Osteomodulin Gene Expression Is Associated With Plaque Calcification, Stability, and Fewer Cardiovascular Events in the CPIP Cohort.

BACKGROUND: Stable atherosclerotic plaques are characterized by thick fibrous caps of smooth muscle cells, collagen, and macrocalcifications. Identifying factors of plaque stability is necessary to design drugs to prevent plaque rupture and symptoms. Osteomodulin, originally identified in bones, is expressed by bone synthesizing osteoblasts and involved in mineralization. In the present study, we analyzed osteomodulin expression in human carotid plaques, its link with plaque phenotype, calcification, and future cardiovascular events. METHODS: Osteomodulin gene expression (OMD; n=82) was determined by RNA sequencing and osteomodulin protein levels by immunohistochemistry (n=45) in carotid plaques obtained by endarterectomy from patients with or without cerebrovascular symptoms from the CPIP (Carotid Plaque Imaging Project) cohort, Skåne University Hospital, Sweden. Plaque components were assessed by immunohistochemistry, RNA sequencing, and multiplex analysis. Patients were followed for cardiovascular events or cardiovascular death during a median of 57 or 70 months, respectively, using national registers. RESULTS: OMD levels were increased in plaques from asymptomatic patients compared to symptomatics. High OMD levels were associated with fewer cardiovascular events during follow-up. OMD correlated positively with smooth muscle α-actin (ACTA2; r=0.73, P=10-13) and collagen (COL1A2; r=0.4, P=0.0002), but inversely with CD68 gene expression (r=-0.67, P=10-11), lipids (r=-0.37, P=0.001), intraplaque hemorrhage (r=-0.32, P=0.010), inflammatory cytokine, and matrix metalloproteinase plaque contents. OMD was positively associated with MSX2 (Msh Homeobox 2) (r=0.32, P=0.003), a marker of preosteoblast differentiation, BMP4 (bone morphogenetic protein) (r=0.50, P=0.000002) and BMP6 (r=0.47, P=0.000007), plaque calcification (r=0.35, P=0.016), and was strongly upregulated in osteogenically stimulated smooth muscle cells, which was further increased upon BMP stimulation. Osteomodulin protein was present in calcified regions. Osteomodulin protein levels were associated with plaque calcification (r=0.41, P=0.006) and increased in macrocalcified plaques. CONCLUSIONS: These data show that osteomodulin mRNA and protein levels are associated with plaque calcification in human atherosclerosis. Furthermore, osteomodulin mRNA, but not protein levels, is associated with plaque stability.

High levels of autoantibodies against apoB100 p210 are associated with lower incidence of atrial fibrillation in women.

BACKGROUND AND OBJECTIVES: Atrial fibrillation (AF) is associated with inflammation, both systemically and in the atrial tissue. Oxidized low-density lipoprotein (LDL) is increased in patients with AF and is suggested to be one of the molecules that drives inflammation. Autoantibodies against oxidized LDL and apolipoprotein B100, the protein component of LDL, are linked to atherosclerotic disease. However, whether these autoantibodies are associated with occurrence of AF is not known. We investigated autoantibodies against oxidized apolipoprotein B100 peptides and incidence of AF in a large population-based cohort. METHODS: IgM and IgG against native and aldehyde-modified apoB100 peptides 210 (p210) and 45 were analyzed by enzyme-linked immunosorbent assay (ELISA) in 5169 individuals from the Malmö Diet and Cancer cohort. RESULTS: Seven hundred sixty-nine incident AF cases were recorded during a follow-up of 21.3 years. Individuals with high levels of IgM against native p210 at baseline had a lower risk of developing AF; however, the association did not remain after adjustment for age and sex. Women had higher levels of IgM against native p210 than men (0.70 ± 0.22 AU vs. 0.63 ± 0.21 AU, p < 0.001). The association of IgM against native p210 and AF was significantly different between sexes (p for interaction = 0.024), where females with high IgM against p210 had a lower risk for incidence of AF (hazard ratio [95% confidence interval] 4th versus 1st quartile: 0.67 [0.49-0.91]; p = 0.01) after adjusting for risk factors and comorbidities. CONCLUSION: These findings support an association of humoral autoimmunity with AF.

Low Levels of CD4+CD28null T Cells at Baseline Are Associated With First-Time Coronary Events in a Prospective Population-Based Case-Control Cohort.

OBJECTIVE: CD4+CD28null T cells have been shown to be associated with recurrent coronary events and suggested as potential biomarker and therapeutic target. It is unknown whether CD4+CD28null T cells associate with first-time cardiovascular events. We examined CD4+CD28null T cells in a prospective population-based cohort and in patients with advanced atherosclerosis. Approach and Results: CD4+CD28null T cells were quantified in 272 individuals experiencing a first-time coronary event during up to 17 years of follow-up and 272 age- and sex-matched controls in a case-control study, nested within the population-based Malmö Diet and Cancer study. The highest tertile of CD4+CD28null T cells was associated with a lower incidence of first-time coronary events compared with the lowest tertile (odds ratio, 0.48 [95% CI, 0.29-0.79], P=0.004) when adjusting for Framingham risk factors. This association remained significant for events recorded after >9 years of follow-up, when most coronary events occurred, but not during the first 9 years of follow-up, despite similar odds ratio. Additionally, we analyzed CD4+CD28null T cells in 201 patients with advanced atherosclerosis undergoing carotid endarterectomy. The adjusted hazard ratio for cardiovascular events in patients with advanced atherosclerosis was 2.11 (95% CI, 1.10-4.05, P=0.024), comparing the highest with the lowest CD4+CD28null T-cell tertile. CONCLUSIONS: Our findings reveal complex associations between CD4+CD28null T cells and cardiovascular disease. Although we confirm the reported positive associations with an adverse prognosis in patients with already established disease, the opposite associations with first-time coronary events in the population-based cohort may limit the clinical use of CD4+CD28null T cells.

Reduced oxidized LDL in T2D plaques is associated with a greater statin usage but not with future cardiovascular events.

BACKGROUND: Type 2 diabetes (T2D) patients are at a greater risk of cardiovascular events due to aggravated atherosclerosis. Oxidized LDL (oxLDL) has been shown to be increased in T2D plaques and suggested to contribute to plaque ruptures. Despite intensified statin treatment during the last decade the higher risk for events remains. Here, we explored if intensified statin treatment was associated with reduced oxLDL in T2D plaques and if oxLDL predicts cardiovascular events, to elucidate whether further plaque oxLDL reduction would be a promising therapeutic target. METHODS: Carotid plaque OxLDL levels and plasma lipoproteins were assessed in 200 patients. Plaque oxLDL was located by immunohistochemistry. Plaque cytokines, cells and scavenger receptor gene expression were quantified by Luminex, immunohistochemistry and RNA sequencing, respectively. Clinical information and events during follow-up were obtained from national registers. RESULTS: Plaque oxLDL levels correlated with markers of inflammatory activity, endothelial activation and plasma LDL cholesterol (r = 0.22-0.32 and p ≤ 0.01 for all). T2D individuals exhibited lower plaque levels of oxLDL, sLOX-1(a marker of endothelial activation) and plasma LDL cholesterol (p = 0.001, p = 0.006 and p = 0.009). No increased gene expression of scavenger receptors was identified in T2D plaques. The lower oxLDL content in T2D plaques was associated with a greater statin usage (p = 0.026). Supporting this, a linear regression model showed that statin treatment was the factor with the strongest association to plaque oxLDL and plasma LDL cholesterol (p < 0.001 for both). However, patients with T2D more frequently suffered from symptoms and yet plaque levels of oxLDL did not predict cardiovascular events in T2D (findings are summarized in Fig. 1a). CONCLUSIONS: This study points out the importance of statin treatment in affecting plaque biology in T2D. It also implies that other biological components, beyond oxLDL, need to be identified and targeted to further reduce the risk of events among T2D patients receiving statin treatment.

Interleukin-25 (IL-25) has a protective role in atherosclerosis development in the aortic arch in mice.

Atherosclerosis is a chronic inflammatory disease characterized by the entrapment of apolipoprotein B-containing lipoproteins in the arterial intima, leading to local inflammation. T helper (Th) cell 1-mediated immune responses have been associated with atherosclerosis, and the cytokine interleukin-25 (IL-25 or IL-17E) has been reported to potentially regulate Th1 cell- and Th17 cell-related immune responses. In this study, we evaluated the effects of complete IL-25 deficiency or of a temporal IL-25 blockade on atherosclerosis development in apolipoprotein E-deficient (Apoe-/-) mice. Mice deficient in both apolipoprotein E and IL-25 (Apoe-/-/IL-25-/-) had more Th1 cells in the spleen, along with elevated plasma levels of IL-17 and an increased release of splenic interferon-γ (INF-γ). In support of this observation, a 4-week-long treatment of young Apoe-/- mice (at 10-14 weeks of age) with an IL-25-blocking antibody increased the release of Th1/Th17-associated cytokines in the spleen. In both mouse models, these findings were associated with increased atherosclerotic plaque formation in the aortic arch. We conclude that complete IL-25 deficiency and a temporal IL-25 blockade during early plaque development aggravate atherosclerosis development in the aortic arch of Apoe-/- mice, accompanied by an increase in Th1/Th17-mediated immune responses. Our finding that endogenous IL-25 has an atheroprotective role in the murine aortic arch has potential implications for atherosclerosis development and management in humans.

Cartilage Oligomeric Matrix Protein Associates With a Vulnerable Plaque Phenotype in Human Atherosclerotic Plaques.

Background and Purpose- Extracellular matrix proteins are important in atherosclerotic disease by influencing plaque stability and cellular behavior but also by regulating inflammation. COMP (cartilage oligomeric matrix protein) is present in healthy human arteries and expressed by smooth muscle cells. A recent study showed that transplantation of COMP-deficient bone marrow to apoE-/- mice increased atherosclerotic plaque formation, indicating a role for COMP also in bone marrow-derived cells. Despite the evidence of a role for COMP in murine atherosclerosis, knowledge is lacking about the role of COMP in human atherosclerotic disease. Methods- In the present study, we investigated if COMP was associated with a stable or a vulnerable human atherosclerotic plaque phenotype by analyzing 211 carotid plaques for COMP expression using immunohistochemistry. Results- Plaque area that stained positive for COMP was significantly larger in atherosclerotic plaques associated with symptoms (n=110) compared with asymptomatic plaques (n=101; 9.7% [4.7-14.3] versus 5.6% [2.8-9.8]; P=0.0002). COMP was positively associated with plaque lipids (r=0.32; P=0.000002) and CD68 cells (r=0.15; P=0.036) but was negatively associated with collagen (r=-0.16; P=0.024), elastin (r=-0.14; P=0.041), and smooth muscle cells (r=-0.25; P=0.0002). COMP was positively associated with CD163 (r=0.37; P=0.00000006), a scavenger receptor for hemoglobin/haptoglobin and a marker of Mhem macrophages, and with intraplaque hemorrhage, measured as glycophorin A staining (r=0.28; P=0.00006). Conclusions- The present study shows that COMP is associated to symptomatic carotid atherosclerosis, CD163-expressing cells, and a vulnerable atherosclerotic plaque phenotype in humans.

Altered metabolism distinguishes high-risk from stable carotid atherosclerotic plaques.

Aims: Identification and treatment of the rupture prone atherosclerotic plaque remains a challenge for reducing the burden of cardiovascular disease. The interconnection of metabolic and inflammatory processes in rupture prone plaques is poorly understood. Herein, we investigate associations between metabolite profiles, inflammatory mediators and vulnerability in carotid atherosclerotic plaques. Methods and results: We collected 159 carotid plaques from patients undergoing endarterectomy and measured 165 different metabolites in a targeted metabolomics approach. We identified a metabolite profile in carotid plaques that associated with histologically evaluated vulnerability and inflammatory mediators, as well as presence of symptoms in patients. The distinct metabolite profiles identified in high-risk and stable plaques were in line with different transcription levels of metabolic enzymes in the two groups, suggesting an altered metabolism in high-risk plaques. The altered metabolic signature in high-risk plaques was consistent with a change to increased glycolysis, elevated amino acid utilization and decreased fatty acid oxidation, similar to what is found in activated leucocytes and cancer cells. Conclusion: These results highlight a possible key role of cellular metabolism to support inflammation and a high-risk phenotype of atherosclerotic plaques. Targeting the metabolism of atherosclerotic plaques with novel metabolic radiotracers or inhibitors might therefore be valid future approaches to identify and treat the high-risk atherosclerotic plaque.

FADD, Caspase-3, and Caspase-8 and Incidence of Coronary Events.

OBJECTIVE: To investigate the relationship between 3 markers of apoptosis, that is, FADD (Fas-associated death domain-containing protein), caspase-3, and caspase-8, and incidence of coronary events (CEs) in a population-based cohort study. APPROACH AND RESULTS: In vitro experiments were performed to assess the response of the apoptotic biomarkers after Fas stimulation of peripheral blood mononuclear cells. The experiments showed significantly increased releases of FADD, caspase-3, and caspase-8 after Fas stimulation. The relationship between FADD, caspase-3, and caspase-8, respectively, and incidence of CEs was studied in 4284 subjects from the population-based Malmö Diet and Cancer Study. Cox' proportional hazards regression was used to examine the association between the apoptotic biomarkers and incidence of CE over a mean follow-up of 19 years. A total of 381 individuals had CE during the follow-up. High FADD at baseline was significantly associated with incident CE. In the highest compared with the lowest quartile of FADD, the risk factor adjusted hazards ratio for CE was 1.82 (95% confidence interval, 1.35-2.46; P for trend <0.001). A significant association was also found between caspase-8 and CE; the hazards ratio (Q4 versus Q1) was 1.90 (95% confidence interval, 1.39-2.60; P for trend <0.001) after adjustment for risk factors. No association was found between caspase-3 and CEs. CONCLUSIONS: High levels of FADD and caspase-8, but not caspase-3, were associated with increased incidence of CE in subjects from the general population. The in vitro experiments support the view that these biomarkers could reflect activation of the extrinsic apoptotic pathway.

Low Levels of IgM Antibodies against an Advanced Glycation Endproduct-Modified Apolipoprotein B100 Peptide Predict Cardiovascular Events in Nondiabetic Subjects.

Increased glucose levels are associated with the generation of advanced glycation endproduct (AGE) modifications. Interaction between AGE-modified plaque components and immune cells is believed to have an important role in the development of vascular complications in diabetes. Methylglyoxal (MGO) is one type of reactive aldehyde that gives rise to AGE modification. The present study analyzed whether autoantibodies against MGO-modified epitopes of the low-density lipoprotein apolipoprotein B (apoB) 100 predict cardiovascular events. A library consisting of 302 peptides comprising the complete apoB100 molecule was screened to identify peptides targeted by MGO-specific autoantibodies. Peptide (p) 220 (apoB amino acids 3286-3305) was identified as a major target. Baseline IgM and IgG against MGO-peptide 220 (p220) were measured in 700 individuals from the Malmö Diet and Cancer Cohort. A total of 139 cardiovascular events were registered during the 15-y follow-up period. Controlling for major cardiovascular risk factors demonstrated that subjects in the lowest tertile of MGO-p220 IgM had an increased risk for cardiovascular events (hazard ratio [95% confidence interval]: 2.07 [1.22-3.50]; p(trend) = 0.004). Interestingly, the association between MGO-p220 IgM and cardiovascular events remained and even tended to become stronger when subjects with prevalent diabetes were excluded from the analysis (2.51 [1.37-4.61]; p(trend) = 0.002). MGO-p220 IgM was inversely associated with blood glucose, but not with oxidized low-density lipoprotein. Finally, we demonstrate that anti-MGO-p220 IgM is produced by B1 cells. These data show that subjects with low levels of IgM recognizing MGO-modified p220 in apoB have an increased risk to develop cardiovascular events and that this association is present in nondiabetic subjects.

The leucine-rich repeat protein PRELP binds fibroblast cell-surface proteoglycans and enhances focal adhesion formation.

PRELP (proline/arginine-rich end leucine-rich repeat protein) is a member of the leucine-rich repeat (LRR) family of extracellular matrix proteins in connective tissue. In contrast with other members of the family, the N-terminal domain of PRELP has a high content of proline and positively charged amino acids. This domain has previously been shown to bind chondrocytes and to inhibit osteoclast differentiation. In the present study, we show that PRELP mediates cell adhesion by binding to cell-surface glycosaminoglycans (GAGs). Thus, rat skin fibroblasts (RSFs) bound to full-length PRELP and to the N-terminal part of PRELP alone, but not to truncated PRELP lacking the positively charged N-terminal region. Cell attachment to PRELP was inhibited by addition of soluble heparin or heparan sulfate (HS), by blocking sulfation of the fibroblasts or by treating the cells with a combination of chondroitinase and heparinase. Using affinity chromatography, we identified syndecan-1, syndecan-4 and glypican-1 as cell-surface proteoglycans (PGs) binding to the N-terminal part of PRELP. Finally, we show that the N-terminal domain of PRELP in combination with the integrin-binding domain of fibronectin, but neither of the fragments alone, induced fibroblast focal adhesion formation. These findings provide support for a role of the N-terminal region of PRELP as an important regulator of cell adhesion and behaviour, which may be of importance in pathological conditions.

Autophagy dysfunction and regulatory cystatin C in macrophage death of atherosclerosis.

Autophagy dysfunction in mouse atherosclerosis models has been associated with increased lipid accumulation, apoptosis and inflammation. Expression of cystatin C (CysC) is decreased in human atheroma, and CysC deficiency enhances atherosclerosis in mice. Here, we first investigated the association of autophagy and CysC expression levels with atheroma plaque severity in human atherosclerotic lesions. We found that autophagy proteins Atg5 and LC3ß in advanced human carotid atherosclerotic lesions are decreased, while markers of dysfunctional autophagy p62/SQSTM1 and ubiquitin are increased together with elevated levels of lipid accumulation and apoptosis. The expressions of LC3ß and Atg5 were positively associated with CysC expression. Second, we investigated whether CysC expression is involved in autophagy in atherosclerotic apoE-deficient mice, demonstrating that CysC deficiency (CysC(-/-) ) in these mice results in reduction of Atg5 and LC3ß levels and induction of apoptosis. Third, macrophages isolated from CysC(-/-) mice displayed increased levels of p62/SQSTM1 and higher sensitivity to 7-oxysterol-mediated lysosomal membrane destabilization and apoptosis. Finally, CysC treatment minimized oxysterol-mediated cellular lipid accumulation. We conclude that autophagy dysfunction is a characteristic of advanced human atherosclerotic lesions and is associated with reduced levels of CysC. The deficiency of CysC causes autophagy dysfunction and apoptosis in macrophages and apoE-deficient mice. The results indicate that CysC plays an important regulatory role in combating cell death via the autophagic pathway in atherosclerosis.

High Plasma Levels of Galectin-3 Are Associated with Increased Risk for Stroke after Carotid Endarterectomy.

BACKGROUND: Galectin-3 (Gal-3) has been suggested to have both pro- and anti-atherogenic properties. High plasma Gal-3 levels are associated with increased risk for cardiovascular (CV) death. However, it has so far not been investigated if plasma Gal-3 levels can predict the risk for future stroke in patients suffering from carotid atherosclerosis. The aim of this study was to investigate whether Gal-3 could be used as a marker to predict postoperative cerebrovascular ischemic events among patients who underwent carotid endarterectomy (CEA). METHODS: Plasma samples were obtained from 558 CEA patients and Gal-3 levels were analyzed by the proximity extension assay technique. The Swedish national in-patient health register was used to identify postoperative cerebrovascular events during the follow-up period (42.6 ± 26.2 months). RESULTS: Plasma Gal-3 was increased in patients treated for a symptomatic carotid stenosis (p = 0.013). Patients with Gal-3 levels above the median value had an increased incidence of stroke as shown by Kaplan-Meier curves of event-free survival (p = 0.007). Gal-3 was a predictor of postoperative stroke among women (hazard ratio 15.1, 95% CI 1.3-172.2; p = 0.028) even after correction for traditional CV risk factors. CONCLUSIONS: This study is the first to show that increased plasma levels of Gal-3 can help in predicting the occurrence of postoperative strokes among female subjects who undergo CEA, independently of traditional risk factors for cerebrovascular disease. This finding suggests that Gal-3 could be used as a marker to identify patients in need of intensified postoperative medical care.

High plasma levels of heparin-binding epidermal growth factor are associated with a more stable plaque phenotype and reduced incidence of coronary events.

OBJECTIVE: Rupture of atherosclerotic plaques is the major cause of acute coronary events (CEs). Plaque destabilization is the consequence of an imbalance between inflammatory-driven degradation of fibrous tissue and smooth muscle cell-dependent tissue repair. Proinflammatory factors have been documented extensively as biomarkers of cardiovascular risk but factors that contribute to stabilization of atherosclerotic plaques have received less attention. The present study aimed to investigate whether plasma levels of the smooth muscle cell growth factor epidermal growth factor (EGF), heparin-binding-EGF (HB-EGF), and platelet-derived growth factor correlate with plaque phenotype and incidence of CEs. APPROACH AND RESULTS: HB-EGF, EGF and platelet-derived growth factor were measured in plasma from 202 patients undergoing carotid endarterectomy and in 384 incident CE cases and 409 matched controls recruited from the Malmö Diet and Cancer cohort. Significant positive associations were found between the plasma levels of all 3 growth factors and the collagen and elastin contents of the removed plaques. CE cases in the Malmö Diet and Cancer cohort had lower levels of HB-EGF in plasma, whereas no significant differences were found for EGF and platelet-derived growth factor. After adjusting for cardiovascular risk factors in a Cox proportional hazard model, the hazard ratio for the highest HB-EGF tertile was 0.61 (95% confidence interval, 0.47-0.82; P<0.001). CONCLUSIONS: The associations between high levels of smooth muscle cell growth factors in plasma and a more fibrous plaque phenotype as well as the association between low levels of HB-EGF and incident CEs point to a potential clinically important role for factors that contribute to plaque stabilization by stimulating smooth muscle cells.

Elevated Plasma Levels of MMP-12 Are Associated With Atherosclerotic Burden and Symptomatic Cardiovascular Disease in Subjects With Type 2 Diabetes.

OBJECTIVE: Matrix metalloproteinases (MMPs) degrade extracellular matrix proteins and play important roles in development and tissue repair. They have also been shown to have both protective and pathogenic effects in atherosclerosis, and experimental studies have suggested that MMP-12 contributes to plaque growth and destabilization. The objective of this study was to investigate the associations between circulating MMPs, atherosclerosis burden, and incidence of cardiovascular disease with a particular focus on type 2 diabetes mellitus. APPROACH AND RESULTS: Plasma levels of MMP-1, -3, -7, -10, and -12 were analyzed by the Proximity Extension Assay technology in 1500 subjects participating in the SUMMIT (surrogate markers for micro- and macrovascular hard end points for innovative diabetes tools) study, 384 incident coronary cases, and 409 matched controls in the Malmö Diet and Cancer study and in 205 carotid endarterectomy patients. Plasma MMP-7 and -12 were higher in subjects with type 2 diabetes mellitus, increased with age and impaired renal function, and was independently associated with prevalent cardiovascular disease, atherosclerotic burden (as assessed by carotid intima-media thickness and ankle-brachial pressure index), arterial stiffness, and plaque inflammation. Baseline MMP-7 and -12 levels were increased in Malmö Diet and Cancer subjects who had a coronary event during follow-up. CONCLUSIONS: The plasma level of MMP-7 and -12 are elevated in type 2 diabetes mellitus, associated with more severe atherosclerosis and an increased incidence of coronary events. These observations provide clinical support to previous experimental studies, demonstrating a role for these MMPs in plaque development, and suggest that they are potential biomarkers of atherosclerosis burden and cardiovascular disease risk.

Association between renin and atherosclerotic burden in subjects with and without type 2 diabetes.

BACKGROUND: Activation of the renin-angiotensin-aldosterone-system (RAAS) has been proposed to contribute to development of vascular complications in type 2 diabetes (T2D). The aim of the present study was to determine if plasma renin levels are associated with the severity of vascular changes in subjects with and without T2D. METHODS: Renin was analyzed by the Proximity Extension Assay in subjects with (n = 985) and without (n = 515) T2D participating in the SUMMIT (SUrrogate markers for Micro- and Macro-vascular hard endpoints for Innovative diabetes Tools) study and in 205 carotid endarterectomy patients. Vascular changes were assessed by determining ankle-brachial pressure index (ABPI), carotid intima-media thickness (IMT), carotid plaque area, pulse wave velocity (PWV) and the reactivity hyperemia index (RHI). RESULTS: Plasma renin was elevated in subjects with T2D and demonstrated risk factor-independent association with prevalent cardiovascular disease both in subjects with and without T2D. Renin levels increased with age, body mass index, HbA1c and correlated inversely with HDL. Subjects with T2D had more severe carotid disease, increased arterial stiffness, and impaired endothelial function. Risk factor-independent associations between renin and APBI, bulb IMT, carotid plaque area were observed in both T2D and non-T2D subjects. These associations were independent of treatment with RAAS inhibitors. Only weak associations existed between plasma renin and the expression of pro-inflammatory and fibrous components in plaques from 205 endarterectomy patients. CONCLUSIONS: Our findings provide clinical evidence for associations between systemic RAAS activation and atherosclerotic burden and suggest that this association is of particular importance in T2D.

Human Carotid Plaques With High Levels of Interleukin-16 Are Associated With Reduced Risk for Cardiovascular Events.

BACKGROUND AND PURPOSE: Interleukin-16 (IL-16) functions as a regulator of T-cell growth and acts as an inducer of cell migration. The aim of this study was to determine whether IL-16 measured in human carotid plaques was associated with symptoms (eg, stroke, transient ischemic attack, or amaurosis fugax), markers of plaque stability, and postoperative cardiovascular events. METHODS: Plaques obtained from patients who had ≥1 cerebrovascular ischemic events within 1 month before endarterectomy (n=111) were compared with plaques from patients without symptoms (n=95). Neutral lipids, smooth muscle cell, and macrophage contents were evaluated histologically, and collagen, elastin, and caspase-3 activity were measured biochemically. IL-16, matrix metalloproteinases, and tissue inhibitors of metalloproteinases were measured in plaque homogenates using a multiplex immunoassay. IL-16, CD3, CD4, and FoxP3 mRNA expressions in carotid plaques were analyzed with quantitative real-time polymerase chain reaction. RESULTS: Carotid plaques from asymptomatic patients had higher levels of IL-16 mRNA. High plaque IL-16 protein levels (above median) were associated with reduced incidence of postoperative cardiovascular events during a mean follow-up of 21 months (hazard ratio, 0.47; 95% confidence interval, 0.22-0.99; P=0.047). IL-16 levels correlated with the plaque-stabilizing components: elastin, collagen, matrix metalloproteinase-2, tissue inhibitors of metalloproteinase-1, tissue inhibitors of metalloproteinase-2 and FoxP3 mRNA. CONCLUSIONS: This study shows that high levels of IL-16 are associated with asymptomatic carotid plaques, expression of factors contributing to plaque stability, and decreased risk of new cardiovascular events during a 2-year period after surgery, suggesting that IL-16 might have a protective role in human atherosclerotic disease.

Impaired fibrous repair: a possible contributor to atherosclerotic plaque vulnerability in patients with type II diabetes.

OBJECTIVE: Diabetes mellitus (DM) type II is increasing rapidly worldwide. Patients with DM II have a greater atherosclerotic burden and higher risk of developing cardiovascular complications. Inflammation has been proposed as the main cause for the high risk of atherosclerotic disease in DM II. In this study, we compared markers of inflammation and fibrous repair in plaques from subjects with and without DM II. APPROACH AND RESULTS: Carotid endarterectomy specimens were obtained from 63 patients with and 131 without DM. Plaque structure, connective tissue proteins, inflammatory cells, and markers were analyzed by immunohistochemistry, ELISA, Mesoscale, and Luminex technology. Carotid plaques from diabetics had lower levels of extracellular matrix proteins, elastin, and collagen, which are critical for plaque stability. Plaques from diabetics had reduced levels of platelet-derived growth factor and matrix metalloproteinase-2, both important for tissue repair. No differences were observed in inflammatory markers in plaques from diabetic and nondiabetic patients. CONCLUSION: This study suggests that atherosclerotic plaques in subjects with DM II are more prone to rupture because of impaired repair responses rather than to increased vascular inflammation. Although this study did not have a mechanistic design, our findings suggest that targeting impaired repair responses in carotid plaques may help to increase our understanding of atherosclerotic plaque development and vulnerability in patients with DM II.

Interleukin-1 receptor accessory protein blockade limits the development of atherosclerosis and reduces plaque inflammation.

AIMS: The interleukin-1 receptor accessory protein (IL1RAP) is a co-receptor required for signalling through the IL-1, IL-33, and IL-36 receptors. Using a novel anti-IL1RAP-blocking antibody, we investigated the role of IL1RAP in atherosclerosis. METHODS AND RESULTS: Single-cell RNA sequencing data from human atherosclerotic plaques revealed the expression of IL1RAP and several IL1RAP-related cytokines and receptors, including IL1B and IL33. Histological analysis showed the presence of IL1RAP in both the plaque and adventitia, and flow cytometry of murine atherosclerotic aortas revealed IL1RAP expression on plaque leucocytes, including neutrophils and macrophages. High-cholesterol diet fed apolipoprotein E-deficient (Apoe-/-) mice were treated with a novel non-depleting IL1RAP-blocking antibody or isotype control for the last 6 weeks of diet. IL1RAP blockade in mice resulted in a 20% reduction in subvalvular plaque size and limited the accumulation of neutrophils and monocytes/macrophages in plaques and of T cells in adventitia, compared with control mice. Indicative of reduced plaque inflammation, the expression of several genes related to leucocyte recruitment, including Cxcl1 and Cxcl2, was reduced in brachiocephalic arteries of anti-IL1RAP-treated mice, and the expression of these chemokines in human plaques was mainly restricted to CD68+ myeloid cells. Furthermore, in vitro studies demonstrated that IL-1, IL-33, and IL-36 induced CXCL1 release from both macrophages and fibroblasts, which could be mitigated by IL1RAP blockade. CONCLUSION: Limiting IL1RAP-dependent cytokine signalling pathways in atherosclerotic mice reduces plaque burden and plaque inflammation, potentially by limiting plaque chemokine production.

Plasma levels of CCL21, but not CCL19, independently predict future coronary events in a prospective population-based cohort.

BACKGROUND AND AIMS: The homeostatic chemokines CCL21 and CCL19 have been explored as biomarkers in cardiovascular disease prediction in patients with established cardiovascular disease, but associations between these chemokines and first-time coronary event incidence have not been investigated before. Here, we explored associations between CCL21 or CCL19 and first-time incident coronary events in the general population-based Malmö Diet and Cancer cohort with two decades of follow-up. METHODS: CCL21 and CCL19 levels in plasma were analysed with ELISA and proximity extension assay and associations with disease incidence were explored with conditional logistic regression in a nested case-control cohort (CCL21; n = 676) and with Cox regression in a population-based cohort (CCL19; n = 4636). RESULTS: High CCL21 levels in plasma were associated with incident first-time coronary events independently of traditional risk factors (odds ratio of 2.64 with 95% confidence interval 1.62-4.31, p < 0.001, comparing the highest versus the lowest tertile of CCL21), whereas CCL19 was not. CCL19 was, however, associated with incident heart failure, as well as increased all-cause, cardiovascular and cancer mortality independently of age and sex. CONCLUSIONS: Even though CCL21 and CCL19 both signal through CCR7, these chemokines may not be interchangeable as disease predictors and CCL21 could be used for prediction of future coronary events in individuals without any previous coronary heart disease history.