IgA antibodies to phosphocholine associate with long-term cardiovascular disease risk.

BACKGROUND AND AIMS: Antibodies to phosphocholine and oxidized LDL (oxLDL) are proposed to modify progression of atherosclerosis. We investigated the prognostic value of antibodies to phosphocholine (PCho), Streptococcus pneumoniae cell wall polysaccharide (CWPS) and oxLDL in defining long-term CVD survival. METHODS: CVD incidence was followed for 18 years and analyzed with baseline plasma IgM, IgG and IgA antibody levels to PCho, CWPS and oxLDL in 1044 subjects of Oulu Project Elucidating Risk of Atherosclerosis study (OPERA). RESULTS: During the follow-up period, 195 subjects (18.7%) had a CVD event. Cox model with ACC/AHA CVD adjustments (ASCVD) showed that IgA levels to PCho and IgA to CWPS were statistically significant factors predicting CVD risk. IgM and IgG antibodies to PCho, CWPS and oxLDL had no effect on CVD risk after adjusting for other risk factors. Net reclassification improvement (categories: 17-year risk <15%, 15-30%, >30%), was 0.06 (-0.001-0.12, p < 0.054), and IDI was 0.0124 (0.0036-0.0211, p < 0.006) with IgA-PCho added to the ASCVD risk model. Seventeen (9.4%) study subjects with CVD events were correctly reclassified into higher risk category while 9 (5.0%) subjects were classified into lower risk category. Among the non-cases, 58 (8.7%) subjects were correctly reclassified into lower risk, and 46 (5.9%) were reclassified into higher risk category. CONCLUSIONS: Plasma IgA antibodies to PCho and Streptococcus pneumoniae CWPS are significant predictors of long-term CVD risk. Additional studies on the role of IgA antibodies in atherogenesis and CVD are warranted.

High plasma immunoglobulin (Ig) A and low IgG antibody titers to oxidized low-density lipoprotein are associated with markers of glucose metabolism.

CONTEXT: Plasma oxidized low-density lipoprotein (OxLDL) is known to be associated with obesity, metabolic syndrome, and diabetes. OBJECTIVE: The objective of the study was to investigate the association between plasma IgA, IgM, and IgG titers to OxLDL, phosphocholine (PC), and streptococcal cell wall polysaccharide (CWPS) and markers of glucose metabolism, type 2 diabetes, and liver adiposity. SETTING AND PARTICIPANTS: A population-based cohort of middle-aged Finns (n = 1039) participated in the study. DESIGN: Plasma IgM, IgG, and IgA to copper oxidized LDL (CuOx-LDL) and malondialdehyde-modified low-density lipoprotein (MDA-LDL), PC, and CWPS were determined with chemiluminescent ELISA and liver adiposity with ultrasonography. RESULTS: IgA autoantibody titers to OxLDL and PC, but not CWPS, were positively associated with fasting blood glucose and plasma insulin levels and inversely with insulin sensitivity index. IgA to OxLDL was significantly higher (P = 0.013 for CuOx-LDL and P = 0.016 for MDA-LDL) and IgG to OxLDL significantly lower (P = 0.036 for CuOx-LDL and P = 0.001 for MDA-LDL) among the subjects with type 2 diabetes compared with subjects with normal or impaired glucose metabolism when adjusted for age, sex, body mass index, smoking, and alcohol consumption. Logistic regression analysis showed that high plasma IgA to OxLDL and low IgG to MDA-LDL were independent risk factors for type 2 diabetes. Plasma IgA titers to OxLDL demonstrated a significant association with liver adiposity (P = 0.012) and gamma-glutamyltransferase levels (P = 0.002). CONCLUSIONS: Plasma IgA titers to OxLDL were positively and IgG titers negatively associated with markers of glucose metabolism. High plasma IgA and low IgG to OxLDL were independent risk factors for type 2 diabetes.

Plasma interleukin-5 levels are related to antibodies binding to oxidized low-density lipoprotein and to decreased subclinical atherosclerosis.

OBJECTIVES: This study's aim was to assess the role of interleukin (IL)-5 in modulating the levels of antibodies binding to oxidized low-density lipoprotein (OxLDL) in human atherosclerosis. BACKGROUND: Various pro- and anti-inflammatory cytokines have been implicated in atherogenesis, and recent findings in mice indicate that the cytokine IL-5 plays a protective role in atherosclerosis in part via the induction of antibodies binding to OxLDL. METHODS: Plasma IL-5 levels and antibody titers to 2 most commonly used models of OxLDL (copper OxLDL and malondialdehyde-modified LDL) were measured in 1,011 Finnish middle-aged subjects with chemiluminescent enzyme-linked immunosorbent assay. Intima-media thickness (IMT) was assessed ultrasonographically from the internal carotid artery, the bifurcation, and the common carotid artery. RESULTS: There was a significant positive association between plasma IL-5 levels and antibody titers to copper OxLDL (p = 0.010 and p = 0.044, immunoglobin [Ig] M and G, respectively) and IgM to malondialdehyde-modified LDL (p < 0.001) in the association analysis performed between different IL-5 quartiles. Furthermore, plasma IL-5 levels were found to be inversely associated with bifurcational IMT, and even after adjustments for traditional risk factors of atherosclerosis (age, gender, smoking, systolic blood pressure, LDL, and body mass index), IL-5 remained an independent determinant of the mean bifurcational IMT (p = 0.010). CONCLUSIONS: Our data demonstrate that plasma IL-5 levels are related to the plasma levels of antibodies binding to OxLDL and to decreased subclinical atherosclerosis in humans. These results are in line with earlier findings in murine atherosclerosis and indicate for the first time that IL-5 may play a role in human atherosclerosis.