CD14 as a Mediator of the Mineralocorticoid Receptor-Dependent Anti-apolipoprotein A-1 IgG Chronotropic Effect on Cardiomyocytes

Anti-apolipoprotein A-1 IgG, incident cardiovascular events, and lipid paradox in rheumatoid arthritis

Objective

To validate the prognostic accuracy of anti-apolipoprotein A-1 (AAA1) IgG for incident major adverse cardiovascular (CV) events (MACE) in rheumatoid arthritis (RA) and study their associations with the lipid paradox at a multicentric scale.

Method

Baseline AAA1 IgG, lipid profile, atherogenic indexes, and cardiac biomarkers were measured on the serum of 1,472 patients with RA included in the prospective Swiss Clinical Quality Management registry with a median follow-up duration of 4.4 years. MACE was the primary endpoint defined as CV death, incident fatal or non-fatal stroke, or myocardial infarction (MI), while elective coronary revascularization (ECR) was the secondary endpoint. Discriminant accuracy and incidence rate ratios (IRR) were respectively assessed using C-statistics and Poisson regression models.

Results

During follow-up, 2.4% (35/1,472) of patients had a MACE, consisting of 6 CV deaths, 11 MIs, and 18 strokes; ECR occurred in 2.1% (31/1,472) of patients. C-statistics indicated that AAA1 had a significant discriminant accuracy for incident MACE [C-statistics: 0.60, 95% confidence interval (95% CI): 0.57-0.98, p = 0.03], mostly driven by CV deaths (C-statistics: 0.77; 95% CI: 0.57-0.98, p = 0.01). IRR indicated that each unit of AAA1 IgG increase was associated with a fivefold incident CV death rate, independent of models' adjustments. At the predefined and validated cut-off, AAA1 displayed negative predictive values above 97% for MACE. AAA1 inversely correlated with total and HDL cholesterol.

Conclusions

AAA1 independently predicts CV deaths, and marginally MACE in RA. Further investigations are requested to ascertain whether AAA1 could enhance CV risk stratification by identifying patients with RA at low CV risk.

People living with HIV display increased anti-apolipoprotein A1 auto-antibodies, inflammation, and kynurenine metabolites: a case-control study

Objective

This study aimed to study the relationship between auto-antibodies against apolipoprotein A1 (anti-apoA1 IgG), human immunodeficiency virus (HIV) infection, anti-retroviral therapy (ART), and the tryptophan pathways in HIV-related cardiovascular disease.

Design

This case-control study conducted in South Africa consisted of control volunteers (n = 50), people living with HIV (PLWH) on ART (n = 50), and untreated PLWH (n = 44). Cardiovascular risk scores were determined, vascular measures were performed, and an extensive biochemical characterisation (routine, metabolomic, and inflammatory systemic profiles) was performed.

Methods

Anti-apoA1 IgG levels were assessed by an in-house ELISA. Inflammatory biomarkers were measured with the Meso Scale Discovery® platform, and kynurenine pathway metabolites were assessed using targeted metabolomic profiling conducted by liquid chromatography-multiple reaction monitoring/mass spectrometry (LC-MRM/MS).

Results

Cardiovascular risk scores and vascular measures exhibited similarities across the three groups, while important differences were observed in systemic inflammatory and tryptophan pathways. Anti-apoA1 IgG seropositivity rates were 15%, 40%, and 70% in control volunteers, PLWH ART-treated, and PLWH ART-naïve, respectively. Circulating anti-apoA1 IgG levels were significantly negatively associated with CD4+ cell counts and positively associated with viremia and pro-inflammatory biomarkers (IFNγ, TNFα, MIPα, ICAM-1, VCAM-1). While circulating anti-apoA1 IgG levels were associated with increased levels of kynurenine in both control volunteers and PLWH, the kynurenine/tryptophan ratio was significantly increased in PLWH ART-treated.

Conclusion

HIV infection increases the humoral response against apoA1, which is associated with established HIV severity criteria and kynurenine pathway activation.

Autoantibodies against apolipoprotein A-1 after COVID-19 predict symptoms persistence

BACKGROUND

SARS-CoV-2 infection triggers different auto-antibodies, including anti-apolipoprotein A-1 IgGs (AAA1), which could be of concern as mediators of persistent symptoms. We determined the kinetics of AAA1 response over after COVID-19 and the impact of AAA1 on the inflammatory response and symptoms persistence.

METHODS

All serologies were assessed at one, three, six and twelve months in 193 hospital employees with COVID-19. ROC curve analyses and logistic regression models (LRM) were used to determine the prognostic accuracy of AAA1 and their association with patient-reported COVID-19 symptoms persistence at 12 months. Interferon (IFN)-α and-γ production by AAA1-stimulated human monocyte-derived macrophages (HMDM) was assessed in vitro.

RESULTS

AAA1 seropositivity was 93% at one month and declined to 15% at 12 months after COVID-19. Persistent symptoms at 12 months were observed in 45.1% of participants, with a predominance of neurological (28.5%), followed by general (15%) and respiratory symptoms (9.3%). Over time, strength of correlations between AAA1 and anti-SARS-COV2 serologies decreased, but remained significant. From the 3^rd month on, AAA1 levels predicted persistent respiratory symptoms (area under the curves 0.72-0.74; p < 0.001), independently of disease severity, age and gender (adjusted odds ratios 4.81-4.94; p = 0.02), while anti-SARS-CoV-2 serologies did not. AAA1 increased IFN-α production by HMDMs (p = 0.03), without affecting the IFN-γ response.

CONCLUSION

COVID-19 induces a marked though transient AAA1 response, independently predicting one-year persistence of respiratory symptoms. By increasing IFN-α response, AAA1 may contribute to persistent symptoms. If and how AAA1 levels assessment could be of use for COVID-19 risk stratification remains to be determined.

SARS-CoV-2 infection as a trigger of humoral response against apolipoprotein A-1

BACKGROUND

Unravelling autoimmune targets triggered by SARS-CoV-2 infection may provide crucial insights into the physiopathology of the disease and foster the development of potential therapeutic candidate targets and prognostic tools. We aimed at determining (a) the association between anti-SARS-CoV-2 and anti-apoA-1 humoral response and (b) the degree of linear homology between SARS-CoV-2, apoA-1 and Toll-like receptor 2 (TLR2) epitopes.

DESIGN

Bioinformatics modelling coupled with mimic peptides engineering and competition experiments were used to assess epitopes sequence homologies. Anti-SARS-CoV-2 and anti-apoA-1 IgG as well as cytokines were assessed by immunoassays on a case-control (n = 101), an intensive care unit (ICU; n = 126) and a general population cohort (n = 663) with available samples in the pre and post-pandemic period.

RESULTS

Using bioinformatics modelling, linear sequence homologies between apoA-1, TLR2 and Spike epitopes were identified but without experimental evidence of cross-reactivity. Overall, anti-apoA-1 IgG levels were higher in COVID-19 patients or anti-SARS-CoV-2 seropositive individuals than in healthy donors or anti-SARS-CoV-2 seronegative individuals (P < .0001). Significant and similar associations were noted between anti-apoA-1, anti-SARS-CoV-2 IgG, cytokines and lipid profile. In ICU patients, anti-SARS-CoV-2 and anti-apoA-1 seroconversion rates displayed similar 7-day kinetics, reaching 82% for anti-apoA-1 seropositivity. In the general population, SARS-CoV-2-exposed individuals displayed higher anti-apoA-1 IgG seropositivity rates than nonexposed ones (34% vs 16.8%; P = .004).

CONCLUSION

COVID-19 induces a marked humoral response against the major protein of high-density lipoproteins. As a correlate of poorer prognosis in other clinical settings, such autoimmunity signatures may relate to long-term COVID-19 prognosis assessment and warrant further scrutiny in the current COVID-19 pandemic.

Mineralocorticoid receptor in cardiovascular diseases-Clinical trials and mechanistic insights

Aldosterone binds to the mineralocorticoid receptor (NR3C2), a transcription factor of the nuclear receptor family, present in the kidney and in various other non-epithelial cells including the heart and the vasculature. Indeed, extra-renal pathophysiological effects of this hormone have been characterized, extending its actions to the cardiovascular system. A growing body of clinical and pre-clinical evidence suggests that mineralocorticoid receptor overactivation plays an important pathophysiological role in cardiovascular remodelling by promoting cardiac hypertrophy, fibrosis, arterial stiffness and in inflammation and oxidative stress. The following review article outlines the role of mineralocorticoid receptor in cardiovascular disease with a focus on myocardial remodelling and heart failure (HF) including clinical trials as well as cellular and animal studies.

B cell-derived anti-beta 2 glycoprotein I antibody contributes to hyperhomocysteinaemia-aggravated abdominal aortic aneurysm

AIMS

Overactivated B cells secrete pathological antibodies, which in turn accelerate the formation of abdominal aortic aneurysms (AAAs). Hyperhomocysteinaemia (HHcy) aggravates AAA in mice; however, the underlying mechanisms remain largely elusive. In this study, we further investigated whether homocysteine (Hcy)-activated B cells produce antigen-specific antibodies that ultimately contribute to AAA formation.

METHODS AND RESULTS

ELISA assays showed that HHcy induced the secretion of anti-beta 2 glycoprotein I (anti-β2GPI) antibody from B cells both in vitro and in vivo. Mechanistically, Hcy increased the accumulation of various lipid metabolites in B cells tested by liquid chromatography-tandem mass spectrometry, which contributed to elevated anti-β2GPI IgG secretion. By using the toll-like receptor 4 (TLR4)-specific inhibitor TAK-242 or TLR4-deficient macrophages, we found that culture supernatants from Hcy-activated B cells and HHcy plasma IgG polarized inflammatory macrophages in a TLR4-dependent manner. In addition, HHcy markedly increased the incidence of elastase- and CaPO4-induced AAA in male BALB/c mice, which was prevented in μMT mice. To further determine the importance of IgG in HHcy-aggravated AAA formation, we purified plasma IgG from HHcy or control mice and then transferred the IgG into μMT mice, which were subsequently subjected to elastase- or CaPO4-induced AAA. Compared with μMT mice that received plasma IgG from control mice, μMT mice that received HHcy plasma IgG developed significantly exacerbated elastase- or CaPO4-induced AAA accompanied by increased elastin degradation, MMP2/9 expression, and anti-β2GPI IgG deposition in vascular lesions, as shown by immunofluorescence histochemical staining.

CONCLUSION

Our findings reveal a novel mechanism by which Hcy-induced B cell-derived pathogenic anti-β2GPI IgG might, at least in part, contribute to HHcy-aggravated chronic vascular inflammation and AAA formation.

Auto-antibodies against apolipoprotein A-1 block cancer cells proliferation and induce apoptosis

Auto-antibodies against apoA-1 (anti-apoA-1 IgGs) have been identified as important actors of atherosclerosis development through pro-inflammatory and pro-atherogenic properties and to also induce apoptosis in tumoral neuronal and lymphocyte derived cell lines through unknown mechanisms. The purpose of this study was to explore the cellular pathways involved in tumoral cell survival modulated by anti-apoA-1 antibodies. We observed that anti-apoA-1 antibodies induce growth arrest (in G2/M phase) and cell apoptosis through caspase 3 activation, accompanied by a selective p53 phosphorylation on serine 15. RNA sequencing indicated that anti-apoA-1 IgGs affect the expression of more than 950 genes belonging to five major groups of genes and respectively involved in i) cell proliferation inhibition, ii) p53 stabilisation and regulation, iii) apoptosis regulation, iv) inflammation regulation, and v) oxidative stress. In conclusion, anti-apoA-1 antibodies seem to have a role in blocking tumoral cell proliferation and survival, by activating a major tumor suppressor protein and by modulating the inflammatory and oxidative stress response. Further investigations are needed to explore a possible anti-cancer therapeutic approach of these antibodies in very specific and circumscribed conditions.

Atherosclerotic plaque vulnerability is increased in mouse model of lupus

Anti-apolipoprotein A-1 (anti-apoA-1 IgG) and anti-double stranded DNA (anti-dsDNA IgG) autoantibodies have been described as mediators of atherogenesis in mice and humans. In the present study, we aim to investigate the association between atherosclerotic parameters, autoantibodies and plaque vulnerability in the context of systemic lupus erythematosus (SLE). We therefore bred a lupus prone-mouse model (Nba2.Yaa mice) with Apoe-/- mice resulting in Apoe-/-Nba2.Yaa mice spontaneously producing anti-apoA-1 IgG antibodies. Although Apoe-/-Nba2.Yaa and Apoe-/- mice subject to a high cholesterol diet displayed similar atherosclerosis lesions size in aortic roots and abdominal aorta, the levels of macrophage and neutrophil infiltration, collagen, MMP-8 and MMP-9 and pro-MMP-9 expression in Apoe-/-Nba2.Yaa mice indicated features of atherosclerotic plaque vulnerability. Even though Apoe-/-Nba2.Yaa mice and Apoe-/- mice had similar lipid levels, Apoe-/-Nba2.Yaa mice showed higher anti-apoA-1 and anti-dsDNA IgG levels. Apoe-/-Nba2.Yaa mice displayed a reduction of the size of the kidney, splenomegaly and lymph nodes (LN) hypertrophy. In addition, anti-apoA-1 and anti-dsDNA IgG increased also in relation with mRNA levels of GATA3, IL-4, Bcl-6 and CD20 in the spleen and aortic arch of Apoe-/-Nba2.Yaa mice. Our data show that although atherosclerosis-lupus-prone Apoe-/-Nba2.Yaa mice did not exhibit exacerbated atherosclerotic lesion size, they did show features of atherosclerotic plaque destabilization in correlation with the increase of pro-atherogenic autoantibodies.

Anti-apolipoprotein A-1 autoantibodies correlate with disease activity in systemic lupus erythematosus

OBJECTIVES

Apolipoprotein A-1 (ApoA-1) is a protein fraction of the high-density lipoproteins with anti-inflammatory and antioxidant properties that play a major role in reverse cholesterol transport. The presence of anti-ApoA-1 IgG has been reported in SLE to be variably associated with disease activity or cardiovascular events (CVEs). We assessed the clinical performance of anti-ApoA-1 IgG and of antibodies directed against its immunodominant F3L1 peptide (F3L1 IgG) in a well-characterized Swiss SLE cohort study.

METHODS

A total of 354 biological samples and interviews from 176 individuals were studied. SLEDAI, clinical characteristics, anamnestic CVEs and therapy details were recorded. Sera were tested for the presence of anti-ApoA-1 IgG, anti-F3L1 IgG, anti-dsDNA IgG and aPL.

RESULTS

Anti-ApoA-1 and anti-F3L1 IgG positivity was associated with higher SLEDAI, mostly due to concomitant positivity of dsDNA IgG and low complement. Variations in time of anti-ApoA-1 IgG correlated positively with variations of anti-dsDNA IgG and inversely to variations of C3 levels. No cross-reactivity was found between anti-ApoA-1 and anti-dsDNA IgG. Positivity for anti-Apo-A1 IgG was more frequent in individuals receiving 10 mg/day or more of prednisone. We did not find any significant association between anti-ApoA-1 IgG positivity and CVEs.

CONCLUSION

Anti-ApoA-1 and anti-F3L1 IgG in SLE correlate strongly with laboratory markers of activity, particularly with the presence and titre of dsDNA IgG. These results confirm and extend previous findings and support the use of anti-ApoA1 IgG in the clinical setting. Their role in CVEs deserves further investigation.

Humoral Immunity Against HDL Particle: A New Perspective in Cardiovascular Diseases?

BACKGROUND

Autoimmune diseases are closely associated with cardiovascular diseases (CVD). Over the last decades, the comprehension of atherosclerosis, the principal initiator of CVD, evolved from a lipidcentered disease to a predominant inflammatory and immune response-driven disease displaying features of autoimmunity against a broad range of auto-antigens, including lipoproteins. Among them, high density lipoproteins (HDL) are important actors of cholesterol transport and bear several anti-atherogenic properties, raising a growing interest as therapeutic targets to decrease atherosclerosis and CVD burden, with nevertheless rather disappointing results so far. Reflecting HDL composition complexity, autoimmune responses and autoantibodies against various HDL components have been reported.

RESULTS

In this review, we addressed the important complexity of humoral autoimmunity towards HDL and particularly how this autoimmune response could help improving our understanding of HDL biological implication in atherosclerosis and CVD. We also discussed several issues related to specific HDL autoantibody subclasses characteristics, including etiology, prognosis and pathological mechanisms according to Rose criteria.

CONCLUSION

Finally, we addressed the possible clinical value of using these antibodies not only as potential biomarkers of atherogenesis and CVD, but also as a factor potentially mitigating the benefit of HDL-raising therapies.

A New Role for the Aldosterone/Mineralocorticoid Receptor Pathway in the Development of Mitral Valve Prolapse

RATIONALE

Mitral valve prolapse (MVP) is one of the most common valvular disorders. However, the molecular and cellular mechanisms involved in fibromyxomatous changes in the mitral leaflet tissue have not been elucidated. Aldosterone (Aldo) promotes fibrosis in myocardium, and MR (mineralocorticoid receptor) antagonists (MRAs) improve cardiac function by decreasing cardiac fibrosis.

OBJECTIVE

We investigated the role of the Aldo/MR in the fibromyxomatous modifications associated with MVP.

METHODS AND RESULTS

Aldo enhanced valvular interstitial cell activation markers and induced endothelial-mesenchymal transition in valvular endothelial cells, resulting in increased proteoglycan secretion. MRA blocked all the above effects. Cytokine arrays showed CT-1 (cardiotrophin-1) to be a mediator of Aldo-induced valvular interstitial cell activation and proteoglycan secretion and CD (cluster of differentiation) 14 to be a mediator of Aldo-induced endothelial-mesenchymal transition and proteoglycan secretion in valvular endothelial cells. In an experimental mouse model of MVP generated by nordexfenfluramine administration, MRA treatment reduced mitral valve thickness and proteoglycan content. Endothelial-specific MR deletion prevented fibromyxomatous changes induced by nordexfenfluramine administration. Moreover, proteoglycan expression was slightly lower in the mitral valves of MVP patients treated with MRA.

CONCLUSIONS

These findings demonstrate, for the first time, that the Aldo/MR pathway regulates the phenotypic, molecular, and histological changes of valvular interstitial cells and valvular endothelial cells associated with MVP development. MRA treatment appears to be a promising option to reduce fibromyxomatous alterations in MVP.

Relationship between HDL Cholesterol Efflux Capacity, Calcium Coronary Artery Content, and Antibodies against ApolipoproteinA-1 in Obese and Healthy Subjects

AIMS

To explore the associations between cholesterol efflux capacity (CEC), coronary artery calcium (CAC) score, Framingham risk score (FRS), and antibodies against apolipoproteinA-1 (anti-apoA-1 IgG) in healthy and obese subjects (OS).

METHODS AND RESULTS

ABCA1-, ABCG1-, passive diffusion (PD)-CEC and anti-apoA-1 IgG were measured in sera from 34 controls and 35 OS who underwent CAC score determination by chest computed tomography. Anti-apoA-1 IgG ability to modulate CEC and macrophage cholesterol content (MCC) was tested in vitro. Controls and OS displayed similar ABCG1-, ABCA1-, PD-CEC, CAC and FRS scores. Logistic regression analyses indicated that FRS was the only significant predictor of CAC lesion. Overall, anti-apoA-1 IgG were significantly correlated with ABCA1-CEC (r = 0.48, p < 0.0001), PD-CEC (r = -0.33, p = 0.004), and the CAC score (r = 0.37, p = 0.03). ABCA1-CEC was correlated with CAC score (r = 0.47, p = 0.004) and FRS (r = 0.18, p = 0.29), while PD-CEC was inversely associated with the same parameters (CAC: r = -0.46, p = 0.006; FRS: score r = -0.40, p = 0.01). None of these associations was replicated in healthy controls or after excluding anti-apoA-1 IgG seropositive subjects. In vitro, anti-apoA-1 IgG inhibited PD-CEC (p < 0.0001), increased ABCA1-CEC (p < 0.0001), and increased MCC (p < 0.0001).

CONCLUSIONS

We report a paradoxical positive association between ABCA1-CEC and the CAC score, with the latter being inversely associated with PD in OS. Corroborating our clinical observations, anti-apoA-1 IgG enhanced ABCA1 while repressing PD-CEC, leading to MCC increase in vitro. These results indicate that anti-apoA-1 IgG have the potential to interfere with CEC and macrophage lipid metabolism, and may underpin paradoxical associations between ABCA1-CEC and cardiovascular risk.

Anti-apolipoprotein A-1 autoantibodies are associated with immunodeficiency and systemic inflammation in HIV patients

OBJECTIVES

To determine the existence of autoantibodies against apolipoprotein A-1 (anti-apoA-1 IgG) in HIV patients and explore their association with biological features of HIV infection and different inflammatory biomarkers. We also evaluated their impact on CD4+ lymphocytes survival.

METHODS

Anti-apoA-1 IgG plasma levels were assessed by ELISA in 237 HIV positive patients from a national prospective cohort with no current lipid-lowering therapy.

RESULTS

58% of patients were found positive for anti-apoA-1 IgG and were associated with lower CD4+ counts, but higher viremia and systemic inflammation. Logistic regression analyses indicated that high anti-apoA-1 IgG levels were associated with a 16-fold increased risk of displaying low CD4+ levels, independent of HIV RNA levels and treatment (adjusted Odds ratio [OR]:16.1, 95% Confidence Interval [95%CI]:1.80-143.6; p = 0.01), and a 6-fold increased risk of having a detectable viremia, independent of antiretroviral treatment (OR:5.47; 95% CI:1.63-18.36; p = 0.006). In vitro, anti-apoA-1 IgG induced dose and time-dependent CD4+ apoptosis that was increased by exposure to HIV RNA.

CONCLUSIONS

In HIV patients, anti-apoA-1 IgG levels are associated with low CD4+ counts, high viremia and a pro-inflammatory systemic profile. Anti-apoA-1 IgG can promote CD4+ lymphocyte apoptosis via undefined pathways.

Pharmacological Intervention to Modulate HDL: What Do We Target?

The cholesterol concentrations of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) have traditionally served as risk factors for cardiovascular disease. As such, novel therapeutic interventions aiming to raise HDL cholesterol have been tested in the clinical setting. However, most trials led to a significant increase in HDL cholesterol with no improvement in cardiovascular events. The complexity of the HDL particle, which exerts multiple physiological functions and is comprised of a number of subclasses, has raised the question as to whether there should be more focus on HDL subclass and function rather than cholesterol quantity. We review current data regarding HDL subclasses and subclass-specific functionality and highlight how current lipid modifying drugs such as statins, cholesteryl ester transfer protein inhibitors, fibrates and niacin often increase cholesterol concentrations of specific HDL subclasses. In addition this review sets out arguments suggesting that the HDL3 subclass may provide better protective effects than HDL2.

Toll-Like Receptor 9 Promotes Survival in SERCA2a KO Heart Failure Mice

Aim. Inflammation is important in heart failure (HF). The role of the immune receptor toll-like receptor 9 (TLR9) in HF is not understood and not investigated in diastolic HF. We investigated the role of TLR9 in a murine diastolic HF model caused by cardiomyocyte SERCA2a excision. Methods and Results. We crossed SERCA2a KO and TLR9 KO mice to generate four mouse lines. Tamoxifen-induced cardiomyocyte SERCA2a gene excision was carried out in mice, causing diastolic HF. After 7.6 weeks, cardiac functions and dimensions were analyzed by echocardiography and heart tissues were processed. HF mice depleted of TLR9 demonstrated reduced survival compared to SERC2a KO mice, with a median life expectancy of 58 days compared to 63 days. Both HF groups displayed increased left atrium size, lung weight, fetal gene expressions, monocyte/macrophage infiltration, and fibrosis. However, there were no significant differences between the groups. Conclusion. In mice with SERCA2a KO-induced diastolic HF, the absence of TLR9 reduced median life expectancy. The cause remains elusive, as all investigated HF parameters were unaltered. Still, these findings support a salutary role of TLR9 in some subsets of HF conditions and underline the importance for future studies on the mechanisms of TLR9 in diastolic HF.

Association between anti-apolipoprotein A-1 antibodies and cardiovascular disease in the general population. Results from the CoLaus study

We aimed to determine the association between autoantibodies against apolipoprotein A-1 (anti-apoA-1 IgG) and prevalent cardiovascular (CV) disease (CVD) as well as markers of CV risk in the general population. Cross-sectional data were obtained from 6649 subjects (age 52.6 ± 10.7 years, 47.4 % male) of the population-based CoLaus study. CVD was defined as myocardial infarction, angina pectoris, percutaneous revascularisation or bypass grafting for ischaemic heart disease stroke or transient ischaemic attack, and was assessed according to standardised medical records. Anti-apoA-1 IgG and biological markers were measured by ELISA and conventional automated techniques, respectively. Prevalence of high anti-apoA-1 IgG levels in the general population was 19.9 %. Presence of anti-apoA-1 IgG was significantly associated with CVD [odds ratio 1.34, 95 % confidence interval (1.05-1.70), p=0.018], independently of established CV risk factors (CVRFs) including age, sex, hypertension, smoking, diabetes, low and high-density lipoprotein cholesterol levels. The n=455 (6.8 %) study participants with a history of CVD (secondary prevention subgroup) presented higher median anti-ApoA-1 IgG values compared with subjects without CVD (p=0.029). Among patients in the secondary prevention subgroup, those with positive anti-apoA-1 IgG levels had lower HDL (p=0.002) and magnesium (p=0.001) levels, but increased uric acid and high-sensitivity C-reactive protein levels (p=0.022, and p<0.001, respectively) compared to patients with negative anti-apoA-1 IgG levels. In conclusion, anti-apoA-1 IgG levels are independently associated with CVD in the general population and also related to CV biomarkers in secondary prevention. These findings indicate that anti-apoA-1 IgG may represent a novel CVRF and need further study in prospective cohorts.

Anti-ApoA-1 IgG serum levels predict worse poststroke outcomes

BACKGROUND

Autoantibodies to apolipoprotein A-1 (anti-ApoA-1 IgG) were shown to predict major adverse cardiovascular events and promote atherogenesis. However, their potential relationship with clinical disability and ischaemic lesion volume after acute ischaemic stroke (AIS) remains unexplored.

MATERIALS AND METHODS

We included n = 76 patients admitted for AIS and we investigated whether baseline serum anti-ApoA-1 IgG levels could predict (i) AIS-induced clinical disability [assessed by the modified Rankin Scale (mRS)], and (ii) AIS-related ischaemic lesion volume [assessed by Computed Tomography (CT)]. We also evaluated the possible pro-apoptotic and pro-necrotic effects of anti-ApoA-1 IgG on human astrocytoma cell line (U251) using flow cytometry.

RESULTS

High levels of anti-ApoA-1 IgG were retrieved in 15·8% (12/76) of patients. Increased baseline levels of anti-ApoA-1 IgG were independently correlated with worse mRS [β = 0·364; P = 0·002; adjusted odds ratio (OR): 1·05 (95% CI 1·01-1·09); P = 0·017] and CT-assessed ischaemic lesion volume [β = 0·333; P < 0·001; adjusted OR: 1·06 (95% CI 1·01-1·12); P = 0·048] at 3 months. No difference in baseline clinical, biochemical and radiological characteristics was observed between patients with high vs. low levels of anti-ApoA-1 IgG. Incubating human astrocytoma cells with anti-ApoA-1 IgG dose dependently induced necrosis and apoptosis of U251 cells in vitro.

CONCLUSION

Anti-ApoA-1 IgG serum levels at AIS onset are associated with poorer clinical recovery and worse brain lesion volume 3 months after AIS. These observations could be partly explained by the deleterious effect of anti-ApoA-1 IgG on human brain cell survival in vitro and may have clinical implication in the prediction of poor outcome in AIS.

Spironolactone promotes autophagy via inhibiting PI3K/AKT/mTOR signalling pathway and reduce adhesive capacity damage in podocytes under mechanical stress

Mechanical stress which would cause deleterious adhesive effects on podocytes is considered a major contributor to the early progress of diabetic nephropathy (DN). Our previous study has shown that spironolactone could ameliorate podocytic adhesive capacity in diabetic rats. Autophagy has been reported to have a protective role against renal injury. The present study investigated the underlying mechanisms by which spironolactone reduced adhesive capacity damage in podocytes under mechanical stress, focusing on the involvement of autophagy. Human conditional immortalized podocytes exposed to mechanical stress were treated with spironolactone, LY294002 or rapamycin for 48 h. The accumulation of LC3 puncta was detected by immunofluorescence staining. Podocyte expression of mineralocorticoid receptor (MR), integrin β1, LC3, Atg5, p85-PI3K, p-Akt, p-mTOR were detected by Western blotting. Podocyte adhesion to collagen type IV was also performed with spectrophotometry. Immunofluorescence staining showed that the normal level of autophagy was reduced in podocytes under mechanical stress. Decreased integrin β1, LC3, Atg5 and abnormal activation of the PI3K/Akt/mTOR pathway were also detected in podocytes under mechanical stress. Spironolactone up-regulated integrin β1, LC3, Atg5 expression, down-regulated p85-PI3K, p-Akt, p-mTOR expression and reduced podocytic adhesive capacity damage. Our data demonstrated that spironolactone inhibited mechanical-stress-induced podocytic adhesive capacity damage through blocking PI3K/Akt/mTOR pathway and restoring autophagy activity.

ApoA1 and ApoA1-specific self-antibodies in cardiovascular disease

Apolipoprotein A1 (ApoA1) is a main protein moiety in high-density lipoprotein (HDL) particles. Generally, ApoA1 and HDL are considered as atheroprotective. In prooxidant and inflammatory microenvironment in the vicinity to the atherosclerotic lesion, ApoA1/HDL are subjected to modification. The chemical modifications such as oxidation, nitration, etc result in altering native architecture of ApoA1 toward dysfunctionality and abnormality. Neutrophil myeloperoxidase has a prominent role in this mechanism. Neo-epitopes could be formed and then exposed that makes them immunogenic. Indeed, these epitopes may be recognized by immune cells and induce production of proatherogenic ApoA1-specific IgG antibodies. These antibodies are biologically relevant because they are able to react with Toll-like receptor (TLR)-2 and TLR4 in target cells and induce a variety of pro-inflammatory responses. Epidemiological and functional studies underline a prognostic value of ApoA1 self-antibodies for several cardiovascular diseases, including myocardial infarction, acute coronary syndrome, and severe carotid stenosis.