Cardiovascular Research最新文献

Aims: Atherosclerosis is a major global health challenge, with limited diagnostic and therapeutic options. Macrophages drive disease progression, but their tissue-specific phenotypes and functions remain poorly defined. This study aims to elucidate macrophage-driven mechanisms by characterizing their functional diversity across key metabolic and vascular tissues.

Methods and results: We used single-cell RNA sequencing (scRNA-seq) and translating ribosome affinity purification sequencing (TRAP-seq) to profile macrophage-specific gene programmes in a mouse model of atherosclerosis across the aorta, adipose tissue, and liver. Our data highlight tissue-specific macrophage gene programmes and identify markers that are shared across mouse and human plaques. First, we identified soluble Trem2 as a potential circulating biomarker for differentiating between asymptomatic and symptomatic individuals. Secondly, we leveraged the pronounced expression of Folr2 and Slc7a7 to explore the potential of folate and glutamine as positron emission tomography (PET) tracers for disease burden assessment through in vivo PET imaging. Finally, we show that knockout of Slc7a7 inhibits acetylated low-density lipoprotein uptake and dampens the gene signature linked to lipid-associated macrophages. This suggests that glutamine signalling may play a critical role in foam cell formation, a key event in atherosclerosis.

Conclusion: Our findings provide novel insights into macrophage-specific gene programmes during atherosclerosis progression and identify a set of promising biomarkers that can serve as a resource for future studies. These findings could significantly contribute to improving the diagnosis, monitoring, and treatment of atherosclerosis.

Aims: High dietary salt intake has powerful effects on cerebral blood vessels and has emerged as a risk factor for stroke and cognitive impairment. In mice, a high salt diet (HSD) leads to reduced cerebral blood flow (CBF), tau hyperphosphorylation, and cognitive dysfunction. However, it is still unclear whether the reduced CBF is responsible for the effects of HSD on tau and cognition. Capillary stalling has been linked to cognitive impairment in models of Alzheimer's disease and diabetes. Therefore, we tested the hypothesis that capillary stalling also contributes to CBF reduction, tau accumulation, and cognitive impairment in HSD.

Methods and results: We used in vivo two-photon imaging to assess capillary stalling in C57BL6/J male mice fed a normal diet or HSD. We found that HSD increased stalling of neutrophils in brain capillaries and decreased CBF. Neutrophil depletion using anti-Ly6G antibodies reduced the number of stalled capillaries and restored CBF, measured by red blood cell speed. Despite the improved CBF, chronic neutrophil depletion did not rescue HSD-induced cognitive impairment, assessed by the Barnes maze and nest building behavior. Furthermore, levels of phosphorylated tau in the cortex and hippocampus remained elevated in HSD mice after neutrophil depletion.

Conclusion: These novel findings show that capillary stalling contributes to CBF reduction in HSD, but not to tau phosphorylation and cognitive deficits. Therefore, the hypoperfusion caused by capillary stalling is not the main driver of the tau phosphorylation and cognitive impairment.

Aims: SCN5A encodes cardiac sodium channel Nav1.5 that maintains normal electrophysiological functions of hearts. Loss-of-function variants of Nav1.5 reduce sodium current densities (INa) and cause arrhythmias such as cardiac conduction block or Brugada syndrome. The regulatory mechanisms of Nav1.5 functions are not fully understood. The aim of this study was to identify novel proteins that interact with Nav1.5 and characterize their regulatory mechanisms on Nav1.5 and arrhythmias.

Methods and results: GST pull-down coupled with mass spectrometry, co-immunoprecipitation, and mutational analysis were used to identify de-ubiquitinating enzyme USP10 as a novel Nav1.5-interacting protein, and showed that USP10 reduces Nav1.5 protein expression and INa densities in vitro. AAV9-mediated cardiac overexpression of USP10 in mice reduced Nav1.5 protein expression, INa and ICa-L densities, shortened APD, and caused delayed ventricular activation, spontaneous atrioventricular conduction block, sinus pause, and ventricular tachycardia induced with electrical pacing. Cardiac knockdown of USP10 in Scn5a+/- mice restored Nav1.5, INa, and ICa-L to levels comparable to wild-type mice, and alleviated the conduction delay and premature ventricular contractions. Mechanistically, USP10 increased Nav1.5 protein degradation through chaperone-mediated autophagy (CMA) as the effect was blocked by lysosome inhibitor CQ and inhibition of CMA using siRNA targeting LAMP2A or HSC70, but not by proteasomal inhibitor MG132. Mutational analysis identified the key CMA degradation motif of Nav1.5 as EKRFQ431-435. USP10 decreased Nav1.5 ubiquitination and increased binding of Nav1.5 to HSC70. Mutational analysis identified K430 of Nav1.5 as the USP10 de-ubiquitination site, and K430R mutation blocked regulation of Nav1.5 by USP10.

Conclusion: We identified a novel CMA-mediated pathway regulating degradation of Nav1.5 by coupling with USP10-mediated de-ubiquitination at K430 of Nav1.5, which resulted in reduced INa densities and cardiac conduction defects. Knockdown of USP10 alleviated arrhythmias in Scn5a+/- mice, providing a novel therapeutic strategy for treating arrhythmias with reduced INa.

Aims: The Rho kinases 1 and 2 (ROCK1/2) are serine-threonine specific protein kinases that control actin cytoskeleton dynamics. They are expressed in all cells throughout the body, including cardiomyocytes, smooth muscle cells and endothelial cells (ECs), and are intimately involved in cardiovascular health and disease. Pharmacological ROCK inhibition is beneficial in mouse models of hypertension, atherosclerosis, and neointimal thickening that display overactivated ROCK. However, the consequences of endothelial ROCK signalling deficiency in vivo remained unknown.

Methods and results: To address this issue, we generated Cdh5CreERT2 driven, tamoxifen inducible loss of function alleles of ROCK1 and ROCK2 and analysed mouse survival and vascular defects through cellular, biochemical, and molecular biology approaches. We observed that postnatal or adult loss of endothelial ROCK1 and 2 was lethal within a week. Mice developed multi-organ haemorrhage along with loss of vascular integrity. ECs displayed deficient cytoskeletal actin polymerization that prevented focal adhesion formation and disrupted junctional integrity. Retinal sprouting angiogenesis was also perturbed, as sprouting vessels exhibited lack of polymerized actin and defective lumen formation. In a three-dimensional endothelial sprouting assay, combined knockdown of ROCK1/2 or individual knockdown of ROCK2 but not ROCK1 led to reduced sprouting, lumenization and cell polarization defects caused by defective actin and altered VE-cadherin dynamics. The isoform specific role of endothelial ROCK2 correlated with ROCK2 substrate specificity for FAK and LIMK. By analysing single and three allele mutants we show that one intact allele of ROCK2 is sufficient to maintain vascular integrity in vivo.

Conclusion: Endothelial ROCK1 and 2 maintain junctional integrity and ensure proper angiogenesis and lumen formation. The presence of one allele of ROCK2 is sufficient to maintain vascular growth and integrity. These data indicate the need for careful consideration when using ROCK inhibitors in disease settings.