Ficolin-2 serum levels predict the occurrence of acute coronary syndrome in patients with severe carotid artery stenosis

BACKGROUND AND PURPOSE

erosion of vulnerable atherosclerotic plaques may cause life-threatening thromboembolic complications. There is indeed an urgent need to recognize a clear-cut biomarker able to identify vulnerable plaques. Here, we focused on circulating proteins belonging to the lectin pathway (LP) of complement activation.

METHODS

we analyzed mannose-binding lectin (MBL), ficolin-1, -2 and -3 (LP initiators) levels by ELISA in sera from n = 240 of an already published cohort of patients undergoing endarterectomy for severe carotid stenosis and followed-up until 18 months after surgery. Immunofluorescence followed by confocal and polarized light microscopy was used to detect LP initiator intraplaque localization. Spearman's rank test was drawn to investigate correlation between serum LP levels and circulating inflammatory proteins or intraplaque components. Survival analyses were then performed to test the predictive role of LP on long-term adverse outcome.

RESULTS

ficolins, but not MBL, correlated positively with 1) high circulating levels of inflammatory markers, including MPO, MMP-8, MMP-9, ICAM-1, osteopontin, neutrophil elastase, and; 2) immune cell intraplaque recruitment. Immunofluorescence showed ficolins in calcified plaques and ficolin-2 in cholesterol-enriched plaque regions in association with macrophages. In the multivariate survival analysis, ficolin-2 serum levels predicted a major adverse cardiovascular event during the follow-up, independently of symptomatic status and inflammatory markers (hazard ratio 38.6 [95 % CI 3.9-385.2]).

CONCLUSIONS

ficolins support intraplaque immune cell recruitment and inflammatory processes ultimately leading to plaque vulnerability. Especially for ficolin-2 a strong predictive value toward adverse cardiovascular events was demonstrated. This evidence offers potentially new pharmacological target to dampen the inflammatory mechanisms leading to plaque vulnerability.

COMP (Cartilage Oligomeric Matrix Protein) Neoepitope: A Novel Biomarker to Identify Symptomatic Carotid Stenosis

OBJECTIVE

COMP (cartilage oligomeric matrix protein) is abundantly expressed in the cardiovascular system, cartilage, and atherosclerotic plaques. We investigated if the total COMP (COMPtotal) and COMP neoepitope (COMPneo) with other cardiovascular markers and clinical parameters could identify symptomatic carotid stenosis. Approach and Results: Blood samples were collected from patients with symptomatic carotid stenosis (stenosis, n=50), patients with stroke without carotid stenosis but small plaques (plaque, n=50), and control subjects (n=50). COMPtotal and COMPneo were measured using an ELISA. Ninety-two cardiovascular disease markers were measured by the Olink CVD kit. The presence of native COMP and COMPneo was determined by immunohistochemistry. The concentration of COMPneo was higher and COMPtotal was lower in the stenosis group. When the concentration was compared between the stenosis and control groups, IL-1ra (interleukin-1 receptor antagonist protein), IL6 (interleukin-6), REN (Renin), MMP1 (matrix metalloproteinase-1), TRAIL-R2 (tumor necrosis factor-related apoptosis-inducing ligand receptor 2), ITGB1BP2 (integrin beta 1 binding protein 2), and COMPneo were predictive of stenosis. Conversely, KLK6 (kallikrein-6), COMPtotal, NEMO (nuclear factor-kappa-B essential modulator), SRC (Proto-oncogene tyrosine-protein kinase Src), SIRT2 (SIR2-like protein), CD40 (cluster of differentiation 40), TF (tissue factor), MP (myoglobin), and RAGE (receptor for advanced glycation end-products) were predictive of the control group. Model reproducibility was good with the receiver operating characteristic plot area under the curve being 0.86. When comparing the plaque group and stenosis group, COMPneo, GAL (galanin), and PTX3 (pentraxin-related protein PTX3) were predictive of stenosis. Model reproducibility was excellent (receiver operating characteristic plot area under the curve 0.92). COMPneo was detected in smooth muscle-, endothelial-, and foam-cells in carotid stenosis.

CONCLUSIONS

Degradation of COMP may be associated with atherosclerosis progression and generation of a specific COMP fragment-COMPneo. This may represent a novel biomarker that together with COMPtotal and other risk-markers could be used to identify symptomatic carotid stenosis. Graphic Abstract: A graphic abstract is available for this article.

Focal Cerebral Arteriopathy in Young Adult Patients With Stroke

Background and Purpose- Focal cerebral arteriopathy is monophasic inflammatory stenosis of the distal internal carotid artery or the proximal segment of the middle cerebral artery. It is one of the most common causes of acute arterial ischemic stroke in young children but is a less familiar entity for adult neurologists. Methods- We retrospectively reviewed stroke service radiology records at a tertiary referral center from January 2013 to December 2014. Focal cerebral arteriopathy was defined as nonprogressive unifocal and unilateral stenosis/irregularity of the distal internal carotid artery or its proximal branches. Only patients aged 16 to 55 years with stroke were included. Results- There were 5 cases of focal cerebral arteriopathy: 2 males and 3 females. Three cases were from the cohort of 123 acute presentations of young stroke, and 2 cases were outpatient referrals. The mean age (range) was 43 (32-55) years. The majority presented with recurrent transient ischemic attacks/minor strokes within a single vascular territory over days to weeks. All cases had characteristic radiological features. Interval imaging demonstrated resolution in 1 case and improvement in 3 cases. Functional outcome was excellent with discharge modified Rankin Scale score ranging from 0 to 1. Recurrence occurred in 1 case. Conclusions- Focal cerebral arteriopathy is a rare cause of arterial ischemic stroke in young adults. Follow-up intracranial imaging is essential to differentiate from progressive arteriopathies. Evidence-based treatment warrants further investigation. Prognosis is favorable.

Increased Number of Mast Cells in Atherosclerotic Lesions Correlates with the Presence of Myeloid but not Plasmacytoid Dendritic Cells as well as Pro-inflammatory T Cells

BACKGROUND

Atherosclerosis is an inflammatory disease of the vessel wall promoted by different immune cells and inflammatory mediators.

METHODS

In this study, 26 human plaques and 12 control vessels without atherosclerosis were immunohistochemically stained to analyze the emergence of mast cells dependent on plaque morphology and to correlate mast cell occurrence with the emergence of myeloid as well as plasmacytoid dendritic cells. Also, mast cell emergence was correlated with the number of pro-inflammatory T cells. For this, plaques were classified as stable or unstable according to established histological criteria.

RESULTS

As expected, atherosclerotic lesions showed significantly higher numbers of tryptase+, chymase+, and cathepsin G+ mast cells compared to control vessels, particularly in lesions with unstable morphology. As a novel finding, we detected significant correlations between mast cells and myeloid dendritic cells (fascin, CD83, r > 0.3, p < 0.01), but not plasmacytoid dendritic cells (CD123, CD304). Also, we observed significant correlations of mast cells and different subgroups of pro-inflammatory T cells (CD3, CD8, CD161, CD25; r > 0.35, p < 0.05).

CONCLUSIONS

Overall, the higher number of mast cells in plaques, particularly with unstable morphology, suggests that mast cells might be involved in the progression of atherosclerosis. The correlation of mast cells with other immune cells that are pivotal in atherogenesis, e.g., myeloid dendritic cells and pro-inflammatory T cells, also suggests an interplay leading to plaque destabilization. Therefore, modulating local mast cell function and invasion into the plaque might be a therapeutic tool for plaque stabilization.

Inhibition of p110δ PI3K prevents inflammatory response and restenosis after artery injury

Inflammatory cells play key roles in restenosis upon vascular surgical procedures such as bypass grafts, angioplasty and stent deployment but the molecular mechanisms by which these cells affect restenosis remain unclear. The p110δ isoform of phosphoinositide 3-kinase (PI3K) is mainly expressed in white blood cells. Here, we have investigated whether p110δ PI3K is involved in the pathogenesis of restenosis in a mouse model of carotid injury, which mimics the damage following arterial grafts. We used mice in which p110δ kinase activity has been disabled by a knockin (KI) point mutation in its ATP-binding site (p110δD910A/D910A PI3K mice). Wild-type (WT) and p110δD910A/D910A mice were subjected to longitudinal carotid injury. At 14 and 30 days after carotid injury, mice with inactive p110δ showed strongly decreased infiltration of inflammatory cells (including T lymphocytes and macrophages) and vascular smooth muscle cells (VSMCs), compared with WT mice. Likewise, PI-3065, a p110δ-selective PI3K inhibitor, almost completely prevented restenosis after artery injury. Our data showed that p110δ PI3K plays a main role in promoting neointimal thickening and inflammatory processes during vascular stenosis, with its inhibition providing significant reduction in restenosis following carotid injury. p110δ-selective inhibitors, recently approved for the treatment of human B-cell malignancies, therefore, present a new therapeutic opportunity to prevent the restenosis upon artery injury.

Cholesterol Crystals Activate the Lectin Complement Pathway via Ficolin-2 and Mannose-Binding Lectin: Implications for the Progression of Atherosclerosis

Cholesterol crystals (CC) play an essential role in the formation of atherosclerotic plaques. CC activate the classical and the alternative complement pathways, but the role of the lectin pathway is unknown. We hypothesized that the pattern recognition molecules (PRMs) from the lectin pathway bind CC and function as an upstream innate inflammatory signal in the pathophysiology of atherosclerosis. We investigated the binding of the PRMs mannose-binding lectin (MBL), ficolin-1, ficolin-2, and ficolin-3, the associated serine proteases, and complement activation products to CC in vitro using recombinant proteins, specific inhibitors, as well as deficient and normal sera. Additionally, we examined the deposition of ficolin-2 and MBL in human carotid plaques by immunohistochemistry and fluorescence microscopy. The results showed that the lectin pathway was activated on CC by binding of ficolin-2 and MBL in vitro, resulting in activation and deposition of complement activation products. MBL bound to CC in a calcium-dependent manner whereas ficolin-2 binding was calcium-independent. No binding was observed for ficolin-1 or ficolin-3. MBL and ficolin-2 were present in human carotid plaques, and binding of MBL to CC was confirmed in vivo by immunohistochemistry, showing localization of MBL around CC clefts. Moreover, we demonstrated that IgM, but not IgG, bound to CC in vitro and that C1q binding was facilitated by IgM. In conclusion, our study demonstrates that PRMs from the lectin pathway recognize CC and provides evidence for an important role for this pathway in the inflammatory response induced by CC in the pathophysiology of atherosclerosis.

Leucocyte count indicates carotid plaque instability in stroke patients

BACKGROUND/AIM

Increasing evidence points to the inflammatory character of atherosclerosis and several parameters of inflammation have been proposed as cerebrovascular risk markers. The objective of the research was to examine the connection of serum inflammatory parameters and ultrasound (US) characteristics of the structure and size of carotid plaque. We assumed that the number of leukocytes (Le) was an indicator of carotid plaque instability and an increased risk of stroke.

METHODS

Serum inflammatory parameters: erythrocyte sedimentation rate in the first (ESR I) and second hour (ESR II), the number of Le, high sensitivity C-reactive protein (hsCRP) and fibrinogen were measured by standard methods. All the subjects (n = 75) were divided into 3 groups (symptomatic, asymptomatic and control). US evaluation of extracranial carotid arteries was performed in a duplex system. Plaques were classified into categories according to stenosis percentage (≥ 50%, < 50%) and pursuant to echomorphological characteristics (Gray-Weale classification). In the subjects with stroke an ischemic lesion was confirmed by computed tomography.

RESULTS

The average values of biochemical parameters in the symptomatic group were: ESR I 29.57 ± 29.87 cm, ESR II 51.60 ± 36.87 cm, the number of Le 10.10 ± 3.20 x 10⁹ U/L, hsCRP 8.15 ± 5.50 mg/L and fibrinogen 4.03 ± 0.70 g/L. The average values of all testing biochemical parameters in symptomatic patients were significantly higher than in the asymptomatic ones and the control group: for ESR I (p < 0.05) and ESR II (p < 0.05); for the number of Le (p < 0.001); for hsCRP (p < 0.001) and fibrinogen (p < 0.001). Category I of echomorphological characteristics in the symptomatic group was present in 66.7% of the cases and it was significantly higher than in the asymptomatic (40.0%; p < 0.05) and the control group (20.0%; p < 0.01). Univariate logistic regression analysis confirmed that all testing biochemical parameters are indicators of stroke risk. Multivariate logistic regression analysis confirmed a statistically significant correlation of the number of Le and stroke risk, while the increase in the value by a unit of measurement was associated with the growth of risk by 3.22 times (from 1.67 to 6.22).

CONCLUSION

The number of Le is associated with the phenomenon of carotid plaque instability and may be a useful additional marker of increased risk for developing acute cerebral infarction.

Dendritic Cells Expressing Triggering Receptor Expressed on Myeloid Cells-1 Correlate with Plaque Stability in Symptomatic and Asymptomatic Patients with Carotid Stenosis

Atherosclerosis is a chronic inflammatory disease with atherosclerotic plaques containing inflammatory cells, including T-lymphocytes, dendritic cells (DCs) and macrophages that are responsible for progression and destabilization of atherosclerotic plaques. Stressed cells undergoing necrosis release molecules that act as endogenous danger signals to alert and activate innate immune cells. In atherosclerotic tissue the number of DCs increases with the progression of the lesion and produce several inflammatory cytokines and growth factors. Triggering receptor expressed on myeloid cells (TREM)-1 plays a crucial role in inflammation. However, relationship of DCs and the role of TREM-1 with the stability of atherosclerotic plaques have not been examined. In this study, we investigated the heterogeneity of the plaque DCs, myeloid (mDC1 and mDC2) and plasmacytoid (pDCs), and examined the expression of TREM-1 and their co-localization with DCs in the plaques from symptomatic (S) and asymptomatic (AS) patients with carotid stenosis. We found increased expression of HLA-DR, fascin, and TREM-1 and decreased expression of TREM-2 and α-smooth muscle actin in S compared to AS atherosclerotic carotid plaques. Both TREM-1 and fascin were co-localized suggesting increased expression of TREM-1 in plaque DCs of S compared to AS patients. These data were supported by increased mRNA transcripts of TREM-1 and decreased mRNA transcripts of TREM-2 in carotid plaques of S compared to AS patients. There was higher density of both CD1c+ mDC₁ and CD141+ mDC₂ in the carotid plaques from AS compared to S patients, where as the density of CD303+ pDCs were higher in the carotid plaques of S compared to AS patients. These findings suggest a potential role of pDCs and TREM-1 in atherosclerotic plaque vulnerability. Thus, newer therapies could be developed to selectively block TREM-1 for stabilizing atherosclerotic plaques.

Circulating autoantibodies against the apolipoprotein B-100 peptides p45 and p210 in relation to the occurrence of carotid plaques in 64-year-old women

Objectives

Immune responses against oxidized low density lipoprotein (LDL) play a key role in atherosclerosis. Previous studies have indicated inverse associations between autoantibodies to epitopes in oxidized LDL and cardiovascular disease. In this study we investigated the associations between autoantibodies against the apolipoprotein B-100 (apoB-100) peptides p45 and p210 and occurrence of carotid plaques.

Design

The study cohort consisted of a population-based sample of 64-year-old women with varying degrees of glucose tolerance (n=594). To identify and record the occurrence of carotid atherosclerotic plaques ultrasonography was used. Measurements of plasma IgM and IgG autoantibodies against the native and malondialdehyde (MDA)-modified apoB-100 peptides p45 and p210 were performed by ELISA.

Results

Women with carotid plaques were found to have lower levels of IgM MDA-p210 autoantibodies compared to plaque-free women. The number of carotid plaques in each subject and the total carotid plaque area correlated inversely with IgM MDA-p210 levels (r=-0.11, P=0.009 and r=-0.11, P=0.013, respectively). Furthermore, levels of IgM MDA-p210 above the lowest tertile were associated with an odds ratio of 0.55 (95% CI 0.38-0.79, P=0.001) for occurrence of carotid plaques, independently of other risk markers and statin treatment. Associations between apo-B100 peptide autoantibodies and cardiovascular risk factors were generally weak but subjects with impaired glucose tolerance had higher levels of IgM against MDA-p210.

Conclusion

The present study demonstrates that high levels of IgM against MDA-p210 are associated with less severe carotid disease in women. These findings provide additional support for a role of immune responses against oxidized LDL in cardiovascular disease.

Circulating immunoglobulins are not associated with intraplaque mast cell number and other vulnerable plaque characteristics in patients with carotid artery stenosis

Background

Recently, we have shown that intraplaque mast cell numbers are associated with atherosclerotic plaque vulnerability and with future cardiovascular events, which renders inhibition of mast cell activation of interest for future therapeutic interventions. However, the endogenous triggers that activate mast cells during the progression and destabilization of atherosclerotic lesions remain unidentified. Mast cells can be activated by immunoglobulins and in the present study, we aimed to establish whether specific immunoglobulins in plasma of patients scheduled for carotid endarterectomy were related to (activated) intraplaque mast cell numbers and plasma tryptase levels. In addition, the levels were related to other vulnerable plaque characteristics and baseline clinical data.

Methods and Results

OxLDL-IgG, total IgG and total IgE levels were measured in 135 patients who underwent carotid endarterectomy. No associations were observed between the tested plasma immunoglobulin levels and total mast cell numbers in atherosclerotic plaques. Furthermore, no associations were found between IgG levels and the following plaque characteristics: lipid core size, degree of calcification, number of macrophages or smooth muscle cells, amount of collagen and number of microvessels. Interestingly, statin use was negatively associated with plasma IgE and oxLDL-IgG levels.

Conclusions

In patients suffering from carotid artery disease, total IgE, total IgG and oxLDL-IgG levels do not associate with plaque mast cell numbers or other vulnerable plaque histopathological characteristics. This study thus does not provide evidence that the immunoglobulins tested in our cohort play a role in intraplaque mast cell activation or grade of atherosclerosis.

Increased platelet activation in early symptomatic vs. asymptomatic carotid stenosis and relationship with microembolic status: results from the Platelets and Carotid Stenosis Study

BACKGROUND

Cerebral microembolic signals (MES) may predict increased stroke risk in carotid stenosis. However, the relationship between platelet counts or platelet activation status and MES in symptomatic vs. asymptomatic carotid stenosis has not been comprehensively assessed.

SETTING

University teaching hospitals.

METHODS

This prospective, pilot observational study assessed platelet counts and platelet activation status, and the relationship between platelet activation and MES in asymptomatic vs. early (≤ 4 weeks after TIA/stroke) and late phase (≥ 3 months) symptomatic moderate or severe (≥ 50%) carotid stenosis patients. Full blood count measurements were performed, and whole blood flow cytometry was used to quantify platelet surface activation marker expression (CD62P and CD63) and circulating leucocyte-platelet complexes. Bilateral simultaneous transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed for 1 h to classify patients as MES positive or MES negative.

RESULTS

Data from 31 asymptomatic patients were compared with 46 symptomatic patients in the early phase, and 35 of these patients were followed up to the late phase after symptom onset. The median platelet count (211 vs. 200 × 10(9)  L(-1) ; P = 0.03) and the median percentage of lymphocyte-platelet complexes was higher in early symptomatic than asymptomatic patients (2.8 vs. 2.4%; P = 0.001). The percentage of lymphocyte-platelet complexes was higher in early symptomatic than in asymptomatic patients with ≥ 70% carotid stenosis (P = 0.0005) and symptomatic patients recruited within 7 days of symptom onset (P = 0.028). Complete TCD data were available in 25 asymptomatic, 31 early phase symptomatic and 27 late phase symptomatic patients. Twelve per cent of asymptomatic vs. 32% of early phase symptomatic (P = 0.02) and 19% of late phase symptomatic patients (P = 0.2) were MES positive. Early symptomatic MES-negative patients had a higher percentage of lymphocyte-platelet complexes than asymptomatic MES-negative patients (2.8 vs. 2.3%; P = 0.0085).

DISCUSSION

Recently, symptomatic carotid stenosis patients have had higher platelet counts (potentially reflecting increased platelet production, mobilization or reduced clearance) and platelet activation status than asymptomatic patients. MES were more frequently detected in early symptomatic than asymptomatic patients, but the differences between late symptomatic and asymptomatic groups were not significant. Increased lymphocyte-platelet complex formation in recently symptomatic vs. asymptomatic MES-negative patients indicates enhanced platelet activation in this early symptomatic subgroup. Platelet biomarkers, in combination with TCD, have the potential to aid risk-stratification in asymptomatic and symptomatic carotid stenosis patients.

Viral cross-class serpin inhibits vascular inflammation and T lymphocyte fratricide; a study in rodent models in vivo and human cell lines in vitro

Poxviruses express highly active inhibitors, including serine proteinase inhibitors (serpins), designed to target host immune defense pathways. Recent work has demonstrated clinical efficacy for a secreted, myxomaviral serpin, Serp-1, which targets the thrombotic and thrombolytic proteases, suggesting that other viral serpins may have therapeutic application. Serp-2 and CrmA are intracellular cross-class poxviral serpins, with entirely distinct functions from the Serp-1 protein. Serp-2 and CrmA block the serine protease granzyme B (GzmB) and cysteine proteases, caspases 1 and 8, in apoptotic pathways, but have not been examined for extracellular anti-inflammatory activity. We examined the ability of these cross-class serpins to inhibit plaque growth after arterial damage or transplant and to reduce leukocyte apoptosis. We observed that purified Serp-2, but not CrmA, given as a systemic infusion after angioplasty, transplant, or cuff-compression injury markedly reduced plaque growth in mouse and rat models in vivo. Plaque growth was inhibited both locally at sites of surgical trauma, angioplasty or transplant, and systemically at non-injured sites in ApoE-deficient hyperlipidemic mice. With analysis in vitro of human cells in culture, Serp-2 selectively inhibited T cell caspase activity and blocked cytotoxic T cell (CTL) mediated killing of T lymphocytes (termed fratricide). Conversely, both Serp-2 and CrmA inhibited monocyte apoptosis. Serp-2 inhibitory activity was significantly compromised either in vitro with GzmB antibody or in vivo in ApoE/GzmB double knockout mice. Conclusions The viral cross-class serpin, Serp-2, that targets both apoptotic and inflammatory pathways, reduces vascular inflammation in a GzmB-dependent fashion in vivo, and inhibits human T cell apoptosis in vitro. These findings indicate that therapies targeting Granzyme B and/or T cell apoptosis may be used to inhibit T lymphocyte apoptosis and inflammation in response to arterial injury.

Impact of carotid artery stenting on plasma interleukin-6, tumor necrosis factor-α and C-reactive protein

AIM

This study aimed to investigate the impact of carotid artery stenting (CAS) on plasma levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and C-reactive protein (CRP).

METHODS

The levels of CRP, IL-6, and TNF-α were measured in 61 patients before CAS, 1 h, 2 weeks, 1 month, 6 months, and 12 months after the stenting.

RESULTS

The levels of CRP, IL-6 and TNF-α increased immediately after CAS (P<0.05 or <0.01). The levels of CRP, IL-6 and TNF-α in patients receiving two stents for multiple lesions or single diffusive lesions was also high than in patients receiving one stent for a single lesion (P<0.05 or <0.01). The levels of CRP, IL-6 and TNF-α in patients with restenosis (14/61, or 23%) were higher than in those without restenosis (P<0.05 or <0.01).

CONCLUSION

CAS was associated with a significant increase in plasma CRP, IL-6 and TNF-α. The levels of these inflammatory factors in patients with post-CAS restenosis were higher than in those without restenosis.

The proinflammatory mediator's production from ischemic brain during carotid endarterectomy

AIM

The aim of the study was to determine the quantity of produced mediators of inflammation (cytokines and eicosanoids), during carotid endarterectomy (CEA), which are factors of ischemic damage of the brain.

METHODS

Two groups (A and B) of 15 patients each, with internal carotid backpressure >30 mmHg were operated in our institution. We did not use a shunt in Group A during CEA and group B was operated upon with a shunt. Plasma concentrations of Interleukin-1b (IL-1b), Thromboxane B2 (TXB2), Prostaglandin E2 (PGE2) and tumor necrosis factor-a (TNFa) were measured by enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

We measured gradual increase of levels of IL-1b and TXB2 during cross-clamping and during reperfusion in group A (P<0.05). The levels of TNFa increased only during reperfusion (P<0.05). The concentration of IL-1b and TNFa remained almost stable in group B, whereas the concentration of TXB2 reduced but not significantly (P>0.05). The levels of PGE2 remained stable in both groups.

CONCLUSION

We should consider the increase of proinflammatory mediators during carotid cross-clamping when no shunt is used. The critical concentration of these mediators that threaten the brain's vitality is not yet detected. However, the clinical significance of this is unclear, since there were no perioperative strokes.

[Correlation of some biochemical and coagulological parameters in carotid atherosclerosis]

It has been established positive correlation of the degree of stenosis and intima-media thickness of carotid arteries with the following biochemical parameters: total cholesterol, LDL cholesterol, Apo-B, Lp(a), triglycerides, hs-C-reactive protein(CRP), interleukines (IL-1beta and IL-6), fibrinogen, D-dimers. Negative correlation was stated with respect to HDL cholesterol, Apo-A-1, protein C. Relation between the parameters of the blood lipid spectre, proteins and mediators of inflammation as well as those of hemostasis enables us to approach pathophysiological mechanisms of carotid atherosclerosis, define the processes of inflammation and atherosclerosis.

Serum interleukin-6 is elevated in symptomatic carotid bifurcation disease

INTRODUCTION

The levels of circulating proinflammatory cytokines may express the extent of the inflammatory response and their participation in plaque progression and rupture needs to be evaluated. We aimed to investigate differences in circulating levels of proinflammatory cytokines and in plaque infiltration by macrophages between patients undergoing carotid endarterectomy for symptomatic and asymptomatic carotid atherosclerotic disease.

METHODS

One hundred nineteen patients (91 men and 28 women; mean age 66 +/- 8 years; range 42-83 years) who underwent carotid endarterectomy for significant (>70%) carotid bifurcation stenosis were enrolled in this study. Patients were characterized as symptomatic (n = 62) or asymptomatic (n = 57) after neurological examination. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, serum amyloid A (SAA), and high-sensitivity C-reactive protein (hs-CRP) were evaluated. Macrophage infiltration of the plaque was assessed quantitatively from endarterectomy specimens using the monoclonal antibody CD68.

RESULTS

Serum IL-6 levels were significantly higher in patients with symptomatic compared with those with asymptomatic carotid disease (3.3 [2.0-6.5] pg/ml vs 2.5 [1.9-4.1] pg/ml, P = 0.02). TNF-alpha, IL-1beta, SAA, and hs-CRP levels did not differ significantly between the two groups. Symptomatic patients had also more intense macrophage accumulation in the carotid plaque compared with asymptomatic patients (0.6 +/- 0.1% vs 0.4 +/- 0.1%, P < 0.001). Although there were correlations between the levels of the different inflammatory markers, there were no correlation between any of them and the extent of plaque macrophage infiltration.

CONCLUSION

Patients with symptomatic carotid atherosclerotic disease have elevated serum IL-6 levels compared with asymptomatic patients. Symptomatic patients have also more intense macrophage infiltration of the atherosclerotic plaque suggesting that inflammatory process may contribute to the destabilization of the carotid plaque.

Oxidized haemoglobin as antigenic target of cell-mediated immune reactions in patients with carotid atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which immune responses play a crucial role. Evidence exist demonstrating the involvement of autoimmune mechanisms in atherogenesis. Our aim in this study was to evaluate the possible role of human oxidized haemoglobin (Hb) as antigenic target of cell-mediated immune reactions in carotid atherosclerosis. PBMC from 44 patients and 24 healthy subjects, and T lymphocytes isolated from 9 carotid atherosclerotic plaques were tested by cell proliferation assay and by ELISA for cytokine production in response to oxidized Hb. This molecule induced a proliferative response in 21 of 44 (48%) patients' PBMC samples, in 12 of 24 (50%) healthy subjects' PBMC samples and in 2 of 9 (22%) infiltrating T lymphocyte samples. Cells from patients proliferating in response to oxidized Hb showed high levels of the pro-inflammatory cytokines interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha. Our findings implicate oxidized Hb as a possible antigenic target of cell-mediated immune responses contributing to inflammation in the pathogenesis of carotid atherosclerosis.

[AECA plasmatic levels in patients with severe dyslipidemia and carotid stenosis]

Anti-endothelial cell antibodies (AECA) are a heterogeneous family of autoantibodies directed against antigens adhering to endothelial cells. These autoantibodies have a pathogenic role in disease characterized by endothelial damage. Aim of this study was to investigate the correlation between AECA and carotid artery stenosis at early stages of atherosclerosis process.

Chlamydia pneumoniae seropositivity in aetiological subtypes of brain infarction and carotid atherosclerosis: a case control study

BACKGROUND AND OBJECTIVE

Many patients with brain infarction (BI) lack traditional risk factors, suggesting that other factors (including infectious agents) might contribute to stroke risk. We investigated Chlamydia pneumoniae infection in a large cohort of patients with BI according to aetiological subtypes and carotid atherosclerosis.

METHODS

We measured serum IgG and IgA to C. pneumoniae by microimmunofluorescence in 483 BI cases and 483 controls matched for age, sex and centre. IgG > or = 1/32 and IgA > or = 1/24 were considered positive. Cases with BI proven by magnetic resonance imaging were consecutively recruited and were classified into aetiological subtypes. Carotid atherosclerosis (intima-media thickness, plaques, stenosis) was evaluated by duplex ultrasonography in all subjects following the same method and with central reading.

RESULTS

C. pneumoniae IgG seropositivity was not associated with BI (adjusted odds ratio (OR) 1.10, 95% confidence interval (CI) 0.80-1.51) and did not increase the risk of any aetiological subtype. Overall, C. pneumoniae IgA was not associated with BI (adjusted OR 1.54, 95% CI 0.84-2.81), but there was a significant interaction with hypertension. IgA seropositivity increased the BI risk in patients without hypertension (adjusted OR 2.79, 95% CI 1.15 to 6.74). When stratifying BI into subtypes, IgA seropositivity increased the risk of BI of unknown cause, but without significant heterogeneity. There was neither association with atherothrombotic, lacunar and cardioembolic BI nor with carotid intima-media thickness, carotid plaques or stenosis.

CONCLUSIONS

We found no evidence that C. pneumoniae seropositivity is associated with carotid atherosclerosis and BI, regardless of aetiological subtype; but it might be associated with an increased risk of BI in normotensive patients.

The +838 C/G MT2A polymorphism, metals, and the inflammatory/immune response in carotid artery stenosis in elderly people

Carotid artery stenosis (CS) is a well-established risk factor for stroke. Increased proinflammatory chemokines, enhanced metallothionein (MT), and altered metal homeostasis may play roles in atherosclerosis progression and plaque destabilization. MT may sequester zinc during chronic inflammation, provoke zinc deficiency, and modulate NK cell cytotoxicity. A recent investigation of older patients with diabetes and atherosclerosis showed an association between the -209 A/G MT2A polymorphism, CS, and zinc status. In this study, we evaluated the relationship between two MT2A polymorphisms (-209 and + 838 locus), metal status, and inflammatory/immune response in older patients with CS only (the CS1 group) or with CS and previous cerebrovascular episodes (transient ischemic attack or stroke) (the CS2 group). A total of 506 individuals (188 CS1, 100 CS2, and 218 healthy controls) were studied. Atherosclerotic patients (CS1 and CS2) showed increased levels of MT, MCP-1, and RANTES, reduced NK cell cytotoxicity, and altered trace element concentrations (zinc, copper, magnesium, iron). The +838 C/G MT2A polymorphism was differently distributed in CS1 and CS2 patients, who displayed the GG genotype (C-) with significantly higher frequency than elderly controls. C- carriers showed increased MCP-1 and decreased NK cell cytotoxicity, CD56+ cells, and intracellular zinc availability along with decreased zinc, copper, and magnesium content in erythrocytes and increased iron in plasma. C- carriers also showed a major incidence of soft carotid plaques. In conclusion, the +838 C/G MT2A polymorphism seems to influence inflammatory markers, zinc availability, NK cell cytotoxicity, and trace element status, all of which may promote CS development.

[Statins and their influence on inflammatory processes in internal carotid artery stenosis]

Arterio-arterial emboli originating from a high-grade stenosis of the internal carotid artery are a common cause for cerebral ischemias. Inflammatory processes are not only pivotal in the development of atherosclerotic vessel wall changes, but also for their clinical destabilization. Inflammatory cells, like macrophages, can turn a chronic high-grade carotid stenosis into a high-risk area for the development of arterial thromboses by way of a complex pathogenesis involving the elevation of proinflammatory factors, biosynthesis of collagen-degrading matrix metalloproteinases and expression of prothrombotic tissue factor. This process could affect the occurrence of perioperative complications during carotid endarterectomies. Statins are potent cholesterol-lowering agents. Among other lipid-independent effects, statins appear to play a significant role in preventing cardiovascular events. A number of studies have shown that statins possess plaque-stabilizing effects and that they improve cerebral autoregulation. A growing evidence supports the preoperative administration of statins in patients with high-grade stenoses of the internal carotid artery.

Glucocorticoid-induced tumour necrosis factor receptor family related protein (GITR) mediates inflammatory activation of macrophages that can destabilize atherosclerotic plaques

Glucocorticoid-induced tumour necrosis factor receptor family related protein (GITR) is the 18th member of the tumour necrosis factor receptor superfamily (TNFRSF18) and is known to interact with its cognate ligand GITRL (TNFSF18). We investigated the potential role of GITR in the pro-inflammatory activation of macrophages. Immunohistochemistry and in situ hybridization analyses of human atherosclerotic plaques demonstrated that GITR and its ligand are expressed mainly in lipid-rich macrophages. We then investigated the role of GITR in human and mouse monocyte/macrophage functions. Stimulation of GITR caused nuclear factor (NF)-kappaB-dependent activation of matrix metalloproteinase-9 (MMP-9) and pro-inflammatory cytokine expression in both the human and mouse monocytic/macrophage cell lines, THP-1 and RAW264.7, respectively. These cellular responses were also observed when the THP-1 cells were treated with phorbol-12 myristate-13 acetate (PMA), which is known to induce macrophage differentiation. To demonstrate that these responses are not restricted to cultured cell lines, we tested primary macrophages. Both peritoneal and bone marrow-derived macrophages responded to GITR stimulation with induction of MMP-9 and tumour necrosis factor-alpha (TNF-alpha). Furthermore, the GITR staining pattern overlapped with those of MMP-9 and TNF-alpha in atherosclerotic plaques. These data indicate that GITR-mediated macrophage activation may promote atherogenesis via the induction of pro-atherogenic cytokines/chemokines, and destabilize the atherosclerotic plaques via the induction of the matrix-degrading enzyme, MMP-9.

Insulin-like growth factor-1 and TNF-alpha regulate autophagy through c-jun N-terminal kinase and Akt pathways in human atherosclerotic vascular smooth cells

A balance between programmed cell death and survival of vascular smooth muscle cells (VSMC) in the fibrous cap, which is primarily composed of VSMC and extracellular matrix, appears to best correlate with plaque instability or stability and is controlled by growth factors and cytokines. Autophagy is also involved in programmed cell death. We assessed the effect of TNF-alpha and insulin-like growth factor-1 (IGF-1) on the expression of autophagic genes, microtubule-associated protein 1 light chain 3 (MAPLC-3) and Beclin-1 in VSMC isolated from atherosclerotic plaques. Transmission electron microscopy showed a significantly higher number of vacuolated cells in the TNF-alpha-treated VSMC and a markedly lower number in the IGF-1-treated VSMC when compared with the untreated control group. TNF-alpha-induced MAPLC-3 mRNA expression through c-jun N-terminal kinase and protein kinase B pathways and induced Beclin-1 protein expression through the c-jun N-terminal kinase pathway. Expression of MAPLC-3 and Beclin-1 correlated with autophagic cell death of plaque VSMC. IGF-1 inhibited MAPLC-3 mRNA transcripts through the Akt pathway. These findings suggest that the expression of autophagy genes can be influenced by IGF-1 and TNF-alpha through c-jun N-terminal kinase or Akt pathways and autophagy might be involved in the regulation of plaque stability.

Differential effects of insulin-like growth factor-1 and atheroma-associated cytokines on cell proliferation and apoptosis in plaque smooth muscle cells of symptomatic and asymptomatic patients with carotid stenosis

Morbidity and mortality from atherosclerosis are associated with complicated atherosclerotic lesions due to plaque rupture, which is regulated by a balance between proliferation and apoptosis of vascular smooth muscle cells (VSMC). We examined insulin-like growth factor-1 (IGF-1)-induced survival of plaque VSMC from carotid endarterectomy specimens and investigated the underlying cellular mechanisms in the presence and absence of IL-12 and IFN-gamma. Both IL-12 and IFN-gamma were strongly expressed in symptomatic atherosclerotic plaques as compared with asymptomatic plaques. In asymptomatic plaque VSMC, IGF-1 induced the survival and proliferation of VSMC and accelerated VSMC into S-phase. IL-12 or IFN-gamma inhibited proliferation and VSMC were arrested in the G0-G1 phase. IGF-1 markedly inhibited the expression of p27(kip) and p21(cip) and significantly induced cyclin E and cyclin D. Both cytokines by themselves increased the expression of p27(kip) and p21(cip) and inhibited cyclin E and cyclin D. On the contrary, in symptomatic VSMC there was already increased apoptosis of VSMC and there was no significant effect of IGF-1 or inflammatory cytokines on proliferation, apoptosis or the expression of p27(kip) and p21(cip) and cyclin D and E. These data suggest that IGF-1 is more potent in inducing the survival of VSMC from the endarterectomy specimens of asymptomatic patients as compared to that of symptomatic subjects and cytokines associated with atheroma lesions decrease the activity of IGF-1-induced survival in the VSMC of asymptomatic plaques. The different expression and activity of cell cycle regulatory proteins could be responsible for apoptosis of VSMC and destabilization of atherosclerotic plaques.

Endothelial Apoptosis Does Not Determine Symptom Status in Carotid Artery Disease

BACKGROUND

We examined the hypothesis that endothelial denudation in advanced carotid plaques (CPs) occurs by increased apoptosis of endothelial cells (ECs) using scanning electron microscopy (SEM) as well as markers of cellular proliferation and apoptosis in advanced symptomatic CPs (SCPs) and asymptomatic CPs (ACPs).

METHODS

93 consecutive patients underwent carotid endarterectomy. Five additional specimens were studied by SEM. We performed TUNEL assays, and immunostaining against Fas receptor (FasR), Fas ligand (FasL), activated caspase 3 (ACA3) and Ki-67.

RESULTS

SEM revealed morphological changes consistent with EC detachment. Surprisingly, ACA3 positivity was more pronounced on the endothelium of ACPs (4.6 +/- 0.7% of total EC count) than on SCPs (3.3 +/- 0.7%, p = 0.049), and was found to correlate positively with nuclear Ki-67 expression (r(s) = 0.275, p = 0.040). FasL expression was significantly increased on the endothelium of SCPs compared with ACPs (66.4 +/- 4.4 vs. 53.9 +/- 4.5%, p = 0.047).

CONCLUSIONS

Absence of increased positivity of apoptotic markers dismisses apoptosis as a dominant mechanism underlying endothelial detachment of SCPs. Rather, increased ACA3 with co-expression of Ki-67 in ACPs might suggest that renewal of endothelium by active cell turnover may contribute to clinically silent evolution of plaques with preserved EC integrity. These observations may assist in designing novel therapies to prevent endothelial decay and symptom generation in advanced carotid artery disease.

Decrease in Circulating Myeloid Dendritic Cell Precursors in Coronary Artery Disease

OBJECTIVES

We analyzed the frequency of myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) precursors in blood of patients with coronary artery disease (CAD) and in atherosclerotic carotid plaques of patients with cerebrovascular disease (CVD).

BACKGROUND

Circulating DC precursors are reduced in several autoimmune diseases. Atherosclerosis has features of an autoimmune disease, such as the presence of autoantibodies or autoreactive T cells. Tissue-resident DCs were previously described in atheromata, and it is assumed that they are important for the activation of T cells against autoantigens there.

METHODS

Circulating mDC and pDC precursors were flow cytometrically detected in healthy controls (n = 19), CAD patients with stable (n = 20) and unstable angina pectoris (n = 19), and acute myocardial infarction (n = 17). In human carotid plaques (n = 65), mDC and pDC precursors were identified immunohistochemically.

RESULTS

Circulating mDC precursors were significantly reduced in patients with stable angina pectoris (0.19%, p = 0.04), unstable angina pectoris (0.16%, p = 0.004), and acute myocardial infarction (0.08%, p < 0.001) compared with control patients (0.22% of peripheral blood mononuclear cells). In contrast, pDC numbers were not significantly altered. Circulating mDC precursors inversely correlated with high-sensitivity C-reactive protein (r = -0.38, p = 0.001) or interleukin-6 (r = -0.42, p < 0.001). In contrast to pDC, significantly more mDC precursors were observed in vulnerable carotid plaques (24, 0.25 mm2; n = 31; p = 0.003) than in stable ones (6.4, 0.25 mm2; n = 34).

CONCLUSIONS

Similar to autoimmune diseases, circulating mDC precursors were significantly reduced in patients with CAD. The emergence of mDC precursors in vulnerable plaques suggests their recruitment into atheromata as a possible reason for their decrease in blood. In contrast, no significant association of circulating pDC precursors with atherosclerosis was observed.

Vascular neutral endopeptidase inhibition improves endothelial function and reduces intimal hyperplasia

OBJECTIVE

Neutral endopeptidase (NEP, EC 3.4.24.11) metabolises endogenous vasoactive peptides that may protect against atherogenesis. Since NEP is found in the adventitia of arteries, we investigated the anti-atherogenic effects of chronic adventitial NEP inhibition.

METHODS

Intimal hyperplasia of rabbit carotid arteries was induced by placement of soft, non-occlusive, peri-arterial silastic collars. NEP localisation was studied with autoradiography 7 and 14 days after collar placement. Vascular NEP was inhibited in vivo by local superfusion of one collared carotid artery with Candoxatrilat (50 pmol/h), for 7 days (n = 7). The contralateral collar was filled with saline vehicle. After 7 days, ring segments of collared and normal (proximal to the collar) arteries were obtained and in vitro functional measurements, immunohistochemical determination of the pro-atherogenic factor plasminogen activator inhibitor-1 (PAI-1), localization of macrophages and morphometric analyses were carried out.

RESULTS

Vascular NEP radiolabelled substrate binding, mainly in the media, was increased by approximately 50% after 7 days (n = 5; p < 0.05) and by approximately 300% after 14 days of collar placement (n = 5; p < 0.05). Compared with normal artery segments from the same animal, vehicle-filled collared sections displayed significantly impaired vasorelaxation to acetylcholine (endothelium-independent vasodilatation was preserved), increased PAI-1 immunostaining, macrophage accumulation and intimal thickening. In Candoxatrilat-treated collared arteries, vasorelaxation to acetylcholine was improved, along with reductions in PAI-1 levels, macrophage numbers and intimal area (all p < 0.05).

CONCLUSION

Enhancing the activity of local, endogenous peptides by adventitial inhibition of vascular NEP may protect against early atherogenesis. This is of particular relevance to using adventitial therapies to prevent intimal hyperplasia leading to restenosis.

Xenogenic smooth muscle cell immunization reduces neointimal formation in balloon-injured rabbit carotid arteries

OBJECTIVE

Intimal hyperplasia plays an important role in a variety of types of vascular remodeling, particularly luminal narrowing after vascular injury. The vascular smooth muscle cells (VSMCs) in the neointimal area are a synthetic phenotype and have different epitopes from VSMCs in the normal media. The synthetic VSMCs in the neointima contain various possible antigens that can be targeted by the immune system. In this study, we tried to develop a new immunotherapy, which targets the synthetic VSMCs, for prevention of neointimal formation after angioplasty.

METHOD AND RESULTS

Rabbits were repeatedly immunized with fixed xenogenic rat cultured VSMCs suspended in adjuvant as immunogens or injected with adjuvant and phosphate-buffered saline (PBS) or rat hepatocytes as controls every 2 weeks for 3 times. One week after the last immunization/injection, balloon injury of the left common carotid artery was performed. Four weeks after the injury, rabbits were euthanized and the neointimal lesion formation was assessed. The mean neointimal area of the PBS-injected, non-immunized group and the rat hepatocyte-immunized, control group was not statistically different (0.339 +/- 0.036 and 0.350 +/- 0.041 mm(2), P = NS). However, immunization with rat VSMCs significantly reduced the intimal lesion area (0.219 +/- 0.0286 mm(2); P < 0.05 vs. PBS-injected, non-immunized group and rat hepatocyte-immunized group.) PCNA-immunopositive proliferating VSMCs in the neointima were suppressed by the rat VSMC immunization (1.34 +/- 0.49% vs. 5.78 +/- 0.47%; P < 0.05 vs. PBS-injected, non-immunized group). Rat VSMC immunization induced antibodies which had strong cross-reactivity against rabbit synthetic VSMCs. In experiments in vitro, proliferation and migration of rabbit VSMCs that were stimulated by serum, angiotensin (AT) II, platelet-derived growth factor (PDGF)-BB, fibroblast growth factor (FGF), and the phorbol ester PMA were significantly suppressed by treatment with immunoglobulin extracted from the VSMC-immunized rabbit plasma, implying that the immunoglobulin had some global effects on VSMCs. The rat VSMC-immunized rabbit immunoglobulin bound the rabbit AT1a receptor protein, which was expressed in COS7 cells by transfection of rabbit AT1a receptor pcDNA3. This binding to AT1a receptor may be one of mechanisms of the effects of VSMC-immunized immunoglobulin.

CONCLUSION

Xenogenic, synthetic rat VSMC immunization in rabbits induced auto-antibodies against synthetic rabbit VSMCs in a cross-reaction. The induced auto-antibodies against synthetic VSMCs may provide a possibility of new immunotherapy for vascular remodeling that forms neointimal lesions.

Effect of the Toll-like receptor 4 (TLR-4) variants on intima-media thickness and monocyte-derived macrophage response to LPS

OBJECTIVES

Toll-like receptor 4 (TLR-4) is believed to contribute to the initiation and progression of atherosclerosis. The association of the D299G polymorphism of the TLR-4 gene with the progression of coronary and carotid atherosclerosis, risk of cardiovascular events and myocardial infarction is controversial. We have investigated whether the presence of the D299G polymorphism and the co-segregated T399I polymorphism affects the intima-media thickness (IMT) in the general population.

SUBJECTS

The PLIC study population (n = 1256) was genotyped for the D299G and the T399I polymorphisms.

RESULTS

The presence of both the D299G and T399I alleles was observed in the 13.0% of the population, carriers of the T399I alone were 1.8% and of the D299G alone were 0.9%. No difference in IMT was detected within the carriers of the D299G and T399I alleles and the wild-type subjects in the PLIC population. Furthermore, we investigated whether monocyte from D299G to T399I subjects present a defective response to CD40, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, cyclo-oxygenase (COX)-2 and PTX3 expression induced by lipopolysaccharide (LPS). When the monocyte-derived macrophages of these subjects were challenged with LPS (1 mug mL(-1)), no impact of the polymorphisms on the induction of CD40, MCP-1 and PTX3 was observed. Only IL-6 and COX-2 induction by LPS resulted reduced in the D299G/T399I carriers.

CONCLUSION

The presence of the D299G and T399I polymorphisms of the TLR-4 gene does not play a major role on the progression of carotid atherosclerosis. Macrophages from the subjects carrying the polymorphisms show an impaired response to LPS limited only to a IL-6 and COX-2.

Autoantibodies against oxidized LDLs and atherosclerosis in type 2 diabetes

OBJECTIVE

The aim of our study was to examine, in type 2 diabetic patients, the relationship between autoantibodies against oxidatively modified LDL (oxLDL Ab) and two indexes of atherosclerosis, intimal-medial thickness of the common carotid artery (CCA-IMT), which reflects early atherosclerosis, and the ankle-brachial index (ABI), which reflects advanced atherosclerosis.

RESEARCH DESIGN AND METHODS

Thirty newly diagnosed type 2 diabetic patients, 30 type 2 diabetic patients with long duration of disease, and 56 control subjects were studied. To detect oxLDL Ab, the ImmunoLisa Anti-oxLDL Antibody ELISA was used. ABI was estimated at rest by strain-gauge plethysmography. Carotid B-mode imaging was performed on a high-resolution imaging system (ATL HDI 5000).

RESULTS

In patients with long duration of disease, IgG oxLDL Ab were significantly higher and ABI significantly lower compared with the other two groups. We found a correlation between IgG oxLDL Ab and CCA-IMT in all diabetic patients. A significant inverse correlation between IgG oxLDL Ab and ABI only in patients with long duration of disease was seen, demonstrating a close relationship between these autoantibodies and advanced atherosclerosis.

CONCLUSIONS

IgG OxLDL Ab may be markers of the advanced phase of the atherosclerotic process and the response of the immunological system to the oxLDL, which are present within atherosclerotic lesions.

Bisphosphonates induce inflammation and rupture of atherosclerotic plaques in apolipoprotein-E null mice

The apolipoprotein E knockout (Apo-E-/-) mouse is a well-known model of atherosclerosis. Bisphosphonates, through their affinity to hydroxyapatite, are known to reduce arterial calcification in several animal models. Thus, we examined the effect of two therapeutically used oral bisphosphonates, alendronate and risedronate, on plaque formation in the Apo-E-/- mouse. The drugs were administered by gavage to 16-week-old Apo-E-/- mice for 8 weeks. At 8 weeks, there was no difference in bone mineral density (BMD) of the alendronate- and risedronate-treated mice at any site. A time-dependent increase in BMD was demonstrated in Apo-E-/- mice with risedronate (p<0.01). Histological evaluation revealed that both bisphosphonates caused atherosclerotic plaque rupture. Five of 17 mice had severe inflammation with or without plaque rupture, while seven mice showed inflammation, but without plaque rupture. Neither caspase 3 nor metalloproteinases 2 and 9 were increased in ruptured plaques on immunocytochemistry. Quantitative measurements of arterial caliber remained unaffected. Our finding of plaque inflammation and rupture in bisphosphonate-treated Apo-E-/- mice may provide the first animal model for studies aimed at characterizing mechanisms of plaque rupture in animal models.

Morphological analysis of cell subpopulations within carotid atherosclerotic plaques

Atherosclerosis is considered a chronic inflammatory process, prompted by lipid accumulation and propagated by cell-mediated mechanisms. The present work was undertaken to clarify this process by characterizing cellular components of inflammatory infiltrate localized within atheroma. Cryostat sections of atherosclerotic lesions obtained from human carotid endarterectomy were analysed immunohistochemically by using monoclonal and polyclonal antibody directed against T cell subpopulations (CD3, CD4, CD8), B cells (CD20), plasma cells (CD138), macrophages (CD14), mast cells (anti-tryptase). Our results assess that T cells are the predominant cell type among plaque infiltrating inflammatory cells. B cells were detected near the lipid core of atheroma and clusters of plasma cells were observed within cellular infiltrates in most plaques. Numerous tryptase positive mast cells were noticed in many areas of complicated lesions. Our results indicate the presence of many inflammatory cells within type V and VI atherosclerotic plaques, suggesting the involvement of those cells in plaque progression. In fact it was previously shown that stability of atherosclerotic lesions is influenced by mast cell-released matrix metalloproteinases which induce plaque rupture and by cytokines and chemokines which increase local inflammatory response and are produced by lymphocytes and macrophages.

Emergence of dendritic cells in rupture-prone regions of vulnerable carotid plaques

Dendritic cells (DC), which are critically involved in various immunological disorders, were detected in atherosclerotic plaques in 1995. Since DC might be related to the immunological processes in atherosclerosis (AS), we analyzed the emergence of DC and other inflammatory cells in different stages of AS. Serial cross-sections of 44 carotid specimens were immunohistochemically analyzed for the presence of DC, T cells, macrophages, and HLA-DR. Atherosclerotic specimens were histologically defined as initial lesions, advanced stable, or vulnerable plaques. In initial lesions significantly lower DC numbers were detected than in advanced plaques (P < 0.001). For advanced plaques, DC numbers were significantly higher in vulnerable than in stable plaques (P = 0.005). In contrast to initial lesions, approximately 70% of DC in advanced plaques exhibited a mature phenotype (CD83+, DC-LAMP+), indicating a functional activity of DC. In plaques of patients with acute ischemic symptoms DC numbers were markedly elevated (P = 0.03), whereas significantly lower DC numbers and more often a stable plaque morphology were detected in statin-treated patients (P = 0.02). DC clusters with a strong HLA-DR expression and frequent DC-T cell contacts were located particularly in the rupture-prone plaque regions and at complications. The results of the present study indicate that DC might contribute to plaque destabilization through an activation of T cells.

Degree of carotid plaque calcification in relation to symptomatic outcome and plaque inflammation

OBJECTIVE

We undertook this study to quantitate differences in the degree of calcification between symptomatic and asymptomatic plaques removed at carotid endarterectomy (CEA) and to determine associated extent of plaque macrophage infiltration, a histopathologic feature of plaque instability.

METHODS

CEA plaques (n = 48) were imaged at 1.25-mm intervals with spiral computed tomography (CT; 10-15 images per plaque). Indications for CEA were transient ischemic attack (n = 16), stroke (n = 5), amaurosis (n = 4), and critical asymptomatic stenosis (n = 23). The percent area calcification for each plaque was determined in spiral CT serial sections and averaged for each plaque. In 31 of 48 plaques macrophage infiltration was quantitated in corresponding histologic sections with immunohistochemical techniques.

RESULTS

The mean (+/- SD) age of patients with symptomatic and asymptomatic plaques was 66 +/- 7 years vs 71 +/- 7 years, respectively, and degree of stenosis was 76% versus 82%, respectively (P =.05). Atherosclerosis risk factors were similar between groups. Percent plaque area calcification was twofold greater in asymptomatic versus symptomatic plaques (48% +/- 19% vs 24% +/- 20%, respectively; P <.05). At receiver operating characteristic curve analysis, 80% of symptomatic plaques were below and 87% of asymptomatic plaques were above a cutoff point of 30% plaque area calcification. Macrophage burden was greater in the symptomatic plaques than in the asymptomatic plaques (52% vs 23%; P <.03). A strong inverse relationship between the degree of plaque calcification and macrophage infiltration was found in critical carotid stenoses (r = -0.87; P <.001).

CONCLUSIONS

Symptomatic plaques are less calcified and more inflamed than asymptomatic plaques. Regardless of clinical outcome, a strong inverse correlation was found between the extent of carotid plaque calcification and the intensity of plaque fibrous cap inflammation as determined by the degree of macrophage infiltration. Carotid plaque calcification is associated with plaque stability, and is a potential spiral CT in vivo quantitative marker for cerebrovascular ischemic event risk.

Estradiol and Progestins Differentially Modulate Leukocyte Infiltration After Vascular Injury

Background— Inflammation plays an important role in the response to endoluminal vascular injury. Estrogen (17β-estradiol, E 2 ) inhibits neointima formation in animal models, and the progestin medroxyprogesterone acetate (MPA) blocks this effect. This study tested the hypothesis that E 2 inhibits the migration of inflammatory cells, particularly granulocytes, into the rat carotid arteries after acute endoluminal injury and that MPA blocks this effect.

Methods and Results— Ovariectomized rats were randomly divided into subgroups and treated with E 2 , MPA, E 2 +MPA, or vehicle and subjected to balloon injury of the right carotid artery. After 1, 3, or 7 days, rats were euthanized, and carotid arteries (injured and control) were analyzed for inflammatory cells by flow cytometry. At 1 day, granulocytes (HIS48 + and CD45 + ), monocyte/macrophages (Mar1 + and CD45 + ), and T lymphocytes (CD3 + and CD45 + ) were increased 26-fold, 12-fold, and 3-fold, respectively, in injured compared with contralateral control arteries of vehicle-treated rats. Granulocytes and monocyte/macrophages decreased markedly by 3 days. E 2 reduced the granulocyte and monocyte/macrophage populations of injured vessels by ≈50% and increased T lymphocytes. MPA had no independent effect on inflammatory cells but completely blocked the effect of E 2 . Immunohistochemical examination verified these findings and localized inflammatory cells to the adventitial and periadventitial domains of injured vessels.

Conclusions— E 2 may limit the neointimal response to endoluminal vascular injury, at least in part, by limiting leukocyte entry from adventitial/periadventitial tissues into injured vessels early in the injury response.

High-sensitivity C-reactive protein in high-grade carotid stenosis: risk marker for unstable carotid plaque

OBJECTIVES

Increasing evidence points to the inflammatory character of atherosclerosis, and several parameters of inflammation have been proposed as cardiovascular risk markers. We analyzed associations among serum high-sensitivity C-reactive protein (hs-CRP) concentrations, carotid plaque structure, and immunocytology, and neurologic symptoms in patients with high-grade carotid stenosis.

METHODS

This was a cross-sectional study in a referral center and institutional practice in hospitalized patients. The study included 62 patients with greater than 70% carotid stenosis treated surgically; 58% of patients had symptoms, and 42% did not. Serum hs-CRP concentrations were determined 48 hours before surgery; levels greater than 10 mg/L were considered pathologic. Histopathologic analysis (stable or unstable) and immunohistochemistry (macrophage count, T lymphocytes, activated T lymphocytes) were carried out on the atherosclerotic plaques.

RESULTS

Median hs-CRP values were 7.6 mg/L (range, 0-165 mg/L). Median hs-CRP concentrations were higher in patients with unstable plaque (53.2%) than in patients with stable plaque (46.7%): 27.1 mg/L (range, 1.8-165 mg/L) versus 4.1 mg/L (range, 0.3-56 mg/L) (P <.001). Among patients with symptomatic disease, 81% had CRP concentrations significantly higher than CRP concentrations in patients with asymptomatic disease (P <.001). A statistically significant association was found between hs-CRP levels and the presence of macrophages (Spearman rank correlation [rho], 0.61, P <.001) and T lymphocytes in the plaque (Spearman rank correlation [rho], 0.52, P <.001). At logistic regression analysis, neurologic event and macrophages in the plaque were independently associated with unstable plaque.

CONCLUSIONS

Increased hs-CRP levels may be related to the presence of macrophages and T lymphocytes in plaque, which is associated with the phenomena of instability that can lead to development of an ischemic event. Thus determination of circulating hs-CRP levels may be a useful additional marker of risk in patients with high-grade carotid stenosis.

Identification of immune responses against aldehyde-modified peptide sequences in apoB associated with cardiovascular disease

OBJECTIVE

Atherosclerosis is associated with an immune response against oxidized LDL, which modulates the progression of the disease process.

METHODS AND RESULTS

Using a library of polypeptides covering the complete sequence of apoB-100, the only major protein of LDL, we have identified over 100 different human antibodies reacting against aldehyde-modified apoB-100 sequences. IgM antibody titer levels decreased with age and were associated with the intima-media thickness of the carotid artery in subjects younger than 60 years. There were also inverse associations between IgM levels and oxidized LDL in plasma. In prospective clinical studies, antibody levels against several aldehyde-modified apoB-100 sites were associated with cardiovascular disease in this age group. Whether this immune response is adaptive (protective) or maladaptive (causal) in atherosclerosis requires further investigation.

CONCLUSIONS

We have characterized a large number of epitopes within the apoB-100 component of oxidized LDL that provoke an immune response in humans. These findings will make it possible to study the role of immune responses against specific sites in oxidized LDL and to determine whether these immune responses influence the risk for future cardiac events.

Role of Chlamydia pneumoniae-infected macrophages in atherosclerosis developments of the carotid artery

Chlamydia pneumoniae (C. pneumoniae) infection has been recently accepted as an important cause of atherosclerosis. However, the precise mechanisms remain unclear. The present study was aimed to clarify the distribution link among C. pneumoniae, chlamydial HSP 60, and activated macrophages. Atheromatous carotid plaques were obtained from 40 consecutive carotid endarterectomies (CEA). The specimens were prepared for HE and elastica-van Gieson staining. Parallel sections were stained immunocytochemically with monoclonal antibodies for a C. pneumoniae-specific antigen, chlamydial HSP 60, activated macrophages, and smooth muscle cells. Immunoreactivity for the C. pneumoniae-specific antigen was observed within the endothelial cells, activated macrophages, and smooth muscle cells in 36 of 40 specimens (90%). Chlamydial HSP 60 was found in all specimens positive for the C. pneumoniae-specific antigen, and mainly co-localized with the C. pneumoniae-specific antigen within the activated macrophages. The present results suggest that C. pneumoniae is a key microbial organ that causes atheroma developments in the carotid artery. Chlamydia pneumoniae-infected macrophages may come into the arterial intima and mediate inflammatory and autoimmune processes through the production of chlamydial HSP 60, leading to atherosclerosis.

Both apolipoprotein E and immune deficiency exacerbate neointimal hyperplasia after vascular injury in mice

In this study, we investigated the role of T and B lymphocytes in neointimal hyperplasia after endothelial denudation. Catheter-induced endothelial denudation of wild-type mice resulted in rapid infiltration of lymphocytes to the site of injury. Mice defective in recombination-activating gene 2 (RAG2(-/-)) showed increased neointimal formation 14 days after vascular injury in comparison to their wild-type immune-competent littermates. Immunohistochemical studies revealed the preponderance of smooth muscle cells and a significantly higher number of proliferating cells in the neointima of the RAG2(-/-) mice. The neointima size and the number of proliferating smooth muscle cells in the injured vessel of RAG2(-/-) mice were similar to those observed in the injured arteries of apolipoprotein E (apoE)-deficient (apoE(-/-)) mice. Interestingly, mice with double apoE and RAG2 gene mutations (apoE(-/-) RAG2(-/-)) displayed similar neointimal characteristics as mice with a single gene defect, suggesting a similar mechanism for apoE and lymphocyte protection against injury-induced neointimal formation. The protective role of lymphocytes against neointimal formation after vascular injury directly contrasts to their reported role in the promotion of atherosclerosis, which was observed in both apoE(+/+) and apoE(-/-) mice. Thus, these results support the hypothesis of different etiology between hyperlipidemia-induced atherosclerosis and injury-induced vascular occlusion.

[Relationship between the concentration of antibodies to myosin heavy chains in serum and symptomatic carotid atherosclerosis]

It is believed that atherosclerosis could result from inflammatory-fibroproliferative response to various forms of injury of endothelium and smooth muscle cells of arterial wall. The aim of this study was to examine whether immunological reaction against myosin filaments of carotid artery (CA) wall smooth muscle cells is involved in atherogenesis. 43 patients (22 females) with first-ever ischaemic stroke proven by CT were investigated. The results were compared with those obtained in 40 (21 females) healthy sex- and age-matched subjects. Anti-myosin antibodies (AMA) were evaluated by solid phase radioimmunoassay using rabbit myosin heavy chains as an antigen. The intima-media thickness (IMT) of common and CA--a measure for atherosclerosis--was estimated with the use of high-resolution ultrasonography. The AMA serum concentration in stroke patients was significantly greater than in control subjects (p < 0.001). Mean IMT for CA in stroke patients was significantly increased compared with the controls (0.98 +/- 0.17 mm vs. 0.68 +/- 0.13 mm; p < 0.0001). There was a significant correlation between AMA serum antibodies concentration and IMT (r = 0.51; p < 0.001).

CONCLUSION

The significant correlation between AMA concentration and IMT of CA is the basis of the hypothesis that immunological reaction against myosin heavy chains of smooth muscle cells in CA is involved in atherogenesis.

Increased CD8(+) T cells associated with Chlamydia pneumoniae in symptomatic carotid plaque

BACKGROUND AND PURPOSE

The presence of Chlamydia pneumoniae has been reported in carotid atheroma, but its causative effect in the activation of an atherosclerotic plaque to a prothrombotic state remains unproved. Antigen- mediated activation of T lymphocytes within plaque may represent a mechanism by which infection can result in plaque conversion. The goal of the present study was to characterize the T-cell subtype profile related to the presence of C pneumoniae in patients with symptomatic versus asymptomatic carotid atherosclerosis.

METHODS

We studied 14 plaques (5 symptomatic and 9 asymptomatic) positive for C pneumoniae confirmed by polymerase chain reaction and 14 plaques (6 symptomatic and 8 asymptomatic) from age- and stenosis-matched patients negative for C pneumoniae by polymerase chain reaction. T-cell subpopulations of T-helper, T-cytotoxic, and T-memory lymphocytes were identified through indirect enzyme immunohistochemistry with anti-CD3+, anti-CD4+, anti-CD8+, and anti-CD45RO+ monoclonal antibodies, respectively. Results are expressed as the number of positive cells per millimeter squared.

RESULTS

In the absence of C pneumoniae, symptomatic plaques had a modest but significant increase of CD3+ (89.6 versus 55.3, P=0.013), CD4+ (57.3 versus 32.7, P=0.01), and CD45RO+ (82.8 versus 43.7, P=0.007), but not CD8+ T cells (28.5 versus 25.5, P=0.245) compared with asymptomatic. However, in the presence of C pneumoniae, there was significant increase of all T-lymphocyte subtypes in symptomatic plaques, including CD8+ (76.8 versus 30.3, P=0.03), CD3+ (192.1 versus 80.4, P=0.004), CD4+ (111.9 versus 37.9, P=0.003), and CD45RO+ (120.2 versus 72.9, P=0.003) cells compared with asymptomatic plaques. With use of 2-way ANOVA, both the presence of chlamydia and symptoms were associated with significantly higher T-cell counts (P<0.005 for all subtypes).

CONCLUSIONS

Although all patients with symptomatic disease show a modest elevation in the concentration of intraplaque lymphocytes, a preferential increase in CD8+ class I-restricted T cells is observed in symptomatic carotid plaque positive for C pneumoniae. These data provide incentive to further explore the role of Chlamydia in the modification of immune-mediated mechanisms in active atherosclerotic plaque.

Immunophenotypic characterisation of carotid plaque: increased amount of inflammatory cells as an independent predictor for ischaemic symptoms

OBJECTIVES

To investigate the inflammatory response within intact carotid plaques from carotid eversion endarterectomy (CEE) to determine the relationship between immunohistological plaque morphology and ischaemic cerebrovascular symptoms.

MATERIAL AND METHODS

Intact CEE plaques from 71 patients with high-grade (>70%) stenosis undergoing CEE (group I, symptomatic, n=42; group II, asymptomatic, n =29) and 12 normal postmortem arteries (control group) were analysed with specific antibodies to inflammatory cells (T-Lymphocytes (CD3, CD4), cytotoxic T-cells (CD8), B-lymphocytes (CD20), natural killer cells (CD57), macrophages (CD68)), endothelial adhesion molecules (ICAM-1 (CD54), P-selectin (CD62P), E-selectin (CD62E), VCAM-1 (CD106) and T-lymphocyte co-stimulatory molecule (CD40)) and procoagulatory modulators (thrombomodulin (CD141), tissue factor (CD142)). Both groups were matched for gender, age, risk factors, degree of carotid artery stenosis. Plaques were measured using a semiquantitative score system in a blinded fashion by two observers. Statistical analysis of the group differences were performed by using the Kruskal-Wallis test and the Multitest Procedure with Permutation-Testing. Significance was taken as a p<0.05.

RESULTS

There were significantly more inflammatory cells, an overexpression of P-selectin and the procoagulatory markers thrombomodulin and tissue factor in symptomatic compared to both asymptomatic plaques and the ones of the control group. In both groups there was no significance for ICAM-1, VCAM-1, macrophages and co-stimulatory molecule CD40. There was also no significance for any factor between the asymptomatic and the control group. However, the differences between the symptomatic and the asymptomatic group were highly significant for all factors.

CONCLUSION

These data suggest that structural changes and inflammatory damage within the individual plaque seems to be a critical step in promoting plaque rupture with embolic sequelae.

[Unstable carotid stenosis--an inflammatory disease?]

Arterioarterial thromboembolism from extracranial internal carotid artery (ICA) stenosis is an important pathogenic mechanism of ischemic stroke. However, even a high-grade ICA stenosis carries a greatly variable annual risk of stroke, as high as 13% following a recent occurrence of transient or minor cerebral ischemia or as low as 1-2% in clinically asymptomatic patients. There is increasing evidence that inflammatory processes play a central role in atherosclerosis and particularly in plaque destabilization converting chronic atherosclerosis into an acute neurological disorder. In thromboendarterectomy specimens from patients with high-grade ICA stenoses, the extent of inflammatory infiltration and the expression of matrixmetalloproteinase-9 correlated to clinical and ultrasonic features of plaque destabilization such as cerebral microembolism. Inflammation might become a new therapeutic target in symptomatic carotid artery disease.

Carotid rupture and intraplaque hemorrhage: immunophenotype and role of cells involved

BACKGROUND

A complete immunohistochemical characterization in complicated carotid plaques is still lacking. The cellular components of 165 carotid endarterectomy specimens were analyzed to assess their role in the pathogenesis of plaque rupture and intraplaque hemorrhage without rupture.

METHODS AND RESULTS

The fibrous caps at the sites of plaque rupture showed CD68+ macrophages, T-lymphocytes, and scarce B-lymphocytes. Ruptured plaques showed mononuclear infiltrates in the caps, shoulders, and bases of the plaques in 85% of the cases. Only 46% of nonruptured plaques showed such infiltrates (P <.0001). Two types of lipid cores were recognized: avascular or mildly vascularized and highly vascularized. The vessels of the latter type reacted with CD31 and CD34. In 57.5% of the cases, the base and the shoulders of the plaques showed neoformed, CD34+ vessels, often surrounded by mononuclear infiltrates. Intraplaque hemorrhage without rupture had highly vascularized lipid cores in all cases. T-lymphocytes and macrophages were in close contact with neoformed vessels.

CONCLUSIONS

Plaque rupture is characterized by mononuclear cell infiltration of the caps, whereas intraplaque hemorrhage without rupture is characterized by extensive vascularization of the plaque.

Inflammation in high-grade carotid stenosis: a possible role for macrophages and T cells in plaque destabilization

BACKGROUND AND PURPOSE

Inflammatory mechanisms have been implicated in the pathogenesis of atherosclerosis. In this study, we investigated whether the extent of inflammatory infiltration in high-grade stenoses of the internal carotid artery (ICA) correlates to clinical features of plaque destabilization.

METHODS

Endarterectomy specimens from 37 consecutive patients undergoing surgery for high-grade ICA stenosis were stained immunocytochemically for macrophages (CD68) and T cells (CD3). The staining was quantified by planimetry of immunostained areas (CD68) or counting individual cells (CD3). Clinical evidence of plaque instability was provided by the preoperative assessment of recent ischemic symptoms attributable to the stenosis and of the occurrence of cerebral microembolism in transcranial Doppler ultrasound monitoring of the ipsilateral middle cerebral artery.

RESULTS

The percentage of macrophage-rich areas and number of T cells per mm2 section area were larger in recently symptomatic patients than in asymptomatic patients (macrophages: 18+/-10% versus 11+/-4%, P=0.005; T cells: 71.2+/-34.4 versus 40.5+/-31.4 mm2, P=0.005). The presence of microembolism was associated with an increase in macrophage-rich areas (P=0.011). Macrophage (19+/-10% versus 9+/-3%, P=0.0009) and T cell (71.5+/-39.0 versus 46.4+/-22 mm2, P=0.045) infiltration were more pronounced in predominantly atheromatous than in fibrous plaques, but did not correlate significantly to the presence of surface ulceration or luminal thrombosis.

CONCLUSIONS

Our data suggest a role of plaque-infiltrating macrophages and T cells in the clinical destabilization of high-grade ICA stenoses. Inflammatory mechanisms may be a therapeutic target in patients with symptomatic ICA disease.

The histologic characteristics of primary and restenotic carotid plaque

BACKGROUND

Although smooth muscle cell proliferation is a prominent feature of restenosis in experimental models, the role of cellular proliferation in the initiation and progression of carotid restenosis is not well documented.

METHODS

Between 1985 and 1995, 35 carotid endarterectomies (CEA) in 34 patients were performed for restenosis. Patient risk factors, cerebrovascular symptoms, and operative findings were recorded. Tissue specimens from 29 of these cases and 14 original specimens from the same patient were examined by light microscopy (H&E, trichrome, elastochrome, and Alcian blue) and immunohistochemistry (alpha actin, CD 68, vWF, and proliferating nuclear cell antigen (PCNA)) in order to determine the morphologic characteristics and cellular proliferative activity of the plaque.

RESULTS

Hemodynamically significant recurrent stenosis occurred in the 29 patients (69% symptomatic) between 2 months and 30 years after their initial CEAs. Eleven of 29 (38%) lesions were removed early (< 3 years). Recurrent lesions were characterized based on their components as neointimal thickening, 24% (7/29), neointimal thickening and atherosclerosis, 55% (16/29), or atherosclerotic, 21% (6/29). Nineteen of 29 (66%) plaques were complicated by mural thrombus or intraplaque hemorrhage. An inflammatory cell infiltrate consisting of macrophages and T lymphocytes was observed adjacent to areas of recurrent atherosclerosis and macrophages in regions of intimal thickening. Although infrequently present (generally 1-3% of cells) PCNA-positive cells were detected in 41% (12 of 29) of recurrent and 14% (2 of 14) of primary plaques. No PCNA-positive cells were detected in the remaining 67% (29 of 43) of specimens. There was no statistical difference in the number of PCNA-positive cells in early recurrent lesions compared to those recurring after 3 years (36% vs 44%). PCNA immunoreactivity when present was most commonly noted in macrophages associated with thrombus or atheroma rather than smooth muscle cells.

CONCLUSIONS

Although evidence of cellular proliferation was observed in 40% of recurrent carotid endarterectomy lesions, the proliferation rate was low (1-3%) and unrelated to the time interval of recurrence. Proliferative activity was most pronounced in macrophages associated with intraplaque hemorrhage or atheroma. The contribution of inflammatory cells to the biologic behavior of restenotic lesions requires further investigation.

Anticardiolipin antibodies, a disease marker for ischemic cerebrovascular events in a younger patient population?

The prevalence of anticardiolipin antibodies (ACLA) in sera of 49 patients having had their first TIA or ischemic stroke before 50 years of age was studied using a solid phase enzyme immunosorbent assay (ELISA). Five patients had IgM antibodies, eight had IgG, and three had antibodies belonging to both classes. Although ACLA were detected in 32% of patients (95% confidence interval [CI] 19-45%), the ACLA positive group did not differ with respect to clinical characteristics and distribution of major stroke risk factor frequency from the ACLA negative group. Further investigations are needed to establish the role of ACLA in the pathogenesis of ischemic cerebrovascular diseases.