Suppression of autophagy induces senescence in the heart.

Aging is a critical risk factor for heart disease, including ischemic heart disease and heart failure. Cellular senescence, characterized by DNA damage, resistance to apoptosis and the senescence-associated secretory phenotype (SASP), occurs in many cell types, including cardiomyocytes. Senescence precipitates the aging process in surrounding cells and the organ through paracrine mechanisms. Generalized autophagy, which degrades cytosolic materials in a non-selective manner, is decreased during aging in the heart. This decrease causes deterioration of cellular quality control mechanisms, facilitates aging and negatively affects lifespan in animals, including mice. Although suppression of generalized autophagy could promote senescence, it remains unclear whether the suppression of autophagy directly stimulates senescence in cardiomyocytes, which, in turn, promotes myocardial dysfunction in the heart. We addressed this question using mouse models with a loss of autophagy function. Suppression of general autophagy in cardiac-specific Atg7 knockout (Atg7cKO) mice caused accumulation of senescent cardiomyocytes. Induction of senescence via downregulation of Atg7 was also observed in chimeric Atg7 cardiac-specific KO mice and cultured cardiomyocytes in vitro, suggesting that the effect of autophagy suppression upon induction of senescence is cell autonomous. ABT-263, a senolytic agent, reduced the number of senescent myocytes and improved cardiac function in Atg7cKO mice. Suppression of autophagy and induction of senescence were also observed in doxorubicin-treated hearts, where reactivation of autophagy alleviated senescence in cardiomyocytes and cardiac dysfunction. These results suggest that suppression of general autophagy directly induces senescence in cardiomyocytes, which in turn promotes cardiac dysfunction.

Contribution of periodontal health in cardiovascular secondary prevention: Analyses on hospitalized patients in cardiology units.

AIM: To investigate the association between dental health and incident cardiovascular disease (CVD) in secondary prevention setting. MATERIALS AND METHODS: A total of 888 patients with known CVD hospitalized in the cardiology unit were prospectively enrolled. We assessed the association between missing teeth and three variables of periodontitis and major adverse cardiovascular events (MACE), defined as a composite of cardiac death, acute myocardial infarction, stroke and hospital re-admission for congestive heart failure. RESULTS: During a median (Q1, Q3) follow-up of 4.6 (1.4, 6.7) years, an additional missing tooth was associated with a 3% (95% confidence interval [CI]: 1%-5%) higher hazard of MACE (p = .004). Compared with patients with 0 to ≤4 missing teeth, periods free from MACE (95% CI) by 5 years of follow-up were, on average, shorter by 0.17 (-0.04 to 0.37) years, 0.26 (0.04-0.49) years and 0.59 (0.34-0.85) years in patients with 5 to ≤7, 8 to ≤13 and >13 missing teeth, respectively. No significant associations were observed between periodontal measures and MACE incidence. CONCLUSIONS: In hospitalized patients with existing CVD, the total number of missing teeth was associated with incident MACE.

Effect of Periodontal Disease on Long-Term Outcomes After Percutaneous Coronary Intervention for De Novo Coronary Lesions in Non-Smokers.

BACKGROUND: This study aimed to investigate the effect of periodontal disease (PD) on the outcomes of patients with coronary artery disease (CAD) treated with percutaneous coronary intervention (PCI).Methods and Results: The study included 77 consecutive non-smoking patients with de novo coronary lesions treated with a drug-eluting stent (DES). Periodontal measurements, including the community periodontal index (CPI), were performed by independent periodontists. A CPI score of ≥3 was used to define PD. The occurrence of major adverse cardiac events (MACEs), which were defined as a composite of cardiovascular death, non-fatal myocardial infarction, target lesion revascularization, or non-target lesion revascularization, was compared between patients with and without PD. Of the 77 patients, 49 (63.6%) exhibited a CPI score of 3 or 4 and were assigned to the PD group. The remaining 28 patients (36.4%) were assigned to the non-PD group. Baseline clinical characteristics and angiographic findings were comparable between the 2 groups. MACEs occurred in 13 (26.5%) of the PD patients and 2 (7.1%) of the non-PD patients. Kaplan-Meier analysis showed a significantly lower MACE-free survival rate in the PD group than for the non-PD group (P=0.034). CONCLUSIONS: PD at baseline was associated with an increased risk of MACEs in CAD patients who were treated with a DES for de novo coronary lesions.

Suppression of autophagy induces senescence in the heart.

Aging is a critical risk factor for heart disease, including ischemic heart disease and heart failure. Cellular senescence, characterized by DNA damage, resistance to apoptosis and the senescence-associated secretory phenotype (SASP), occurs in many cell types, including cardiomyocytes. Senescence precipitates the aging process in surrounding cells and the organ through paracrine mechanisms. Generalized autophagy, which degrades cytosolic materials in a non-selective manner, is decreased during aging in the heart. This decrease causes deterioration of cellular quality control mechanisms, facilitates aging and negatively affects lifespan in animals, including mice. Although suppression of generalized autophagy could promote senescence, it remains unclear whether the suppression of autophagy directly stimulates senescence in cardiomyocytes, which, in turn, promotes myocardial dysfunction in the heart. We addressed this question using mouse models with a loss of autophagy function. Suppression of general autophagy in cardiac-specific Atg7 knockout ( Atg7 cKO) mice caused accumulation of senescent cardiomyocytes. Induction of senescence via downregulation of Atg7 was also observed in chimeric Atg7 cardiac-specific KO mice and cultured cardiomyocytes in vitro , suggesting that the effect of autophagy suppression upon induction of senescence is cell autonomous. ABT-263, a senolytic agent, reduced the number of senescent myocytes and improved cardiac function in Atg7 cKO mice. Suppression of autophagy and induction of senescence were also observed in doxorubicin-treated hearts, where activation of autophagy alleviated senescence in cardiomyocytes and cardiac dysfunction. These results suggest that suppression of general autophagy directly induces senescence in cardiomyocytes, which in turn promotes cardiac dysfunction.

Porphyromonas gingivalis, a periodontal pathogen, impairs post-infarcted myocardium by inhibiting autophagosome-lysosome fusion.

While several previous studies have indicated the link between periodontal disease (PD) and myocardial infarction (MI), the underlying mechanisms remain unclear. Autophagy, a cellular quality control process that is activated in several diseases, including heart failure, can be suppressed by Porphyromonas gingivalis (P.g.). However, it is uncertain whether autophagy impairment by periodontal pathogens stimulates the development of cardiac dysfunction after MI. Thus, this study aimed to investigate the relationship between PD and the development of MI while focusing on the role of autophagy. Neonatal rat cardiomyocytes (NRCMs) and MI model mice were inoculated with wild-type P.g. or gingipain-deficient P.g. to assess the effect of autophagy inhibition by P.g. Wild-type P.g.-inoculated NRCMs had lower cell viability than those inoculated with gingipain-deficient P.g. This study also revealed that gingipains can cleave vesicle-associated membrane protein 8 (VAMP8), a protein involved in lysosomal sensitive factor attachment protein receptors (SNAREs), at the 47th lysine residue, thereby inhibiting autophagy. Wild-type P.g.-inoculated MI model mice were more susceptible to cardiac rupture, with lower survival rates and autophagy activity than gingipain-deficient P.g.-inoculated MI model mice. After inoculating genetically modified MI model mice (VAMP8-K47A) with wild-type P.g., they exhibited significantly increased autophagy activation compared with the MI model mice inoculated with wild-type P.g., which suppressed cardiac rupture and enhanced overall survival rates. These findings suggest that gingipains, which are virulence factors of P.g., impair the infarcted myocardium by cleaving VAMP8 and disrupting autophagy. This study confirms the strong association between PD and MI and provides new insights into the potential role of autophagy in this relationship.

Endoplasmic Reticulum Selective Autophagy Alleviates Anthracycline-Induced Cardiotoxicity.

Background: The administration of anthracycline drugs induces progressive and dose-related cardiac damage through several cytotoxic mechanisms, including endoplasmic reticulum (ER) stress. The unfolded protein response plays a crucial role for mitigating misfolded protein accumulation induced by excessive ER stress. Objectives: We aimed to clarify whether endoplasmic reticulum-selective autophagy machinery (ER-phagy) serves as an alternative system to protect cardiomyocytes from ER stress caused by anthracycline drugs. Methods: Primary cultured cardiomyocytes, H9c2 cell lines, and cardiomyocyte-specific transgenic mice, all expressing ss-RFP-GFP-KDEL proteins, were used as ER-phagy reporter models. We generated loss-of-function models using RNA interference or gene-trap mutagenesis techniques. We assessed phenotypes and molecular signaling pathways using immunoblotting, quantitative polymerase chain reaction, cell viability assays, immunocytochemical and histopathological analyses, and cardiac ultrasonography. Results: The administration of doxorubicin (Dox) activated ER-phagy in ss-RFP-GFP-KDEL-transduced cardiomyocytes. In addition, Dox-induced cardiomyopathy models of ER-phagy reporter mice showed marked activation of ER-phagy in the myocardium compared to those of saline-treated mice. Quantitative polymerase chain reaction analyses revealed that Dox enhanced the expression of cell-cycle progression gene 1 (CCPG1), one of the ER-phagy receptors, in H9c2 cells. Ablation of CCPG1 in H9c2 cells resulted in the reduced ER-phagy activity, accumulation of proapoptotic proteins, and deterioration of cell survival against Dox administration. CCPG1-hypomorphic mice developed more severe deterioration in systolic function in response to Dox compared to wild-type mice. Conclusions: Our findings highlight a compensatory role of CCPG1-driven ER-phagy in reducing Dox toxicity. With further study, ER-phagy may be a potential therapeutic target to mitigate Dox-induced cardiomyopathy.

Association between periodontal disease and pericardial adipose tissue in patients with cardiovascular disease.

Background: Periodontal disease (PD) is associated with an increased risk of cardiovascular disease (CVD). Pericardial adipose tissue (PAT) is known as a marker of progressive CVD. This study sought to assess the association between PD and PAT in patients with CVD. Methods: We retrospectively investigated 135 patients admitted for CVD who underwent computed tomography coronary angiography (CTCA) and periodontal examinations. Periodontal assessment using the community periodontal index (CPI) was based on the probing pocket depth around teeth. Patients with CPI ≥3 were categorized as having PD. PAT volume was measured with a quantitative semi-automated procedure using CTCA images. Patients were divided into tertiles according to PAT volume. Baseline characteristics and PD findings were compared among the tertiles. Results: Eighty-six patients were diagnosed with PD (63.7 %). Mean PAT volume was 181.4 ml, and patients were categorized as small-PAT (PAT <148.9 ml), intermediate-PAT (148.9 ml ≤ PAT ≤204.6 ml), and large-PAT (PAT >204.6 ml). The prevalence of PD was significantly higher in large-PAT (38/46, 82.6 %) than in small-PAT (18/45, 40.0 %) and intermediate-PAT (30/44, 68.2 %) patients. Multivariate logistic regression analysis showed that body weight, history of hypertension, and the presence of PD were independent predictors for large-PAT (odds ratio [OR]: 1.12, P < 0.001, OR: 3.97, P = 0.017, and OR: 4.18, P = 0.0078, respectively). Conclusion: The presence and severity of PD were significantly correlated with PAT volume, which has been associated with progressive CVD. Further prospective studies are warranted to assess the impact of PD on the onset and outcomes of CVD.

Erratum to "Association between periodontal disease and pericardial adipose tissue in patients with cardiovascular disease" [American Heart Journal Plus: Cardiol. Res. and Pract. Volume 30, 2023, 100,298].

[This corrects the article DOI: 10.1016/j.ahjo.2023.100298.].

The Pathophysiological Significance of "Mitochondrial Ejection" from Cells.

Mitochondria have beneficial effects on cells by producing ATP and contributing to various biosynthetic procedures. On the other hand, dysfunctional mitochondria have detrimental effects on cells by inducing cellular damage, inflammation, and causing apoptosis in response to various stimuli. Therefore, a series of mitochondrial quality control pathways are required for the physiological state of cells to be maintained. Recent research has provided solid evidence to support that mitochondria are ejected from cells for transcellular degradation or transferred to other cells as metabolic support or regulatory messengers. In this review, we summarize the current understanding of the regulation of mitochondrial transmigration across the plasma membranes and discuss the functional significance of this unexpected phenomenon, with an additional focus on the impact on the pathogenesis of cardiovascular diseases. We also provide some perspective concerning the unrevealed mechanisms underlying mitochondrial ejection as well as existing problems and challenges concerning the therapeutic application of mitochondrial ejection.

Periodontitis was associated with worse clinical outcomes after catheter ablation for paroxysmal atrial fibrillation.

Background: Periodontitis (PD), a common chronic inflammatory disease, may be associated with the subsequent development of atrial fibrillation (AF) through a mechanism of systemic inflammation. However, little is known about the impact of PD on the recurrence of atrial fibrillation after catheter ablation (CA). Methods: A total of 132 patients (age 62.2 ± 10.6 years; 72.7% male) who underwent periodontal examinations and the first CA for paroxysmal atrial fibrillation (PAF) were investigated. Clinical periodontal examination was performed by independent trained periodontists, and patients were diagnosed with PD when the maximum periodontal probing depth was equal to or greater than 4 mm and bleeding on probing was evident. Of these, 71 patients (54%) were categorized as those with PD (PD group) and the other 61 (46%) as those without PD (non-PD group). Pulmonary vein isolation was performed in a standard fashion. Results: Kaplan-Meier curve analysis revealed worse atrial arrhythmia recurrence-free survival probabilities after CA for PAF in the PD group than in the non-PD group (64.8% versus 80.3%, respectively; p = 0.024) during a median follow-up period of 3.0 (interquartile range: 1.1-6.4) years. Cox regression analysis revealed PD as a significant predictor of arrhythmia recurrence (hazard ratio: 2.063, 95% confidence interval: 1.018-4.182), after adjusting for age and gender. Conclusion: Periodontitis was independently associated with an increased risk of arrhythmia recurrence after the first CA for PAF. Our results may suggest that the periodontal status is potentially a modifiable determinant of the outcomes after PAF ablation, and further prospective studies are warranted.

Neutrophil extracellular traps-mediated Beclin-1 suppression aggravates atherosclerosis by inhibiting macrophage autophagy.

A growing body of evidence suggests that neutrophil extracellular traps (NETs) critically contribute to the development of atherosclerosis. However, the detailed mechanism of how NETs promote atherogenesis remains unknown. In this study, we explored the role of NETs for promoting atherosclerosis by modulating the activity of autophagy in macrophages. NETs were effectively induced by a nicotine administration to the HL-60 cell-derived neutrophil-like cells. Treatment with NETs markedly suppressed both autophagosome formation and autophagosome-lysosome fusion in 7-ketocholesterol-treated macrophages, which are accompanied by the enhancement of inflammasome activity. NETs upregulate epidermal growth factor receptor (EGFR) activity, which enhances Beclin-1 phosphorylation of the tyrosine residues of Beclin-1 by EGFR, inhibits the PI3 kinase activity of the Beclin1-Vps34 complex, and suppresses autophagosome formation in macrophages. Furthermore, NET-induced activation of EGFR allows Rubicon to increase its expression, thereby suppressing autophagosome-lysosome fusion. In vivo experiments revealed that the suppression of NET formation by ablating peptidyl arginine deiminase-4 in neutrophil leukocytes resulted in the attenuation of atherosclerotic plaques in a nicotine-administered HFD-fed ApoE -/- mice. Taken together, these results suggest that NET-mediated EGFR-Beclin-1 signaling in the macrophages promotes atherogenesis by autophagy inhibition-mediated inflammasome activation.

Plasma apolipopotein C-2 elevation is associated with Takayasu arteritis.

Takayasu arteritis (TAK) is an autoimmune systemic arteritis of unknown etiology. Although a number of investigators have attempted to determine biomarkers for diagnosing TAK, there exist no specific serological markers of this intractable disease. We undertook the exploration of novel serological markers which could be useful for an accurate diagnosis of TAK using an unbiased proteomics approach. The purified plasma samples from untreated patients with TAK and healthy individuals were separated by two-dimensional electrophoresis. The differentially expressed protein spots were detected by gel comparison and identified using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MS). Next, we validated plasma concentrations of identified proteins by enzyme-linked immunosorbent assay (ELISA). Two-dimensional electrophoresis and numerical analysis revealed 19 spots and 3 spot clusters whose sum of the sample averages was ≥ 0.01, and the average concentrations were ≥ 1.5 times in the patient group compared with the control group. Among them, 10 spots and spot clusters that met the condition of the average spot concentration being 2.5 times more than that in the control group were selected. After processing these spots using MS and conducting MS/MS ion search, we identified 10 proteins: apolipoprotein C-2 (ApoC-2), actin, apolipoprotein A-1, complement C3, kininogen-1, vitronectin, α2-macroglobulin, 14-3-3 protein ζ/δ, complement C4, and inter-α-trypsin inhibitor heavy chain H4 isoform 1 precursor. Finally, ELISA demonstrated that plasma ApoC-2 level was significantly elevated in patients with TAK compared with that in healthy individuals. Thus, ApoC-2 would be a promising candidate biomarker for TAK diagnosis.

Rivaroxaban, a Direct Oral Factor Xa Inhibitor, Attenuates Atherosclerosis by Alleviating Factor Xa-PAR2-Mediated Autophagy Suppression.

The authors showed a mechanism for attenuating atherosclerosis by directly administering an oral factor Xa inhibitor (ie, rivaroxaban [RIV]). The autophagy activity of macrophages was significantly suppressed by factor Xa and was alleviated by the administration of RIV. However, factor Xa failed to inhibit 7-ketocholesterol-induced autophagy and inflammasome activation in protease-activated receptor 2 (PAR2) knockout macrophages. The atherosclerotic area of apolipoprotein E knockout mice was significantly reduced by the genetic ablation of PAR2, which was partially reversed by chloroquine. Thus, the authors found that RIV attenuates atherogenesis by inhibiting the factor Xa-PAR2-mediated suppression of macrophage autophagy and abrogating inflammasome activity.

Linagliptin, A Xanthine-Based Dipeptidyl Peptidase-4 Inhibitor, Ameliorates Experimental Autoimmune Myocarditis.

This study sought to show the mechanism of how to ameliorate experimental autoimmune myocarditis (EAM) by administering dipeptidyl peptidase (DPP)-4 inhibitor linagliptin. The number of RAR-related orphan nuclear receptor gamma-positive Th17 cells infiltrated to the EAM myocardium was significantly attenuated by linagliptin treatment. Tandem mass spectrometry-based analysis demonstrated that DPP-4 binds to cathepsin G in EAM hearts, thereby protecting cathepsin G activity through inhibiting SerpinA3N activity. Linagliptin suppresses oxidative stress in EAM hearts as well. Thus, we found that DPP-4 plays a detrimental role in the progression of EAM by interacting with cathepsin G, which, in turn, suppresses SerpinA3N activity.

Synergistic effects of HMG-CoA reductase inhibitor and angiotensin II receptor blocker on load-induced heart failure.

5-Hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins) have beneficial effects in patients with heart failure (HF), regardless of serum cholesterol levels. However, their synergic effects with angiotensin II receptor blocker (ARB) remain to be established. We assessed the existence and potential underlying mechanisms of the effects of combined ARB [losartan (LOS)] and statin [simvastatin (SIM)] on cardiac function in rats and mice with load-induced HF. Salt-loaded Dahl salt-sensitive (DS) rats were treated with vehicle, LOS, SIM, or LOS + SIM for 8 weeks. To mimic load-induced HF in vitro, cultured neonatal rat cardiomyocytes (NRCM) were cyclically stretched. We also investigated the effect of LOS + SIM on pressure overload-induced HF using mice with transverse aortic constriction (TAC). LOS + SIM improved left ventricular (LV) function and reduced LV hypertrophy more than the monotherapies in both salt-loaded DS rats and TAC-operated mice. LV-tissue increases in Rho kinase and matrix metalloproteinase-9 activity were decreased to a greater extent by LOS + SIM than by LOS and SIM monotherapies. Plasma levels of Exp-3174, a LOS metabolite, were higher in LOS + SIM-treated DS rats than in LOS-treated rats. Stretch-induced hypertrophy of NRCM pretreated with SIM + Exp-3174 was significantly attenuated from that with LOS, Exp-3174, SIM, or LOS + SIM. SIM administration significantly enhanced mitophagy in mouse hearts after TAC. However, LOS + SIM reduced mitophagy, and the salutary effect of SIM in mouse hearts after TAC was abolished in AT1R-/- mice. In conclusion, LOS and SIM have beneficial myocardial effects on load-induced HF via differential pleiotropic effects. Thus, combination therapy of these drugs thus has potential as a therapeutic strategy for HF.

Single-Nucleotide Polymorphism of the MLX Gene Is Associated With Takayasu Arteritis.

BACKGROUND: Takayasu arteritis (TAK) is an autoimmune systemic arteritis of unknown pathogenesis. Genome-wide association studies revealed that single-nucleotide polymorphisms in the MLX gene encoding the MLX (Max-like protein X) transcription factor are significantly associated with TAK in Japanese patients. MLX single-nucleotide polymorphism rs665268 is a missense mutation causing the Q139R substitution in the DNA-binding site of MLX. METHODS: To elucidate the hypothesis that the single-nucleotide polymorphism of the MLX gene plays a critical role in the development of TAK, we conducted clinical and laboratory analyses. RESULTS: We show that rs665268 significantly correlated with the severity of TAK, including the number of arterial lesions and morbidity of aortic regurgitation; the latter may be attributed to the fact that MLX mRNA expression was mostly detected in the aortic valve. Furthermore, the Q139R mutation caused structural changes in MLX, which resulted in enhanced formation of a heterodimer with MondoA, upregulation of TXNIP (thioredoxin-interacting protein) expression, and increase in the activity of the NLRP3 (NACHT, LRR, and PYD domains-containing protein 3) inflammasome and cellular oxidative stress. Furthermore, autophagy, which negatively regulates inflammasome activation, was suppressed by the Q139R mutation in MLX. The MLX-Q139R mutant significantly induced macrophage proliferation and macrophage-endothelium interaction, which was abolished by the treatment with SBI-477, an inhibitor of MondoA nuclear translocation. Our findings suggest that the Q139R substitution in MLX plays a crucial role in the pathogenesis of TAK. CONCLUSIONS: MLX-Q139R mutation plays a crucial role in the pathogenesis of TAK through promoting inflammasome formation.