Loss Of Vascular Smooth Muscle Cells Research Articles

Inhibition of poly(ADP-Ribosyl)ation reduced vascular smooth muscle cells loss and improves aortic disease in a mouse model of human accelerated aging syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare genetic disorder associated with features of accelerated aging. HGPS is an autosomal dominant disease caused by a de novo mutation of LMNA gene, encoding A-type lamins, resulting in the truncated form of pre-lamin A called progerin. While asymptomatic at birth, patients develop symptoms within the first year of life when they begin to display accelerated aging and suffer from growth retardation, and severe cardiovascular complications including loss of vascular smooth muscle cells (VSMCs). Recent works reported the loss of VSMCs as a major factor triggering atherosclerosis in HGPS. Here, we investigated the mechanisms by which progerin expression leads to massive VSMCs loss. Using aorta tissue and primary cultures of murine VSMCs from a mouse model of HGPS, we showed increased VSMCs death associated with increased poly(ADP-Ribosyl)ation. Poly(ADP-Ribosyl)ation is recognized as a post-translational protein modification that coordinates the repair at DNA damage sites. Poly-ADP-ribose polymerase (PARP) catalyzes protein poly(ADP-Ribosyl)ation by utilizing nicotinamide adenine dinucleotide (NAD+). Our results provided the first demonstration linking progerin accumulation, augmented poly(ADP-Ribosyl)ation and decreased nicotinamide adenine dinucleotide (NAD+) level in VSMCs. Using high-throughput screening on VSMCs differentiated from iPSCs from HGPS patients, we identified a new compound, trifluridine able to increase NAD+ levels through decrease of PARP-1 activity. Lastly, we demonstrate that trifluridine treatment in vivo was able to alleviate aortic VSMCs loss and clinical sign of progeria, suggesting a novel therapeutic approach of cardiovascular disease in progeria.

Cigarette tar accelerates atherosclerosis progression via RIPK3-dependent necroptosis mediated by endoplasmic reticulum stress in vascular smooth muscle cells

BackgroundTar is the main toxic of cigarettes, and its effect on atherosclerosis progression and the underlying mechanisms remain largely unknown. Vascular smooth muscle cells (VSMCs) play a key role in atherogenesis and plaque vulnerability. The present study sought to investigate the mechanism of atherosclerosis progression through tar-induced VSMC necroptosis, a recently described form of necrosis.MethodsThe effect of tar on atherosclerosis progression and VSMC necroptosis was examined in ApoE−/− mice and cultured VSMCs. The role of necroptosis in tar-induced plaque development was evaluated in RIPK3-deletion mice (ApoE−/−RIPK3−/−). The key proteins of necroptosis in carotid plaques of smokers and non-smokers were also examined. Quantitative proteomics of mice aortas was conducted to further investigate the underlying mechanism. Pharmacological approaches were then applied to modulate the expression of targets to verify the regulatory process of tar-induced necroptosis.ResultsTar administration led to increased atherosclerotic plaque area and reduced collagen and VSMCs in ApoE−/− mice. The expression of RIPK1、RIPK3、and MLKL in VSMCs of plaques were all increased in tar-exposed mice and smokers. RIPK3 deletion protected against VSMC loss and plaque progression stimulated by tar. In mechanistic studies, quantitative proteomics analysis of ApoE−/− mice aortas suggested that tar triggered endoplasmic reticulum (ER) stress. PERK-eIF2α-CHOP axis was activated in tar-treated VSMCs and atherosclerotic plaque. Inhibition of ER stress using 4PBA significantly reduced plaque progression and VSMC necroptosis. Further study revealed that ER stress resulted in calcium (Ca2+) release into mitochondria and cytoplasm. Elevated Ca2+ levels lead to mitochondrial dysfunction and excessive reactive oxygen species (ROS) production, which consequently promote RIPK3-dependent necroptosis. In addition, Ca2+/calmodulin-dependent protein kinase II (CaMKII) activated by cytosolic Ca2+ overload binds to RIPK3, accounting for necroptosis.ConclusionThe findings revealed that cigarette tar promoted atherosclerosis progression by inducing RIPK3-dependent VSMC necroptosis and identified novel avenues of ER stress and Ca2+ overload.

PANoptosis in vascular smooth muscle cells regulated by TNF-α/IL-1β can be a new target for alleviating the progression of abdominal aortic aneurysm.

PANoptosis is an inflammatory programmed cell death (PCD) regulated by multifaceted PANoptosome complexes with major features of pyroptosis, apoptosis, and/or necroptosis that cannot be accounted for by any of these PCD pathways alone. The aim of this study was to investigate the role of PANoptosis on the occurrence and development of abdominal aortic aneurysm (AAA). Clinical samples of patients with AAA, angiotensin II (ANG II)-induced AAA mouse model, and ANG II-induced vascular smooth muscle cells (VSMCs) in vitro model were used for investigation on PANoptosis features. The expressions of ZBP1, AIM2, and other markers related to pyroptosis, apoptosis, and necroptosis elevated obviously in aortic wall tissues of patients with AAA, mice with AAA, and ANG II-treated VSMCs. ANG II treatment increased inflammatory cytokines levels in VSMCs. The stimulation of tumor necrosis factor-α (TNF-α) or interleukin-1β (IL-1β) alone promoted VSMCs death, and the effect of TNF-α combined with IL-1β is more obvious. The expressions of ZBP1, AIM2, and related markers of pyroptosis, apoptosis, and necroptosis were increased by TNF-α and IL-1β combined treatment. Inhibition of TNF-α and/or IL-1β in mice with AAA improved the AAA pathology, reduced the loss of VSMCs, decreased the expression of ZBP1 and AIM2, and markers associated with pyroptosis, apoptosis, and necroptosis. PANoptosis features were observed in aortic wall tissues of patients with AAA, mice with AAA, and ANG II-treated VSMCs. The inhibition of TNF-α and IL-1β can alleviate PANoptosis in mice with AAA, which provides a new strategy for the prevention and treatment of AAA.NEW & NOTEWORTHY Early detection, diagnosis, and treatment are very important to improve the quality of life and prognosis of patients with abdominal aortic aneurysm (AAA). Based on the findings of apoptosis, necroptosis, and pyroptosis (PANoptosis) in AAA clinical samples, this study further explored the molecular mechanism in vivo and in vitro. Specifically, inhibition of tumor necrosis factor-α and interleukin-1β can reduce PANoptosis in vascular smooth muscle cell and thus alleviate the process of AAA.

Regulation of Matrix Metalloproteinase-2 and Matrix Metalloproteinase-9 in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a degenerative disease characterized by destruction and progressive expansion of the abdominal aortic wall. An AAA is typically defined as an enlargement of the abdominal aorta with diameter ≥3 cm or ≥50% greater than the suprarenal diameter. The pathological changes associated with AAA include inflammatory cell infiltration, extracellular matrix (ECM) destruction and remodeling, and vascular smooth muscle cell loss. The matrix metalloproteinase (MMP) family of proteins plays an important role in initiation and progression of AAA. Since understanding the regulation of MMP-2 and MMP-9 in AAA is essential for treatment of AAA, this review summarized the regulatory mechanisms of MMPs to provide a reference for exploring novel therapeutic approaches.

ER stress induced immunopathology involving complement in CADASIL: implications for therapeutics

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by NOTCH3 mutations. Typical CADASIL is characterised by subcortical ischemic strokes due to severe arteriopathy and fibrotic thickening of small arteries. Arteriolar vascular smooth muscle cells (VSMCs) are the key target in CADASIL, but the potential mechanisms involved in their degeneration are still unclear. Focusing on cerebral microvessels in the frontal and anterior temporal lobes and the basal ganglia, we used advanced proteomic and immunohistochemical methods to explore the extent of inflammatory and immune responses in CADASIL subjects compared to similar age normal and other disease controls. There was variable loss of VSMC in medial layers of arteries in white matter as well as the cortex, that could not be distinguished whether NOTCH3 mutations were in the epidermal growth factor (EGFr) domains 1–6 or EGFr7-34. Proteomics of isolated cerebral microvessels showed alterations in several proteins, many associated with endoplasmic reticulum (ER) stress including heat shock proteins. Cerebral vessels with sparsely populated VSMCs also attracted robust accrual of perivascular microglia/macrophages in order CD45+ > CD163+ > CD68+cells, with > 60% of vessel walls exhibiting intercellular adhesion molecule-1 (ICAM-1) immunoreactivity. Functional VSMC cultures bearing the NOTCH3 Arg133Cys mutation showed increased gene expression of the pro-inflammatory cytokine interleukin 6 and ICAM-1 by 16- and 50-fold, respectively. We further found evidence for activation of the alternative pathway of complement. Immunolocalisation of complement Factor B, C3d and C5-9 terminal complex but not C1q was apparent in ~ 70% of cerebral vessels. Increased complement expression was corroborated in > 70% of cultured VSMCs bearing the Arg133Cys mutation independent of N3ECD immunoreactivity. Our observations suggest that ER stress and other cellular features associated with arteriolar VSMC damage instigate robust localized inflammatory and immune responses in CADASIL. Our study has important implications for immunomodulation approaches to counter the characteristic arteriopathy of CADASIL.

Abstract 360: Role Of Mitochondrial Dynamics In Vascular Smooth Muscle Cell Death

Background: Vascular smooth muscle cell (VSMC) death has been linked to the pathogenesis of various vascular diseases. Excessive mitochondrial fission in response to pathological stimuli contributes to cell death, thus, inhibition of mitochondrial fission can be a promising therapeutic target in vascular diseases. Mitochondrial division inhibitor 1 (mdivi-1) inhibits Drp1-dependent mitochondrial fission by attenuation of its GTPase activity. As association between fission inhibition & VSMCs cell death has been implicated in vascular diseases, the underlying mechanism warrants further investigation. We assessed the effects of mdivi-1 (an inhibitor of Drp1-mediated mitochondrial fission) on staurosporine (STS)-induced mitochondrial dysfunction, impaired autophagy, & cell death in aortic VSMC. Methods & Results: The flow cytometry analysis demonstrated reduced cell death in VSMCs-treated with mdivi-1. The mitochondrial fission was evaluated using Mitotracker Red staining. mdivi-1-treated VSMCs showed significantly higher mitochondrial networks, mean branch length, & mitochondrial footprint compared to STS-treated cells indicating reduced mitochondrial fragmentation. Inhibitory effects of mdivi-1 on fission were exerted by reduced Drp1 phosphorylation at 616. Mitochondrial function via evaluation of mitochondrial permeability transition pore opening, mitochondrial membrane potential & bioenergetic profile showed restored mitochondrial function & metabolic potential in the mdivi-1-treated cells compared to the STS group. The mdivi-1-treated VSMCs showed significantly reduced ROS generation indicating suppressed oxidative stress. The improved mitochondrial structural integrity due to inhibition of fission was associated with reduced mitophagy & cell death-related proteins. Conclusion: In response to apoptotic stimuli, excessive Drp1-dependent mitochondrial fission leads to mitochondrial damage, playing a key role in VSMC death. Inhibition of Drp1-dependent mitochondrial fission by mdivi-1 attenuated mitochondrial fission & prevented cell death in VSMCs. Pharmacological inhibition of mitochondrial fission provides a potential therapeutic target in vascular diseases associated with loss of VSMC.

Abstract 587: The Matricellular Protein Ccn1 Induces Aortic Aneurysms In Mice

Aortic aneurysm ( AA ) is a dilation of the aorta due to an arterial wall weakening. Chronic inflammation and oxidative stress have been associated with dysregulated vascular smooth muscle cell (VSMC) homeostasis and functional phenotype leading to loss of VSMCs, matrix remodeling, and AA formation. The matricellular protein CCN1 (cellular communication network factor 1) has been identified in a subpopulation of VSMCs at the early stage of phenotypic switching. To assess the involvement of CCN1 in AA, CCN1 expression was examined in the CaCl 2 -induced mouse AA model using Ccn1 lacZ/+ -knockin mice. CCN1 expression revealed by whole-mount aortic X-gal staining was intensely induced 3 days after the peri-aortic application of CaCl 2 and sustained more refined to the lesion areas. CCN1 was largely expressed in VSMCs and infiltrating macrophages. CCN1 binds to its receptor integrin α6β1 and promotes atherogenesis through prolonged elevations of inflammation, oxidative stress, and matrix remodeling, the similar driving forces underlying AA progression. To test the role of CCN1 in AA development, Ccn1 dm/dm mice, carrying the α6β1-binding-defective mutant allele Ccn1-dm , were tested in the mouse AA model. Ccn1 dm/dm mice exhibited remarkable resistance against CaCl 2 -induced AA comparing with wild-type control mice 4 weeks after treatment. The Ccn1 dm/dm aortic wall possessed well-structured elastic lamellae and organized VSMC layers with less infiltrating macrophages, inflammation (interleukin-1β and tumor necrosis factor-α), and oxidative stress (8-OHdG). MMP9 levels detected by immunostaining were induced by CaCl 2 in the wild-type aortic wall, but not detected in Ccn1 dm/dm mice. Together, our results demonstrate a critical role of CCN1 in AA formation through binding its receptor α6β1 to increase VSMC inflammation and oxidative stress. CCN1 can be used as a novel therapeutic target for AA.

Protection of diabetes in aortic abdominal aneurysm: Are antidiabetics the real effectors?

Aortic aneurysms, including abdominal aortic aneurysms (AAAs), is the second most prevalent aortic disease and represents an important cause of death worldwide. AAA is a permanent dilation of the aorta on its infrarenal portion, pathologically associated with oxidative stress, proteolysis, vascular smooth muscle cell loss, immune-inflammation, and extracellular matrix remodeling and degradation. Most epidemiological studies have shown a potential protective role of diabetes mellitus (DM) on the prevalence and incidence of AAA. The effect of DM on AAA might be explained mainly by two factors: hyperglycemia [or other DM-related factors such as insulin resistance (IR)] and/or by the effect of prescribed DM drugs, which may have a direct or indirect effect on the formation and progression of AAAs. However, recent studies further support that the protective role of DM in AAA may be attributable to antidiabetic therapies (i.e.: metformin or SGLT-2 inhibitors). This review summarizes current literature on the relationship between DM and the incidence, progression, and rupture of AAAs, and discusses the potential cellular and molecular pathways that may be involved in its vascular effects. Besides, we provide a summary of current antidiabetic therapies which use could be beneficial for AAA.

Vascular smooth muscle cell aging: Insights from Hutchinson-Gilford progeria syndrome

Vascular smooth muscle cells (VSMCs) constitute the principal cellular component of the medial layer of arteries and are responsible for vessel contraction and relaxation in response to blood flow. Alterations in VSMCs can hinder vascular system function, leading to vascular stiffness, calcification and atherosclerosis, which in turn may result in life-threatening complications. Pathological changes in VSMCs typically correlate with chronological age; however, there are certain conditions and diseases, such as Hutchinson-Gilford progeria syndrome (HGPS), that can accelerate this process, resulting in premature vascular aging. HGPS is a rare genetic disorder characterized by severe VSMC loss, accelerated atherosclerosis and death from myocardial infarction or stroke during the adolescence. Because experiments with mouse models have demonstrated that alterations in VSMCs are responsible for early atherosclerosis in HGPS, studies on this disease can provide insights into the mechanisms of vascular aging and assess the relative contribution of VSMCs to this process.

Progerin induces a phenotypic switch in vascular smooth muscle cells and triggers replication stress and an aging-associated secretory signature.

Hutchinson-Gilford progeria syndrome is a premature aging disease caused by LMNA gene mutation and the production of a truncated prelamin A protein "progerin" that elicits cellular and organismal toxicity. Progerin accumulates in the vasculature, being especially detrimental for vascular smooth muscle cells (VSMC). Vessel stiffening and aortic atherosclerosis in HGPS patients are accompanied by VSMC depletion in the medial layer, altered extracellular matrix (ECM), and thickening of the adventitial layer. Mechanisms whereby progerin causes massive VSMC loss and vessel alterations remain poorly understood. Mature VSMC retain phenotypic plasticity and can switch to a synthetic/proliferative phenotype.Here, we show that progerin expression in human and mouse VSMC causes a switch towards the synthetic phenotype. This switch elicits some level of replication stress in normal cells, which is exacerbated in the presence of progerin, leading to telomere fragility, genomic instability, and ultimately VSMC death. Calcitriol prevents replication stress, telomere fragility, and genomic instability, reducing VSMC death. In addition, RNA-seq analysis shows induction of a profibrotic and pro-inflammatory aging-associated secretory phenotype upon progerin expression in human primary VSMC. Our data suggest that phenotypic switch-induced replication stress might be an underlying cause of VSMC loss in progeria, which together with loss of contractile features and gain of profibrotic and pro-inflammatory signatures contribute to vascular stiffness in HGPS.

Elevated TGFβ signaling contributes to cerebral small vessel disease in mouse models of Gould syndrome

Cerebral small vessel disease (CSVD) is a leading cause of stroke and vascular cognitive impairment and dementia. Studying monogenic CSVD can reveal pathways that are dysregulated in common sporadic forms of the disease and may represent therapeutic targets. Mutations in collagen type IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause highly penetrant CSVD as part of a multisystem disorder referred to as Gould syndrome. COL4A1 and COL4A2 form heterotrimers [a1α1α2(IV)] that are fundamental constituents of basement membranes. However, their functions are poorly understood and the mechanism(s) by which COL4A1 and COL4A2 mutations cause CSVD are unknown. We used histological, molecular, genetic, pharmacological, and in vivo imaging approaches to characterize central nervous system (CNS) vascular pathologies in Col4a1 mutant mouse models of monogenic CSVD to provide insight into underlying pathogenic mechanisms. We describe developmental CNS angiogenesis abnormalities characterized by impaired retinal vascular outgrowth and patterning, increased numbers of mural cells with abnormal morphologies, altered contractile protein expression in vascular smooth muscle cells (VSMCs) and age-related loss of arteriolar VSMCs in Col4a1 mutant mice. Importantly, we identified elevated TGFβ signaling as a pathogenic consequence of Col4a1 mutations and show that genetically suppressing TGFβ signaling ameliorated CNS vascular pathologies, including partial rescue of retinal vascular patterning defects, prevention of VSMC loss, and significant reduction of intracerebral hemorrhages in Col4a1 mutant mice aged up to 8 months. This study identifies a novel biological role for collagen α1α1α2(IV) as a regulator of TGFβ signaling and demonstrates that elevated TGFβ signaling contributes to CNS vascular pathologies caused by Col4a1 mutations. Our findings suggest that pharmacologically suppressing TGFβ signaling could reduce the severity of CSVD, and potentially other manifestations associated with Gould syndrome and have important translational implications that could extend to idiopathic forms of CSVD.

Abstract 155: Divergent Mature Vascular Smooth Muscle Cell Fates Are Directed By Platelet-derived Transcriptomic Codes In Aortic Aneurysms.

Introduction: Loss of vascular smooth-muscle cells (vSMC) and subsequent defective replenishment of functional vSMC de novo are pathological hallmarks of abdominal aortic aneurysm (AAA). Evidence suggests that clusters of progenitors can be reprogrammed into vSMC lineage following vascular injury. However, the landscape of vSMC precursors and reprograming signatures that determine their fate in AAA is undefined. Hypothesis: We hypothesize that quiescent progenitor pools reside in aorta and undergo spatiotemporal fate decision into mature vSMC in AAA. We speculate that distinct ligand-receptor and transcriptional signals gear their pathogenic trajectories into dysfunctional vSMC in AAA. Methods & Results: Single-cell RNA-sequencing (scRNA-seq) identified vascular progenitor cells (Cd34 + Pdgfra + ) in murine (angiotensin II-induced) and human AAA. Pseudotime analysis tracked two differentiation fates of progenitors into divergent mature vSMC pools characterized by enrichment in contractile cytoskeleton machinery (Acta2 + Myh11 + ) or abnormally supplemented with matrix remodeling genes (Mmp2 + Col8a1 + ). Mmp2 + Col8a1 + clusters were dominant in AAA suggesting pathological reprograming in AAA. Gene regulatory network analysis mapped distinct libraries of upstream transcription factors in each mature vSMC states in AAA. Acta2 + Myh11 + and Mmp2 + Col8a1 + transcriptomes were driven by opposing actions of Pparg and its repressor Runx1 respectively. Interestingly, cellular interaction analysis revealed that platelet-derived Pdgfb fueled the phenotypic switch into Mmp2 + Col8a1 + vSMC via its receptor Pdgfra. Dampening Pdgfra signaling by systemic platelet depletion repressed Runx1 activation thereby increasing Pparg transcriptomic activity in progenitors in the aortic wall. This rescued functional regeneration of vSMC (Acta2 + Myh11 + ) with contractile properties consistent with reduced aortic damage and diminished AAA incidence. Conclusion: Our data demonstrate that platelets are novel actors capable of awakening progenitor pools by coding their fate into pathogenic vSMC lineage in AAA. We provide evidence suggesting that strategies aimed at sustaining vSMC contractile destiny could encourage repair of vascular damage in AAA.

In This Issue

HomeCirculation ResearchVol. 130, No. 5In This Issue Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessIn BriefPDF/EPUBIn This Issue Ruth Williams Ruth WilliamsRuth Williams Search for more papers by this author Originally published3 Mar 2022https://doi.org/10.1161/RES.0000000000000536Circulation Research. 2022;130:691is related toEro1α-Dependent ERp44 Dissociation From RyR2 Contributes to Cardiac ArrhythmiaGLP1R Attenuates Sympathetic Response to High Glucose via Carotid Body InhibitionInhibition of IL11 Signaling Reduces Aortic Pathology in Murine Marfan SyndromeGLP1R Attenuates Sympathetic Response to High Glucose via Carotid Body Inhibition (p 694)Gut hormone receptors in the carotid body may be treatment targets for metabolic syndrome, say Pauza et al.Download figureDownload PowerPointHypertension and diabetes are risk factors for cardiovascular disease (CVD) and yet, for many patients with these two conditions, lowering blood pressure and blood sugar is insufficient for eliminating the risk. Because both hypertension and diabetes are linked to increased sympathetic nerve activation, and because the carotid body (CB)—a clusters of sensory cells in the carotid artery—regulates sympathetic nerve activity, Pauza and colleagues investigated the CB’s possible involvement. They performed a transcriptome analysis of CB tissue from rats with and without spontaneous hypertension and found, among many differently expressed genes, that the transcript encoding glucagon-like peptide-1 receptor (GLP1R) was considerably less abundant in the hypertensive animals. This was of particular interest because the gut hormone GLP1 promotes insulin secretion and tends to be suppressed in type 2 diabetes. Moreover, GLP1R agonists are already used as diabetes treatments. The team now show that treating rat CBs with such an agonist suppresses sympathetic nerve activation and arterial blood pressure, suggesting such drugs may provide benefits in more ways than one, and that the CB could be a novel target for lowering CVD risk in metabolic syndrome.Ero1α-Dependent ERp44 Dissociation from RyR2 Contributes to Cardiac Arrhythmia (p 711)Blocking oxidoreductase Ero1α could reduce arrhythmia risk in cardiovascular disease, say Hamilton et al.Download figureDownload PowerPointThe oxidative stress associated with cardiovascular disease (CVD) can lead to heart arrhythmia and sudden death. At the cellular level, the increased oxidation in the sarcoplasmic reticulum (SR) triggers aberrant release of calcium—via the ryanodine receptor (RyR2) channel—and this in turn ramps up muscle contractions. However, the precise molecular details of the pathology are lacking. Cellular stress is known to raise the level of SR oxidoreductase Ero1α, which interacts with an inhibitor of calcium release called ERp44. Now, Hamilton and colleagues complete the molecular puzzle, showing that ERp44 normally binds and inhibits RyR2 in rat cardiomyocytes. The stress-induced increase in Ero1α expression (in hypertrophic rat cardiomyocytes) causes dissociation of ERp44 from RyR2, they report, thus boosting calcium release. Importantly, the team also showed that inhibiting Ero1α reduced oxidation in the SR, prevented ERp44-RyR2 disassociation and reduced RyR2-mediated calcium release. It also curbed arrhythmia in isolated hypertrophic hearts. Because myocardium from heart failure patients also exhibited increased Ero1α expression compared with controls, the authors say, Ero1α inhibition could be a clinical strategy for preventing CVD-associated arrhythmia.Inhibition of IL11 Signaling Reduces Aortic Pathology in Murine Marfan Syndrome (p 728)Lim et al suggest cytokine IL-11 as a new target for the treatment of Marfan syndrome.Download figureDownload PowerPointPeople with the genetic connective tissue disorder Marfan syndrome (MFS) are typically tall and thin with long limbs, and are prone to skeletal, eye and cardiovascular problems including a life-threatening weakening of the aorta. While MFS patients commonly take blood-pressure lowering treatments to minimize the risk of aortic aneurysm and dissection, there is no cure for MFS nor even a targeted therapy. With the aim of finding novel MFS treatments, Lim and colleagues focused their attention on IL-11. This cytokine is strongly induced in vascular smooth muscle cells (VSMCs) upon treatment with the growth factor TGFβ—itself overactivated in MFS patients and considered a key feature of the syndrome’s molecular pathology. The team now show that IL-11 is indeed strongly upregulated in the aortas of MFS model mice and that genetically eliminating IL-11 in these animals can protect them against the aortic pathology they normally exhibit—including dilation, fibrosis, inflammation, elastin degradation and loss of VSMCs. Furthermore, treating MFS mice with an anti-IL-11 neutralizing antibody had the same beneficial effects. The results therefore suggest that inhibiting IL-11 activity could be a novel approach for protecting the aortas of MFS patients. Previous Back to top Next FiguresReferencesRelatedDetailsRelated articlesEro1α-Dependent ERp44 Dissociation From RyR2 Contributes to Cardiac ArrhythmiaShanna Hamilton, et al. Circulation Research. 2022;130:711-724GLP1R Attenuates Sympathetic Response to High Glucose via Carotid Body InhibitionAudrys G. Pauza, et al. Circulation Research. 2022;130:694-707Inhibition of IL11 Signaling Reduces Aortic Pathology in Murine Marfan SyndromeWei-Wen Lim, et al. Circulation Research. 2022;130:728-740 March 4, 2022Vol 130, Issue 5Article InformationMetrics © 2022 American Heart Association, Inc.https://doi.org/10.1161/RES.0000000000000536 Originally publishedMarch 3, 2022 PDF download Advertisement

Inhibition of IL11 Signaling Reduces Aortic Pathology in Murine Marfan Syndrome.

Marfan syndrome (MFS) is associated with TGF (transforming growth factor) β-stimulated ERK (extracellular signal-regulated kinase) activity in vascular smooth muscle cells (VSMCs), which adopt a mixed synthetic/contractile phenotype. In VSMCs, TGFβ induces IL (interleukin) 11) that stimulates ERK-dependent secretion of collagens and MMPs (matrix metalloproteinases). Here, we examined the role of IL11 in the MFS aorta. We used echocardiography, histology, immunostaining, and biochemical methods to study aortic anatomy, physiology, and molecular endophenotypes in Fbn1C1041G/+ mice, an established murine model of MFS (mMFS). mMFS mice were crossed to an IL11-tagged EGFP (enhanced green fluorescent protein; Il11EGFP/+) reporter strain or to a strain deleted for the IL11 receptor (Il11ra1-/-). In therapeutic studies, mMFS were administered an X209 (neutralizing antibody against IL11RA [IL11 receptor subunit alpha]) or IgG for 20 weeks and imaged longitudinally. IL11 mRNA and protein were elevated in the aortas of mMFS mice, as compared to controls. mMFS mice crossed to Il11EGFP/+ mice had increased IL11 expression in VSMCs, notably in the aortic root and ascending aorta. As compared to the mMFS parental strain, double mutant mMFS:Il11ra1-/- mice had reduced aortic dilatation and exhibited lesser fibrosis, inflammation, elastin breaks, and VSMC loss, which was associated with reduced aortic COL1A1 (collagen type I alpha 1 chain), IL11, MMP2/9, and phospho-ERK expression. To explore therapeutic targeting of IL11 signaling in MFS, we administered either a neutralizing antibody against IL11RA (X209) or an IgG control. After 20 weeks of antibody administration, as compared to IgG, mMFS mice receiving X209 had reduced thoracic and abdominal aortic dilation as well as lesser fibrosis, inflammation, elastin breaks, and VSMC loss. By immunoblotting, X209 was shown to reduce aortic COL1A1, IL11, MMP2/9, and phospho-ERK expression. In MFS, IL11 is upregulated in aortic VSMCs to cause ERK-related thoracic aortic dilatation, inflammation, and fibrosis. Therapeutic inhibition of IL11, imminent in clinical trials, might be considered as a new approach in MFS.

Vascular smooth muscle cell aging: Insights from Hutchinson-Gilford progeria syndrome

Vascular smooth muscle cells (VSMCs) constitute the principal cellular component of the medial layer of arteries and are responsible for vessel contraction and relaxation in response to blood flow. Alterations in VSMCs can hinder vascular system function, leading to vascular stiffness, calcification and atherosclerosis, which in turn may result in life-threatening complications. Pathological changes in VSMCs typically correlate with chronological age; however, there are certain conditions and diseases, such as Hutchinson-Gilford progeria syndrome (HGPS), that can accelerate this process, resulting in premature vascular aging. HGPS is a rare genetic disorder characterized by severe VSMC loss, accelerated atherosclerosis and death from myocardial infarction or stroke during the adolescence. Because experiments with mouse models have demonstrated that alterations in VSMCs are responsible for early atherosclerosis in HGPS, studies on this disease can provide insights into the mechanisms of vascular aging and assess the relative contribution of VSMCs to this process.

Yes-associated protein reacts differently in vascular smooth muscle cells under different intensities of mechanical stretch.

Vascular smooth muscle cells (VSMCs) are stromal cells of the vascular wall and are continually exposed to mechanical signals. The loss of VSMCs is closely related to the occurrence of many vascular diseases, such as aortic aneurysms and aortic dissection. The proliferation and apoptosis of VSMCs are mechanically stimulated. Yes-associated protein (YAP), one of the core components of the Hippo pathway, plays a key role in the response of VSMCs to mechanical signals. In this study, we tested the impact of different intensities of mechanical stretch on the proliferation and apoptosis of VSMCs, as well as YAP. We tested VSMCs’ proliferation and apoptosis and YAP reaction via immunocytochemistry, western blotting, CCK-8 and flow cytometric analysis. We found that 10% elongation could increase the phosphorylation of YAP and prevent it from entering the nucleus, as well as inhibit cell proliferation and promote apoptosis. However, 15% elongation reduced YAP phosphorylation and promoted its nuclear entry, thereby promoting cell proliferation and inhibiting apoptosis. Accordingly, YAP knockdown suppressed the phenotype of VMSCs induced by 15% elongation. Taken together, YAP regulates proliferation and apoptosis of VSMCs differently under different intensity of mechanical stretch. Mechanical stretch with appropriate intensity can promote the proliferation and inhibit apoptosis of VSMCs by activating YAP.

Vascular Smooth Muscle Cells in Aortic Aneurysm: From Genetics to Mechanisms.

Aortic aneurysm, including thoracic aortic aneurysm and abdominal aortic aneurysm, is the second most prevalent aortic disease following atherosclerosis, representing the ninth‐leading cause of death globally. Open surgery and endovascular procedures are the major treatments for aortic aneurysm. Typically, thoracic aortic aneurysm has a more robust genetic background than abdominal aortic aneurysm. Abdominal aortic aneurysm shares many features with thoracic aortic aneurysm, including loss of vascular smooth muscle cells (VSMCs), extracellular matrix degradation and inflammation. Although there are limitations to perfectly recapitulating all features of human aortic aneurysm, experimental models provide valuable tools to understand the molecular mechanisms and test novel therapies before human clinical trials. Among the cell types involved in aortic aneurysm development, VSMC dysfunction correlates with loss of aortic wall structural integrity. Here, we discuss the role of VSMCs in aortic aneurysm development. The loss of VSMCs, VSMC phenotypic switching, secretion of inflammatory cytokines, increased matrix metalloproteinase activity, elevated reactive oxygen species, defective autophagy, and increased senescence contribute to aortic aneurysm development. Further studies on aortic aneurysm pathogenesis and elucidation of the underlying signaling pathways are necessary to identify more novel targets for treating this prevalent and clinical impactful disease.

Abstract 10730: Vascular Smooth Muscle Cell Phenotypic Switch and Replication Stress as a Key Contributors in CVD in HGPS

Hutchinson Gilford Progeria Syndrome is a premature aging disease caused by LMNA gene mutation and production of a truncated lamin A protein “progerin” that elicits cellular and organismal toxicity. Patients show severe aging phenotypes, including alopecia, reduced fat and bone density, and cardiovascular disease (CVD), which ultimately causes their death as teenagers. HGPS has no cure and clinical trials obtained only minor benefits. It is urgent to identify mechanisms of progerin toxicity to target therapeutically. Progerin accumulates preferentially in the vasculature, being especially toxic for vascular smooth muscle cells (VSMC). Patients' autopsies show that vessel stiffening and aortic atherosclerosis are accompanied by VSMCs depletion in the media, increased extracellular matrix (ECM), and adventitia thickening. Mechanisms whereby progerin causes massive VSMC loss and ECM accumulation are unknown. We previously demonstrated that progerin expression in fibroblasts hinders DNA replication, causes genomic instability, and triggers a phenotypic switch towards activated fibroblasts/myofibroblasts. These cells are known to promote tissue fibrosis by ECM deposition and release of inflammatory cytokines. VSMCs can also undergo phenotypic modulation or de-differentiation, a process whereby contractile cells revert to a synthetic/proliferative phenotype, leading to pathological accumulation of ECM and CVD. Here we show that progerin expression in VSMCs causes a switch towards the synthetic/proliferative phenotype. Similarly to fibroblasts, progerin represents a challenge for DNA replication in VSMC, triggering replication stress, genomic instability and ultimately VSMC death. Importantly, we found that calcitriol -hormonal active form of vitamin D- prevents VSMC switch and replication stress. Our data suggest that replication stress might be an underlying cause of VSMC loss in progeria and that preventing the phenotypic switch-induced replication stress with compounds such as calcitriol might prevent the massive loss of VSMC and the vascular stiffness in HGPS patients.

Cardiovascular Progerin Suppression and Lamin A Restoration Rescue Hutchinson-Gilford Progeria Syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare disorder characterized by premature aging and death mainly because of myocardial infarction, stroke, or heart failure. The disease is provoked by progerin, a variant of lamin A expressed in most differentiated cells. Patients look healthy at birth, and symptoms typically emerge in the first or second year of life. Assessing the reversibility of progerin-induced damage and the relative contribution of specific cell types is critical to determining the potential benefits of late treatment and to developing new therapies. We used CRISPR-Cas9 technology to generate LmnaHGPSrev/HGPSrev (HGPSrev) mice engineered to ubiquitously express progerin while lacking lamin A and allowing progerin suppression and lamin A restoration in a time- and cell type-specific manner on Cre recombinase activation. We characterized the phenotype of HGPSrev mice and crossed them with Cre transgenic lines to assess the effects of suppressing progerin and restoring lamin A ubiquitously at different disease stages as well as specifically in vascular smooth muscle cells and cardiomyocytes. Like patients with HGPS, HGPSrev mice appear healthy at birth and progressively develop HGPS symptoms, including failure to thrive, lipodystrophy, vascular smooth muscle cell loss, vascular fibrosis, electrocardiographic anomalies, and precocious death (median lifespan of 15 months versus 26 months in wild-type controls, P<0.0001). Ubiquitous progerin suppression and lamin A restoration significantly extended lifespan when induced in 6-month-old mildly symptomatic mice and even in severely ill animals aged 13 months, although the benefit was much more pronounced on early intervention (84.5% lifespan extension in mildly symptomatic mice, P<0.0001, and 6.7% in severely ill mice, P<0.01). It is remarkable that major vascular alterations were prevented and lifespan normalized in HGPSrev mice when progerin suppression and lamin A restoration were restricted to vascular smooth muscle cells and cardiomyocytes. HGPSrev mice constitute a new experimental model for advancing knowledge of HGPS. Our findings suggest that it is never too late to treat HGPS, although benefit is much more pronounced when progerin is targeted in mice with mild symptoms. Despite the broad expression pattern of progerin and its deleterious effects in many organs, restricting its suppression to vascular smooth muscle cells and cardiomyocytes is sufficient to prevent vascular disease and normalize lifespan.

Fcγ receptor activation mediates vascular inflammation and abdominal aortic aneurysm development.

BackgroundAbdominal aortic aneurysm (AAA), a degenerative vascular pathology characterized by permanent dilation of the aorta, is considered a chronic inflammatory disease involving innate/adaptive immunity. However, the functional role of antibody‐dependent immune response against antigens present in the damaged vessel remains unresolved. We hypothesized that engagement of immunoglobulin G (IgG) Fc receptors (FcγR) by immune complexes (IC) in the aortic wall contributes to AAA development. We therefore evaluated FcγR expression in AAA lesions and analysed whether inhibition of FcγR signaling molecules (γ‐chain and Syk kinase) influences AAA formation in mice.MethodsFcγR gene/protein expression was assessed in human and mouse AAA tissues. Experimental AAA was induced by aortic elastase perfusion in wild‐type (WT) mice and γ‐chain knockout (γKO) mice (devoid of activating FcγR) in combination with macrophage adoptive transfer or Syk inhibitor treatment. To verify the mechanisms of FcγR in vitro, vascular smooth muscle cells (VSMC) and macrophages were stimulated with IgG IC.ResultsFcγR overexpression was detected in adventitia and media layers of human and mouse AAA. Elastase‐perfused γKO mice exhibited a decrease in AAA incidence, aortic dilation, elastin degradation, and VSMC loss. This was associated with (1) reduced infiltrating leukocytes and immune deposits in AAA lesions, (2) inflammatory genes and metalloproteinases downregulation, (3) redox balance restoration, and (4) converse phenotype of anti‐inflammatory macrophage M2 and contractile VSMC. Adoptive transfer of FcγR‐expressing macrophages aggravated aneurysm in γKO mice. In vitro, FcγR deficiency attenuated inflammatory gene expression, oxidative stress, and phenotypic switch triggered by IC. Additionally, Syk inhibition prevented IC‐mediated cell responses, reduced inflammation, and mitigated AAA formation.ConclusionOur findings provide insight into the role and mechanisms mediating IgG‐FcγR‐associated inflammation and aortic wall injury in AAA, which might represent therapeutic targets against AAA disease.