Sex-Specific Disparities in Clinical Outcomes After Transcatheter Aortic Valve Replacement Among Different Racial Populations.

Background: Sex-related disparities in clinical outcomes following transcatheter aortic valve replacement (TAVR) and the impact of sex on clinical outcomes after TAVR among different racial groups are undetermined. Objectives: This study assessed whether sex-specific differences in baseline clinical and anatomical characteristics affect clinical outcomes after TAVR and investigated the impact of sex on clinical outcomes among different racial groups. Methods: The TP-TAVR (Trans-Pacific TAVR) registry is a multinational cohort study of patients with severe aortic stenosis who underwent TAVR at 2 major centers in the United States and 1 major center in South Korea. The primary outcome was a composite of death from any cause, stroke, or rehospitalization after 1 year. Results: The incidence of the primary composite outcome was not significantly different between sexes (27.9% in men vs 28% in women; adjusted HR: 0.97; 95% CI: 0.79-1.20). This pattern was consistent in Asian (23.5% vs 23.3%; adjusted HR: 0.99; 95% CI: 0.69-1.41) and non-Asian (30.8% vs 31.6%; adjusted HR: 0.95; 95% CI: 0.72-1.24) cohorts, without a significant interaction between sex and racial group (P for interaction = 0.74). The adjusted risk for all-cause mortality was similar between sexes, regardless of racial group. However, the adjusted risk of stroke was significantly lower in male patients than in female patients, which was more prominent in the non-Asian cohort. Conclusions: Despite significantly different baseline and procedural characteristics, there were no sex-specific differences in the adjusted 1-year rates of primary composite outcomes and all-cause mortality, regardless of different racial groups. (Transpacific TAVR registry [TP-TAVR]; NCT03826264).

Air Pollution, Built Environment, and Early Cardiovascular Disease.

As the world's population becomes increasingly urbanized, there is growing concern about the impact of urban environments on cardiovascular health. Urban residents are exposed to a variety of adverse environmental exposures throughout their lives, including air pollution, built environment, and lack of green space, which may contribute to the development of early cardiovascular disease and related risk factors. While epidemiological studies have examined the role of a few environmental factors with early cardiovascular disease, the relationship with the broader environment remains poorly defined. In this article, we provide a brief overview of studies that have examined the impact of the environment including the built physical environment, discuss current challenges in the field, and suggest potential directions for future research. Additionally, we highlight the clinical implications of these findings and propose multilevel interventions to promote cardiovascular health among children and young adults.

Race-Specific Impact of Conventional Surgical Risk Score on 1-Year Mortality After Transcatheter Aortic Valve Replacement.

Background: Interracial differences in the distribution and prognostic value of conventional Society of Thoracic Surgeons (STS) score on long-term mortality after transcatheter aortic valve replacement (TAVR) are uncertain. Objectives: This study aims to compare the impact of STS scores on clinical outcomes at 1-year after TAVR between Asian and non-Asian populations. Methods: We used the Trans-Pacific TAVR (TP-TAVR) registry, a multinational multicenter, observational registry involving patients undergoing TAVR at 2 major centers in the United States and 1 major center in Korea. Patients were classified into 3 groups (low, intermediate, and high-risk) according to the STS score and compared between STS risk groups and race. The primary outcome was all-cause mortality at 1-year. Results: Among 1,412 patients, 581 were Asian and 831 were non-Asian. The distribution of the STS risk score group was different between Asian and non-Asian groups (62.5% low-, 29.8% intermediate-, and 7.7% high-risk in Asian vs 40.6% low-, 39.1% intermediate-, and 20.3% high-risk in non-Asian). In the Asian population, the all-cause mortality at 1-year was substantially higher in the high-risk STS group than in the low- and intermediate-risk groups (3.6% low-risk, 8.7% intermediate-risk, and 24.4% high-risk; log-rank P < 0.001), which was primarily driven by noncardiac mortality. In the non-Asian group, there was a proportional increase in all-cause mortality at 1-year according to the STS risk category (5.3% low-risk, 12.6% intermediate-risk, and 17.8% high-risk; log-rank P < 0.001). Conclusions: In this multiracial registry of patients with severe aortic stenosis who underwent TAVR, we identified a differential proportion and prognostic impact of STS score on 1-year mortality between Asian and non-Asian patients (TP-TAVR [Transpacific TAVR Registry]; NCT03826264).

Modulation of mouse laryngeal inflammatory and immune cell responses by low and high doses of mainstream cigarette smoke.

Cigarette smoking is a major risk factor for laryngeal diseases. Despite well-documented cigarette smoke (CS) induced laryngeal histopathological changes, the underlying immunopathological mechanisms remain largely unexplored. The goal of this study was to evaluate inflammatory and immune cell responses in a CS-exposed larynx. Specifically, we used a 4-week subacute whole-body CS inhalation mouse model to assess these responses in the laryngeal mucosa upon exposure to low (LD; 1 h/day) and high dose (HD; 4 h/day) CS. Laryngeal tissues were harvested and evaluated using a 254-plex NanoString inflammation panel and neutrophil/macrophage/T-cell immunohistochemistry (IHC). NanoString global and differential gene expression analysis revealed a unique expression profile only in the HD group, with 26 significant differentially expressed genes (DEGs). StringDB KEGG pathway enrichment analysis revealed the involvement of these DEGs with pro-inflammatory pathways including TNF/TNFα and IL-17. Furthermore, inflammatory responses remained inhibited in conjunction with predicted activated states of anti-inflammatory regulators like PPARγ and NFE2L2 upon Ingenuity Pathway Analysis (IPA). Subglottic T-cell levels remained significantly inhibited as corroborated by IPA predictions. Overall, our key findings are consistent with HD exposures being anti-inflammatory and immunosuppressive. Furthermore, the identification of important regulatory genes and enriched pathways may help improve clinical interventions for CS-induced laryngeal diseases.

Smad3 regulates smooth muscle cell fate and mediates adverse remodeling and calcification of the atherosclerotic plaque.

Atherosclerotic plaques consist mostly of smooth muscle cells (SMC), and genes that influence SMC phenotype can modulate coronary artery disease (CAD) risk. Allelic variation at 15q22.33 has been identified by genome-wide association studies to modify the risk of CAD and is associated with the expression of SMAD3 in SMC. However, the mechanism by which this gene modifies CAD risk remains poorly understood. Here we show that SMC-specific deletion of Smad3 in a murine atherosclerosis model resulted in greater plaque burden, more outward remodelling and increased vascular calcification. Single-cell transcriptomic analyses revealed that loss of Smad3 altered SMC transition cell state toward two fates: a SMC phenotype that governs both vascular remodelling and recruitment of inflammatory cells, as well as a chondromyocyte fate. Together, the findings reveal that Smad3 expression in SMC inhibits the emergence of specific SMC phenotypic transition cells that mediate adverse plaque features, including outward remodelling, monocyte recruitment, and vascular calcification.

Inter-racial differences in patients undergoing transcatheter aortic valve implantation.

OBJECTIVE: Little information exists about inter-racial differences in patients with aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI). We investigated whether differences in baseline characteristics between Asian and non-Asian population may contribute to disparities in clinical outcomes after TAVI. METHODS: We performed a registry-based, multinational cohort study of patients with severe AS who underwent TAVI at two centres in the USA and one centre in South Korea. The primary outcome was a composite of death, stroke or rehospitalisation at 1 year. RESULTS: Of 1412 patients, 581 patients were Asian and 831 were non-Asian (87.5% white, 1.7% black, 6.1% Hispanic or 4.7% others). There were substantial differences in baseline characteristics between two racial groups. The primary composite outcome was significantly lower in the Asian group than in the non-Asian group (26.0% vs 35.0%; HR 0.73; 95% CI 0.59 to 0.89; p=0.003). However, after adjustment of baseline covariates, the risk of primary composite outcome was not significantly different (HR 0.79; 95% CI 0.60 to 1.03; p=0.08). The all-cause mortality at 1 year was significantly lower in the Asian group than the non-Asian group (7.4% vs 12.5%; HR 0.60; 95% CI 0.41 to 0.88; p=0.009). After multivariable adjustment, the risk of all-cause mortality was also similar (HR 1.17; 95% CI 0.73 to 1.88; p=0.52). CONCLUSIONS: There were significant differences in baseline and procedural factors among Asian and non-Asian patients who underwent TAVI. Observed inter-racial differences in clinical outcomes were largely explained by baseline differences in clinical, anatomical and procedural factors. TRIAL REGISTRATION NUMBER: NCT03826264 (https://wwwclinicaltrialsgov).

Distance between valvular leaflet and coronary ostium predicting risk of coronary obstruction during TAVR.

BACKGROUND: The aim of this study was to evaluate the role of the distance between the aortic valve in projected position to the coronary ostium to determine risk of coronary artery obstruction after transcatheter aortic valve replacement (TAVR). METHODS: An Expected Leaflet-to-ostium Distance (ELOD) was obtained on pre-TAVR planning computed tomography by subtracting leaflet thickness and the distances from the center to the annular rim at annulus level and from the center to the coronary ostium at mid-ostial level. Variables were compared between patients with and without coronary obstruction and the level of association between variables was assessed using log odds ratio (OR). RESULTS: A total of 177 patients with 353 coronary arteries was analyzed. Mean annulus diameters (22.8 ± 2.8 mm and 23.4 ± 1.0 mm, p > 0.05) and mean sinus of Valsalva (SOV) diameters (31.2 ± 3.6 mm and 31.9 ± 3.6 mm, p > 0.05) were similar between patients with lower and higher coronary heights, respectively. There were three coronary obstruction cases. ELOD ≤ 2 mm in combination with leaflet length longer than mid-ostial height allowed for discrimination of cases with and without coronary obstruction. There was a significant association between coronary obstruction event and ELOD ≤ 2 mm (log OR = 6.180, p < 0.001). CONCLUSIONS: Our study showed that a combination of ELOD < 2 mm and a longer leaflet length than mid-ostial height may be associated with increased risk for coronary obstruction during TAVR.

Racial Differences in the Incidence and Impact of Prosthesis-Patient Mismatch After Transcatheter Aortic Valve Replacement.

OBJECTIVES: The aim of this study was to compare the incidence and prognostic significance of prosthesis-patient mismatch (PPM) after transcatheter aortic valve replacement (TAVR) according to racial groups. BACKGROUND: PPM after TAVR may be of more concern in Asian populations considering their relatively small annular and valve sizes compared with Western populations. METHODS: TP-TAVR (Transpacific TAVR Registry) was an international multicenter cohort study of patients with severe aortic stenosis who underwent TAVR in the United States and South Korea from January 2015 to November 2019. PPM was defined as moderate (0.65-0.85 cm2/m2) or severe (<0.65 cm2/m2) at the indexed effective orifice area. The primary outcome was a composite of death, stroke, or rehospitalization at 1 year. RESULTS: Among 1,101 eligible patients (533 Asian and 569 non-Asian), the incidence of PPM was significantly lower in the Asian population (33.6%; moderate, 26.5%; severe, 7.1%) than in the non-Asian population (54.5%; moderate, 29.8%; severe, 24.7%). The 1-year rate of the primary outcome was similar between the PPM and non-PPM groups (27.5% vs 28.1%; P = 0.69); this pattern was consistent between Asian (25.4% vs 25.2%; P = 0.31) and non-Asian (28.7% vs 32.1%; P = 0.97) patients. After multivariable adjustment, the risk for the primary outcome did not significantly differ between the PPM and non-PPM groups in the overall population (HR: 0.95; 95% CI: 0.74-1.21), in Asian patients (HR: 1.07; 95% CI: 0.74-1.55), and in non-Asian patients (HR: 0.86; 95% CI: 0.63-1.19). CONCLUSIONS: In this study of patients with severe aortic stenosis who underwent TAVR, the incidence of PPM was significantly lower in Asian patients than in non-Asian patients. The 1-year risk for the primary composite outcome was similar between the PPM and non-PPM groups regardless of racial group. (Transpacific TAVR Registry [TP-TAVR]; NCT03826264).

CTA pulmonary artery enlargement in patients with severe aortic stenosis: Prognostic impact after TAVR.

BACKGROUND: Identifying high-risk patients who will not derive substantial survival benefit from TAVR remains challenging. Pulmonary hypertension is a known predictor of poor outcome in patients undergoing TAVR and correlates strongly with pulmonary artery (PA) enlargement on CTA. We sought to evaluate whether PA enlargement, measured on pre-procedural computed tomography angiography (CTA), is associated with 1-year mortality in patients undergoing TAVR. METHODS: We retrospectively included 402 patients undergoing TAVR between July 2012 and March 2016. Clinical parameters, including Society of Thoracic Surgeons (STS) score and right ventricular systolic pressure (RVSP) estimated by transthoracic echocardiography were reviewed. PA dimensions were measured on pre-procedural CTAs. Association between PA enlargement and 1-year mortality was analyzed. Kaplan-Meier and Cox proportional hazards regression analyses were performed. RESULTS: The median follow-up time was 433 (interquartiles 339-797) days. A total of 56/402 (14%) patients died within 1 year after TAVR. Main PA area (area-MPA) was independently associated with 1-year mortality (hazard ratio per standard deviation equal to 2.04 [95%-confidence interval (CI) 1.48-2.76], p â€‹< â€‹0.001). Area under the curve (95%-CI) of the clinical multivariable model including STS-score and RVSP increased slightly from 0.67 (0.59-0.75) to 0.72 (0.72-0.89), p â€‹= â€‹0.346 by adding area-MPA. Although the AUC increased, differences were not significant (p â€‹= â€‹0.346). Kaplan-Meier analysis showed that mortality was significantly higher in patients with a pre-procedural non-indexed area-MPA of ≥7.40 â€‹cm2 compared to patients with a smaller area-MPA (mortality 23% vs. 9%; p â€‹< â€‹0.001). CONCLUSIONS: Enlargement of MPA on pre-procedural CTA is independently associated with 1-year mortality after TAVR.

Immune biomarkers link air pollution exposure to blood pressure in adolescents.

BACKGROUND: Childhood exposure to air pollution contributes to cardiovascular disease in adulthood. Immune and oxidative stress disturbances might mediate the effects of air pollution on the cardiovascular system, but the underlying mechanisms are poorly understood in adolescents. Therefore, we aimed to identify immune biomarkers linking air pollution exposure and blood pressure levels in adolescents. METHODS: We randomly recruited 100 adolescents (mean age, 16 years) from Fresno, California. Using central-site data, spatial-temporal modeling, and distance weighting exposures to the participant's home, we estimated average pollutant levels [particulate matter (PM), polyaromatic hydrocarbons (PAH), ozone (O3), carbon monoxide (CO) and nitrogen oxides (NOx)]. We collected blood samples and vital signs on health visits. Using proteomic platforms, we quantitated markers of inflammation, oxidative stress, coagulation, and endothelial function. Immune cellular characterization was performed via mass cytometry (CyTOF). We investigated associations between pollutant levels, cytokines, immune cell types, and blood pressure (BP) using partial least squares (PLS) and linear regression, while adjusting for important confounders. RESULTS: Using PLS, biomarkers explaining most of the variance in air pollution exposure included markers of oxidative stress (GDF-15 and myeloperoxidase), acute inflammation (C-reactive protein), hemostasis (ADAMTS, D-dimer) and immune cell types such as monocytes. Most of these biomarkers were independently associated with the air pollution levels in fully adjusted regression models. In CyTOF analyses, monocytes were enriched in participants with the highest versus the lowest PM2.5 exposure. In both PLS and linear regression, diastolic BP was independently associated with PM2.5, NO, NO2, CO and PAH456 pollution levels (P ≤ 0.009). Moreover, monocyte levels were independently related to both air pollution and diastolic BP levels (P ≤ 0.010). In in vitro cell assays, plasma of participants with high PM2.5 exposure induced endothelial dysfunction as evaluated by eNOS and ICAM-1 expression and tube formation. CONCLUSIONS: For the first time in adolescents, we found that ambient air pollution levels were associated with oxidative stress, acute inflammation, altered hemostasis, endothelial dysfunction, monocyte enrichment and diastolic blood pressure. Our findings provide new insights on pollution-related immunological and cardiovascular disturbances and advocate preventative measures of air pollution exposure.

Molecular mechanisms of coronary disease revealed using quantitative trait loci for TCF21 binding, chromatin accessibility, and chromosomal looping.

BACKGROUND: To investigate the epigenetic and transcriptional mechanisms of coronary artery disease (CAD) risk, as well as the functional regulation of chromatin structure and function, we create a catalog of genetic variants associated with three stages of transcriptional cis-regulation in primary human coronary artery vascular smooth muscle cells (HCASMCs). RESULTS: We use a pooling approach with HCASMC lines to map regulatory variants that mediate binding of the CAD-associated transcription factor TCF21 with ChIPseq studies (bQTLs), variants that regulate chromatin accessibility with ATACseq studies (caQTLs), and chromosomal looping with Hi-C methods (clQTLs). We examine the overlap of these QTLs and their relationship to smooth muscle-specific genes and transcription factors. Further, we use multiple analyses to show that these QTLs are highly associated with CAD GWAS loci and correlate to lead SNPs where they show allelic effects. By utilizing genome editing, we verify that identified functional variants can regulate both chromatin accessibility and chromosomal looping, providing new insights into functional mechanisms regulating chromatin state and chromosomal structure. Finally, we directly link the disease-associated TGFB1-SMAD3 pathway to the CAD-associated FN1 gene through a response QTL that modulates both chromatin accessibility and chromosomal looping. CONCLUSIONS: Together, these studies represent the most thorough mapping of multiple QTL types in a highly disease-relevant primary cultured cell type and provide novel insights into their functional overlap and mechanisms that underlie these genomic features and their relationship to disease risk.

Quantifying the Influence of Wedge Pressure, Age, and Heart Rate on the Systolic Thresholds for Detection of Pulmonary Hypertension.

Background The strong linear relation between mean (MPAP) and systolic (SPAP) pulmonary arterial pressure (eg, SPAP=1.62×MPAP) has been mainly reported in precapillary pulmonary hypertension. This study sought to quantify the influence of pulmonary arterial wedge pressure (PAWP), heart rate, and age on the MPAP-SPAP relation. Methods and Results An allometric equation relating invasive MPAP and SPAP was developed in 1135 patients with pulmonary arterial hypertension, advanced lung disease, chronic thromboembolic pulmonary hypertension, or left heart failure. The equation was validated in 60 885 patients from the United Network for Organ Sharing (UNOS) database referred for heart and/or lung transplant. The MPAP/SPAP longitudinal stability was assessed in pulmonary arterial hypertension with repeated right heart catheterization. The equation obtained was SPAP=1.39×MPAP×PAWP-0.07×(60/heart rate)0.12×age0.08 (P<0.001). It was validated in the UNOS cohort (R2=0.93, P<0.001), regardless of the type of organ(s) patients were listed for (mean bias [-1.96 SD; 1.96 SD] was 0.94 [-8.00; 9.88] for heart, 1.34 [-7.81; 10.49] for lung and 0.25 [-16.74; 17.24] mm Hg for heart-lung recipients). Thresholds of SPAP for MPAP=25 and 20 mm Hg were lower in patients with higher PAWP (37.2 and 29.8 mm Hg) than in those with pulmonary arterial hypertension (40.1 and 32.0 mm Hg). In 186 patients with pulmonary arterial hypertension, the predicted MPAP/SPAP was stable over time (0.63±0.03 at baseline and follow-up catheterization, P=0.43). Conclusions This study quantifies the impact of PAWP, and to a lesser extent heart rate and age, on the MPAP-SPAP relation, supporting lower SPAP thresholds for pulmonary hypertension diagnosis in patients with higher PAWP for echocardiography-based epidemiological studies.

Environment-Sensing Aryl Hydrocarbon Receptor Inhibits the Chondrogenic Fate of Modulated Smooth Muscle Cells in Atherosclerotic Lesions.

BACKGROUND: Smooth muscle cells (SMC) play a critical role in atherosclerosis. The Aryl hydrocarbon receptor (AHR) is an environment-sensing transcription factor that contributes to vascular development, and has been implicated in coronary artery disease risk. We hypothesized that AHR can affect atherosclerosis by regulating phenotypic modulation of SMC. METHODS: We combined RNA-sequencing, chromatin immunoprecipitation followed by sequencing, assay for transposase-accessible chromatin using sequencing, and in vitro assays in human coronary artery SMCs, with single-cell RNA-sequencing, histology, and RNAscope in an SMC-specific lineage-tracing Ahr knockout mouse model of atherosclerosis to better understand the role of AHR in vascular disease. RESULTS: Genomic studies coupled with functional assays in cultured human coronary artery SMCs revealed that AHR modulates the human coronary artery SMC phenotype and suppresses ossification in these cells. Lineage-tracing and activity-tracing studies in the mouse aortic sinus showed that the Ahr pathway is active in modulated SMCs in the atherosclerotic lesion cap. Furthermore, single-cell RNA-sequencing studies of the SMC-specific Ahr knockout mice showed a significant increase in the proportion of modulated SMCs expressing chondrocyte markers such as Col2a1 and Alpl, which localized to the lesion neointima. These cells, which we term "chondromyocytes," were also identified in the neointima of human coronary arteries. In histological analyses, these changes manifested as larger lesion size, increased lineage-traced SMC participation in the lesion, decreased lineage-traced SMCs in the lesion cap, and increased alkaline phosphatase activity in lesions in the Ahr knockout in comparison with wild-type mice. We propose that AHR is likely protective based on these data and inference from human genetic analyses. CONCLUSIONS: Overall, we conclude that AHR promotes the maintenance of lesion cap integrity and diminishes the disease-related SMC-to-chondromyocyte transition in atherosclerotic tissues.

Cumulative Lifetime Burden of Cardiovascular Disease From Early Exposure to Air Pollution.

The disease burden associated with air pollution continues to grow. The World Health Organization (WHO) estimates ≈7 million people worldwide die yearly from exposure to polluted air, half of which-3.3 million-are attributable to cardiovascular disease (CVD), greater than from major modifiable CVD risks including smoking, hypertension, hyperlipidemia, and diabetes mellitus. This serious and growing health threat is attributed to increasing urbanization of the world's populations with consequent exposure to polluted air. Especially vulnerable are the elderly, patients with pre-existing CVD, and children. The cumulative lifetime burden in children is particularly of concern because their rapidly developing cardiopulmonary systems are more susceptible to damage and they spend more time outdoors and therefore inhale more pollutants. World Health Organization estimates that 93% of the world's children aged <15 years-1.8 billion children-breathe air that puts their health and development at risk. Here, we present growing scientific evidence, including from our own group, that chronic exposure to air pollution early in life is directly linked to development of major CVD risks, including obesity, hypertension, and metabolic disorders. In this review, we surveyed the literature for current knowledge of how pollution exposure early in life adversely impacts cardiovascular phenotypes, and lay the foundation for early intervention and other strategies that can help prevent this damage. We also discuss the need for better guidelines and additional research to validate exposure metrics and interventions that will ultimately help healthcare providers reduce the growing burden of CVD from pollution.

Spontaneous Coronary Artery Dissection and ST-Segment Elevation Myocardial Infarction in an Anomalous LAD Artery.

Spontaneous coronary artery dissection is an increasingly recognized cause of acute coronary syndrome in younger patients. Management remains challenging and involves weighing the benefits of revascularization with the potential to worsen the dissection. We present a case of spontaneous coronary artery dissection with the superimposed complexity of an anomalous intramural coronary artery. (Level of Difficulty: Intermediate.).

Coronary Disease-Associated Gene TCF21 Inhibits Smooth Muscle Cell Differentiation by Blocking the Myocardin-Serum Response Factor Pathway.

RATIONALE: The gene encoding TCF21 (transcription factor 21) has been linked to coronary artery disease risk by human genome-wide association studies in multiple racial ethnic groups. In murine models, Tcf21 is required for phenotypic modulation of smooth muscle cells (SMCs) in atherosclerotic tissues and promotes a fibroblast phenotype in these cells. In humans, TCF21 expression inhibits risk for coronary artery disease. The molecular mechanism by which TCF21 regulates SMC phenotype is not known. OBJECTIVE: To better understand how TCF21 affects the SMC phenotype, we sought to investigate the possible mechanisms by which it regulates the lineage determining MYOCD (myocardin)-SRF (serum response factor) pathway. METHODS AND RESULTS: Modulation of TCF21 expression in human coronary artery SMC revealed that TCF21 suppresses a broad range of SMC markers, as well as key SMC transcription factors MYOCD and SRF, at the RNA and protein level. We conducted chromatin immunoprecipitation-sequencing to map SRF-binding sites in human coronary artery SMC, showing that binding is colocalized in the genome with TCF21, including at a novel enhancer in the SRF gene, and at the MYOCD gene promoter. In vitro genome editing indicated that the SRF enhancer CArG box regulates transcription of the SRF gene, and mutation of this conserved motif in the orthologous mouse SRF enhancer revealed decreased SRF expression in aorta and heart tissues. Direct TCF21 binding and transcriptional inhibition at colocalized sites were established by reporter gene transfection assays. Chromatin immunoprecipitation and protein coimmunoprecipitation studies provided evidence that TCF21 blocks MYOCD and SRF association by direct TCF21-MYOCD interaction. CONCLUSIONS: These data indicate that TCF21 antagonizes the MYOCD-SRF pathway through multiple mechanisms, further establishing a role for this coronary artery disease-associated gene in fundamental SMC processes and indicating the importance of smooth muscle response to vascular stress and phenotypic modulation of this cell type in coronary artery disease risk.

PM2.5 concentration in the ambient air is a risk factor for the development of high-risk coronary plaques.

AIMS: We aimed to investigate whether long-term exposure to particulate matter with an aerodynamic diameter <2.5 µm (PM2.5) in the ambient air is related to the development or growth of coronary plaques. METHODS AND RESULTS: This study involved 364 residents of Seoul, Korea, who underwent serial coronary computed tomographic angiography (CCTA) at an interval of ≥2 years. Each participant's average concentration of residential PM2.5 between the two CCTAs was calculated. Primary endpoint was the development of high-risk plaque (HRP), defined as a plaque with low attenuation, spotty calcium, and positive remodelling. Secondary endpoints were the volume increase of total plaque and its component volume. Among those without HRP at baseline (n = 341), 20 patients developed HRP at follow-up CCTA, the residential PM2.5 concentration of which was significantly higher than those without HRP at follow-up (25.8 ± 2.0 vs. 25.0 ± 1.7 µg/m3 for patients with newly developed HRP vs. patients without HRP at follow-up; P = 0.047). An increase in PM2.5 concentration was associated with increased incidence of HRP at follow-up [adjusted hazard ratio (aHR) 1.62, 95% confidence interval (CI) 1.22-2.15, P < 0.001]. In a secondary analysis, the PM2.5 concentration was associated with an increased risk of the formation of either fibrofatty or necrotic core component in newly developed plaques (aHR 1.41, 95% CI 1.23-1.61, P < 0.001), and with a higher risk of total plaque volume progression in the pre-existing plaques (aHR 1.14, 95% CI 1.05-1.23, P = 0.002). CONCLUSION: Exposure to higher concentration of PM2.5 in the ambient air is significantly associated with the development of high-risk coronary plaques.

TCF21 and AP-1 interact through epigenetic modifications to regulate coronary artery disease gene expression.

BACKGROUND: Genome-wide association studies have identified over 160 loci that are associated with coronary artery disease. As with other complex human diseases, risk in coronary disease loci is determined primarily by altered expression of the causal gene, due to variation in binding of transcription factors and chromatin-modifying proteins that directly regulate the transcriptional apparatus. We have previously identified a coronary disease network downstream of the disease-associated transcription factor TCF21, and in work reported here extends these studies to investigate the mechanisms by which it interacts with the AP-1 transcription complex to regulate local epigenetic effects in these downstream coronary disease loci. METHODS: Genomic studies, including chromatin immunoprecipitation sequencing, RNA sequencing, and protein-protein interaction studies, were performed in human coronary artery smooth muscle cells. RESULTS: We show here that TCF21 and JUN regulate expression of two presumptive causal coronary disease genes, SMAD3 and CDKN2B-AS1, in part by interactions with histone deacetylases and acetyltransferases. Genome-wide TCF21 and JUN binding is jointly localized and particularly enriched in coronary disease loci where they broadly modulate H3K27Ac and chromatin state changes linked to disease-related processes in vascular cells. Heterozygosity at coronary disease causal variation, or genome editing of these variants, is associated with decreased binding of both JUN and TCF21 and loss of expression in cis, supporting a transcriptional mechanism for disease risk. CONCLUSIONS: These data show that the known chromatin remodeling and pioneer functions of AP-1 are a pervasive aspect of epigenetic control of transcription, and thus, the risk in coronary disease-associated loci, and that interaction of AP-1 with TCF21 to control epigenetic features, contributes to the genetic risk in loci where they co-localize.