Low levels of IgM antibodies against phosphorylcholine—A potential risk marker for ischemic stroke in men

doi:10.1016/j.atherosclerosis.2008.07.009

Atherosclerosis

Volume 203, Issue 2, April 2009, Pages 528-532

https://doi.org/10.1016/j.atherosclerosis.2008.07.009 Get rights and content

Abstract

Background

Natural antibodies specific for phosphorylcholine (anti-PC) have been implicated as protective factors in atherosclerosis. We herein determined the relationship between IgM anti-PC and incidence of cardiovascular disease (CVD).

Methods

We studied 349 incident cases (200 men) of first events of CVD (coronary heart disease (CHD; n = 203 or ischemic stroke; n = 146) and 693 age- and sex-matched controls identified through 12 years of follow-up (1991–2003) of subjects from the cardiovascular cohort within the Malmö Diet and Cancer Study. Relative risks (RR) of CVD with 95% confidence intervals (CI) of incident CVD with adjustments for age, smoking, total cholesterol and blood pressure were determined. Anti-PC-levels were measured using ELISA (Athera CVDefine™).

Results

As determined using Athera CVDefine™, significant associations were attained with values of anti-PC below 17 U/ml (corresponding to the lowest 9th percentile), which remained after taking confounders into account (RR: 1.79, 95% CI: 1.09–2.94, p = 0.021). If men were studied separately, significance was evident at values below 17 U/ml (RR: 2.01, 95% CI: 1.11–3.67, p = 0.022), which was not the case among women. Furthermore, values below 17 U/ml were also associated with ischemic stroke (RR = 3.67, 95% CI: 1.34–10.1, p = 0.01), but not with CHD.

Conclusion

Low IgM anti-PC could be a novel risk marker for development of ischemic stroke in men. Further studies are needed to establish gender and subgroup differences.

Introduction

Atherosclerosis is characterized by the presence of activated immune competent cells which produce cytokines, mainly of a pro-inflammatory type, in the lesions [1]. It is not clear how traditional risk factors such as hypertension, hyperlipidemia, diabetes and smoking are related to the immune reactions in atherosclerotic lesions, and even what the aetiology of the disease is. Different non-mutually exclusive possibilities have been proposed, including modification of LDL through oxidation (OxLDL) or through enzymatic modification by enzymes such as phospholipase A2 [2], [3]. The role of infectious agents and heat shock proteins (HSP) have also been discussed [3], [4].

OxLDL is immunogenic and can activate T cells [5], [6] and B cells producing antibodies against modified forms of LDL have been known for a long time [7]. Both antigens from the protein and lipid moieties of LDL may be of importance, and these possibilities are not mutually exclusive. For example, antibodies against peptides from apoB100 are involved in some forms of immune reactions against OxLDL and immunization with such peptides can inhibit atherosclerosis development in experimental animals [8].

We and others have reported that the immuno-stimulatory effects of OxLDL can be attributed to inflammatory phospholipids such as platelet activating factor (PAF)-like phospholipids and lysophosphatidylcholine of which phosphorylcholine (PC) is a major component. PAF-like lipids and/or lysophosphatidylcholine (LPC) can cause OxLDL-related immune reactions and pro-inflammatory effects [2], [9], [10], [11]. The anti-atherogenic effect of immunization with OxLDL in animal models can be mimicked by passive immunization with both apoB100 peptides [12] and antibodies against PC [13]. PC is also a major active component in bacteria including Streptococcus pneumoniae[14] and in apoptotic cells [15], [16]. Immunization with pneumococcal vaccine that induced anti-PC, among other antibodies, was demonstrated to protect against atherosclerosis development [17].

We recently demonstrated that anti-PC of IgM isotype are negatively associated with development of atherosclerosis in hypertensive patients [18]. We herein report that low levels of IgM anti-PC could be a novel risk marker for ischemic stroke in men. The implications of these findings are discussed.

Section snippets

Materials and methods

The Malmö Diet and Cancer Study (MDCS) is a prospective cohort study examining the association between diet and cancer [19]. Subjects born between 1926 and 1945 and living in Malmö were eligible for inclusion in the study. Between October 1991 and February 1994, every other participant was also invited to take part in a substudy of the epidemiology of carotid artery disease [20]. Subjects with history of myocardial infarction (MI) or stroke prior to enrolment and subjects with diabetes mellitus

Performance data of CVDefine

The detection limit for IgM anti-PC determined with Athera CVDefine was evaluated by testing calibrator 1 (0 U/ml) in 56 replicates. The mean value of the replicates +3S.D. was 0.5 U/ml, which was defined as the detection limit. The quantification limit, defined by the mean value of the 56 replicates +10S.D., was 3.2 U/ml.

To ascertain the specificity of IgM anti-PC, 15 serum samples containing different levels of IgM anti-PC were tested in microwells coated with 5 μg/ml of either BSA or PC-BSA. The

Discussion

Herein we report that low levels of IgM antibodies to PC predict increased risk for ischemic stroke in men from a population urban-based cohort from southern Sweden, indicating that low IgM anti-PC levels could be a novel risk marker for development of ischemic stroke in men.

These findings are in agreement with recent findings from our group indicating an inverse association between IgM anti-PC levels and development of atherosclerosis with time in hypertensive individuals [18] (the higher the

Acknowledgements

We thank Helene Lettesjö och Fredrik Hjelm for development of the IgM anti-PC determination method and Dr. RA Harris for linguistic advice.

Grant/funding support: This study was supported by the Swedish Heart Lung Foundation, the Swedish Research Council, ALF, the Swedish Science Fund, the King Gustav V 80th Birthday Fund, The Swedish Rheumatism Association, The Torsten and Ragnar Söderberg Foundation, Swedish Cancer Society, the Malmö University Hospital Foundation, the region of Skåne and

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High immunoglobulin-M levels to oxidation-specific epitopes are associated with lower risk of acute myocardial infarction
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Immunoglobulin M (IgM) autoantibodies to oxidation-specific epitopes (OSEs) can be present at birth and protect against atherosclerosis in experimental models. This study sought to determine whether high titers of IgM titers to OSE (IgM OSE) are associated with a lower risk of acute myocardial infarction (AMI) in humans. IgM to malondialdehyde (MDA)-LDL, phosphocholine-modified BSA, IgM apolipoprotein B100-immune complexes, and a peptide mimotope of MDA were measured within 24 h of first AMI in 4,559 patients and 4,617 age- and sex-matched controls in the Pakistan Risk of Myocardial Infarction Study. Multivariate-adjusted logistic regression was used to estimate odds ratio (OR) and 95% confidence interval for AMI. All four IgM OSEs were lower in AMI versus controls (P < 0.001 for all). Males, smokers and individuals with hypertension and diabetes had lower levels of all four IgM OSE than unaffected individuals (P < 0.001 for all). Compared to the lowest quintile, the highest quintiles of IgM MDA-LDL, phosphocholine-modified BSA, IgM apolipoprotein B100-immune complexes, and MDA mimotope P1 had a lower OR of AMI: OR (95% confidence interval) of 0.67 (0.58–0.77), 0.64 (0.56–0.73), 0.70 (0.61–0.80) and 0.72 (0.62–0.82) (P < 0.001 for all), respectively. Upon the addition of IgM OSE to conventional risk factors, the C-statistic improved by 0.0062 (0.0028–0.0095) and net reclassification by 15.5% (11.4–19.6). These findings demonstrate that IgM OSE provides clinically meaningful information and supports the hypothesis that higher levels of IgM OSE may be protective against AMI.
Anti-phosphorylcholine IgM, an Anti-inflammatory Mediator, Predicts Peripheral Vein Graft Failure: A Prospective Observational Study
2019, European Journal of Vascular and Endovascular Surgery
Citation Excerpt :
Endoscopic harvesting techniques were not used. Previous clinical studies have indicated that the lowest levels of anti-PC IgM are closely linked to adverse cardiovascular outcomes, while a much broader range of average or high levels is associated with freedom from risk.8–10 Thus, for this study it was chosen, in advance, to compare the cohort of patients in the lowest quartile of anti-PC IgM with those in the highest three quartiles.
One third of infrainguinal vein bypasses may fail within the first 1.5 years. Pro- and anti-inflammatory mechanisms are thought to be involved in these graft stenoses and occlusions. In previous studies, low levels of anti-phosphorylcholine IgM (anti-PC IgM, an innate anti-inflammatory IgM) have been associated with increased cardiovascular events. In this study, the peri-operative dynamics of anti-PC IgM levels were established during leg bypass surgery, and associations assessed between anti-PC IgM levels and primary graft patency.
This was a prospective, observational cohort study of infrainguinal autogenous vein bypass for peripheral arterial occlusive disease involving four university affiliated hospitals. Plasma cytokine and anti-PC IgM levels were measured pre- and post-operatively. The outcome of interest was loss of primary graft patency because of occlusion or intervention for graft stenosis.
One hundred and forty-two consecutive patients were enrolled: mean age 66 (46–91); 91% white race and male; 72.5% critical limb ischaemia (Fontaine III or IV). Median pre-operative anti-PC IgM levels were 49 units/mL (IQR 32.3–107.7, mean 89.8 + 101 sd). During follow up of an average of 1.8 years (1 month–7.4 years), 50 (35.2%) grafts lost primary patency. Pre-operative levels of interleukin 6 or C-reactive protein did not predict graft failure. Patients with pre-operative anti-PC IgM values in the lowest quartile had a twofold increased risk of graft failure (multivariable Cox proportional hazard, p = .03, HR 2.11, 95% CI 1.09–4.07), even after accounting for the other significant factors of conduit diameter, distal anastomosis, smoking, and the severity of leg ischaemia.
Low levels of anti-PC IgM are associated with vein bypass graft failure. This biological mediator may be a useful marker to identify patients at higher risk, and offers the potential for novel, directed therapies for vascular inflammation and its consequences.
Age-associated B cells (ABC) inhibit B lymphopoiesis and alter antibody repertoires in old age
2017, Cellular Immunology
Citation Excerpt :
Antibodies to these bacterial antigens are important in defense against infections. Antibodies reactive with either PC or MDA also react with oxidized lipoproteins and may protect against—or promote—atherosclerosis [29–31]. ABC expansion as seen in old age is dependent upon TLR7 and can be driven by TLR7 ligands [20].
With old age (∼2 y old), mice show substantial differences in B cell composition within the lymphoid tissues. In particular, a novel subset of IgM⁺ CD21/35^lo/− CD23⁻ mature B cells, the age-associated B cells or ABC, increases numerically and proportionately. This occurs at the expense of other B cell subsets, including B2 follicular B cells in spleen and recirculating primary B cells in bone marrow. Our studies suggest that ABC have a distinctive antibody repertoire, as evidenced by relatively high reactivity to the self-antigens phosphorylcholine (PC) and malondialdehyde (MDA). While PC and MDA are found on apoptotic cells and oxidized lipoproteins, antibodies to these antigens are also cross-reactive with epitopes on bacterial species. In old mice, ABC express TNFα and are pro-inflammatory. ABC can inhibit growth and/or survival in pro-B cells as well as common lymphoid progenitors (CLP). In particular, ABC cause apoptosis in pro-B cells with relatively high levels of the surrogate light chain (SLC) and, consequently, promote an “SLC low” pathway of B cell differentiation in old mice. SLC together with μ heavy chain comprises the pre-B cell receptor (preBCR) critical for pre-B cell expansion and selection of the μ heavy chain Vh repertoire. The low level of SLC likely impairs normal preBCR driven proliferation and alters μ heavy chain Vh selection thereby affecting the antibody specificities of new B cells. In this manner, ABC may contribute to both qualitative and quantitative disruptions of normal B lymphopoiesis in old age.
In old BALB/c mice, bone marrow pre-B cell and surrogate light chain reduction is associated with increased B cell reactivity to phosphorylcholine, but reduced T15 idiotype dominance
2017, Mechanisms of Ageing and Development
Citation Excerpt :
Moreover, T15+ anti-PC antibodies bind to oxidized phospholipids found in atherosclerotic lesions (Shaw et al., 2000). In humans, increased levels of IgM anti-PC antibodies are associated with diminished risk for cardiovascular disease and stroke (de Faire et al., 2010; Sjöberg et al., 2009). Therefore, humoral immunity to PC functions in normal tissue homeostasis as well as in combating infection.
In young adult BALB/c mice, antibodies to phosphorylcholine (PC) bearing the T15 (TEPC 15) idiotype confer protection against pneumococcal infections. In old age, even though PC reactive B cells are often increased, the proportion of T15⁺ antibodies declines. We hypothesize that limited surrogate light chain (SLC) and compromise of the pre-B cell receptor checkpoint in old mice contribute to both reduced new B cell generation and changes in the anti-PC antibodies seen in old age. In old mice: 1) early pre-B cell loss is most pronounced at the preBCR checkpoint; however, the reduced pool of early pre-B cells continues to proliferate consistent with preBCR signaling; 2) increased PC reactivity is seen in bone marrow immature B cells; 3) deficient SLC promotes increased B cell PC reactivity and diminished T15 idiotype expression; and 4) as pre-B cell losses and reduced SLC become progressively more severe, increased T15 negative PC reactive B cells occur. These results associate a reduction in pre-B cells, imposed at the preBCR checkpoint, with increased reactivity to PC, but more limited expression of the protective T15 idiotype among PC reactive antibodies in old age.
Long-term prognostic value of IgM antibodies against phosphorylcholine for adverse cardiovascular events in patients with stable coronary heart disease
2015, Atherosclerosis
Citation Excerpt :
Prior studies have shown conflicting results on the association between IgM anti-PC antibodies and risk of future cardiovascular events in various populations. Among patients with hypertension, after suffering from stroke, patients on chronic dialysis and after recent MI low concentrations of IgM anti-PC were predictive for cardiovascular events [4,7,8,11,20]. Moreover, in a small study of fifty-six patients with severe peripheral artery disease (PAD) after surgical revascularisation concentrations of IgM anti-PC in the lowest quartile of the distribution were associated with statistically significant worse bypass graft patency [21].
Low concentrations of IgM-phosphorylcholine autoantibodies (IgM-anti-PC) have been shown to be associated with increased risk of incident cardiovascular disease (CVD) events and total mortality in patients suffering from an acute coronary syndrome. We assessed whether IgM-anti-PC concentrations add prognostic information for cardiovascular risk in patients with known stable coronary artery disease (CAD).
IgM-anti-PC concentrations were measured in serum obtained from 1062 patients with clinically manifest stable CAD at baseline. The relation of IgM-anti PC concentrations with CVD events during long-term follow-up was assessed by the Kaplan–Meier and life table method and quantified by means of the log-rank test. Then, Cox proportional hazards regression analysis was performed to assess the independent association of IgM anti-PC concentration with risk of secondary CVD events after adjustment for established and emerging risk factors.
In n = 1062 patients with stable CAD only very low IgM anti-PC serum concentrations were associated with increased risk for future fatal and non-fatal coronary events (n = 201 during median of 10 years of follow-up). Among patients with IgM anti-PC concentrations in the lowest decile, the partly adjusted hazard ratio for fatal and non-fatal coronary events was 1.60 (95% confidence interval (CI) 1.01–2.55) compared to the top quartile and 1.94 (95%-CI 1.18–3.18) after adjustment for multiple covariates.
In patients with stable CAD, very low concentrations of IgM anti-PC are associated with increased risk for fatal and non-fatal future coronary events and thus may add prognostic information to traditional cardiovascular risk factors among these patients.
Inflammatory mediators after endovascular aortic aneurysm repair
2014, Cytokine
To evaluate patterns of inflammatory mediators before and after elective endovascular aortic aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA).
Inflammatory mediators including soluble urokinase plasminogen activator (suPAR), endothelin (ET)-1, tumour necrosis factor (TNF)-α, interleukin (IL)-6, CD40 ligand (CD40L) and IgM antibodies against phosphorylcholine (IgM anti-PC), were evaluated before and after elective EVAR in 21 patients. Five patients undergoing open AAA repair (OR) were evaluated for comparison.
SuPAR (p < 0.001), ET-1 (p = 0.003) and IL-6 (p = 0.02) increased whereas IgM anti-PC decreased (p < 0.001) after EVAR. Both suPAR (p = 0.04) and IL-6 (p = 0.03) increased in the five patients with unchanged/expanded aneurysm sac after EAR, whereas only suPAR increased (p = 0.04) and IL-6 remained unchanged (p = 0.2) among the 16 patients with shrinking aneurysm sac. No difference was noted between patients undergoing EVAR and OR regarding levels or changes of studied markers.
These changes in plasma biomarker profile are compatible with on-going inflammatory activation in AAA patients after EVAR. The potential role of IL-6 as a plasma biomarker for treatment failure in surveillance programs after EVAR needs to be further evaluated.

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Low levels of IgM antibodies against phosphorylcholine—A potential risk marker for ischemic stroke in men

Abstract

Background

Methods

Results

Conclusion

Introduction

Section snippets

Materials and methods

Performance data of CVDefine

Discussion

Acknowledgements

Atherosclerosis

Atherosclerosis

Atherosclerosis

Immunol Today

Atherosclerosis

J Biol Chem

J Am Coll Cardiol

Lysophosphatidylcholine (LPC) induces proinflammatory cytokines by a platelet-activating factor (PAF) receptor-dependent mechanism

Clin Exp Immunol

Inflammation, atherosclerosis, and coronary artery disease

N Engl J Med

Induction of T-cell activation by oxidized low density lipoprotein

Arterioscler Thromb

T lymphocytes from human atherosclerotic plaques recognize oxidized low density lipoprotein

Proc Natl Acad Sci USA

Autoantibodies to glucosylated proteins in the plasma of patients with diabetes mellitus

Proc Natl Acad Sci USA

Inhibition of atherosclerosis in apoE-null mice by immunization with apoB-100 peptide sequences

Arterioscler Thromb Vasc Biol

Platelet-activating factor and oxidized LDL induce immune activation by a common mechanism

Arterioscler Thromb Vasc Biol

Lysophosphatidylcholine is involved in the antigenicity of oxidized LDL

Arterioscler Thromb Vasc Biol

Oxidatively modified LDL contains phospholipids with platelet-activating factor-like activity and stimulates the growth of smooth muscle cells

J Clin Invest

Recombinant human antibodies against aldehyde-modified apolipoprotein B-100 peptide sequences inhibit atherosclerosis

Circulation

Innate and acquired immunity in atherogenesis

Nat Med