Data on TREM-1 activation destabilizing carotid plaques

Therapeutic Potential of Targeting p27kip1 in Plaque Vulnerability

Atherosclerosis, a critical contributor to coronary artery diseases, involves the accumulation of cholesterol, fibrin, and lipids within arterial walls, inciting inflammatory reactions culminating in plaque formation. This multifaceted interplay encompasses excessive fibrosis, fatty plaque development, vascular smooth muscle cell (VSMC) proliferation, and leukocyte migration in response to inflammatory pathways. While stable plaques demonstrate resilience against complications, vulnerable ones, with lipid-rich cores, necrosis, and thin fibrous caps, lead to thrombosis, myocardial infarction, stroke, and acute cerebrovascular accidents. The nuanced phenotypes of VSMCs, modulated by gene regulation and environmental cues, remain pivotal. Essential markers like alpha-SMA, myosin heavy chain, and calponin regulate VSMC migration and contraction, exhibiting diminished expression during VSMC de-differentiation and proliferation. p27kip, a CDK inhibitor, shows promise in regulating VSMC proliferation and appears associated with TNF-α-induced pathways impacting unstable plaques. Oncostatin M (OSM), an IL-6 family cytokine, correlates with MMP upregulation and foam cell formation, influencing plaque development. Efforts targeting mammalian target of rapamycin (mTOR) inhibition, notably using rapamycin and its analogs, demonstrate potential but pose challenges due to associated adverse effects. Exploration of the impact of p27kip impact on plaque macrophages presents promising avenues, yet its complete therapeutic potential remains untapped. Similarly, while OSM has exhibited potential in inducing cell cycle arrest via p27kip, direct links necessitate further investigation. This critical review discusses the role of mTOR, p27kip, and OSM in VSMC proliferation and differentiation followed by the therapeutic potential of targeting these mediators in atherosclerosis to attenuate plaque vulnerability.

The Exacerbating Effects of the Tumor Necrosis Factor in Cardiovascular Stenosis: Intimal Hyperplasia

TNF-α functions as a master regulator of inflammation, and it plays a prominent role in several immunological diseases. By promoting important cellular mechanisms, such as cell proliferation, migration, and phenotype switch, TNF-α induces its exacerbating effects, which are the underlying cause of many proliferative diseases such as cancer and cardiovascular disease. TNF-α primarily alters the immune component of the disease, which subsequently affects normal functioning of the cells. Monoclonal antibodies and synthetic drugs that can target TNF-α and impair its effects have been developed and are currently used in the treatment of a few select human diseases. Vascular restenosis is a proliferative disorder that is initiated by immunological mechanisms. In this review, the role of TNF-α in exacerbating restenosis resulting from neointimal hyperplasia, as well as molecular mechanisms and cellular processes affected or induced by TNF-α, are discussed. As TNF-α-targeting drugs are currently not approved for the treatment of restenosis, the summation of the topics discussed here is anticipated to provide information that can emphasize on the use of TNF-α-targeting drug candidates to prevent vascular restenosis.

Increased Oxidative Stress and Decreased Sirtuin-3 and FOXO3 Expression Following Carotid Artery Intimal Injury in Hyperlipidemic Yucatan Microswine

Hypercholesterolemia is a major risk factor for atherosclerosis as oxidized-low-density lipoproteins (ox-LDL) contribute to the formation of foam cells and inflammation. Increased immune cell infiltration and oxidative stress induce instability of a plaque. Rupture of the unstable plaque precipitates adverse ischemic events. Since reactive oxygen species (ROS) play a critical role in plaque formation and vulnerability, regulating ROS generation may have therapeutic potential. Sirtuins, specifically sirtuin-3 (SIRT3), are antigenic molecules that can reduce oxidative stress by reducing mitochondrial ROS production through epigenetic modulation. Lack of SIRT3 expression is associated with dysregulation of ROS and endothelial function following high-fat high-cholesterol diet. SIRT3 deacetylates FOXO3a (Forkhead transcription factor O subfamily member 3a) and protects mitochondria against oxidative stress which can lead to even further protective anti-oxidizing properties. This study was designed to investigate the association between hyperlipidemia, intimal injury, chronic inflammation, and the expression of NAD-dependent deacetylase SIRT-3, FOXO3, antioxidant genes, and oxidative stress in carotid arteries of hypercholesterolemic Yucatan microswine. We found that intimal injury in hypercholesterolemic state led to increased expression of oxidative stress, inflammation, neointimal hyperplasia, and plaque size and vulnerability, while decreasing anti-oxidative regulatory genes and mediators. The findings suggest that targeting the SIRT3-FOXO3a-oxidative stress pathway will have therapeutic significance.

Role of sirtuins in attenuating plaque vulnerability in atherosclerosis

Atherosclerosis is characterized by the development of intimal plaque, thrombosis, and stenosis of the vessel lumen causing decreased blood flow and hypoxia precipitating angina. Chronic inflammation in the stable plaque renders it unstable and rupture of unstable plaques results in the formation of emboli leading to hypoxia/ischemia to the organs by occluding the terminal branches and precipitate myocardial infarction and stroke. Such delibitating events could be controlled by the strategies that prevent plaque development or plaque stabilization. Despite the use of statins to stabilize plaques, there is a need for novel targets due to continuously increasing cases of cardiovascular events. Sirtuins (SIRTs), a family of signaling proteins, are involved in sustaining genome integrity, DNA damage response and repair, modulating oxidative stress, aging, inflammation, and energy metabolism. SIRTs play a critical role in modulating inflammation and involves in the development and progression of atherosclerosis. The role of SIRTs in relation to atherosclerosis and plaque vulnerability is scarcely discussed in the literature. Since SIRTs regulate oxidative stress, inflammation, and aging, they may also regulate plaque progression and vulnerability as these molecular mechanisms underlie the pathogenesis of plaque development, progression, and vulnerability. This review critically discusses the role of SIRTs in plaque progression and vulnerability and the possibility of targeting SIRTs to attenuate plaque rupture, focusing on the highlights in genomics, molecular pathways, and cell types involved in the underlying pathophysiology.

Residual risks and evolving atherosclerotic plaques

Atherosclerotic disease of the coronary and carotid arteries is the primary global cause of significant mortality and morbidity. The chronic occlusive diseases have changed the epidemiological landscape of health problems both in developed and the developing countries. Despite the enormous benefit of advanced revascularization techniques, use of statins, and successful attempts of targeting modifiable risk factors, like smoking and exercise in the last four decades, there is still a definite "residual risk" in the population, as evidenced by many prevalent and new cases every year. Here, we highlight the burden of the atherosclerotic diseases and provide substantial clinical evidence of the residual risks in these diseases despite advanced management settings, with emphasis on strokes and cardiovascular risks. We critically discussed the concepts and potential underlying mechanisms of the evolving atherosclerotic plaques in the coronary and carotid arteries. This has changed our understanding of the plaque biology, the progression of unstable vs stable plaques, and the evolution of plaque prior to the occurrence of a major adverse atherothrombotic event. This has been facilitated using intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy in the clinical settings to achieve surrogate end points. These techniques are now providing exquisite information on plaque size, composition, lipid volume, fibrous cap thickness and other features that were previously not possible with conventional angiography.

Role of oncostatin-M in ECM remodeling and plaque vulnerability

Atherosclerosis is a multifactorial inflammatory disease characterized by the development of plaque formation leading to occlusion of the vessel and hypoxia of the tissue supplied by the vessel. Chronic inflammation and altered collagen expression render stable plaque to unstable and increase plaque vulnerability. Thinned and weakened fibrous cap results in plaque rupture and formation of thrombosis and emboli formation leading to acute ischemic events such as stroke and myocardial infarction. Inflammatory mediators including TREM-1, TLRs, MMPs, and immune cells play a critical role in plaque vulnerability. Among the other inflammatory mediators, oncostatin-M (OSM), a pro-inflammatory cytokine, play an important role in the development and progression of atherosclerosis, however, the role of OSM in plaque vulnerability and extracellular matrix remodeling (ECM) is not well understood and studied. Since ECM remodeling plays an important role in atherosclerosis and plaque vulnerability, a detailed investigation on the role of OSM in ECM remodeling and plaque vulnerability is critical. This is important because the role of OSM has been discussed in the context of proliferation of vascular smooth muscle cells and regulation of cytokine expression but the role of OSM is scarcely discussed in relation to ECM remodeling and plaque vulnerability. This review focuses on critically discussing the role of OSM in ECM remodeling and plaque vulnerability.

Oxidized Low-density Lipoproteins and Lipopolysaccharides Augment Carotid Artery Plaque Vulnerability in Hypercholesterolemic Microswine

Atherosclerosis is a chronic inflammatory disease and hypercholesterolemia is a risk factor. This study aims to compare the potency of lipopolysaccharide (LPS) and oxidized low-density lipoproteins (oxLDL) to induce plaque formation and increase plaque vulnerability in the carotid artery of hypercholesterolemic Yucatan microswine. Atherosclerotic lesions at the common carotid artery junction and ascending pharyngeal artery were induced in hypercholesterolemic Yucatan microswine at 5-6 months of age with balloon angioplasty. LPS or oxLDL were administered intraluminally at the site of injury after occluding the arterial flow temporarily. Pre-intervention ultrasound (US), angiography, and optical coherence tomography (OCT) were done at baseline and just before euthanasia to assess post-op parameters. The images from the US, OCT, and angiography in the LPS and the oxLDL-treated group showed increased plaque formation with features suggestive of unstable plaque, including necrotic core, thin fibrous caps, and a signal poor region more with oxLDL compared to LPS. Histomorphology of the carotid artery tissue near the injury corroborated the presence of severe lesions in both LPS and oxLDL-treated pigs but more in the oxLDL group. Vascular smooth muscle and endothelial cells treated with LPS and oxLDL showed increased folds changes in mRNA transcripts of the biomarkers of inflammation and plaque vulnerability compared to untreated cells. Collectively, the results suggest that angioplasty-mediated intimal injury of the carotid arteries in atherosclerotic swine with local administration of LPS or ox-LDL induces vulnerable plaques compared to angioplasty alone and oxLDL is relatively more potent than LPS in inducing vulnerable plaque.

Non-Coding RNAs in Regulating Plaque Progression and Remodeling of Extracellular Matrix in Atherosclerosis

Non-coding RNAs (ncRNAs) regulate cell proliferation, migration, differentiation, inflammation, metabolism of clinically important biomolecules, and other cellular processes. They do not encode proteins but are involved in the regulatory network of various proteins that are directly related to the pathogenesis of diseases. Little is known about the ncRNA-associated mechanisms of atherosclerosis and related cardiovascular disorders. Remodeling of the extracellular matrix (ECM) is critical in the pathogenesis of atherosclerosis and related disorders; however, its regulatory proteins are the potential subjects to explore with special emphasis on epigenetic regulatory components. The activity of regulatory proteins involved in ECM remodeling is regulated by various ncRNA molecules, as evident from recent research. Thus, it is important to critically evaluate the existing literature to enhance the understanding of nc-RNAs-regulated molecular mechanisms regulating ECM components, remodeling, and progression of atherosclerosis. This is crucial since deregulated ECM remodeling contributes to atherosclerosis. Thus, an in-depth understanding of ncRNA-associated ECM remodeling may identify novel targets for the treatment of atherosclerosis and other cardiovascular diseases.

Targeting the Crosstalk of Immune Response and Vascular Smooth Muscle Cells Phenotype Switch for Arteriovenous Fistula Maturation

Plaque formation, thrombosis, and embolism are the underlying causes of acute cardiovascular events such as myocardial infarction and stroke while early thrombosis and stenosis are common pathologies for the maturation failure of arteriovenous fistula (AVF). Chronic inflammation is a common underlying pathogenesis mediated by innate and adaptive immune response involving infiltration of immune cells and secretion of pro- and anti-inflammatory cytokines. Impaired immune cell infiltration and change in vascular smooth muscle cell (VSMC) phenotype play a crucial role in the underlying pathophysiology. However, the change in the phenotype of VSMCs in a microenvironment of immune cell infiltration and increased secretion of cytokines have not been investigated. Since change in VSMC phenotype regulates vessel remodeling after intimal injury, in this study, we investigated the effect of macrophages and pro-inflammatory cytokines, IL-6, IL-1β, and TNF-α, on the change in VSMC phenotype under in vitro conditions. We also investigated the expression of the markers of VSMC phenotypes in arteries with atherosclerotic plaques and VSMCs isolated from control arteries. We found that the inhibition of cytokine downstream signaling may mitigate the effect of cytokines on the change in VSMCs phenotype. The results of this study support that regulating or targeting immune cell infiltration and function might be a therapeutic strategy to mitigate the effects of chronic inflammation to attenuate plaque formation, early thrombosis, and stenosis, and thus enhance AVF maturation.

Transcriptomic Analysis Identifies Differentially Expressed Genes Associated with Vascular Cuffing and Chronic Inflammation Mediating Early Thrombosis in Arteriovenous Fistula

Arteriovenous fistula (AVF) is vascular access created for hemodialysis in end-stage renal disease patients. AVF creation causes increased blood flow in the outflow vein with increased pressure. Increased blood flow, blood volume, and shear stress causes outward remodeling so that the outflow vein can withstand the increased pressure. Outward remodeling of the vein involved in AVF is necessary for AVF maturation, however, inward remodeling due to excessive neointimal hyperplasia (NIH) and chronic inflammation may end up with vessel thrombosis and AVF maturation failure. Early thrombosis of the vessel may be due to the luminal factors including NIH and chronic inflammation or due to chronic inflammation of the adventitial due to perivascular cuffing. Inflammation may either be due to an immune response to the vascular injury during AVF creation or injury to the surrounding muscles and fascia. Several studies have discussed the role of inflammation in vascular thrombosis due to intimal injury during AVF creation, but there is limited information on the role of inflammation due to surrounding factors like a muscle injury. The concept of perivascular cuffing has been reported in the nervous system, but there is no study of perivascular cuffing in AVF early thrombosis. We performed the bulk RNA sequencing of the femoral arterial tissue and contralateral arteries as we found thrombosed arteries after AVF creation. RNA sequencing revealed several significantly differentially expressed genes (DEGs) related to chronic inflammation and perivascular cuffing, including tripartite motif-containing protein 55 (TRIM55). Additionally, DEGs like myoblast determination protein 1 (MYOD1) increased after muscle injury and relates to skeletal muscle differentiation, and network analysis revealed regulation of various genes regulating inflammation via MYOD1. The findings of this study revealed multiple genes with increased expression in the AVF femoral artery and may provide potential therapeutic targets or biomarkers of early thrombosis in AVF maturation failure. Thus, not only the luminal factors but also the surrounding factors mediating vascular cuffing contribute to vessel thrombosis and AVF failure via early thrombosis, and targeting the key regulatory factors may have therapeutic potential.

Nanomaterial-Mediated Theranostics for Vascular Diseases

Nanotechnology could offer a new complementary strategy for the treatment of vascular diseases including coronary, carotid, or peripheral arterial disease due to narrowing or blockage of the artery caused by atherosclerosis. These arterial diseases manifest correspondingly as angina and myocardial infarction, stroke, and intermittent claudication of leg muscles during exercise. The pathogenesis of atherosclerosis involves biological events at the cellular and molecular level, thus targeting these using nanomaterials precisely and effectively could result in a better outcome. Nanotechnology can mitigate the pathological events by enhancing the therapeutic efficacy of the therapeutic agent by delivering it at the point of a lesion in a controlled and efficacious manner. Further, combining therapeutics with imaging will enhance the theranostic ability in atherosclerosis. Additionally, nanoparticles can provide a range of delivery systems for genes, proteins, cells, and drugs, which individually or in combination can address various problems within the arteries. Imaging studies combined with nanoparticles helps in evaluating the disease progression as well as the response to the treatment because imaging and diagnostic agents can be delivered precisely to the targeted destinations via nanocarriers. This review focuses on the use of nanotechnology in theranostics of coronary artery and peripheral arterial disease.

Rheumatoid arthritis synovial fibroblasts promote TREM-1 expression in monocytes via COX-2/PGE2 pathway

BACKGROUND

Triggering receptor expressed on myeloid cells-1 (TREM-1) is inducible on monocyte/macrophages and neutrophils and amplifies the inflammatory response. The aim of this study was to determine whether rheumatoid arthritis synovial fibroblasts (RASF) promote the expression of TREM-1 in monocytes and its potential regulatory mechanism.

METHODS

Synovial fluid and paired peripheral blood from rheumatoid arthritis (RA) patients were analyzed using flow cytometry. Expression of TREM-1 in monocytes was detected after co-culture with RASF, with or without pre-treatment with toll-like receptor (TLR) ligands. Whether RASF-regulated TREM-1 level in monocytes require direct cell contact or soluble factors was evaluated by transwell experiment. COX-2 expression and PGE₂ secretion in RASF were determined by quantitative PCR (qPCR) and ELISA. RASF, with and without TLR ligand stimulation, were treated with COX-2 inhibitors, COX-2 siRNA (siCOX-2) or EP1-4 antagonists, and the resulting TREM-1 level in CD14⁺ monocytes was measured using flow cytometry.

RESULTS

TREM-1 was highly expressed in CD14⁺ cells from peripheral blood and especially synovial fluid from RA patients. The expression of TREM-1 in monocytes was increased by co-culture with RASF. TLR-ligand-activated RASF further elevated TREM-1 level. Transwell assay indicated that soluble factors played a key role in RASF-promoted expression of TREM-1 in monocytes. RASF, with or without stimulation by TLR ligands, increased secretion of PGE₂ in a cyclooxygenase (COX)-2-dependent manner. PGE₂ enhanced the increase in TREM-1 level in monocytes. Finally, studies using COX-2 inhibitors, COX-2 siRNA (siCOX-2) and EP1-4 antagonists, showed that RASF promotion of TREM-1 expression in monocytes was mediated by COX-2/PGE₂/EP2,4 signaling.

CONCLUSIONS

Our data is the first report to reveal the critical role of RASF in upregulating TREM-1 expression in monocytes, which indicates that TREM-1 might be a novel target for RA therapy.

TREM-1; Is It a Pivotal Target for Cardiovascular Diseases?

Cardiovascular diseases (CVDs) are as menacing as ever and still continue to kill adults worldwide, notwithstanding tremendous efforts to decrease their consequent mortality and morbidity. Lately, a growing body of research indicated that inflammation plays a pivotal role in the pathogenesis and complications of CVDs. A receptor of the immunoglobulin superfamily, triggering receptors expressed on myeloid cells-1 (TREM-1) was shown to induce and amplify the inflammation in both acute and chronic disease’ pathogenesis and progression, which hence makes it one of the most important complication factors of CVDs. Thus, studies endeavored to investigate the role played by TREM-1 in CVDs with respect to their etiologies, complications, and possible therapeutics. We examined here, for the first time, the most relevant studies regarding TREM-1 involvement in CVDs. We critically analyzed and summarized our findings and made some suggestions for furtherance of the investigations with the aim to utilize TREM-1 and its pathways for diagnostic, management, and prognosis of CVDs. Overall, TREM-1 was found to be involved in the pathogenesis of acute and chronic cardiovascular conditions, such as acute myocardial infarction (AMI) and atherosclerosis. Although most therapeutic approaches are yet to be elucidated, our present research outcome displays a promising future to utilizing the TREM-1 pathway as a potential target for understanding and managing CVDs.

TREM-1 and its potential ligands in non-infectious diseases: from biology to clinical perspectives

Triggering receptor expressed on myeloid cells-1 (TREM-1) is expressed on the majority of innate immune cells and to a lesser extent on parenchymal cells. Upon activation, TREM-1 can directly amplify an inflammatory response. Although it was initially demonstrated that TREM-1 was predominantly associated with infectious diseases, recent evidences shed new light into its role in sterile inflammatory diseases. Indeed, TREM-1 receptor and its signaling pathways contribute to the pathology of several non-infectious acute and chronic inflammatory diseases, including atherosclerosis, ischemia reperfusion-induced tissue injury, colitis, fibrosis and cancer. This review, aims to give an extensive overview of TREM-1 in non-infectious diseases, with the focus on the therapeutic potential of TREM-1 intervention strategies herein. In addition, we provide the reader with a functional enrichment analysis of TREM-1 signaling pathway and potential TREM-1 ligands in these diseases, obtained via in silico approach. We discuss pre-clinical studies which show that TREM-1 inhibition, via synthetic soluble TREM-1 protein mimickers, is effective in treating (preventing) specific inflammatory disorders, without significant effects on antibacterial response. Further research aimed at identifying specific TREM-1 ligands, in different inflammatory disorders, is required to further unravel the role of this receptor, and explore new avenues to modulate its function.

The role of damage- and pathogen-associated molecular patterns in inflammation-mediated vulnerability of atherosclerotic plaques

Atherosclerosis is a chronic inflammatory disease resulting in the formation of the atherosclerotic plaque. Plaque formation starts with the inflammation in fatty streaks and progresses through atheroma, atheromatous plaque, and fibroatheroma leading to development of stable plaque. Hypercholesterolemia, dyslipidemia, and hyperglycemia are the risk factors for atherosclerosis. Inflammation, infection with viruses and bacteria, and dysregulation in the endothelial and vascular smooth muscle cells leads to advanced plaque formation. Death of the cells in the intima due to inflammation results in secretion of damage-associated molecular patterns (DAMPs) such as high mobility group box 1 (HMGB1), receptor for advanced glycation end products (RAGE), alarmins (S100A8, S100A9, S100A12, and oxidized low-density lipoproteins), and infection with pathogens leads to secretion of pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharides, lipoteichoic acids, and peptidoglycans. DAMPs and PAMPs further activate the inflammatory surface receptors such as TREM-1 and toll-like receptors and downstream signaling kinases and transcription factors leading to increased secretion of pro-inflammatory cytokines such as tumor necrosis factor α, interleukin (IL)-1β, IL-6, and interferon-γ and matrix metalloproteinases (MMPs). These mediators and cytokines along with MMPs render the plaque vulnerable for rupture leading to ischemic events. In this review, we have discussed the role of DAMPs and PAMPs in association with inflammation-mediated plaque vulnerability.

The preterm cervix reveals a transcriptomic signature in the presence of premature prelabor rupture of membranes

BACKGROUND

Premature prelabor rupture of fetal membranes accounts for 30% of all premature births and is associated with detrimental long-term infant outcomes. Premature cervical remodeling, facilitated by matrix metalloproteinases, may trigger rupture at the zone of the fetal membranes overlying the cervix. The similarities and differences underlying cervical remodeling in premature prelabor rupture of fetal membranes and spontaneous preterm labor with intact membranes are unexplored.

OBJECTIVES

We aimed to perform the first transcriptomic assessment of the preterm human cervix to identify differences between premature prelabor rupture of fetal membranes and preterm labor with intact membranes and to compare the enzymatic activities of matrix metalloproteinases-2 and -9 between premature prelabor rupture of fetal membranes and preterm labor with intact membranes.

STUDY DESIGN

Cervical biopsies were collected following preterm labor with intact membranes (n = 6) and premature prelabor rupture of fetal membranes (n = 5). Biopsies were also collected from reference groups at term labor (n = 12) or term not labor (n = 5). The Illumina HT-12 version 4.0 BeadChips microarray was utilized, and a novel network graph approach determined the specificity of changes between premature prelabor rupture of fetal membranes and preterm labor with intact membranes. Quantitative reverse transcription-polymerase chain reaction and Western blotting confirmed the microarray findings. Immunofluorescence was used for localization studies and gelatin zymography to assess matrix metalloproteinase activity.

RESULTS

PML-RARA-regulated adapter molecule 1, FYVE-RhoGEF and PH domain-containing protein 3 and carcinoembryonic antigen-ralated cell adhesion molecule 3 were significantly higher, whereas N-myc downstream regulated gene 2 was lower in the premature prelabor rupture of fetal membranes cervix when compared with the cervix in preterm labor with intact membranes, term labor, and term not labor. PRAM1 and CEACAM3 were localized to immune cells at the cervical stroma and NDRG2 and FGD3 were localized to cervical myofibroblasts. The activity of matrix metalloproteinase-9 was higher (1.22 ± 4.403-fold, P < .05) in the cervix in premature prelabor rupture of fetal membranes compared with preterm labor with intact membranes.

CONCLUSION

We identified 4 novel proteins with a potential role in the regulation of cervical remodeling leading to premature prelabor rupture of fetal membranes. Our findings contribute to the studies dissecting the mechanisms underlying premature prelabor rupture of fetal membranes and inspire further investigations toward the development of premature prelabor rupture of fetal membranes therapeutics.