Endothelial TET2 regulates the white adipose browning and metabolism via fatty acid oxidation in obesity.

Obesity is a complex metabolic disorder, manifesting as excessive accumulation of body fat. Ten-Eleven Translocation-2 (TET2) has garnered significant attention in the context of obesity due to its crucial role in epigenetic regulation and metabolic homeostasis. In this study, we aimed to investigate the effect of endothelial TET2 on obesity and explore the potential mechanism. We generated endothelial cell-specific TET2 deficiency mice and investigated endothelial TET2 using transcriptomic and epigenomic analyses. We determined the downregulation of endothelial TET2 in white adipose tissues. Furthermore, we identified that endothelial TET2 loss aggravated high-fat diet-induced obesity by inhibiting vascularization and thus suppressing white adipose tissue browning. Mechanistically, endothelial TET2 modulates obesity by engaging in endothelial fatty acid oxidation and angiocrine-mediated secretion of bone morphogenetic protein 4 (BMP4), in which nuclear factor-erythroid 2-related factor 2 (NRF2) serves as a key mediator. Our study reveals that endothelial TET2 regulates white adipose tissue browning by interacting with NRF2 to facilitate fatty acid oxidation and lipolysis in adipocytes.

TREM2 macrophage promotes cardiac repair in myocardial infarction by reprogramming metabolism via SLC25A53.

Efferocytosis and metabolic reprogramming of macrophages play crucial roles in myocardial infarction (MI) repair. TREM2 has been proven to participate in phagocytosis and metabolism, but how it modulates myocardial infarction remains unclear. In this study, we showed that macrophage-specific TREM2 deficiency worsened cardiac function and impaired post-MI repair. Using RNA-seq, protein and molecular docking, and Targeted Metabolomics (LC-MS), our data demonstrated that macrophages expressing TREM2 exhibited decreased SLC25A53 transcription through the SYK-SMAD4 signaling pathway after efferocytosis, which impaired NAD+ transport into mitochondria, downregulated SLC25A53 thereby causing the breakpoint in the TCA cycle and subsequently increased itaconate production. In vitro experiments confirmed that itaconate secreted by TREM2+ macrophages inhibited cardiomyocyte apoptosis and promoted fibroblast proliferation. Conversely, overexpression of TREM2 in macrophages could improve cardiac function. In summary, our study reveals a novel role for macrophage-specific TREM2 in MI, connecting efferocytosis to immune metabolism during cardiac repair.

NLRC3 deficiency promotes hypoxia-induced pulmonary hypertension development via IKK/NF-κB p65/HIF-1α pathway.

Hypoxia-induced pulmonary hypertension is a subgroup of type 3 pulmonary hypertension (PH) with the recommended treatment limited to oxygen therapy and lacks potential therapeutic targets. To investigate the role of NLRC3 in hypoxia-induced PH and its potential mechanism, we first collected lung tissues of high-altitude pulmonary hypertension (HAPH) patients. Immunohistochemistry and immunofluorescence showed that NLRC3 was downregulated and was mainly co-localized with the smooth muscle cells of the pulmonary vessels in HAPH patients. Besides, we found that NLRC3 was also expressed in endothelial cells in HAPH patients for the first time. Then, wild type (WT) and NLRC3 knockout (NLRC3-/-) mice were used to construct hypoxia models and primary pulmonary arterial smooth muscle cells (PASMCs) of rats and endothelial cells were cultured for verification. Right heart catheterization and echocardiography suggested that NLRC3 knockout promoted right ventricular systolic pressure (RVSP) up-regulation, right ventricular hypertrophy and fibrosis in hypoxia-induced mice. This study first demonstrated that NLRC3 deficiency promoted hypoxia-stimulated PASMCs proliferation, Human umbilical vein endothelial cells (HUVECs) apoptosis, migration and inflammation through IKK/NF-κB p65/HIF-1α pathway in vitro and in vivo, further promoted vascular remodeling and PH progression, which provided a new target for the treatment of hypoxia-induced PH.

Macrophage-Specific NLRC5 Protects From Cardiac Remodeling Through Interaction With HSPA8.

Macrophages regulate inflammation and the process of tissue repair. Therefore, a better understanding of macrophages in the pathogenesis of heart failure is needed. In patients with hypertrophic cardiomyopathy, NLRC5 was significantly increased in circulating monocytes and cardiac macrophages. Myeloid-specific deletion of NLRC5 aggravated pressure overload-induced pathological cardiac remodeling and inflammation. Mechanistically, NLRC5 interacted with HSPA8 and suppressed NF-κB pathway in macrophages. The absence of NLRC5 in macrophages promoted the secretion of cytokines such as interleukin-6 (IL-6), which affected cardiomyocyte hypertrophy and cardiac fibroblast activation. Tocilizumab, an anti-IL-6 receptor antagonist, may be a novel therapeutic strategy for cardiac remodeling and chronic heart failure.

Loss of TET2 impairs endothelial angiogenesis via downregulating STAT3 target genes.

BACKGROUND: Ischemic diseases represent a major global health care burden. Angiogenesis is critical in recovery of blood flow and repair of injured tissue in ischemic diseases. Ten-eleven translocation protein 2 (TET2), a member of DNA demethylases, is involved in many pathological processes. However, the role of TET2 in angiogenesis is still unrevealed. METHODS: TET2 was screened out from three DNA demethylases involved in 5-hydroxylmethylcytosine (5-hmC) regulation, including TET1, TET2 and TET3. Knockdown by small interfering RNAs and overexpression by adenovirus were used to evaluate the role of TET2 on the function of endothelial cells. The blood flow recovery and density of capillary were analyzed in the endothelial cells-specific TET2-deficient mice. RNA sequencing was used to identify the TET2-mediated mechanisms under hypoxia. Co-immunoprecipitation (Co-IP), chromatin immunoprecipitation-qPCR (ChIP-qPCR) and glucosylated hydroxymethyl-sensitive-qPCR (GluMS-qPCR) were further performed to reveal the interaction of TET2 and STAT3. RESULTS: TET2 was significantly downregulated in endothelial cells under hypoxia and led to a global decrease of 5-hmC level. TET2 knockdown aggravated the hypoxia-induced dysfunction of endothelial cells, while TET2 overexpression alleviated the hypoxia-induced dysfunction. Meanwhile, the deficiency of TET2 in endothelial cells impaired blood flow recovery and the density of capillary in the mouse model of hindlimb ischemia. Mechanistically, RNA sequencing indicated that the STAT3 signaling pathway was significantly inhibited by TET2 knockdown. Additionally, Co-IP, ChIP-qPCR and GluMS-qPCR further illustrated that STAT3 recruited and physically interacted with TET2 to activate STAT3 target genes. As expected, the effects of TET2 overexpression were completely suppressed by STAT3 silencing in vitro. CONCLUSIONS: Our study suggests that the deficiency of TET2 in endothelial cells impairs angiogenesis via suppression of the STAT3 signaling pathway. These findings give solid evidence for TET2 to be a therapeutic alternative for ischemic diseases.

Myosin light-chain 4 gene-transfer attenuates atrial fibrosis while correcting autophagic flux dysregulation.

OBJECTIVES: To determine the role of MYL4 regulation of lysosomal function and its disturbance in fibrotic atrial cardiomyopathy. BACKGROUND: We have previously demonstrated that the atrial-specific essential light chain protein MYL4 is required for atrial contractile, electrical, and structural integrity. MYL4 mutation/dysfunction leads to atrial fibrosis, standstill, and dysrhythmia. However, the underlying pathogenic mechanisms remain unclear. METHODS AND RESULTS: Rats subjected to knock-in of a pathogenic MYL4 mutant (p.E11K) developed fibrotic atrial cardiomyopathy. Proteome analysis and single-cell RNA sequencing indicate enrichment of autophagy pathways in mutant-MYL4 atrial dysfunction. Immunofluorescence and electron microscopy revealed undegraded autophagic vesicles accumulated in MYL4p.E11K rat atrium. Next, we identified that dysfunctional MYL4 protein impairs autophagy flux in vitro and in vivo. Cardiac lysosome positioning and mobility were regulated by MYL4 in cardiomyocytes, which affected lysosomal acidification and maturation of lysosomal cathepsins. We then examined the effects of MYL4 overexpression via adenoviral gene-transfer on atrial cardiomyopathy induced by MYL4 mutation: MYL4 protein overexpression attenuated atrial structural remodeling and autophagy dysfunction. CONCLUSIONS: MYL4 regulates autophagic flux in atrial cardiomyocytes via lysosomal mobility. MYL4 overexpression attenuates MYL4 p.E11K induced fibrotic atrial cardiomyopathy, while correcting autophagy and lysosomal function. These results provide a molecular basis for MYL4-mutant induced fibrotic atrial cardiomyopathy and identify a potential biological-therapy approach for the treatment of atrial fibrosis.

A novel clinical prediction scoring system of high-altitude pulmonary hypertension.

Background: High-altitude pulmonary hypertension (HAPH) is a common disease in regions of high altitude where performing right heart catheterization (RHC) is challenging. The development of a diagnostic scoring system is crucial for effective disease screening. Methods: A total of 148 individuals were included in a retrospective analysis, and an additional 42 residents were prospectively enrolled. We conducted a multivariable analysis to identify independent predictors of HAPH. Subsequently, we devised a prediction score based on the retrospective training set to anticipate the occurrence and severity of HAPH. This scoring system was further subjected to validation in the prospective cohort, in which all participants underwent RHC. Results: This scoring system, referred to as the GENTH score model (Glycated hemoglobin [OR = 4.5], Echocardiography sign [OR = 9.1], New York Heart Association-functional class [OR = 12.5], Total bilirubin [OR = 3.3], and Hematocrit [OR = 3.6]), incorporated five independent risk factors and demonstrated strong predictive accuracy. In the training set, the area under the curve (AUC) values for predicting the occurrence and severity of HAPH were 0.851 and 0.832, respectively, while in the validation set, they were 0.841 and 0.893. In the validation set, GENTH score model cutoff values of ≤18 or >18 points were established for excluding or confirming HAPH, and a threshold of >30 points indicated severe HAPH. Conclusions: The GENTH score model, combining laboratory and echocardiography indicators, represents an effective tool for distinguishing potential HAPH patients and identifying those with severe HAPH. This scoring system improves the clinical screening of HAPH diseases and offers valuable insights into disease diagnosis and management.

Extracellular traps from activated vascular smooth muscle cells drive the progression of atherosclerosis.

Extracellular DNA traps (ETs) represent an immune response by which cells release essential materials like chromatin and granular proteins. Previous studies have demonstrated that the transdifferentiation of vascular smooth muscle cells (VSMCs) plays a crucial role in atherosclerosis. This study seeks to investigate the interaction between CD68+ VSMCs and the formation of ETs and highlight its function in atherosclerosis. Here we show that ETs are inhibited, and atherosclerotic plaque formation is alleviated in male Myh11CrePad4flox/flox mice undergoing an adeno-associated-virus-8 (AAV8) mediating overexpression of proprotein convertase subtilisin/kexin type 9 mutation (PCSK9) injection and being challenged with a high-fat diet. Obvious ETs generated from CD68+ VSMCs are inhibited by Cl-amidine and DNase I in vitro. By utilizing VSMCs-lineage tracing technology and single-cell RNA sequencing (scRNA-seq), we demonstrate that the ETs from CD68+ VSMCs influence the progress of atherosclerosis by regulating the direction of VSMCs' transdifferentiation through STING-SOCS1 or TLR4 signaling pathway.

Clinical and Predictive Value of Computed Tomography Angiography in High-Altitude Pulmonary Hypertension.

Background: High-altitude pulmonary hypertension (HAPH), as the group 3 pulmonary hypertension, has been less studied so far. The limited medical conditions in the high-altitude plateau are responsible for the delay of the clinical management of HAPH. Objectives: This study aims to identify the imaging characteristics of HAPH and explore noninvasive assessment of mean pulmonary arterial pressure (mPAP) based on computed tomography angiography (CTA). Methods: Twenty-five patients with suspected HAPH were enrolled. Right heart catheterization (RHC) and pulmonary angiography were performed. Echocardiography and CTA image data were collected for analysis. A multivariable linear regression model was fit to estimate mPAP (mPAPpredicted). A Bland-Altman plot and pathological analysis were performed to assess the diagnostic accuracy of this model. Results: Patients with HAPH showed slow blood flow and coral signs in lower lobe pulmonary artery in pulmonary arteriography, and presented trend for dilated pulmonary vessels, enlarged right atrium, and compressed left atrium in CTA (P for trend <0.05). The left lower pulmonary artery-bronchus ratio (odds ratio: 1.13) and the ratio of right to left atrial diameter (odds ratio: 1.09) were significantly associated with HAPH, and showed strong correlation with mPAPRHC, respectively (r = 0.821 and r = 0.649, respectively; all P < 0.0001). The mPAPpredicted model using left lower artery-bronchus ratio and ratio of right to left atrial diameter as covariates showed high correlation with mPAPRHC (r = 0.907; P < 0.0001). Patients with predicted HAPH also had the typical pathological changes of pulmonary hypertension. Conclusions: Noninvasive mPAP estimation model based on CTA image data can accurately fit mPAPRHC and is beneficial for the early diagnosis of HAPH.

Proanthocyanidins: Components, Pharmacokinetics and Biomedical Properties.

Proanthocyanidins (PAs) are a group of polyphenols enriched in plant and human food. In recent decades, epidemiological studies have upheld the direct relationship between PA consumption and health benefits; therefore, studies on PAs have become a research hotspot. Although the oral bioavailability of PAs is quite low, pharmacokinetics data revealed that some small molecules and colonic microbial metabolites of PAs could be absorbed and exert their health beneficial effects. The pharmacological effects of PAs mainly include anti-oxidant, anticancer, anti-inflammation, antimicrobial, cardiovascular protection, neuroprotection, and metabolism-regulation behaviors. Moreover, current toxicological studies show that PAs have no observable toxicity to humans. This review summarizes the resources, extraction, structures, pharmacokinetics, pharmacology, and toxicology of PAs and discusses the limitations of current studies. Areas for further research are also proposed.