NR1D1 Deletion Induces Rupture-Prone Vulnerable Plaques by Regulating Macrophage Pyroptosis via the NF-κB/NLRP3 Inflammasome Pathway

The Role of Pyroptosis in Coronary Heart Disease

The incidence and mortality of cardiovascular diseases, of which coronary heart disease (CHD) is a significant cardiovascular burden, are on the rise. Pyroptosis as an incipient programmed cell death mediated by inflammasomes can sense cytoplasmic contamination or interference and is typically marked by intracellular swelling, plasma membrane blistering and intense inflammatory cytokine release. As research on pyroptosis continues to progress, there is mounting evidence that pyroptosis is a vital participant in the pathophysiological basis of CHD. Atherosclerosis is the major pathophysiological basis of CHD and involves pyroptosis of endothelial cells, macrophages, vascular smooth muscle cells, and other immune cells, often in association with the release of pro-inflammatory factors. When cardiomyocytes are damaged, it will eventually lead to heart failure. Previous studies have covered that pyroptosis plays a critical role in CHD. In this review, we describe the properties of pyroptosis, summarize its contribution and related targets to diseases involving angina pectoris, myocardial infarction, myocardial ischemia in perfusion injury and heart failure, and highlight potential drugs for different heart diseases.

Nobiletin alleviates atherosclerosis by inhibiting lipid uptake via the PPARG/CD36 pathway

BACKGROUND

Atherosclerosis (AS) is a persistent inflammatory condition triggered and exacerbated by several factors including lipid accumulation, endothelial dysfunction and macrophages infiltration. Nobiletin (NOB) has been reported to alleviate atherosclerosis; however, the underlying mechanism remains incompletely understood.

METHODS

This study involved comprehensive bioinformatic analysis, including multidatabase target prediction; GO and KEGG enrichment analyses for function and pathway exploration; DeepSite and AutoDock for drug binding site prediction; and CIBERSORT for immune cell involvement. In addition, target intervention was verified via cell scratch assays, oil red O staining, ELISA, flow cytometry, qRT‒PCR and Western blotting. In addition, by establishing a mouse model of AS, it was demonstrated that NOB attenuated lipid accumulation and the extent of atherosclerotic lesions.

RESULTS

(1) Altogether, 141 potentially targetable genes were identified through which NOB could intervene in atherosclerosis. (2) Lipid and atherosclerosis, fluid shear stress and atherosclerosis may be the dominant pathways and potential mechanisms. (3) ALB, AKT1, CASP3 and 7 other genes were identified as the top 10 target genes. (4) Six genes, including PPARG, MMP9, SRC and 3 other genes, were related to the M0 fraction. (5) CD36 and PPARG were upregulated in atherosclerosis samples compared to the normal control. (6) By inhibiting lipid uptake in RAW264.7 cells, NOB prevents the formation of foam cell. (7) In RAW264.7 cells, the inhibitory effect of oxidized low-density lipoprotein on foam cells formation and lipid accumulation was closely associated with the PPARG signaling pathway. (8) In vivo validation showed that NOB significantly attenuated intra-arterial lipid accumulation and macrophage infiltration and reduced CD36 expression.

CONCLUSIONS

Nobiletin alleviates atherosclerosis by inhibiting lipid uptake via the PPARG/CD36 pathway.

Rev-erbα attenuates diabetic myocardial injury through regulation of ferroptosis

Diabetes is a widespread disease that threatens the life and health of human beings, and diabetic cardiomyopathy (DCM) is one of the major complications of diabetic patients. The pathological mechanisms of DCM are complex, including inflammation, endoplasmic reticulum stress, and oxidative stress that have been reported previously. Although recent studies suggested that ferroptosis is also involved in the progression of DCM, the exact mechanism remains unclear. Rev-erbα cardiac conditional knockout mice were generated and type 2 diabetes were induced by high fat diet (HFD) and intraperitoneal injection of streptozotocin (STZ) in in vivo experiments. In parallel, our in vitro experiments entailed the introduction of elevated levels of glucose (HG) and palmitic acid (PA) to induce glycolipid toxicity in H9c2 cardiomyocytes. Further deterioration of cardiac function was detected by echocardiography after the clock gene rev-erbα was knocked out. This was accompanied by significant elevations in markers of inflammation, myocardial fibrosis, and oxidative stress. In addition, iron content, transmission electron microscopy (TEM), and RT-PCR assays confirmed significantly increased levels of ferroptosis in rev-erbα-deficient DCM. Intriguingly, Co-Immunoprecipitation (Co-IP) data uncovered an interaction between rev-erbα and nuclear factor E2-related factor 2 (NRF2) in diabetic myocardial tissues. It is worth highlighting that ferroptosis within cardiomyocytes witnessed significant mitigation upon the administration of sulforaphane (SFN), an NRF2 agonist, to HG + PA-incubated H9c2 cells. Our study demonstrates for the first time that knockdown of the clock gene rev-erbα exacerbates myocardial injury and ferroptosis in type 2 diabetic mice, which can be reversed by activating NRF2.

Effect of Long Non-coding RNA and DNA Methylation on Gene Expression in Dental Fluorosis

In the process of tooth development, the interaction between genetic information, epigenetic inheritance, and environment jointly affects the teeth formation. At present, the mechanism of dental fluorosis is rarely studied from transcriptomics, and there is no report on epigenetic perspective. In the study, SD rats were randomly divided into dental fluorosis group and control group fed with NaF (150 mg/L) or distilled water for 8 weeks. After 3.5 days of birth, the RNAs or DNA of rat mandibular molars were detected by RNA-seq or MethylTarget, respectively. The results demonstrated that a total of 1723 differentially expressed genes (DEGs) and 2511 differential expression lncRNAs (DE-lncRNAs) were mainly involved in the ion channels, calcium ion transport, and immunomodulatory signaling pathways. ATP2C1 and Nr1d1, which were related to Ca2+ transport, cellular calcium homeostasis, endoplasmic reticulum stress and immunity, may be the key genes in the formation of dental fluorosis. Notably, we also found that the immune response plays an important role in the formation of dental fluorosis, and a large amount of DEGs was enriched in immune regulation and NF-κB signaling pathways. Furthermore, the methylation levels of 13 sites were increased in Ago4, Atf3, Atp2c1, Dusp1, Habp4, and Mycl, while methylation levels of 5 CpG sites decreased in Ago4, Atp2c1, Habp4, and Traf6, and conformably, the expression of these genes have been significantly changed. This study comprehensively analyzed the occurrence mechanism of dental fluorosis from transcriptomics and epigenetics, so as to provide theoretical reference for further research.

Targeting NR1D1 in organ injury: challenges and prospects

Nuclear receptor subfamily 1, group D, member 1 (NR1D1, also known as REV-ERBα) belongs to the nuclear receptor (NR) family, and is a heme-binding component of the circadian clock that consolidates circadian oscillators. In addition to repressing the transcription of multiple clock genes associated with circadian rhythms, NR1D1 has a wide range of downstream target genes that are intimately involved in many physiopathological processes, including autophagy, immunity, inflammation, metabolism and aging in multiple organs. This review focuses on the pivotal role of NR1D1 as a key transcription factor in the gene regulatory network, with particular emphasis on the milestones of the latest discoveries of NR1D1 ligands. NR1D1 is considered as a promising drug target for treating diverse diseases and may contribute to research on innovative biomarkers and therapeutic targets for organ injury-related diseases. Further research on NR1D1 ligands in prospective human trials may pave the way for their clinical application in many organ injury-related disorders.

High-Dose Ionizing Radiation Accelerates Atherosclerotic Plaque Progression by Regulating P38/NCOA4-Mediated Ferritinophagy/Ferroptosis of Endothelial Cells

PURPOSE

Radiation therapy (RT) significantly increased the incidence of coronary artery diseases, especially atherosclerosis. Endothelial dysfunction has been the major side effect of RT among tumor patients who received RT. However, the involvement between endothelial dysfunction and radiation-induced atherosclerosis (RIA) remains unclear. Here, we constructed a murine model of RIA, aiming to uncover its underlying mechanisms and identify novel strategies for RIA prevention and treatment.

METHODS AND MATERIALS

Eight-week-old ApoE-/- mice that were fed a Western diet were subjected to partial carotid ligation (PCL). Four weeks later, ionizing radiation (IR) of 10 Gy was performed to verify the detrimental role of IR on atherogenesis. Ultrasound imaging, RT quantitative polymerase chain reaction, histopathology and immunofluorescence, and biochemical analysis were performed 4 weeks after IR. To study the involvement of endothelial ferroptosis induced by IR in RIA, mice after IR were administrated with ferroptosis agonist (cisplatin) or antagonist (ferrostatin-1) intraperitoneally. Western blotting, autophagic flux measurement, reactive oxygen species level detection, and coimmunoprecipitation assay were carried out in vitro. Furthermore, to determine the effect of ferritinophagy inhibition on RIA, in vivo knockdown of NCOA4 was carried out by pluronic gel.

RESULTS

We verified that accelerated plaque progression was concomitant with endothelial cell (EC) ferroptosis after IR induction, as suggested by a higher level of lipid peroxidation and changes in ferroptosis-associated genes in the PCL + IR group than in the PCL group within vasculature. In vitro experiments further validated the devastating effects of IR on oxidative stress and ferritinophagy in ECs. Mechanistic experiments revealed that IR induced EC ferritinophagy and subsequent ferroptosis in a P38/NCOA4-dependent manner. Both in vitro and in vivo experiments confirmed the therapeutic effect of NCOA4 knockdown in alleviating IR-induced ferritinophagy/ferroptosis of EC and RIA.

CONCLUSIONS

Our findings provide novel insights into the regulatory mechanisms of RIA and first prove that IR accelerates atherosclerotic plaque progression by regulating ferritinophagy/ferroptosis of ECs in a P38/NCOA4-dependent manner.

The Stria Vascularis in Mice and Humans Is an Early Site of Age-Related Cochlear Degeneration, Macrophage Dysfunction, and Inflammation

Age-related hearing loss, or presbyacusis, is a common degenerative disorder affecting communication and quality of life for millions of older adults. Multiple pathophysiologic manifestations, along with many cellular and molecular alterations, have been linked to presbyacusis; however, the initial events and causal factors have not been clearly established. Comparisons of the transcriptome in the lateral wall (LW) with other cochlear regions in a mouse model (of both sexes) of "normal" age-related hearing loss revealed that early pathophysiological alterations in the stria vascularis (SV) are associated with increased macrophage activation and a molecular signature indicative of inflammaging, a common form of immune dysfunction. Structure-function correlation analyses in mice across the lifespan showed that the age-dependent increase in macrophage activation in the stria vascularis is associated with a decline in auditory sensitivity. High-resolution imaging analysis of macrophage activation in middle-aged and aged mouse and human cochleas, along with transcriptomic analysis of age-dependent changes in mouse cochlear macrophage gene expression, support the hypothesis that aberrant macrophage activity is an important contributor to age-dependent strial dysfunction, cochlear pathology, and hearing loss. Thus, this study highlights the SV as a primary site of age-related cochlear degeneration and aberrant macrophage activity and dysregulation of the immune system as early indicators of age-related cochlear pathology and hearing loss. Importantly, novel new imaging methods described here now provide a means to analyze human temporal bones in a way that had not previously been feasible and thereby represent a significant new tool for otopathological evaluation.SIGNIFICANCE STATEMENT Age-related hearing loss is a common neurodegenerative disorder affecting communication and quality of life. Current interventions (primarily hearing aids and cochlear implants) offer imperfect and often unsuccessful therapeutic outcomes. Identification of early pathology and causal factors is crucial for the development of new treatments and early diagnostic tests. Here, we find that the SV, a nonsensory component of the cochlea, is an early site of structural and functional pathology in mice and humans that is characterized by aberrant immune cell activity. We also establish a new technique for evaluating cochleas from human temporal bones, an important but understudied area of research because of a lack of well-preserved human specimens and difficult tissue preparation and processing approaches.

The REV-ERB Nuclear Receptors: Timekeepers for the Core Clock Period and Metabolism

REV-ERB nuclear receptors are potent transcriptional repressors that play an important role in the core mammalian molecular clock and metabolism. Deletion of both REV-ERBα and its largely redundant isoform REV-ERBβ in a murine tissue-specific manner have shed light on their specific functions in clock mechanisms and circadian metabolism. This review highlights recent findings that establish REV-ERBs as crucial circadian timekeepers in a variety of tissues, regulating overlapping and distinct processes that maintain normal physiology and protect from metabolic dysfunction.

Nuclear Receptor NR1D1 Regulates Abdominal Aortic Aneurysm Development by Targeting the Mitochondrial Tricarboxylic Acid Cycle Enzyme Aconitase-2

BACKGROUND

Metabolic disorder increases the risk of abdominal aortic aneurysm (AAA). NRs (nuclear receptors) have been increasingly recognized as important regulators of cell metabolism. However, the role of NRs in AAA development remains largely unknown.

METHODS

We analyzed the expression profile of the NR superfamily in AAA tissues and identified NR1D1 (NR subfamily 1 group D member 1) as the most highly upregulated NR in AAA tissues. To examine the role of NR1D1 in AAA formation, we used vascular smooth muscle cell (VSMC)-specific, endothelial cell-specific, and myeloid cell-specific conditional Nr1d1 knockout mice in both AngII (angiotensin II)- and CaPO₄-induced AAA models.

RESULTS

Nr1d1 gene expression exhibited the highest fold change among all 49 NRs in AAA tissues, and NR1D1 protein was upregulated in both human and murine VSMCs from AAA tissues. The knockout of Nr1d1 in VSMCs but not endothelial cells and myeloid cells inhibited AAA formation in both AngII- and CaPO₄-induced AAA models. Mechanistic studies identified ACO2 (aconitase-2), a key enzyme of the mitochondrial tricarboxylic acid cycle, as a direct target trans-repressed by NR1D1 that mediated the regulatory effects of NR1D1 on mitochondrial metabolism. NR1D1 deficiency restored the ACO2 dysregulation and mitochondrial dysfunction at the early stage of AngII infusion before AAA formation. Supplementation with αKG (α-ketoglutarate, a downstream metabolite of ACO2) was beneficial in preventing and treating AAA in mice in a manner that required NR1D1 in VSMCs.

CONCLUSIONS

Our data define a previously unrecognized role of nuclear receptor NR1D1 in AAA pathogenesis and an undescribed NR1D1-ACO2 axis involved in regulating mitochondrial metabolism in VSMCs. It is important that our findings suggest αKG supplementation as an effective therapeutic approach for AAA treatment.

Structural basis of synthetic agonist activation of the nuclear receptor REV-ERB

The nuclear receptor REV-ERB plays an important role in a range of physiological processes. REV-ERB behaves as a ligand-dependent transcriptional repressor and heme has been identified as a physiological agonist. Our current understanding of how ligands bind to and regulate transcriptional repression by REV-ERB is based on the structure of heme bound to REV-ERB. However, porphyrin (heme) analogues have been avoided as a source of synthetic agonists due to the wide range of heme binding proteins and potential pleotropic effects. How non-porphyrin synthetic agonists bind to and regulate REV-ERB has not yet been defined. Here, we characterize a high affinity synthetic REV-ERB agonist, STL1267, and describe its mechanism of binding to REV-ERB as well as the method by which it recruits transcriptional corepressor both of which are unique and distinct from that of heme-bound REV-ERB.

Targeting Nuclear Receptors for Chronic Inflammatory Pain: A Potential Alternative

Pain is the unpleasant consequence of detrimental neuronal activity that can be triggered by chronic inflammation, noxious stimuli, and nerve damage. In the case of chronic inflammatory pain, the establishment and maintenance of pain states often depend on the chronic activation and immune response occurring at the site of the peripheral nerve injury. Many current analgesic drugs lack efficacy in long-term pain management. Targeting the nuclear receptor family of transcription factors may provide a novel avenue for the treatment of chronic inflammatory pain. Peroxisome proliferator-activated receptor (PPAR) ligands have demonstrated efficacy in several diabetic-related neuropathic pain models, while the REV-ERB receptors play a key role in the regulation of both P2X7 receptor expression and NLRP3 inflammasome expression and activation. As such, activating the REV-ERB receptor may provide an anti-inflammatory and analgesic option for chronic inflammatory pain sufferers.

Disruption of Circadian Rhythms by Shift Work Exacerbates Reperfusion Injury in Myocardial Infarction

BACKGROUND

Shift work is associated with increased risk of acute myocardial infarction (AMI) and worsened prognosis. However, the mechanisms linking shift work and worsened prognosis in AMI remain unclear.

OBJECTIVES

This study sought to investigate the impact of shift work on reperfusion injury, a major determinant of clinical outcomes in AMI.

METHODS

Study patient data were obtained from the database of the EARLY-MYO-CMR (Early Assessment of Myocardial Tissue Characteristics by CMR in STEMI) registry, which was a prospective, multicenter registry of patients with ST-segment elevation myocardial infarction (STEMI) undergoing cardiac magnetic resonance (CMR) imaging after reperfusion therapy. The primary endpoint was CMR-defined post-reperfusion infarct size. A secondary clinical endpoint was the composite of major adverse cardiac events (MACE) during follow-up. Potential mechanisms were explored with the use of preclinical animal AMI models.

RESULTS

Of 706 patients enrolled in the EARLY-MYO-CMR registry, 412 patients with STEMI were ultimately included. Shift work was associated with increased CMR-defined infarct size (β = 5.94%; 95% CI: 2.94-8.94; P < 0.0001). During a median follow-up of 5.0 years, shift work was associated with increased risks of MACE (adjusted HR: 1.92; 95% CI: 1.12-3.29; P = 0.017). Consistent with clinical findings, shift work simulation in mice and sheep significantly augmented reperfusion injury in AMI. Mechanism studies identified a novel nuclear receptor subfamily 1 group D member 1/cardiotrophin-like cytokine factor 1 axis in the heart that played a crucial role in mediating the detrimental effects of shift work on myocardial injury.

CONCLUSIONS

The current study provided novel findings that shift work increases myocardial infarction reperfusion injury. It identified a novel nuclear receptor subfamily 1 group D member 1/cardiotrophin-like cytokine factor 1 axis in the heart that might play a crucial role in mediating this process. (Early Assessment of Myocardial Tissue Characteristics by CMR in STEMI [EARLY-MYO-CMR] registry; NCT03768453).