Endothelial dysfunction is a hallmark of various metabolic disorders and plays a pivotal role in the progression of cardiovascular diseases, including coronary microvascular dysfunction and myocardial ischemia. Lipid droplets (LDs) have emerged as key regulators of fatty acid metabolism in endothelial cells (ECs), but their functional role in lipotoxicity-induced EC damage in the context of coronary microvascular dysfunction remains unclear. Here, we examined the contribution of LD biogenesis to oleic acid-induced lipotoxic effects in mouse cardiac ECs (MCECs). Our findings reveal that oleic acid markedly increases LD biogenesis in MCECs via a diacylglycerol O-acyltransferase 1 (DGAT1)-dependent pathway. This process is accompanied by substantial disruptions in cellular homeostasis, including elevated endoplasmic reticulum (ER) stress, impaired mitochondrial respiration, reduced ATP production, and heightened hypoxic responses. Furthermore, oleic acid-induced lipotoxicity is primarily mediated by ferroptosis−a form of lipid peroxide-dependent, caspase-independent cell death. Notably, pharmacological inhibition or genetic knockdown of DGAT1, which diminishes LD biogenesis, exacerbates oleic acid-induced cellular stress, mitochondrial dysfunction, and ferroptosis in MCECs. These results suggest that LD biogenesis plays a protective role in mitigating lipotoxicity, preserving mitochondrial function, and preventing lipid peroxide accumulation and ferroptosis, thereby safeguarding cardiac microvascular endothelial function in the context of metabolic disorders.

Background: Accumulating evidence indicates that coronary microvascular dysfunction (CMD) caused by hypercholesterolemia can lead to myocardial ischemia, with or without obstructive atherosclerotic coronary artery disease. However, the molecular pathways associated with compromised coronary microvascular function before the development of myocardial ischemic injury remain poorly defined. In this study, we investigated the effects of hypercholesterolemia on the function and integrity of the coronary microcirculation in mice and the underlying mechanisms. Methods and Results: Mice were fed a hypercholesterolemic Paigen's diet for 8 weeks. Echocardiography data showed that Paigen's diet caused CMD, characterized by significant reductions in coronary blood flow and coronary flow reserve, but did not affect cardiac remodeling or dysfunction. Immunofluorescence studies revealed that Paigen's diet–induced CMD was associated with activation of coronary arterioles inflammation and increased myocardial inflammatory cell infiltration. These pathological changes occurred in parallel with the upregulation of lysosomal signaling pathways in endothelial cells (ECs). Treating hypercholesterolemic mice with the cholesterol‐lowering drug ezetimibe significantly ameliorated Paigen's diet–induced adverse effects, including hypercholesterolemia, steatohepatitis, reduced coronary flow reserve, coronary endothelial cell inflammation, and myocardial inflammatory cell infiltration. In cultured mouse cardiac ECs, 7‐ketocholesterol increased mitochondrial reactive oxygen species and inflammatory responses. Meanwhile, 7‐ketocholesterol induced the activation of transcriptional factor EB and lysosomal signaling in mouse cardiac ECs, whereas the lysosome inhibitor bafilomycin A1 blocked 7‐ketocholesterol–induced transcriptional factor EB activation and exacerbated 7‐ketocholesterol–induced inflammation and cell death. Interestingly, ezetimibe synergistically enhanced 7‐ketocholesterol–induced transcriptional factor EB activation and attenuated 7‐ketocholesterol–induced mitochondrial reactive oxygen species and inflammatory responses in mouse cardiac ECs. Conclusions: These results suggest that CMD can develop and precede detectable cardiac functional or structural changes in the setting of hypercholesterolemia and that upregulation of transcriptional factor EB–mediated lysosomal signaling in endothelial cells plays a protective role against CMD.

HIF-1α plays a crucial regulatory role in vascular calcification (VC), primarily influencing the osteogenic differentiation of VSMCs through oxygen-sensing mechanisms. Under hypoxic conditions, the stability of HIF-1α increases, avoiding PHD and VHL protein-mediated degradation, which promotes its accumulation in cells and then activates gene expressions related to calcification. Additionally, HIF-1α modulates the metabolic state of VSMCs by regulating the pathways that govern the switch between glycolysis and oxidative phosphorylation, thereby further advancing the calcification process. The interaction between HIF-1α and other signaling pathways, such as nuclear factor-κB, Notch, and Wnt/β-catenin, creates a complex regulatory network that serves as a critical driving force in VC. Therefore, a deeper understanding of the role and regulatory mechanism of the HIF-1α signaling during the development and progression of VC is of great significance, as it is not only a key molecular marker for understanding the pathological mechanisms of VC but also represents a promising target for future anti-calcification therapies.

Lysosomes in mammalian cells are recognized as key digestive organelles, containing a variety of hydrolytic enzymes that enable the processing of both endogenous and exogenous substrates. These organelles digest various macromolecules and recycle them through the autophagy–lysosomal system. Recent research has expanded our understanding of lysosomes, identifying them not only as centers of degradation but also as crucial regulators of nutrient sensing, immunity, secretion, and other vital cellular functions. The lysosomal pathway plays a significant role in vascular regulation and is implicated in diseases such as atherosclerosis. During atherosclerotic plaque formation, macrophages initially engulf large quantities of lipoproteins, triggering pathogenic responses that include lysosomal dysfunction, foam cell formation, and subsequent atherosclerosis development. Lysosomal dysfunction, along with the inefficient degradation of apoptotic cells and the accumulation of modified low-density lipoproteins, negatively impacts atherosclerotic lesion progression. Recent studies have highlighted that lysosomal dysfunction contributes critically to atherosclerosis in a cell- and stage-specific manner. In this review, we discuss the mechanisms of lysosomal biogenesis and its regulatory role in atherosclerotic lesions. Based on these lysosomal functions, we propose that targeting lysosomes could offer a novel therapeutic approach for atherosclerosis, shedding light on the connection between lysosomal dysfunction and disease progression while offering new insights into potential anti-atherosclerotic strategies.

This study reveals that the NLRP3-GSDMD axis drives PDGF-BB-induced dedifferentiation transition and inflammation of vascular smooth muscle cells (VSMCs), contributing to intimal hyperplasia. These findings identify NLRP3-GSDMD signaling as a novel driver of pathological vascular remodeling and a potential therapeutic target for intimal hyperplasia-associated cardiovascular diseases.