Characterizing the cellular and molecular variabilities of peripheral immune cells in healthy recipients of BBIBP-CorV inactivated SARS-CoV-2 vaccine by single-cell RNA sequencing.

Over 3 billion doses of inactivated vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been administered globally. However, our understanding of the immune cell functional transcription and T cell receptor (TCR)/B cell receptor (BCR) repertoire dynamics following inactivated SARS-CoV-2 vaccination remains poorly understood. Here, we performed single-cell RNA and TCR/BCR sequencing on peripheral blood mononuclear cells at four time points after immunization with the inactivated SARS-CoV-2 vaccine BBIBP-CorV. Our analysis revealed an enrichment of monocytes, central memory CD4+ T cells, type 2 helper T cells and memory B cells following vaccination. Single-cell TCR-seq and RNA-seq comminating analysis identified a clonal expansion of CD4+ T cells (but not CD8+ T cells) following a booster vaccination that corresponded to a decrease in the TCR diversity of central memory CD4+ T cells and type 2 helper T cells. Importantly, these TCR repertoire changes and CD4+ T cell differentiation were correlated with the biased VJ gene usage of BCR and the antibody-producing function of B cells post-vaccination. Finally, we compared the functional transcription and repertoire dynamics in immune cells elicited by vaccination and SARS-CoV-2 infection to explore the immune responses under different stimuli. Our data provide novel molecular and cellular evidence for the CD4+ T cell-dependent antibody response induced by inactivated vaccine BBIBP-CorV. This information is urgently needed to develop new prevention and control strategies for SARS-CoV-2 infection. (ClinicalTrials.gov Identifier: NCT04871932).

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.

Nuclear receptor Nur77 protects against oxidative stress by maintaining mitochondrial homeostasis via regulating mitochondrial fission and mitophagy in smooth muscle cell.

Angiotensin II (AngII) induces disruption of mitochondrial homeostasis and oxidative stress. Nuclear receptor NR4A1 (Nur77) plays an important role in vascular smooth muscle cells (VSMCs) function. However, the role of Nur77 in AngII-induced mitochondrial dynamics and oxidative stress in VSMCs remains unknown. In an in vitro model of AngII-treated cells, we discovered that Nur77 knockout aggravated AngII-induced oxidative stress in VSMCs, whereas activation of Nur77 by celastrol diminished them. Concomitantly, disturbance of mitochondrial dynamics induced by AngII was further exacerbated in Nur77 deficient VSMCs compared to wild-type (WT) VSMCs. Interestingly, Nur77 deletion increased mitochondrial fission but not fusion as evidenced by upregulated fission related genes (Fis1 and Drp1) but not fusion (Opa1 and Mfn2) under AngII stimulation in VSMCs. Mechanically, Nur77 could directly bind to the promoter regions of Fis1 and Drp1 and repress their transcription. Furthermore, we observed that Nur77 additionally promoted mitochondrial homeostasis by increasing mitophagic flux in a transcription-independent manner upon AngII challenge. By using an in vivo model of AngII-induced abdominal aortic aneurysm (AAA), we finally validated the protective role of Nur77 involved in the mitochondrial fission process and mitophagic flux in aortas, which was correlated with the occurrence and development of AAA in AngII-infused mice. Our data defines an essential role of Nur77 in regulating oxidative stress by maintaining mitochondrial homeostasis in VSMCs via both transcription-dependent and transcription-independent manner, supporting the therapeutic potential of Nur77 targeting in vascular diseases.

Reduced Notch1 Cleavage Promotes the Development of Pulmonary Hypertension.

Clinical trials of Dll4 (Delta-like 4) neutralizing antibodies (Dll4nAbs) in cancer patients are ongoing. Surprisingly, pulmonary hypertension (PH) occurs in 14% to 18% of patients treated with Dll4nAbs, but the mechanisms have not been studied. Here, PH progression was measured in mice treated with Dll4nAbs. We detected Notch signaling in lung tissues and analyzed pulmonary vascular permeability and inflammation. Notch target gene array was performed on adult human pulmonary microvascular endothelial cells (ECs) after inhibiting Notch cleavage. Similar mechanisms were studied in PH mouse models and pulmonary arterial hypertension patients. The rescue effects of constitutively activated Notch1 in vivo were also measured. We observed that Dll4nAbs induced PH in mice as indicated by significantly increased right ventricular systolic pressure, as well as pulmonary vascular and right ventricular remodeling. Mechanistically, Dll4nAbs inhibited Notch1 cleavage and subsequently impaired lung endothelial barrier function and increased immune cell infiltration in vessel walls. In vitro, Notch targeted genes' expression related to cell growth and inflammation was decreased in human pulmonary microvascular ECs after the Notch1 inactivation. In lungs of PH mouse models and pulmonary arterial hypertension patients, Notch1 cleavage was inhibited. Consistently, EC cell-cell junction was leaky, and immune cell infiltration increased in PH mouse models. Overexpression activated Notch1-attenuated progression of PH in mice. In conclusion, Dll4nAbs led to PH development in mice by impaired EC barrier function and increased immune cell infiltration through inhibition of Notch1 cleavage in lung ECs. Reduced Notch1 cleavage in lung ECs could be an underlying mechanism of PH pathogenesis.

A novel peptide inhibitor of Dll4-Notch1 signalling and its pro-angiogenic functions.

BACKGROUND AND PURPOSE: The Dll4-Notch1 signalling pathway plays an important role in sprouting angiogenesis, vascular remodelling and arterial or venous specificity. Genetic or pharmacological inhibition of Dll4-Notch1 signalling leads to excessive sprouting angiogenesis. However, transcriptional inhibitors of Dll4-Notch1 signalling have not been described. EXPERIMENTAL APPROACH: We designed a new peptide targeting Notch signalling, referred to as TAT-ANK, and assessed its effects on angiogenesis. In vitro, tube formation and fibrin gel bead assay were carried out, using human umbilical vein endothelial cells (HUVECs). In vivo, Matrigel plug angiogenesis assay, a developmental retinal model and tumour models in mice were used. The mechanisms underlying TAT-ANK activity were investigated by immunochemistry, western blotting, immunoprecipitation, RT-qPCR and luciferase reporter assays. KEY RESULTS: The amino acid residues 179-191 in the G-protein-coupled receptor-kinase-interacting protein-1 (GIT1-ankyrin domain) are crucial for GIT1 binding to the Notch transcription repressor, RBP-J. We designed the peptide TAT-ANK, based on residues 179-191 in GIT1. TAT-ANK significantly inhibited Dll4 expression and Notch 1 activation in HUVECs by competing with activated Notch1 to bind to RBP-J. The analyses of biological functions showed that TAT-ANK promoted angiogenesis in vitro and in vivo by inhibiting Dll4-Notch1 signalling. CONCLUSIONS AND IMPLICATIONS: We synthesized and investigated the biological actions of TAT-ANK peptide, a new inhibitor of Notch signalling. This peptide will be of significant interest to research on Dll4-Notch1 signalling and to clinicians carrying out clinical trials using Notch signalling inhibitors. Furthermore, our findings will have important conceptual and therapeutic implications for angiogenesis-related diseases.

Associations of Walking Activity With Hypertensive Mediated Organ Damage in Community-Dwelling Elderly Chinese: The Northern Shanghai Study.

Background: Walking, as the most common campaign in older people, is recommended to improve their cardiovascular health. However, the direct association between weekly walking activity and asymptomatic hypertensive mediated organ damage (HMOD) remains unclear. Methods: 2,830 community-dwelling elderly subjects (over 65 years) in northern Shanghai were recruited from 2014 to 2018. Weekly walking activity was assessed by International Physical Activity Questionnaires (IPAQ). Within the framework of comprehensive cardiovascular examinations, HMOD, including left ventricular mass index, peak transmitral pulsed Doppler velocity/early diastolic tissue Doppler velocity, creatinine clearance rate, urinary albumin-creatinine ratio, carotid-femoral pulse wave velocity (cf-PWV), carotid intima-media thickness (CIMT), arterial plaque, and ankle-brachial index (ABI), were all evaluated. Results: 1,862 (65.8%) participants with weekly walking activity showed lower CIMT, lower cf-PWV, fewer abnormal ABI, and lower prevalence of hypertension and coronary heart disease (p < 0.05). Walking activity was negatively correlated with age and smokers (correlation coefficient: -0.066, -0.042; both p < 0.05). After adjusting for cardiovascular risk factors and concomitant diseases, walking activity was significantly associated with better indicator of most vascular HMOD in multivariate logistic regressions, including arterial stiffness [odds ratio (OR) = 0.75, p = 0.01], increased CIMT (OR = 0.70, p = 0.03), and peripheral artery disease (OR = 0.72, p = 0.005), but not cardiac or renal HMOD. Subgroup analysis further showed that walking duration ≥1 h/day was significantly associated with decreased risk of most vascular HMOD after adjustment for confounders and moderate-to-vigorous physical activity based on IPAQ (all p < 0.05). Conclusions: In the community-dwelling elderly Chinese, there was a significant negative association of weekly walking activity with vascular HMOD, but not cardiac or renal HMOD. Increased daily walking duration, but not walking frequency, was significantly associated with improved vascular HMOD. Hence, increasing daily walking duration seems to encourage a healthy lifestyle in terms of vascular protection. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT02368938.

Nuclear Receptor Nur77 Protects Against Abdominal Aortic Aneurysm by Ameliorating Inflammation Via Suppressing LOX-1.

Background Abdominal aortic aneurysm (AAA) is a life-threatening vascular disorder characterized by chronic inflammation of the aortic wall, which lacks effective pharmacotherapeutic remedies and has an extremely high mortality. Nuclear receptor NR4A1 (Nur77) functions in various chronic inflammatory diseases. However, the influence of Nur77 on AAA has remained unclear. Herein, we sought to determine the effects of Nur77 on the development of AAA. Methods and Results We observed that Nur77 expression decreased significantly in human and mice AAA lesions. Deletion of Nur77 accelerated the development of AAA in mice, as evidenced by increased AAA incidence, abdominal aortic diameters, elastin fragmentation, and collagen content. Consistent with genetic manipulation, pharmacological activation of Nur77 by celastrol showed beneficial effects against AAA. Microscopic and molecular analyses indicated that the detrimental effects of Nur77 deficiency were associated with aggravated macrophage infiltration in AAA lesions and increased pro-inflammatory cytokines secretion and matrix metalloproteinase (MMP-9) expression. Bioinformatics analyses further revealed that LOX-1 was upregulated by Nur77 deficiency and consequently increased the expression of cytokines and MMP-9. Moreover, rescue experiments verified that LOX-1 notably aggravated inflammatory response, an effect that was blunted by Nur77. Conclusions This study firstly demonstrated a crucial role of Nur77 in the formation of AAA by targeting LOX-1, which implicated Nur77 might be a potential therapeutic target for AAA.

Rare Pulmonary Connective Tissue Type Mast Cells Regulate Lung Endothelial Cell Angiogenesis.

Within the human lung, mast cells typically reside adjacent to the conducting airway and assume a mucosal phenotype (MCT). In rare pathologic conditions, connective tissue phenotype mast cells (MCTCs) can be found in the lung parenchyma. MCTCs accumulate in the lungs of infants with severe bronchopulmonary dysplasia, a chronic lung disease associated with preterm birth, which is characterized by pulmonary vascular dysmorphia. The human mast cell line (LUVA) was used to model MCTCs or MCTs. The ability of MCTCs to affect vascular organization during fetal lung development was tested in mouse lung explant cultures. The effect of MCTCs on in vitro tube formation and barrier function was studied using primary fetal human pulmonary microvascular endothelial cells. The mechanistic role of MCTC proteases was tested using inhibitors. MCTCLUVA but not MCTLUVA was associated with vascular dysmorphia in lung explants. In vitro, the addition of MCTCLUVA potentiated fetal human pulmonary microvascular endothelial cell interactions, inhibited tube stability, and disrupted endothelial cell junctions. Protease inhibitors ameliorated the ability of MCTCLUVA to alter endothelial cell angiogenic activities in vitro and ex vivo. These data indicate that MCTCs may directly contribute to disrupted angiogenesis in bronchopulmonary dysplasia. A better understanding of factors that regulate mast cell subtype and their different effector functions is essential.

SENCR stabilizes vascular endothelial cell adherens junctions through interaction with CKAP4.

SENCR is a human-specific, vascular cell-enriched long-noncoding RNA (lncRNA) that regulates vascular smooth muscle cell and endothelial cell (EC) phenotypes. The underlying mechanisms of action of SENCR in these and other cell types is unknown. Here, levels of SENCR RNA are shown to be elevated in several differentiated human EC lineages subjected to laminar shear stress. Increases in SENCR RNA are also observed in the laminar shear stress region of the adult aorta of humanized SENCR-expressing mice, but not in disturbed shear stress regions. SENCR loss-of-function studies disclose perturbations in EC membrane integrity resulting in increased EC permeability. Biotinylated RNA pull-down and mass spectrometry establish an abundant SENCR-binding protein, cytoskeletal-associated protein 4 (CKAP4); this ribonucleoprotein complex was further confirmed in an RNA immunoprecipitation experiment using an antibody to CKAP4. Structure-function studies demonstrate a noncanonical RNA-binding domain in CKAP4 that binds SENCR Upon SENCR knockdown, increasing levels of CKAP4 protein are detected in the EC surface fraction. Furthermore, an interaction between CKAP4 and CDH5 is enhanced in SENCR-depleted EC. This heightened association appears to destabilize the CDH5/CTNND1 complex and augment CDH5 internalization, resulting in impaired adherens junctions. These findings support SENCR as a flow-responsive lncRNA that promotes EC adherens junction integrity through physical association with CKAP4, thereby stabilizing cell membrane-bound CDH5.