Cigarette smoke induces mitochondrial DNA damage and activates cGAS-STING pathway: application to a biomarker for atherosclerosis.

Cigarette smoking is a major risk factor for atherosclerosis. We previously reported that DNA damage was accumulated in atherosclerotic plaque, and was increased in human mononuclear cells by smoking. As vascular endothelial cells are known to modulate inflammation, we investigated the mechanism by which smoking activates innate immunity in endothelial cells focusing on DNA damage. Furthermore, we sought to characterize the plasma level of cell-free DNA (cfDNA), a result of mitochondrial and/or genomic DNA damage, as a biomarker for atherosclerosis. Cigarette smoke extract (CSE) increased DNA damage in the nucleus and mitochondria in human endothelial cells. Mitochondrial damage induced minority mitochondrial outer membrane permeabilization, which was insufficient for cell death but instead led to nuclear DNA damage. DNA fragments, derived from the nucleus and mitochondria, were accumulated in the cytosol, and caused a persistent increase in IL-6 mRNA expression via the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway. cfDNA, quantified with quantitative PCR in culture medium was increased by CSE. Consistent with in vitro results, plasma mitochondrial cfDNA (mt-cfDNA) and nuclear cfDNA (n-cfDNA) were increased in young healthy smokers compared with age-matched nonsmokers. Additionally, both mt-cfDNA and n-cfDNA were significantly increased in patients with atherosclerosis compared with the normal controls. Our multivariate analysis revealed that only mt-cfDNA predicted the risk of atherosclerosis. In conclusion, accumulated cytosolic DNA caused by cigarette smoke and the resultant activation of the cGAS-STING pathway may be a mechanism of atherosclerosis development. The plasma level of mt-cfDNA, possibly as a result of DNA damage, may be a useful biomarker for atherosclerosis.

Impact of Tweeting Summaries by the Japanese Circulation Society Official Account on Article Viewership　- Pilot Trial.

BACKGROUND: The impact of promotional tweets from the official journal account (forCirculation JournalandCirculation Reports) on article viewership has not been thoroughly evaluated.Methods and Results:We retrospectively collected journal viewership data forCirculation JournalandCirculation Reportsfrom March 2021 to August 2021. We compared viewership between articles with (n=15) and without (n=250) tweets. After 1 : 4 propensity score matching (15 tweeted articles and 60 non-tweeted matched controls), journal viewership metrics within 7 days of the tweeting date (and the hypothetical tweeting date), was larger in tweeted articles than non-tweeted articles (median [interquartile range] Abstract page views 89 [60-104] vs. 18 [8-41]). CONCLUSIONS: This pilot study suggests a positive relationship between journal-posted promotional tweets and article viewership.

DNA Damage Induced by Radiation Exposure from Cardiac Catheterization.

Almost 40% of medical radiation exposure is related to cardiac imaging or intervention. However, the biological effects of low-dose radiation from medical imaging remain largely unknown. This study aimed to evaluate the effects of ionized radiation from cardiac catheterization on genomic DNA integrity and inflammatory cytokines in patients and operators.Peripheral mononuclear cells (MNCs) were isolated from patients (n = 51) and operators (n = 35) before and after coronary angiography and/or percutaneous coronary intervention. The expression of γH2AX, a marker for DNA double-strand breaks, was measured by immunofluorescence. Dicentric chromosomes (DICs), a form of chromosome aberrations, were assayed using a fluorescent in situ hybridization technique.In the patient MNCs, the numbers of γH2AX foci and DICs increased after cardiac catheterization by 4.5 ± 9.4-fold and 71 ± 122%, respectively (P < 0.05 for both). The mRNA expressions of interleukin (IL)-1α, IL-1ß, leukemia inhibitory factor, and caspase-1 were significantly increased by radiation exposure from cardiac catheterization. The increase in IL-1ß was significantly correlated with that of γH2AX, but not with the dose area product. In the operators, neither γH2AX foci nor the DIC level was changed, but IL-1ß mRNA was significantly increased. The protein expression of IκBα was significantly decreased in both groups.DNA damage was increased in the MNCs of patients, but not of operators, who underwent cardiac catheterization. Inflammatory cytokines were increased in both the patients and operators, presumably through NF-κB activation. Further efforts to reduce radiation exposure from cardiac catheterization are necessary for both patients and operators.

Biological Effects of Low-Dose Chest CT on Chromosomal DNA.

Background Although the National Lung Screening Trial reported a significant reduction in lung cancer mortality when low-dose (LD) CT chest examinations are used for a diagnosis, their biologic effects from radiation exposure remain unclear. Purpose To compare LD CT and standard-dose (SD) CT for DNA double-strand breaks and chromosome aberrations (CAs) in peripheral blood lymphocytes. Materials and Methods Between March 2016 and June 2018, 209 participants who were referred to a respiratory surgery department for chest CT studies were prospectively enrolled in this study. Individuals were excluded if they had undergone radiography examinations within the last 3 days or had undergone chemotherapy or radiation therapy. Peripheral blood samples were obtained before and 15 minutes after CT. The number of γ-H2AX foci and unstable CAs in lymphocytes was quantified by immunofluorescent staining of γ-H2AX and by fluorescence in situ hybridization by using peptide nucleic acid probes for centromeres and telomeres, respectively. The Wilcoxon signed rank test was used for statistical analysis. Bonferroni correction was applied for multiple comparisons. Results Of the 209 participants (105 women, 104 men; mean age, 67.0 years ± 11.3 [standard deviation]), 107 underwent chest LD CT and 102 underwent chest SD CT. Sex distribution, age, and body size metrics were similar between the two groups. The median effective dose of LD CT and SD CT was 1.5 and 5.0 mSv, respectively. The number of double-strand breaks and CAs increased after a SD CT examination (γ-H2AX, P < .001; CAs, P = .003); the number of double-strand breaks and CAs before and after LD CT was not different (γ-H2AX, P = .45; CAs, P = .69). Conclusion No effect of low-dose CT on human DNA was detected. In the same setting, DNA double-strand breaks and chromosome aberrations increased after standard-dose CT. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Brenner in this issue.

Recommendations for Maintaining the Cardiovascular Care System Under the Conditions of the COVID-19 Pandemic　- 1st Edition, April 2020.

BACKGROUND: The Japanese Circulation Society proposes recommendations for all healthcare professionals involved in cardiovascular medicine to protect them from infection and ensure that seriously ill patients requiring urgent care receive proper treatment.Methods and Results:Patients are divided into "Positive or suspected coronavirus disease 2019 (COVID-19)" and "All others". Furthermore, tests and treatments are divided into emergency or standby. For each category, we propose recommendations. CONCLUSIONS: To maintain the cardiovascular care system, The Japanese Circulation Society recommends completely preventing nosocomial COVID-19 infections, ensuring adequate PPE necessary for healthcare personnel, and learning and implementing standard precautions.

Coronavirus Disease 2019 (COVID-19) Information for Cardiologists　- Systematic Literature Review and Additional Analysis.

BACKGROUND: Despite the rapidly increasing attention being given to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, more commonly known as coronavirus disease 2019 (COVID-19), the relationship between cardiovascular disease and COVID-19 has not been fully described.Methods and Results:A systematic review was undertaken to summarize the important aspects of COVID-19 for cardiologists. Protection both for patients and healthcare providers, indication for treatments, collaboration with other departments and hospitals, and regular update of information are essentials to front COVID-19 patients. CONCLUSIONS: Because the chief manifestations of COVID-19 infection are respiratory and acute respiratory distress syndrome, cardiologists do not see infected patients directly. Cardiologists need to be better prepared regarding standard disinfection procedures, and be aware of the indications for extracorporeal membrane oxygenation and its use in the critical care setting.

DNA Damage and Senescence-Associated Inflammation in Cardiovascular Disease.

DNA suffers various types of damage even in a normal condition, although they are rapidly repaired by mechanisms called DNA repair. Most progeroid syndromes are caused by genetic defects in specific molecules involved in the DNA repair. DNA damage activates a broad range of signaling pathway that leads to repair, cell cycle arrest, apoptosis and so on, which is called DNA damage response. Recent studies revealed that persistent DNA damage response triggers induction of cell senescence and senescence-associated secretory phenotype (SASP). Here, we review recent advances in the understanding of the molecular mechanisms by which SASP components are regulated, and discuss the possible roles of DNA damage and the DNA damage response, and SASP in the pathogenesis of cardiovascular disease.

DNA damage in lymphocytes induced by cardiac CT and comparison with physical exposure parameters.

OBJECTIVES: To investigate whether physical exposure parameters such as the dose index (CTDI), dose length product (DLP), and size-specific dose estimate (SSDE) are predictive of DNA damage. METHODS: In vitro, we scanned a phantom containing blood samples from five volunteers at CTDI 50, 100, and 150 mGy. One sample was not scanned. We also scanned samples in three different-size phantoms at CTDI 100 mGy. In vivo, we enrolled 45 patients and obtained blood samples before and after cardiac CT. The γ-H2AX foci were counted. RESULTS: In vitro, in the control and at CTDI 50, 100, and 150 mGy, the number of γ-H2AX was 0.94 ± 0.24 (standard error, SE), 1.28 ± 0.30, 1.91 ± 0.47, and 2.16 ± 0.20. At SSDE 180, 156, and 135 mGy, it was 2.41 ± 0.20, 1.91 ± 0.47, and 1.42 ± 0.20 foci/cell. The γ-H2AX foci were positively correlated with the radiation dose and negatively correlated with the body size. In vivo, the γ-H2AX foci were significantly increased after CT (from 1.21 ± 0.19 to 1.92 ± 0.22 foci/cell) and correlated with CTDI, DLP, and SSDE. CONCLUSIONS: DNA damage was induced by cardiac CT. There was a correlation between the physical exposure parameters and γ-H2AX. KEY POINTS: • DNA damage was induced by radiation exposure from cardiac CT. • The γ-H2AX foci number was correlated with the CT radiation dose. • Physical exposure parameters reflect the DNA damage by CT radiation exposure.

Social functioning and socioeconomic changes after introduction of regular dialysis treatment and impact of dialysis modality: a multi-centre survey of Japanese patients.

AIM: Patient socialization and preservation of socioeconomic status are important patient-centred outcomes for those who start dialysis, and retention of employment is a key enabler. This study examined the influence of dialysis inception and modality upon these outcomes in a contemporary Japanese cohort. METHODS: We conducted a survey of prevalent chronic dialysis patients from 5 dialysis centres in Japan. All patients who had been on peritoneal dialysis (PD) since dialysis inception were recruited, and matched with a sample of those on in-centre haemodialysis (ICHD). We assessed patients' current social functioning (Short Form 36 Health Survey), and evaluated changes to patient employment status, annual income, and general health condition from the pre-dialysis period to the current time. RESULTS: A total of 179 patients were studied (102 PD and 77 ICHD). There were no differences in social functioning by modality. Among them, 113 were employed in the pre-dialysis period with no difference by modality. Of these, 22% became unemployed after dialysis inception, with a corresponding decline in average working hours and annual income. The odds of unemployment after dialysis inception were 5.02 fold higher in those on ICHD compared to those on PD, after adjustment for covariates. There were no changes for those who were already unemployed in the pre-dialysis period. CONCLUSIONS: Employment status is significantly hampered by dialysis inception, although PD was associated with superior retention of employment and greater income compared to ICHD. This supports a positive role for PD in preservation of socioeconomic status and potentially other patient-centred outcomes.

Role of DNA damage in cardiovascular disease.

Patients with some progeroid syndromes, such as Werner syndrome, exhibit atherosclerotic cardiovascular disease (CVD) at a young age as a manifestation of premature aging. Recent studies have revealed that most progeroid syndromes are caused by genetic defects in specific molecules involved in the DNA damage response, a cornerstone of genome stability. Ionizing radiation is one of the most potent genotoxic stimuli and causes various kinds of DNA damage. Further, there is increasing evidence that therapeutic radiation treatments can cause cardiovascular complications. Here, we describe the DNA damage and subsequent response, review recent advances in the understanding of the molecular basis of progeroid syndromes (especially those syndromes that involve CVD), review the pathological and epidemiological analysis of radiation-induced CVD, and discuss the possible role of DNA damage and the DNA damage response in the pathogenesis of atherosclerotic CVD.

Cigarette Smoking and Atherosclerotic Cardiovascular Disease.

The detrimental effects of cigarette smoking on cardiovascular health, particularly atherosclerosis and thrombosis, are well established, and more detailed mechanisms continue to emerge. As the fundamental pathophysiology of the adverse effects of smoking, endothelial dysfunction, inflammation, and thrombosis are considered to be particularly important. Cigarette smoke induces endothelial dysfunction, leading to impaired vascular dilation and hemostasis regulation. Factors contributing to endothelial dysfunction include reduced bioavailability of nitric oxide, increased levels of superoxide anion, and endothelin release. Chronic inflammation of the vascular wall is a central pathogenesis of smoking-induced atherosclerosis. Smoking systemically elevates inflammatory markers and induces the expression of adhesion molecules and cytokines in various tissues. Pattern recognition receptors and damage-associated molecular patterns play crucial roles in the mechanism underlying smoking-induced inflammation. Smoking-induced DNA damage and activation of innate immunity, such as the NLRP3 inflammasome, cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, and Toll-like receptor 9, are shown to amplify inflammatory cytokine expression. Cigarette smoke-induced oxidative stress and inflammation influence platelet adhesion, aggregation, and coagulation via adhesion molecule upregulation. Furthermore, it affects the coagulation cascade and fibrinolysis balance, causing thrombus formation. Matrix metalloproteinases contribute to plaque vulnerability and atherothrombotic events. The impact of smoking on inflammatory cells and adhesion molecules further intensifies the risk of atherothrombosis. Collectively, exposure to cigarette smoke exerts profound effects on endothelial function, inflammation, and thrombosis, contributing to the development and progression of atherosclerosis and atherothrombotic cardiovascular diseases. Understanding these intricate mechanisms highlights the urgent need for smoking cessation to protect cardiovascular health. This comprehensive review investigates the multifaceted mechanisms through which smoking contributes to these life-threatening conditions.

Mitochondrial DNA is a key driver in cigarette smoke extract-induced IL-6 expression.

Smoking is an independent risk factor for atherosclerosis, the primary pathogenesis of which is inflammation. We recently reported that cigarette smoke extract (CSE) causes cytosolic and extracellular accumulation of both nuclear (n) and mitochondrial (mt) DNA, which leads to inflammation in human umbilical vein endothelial cells (HUVECs). In this study, we examined whether inflammation induction depends more on cytosolic nDNA or mtDNA, and which chemical constituents of CSE are involved. Acrolein (ACR), methyl vinyl ketone (MVK), and 2-cyclopenten-1-one (CPO) were used in the experiments, as these are the major cytotoxic factors in CSE in various cell types. Stimulation with ACR, MVK, or CPO alone resulted in the accumulation of DNA double-strand breaks (DSBs), but not oxidative DNA damage, accumulation of cytosolic DNA, or increased expression of inflammatory cytokines. Simultaneous administration of all three constituents (ALL) resulted in oxidative DNA damage in both the nucleus and mitochondria, accumulation of DSBs, reduced mitochondrial membrane potential, induction of minority mitochondrial outer membrane permeabilization, accumulation of cytosolic free DNA, and increased expression of inflammatory cytokines such as IL-6 and IL-1α. Treatment with N-acetyl-L-cysteine, a reactive oxygen species scavenger, suppressed oxidative DNA damage and the increased expression of IL-6 and IL-1α induced by ALL or CSE. The ALL- or CSE-induced increase in IL-6 expression, but not that of IL-1α, was suppressed by mtDNA depletion. In conclusion, ACR, MVK, and CPO may strongly contribute to CSE-induced inflammation. More importantly, cytosolic free mtDNA is thought to play an important role in IL-6 expression, a central mediator of inflammation.

Induction of Timp1 in smooth muscle cells during development of abdominal aortic aneurysms.

Abdominal aortic aneurysm (AAA) is known to develop mainly by the increased diameter of aorta through metalloproteinases (MMPs). Although activities of MMPs are tightly regulated by the presence of tissue inhibitor of MMPs (TIMPs) and imbalances between MMPs and TIMPs may serve to fragility of arterial wall, little is known about TIMPs behavior in aneurysmal formation. Here, we utilized a murine experimental AAA model, and found that by immunohistochemical analysis, Timp1 as and Timp1 mRNA levels was also revealed in aortic tissue in AAA by RT-PCR. In cultured vascular smooth muscle cells (SMCs), Tumor Necrosis Factor (TNF)-alpha significantly activated both Mmp9 and Timp1 expression, and they were blocked by Jun kinase inhibitor (SP600125) in a dose-dependent manner. Interestingly, a proteasome inhibitor (MG132), which is known as an agent for inhibition of the nuclear factor-kappa B (NF-kappaB), significantly inhibited the TNF-alpha-induced expression of Timp1, whereas MG132, which also works as an activator of c-Jun/AP-1 pathway, strongly increased Mmp9. Taken together, inflammatory cytokines, including TNF-alpha, may simultaneously induce MMPs and TIMPs for the remodeling of the medial layer, leading to the increased diameter of the aorta, the aneurysm.

Role of DNA damage in the pathogenesis of atherosclerosis.

Atherosclerosis is a cause of coronary artery disease, abdominal aortic aneurysm, and stroke. The pathogenesis underlying atherosclerosis is complex but it is clear that inflammation plays a pivotal role. Inflammation in atherosclerosis is triggered by the recognition of intracellular contents released from damaged cells by pattern recognition receptors, and is therefore sterile and chronic. Because the DNA of these cells is damaged, cellular senescence is also involved in this inflammation. Here, we will discuss the emerging evidence of a relationship between DNA damage and inflammation in the pathogenesis of atherosclerosis, with a focus on intracellular events and cell fates that arise following DNA damage. Recent evidence will lead us to potential therapeutic targets and allow us to explore potential preventative and therapeutic strategies.

The time trend of information seeking behavior about salt reduction using Google Trends: infodemiological study in Japan.

Numerous initiatives have been implemented to reduce salt intake to prevent hypertension and cardiovascular disease. However, salt consumption remains high. No study worldwide has evaluated the public's awareness of salt reduction by analyzing Internet research activity. This research aims to assess trends in the public's attention to salt reduction using Google Trends. We evaluated the relative search volume (RSV) of "salt reduction" in Google Trends from January 1, 2004, to December 31, 2021. Regression coefficients indicated that RSVs increased 0.0091 (95% CI, 0.0085-0.0097, p < 0.001) per year for salt reduction. Among related search terms, search for "salt component," "soy sauce," and "pickled plum" contributed to 9.9 ± 3.2%, 5.8 ± 2.0%, and 3.9 ± 5.5% of total RSVs for salt reduction. Google Trends revealed that the Japanese public's awareness of salt reduction has increased. Related searches might provide insights when people search for salt reduction, which could be helpful for future effective interventions for understanding salt reduction. The trends of Relative search volumes (RSVs) for "salt reduction" and "salt reduction filtered" have significantly increased RSV in 2021 compared to 2004. Google Trends is an effective tool for salt reduction awareness research that provides large amounts of real-time search data.

Angiotensin II Type 1 Receptor Blocker Prevents Abdominal Aortic Aneurysm Progression in Osteoprotegerin-Deficient Mice via Upregulation of Angiotensin (1-7).

Background Angiotensin II type 1 receptor blockers (ARBs) have been shown to limit the growth of abdominal aortic aneurysm (AAA), but their efficacy is controversial. This study aimed to investigate the molecular mechanism underlying the protective effect of ARBs against AAA progression. Methods and Results Olmesartan, an ARB, was administered to wild-type and osteoprotegerin-knockout (Opg-KO) mice starting 2 weeks before direct application of CaCl2 to aortas to induce AAA. The protective effect of olmesartan against AAA in wild-type and Opg-KO mice was compared at 6 weeks after AAA induction. Olmesartan prevented AAA progression in Opg-KO mice, including excessive aortic dilatation and collapse of tunica media, but not in wild-type mice. Deficiency of the Opg gene is known to cause excessive activation of the tumor necrosis factor-related apoptosis-inducing ligand-induced c-Jun N-terminal kinase/matrix metalloproteinase 9 pathway, resulting in prolonged AAA progression. Olmesartan attenuated the upregulation of phosphorylated c-Jun N-terminal kinase and matrix metalloproteinase 9 expression in the aortic wall of Opg-KO mice. In cultured vascular smooth muscle cells, tumor necrosis factor-related apoptosis-inducing ligand-induced c-Jun N-terminal kinase phosphorylation and matrix metalloproteinase 9 expression were inhibited by angiotensin (1-7), the circulating levels of which are increased by ARBs. Furthermore, administering an angiotensin (1-7) antagonist to Opg-KO mice diminished the protective effect of olmesartan against AAA progression. Conclusions Olmesartan prevented AAA progression in Opg-KO mice by upregulating angiotensin (1-7), suggesting that angiotensin (1-7) may be a key factor that mediates the protective effect of ARBs.

Impact of Tweet Content on the Number of Retweets　- "Tweet the Meeting 2022".

Background: Previous research has investigated the effectiveness of the "Tweet the Meeting" campaign, but the relationship between tweet content and the number of retweets has not been fully evaluated. Methods and Results: We analyzed the number of tweets and retweets during the Japanese Circulation Society's 2022 annual meeting. The ambassador group had significantly more session- and symposium-related tweets than the non-ambassador group (P<0.001), associated with the nubmer of retweets. Symposium-related tweets with figures generated more retweets than those without figures (mean [±SD] 3.47±3.31 vs. 2.48±1.94 retweets per tweet, respectively; P=0.001). Conclusions: The study revealed that official meeting-designated Twitter ambassadors disseminate more educational content than non-ambassadors, and generated more retweets.

Factors Influencing Acceptance of the Chairperson Position at Annual Scientific Meetings of the Japanese Circulation Society　- A Questionnaire Survey in Chugoku District.

Background: The Japanese Circulation Society survey revealed that Japanese female cardiologists exhibited a trend to refuse the chairperson position; however, the causal factors remain uncertain. Methods and Results: We distributed a questionnaire survey among chairpersons of the Chugoku regional meeting in November 2022. The rate of chair acceptance at the annual meeting tended to increase as the chairperson's experience grew (first time chairing a meeting, 25.0%; 2-3 times, 33.3%; 4-5 times, 53.8%; ≥6 times, 70.0%; P=0.021). Conclusions: Providing inexperienced members with the chance to perform the role of chairperson will lead to them accepting to chair annual meetings.