PARP-1 (Poly[ADP-Ribose] Polymerase 1) Inhibition Protects From Ang II (Angiotensin II)-Induced Abdominal Aortic Aneurysm in Mice

Regulated vascular smooth muscle cell death in vascular diseases

Regulated cell death (RCD) is a complex process that involves several cell types and plays a crucial role in vascular diseases. Vascular smooth muscle cells (VSMCs) are the predominant elements of the medial layer of blood vessels, and their regulated death contributes to the pathogenesis of vascular diseases. The types of regulated VSMC death include apoptosis, necroptosis, pyroptosis, ferroptosis, parthanatos, and autophagy-dependent cell death (ADCD). In this review, we summarize the current evidence of regulated VSMC death pathways in major vascular diseases, such as atherosclerosis, vascular calcification, aortic aneurysm and dissection, hypertension, pulmonary arterial hypertension, neointimal hyperplasia, and inherited vascular diseases. All forms of RCD constitute a single, coordinated cell death system in which one pathway can compensate for another during disease progression. Pharmacologically targeting RCD pathways has potential for slowing and reversing disease progression, but challenges remain. A better understanding of the role of regulated VSMC death in vascular diseases and the underlying mechanisms may lead to novel pharmacological developments and help clinicians address the residual cardiovascular risk in patients with cardiovascular diseases.

Exploring the role of parthanatos in CNS injury: Molecular insights and therapeutic approaches

BACKGROUND

Central nervous system (CNS) injury causes severe organ damage due to both damage resulting from the injury and subsequent cell death. However, there are currently no effective treatments for countering the irreversible loss of cell function. Parthanatos is a poly (ADP-ribose) polymerase 1 (PARP-1)-dependent form of programmed cell death that is partly responsible for neural cell death. Consequently, the mechanism by which parthanatos promotes CNS injury has attracted significant scientific interest.

AIM OF REVIEW

Our review aims to summarize the potential role of parthanatos in CNS injury and its molecular and pathophysiological mechanisms. Understanding the role of parthanatos and related molecules in CNS injury is crucial for developing effective treatment strategies and identifying important directions for future in-depth research.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Parthanatos (from Thanatos, the personification of death according to Greek mythology) is a type of programmed cell death that is initiated by the overactivation of PARP-1. This process triggers a cascade of reactions, including the accumulation of poly(ADP-ribose) (PAR), the nuclear translocation of apoptosis-inducing factor (AIF) after its release from mitochondria, and subsequent massive DNA fragmentation caused by migration inhibitory factor (MIF) forming a complex with AIF. Secondary molecular mechanisms, such as excitotoxicity and oxidative stress-induced overactivation of PARP-1, significantly exacerbate neuronal damage following initial mechanical injury to the CNS. Furthermore, parthanatos is not only associated with neuronal damage but also interacts with various other types of cell death. This review focuses on the latest research concerning the parthanatos cell death pathway, particularly considering its regulatory mechanisms and functions in CNS damage. We highlight the associations between parthanatos and different cell types involved in CNS damage and discuss potential therapeutic agents targeting the parthanatos pathway.

Rolipram impacts on redox homeostasis and cellular signaling in an experimental model of abdominal aortic aneurysm

INTRODUCTION

Cyclic nucleotide phosphodiesterases (PDEs) of the PDE4 subfamily are responsible for the hydrolysis and subcellular compartmentalization of cAMP, a second messenger that modulates vascular functionality. We had shown that PDE4B is induced in abdominal aortic aneurysms (AAA) and that PDE4 inhibition by rolipram limits experimental aneurysms. In this study we have delved into the mechanisms underlying the beneficial effect of rolipram on AAA.

METHODS

AAA were induced in ApoE-/- mice by angiotensin II (Ang II) infusion. Aneurysm formation was evaluated by ultrasonography. The expression of enzymes involved in rédox homeostasis was analyzed by real-time RT-PCR and the activation of signaling pathways by Western blot.

RESULTS

Induction of PDE4B in human AAA has been confirmed in a second cohort of patients. In Ang II-infused ApoE-/- mice, rolipram increased the percentage of animals free of aneurysms without affecting the percentage of aortic ruptures. Quantitative analyses determined that this drug significantly attenuated aortic collagen deposition. Additionally, rolipram reduced the increased Nox2 expression triggered by Ang II, exacerbated Sod1 induction, and normalized Sod3 expression. Likewise, PDE4 inhibition decreased the activation of both ERK1/2 and the canonical Wnt pathway, while AKT activity was not altered.

CONCLUSIONS

The inhibition of PDE4 activity modulates the expression of enzymes involved in rédox homeostasis and affects cell signaling pathways involved in the development of AAA.

Mechanisms of chondrocyte regulated cell death in osteoarthritis: Focus on ROS-triggered ferroptosis, parthanatos, and oxeiptosis

Osteoarthritis (OA) is a common chronic inflammatory degenerative disease. Since chondrocytes are the only type of cells in cartilage, their survival is critical for maintaining cartilage morphology. This review offers a comprehensive analysis of how reactive oxygen species (ROS), including superoxide anions, hydrogen peroxide, hydroxyl radicals, nitric oxide, and their derivatives, affect cartilage homeostasis and trigger several novel modes of regulated cell death, including ferroptosis, parthanatos, and oxeiptosis, which may play roles in chondrocyte death and OA development. Moreover, we discuss potential therapeutic strategies to alleviate OA by scavenging ROS and provide new insight into the research and treatment of the role of regulated cell death in OA.

Association between CHFR and PARP-1, and Their Roles in Regulation of Proliferation and Apoptosis of B Cell Lymphoma

Background. Aberrant methylation of checkpoint with forkhead and ring finger domains (CHFR) was found in B-cell non-Hodgkin lymphoma (NHL), whereas its role in carcinogenesis is not clear. CHFR can control poly (ADP-ribose) polymerase levels by causing its degradation. The study was aimed to explore the roles and mechanisms of CHFR in the pathogenesis of B-cell NHL. Methods. Short hairpin ribonucleic acid (ShRNAs) targeting CHFR and poly (ADP-ribose) polymerase 1 (PARP-1) were transduced into Raji cells, and real-time polymerase chain reaction (PCR) and western blotting were carried out to determine their expression. Afterwards, the CCK-8 assay and flow cytometry were used to evaluate the cell growth and apoptosis. Tumor size and weight were determined using a xenograft model, and decitabine (5-Aza-dC) was used to further determine the methylation status of CHFR through a methylation specificity-PCR assay. Results. 5-Aza-dC-treatment promoted the expression of CHFR and decreased the expression of PARP-1 at both messenger ribonucleic acid (mRNA) and protein levels. 5-Aza-dC also accelerated Raji-cell apoptosis and restrained its growth in vitro and in vivo ( $P<0.05$ ). These results were contrary to those observed in the shRNA-CHFR group but consistent with those observed in the shRNA-PARP-1 group. The expression profiles of CHFR and PARP-1 in the xenograft model were consistent with those in the cellular model. Treatment with 5-Aza-dC led to demethylation of CHFR in nude mice. Besides, there may be a negative correlation between CHFR and PARP-1 in B-cell NHL cells. Conclusion. Our findings indicated that 5-Aza-dC could lead to the demethylation of the CHFR promoter and suppress Raji cell growth.

Investigation of the Pathogenic Mechanism of Ciprofloxacin in Aortic Aneurysm and Dissection by an Integrated Proteomics and Network Pharmacology Strategy

Aortic aneurysm and dissection (AAD) is a life-threatening disease worldwide. Recently, fluoroquinolones have been reported to significantly increase the risk of AAD. This study aimed to investigate the potential functional mechanism and molecular targets of fluoroquinolones in relation to AAD by an integrated proteomic and network pharmacology strategy. A total of 1351 differentially expressed proteins were identified in human aortic vascular smooth muscle cells (VSMCs) after ciprofloxacin (CIP) stimulation. The functional analysis emphasized the important roles of metabolism, extracellular matrix homeostasis, mitochondrial damage, focal adhesion, and apoptosis in CIP-stimulated VSMCs. CIP targets were predicted with online databases and verified by molecular docking. Protein-protein interaction (PPI) analysis and module construction of the 34 potential CIP targets and 37 selected hub molecules after CIP stimulation identified four critical target proteins in the module: PARP1, RAC1, IGF1R and MKI67. Functional analysis of the PPI module showed that the MAPK signalling pathway, focal adhesion, apoptosis, regulation of actin cytoskeleton, and PI3K-Akt signalling pathway were significantly enriched. Our results will provide novel insights into the pathogenic mechanism of fluoroquinolones in aortic diseases.

DNA damage response signaling: A common link between cancer and cardiovascular diseases

DNA damage response (DDR) signaling ensures genomic and proteomic homeostasis to maintain a healthy genome. Dysregulation either in the form of down- or upregulation in the DDR pathways correlates with various pathophysiological states, including cancer and cardiovascular diseases (CVDs). Impaired DDR is studied as a signature mechanism for cancer; however, it also plays a role in ischemia-reperfusion injury (IRI), inflammation, cardiovascular function, and aging, demonstrating a complex and intriguing relationship between cancer and pathophysiology of CVDs. Accordingly, there are increasing number of reports indicating higher incidences of CVDs in cancer patients. In the present review, we thoroughly discuss (1) different DDR pathways, (2) the functional cross talk among different DDR mechanisms, (3) the role of DDR in cancer, (4) the commonalities and differences of DDR between cancer and CVDs, (5) the role of DDR in pathophysiology of CVDs, (6) interventional strategies for targeting genomic instability in CVDs, and (7) future perspective.

Loss of myeloid Tsc2 predisposes to angiotensin II-induced aortic aneurysm formation in mice

RATIONALE

Genetic studies have proved the involvement of Tuberous sclerosis complex subunit 2 (Tsc2) in aortic aneurysm. However, the exact role of macrophage Tsc2 in the vascular system remains unclear. Here, we examined the potential function of macrophage Tsc2 in the development of aortic remodeling and aortic aneurysms.

METHODS AND RESULTS

Conditional gene knockout strategy combined with histology and whole-transcriptomic analysis showed that Tsc2 deficiency in macrophages aggravated the progression of aortic aneurysms along with an upregulation of proinflammatory cytokines and matrix metallopeptidase-9 in the angiotensin II-induced mouse model. G protein-coupled receptor 68 (Gpr68), a proton-sensing receptor for detecting the extracellular acidic pH, was identified as the most up-regulated gene in Tsc2 deficient macrophages compared with control macrophages. Additionally, Tsc2 deficient macrophages displayed higher glycolysis and glycolytic inhibitor 2-deoxy-D-glucose treatment partially attenuated the level of Gpr68. We further demonstrated an Tsc2-Gpr68-CREB network in macrophages that regulates the inflammatory response, proteolytic degradation and vascular homeostasis. Gpr68 inhibition largely abrogated the progression of aortic aneurysms caused by Tsc2 deficiency in macrophages.

CONCLUSIONS

The findings reveal that Tsc2 deficiency in macrophages contributes to aortic aneurysm formation, at least in part, by upregulating Gpr68 expression, which subsequently drives proinflammatory processes and matrix metallopeptidase activation. The data also provide a novel therapeutic strategy to limit the progression of the aneurysm resulting from Tsc2 mutations.

ROS-triggered endothelial cell death mechanisms: Focus on pyroptosis, parthanatos, and ferroptosis

The endothelium is a single layer of epithelium covering the surface of the vascular system, and it represents a physical barrier between the blood and vessel wall that plays an important role in maintaining intravascular homeostasis. However, endothelial dysfunction or endothelial cell death can cause vascular barrier disruption, vasoconstriction and diastolic dysfunction, vascular smooth muscle cell proliferation and migration, inflammatory responses, and thrombosis, which are closely associated with the progression of several diseases, such as atherosclerosis, hypertension, coronary atherosclerotic heart disease, ischemic stroke, acute lung injury, acute kidney injury, diabetic retinopathy, and Alzheimer's disease. Oxidative stress caused by the overproduction of reactive oxygen species (ROS) is an important mechanism underlying endothelial cell death. Growing evidence suggests that ROS can trigger endothelial cell death in various ways, including pyroptosis, parthanatos, and ferroptosis. Therefore, this review will systematically illustrate the source of ROS in endothelial cells (ECs); reveal the molecular mechanism by which ROS trigger pyroptosis, parthanatos, and ferroptosis in ECs; and provide new ideas for the research and treatment of endothelial dysfunction-related diseases.

Insulin-like growth factor binding protein 7 promotes acute kidney injury by alleviating poly ADP ribose polymerase 1 degradation

The novel biomarker, insulin-like growth factor binding protein 7 (IGFBP7), is used clinically to predict different types of acute kidney injury (AKI) and has drawn significant attention as a urinary biomarker. However, as a secreted protein in the circulation of patients with AKI, it is unclear whether IGFBP7 acts as a key regulator in AKI progression, and if mechanisms underlying its upregulation still need to be determined. Here we found that IGFBP7 is highly expressed in the blood and urine of patients and mice with AKI possibly via a c-Jun-dependent mechanism, and is positively correlated with kidney dysfunction. Global knockout of IGFBP7 ameliorated kidney dysfunction, inflammatory responses, and programmed cell death in murine models of cisplatin-, kidney ischemia/reperfusion-, and lipopolysaccharide-induced AKI. IGFBP7 mainly originated from kidney tubular epithelial cells. Conditional knockout of IGFBP7 from the kidney protected against AKI. By contrast, rescue of IGFBP7 expression in IGFBP7-knockout mice restored kidney damage and inflammation. IGFBP7 function was determined in vitro using recombinant IGFBP7 protein, IGFBP7 knockdown, or overexpression. Additionally, IGFBP7 was found to bind to poly [ADP-ribose] polymerase 1 (PARP1) and inhibit its degradation by antagonizing the E3 ubiquitin ligase ring finger protein 4 (RNF4). Thus, IGFBP7 in circulation acts as a biomarker and key mediator of AKI by inhibiting RNF4/PARP1-mediated tubular injury and inflammation. Hence, over-activation of the IGFBP7/PARP1 axis represents a promising target for AKI treatment.

Exploring the Effect and Mechanism of Si-Miao-Yong-An Decoction on Abdominal Aortic Aneurysm Based on Mice Experiment and Bioinformatics Analysis

Background

Abdominal aortic aneurysm (AAA) is a fatal disease characterized by high morbidity and mortality in old population. Globally, effective drugs for AAA are still limited. Si-Miao-Yong-An decoction (SMYAD), a traditional Chinese medicine (TCM) formula with a high medical value, was reported to be successfully used in an old AAA patient. Thus, we reason that SMYAD may serve as a potential anti-AAA regime.

Objective

The exact effects and detailed mechanisms of SMYAD on AAA were explored by using the experimental study and bioinformatics analysis.

Methods

Firstly, C57BL/6N mice induced by Bap and Ang II were utilized to reproduce the AAA model, and the effects of SMYAD were systematically assessed according to histology, immunohistochemistry, and enzyme-linked immunosorbent assay (ELISA). Then, network pharmacology was applied to identify the biological processes, pathways, and hub targets of SMYAD against AAA; moreover, molecular docking was utilized to identify the binding ability and action targets.

Results

In an animal experiment, SMYAD was found to effectively alleviate the degree of pathological expansion of abdominal aorta and reduce the incidence of Bap/Ang II-induced AAA, along with reducing the damage to elastic lamella, attenuating infiltration of macrophage, and lowering the circulating IL-6 level corresponding to the animal study, and network pharmacology revealed the detailed mechanisms of SMYAD on AAA that were related to pathways of inflammatory response, defense response, apoptotic, cell migration and adhesion, and reactive oxygen species metabolic process. Then, seven targets, IL-6, TNF, HSP90AA1, RELA, PTGS2, ESR1, and MMP9, were identified as hub targets of SMYAD against AAA. Furthermore, molecular docking verification revealed that the active compounds of SMYAD had good binding ability and clear binding site with core targets related to AAA formation.

Conclusion

SMYAD can suppress AAA development through multicompound, multitarget, and multipathway, which provides a research direction for further study.

Adventitial Fibroblasts in Aortic Aneurysm: Unraveling Pathogenic Contributions to Vascular Disease

Aortic aneurysm (AA) is a degenerative vascular disease that involves aortic dilatation, and, if untreated, it can lead to rupture. Despite its significant impact on the healthcare system, its multifactorial nature and elusive pathophysiology contribute to limited therapeutic interventions that prevent the progression of AA. Thus, further research into the mechanisms underlying AA is paramount. Adventitial fibroblasts are one of the key constituents of the aortic wall, and they play an essential role in maintaining vessel structure and function. However, adventitial fibroblasts remain understudied when compared with endothelial cells and smooth muscle cells. Adventitial fibroblasts facilitate the production of extracellular matrix (ECM), providing structural integrity. However, during biomechanical stress and/or injury, adventitial fibroblasts can be activated into myofibroblasts, which move to the site of injury and secrete collagen and cytokines, thereby enhancing the inflammatory response. The overactivation or persistence of myofibroblasts has been shown to initiate pathological vascular remodeling. Therefore, understanding the underlying mechanisms involved in the activation of fibroblasts and in regulating myofibroblast activation may provide a potential therapeutic target to prevent or delay the progression of AA. This review discusses mechanistic insights into myofibroblast activation and associated vascular remodeling, thus illustrating the contribution of fibroblasts to the pathogenesis of AA.

OUP accepted manuscript

Cardiovascular diseases (CVDs) arise from a complex interplay among genomic, proteomic, and metabolomic abnormalities. Emerging evidence has recently consolidated the presence of robust DNA damage in a variety of cardiovascular disorders. DNA damage triggers a series of cellular responses termed DNA damage response (DDR) including detection of DNA lesions, cell cycle arrest, DNA repair, cellular senescence, and apoptosis, in all organ systems including hearts and vasculature. Although transient DDR in response to temporary DNA damage can be beneficial for cardiovascular function, persistent activation of DDR promotes the onset and development of CVDs. Moreover, therapeutic interventions that target DNA damage and DDR have the potential to attenuate cardiovascular dysfunction and improve disease outcome. In this review, we will discuss molecular mechanisms of DNA damage and repair in the onset and development of CVDs, and explore how DDR in specific cardiac cell types contributes to CVDs. Moreover, we will highlight the latest advances regarding the potential therapeutic strategies targeting DNA damage signalling in CVDs.

Targeting regulated cell death in aortic aneurysm and dissection therapy

Regulated cell death (RCD) is a basic biological phenomenon associated with cell and tissue homeostasis. Recent studies have enriched our understanding of RCD, and many novel cell death types, such as ferroptosis and pyroptosis, have been discovered and defined. Aortic aneurysm and dissection (AAD) is a life-threatening condition, but the pathogenesis remains largely unclear. A series of studies have indicated that the death of smooth muscle cells, endothelial cells and inflammatory cells participates in the development of AAD and that corresponding interventions could alleviate disease progression. Many treatments against cell death have been used to impede the process of AAD in vitro and in vivo, which provides strategies to protect against this condition. In this review, we focus on various types of regulated cell death and provide a framework of their roles in AAD, and the information contributes to further exploration of the molecular mechanisms of AAD.

Cellular and Molecular Mechanism of Traditional Chinese Medicine on Ventricular Remodeling

Ventricular remodeling is related to the renin-angiotensin-aldosterone system, immune system, and various cytokines involved in inflammation, apoptosis, and cell signal regulation. Accumulated studies have shown that traditional Chinese medicine can significantly inhibit the process of ventricular remodeling, which may be related to the mechanism mentioned above. Here, we conducted a system overview to critically review the cellular and molecular mechanism of traditional Chinese medicine on ventricular remodeling. We mainly searched PubMed for basic research about the anti-ventricular remodeling of traditional Chinese medicine in 5 recent years, and then objectively summarized these researches. We included more than 25 kinds of Chinese herbal medicines including Qi-Li-Qian-Xin, Qi-Shen-Yi-Qi Pill, Xin-Ji-Er-Kang Formula, and Yi-Qi-Wen-Yang Decoction, and found that they can inhibit ventricular remodeling effectively through multi-components and multi-action targets, which are promoting the clinical application of traditional Chinese medicine.

Angiotensin II is a crucial factor in retinal aneurysm formation

Retinal arterial macroaneurysms are characterized by the acquired fusiform or saccular dilatations of the retinal artery. Angiotensin II (Ang II) is a major signal molecule of the renin-angiotensin system, which exerts a range of pathogenic actions that are relevant to retinal vascular abnormalities. We aimed to study the effect of Ang II on retinal vessels and explore its relationship with retinal aneurysmal disease. C57BL/6J male mice were administered Ang II at 1000 ng/kg/min for 28 days, and the mice given saline served as controls. The mice in the treatment group were treated once daily by gastric gavage of candesartan cilexetil (an antagonist of Ang II type 1 (AT1) receptor) at 100 mg/kg/day. The in vivo imaging of murine retinas was performed using fundus photography, optical coherence tomography, fluorescein angiography, and indocyanine green angiography at 7th, 14th, and 28th days of infusion. At the end of the infusion and treatment, the morphological changes were evaluated by histopathological examination and electron microscopy; the levels of related proteins in murine retinas were examined by antibody array and Western blot analyses. We found that Ang II infusion induced aneurysm formation in mice retina, which presented as either solitary aneurysms or retinal arterial beading. The aneurysm formation was often accompanied with vessel leakage. Moreover, Ang II infusion itself may result in increased vascular permeability and ganglion cell and inner plexiform layer thickening. The blockade of AT1 receptors by systemic administration of candesartan cilexetil alleviated the Ang II-induced retinal vasculopathy. The protein level analysis further showed that Ang II upregulated IL-1β, PDGFR-β, and MMP-9 expression, and the expression of IL-1β could be inhibited by AT1 receptor antagonist. Our study provides evidence that Ang II is a crucial factor in retinal aneurysm formation and vessel leakage. It is probably the combined effect of Ang II on vessel inflammatory response, pericyte function, and extracellular matrix remodeling that predisposes the retinal arterial wall to aneurysm formation and blood-retinal barrier breakdown.

Cardiovascular angiotensin II type 1 receptor biased signaling: Focus on non-Gq-, non-βarrestin-dependent signaling

The physiological and pathophysiological roles of the angiotensin II type 1 (AT₁) receptor, a G protein-coupled receptor ubiquitously expressed throughout the cardiovascular system, have been the focus of intense investigations for decades. The success of angiotensin converting enzyme inhibitors (ACEIs) and of angiotensin receptor blockers (ARBs), which are AT₁R-selective antagonists/inverse agonists, in the treatment of heart disease is a testament to the importance of this receptor for cardiovascular homeostasis. Given the pleiotropic signaling of the cardiovascular AT₁R and, in an effort to develop yet better drugs for heart disease, the concept of biased signaling has been exploited to design and develop biased AT₁R ligands that selectively activate β-arrestin transduction pathways over G_q protein-dependent pathways. However, by focusing solely on G_q or β-arrestins, studies on AT₁R "biased" signaling & agonism tend to largely ignore other non-Gq-, non β-arrestin-dependent signaling modalities the very versatile AT₁R employs in cardiovascular tissues, including two very important types of signal transducers/regulators: other G protein types (e.g., G_i/o, G_12/13) & the Regulator of G protein Signaling (RGS) proteins. In this review, we provide a brief overview of the current state of cardiovascular AT₁R biased signaling field with a special focus on the non-Gq-, non β-arrestin-dependent signaling avenues of this receptor in the cardiovascular system, which usually get left out of the conversation of "biased" AT₁R signal transduction.

Hypertension-induced cognitive impairment: from pathophysiology to public health

Hypertension affects two-thirds of people aged >60 years and significantly increases the risk of both vascular cognitive impairment and Alzheimer's disease. Hypertension compromises the structural and functional integrity of the cerebral microcirculation, promoting microvascular rarefaction, cerebromicrovascular endothelial dysfunction and neurovascular uncoupling, which impair cerebral blood supply. In addition, hypertension disrupts the blood-brain barrier, promoting neuroinflammation and exacerbation of amyloid pathologies. Ageing is characterized by multifaceted homeostatic dysfunction and impaired cellular stress resilience, which exacerbate the deleterious cerebromicrovascular effects of hypertension. Neuroradiological markers of hypertension-induced cerebral small vessel disease include white matter hyperintensities, lacunar infarcts and microhaemorrhages, all of which are associated with cognitive decline. Use of pharmaceutical and lifestyle interventions that reduce blood pressure, in combination with treatments that promote microvascular health, have the potential to prevent or delay the pathogenesis of vascular cognitive impairment and Alzheimer's disease in patients with hypertension.

Deacetylation-dependent regulation of PARP1 by SIRT2 dictates ubiquitination of PARP1 in oxidative stress-induced vascular injury

Poly(ADP-ribose) polymerase 1 (PARP1) has a major regulatory role in cardiovascular disease. However, inhibiting PARP1 activity does not significantly improve clinical outcomes of cardiovascular disease, which suggests that the regulatory mechanism of PARP1 in cardiovascular disease is unclear. Here, we focused on deacetylation regulatory mechanisms of PARP1 and crosstalk of PARP1 post-translational modifications. We uncovered the crucial molecular interactions and protein modifications of deacetylase Sirtuin 2 (SIRT2) and PARP1 in vascular damage. The results showed that SIRT2 was involved in this process and oxidative stress damage factor PARP1 was a novel physiological substrate of SIRT2. SIRT2 interacted with PARP1 at the PARP-A-helical domain and deacetylated the K249 residue of PARP1. Furthermore, SIRT2 promoted ubiquitination of the K249 residue of PARP1 via mobilization of the E3 ubiquitin ligase WW domain-containing protein 2 (WWP2), which led to proteasome-mediated degradation of PARP1. Knockout of SIRT2 in mice and cells increased PARP1 acetylation and decreased PARP1 ubiquitination, which in turn aggravated oxidative stress-induced vascular injury and remodeling. Conversely, overexpression of SIRT2 in mice and cells decreased PARP1 acetylation, increased PARP1 ubiquitination, and relieved oxidative stress-induced vascular injury and remodeling. Overall, this study revealed a previously unrecognized mechanistic link between SIRT2 and PARP1 in the regulation of oxidative stress-induced vascular injury.

Expression Pattern and Clinical Value of Key m6A RNA Modification Regulators in Abdominal Aortic Aneurysm

Background

Aberrant expression of N6-methyladenosine (m6A) RNA modification regulators plays a critical role in a variety of human diseases. However, their implication in abdominal aortic aneurysm (AAA) remains largely unknown. Herein, we sought to explore the general expression pattern and potential functions of m6A regulators in AAA.

Methods

We analyzed gene expression data of m6A regulators in human AAA and normal tissues from public GEO database. The R package and other tools such as m6A2Target database, Gene ontology (GO) functional and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses, gene set variation analysis (GSVA), Search Tool for the Retrieval of Interacting Genes (STRING), starBase, miRDB and Cytoscape software were applied for bioinformatics analysis to investigate the downstream molecular mechanisms and upstream regulatory mechanisms for distinctly expressed regulators. Quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were performed to validate the expression of key m6A regulators in our collected human AAA specimens.

Results

We found that METTL14 and HNRNPC were the downregulated m6A regulators, and RBM15B was the upregulated methylation transferase in human AAA. The modified genes were primarily enriched in RNA catabolic process, regulation of translation, focal adhesion, transcription coregulator activity, ribosome, RNA transport, cell cycle, et al. METTL14, HNRNPC and RBM15B levels were correlated with the immune infiltration degree of Tcm, macrophages, mast cells, Tgd and NK CD56bright cells. A total of 154 and 76 target genes of three regulators were separately involved in body metabolism and autophagy in AAA disease, and their interactive relationships and hub genes were identified. The lncRNA-miRNA-mRNA interaction regulatory networks were also constructed for METTL14, HNRNPC and RBM15B. Based on our clinical tissue and serum samples, METTL14 exhibited lower expression levels in AAA and its rupture type, and low METTL14 expression was associated with high levels of WBC and CRP (all P < 0.05).

Conclusion

Our study presents an overview of the expression pattern and functional significance of m6A regulators in human AAA. Our findings will provide a valuable resource that may guide both mechanistic and therapeutic analyses about the role of key m6A regulators in AAA.

Angiotensin II receptor type 1 - An update on structure, expression and pathology

The AT₁ receptor, a major effector of the renin-angiotensin system, has been extensively studied in the context of cardiovascular and renal disease. Moreover, angiotensin receptor blockers, sartans, are among the most frequently prescribed drugs for the treatment of hypertension, chronic heart failure and chronic kidney disease. However, precise molecular insights into the structure of this important drug target have not been available until recently. In this context, seminal studies have now revealed exciting new insights into the structure and biased signaling of the receptor and may thus foster the development of novel therapeutic approaches to enhance the efficacy of pharmacological angiotensin receptor antagonism or to enable therapeutic induction of biased receptor activity. In this review, we will therefore highlight these and other seminal publications to summarize the current understanding of the tertiary structure, ligand binding properties and downstream signal transduction of the AT₁ receptor.

CCL7 contributes to angiotensin II-induced abdominal aortic aneurysm by promoting macrophage infiltration and pro-inflammatory phenotype

Chemokine C‐C motif ligand 7 (CCL7), a member of CC chemokine subfamily, plays pivotal roles in numerous inflammatory diseases. Hyper‐activation of inflammation is an important characteristic of abdominal aortic aneurysm (AAA). Therefore, in the present study, we aimed to determine the effect of CCL7 on AAA formation. CCL7 abundance in aortic tissue and macrophage infiltration were both increased in angiotensin II (Ang II)‐induced AAA mice. Ex vivo, CCL7 promoted macrophage polarization towards M1 phenotype. This effect was reversed by the blockage of CCR1, a receptor of CCL7. CCL7 up‐regulated JAK2/STAT1 protein level in macrophage, and CCL7‐induced M1 activation was suppressed by JAK2/STAT1 pathway inhibition. To verify the effect of CCL7 on AAA in vivo, either CCL7‐neutralizing antibody (CCL7‐nAb) or vehicles were intraperitoneally injected 24 hours prior to Ang II infusion and subsequently every three days for 4 weeks. CCL7‐nAb administration significantly attenuated Ang II‐induced luminal and external dilation as well as pathological remodelling. Immunostaining showed that CCL7‐nAb administration significantly decreased aneurysmal macrophage infiltration. In conclusion, CCL7 contributed to Ang II‐induced AAA by promoting M1 phenotype of macrophage through CCR1/JAK2/STAT1 signalling pathway.

Okamoto model for necrosis and its expansions, CD38-cyclic ADP-ribose signal system for intracellular Ca2+ mobilization and Reg (Regenerating gene protein)-Reg receptor system for cell regeneration

In pancreatic islet cell culture models and animal models, we studied the molecular mechanisms involved in the development of insulin-dependent diabetes. The diabetogenic agents, alloxan and streptozotocin, caused DNA strand breaks, which in turn activated poly(ADP-ribose) polymerase/synthetase (PARP) to deplete NAD+, thereby inhibiting islet β-cell functions such as proinsulin synthesis and ultimately leading to β-cell necrosis. Radical scavengers protected against the formation of DNA strand breaks and inhibition of proinsulin synthesis. Inhibitors of PARP prevented the NAD+ depletion, inhibition of proinsulin synthesis and β-cell death. These findings led to the proposed unifying concept for β-cell damage and its prevention (the Okamoto model). The model met one proof with PARP knockout animals and was further extended by the discovery of cyclic ADP-ribose as the second messenger for Ca2+ mobilization in glucose-induced insulin secretion and by the identification of Reg (Regenerating gene) for β-cell regeneration. Physiological and pathological events found in pancreatic β-cells have been observed in other cells and tissues.

Xanthan gum protects temporomandibular chondrocytes from IL‑1β through Pin1/NF‑κB signaling pathway

Temporomandibular disorder (TMD) is a complicated and multi-factorial disease related to inflammation and cartilage destruction. Intra-articular injection of xanthan gum (XG) has been demonstrated to protect the joint cartilage and reduce osteoarthritis progression. However, the role and mechanism of XG in TMD is still unclear. In the present study, chondrocytes were isolated from rats and identified by immunofluorescence. Cells were stimulated by XG or interleukin (IL)-1β. Cell viability was analyzed by MTT assay. Tumor necrosis factor α (TNF-α) and IL-6 levels were determined by ELISA. The expression of monocyte chemoattractive protein-1 (MCP-1), inducible nitric oxide synthase (iNOS), collagens, matrix metalloproteinases (MMPs), peptidyl-prolyl isomerase 1 (Pin1) and phosphorylated nuclear factor κB (NF-κB) p65 (p-p65) was analyzed by quantitative PCR or western blotting. MMP activity was assessed by gelatin zymography. Compared with the control, XG treatment partially reversed the IL-1β-reduced cell viability. In addition, IL-1β stimulation increased inflammatory cytokine expression, including TNF-α, IL-6 secretion, MCP-1 and iNOS expression, whereas XG treatment reduced the expression of these inflammatory cytokines compared with that of the IL-1β-stimulated cells. Additionally, XG increased the expression of collagen, but reduced MMP expression and activity as compared with that in the IL-1β group. In addition, XG treatment prevented the IL-1β-increased Pin1 and p-p65 expression. These data suggested that XG reduced the expression of inflammatory cytokines and may maintain the balance between collagens and MMPs partially through the Pin1/NF-κB signaling pathway in IL-1β-stimulated temporomandibular chondrocytes. Therefore, XG may be useful in the treatment of TMD.

Silencing of long non-coding RNA Sox2ot inhibits oxidative stress and inflammation of vascular smooth muscle cells in abdominal aortic aneurysm via microRNA-145-mediated Egr1 inhibition

Long non-coding RNAs (lncRNAs) have been largely reported to contribute to the development and progression of abdominal aortic aneurysm (AAA), a common vascular degenerative disease. The present study was set out with the aim to investigate the possible role of lncRNA Sox2ot in the development of AAA. In this study, we found that lncRNA Sox2ot and early growth response factor-1 (Egr1) were highly expressed, while microRNA (miR)-145 was poorly expressed in Ang II-induced AAA mice and oxidative stress-provoked vascular smooth muscle cell (VSMC) model. Egr1 was a potential target gene of miR-145, and lncRNA Sox2ot could competitively bind to miR-145 to upregulate Egr1 expression. Overexpression of miR-145-5p was found to attenuate oxidative stress and inflammation by inhibiting Egr1 both in vivo and in vitro, which was counteracted by lncRNA Sox2ot. Taken together, the present study provides evidence that downregulation of lncRNA Sox2ot suppressed the expression of Egr1 through regulating miR-145, thus inhibiting the development of AAA, highlighting a theoretical basis for AAA treatment.

A novel role of VEPH1 in regulating AoSMC phenotypic switching

Abdominal aortic aneurysm (AAA) is a potentially lethal disease featured by focal dilatation in the aorta. The transition of vascular smooth muscle cells (SMCs) from a contractile/differentiated to a synthetic/dedifferentiated phenotype is considered to contribute to AAA formation and expansion. Our previous gene microarray data showed that Ventricular Zone Expressed PH Domain Containing 1 (VEPH1) expression increased in angiotensin II (Ang II)-infused aortic tissues. This study was thus performed to further explore the role of VEPH1. Herein, we first demonstrate that VEPH1 increases in the SMCs of Ang II-treated abdominal aortas. As in vivo, Ang II also upregulated VEPH1 expression in cultured hAoSMCs. The dedifferentiation of human aortic SMCs (hAoSMCs) was induced by a 24-hr stimulation of Ang II (1 μM)-the expression of contractile SMC markers, MYH11 and α-smooth muscle actin (α-SMA) decreased and that of synthetic markers, proliferating cell nuclear antigen and Vimentin increased. Inhibition of VEPH1 prevented Ang II-induced pathological dedifferentiation of hAoSMCs as indicated by the restored expression of MYH11 and α-SMA. In contrast, the forced overexpression of VEPH1 aggravated Ang II's effects. Furthermore, we demonstrated that VEPH1 and transforming growth factor-β1 (TGF-β1), a key regulator responsible for vascular SMC differentiation, negatively regulated each other's transcription. In contrast to VEPH1 silencing, its overexpression inhibited recombinant TGF-β1-induced increases in MYH11 and α-SMA and suppressed Smad3 phosphorylation and nuclear accumulation. Collectively, our study demonstrates that VEPH1 elevation promotes the synthetic phenotype switching of AoSMCs and suppressed the TGF-β1/Smad3 signaling pathway. Identification of VEPH1 as a pathogenic molecule for AAA formation provides novel insights into this disease.

The role of IL-1β in aortic aneurysm

Interleukin-1β (IL-1β) is a vital cytokine that plays an important role in regulating immune responses to infectious challenges and sterile insults. In addition, two endogenous inhibitors of functional receptor binding, IL-1 receptor antagonist (IL-1Ra), complete the family. To gain biological activity, IL-1β requires processing by the protease caspase-1 and activation of inflammasomes. Numerous clinical association studies and experimental approaches have implicated members of the IL-1 family, their receptors, or components of the processing machinery in the underlying processes of cardiovascular diseases. Here, we summarize the current state of knowledge regarding the pro-inflammatory and disease-modulating role of the IL-1 family in aneurysm. We discuss clinical evidence, signalling pathway, and mechanism of action and last, lend a perspective on currently developing therapeutic strategies involving IL-1β in aneurysm.

Remifentanil Protects against Lipopolysaccharide-Induced Inflammation through PARP-1/NF-κB Signaling Pathway

Sepsis is a leading cause of death in patients with severe infection worldwide. Remifentanil is an ultra-short-acting, potent opioid analgesic. In the study, we aimed to investigate the role and underlying mechanism of remifentanil in lipopolysaccharide- (LPS-) induced inflammation in human aortic endothelial cells (HAECs). HAECs were pretreated with phosphate-buffered saline (PBS) or remifentanil (2.5 μM) for 30 min, then stimulated by LPS (10 μg/ml) for another 24 h. Poly(ADP-ribose) polymerase 1 (PARP-1) was inhibited by small interfering RNA (siRNA). Superoxide anion production and DNA damage were analyzed by dihydroethidium (DHE) staining and comet assay. The inducible nitric oxide synthase (iNOS), intercellular adhesion molecule 1 (ICAM-1), PARP-1, poly(ADP-ribose) (PAR), and nuclear factor-kappa B p65 (NF-κB p65) expressions were analyzed by RT-PCR or western blotting analysis. NF-κB p65 nuclear translocation was assessed by immunofluorescence. Compared with the control group, pretreatment with remifentanil significantly reduced superoxide anion production and DNA damage, with downregulation of iNOS, ICAM-1, and PARP-1 expressions as well as PAR expression. Moreover, pretreatment with PARP-1 siRNA or remifentanil inhibited LPS-induced NF-κB p65 expression and nuclear translocation. Remifentanil reduced LPS-induced inflammatory response through PARP-1/NF-κB signaling pathway. Remifentanil might be an optimal choice of analgesia in septic patients.

The TGF-β pathway plays a key role in aortic aneurysms

Aortic dissection and aortic aneurysms are currently among the most high-risk cardiovascular diseases due to their rapid onset and high mortality. Although aneurysm research has been extensive, the pathogenesis remains unknown. Studies have found that the TGF-β/Smad pathway and aneurysm formation appear linked. For example, the TGF-β signaling pathway was significantly activated in aneurysm development and aortic dissection. Aneurysms are not, however, mitigated following knockdown of TGF-β signaling pathway-related genes. Incidence and mortality rate of ruptured thoracic aneurysms increase with the down-regulation of the classical TGF-β signaling pathway. In this review, we summarize recent findings and evaluate the differential role of classical and non-classical TGF-β pathways on aortic aneurysm. It is postulated that the TGF-β signaling pathway is necessary to maintain vascular function, but over-activation will promote aneurysms whereas over-inhibition will lead to bypass pathway over-activation and promote aneurysm occurrence.

Regulatory T cells protected against abdominal aortic aneurysm by suppression of the COX-2 expression

CD4⁺CD25⁺ regulatory T cells (Tregs) have been shown to protect against the development of abdominal aortic aneurysm (AAA). Cyclooxygenase‐2 (COX‐2), a pro‐inflammatory protein, can convert arachidonic acid into prostaglandins (PGs). The present study was aimed to investigate the effect of Tregs on COX‐2 expression in angiotension II (Ang II)‐induced AAA in ApoE^−/− mice. Tregs were injected via tail vein in every 2 weeks. Ang II was continuously infused by a micropump for 28 days to induce AAA. In vivo, compared with the control group, adoptive transfer of Tregs significantly reduced the incidence of AAA, maximal diameter, and the mRNA and protein expression of COX‐2 in mice. Immunofluorescence showed that Tregs treatment reduced COX‐2 expression both in smooth muscle cells (SMCs) and macrophages in AAA. In vitro, the Western blot analysis showed that Tregs reduced Ang II‐induced COX‐2 expression in macrophages and SMCs. Meanwhile, ELISA showed that Tregs reduced Ang II‐induced prostaglandin E₂ (PGE₂) secretion. Moreover, Tregs increased SMC viability and induced transition of macrophages phenotype from M1 to M2. In conclusion, Tregs treatment dramatically decreased the expression of COX‐2 in vivo and in vitro, suggesting that Tregs could protect against AAA through inhibition of COX‐2. The study may shed light on the immune treatment of AAA.