Marie Mn Nilsson

Evidence Supporting a Key Role of Lp-PLA2-Generated Lysophosphatidylcholine in Human Atherosclerotic Plaque Inflammation

Objectives—To determine whether the level of lysophosphatidylcholine (lysoPC) generated by lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with severity of inflammation in human atherosclerotic plaques. Elevated plasma Lp-PLA2 is associated with increased cardiovascular risk. Lp-PLA2 inhibition reduces atherosclerosis. Lp-PLA2 hydrolyzes low-density lipoprotein–oxidized phospholipids generating lysoPCs. According to in vitro studies, lysoPCs are proinflammatory but the association between their generation and plaque inflammation remains unknown. Methods and Results—Inflammatory activity in carotid plaques (162 patients) was determined immunohistochemically and by analyzing cytokines in homogenates (multiplex immunoassay). LysoPCs were quantified using mass spectrometry and Lp-PLA2 and the lysoPC metabolite lysophosphatidic acid (LPA) by ELISA. There was a strong correlation among lysoPC 16:0, 18:0, 18:1, LPA, and Lp-PLA2 in plaques. LysoPC 16:0, 18:0, 18:1, LPA, and Lp-PLA2 correlated with interleukin-1&bgr;, interleukin-6, monocyte chemoattractant protein-1, macrophage inflammatory protein-1&bgr;, regulated on activation normal T-cell expressed and secreted, and tumor necrosis factor-&agr; in plaques. High lysoPC and Lp-PLA2 correlated with increased plaque macrophages and lipids and with low content of smooth muscle cells, whereas LPA only correlated with plaque macrophages. Lp-PLA2, lysoPC 16:0, 18:0, and 18:1, but not LPA were higher in symptomatic than in asymptomatic plaques. Conclusions—The associations among Lp-PLA2, lysoPCs, LPA, and proinflammatory cytokines in human plaques suggest that lysoPCs play a key role in plaque inflammation and vulnerability. Our findings support Lp-PLA2 inhibition as a possible strategy for the prevention of cardiovascular disease.

Soluble Urokinase Plasminogen Activator Receptor is Associated With Inflammation in the Vulnerable Human Atherosclerotic Plaque.

Background and Purpose— Recently, plasma soluble urokinase plasminogen activator receptor (suPAR) has gained interest as a marker of cardiovascular risk. suPAR is released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in monocytes, activated T-lymphocytes and endothelial cells, all involved in atherosclerosis. suPAR levels have been well studied in plasma, but no studies have focused on suPAR in human atherosclerotic plaques. The aim of this study was to determine whether suPAR measured in the plaque is associated with symptomatic plaques and plaque inflammation. Methods— Plasma and carotid plaques from 162 patients were analyzed. Lipids, collagen, uPAR, and macrophages were measured histologically. Cytokines and suPAR were measured in homogenized plaque extracts using multiplex immunoassay and ELISA, respectively. Plasma levels of suPAR were analysed with ELISA. CD3, CD4, as well as uPAR mRNA expression were assessed with quantitative real-time polymerase chain reaction in plaque homogenates from 123 patients. Results— Plaque and plasma suPAR levels were higher in symptomatic patients compared with asymptomatic patients. Plaque suPAR levels correlated with plaque content of lipids and macrophages and with proinflammatory chemokines and cytokines monocyte chemoattractant protein 1, tumor necrosis factor &agr;, interleukin 1&bgr;, interleukin 6, platelet-derived growth factor AB/BB, monocyte inflammatory protein 1&bgr;, regulated on activation normal T-cell expressed and secreted, and s-CD40L. uPAR mRNA and histological staining for uPAR correlated with plaque content of suPAR. Conclusion— This study shows that suPAR in human carotid plaques and plasma is associated with the presence of symptoms and that plaque suPAR is associated with the vulnerable inflammatory plaque. These findings strengthen the hypothesis of suPAR as a future marker of vulnerable atherosclerotic plaques.

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. # Significance {#article-title-31}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.

Circulating cytokines reflect the expression of pro-inflammatory cytokines in atherosclerotic plaques.

AIMS Inflammation is a key factor in the development of plaque rupture and acute cardiovascular events. Although imaging techniques can be used to identify vulnerable atherosclerotic plaques, we are lacking non-invasive methods, such as plasma markers of plaque inflammation that could help to identify presence of vulnerable plaques. The aim of the present study was to investigate whether increased plasma levels of pro-inflammatory cytokines reflects inflammatory activity within atherosclerotic plaques. METHODS AND RESULTS Cytokines were measured using Luminex immunoassay in 200 homogenized plaque extracts and plasma, obtained from 197 subjects undergoing carotid surgery. Plasma levels of macrophage inflammatory protein-1β (MIP-1β), tumor necrosis factor- α (TNF-α) and fractalkine correlated significantly, not only with plaque levels of the same cytokines but also with the abundance of several pro-inflammatory and atherogenic cytokines assessed in plaque tissue. High plasma levels (upper tertile) of MIP-1β, TNF-α and fractalkine identified the presence of a plaque with high inflammation (above median of a score based on the plaque content of MIP-1β, TNF-α, interferon-γ (IFN-γ) and fractalkine) with a sensitivity between 65 and 67% and a specificity between 78 and 83%. Furthermore, this study shows that high plasma levels of MIP-1β, TNF-α and fractalkine predict future transient ischemic attacks. CONCLUSIONS Our findings show that the plasma levels of MIP-1β, TNF-α and fractalkine reflect the levels of several pro-atherogenic cytokines in plaque tissue and might be possible plasma markers for a vulnerable atherosclerotic disease. We thereby propose that these cytokines can be used as surrogate markers for the identification of patients with high-risk plaques.

Plasma levels of high-sensitive C-reactive protein do not correlate with inflammatory activity in carotid atherosclerotic plaques.

It is well established that subjects with moderately elevated plasma levels of C‐reactive protein (CRP) have an increased risk of development of cardiovascular events. As atherosclerosis is a disease characterized by chronic arterial inflammation, it is possible that moderate increases in CRP level reflect the presence of plaque inflammation. To investigate this possibility, we compared plasma levels of hsCRP the day before carotid endarterectomy with the degree of inflammation in the excised plaque tissue.

Impaired Fibrous Repair

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. # Significance {#article-title-31}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.

Low Elastin Content of Carotid Plaques Is Associated with Increased Risk of Ipsilateral Stroke

Objectives Atherosclerotic plaques with a low content of connective tissue proteins are believed to have an increased risk of rupture and to give rise to clinical events. The aim of the present study was to investigate if the content of elastin, collagen and of the matrix metalloproteinase (MMP) −1, −3, −9 and −12 in plaques removed at surgery can be associated with the occurrence of ipsilateral symptoms. Methods The atherosclerotic plaques of 221 patients undergoing carotid endarterectomy were analyzed and their composition was related to the incidence of preoperative, intraoperative and postoperative neurological events. Results Elastin, collagen and MMP-12 contents were lower in males and diabetic patients. Elastin (P .010), MMP-3 (P .008) and MMP-9 (P < .0001) were lower, while MMP-1 (P .004) and MMP-9 (P .002) were higher in plaques of patients with preoperative symptoms, even after correction for the time between the occurrence of symptoms and surgery. Elastin and MMP-12 decreased (r = −0.17, P .009 and r = −.288, P <.0001 respectively) while MMP-1 (r = 0.17, P .012) and MMP-9 (r = .21 P <.0001) increased with age. After a mean follow-up time of 39.6 ± 16.6 months, 7.7% of patients had suffered one or multiple ipsilateral neurological events. Patients with plaque elastin levels lower than the median (52 mg/g) had increased post-operative incidence of ipsilateral stroke (P for trend 0.009 using Log Rank Chi-square test). This finding was confirmed when controlling for age, gender, hypertension, diabetes, smoking, pre-operative symptoms and statin usage in a Cox Proportional Hazard model (hazard ratio 7.38, 95% C.I. 1.50–36.31). Conclusions These observations support the concept that elastin may be important for plaque stability, and suggest that a low plaque content of elastin is associated with a higher risk for ipsilateral stroke.

Impaired Fibrous RepairSignificance

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. # Significance {#article-title-31}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.