To validate the diagnostic accuracy of a Euroimmun SARS-CoV-2 IgG and IgA immunoassay for COVID-19.
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.
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.
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.
Recent diagnostic advances allow to identify persons in a pre‐symptomatic stage of rheumatoid arthritis (RA), opening the way for a preventive therapeutic intervention, which may potentially be ...curative. We review and discuss existing biomarkers predictive of future onset of RA. A responsible use of biomarkers in clinical settings will require an integration of blood‐based tests, imaging techniques, clinical history, environmental risk factors, and family history.
. Pagano S, Satta N, Werling D, Offord V, de Moerloose P, Charbonney E, Hochstrasser D, Roux‐Lombard P, Vuilleumier N (Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland; Geneva ...University Hospital and Faculty of Medicine, Geneva, Switzerland; Royal Veterinary College, Hertfordshire, UK; St. Michael’s Hospital, Toronto, Canada; Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland). Anti‐apolipoprotein A‐1 IgG in patients with myocardial infarction promotes inflammation through TLR2/CD14 complex. J Intern Med 2012; 272: 344–357.
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.
Summary
Background Antitumour necrosis factor (anti‐TNF) treatments may reactivate latent tuberculosis infection (LTBI). For detecting LTBI, the tuberculin skin test (TST) has low sensitivity and ...specificity. Interferon‐γ release assays (IGRA) have been shown to be more sensitive and specific than TST.
Objective To compare the TST and the T‐SPOT.TB IGRA for identifying LTBI in patients with psoriasis before anti‐TNF treatment.
Methods A retrospective study was carried out over a 4‐year period on patients with psoriasis requiring anti‐TNF treatment. All were subjected to the TST, T‐SPOT.TB and chest X‐ray. Risk factors for LTBI and history of bacillus Calmette–Guérin (BCG) vaccination were recorded. The association of T‐SPOT.TB and TST results with risk factors for LTBI was tested through univariate logistic regression models. Agreement between tests was quantified using kappa statistics. Treatment for LTBI was started 1 month before anti‐TNF therapy when indicated.
Results Fifty patients were included; 90% had prior BCG vaccination. A positive T‐SPOT.TB was strongly associated with a presumptive diagnosis of LTBI (odds ratio 7·43; 95% confidence interval 1·38–39·9), which was not the case for the TST. Agreement between the T‐SPOT.TB and TST was poor, κ = 0·33 (SD 0·13). LTBI was detected and treated in 20% of the patients. In 20% of the cases, LTBI was not retained in spite of a positive TST but a negative T‐SPOT.TB. All patients received an anti‐TNF agent for a median of 56 weeks (range 20–188); among patients with a positive TST/negative T‐SPOT.TB, no tuberculosis was detected with a median follow‐up of 64 weeks (44–188). One case of disseminated tuberculosis occurred after 28 weeks of adalimumab treatment in a patient with LTBI in spite of treatment with rifampicin.
Conclusion This study is the first to underline the frequency of LTBI in patients with psoriasis (20%), and to support the use of IGRA instead of the TST for its detection. Nevertheless, there is still a risk of tuberculosis under anti‐TNF therapy, even if LTBI is correctly diagnosed and treated.
. Keller P‐F, Pagano S, Roux‐Lombard P, Sigaud P, Rutschmann OT, Mach F, Hochstrasser D Vuilleumier N (Geneva University Hospitals, Geneva). Autoantibodies against apolipoprotein A‐1 and ...phosphorylcholine for diagnosis of non‐ST‐segment elevation myocardial infarction. J Intern Med 2012; 271: 451–462.
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.
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.
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.
Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), essential components in the pathogenesis of immunoinflammatory diseases, are strongly induced in monocytes by direct contact with ...stimulated T lymphocytes. This study demonstrates that adult human serum (HS) but not fetal calf or cord blood serum displays inhibitory activity toward the contact-mediated activation of monocytes by stimulated T cells, decreasing the production of both TNF-α and IL-1β. Fractionation of HS and N-terminal microsequencing as well as electroelution of material subjected to preparative electrophoresis revealed that apolipoprotein A-I (apo A-I), a “negative” acute-phase protein, was the inhibitory factor. Functional assays and flow cytometry analyses show that high-density lipoprotein (HDL)-associated apo A-I inhibits contact-mediated activation of monocytes by binding to stimulated T cells, thus inhibiting TNF-α and IL-1β production at both protein and messenger RNA levels. Furthermore, apo A-I inhibits monocyte inflammatory functions in peripheral blood mononuclear cells activated by either specific antigens or lectins without affecting cell proliferation. These results demonstrate a new anti-inflammatory activity of HDL-associated apo A-I that might have modulating functions in nonseptic conditions. Therefore, because HDL has been shown to bind and neutralize lipopolysaccharide, HDL appears to play an important part in modulating both acute and chronic inflammation. The novel anti-inflammatory function of apo A-I reported here might lead to new therapeutic approaches in inflammatory diseases such as rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, and atherosclerosis.
Background‘Systemic autoimmunity associated with rheumatoid arthritis’ (RA), is a pre-clinical stage preceding the onset of clinical RA, characterised by the presence of autoantibodies, such as ...anti-citrullinated protein antibodies (ACPA) or anti-carbamylated protein antibodies (antiCarP). Breastfeeding has been proposed as a protective factor for RA development,1 but there are some controversies.2 To establish the causal role of a putative risk factor, longitudinal studies are needed, in particular in the pre-stages of RA development.ObjectivesTo study the association between breastfeeding and the development of systemic autoimmunity associated with RA.MethodsThis ongoing prospective study includes individuals genetically at risk of developing RA, namely first-degree relatives of RA patients (RA-FDR). Individuals without clinical evidence of RA were enrolled, and assessed yearly clinically and biologically. We included all RA-FDR women with available ACPA status (anti-CCP 2, 3.1 or 3.0) and information about breastfeeding. The primary outcome was ACPA positivity. The exposure of interest was breastfeeding and duration of breastfeeding (categorised as 0, 1–7 and ≥7 months). The presence of antiCarP was a secondary outcome. We used logistic regression to analyse univariable and multivariable associations.ResultsA total of 882 women were included, of which 57 (6%) were ACPA positive. The characteristics of ACPA positive and negative participants were balanced, except for an older age in ACPA positives (median 52 versus 45 years; table 1). In the univariable analysis, ACPA positivity was not significantly associated with breastfeeding (OR 1.5, p=0.16) or with breastfeeding duration (OR=1.8, p=0.14). In the multivariable analysis adjusted by age, smoking, number of pregnancies and years of education, there was a weak, but not significant, association between breastfeeding for more than 7 months and ACPA positivity (OR 2.16, p=0.10). Among 728 women with available antiCarP results, 70 (10%) were positive, of which 27 (40%) breastfed. Breastfeeding for more than 7 months was not significantly associated with antiCarP in univariable or multivariable analyses (OR 1.3, p=0.52 and OR 1.9, p=0.16, respectively).Abstract SAT0692 – Table 1General characteristics of RA-FDR women, n=882ConclusionsAmong women at risk of RA, breastfeeding was not associated with the presence of ACPA or antiCarP. Our results do not support a protective role of breastfeeding in the development of systemic autommunity associated with RA.References1 Orellana C, et al. Ann Rheum Dis2017;76:1845–52.2 Berglin E, et al. Scand J Rheumatol2010;39:454 -60.Disclosure of InterestNone declared
The aim of this study was to assess the contribution of an interferon-gamma release assay (T-SPOT.TB) to the differentiation of active tuberculosis (TB) from latent TB infection by quantifying ...spot-forming units (sfu). The investigation was a prospective study of contacts exposed to a case of contagious TB and cases of HIV-negative culture-proven TB referred over a 16-month period. Tuberculin skin tests (TSTs) and T-SPOT.TB were performed in 310 contacts 8-12 weeks after exposure. In subjects with culture-proven TB, T-SPOT.TB was performed within 2 weeks of initiation of treatment. The analysis included all contacts with a positive T-SPOT.TB result and all subjects with TB. TB contacts (n = 127) and cases (n = 58) were included. Mean+/-sd T-SPOT.TB results were 107+/-56 (range 1-207) sfu for TB, 54+/-60 (7-239) sfu for contacts with positive T-SPOT.TB results and a TST induration diameter of >5 mm, and 19+/-27 (7-143) sfu for contacts with positive T-SPOT.TB results and a TST induration diameter of < or =5 mm. By receiver operating characteristic curve analysis, a threshold value of 49.5 sfu showed a sensitivity of 83% and specificity of 74% for distinguishing latent TB infection from TB. Although T-SPOT.TB results were significantly related to disease activity, the test cannot be recommended for the diagnosis of tuberculosis.
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