An Italian nationwide survey on the evolution of autoantibody diagnostics in autoimmune rheumatic diseases

OBJECTIVES

The advent of new technologies and the discovery of new antigenic targets of autoantibodies has led to significant changes in autoimmune diagnostics worldwide. To address the extent to which autoimmunology laboratories adhere to such innovation in testing and reporting practices, the Italian Society of Clinical Pathology and Laboratory Medicine launched a national survey to assess the current status of autoimmune diagnostics and to provide direction for further harmonisation.

METHODS

A questionnaire covering topics related to the diagnosis of autoimmune systemic rheumatic diseases was distributed to 152 Italian autoimmunology laboratories. The 59 closed-answer questions were subdivided into four main sections: 1. the setting (university, hospital or private laboratory) and the number of tests carried out; 2. the technologies used and their level of automation; 3. the analytical phase (antibody tests and methods), including awareness of the International Consensus on ANA Patterns (ICAP) initiative; 4. reporting of results and clinician relations.

RESULTS

A total of 121 laboratories (79.6%) responded to the survey (15% universities, 70 hospitals, and 15% private laboratories). Indirect immunofluorescence is used by 94.8% of respondents, chemiluminescence by 78.4%, fluoro-immuno-enzymatic assays by 67.5%, immunodot by 52.6%, line-immunoassay by 47.4%, addressable laser bead immunoassay by 10.3% and radioimmunological methods by 10.2%. The great majority of respondents implemented complete automation of the listed methodologies. 65% of participants state that they add an interpretative comment in the report. 45% of participants enjoy a collaborative relationship with clinicians; counselling activities are provided by almost half of participants.

CONCLUSIONS

Survey results indicated that almost all respondent laboratories have broadened their antibody panel and that high-throughput technologies have been widely introduced. Gaps identified by the survey include a still incomplete compliance with guidelines in antibody profiles (e.g. in antiphospholipid syndrome and rheumatoid arthritis and reporting of test results. Awareness of these differences provides insights that may further contribute to achieving harmonisation in autoimmune diagnostics.

Prevalence of myositis specific and associated antibodies in a cohort of patients affected by idiopathic NSIP and no hint of inflammatory myopathies

The presence of interstitial lung disease (ILD) is a common and fearsome feature of idiopathic inflammatory myopathies (IIM). Such patients show radiological pattern of non-specific interstitial pneumonia (NSIP). The present study aimed to assess the prevalence of myositis-specific and myositis-associated antibodies (MSA and MAA) in a cohort of patients with a previous diagnosis of NSIP and no sign or symptom of IIM. Secondly, it will be assessed whether patients displaying MSA and/or MAA positivity have a worse or a better outcome than idiopathic NSIP. All patients affected by idiopathic NSIP were enrolled. MSA and MAA were detected using EUROLINE Autoimmune Inflammatory Myopathies 20 Ag (Euroimmun Lubeck, Germany), line immunoassay. A total of 16 patients (mean age 72 ± 6.1 years old) were enrolled. Six out of 16 patients (37.5%) had significant MSA and/or MAA positivity: one displayed positivity of anti-PL-7 (+ +), one of anti-Zo (+ +), anti-TIF1γ (+ + +) and anti-Pm-Scl 75 (+ + +), one of anti-Ro52 (+ +), one of anti-Mi2β (+ + +), one of anti-Pm-Scl 75 (+ + +) and the latter of both anti-EJ (+ + +) and anti-Ro52 (+ + +).Two out of 7 seropositive patients showed a significant impairment of FVC (relative risk 4.8, 95% CI 0.78-29.5; p = 0.0350). Accordingly, among the 5 patients that started antifibrotic treatment during the observation time, 4 were seronegative. Our findings highlighted a potential autoimmune or inflammatory in idiopathic NSIP patients and also in those without significant rheumatological symptoms. A more accurate diagnostic assessment may ameliorate diagnostic accuracy as well as may provide new therapeutic strategy (antifibrotic + immunosuppressive). A cautious assessment of NSIP patients with a progressive and non-responsive to glucocorticoids disease course should therefore include an autoimmunity panel comprising MSA and MAA.

Anti-Cytosolic 5'-Nucleotidase 1A in the Diagnosis of Patients with Suspected Idiopathic Inflammatory Myopathies: An Italian Real-Life, Single-Centre Retrospective Study

BACKGROUND

Anti-cytosolic 5'-nucleotidase 1A (anti-cN1A) antibodies were proposed as a biomarker for the diagnosis of inclusion body myositis (IBM), but conflicting specificity and sensitivity evidence limits its use. Our study aimed to assess the diagnostic accuracy of anti-cN1A in a cohort of patients who underwent a myositis line immunoassay for suspected idiopathic inflammatory myopathies (IIM). We also assessed the agreement between two testing procedures: line immunoassay (LIA) and enzyme-linked immunoassay (ELISA).

MATERIALS AND METHODS

We collected retrospective clinical and serological data for 340 patients who underwent a myositis antibody assay using LIA (EUROLINE Autoimmune Inflammatory Myopathies 16 Ag et cN-1A (IgG) line immunoassay) and verification with an anti-cN1A antibody assay using ELISA (IgG) (Euroimmun Lubeck, Germany).

RESULTS

The serum samples of 20 (5.88%) patients (15 females, 5 males, mean age 58.76 ± 18.31) tested positive for anti-cN1A using LIA, but only two out of twenty were diagnosed with IBM. Seventeen out of twenty tested positive for anti-cN1A using ELISA (median IQR, 2.9 (1.9-4.18)).

CONCLUSIONS

Our study suggests excellent concordance between LIA and ELISA for detecting anti-cN1A antibodies. LIA may be a rapid and useful adjunct, and it could even replace ELISA for cN1A assay. However, the high prevalence of diseases other than IBM in our cohort of anti-cN1A-positive patients did not allow us to consider anti-cN1A antibodies as a specific biomarker for IBM.

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.

Screening of Organ-Specific Autoantibodies in a Large Cohort of Patients with Autoimmune Thyroid Diseases

Background: Autoimmune diseases tend to cluster in the same individual or in families. Four types of autoimmune polyglandular syndromes (APS) have been described based on the combination of endocrine and/or non-endocrine autoimmune diseases. In particular, type-3 APS is defined by the association of an autoimmune thyroid disease (ATD) and other autoimmune diseases and has a multifactorial etiology. The natural history of autoimmune diseases is characterized by three stages: potential, subclinical, and clinical. Methods: To determine the prevalence of organ-specific autoantibodies (anti-adrenal, anti-ovary [StCA], anti-pituitary [APA], anti-parietal cells [PCA], anti-tissue transglutaminase [tTGAb], anti-mitochondrial [AMA], anti-glutamic acid decarboxylase [GADA], anti-nicotinic acetylcholine receptor) in patients with ATD and to define the stage of the disease in patients with positive autoantibodies. From January 2016 to November 2018, 1502 patients (1302 female; age 52.7 ± 14.7 [mean ± standard deviation] years, range 18-86 years) with ATD (1285/1502 [85.6%] with chronic autoimmune thyroiditis and 217/1502 [14.4%] with Graves' disease) were prospectively enrolled. Results: The most common organ-specific autoantibodies were PCA (6.99%) and GADA (2.83%), while the prevalence of the remaining autoantibodies was ≤1%. All autoimmune diseases, but celiac disease, were predominant at the potential stage. Sex, ATD type, smoking habit, and coexistence of other autoimmune diseases correlated with the susceptibility to develop chronic atrophic gastritis (CAG) or autoimmune diabetes mellitus. Conclusions: The association between ATD and CAG was the most common manifestation of type-3 APS, mainly at the potential stage, that could lead to appropriate follow-up for early detection and timely treatment of the disease.

Positive tissue transglutaminase antibodies with negative endomysial antibodies: Unresolved issues in diagnosing celiac disease

BACKGROUND

The serological screening for celiac disease (CD) is currently based on the detection of anti-transglutaminase (tTG) IgA antibodies, subsequently confirmed by positive endomysial antibodies (EMA). When an anti-tTG IgA positive/EMA IgA negative result occurs, it can be due either to the lower sensitivity of the EMA test or to the lower specificity of the anti-tTG test. This study aimed at verifying how variation in analytical specificity among different anti-tTG methods could account for this discrepancy.

METHODS

A total of 130 consecutive anti-tTG IgA positive/EMA negative samples were collected from the local screening routine and tested using five anti-tTG IgA commercial assays: two chemiluminescence methods, one fluoroimmunoenzymatic method, one immunoenzymatic method and one multiplex flow immunoassay method.

RESULTS

Twenty three/130 (17.7%) patients were diagnosed with CD. In the other 107 cases a diagnosis of CD was not confirmed. The overall agreement among the five anti-tTG methods ranged from 28.5% to 77.7%. CD condition was more likely linked to the positivity of more than one anti-tTG IgA assay (monopositive = 2.5%, positive with ≥ three methods = 29.5%; p = 0.0004), but it was not related to anti-tTG IgA antibody levels (either positive or borderline; p = 0.5).

CONCLUSIONS

Patients with positive anti-tTG/negative EMA have a low probability of being affected by CD. Given the high variability among methods to measure anti-tTG IgA antibodies, anti-tTG-positive/EMA-negative result must be considered with extreme caution. It is advisable that the laboratory report comments on any discordant results, suggesting to consider the data in the proper clinical context and to refer the patient to a CD reference center for prolonged follow up.

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.

Evaluation of a novel extended automated particle-based multi-analyte assay for the detection of autoantibodies in the diagnosis of primary biliary cholangitis

Background

Anti-mitochondrial autoantibodies (AMA) detected by indirect immunofluorescence (IIF) on rodent tissues are the diagnostic marker of primary biliary cholangitis (PBC). However, up to 15% of patients with PBC are AMA-negative by IIF. In the effort to close the serological gap and improve the diagnostic sensitivity of PBC testing, recently, novel autoantibodies specific for PBC, such as kelch-like 12 (KLHL12, KLp epitope) and hexokinase 1 (HK1) have been described. In this study, we evaluated the autoantibody profile in a large cohort of PBC patients and in patients with other liver disease, including anti-HK1 and anti-KLp autoantibodies.

Methods

Sera of 194 PBC patients (126 AMA-IIF-positive and 68 AMA-IIF-negative) and 138 disease controls were tested for a panel of PBC-specific antibodies (MIT3, sp100, gp210, HK1, KLp) using a new automated particle-based multi-analyte technology (PMAT) assay on the Aptiva instrument (Inova).

Results

Selecting a cutoff yielding a specificity of >95% for all the markers, the sensitivity for anti-MIT3, anti-sp100, anti-gp210, anti-HK1 and anti-KLp in the PBC AMA-IIF-negative cohort was 20.6%, 16.2%, 23.5%, 22.0%, 17.6 and 13.2%, respectively. Six out of the 68 (8.8%) AMA-IIF negative sera were positive for anti-HK1 or anti-KLp alone. Using these new markers in addition to anti-MIT3, anti-sp100 and anti-gp210, the overall sensitivity in this cohort of AMA-IIF-negative patients increased from 53% to 61.8%, reducing the serological gap in AMA-negative PBC patients.

Conclusions

PBC antibody profiling, made possible by the new Aptiva-PMAT technology, allows recognition of a higher number of AMA-negative PBC patients than conventional immunoassays and may represent a useful tool to evaluate the prognostic significance of autoantibody association in PBC patients.

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.

Some Aspects of Purine Nucleotide Metabolism in Lymphocytes of B-CLL

The authors studied the behavior of some enzymes involved in purine nucleotide metabolism in human peripheral blood lymphocytes from normal and B-cell chronic lymphocytic leukemia subjects. Determinations were made with radiochemical methods associated with high performance liquid chromatography. Results indicated a marked increase in de novo purine synthesis enzymes, particularly those of the « inosinic branch point ». The latter were absent in normal lymphocytes, whereas they were well evident in leukemic lymphocytes, with the exception of AMP-S synthetase. Whereas the enzymes of the « salvage pathway » were spared in comparison to other proteins, those of the « catabolic pathway » significantly decreased. The authors discuss the possibility that such enzymes may be used as tumor markers.

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.

Prevalence of hypophysitis in a cohort of patients with metastatic melanoma and prostate cancer treated with ipilimumab

OBJECTIVE

Ipilimumab is a human monoclonal antibody directed against cytotoxic T-lymphocyte antigen-4, that has been shown to significantly improve survival in patients with metastatic melanoma. Blocking cytotoxic T-lymphocyte antigen-4 elicits T cell activation, proliferation and anti-tumor response, but can also trigger immune-related adverse events. Among immune-related endocrinopathies, hypophysitis represents the most frequent, with an incidence up to 17% in patients treated with ipilimumab.

DESIGN AND METHODS

We report nine cases of ipilimumab-induced hypophysitis in a cohort of 273 patients treated with ipilimumab between 2006 and 2015, as part of clinical trials or after its marketing. Thyroid function tests were scheduled at screening and during follow up (every 21 days) in all patients. Cortisol, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, and estradiol (for females) or testosterone (for males), prolactin, growth hormone, insulin-like growth factor 1 were measured only in case of clinical suspicion.

RESULTS

The incidence of hypophysitis was 3.3%. The most frequent pituitary failure was adrenocorticotropic hormone and thyroid stimulating hormone secretion with a complete recovery of thyroid stimulating hormone, but not of adrenocorticotropic hormone during follow up. All patients had negative pituitary antibodies. The main symptoms at diagnosis were fatigue and headache.

CONCLUSION

Clinicians should be aware about the risk of hypophysitis during treatment with immune check-point inhibitors and the necessity of investigating pituitary function during therapy. Pituitary magnetic resonance imaging does not seem pivotal for a definite diagnosis if not performed at the onset of disease.

Synthetic Gel of Carotid Artery Plaque

Atherosclerosis is a complex disease that affects medium and large arteries, leading to the formation and progression of plaque. In this process the proteins play an essential role and as a consequence, proteomic-based strategies examining the protein content of cells or tissues could offer a useful approach for the study of plaque proteins. Due to the heterogeneous cell composition of plaque, proteome analysis of whole lesions is difficult, besides being also complicated by the presence of plasma proteins that cannot be completely eliminated. A good way to study variations in protein expression among series of gels is to construct a synthetic gel. This type of gel is obtained by averaging the positions, shapes and optical densities of spots in a given set of gels. To be included in the synthetic gel, spots must be found in at least three gels. To obtain a profile representative of the proteome of atherosclerotic plaque, canceling its high variability, we constructed a synthetic gel using an average of ten carotid plaque samples. We then compared it with an equivalent synthetic gel constructed using ten plasma samples from the same carotid surgery patients. For the comparison of two synthetic gels (plasma/plaque) we could discriminate plasma proteins from plaque proteins. Besides analysis of spots common to plasma, the synthetic gel is useful to detect spots exclusive to plaque, thus simplifying a very complex mixture.

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.

High levels of soluble CTLA-4 are present in anti-mitochondrial antibody positive, but not in antibody negative patients with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic autoimmune cholestatic liver disease frequently characterized by anti-mitochondrial autoantibodies (AMA). A minority of patients are AMA-negative. Cytotoxic-T-Lymphocyte-Antigen-4 (CTLA-4) is a surface molecule expressed on activated T-cells delivering a critical negative immunoregulatory signal. A soluble form of CTLA-4 (sCTLA-4) has been detected at high concentrations in several autoimmune diseases, and its possible functional meaning has been suggested. We aimed to evaluate sCTLA-4 concentration in sera of patients with PBC and to correlate it to immunological abnormalities associated with the disease. Blood samples were collected from 82 PBC-patients diagnosed according to international criteria (44 AMA-positive/MIT3-positive and 38 AMA-negative-MIT3-negative), and 65 controls. sCTLA-4 levels were evaluated by ELISA and Western blot. Increased sCTLA-4 concentrations were found in all AMA-positive PBC-patients, but in none of the AMA-negative ones, nor in normal controls or in controls with unrelated liver diseases. sCTLA-4 presence was associated with autoantibodies against MIT3, but not with nuclear autoantibodies (sp100, gp210). This is the first study to demonstrate that levels of sCTLA-4 are elevated in sera of PBC patients. However, they are clearly restricted to patients with AMA positivity, suggesting an immunological difference with respect to AMA-negative ones.

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.

Autoantibody Profiling in a Cohort of Pediatric and Adult Patients With Autoimmune Hepatitis

BACKGROUND

Autoimmune hepatitis (AIH) is a rare condition characterized by the presence of autoantibodies distinctive of type 1 AIH (AIH-1) and type 2 AIH (AIH-2). The aim of this study was to evaluate the autoantibody profile in a cohort of pediatric and adult AIH patients, using both indirect immunofluorescence (IIF) and a new multiplexed line-blot assay.

METHODS

Sera from 63 pediatric and 53 adult AIH patients were tested for antinuclear (ANA), antismooth muscle (SMA), anti-liver kidney microsome 1 (anti-LKM1), anti-liver cytosol 1 (anti-LC1) autoantibodies using IIF methods; for anti-LKM1, anti-LC1, and soluble liver antigen/liver-pancreas (anti-SLA/LP) autoantibodies using the line-blot; for anti-F-actin autoantibodies using IIF both on VSM47 cell-line and on rat intestinal epithelial cells.

RESULTS

AIH-1 was the most common type of AIH in the adult cohort (73.6%), while AIH-2 was the most common AIH in the pediatric cohort (61.9%). Both in adult and pediatric AIH-2 anti-LKM1 were the prevalent autoantibodies. In pediatric AIH-2 anti-LC1 autoantibodies were more frequent than in adult AIH-2 (59 vs. 28.6%), and in 35.9% of cases they were present alone. In 17 patients anti-LC1 autoantibodies were detected only with the line-blot assay. The levels of anti-LKM1 and of anti-LC1 were not different between adult and pediatric AIH, and the overall agreement between the results obtained with the two IIF methods for F-actin detection was 98.8% (CI 95%: 94.4-99.7%).

CONCLUSIONS

The line-blot assay showed a higher sensitivity than IIF for anti-LC1 detection. Anti-LKM1 and anti-LC1 autoantibody levels are not different in adults and children. An almost perfect agreement between the two IIF methods for anti-F-actin detection has been observed.

Detection of autoantibodies against actin filaments in celiac disease

INTRODUCTION

Serum autoantibodies specifically directed toward intracellular cytoskeletal actin filaments (anti-actin antibodies, AAA) were found to be associated with intestinal villous atrophy (IVA) in celiac disease (CD). The aim of this study was to assess IgA-AAA with a commercial test that uses sections of rat intestinal epithelial cells in a well-selected cohort of patients and to evaluate the relationship between the presence of serum IgA-AAA and the severity of intestinal mucosa damage.

MATERIALS AND METHODS

Serum samples from 70 CD patients and 150 controls subjects were analyzed retrospectively for the presence of IgA-AAA.

RESULTS

The indirect immunofluorescence test that we used has a specificity of 100%; the sensitivity of the test is not high (25.7%). In this study we also show that serum AAA are more frequently positive in CD patients with total IVA (77.8%) and that this association is significant

DISCUSSION

IgA-AAA certainly cannot take the place of much more sensitive tests such as a-tTG and EMA in the diagnosis of CD because of their low sensitivity; nonetheless, these antibodies could be determined in a-tTG and/or EMA positive patients who cannot undergo an intestinal biopsy because of a severe contraindication, or in the case of negative consensus regarding endoscopy, or when the histology interpretation is difficult.

CONCLUSION

In conclusion, the IFI commercial test with intestinal epithelial cells as substrate offers a useful method for IgA-AAA determination. Serum IgA-AAA positivity is indicative of more severe intestinal histology damage and their assay could be a real help to the clinician, especially in the complicated cases.

Automation in indirect immunofluorescence testing: a new step in the evolution of the autoimmunology laboratory

Indirect immunofluorescence (IIF) plays an important role in immunological and immunometric assays for detecting and measuring autoantibodies. This technology was the first multiplex method used to detect cardinal autoantibodies for the diagnosis of autoimmune diseases. Over the last 20 years, research has enabled the progressive identification of cell and tissue autoantigens which are the target of autoantibodies originally detected by IIF. Accordingly, newer immunometric methods, capable of measuring concentrations of specific autoantibodies directed against these autoantigens, allowed for a gradual replacement of the IIF method in the autoimmunology laboratory. Currently, IIF remains the method of choice only in selected fields of autoimmune diagnostics. Following the recent statement by the American College of Rheumatology that the IIF technique should be considered as the standard screening method for the detection of ANA, the biomedical industry has developed technological solutions which significantly improve automation of the procedure, not only in the preparation of substrates and slides, but also in microscope reading. This review summarizes the general and specific features of new available commercial systems (Aklides, Medipan; Nova View, Inova; Zenit G Sight, A. Menarini Diagnostics; Europattern, Euroimmun; Helios, Aesku.Diagnostics; Image Navigator, Immuno Concepts; Cytospot, Autoimmun Diagnostika) for automation of the IIF method. The expected advantages of automated IIF are the reduction in frequency of false negative and false positive results, the reduction of intra- and inter-laboratory variability, the improvement of correlation of staining patterns with corresponding autoantibody reactivities, and higher throughput in the laboratory workflow.

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.

Erythropoiesis, erythropoietin and blood lead levels

In a previous study EPO values were significantly lower in exposed subjects (PbB > or =30 mcg/dl) than in controls (PbB" 20 mcg/dl). The aim of the study was to verify if high PbB cause the reduction of EPO in connection with the serum concentration of this hormone expected considering the Hct and hemoglobin (Hb) levels. Both in Pb exposed workers and controls blood levels of EPO, PbB, Hb, Hct were measured. It was not observed any line relation between Hct e log EPO (p = 0.01) and any multiple regression relation between log EPO, Hct and PbB into the total studied population. In our subjects PbB does not change physiologic relation between EPO and Hct and between EPO and Hb. Maybe because normal levels of Hct and Hb reduce EPO production in the healthy population. In physiologic condition of erythropoiesis, EPO does not seem influenced by PbB.

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Purine nucleotide catabolism in rat liver. Certain preliminary aspects of uricase reaction

We investigated the mechanism of action of uricase, which oxidizes uric acid to allantoin, in the rat. Allantoin may decompose chemically to urea and hydantoin, containing the carbons in positions 2 and 8 of the purine ring, respectively. These carbons are derived by formylation, catalyzed by formyltransferase, in two reactions of de novo synthesis. Since uric acid and allantoin are represented in equivalent amounts in the liver, we expected to find identical incorporation of radioactivity in C(2) and C(8) of both compounds after administration of (14)C-formate. In the case of (14)C-allantoin, this was true, but not for (14)C-uric acid extracted from rat liver. We interpret these results through a series of experiments and considerations.

Antioxidant status and purine bases in carotid artery plaque

Free radical excess and oxidative stress are implicated in the formation and progression of atherosclerotic plaque through actions on susceptible vascular cells, such as by activating xanthine oxidase. Purine bases and other antioxidant compounds could play important protective roles in atherogenesis, as could nonenzymatic low molecular weight thiol defenses, not previously evaluated in carotid artery plaque. Therefore, we measured purine catabolites (hypoxanthine, xanthine, uric acid, allantoin) and antioxidant compounds (total sulphydryl groups, homocysteine, cysteine, and glutathione) in advanced carotid artery plaque and found a high ratio of allantoin to uric acid, suggesting a ongoing local oxidative stress.

Simultaneous determination of serum concentrations of levodopa, dopamine, 3-O-methyldopa and alpha-methyldopa by HPLC

Levodopa is the medication of choice for Parkinson's disease. The biological complexity of levodopa and of its main derivatives makes their determination important in the clinical field. The aim of this study was to develop an HPLC method for the simultaneous determination of serum concentrations of levodopa, dopamine, 3-O-methyldopa and alpha-methyldopa. We compared UV and fluorimetric detection of native and derivatised compounds. Though less sensitive than other methods, UV detection is important to exclude naturally fluorescent, interfering substances. Fluorimetric detection of derivatised compounds is more sensitive than UV detection. Since 3-O-methyldopa does not react with the derivatising agent 1,2-diphenylethylenediamine, it cannot be detected. For simultaneous determination of the four compounds after pharmacological treatment of patients we therefore advise fluorimetric detection of the native compound.

Purine catabolism in advanced carotid artery plaque

This study was carried out on carotid artery plaque and plasma of 50 patients. We analyzed uric acid, hypoxanthine, xanthine, and allantoin levels to verify if enzymatic purine degradation occurs in advanced carotid plaque; we also determined free radicals and sulphydryl groups to check if there is a correlation between oxidant status and purine catabolism. Comparing plaque and plasma we found higher levels of free radicals, hypoxanthine, xanthine, and a decrease of some oxidant protectors, such as sulphydryl groups and uric acid, in plaque. We also observed a very important phenomenon in plaque, the presence of allantoin due to chemical oxidation of uric acid, since humans do not have the enzyme uricase. The hypothetical elevated activity of xanthine oxidase in atherosclerosis could be reduced by specific therapies using its inhibitors, such as oxypurinol or allopurinol.

EPR spin trapping of a radical intermediate in the urate oxidase reaction

Urate oxidase, or uricase (EC 1.7.3.3), is a peroxisomal enzyme that catalyses the oxidation of uric acid to allantoin. The chemical mechanism of the urate oxidase reaction has not been clearly established, but the involvement of radical intermediates was hypothesised. In this study EPR spectroscopy by spin trapping of radical intermediates has been used in order to demonstrate the eventual presence of radical transient urate species. The oxidation reaction of uric acid by several uricases (Porcine Liver, Bacillus Fastidiosus, Candida Utilitis) was performed in the presence of 5-diethoxyphosphoryl-5-methyl-pyrroline-N-oxide (DEPMPO) as spin trap. DEPMPO was added to reaction mixture and a radical adduct was observed in all cases. Therefore, for the first time, the presence of a radical intermediate in the uricase reaction was experimentally proved.

Effect of testosterone on purine nucleotide metabolism in rat liver

In previous studies, we found that castration induced interesting morphological and biochemical changes in rat liver. For the present study, we have examined the effects of testosterone on the kinetics of purine nucleotide metabolism with the aim of determining the steps affected by testosterone deficiency. A biomathematical model of purine nucleotide metabolism was used to analyze the many reactions involved. The model simplifies purine nucleotide metabolism to four main steps: 1) de novo synthesis from PRPP to IMP; 2) the inosinic branch point from IMP to GMP or AMP; 3) catabolism of IMP, AMP and GMP to uric acid; 4) RNA and DNA formation from AMP and GMP. We evaluated rate constants from each step from variations in specific radioactivity of metabolites labelled with (14)C-formate, a precursor of de novo synthesis. The model was applied to the liver of normal and castrated rats before and after testosterone treatment. All four steps were slowed after castration, and were not completely restored by androgen administration. The model can give a clear representation of the kinetics of the reactions involved in the liver nucleotide metabolism investigated here, and we propose that a similar approach could be useful whenever a quantitative evaluation of the results obtained in vivo after administration of labelled precursors is required.

Purine bases and atheromatous plaque

In this work we determined hypoxanthine (HX), xanthine (X), uric acid (UA), allantoin (ALL) and free radicals in atheromatous plaques to improve the comprehension of oxidative stress, a phenomenon which characterizes the evolution of atherosclerotic lesions. Carotid artery plaque were obtained from subjects undergoing endoarterectomy. Pulverized plaque, extracted by water, was used for analysis of oxidative stress factors (allantoin, uric acid, xanthine, hypoxanthine, free radicals). The peroxidation UA-->ALL was very high in the plaque, as was the level of free radicals. The results show that oxidative degradation of nucleotides, such as LDL oxidation, plays a specific role not only in the progression of atherosclerotic lesions but also in the advanced plaque.

Purine nucleotide catabolism in rat liver: labelling of uric acid and allantoin after administration of various labelled precursors

Uric acid and allantoin are the key compounds of purine nucleotide catabolism formed in liver and many other organs of the rat. We observed that, after administration of 14C-formate, incorporation of radioactivity into uric acid and allantoin is not similar, as one would expect. The phenomenon was demonstrated to be specific to liver and perfused liver, and not to other organs such as heart, jejunal mucosa, lung, spleen, and kidney. To interpret these results, the specific radioactivity of uric acid and allantoin in rat liver were analysed comparatively, after administration of the following labelled precursors: 14C-glycine, 14C-formate, 14C-hypoxanthine, 14C-uric acid and 14C-adenine. After administration of 14C-formate the specific radioactivity of allantoin was higher than that of uric acid and the same behavior was observed after 14C-uric acid and 14C-hypoxanthine, but not after 14C-glycine and 14C-adenine administration. The results indicate that the rate of their incorporation into uric acid and allantoin, and the subsequent export of these compounds into serum, can only partially explain the observed phenomenon, while the presence of different pools of uric acid and allantoin may give a complete explanation.

Expression of p185 and p53 in benign and malignant colorectal lesions

The c-erbB2 gene has been found to be amplified in a number of human adenocarcinomas, leading to elevated levels of expression of its encoded product, p185. Mutations in the p53 gene are also common in colorectal carcinomas, brain tumours, leukaemia and lymphomas. In this study, p185 and p53 overexpression was analyzed in colorectal adenomas (22 tubular adenomas and 2 tubulo-villous adenomas) and moderately differentiated adenocarcinomas (n = 22) in order to determine whether there was a relationship between these two proteins. The proteins are encoded by two genes located in the same chromosome. p185 and p53 expression was determined on tissue sections by immunohistochemical staining procedure. Expression of p185 was significantly higher (p < 0.01) in preneoplastic lesions (95.8% of cases) than colorectal cancer (63.6% of cases). p53 showed an inverse pattern to p185, being expressed in 58.3% of benign lesions and 72.7% of adenocarcinomas. These results confirm that p185 overexpression is associated with the early stages of colorectal cancer, whereas p53 is associated with more advanced stages. Although there was no correlation between p185 and p53 expression in premalignant lesions and adenocarcinomas, these two proteins have an important role in the adenoma-carcinoma sequence.