Single-Cell RNA Sequencing Deconstructs the Distribution of Immune Cells Within Abdominal Aortic Aneurysms in Mice.

BACKGROUND: Inflammation is a key component in the development of abdominal aortic aneurysm (AAA), yet insights into the roles of immune cells and their interactions in this process are limited. METHODS: Using single-cell RNA transcriptomic analysis, we deconstructed the CD45+ cell population in elastase-induced murine AAA at the single-cell level. We isolated each group of immune cells from murine AAA tissue at different time points and divided them into several subtypes, listed the remarkable differentially expressed genes, explored the developmental trajectories of immune cells, and demonstrated the interactions among them. RESULTS: Our findings reveal significant differences in several immune cell subsets, including macrophages, dendritic cells, and T cells, within the AAA microenvironment compared with the normal aorta. Especially, conventional dendritic cell type 1 exclusively existed in the AAA tissue rather than the normal aortas. Via CellChat analysis, we identified several intercellular communication pathways like visfatin, which targets monocyte differentiation and neutrophil extracellular trap-mediated interaction between neutrophils and dendritic cells, which might contribute to AAA development. Some of these pathways were validated in human AAA. CONCLUSIONS: Despite the absence of external pathogenic stimuli, AAA tissues develop a complex inflammatory microenvironment involving numerous immune cells. In-depth studies of the inflammatory network shall provide new strategies for patients with AAA.

Catheter ablation of atrial fibrillation in a patient with interruption of the inferior vena cava complicated with persistent left superior vena cava.

A 55-year-old woman of I-IVC complicated with PLSVC underwent catheter ablation for atrial fibrillation through right jugular vein access. TSP was achieved by electrocautery and the J-tip guidewire with the help of deflectable sheath and ICE. After PVI, the CS-PLSVC and LA-PLSVC connections were ablated within PLSVC.

The efficiency and safety of multidetector computed tomography-guided transseptal puncture during atrial fibrillation catheter ablation.

Background: Transseptal puncture (TSP) is a crucial technique for catheter ablation of atrial fibrillation (AF). Although intracardiac echo (ICE) facilitates a safe and accurate TSP, it is not widely used in developing countries because of the expense. This study evaluated the efficiency and safety of a novel cardiac multidetector computed tomography (MDCT)-guided TSP during AF catheter ablation. Methods: The study consisted of two cohorts. In the index cohort, TSP procedure was performed under the guidance of ICE, and we recorded the angulation of right anterior oblique of X-ray projection. In the validation cohort, we compared the efficiency and safety of TSP guided by MDCT-calculated angulation with propensity-score-matched patients who underwent TSP guided by ICE. Results: We included 50 patients in the index cohort, and the mean angles of interatrial septum (IAS) measured from MDCT and ICE were 34.8 ± 6.3 and 35.1 ± 6.5, respectively. In the validation cohort, 376 patients were enrolled in the MDCT-guided group and ICE-guided group. Both groups had 1 case of cardiac tamponade. The mean axial plane angle was 35.46 ± 6.17 degrees, which was not influenced by age, gender, BMI, and LA size, while a moderate positive linear correlation between EF and the axial plane angle (R 2 = 0.14, p = .006). Conclusion: Cardiac MDCT can provide a clear vision of IAS orientation, and provide the appropriate RAO angle and height for TSP. The efficiency and safety of our MDCT-guided TSP were comparable to ICE-guided TSP, which may serve as an alternative method for TSP with ICE unavailable.

IRF5 governs macrophage adventitial infiltration to fuel abdominal aortic aneurysm formation.

Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease characterized by the expansion of the aortic wall. One of the most significant features is the infiltration of macrophages in the adventitia, which drives vasculature remodeling. The role of macrophage-derived interferon regulatory factor 5 (IRF5) in macrophage infiltration and AAA formation remains unknown. RNA sequencing of AAA adventitia identified Irf5 as the top significantly increased transcription factor that is predominantly expressed in macrophages. Global and myeloid cell-specific deficiency of Irf5 reduced AAA progression, with a marked reduction in macrophage infiltration. Further cellular investigations indicated that IRF5 promotes macrophage migration by direct regulation of downstream phosphoinositide 3-kinase γ (PI3Kγ, Pik3cg). Pik3cg ablation hindered AAA progression, and myeloid cell-specific salvage of Pik3cg restored AAA progression and macrophage infiltration derived from Irf5 deficiency. Finally, we found that IRF5 and PI3Kγ expression in the adventitia is significantly increased in patients with AAA. These findings reveal that the IRF5-dependent regulation of PI3Kγ is essential for AAA formation.

Successful ablation of a right concealed epicardial accessory pathway using ethanol infusion.

INTRODUCTION: This study describes a rare case of concealed epicardial accessory pathway (AP) successfully ablated using ethanol infusion (EI) through a variant vessel connecting the right atrium (RA) and the right ventricle (RV) surface. METHODS AND RESULTS: A 58-year-old male referred to our hospital for prior failed AP ablation. Cardiac-enhanced computerized tomography scan showed there was a variant vessel at the tip of right atrial appendage and a pulmonary artery (PA)-RA fistula at the roof of RA. The earliest activation was present at the site of the PA-RA fistula. A selective angiography showed that a small branch of the variant vessel covered the earliest excitation site of the AP. EI into this branch successfully repressed the AP without any recurrences within a follow-up period of 3 months. CONCLUSION: Endocardial ablation is challenging for epicardial APs related to cardiac structural variations. If small vascular branches near the earliest activation site can be found, EI can successfully ablate these types of epicardial APs.

Novel combinations of variations in KCNQ1 were associated with patients with long QT syndrome or Jervell and Lange-Nielsen syndrome.

OBJECTIVES: Long QT syndrome (LQTS) is one of the primary causes of sudden cardiac death (SCD) in youth. Studies have identified mutations in ion channel genes as key players in the pathogenesis of LQTS. However, the specific etiology in individual families remains unknown. METHODS: Three unrelated Chinese pedigrees diagnosed with LQTS or Jervell and Lange-Nielsen syndrome (JLNS) were recruited clinically. Whole exome sequencing (WES) was performed and further validated by multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing. RESULTS: All of the probands in our study experienced syncope episodes and featured typically prolonged QTc-intervals. Two probands also presented with congenital hearing loss and iron-deficiency anemia and thus were diagnosed with JLNS. A total of five different variants in KCNQ1, encoding a subunit of the voltage-gated potassium channel, were identified in 3 probands. The heterozygous variants, KCNQ1 c.749T > C was responsible for LQTS in Case 1, transmitting in an autosomal dominant pattern. Two patterns of compound heterozygous variants were responsible for JLNS, including a large deletion causing loss of the exon 16 and missense variant c.1663 C > T in Case 2, and splicing variant c.605-2 A > G and frame-shift variant c.1265del in Case 3. To our knowledge, the compound heterozygous mutations containing a large deletion and missense variant were first reported in patients with JLNS. CONCLUSION: Our study expanded the LQTS genetic spectrum, thus favoring disease screening and diagnosis, personalized treatment, and genetic consultation.

Oxidative stress and valvular endothelial cells in aortic valve calcification.

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

Endoplasmic Reticulum Stress and Pathogenesis of Vascular Calcification.

Vascular calcification (VC) is characterized by calcium phosphate deposition in blood vessel walls and is associated with many diseases, as well as increased cardiovascular morbidity and mortality. However, the molecular mechanisms underlying of VC development and pathogenesis are not fully understood, thus impeding the design of molecular-targeted therapy for VC. Recently, several studies have shown that endoplasmic reticulum (ER) stress can exacerbate VC. The ER is an intracellular membranous organelle involved in the synthesis, folding, maturation, and post-translational modification of secretory and transmembrane proteins. ER stress (ERS) occurs when unfolded/misfolded proteins accumulate after a disturbance in the ER environment. Therefore, downregulation of pathological ERS may attenuate VC. This review summarizes the relationship between ERS and VC, focusing on how ERS regulates the development of VC by promoting osteogenic transformation, inflammation, autophagy, and apoptosis, with particular interest in the molecular mechanisms occurring in various vascular cells. We also discuss, the therapeutic effects of ERS inhibition on the progress of diseases associated with VC are detailed.

Endothelial cell-derived tetrahydrobiopterin prevents aortic valve calcification.

AIMS: Tetrahydrobiopterin (BH4) is a critical determinant of the biological function of endothelial nitric oxide synthase. The present study was to investigate the role of valvular endothelial cell (VEC)-derived BH4 in aortic valve calcification. METHODS AND RESULTS: Plasma and aortic valve BH4 concentrations and the BH4:BH2 ratio were significantly lower in calcific aortic valve disease patients than in controls. There was a significant decrease of the two key enzymes of BH4 biosynthesis, guanosine 5'-triphosphate cyclohydrolase I (GCH1) and dihydrofolate reductase (DHFR), in calcified aortic valves compared with the normal ones. Endothelial cell-specific deficiency of Gch1 in Apoe-/- (Apoe-/-Gch1fl/flTie2Cre) mice showed a marked increase in transvalvular peak jet velocity, calcium deposition, runt-related transcription factor 2 (Runx2), dihydroethidium (DHE), and 3-nitrotyrosine (3-NT) levels in aortic valve leaflets compared with Apoe-/-Gch1fl/fl mice after a 24-week western diet (WD) challenge. Oxidized LDL (ox-LDL) induced osteoblastic differentiation of valvular interstitial cells (VICs) co-cultured with either si-GCH1- or si-DHFR-transfected VECs, while the effects could be abolished by BH4 supplementation. Deficiency of BH4 in VECs caused peroxynitrite formation increase and 3-NT protein increase under ox-LDL stimulation in VICs. SIN-1, the peroxynitrite generator, significantly up-regulated alkaline phosphatase (ALP) and Runx2 expression in VICs via tyrosine nitration of dynamin-related protein 1 (DRP1) at Y628. Finally, folic acid (FA) significantly attenuated aortic valve calcification in WD-fed Apoe-/- mice through increasing DHFR and salvaging BH4 biosynthesis. CONCLUSION: The reduction in endothelial-dependent BH4 levels promoted peroxynitrite formation, which subsequently resulted in DRP1 tyrosine nitration and osteoblastic differentiation of VICs, thereby leading to aortic valve calcification. Supplementation of FA in diet attenuated hypercholesterolaemia-induced aortic valve calcification by salvaging BH4 bioavailability.

The Protective Effect of Metformin on Abdominal Aortic Aneurysm: A Systematic Review and Meta-Analysis.

Background: Type 2 diabetes mellitus (T2DM) patients have a lower risk of abdominal aortic aneurysm (AAA) and its comorbidities, which might be associated with the usage of metformin. The objective of the study was to evaluate the role of metformin in the process of AAA development. Method: PubMed, Embase and Cochrane Library were searched up to May 15th, 2021. We implemented several methods including the risk of bias graph, GRADE system and funnel plot to assess the quality and possible bias of this study. Subgroup analysis and sensitivity analysis were applied to address quality differences and validate the robustness of the final results. Result: Ten articles were enrolled after screening 151 articles searched from databases. The pooled results showed that, compared with T2DM patients without metformin, metformin prescription was associated with a slower annual growth rate of the aneurysm (mean difference (MD) -0.67 cm [95% confidence interval (CI) -1.20 ~ -0.15 cm]). Besides, metformin exposure was associated with a lower frequency of AAA events (odds ratio (OR) 0.61 [95% CI 0.41-0.92]). Conclusion: Metformin alleviated both annual expansion rate and aneurysm rupture frequency in AAA patients with T2DM. Systematic Review Registration: PROSPERO, identifier https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=217859 (CRD42020217859).

AMPK: Potential Therapeutic Target for Vascular Calcification.

Vascular calcification (VC) is an urgent worldwide health issue with no available medical treatment. It is an active cell-driven process by osteogenic differentiation of vascular cells with complex mechanisms. The AMP-activated protein kinase (AMPK) serves as the master sensor of cellular energy status. Accumulating evidence reveals the vital role of AMPK in VC progression. AMPK is involved in VC in various ways, including inhibiting runt-related transcription factor 2 signaling pathways, triggering autophagy, attenuating endoplasmic reticulum stress and dynamic-related protein 1-mediated mitochondrial fission, and activating endothelial nitric oxide synthase. AMPK activators, like metformin, are associated with reduced calcification deposits in certain groups of patients, indicating that AMPK is a potential therapeutic target for VC.

The Association Between Metformin Treatment and Outcomes in Type 2 Diabetes Mellitus Patients With Heart Failure With Preserved Ejection Fraction: A Retrospective Study.

Background: Metformin is the first-line antidiabetic medication for type 2 diabetes mellitus (T2DM). However, the association between metformin and outcomes in T2DM patients with heart failure with preserved ejection fraction (HFpEF) is still unknown. We aimed to explore the association between metformin and adverse outcome in T2DM patients with HFpEF. Methods: A total of 372 T2DM patients with HFpEF hospitalized from January 1, 2013, to December 31, 2017, were included in this retrospective cohort study. There were 113 and 259 subjects in metformin and non-metformin group, respectively. Subjects were followed up for all-cause mortality, cardiovascular death, all-cause hospitalization, and heart failure hospitalization. Results: The median follow-up period was 47 months. Eleven patients (2.49% per patient-year) in the metformin group and 56 patients (5.52% per patient-year) in the non-metformin group deceased during follow-up (P = 0.031). However, a multivariable Cox regression failed to show that metformin was an independent factor of all-cause mortality [HR (95% CI) = 0.682 (0.346-1.345); P = 0.269]. A subgroup analysis revealed a significant association between metformin and all-cause mortality in patients with a higher hemoglobin A1c (HbA1c) level (HbA1c ≥7%) [HR (95% CI) = 0.339 (0.117-0.997); P = 0.045]. The 4-year estimated number needed to treat (NNT) with metformin compared with non-metformin for all-cause mortality was 12 in all populations and 8 in the HbA1c ≥7% subgroup. Conclusions: Metformin was not independently associated with clinical outcomes in patients with T2DM and HFpEF, but was associated with lower all-cause mortality in the subgroup of patients with poor glycemic control. Prospective, randomized controlled trials are needed to further verify these findings.

Identification and characterization of dynamically regulated hepatitis-related genes in a concanavalin A-induced liver injury model.

BACKGROUND: Concanavalin A (ConA)-induced liver damage of mice is a well-established murine model mimicking the human autoimmune hepatitis (AIH). However, the pathogenic genes of the liver injury remain to be revealed. METHODS: Using time-series liver transcriptome, top dynamic genes were inferred from a set of segmented regression models, and cross-checked by weighted correlation network analysis (WGCNA). AIH murine models created by ConA were used to verify the in vivo effect of these genes. RESULTS: We identified 115 top dynamic genes, of which most were overlapped with the hub genes determined by WGCNA. The expression of several top dynamic genes including Cd63, Saa3, Slc10a1, Nrxn1, Ugt2a3, were verified in vivo. Further, Cluster determinant 63 (Cd63) knockdown in mice treated with ConA showed significantly less liver pathology and inflammation as well as higher survival rates than the corresponding controls. CONCLUSION: We have identified the top dynamic genes related to the process of acute liver injury, and highlighted a targeted strategy for Cd63 might have utility for the protection of hepatocellular damage.

Does Quicker Mean Better? Comparison of Rapid Deployment Versus Conventional Aortic Valve Replacement.

The aim of this meta-analysis was to compare the clinical outcomes in patients who underwent rapid deployment aortic valve replacement (RDAVR) and conventional bio prosthetic aortic valve replacement (CAVR).We performed a literature search by August 2018. The primary outcomes were hospital and 1-year mortality, and the secondary endpoints included the aortic cross-clamp (ACC), cardiopulmonary bypass (CPB) time, and postoperative and valve-related complications.Two randomized controlled trials and 13 propensity score-matched studies were included. There was no difference between RDAVR and CAVR in hospital mortality (2.5% versus 2.1%; risk ratio (RR) 1.16 [95% confidence interval (CI) 0.80-1.68]) or 1-year mortality (2.9% versus 4.1%; RR 0.69 [95% CI 0.34-1.34]). RDAVR significantly reduced the ACC time ( (mean difference (MD) -24.33 [95% CI -28.35 to -20.32]) and CPB time (MD -21.51 [95% CI -22.83 to -20.20]). The pooled analysis showed that RDAVR doubled the occurrence of permanent pacemaker implantation (8.6% versus 4.3%; RR 2.05 [95% CI 1.62-2.60]). Meanwhile, the blood transfusion amount (MD -1.54 [95% CI -2.22 to -0.86]) and postoperative atrial fibrillation (POAF) occurrence (RR 0.83 [95% CI 0.69-0.99]) was reduced. The difference of paravalvular leakage frequency between RDAVR and CAVR was marginal (RR 1.77 [95% CI 1.00-3.17]; P = 0.05). Furthermore, RDAVR was related to larger valves (MD 0.70 cm [95% CI 0.33-1.07]) and lower mean pressure gradients (MD -1.93 mmHg [95% CI -3.58 to -0.28]).The hospital and 1-year survival rates between RDAVR and CAVR are comparable. RDAVR reduces POAF occurrence and blood transfusion but is associated with a higher occurrence of pacemaker implantation.

Next-generation sequencing identified novel Desmoplakin frame-shift variant in patients with Arrhythmogenic cardiomyopathy.

BACKGROUND: Arrhythmogenic cardiomyopathy (AC) is one of the leading causes for sudden cardiac death (SCD). Recent studies have identified mutations in cardiac desmosomes as key players in the pathogenesis of AC. However, the specific etiology in individual families remains largely unknown. METHODS: A 4-generation family presenting with syncope, lethal ventricular arrhythmia and SCD was recruited. Targeted next generation sequencing (NGS) was performed and validated by Sanger sequencing. Plasmids containing the mutation and wild type (WT) were constructed. Real-time PCR, western-blot and immunofluorescence were performed to detect the functional change due to the mutation. RESULTS: The proband, a 56-year-old female, presented with recurrent palpitations and syncope. An ICD was implanted due to her family history of SCD/ aborted SCD. NGS revealed a novel heterozygous frame-shift variant (c.832delG) in Desmoplakin (DSP) among 5 family members. The variant led to frame-shift and premature termination, producing a truncated protein. Cardiac magnetic resonance (CMR) of the family members carrying the same variant shown myocardium thinning and fatty infiltration in the right ventricular, positive bi-ventricular late gadolinium enhancement and severe RV dysfunction, fulfilling the diagnostic criteria of AC. HEK293T cells transfected with mutant plasmids expressed truncated DSP mRNA and protein, upregulation of nuclear junction plakoglobin (JUP) and downregulation of ß-catenin, when compared with WT. CONCLUSION: We infer that the novel c.832delG variant in DSP was associated with AC in this family, likely through Wnt/ß-catenin signaling pathway.

Abdominal Aortic Aneurysm: Roles of Inflammatory Cells.

Abdominal aortic aneurysms (AAAs) are local dilations of infrarenal segment of aortas. Molecular mechanisms underlying the pathogenesis of AAA remain not fully clear. However, inflammation has been considered as a central player in the development of AAA. In the past few decades, studies demonstrated a host of inflammatory cells, including T cells, macrophages, dendritic cells, neutrophils, B cells, and mast cells, etc. infiltrating into aortic walls, which implicated their crucial roles. In addition to direct cell contacts and cytokine or protease secretions, special structures like inflammasomes and neutrophil extracellular traps have been investigated to explore their functions in aneurysm formation. The above-mentioned inflammatory cells and associated structures may initiate and promote AAA expansion. Understanding their impacts and interaction networks formation is meaningful to develop new strategies of screening and pharmacological interventions for AAA. In this review, we aim to discuss the roles and mechanisms of these inflammatory cells in AAA pathogenesis.

Early Aortic Valve Replacement vs. Conservative Management in Asymptomatic Severe Aortic Stenosis Patients With Preserved Ejection Fraction: A Meta-Analysis.

Background: Aortic stenosis (AS) is the most common valvular disease in developed countries. Until now, the specific timing of intervention for asymptomatic patients with severe aortic stenosis and preserved ejection fraction remains controversial. Methods: A systematic search of four databases (Pubmed, Web of science, Cochrane library, Embase) was conducted. Studies of asymptomatic patients with severe AS or very severe AS and preserved left ventricular ejection fraction underwent early aortic valve replacement (AVR) or conservative care were included. The end points included all-cause mortality, cardiac mortality, and non-cardiac mortality. Results: Four eligible studies were identified with a total of 1,249 participants. Compared to conservative management, patients who underwent early AVR were associated with lower all-cause mortality, cardiac mortality, and non-cardiac mortality rate (OR 0.16, 95% CI 0.09-0.31, P < 0.00001; OR 0.12, 95% CI 0.02-0.62, P = 0.01; OR 0.36, 95% CI 0.21-0.63, P = 0.0003, respectively). Conclusions: Early AVR is preferable for asymptomatic severe AS patients with preserved ejection fraction.

Involvement of macrophage-derived exosomes in abdominal aortic aneurysms development.

BACKGROUND AND AIMS: Abdominal aortic aneurysm (AAA) is characterized by infiltration of inflammatory cells, extracellular matrix (ECM) degradation, and dysfunction of vascular smooth muscle cells (VSMCs). Recent studies reported that exosomes mediate intercellular communication and are involved in different diseases. Whether exosomes play a role in AAA is poorly understood. Hence, this study evaluated the function of exosomes in AAA development. METHODS: The presence of exosomes in human and calcium phosphate (CaPO4)-induced AAA tissues was determined by immunofluorescence staining of CD63 and Alix. GW4869, an inhibitor of exosome biogenesis, was intraperitoneally injected into CaPO4-induced AAA tissues to evaluate the effects of exosomal inhibition on AAA development. To explore the underlying mechanisms, the human monocytic cell line THP-1 was differentiated into macrophages, and exosomes were collected from macrophages. VSMCs were treated with macrophage-derived exosomes, and the expression of matrix metalloproteinase-2 (MMP-2) was evaluated. The activation of mitogen-activated protein kinases (MAPKs) pathways was also investigated in vitro and in vivo. RESULTS: Exosomes were detected in the adventitia of aneurysmal tissues obtained from humans and mice. They were mainly expressed in clusters of macrophages. Intraperitoneal injection of GW4869 for two weeks significantly attenuated the progression of CaPO4-induced AAA, preserved elastin integrity and decreased MMP-2 expression. Similarly, administration of GW4869 suppressed the systemic and aneurysmal exosome generation. In vitro, treatment with macrophage-derived exosomes elevated MMP-2 expression in human VSMCs, while pre-treatment with GW4869 abolished these effects. It was also found that JNK and p38 pathways mediated the production of MMP-2 in VSMCs following treatment with macrophage-derived exosomes. CONCLUSIONS: This study suggests that exosomes derived from macrophages are involved in the pathogenesis of AAA. Macrophage-derived exosomes trigger MMP-2 expression in VSMC via JNK and p38 pathways. GW4869 supplementation attenuates CaPO4-induced AAA in mice.