Higher levels of anti-phosphorylcholine autoantibodies in early rheumatoid arthritis indicate lower risk of incident cardiovascular events

Plasma levels of anti phosphocholine IgM antibodies are negatively correlated with bone mineral density in humans

Phosphatidylcholine is a ubiquitous phospholipid. It contains a phosphocholine (PC) headgroup and polyunsaturated fatty acids that, when oxidized, form reactive oxidized phospholipids (PC-OxPLs). PC-OxPLs are pathogenic in multiple diseases and neutralized by anti-PC IgM antibodies. The levels of anti-PC IgM increase as the levels of PC-OxPLs increase and, in humans, are inversely correlated with the incidence of cardiovascular diseases and steatohepatitis. PC-OxPLs also decrease bone mass in mice. Overexpression of anti-PC IgM ameliorates atherosclerosis and steatohepatitis, increases bone mass in young mice, and protects against high fat diet- and age-associated osteoporosis. We investigated the relationship between anti-PC IgM plasma levels and bone mineral density (BMD) in a cross-sectional study of 247 participants [mean age: 65.5 (± 8.6) years] without medical conditions known to influence BMD or antibody production. Anti-PC IgM levels negatively correlated with both T- and Z-scores at the lumbar spine, femur and, to a lesser extent, the forearm. These correlations were maintained after adjustment for age, race, and sex. These results raise the possibility that higher levels of anti-PC IgM in patients with lower BMD reflect exposure to higher levels of PC-OxPLs, which are known to affect bone mass, and could be a novel risk marker for osteoporosis.

Antibodies Against Phosphorylcholine in Prediction of Cardiovascular Disease Among Women: A Population-Based Prospective Cohort Study

Background

Antibodies against phosphorylcholine (anti-PC) have been reported as associated with protection against atherosclerosis, cardiovascular disease (CVD), and other chronic inflammatory diseases. Underlying potential mechanisms have been demonstrated and include anti-inflammatory, clearance of dead cells, and inhibition of oxidized low-density lipoprotein effects.

Objectives

This study examined the role of IgM anti-PC and incident CVD among women, where less is known than among men in the general population.

Methods

In a total of 932 women, age 66 ± 6 years at baseline, from the population-based Swedish Mammography Cohort, IgM anti-PC levels of sera were measured using Enzyme Linked Immunosorbent assay. Prospective associations with any first CVD, ischemic heart disease (IHD), myocardial infarction (MI), and ischemic stroke were assessed using Cox proportional hazard regression, generating HRs and 95% CIs. The model was adjusted for potential confounding factors.

Results

Over the course of 16 years (13,033 person-years), we identified 113 cases of composite CVD, 69 cases of IHD, 44 cases of MI, and 50 cases of ischemic stroke. IgM anti-PC was statistically significantly inversely associated with risk of CVD, IHD, and MI, but not with ischemic stroke. Comparing the highest tertile with lowest, we observed multivariable-adjusted HR of 0.27 (95% CI: 0.11-0.68; P trend <0.01) for MI.

Conclusions

IgM anti-PC may play an active role in inhibition of CVD development in women, especially MI. Furthermore, IgM anti-PC levels may play a role in identifying those at risk.

GM-CSF receptor/SYK/JNK/FOXO1/CD11c signaling promotes atherosclerosis

Atherosclerosis complicates chronic inflammatory diseases, such as rheumatoid arthritis and systemic lupus erythematosus, suggesting that a shared physiological pathway regulates inflammatory responses in these diseases wherein spleen tyrosine kinase (SYK) is involved. We aimed to identify a shared therapeutic target for atherosclerosis and inflammatory diseases. We used Syk-knockout atherosclerosis-prone mice to determine whether SYK is involved in atherosclerosis via the inflammatory response and elucidate the mechanism of SYK signaling. The Syk-knockout mice showed reduced atherosclerosis in vivo, and macrophages derived from this strain showed ameliorated cell migration in vitro. CD11c expression decreased on Syk-knockout monocytes and macrophages; it was upregulated by forkhead box protein O1 (FOXO1) after stimulation with granulocyte-macrophage colony-stimulating factor (GM-CSF), and c-Jun amino-terminal kinase (JNK) mediated SYK signaling to FOXO1. Furthermore, FOXO1 inhibitor treatment mitigated atherosclerosis in mice. Thus, GM-CSF receptor/SYK/JNK/FOXO1/CD11c signaling in monocytes and macrophages and FOXO1 could be therapeutic targets for atherosclerosis and inflammatory diseases.

Antibodies against phosphorylcholine and protection against atherosclerosis, cardiovascular disease and chronic inflammation

INTRODUCTION

Chronic inflammatory diseases include cardiovascular disease (CVD) atherosclerosis, rheumatic and autoimmune diseases, and others, constitute a large part of the disease burden. It is therefore of major importance to improve understanding of underlying mechanisms, prediction and treatment.

AREAS COVERED

Broad fields including atherosclerosis, immunology and inflammation are covered, through searches on Pubmed and background knowledge. Phosphorylcholine (PC) is both a danger associated molecular pattern (DAMP), present on oxidized LDL (OxLDL) in atherosclerotic lesions and dead cells, and a pathogen associated molecular pattern (PAMP), present on microorganisms. IgM and IgG1 antibodies against PC (anti-PC) are associated with protection in several chronic inflammatory conditions, especially in CVD and atherosclerosis where most research has been done. PC-immunization ameliorates atherosclerosis in animal models and several potential underlying mechanisms have been proposed, including anti-inflammatory, decreased uptake of OxLDL in the artery wall, promotion of T regulatory cells. Anti-PC develops during the first years of life. Low levels of IgM and IgG1 anti-PC may be caused by lack of exposure to microorganisms, including nematodes and helminths among others.

EXPERT OPINION

anti-PC could improve prediction of clinical outcome and raising anti-PC could be developed into a novel therapy.