Comparison of current methods for anti-dsDNA antibody detection and reshaping diagnostic strategies.

Anti-double-stranded DNA antibodies (anti-dsDNA) are considered a specific marker for systemic lupus erythematosus (SLE). Though the Farr technique was once the reference method for their detection, it has been almost entirely replaced by more recently developed assays. However, there is still no solid evidence of the commutability of these methods in terms of diagnostic accuracy and their correlation with the Crithidia luciliae immunofluorescence test (CLIFT). Anti-dsDNA antibody levels were measured in 80 subjects: 24 patients with SLE, 36 disease controls drawn from different autoimmune rheumatic diseases (14 systemic sclerosis, 10 Sjögren's syndrome, nine autoimmune myositis, three mixed connective tissue disease), 10 inflammatory arthritis and 10 apparently healthy blood donors by eight different methods: fluorescence enzyme immunoassay, microdot array, chemiluminescent immunoassay (two assays), multiplex flow immunoassay, particle multi-analyte technology immunoassay and two CLIFT. At the recommended manufacturer cut-off, the sensitivity varied from 67% to 92%, while the specificity ranged from 84% to 98%. Positive agreement among CLIFT and the other assays was higher than negative agreement. Mean agreement among methods assessed by the Cohen's kappa was 0.715, ranging from moderate (0.588) to almost perfect (0.888). Evaluation of the concordance among quantitative values by regression analysis showed a poor correlation index (mean r2, 0.66). The present study shows that current technologies for anti-dsDNA antibody detection are not fully comparable. In particular, their different correlation with CLIFT influences their positioning in the diagnostic algorithm for SLE (either in association or sequentially). Considering the high intermethod variability, harmonization and commutability of anti-dsDNA antibody testing remains an unachieved goal.

Current technologies for anti-ENA antibody detection: State-of-the-art of diagnostic immunoassays.

BACKGROUND: Autoantibodies against extractable nuclear antigens (ENA) play a pivotal role in the diagnosis and classification of systemic autoimmune rheumatic diseases (SARD). In recent years, newly developed methods have enabled the simultaneous and quantitative detection of multiple anti-ENA reactivities. However, data regarding the comparability of results obtained using different technologies across different platforms are scarce. In this study we compared eight different immunoassays, commonly used in current laboratory practice for detection of anti-ENA antibodies. METHODS: Sixty patients suffering from different SARD, 10 inflammatory arthritis patients (disease controls) and 10 healthy blood donors were included in this comparative study. Sera were collected in 15 centers belonging to the Study Group on Autoimmune Diseases of the Italian Society of Clinical Pathology and Laboratory Medicine. We evaluated the analytical sensitivity, specificity and diagnostic accuracy of each method for antibodies to Sm, RNP, Ro60, Ro52, Scl70, CENP-B and Jo1. Cohen's kappa was used to analyze the agreement among methods. RESULTS: Average agreement among methods was 0.82, ranging from substantial (k = 0.72) to almost perfect (k = 0.92). However, while the specificity was very good for all methods, some differences emerged regarding the analytical sensitivity. CONCLUSIONS: Diagnostic performance of current technologies for anti-ENA antibody detection showed good comparability. However, as some differences exist among methods, laboratory scientists and clinicians must be aware of the diagnostic accuracy of the testing method in use.

Diagnostic accuracy of anti-phospholipase A2 receptor (PLA2R) antibodies in idiopathic membranous nephropathy: an Italian experience.

BACKGROUND: Autoantibodies against-phospholipase A2 receptor (PLA2R) are specific markers of idiopathic membranous nephropathy (iMN). Enzyme-linked immunosorbent assay (ELISA) is becoming the preferred method in many laboratories for the determination of anti-PLA2R antibodies, because it provides quantitative results, and is not prone to subjective interpretation, as is the case with indirect immunofluorescence assay. METHODS: The purpose of our study was to determine the diagnostic performance of serum PLA2R antibodies detected by commercially available ELISA in a large Italian multicenter cohort of patients with biopsy-proven iMN and in patients with other renal diseases, with special focus on evaluating the optimal cut-off value to discriminate positive and negative results. A total of 495 consecutive patients were recruited. Renal biopsies were performed in all patients, and blood samples were taken before the initiation of immunosuppressive treatment. RESULTS: According to the clinical diagnosis and to kidney biopsy, 126 patients were diagnosed with iMN and 369 had other non-membranous nephropathies. Anti-PLA2R autoantibodies were detected using a commercial anti-PLA2R ELISA. At a cut-off value of 20 relative units (RU)/ml indicated by the manufacturer for positive classification, sensitivity was 61.1% and specificity 99.7%. At a cut-off value of 14 RU/ml indicated by the manufacturer for borderline results, sensitivity was 63.5% and specificity remained the same (99.7%). At a cut-off of 2.7 RU/ml, selected as the optimal cut-off on the basis of ROC curve analysis, sensitivity was 83.3% and specificity 95.1%. The best overall efficiency of the test was observed at 2.7 RU/ml; however, the highest positive likelihood ratio and diagnostic odds ratio were achieved at 14 RU/ml. A cut-off threshold higher than 14 RU/ml or lower than 2.7 RU/ml entailed worse test performance. CONCLUSION: Depending on the clinical use (early diagnosis or as a support to confirm clinical diagnosis), nephrologists may take advantage of this evidence by choosing the most convenient cut-off. However, renal biopsy remains mandatory for the definitive diagnosis of iMN and for the assessment of disease severity.

Testing for fecal gluten immunogenic peptides: a useful tool to evaluate compliance with gluten-free diet by celiacs.

BACKGROUND: Although experts agree that strict dietary compliance is fundamental for the health of celiac patients, there are no evidence-based recommendations on the best way to assess dietary compliance. Detection of gluten immunogenic peptides (GIPs) in feces was recently proposed as an effective method of assessing the dietary compliance of celiac patients. METHODS: Fifty-five consecutive celiac patients (27 adults and 28 children, age 6-72 years), who had been on a gluten-free diet for at least 2 years, were enrolled. All patients were evaluated clinically for symptoms, physical parameters and laboratory parameters. Dietary compliance was assessed with the Biagi questionnaire and serum anti-tissue transglutaminase (tTG) IgA antibodies were measured. GIPs were determined by immunoenzymatic assay on an automated Chorus analyzer (DIESSE Diagnostica Senese), after extraction of fecal samples by the method developed by DIESSE. RESULTS: Eight patients tested positive for GIPs (GIPs+); 71.4% of GIP-positive patients were asymptomatic; tTG antibodies were detected in 3/8 GIP+ patients. The Biagi score was significantly associated with fecal positivity for GIPs (P=0.02). However, according to the Biagi score, 57.1% of GIP+ patients followed the diet strictly and 5.4% of GIP- subjects did not comply with the diet or made substantial mistakes. CONCLUSIONS: Assay of fecal GIPs identified more patients who did not comply with the diet than did the Biagi questionnaire, evaluation of symptoms or anti-tTG antibodies. Detection of fecal GIPs offers a direct, objective, quantitative assessment of even occasional exposure to gluten and is confirmed as a practical way to check dietary compliance.

A new diagnostic algorithm for pattern-oriented autoantibody testing according to the ICAP nomenclature: A pilot study.

The commercial tests currently available as second-level tests to detect ANA sub-specificities are generally used independently from the ANA immunofluorescence (IIF) pattern. The aim of this study was to evaluate the efficacy of the use of a customizable pattern-oriented antigenic panel by immunoblot (IB) using the International Consensus on ANA Patterns (ICAP) classification scheme, in order to introduce a novel and updated autoimmune diagnostic flowchart. 710 sera referred for routine ANA testing were selected on the basis of the ANA pattern according to the ICAP nomenclature (nuclear speckled AC-2,4,5; nucleolar AC-8,9,10,29; cytoplasmic speckled AC-18,19,20) and on an IIF titer ≥1:320. They were then assayed by three experimental IB assays using a panel of selected antigens. ICAP-oriented IB detected 515 antibody reactivities vs. 457 of traditional anti-ENA in the nuclear speckled pattern group, 108 vs. 28 in the nucleolar pattern group, and 43 vs. 34 in the cytoplasmic speckled pattern. This pilot study may lead the way for a new approach introducing an ICAP pattern-oriented follow up testing as a valid alternative to the existing standard panels, thus enabling more patients with autoimmune rheumatic disease to be accurately diagnosed.

Autoantibodies against the autophagic protein microtubule-associated light-chain 3 (LC3): Immunocharacterization of an atypical ANA pattern.

Autoantibodies to nuclear and cytoplasmic antigens are commonly detected by indirect immunofluorescence (IIF) on HEp-2 cells, and three major staining patterns (nuclear, cytoplasmic, and mitotic) are distinguished. Here, we report an atypical cytoplasmic pattern, not described so far, observed in the serum of a patient with a controversial diagnosis of systemic lupus erythematosus (SLE). Moreover, for the first time, we have revealed the presence of autoantibodies against the microtubule-associated light-chain 3 (LC3) protein, which plays a key role in the autophagic process. The target antigen has been identified in IIF by means of a competition test using purified anti-LC3 antibodies on HEp-2 cells, and confirmed by Western blot analysis using cellular or recombinant LC3 as antigen, immunoreacted with the patient's serum. The identification of this atypical pattern and the related autoantibody-antigen system sheds new light on autophagy, which is increasingly considered to be involved in the etiopathogenesis of autoimmune disorders, and could contribute to select more personalized therapies.

Fecal gluten immunogenic peptides as indicators of dietary compliance in celiac patients.

BACKGROUND: It is important to have methods for evaluating dietary compliance in patients with celiac disease (CD). Determination of fecal gluten immunogenic peptides (GIPs) was recently proposed as a method of detecting gluten intake. The aim of this study was to evaluate whether determination of GIPs can be used as an indicator of compliance with a gluten-free diet (GFD). METHODS: Twenty-five persons with CD on a gluten-free diet for at least one year were enrolled in the study. Compliance with the diet was assessed by the Biagi questionnaire, evaluation of symptoms and assay of IgA anti-tissue transglutaminase antibodies (IgA anti-tTG). GIPs were determined by iVYLISA GIP-S test (Biomedal S.L., Seville, Spain) on an automated Chorus analyzer (DIESSE Diagnostica Senese, Siena, Italy), after extraction of fecal samples by the method developed by DIESSE. RESULTS: Four patients tested positive for GIPs (GIP+), two of whom complied strictly with the gluten-free diet according to the Biagi questionnaire. None of the four GIP-positive patients manifested symptoms. IgA anti-tTG was significantly higher in GIP+ than in GIP- subjects. CONCLUSIONS: Assay of fecal GIPs identified more patients who were not complying with the diet than the Biagi questionnaire or evaluation of symptoms. The anti-tTG and GIP results agreed perfectly; however, since anti-tTG antibodies remain high for longer and are not a completely reliable marker of GFD intake, detection of fecal GIPs offers a direct, objective, quantitative assessment of exposure, even occasional, to gluten and could be used to check dietary compliance.

The GAG-specific branched peptide NT4 reduces angiogenesis and invasiveness of tumor cells.

Heparan sulfate proteoglycans, HSPGs, modulate major transformations of cancer cells, leading to tumor growth, invasion and metastasis. HSPGs also regulate neo-angiogenesis which prompts cancer progression and metastatic spread. A different aspect of heparin and analogs is their prominent role in the coagulation of blood. The interplay between coagulation and metastasis is being actively studied: anticoagulants such as heparin-derivatives have anticancer activity and procoagulants, such as thrombin, positively modulate proliferation, migration and invasion. The branched peptide NT4 binds to HSPGs and targets selectively cancer cells and tissues. For this, it had been extensively investigated in the last years and it proved to be efficient as chemotherapeutic and tumor tracer in in vivo models of cancer. We investigated the effects of the branched peptide in terms of modulation of angiogenesis and invasiveness of cancer cells. NT4 proved to have a major impact on endothelial cell proliferation, migration and tube formation, particularly when induced by FGF2 and thrombin. In addition, NT4 had important effects on aggressive tumor cells migration and invasion and it also had an anticoagulant profile.The peptide showed very interesting evidence of interference with tumor invasion pathways, offering a cue for its development as a tumor-targeting drug, and also for its use in the study of links between coagulation and tumor progression involving HSPGs.

A study on the association of mood disorders and gluten-related diseases.

Our study aimed to evaluate the presence of antibodies related to gluten intolerance in patients with mood disorders. A total of 60 patients with a diagnosis of bipolar disorder or depressive disorder were recruited. Fourty-eight subjects randomly selected among unrelated family members were included as controls. Celiac disease-associated antibodies were assayed both in the patients and controls. Mean values of IgA/IgG anti-gliadin antibodies, IgA/IgG anti-deamidated gliadin peptide antibodies and IgA anti-transglutaminase (tTG) antibodies were not different between patients and controls. However, a significant difference was found for anti-tTG IgG antibodies. Even if both in controls and in patients the mean anti-tTG IgG value was below the cutoff, the estimates produced by the statistical model showed that each unit increase in the anti-tTG IgG antibody value corresponded to an approximately 5% increased chance of having a mood disorder. The patient group showed a more frequent presence of symptoms associated to non-celiac gluten sensitivity. However, as there was neither any correlation between antibody levels and gastrointestinal symptoms, nor with the intensity of the psychiatric symptoms, it may be conceivable that the increase in anti-tTG IgG antibodies is not disorder-related but possibly an outcome of the psychiatric disorder itself.

Association between stressful life events and autoimmune diseases: A systematic review and meta-analysis of retrospective case-control studies.

BACKGROUND: Evidence of a relationship between stressful life events and the onset of autoimmune diseases is not univocal and there are no meta-analyses in the literature on the question. AIM: To look for differences in the number and type of stressful life events in the premorbid period between patients with autoimmune diseases and healthy subjects. METHOD: Review of the literature in PubMed and Scopus (January 1963-May 2015). INCLUSION CRITERIA: We included retrospective case-control studies that compared patients diagnosed with autoimmune disorders and controls regarding the incidence of stressful events occurring before diagnosis, and investigated said events with validated questionnaires. EFFECT-SIZE INDEXES: By random effect meta-analysis, two independent researchers calculated effect-size indexes as the difference between the means of the clinical groups and the control group in relation to the combined standard deviation. RESULTS: The database searches produced 2490 articles, 14 of which were selected (3201 patients). Analysis showed a moderate but significant mean effect-size index [d=0.63, p<0.01], suggesting that autoimmune disorders are effectively associated with major stressful events in the premorbid period. The relationship between stressful events and autoimmune disease was weaker in studies with a high proportion of female subjects [ß=-0.004, p<0.01] and stronger in studies that considered a longer interval between stressors and onset of disease [ß=0.16, p<0.01]. CONCLUSIONS: The results of this meta-analysis suggest that stressors may play an important role in the etiopathogenesis of autoimmune disorders. Only prospective studies can provide more certain inference about the causality of this relationship.

Assessment of a Test for the Screening and Diagnosis of Celiac Disease.

BACKGROUND: Celiac disease (CD) is an immune-mediated intolerance to dietary gluten, affecting genetically predisposed individuals. ELISA-based serological tests help to decide if further duodenal biopsy is necessary, for this the diagnostic kits have to be accurate, specific, and sensible. In this study, we investigate the performance of an ELISA that uses the purified cross-linked complex of tissue transglutaminase and gliadin, referred as the "neoepitope" (AESKULISA® tTG New Generation), as antigen. METHODS: We evaluated 41 newly diagnosed celiac patients, 18 celiac patients on gluten-free diet, and 169 controls, comprising healthy subjects, patients affected by other autoimmune diseases, and patients affected by several non-autoimmune diseases. RESULTS AND CONCLUSION: The assay has an excellent performance. Due to its high level of diagnostic accuracy, this assay constitutes a new approach for the screening of celiac patients not only for the diagnosis of CD, but also for monitoring patients on gluten-free diet and their compliance. Moreover, cases of neoepitope-positive subjects who were tested negative with "classical" serological markers could have a predictive value for this pathology. This aspect will require further studies of elaboration.

Decreased plasma endogenous soluble RAGE, and enhanced adipokine secretion, oxidative stress and platelet/coagulative activation identify non-alcoholic fatty liver disease among patients with familial combined hyperlipidemia and/or metabolic syndrome.

OBJECTIVE: In patients with familial combined hyperlipidemia (FCHL), without metabolic syndrome (MS), occurrence of non-alcoholic fatty liver disease (NAFLD) is related to a specific pro-inflammatory profile, influenced by genetic traits, involved in oxidative stress and adipokine secretion. Among FCHL or MS patients, hyperactivity of the ligand-receptor for advanced glycation-end-products (RAGE) pathway, as reflected by inadequate protective response by the endogenous secretory (es)RAGE, in concert with genetic predisposition, may identify those with NAFLD even before and regardless of MS. METHODS: We cross-sectionally compared 60 patients with vs. 50 without NAFLD. Each group included patients with FCHL alone, MS alone, and FCHL plus MS. RESULTS: NAFLD patients had significantly lower plasma esRAGE, IL-10 and adiponectin, and higher CD40 ligand, endogenous thrombin potential and oxidized LDL. The effects of MS plus FCHL were additive. The genotypic cluster including LOX-1 IVS4-14A plus ADIPO 45GG and 256 GT/GG plus IL-10 10-1082G, together with higher esRAGE levels highly discriminate FCHL and MS patients not developing NAFLD. CONCLUSIONS: Among FCHL or MS patients, noncarriers of the protective genotypic cluster, with lower esRAGE and higher degree of atherothrombotic abnormalities coincide with the diagnosis of NAFLD. This suggests an interplay between genotype, adipokine secretion, oxidative stress and platelet/coagulative activation, accelerating NAFLD occurrence as a proxy for cardiovascular disease.

Celiac and non-celiac gluten sensitivity: a review on the association with schizophrenia and mood disorders.

An association between many psychiatric and gluten-related disorders has been known for some time. In the case of schizophrenia and mood disorders, the major psychiatric disorders, there is much evidence, not without contradictions, of a possible association between schizophrenia and celiac disease. The association between mood disorders and gluten-related disorders, especially celiac disease, has only been studied for depression, often coupled with anxiety, and very recently for bipolar disorder. Since non-celiac gluten sensitivity is now known to be different from celiac disease, many studies have shown that gluten sensitivity is also associated with major psychiatric disorders. Here we review the literature on the association between schizophrenia/mood disorders and celiac disease/gluten sensitivity, pointing out the differences between these associations.

Overcoming a "probable" diagnosis in antimitochondrial antibody negative primary biliary cirrhosis: study of 100 sera and review of the literature.

Serum anti-mitochondrial antibodies (AMA) are the serological hallmark of primary biliary cirrhosis (PBC), yet up to 15% of PBC sera are AMA negative at routine indirect immunofluorescence (IIF) while being referred to as "probable" cases. The diagnostic role of PBC-specific antinuclear antibodies (ANA) remains to be determined. We will report herein data on the accuracy of new laboratory tools for AMA and PBC-specific ANA in a large series of PBC sera that were AMA-negative at IIF. We will also provide a discussion of the history and current status of AMA detection methods. We included IIF AMA-negative PBC sera (n=100) and sera from patients with other chronic liver diseases (n=104) that had been independently tested for IIF AMA and ANA; sera were blindly tested with an ELISA PBC screening test including two ANA (gp210, sp100) and a triple (pMIT3) AMA recombinant antigens. Among IIF AMA-negative sera, 43/100 (43%) manifested reactivity using the PBC screening test. The same test was positive for 6/104 (5.8%) control sera. IIF AMA-negative/PBC screen-positive sera reacted against pMIT3 (11/43), gp210 (8/43), Sp100 (17/43), both pMIT3 and gp210 (1/43), or both pMIT3 and Sp100 (6/43). Concordance rates between the ANA pattern on HEp-2 cells and specific Sp100 and gp210 ELISA results in AMA-negative subjects were 92% for nuclear dots and Sp100 and 99% for nuclear rim and gp210. Our data confirm the hypothesis that a substantial part of IIF AMA-negative (formerly coined "probable") PBC cases manifest disease-specific autoantibodies when tested using newly available tools and thus overcome the previously suggested diagnostic classification. As suggested by the recent literature, we are convinced that the proportion of AMA-negative PBC cases will be significantly minimized by the use of new laboratory methods and recombinant antigens.

Erratum to: Assessment of a combination screening assay for celiac disease.

[This corrects the article DOI: 10.1007/s13317-011-0020-1.].

[A case of Xanthinuria in a patient with marked hypouricemia]. / Un caso di xantinuria in una paziente con marcata ipouricemia.

Xanthinuria is a rare autosomal recessive disorder associated with a deficiency of xanthine oxidoreductase (XOR), which normally catalyzes the conversion of hypoxanthine to uric acid. The effects of this deficit are an elevated concentration of hypoxanthine and xanthine in the blood and urine, hypouricemia, and hypouricuria. The deficit in XOR can be isolated (type I xanthinuria) or associated with a deficit in aldehyde oxidase (type II xanthinuria) and sulfite oxidase (type III xanthinuria). While the first two variants have a benign course, are often asymptomatic (20%), and clinically indistinguishable, type III xanthinuria is a harmful form that leads to infant death due to neurological damage. The clinical symptoms (kidney stones, CKD, muscle and joint pain, peptic ulcer) are the result of the accumulation of xanthine, which is highly insoluble, in the body fluids. We describe a case of type I xanthinuria in a 52-year-old woman who presented with hypouricemia, hypouricuria and kidney stones. The diagnosis was based on purine catabolite levels in urine and serum measured by 3 nonroutine methods: high-pressure liquid chromatography, mass spectrometry, and magnetic resonance imaging. To identify the type of xanthinuria the allopurinol test was used. We believe that these tests will facilitate the diagnosis of xantinuria especially in asymptomatic patients without the need for a biopsy of the liver or intestines, which is useful only for scientific purposes.

Assessment of a combination screening assay for celiac disease.

PURPOSE: A serological screening assay for celiac disease (CD), designed to simultaneously detect IgA and IgG anti-tissue transglutaminase (a-tTG) and IgA and IgG deamidated gliadin peptide antibodies (a-DGP), was recently developed. In this study, we establish the performance of this assay. METHODS: We enrolled 41 CD patients and 18 CD patients on gluten-free diets. The diagnosis of CD was based on histological and serological criteria, including concomitant positive serology tests (a-tTG, IgA anti-endomysial antibodies). As control population, we enrolled 169 subjects: 145 disease controls and 24 blood donors. In all cases, serum samples were tested for: IgA a-tTG, IgG a-tTG, IgA a-DGP, IgG a-DGP, IgA anti-endomysial antibodies (EMA), IgA and IgG for a-tTG and a-DGP in a single assay. RESULTS: The new test, QUANTA Lite (™) h-tTG/DGP Screen, detects all IgA and IgG antibodies against atTG and a-DGP present in a sample. In our study, the test showed 100% sensitivity and 91.12% specificity. CONCLUSIONS: This study showed additional value of the new h-tTG/DGP Screen assay, which proved superior to more conventional assays and can be considered the best initial test for CD. Further studies are necessary to determine whether combination of h-tTG/DGP Screen with IgA a-tTG or IgA a-DGP can be used to obviate the need for duodenal biopsy in high- and low-risk populations.

WITHDRAWN: Analysis of serum levels of homocysteine and oxidative stress markers in patients with Alzheimer disease.

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