Optimisation of individual cardiovascular risk assessment in a German coronary artery disease cohort using a commercial test for genetic polymorphisms - a pilot study

BACKGROUND AND AIMS

Assessment of cardiovascular risk using established risk scores such as ESC SCORE2 or PROCAM insufficiently emphasise the role of genetic factors. We hypothesise that commercially available genetic assays may provide additional information on hereditary cardiovascular risk in a timely and cost-efficient manner.

METHODS

In a cohort of 51 patients treated for coronary artery disease (CAD) at University Hospital Heidelberg, Germany, a subgroup of patients with "unstable" CAD (i.e. recurrent acute coronary syndrome) was identified and compared to patients with "stable" disease (i.e. chronic coronary syndrome). Gene array analysis using a commercial assay for 15 potentially pathogenic polymorphisms revealed our cohort's genetic risk profile regarding atherosclerotic/thromboembolic events. Improvement of cardiovascular risk assessment based on established risk scores was analysed using net reclassification, logistic regression and receiver operating characteristic (ROC) analysis.

RESULTS

Discriminatory capacity of traditional risk scores such as SCORE2 or PROCAM with regard to stable and unstable CAD groups was poor (ROC AUC <0.5). Patients with "unstable" CAD exhibited a significantly increased frequency of pathogenic eNOS 894 T and MTHFR 1298 C polymorphisms compared to "stable" CAD patients, and information on these polymorphisms individually as well as combinations with additional polymorphisms included in the assay such as ACE D/D or PAI-1 5 G variants markedly improved risk prediction compared to SCORE2/PROCAM alone (ROC AUC ≥0.75).

CONCLUSION

Commercially available assays for genetic polymorphisms may provide valuable information on individual genetic cardiovascular risk, potentially guiding future primary and/or secondary preventative therapies for coronary artery disease.

Identification of Specific Coronary Artery Disease Phenotypes Implicating Differential Pathophysiologies

Background and Aims

The roles of multiple risk factors of coronary artery disease (CAD) are well established. Commonly, CAD is considered as a single disease entity. We wish to examine whether coronary angiography allows to identify distinct CAD phenotypes associated with major risk factors and differences in prognosis.

Methods

In a cohort of 4,344 patients undergoing coronary angiography at Heidelberg University Hospital between 2014 and 2016, cluster analysis of angiographic reports identified subgroups with similar patterns of spatial distribution of high-grade stenoses. Clusters were independently confirmed in 3,129 patients from the LURIC study.

Results

Four clusters were identified: cluster one lacking critical stenoses comprised the highest percentage of women with the lowest cardiovascular risk. Patients in cluster two exhibiting high-grade stenosis of the proximal RCA had a high prevalence of the metabolic syndrome, and showed the highest levels of inflammatory biomarkers. Cluster three with predominant proximal LAD stenosis frequently presented with acute coronary syndrome and elevated troponin levels. Cluster four with high-grade stenoses throughout had the oldest patients with the highest overall cardiovascular risk. All-cause and cardiovascular mortality differed significantly between the clusters.

Conclusions

We identified four phenotypic subgroups of CAD bearing distinct demographic and biochemical characteristics with differences in prognosis, which may indicate multiple disease entities currently summarized as CAD.

Functional association of a CD40 gene single-nucleotide polymorphism with the pathogenesis of coronary heart disease

AIMS

Endothelial dysfunction is a major contributor to the pathogenesis of atherosclerosis. CD40-CD40 ligand interactions confer a pro-inflammatory phenotype to endothelial cells (ECs). Recently, a thymine to cytosine transition (-1T>C) in the Kozak sequence of the CD40 gene (rs1883832) has been associated with coronary heart disease (CHD) in an Asian population. As there are no reports yet regarding its role in other ethnic groups, this study determines if the -1T>C single-nucleotide polymorphism (SNP) could be a risk factor for CHD in Caucasians by performing an association study and elucidates its functional consequence in cultured ECs.

METHODS AND RESULTS

Molecular and biochemical techniques, cell adhesion assays were used for genotype-stratified human EC characterization. SNP distribution in Caucasians was examined in a hospital-based case-control CHD study and serum levels of soluble CD40 (sCD40) were quantified by ELISA. The SNP in the CD40 gene affected baseline CD40 protein abundance on ECs. There was a genotype-dependent difference in CD40-mediated expression of pro-inflammatory genes. Monocyte adhesion was highest on the surface of cells homozygous for the C allele. Homozygosity for the C allele was associated with significant 2.32-fold higher odds of developing CHD as compared to TT genotype carriers. sCD40 plasma levels were genotype-dependently elevated in CHD patients, indicating a possible prognostic value.

CONCLUSION

The C allele of the CD40 SNP provokes a pro-inflammatory EC phenotype, compensated by an enhanced CD40 shedding to neutralize excess CD40 ligand. Homozygosity for the C allele is the cause for a genetic susceptibility to atherosclerosis and its sequelae.

15-Deoxy-Δ12,14-Prostaglandin J 2 Reinforces the Anti-Inflammatory Capacity of Endothelial Cells With a Genetically Determined NO Deficit

Rationale:

Fluid shear stress (FSS) maintains NOS-3 (endothelial NO synthase) expression. Homozygosity for the C variant of the T-786C single-nucleotide polymorphism of the NOS3 gene, which solely exists in humans, renders the gene less sensitive to FSS, resulting in a reduced endothelial cell (EC) capacity to generate NO. Decreased bioavailability of NO in the arterial vessel wall facilitates atherosclerosis. Consequently, individuals homozygous for the C variant have an increased risk for coronary heart disease (CHD).

Objective:

At least 2 compensatory mechanisms seem to minimize the deleterious effects of this single-nucleotide polymorphism in affected individuals, one of which is characterized herein.

Methods and Results:

Human genotyped umbilical vein ECs and THP-1 monocytes were used to investigate the role of 15-deoxy-Δ12,14-prostaglandin J 2 (15d-PGJ 2 ) in vitro. Its concentration in plasma samples from genotyped patients with CHD and age-matched CHD-free controls was determined using quantitative ultraperformance LC-MS/MS. Exposure of human ECs to FSS effectively reduced monocyte transmigration particularly through monolayers of CC-genotype ECs. Primarily in CC-genotype ECs, FSS elicited a marked rise in COX (cyclooxygenase)-2 and L-PGDS (lipocalin-type prostaglandin D synthase) expression, which appeared to be NO sensitive, and provoked a significant release of 15d-PGJ 2 over baseline. Exogenous 15d-PGJ 2 significantly reduced monocyte transmigration and exerted a pronounced anti-inflammatory effect on the transmigrated monocytes by downregulating, for example, transcription of the IL (interleukin)-1β gene ( IL1B ). Reporter gene analyses verified that this effect is due to binding of Nrf2 (nuclear factor [erythroid-derived 2]–like 2) to 2 AREs (antioxidant response elements) in the proximal IL1B promoter. In patients with CHD, 15d-PGJ 2 plasma levels were significantly upregulated compared with age-matched CHD-free controls, suggesting that this powerful anti-inflammatory prostanoid is part of an endogenous defence mechanism to counteract CHD.

Conclusions:

Despite a reduced capacity to form NO, CC-genotype ECs maintain a robust anti-inflammatory phenotype through an enhanced FSS-dependent release of 15d-PGJ 2 .

CXCL4-induced macrophages in human atherosclerosis

Atherosclerosis is considered an inflammatory disease of the arterial wall. Monocytes and monocyte-derived cells (most often termed macrophages) play an essential role in the formation of atherosclerotic lesions, as they take up lipids leading to subsequent foam cell formation accompanied by release of pro-inflammatory cytokines. Similarly, platelets have been discovered to represent an important cell type mediating inflammatory and immune processes in atherogenesis, mainly by secreting chemokines, which are stored in the platelets' alpha granules, upon platelet activation. Therefore, the interaction between monocyte-derived cells and platelets is of exceptional importance. In this review, we specifically focus on the chemokine (platelet factor-4, PF4) and its effects on monocytes and monocyte-derived cells. By formation of heterodimers dimers and -oligomers with CCL5, CXCL4 induces binding of monocytes cells to endothelial cell and thereby promotes diapedesis of monocytes into the subendothelial space. CXCL4 also affects the differentiation of monocytes as it induces a specific macrophage phenotype, which we suggested to term "M4". For example, CXCL4-induced macrophages irreversibly lose the hemoglobin-haptoglobin scavenger receptor CD163. The combination of CD68, S100A8, and MMP7 turned out to reliably identify M4 macrophages both in vitro and in vivo within atherosclerotic lesions. In human atherosclerotic plaques, M4 macrophages are predominantly present in the adventitia and the intima and their prevalence is associated with plaque instability suggesting that they are a marker of pro-inflammatory activity. Overall, CXCL4-induced M4 macrophages may represent a target for diagnostic and therapeutic interventions in human atherosclerotic disease.

Adventitial tertiary lymphoid organ classification in human atherosclerosis

BACKGROUND

Atherosclerosis is a chronic inflammatory disease of the arterial wall. Adjacent to lamina intima lesion progression, a cellular compound develops in the lamina adventitia, defined as tertiary lymphoid organs (TLO) in mice. But in human system, it remains unknown whether these adventitial cellular accumulations represent these highly organized immunological structures.

PATIENTS AND METHODS

In this study, we investigated whether the adventitial cellular compounds represent TLOs in 72 human coronary artery samples by immunoenzyme staining.

RESULTS

The study showed that the adventitial cellular compound partly represented TLOs in human coronary arteries affected by atherogenesis in patients suffering from ischemic heart disease (56%) or a fatal myocardial infarction (100%), but not dilated cardiomyopathy. In addition, we established a classification for human TLOs, stage I-III, and showed that all stages were present in diseased coronary arteries. The stage of TLOs highly correlated with lesion size as well as plaque instability and rupture, and all patients with a myocardial infarction had stage III. Additionally, there were cellular infiltration and destruction of the lamina media, which were restricted to TLOs next to ruptured plaques in patients with a fatal myocardial infarction.

CONCLUSIONS

TLOs are present in patients with a coronary artery disease and highly correlated with lesion size, plaque instability, and rupture. Further studies are needed to investigate whether TLOs might be a specific diagnostic and drug target to modify plaque instability/rupture.

The influence of surgical technique on early posttransplant atrial fibrillation - comparison of biatrial, bicaval, and total orthotopic heart transplantation

PURPOSE

Early posttransplant atrial fibrillation (AF) has been associated with worse clinical outcomes after heart transplantation (HTX). The type of surgical technique may constitute a relevant risk factor for AF.

PATIENTS AND METHODS

This retrospective single-center study included 530 adult patients. Patients were stratified by surgical technique (biatrial, bicaval, or total orthotopic HTX) and early posttransplant heart rhythm (AF or sinus rhythm). Univariate and multivariate analyses were performed to evaluate risk factors for AF.

RESULTS

A total of 161 patients received biatrial HTX (30.4%), 115 bicaval HTX (21.7%), and 254 total orthotopic HTX (47.9%). Sixty-one of 530 patients developed early posttransplant AF (11.5%). Patients with AF showed a statistically inferior 5-year survival compared to those with sinus rhythm (P<0.0001). Total orthotopic HTX had the lowest rate of AF (total orthotopic HTX [6.3%], bicaval HTX [14.8%], biatrial HTX [17.4%], P=0.0012). Multivariate analysis showed pretransplant valvular heart disease (P=0.0372), posttransplant enlarged left atrium (P=0.0066), posttransplant mitral regurgitation (P=0.0370), and non-total orthotopic HTX (P=0.0112) as risk factors for AF.

CONCLUSION

Early posttransplant AF was associated with increased mortality (P<0.0001). Total orthotopic HTX showed the lowest rate of AF compared to biatrial or bicaval HTX (P=0.0012).

Histopathological assessment of calcification and inflammation of calcific aortic valves from patients with and without diabetes mellitus

BACKGROUND

Calcific aortic valve disease (CAVD) is the most common valvular heart disease and likely evolves from inflammatory pre-conditions in the valve. Type II diabetes mellitus (DMII) has been associated with pathogenesis of CAVD, however, the mechanism initiating CAVD in DMII is not well understood and the human valve pathology in DMII has not been described. We therefore performed quantitative histological analyses of aortic valves of CAVD patients with and without DMII.

METHODS

CAVD human aortic valves (n=45) obtained after surgical valve replacement were examined macroscopically with gross measurements of calcified areas. Inflammation and calcification were assessed by immunohistochemistry and immunofluorescence staining.

RESULTS

Calcification was increased in diabetic patients according to gross measurements (p<0.01) and alizarin red staining (p=0.05). Early calcification markers, including Runx2 (p=0.02) and alkaline phosphatase (ALP, p=0.03) were significantly elevated in diabetic patients. Furthermore, in diabetic patients we found significantly increased expression of annexin II (p=0.04) and annexin V (p=0.04), both of which are thought to play a role in microcalcification formation via apoptosis or extracellular vesicle release. Macrophage numbers were comparable in both groups (p=0.41), while the expression of the pro-inflammatory protein S100A9 (p<0.01) was significantly decreased in diabetic individuals. Evaluation of lymphocytes revealed similar CD8 (p=0.45) and CD4 (p=0.92) T cell counts in diabetic and non-diabetic aortic valves.

CONCLUSION

Aortic valves from diabetic patients show more calcification, while inflammation is similar in both patient populations. Considering the generally accepted theory of an inflammation-dependent mechanism of calcification, these data suggest that in patients with CAVD requiring valve replacement, diabetic patients could be molecularly in a more advanced disease stage with a higher grade of mineralization than non-diabetic patients.

Long-term use of amiodarone before heart transplantation significantly reduces early post-transplant atrial fibrillation and is not associated with increased mortality after heart transplantation

Background

Amiodarone is a frequently used antiarrhythmic drug in patients with end-stage heart failure. Given its long half-life, pre-transplant use of amiodarone has been controversially discussed, with divergent results regarding morbidity and mortality after heart transplantation (HTX).

Aim

The aim of this study was to investigate the effects of long-term use of amiodarone before HTX on early post-transplant atrial fibrillation (AF) and mortality after HTX.

Methods

Five hundred and thirty patients (age ≥18 years) receiving HTX between June 1989 and December 2012 were included in this retrospective single-center study. Patients with long-term use of amiodarone before HTX (≥1 year) were compared to those without long-term use (none or <1 year of amiodarone). Primary outcomes were early post-transplant AF and mortality after HTX. The Kaplan–Meier estimator using log-rank tests was applied for freedom from early post-transplant AF and survival.

Results

Of the 530 patients, 74 (14.0%) received long-term amiodarone therapy, with a mean duration of 32.3±26.3 months. Mean daily dose was 223.0±75.0 mg. Indications included AF, Wolff–Parkinson–White syndrome, ventricular tachycardia, and ventricular fibrillation. Patients with long-term use of amiodarone before HTX had significantly lower rates of early post-transplant AF (P=0.0105). Further, Kaplan–Meier analysis of freedom from early post-transplant AF showed significantly lower rates of AF in this group (P=0.0123). There was no statistically significant difference between patients with and without long-term use of amiodarone prior to HTX in 1-year (P=0.8596), 2-year (P=0.8620), 5-year (P=0.2737), or overall follow-up mortality after HTX (P=0.1049). Moreover, Kaplan–Meier survival analysis showed no statistically significant difference in overall survival (P=0.1786).

Conclusion

Long-term use of amiodarone in patients before HTX significantly reduces early post-transplant AF and is not associated with increased mortality after HTX.

Differential regulation of aldose reductase expression during macrophage polarization depends on hyperglycemia

Aldose reductase (AR; gene AKR1B1) is the rate-limiting enzyme of the polyol pathway and has been associated with diabetes and atherosclerosis. Here, we sought to identify the mechanisms underlying differential AR expression in human atherosclerotic plaque macrophages. In vitro, M1-polarized human monocyte-derived macrophages expressed significantly higher levels of AKR1B1 mRNA and AR protein compared with M2-polarized macrophages. AR activity was significantly higher in M1 macrophages. AKR1B1 mRNA expression correlated positively with the M1 marker TNF(r = 0.430,P = 0.006) and negatively with the M2 marker MRC1 (r = -0.443,P = 0.044). Increased AR expression in M1 macrophages depended on hyperglycemia. Concomitantly, expression of SLC2A1 (coding for the Glc transporter GLUT-1) was significantly higher in M1 than in M2 macrophages. Pharmacological inhibition of GLUT-1 using STF-32 completely abrogated Glc-induced AR up-regulation in M1 macrophages. When analyzing AR expression in post-mortem coronary artery plaque macrophages, a history of diabetes was associated with a significantly increased proportion of CD68(+)AR(++)macrophages, supporting the in vivo relevance of our in vitro findings. We demonstrate that the phenotype of atherosclerotic plaque macrophages may be affected by cardiovascular risk factors such as hyperglycemia. Our data illustrate the complex interplay between systemic and local factors in atherogenesis.

CXCL4 Plasma Levels Are Not Associated with the Extent of Coronary Artery Disease or with Coronary Plaque Morphology

BACKGROUND

CXCL4 is a platelet chemokine released at micromolar concentrations upon platelet activation. CXCL4 has been shown to promote atherogenesis by various mechanisms. However, data on CXCL4 plasma levels in patients with coronary artery disease are largely inconclusive. Computed coronary artery angiography (CCTA) represents an excellent tool to quantify and characterize coronary atherosclerotic plaques. We hypothesized that increased CXCL4 plasma levels may be associated with features of plaque instability resulting in adverse cardiovascular events. Specifically, we sought to determine whether CXCL4 levels are correlated with specific features of coronary artery disease including (1) plaque volume, (2) calcium score, (3) degree of stenosis, or (4) vascular remodeling.

METHODS AND RESULTS

CXCL4 plasma levels were measured by ELISA in 217 patients undergoing CCTA for suspected CAD (mean age 64.2 ± 9.4 years, 107 (49.3%) male). Mean CXCL4 plasma levels were 12.5 ± 4.6 ng/mL. There was no significant correlation between CXCL4 levels and any clinical or demographic parameters including cardiovascular risk factors. CXCL4 plasma levels did not differ between patient with or without coronary artery disease (CAD: 12.5 ± 4.5 ng/ml, no CAD: 12.5 ± 4.8 ng/ml). Neither univariate nor multivariate analysis showed an association between CXCL4 levels and plaque volume, total calcium score, degree of stenosis, or vascular remodeling. Subgroup analysis of patients with CAD as confirmed by CCTA did not show any association of CXCL4 levels with the extent of CAD.

CONCLUSIONS

While CXCL4 may be present and active within the arterial wall, local increase of CXCL4 may not translate into systemically elevated CXCL4 levels. Further studies will have to test whether CXCL4 may still represent a suitable therapeutic target in human atherosclerosis.

Prevalence of M4 macrophages within human coronary atherosclerotic plaques is associated with features of plaque instability

BACKGROUND

The platelet chemokine CXCL4 induces monocyte differentiation resulting in a macrophage phenotype called "M4", which co-expresses CD68, MMP7, and S100A8. We hypothesized that M4 macrophages are associated with plaque destabilization.

METHODS

Atherosclerotic arteries were obtained from explanted hearts of patients with severe coronary artery disease (CAD, n = 32) and of patients with dilated cardiomyopathy and no or mild CAD (controls, n = 19). Coronary arteries were stained with H&E, and immuno-fluorescence was performed against CD68, MMP7, and S100A8.

RESULTS

Both CD68(+) macrophages representing the entire macrophage population and MMP7(+)S100A8(+)CD68(+) M4 macrophages could be reproducibly identified within all arterial layers. The average proportion of the M4 macrophage phenotype amongst all CD68(+) macrophages was 31.7 ± 16.2%. The highest number of M4 macrophages was found in the adventitia, followed by the intima. CD68(+) and M4 macrophage numbers were significantly higher in patients with severe CAD. The presence of M4 macrophages within the intima and the media was significantly associated with plaque instability as determined by Stary class. Multivariate analysis showed a highly significant contribution of cardiovascular risk factors (P = 0.008) to plaque instability, while only trends were observed for age (P = 0.060) and intimal prevalence of M4 macrophages (P = 0.098).

CONCLUSIONS

We demonstrate for the first time that M4 macrophages can be reproducibly found in coronary artery plaques. The prevalence of M4 macrophages is associated with indexes of plaque instability, most likely representing a surrogate marker of inflammatory activity. These findings suggest a pathogenetic role of M4 macrophages in vulnerable atherosclerotic plaques.

Advantageous effects of immunosuppression with tacrolimus in comparison with cyclosporine A regarding renal function in patients after heart transplantation

BACKGROUND

Nephrotoxicity is a serious adverse effect of calcineurin inhibitor therapy in patients after heart transplantation (HTX).

AIM

In this retrospective registry study, renal function within the first 2 years after HTX in patients receiving de novo calcineurin inhibitor treatment, that is, cyclosporine A (CSA) or tacrolimus (TAC), was analyzed. In a consecutive subgroup analysis, renal function in patients receiving conventional tacrolimus (CTAC) was compared with that of patients receiving extended-release tacrolimus (ETAC).

METHODS

Data from 150 HTX patients at Heidelberg Heart Transplantation Center were retrospectively analyzed. All patients were continuously receiving the primarily applied calcineurin inhibitor during the first 2 years after HTX and received follow-up care according to center practice.

RESULTS

Within the first 2 years after HTX, serum creatinine increased significantly in patients receiving CSA (P<0.0001), whereas in patients receiving TAC, change of serum creatinine was not statistically significant (P=not statistically significant [ns]). McNemar's test detected a significant accumulation of patients with deterioration of renal function in the first half year after HTX among patients receiving CSA (P=0.0004). In patients receiving TAC, no significant accumulation of patients with deterioration of renal function during the first 2 years after HTX was detectable (all P=ns). Direct comparison of patients receiving CTAC versus those receiving ETAC detected no significant differences regarding renal function between patients primarily receiving CTAC or ETAC treatment during study period (all P=ns).

CONCLUSION

CSA is associated with a more pronounced deterioration of renal function, especially in the first 6 months after HTX, in comparison with patients receiving TAC as baseline immunosuppressive therapy.

Analysis of malignancies in patients after heart transplantation with subsequent immunosuppressive therapy

Objective

The aim of this study was to analyze the distribution of malignancies in patients after heart transplantation (HTX) and to evaluate the risk factors including immunosuppressive therapy with regard to the development of malignancies and survival. Special emphasis was placed on the effects of a mammalian target of rapamycin (mTOR) containing immunosuppressive regimen.

Methods

A total of 381 patients (age ≥18 years) receiving HTX were included in the present analysis. All patients were followed-up at the University of Heidelberg Heart Center, Heidelberg, Germany. Data were retrieved from the Heidelberg Registry for Heart Transplantation being collected between 1989 and 2014. According to center standard, all patients received induction therapy with anti-thymocyte globulin guided by T-cell monitoring since 1994. The initial immunosuppressive regimen consisting of cyclosporine A (CsA) and azathioprine (AZA) was replaced by CsA and mycophenolate mofetil (MMF) in 2001 and by tacrolimus (TAC) and MMF in 2006. Additionally, mTOR inhibitors (everolimus/sirolimus) were applied since 2003.

Results

Mean recipient age at HTX was 51.2±10.5 years and the mean follow-up period after HTX was 9.7±5.9 years. During follow-up, 130 patients developed a neoplasm (34.1% of total). Subgroup analysis revealed 58 patients with cutaneous malignancy only (15.2%), 56 patients with noncutaneous malignancy only (14.7%), and 16 patients with both cutaneous and noncutaneous malignancy (4.2%). Statistically significant risk factors associated with an increased risk of malignancy after HTX were older age (P<0.0001), male recipients (P=0.0008), dyslipidemia (P=0.0263), diabetes mellitus (P=0.0003), renal insufficiency (P=0.0247), and >1 treated rejection episode (TRE) in the first year after HTX (P=0.0091). Administration of CsA (P=0.0195), AZA (P=0.0008), or steroids (P=0.0018) for >1 year after HTX was associated with increased development of malignancy, whereas administration of MMF (P<0.0001) or mTOR inhibitors (P<0.0001) was associated with a lower risk for development of malignancy. Additionally, 5-year follow-up of cutaneous malignancy recurrence (P=0.0065) and noncutaneous malignancy mortality (P=0.0011) was significantly lower in patients receiving an mTOR inhibitor containing therapy after the development of a malignancy.

Conclusion

This study highlights the complexity of risk factors including immunosuppression with regard to the development of malignancies after HTX. mTOR-inhibitor-based immunosuppression is associated with a better outcome after HTX, particularly in cases with noncutaneous malignancy.

CCL19 and CCL21 modulate the inflammatory milieu in atherosclerotic lesions

Despite advances in the pharmacologic and interventional treatment of coronary artery disease, atherosclerosis remains the leading cause of death worldwide. Atherosclerosis is a chronic inflammatory disease, and elevated expression of CCL19 and CCL21 has been observed in ruptured lesions of coronary arteries of patients with myocardial infarction and carotid plaques of patients with ischemic symptoms, as well as in plasma of coronary artery disease patients. However, the exact role of CCL19 and CCL21 in atherosclerosis remains unknown. In order to identify CCL19 and CCL21 as a novel therapeutic target, we performed bone marrow transplantation as an immunomodulatory treatment concept. Bone marrow of plt/plt mice (lacking CCL19 and CCL21-Ser) was transplanted into atherogenic Ldlr(-/-) mice. The study demonstrated a significantly increased inflammatory cellular infiltration into the lesions of plt/plt/Ldlr(-/-) mice versus controls. Although the level of chemoattraction was increased, messenger ribonucleic acid and protein levels in thoracic aorta and serum of several proinflammatory cytokines (TNFα, IFNγ, IL-6, IL-12, and IL-17) were significantly reduced in plt/plt/Ldlr(-/-) versus control mice. Increased influx, accompanied by reduced activation of leukocytes in atherosclerotic lesion, was accompanied by increased plaque stability but unchanged lesion development. In conclusion, modulation of the chemokines CCL19 and CCL21 represents a potent immunoregulatory treatment approach, and thus represents a novel therapeutic target to stabilize atherosclerotic lesions.

Inflammatory therapeutic targets in coronary atherosclerosis-from molecular biology to clinical application

Atherosclerosis is the leading cause of death worldwide. Over the past two decades, it has been clearly recognized that atherosclerosis is an inflammatory disease of the arterial wall. Accumulating data from animal experiments have supported this hypothesis, however, clinical applications making use of this knowledge remain scarce. In spite of optimal interventional and medical therapy, the risk for recurrent myocardial infarction remains by about 20% over 3 years after acute coronary syndromes, novel therapies to prevent atherogenesis or treat atherosclerosis are urgently needed. This review summarizes selected potential molecular inflammatory targets that may be of clinical relevance. We also review recent and ongoing clinical trails that target inflammatory processes aiming at preventing adverse cardiovascular events. Overall, it seems surprising that translation of basic science into clinical practice has not been a great success. In conclusion, we propose to focus on specific efforts that promote translational science in order to improve outcome and prognosis of patients suffering from atherosclerosis.

IL-17A influences essential functions of the monocyte/macrophage lineage and is involved in advanced murine and human atherosclerosis

Atherosclerosis is a chronic inflammatory disease. Lesion progression is primarily mediated by cells of the monocyte/macrophage lineage. IL-17A is a proinflammatory cytokine, which modulates immune cell trafficking and is involved inflammation in (auto)immune and infectious diseases. But the role of IL-17A still remains controversial. In the current study, we investigated effects of IL-17A on advanced murine and human atherosclerosis, the common disease phenotype in clinical care. The 26-wk-old apolipoprotein E-deficient mice were fed a standard chow diet and treated either with IL-17A mAb (n = 15) or irrelevant Ig (n = 10) for 16 wk. Furthermore, essential mechanisms of IL-17A in atherogenesis were studied in vitro. Inhibition of IL-17A markedly prevented atherosclerotic lesion progression (p = 0.001) by reducing inflammatory burden and cellular infiltration (p = 0.01) and improved lesion stability (p = 0.01). In vitro experiments showed that IL-17A plays a role in chemoattractance, monocyte adhesion, and sensitization of APCs toward pathogen-derived TLR4 ligands. Also, IL-17A induced a unique transcriptome pattern in monocyte-derived macrophages distinct from known macrophage types. Stimulation of human carotid plaque tissue ex vivo with IL-17A induced a proinflammatory milieu and upregulation of molecules expressed by the IL-17A-induced macrophage subtype. In this study, we show that functional blockade of IL-17A prevents atherosclerotic lesion progression and induces plaque stabilization in advanced lesions in apolipoprotein E-deficient mice. The underlying mechanisms involve reduced inflammation and distinct effects of IL-17A on monocyte/macrophage lineage. In addition, translational experiments underline the relevance for the human system.

Superior rejection profile during the first 24 months after heart transplantation under tacrolimus as baseline immunosuppressive regimen

Background

The use of tacrolimus (TAC) in patients after heart transplantation (HTX) has increased over the last few years.

Aim

In this retrospective study, we evaluated the effects of a TAC (conventional and extended-release TAC)-based immunosuppressive therapy regarding rejection profile in comparison to a cyclosporine A (CSA)-based regimen in patients after HTX.

Methods

The data of 233 patients who underwent HTX at the Heidelberg Heart Transplantation Center from May 1998 until November 2010 were retrospectively analyzed. Primary immunosuppressive therapy was changed from a CSA (n=114) to a TAC (n=119)-based regimen in February 2006 according to center routine. Follow-up period was 2 years post-HTX. Primary endpoint was time to first biopsy-proven rejection requiring therapy. In all patients, routine follow-up at the Heidelberg Heart Transplantation Center was mandatory.

Results

Multivariate risk factor analysis regarding time to first rejection episode showed no statistically significant differences regarding recipient age, donor age, recipient sex, donor sex, sex mismatch, ischemic time, and diagnosis leading to HTX between the two groups (all P= not statistically significant). Time to first biopsy-proven rejection was significantly longer in the TAC group (intention-to-treat analysis, n=233, log-rank test P<0.0001; per-protocol analysis, n=150, log-rank test P=0.0003). In patients who underwent a change of primary immunosuppression (n=49), a significantly longer time to first biopsy-proven rejection was also found in the primary TAC subgroup (log-rank test P=0.0297). Further subgroup analysis in the TAC subgroups showed no statistically significant differences in time to biopsy-proven rejection under extended-release TAC compared to conventional TAC (intention-to-treat analysis, log-rank test P=0.1736).

Conclusion

Our study demonstrated that a TAC-based primary immunosuppressive therapy is superior to a CSA-based immunosuppressive regimen in patients after HTX regarding time to first biopsy-proven rejection.

Adventitial inflammation and its interaction with intimal atherosclerotic lesions

The presence of adventitial inflammation in correlation with atherosclerotic lesions has been recognized for decades. In the last years, several studies have investigated the relevance and impact of adventitial inflammation on atherogenesis. In the abdominal aorta of elderly Apoe^−/− mice, adventitial inflammatory structures were characterized as organized ectopic lymphoid tissue, and therefore termed adventitial tertiary lymphoid organs (ATLOs). These ATLOs possess similarities in development, structure and function to secondary lymphoid organs. A crosstalk between intimal atherosclerotic lesions and ATLOs has been suggested, and several studies could demonstrate a potential role for medial vascular smooth muscle cells in this process. We here review the development, phenotypic characteristics, and function of ATLOs in atherosclerosis. Furthermore, we discuss the possible role of medial vascular smooth muscle cells and their interaction between plaque and ATLOs.

Impact of the reduction of calcineurin inhibitors on renal function in heart transplant patients: a systematic review and meta-analysis

AIMS

Calcineurin inhibitors (CNIs) taken after heart transplantation lead to excellent short-term outcomes, but long-term use may cause chronic nephrotoxicity. Our aim was to identify, appraise, select and analyse all high-quality research evidence relevant to the question of the clinical impact of CNI-sparing strategies in heart transplant patients.

METHODS

We carried out a systematic review and meta-analysis of randomized controlled trials on CNI reduction in heart transplant recipients. Primary outcomes were kidney function and acute rejection after 1 year. Secondary outcomes included graft loss, all-cause mortality and adverse events.

RESULTS

Eight open-label studies were included, with 723 patients (four tested de novo CNI reduction and four maintenance CNI reduction). Calcineurin inhibitor reduction did not improve creatinine clearance at 12 months 5.46 [-1.17, 12.03] P = 0.32 I(2)  = 65.4%. Acute rejection at 12 months (55/360 vs. 52/332), mortality (18/301 vs. 15/270) and adverse event rates (55/294 vs. 52/281) did not differ between the low-CNI and standard-CNI groups. There was significant benefit on creatinine clearance in patients with impaired renal function at 6 months [+12.23 (+5.26, +18.82) ml min(-1) , P = 0.0003] and at 12 months 4.63 [-4.55, 13.82] P = 0.32 I(2)  = 75%.

CONCLUSIONS

This meta-analysis did not demonstrate a favourable effect of CNI reduction on kidney function, but there was no increase in acute rejection. To provide a better analysis of the influence of CNI reduction patterns and associated treatments, a meta-analysis of individual patient data should be performed.

Inhibition of B7-1 (CD80) by RhuDex® reduces lipopolysaccharide-mediated inflammation in human atherosclerotic lesions

Background

Atherosclerosis is based on a chronic inflammatory process including the innate and adaptive immune response. Costimulatory molecules and their receptors provide decisive signals for antigen-specific cell activation. The contribution of B7-related pathways to atherosclerosis has hardly been explored.

Methods

In the present study, we investigated the contribution of B7-1 to inflammation and tissue injury in the human plaque microenvironment in order to identify possible target structures of future therapeutic agents ex vivo and in vitro.

Results

Carotid artery plaque stimulation with lipopolysaccharides (LPS) could be significantly inhibited by RhuDex^®, a specific inhibitor of the costimulatory molecule B7-1 ex vivo (P<0.001). Coculture of antigen-presenting cells with T-cells demonstrated that the inhibitory effects of RhuDex^® derived from reduced T-cell activation. In addition, incubation of monocytes/macrophages with LPS and RhuDex^® resulted in an inhibitory negative feedback on antigen-presenting cells. Signaling pathways affected by RhuDex^® seem to be nuclear transcription factor kappa B, activator protein-1, and extracellular signal-regulated kinase 1/2.

Conclusion

The present data support B7-1 alone as an important costimulatory molecule in the context of LPS-mediated inflammation in atherosclerotic lesions. Due to its marked inhibitory effects, RhuDex^® may be a useful therapy to modulate the inflammatory milieu in atherosclerosis.

A human ex vivo atherosclerotic plaque model to study lesion biology

Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic lesions. Mouse models are an important tool to investigate inflammatory processes in atherogenesis, but these models suffer from the phenotypic and functional differences between the murine and human immune system. In vitro cell experiments are used to specifically evaluate cell type-dependent changes caused by a substance of interest, but culture-dependent variations and the inability to analyze the influence of specific molecules in the context of the inflammatory compound in atherosclerotic lesions limit the impact of the results. In addition, measuring levels of a molecule of interest in human blood helps to further investigate its clinical relevance, but this represents systemic and not local inflammation. Therefore, we here describe a plaque culture model to study human atherosclerotic lesion biology ex vivo. In short, fresh plaques are obtained from patients undergoing endarterectomy or coronary artery bypass grafting and stored in RPMI medium on ice until usage. The specimens are cut into small pieces followed by random distribution into a 48-well plate, containing RPMI medium in addition to a substance of interest such as cytokines or chemokines alone or in combination for defined periods of time. After incubation, the plaque pieces can be shock frozen for mRNA isolation, embedded in Paraffin or OCT for immunohistochemistry staining or smashed and lysed for western blotting. Furthermore, cells may be isolated from the plaque for flow cytometry analysis. In addition, supernatants can be collected for protein measurement by ELISA. In conclusion, the presented ex vivo model opens the possibility to further study inflammatory lesional biology, which may result in identification of novel disease mechanisms and therapeutic targets.

CXCL4-induced plaque macrophages can be specifically identified by co-expression of MMP7+S100A8+ in vitro and in vivo

Macrophage heterogeneity in human atherosclerotic plaques has been recognized; however, markers for unequivocal identification of some subtypes are lacking. We found that the platelet chemokine CXCL4 induces a unique macrophage phenotype, which we proposed to call 'M4'. Here, we sought to identify suitable markers that identify M4 macrophages in vitro and in vivo. Using a stringent algorithm, we identified a set of potential markers from transcriptomic data derived from polarized macrophages. We specifically focused on matrix metalloproteinase (MMP)7 and S100A8, the co-expression of which has not been described in any macrophage type thus far. We found dose- and time-dependent MMP7 and S100A8 expression in M4 macrophages at the gene and protein levels. CXCL4-induced up-regulation of both MMP7 and S100A8 was curbed in the presence of heparin, which binds to CXCL4 and glycosaminoglycans, most likely representing the macrophage receptor for CXCL4. Immunofluorescence of post-mortem atherosclerotic coronary arteries identified CD68(+)MMP7(+), CD68(+)MMP7(-), CD68(+)S100A8(+) and CD68(+)S100A8(-) macrophages. A small proportion of MMP7(+)S100A8(+) macrophages most likely represent M4 macrophages. In summary, we have identified co-expression of MMP7 and S100A8 to be a marker combination exclusively found in M4 macrophages. This finding may allow further dissection of the role of M4 macrophages in atherosclerosis and other pathologic conditions.

Conversion to generic cyclosporine A in stable chronic patients after heart transplantation

Background

Cyclosporine A (CSA) is a narrow therapeutic index drug. Available CSA products differ in the constitution of their emulsion. To compare intra-individual differences after a conversion to a generic CSA, a retrospective single-center study was initiated.

Methods

Twenty adult stable chronic (>24 months post heart transplant) recipients were included in the present retrospective study. These patients were previously switched from Sandimmune Neoral® to the generic CSA (Equoral®) according to the patients’ preference during the clinical routine. Dose-normalized trough levels (DNL) and trough levels (C0) at 8 months, 4 months, and 2 weeks before the switch were retrospectively compared with the corresponding values at 2 weeks, 4 months, and 8 months after the switch to the generic CSA. Additionally, changes in the routine laboratory parameters, the number of treated rejection episodes, and the adherence to the CSA target levels were compared.

Results

The mean DNL (adapted to the daily CSA dose in mg) was 0.71±0.26 (ng/mL)/mg on Neoral therapy; on Equoral it was 0.68±0.23 (ng/mL)/mg, (P=0.38). In comparison to the CSA daily dose prior to the conversion, at postconversion, no significant changes of CSA daily dose were observed (Neoral 140.67±39.81 mg versus Equoral 134.58±41.61 mg; P=0.13). No rejection episodes requiring therapy occurred prior to or postconversion (P=0.99). Additionally, no statistically significant changes of routine laboratory parameters regarding the Modification of Diet in Renal Disease or hematological parameters were seen (all P=not significant). No adverse events after the conversion were observed.

Conclusion

This study in chronic and stable HTx patients demonstrated no statistically significant differences in the CSA DNL after a conversion to generic CSA (Equoral). The generic CSA was generally well-tolerated. We concluded that a conversion from Neoral to Equoral is safe and clinically feasible in this distinct patient population. However, multiple switches between different generic immunosuppressants must especially be avoided in the interest of patient safety, and close follow-up examinations must be warranted.

Heart rate reduction for 36 months with ivabradine reduces left ventricular mass in cardiac allograft recipients: a long-term follow-up study

Background

Due to graft denervation, sinus tachycardia is a common problem after heart transplantation, underlining the importance of heart rate control without peripheral effects. However, long-term data regarding the effects of ivabradine, a novel I_f channel antagonist, are limited in patients after heart transplantation.

Methods

In this follow-up analysis, the resting heart rate, left ventricular mass indexed to body surface area (LVMI), tolerability, and safety of ivabradine therapy were evaluated at baseline and after 36 months in 30 heart transplant recipients with symptomatic sinus tachycardia versus a matched control group.

Results

During the study period, ivabradine medication was stopped in three patients (10% of total). Further analysis was based on 27 patients with 36 months of drug intake. The mean patient age was 53.3±11.3 years and mean time after heart transplantation was 5.0±4.8 years. After 36 months, the mean ivabradine dose was 12.0±3.4 mg/day. Resting heart rate was reduced from 91.0±10.7 beats per minute before initiation of ivabradine therapy (ie, baseline) to 81.2±9.8 beats per minute at follow-up (P=0.0006). After 36 months of ivabradine therapy, a statistically significant reduction of LVMI was observed (104.3±22.7 g at baseline versus 93.4±18.4 g at follow-up, P=0.002). Hematologic, renal, and liver function parameters remained stable during ivabradine therapy. Except for a lower mycophenolate mofetil dose at follow-up (P=0.02), no statistically significant changes in immunosuppressive drug dosage or blood levels were detected. No phosphenes were observed during 36 months of ivabradine intake despite active inquiry.

Conclusion

In line with previously published 12-month data, heart rate reduction with ivabradine remained effective and safe in chronic stable patients after heart transplantation, and also during 36-month long-term follow-up. Further, a significant reduction of LVMI was observed only during ivabradine therapy. Therefore, ivabradine may have a sustained long-term beneficial effect with regard to left ventricular remodeling in heart transplant patients.

An in vitro model to study heterogeneity of human macrophage differentiation and polarization

Monocyte-derived macrophages represent an important cell type of the innate immune system. Mouse models studying macrophage biology suffer from the phenotypic and functional differences between murine and human monocyte-derived macrophages. Therefore, we here describe an in vitro model to generate and study primary human macrophages. Briefly, after density gradient centrifugation of peripheral blood drawn from a forearm vein, monocytes are isolated from peripheral blood mononuclear cells using negative magnetic bead isolation. These monocytes are then cultured for six days under specific conditions to induce different types of macrophage differentiation or polarization. The model is easy to use and circumvents the problems caused by species-specific differences between mouse and man. Furthermore, it is closer to the in vivo conditions than the use of immortalized cell lines. In conclusion, the model described here is suitable to study macrophage biology, identify disease mechanisms and novel therapeutic targets. Even though not fully replacing experiments with animals or human tissues obtained post mortem, the model described here allows identification and validation of disease mechanisms and therapeutic targets that may be highly relevant to various human diseases.

Effects of oral valganciclovir prophylaxis for cytomegalovirus infection in heart transplant patients

BACKGROUND

Cytomegalovirus (CMV) infection is a serious complication following heart transplantation. This study (June 2003-January 2010) retrospectively assessed the effects of oral valganciclovir prophylaxis in adult heart transplant recipients during the first year after transplantation.

METHODS

In patients with normal renal function, 900 mg of oral valganciclovir was administered twice daily for 14 days after heart transplant followed by 900 mg per day for following 6 months. In the event of renal insufficiency, valganciclovir was adjusted according to the manufacturer's recommendations. Antigenemia testing for pp65 antigen and simultaneous polymerase chain reaction (PCR) were used to document exposure to CMV. From 2003 to 2010, 146 patients (74.0% men) of mean age 50.7 ± 10.3 years at the time of heart transplant were included.

RESULTS

A total of 16 patients (11.0% of total, 75.0% male) had a positive pp65 and PCR result (ie, CMV infection) during the year following heart transplant; three of these patients had discontinued valganciclovir prophylaxis within the first 6 months following transplant because of leukopenia, including one patient developed CMV colitis. Two further patients developed CMV pneumonia during prophylactic valganciclovir therapy. Eight patients had positive pp65 and PCR tests in the 6-12 months after heart transplant following cessation of routine prophylaxis. One of these patients developed CMV pneumonia and another developed CMV colitis and CMV pneumonia. Thirty-seven of the 146 (25.3%) patients were CMV donor-seropositive/recipient-seronegative, and seven (18.9% of this subgroup) had a positive CMV test. In patients who were CMV donor-seropositive/recipient-seronegative, the risk of a positive CMV test (ie, CMV infection) was significantly elevated (P = 0.023).

CONCLUSION

CMV prophylaxis with oral valganciclovir for 6 months following heart transplant is clinically feasible. In line with previous studies, CMV donor-seropositive/recipient-seronegative patients have a significantly elevated risk of CMV infection. In patients who prematurely discontinue valganciclovir, close monitoring of CMV antigenemia appears warranted. No significantly elevated rate of CMV infection was observed after 6 months of valganciclovir prophylaxis.

Abstract 338: 90K Inhibits Human Macrophage Foam Cell Formation and Is Associated with Reduced Plaque Burden and Reduced Adverse Cardiovascular Events in Patients with Coronary Artery Disease

Objective: 90K (also known as galectin-3 binding protein) is a secreted protein that modulates inflammation in vivo. We hypothesized that 90K may affect atherosclerosis through its effects on macrophages.

Methods and results: In human primary macrophages, recombinant human 90K reduced gene and protein expression of the scavenger receptors CD36 and SR-A in a dose- and time-dependent manner. Accordingly, uptake of DiI-labeled acetylated (acLDL) or oxidized low density lipoprotein (oxLDL) was significantly reduced after pre-treatment with 90K. Oil red O staining confirmed 90K-dependent reduction of foam cell formation induced by oxLDL after 24 hours. 90K expression in macrophage-rich areas of human atherosclerotic plaques was confirmed by immunohistochemistry in post mortem coronary arteries. In 122 patients undergoing coronary angiography 90K plasma levels were measured by ELISA. Hereby, there was no significant difference between patients with (n=89) and without (n=33) coronary artery disease (CAD). However, 90K plasma levels were significantly lower in CAD patients with at least one coronary artery stenosis ≥50% (n=37) compared to those with lumen narrowing <50% (n=52, P=0.044). By measuring total coronary artery plaque volume by cardiac computed tomography angiography (CCTA) in 56 of these patients with angiographically confirmed CAD, we found an inverse correlation between plaque volume and 90K plasma levels (r=-0.318, P=0.018). This correlation remained significant after multivariate analysis taking into account established cardiovascular risk factors including high sensitivity C reactive protein. In an independent cohort of 77 patients with angiographically confirmed CAD, low 90K plasma levels were associated with increased incidence of adverse cardiovascular events (as defined by cardiovascular death, myocardial infarction, or stroke) within one year (P=0.007). Again, this correlation remained significant in a multivariate Cox proportional hazards regression analysis (P=0.039, hazard ratio 0.230, 95%-CI 0.097-0.935).

Conclusions: We propose a protective role of 90K in coronary artery disease. By modulating macrophage foam cell formation, 90K may reduce plaque growth and promote plaque stability preventing adverse cardiovascular events.

Macrophage Phenotype Modulation by CXCL4 in Atherosclerosis

During atherogenesis, blood monocytes transmigrate into the subendothelial space and differentiate toward macrophages and foam cells. The major driver of monocyte-macrophage differentiation is macrophage colony-stimulating factor (M-CSF). M-CSF-induced macrophages are important promoters of atherogenesis as demonstrated in M-CSF and M-CSF receptor knock out mice. However, M-CSF is not the only relevant promoter of macrophage differentiation. The platelet chemokine CXCL4 also prevents monocyte apoptosis and promotes macrophage differentiation in vitro. It is secreted from activated platelets and has effects on various cell types relevant in atherogenesis. Knocking out the Pf4 gene coding for CXCL4 in Apoe(-/-) mice leads to reduced atherogenesis. Thus, it seems likely that CXC4-induced macrophages may have specific pro-atherogenic capacities. We have studied CXC4-induced differentiation of human macrophages using gene chips, systems biology, and functional in vitro and ex vivo experiments. Our data indicate that CXCL4-induced macrophages are distinct from both their M-CSF-induced counterparts and other known macrophage polarizations like M1 macrophages (induced by lipopolysaccharide and interferon-gamma) or M2 macrophages (induced by interleukin-4). CXCL4-induced macrophages have distinct phenotypic and functional characteristics, e.g., the complete loss of the hemoglobin-haptoglobin (Hb-Hp) scavenger receptor CD163 which is necessary for effective hemoglobin clearance after plaque hemorrhage. Lack of CD163 is accompanied by the inability to upregulate the atheroprotective enzyme heme oxygenase-1 in response to Hb-Hp complexes. This review covers the current knowledge about CXCL4-induced macrophages. Based on their unique properties, we have suggested to call these macrophages "M4." CXCL4 may represent an important orchestrator of macrophage heterogeneity within atherosclerotic lesions. Further dissecting its effects on macrophage differentiation may help to identify novel therapeutic targets in atherogenesis.

PARP inhibition in atherosclerosis and its effects on dendritic cells, T cells and auto-antibody levels

Objective

Atherosclerosis is a chronic inflammatory process. Poly(ADP-ribose) polymerase-1 (PARP), a nuclear enzyme linked to DNA repair, has been shown to be involved in atherogenesis; however, the effects on dendritic cells, T cells and serum auto-antibody levels are not fully understood.

Methods

Male Apoe^-/- mice on a western diet were treated with the PARP inhibitor 1NO-1001 (n = 15), while the control group (n = 15) received 5% glucose solution for 10 weeks.

Results

Inhibition of PARP markedly reduced atherosclerotic lesion development (p = 0.001). Immunohistochemistry and mRNA analysis revealed a reduced inflammatory compound inside the lesion. Focusing on dendritic cells, INO-1001 reduced number of cells (p = 0.04), grade of activation, represented by I/12 (p = 0.04) and Cd83 (p = 0.03), and grade of attraction, represented by Mip3α (p = 0.02) in the plaque. Furthermore, INO-1001 decreased number of T lymphocyte (p = 0.003) in the lesion and grade of activation after stimulation with oxLDL in vitro. Moreover, serum IgM antibody levels to oxLDL were significantly lower in INO-1001 treated mice (p = 0.03).

Conclusions

Functional blockade of PARP by INO-1001 reduces atherosclerotic lesion development. The anti-atherogenic effect is beside already known mechanisms also moderated due to modulation of DC and T cell invasion and activation, DC attraction as well as IgM antibody levels to oxLDL.

Expression of IL-17A in human atherosclerotic lesions is associated with increased inflammation and plaque vulnerability

A chronic (auto)immune response is the critical mechanism in atherosclerosis. Interleukin-17A is a pivotal effector cytokine, which modulates immune cell trafficking and initiates inflammation in (auto)immune and infectious diseases. However, expression of IL-17A in the context of human atherosclerosis has hardly been explored. Carotid artery plaques were collected from 79 patients undergoing endarterectomy. Patients were grouped according to their symptomatic status (TIA, stroke), plaque morphology and medication. Quantitative RT-PCR was used to analyze tissue inflammation and immunohistochemistry to assess cellular source of IL-17A expression and lesion morphology. Carotid plaques from patients with ischemic symptoms were characterized by a highly activated inflammatory milieu including accumulation of T cells (p = 0.04) and expression of IL-6 and VCAM1 (p = 0.02, 0.01). Expression of IL-17A and its positive regulators IL-21 and IL-23 was present in atherosclerotic lesions, significantly upregulated in atheromas of symptomatic patients (p = 0.005, 0.004, 0.03), and expression of IL-17A and IL-21 showed a strong correlation (p = 0.002, r = 0.52). The cellular sources of lesional IL-17A expression are T cells, macrophages, B cells and plasma cells. Vulnerable/ruptured (complicated) plaques were significantly associated with IL-17A expression levels (p = 0.003). In addition, IL-17A showed a marked negative correlation with the potent anti-inflammatory/atheroprotective cytokine IL-10 (p = 0.0006, r = -0.46). Furthermore, treatment with a HMG-CoA reductase inhibitor or acetylsalicylic acid showed reduced levels of IL-21, IL-23 and VCAM1 (all p < 0.05), but did not influence IL-17A. The association of IL-17A with ischemic symptoms and vulnerable plaque characteristics suggests that the pro-inflammatory cytokine IL-17A may contribute to atherosclerosis und plaque instability.

CXC chemokine ligand 4 induces a unique transcriptome in monocyte-derived macrophages

In atherosclerotic arteries, blood monocytes differentiate to macrophages in the presence of growth factors, such as macrophage colony-stimulation factor (M-CSF), and chemokines, such as platelet factor 4 (CXCL4). To compare the gene expression signature of CXCL4-induced macrophages with M-CSF-induced macrophages or macrophages polarized with IFN-gamma/LPS (M1) or IL-4 (M2), we cultured primary human peripheral blood monocytes for 6 d. mRNA expression was measured by Affymetrix gene chips, and differences were analyzed by local pooled error test, profile of complex functionality, and gene set enrichment analysis. Three hundred seventy-five genes were differentially expressed between M-CSF- and CXCL4-induced macrophages; 206 of them overexpressed in CXCL4 macrophages coding for genes implicated in the inflammatory/immune response, Ag processing and presentation, and lipid metabolism. CXCL4-induced macrophages overexpressed some M1 and M2 genes and the corresponding cytokines at the protein level; however, their transcriptome clustered with neither M1 nor M2 transcriptomes. They almost completely lost the ability to phagocytose zymosan beads. Genes linked to atherosclerosis were not consistently upregulated or downregulated. Scavenger receptors showed lower and cholesterol efflux transporters showed higher expression in CXCL4- than M-CSF-induced macrophages, resulting in lower low-density lipoprotein content. We conclude that CXCL4 induces a unique macrophage transcriptome distinct from known macrophage types, defining a new macrophage differentiation that we propose to call M4.

CXCL4 downregulates the atheroprotective hemoglobin receptor CD163 in human macrophages

RATIONALE

CXCL4 is a platelet-derived chemokine that promotes macrophage differentiation from monocytes. Deletion of the PF4 gene that encodes CXCL4 reduces atherosclerotic lesions in ApoE(-/-) mice.

OBJECTIVE

We sought to study effects of CXCL4 on macrophage differentiation with possible relevance for atherogenesis.

METHODS AND RESULTS

Flow cytometry for expression of surface markers in macrophage colony-stimulating factor (M-CSF)- and CXCL4-induced macrophages demonstrated virtually complete absence of the hemoglobin scavenger receptor CD163 in CXCL4-induced macrophages. mRNA for CD163 was downregulated as early as 2 hours after CXCL4. CD163 protein reached a minimum after 3 days, which was not reversed by treatment of cells with M-CSF. The CXCL4 effect was entirely neutralized by heparin, which bound CXCL4 and prevented CXCL4 surface binding to monocytes. Pretreatment of cells with chlorate, which inhibits glycosaminoglycan synthesis, strongly inhibited CXCL4-dependent downregulation of CD163. Similar to recombinant CXCL4, releasate from human platelets also reduced CD163 expression. CXCL4-differentiated macrophages were unable to upregulate the atheroprotective enzyme heme oxygenase-1 at the RNA and protein level in response to hemoglobin-haptoglobin complexes. Immunofluorescence of human atherosclerotic plaques demonstrated presence of both CD68+CD163+ and CD68+CD163- macrophages. PF4 and CD163 gene expression within human atherosclerotic lesions were inversely correlated, supporting the in vivo relevance of CXCL4-induced downregulation of CD163.

CONCLUSIONS

CXCL4 may promote atherogenesis by suppressing CD163 in macrophages, which are then unable to upregulate the atheroprotective enzyme heme oxygenase-1 in response to hemoglobin.

Glycosylation in immune cell trafficking

Leukocyte recruitment encompasses cell adhesion and activation steps that enable circulating leukocytes to roll, arrest, and firmly adhere on the endothelial surface before they extravasate into distinct tissue locations. This complex sequence of events relies on adhesive interactions between surface structures on leukocytes and endothelial cells and also on signals generated during the cell-cell contacts. Cell surface glycans play a crucial role in leukocyte recruitment. Several glycosyltransferases such as alpha1,3 fucosyltransferases, alpha2,3 sialyltransferases, core 2 N-acetylglucosaminlytransferases, beta1,4 galactosyltransferases, and polypeptide N-acetylgalactosaminyltransferases have been implicated in the generation of functional selectin ligands that mediate leukocyte rolling via binding to selectins. Recent evidence also suggests a role of alpha2,3 sialylated carbohydrate determinants in triggering chemokine-mediated leukocyte arrest and influencing beta1 integrin function. The recent discovery of galectin- and siglec-dependent processes further emphasizes the significant role of glycans for the successful recruitment of leukocytes into tissues. Advancing the knowledge on glycan function into appropriate pathology models is likely to suggest interesting new therapeutic strategies in the treatment of immune- and inflammation-mediated diseases.

Platelet chemokines in vascular disease

Platelets are a rich source of different chemokines and express chemokine receptors. CXCL4 is highly abundant in platelets and involved in promoting monocyte arrest from rolling and monocyte differentiation to macrophages. CXCL4 can also associate with CCL5 and amplify its effect on monocytes. The megakaryocyte CXCL7 gene product is proteolytically cleaved into the strong neutrophil chemoattractant, NAP-2, which has also been implicated in repair cell homing to vascular lesions. Platelet adhesion can induce release of CCL2 and CXCL8 from endothelial cells. Conversely, the chemokines CCL17, CCL22, and CXCL12 made by other cells amplify platelet activation. Platelet chemokines enhance recruitment of various hematopoietic cells to the vascular wall, fostering processes such as neointima formation, atherosclerosis, and thrombosis, but also vessel repair and regeneration after vascular injury.

Upregulation of aldose reductase during foam cell formation as possible link among diabetes, hyperlipidemia, and atherosclerosis

OBJECTIVE

Aldose reductase (AR) is the rate-limiting enzyme of the polyol pathway. In diabetes, it is related to microvascular complications. We discovered AR expression in foam cells by gene chip screening and hypothesized that it may be relevant in atherosclerosis.

METHODS AND RESULTS

AR gene expression and activity were found to be increased in human blood monocyte-derived macrophages during foam cell formation induced by oxidized LDL (oxLDL, 100 microg/mL). AR activity as photometrically determined by NADPH consumption was effectively inhibited by the AR inhibitor epalrestat. oxLDL-dependent AR upregulation was further increased under hyperglycemic conditions (30 mmol/L D-glucose) as compared to osmotic control, suggesting a synergistic effect of hyperlipidemia and hyperglycemia. AR was also upregulated by 4-hydroxynonenal, a constituent of oxLDL. Upregulation was blocked by an antibody to CD36. AR inhibition resulted in reduction of oxLDL-induced intracellular oxidative stress as determined by 2'7'-dichlorofluoresceine diacetate (H2DCFDA) fluorescence, indicating that proinflammatory effects of oxLDL are partly mediated by AR. Immunohistochemistry showed AR expression in CD68+ human atherosclerotic plaque macrophages.

CONCLUSIONS

These data show that oxLDL-induced upregulation of AR in human macrophages is proinflammatory in foam cells and may represent a potential link among hyperlipidemia, atherosclerosis, and diabetes mellitus.

Induction of dendritic cell-like phenotype in macrophages during foam cell formation

Foam cell formation from monocyte-derived macrophages is a hallmark of atherosclerotic lesions. Aspects of this process can be recapitulated in vitro by exposing M-CSF-induced or platelet factor 4 (CXCL4)-induced macrophages to oxidized (ox) or minimally modified (mm) low density lipoprotein (LDL). We measured gene expression in peripheral blood mononuclear cells, monocytes, and macrophages treated with CXCL1 (GRO-α) or CCL2 (MCP-1), as well as foam cells induced by native LDL, mmLDL, or oxLDL using 22 Affymetrix gene chips. Using an advanced Bayesian error-pooling approach and a heterogeneous error model with a false discovery rate <0.05, we found 5,303 of 22,215 probe sets to be significantly regulated in at least one of the conditions. Among a subset of 917 candidate genes that were preselected for their known biological functions in macrophage foam-cell differentiation, we found that 290 genes met the above statistical criteria for significant differential expression patterns. While many expected genes were found to be upregulated by LDL and oxLDL, very few were induced by mmLDL. We also found induction of unexpected genes, most strikingly MHC-II and other dendritic cell markers such as CD11c. The gene expression patterns in response to oxLDL were similar in M-CSF-induced and CXCL4-induced macrophages. Our findings suggest that LDL and oxLDL, but not mmLDL, induce a dendritic cell-like phenotype in macrophages, suggesting that these cells may be able to present antigens and support an immune response.

IL-10 inhibits endothelium-dependent T cell costimulation by up-regulation of ILT3/4 in human vascular endothelial cells

Effects of IL-10 on endothelium-dependent T cell activation have not been investigated in detail. We confirm expression of the IL-10 receptor and effective signaling via STAT-3 in human umbilical vein endothelial cells (HUVEC). In CD4 T cell cocultures with HUVEC, pretreatment of endothelial cells with IL-10 resulted in significant dose-dependent inhibition of CD4 T cell proliferation, which also occurred when IL-10 was removed after pretreatment before starting cocultures. Th1/Th2 polarization of proliferated T cells, endothelial nitric oxide (NO), or IL-12 production were unchanged. However, IL-10 stimulation resulted in up-regulation of SOCS-3, a negative regulator of cytokine secretion, and induction of the inhibitory surface molecules immunoglobulin-like transcript 3 and 4 (ILT3/ILT4) in EC, potentially involving glucocorticoid-induced leucine zipper (GILZ). Addition of blocking antibodies against ILT3/ILT4 to EC/T cell cocultures resulted in nearly complete reestablishment of T cell proliferation. In contrast, addition of soluble ILT3 or overexpression of ILT3 in cocultures significantly reduced T cell proliferation. No induction of foxp3+ regulatory T cells was seen. In conclusion, the T cell costimulatory potential of human EC is markedly suppressed by IL-10 due to up-regulation of ILT3/ILT4, obviously not involving generation of Treg. This identifies a novel action of IL-10 in EC and a potential therapeutical target for local immunomodulation.

Mechanisms by which diabetes increases cardiovascular disease

Diabetes mellitus is one of the major risk factors for cardiovascular disease which is the leading cause of death in the U.S. Increasing prevalence of diabetes and diabetic atherosclerosis makes identification of molecular mechanisms by which diabetes promotes atherogenesis an important task. Targeting common pathways may ameliorate both diseases. This review focuses on well known as well as newly discovered mechanisms which may represent promising therapeutic targets.