Lutgens, Esther

Introduction: Co-stimulatory proteins are master regulators of the immune system. We identified the co-stimulatory CD40-CD40L dyad as a key driver of inflammation during atherosclerosis and have shown that CD40 and CD40L exert cell-type divergent functions. Hypothesis: CD40 is abundantly expressed on endothelial cells (EC) undergoing endothelial mesenchymal transition (EndMT). We hypothesize that EC CD40 drives atherosclerosis via EndMT. Methods: We analyzed scRNAseq data from human carotid plaques, performed multiplex IHC, and used human aortic endothelial cells (HAECs) for in vitro studies. A tamoxifen-inducible EC specific CD40 deficient atherosclerotic mouse model (cadherin5 (cdh5)ERT2-CD40 flfl -ApoE -/- ) was generated. Results: Besides its presence on immune cells, CD40 is expressed on endothelial cells in both human and mouse atherosclerotic plaques. Analysis of scRNAseq data of human carotid atherosclerotic plaques showed that CD40 is highly expressed in COL1A2/FN1 expressing endothelial cells (ECs), a subset undergoing EndMT. Multiplex staining revealed that CD40 colocalized with the EndMT markers αSMA, NOTCH3, TWIST and VCAM1 in human plaques. In vitro , stimulation of human arterial endothelial cells (HAECs) with CD40L resulted in an increase in the EndMT markers markers fibronectin, vimentin, sm22α, FSP1 and snail. Using phosphoproteomics, CD40L was found to decrease phosphorylation of the junctional integrity proteins CTNNA1 [S652; S655] and ARHGAP21 [S1383]. To investigate the endothelial-specific effects of CD40 in atherosclerosis, 8-week-old cdh5ERT2-CD40 flfl -ApoE -/- mice and their CD40 flfl -ApoE -/- littermate controls were treated with tamoxifen and fed a high cholesterol diet for 10 wks. Deletion of EC-CD40 resulted in a significant reduction in plaque size. This reduction was accompanied by a shift from fibrous cap atheromas (FCA) towards intimal xanthoma (IX) and pathological intimal thickening (PIT). Flow cytometry analysis of the spleen showed that CD40 deletion in ECs results in a significant decrease in CD8 and CD4 effector T cells. This decrease in CD8 and CD4 effector T cells was accompanied by a diminished activation status, shown by a decrease in CD69 + CD8 + CD62 - CD44 + T cells, CD40L + CD8 + CD62 - CD44 + T cells and CD40L + CD4 + CD62 - CD44 + T cells. These findings demonstrate that endothelial CD40 drives atherosclerosis by inducing EndMT-driven plaque inflammation.

Introduction: V-domain Immunoglobulin Suppressor of T-cell Activation (VISTA), a co-inhibitory immune checkpoint protein, is known for regulating adaptive immune responses. Here, we investigated the role of VISTA in atherosclerosis. Hypothesis: VISTA is constitutively expressed on hematopoietic cells, particularly T cells. VISTA functions as both a ligand and receptor to maintain T cell quiescence. We hypothesize that VISTA expression is protective against plaque formation by inhibiting CD4 + T cell activation. Methods: Cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) was performed on aortic CD45 + cells of HCD fed ApoE-/- mice. Spatial transcriptomics (VISIUM) was performed on carotid plaques from patients with either asymptomatic or symptomatic cerebrovascular disease. Plaque burden, characterization, and flow cytometry of blood and lymphoid organs were performed on VISTA -/- ApoE -/- (VISTA KO) and VISTA +/+ ApoE -/- (WT) mice that were fed a HCD for 10 weeks. ApoE -/- mice treated with VISTA agonist 8G8 or IgG control (200ug, intra-peritoneal, 3 times per week for the last 6/10 weeks of HCD feeding). In vitro proliferation, migration, and functional T cell assays were performed. Results: We found that VISTA is expressed on plaque T cell populations, particularly regulatory T cells, gamma-delta T cells, and naïve T cells. In humans, individuals with symptomatic CVD have significantly reduced VISTA gene expression in carotid plaques. VISTA KO mice have increased total plaque area and necrotic core area compared to littermate WT controls. VISTA KO mice have increased peripheral CD4 + and CD8 + effector memory T (T EM ) cells with a corresponding decrease in CD4 + and CD8 + naïve T (T N ) cells and CD4 + regulatory T (T reg ) cells. Further, VISTA KO mice have a higher frequency of CD4 + T H 1 (T-bet + IFNy + ) cells and lower frequencies of IL-10 + CD4 + T cells and CD4 + T H 2 (GATA-3 + IL-13 + ) cells. In vitro assays showed that VISTA suppresses CD4 + T cell proliferation, IFNγ production, and migration. Finally, VISTA agonist treatment significantly decreased plaque and necrotic core areas in atherosclerotic mice. Conclusion: Our data reveals a novel role for VISTA in reducing plaque development and in suppressing T cell activation, proliferation, and migration. Further characterization of T-cell specific VISTA-deficient mouse models and mechanistic insights into how VISTA modulates T cells are currently being investigated.

Vascular calcification is a strong predictor of cardiovascular mortality and lacks effective treatment. The transformation of vascular smooth muscle cells (VSMCs) into osteoblast-like phenotypes is a key driver of calcification. This study identifies a regulatory role for Hyaluronan (HA) in VSMC osteogenic differentiation and arterial calcification. Human aortic VSMCs stimulated with high phosphate and/or pro-inflammatory cytokines (IL6 and TGF-β1) exhibited increased RUNX2, alkaline phosphatase and osteopontin expression, along with reduced contractility and elevated calcium deposition. This corresponded with reduced HA deposition and downregulation of HA synthase enzymes (HAS1, HAS2), Hyaluronidase enzymes (Hyal1), and HA binding proteins (CD44, TSG-6), whilst HAS3 and versican were upregulated. Comparable alterations in HA and protein expression were observed in an in vivo model of arterial calcification using vitamin K-deficient warfarin-fed mice. Pharmacological inhibition of HA synthesis, enzyme-mediated HA degradation and siRNA/plasmid modulation of HAS isoenzymes demonstrated a possible functional link between HA regulation and VSMC osteogenic differentiation. This study establishes HA and its associated binding proteins as key regulators of arterial calcification, highlighting a novel pathway for potential therapeutic intervention.

The creation of an arteriovenous fistula in a uremic pig induces cardiac remodeling, which resembles contemporary clinical findings in patients with end-stage kidney disease (ESKD) and includes increased end-diastolic volumes and cardiomyocyte hypertrophy, potentially driven by fibrosis and senescence. This novel large animal model may now enable mechanistic and therapeutic studies aiming to ease the unacceptably high burden of cardiovascular disease on patients with ESKD.

Abstract Background T cell activation and polarization drive atherosclerosis. Among the mediators underlying T cell polarization, the epigenetic enzyme EZH2 catalyses the repressive mark H3K27me3. In humans, EZH2 is upregulated in T cells in advanced atherosclerosis, whereas its deficiency in T cells in mice limits plaque formation via an anti-inflammatory response. Emerging evidence indicates that EZH2 can also regulate lncRNAs and miRNAs by depositing H3K27me3 at their loci, repressing transcription. Purpose We hypothesize that EZH2 governs lncRNAs and miRNAs expression in T cells in the context of atherogenesis. Methods CD4+ T cells were isolated from spleens of atherosclerosis-prone T cell-specific Ezh2 (Ezh2cd4)-KO mice and WT littermates. Small RNA-seq (SMARTer® smRNA-Seq) and transcriptomic profiling (Prime-seq) were performed. Differential expression was assessed using edgeR. Selected miRNAs were validated by RT-qPCR. Putative miRNA targets were retrieved from miRTarBase (v. 8) and TargetScan, and gene ontology enrichment was performed using Metascape. Results In CD4+ T cells from Ezh2cd4-KO mice, 41 out of 2,950 mature miRNAs were differentially expressed (log2FC > |0.8|, FDR < 0.05), with 27 upregulated and 14 downregulated. Top upregulated miRNAs included miR-125a-5p, miR-130a-3p, miR-744-5p, miR-181a-5p, miR-181b-5p, miR-374b-5p, miR-99b, miR-3085, and miR-7049-3p. RT-qPCR confirmed that expression of miR-125a-5p, miR-181a-5p, miR-181b-5p, and miR-99b-5p were upregulated in Ezh2-deficient murine CD4+ T cells. GO enrichment analysis of downregulated genes revealed enrichment of IL-4, IL-9, IL-10, and TGF-β pathways, suggesting their relevance in T-cell function and differentiation. In human Jurkat T cells, pharmacological EZH2 inhibition using GSK126 or tazemetostat resulted only in the upregulation of miR-125a-5p and miR-99b-5p, confirming the conservation of the mechanisms in humans. Integration of our Prime-seq transcriptomics and smallRNAseq datasets with human and mouse predicted and experimentally validated targets of miR-125a-5p and miR-99b-5p identified six conserved target genes: STAT1, FAM169B, NDRG3, PSMB9, TRIB1, and RAB3IP. Conclusions Our findings indicate that Ezh2 represses miRNA expression in T cells during atherogenesis, thereby possibly promoting differentiation toward pro-atherogenic subsets while restraining anti-atherogenic transcriptional programs. Further research is needed to elucidate the underlying mechanisms. Ezh2-regulated miRNAs may represent promising targets to direct T cell plasticity to combat atherosclerosis.

Abstract Metabolic disorders such as obesity, type 2 diabetes, and dyslipidaemia are major drivers of cardiovascular risk and have reached epidemic levels in Western populations. Recent advances in clinical research have uncovered unexpected and often beneficial effects of pharmacological classes of metabolic drugs on cardiovascular outcomes, revealing complex interactions between metabolism and cardiac pathology. Despite their clinical efficacy, the molecular and cellular mechanisms through which many of these agents act remain only partially understood. This gap in knowledge underscores the urgent need for fundamental research that not only dissects the biology of metabolic disorders and cardiovascular disease but also reveals the mechanistic basis of existing and emerging therapies, thereby enabling rational therapeutic development. This scientific statement, developed by researchers from the European Society of Cardiology (ESC) Council on Basic Cardiovascular Science and several ESC Working Groups, provides a state-of-the-art overview of the emerging molecular and cellular pathways linking metabolic abnormalities with vascular and cardiac disease. By illuminating these critical connections and unresolved questions, this article aims to catalyse innovation in the prevention and management of cardiovascular disease in the context of metabolic dysfunction and to suggest new directions for future research.

Abstract Background People living with HIV (PLHIV) are at increased risk of atherosclerotic cardiovascular disease (ASCVD), but the immunological mechanisms driving plaque formation remain unclear. This study investigated the association between peripheral immune cell subsets and carotid atherosclerotic plaques in PLHIV without prior clinical ASCVD. Methods In this multi-center cross-sectional study, virally suppressed PLHIV receiving antiretroviral therapy were enrolled from two Dutch cohorts: a discovery cohort (n = 994) and a validation cohort (n = 200). Participants underwent carotid ultrasound imaging to assess plaques using standardized criteria. Immune profiling was performed using high-dimensional flow cytometry of 355 immune cell populations. Associations with plaque were analyzed using linear regression adjusted for relevant confounders, and key findings were validated in the second cohort. Transcriptomic profiles of main cell populations were evaluated using deconvoluted bulk RNA sequencing to identify differential expression and pathway enrichment. Results Carotid plaques were present in 584 participants (49%)—502 of 994 (51%) in the discovery and 82 of 200 (41%) in the validation cohort. Plaques were associated with higher counts of several CD8+ T cell subsets, particularly PD-1-expressing cytotoxic T cells with an interferon secretion profile (CD8TC1PD1+). Transcriptomic analysis of CD8+ T cells revealed downregulated mitochondrial function and upregulated type 1 interferon and epidermal growth factor receptor signaling, indicating a senescent phenotype. Conclusions CD8+ T cell senescence may contribute to early atherosclerotic plaque formation in PLHIV. Targeting immune senescence could offer a novel strategy for cardiovascular risk reduction in this population. Clinical Trials Registration ClinicalTrials.gov Identifier: NCT03994835

Background: The arteriovenous fistula (AVF) is a requirement for hemodialysis therapy in end-stage kidney disease (ESKD) patients. A consequence of AVF creation is compensatory cardiovascular hemodynamics, which are subsequently associated with cardiac remodeling. Relatedly, cardiovascular mortality and morbidity are elevated in ESKD patients, which worsens in dialysis patients. Currently, no suitable uremic large animal models exist to investigate the underlying mechanisms of AVF-induced cardiac remodeling. Research Question: This study aims to characterize cardiovascular changes secondary to AVF creation, supported by percutaneous transluminal angioplasty (PTA), in a uremic pig model. Methods: Chronic kidney disease (CKD) was induced via renal embolization, followed by AVF creation 28 days later. The AVF was created by anastomosis of the left common carotid artery to the left external jugular vein. AVF stenosis was alleviated 28 days thereafter via PTA, and cardiac MRI was performed at 14-, 28-, and 42-days post-PTA. Results: Increased end-diastolic volumes were observed in the left and right ventricles at day 42 vs 14 (200.8ml to 249.5ml, p=0.0457, and 204.6ml to 260.0ml, p=0.0268 respectively), while systolic function was preserved. Left ventricle (LV) stroke volume and blood flow through the aorta, pulmonary artery, and vena cava were also increased. In perivascular areas of the free wall of the LV at day 42 vs control, senescence markers showed increased p16 expression (fold change 10.21, p=0.0086) and decreased p21 expression (fold change 0.07, p=0.0357). The LV showed perivascular fibrosis (0.2% to 0.59%, p=0.021), via picrosirius red, reduced collagen-type IV expression (fold change 0.81, p=0.0089), and increased MMP2 levels (fold change 14.33, p=0.0213). Cardiomyocyte cross-sectional area was increased (from 800.9 µm 2 to 1250.0 µm 2 , p=0.0296), without CD4+ or CD68+ cell LV infiltration. Conclusion: In conclusion, AVF creation leads to modified left and right ventricular function and increased peripheral flow, potentially mediated by cellular senescence and fibrosis, resulting in progressive cardiac remodeling. This model of uremic kidney disease can now be used to evaluate mechanisms of AVF induced cardiac disease and test the efficacy of therapeutics like senolytics and anti-fibrotic agents.

Worldwide, more than 4 million patients with end-stage kidney disease require hemodialysis through an arteriovenous fistula (AVF). AVFs fail because of venous neointimal hyperplasia (VNH) resulting in venous stenosis formation. A phase 1 randomized trial in patients undergoing upper extremity AVF placement was performed to evaluate the safety and efficacy of autologous adipose–derived mesenchymal stem cells (MSCs) in improving AVF function. The mechanism of action by which MSCs exert their beneficial effects was investigated using AVFs created in mice and pigs treated with allogenic MSCs and xenotransplant using patient MSCs in CD1- Foxn1nu mice. At a median follow-up of 42 months, patients with MSC-treated AVFs had reduced time to maturation with an increase in the vein diameter compared with controls. AVFs treated with allogenic MSCs in mice and pigs had an increase in M2- and M1-like macrophages with a decrease in VNH. Transcriptomic analysis of AVFs treated with allogenic MSCs in mouse and MSC xenotransplants of patients with successful AVFs showed decreased peroxisome proliferator–activated receptor gamma ( Ppar γ) and leptin receptor ( Lepr ) and increased latent transforming growth factor–beta–binding protein 2 ( Ltbp2 ). PPARγ was reduced in CD68 (+) cells from successful AVFs and allogenic MSC-treated mouse AVFs. Venous stenosis and VNH formation were mitigated in AVFs of mice with Ppar γ ablation in immune cells. Conditioned medium from MSCs of responders versus nonresponders had decreased proinflammatory genes, senescence-associated proteins, and monocyte-to-macrophage differentiation induced by phorbol 12-myristate-13-acetate. Periadventitial delivery of MSCs to AVFs promoted positive vascular remodeling through decreased inflammatory responses.