Abstract Body: Background: Acute myocardial ischemia/reperfusion (MI/R) triggers sterile inflammation, where innate cells drive immediate response to tissue damage and adaptive subsets influence long-term repair. While global inhibition of STING (Stimulator of Interferon Genes) is cardioprotective, neutrophil-specific STING knockout (neuSTING KO) significantly impairs recovery following MI/R; currently, the relationship between neutrophil STING signaling and the inflammation-fibrosis axis in cardiac wound healing is not fully understood.
Hypothesis: We hypothesize that STING-deficient neutrophils blunt adaptive immune activation, prolong the pro-inflammatory innate response, and promote fibrosis during the reparative phase through exacerbated inflammation and maladaptive lymphocyte-fibroblast crosstalk.
Methods: Single-cell RNA sequencing was performed on neuSTING KO and WT murine cardiac tissue at baseline and 1, 3, and 5 days post-MI/R. Immune populations were subclustered by functional markers, analyzed using pathway enrichment, and examined proportionally over time. Temporal gene expression was assessed via pseudobulked Likelihood Ratio Test.
Results: Compared to WT, neuSTING KO mice showed increased Treg proportions, delayed naïve T cell recruitment, and reduced effector populations, suggesting Treg-mediated suppression of T cell activation post-insult. neuSTING KO mice exhibited sustained γδT populations through day 5, whereas WT γδT cells declined; the persistence of IL-17-producing γδT cells suggests a stalled transition from inflammation to repair.
By day 5, WT mice increased T cell Ifng expression, a shift absent in KO mice. Instead, KO mice displayed a fivefold increase of a unique Il12rb2+ cytotoxic cluster. This shift may represent a compensatory mechanism for deficient stimulatory signaling, meant to increase IL-12 sensitivity and induce IFNγ production, potentially leading to inflammatory overcorrection and fibrosis in the repair phase.
Conclusion: These findings demonstrate that STING signaling in neutrophils is required for the timely activation of the adaptive immune response, and its loss creates a dysfunctional inflammatory environment that precludes effective cardiac wound healing post-MI/R.