibit increased genome instability and cGAS‐STING overactivation; STING antagonist H‐151 treatment reduces neutrophil expansion in Tet2‐deficient mice after MI and mitigates deleterious cardiac outcomes.