Daily Cardiology Research Analysis

Transcriptional activity perturbation holds promise for selectively modulating harmful transcriptional networks, but its therapeutic potential remains largely unexplored. We employed a network-based analysis of single-cell heart transcriptomes to identify transcription factor activities linked to pathological cardiomyocytes in vivo. This analysis revealed that transcriptional activity of Krüppel-like factor 15 (KLF15) exhibited the most significant change in pathological cardiomyocytes, characterized by less effective repression of disease-associated genes in stressed hearts, which correlated with reduced KLF15 expression. To restore KLF15 activity, we utilized CRISPR/nuclease-dead (d)Cas9-based transcriptional enhancement (CRISPRa) in cardiomyocytes, which effectively abolished fetal reprogramming by simultaneously suppressing pathological gene expression and restoring metabolic homeostasis under sustained stress conditions. Furthermore, we identified a novel cell-nonautonomous anti-fibrotic effect mediated by cardiomyocyte-fibroblast crosstalk, and revealed the contribution of KLF15-dependent Alpha-2-glycoprotein 1, zinc-binding (AZGP1) regulation in this process. We also elucidated the upstream mechanisms of KLF15 regulation, highlighting its role as a cell-specific downstream target of the broad TGF-β canonical signaling pathway, along with its downstream-dependent mechanisms in human cardiomyocytes. Finally, to enhance the therapeutic potential of this approach, we engineered and validated an adeno-associated viral (AAV) vector with a small CRISPRa system for endogenous regulation in human cardiomyocytes suitable for clinical applications. Overall, we elucidated a regulatory circuit involving TGF-β, KLF15, and AZGP1, which coordinates critical pathological responses through cellular crosstalk between cardiomyocytes and fibroblasts. Importantly, we demonstrated the efficacy of CRISPRa as an epigenetic intervention restoring a critical transcriptional function disrupted in non-genetic heart failure. This approach provides a promising blueprint for future adaptation targeting additional non-hereditary pathologies.

BACKGROUND: Chronic kidney disease (CKD) significantly increases the risk of atrial fibrillation (AF). Although alterations in the gut microbiota have been linked to CKD progression, its exact involvement in CKD-associated AF remians unclear. We amis to investigate the role of gut microbiota in the development of CKD-associated AF, and to uncover potential mechanisms that could serve as effective targets for prevention and treatment. METHODS AND RESULTS: A rat model of CKD was induced by an adenine-enriched diet. 16S rRNA sequencing and fecal microbiota transplantation (FMT) were utilized to study the involvement of gut microbiota. AST-120, gut barrier protectants and mono-colonization experiments were performed to investigate potential mechanism. CKD rats exhibited gut microbiota dysbiosis and a significantly increased susceptibility to AF. FMT from CKD rats transferred this heightened AF susceptibility to healthy recipient rats, linked to the activation of the NLRP3 inflammasome. Mechanistically, gut dysbiosis in CKD patients leads to elevated IS levels, causing gut barrier dysfunction and increased circulating lipopolysaccharide (LPS). Elevated LPS activates atrial TLR4 receptors, triggering NLRP3 inflammasome activation, which contributes to AF pathogenesis. Treatment with the IS scavenger AST-120 or gut barrier protectants successfully prevented CKD-associated AF. Furthermore, supplementation with Lactobacillus gasseri reduced circulating IS levels and mitigated AF susceptibility in CKD rats. CONCLUSION: This study demonstrates that gut dysbiosis-driven elevation of IS and subsequent activation of the atrial NLRP3 inflammasome are key mechanisms in CKD-associated AF. Modulating the gut microbiota could provide a new therapeutic strategy for CKD-associated AF.

GLP-1 receptor (GLP-1R) agonists decrease blood glucose and body weight and reduce rates of cardiovascular and renal disease. Although GLP-1R activation lowers blood pressure (BP), the underlying mechanisms remain incompletely understood and have been attributed to weight loss and endothelial cell GLP-1R signaling. Here, we show that GLP-1Rs in vascular smooth muscle cells (VSMCs) are essential for semaglutide-mediated BP reduction in mice. In contrast, GLP-1Rs in Tie2+ endothelial or immune cells are not required for semaglutide to lower BP. The VSMC GLP-1R is dispensable for the effects of semaglutide on food intake, body weight, and blood glucose, but is required for its actions to increase glomerular filtration rate and promote natriuresis. Systemic semaglutide administration resulted in proteomic changes in the renal artery and kidney in pathways related to platelet aggregation, fibrin clot formation, lipid metabolism, and pro-apoptotic signaling that are abolished in mice lacking VSMC GLP-1R expression. Moreover, semaglutide directly induced vasorelaxation in pre-constricted mesenteric arteries ex vivo. Together, these findings identify VSMCs as a key cellular target linking GLP-1R activation to BP regulation, renal electrolyte excretion, and proteomic changes in renal artery and kidney.