Max Vikström

Increased prevalence of vulnerable atherosclerotic plaques and low levels of natural IgM antibodies against phosphorylcholine in patients with systemic lupus erythematosus.

IntroductionThe risk of cardiovascular disease (CVD) and atherosclerosis is reported to be increased in systemic lupus erythematosus (SLE). We recently reported a negative association between natural IgM-antibodies against phosphorylcholine (anti-PC) in the general population, high anti-PC levels leading to decreased atherosclerosis development and low levels to increased risk of CVD. Potential mechanisms include anti-inflammatory properties and inhibition of uptake of oxidized low density lipoprotein (LDL) in macrophages. The objective herein was to study atherosclerosis in SLE in detail and in relation to traditional and non-traditional risk factors.MethodsA total of 114 patients with SLE were compared with 122 age- and sex-matched population-based controls. Common carotid intima-media thickness (IMT), calculated intima-media area (cIMa) and plaque occurrence were determined by B-mode ultrasound as a surrogate measure of atherosclerosis. Plaques were graded according to echogenicity and grouped as 1 to 4, with 1 being echoluscent, and considered most vulnerable. Anti-PC was studied by ELISA.ResultsHypertension, triglycerides and insulin resistance (determined by homeostasis model assessment of insulin resistance) and C-reactive protein (CRP) were increased in SLE (P < 0.01) while smoking, LDL, high density lipoprotein (HDL) did not differ between groups. Low levels of anti-PC IgM (lowest tertile) were more common in SLE patients than in controls (P = 0.0022). IMT and cIMa did not differ significantly between groups. However, plaques were more often found in SLE patients (P = 0.029). Age, LDL and IgM anti-PC (lowest tertile) were independently associated with plaque occurrence in SLE. Further, in the left carotid arteries echoluscent plaques (grade 1) were more prevalent in SLE as compared to controls (P < 0.016).ConclusionsPlaque occurrence in the carotid arteries is increased in SLE and is independently associated with age, LDL and low anti-PC levels. Vulnerable plaques were more common in SLE. Anti-PC could be a novel risk marker also with a therapeutic potential in SLE.

Low levels of IgM antibodies to oxidized cardiolipin increase and high levels decrease risk of cardiovascular disease among 60-year olds: a prospective study

BackgroundAntibodies against cardiolipin (aCL) are associated with increased risk of cardiovascular disease (CVD). We here determine the role of antibodies against oxidized CL (aOxCL).MethodsOne third of sixty-year olds from the Stockholm County were screened (2039 men, 2193 women), where 211 incident CVD-cases and 633 age- and sex-matched controls were identified (5–7 year follow-up). Antibodies were determined by ELISA and uptake of oxLDL in macrophages by FACScan.ResultsIgM aOxCL was lower among CVD cases than controls (p=0.024). aOxCL-levels were divided in quartiles with the highest quartile set as the reference group. After adjustment for smoking, BMI, type II diabetes, hypercholesterolaemia and hypertension, an increased risk was determined in the lowest quartile of IgM aOxCL (OR: 1.80, CI: 1.12–2.91, p=0.0159); OR for men in the lowest quartile was 2.46 (CI 1.34–4.53, p=0.0037) for CVD and for stroke: 12.28 (CI: 1.48-101.77, p=0.02). IgG aOxCL levels did not differ between quartiles in CVD-risk. High levels of IgM aOxCL (reaching significance above 86th) and IgG aOxCL (above 95th percentile) were associated with decreased risk of CVD (OR: 0.485, CI: 0.283-0.829; p=0.0082 and OR: 0.23, CI: 0.07-0.69; p=0.0091). aCL were not associated with CVD. oxCL but not CL competed out uptake of OxLDL in macrophages, and aOxLDL recognized oxCL but not CL. In contrast to aCL, aOxCL was not dependent on co-factor Beta2-glycoprotein-I.ConclusionsaOxCL is a novel risk/protection marker for CVD, with therapeutic implications. OxCL competes with oxLDL for uptake in macrophages and the possibility that aOxCL inhibits such uptake by interfering with same or similar epitopes in oxCL and oxLDL should be further studied.

Variants in the coagulation factor 2 receptor (F2R) gene influence the risk of myocardial infarction in men through an interaction with interleukin 6 serum levels.

Thrombin-activated factor 2 receptor (F2R) links thrombosis to inflammation modulating interleukin (IL)6 synthesis. We have investigated the role of F2R genetic variants and their interaction with IL6 serum levels in the occurrence of myocardial infarction (MI) in the Stockholm Heart Epidemiology Program (SHEEP). Seven SNPs -1738 G/A, -506-/GGCCGCGGGAAGC (D/I), 2860 G/A, 2930 T/C, 9113 C/A, 9333 C/T and 120813 T/C within F2R locus were genotyped in the SHEEP (n=2,774). The C allele at position 2930 was associated with a slight reduction in MI risk in men. IL6 serum levels were higher in male cases carrying genotypes AA at the -1738 (p= 0.01) and GG at the 2860 loci (p= 0.03) and both alleles were found to differentially modulate IL6 serum levels in the context of selective haplotypes. High IL6 serum levels (>75(th) percentile), were independently associated with an increased risk of MI in men with an odds ratio (OR) (95% confidence interval [CI]) of 2.44 (1.72-3.46), (p=0.0016), but not in women ( OR 0.83 [95%CI 0.50-1.36], p=0.64). In the presence of high IL6 serum levels, the -1738A allele increased and the 2860A allele reduced the risk of MI (all p < or = 0.02). Consistently, the AG diplotype increased MI risk (OR 1.71 [95%CI 1.17-2.51], p=0.005). The -1738 and 2860 loci association with IL6 serum levels was replicated in men in the Stockholm Coronary Artery Risk Factor (SCARF) study (both p < or = 0.04). In the pooled data from the two populations, the A and G allele modulated the risk of MI in men with high IL6 serum levels (p < or = 0.03). Our results demonstrate that in men F2R genetic variants influence the risk of MI mainly through an interaction with IL6 serum levels.

Identification of the BCAR1-CFDP1-TMEM170A Locus as a Determinant of Carotid Intima-Media Thickness and Coronary Artery Disease Risk

Background—Carotid intima-media thickness (cIMT) is a widely accepted marker of subclinical atherosclerosis. To date, large-scale investigations of genetic determinants of cIMT are sparse. Methods and Results—To identify cIMT-associated genes and genetic variants, a discovery analysis using the Illumina 200K CardioMetabochip was conducted in 3430 subjects with detailed ultrasonographic determinations of cIMT from the IMPROVE (Carotid Intima Media Thickness [IMT] and IMT-Progression as Predictors of Vascular Events in a High Risk European Population) study. Segment-specific IMT measurements of common carotid, bifurcation, and internal carotid arteries, and composite IMT variables considering the whole carotid tree (IMTmean, IMTmax, and IMTmean-max), were analyzed. A replication stage investigating 42 single-nucleotide polymorphisms for association with common carotid IMT was undertaken in 5 independent European cohorts (total n=11 590). A locus on chromosome 16 (lead single-nucleotide polymorphism rs4888378, intronic in CFDP1) was associated with cIMT at significance levels passing multiple testing correction at both stages (array-wide significant discovery P=6.75×10−7 for IMTmax; replication P=7.24×10−6 for common cIMT; adjustments for sex, age, and population substructure where applicable; minor allele frequency 0.43 and 0.41, respectively). The protective minor allele was associated with lower carotid plaque score in a replication cohort (P=0.04, n=2120) and lower coronary artery disease risk in 2 case-control studies of subjects with European ancestry (odds ratio [95% confidence interval] 0.83 [0.77–0.90], P=6.53×10−6, n=13 591; and 0.95 [0.92–0.98], P=1.83×10−4, n=82 297, respectively). Queries of human biobank data sets revealed associations of rs4888378 with nearby gene expression in vascular tissues (n=126–138). Conclusions—This study identified rs4888378 in the BCAR1-CFDP1-TMEM170A locus as a novel genetic determinant of cIMT and coronary artery disease risk in individuals of European descent.

The Interaction between Coagulation Factor 2 Receptor and Interleukin 6 Haplotypes Increases the Risk of Myocardial Infarction in Men

The aim of the study was to investigate if the interaction between the coagulation factor 2 receptor (F2R) and the interleukin 6 (IL6) haplotypes modulates the risk of myocardial infarction (MI) in the Stockholm Heart Epidemiology Program (SHEEP). Seven SNPs at the F2R locus and three SNPs at the IL6 locus were genotyped. Haplotypes and haplotype pairs (IL6*F2R) were generated. A logistic regression analysis was performed to analyze the association of the haplotypes and haplotype pairs with the MI risk. Presence of an interaction between the two haplotypes in each haplotype pair was calculated using two different methods: the statistical, on a multiplicative scale, which includes the cross product of the two factors into the logistic regression model; the biological, on an additive scale, which evaluates the relative risk associated with the joint presence of both factors. The ratio between the observed and the predicted effect of the joint exposure, the synergy index (S), indicates the presence of a synergy (S>1) or of an antagonism (S<1). None of the haplotypes within the two loci was associated with the risk of MI. Out of 22 different haplotype pairs, the haplotype pair 17 GGG*ADGTCCT was associated with an increased risk of MI with an OR (95%CI) of 1.58 (1.05–2.41) (p = 0.02) in the crude and an OR of 1.72 (1.11–2.67) (p = 0.01) in the adjusted analysis. We observed the presence of an interaction on a multiplicative scale with an OR (95%CI) of 2.24 (1.27–3.95) (p = 0.005) and a slight interactive effect between the two haplotypes on an additive scale with an OR (95%CI) of 1.56 (1.02–2.37) (p = 0.03) and S of 1.66 (0.89–31). In conclusion, our results support the hypothesis that the interaction between these two functionally related genes may influence the risk of MI and suggest new mechanisms involved in the genetic susceptibility to MI.

Polyunsaturated Fat Intake Estimated by Circulating Biomarkers and Risk of Cardiovascular Disease and All-Cause Mortality in a Population-Based Cohort of 60-Year-Old Men and Women

Background— High intake of polyunsaturated fatty acids (PUFAs) may reduce the risk of cardiovascular disease (CVD) and mortality. Large, prospective studies including both sexes and circulating PUFAs as dietary biomarkers are needed. We investigated sex-specific associations of the major dietary PUFAs, eicosapentaenoic acid, docohexaenoic acid, linoleic acid, and &agr;-linolenic acid, with incident CVD and all-cause mortality in a population-based cohort. Methods and Results— PUFAs in serum cholesterol esters were measured at baseline in 60-year-old Swedish women (n=2193) and men (n=2039). With the use of national registers, 484 incident CVD events (294 men and 190 women) and 456 all-cause deaths (265 men and 191 women) were identified during follow-up (median, 14.5 years) in individuals without prior CVD at baseline. Associations of PUFAs with CVD and mortality were evaluated with Cox proportional hazard models. In multivariable-adjusted models, 1-SD increases in eicosapentaenoic acid and docohexaenoic acid were associated with lower risk of incident CVD among women (hazard ratio [HR], 0.79 [95% confidence interval (CI), 0.64–0.97] and 0.74 [95% CI, 0.61–0.89], respectively). &agr;-Linolenic acid was associated with moderately increased CVD risk in women (HR, 1.16; 95% CI, 1.02–1.32). Inverse associations with all-cause mortality were observed for eicosapentaenoic acid and docohexaenoic acid among all participants (HR, 0.81 [95% CI, 0.72–0.91] and 0.80 [95% CI, 0.72–0.89], respectively) and for linoleic acid in men (HR, 0.73; 95% CI, 0.64–0.83). Conclusions— Serum linoleic acid and very-long-chain n-3 PUFAs, partly reflecting vegetable oil and fish intake, respectively, were inversely associated with all-cause mortality. Inverse associations of eicosapentaenoic acid and docohexaenoic acid with incident CVD were observed only in women.

Interleukin-26 in Antibacterial Host Defense of Human Lungs. Effects on Neutrophil Mobilization

RATIONALE The role of the presumed Th17 cytokine IL-26 in antibacterial host defense of the lungs is not known. OBJECTIVES To characterize the role of IL-26 in antibacterial host defense of human lungs. METHODS Intrabronchial exposure of healthy volunteers to endotoxin and vehicle was performed during bronchoscopy and bronchoalveolar lavage (BAL) samples were harvested. Intracellular IL-26 was detected using immunocytochemistry and immunocytofluorescence. This IL-26 was also detected using flow cytometry, as was its receptor complex. Cytokines and phosphorylated signal transducer and activator of transcription (STAT) 1 plus STAT3 were quantified using ELISA. Gene expression was analyzed by real-time polymerase chain reaction and neutrophil migration was assessed in vitro. MEASUREMENTS AND MAIN RESULTS Extracellular IL-26 was detected in BAL samples without prior exposure in vivo and was markedly increased after endotoxin exposure. Alveolar macrophages displayed gene expression for, contained, and released IL-26. Th and cytotoxic T cells also contained IL-26. In the BAL samples, IL-26 concentrations and innate effector cells displayed a correlation. Recombinant IL-26 potentiated neutrophil chemotaxis induced by IL-8 and fMLP but decreased chemokinesis for neutrophils. Myeloperoxidase in conditioned media from neutrophils was decreased. The IL-26 receptor complex was detected in neutrophils and IL-26 decreased phosphorylated STAT3 in these cells. In BAL and bronchial epithelial cells, IL-26 increased gene expression of the IL-26 receptor complex and STAT1 plus STAT3. Finally, IL-26 increased the release of neutrophil-mobilizing cytokines in BAL but not in epithelial cells. CONCLUSIONS This study implies that alveolar macrophages produce IL-26, which stimulates receptors on neutrophils and focuses their mobilization toward bacteria and accumulated immune cells in human lungs.

IgM phosphorylcholine antibodies inhibit cell death and constitute a strong protection marker for atherosclerosis development, particularly in combination with other auto-antibodies against modified LDL

BACKGROUND We have reported that anti-phosphorylcholine (anti-PC) IgM is a protection marker for human cardiovascular disease (CVD) and atherosclerosis. We here investigate the anti-PC autoantibodies in a well-defined cohort with regard to idiotype, atherosclerosis progression and mechanisms for its protective action. METHODS Serum levels and binding specificities of different anti-PC isotypes were determined in 226 hypertensive individuals enrolled in European Lacidipine Study on Atherosclerosis using ELISA. The mean of the maximum Intima-Media Thicknesses (IMT) in the far walls of common carotids and bifurcations was assessed at the time of inclusion, and four years afterwards. Apoptosis in immune cells was induced with lysophosphatidylcholine (LPC) and quantified using the MTT-assay. RESULTS Anti-PC IgM, IgA and IgG1 (but not IgG2) was negatively associated with IMT-progression. Combining anti-PC IgM with data on antibodies against oxidized- and malondialdehyde-modified LDL further strengthened this association. At very high levels, anti-PC IgM exhibited a striking negative association with atherosclerosis progression (OR 0.05; CI 0.006-0.40). Analysis of serum samples taken four years apart in study participants affirmed the stability of anti-PC IgM titers over time. Examination of fine specificities revealed that the protective isotypes (IgM, IgA and IgG1) are of the Group I idiotype whereas the non-protective IgG2 subclass was Group II. Anti-PC IgM inhibited LPC-induced cell death of immune cells. CONCLUSION Group I anti-PC antibodies, particularly of the IgM class, are independent protection markers for atherosclerosis progression. One potential mechanism of action is inhibition of LPC-induced cell cytotoxicity.

Low levels of IgM antibodies against phosphorylcholine are associated with fast carotid intima media thickness progression and cardiovascular risk in men

OBJECTIVE Low levels of IgM anti-phosphorylcholine (anti-PC) increase the risk of cardiovascular events (CVE). Here we investigate the association of low anti-PC with the progression of carotid intima media thickness (C-IMT) and incidence of CVE in a large cohort of individuals at high risk of CVE, the IMPROVE, a prospective multicenter European study. METHODS 3711 subjects (54-79 years) with at least three established cardiovascular risk factors were enrolled. Baseline serum levels of IgM anti-PC were measured by ELISA. Carotid ultrasound investigations were performed at baseline and after 15 and 30 months of follow-up. The risk of C-IMT progression and ischemic CVE associated with low anti-PC levels was tested by logistic regression and Cox regression analysis, respectively. Risk estimates were adjusted by center and conventional cardiovascular risk factors. RESULTS 3670 study participants were included in the present analysis and 213 CVE were recorded during a 3 year follow up. Anti-PC levels (U/ml) were classified into quartiles [Q1≤ 40, Q2 >40-≤64, Q3 >64-≤102, Q4 >102]. In men, low levels of anti-PC (Q1) were associated with the highest (>90th) percentile of the fastest C-IMT progression, i.e. the segment showing the fastest progression over 30 months in the whole carotid tree, with an OR of 1.41 (95%CI, 1.02-1.9) and with an increased risk of CVE with a multivariable adjusted HR of 1.85 (95%CI, 1.1-3.1). No significant associations were found in women. CONCLUSIONS Low anti-PC levels increase the risk of CVE in men. This effect may be partly mediated by a fast C-IMT progression.

NAMPT (visfatin) and AKT1 genetic variants associate with myocardial infarction.

BACKGROUND High plasma levels of the adipokine NAMPT (or visfatin) have been associated with cardiovascular disease. However experimental data suggest that NAMPT, via Akt signaling, protects the myocardium against hypoxic insults. We studied whether the NAMPT rs1319501, AKT1 rs3730358, p53 rs1042522, Mdm2 rs2279744 or eNOS rs1799983 SNP:s linked to NAMPT and Akt signaling associate with risk of myocardial infarction (MI). METHODS Cases were 828 men and 346 women aged 45-70 who had suffered a first MI. Control individuals, 1062 men and 513 women, were randomly chosen from the study base. We employed unconditional logistic regression analysis. RESULTS The rs1319501 minor allele associated with MI among women aged 45-60; odds ratio (OR) under a recessive model of inheritance: 2.96 (95% confidence interval [CI] 1.06-8.29). Replication analysis in an independent material yielded OR point estimates in the same direction. The rs3730358 minor allele associated with low MI risk in men aged 45-60 (OR dominant model: 0.72, 95% CI 0.53-0.97), an association completely attenuated by adjusting for inflammatory markers. CONCLUSIONS The NAMPT rs1319501 minor allele associates with increased MI risk in young women. In young men a protective effect of the AKT1 rs3730358 minor allele was suggested, possibly related to an attenuated inflammation.