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Researchers in the Medical Sciences Division have established a key cause of micro blood vessels constricting during surgery to reopen a blocked artery, and identified a potential therapeutic target to block the mechanism behind it.
[Prospective association between liver biomarkers and mortality risk in Chinese middle-aged and elderly populations].
Objective: To analyze the prospective associations between liver biomarkers and mortality among Chinese middle-aged and elderly populations and to evaluate the mortality risk predictive value. Methods: A total of 22 758 participants from the 3rd resurvey of the China Kadoorie Biobank were included. Cox proportional hazard models were used to analyze the prospective associations of 5 liver biomarkers with mortality. These liver biomarkers included two liver imaging biomarkers (liver fat attenuation parameter, liver stiffness measurement) and three serum liver enzyme biomarkers [gamma-glutamyl transferase (GGT), ALT, and AST]. Restricted cubic spline was used to assess the nonlinear associations between biomarkers and mortality. The area used the receiver operating characteristic curve (AUC) to evaluate the predictive ability of the models after incorporating liver biomarkers into traditional prediction models for mortality. Results: The mean age of the participants was (65.2±9.1) years, with a median follow-up of 1.5 years, during which 307 deaths occurred. Compared to individuals without hepatic steatosis, those with severe hepatic steatosis had a 79% higher risk of mortality, with a HR of 1.79 (95%CI: 1.06-3.03). Compared to individuals without hepatic fibrosis, those with advanced fibrosis and cirrhosis had higher mortality risks of 48% and 91%, respectively (both P<0.05). For each standard deviation increase in GGT, the mortality risk increased by 10% (HR=1.10, 95%CI: 1.05-1.15), with the positive association plateauing at higher GGT levels. AST exhibited a U-shaped association with mortality risk. The AUC of the prediction model adding liver biomarkers into traditional prediction factors was 0.718 (95%CI: 0.679-0.757), with an increase of 0.030 (P<0.001) compared with the traditional model. Conclusions: Severe hepatic steatosis, higher levels of hepatic fibrosis, and elevated GGT levels are significantly associated with higher mortality risk. AST shows a U-shaped nonlinear association with mortality risk. Incorporating liver biomarkers into traditional risk prediction models enhance the ability to predict mortality.
Redefining respiratory sinus arrhythmia as respiratory heart rate variability: an international Expert Recommendation for terminological clarity.
The variation of heart rate in phase with breathing, known as 'respiratory sinus arrhythmia' (RSA), is a physiological phenomenon present in all air-breathing vertebrates. RSA arises from the interaction of several physiological mechanisms but is primarily mediated by rhythmic changes in cardiac parasympathetic (vagal) activity, increasing heart rate during inspiration and decreasing heart rate during expiration. RSA amplitude is an indicator of autonomic and cardiac health; RSA is diminished or absent in common pathological conditions such as chronic heart failure and hypertension. In this Expert Recommendation, we argue that the term 'RSA', although historically important, is semantically inaccurate and carries misleading pathological connotations, contributing to misunderstanding and misinterpretation of the origin and the physiological importance of the phenomenon. We propose replacing 'RSA' with the term 'respiratory heart rate variability' (RespHRV), which avoids pathological connotations and emphasizes the specific respiratory contribution to heart rate variability. We clarify that RespHRV encompasses respiratory-related heart rate variations in both the low-frequency and high-frequency bands traditionally defined in heart rate variability analysis, and that its amplitude should not be misconstrued as a measure of vagal tone. Adopting the proposed term 'RespHRV' is expected to unify understanding and stimulate further experimental and clinical research into the physiological mechanisms and functional importance of this phenomenon.
FoxO1-zDHHC4-CD36 S-Acylation Axis Drives Metabolic Dysfunction in Diabetes.
BACKGROUND: The fatty acid (FA) transporter CD36 (FA translocase/cluster of differentiation 36) is the gatekeeper of cardiac FA metabolism. Preferential localization of CD36 to the sarcolemma is one of the initiating cellular responses in the development of muscle insulin resistance and the type 2 diabetic heart. Posttranslational S-acylation controls protein trafficking, and in this study, we hypothesized that increased CD36 S-acylation may underpin the preferential sarcolemmal localization of CD36, driving metabolic and contractile dysfunction in diabetes. METHODS AND RESULTS: Type 2 diabetes increased cardiac CD36 S-acylation, CD36 sarcolemmal localization, FA oxidation rates, and triglyceride storage in the diabetic heart. CD36 S-acylation was increased in diabetic rats, db/db mice, diabetic pigs, and insulin-resistant human iPSC-derived cardiomyocytes, demonstrating conservation between species. The enzyme responsible for S-acylating CD36, zDHHC4, was transcriptionally upregulated in the diabetic heart, and genetic silencing of zDHHC4 using siRNA or lentiviral shRNA decreased CD36 S-acylation. We identified that zDHHC4 expression is under the regulation of the transcription factor FoxO (forkhead box O) 1, as FoxO1 binds to the promotor of zDHHC4 and induces its transcription, as assessed using chromatin immunoprecipitation-seq, chromatin immunoprecipitation-quantitative PCR, luciferase assays, and siRNA silencing. Diabetic mice with cardiomyocyte-specific FoxO1 deletion had decreased cardiac zDHHC4 expression and decreased CD36 S-acylation, which was further confirmed using diabetic mice treated with the FoxO1 inhibitor AS1842856. Pharmacological inhibition of zDHHC enzymes in diabetic hearts decreased CD36 S-acylation, sarcolemmal CD36 content, FA oxidation rates, and triglyceride storage, culminating in improved cardiac function in diabetes. Conversely, inhibiting the deacylating enzymes in control hearts increased CD36 S-acylation, sarcolemmal CD36 content, and FA metabolic rates in control hearts, recapitulating the metabolic phenotype seen in diabetic hearts. CONCLUSIONS: Activation of the FoxO1-zDHHC4-CD36 S-acylation axis in diabetes drives metabolic and contractile dysfunction in type 2 diabetic heart.
Exercise Improves Myocardial Deformation But Not Cardiac Structure in Preterm-Born Adults: A Randomized Clinical Trial.
BACKGROUND: People born preterm (<37 weeks' gestation) have a potentially adverse cardiac phenotype that progresses with blood pressure elevation. OBJECTIVES: The authors investigated whether preterm-born and term-born adults exhibit similar cardiac structural and functional remodeling following a 16-week aerobic exercise intervention. METHODS: We conducted a randomized controlled trial in 203 adults (aged 18-35 years) with elevated blood pressure or stage 1 hypertension. Participants were randomized 1:1 to a 16-week aerobic exercise intervention or to a control group. In a prespecified cardiovascular magnetic resonance imaging (CMR) substudy, CMR was performed at 3.0-Tesla to assess left and right ventricular (LV and RV) structure and function before and after intervention. RESULTS: A total of 100 participants completed CMR scans at baseline and after the 16-week intervention, with n = 47 in the exercise intervention group (n = 26 term-born; n = 21 preterm-born) and n = 53 controls (n = 32 term-born; n = 21 preterm-born). In term-born participants, LV mass to end-diastolic volume ratio decreased (-3.43; 95% CI: -6.29 to -0.56; interaction P = 0.027) and RV stroke volume index increased (5.53 mL/m2; 95% CI: 2.60, 8.47; interaction P = 0.076) for those in the exercise intervention group vs controls. No significant effects were observed for cardiac structural indices in preterm-born participants. In preterm-born participants, LV basal- and mid-ventricular circumferential strain increased (-1.33; 95% CI: -2.07 to -0.60; interaction P = 0.057 and -1.54; 95% CI: -2.46 to -0.63; interaction P = 0.046, respectively) and RV global longitudinal strain increased (1.99%; 95% CI: -3.12 to -0.87; interaction P = 0.053) in the exercise intervention group vs controls. No significant effects were observed for myocardial deformation parameters in term-born participants. CONCLUSIONS: Aerobic exercise training induces improved myocardial function but not cardiac structure in preterm-born adults.
Long-term exposure to fine particulate matter interacting with individual conditions increase breast cancer incidence: a large-scale Chinese cohort
Background: Breast cancer is the most frequently diagnosed malignancy among women worldwide. This study aimed to investigate the impact of long-term fine particulate matter (PM2.5) exposure on breast cancer incidence in a cohort of 281,152 women from the China Kadoorie Biobank who were initially free of breast cancer. Results: PM2.5 concentrations were estimated using a high-resolution satellite-based model, and breast cancer cases were ascertained through national databases. Over a median follow-up of 11.12 years, 2393 new breast cancer cases were reported. Analyses using Cox proportional hazard and restricted cubic spline models demonstrated a non-linear association between PM2.5 exposure and breast cancer incidence, with a marked increase in risk observed once PM2.5surpassed 53.6 μg/m3. For every 10 μg/m3 increase in PM2.5, the hazard ratio for breast cancer incidence was 1.07 (95% confidence interval: 1.03–1.12). Furthermore, interactions were noted between PM2.5, physical activity, and life satisfaction, indicating that high pollution levels may diminish the protective benefits of exercise and positive psychological well-being. Conclusions: These findings highlight the need for stringent air pollution control measures and underscore the importance of integrated strategies that consider environmental, lifestyle, and psychological factors to reduce the burden of breast cancer.
Distinct epicardial gene regulatory programs drive development and regeneration of the zebrafish heart
Unlike the adult mammalian heart, which has limited regenerative capacity, the zebrafish heart fully regenerates following injury. Reactivation of cardiac developmental programs is considered key to successfully regenerating the heart, yet the regulation underlying the response to injury remains elusive. Here, we compared the transcriptome and epigenome of the developing and regenerating zebrafish epicardia. We identified epicardial enhancer elements with specific activity during development or during adult heart regeneration. By generating gene regulatory networks associated with epicardial development and regeneration, we inferred genetic programs driving each of these processes, which were largely distinct. Loss of Hif1ab, Nrf1, Tbx2b, and Zbtb7a, central regulators of the regenerating epicardial network, in injured hearts resulted in elevated epicardial cell numbers infiltrating the wound and excess fibrosis after cryoinjury. Our work identifies differences between the regulatory blueprint deployed during epicardial development and regeneration, underlining that heart regeneration goes beyond the reactivation of developmental programs.
N-terminal cysteine acetylation and oxidation patterns may define protein stability.
Oxygen homeostasis is maintained in plants and animals by O2-sensing enzymes initiating adaptive responses to low O2 (hypoxia). Recently, the O2-sensitive enzyme ADO was shown to initiate degradation of target proteins RGS4/5 and IL32 via the Cysteine/Arginine N-degron pathway. ADO functions by catalysing oxidation of N-terminal cysteine residues, but despite multiple proteins in the human proteome having an N-terminal cysteine, other endogenous ADO substrates have not yet been identified. This could be because alternative modifications of N-terminal cysteine residues, including acetylation, prevent ADO-catalysed oxidation. Here we investigate the relationship between ADO-catalysed oxidation and NatA-catalysed acetylation of a broad range of protein sequences with N-terminal cysteines. We present evidence that human NatA catalyses N-terminal cysteine acetylation in vitro and in vivo. We then show that sequences downstream of the N-terminal cysteine dictate whether this residue is oxidised or acetylated, with ADO preferring basic and aromatic amino acids and NatA preferring acidic or polar residues. In vitro, the two modifications appear to be mutually exclusive, suggesting that distinct pools of N-terminal cysteine proteins may be acetylated or oxidised. These results reveal the sequence determinants that contribute to N-terminal cysteine protein modifications, with implications for O2-dependent protein stability and the hypoxic response.
Nitric oxide biosensor uncovers diminished ferrous iron-dependency of cultured cells adapted to physiological oxygen levels.
Iron is an essential metal for cellular metabolism and signaling, but it has adverse effects in excess. The physiological consequences of iron deficiency are well established, yet the relationship between iron supplementation and pericellular oxygen levels in cultured cells and their downstream effects on metalloproteins has been less explored. This study exploits the metalloprotein geNOps in cultured HEK293T epithelial and EA.hy926 endothelial cells to test the iron-dependency in cells adapted to standard room air (18 kPa O2) or physiological normoxia (5 kPa O2). We show that cells in culture require iron supplementation to activate the metalloprotein geNOps and demonstrate for the first time that cells adapted to physiological normoxia require significantly lower iron compared to cells adapted to hyperoxia. This study establishes an essential role for recapitulating oxygen levels in vivo and uncovers a previously unrecognized requirement for ferrous iron supplementation under standard cell culture conditions to achieve geNOps functionality.
Hif-2α programs oxygen chemosensitivity in chromaffin cells.
The study of transcription factors that determine specialized neuronal functions has provided invaluable insights into the physiology of the nervous system. Peripheral chemoreceptors are neurone-like electrophysiologically excitable cells that link the oxygen concentration of arterial blood to the neuronal control of breathing. In the adult, this oxygen chemosensitivity is exemplified by type I cells of the carotid body, and recent work has revealed one isoform of the hypoxia-inducible transcription factor (HIF), HIF-2α, as having a nonredundant role in the development and function of that organ. Here, we show that activation of HIF-2α, including isolated overexpression of HIF-2α but not HIF-1α, is sufficient to induce oxygen chemosensitivity in adult adrenal medulla. This phenotypic change in the adrenal medulla was associated with retention of extra-adrenal paraganglioma-like tissues resembling the fetal organ of Zuckerkandl, which also manifests oxygen chemosensitivity. Acquisition of chemosensitivity was associated with changes in the adrenal medullary expression of gene classes that are ordinarily characteristic of the carotid body, including G protein regulators and atypical subunits of mitochondrial cytochrome oxidase. Overall, the findings suggest that, at least in certain tissues, HIF-2α acts as a phenotypic driver for cells that display oxygen chemosensitivity, thus linking 2 major oxygen-sensing systems.
Immune-mediated cardiac development and regeneration.
The complex interplay between the immune and cardiovascular systems during development, homeostasis and regeneration represents a rapidly evolving field in cardiac biology. Single cell technologies, spatial mapping and computational analysis have revolutionised our understanding of the diversity and functional specialisation of immune cells within the heart. From the earliest stages of cardiogenesis, where primitive macrophages guide heart tube formation, to the complex choreography of inflammation and its resolution during regeneration, immune cells emerge as central orchestrators of cardiac fate. Translating these fundamental insights into clinical applications represents a major challenge and opportunity for the field. In this Review, we decode the immunological blueprint of heart development and regeneration to transform cardiovascular disease treatment and unlock the regenerative capacity of the human heart.
MicroRNA-210 Enhances Cell Survival and Paracrine Potential for Cardiac Cell Therapy While Targeting Mitophagy.
The therapeutic potential of presumed cardiac progenitor cells (CPCs) in heart regeneration has garnered significant interest, yet clinical trials have revealed limited efficacy due to challenges in cell survival, retention, and expansion. Priming CPCs to survive the hostile hypoxic environment may be key to enhancing their regenerative capacity. We demonstrate that microRNA-210 (miR-210), known for its role in hypoxic adaptation, significantly improves CPC survival by inhibiting apoptosis through the downregulation of Casp8ap2, a ~40% reduction in caspase activity, and a ~90% decrease in DNA fragmentation. Contrary to the expected induction of Bnip3-dependent mitophagy by hypoxia, miR-210 did not upregulate Bnip3, indicating a distinct anti-apoptotic mechanism. Instead, miR-210 reduced markers of mitophagy and increased mitochondrial biogenesis and oxidative metabolism, suggesting a role in metabolic reprogramming. Furthermore, miR-210 enhanced the secretion of paracrine growth factors from CPCs, with a ~1.6-fold increase in the release of stem cell factor and of insulin growth factor 1, which promoted in vitro endothelial cell proliferation and cardiomyocyte survival. These findings elucidate the multifaceted role of miR-210 in CPC biology and its potential to enhance cell-based therapies for myocardial repair by promoting cell survival, metabolic adaptation, and paracrine signalling.
[Associations of plasma metabolites with mortality in Chinese adults: a prospective study].
Objective: To investigate the prospective associations between plasma metabolites and the risks of all-cause and cause-specific mortality among Chinese adults. Methods: This study analyzed plasma metabolomics data from 2 183 healthy adults in the China Kadoorie Biobank (CKB), measured using targeted mass spectrometry. Cox proportional hazards regression models were used to examine the associations between 630 metabolites and the risk of all-cause mortality. Cause-specific hazard regression models evaluated the associations between metabolites and cardiovascular disease (CVD) risks, cancer, and other-cause mortality. Stepwise regression was used to identify key metabolites independently associated with all-cause mortality, and the area under the receiver operating characteristic curve (AUC) was calculated to assess the improvement in predictive performance when these metabolites were added to traditional risk prediction models. Results: The mean age of the participants was (53.2±9.8) years, 65.1% of whom were female. During a median follow-up of 14.5 years, 231 deaths occurred. A total of 44 metabolites were significantly associated with the risk of all-cause mortality [false discovery rate (FDR)-adjusted P<0.05], primarily including triglycerides, ceramides, and amino acids. Additionally, 29 and 15 metabolites were found to be associated with cancer and other-cause mortality, respectively, but no metabolites were significantly associated with CVD mortality after FDR corrections. Adding 14 metabolites independently associated with all-cause mortality into the traditional prediction model significantly improved its predictive performance. Specifically, incorporating metabolites into the traditional model, which already included laboratory biomarkers, increased the AUC to 0.798 (95%CI: 0.755-0.843), an improvement of 0.088 compared to the traditional model (P<0.001). Conclusions: Multiple metabolites are significantly associated with mortality risk and can substantially improve the accuracy of mortality risk prediction models. These findings provide new insights into the physiological mechanisms of aging and offer valuable clues for personalized health risk assessment.