Can Antibodies Protect Us Against Cardiovascular Disease?

Changes in Specific Biomarkers Indicate Cardiac Adaptive and Anti-inflammatory Response of Repeated Recreational SCUBA Diving

Objective

Recreational SCUBA (rSCUBA) diving has become a highly popular and widespread sport. Yet, information on molecular events underlying (patho)physiological events that follow exposure to the specific environmental conditions (hyperbaric conditions, coldness, immersion, and elevated breathing pressure), in which rSCUBA diving is performed, remain largely unknown. Our previous study suggested that repeated rSCUBA diving triggers an adaptive response of cardiovascular and immune system. To elucidate further molecular events underlying cardiac and immune system adaptation and to exclude possible adverse effects we measured blood levels of specific cardiac and inflammation markers.

Methods

This longitudinal intervention study included fourteen recreational divers who performed five dives, one per week, on the depth 20–30 m that lasted 30 min, after the non-dive period of 5 months. Blood samples were taken immediately before and after the first, third, and fifth dives. Copeptin, immunoglobulins A, G and M, complement components C3 and C4, and differential blood count parameters, including neutrophil-to-lymphocyte ratio (NLR) were determined using standard laboratory methods. Cell-free DNA was measured by qPCR analysis and N-glycans released from IgG and total plasma proteins (TPP), were analyzed by hydrophilic interaction ultra-performance liquid chromatography.

Results

Copeptin level increased after the first dive but decreased after the third and fifth dive. Increases in immunoglobulins level after every dive and during whole studied period were observed, but no changes in C3, C4, and cfDNA level were detected. NLR increased only after the first dive. IgG and TPP N-glycosylation alterations toward anti-inflammatory status over whole studied period were manifested as an increase in monogalyctosylated and core-fucosylated IgG N-glycans and decrease in agalactosylated TPP N-glycans.

Conclusion

rSCUBA diving practiced on a regular basis promotes anti-inflammatory status thus contributing cardioprotection and conferring multiple health benefits.

Oxidized Lipids: Common Immunogenic Drivers of Non-Alcoholic Fatty Liver Disease and Atherosclerosis

The prevalence of non-alcoholic fatty liver disease (NAFLD), ranging from simple steatosis to inflammatory steatohepatitis (NASH) and cirrhosis, continues to rise, making it one of the major chronic liver diseases and indications for liver transplantation worldwide. The pathological processes underlying NAFLD not only affect the liver but are also likely to have systemic effects. In fact, growing evidence indicates that patients with NAFLD are at increased risk for developing atherosclerosis. Indeed, cardiovascular complications are the leading cause of mortality in NAFLD patients. Here, we aim to address common pathophysiological molecular pathways involved in chronic fatty liver disease and atherosclerosis. In particular, we focus on the role of oxidized lipids and the formation of oxidation-specific epitopes, which are important targets of host immunity. Acting as metabolic danger signals, they drive pro-inflammatory processes and thus contribute to disease progression. Finally, we summarize encouraging studies indicating that oxidized lipids are promising immunological targets to improve intervention strategies for NAFLD and potentially limit the risk of developing atherosclerosis.

Long-Term Efficacy and Safety of Immunomodulatory Therapy for Atherosclerosis

BACKGROUND AND AIMS

The long-term effect of immune tolerance has not been explored so far in atherosclerosis. In the present study, we assessed the effect of mucosal tolerance to a multi antigenic construct expressing three peptides from ApoB, HSP60, and outer membrane protein from Chlamydia pneumonia (AHC) for 30 weeks at every 6-week interval to understand the kinetics of immune modulation in disease progression. The safety profile of the molecule was also evaluated in mice.

METHODS

Apob^tm2SgyLdlr^tm1Her/J mice (5-6 weeks) were orally dosed with multi antigenic construct (AHC) molecule on alternate days, followed by high-fat diet feeding to initiate atherosclerosis.

RESULTS

Treated animals showed an efficient reduction in plaque growth and lipid accumulation at 6 weeks (49%, p < 0.01) and 12 weeks (42.3%, p < 0.01) which decreased to 29% (p = 0.0001) at 18 weeks and at later time points. Macrophage accumulation was significantly lower at all time points (53% at 12 weeks to 27% at 30 weeks). Regulatory T cells increased in the spleen following treatment until 12 weeks (week 0 (2.57 ± 0.18 vs. 6.36 ± 0.03, p = 0.02), week 6 (4.52 ± 0.2 vs. 8.87 ± 0.32, p = 0.02), and week 12 (8.74 ± 0.37 vs. 15.4 ± 0.27, p = 0.02)) but showed a decline later. A similar trend was observed with tolerogenic dendritic cells. We observed an increase in antibody levels to low-density lipoprotein and oxidized LDL at later stages. AHC molecule was found to be safe in acute and repeated dose toxicity studies.

CONCLUSIONS

Our results suggest that immune tolerance to AHC protein by oral administration is able to provide efficient atheroprotection up to 18 weeks and moderately at later stages. Apart from immune regulatory cells, protective antibodies may also have a role in controlling atherosclerosis.

IgM anti-malondialdehyde low density lipoprotein antibody levels indicate coronary heart disease and necrotic core characteristics in the Nordic Diltiazem (NORDIL) study and the Integrated Imaging and Biomarker Study 3 (IBIS-3)

Background

Certain immunoglobulins (Ig) are proposed to have protective functions in atherosclerosis.

Objectives

We tested whether serum levels of IgG and IgM autoantibodies against malondialdehyde low density lipoprotein (MDA-LDL) are associated with clinical coronary heart disease (CHD) and unfavorable plaque characteristics.

Methods

NORDIL was a prospective study investigating adverse cardiovascular outcomes in hypertensive patients. IBIS-3 analyzed lesions in a non-culprit coronary artery with <50% stenosis using radiofrequency intravascular ultrasound (RF-IVUS) and near-infrared spectroscopy (NIRS). Imaging was repeated after a median of 386?days on rosuvastatin. Associations of antibodies with incident CHD and imaging parameters were assessed in the two sub-studies respectively.

Findings

From 10,881 NORDIL patients, 87 had serum sampled at baseline and developed CHD over 4.5 years, matched to 227 controls. Higher titers of IgM anti-MDA-LDL had a protective effect on adverse outcomes, with odds ratio 0.29 (0.11, 0.76; p=0.012; p=0.016 for trend). Therefore, the effect was explored at the lesional level in IBIS-3. 143 patients had blood samples and RF-IVUS measurements available, and NIRS was performed in 90 of these. At baseline, IgM anti-MDA-LDL levels had a strong independent inverse relationship with lesional necrotic core volume (p=0.027) and percentage of plaque occupied by necrotic core (p=0.011), as well as lipid core burden index (p=0.024) in the worst 4 mm segment.

Interpretation

Our study supports the hypothesis that lower circulating levels of IgM anti-MDA-LDL are associated with clinical CHD development, and for the first time relates these findings to atherosclerotic plaque characteristics that are linked to vulnerability.

Inverse association of ApoB and HSP60 antibodies with coronary artery disease in Indian population

Objective

Atherosclerosis is an autoimmune condition and the underlying cause of coronary artery disease (CAD). Circulating antibodies to self-antigens can have a pathogenic or protective function in atherosclerosis. The objective of the study was to understand the association of autoantibody levels with CAD and its correlation with circulating immune cells.

Methods

We assessed antigen concentration and antibodies to apolipoprotein B (ApoB) and heat shock protein (HSP)60 by ELISA in 252 acute coronary syndromes (ACS), 112 patients with stable angina (SA) and 203 healthy controls from Indian population. T cells in peripheral blood mononuclear cells (PBMC) were enumerated by flow cytometry. Cytokine concentrations were measured by multiplex assay.

Results

IgG and IgM antibodies to ApoB and HSP60 proteins were significantly lower in patients with ACS while only IgG levels to ApoB were lower in patients with SA, compared with control. Subjects in the highest tertile of antibodies showed significantly lower OR for ACS (IgG 0.52, 95% CI 0.31 to 0.88, p=0.02 and IgM 0.58, 95% CI 0.34 to 0.98, p=0.04), ApoB100 (IgG 0.52, 95% CI 0.31 to 0.88, p=0.02 and IgM 0.58, 95% CI 0.34 to 0.99, p=0.04) and HSP60, respectively. Interestingly, T helper 17 (TH17) cells showed an inverse relationship with ApoB and HSP60 IgG antibodies (r²=-0.17, p<0.001 and r²=-0.20, p<0.001, respectively), while interleukin 17 concentrations were negatively correlated with IgM antibodies to the proteins.

Conclusion

This study shows that higher antibodies to ApoB and HSP60 proteins are less often associated with ACS and that these antibodies are inversely associated with inflammatory Th17 cells.