Pathophysiological role of neutrophils in acute myocardial infarction

The pathogenesis of acute myocardial infarction is known to be mediated by systemic, intraplaque and myocardial inflammatory processes. Among different immune cell subsets, compelling evidence now indicates a pivotal role for neutrophils in acute coronary syndromes. Neutrophils infiltrate coronary plaques and the infarcted myocardium and mediate tissue damage by releasing matrix-degrading enzymes and reactive oxygen species. In addition, neutrophils are also involved in post-infarction adverse cardiac remodelling and neointima formation after angioplasty. The promising results obtained in preclinical modelswith pharmacological approaches interfering with neutrophil recruitment or function have confirmed the pathophysiological relevance of these immune cells in acute coronary syndromes and prompted further studies of these therapeutic interventions. This narrative review will provide an update on the role of neutrophils in acute myocardial infarction and on the pharmacological means that were devised to prevent neutrophil-mediated tissue damage and to reduce post-ischaemic outcomes.

Validation of a commercially available SARS-CoV-2 serological immunoassay

OBJECTIVES

To validate the diagnostic accuracy of a Euroimmun SARS-CoV-2 IgG and IgA immunoassay for COVID-19.

METHODS

In this unmatched (1:2) case-control validation study, we used sera of 181 laboratory-confirmed SARS-CoV-2 cases and 326 controls collected before SARS-CoV-2 emergence. Diagnostic accuracy of the immunoassay was assessed against a whole spike protein-based recombinant immunofluorescence assay (rIFA) by receiver operating characteristic (ROC) analyses. Discrepant cases between ELISA and rIFA were further tested by pseudo-neutralization assay.

RESULTS

COVID-19 patients were more likely to be male and older than controls, and 50.3% were hospitalized. ROC curve analyses indicated that IgG and IgA had high diagnostic accuracies with AUCs of 0.990 (95% Confidence Interval [95%CI]: 0.983-0.996) and 0.978 (95%CI: 0.967-0.989), respectively. IgG assays outperformed IgA assays (p=0.01). Taking an assessed 15% inter-assay imprecision into account, an optimized IgG ratio cut-off > 2.5 displayed a 100% specificity (95%CI: 99-100) and a 100% positive predictive value (95%CI: 96-100). A 0.8 cut-off displayed a 94% sensitivity (95%CI: 88-97) and a 97% negative predictive value (95%CI: 95-99). Substituting the upper threshold for the manufacturer's, improved assay performance, leaving 8.9% of IgG ratios indeterminate between 0.8-2.5.

CONCLUSIONS

The Euroimmun assay displays a nearly optimal diagnostic accuracy using IgG against SARS-CoV-2 in patient samples, with no obvious gains from IgA serology. The optimized cut-offs are fit for rule-in and rule-out purposes, allowing determination of whether individuals in our study population have been exposed to SARS-CoV-2 or not. IgG serology should however not be considered as a surrogate of protection at this stage.

Cardiac biomarkers for risk stratification in non-massive pulmonary embolism: a multicenter prospective study

BACKGROUND

Troponins (cTnI and cTnT), N-terminal pro-Brain Natriuretic Peptide (NT-proBNP), myoglobin, heart-type fatty acid-binding protein (H-FABP) and fibrin D-Dimer are emergent candidates for risk stratification in pulmonary embolism (PE).

OBJECTIVE

To compare the respective prognostic values of biomarker with non-massive PE to predict an adverse outcome at 3 months.

PATIENTS/METHODS

One hundred and forty-six consecutive patients with non-massive PE were included in this multicenter prospective study. The combined outcome consisted of intensive care monitoring on admission, death or hospitalization attributable to either a PE-related complication [defined by PE/deep vein thrombosis (DVT) relapse or major bleeding under anticoagulation] or to dyspnoea with or without chest pain during follow-up.

RESULTS

The outcome was met in 12% of patients. In univariate analysis, a NT-proBNP level above 300 pg/ml was the strongest predictor of unfavorable outcome with an odds ratio (OR) of 15.8 [95% confidence interval (CI): 2.05-122). ORs for the other variables were: 8.0 for D-dimer >2000 ng/ml (95% CI: 1.1-64), 4.7 for H-FABP >6 ng/ml (95% CI:1.5-14.8), 3.5 for cTnI >0.09 ng/ml (95% CI:1.2-9.7), 3.4 for myoglobin >70 ng/ml (95% CI:0.9-12.2). Receiver operating curve (ROC) analysis indicated that NT-proBNP was the best predictor [area under the curve (AUC) 0.84; 95%CI: 0.76-0.92; P < 0.0001] with a negative predictive value of 100% (95% CI: 91-100) at 300 pg/ml. At that cut-off, the true negative rate for NT-proBNP was 40%. In multivariate analysis, NT-proBNP was the only significant independent predictors.

CONCLUSIONS

NT-proBNP appears to be a good risk stratification marker in identifying low-risk patients with non-massive PE who could be treated in an outpatient setting.

Anti-apolipoprotein A-1 IgG in patients with myocardial infarction promotes inflammation through TLR2/CD14 complex

OBJECTIVES

Toll-like receptor (TLR)-mediated vascular inflammation, inducible by - amongst other factors - auto-antibodies, is increasingly recognized as a potential mediator of cardiovascular disease. We investigated whether anti-apolipoprotein (Apo)A-1 IgG was associated with a pro-inflammatory cytokine profile in myocardial infarction (MI) patients and whether anti-ApoA-1 IgG elicited a pro-inflammatory response by activating TLRs.

METHODS

As surrogate markers of atherosclerotic plaque vulnerability, interleukin (IL)-6, tumour necrosis factor (TNF)-α, matrix metalloproteinase (MMP)-9 and MMP-3 levels were assessed in 221 consecutive MI patients. Using human monocyte-derived macrophages (HMDMs) we investigated (i) the anti-ApoA-1 IgG interaction with TLRs using proximity ligation assay and (ii) anti-ApoA-1 IgG-dependent IL-6/TNF-α production. TLR involvement was further confirmed using HEK293-Blue TLR-2/-4 cells and by computational docking simulations.

RESULTS

In MI patients, anti-ApoA-1 IgG positivity was associated with higher levels of IL-6, TNF-α and MMP-9, but lower MMP-3 levels. In in vitro experiments, anti-ApoA-1 antibodies bound to HDMDs in a TLR2-dependent manner, resulting in nuclear translocation of NFκB and a significant increase in TNF-α and IL-6 production. Subsequent functional studies highlighted the importance of CD14 as co-receptor in the anti-ApoA-1 IgG-TLR2-induced cytokine production. Additional bioinformatic studies identified structural homologies between TLR2 and ApoA-1, which may explain the observed cross-reactivity between antibodies against these two molecules.

CONCLUSIONS

Anti-ApoA-1 IgG positivity in MI is associated with a high-risk cytokine profile. These auto-antibodies promote inflammation by stimulating the TLR2/CD14 receptor complex, probably because of molecular mimicry, which may contribute to atherosclerosis-related complications in patients.

Anti-apoA-1 IgG and oxidized LDL are raised in rheumatoid arthritis (RA): potential associations with cardiovascular disease and RA disease activity

OBJECTIVE

To determine whether emerging cardiovascular risk factors such as anti-apolipoprotein A-1 (anti-apoA-1) immunoglobulin (Ig)G and oxidized low density lipoprotein (oxLDL) are associated with cardiovascular disease (CVD), carotid intima-media thickness (IMT), and disease activity in rheumatoid arthritis (RA).

METHOD

We determined the aforementioned associations in 69 RA patients with disease duration of 5 years and 46 controls matched by age, sex, and smoking status. Anti-apoA-1 IgG and oxLDL were measured by enzyme-linked immunosorbent assay (ELISA). Carotid arteries were examined by ultrasound. Disease Activity Score calculated on 28 joints (DAS28) was used to assess disease activity.

RESULTS

CVD prevalence was higher among RA patients than controls (17% vs. 2%, p = 0.01) but there was no difference in IMT (median: 0.67 vs. 0.66, p = 0.33). RA patients had a higher anti-apoA-1 IgG prevalence than controls (20% vs. 0%, p = 0.001). Anti-apoA-1 IgG and oxLDL levels were higher in cases than controls [median: 0.33 vs. 0.175 optical density (OD), p = 0.03; and 121 vs. 37.2 U/L, p = 0.0001, respectively]. Anti-apoA-1 IgG-positive patients had higher levels of oxLDL (median: 140.5 vs. 112 U/L, p = 0.01) than those tested negative. Receiver operating characteristic (ROC) curve analysis showed that only anti-apoA-1 IgG was a modest but significant predictor of CVD [area under the curve (AUC) = 0.65, p = 0.03] in RA patients. oxLDL was significantly associated with RA disease activity, whereas anti-apoA-1 IgG was not.

CONCLUSIONS

Anti-apoA-1 IgG could be a marker of CVD in RA, whereas oxLDL levels seem to reflect RA disease activity. Other causes of CVD than a general increase in atherosclerosis (as determined by IMT measurements) including plaque stability may therefore be of importance to explain the increased incidence of CVD in RA.

Evidence on the pathogenic role of auto-antibodies in acute cardiovascular diseases

Atherothrombosis is the major determinant of acute ischaemic cardiovascular events, such as myocardial infarction and stroke. Inflammatory processes have been linked to all phases of atherogenesis In particular, the identification of autoimmunity mediators in the complex microenvironment of chronic inflammation has become the focus of attention in both early and advanced atherogenic processes. Auto-antibodies against self-molecules or new epitopes generated by oxidative processes infiltrate atherosclerotic plaques and were shown to modulate the activity of immune cells by binding various types of receptors. However, despite mounting evidence for a pathophysiological role of autoantibodies in atherothrombosis, the clinical relevance for circulating autoantibodies in cardiovascular outcomes is still debated. This review aims at illustrating the mechanisms by which different types of autoantibodies might either promote or repress atherothrombosis and to discuss the clinical studies assessing the role of auto-antibodies as prognostic biomarkers of plaque vulnerability.

Anti-apoA-1 auto-antibodies increase mouse atherosclerotic plaque vulnerability, myocardial necrosis and mortality triggering TLR2 and TLR4

Auto-antibodies to apolipoprotein A-1 (anti-apoA-1 IgG) were shown to promote inflammation and atherogenesis, possibly through innate immune receptors signalling. Here, we aimed at investigating the role of Toll-like receptors (TLR) 2 and 4 on anti-apoA-1 IgG-induced atherosclerotic plaque vulnerability, myocardial necrosis and mortality in mice. Adult male apolipoprotein E knockout (ApoE)-/- (n=72), TLR2-/-ApoE-/- (n=36) and TLR4-/-Apo-/- (n=28) mice were intravenously injected with 50 µg/mouse of endotoxin-free polyclonal anti-apoA-1 IgG or control isotype IgG (CTL IgG) every two weeks for 16 weeks. Atherosclerotic plaque size and vulnerability were assessed by histology. Myocardial ischaemia and necrosis, respectively, were determined by electrocardiographic (ECG) changes assessed by telemetry and serum troponin I (cTnI) measurements. Impact on survival was assessed by Kaplan-Meier analyses. In ApoE-/- mice, anti-apoA-1 IgG passive immunisation enhanced histological features of atherosclerotic plaque vulnerability (increase in neutrophil and MMP-9 and reduction in collagen content), induced a substantial cTnI elevation (p=0.001), and increased mortality rate by 23 % (LogRank, p=0.04) when compared to CTL IgG. On a subgroup of ApoE-/- mice equipped with telemetry (n=4), a significant ST-segment depression was noted in anti-apoA-1 IgG-treated mice when compared to CTL IgG recipients (p< 0.001), and an acute ST-segment elevation myocardial infarction preceding mouse death was observed in one case. The deleterious effects of anti-apoA-1 IgG on atherosclerotic plaque vulnerability, myocardial necrosis and death were partially reversed in TLR2-/-ApoE-/- and TLR4-/-ApoE-/- backgrounds. In conclusion, anti-apoA-1 auto-antibodies seem to be active mediators of atherosclerotic plaque vulnerability, myocardial necrosis, and mortality in mice through TLR2- and TLR4-mediated pathways.

Autoantibodies against apolipoprotein A-1 and phosphorylcholine for diagnosis of non-ST-segment elevation myocardial infarction

OBJECTIVES

To explore the diagnostic accuracies of anti-apolipoproteinA-1 (anti-ApoA-1) IgG and anti-phosphorylcholine (anti-PC) IgM alone, expressed as a ratio (anti-ApoA-1 IgG/anti-PC IgM), and combined with the Thrombolysis In Myocardial Infarction (TIMI) score for non-ST-segment elevation myocardial infarction (NSTEMI) (NSTEMI-TIMI score) to create a new diagnostic algorithm - the Clinical Autoantibody Ratio (CABR) score - for the diagnosis of NSTEMI and subsequent cardiac troponin I (cTnI) elevation in patients with acute chest pain (ACP).

METHODS

In this single-centre prospective study, 138 patients presented at the emergency department with ACP without ST-segment elevation myocardial infarction. Anti-ApoA-1 IgG and anti-PC IgM were assessed by enzyme-linked immunosorbent assay on admission. Post hoc determination of the CABR score cut-off was performed by receiver operating characteristics analyses.

RESULTS

The adjudicated final diagnosis was NSTEMI in 17% (24/138) of patients. Both autoantibodies alone were found to be significant predictors of NSTEMI diagnosis, but the CABR score had the best diagnostic accuracy [area under the curve (AUC): 0.88; 95% confidence interval (CI): 0.82-0.95]. At the optimal cut-off of 3.3, the CABR score negative predictive value (NPV) was 97% (95% CI: 90-99). Logistic regression analysis showed that a CABR score >3.3 increased the risk of subsequent NSTEMI diagnosis 19-fold (odds ratio: 18.7; 95% CI: 5.2-67.3). For subsequent cTnI positivity, only anti-ApoA-1 IgG and CABR score displayed adequate predictive accuracies with AUCs of 0.80 (95% CI: 0.68-0.91) and 0.82 (95% CI: 0.70-0.94), respectively; the NPVs were 95% (95% CI: 90-98) and 99% (95% CI: 94-100), respectively.

CONCLUSION

The CABR score, derived from adding the anti-ApoA-1 IgG/anti-PC IgM ratio to the NSTEMI-TIMI score, could be a useful measure to rule out NSTEMI in patients presenting with ACP at the emergency department without electrocardiographic changes.

Auto-antibodies as emergent prognostic markers and possible mediators of ischemic cardiovascular diseases

During the last 15 years, a growing body of evidence supported the fact that auto-antibodies represent not only emergent markers but also active mediators of cardiovascular disease (CVD), clinically represented mostly by acute coronary syndrome (ACS) and stroke. There is a contrasted relationship between auto-antibodies and CVD, some being protective, while others acting as potential risk factors. Therefore, we performed a review of the literature on the respective cardiovascular prognostic value of the most relevant auto-antibodies in ACS and stroke, and their putative pathophysiological properties in atherogenesis. This review highlights auto-antibodies as active modulators of the innate immune system in atherogenesis (either toward a pro- or anti-inflammatory response), or by affecting basal heart rate regulation (anti-apoA-1 IgG). Given their apparent prognostic independency towards traditional cardiovascular risk factors, the data available in the literature indicates that some of those auto-antibodies could be of valuable help for cardiovascular risk stratification in the future, especially because their deleterious effects have been shown to be potentially abrogated in vivo and in vitro by existing therapeutic modalities. Although evidence in humans is currently lacking, these studies may open innovative therapeutic perspectives for CVD in the future.

Anti-apolipoprotein A-1 autoantibodies as biomarker for atherosclerosis burden in patients with periodontitis

BACKGROUND AND OBJECTIVE

Anti-apolipoprotein A-1 (anti-apoA-1) IgG is a potential marker of atherosclerotic plaque vulnerability and cardiovascular complications. In patients with periodontitis the presence of anti-apoA-1 IgGs in serum and their association with atherosclerosis is unknown.

MATERIAL AND METHODS

One-hundred and thirty subjects with periodontal disease and 46 healthy subjects, matched for age and gender, participated in this study. Anti-apoA-1 IgG, high-sensitivity C-reactive protein (hsCRP) and matrix metalloproteinase (MMP) -2, -3, -8 and -9 were measured in serum samples. An ankle-brachial index (ABI) value below 1.11 served as a surrogate marker of atherosclerosis. Predictive accuracies of biomarkers for abnormal ABI were determined using receiver-operating characteristics curves and logistic regression analyses.

RESULTS

Compared with healthy controls, periodontitis patients showed lower median ABI values (1.10 vs. 1.15; p < 0.0001), a higher prevalence of anti-apoA-1 IgG positivity (23.8% vs. 6.5%; p = 0.009) and higher concentrations of hsCRP (1.62 mg/L vs. 0.85 mg/L; p = 0.02) and MMP-9 (435 μg/mL vs. 283 μg/mL; p < 0.0001). In patients younger than 50 years of age (n = 66), anti-apoA-1 IgG was found to be the best predictor for an abnormal ABI (area under the curve = 0.63; p = 0.03). Anti-apoA-1 IgG positivity increased the risk of having an abnormal ABI (odds ratio = 4.20; p = 0.04), independently of diabetes, smoking and body mass index.

CONCLUSIONS

Anti-apoA-1 IgG positivity and atherosclerosis, as reflected by abnormal ABI, were more prevalent in periodontitis patients than in age- and gender-matched controls. In younger periodontitis patients, anti-apoA-1 IgG was found to be the best predictor of atherosclerosis burden.

Copan WASPLab automation significantly reduces incubation times and allows earlier culture readings

OBJECTIVE

The aim was to evaluate whether laboratory automation (inoculation and automated incubation combined with timely defined high-resolution digital imaging) may help reduce the time required to obtain reliable culture analysis results.

METHODS

We compared the results obtained by WASPLab automation against WASP-based automated inoculation coupled to conventional incubation and manual diagnostic on 1294 clinical samples (483 for the derivation set and 811 for the independent validation set) that included urine, genital tract and non-sterile site specimens, as well as ESwabs for screening of methicillin-resistant Staphylococcus aureus (MRSA), methicillin-sensitive Staphylococcus aureus (MSSA), extended-spectrum beta-lactamases (ESBLs) and carbapenemase-producing Enterobacteriaceae (CPE). We used sequential routine specimens referred to the bacteriology laboratory at Geneva University Hospitals between October 2018 and March 2019.

RESULTS

The detection sensitivity of MRSA and MSSA at 18 hr on WASPLab was 100% (95% confidence interval [CI], 94.48-100.00%). The detection sensitivity of ESBL and CPE at 16 hr on WASPLab was 100% (95% confidence interval [CI], 94.87% to 100.00%). For urine specimens, the similarity was 79% (295/375) between 18 hr and 24 hr of incubation on WASPLab. For genital tract and non-sterile site specimens, the similarity between 16 hr and 28 hr of incubation on WASPLab were 26% (72/281) and 77% (123/159) respectively. Thus, 28 hr was defined as the final incubation time on WASPLab for genital tract and non-sterile site specimens.

CONCLUSIONS

The results of this study show that WASPLab automation enables a reduction of the culture reading time for all specimens tested without affecting performances. Implementing the established and duly validated incubation times will allow appropriate laboratory workflows for improved efficiency to be built.

Update on the efficacy of statin treatment in acute coronary syndromes

BACKGROUND

The natural history of atherosclerosis might involve coronary plaque rupture/erosion, thrombus formation and vessel lumen occlusion, clinically recognized as acute coronary syndrome (ACS). International guidelines strongly recommend early statin administration in patients admitted for ACS. In addition to lowering circulating levels of low-density lipoprotein cholesterol (LDL-c), statin treatment was shown to promote plaque stabilization or regression in several ways, including reduction in necrotic lipid core, anti-inflammatory effects and improvement in endothelial function. The aim of this review is to summarize clinical evidence on the role of statins in secondary prevention of ACS.

MATERIALS AND METHODS

This narrative review is based on the material found on medline and pubmed up to August 2013. We looked for the terms 'statin, acute coronary syndromes' in combination with 'atherosclerosis, acute myocardial infarction, pathophysiology'.

RESULTS

This review article emphasizes the relevance of the timing of statin administration to improve the outcomes after ACS. Early and continuous statin administration has emerged as key features to prevent adverse events, especially in patients admitted for ACS undergoing percutaneous coronary intervention. Clinical trials matching the improved clinical outcome with the imaging of atherosclerotic plaque stabilization/regression, further supporting the effectiveness of statin therapy. However, the achievement of these goals requires high dose of statins, thus increasing the risk of adverse events.

CONCLUSIONS

Although clinical trials and meta-analyses have provided conflicting results, it is likely that in clinical practice, the rate of adverse events is higher, so that many concerns still remain about a statin high-dose approach in ACS patients.

Cardiac biomarkers and clinical scores for risk stratification in elderly patients with non-high-risk pulmonary embolism

OBJECTIVE

To determine the prognostic accuracy of cardiac biomarkers alone and in combination with clinical scores in elderly patients with non-high-risk pulmonary embolism (PE).

DESIGN

Ancillary analysis of a Swiss multicentre prospective cohort study.

SUBJECTS

A total of 230 patients aged ≥65 years with non-high-risk PE.

MAIN OUTCOME MEASURES

The study end-point was a composite of PE-related complications, defined as PE-related death, recurrent venous thromboembolism or major bleeding during a follow-up of 30 days. The prognostic accuracy of the Pulmonary Embolism Severity Index (PESI), the Geneva Prognostic Score (GPS), the precursor of brain natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) was determined using sensitivity, specificity, predictive values, receiver operating characteristic (ROC) curve analysis, logistic regression and reclassification statistics.

RESULTS

The overall complication rate during follow-up was 8.7%. hs-cTnT achieved the highest prognostic accuracy [area under the ROC curve: 0.75, 95% confidence interval (CI): 0.63-0.86, P < 0.001). At the predefined cut-off values, the negative predictive values of the biomarkers were above 95%. For levels above the cut-off, the risk of complications increased fivefold for hs-cTnT [odds ratio (OR): 5.22, 95% CI: 1.49-18.25] and 14-fold for NT-proBNP (OR: 14.21, 95% CI: 1.73-116.93) after adjustment for both clinical scores and renal function. Reclassification statistics indicated that adding hs-cTnT to the GPS or the PESI significantly improved the prognostic accuracy of both clinical scores.

CONCLUSION

In elderly patients with nonmassive PE, NT-proBNP or hs-cTnT could be an adequate alternative to clinical scores for identifying low-risk individuals suitable for outpatient management.

Comparison of the Copan WASPLab incorporating the BioRad expert system against the SIRscan 2000 automatic for routine antimicrobial disc diffusion susceptibility testing

OBJECTIVES

This study investigated the agreement at the categorical level between the Copan WASPLab incorporating the BioRad expert system against the SIRscan 2000 automatic for antimicrobial disc diffusion susceptibility testing.

METHODS

The 338 clinical strains (67 Pseudomonas aeruginosa, 19 methicillin-resistant Staphylococcus aureus, 75 methicillin-sensitive S. aureus and 177 Enterobacterales isolates) analysed in this study were non-duplicate isolates obtained from consecutive clinical samples referred to the clinical bacteriology laboratory at Geneva University Hospitals between June and August 2019. For the WASPLab the inoculum suspension was prepared in strict accordance with the manufacturer's instruction (Copan WASP srl, Brescia, Italy) by adding 2 mL of the 0.5 McFarland primary suspension used for the SIRscan analysis into a sterile tube filled with 4 mL of sterile saline (1:3 dilution). The inoculum (2 × 30 μL loop/spreader) was spread over the entire surface of Mueller-Hinton agar plates according to the AST streaking pattern defined by Copan. The antibiotic discs were dispensed by the WASP and inoculated media were loaded on conveyors for transfer to the automatic incubators. The plates were incubated for 16 h, and several digital images were acquired. Inhibition zone diameters were automatically read by the WASPLab and were adjusted manually whenever necessary. For the SIRscan 2000 automatic, the antimicrobial disc diffusion susceptibility testing was performed according to the EUCAST guidelines. The gradient strip method was used to resolve discrepancies.

RESULTS

The overall categorical agreement between the compared methods reached 99.1% (797/804; 95% CI 98.2%-99.6%), 99.5% (1029/1034; 95% CI 98.9%-99.8%), and 98.8% (2798/2832; 95% CI 98.3%-99.1%) for P. aeruginosa, S. aureus and the Enterobacterales, respectively.

CONCLUSIONS

WASPLab incorporating the BioRad expert system provides a fully automated solution for antimicrobial disc diffusion susceptibility testing with equal or better accuracy than other available phenotypic methods.

P5343The presence of anti-apolipoprotein A1 autoantibodies is associated with a pro-atherogenic profile in HIV-infected patients

Background

With the access to antiretroviral therapy (ART), the mortality related to the human immunodeficiency virus (HIV) has dropped, shifting the clinical challenges towards chronic disease management, including cardiovascular disease (CVD) risk assessment. Factors that potentially contribute to the physiopathology of HIV-related CVD include the HI-virus itself, adverse effects of ART, and processes such as dyslipidemia, inflammation, immune/autoimmune activation and endothelial injury. Among autoantibodies of possible cardiovascular relevance, those directed against apolipoprotein A-1 (anti-apoA-1 IgG) were shown to predict major adverse cardiovascular events and promote atherogenesis.

Purpose

The aim of the study was to evaluate the prevalence of anti-apoA1 IgG in HIV-free and ART experienced and naïve HIV-infected patients as well as the association between anti-apoA1 IgG levels and, indices of viral suppression, clinical parameters (10 year Framingham Risk Score (FRS)) and inflammatory biomarkers, known to underlie atherosclerosis burden in these patients.

Methods

Anti-apoA1 IgG serum levels were assessed by a homemade ELISA assay in 144 participants from a South African cohort divided in three groups: HIV-free (n=50), HIV-infected/ART experienced (n=50) and HIV-infected/ART naïve (n=44). Inflammatory biomarkers were measured.

Results

HIV-infected patients displayed an increased pro-atherogenic biomarker profile compared to HIV-free subjects, but not difference in the FRS was observed between these two groups. Regarding anti-apoA1 IgG, 24% of HIV-free patients tested positive compared to 40% and 70% in HIV-infected/ART experienced and naïve groups, respectively. HIV-infected, anti-apoA1 IgG positive patients showed a significant decrease in CD4+ counts (p=0.003) and a significant increase in viremia (p=0.0130), mean heart rate (p=0.0243), albuminuria (p=0.0155), pro-inflammatory biomarkers (IFNγ, IL-10, TNFα, MIPα; all p<0.05), circulating levels of intercellular adhesion molecule (ICAM-1) (p=0.0217) and vascular cell adhesion molecule (VCAM-1) (p=0.003) compared to anti-apoA1 IgG negative ones. Of note, while this profile was maintained in HIV-infected/ART experienced, these significant differences were lost in HIV-infected/ART naïve patients. No significant difference in FRS was observed between anti-apoA1 IgG positive vs negative individuals in all groups.

Conclusions

HIV-infected patients presented with an increased prevalence of anti-apoA1 IgG compared to HIV-free subjects. In HIV-infected/ART experienced patients, anti-apoA1 IgG levels were associated with low CD4+ counts, levels of adhesion molecules and pro-inflammatory responses, features associated with increased cardiovascular events. ART highlighted pro-atherogenic differences between HIV-infected anti-apoA1 IgG negative and positive patients.

Autoantibodies directed against apolipoprotein A-1 as a potential contributor to non-alcoholic fatty liver disease

Background

Non-Alcoholic Fatty Liver Disease (NAFLD) represents an increasing cause of liver disease worldwide. Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in these patients. Although NAFLD pathophysiology is not fully understood alterations in fat metabolism seem to play a role. Autoantibodies against apolipoprotein A-1 (anti-apoA-1 IgG) are a novel cardiovascular risk factor to which have been recently attributed a metabolic role in addition to a well-established macrophage-mediated inflammatory effect and have a function as a disruptor of the cholesterol pathway.

Purpose

This study aims at evaluating a possible role of anti-apoA-1 IgG in NAFLD.

Methods

Serum from 137 NAFLD patients were tested for anti-apoA-1 IgG prevalence. In vitro, SREBP1, SREBP2 expressions were assessed in the human hepatic cell line HepaRG by western blot analysis and bodipy staining was used to evaluate the lipid droplet content. Mescoscale technology platform was used to measure TNF-α, IL-6 and IL-8 cytokines/chemokines in HepaRG supernatants. Oil Red O staining was used to detect lipid accumulation in liver sections from ApoE−/− mice.

Results

Elevated anti-apoA-1 IgG seropositivity was found in patients with NAFLD (46%). In vitro, anti-apoA-1 IgG and not control IgG induced lipid accumulation in hepatic cells (5.9 vs 2.5, P=0.0008) and this lipid overload was associated with a high SREBP1 but not SREBP2 expression. Furthermore, anti-apoA-1 IgG and not control antibodies caused a significant large increase of the proinflammatory cytokines IL-6 (680 vs. 163 pg/mL, P=0.03) and TNF-α (391 vs 266 pg/mL, P=0.04) as well as of the chemokine IL-8 (174.1 vs. 72.6 ng/mL, P=0.03) detected in the hepatic cell supernatants. In vivo, anti-apoA-1 IgG and not control IgG also induced higher lipid accumulation in the livers of ApoE−/− mice (1.23 vs 0.53, P=0.03).

Conclusion

Anti-apoA-1 IgG are frequent in NAFLD, cause a strong inflammatory response and promote lipid accumulation through SREBP1 activation in human hepatic cells. We hypothesize that anti-apoA1 IgG may be a potential contributor in the development of NAFLD.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Geneva University Hospital