The BMAL1/HIF2A heterodimer modulates circadian variations of myocardial injury.

Acute myocardial infarction stands as a prominent cause of morbidity and mortality worldwide1-6. Clinical studies have demonstrated that the severity of cardiac injury following myocardial infarction exhibits a circadian pattern, with larger infarct sizes and poorer outcomes in patients experiencing morning onset myocardial infarctions7-14. However, the molecular mechanisms that govern circadian variations of myocardial injury remain unclear. Here, we show that BMAL114-20, a core circadian transcription factor, orchestrates diurnal variability in myocardial injury. Unexpectedly, BMAL1 modulates circadian-dependent cardiac injury by forming a transcriptionally active heterodimer with a non-canonical partner, hypoxia-inducible factor 2 alpha (HIF2A)6,21-23, in a diurnal manner. Substantiating this finding, we determined the cryo-EM structure of the BMAL1/HIF2A/DNA complex, revealing a previously unknown capacity for structural rearrangement within BMAL1, which enables the crosstalk between circadian rhythms and hypoxia signaling. Furthermore, we identified amphiregulin (AREG) as a rhythmic transcriptional target of the BMAL1/HIF2A heterodimer, critical for regulating circadian variations of myocardial injury. Finally, pharmacologically targeting the BMAL1/HIF2A-AREG pathway provides effective cardioprotection, with maximum efficacy when aligned with the pathway's circadian trough. Our findings not only uncover a novel mechanism governing the circadian variations of myocardial injury but also pave the way for innovative circadian-based treatment strategies, potentially shifting current treatment paradigms for myocardial infarction.

Distinct Stress-Dependent Signatures of Cellular and Extracellular tRNA-Derived Small RNAs.

The cellular response to stress is an important determinant of disease pathogenesis. Uncovering the molecular fingerprints of distinct stress responses may identify novel biomarkers and key signaling pathways for different diseases. Emerging evidence shows that transfer RNA-derived small RNAs (tDRs) play pivotal roles in stress responses. However, RNA modifications present on tDRs are barriers to accurately quantifying tDRs using traditional small RNA sequencing. Here, AlkB-facilitated methylation sequencing is used to generate a comprehensive landscape of cellular and extracellular tDR abundances in various cell types during different stress responses. Extracellular tDRs are found to have distinct fragmentation signatures from intracellular tDRs and these tDR signatures are better indicators of different stress responses than miRNAs. These distinct extracellular tDR fragmentation patterns and signatures are also observed in plasma from patients on cardiopulmonary bypass. It is additionally demonstrated that angiogenin and RNASE1 are themselves regulated by stressors and contribute to the stress-modulated abundance of sub-populations of cellular and extracellular tDRs. Finally, a sub-population of extracellular tDRs is identified for which AGO2 appears to be required for their expression. Together, these findings provide a detailed profile of stress-responsive tDRs and provide insight about tDR biogenesis and stability in response to cellular stressors.

Single-Cell Multiomics Reveals Clonal T-Cell Expansions and Exhaustion in Blastic Plasmacytoid Dendritic Cell Neoplasm.

The immune system represents a major barrier to cancer progression, driving the evolution of immunoregulatory interactions between malignant cells and T-cells in the tumor environment. Blastic plasmacytoid dendritic cell neoplasm (BPDCN), a rare acute leukemia with plasmacytoid dendritic cell (pDC) differentiation, provides a unique opportunity to study these interactions. pDCs are key producers of interferon alpha (IFNA) that play an important role in T-cell activation at the interface between the innate and adaptive immune system. To assess how uncontrolled proliferation of malignant BPDCN cells affects the tumor environment, we catalog immune cell heterogeneity in the bone marrow (BM) of five healthy controls and five BPDCN patients by analyzing 52,803 single-cell transcriptomes, including 18,779 T-cells. We test computational techniques for robust cell type classification and find that T-cells in BPDCN patients consistently upregulate interferon alpha (IFNA) response and downregulate tumor necrosis factor alpha (TNFA) pathways. Integrating transcriptional data with T-cell receptor sequencing via shared barcodes reveals significant T-cell exhaustion in BPDCN that is positively correlated with T-cell clonotype expansion. By highlighting new mechanisms of T-cell exhaustion and immune evasion in BPDCN, our results demonstrate the value of single-cell multiomics to understand immune cell interactions in the tumor environment.

Novel and Annotated Long Noncoding RNAs Associated with Ischemia in the Human Heart.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been implicated in the pathogenesis of cardiovascular diseases. We aimed to identify novel lncRNAs associated with the early response to ischemia in the heart. METHODS AND RESULTS: RNA sequencing data gathered from 81 paired left ventricle samples from patients undergoing cardiopulmonary bypass was collected before and after a period of ischemia. Novel lncRNAs were validated with Oxford Nanopore Technologies long-read sequencing. Gene modules associated with an early ischemic response were identified and the subcellular location of selected lncRNAs was determined with RNAscope. A total of 2446 mRNAs, 270 annotated lncRNAs and one novel lncRNA differed in response to ischemia (adjusted p < 0.001, absolute fold change >1.2). The novel lncRNA belonged to a gene module of highly correlated genes that also included 39 annotated lncRNAs. This module associated with ischemia (Pearson correlation coefficient = -0.69, p = 1 × 10-23) and activation of cell death pathways (p < 6 × 10-9). A further nine novel cardiac lncRNAs were identified, of which, one overlapped five cis-eQTL eSNPs for the gene RWD Domain-Containing Sumoylation Enhancer (RWDD3) and was itself correlated with RWDD3 expression (Pearson correlation coefficient -0.2, p = 0.002). CONCLUSION: We have identified 10 novel lncRNAs, one of which was associated with myocardial ischemia and may have potential as a novel therapeutic target or early marker for myocardial dysfunction.

Myocardial preservation methods in isolated minimal invasive mitral valve surgery: Society of Thoracic Surgeons (STS) database outcomes.

OBJECTIVE: Minimal invasive mitral valve surgery (MIMVS) has become a commonly used approach for mitral valve surgery. Several techniques of myocardial preservation were described in patients undergoing MIMVS. We aim to evaluate preservation technique and short term outcomes. METHODS: A retrospective analysis of patients who underwent isolated MIMVS and were included in the Society of Thoracic Surgeons (STS) database. RESULTS: The final cohort included 4976 patients. Mean age was 63.1 years (SD, 12.5) and 42.6% were females. Antegrade delivery method (71.3% of the patients) was the most common, follow by antergrade/retrograde (19.9%). Blood, crystalloid solution, and combination of blood-crystalloid were used in 62.4%, 13.2%, and 13.7%, respectively. In multivariate analysis, cardioplegia technique was associated with mortality (P = .011), pleural effusion (P = .045), and length of ICU stay (P < .001). Antegrade-crystalloid (OR, 3.37; 95%CI, 1.70-6.68) and antegrade/retrograde-blood/crystalloid (OR, 3.28; 95%CI, 1.15-9.38) were associated with increased risk for mortality compared with antegrade-blood cardioplegia. Data on postoperative ejection fraction (EF), CPK-MB, and Troponin was available only in 30%, 9%, and 5% of the patients, respectively, and were not included in the analysis. CONCLUSIONS: Ante-grade-blood was the most common preservation technique in MIMVS. Ante-grade-crystalloid and ante-grade/retrograde-blood/crystalloid are associated with increased risk for mortality. The results suggest that using crystalloid solutions for cardioplegia should be carefully considered. The STS database as a source for MIMVS outcome analysis is lacking, both in detailed specification of different surgical technique aspects, and in actual data collection of already existing categories.

Sex differences in gene expression in response to ischemia in the human left ventricular myocardium.

Sex differences exist in the prevalence, presentation and outcomes of ischemic heart disease (IHD). Females have higher risk of heart failure post-myocardial infarction relative to males and are two to three times more likely to die after coronary artery bypass grafting surgery. We examined sex differences in human myocardial gene expression in response to ischemia. Left ventricular biopsies from 68 male/46 female patients undergoing aortic valve replacement surgery were obtained at baseline and after a median 74 min of cold cardioplegic arrest/ischemia. Transcriptomes were quantified by RNA-sequencing. Cell-type enrichment analysis was used to estimate the identity and relative proportions of different cell types in each sample. A sex-specific response to ischemia was observed for 271 genes. Notably, the expression FAM5C, PLA2G4E and CYP1A1 showed an increased expression in females compared to males due to ischemia and DIO3, MT1G and CMA1 showed a decreased expression in females compared to males due to ischemia. Functional annotation analysis revealed sex-specific modulation of the oxytocin signaling pathway and common pathway of fibrin clot formation. Expression quantitative trait locus (eQTL) analysis identified variant-by-sex interaction eQTLs, indicative of sex differences in the genotypic effects on gene expression. Cell-type enrichment analysis showed sex-bias in proportion of specific cell types. Common lymphoid progenitor cells and M2 macrophages were found to increase in female samples from pre- to post-ischemia, but no change was observed in male samples. These differences in response to myocardial ischemia provide insight into the sexual dimorphism of IHD and may aid in the development of sex-specific therapies that reduce myocardial injury.

Familial Anomalous Origin of Right Coronary Artery from the Left Coronary Sinus.

Anomalous origin of a coronary artery from the opposite sinus of Valsalva is a rare congenital anomaly. The prevalence of familial clustering of coronary artery anomalies is unknown. Here we describe the case of a father and son, both of whom presented with major adverse cardiac events due to Anomalous origin of a coronary artery from the opposite sinus of Valsalva and both had right coronary artery arising from the left coronary cusp with an interarterial course.

Molecular Genetics of Lidocaine-Containing Cardioplegia in the Human Heart During Cardiac Surgery.

BACKGROUND: During cardiac surgery with cardiopulmonary bypass, delivery of cardioplegia solution to achieve electromechanical cardiac quiescence is obligatory. The addition of lidocaine to cardioplegia has advantages, although its consequences at a molecular level remain unclear. We performed whole-genome RNA sequencing of the human left ventricular (LV) myocardium to elucidate the differences between whole-blood (WB) cardioplegia with and without addition of lidocaine (LC) on gene expression. METHODS: We prospectively enrolled 130 patients undergoing aortic valve replacement surgery. Patients received high-potassium blood cardioplegia either with (n = 37) or without (n = 93) lidocaine. The LV apex was biopsied at baseline, and after an average of 74 minutes of cold cardioplegic arrest. We performed differential gene expression analysis for 18,258 genes between these 2 groups. Clinical and demographic variables were adjusted in the model. Gene ontology (GO) and network enrichment analysis of the retained genes were performed using g:Profiler and Cytoscape. RESULTS: A total of 1,298 genes were differentially expressed between cardioplegic treatments. Compared with the WB group, genes upregulated in the LC group were identified by network enrichment to play a protective role in ischemic injury by inhibiting apoptosis, increasing transferrin endocytosis, and increasing cell viability. Downregulated genes in the LC group were identified to play a role in inflammatory diseases, oxygen transport, and neutrophil aggregation. CONCLUSIONS: The addition of lidocaine to cardioplegia had pronounced effects on a molecular level with genes responsible for decreased inflammation, reduced intracellular calcium binding, enhanced antiapoptotic protection, augmented oxygen accessibility through transferrins, and increased cell viability showing measurable differences.

Current Readings: Single vs Bilateral Internal Mammary Artery in Coronary Artery Bypass Grafting.

There is strong retrospective data demonstrating that bilateral internal mammary artery (BIMA) grafting leads to better long-term survival as compared to left internal mammary artery grafting. However, this survival advantage was not corroborated by the interim results of the Arterial Revascularization Trial. Today, there are barriers to widespread adoption of BIMA grafting. One of the main disadvantages of the use of BIMA grafts is the higher risk of deep sternal wound infection. Deep sternal wound infections can be minimized by skeletonized harvesting of the internal mammary artery grafts, which preserve blood flow to the sternum. Also, utilizing the BIMA graft as a "Y" graft may lead to more complete revascularization compared to its in situ use. BIMA grafting on average takes 25 minutes longer operating time with a higher in-hospital costs. We eagerly await the 10-year results of the Arterial Revascularization Trial to determine the truly unbiased randomized long-term effectiveness of BIMA grafting.

Outcomes of repeat mitral valve replacement in patients with prior mitral surgery: A benchmark for transcatheter approaches.

OBJECTIVES: With the emergence of transcatheter mitral valve-in-valve/ring replacement for deteriorated bioprostheses or failed repair, comparative clinical benchmarks for surgical repeat mitral valve replacement (re-MVR) are needed. We present in-hospital and survival outcomes of a 24-year experience with re-MVR. METHODS: From January 1992 to June 2015, 520 adult patients underwent re-MVR; 273 had undergone prior mitral valve repair (pMVP) and 247 had undergone prior MVR (pMVR). A benchmark cohort of isolated re-MVR was defined based on potential eligibility for transcatheter mitral valve-in-valve/ring replacement, resulting in 73 pMVPs with previous annuloplasty rings and 74 pMVRs with previous bioprosthetic valves for comparison. RESULTS: For the entire cohort, mean age was 64 ± 12 years for pMVP patients and 63 ± 15 years for pMVR patients (P = .281), which was similar for the benchmark cohort. Overall operative mortality was 14 out of 273 (5%) for pMVP versus 23 out of 247 (9%) for pMVR (P = .087). There were 3 operative deaths (4.1%) in both groups of the benchmark cohort (P = 1.0). For the benchmark cohort, median time to reoperation was 9.8 years for pMVP and 9.1 years for pMVR. Cox proportional hazard analysis showed that chronic kidney disease (hazard ratio [HR], 2.47; 95% CI, 1.77-3.44), endocarditis (HR, 1.49; 95% CI, 1.07-2.07), pMVR (HR, 1.45; 95% CI, 1.12-1.89), early reoperation ≤ 1 year (HR, 1.49; 95% CI, 1.02-2.17), and age (HR, 1.04/y; 95% CI, 1.03-1.05) were associated with decreased survival after re-MVR. CONCLUSIONS: A re-MVR is a high-risk operation, but in carefully selected patients such as our benchmark population, it can be performed with acceptable results. Patients undergoing pMVP also have better long-term survival compared with patients undergoing pMVR. These results will serve as a benchmark for transcatheter mitral valve-in-valve/ring replacement.