A-052 Sex-Specific Cardiometabolic Crosstalk with Adipose Tissue in Transgenic Mice

Abstract Background Metabolic syndrome rates are rising and consist of disorders, such as obesity, related to cardiovascular disease. There is little evidence on cardiokines (compounds released from the heart), their effect on metabolism, and sex-specific responses. Previously, we investigated the effects of cardiomyocyte expression of an amino-terminal peptide of G protein-coupled receptor kinase 2 (ßARKnt) versus non-transgenic littermate controls (NLCs) on high-fat diet (HFD). In response to HFD stress, female transgenic mice show reduced cardiometabolic signaling, maladaptive cardiac remodeling and dysfunction, preserved brown adipose tissue (BAT) morphology yet decreased BAT metabolic activation, and fatal thermogenic incapacity during 4 degrees Celsius cold challenge. In contrast, male transgenic mice demonstrate enhanced cardiometabolic signaling, cardioprotection, improved white adipose tissue (WAT) health, and metabolic flexibility. Given ßARKnt is cardiomyocyte specific, the goal of this study is to elucidate the differences in mechanisms of cardiac-mediated adipose tissue crosstalk between the sexes under metabolic stress. Methods Untargeted and targeted serum metabolomics using high performance liquid chromatography-mass spectrometry (LC-MS) was performed at baseline, 4-, and 16-weeks post HFD. Multi- and Uni-variate statistical analysis, enrichment, pathway, and time series analysis was performed in addition to quantification using standards. Results Untargeted data showed a clear separation of metabolic profiles between ßARKnts and NLCs at baseline and 16 weeks post HFD. By 16 weeks, male ßARKnts exhibited a significant increase in down-regulated compounds, while female ßARKnts showed an increase in upregulated compounds (p<0.05). Several of these metabolites demonstrated correlations with time on HFD, either genotype-dependent or independent, and were overrepresented within systemic metabolic pathways. Overrepresentation refers to the identification of metabolites with higher-than-expected abundance compared to chance variation, based on known mouse metabolic pathways in online databases. Of these compounds, known signaling molecules N8-acetylspermidine, allothreonine, glutamic acid, and L-kynurenine, associated with or impact mitochondrial beta-oxidation, fatty acid synthesis, and arachidonic acid metabolism, and were selected for targeted LC-MS using the same samples. All metabolites except N8-acetylspermidine exhibited sex-specific concentration differences over time on HFD. Allothreonine displayed the most pronounced changes, alongside significant genotype-dependent differences within each sex. At 16 weeks, the mean concentrations (ng/mL, n=3-6) were 3,701 for male and 6,042 for females NLCs, compared to 2,667 for male and 4,621 for female ßARKnts. Conclusion These preliminary results support the fundamental idea that acute and chronic changes in a metabolically stressed heart lead to significant modifications in the systemic metabolome. These metabolic shifts may play a role in producing the observed sex differences in thermogenic capacity and BAT and WAT structure and function. For instance, branched-chain amino acids have been shown to influence BAT activation, suggesting structurally similar amino acids, like allothreonine, may play a role in thermogenic signaling. The findings of this study warrant further investigation to establish the specific role of the identified metabolites in regulating the different adipose tissue depots and whether they have a direct or indirect effects on thermogenesis or tissue integrity. This may reveal sex-specific cardiokines driving interorgan crosstalk during obesity and metabolic dysfunction, unveiling potential therapeutic targets for maintaining energy balance and metabolic flexibility.