Potential natural immunization against atherosclerosis in hibernating bears

Antibodies against malondialdehyde among 60-year-olds: prediction of cardiovascular disease

Malondialdehyde (MDA) is generated in oxidized LDL. It forms covalent protein adducts, and is recognized by antibodies (anti-MDA). We previously studied IgM anti-MDA, and here we focus on IgG, IgG1 and IgG2 anti-MDA in predicting cardiovascular disease (CVD). We determined, by ELISA, anti-MDA in a 7-year follow-up of 60-year-old men and women from Stockholm County (2039 men, 2193 women). We identified 210 incident CVD cases (defined as new events of myocardial infarction (MI), and hospitalization for angina pectoris) and ischemic stroke, and 620 age- and sex-matched controls. IgG anti-MDA was not associated with CVD. Median values only differed significantly for IgG1 anti-MDA among men, with lower levels among cases than controls (p = 0.039). High IgG1 anti-MDA (above 75th percentile) was inversely associated with CVD risk after adjustment for smoking, body mass index, type 2 diabetes, hyperlipidemia, and hypertension, (OR and 95% CI: 0.59; 0.40-0.89). After stratification by sex, this association emerged in men (OR and 95% CI: 0.46; 0.27-0.77), but not in women. IgG2 anti-MDA were associated with protection in the whole group and among men though weaker than IgG1 anti-MDA. IgG2 anti-MDA above the 75th percentile was associated with an increased risk of MI/angina in women (OR and 95% CI: 2.57; (1.08-6.16)). IgG1 and less so IgG2 anti-MDA are protection markers for CVD and MI/angina in the whole group and among men. However, IgG2 anti-MDA was a risk marker for MI/angina among women. These findings could have implications for both prediction and therapy.

Formerly bile-farmed bears as a model of accelerated ageing

Bear bile-farming is common in East and Southeast Asia and this farming practice often results in irreversible health outcomes for the animals. We studied long-term effects of chronic bacterial and sterile hepatobiliary inflammation in 42 Asiatic black bears (Ursus thibetanus) rescued from Vietnamese bile farms. The bears were examined under anesthesia at least twice as part of essential medical interventions. All bears were diagnosed with chronic low-grade sterile or bacterial hepatobiliary inflammation along with pathologies from other systems. Our main finding was that the chronic low-grade inflammatory environment associated with bile extraction in conjunction with the suboptimal living conditions on the farms promoted and accelerated the development of age-related pathologies such as chronic kidney disease, obese sarcopenia, cardiovascular remodeling, and degenerative joint disease. Through a biomimetic approach, we identified similarities with inflammation related to premature aging in humans and found significant deviations from the healthy ursid phenotype. The pathological parallels with inflammageing and immuno-senescence induced conditions in humans suggest that bile-farmed bears may serve as animal models to investigate pathophysiology and deleterious effects of lifestyle-related diseases.

Antibodies against Phosphorylcholine-Implications for Chronic Inflammatory Diseases

Atherosclerosis and its main consequence, cardiovascular disease (CVD) are nowadays regarded as chronic inflammatory disease conditions, and CVD is the main cause of death in the world. Other examples of chronic inflammation are rheumatic and other autoimmune conditions, but also diabetes, obesity, and even osteoarthritis among others. In addition, infectious diseases can have traits in common with these conditions. Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease, where atherosclerosis is increased and the risk of CVD is very high. This is a clinical problem but could also shed light on the role of the immune system in atherosclerosis and CVD. Underlying mechanisms are of major interest and these are only partially known. Phosphorylcholine (PC) is a small lipid-related antigen, which is both a danger associated molecular pattern (DAMP), and a pathogen associated molecular pattern (PAMP). Antibodies against PC are ubiquitous and 5-10% of circulating IgM is IgM anti-PC. Anti-PC, especially IgM and IgG1 anti-PC, has been associated with protection in the chronic inflammatory conditions mentioned above, and develops during the first years of life, while being present at very low levels at birth. Animal experiments with immunization to raise anti-PC ameliorate atherosclerosis and other chronic inflammatory conditions. Potential mechanisms include anti-inflammatory, immune modulatory, clearance of dead cells and protection against infectious agents. An intriguing possibility is to raise anti-PC levels through immunization, to prevent and/or ameliorate chronic inflammation.

Systemic lupus erythematosus and cardiovascular disease

The prognosis in systemic lupus erythematosus (SLE) has improved due to better treatment and care, but cardiovascular disease (CVD) still remains an important clinical problem, since the risk of CVD in SLE is much higher than among controls. Atherosclerosis is the main cause of CVD in the general population, and in SLE, increased atherosclerosis, especially the prevalence of atherosclerotic plaques, has been demonstrated. Atherosclerosis is an inflammatory condition, where immunity plays an important role. Interestingly, oxidized low-density lipoprotein, defective clearance of dead cells, and inflammation, with a pro-inflammatory T-cell profile are characteristics of both atherosclerosis and SLE. In addition to atherosclerosis as an underlying cause of CVD in SLE, there are also other non-mutually exclusive mechanisms, and the most important of these are antiphospholipid antibodies (aPL) leading to the antiphospholipid antibody syndrome with both arterial and venous thrombosis. aPL can cause direct pro-inflammatory and prothrombotic effects on endothelial and other cells and also interfere with the coagulation, for example, by inhibiting annexin A5 from its antithrombotic and protective effects. Antibodies against phosphorylcholine (anti-PC) and other small lipid-related epitopes, sometimes called natural antibodies, are negatively associated with CVD and atherosclerosis in SLE. Taken together, a combination of traditional risk factors such as hypertension and dyslipidemia, and nontraditional ones, especially aPL, inflammation, and low anti-PC are implicated in the increased risk of CVD in SLE. Close monitoring of both traditional risk factors and nontraditional ones, including treatment of disease manifestations, not lest renal disease in SLE, is warranted.

Antibodies in action: the role of humoral immunity in the fight against atherosclerosis

The sequestering of oxidation-modified low-density lipoprotein by macrophages results in the accumulation of fatty deposits within the walls of arteries. Necrosis of these cells causes a release of intercellular epitopes and the activation of the adaptive immune system, which we predict leads to robust autoantibody production. T cells produce cytokines that act in the plaque environment and further stimulate B cell antibody production. B cells in atherosclerosis meanwhile have a mixed role based on subclass. The current model is that B-1 cells produce protective IgM antibodies in response to oxidation-specific epitopes that work to control plaque formation, while follicular B-2 cells produce class-switched antibodies (IgG, IgA, and IgE) which exacerbate the disease. Over the course of this review, we discuss further the validation of these protective antibodies while evaluating the current dogma regarding class-switched antibodies in atherosclerosis. There are several contradictory findings regarding the involvement of class-switched antibodies in the disease. We hypothesize that this is due to antigen-specificity, and not simply isotype, being important, and that a closer evaluation of these antibodies' targets should be conducted. We propose that specific antibodies may have therapeutical potential in preventing and controlling plaque development within a clinical setting.

Serum plays an important role in reprogramming the seasonal transcriptional profile of brown bear adipocytes

Understanding how metabolic reprogramming happens in cells will aid the progress in the treatment of a variety of metabolic disorders. Brown bears undergo seasonal shifts in insulin sensitivity, including reversible insulin resistance in hibernation. We performed RNA-sequencing on brown bear adipocytes and proteomics on serum to identify changes possibly responsible for reversible insulin resistance. We observed dramatic transcriptional changes, which depended on both the cell and serum season of origin. Despite large changes in adipocyte gene expression, only changes in eight circulating proteins were identified as related to the seasonal shifts in insulin sensitivity, including some that have not previously been associated with glucose homeostasis. The identified serum proteins may be sufficient for shifting hibernation adipocytes to an active-like state.

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.

Antibodies Against Phosphorylcholine Among 60-Year-Olds: Clinical Role and Simulated Interactions

Aims

Antibodies against phosphorylcholine (anti-PC) are implicated as protection markers in atherosclerosis, cardiovascular disease (CVD), and other chronic inflammatory conditions. Mostly, these studies have been focused on IgM. In this study, we determined IgG, IgG1, and IgG2 anti-PC among 60-year-olds.

Methods

Based on a 7-year follow-up of 60-year-olds (2,039 men and 2,193 women) from Stockholm County, we performed a nested case-control study of 209 incident CVD cases with 620 age- and sex-matched controls. Anti-PC was determined using ELISA. We predicted the binding affinity of PC with our fully human, in-house-produced IgG1 anti-PC clones (i.e., A01, D05, and E01) using the molecular docking and molecular dynamics simulation approach, to retrieve information regarding binding properties to PC.

Results

After adjustment for confounders, IgG and IgG2 anti-PC showed some significant associations, but IgG1 anti-PC was much stronger as a protection marker. IgG1 anti-PC was associated with an increased risk of CVD below 33rd, 25th, and 10th percentile and of stroke below 33rd and 25th, and of myocardial infarction (MI) below 10th percentile. Among men, a strong association with stroke was determined below the 33rd percentile [HR 9.20, CI (2.22–38.12); p = 0.0022]. D05 clone has higher binding affinity followed by E01 and A01 using molecular docking and further have been confirmed during the course of 100 ns simulation. The stability of the D05 clone with PC was substantially higher.

Conclusion

IgG1 anti-PC was a stronger protection marker than IgG anti-PC and IgG2 anti-PC and also separately for men. The molecular modeling approach helps in identifying the intrinsic properties of anti-PC clones and atomistic interactions with PC.

Antibodies against phosphorylcholine in hospitalized versus non-hospitalized obese subjects

Obesity associates with reduced life expectancy, type 2 diabetes, hypertension and cardiovascular disease, and is characterized by chronic inflammation. Phosphorylcholine (PC) is an epitope on oxidized low-density lipoprotein, dead cells and some microorganisms. Antibodies against PC (anti-PC) have anti-inflammatory properties. Here, we explored the role of anti-PC in hospitalized versus non-hospitalized obese. One-hundred-and-twenty-eight obese (BMI ≥ 30 kg/m²) individuals (59.8 (± 5.5) years, 53.9% women) from the Malmö Diet and Cancer Cardiovascular Cohort were examined and IgM, IgG1 and IgG2 anti-PC were analyzed by ELISA. Individuals with at least one recorded history of hospitalization prior to study baseline were considered hospitalized obese (HO). Associations between IgM, IgG1 and IgG2 anti-PC and HO (n = 32)/non-hospitalized obese (NHO) (n = 96), but also with metabolic syndrome and diabetes were analysed using logistic regressions. Both IgM and IgG1 anti-PC were inversely associated with HO, also after controlling for age and sex. When further adjusted for waist circumference, systolic blood pressure, glucose levels and smoking status, only IgG1 anti-PC remained significantly associated with HO. In multivariate models, each 1 standard deviation of increment in anti-PC IgG1 levels was inversely associated with prevalence of HO (odds ratio 0.57; CI 95% 0.33–0.98; p = 0.044). IgG2 anti-PC did not show any associations with HO. Low levels of IgM and IgG1 anti-PC are associated with higher risk of being a HO individual independent of sex and age, IgG1 anti-PC also independently of diabetes and metabolic syndrome. The anti-inflammatory properties of these antibodies may be related to inflammation in obesity and its complications.