Arteriosclerosis, Thrombosis, and Vascular Biology

ABSTRACT Endothelial cells (ECs) display marked vascular bed-specific heterogeneity, and their inflammation-induced activation is a central feature of vascular pathology. However, whether inflammatory responses are primarily shaped by intrinsic organotypic endothelial identity or by the inflammatory stimulus itself remains largely unknown. To address this question, we compared the temporal responses of brain- (hCMEC/D3), skin- (HMEC-1), and lung-derived (HuLEC-5a) human microvascular ECs to lipopolysaccharide (LPS) and interleukin-6 (IL-6/IL-6R). Across all conditions, endothelial origin was the dominant determinant of transcriptional variation, outweighing the effects of both the inflammatory stimulus and exposure time. Brain-, skin- and lung-derived ECs exhibited distinct basal inflammatory and innate immune gene expression programs and responded differently to both LPS and IL-6/IL-6R. LPS induced a rapid but largely transient response, whereas IL-6/IL-6R elicited more sustained inflammatory changes. Although transcriptional profiling identified a shared inflammatory signature across EC populations, most differentially expressed genes were vascular bed specific. These molecular differences translated into distinct functional outcomes: IL-6/IL-6R increased endothelial permeability and promoted more sustained metabolic adaptations, whereas LPS induced robust inflammatory activation without persistent barrier dysfunction. Collectively, these findings demonstrate that while inflammatory stimuli determine which signaling pathways are activated, intrinsic endothelial identity dictates the magnitude, kinetics, and functional consequences of the inflammatory response. Our results highlight the importance of incorporating vascular bed specificity into experimental models and the development of therapies targeting endothelial dysfunction and inflammation.

Background: Macrophage foam cell formation is a central event in atherosclerosis. Although protein ubiquitination is increasingly recognized as a regulator of macrophage lipid handling, whether deubiquitinating enzymes directly control lipid uptake and metabolic remodeling during atherogenesis remains unclear. Methods and Results: Here, transcriptomic profiling identified ubiquitin-specific protease 20 (USP20) as a previously unrecognized regulator of macrophage foam cell formation. Genetic and pharmacological studies demonstrated that USP20 promoted macrophage lipid accumulation and foam cell formation, whereas macrophage-specific Usp20 deficiency markedly attenuated atherosclerotic lesion formation, lipid deposition, and macrophage accumulation in mice. To elucidate the underlying mechanism, integrative analysis of USP20-interacting proteins and proteomic alterations in Usp20-deficient macrophages identified fatty acid-binding protein 5 (FABP5) as a substrate of USP20. Mechanistically, USP20 interacted with FABP5 and stabilized its protein abundance by preventing ubiquitin-dependent proteasomal degradation. Consequently, USP20-mediated stabilization of FABP5 enhanced PPAR{gamma} occupancy at the Cd36 promoter, thereby increasing Cd36 transcription, ox-LDL uptake, and foam cell formation. Accordingly, Fabp5 knockdown abolished USP20-induced CD36 expression, ox-LDL uptake, and foam cell formation, whereas pharmacological activation of PPAR{gamma} restored CD36 expression in Fabp5-deficient macrophages. Finally, macrophage-targeted delivery of the USP20 inhibitor GSK2643943A markedly reduced atherosclerotic burden without evident systemic toxicity, supporting the therapeutic potential of targeting USP20 in atherosclerosis. Conclusions: USP20 promotes macrophage foam cell formation by stabilizing FABP5 and enhancing PPAR{gamma}-dependent Cd36 transcription. Targeting the USP20-FABP5-PPAR{gamma}-CD36 axis may represent a therapeutic strategy to limit macrophage lipid accumulation, metabolic dysfunction, and atherosclerosis progression.

Atherosclerosis is a chronic inflammatory disease primarily initiated by the sub-endothelial retention and modification of low-density lipoproteins (LDL), such as oxidation and aggregation. While oxidized LDL (oxLDL) exists in atherosclerotic lesions, aggregated lipoproteins are also prominent. Aggregated LDL (agLDL), for instance, is viewed as a passive substrate for macrophages to uptake and form foam cells. Recent studies show that agLDL, through toll-like receptor 4 (TLR4), induces formation of lysosomal synapses, which drive agLDL degradation by macrophages, a process described as "digestive exophagy". As TLR4 is one of the pattern-recognition receptors for inflammatory responses in macrophages, we postulated that agLDL could initiate macrophage inflammation along with lipoprotein degradation/internalization, thereby contributing to a low degree of chronic inflammation in atherosclerosis. Here, we demonstrate that agLDL directly activates the canonical NF-{kappa}B signaling pathway and triggers a pro-inflammatory transcriptional program through TLR4, which closely resembles classical lipopolysaccharide (LPS)-mediated TLR4 activation. In addition, agLDL also activates TLR4 to generate inflammatory macrophages that recruit immune cells, a key process in the development of atherosclerotic lesions. Our findings therefore support a novel dual functionality of agLDL: a lipid donor and an inflammatory agonist. This establishes the agLDL-TLR4-NF-{kappa}B axis as a direct link between LDL aggregation in the intima and the initiation of sterile vascular inflammation. It also strengthens the understanding of the role of digestive exophagy with new mechanistic details.

Background: Platelets are critical drivers of thrombo-inflammatory responses in different cardiovascular diseases. Abdominal aortic aneurysm (AAA) is a progressive, life-threatening vascular disorder mainly characterised by chronic inflammation, extracellular matrix degradation, and the formation of a platelet-rich intraluminal thrombus (ILT). Experimental and clinical evidence identified platelets as main players in AAA pathology as evidenced by elevated platelet activation and procoagulant activity that critically contribute to AAA progression. Methods: The present study investigated the contribution of glycoprotein (GP)Ib alpha, the von Willebrand factor (VWF)-binding subunit of the platelet GPIb-IX-V complex, to AAA initiation and progression in experimental AAA using the ePPE mouse model and in patients. Results: Genetic ablation of platelet GPIb alpha significantly attenuated early aneurysm expansion in experimental AAA, indicating a critical role for GPIb alpha during the initial stages of aneurysm development. This initial effect was compensated at later time points showing no differences in aneurysm progression between groups. Notably, genetic deletion of GPIb alpha induced a constitutively hyperactive platelet phenotype already in naive mice that was further amplified during experimental AAA. This elevated platelet hyperactivity was mainly due to increased GPVI activation of platelets 28 days post-surgery. To assess the clinical relevance, spatial profiles of human ILT specimens from patients with AAA were analysed. In the ILT, we detected a highly compartmentalised distribution of GPIb alpha and VWF with pronounced enrichment within the luminal layer. In parallel, circulating VWF activity as well as platelet surface expression of GPIb alpha were significantly increased in patients with AAA. Conclusion: Collectively, these findings identify a dysregulated GPIb alpha-VWF axis in human AAA pathology, mainly characterised by enhanced platelet GPIb alpha surface expression and increased activity of circulating VWF.

Objective: The maturation of an autologous arteriovenous fistula (AVF) depends on the coordinated hemodynamic adaptation of the inflow artery and the outflow vein. While venous remodeling has been extensively studied, the mechanisms of arterial adaptation are poorly understood. We addressed this knowledge gap with the first temporal single-cell atlas of the porcine AVF model. Methods: Six Yorkshire pigs underwent bilateral femoro-femoral AVF creation for tissue harvest at 2 and 21 days postoperatively or sham operation to collect native vessels after 2 days. Arteries and veins were analyzed by droplet-based single-cell RNA sequencing, histology, and immunohistochemistry. Results: All fistulas were patent, with flows reaching 1185.0 +/- 170.6 mL/min despite mild to moderate neointima formation in the veins. Arteries and veins demonstrated >60% endothelial denudation and increased neovascularization. Arterial remodeling was characterized by a progressive increase in venous-like transcriptional features. Arteries presented a venous-like endothelial cell (EC) composition at 21 days postop and a temporal increase in venous-associated phenotypes of myofibroblasts and fibroblasts. In both vessels, the latter populations were the main bearers of mechanosensitive signatures at 2 days. Despite the temporal convergence in phenotypes, arteries and veins retained vessel-selective characteristics. Arterial ECs expressed high levels of nitric oxide synthase, whereas venous ECs were largely inflammatory. Arterial myofibroblasts and fibroblasts had higher expression of Notch signaling transducers (HEY2, HEYL) and cellular communication network factors (CCN3, CCN5), while Wnt signaling regulators (DKK2, SFRP4) and complement genes (C3, C7, CFD) were upregulated in veins. Anti-inflammatory macrophages increased in both vessels during remodeling, likely contributing to the maturation of the fistulas. Conclusion: These analyses challenge the traditional paradigm of exclusive vein arterialization and support a complementary process of arterial venification after anastomosis. Recognition of this underappreciated phenomenon may reshape our understanding of AVF biology and guide the discovery of both vascular-wide and vessel-selective anti-stenotic therapies.

Background: Calcific aortic valve disease (CAVD) is characterized by progressive inflammatory and fibrocalcific remodeling. Although valvular interstitial cells (VICs) are generally considered to drive fibrosis and osteogenic remodeling, whether injury-activated VICs mount endogenous protective responses that preserve the valvular interstitial microenvironment and restrain calcification remains unknown. Methods: We performed spatial transcriptomic profiling of aortic valves in a mouse model of endothelial injury-induced CAVD to define early injury-responsive programs within the valvular interstitium. The cellular origin and spatial distribution of candidate protective factors were examined by immunohistochemistry and lineage tracing, and their relevance to human disease was assessed using stenotic aortic valves. The functional role of CTHRC1 was investigated using genetic Cthrc1 deficiency combined with longitudinal hemodynamic assessment, histological analysis, and spatial transcriptomic profiling. Results: Spatial transcriptomics identified Cthrc1 as a prominent component of an early injury-induced stromal response in the expanding valvular interstitium. CTHRC1 was strongly expressed in activated VICs within thickened murine valve leaflets and human stenotic aortic valves. Lineage tracing demonstrated that the expanded VIC population arose predominantly from PDGFR{beta}+ resident interstitial cells, with minimal endothelial contribution. Despite comparable early hemodynamic responses to endothelial injury, Cthrc1 deficiency exacerbated chronic valvular calcification. Spatial profiling of Cthrc1-deficient valves revealed pronounced interstitial accumulation of galectin-3+ foamy macrophages, accompanied by mitochondrial respiratory-chain signature loss and cell death-associated pathway activation. These findings indicate that transient CTHRC1 induction after endothelial injury defines an endogenous stromal protective response that preserves the valvular interstitial microenvironment and limits macrophage-associated tissue injury and subsequent dystrophic calcification. Conclusions: Injury-activated VICs are not merely effectors of pathological remodeling, but can engage an endogenous tissue-protective response through CTHRC1. These findings identify a previously unrecognized stromal defense mechanism linking endothelial injury to macrophage-associated inflammatory remodeling and dystrophic calcification and suggest CTHRC1-dependent stromal protection as a potential therapeutic axis for limiting CAVD progression.

Background: Autophagy is a homeostatic pathway supporting stress adaptation and is dysregulated in atherosclerosis. Its potential as a biomarker or therapeutic target in atherosclerotic vascular disease (ASVD) remains incompletely defined. We measured autophagic flux in peripheral blood mononuclear cells (PBMCs) from patients with peripheral arterial disease (PAD) or carotid stenosis (CS), compared with healthy controls, and explored clinical outcome associations. Methods: Ninety-four patients with PAD or CS and 19 healthy controls were studied. Autophagic flux was quantified from fresh blood using a validated ex vivo chloroquine inhibition ELISA measuring LC3BII accumulation. Major adverse cardiovascular events (MACE) and major adverse limb events (MALE) were ascertained over a median follow up of 828 days. Results: The ASVD cohort comprised claudication (n = 16), chronic limb threatening ischemia (CLTI; n = 49), and CS (n = 29). Autophagic flux was higher in ASVD than controls (mean 281.4 vs. 182.3 ng LC3BII/mg protein/h; p < 0.0001) and remained independently associated after multivariable adjustment. Within CLTI, concurrent infection was associated with lower flux (p = 0.001), approaching control levels (p = 0.327). In CLTI, higher flux quartiles were associated with lower MACE risk, most strongly for quartile 3 (hazard ratio 0.07 vs. quartile 1, 95% CI 0.01 to 0.50; p = 0.009). Conclusion: Autophagic flux is elevated in PBMCs from ASVD patients, independent of age and sex. Attenuated flux in CLTI with concurrent infection may indicate autophagic exhaustion in advanced disease. The association between higher flux and lower MACE in CLTI suggests prognostic utility, warranting evaluation in larger prospective studies.

Pulmonary lymphatic vessels are essential for interstitial fluid balance and macromolecular clearance, yet the endothelial mechanisms regulating lymphatic vessel function during chronic fibroproliferative lung injury remain undefined. Here, we demonstrate that the lineage-defining transcription factor ERG in lymphatic endothelial cells (LECs) governs junctional plasticity and fluid drainage in pulmonary fibrosis. In human idiopathic pulmonary fibrosis (IPF) lungs, lymphatic ERG expression is markedly downregulated. Lineage-specific inducible deletion of Erg in murine LECs (Erg-CKO) unexpectedly conferred robust protection against bleomycin-induced pulmonary fibrosis, significantly dampening acute inflammation, reducing edema, and preserving pulmonary compliance. Mechanistically, loss of ERG enhanced lymphatic drainage capacity in vivo. Transcriptomic profiling of isolated LECs revealed that ERG deficiency activates actomyosin contractile pathways and selectively upregulates Endothelin Receptor Type B (Ednrb), driving junctional remodeling from continuous zippers into discontinuous button-like configurations that facilitate interstitial fluid entry. Pharmacological blockade of EDNRB with BQ-788 abolished junctional reorganization, eliminated the enhanced lymphatic drainage, and completely reversed the anti-fibrotic protection in Erg-CKO mice. Together, our findings identify an endothelial ERG-EDNRB regulatory axis that controls lymphatic junctional architecture and demonstrate that promoting lymphatic clearance via endothelial junctional remodeling represents a viable therapeutic strategy for fibrotic vascular remodeling.

Background: Calcific aortic valve disease (CAVD) is the most common valvular heart disease in older adults and currently has no approved pharmacological therapy to prevent or slow disease progression. Aortic valve replacement, either surgically or by transcatheter aortic valve implantation (TAVI), therefore remains the only effective treatment for severe CAVD. Monocytes play an important role in driving inflammation and disease progression in CAVD. As the disease progresses and the aortic valve becomes increasingly stenotic, circulating monocytes passing through the narrowed valve are repeatedly exposed to pathological haemodynamic forces, including markedly elevated shear stress, before their recruitment into the valve tissue. However, how exposure to these mechanical forces reprograms circulating monocytes influences their subsequent responses within the valve remain poorly understood. Methods and Results: In this study, we used an engineered model of aortic valve stenosis combined with phosphoproteomic profiling to investigate how prolonged exposure to pathological shear stress reprograms circulating monocytes and influences their subsequent phenotype and function following recruitment into the valve matrix. We further used TAVI as a unique clinical model to determine whether restoration of physiological haemodynamics in patients with severe aortic stenosis reverses the shear-induced monocyte phenotype observed in our experimental model. We found that prolonged exposure of monocytes to pathological shear stress induced extensive remodelling of the proteomic and phosphoproteomic landscape, with enrichment of pathways associated with cellular metabolism, cytoskeletal organisation, and inflammatory signalling. Kinase activity analysis further identified increased protein kinase C (PKC) activity accompanied by suppression of AKT signalling. Consistent with these molecular changes, pathological shear stress increased actin polymerisation, mitochondrial membrane potential, intracellular calcium signalling, and PKC activity. Using a bioengineered extracellular matrix model that recapitulates the glycosaminoglycan-rich microenvironment of the stenotic aortic valve we found that prior exposure to pathological shear stress altered monocyte-to-macrophage differentiation, reducing oxidised LDL uptake and foam-cell formation while promoting co-expression of CD80 and CD163, indicative of a mixed macrophage phenotype. Finally, using a myeloid-specific Piezo1 knockout mouse model, we identified Piezo1 as a key mechanosensor linking pathological shear stress to PKC activation, mitochondrial responses, and persistent changes in monocyte phenotype following migration into the extracellular matrix. Conclusions: These findings establish a mechanistic link between abnormal valve haemodynamics, metabolic and inflammatory reprogramming of circulating monocytes, extracellular matrix remodelling, and immune dysregulation during CAVD progression, highlighting monocyte mechanotransduction and downstream PKC/Piezo1 signalling as potential therapeutic targets.

Giant cell arteritis (GCA) is an immune-mediated vasculitis that can cause serious morbidity including sight loss, stroke and aortic aneurysm. There is an unmet need for blood-based biomarkers and novel therapeutics. We measured plasma protein levels using the SomaScan v4.1 platform, comprising 7,273 protein measurements (SOMAmers) reflecting 6,596 unique protein targets. We profiled the proteome in 113 patients who presented acutely with possible GCA. 56 had biopsy-proven GCA and 57 did not have GCA (non-GCA). We found 144 SOMAmers increased and 151 reduced in GCA. Dysregulated biological pathways included IL6-JAK-STAT3 signalling, chemokines for both myeloid (e.g. CXCL2, CXCL3, CCL18, CCL23) and lymphoid cells (e.g. CXCL9, CXCL13), and the complement system (e.g. C9, CFHR5, C5a, Factor B). Enzyme-Linked Immunosorbent Assays (ELISAs) confirmed elevated plasma levels of C5a, the terminal complement complex, Factor B and CFHR5 in GCA. We developed a 26-protein signature that distinguished GCA from non-GCA (area-under-the curve, AUC, 0.93) and validated the diagnostic signature in external datasets. Our data implicate terminal complement pathway activation in GCA, raising the possibility of complement-directed therapies. We show proof-of-principle that a multiplex protein biomarker could be used as a diagnostic adjunct in suspected GCA.

Pulmonary arterial hypertension (PAH) is characterized by the hyperproliferative phenotype of pulmonary arterial smooth muscle cells (PAVSMCs) and extensive extracellular matrix (ECM) remodeling. Vacuolar protein sorting 34 (VPS34), a Class III Phosphatidylinositol-3 Kinase (PI3K), regulates cell proliferation, but its specific function in pulmonary vascular remodeling remains poorly understood. We aim to determine the role of VPS34 activation and regulation in PAVSMC proliferation, matrix deposition, and the progression of PAH. First, we found a marked decrease in the inhibitory phosphorylation of VPS34 at Ser164 (P-S164-VPS34), indicative of constitutive VPS34 activation, in remodeled pulmonary arteries (PAs) from human PAH patients and male mice exposed to Sugen/Hypoxia (SuHx). In human PAH PAVSMCs, siRNA-mediated knockdown of VPS34 or pharmacological inhibition via the selective inhibitor SAR405 significantly blunted cell proliferation and reduced the production of fibronectin, a major component of the remodeled ECM. Mechanistically, we found that Akt activation in PAH PAVSMCs promotes VPS34 activation; Protein Phosphatase 1 Catalytic Subunit Alpha is a potential effector in VPS34 activation; and active VPS34 led to the activation of the mTOR/S6 signaling pathway with tuberous sclerosis complex 2 downregulation. Finally, in vivo treatment with SAR405 attenuated right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in SuHx mice, while concurrently decreasing vascular fibronectin deposition. Our study demonstrates that VPS34 activation, driven by an Akt-mediated loss of the inhibitory P-S164, is crucial in PAVSMC proliferation and fibrotic vascular remodeling in PAH. Targeting the VPS34 axis represents a promising anti-remodeling therapeutic strategy for the treatment of PAH. Keywords: Pulmonary arterial hypertension, vacuolar protein sorting 34, pulmonary vascular remodeling, pulmonary arterial vascular smooth muscle

Background: Calcific aortic valve disease (CAVD) lacks disease-modifying therapy. LDL-cholesterol lowering does not attenuate valvular calcification, suggesting cholesterol-independent drivers. Thus, we tested whether ceramide accumulation drives CAVD and whether inhibiting sphingolipid de novo synthesis is therapeutic. Methods: We integrated lipidomics and proteomics of calcified and non-calcified human aortic valves with matched plasma. Mechanistic effects of ceramides were tested in primary human valvular interstitial cells (VICs). Therapeutic efficacy of serine palmitoyltransferase (SPT) inhibition with Myriocin was evaluated in ApoE-/- mice with PCSK9DY-AAV-driven hyperlipidemia on Western diet using preventive treatment and therapeutic initiation after echocardiographically verified gradient elevation. Myriocin was additionally tested in a normolipidemic wild-type aortic valve wire-injury model. Hemodynamics, valve structure, lipid composition, and cell-state transitions were assessed by echocardiography, histology, lipidomics, and single-cell RNA sequencing. Results: Calcified human valves showed enrichment of long-chain ceramides linked to NF-{kappa}B, endothelial-to-mesenchymal transition (EndMT), and ER-stress/unfolded protein response (UPR) programs, whereas matched plasma sphingolipids were not elevated. In hVICs, long-chain C18 ceramide induced GRP78/BiP, CHOP, and ATF4, activated NF-{kappa}B, and promoted dose-dependent calcification. In vivo, SPT inhibition with Myriocin lowered valvular ceramides, reduced leaflet inflammation and mineralization, and improved cusp separation and transvalvular hemodynamics without lowering plasma LDL-cholesterol. In a therapeutic protocol initiated after gradient elevation, Myriocin halted further hemodynamic progression, providing the first evidence that de novo sphingolipid synthesis can be targeted after established CAVD onset in vivo. Myriocin also attenuated injury-induced stenosis in normolipidemic mice. Single-cell RNA sequencing showed reduced NF-{kappa}B/EndMT and ER-stress signatures and shifted VIC states away from osteogenic phenotypes. Conclusions: Human valve lipidomics and human VIC experiments identify ceramide-driven lipotoxicity as a driver of an ER-stress-NF-{kappa}B-EndMT axis in CAVD. In vivo, de novo sphingolipid synthesis is an actionable, LDL-independent target capable of modifying established hemodynamic disease progression, supporting SPT inhibition as a tractable strategy for medical CAVD therapy.

Background: Thoracic aortic aneurysms enlarge silently and can cause fatal aortic dissection without timely surgical repair, underscoring the need for improved approaches to identify individuals at high risk. Rare pathogenic variants in established heritable thoracic aortic disease (HTAD) genes explain only a subset of familial and fewer nonfamilial thoracic aortic disease (TAD) cases. Methods: We performed phenotype-stratified, genome-wide, gene-based rare-variant burden analyses of ultrarare damaging missense and predicted loss-of-function variants. Primary analyses focused on aortic dissection, thoracic aortic aneurysm requiring surgical repair, and their combined phenotype. Broader thoracic aortic aneurysm (TAA) was evaluated as a secondary phenotype. Discovery analyses were conducted in the UK Biobank and All of Us, followed by independent replication in the Penn Medicine BioBank, Mass General Brigham Biobank, and Million Veteran Program. Discovery and replication results were subsequently combined in an overall fixed-effect, inverse-variance-weighted meta-analysis across up to five biobanks. Implicated genes were further evaluated in additional clinically ascertained TAD cohorts and using single-cell transcriptomic data from human thoracic aortic tissue. Results: Discovery analyses identified 80 genes reaching study-wide significance across the prespecified TAD phenotypes. These included six established and two putative HTAD genes. Fourteen genes demonstrated independent replication support and reached study-wide significance in the overall meta-analysis across up to five biobanks, which included more than 10,000 cases and 880,000 controls. The eight novel candidate genes among these were FNDC3B, ROCK1, URM1, SLFN11, ENPP1, CLEC16A, CREM, and VCAN. Associations were strongest for dissection and TAA requiring surgical repair. Four novel associations were driven exclusively by missense variants. FNDC3B was observed in a family with HTAD, while additional variants were identified primarily in sporadic dissection or aortic surgery cohorts, suggesting that other genetic or physiologic factors may influence penetrance. The implicated genes showed cell-type-specific expression patterns in human thoracic aortic tissue. Conclusions: These findings expand the genetic architecture of TAD by identifying eight novel candidate genes and demonstrate the utility of phenotype-stratified rare variant burden analyses across large biobanks for gene discovery.

BACKGROUND: The chromosome 9p21.3 locus is among the strongest genetic risk loci for cardiovascular disease (CVD), yet the regulatory mechanisms underlying this association remain poorly understood. Previous vascular disease studies focused predominantly on the role of this locus in smooth muscle cell (SMC) dysfunction, whereas its potential role in endothelial cells (ECs) remains less well characterized. Here, we sought to identify candidate regulatory variants at 9p21.3, their distal target genes, and effector transcripts that contribute to CVD-related phenotypes in ECs. METHODS: Promoter capture Hi-C was used to map chromatin interactions at 9p21.3 in primary human ascending aortic SMCs (n=6), supplementing the previously obtained ECs (n=16) dataset. To support the regulatory relevance of these interactions, expression quantitative trait locus analysis was performed in 136 vascular biopsies. Variant effects were prioritized in silico using AlphaGenome. The regulatory activity of the prioritized region was validated using CRISPR activation. RESULTS: Chromatin interaction mapping identified a complex regulatory architecture at the 9p21.3 locus involving 19 putative regulatory elements and 15 genes across ECs and SMCs. MIR31HG showed the most recurrent distal promoter connectivity with the 9p21.3 region. Consistent with the chromatin interaction map, expression of MIR31HG transcripts was associated with genetic variation at the 9p21.3 locus. In ECs, the lncRNA MIR31HG, but not miR-31, was responsive to hemodynamic flow. Depletion of MIR31HG in ECs was associated with endothelial activation. Epigenetic tracks and deep learning predictions highlighted an active enhancer element at 9p21.3, which was subsequently validated by CRISPR activation and increased MIR31HG expression, confirming its capacity to regulate MIR31HG over a large genomic distance of approximately 538 kb. CONCLUSIONS: Altogether, these data implicate lncRNA MIR31HG as a likely effector of the 9p21.3 CVD locus, linking the cis-regulatory element and heritable genetic variation in the respective region to endothelial activation through long-range enhancer regulation.

Pathogenic variants of COL4A1 and COL4A2, which encode the 1 and 2 chains of type IV collagen in vascular basement membranes, cause cerebral small vessel disease and intracerebral hemorrhage, but the signaling mechanisms that precede vascular damage remain incompletely defined. Here, we investigated cerebral arterial function in mice heterozygous for the Col4a2+/G646D mutation. Cerebral pial arteries from aged (12-month-old), but not young (3-month-old), Col4a2+/G646D mice exhibited impaired pressure-induced myogenic tone, whereas downstream parenchymal arterioles retained normal myogenic responsiveness, revealing a segment-selective vascular defect. The frequency of subcellular Ca2+ signals (Ca2+ sparks) generated by the release of Ca2+ through ryanodine receptors (RyR2s) on the sarcoplasmic reticulum (SR) was increased, and large-conductance Ca2+-activated K+ (BK) channel activity was elevated, in cerebral pial artery smooth muscle cells (SMCs) from aged Col4a2+/G646D mice. SR Ca2+ store load and Ryr2 transcript abundance were unchanged in these cells, but Stimulated Emission Depletion super-resolution microscopy revealed that RyR2 protein clusters were enlarged compared with controls. Protein kinase A (PKA) activation reproduced RyR2 cluster enlargement, whereas PKA inhibition normalized RyR2 cluster organization and BK channel activity in SMCs from aged Col4a2+/G646D mice. These findings identify age-associated, PKA-dependent, nanoscale remodeling of RyR2 clusters as a previously unknown mechanism underlying cerebral arterial dysfunction in COL4A2-related disease.

BackgroundThe progression of abdominal aortic aneurysm (AAA) is closely associated with the phenotypic switch of vascular smooth muscle cells (VSMC). While members of the Serine/Arginine-rich splicing factor (SRs) superfamily are increasingly acknowledged for their pivotal role in modulating cell phenotype, the specific contribution of these factors to AAA development has remained underexplored. MethodsThrough integrated analyses the whole transcriptome of human and murine AAA tissues derived from clinical samples and animal models, we identified serine-arginine repeat matrix 4 (SRRM4) as a candidate gene regulating AAA formation. To investigate the role of SRRM4 in AAA formation, we used global and VSMC-specific SRRM4-knockout mice to construct AAA mouse models in two different ways. The impact of SRRM4 on AAA was further investigated in in vivo and in vitro models ResultsElevated levels of SRRM4 mRNA and protein were observed in VSMC from both human and murine AAA tissues. Targeted silencing of SRRM4 in VSMC (but not in endothelial or myeloid cells) significantly attenuated AAA formation in both AngII- and CaCl2-induced mouse models. Our results identify the RE1 silencing transcription factor (REST) as a critical target gene of SRRM4 in AAA, a master regulator of cellular phenotypic stability. We show that SRRM4 modulates VSMC phenotype through alternative splicing of the REST gene, resulting in a non-functional REST4 isoform. Furthermore, our study shows that REST directly represses STAT1, a mechanism by which SRRM4 influences VSMC phenotypic transition. Regarding clinical significance, inhibition of both STAT1 expression and function was shown to be beneficial in preventing AAA formation and slowing disease progression in mouse models. ConclusionsThis investigation uncovers a previously unrecognized role of SRRM4-mediated splicing of the REST gene in the progression of AAA and identifies a novel REST/STAT1 axis critical in the phenotypic modulation of VSMC. The findings of this study may provide insights for the development of innovative therapeutic strategies for AAA. What is New?O_LIOur study demonstrates that the RNA splicing factor SRRM4 (serine/arginine repetitive matrix 4) expression is increased in human and murine abdominal aortic aneurysm (AAA) tissues and unveils a previously undescribed role of SRRM4 in regulating AAA development. C_LIO_LISRRM4 promotes AAA development and progression through inducing splicing of REST (RE1 silencing transcription factor) gene and upregulating STAT1 (signal transducer and activator of transcription 1) expression, which result in extracellular matrix degradation, inflammation, and VSMC phenotypic switching. C_LIO_LIOur study provides proof-of-concept evidence indicating the therapeutic value of STAT1 inhibition in AAA prevention and treatment. C_LI What Are the Clinical Implications?O_LIOur study defining a novel mechanism underlying the SRRM4/REST/STAT1 axis is crucial for developing new therapeutic strategies for AAA. C_LIO_LIBased on these findings, we have initiated a prospective study (REST4-AAA; ClinicalTrials.gov Identifier: NCT07056491) to evaluate REST4 expression levels in serum of AAA patients and explore its potential as a serum biomarker for AAA prediction C_LIO_LIOur findings indicate that fludarabine, a clinically available agent reported to selectively suppress STAT1, effectively attenuates AAA progression in mice, suggesting its potential for repurposing as a therapeutic strategy for AAA. C_LI

Background: Pulmonary arterial hypertension (PAH) manifests by pulmonary vascular remodeling, caused by hyper-proliferation and apoptosis resistance of resident PA cells, elevated right ventricular (RV) afterload, and death of RV failure. The goal of this study is to determine the role and mechanisms of action of mitotic spindle-associated microtubule regulator DLG associated protein 5 (DLGAP5) in pulmonary vascular remodeling in PAH. Methods: DLGAP5 expression was assessed in human PAH transcriptomic datasets, PAH patients' lung tissues, pulmonary artery smooth muscle cells (PASMCs), and pulmonary artery adventitial fibroblasts (PAAFs). Loss-of-function, molecular, functional, RNAseq, and network analyses were performed. Smooth muscle (SM)-specific DLGAP5 knockdown using adeno-associated virus serotype 6 (AAV6) in mice with SU5416/hypoxia-induced PH was performed. Results: DLGAP5 was overaccumulated in small muscular PAs, PASMCs, and PAAFs from PAH lungs. siRNA DLGAP5 down-regulated cyclin A2, suppressed hyper-proliferation, increased pro-apoptotic BIM, and induced apoptosis in human PAH PASMCs and PAAFs. DEP domain containing 1 (DEPDC1) was identified and validated as a downstream effector of DLGAP5 in PAH PASMCs responsible for hyper-proliferation and apoptosis resistance of human PAH PASMCs. SM-specific DLGAP5 knockdown with AAV6-enTagln-shDLGAP5 reversed DEPDC1 overaccumulation in small muscular PAs, reduced PA medial thickness, RV systolic pressure, mean PA pressure, and RV hypertrophy in mice with SuHx-induced PH. Conclusions: DLGAP5 supports proliferation and survival of human PAH PASMCs and PAAFs through up-regulation of cyclin A2, DEPDC1, and suppression of BIM, and promotes PA remodeling and PH in mice. DLGAP5 could serve as a potential molecular target to attenuate pulmonary vascular remodeling in PAH.

The extracellular matrix (ECM) of adipose tissue regulates metabolic homeostasis, yet how ECM composition drives adipose dysfunction in obesity remains only partially defined. Multi-omics profiling of visceral adipose tissue identified the multidomain ECM protein SVEP1 as a candidate regulator of adipose remodeling; SVEP1 was elevated in obese human adipose tissue and correlated with insulin resistance and systemic inflammation, and interaction analysis predicted associations with ECM proteins, integrins, and cytoskeletal regulators. On a chow diet, Svep1 heterozygous (Svep1+/-) mice gained less weight with lower fasting glucose, and their adipocytes showed enhanced lipolysis and AMPK activation. On a high-fat diet, Svep1+/- mice exhibited attenuated adiposity, improved glucose tolerance and insulin sensitivity, and fewer adipose macrophages with a shift away from a pro-inflammatory profile, alongside downregulation of inflammatory, lipid-metabolic, and ECM-remodeling pathways. Decellularized Svep1+/- matrix altered macrophage adhesion and phenotype relative to Svep1+/+ matrix, identifying SVEP1 as a matrix-borne mediator coupling adipose remodeling to immune activation and metabolic impairment. Together, these findings position the adipose ECM as an active driver of immunometabolic dysfunction and nominate SVEP1 and its receptor network as candidate targets in obesity.

Background: Metabolic perturbations associated with cardiovascular disease (CVD) risk factors prior to clinical disease manifestation may inform novel preventative measures. Here we characterize metabolome-wide associations with various cardiometabolic risk factors in an asymptomatic population to develop a mechanistic metabolic framework of preemergent metabolic shifts. Methods: Plasma was collected from a clinically healthy cross-sectional cohort (n = 361; Clinical Trials.gov ID: NCT02367287). Cohort mass spectrometry-based metabolomics (biocrates MxP(R) Quant 500 kits) were complemented with expanded lipidomic coverage for a sex/age-matched subset with LDLc difference > 60 mg/dL (n = 38). LDLc-focused partial least square regressions and discriminate analyses were performed, after false discovery rate corrections. Results: As LDLc levels increased, plasma sphingolipids and cholesteryl esters, and transulfuration products were higher, while ether-linked phosphatidylcholines serine, glycine, alanine, methionine were lower. The subset analysis further highlighted elevations in triglycerides and deoxyceramides with elevated LDLc. When adjusted for alanine concentrations, deoxyceramide concentrations increased as serine declined (p = 0.0012), and the deoxyceramide:ceramide ratios were higher in the high LDLc group (p = 0.039). Lower serine levels were also accompanied by parallel changes in glycine (p= 0.0004), and anti-parallel changes in transsulfuration pathway metabolites particularly when adjusted for ceramide levels. Notably, the alanine:serine ratio was more strongly associated with fasting triglycerides (r = 0.38; p <0.0001) than LDLc. Conclusions: Serine depletion by increased demands of sphingolipid, and possibly transsulfuration pathway, metabolism is associated with elevations in cytotoxic deoxyceramides and reductions in glycine and methionine availability for one-carbon metabolism. These changes were strongly associated with fasting triglycerides and insulin resistance, a key marker of residual CVD risk.

Background: Murine models are widely used to investigate cardiovascular disease (CVD), yet many established models rely on invasive surgery or genetic manipulation to induce hyperlipidemia and therefore may not fully capture the gradual cardiovascular consequences of mutant hematopoiesis. Tie2-Cre/-FF1/- (Tie2FF1) mice express JAK2V617F mutation in both hematopoietic and endothelial cells and develop spontaneous CVD on a standard chow diet. Methods: We applied a comprehensive, non-invasive cardiovascular phenotyping protocol to 1-year-old Tie2FF1 mice and age-matched controls. Assessments included transthoracic echocardiography, coronary flow reserve by Doppler ultrasound, quantitative analysis of coronary arteriolar structure and perivascular fibrosis, endocardial histology and subendocardial collagen deposition, and histologic evaluation of pulmonary and hepatic congestion. Results: Tie2FF1 mice demonstrated left ventricular dilation, increased cardiac mass, and mildly reduced systolic function without obstructive epicardial coronary disease. Coronary microvascular remodeling was evident by arteriolar narrowing and increased perivascular fibrosis, while coronary flow reserve was markedly reduced in an exploratory cohort. Endocardial endothelial disruption and increased subendocardial fibrosis were also observed. In addition, Tie2FF1 mice showed increased lung and liver weights, pulmonary fluid accumulation, alveolar septal thickening, pulmonary vascular fibrosis, hepatic sinusoidal dilatation, and centrilobular hepatocyte swelling, providing objective evidence of clinically relevant heart failure. Significance: These findings establish Tie2FF1 mice as a spontaneous, non-invasive model with features of coronary microvascular and endocardial endothelial dysfunction and heart failure with mildly reduced left ventricular ejection fraction. The integrated approach described here provides a practical framework for comprehensive murine cardiovascular phenotyping beyond traditional atherosclerosis- and surgery-based models.