Nppb contributes to Sepsis-Induced myocardial injury by regulating Senescence-Related genes

Sepsis, a systemic inflammatory condition, is a leading cause of mortality due to cardiovascular injury. Sepsis and cellular senescence are closely related, yet the specific mechanisms are still unclear. This study aims to identify a novel therapeutic target for mitigating sepsis-induced myocardial injury.

We initially assessed serum inflammatory markers and myocardial injury indicators in septic mice. This involved observing inflammatory cell infiltration in ventricular muscle tissue, assessing cardiac function, and recording electrocardiograms. We examined the expression of connexin 40 (Cx40) and connexin 43 (Cx43) and analyzed mitochondrial structures in ventricular tissues. A conditional heart-specific Nppb knockout mouse model was then developed in mice to evaluate these changes. Ventricular tissues were analyzed via mRNA sequencing to identify differentially expressed genes (DEGs), which were cross-referenced with senescence-related genes to identify key hub genes. The expression and distribution of hub genes were subsequently analyzed by single-cell analysis. Finally, the expression of the senescence-related gene CCL2, along with cardiac structure and function, was validated in a conditional heart-specific Nppb knockout sepsis mouse model.

Myocardial injury severity positively correlated with serum brain natriuretic peptide (BNP) in septic mice. Conditional heart-specific Nppb knockout improved myocardial injury outcomes in mice with sepsis. The DEGs identified in the conditional heart-specific Nppb knockout model overlapped with senescence-related genes, identifying seven upregulated genes associated with inflammation, cardiac contraction and apoptotic pathways. Single-cell analysis confirmed high CCL2 levels and an increased macrophage presence correlating with sepsis progression. Conditional heart-specific Nppb knockout reduced CCL2 levels, which were associated with improved cardiac structure and function.

This study confirms that conditional heart-specific Nppb knockout reduces CCL2 expression, thereby ameliorating myocardial injury in septic mice. Targeting Nppb to regulate the senescence-related gene CCL2 may represent an effective strategy for treating myocardial injury in septic patients.