Gabriella Passerini

Cross-validation of biomarkers for the early differential diagnosis and prognosis of dementia in a clinical setting

PurposeThe aim of this study was to evaluate the supportive role of molecular and structural biomarkers (CSF protein levels, FDG PET and MRI) in the early differential diagnosis of dementia in a large sample of patients with neurodegenerative dementia, and in determining the risk of disease progression in subjects with mild cognitive impairment (MCI).MethodsWe evaluated the supportive role of CSF Aβ42, t-Tau, p-Tau levels, conventional brain MRI and visual assessment of FDG PET SPM t-maps in the early diagnosis of dementia and the evaluation of MCI progression.ResultsDiagnosis based on molecular biomarkers showed the best fit with the final diagnosis at a long follow-up. FDG PET SPM t-maps had the highest diagnostic accuracy in Alzheimer’s disease and in the differential diagnosis of non-Alzheimer’s disease dementias. The p-tau/Aβ42 ratio was the only CSF biomarker providing a significant classification rate for Alzheimer’s disease. An Alzheimer’s disease-positive metabolic pattern as shown by FDG PET SPM in MCI was the best predictor of conversion to Alzheimer’s disease.ConclusionIn this clinical setting, FDG PET SPM t-maps and the p-tau/Aβ42 ratio improved clinical diagnostic accuracy, supporting the importance of these biomarkers in the emerging diagnostic criteria for Alzheimer’s disease dementia. FDG PET using SPM t-maps had the highest predictive value by identifying hypometabolic patterns in different neurodegenerative dementias and normal brain metabolism in MCI, confirming its additional crucial exclusionary role.

Diagnostic value of IgG4 Indices in IgG4-Related Hypertrophic Pachymeningitis ☆ ☆☆ ★

Diagnosis of IgG4-Related Hypertrophic Pachymeningitis (IgG4-HP) relies on meningeal biopsies, because cerebrospinal fluid (CSF) diagnostic biomarkers are lacking. Here, we determined whether IgG4 intrathecal production could distinguish IgG4-HP from other disorders presenting with HP (OHP). In patients with IgG4-HP, the median CSF IgG4 concentration, IgG4 Index and IgG4Loc were significantly higher than in both controls and OHP. CSF IgG4 levels higher than 2.27mg/dL identified 100% of IgG4-HP and 5% of OHP. An IgG4Loc cut-off of 0.47 identified 100% of IgG4-HP and no cases of OHP. Our results support CSF IgG4 quantification and IgG4 Indices as alternatives to meningeal biopsy for the diagnosis of IgG4-HP when this procedure is contraindicated or uninformative.

Cerebrospinal Fluid Analysis in Immunoglobulin G4-related Hypertrophic Pachymeningitis

To the Editor: Immunoglobulin G4-related disease (IgG4-RD) is characterized by fibrous swelling of affected organs, elevations in serum IgG4 concentrations, and responsiveness to glucocorticoid treatment1. Affected tissues display similar histological features: diffuse lymphoplasmacytic infiltration by numerous IgG4-positive plasma cells, occasional eosinophils, storiform fibrosis, and obliterative phlebitis2. IgG4-related hypertrophic pachymeningitis (IgG4-HP) has been identified as a characteristic central nervous system (CNS) manifestation of IgG4-RD, but comprehensive cerebrospinal fluid (CSF) analyses are substantially lacking3,4. Recently, we demonstrated an intrathecal IgG and IgG4 synthesis in the CSF of a patient with IgG4-HP and suggested IgG4 Indices as safe potential diagnostic tools for IgG4-HP5. Here, we describe 2 new cases of IgG4-HP with CSF evaluation at diagnosis and in response to treatment. In case 1, March 2007, a 56-year-old man was admitted with a 1-year history of right frontal headache. Magnetic resonance imaging (MRI) showed right frontal pachymeningitis. Granulomatous meningeal inflammation was suspected and oral prednisone (1 mg/kg body weight/day) was started with clinical and radiological improvement. Prednisone was discontinued after 8 months, but in July 2008 the headache recurred. Blood and CSF analyses are shown in Table 1. MRI evidenced a right frontotemporal progression of the pachymeningitis (Figure 1A). A meningeal biopsy … Address correspondence to Dr. E. Della-Torre, Department of Medicine and Clinical Immunology, San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy. E-mail: dellatorre.emanuel{at}hsr.it

Multicenter evaluation of hemoglobin A1c assay on capillary electrophoresis.

BACKGROUND Hemoglobin A1c (HbA1c) measurement is currently used for the routine monitoring of long-term glycemic status, thus playing a fundamental role in the management of this disease. Since this marker has recently been recommended as an additional tool for diagnosing diabetes, its of the utmost importance to ensure that the precision and accuracy of HbA1c methods are satisfactory. METHODS We assessed the analytical performances of the Capillarys 2 Flex Piercing® analyzer and compared the results obtained with those from two other widely used HPLC instruments. Furthermore, we evaluated the convenience and ergonomics of the system in authentic routine work conditions in three centers. RESULTS Within-laboratory (n=40) and between-laboratory (n=120) imprecision CV% using four blood samples with different concentrations of HbA1c were <3.4% and <3.1% using IFCC units and <2.1% and <2.0% using NGSP units, respectively. The obtained trueness (<3 mmol/mol, <0.3%) was highly satisfactory, nor was HbA1c measurement compromised by the presence of the commonly present hemoglobinopathies. The comparison made with established methods revealed excellent agreement (r>0.985). CONCLUSIONS The evaluated method is precise, accurate and robust, with a high throughput. It also allows the identification of the most frequent Hb variants and therefore may be a valid alternative to other methods currently proposed for routine use in clinical laboratories.

Cerebrospinal Fluid Biomarkers Can Play a Pivotal Role in the Diagnostic Work Up of Primary Progressive Aphasia

BACKGROUND Three variants of primary progressive aphasia (PPA) have been currently characterized: non fluent/agrammatic (nfv-PPA), semantic (sv-PPA), and logopenic variant (lv-PPA). lv-PPA is most commonly associated with Alzheimers disease (AD), while nfv-PPA and sv-PPA are related to frontotemporal lobar degeneration. OBJECTIVE We aimed to determine whether cerebrospinal fluid (CSF) amyloid-β42 (Aβ42), total tau protein (t-tau), and phosphorylated tau (p-tau), frequently abnormal in AD, could constitute a useful tool in the PPA diagnostic work up, in order to identify subjects with an underlying AD pathology. METHODS We measured CSF biomarker levels in a group of twenty-eight patients, fourteen lv-PPA, nine nfv-PPA, and five sv-PPA. RESULTS Since there were no significant differences in any of the parameters investigated between nfv-PPA and sv-PPA, the two groups were considered as one (nfv/sv-PPA). At diagnosis, lv-PPA were older than nfv/sv-PPA patients (mean values: 70.7 versus 64.6 years, p = 0.02). CSF biomarker mean concentrations were significantly different in lv-PPA versus nfv/sv-PPA patients (p = 0.000): Aβ42 350.64 versus 661.64 ng/L; tau 631.21 versus 232.71 ng/L; p-tau 101 versus 38.21 ng/L. According to the recent AD diagnostic criteria, (Cummings et al., 2013) eleven lv-PPA and only one nfv/sv-PPA showed a liquoral pattern typical for AD. Finally lv-PPA had CSF biomarker levels very similar to a sample of 72 AD patients from our Department. CONCLUSIONS Our data showed that CSF biomarkers can easily and reliably detect those patients with language disorders due to an underlying AD pathology, thus offering the possibility of targeted therapeutic interventions. However, because of the small sample size, such analyses should be reproduced in larger populations of patients to confirm our data.

Combining Cerebrospinal Fluid Biomarkers and Neuropsychological Assessment: A Simple and Cost-Effective Algorithm to Predict the Progression from Mild Cognitive Impairment to Alzheimer’s Disease Dementia

BACKGROUND Correctly diagnosing Alzheimers disease (AD) in prodromal phases would allow the adoption of experimental therapeutic strategies that could selectively interrupt the pathogenetic process before neuronal damage becomes irreversible. Therefore, great efforts have been aimed at finding early reliable disease markers. OBJECTIVE The aim of this study was to identify a simple, cost effective, and reliable diagnostic algorithm to predict conversion from mild cognitive impairment (MCI) to AD. METHODS 96 consecutive MCI patients admitted to the Neurology department of San Raffaele Hospital in Milan between January 2009 and January 2015 were included. All patients underwent neuropsychological assessment and lumbar puncture with CSF analysis of amyloid-β 42 (Aβ42), total tau (t-tau), and phosphorylated tau (p-tau) levels. Each patient underwent clinical and neuropsychological follow-up, in order to identify a possible progression from MCI to AD. The mean follow up time was 36.73 months. RESULTS 37 out of 96 MCI converted to AD during follow up. CSF analysis and neuropsychological assessment reliably detected MCI patients who developed AD. In a subsample of 43 subjects, a Composite Cognitive Score (CCS) was calculated including episodic memory, executive function, and verbal fluency tests. Combining together CSF biomarkers and CCS increased the accuracy of the single predictors, correctly classifying 86% of patients with a specificity of 96% and a Positive Predictive Value of 93%. DISCUSSION Even if preliminary, our data seem to suggest that CSF analysis and neuropsychological assessment could detect MCI patients who will convert to AD with high confidence. Their relative low cost and availability could make them worldwide essential tools in future clinical trials.

Clinical significance of the number of oligoclonal bands in patients with clinically isolated syndromes

CSF oligoclonal bands (OCBs) in patients with clinically isolated syndromes (CIS) are a risk factor for clinically definite multiple sclerosis (CDMS). We aimed to address the relevance of the number of OCBs in the prognosis of CIS patients. 219 CIS patients were included in the study, and 42% of them developed the disease during follow-up (median: 5.04 years). Patients with a high number of CSF OCBs (third quartile, 8-12 OCBs) had 2.5-fold increase in CDMS risk, while no further increase in the HR of disease was observed for patients with more than 12 OCBs. The results did not change after adjustment for additional correlates of CDMS development. This association may be due to the epitope-spreading phenomenon and may reflect the stage of the disease at the time of the examination.

Free Light Chains and Intrathecal B Cells Activity in Multiple Sclerosis: A Prospective Study and Meta-Analysis.

Background. The presence of CSF oligoclonal bands (OBs) is an independent prognostic factor for multiple sclerosis (MS), but the difficulties in the standardization of the test and the interlaboratory variation in reporting have contributed to its limited use in the diagnosis of the disease. Standard nephelometric assays to measure free light chains (FLC) levels have been recently developed and the test may improve the detection of intrathecal B cells activity. Methods. The presence of OBs, kappa and lambda FLC levels, and standard indices of intrathecal inflammation were assessed in 100 consecutive patients, including patients with MS, clinically isolated syndromes (CIS), other inflammatory diseases of the CNS, and other noninflammatory diseases. Results. Both KFLC and LFLC correlated strongly with the presence of OCBs and with all common tests for intrathecal inflammation (p < 0.001 for all comparisons). KFLC and LFLC were significantly different in patients with MS and CIS compared to the other groups (p < 0.001 and p < 0.001, resp.) and had a better diagnostic accuracy than all the other tests (area under the curve 82.3 % for KFLC index and 79.3 % for LFLC index). Conclusion. Nephelometric assays for KFLC in CSF reliably detect intrathecal immunoglobulin synthesis and discriminate MS patients.

Cerebrospinal fluid analysis and the determination of oligoclonal bands

This document presents the guidelines for the cerebrospinal fluid (CSF) analysis and the determination of oligoclonal bands (OCBs) as pivotal tests in neuroinflammatory pathologies of the central nervous system. The guidelines have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on the pathologies in which the CSF analysis is indicated, and, particularly, on those characterized by the presence of OCBs in the intrathecal compartment, indications and limits of CSF analysis and OCB determination, instructions for result interpretation, and agreed laboratory protocols (Appendix) are reported for the communicative community of neurologists and clinical pathologists.

Evaluation of the performance of an immunoturbidimetric HbA1c reagent applied to the Siemens ADVIA 2400 automatic analyzer.

OBJECTIVES A new immunochemical reagent based on latex particles and antibodies against HbA1c (Axis-Shield), using Siemens ADVIA 2400 Instrument was evaluated. DESIGN AND METHODS Intra-assay and total imprecision, interferences studies (bilirubin ~850 μmol/L, triglycerides ~16.9 mmol/L, total protein ~140 g/L, sodium cyanate ~50 mg/dL, ascorbic acid ~50 mg/dL, urea ~24.99 mmol/L, glucose ~105.46 mmol/L, rheumatoid factor ~600 U/mL), method comparison vs Capillary Electrophoresis (Sebia), Lot to Lot reproducibility, linearity and carry over were conducted on ADVIA 2400 according to CLSI protocols. Additionally, 40 samples were measured by the two methods and also by a NGSP reference lab. RESULTS CVs % obtained by intra-assay imprecision, on 3 human HbA1c specimens at different concentrations (48, 48-64 and >64 mmol/mol) in 20 replicates, were <4%. CVs % by total imprecision, performed over 20 days with 4 calibrations on 3 human HbA1c samples (48, 48-64 and >64 mmol/mol), resulted <4%. Interferences were studied on two human samples (42-53 and>64 mmol/mol) without obtaining significant biases (<10%). Methods comparison vs Capillary Electrophoresis, performed on 120 samples ranging 23-137 mmol/mol, obtaining r = 0.974 as regression coefficient and a mean bias at decision level (48 mmol/mol) <3%. The results obtained with the NGSP samples have allowed the certification of the new reagent. CONCLUSIONS The ASD reagent met the needs of clinical laboratories, fulfilling both NGSP and IFCC requirements and it is robust to endogenous interferences.