APOM-associated inflammation and apoptosis in stroke-exacerbated myocardial infarction: implications for brain-heart...

Brain-heart syndrome (BHS) describes cardiac dysfunction secondary to central nervous system injury, with acute ischemic stroke (AIS) serving as a critical driver that exacerbates myocardial infarction (MI). This study aimed to elucidate the role of Apolipoprotein M (APOM) in stroke-aggravated MI and to explore its underlying systemic and molecular mechanisms. Clinical data were analyzed to evaluate the correlation between stroke and MI. A combined mouse model of middle cerebral artery occlusion (MCAO) and MI was established to assess neurological and cardiac injury. Quantitative proteomics and Weighted Gene Co-expression Network Analysis (WGCNA) were employed to screen key differentially expressed proteins. The role of APOM in myocardial injury was validated using APOM-knockout (KO) mice. Furthermore, nuclear-cytoplasmic fractionation, immunofluorescence, and Western blot were performed to investigate its effects on the Saa1 and NF-κB signaling, NLRP3-related inflammatory signaling pathway, and lipid metabolism pathways. Clinical analysis indicated that stroke is a significant risk factor for MI (OR = 4.5). In the mouse model, MCAO significantly exacerbated post-MI electrocardiographic abnormalities, myocardial inflammatory response, while elevating circulating levels of cTnT and IL-1β. Proteomics identified a significant downregulation of APOM in the heart, brain, and serum post-stroke, a trend consistent with observations in AIS patients. Further experiments revealed that APOM deficiency markedly worsened cardiac conduction disturbances, histological damage, and inflammatory responses in MI mice. Mechanistically, the loss of APOM upregulates the acute-phase protein Saa1, triggers NF-κB phosphorylation and nuclear translocation, and enhances inflammatory signaling related to inflammasomes, while simultaneously mediating cytokine release from cardiomyocytes. Concurrently, APOM deficiency led to a significant decrease in sphingosine-1-phosphate (S1P) and also caused myocardial lipid droplet accumulation and metabolite changes. Additionally, the loss of APOM increased the expression of D-dimer and fibrinogen family proteins. Our findings suggest that APOM is a potential cardioprotective agent post-AIS. Downregulation of APOM may exacerbate myocardial injury after MI by elevating Saa1 expression, activating the NF-κB pathway and the inflammasome-mediated signaling, and inducing lipid metabolic disorders and coagulation-associated alterations. APOM may represent a potential therapeutic target for the intervention of brain-heart syndrome.