Interaction of amyloid and tau on cortical microstructure in cognitively unimpaired adults.

INTRODUCTION: Neurite orientation dispersion and density imaging (NODDI), a multi-compartment diffusion-weighted imaging (DWI) model, may be useful for detecting early cortical microstructural alterations in Alzheimer's disease prior to cognitive impairment. METHODS: Using neuroimaging (NODDI and T1-weighted magnetic resonance imaging [MRI]) and cerebrospinal fluid (CSF) biomarker data (measured using Elecsys® CSF immunoassays) from 219 cognitively unimpaired participants, we tested the main and interactive effects of CSF amyloid beta (Aß)42 /Aß40 and phosphorylated tau (p-tau) on cortical NODDI metrics and cortical thickness, controlling for age, sex, and apolipoprotein E ε4. RESULTS: We observed a significant CSF Aß42 /Aß40 × p-tau interaction on cortical neurite density index (NDI), but not orientation dispersion index or cortical thickness. The directionality of these interactive effects indicated: (1) among individuals with lower CSF p-tau, greater amyloid burden was associated with higher cortical NDI; and (2) individuals with greater amyloid and p-tau burden had lower cortical NDI, consistent with cortical neurodegenerative changes. DISCUSSION: NDI is a particularly sensitive marker for early cortical changes that occur prior to gross atrophy or development of cognitive impairment.

An examination of a novel multipanel of CSF biomarkers in the Alzheimer's disease clinical and pathological continuum.

INTRODUCTION: This study examines the utility of a multipanel of cerebrospinal fluid (CSF) biomarkers complementing Alzheimer's disease (AD) biomarkers in a clinical research sample. We compared biomarkers across groups defined by clinical diagnosis and pTau181 /Aß42 status (+/-) and explored their value in predicting cognition. METHODS: CSF biomarkers amyloid beta (Aß)42 , pTau181 , tTau, Aß40 , neurogranin, neurofilament light (NfL), α-synuclein, glial fibrillary acidic protein (GFAP), chitinase-3-like protein 1 (YKL-40), soluble triggering receptor expressed on myeloid cells 2 (sTREM2), S100 calcium binding protein B (S100B), and interleukin 6 (IL6), were measured with the NeuroToolKit (NTK) for 720 adults ages 40 to 93 years (mean age = 63.9 years, standard deviation [SD] = 9.0; 50 with dementia; 54 with mild cognitive impairment [MCI], 616 unimpaired). RESULTS: Neurodegeneration and glial activation biomarkers were elevated in pTau181 /Aß42 + MCI/dementia participants relative to all pTau181 /Aß42 - participants. Neurodegeneration biomarkers increased with clinical severity among pTau181 /Aß42 + participants and predicted worse cognitive performance. Glial activation biomarkers were unrelated to cognitive performance. DISCUSSION: The NTK contains promising markers that improve the pathophysiological characterization of AD. Neurodegeneration biomarkers beyond tTau improved statistical prediction of cognition and disease stages.

The Alzheimer's Association international guidelines for handling of cerebrospinal fluid for routine clinical measurements of amyloid ß and tau.

The core cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarkers amyloid beta (Aß42 and Aß40), total tau, and phosphorylated tau, have been extensively clinically validated, with very high diagnostic performance for AD, including the early phases of the disease. However, between-center differences in pre-analytical procedures may contribute to variability in measurements across laboratories. To resolve this issue, a workgroup was led by the Alzheimer's Association with experts from both academia and industry. The aim of the group was to develop a simplified and standardized pre-analytical protocol for CSF collection and handling before analysis for routine clinical use, and ultimately to ensure high diagnostic performance and minimize patient misclassification rates. Widespread application of the protocol would help minimize variability in measurements, which would facilitate the implementation of unified cut-off levels across laboratories, and foster the use of CSF biomarkers in AD diagnostics for the benefit of the patients.

Current state of Alzheimer's fluid biomarkers.

Alzheimer's disease (AD) is a progressive neurodegenerative disease with a complex and heterogeneous pathophysiology. The number of people living with AD is predicted to increase; however, there are no disease-modifying therapies currently available and none have been successful in late-stage clinical trials. Fluid biomarkers measured in cerebrospinal fluid (CSF) or blood hold promise for enabling more effective drug development and establishing a more personalized medicine approach for AD diagnosis and treatment. Biomarkers used in drug development programmes should be qualified for a specific context of use (COU). These COUs include, but are not limited to, subject/patient selection, assessment of disease state and/or prognosis, assessment of mechanism of action, dose optimization, drug response monitoring, efficacy maximization, and toxicity/adverse reactions identification and minimization. The core AD CSF biomarkers Aß42, t-tau, and p-tau are recognized by research guidelines for their diagnostic utility and are being considered for qualification for subject selection in clinical trials. However, there is a need to better understand their potential for other COUs, as well as identify additional fluid biomarkers reflecting other aspects of AD pathophysiology. Several novel fluid biomarkers have been proposed, but their role in AD pathology and their use as AD biomarkers have yet to be validated. In this review, we summarize some of the pathological mechanisms implicated in the sporadic AD and highlight the data for several established and novel fluid biomarkers (including BACE1, TREM2, YKL-40, IP-10, neurogranin, SNAP-25, synaptotagmin, α-synuclein, TDP-43, ferritin, VILIP-1, and NF-L) associated with each mechanism. We discuss the potential COUs for each biomarker.

CSF biomarkers of Alzheimer's disease concord with amyloid-ß PET and predict clinical progression: A study of fully automated immunoassays in BioFINDER and ADNI cohorts.

INTRODUCTION: We studied whether fully automated Elecsys cerebrospinal fluid (CSF) immunoassay results were concordant with positron emission tomography (PET) and predicted clinical progression, even with cutoffs established in an independent cohort. METHODS: Cutoffs for Elecsys amyloid-ß1-42 (Aß), total tau/Aß(1-42), and phosphorylated tau/Aß(1-42) were defined against [18F]flutemetamol PET in Swedish BioFINDER (n = 277) and validated against [18F]florbetapir PET in Alzheimer's Disease Neuroimaging Initiative (n = 646). Clinical progression in patients with mild cognitive impairment (n = 619) was studied. RESULTS: CSF total tau/Aß(1-42) and phosphorylated tau/Aß(1-42) ratios were highly concordant with PET classification in BioFINDER (overall percent agreement: 90%; area under the curve: 94%). The CSF biomarker statuses established by predefined cutoffs were highly concordant with PET classification in Alzheimer's Disease Neuroimaging Initiative (overall percent agreement: 89%-90%; area under the curves: 96%) and predicted greater 2-year clinical decline in patients with mild cognitive impairment. Strikingly, tau/Aß ratios were as accurate as semiquantitative PET image assessment in predicting visual read-based outcomes. DISCUSSION: Elecsys CSF biomarker assays may provide reliable alternatives to PET in Alzheimer's disease diagnosis.

The impact of preanalytical variables on measuring cerebrospinal fluid biomarkers for Alzheimer's disease diagnosis: A review.

INTRODUCTION: Cerebrospinal fluid (CSF) biomarkers have the potential to improve the diagnostic accuracy of Alzheimer's disease, yet there is a lack of harmonized preanalytical CSF handling protocols. METHODS: This systematic review summarizes the current literature on the influence of preanalytical variables on CSF biomarker concentration. We evaluated the evidence for three core CSF biomarkers: ß-amyloid 42, total tau, and phosphorylated tau. RESULTS: The clinically important variables with the largest amount of conflicting data included the temperature at which samples are stored, the time nonfrozen samples can be stored, and possible effects of additives such as detergents, blood contamination, and centrifugation. Conversely, we discovered that there is consensus that tube material has a significant effect. DISCUSSION: A unified CSF handling protocol is recommended to reduce preanalytical variability and facilitate comparison of CSF biomarkers across studies and laboratories. In future, experiments should use a gold standard with fresh CSF collected in low binding tubes.

A user's guide for α-synuclein biomarker studies in biological fluids: Perianalytical considerations.

Parkinson's disease biomarkers are needed to increase diagnostic accuracy, to objectively monitor disease progression and to assess therapeutic efficacy as well as target engagement when evaluating novel drug and therapeutic strategies. This article summarizes perianalytical considerations for biomarker studies (based on immunoassays) in Parkinson's disease, with emphasis on quantifying total α-synuclein protein in biological fluids. Current knowledge and pitfalls are discussed, and selected perianalytical variables are presented systematically, including different temperature of sample collection and types of collection tubes, gradient sampling, the addition of detergent, aliquot volume, the freezing time, and the different thawing methods. We also discuss analytical confounders. We identify gaps in the knowledge and delineate specific areas that require further investigation, such as the need to identify posttranslational modifications of α-synuclein and antibody-independent reference methods for quantification, as well as the analysis of potential confounders, such as comorbidities, medication, and phenotypes of Parkinson's disease in larger cohorts. This review could be used as a guideline for future Parkinson's disease biomarker studies and will require regular updating as more information arises in this growing field, including new technical developments as they become available. In addition to reviewing best practices, we also identify the current technical limitations and gaps in the knowledge that should be addressed to enable accurate and quantitative assessment of α-synuclein levels in the clinical setting. © 2017 International Parkinson and Movement Disorder Society.

Serum Levels of Hepatitis B Surface Antigen Predict Severity of Fibrosis in Patients With E Antigen-Positive Chronic Hepatitis B.

BACKGROUND & AIMS: Noninvasive techniques are needed to assess hepatic fibrosis in patients with chronic hepatitis B. We developed a scoring system to determine the degree of fibrosis in patients with genotype B or genotype C hepatitis B virus (HBV) infection and positive for the hepatitis B e antigen. METHODS: We performed a retrospective study to identify baseline variables associated with the severity of fibrosis (METAVIR scores, F0-F4) in a large phase 3 clinical trial of predominantly Asian patients (n = 710), using multivariate logistic regression analyses. Significant variables were used to construct predictive models using optimal cut-off values. The final model was validated in similar patients from a large phase 4 clinical trial (n = 465). RESULTS: We developed 2 prediction scoring systems (PSs). PS1 analyzed data on HBV genotype (B vs. C), patient age (<30 vs. ≥30 y), level of hepatitis B surface antigen (≤17,500 vs. >17,500 IU/mL), and level of alanine aminotransferase (≤3-fold vs. >3-fold the upper limit of normal). PS2 analyzed data on only age and level of hepatitis B surface antigen. PS1 identified patients with F0 to F1 vs. F2 to F4 fibrosis with more than 87% specificity and a positive predictive value greater than 75; it identified patients with F0 to F2 vs. F2 to F4 fibrosis with approximately 95% specificity and a positive predictive value (PPV) of approximately 97%. PS2 identified patients with F0 to F1 fibrosis with less accuracy than PS1, but identified patients with F0 to F2 fibrosis with an almost identical level of sensitivity and PPV. CONCLUSIONS: We developed a simple scoring system to determine the severity of fibrosis in patients with genotypes B or C HBV infection who are hepatitis B e antigen positive. Our system differentiated patients with no or mild fibrosis (F0-F1) from those with marked or severe (F2-F4) fibrosis with a high PPV. The high level of specificity for the identification of nonsevere fibrosis (F0-F2) limits the risk of overlooking patients with severe fibrosis (F3-F4).

Acceptable performance of blood biomarker tests of amyloid pathology - recommendations from the Global CEO Initiative on Alzheimer's Disease.

Anti-amyloid treatments for early symptomatic Alzheimer disease have recently become clinically available in some countries, which has greatly increased the need for biomarker confirmation of amyloid pathology. Blood biomarker (BBM) tests for amyloid pathology are more acceptable, accessible and scalable than amyloid PET or cerebrospinal fluid (CSF) tests, but have highly variable levels of performance. The Global CEO Initiative on Alzheimer's Disease convened a BBM Workgroup to consider the minimum acceptable performance of BBM tests for clinical use. Amyloid PET status was identified as the reference standard. For use as a triaging test before subsequent confirmatory tests such as amyloid PET or CSF tests, the BBM Workgroup recommends that a BBM test has a sensitivity of ≥90% with a specificity of ≥85% in primary care and ≥75-85% in secondary care depending on the availability of follow-up testing. For use as a confirmatory test without follow-up tests, a BBM test should have performance equivalent to that of CSF tests - a sensitivity and specificity of ~90%. Importantly, the predictive values of all biomarker tests vary according to the pre-test probability of amyloid pathology and must be interpreted in the complete clinical context. Use of BBM tests that meet these performance standards could enable more people to receive an accurate and timely Alzheimer disease diagnosis and potentially benefit from new treatments.

Hepatitis B surface antigen serum level is associated with fibrosis severity in treatment-naïve, e antigen-positive patients.

BACKGROUND & AIMS: Little is currently known about the association between serum HBsAg or HBV DNA levels and the severity of liver disease in chronic hepatitis B (CHB) patients. Therefore, we investigated these relationships in a large cohort of unselected, well-characterized, treatment-naïve CHB patients. METHODS: CHB patients were assessed at the Hôpital Beaujon in Paris, France, between 2000 and 2008. Serum samples and liver biopsies were obtained on the same day. HBsAg, HBV DNA, and HBV genotype were investigated using commercial diagnostic assays and liver histology was scored using the METAVIR system. RESULTS: 406 patients were included in this cross-sectional study. Serum HBsAg and HBV DNA levels in hepatitis B e antigen-positive (HBeAg[+]) patients showed strong correlation (r=0.44, p<0.0001), as did serum HBsAg levels and fibrosis severity (r=0.43, p<0.0001). HBeAg(+) patients with moderate to severe fibrosis exhibited significantly lower serum HBsAg and HBV DNA levels compared with patients with no or mild fibrosis. Modeling analysis suggested a serum HBsAg cut-off of 3.85 logIU/ml would provide a theoretical sensitivity of 100% (95% CI: 0-100), theoretical specificity of 86% (95% CI: 50-100), and a negative predictive value of 100% (95% CI: 67-100) in HBeAg(+) patients infected with HBV genotype B or C. CONCLUSIONS: We found an association between low serum HBsAg levels and moderate to severe fibrosis in HBeAg(+) CHB patients. Furthermore, we described a serum HBsAg cut-off for the prediction of fibrosis severity in CHB patients infected with HBV genotype B or C.

Blood-based biomarkers for Alzheimer's disease: Current state and future use in a transformed global healthcare landscape.

Timely detection of the pathophysiological changes and cognitive impairment caused by Alzheimer's disease (AD) is increasingly pressing because of the advent of biomarker-guided targeted therapies that may be most effective when provided early in the disease. Currently, diagnosis and management of early AD are largely guided by clinical symptoms. FDA-approved neuroimaging and cerebrospinal fluid biomarkers can aid detection and diagnosis, but the clinical implementation of these testing modalities is limited because of availability, cost, and perceived invasiveness. Blood-based biomarkers (BBBMs) may enable earlier and faster diagnoses as well as aid in risk assessment, early detection, prognosis, and management. Herein, we review data on BBBMs that are closest to clinical implementation, particularly those based on measures of amyloid-ß peptides and phosphorylated tau species. We discuss key parameters and considerations for the development and potential deployment of these BBBMs under different contexts of use and highlight challenges at the methodological, clinical, and regulatory levels.

The age-specific comorbidity burden of mild cognitive impairment: a US claims database study.

BACKGROUND: Identifying individuals with mild cognitive impairment (MCI) who are likely to progress to Alzheimer's disease and related dementia disorders (ADRD) would facilitate the development of individualized prevention plans. We investigated the association between MCI and comorbidities of ADRD. We examined the predictive potential of these comorbidities for MCI risk determination using a machine learning algorithm. METHODS: Using a retrospective matched case-control design, 5185 MCI and 15,555 non-MCI individuals aged ≥50 years were identified from MarketScan databases. Predictive models included ADRD comorbidities, age, and sex. RESULTS: Associations between 25 ADRD comorbidities and MCI were significant but weakened with increasing age groups. The odds ratios (MCI vs non-MCI) in 50-64, 65-79, and ≥ 80 years, respectively, for depression (4.4, 3.1, 2.9) and stroke/transient ischemic attack (6.4, 3.0, 2.1). The predictive potential decreased with older age groups, with ROC-AUCs 0.75, 0.70, and 0.66 respectively. Certain comorbidities were age-specific predictors. CONCLUSIONS: The comorbidity burden of MCI relative to non-MCI is age-dependent. A model based on comorbidities alone predicted an MCI diagnosis with reasonable accuracy.

Hepatitis B virus surface antigen levels: a guide to sustained response to peginterferon alfa-2a in HBeAg-negative chronic hepatitis B.

UNLABELLED: We investigated the relationship between hepatitis B virus surface antigen (HBsAg) serum level decline and posttreatment response in patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B from a large multinational study of pegylated interferon alfa-2a (peginterferon alfa-2a), with or without lamivudine, versus lamivudine alone. Serum HBsAg was quantified using the Architect assay (Abbott Diagnostics) at pretreatment, end of treatment (week 48), and 6 months after the end of treatment (week 72) in sera from 386 of the 537 patients who participated in the multinational study (peginterferon alfa-2a, 127; peginterferon alfa-2a plus lamivudine, 137; lamivudine monotherapy, 122). Pretreatment HBsAg levels varied according to genotype, with the highest levels present in patients infected with genotypes A (median, 4.11 log(10) IU/mL) and D (median, 3.85 log(10) IU/mL). Significant on-treatment decline in HBsAg was observed during treatment with peginterferon alfa-2a (alone or combined with lamivudine; mean decline at week 48, -0.71 and -0.67 log(10) IU/mL, respectively, P < 0.001), but not during treatment with lamivudine alone (-0.02 log(10) IU/mL). Significantly more patients treated with peginterferon alfa-2a (21%) or peginterferon alfa-2a plus lamivudine (17%) achieved HBsAg levels <100 IU/mL at the end of treatment compared with lamivudine (1%) (both P < 0.001 versus lamivudine). End-of-treatment HBsAg level correlated strongly with HBV DNA suppression to 1 log(10) IU/mL were significantly associated with sustained HBsAg clearance 3 years after treatment (both P < 0.0001). CONCLUSION: On-treatment quantification of HBsAg in patients with HBeAg-negative chronic hepatitis B treated with peginterferon alfa-2a may help identify those likely to be cured by this therapy and optimize treatment strategies.

Preanalytical sample handling recommendations for Alzheimer's disease plasma biomarkers.

INTRODUCTION: We examined the influence of common preanalytical factors on the measurement of Alzheimer's disease-specific biomarkers in human plasma. METHODS: Amyloid ß peptides (Aß[1-40], Aß[1-42]) and total Tau plasma concentrations were quantified using fully automated Roche Elecsys assays. RESULTS: Aß(1-40), Aß(1-42), and total Tau plasma concentrations were not affected by up to three freeze/thaw cycles, up to five tube transfers, the collection tube material, or the size; circadian rhythm had a minor effect. All three biomarkers were influenced by the anticoagulant used, particularly total Tau. Aß concentrations began decreasing 1 hour after blood draw/before centrifugation and decreased by up to 5% and 10% at 2 and 6 hours, respectively. For separated plasma, time to measurement influenced Aß levels by up to 7% after 6 hours and 10% after 24 hours. DISCUSSION: Our findings provide guidance for standardizing blood sample collection, handling, and storage to ensure reliable analysis of Alzheimer's disease plasma biomarkers in routine practice and clinical trials.

Blood-based systems biology biomarkers for next-generation clinical trials in Alzheimer's disease
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Alzheimer's disease (AD)-a complex disease showing multiple pathomechanistic alterations-is triggered by nonlinear dynamic interactions of genetic/epigenetic and environmental risk factors, which, ultimately, converge into a biologically heterogeneous disease. To tackle the burden of AD during early preclinical stages, accessible blood-based biomarkers are currently being developed. Specifically, next-generation clinical trials are expected to integrate positive and negative predictive blood-based biomarkers into study designs to evaluate, at the individual level, target druggability and potential drug resistance mechanisms. In this scenario, systems biology holds promise to accelerate validation and qualification for clinical trial contexts of use-including proof-of-mechanism, patient selection, assessment of treatment efficacy and safety rates, and prognostic evaluation. Albeit in their infancy, systems biology-based approaches are poised to identify relevant AD "signatures" through multifactorial and interindividual variability, allowing us to decipher disease pathophysiology and etiology. Hopefully, innovative biomarker-drug codevelopment strategies will be the road ahead towards effective disease-modifying drugs.
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La Enfermedad de Alzheimer (EA) es una enfermedad compleja que presenta múltiples alteraciones patomecánicas, que se desencadena por interacciones dinámicas no lineales de factores de riesgo genéticos / epigenéticos y ambientales, los que, en definitiva, convergen en una enfermedad biológicamente heterogénea. Para hacer frente a la carga de la EA durante las etapas preclínicas tempranas, actualmente se están desarrollando biomarcadores sanguíneos de fácil accesibilidad. Específicamente, se espera que los ensayos clínicos de próxima generación integren biomarcadores sanguíneos predictivos tanto positivos como negativos en los diseños de los estudios para evaluar, a nivel individual, la capacidad de la droga objetivo y los posibles mecanismos de resistencia a los medicamentos. En este contexto, la biología de sistemas promete acelerar la validación y la calificación de su empleo en los ensayos clínicos, incluida la prueba del mecanismo, la selección de pacientes, la evaluación de la eficacia del tratamiento y los porcentajes de seguridad, y la evaluación pronóstica. A pesar de estar en sus comienzos, los enfoques basados en la biología de sistemas están preparados para identificar "firmas" de EA relevantes a través de la variabilidad multifactorial e interindividual, lo que nos permite descifrar la fisiopatología y la etiología de la enfermedad. Ojalá, las estrategias innovadoras conjuntas del desarrollo de biomarcadores y de medicamentos sean el camino adecuado para conseguir fármacos eficaces que modifiquen la enfermedad.

La maladie d'Alzheimer (MA) ­ maladie complexe présentant des altérations nombreuses pathomécaniques ­ est déclenchée par des interactions dynamiques non linéaires entre des facteurs de risques génétiques et épigénétiques et environnementaux qui, au bout du compte, aboutissent à une maladie biologiquement hétérogène. Pour réduire la charge de morbidité de la MA durant ses premiers stades précliniques, des biomarqueurs sanguins sont actuellement développés. Spécifiquement, la prochaine génération d'essais cliniques devrait intégrer ces biomarqueurs sanguins positifs ou négatifs prédictifs de la maladie dans des études qui auront pour but d'évaluer, à un niveau individuel, des cibles pouvant être traitées par des candidats médicaments et de potentiels mécanismes de résistance à ces médicaments. Dans ce contexte, la biologie des systèmes devrait permettre d'accélérer la validation et la qualification de leur utilisation dans les études cliniques ­ incluant la preuve du mécanisme d'action, la sélection des patients, la confirmation de l'efficacité du traitement et son niveau de sécurité, ainsi que l'évaluation pronostique. Bien que nous en soyons au tout début, les approches reposant sur la biologie des systèmes sont sur le point d'identifier des « signatures ¼ pertinentes de la MA grâce à des variables multifactorielles et interindividuelles, qui nous permettront d'élucider la pathophysiologie et l'étiologie de la maladie. Avec un peu de chance, les stratégies innovantes de codéveloppement de biomarqueurs et de médicaments nous mèneront vers des médicaments efficaces pour lutter contre la maladie.

Blood-based biomarkers for Alzheimer disease: mapping the road to the clinic.

Biomarker discovery and development for clinical research, diagnostics and therapy monitoring in clinical trials have advanced rapidly in key areas of medicine - most notably, oncology and cardiovascular diseases - allowing rapid early detection and supporting the evolution of biomarker-guided, precision-medicine-based targeted therapies. In Alzheimer disease (AD), breakthroughs in biomarker identification and validation include cerebrospinal fluid and PET markers of amyloid-ß and tau proteins, which are highly accurate in detecting the presence of AD-associated pathophysiological and neuropathological changes. However, the high cost, insufficient accessibility and/or invasiveness of these assays limit their use as viable first-line tools for detecting patterns of pathophysiology. Therefore, a multistage, tiered approach is needed, prioritizing development of an initial screen to exclude from these tests the high numbers of people with cognitive deficits who do not demonstrate evidence of underlying AD pathophysiology. This Review summarizes the efforts of an international working group that aimed to survey the current landscape of blood-based AD biomarkers and outlines operational steps for an effective academic-industry co-development pathway from identification and assay development to validation for clinical use.

Ultra-deep sequencing reveals high prevalence and broad structural diversity of hepatitis B surface antigen mutations in a global population.

The diversity of the hepatitis B surface antigen (HBsAg) has a significant impact on the performance of diagnostic screening tests and the clinical outcome of hepatitis B infection. Neutralizing or diagnostic antibodies against the HBsAg are directed towards its highly conserved major hydrophilic region (MHR), in particular towards its "a" determinant subdomain. Here, we explored, on a global scale, the genetic diversity of the HBsAg MHR in a large, multi-ethnic cohort of randomly selected subjects with HBV infection from four continents. A total of 1553 HBsAg positive blood samples of subjects originating from 20 different countries across Africa, America, Asia and central Europe were characterized for amino acid variation in the MHR. Using highly sensitive ultra-deep sequencing, we found 72.8% of the successfully sequenced subjects (n = 1391) demonstrated amino acid sequence variation in the HBsAg MHR. This indicates that the global variation frequency in the HBsAg MHR is threefold higher than previously reported. The majority of the amino acid mutations were found in the HBV genotypes B (28.9%) and C (25.4%). Collectively, we identified 345 distinct amino acid mutations in the MHR. Among these, we report 62 previously unknown mutations, which extends the worldwide pool of currently known HBsAg MHR mutations by 22%. Importantly, topological analysis identified the "a" determinant upstream flanking region as the structurally most diverse subdomain of the HBsAg MHR. The highest prevalence of "a" determinant region mutations was observed in subjects from Asia, followed by the African, American and European cohorts, respectively. Finally, we found that more than half (59.3%) of all HBV subjects investigated carried multiple MHR mutations. Together, this worldwide ultra-deep sequencing based genotyping study reveals that the global prevalence and structural complexity of variation in the hepatitis B surface antigen have, to date, been significantly underappreciated.

CD40-expressing carcinoma cells induce down-regulation of CD40 ligand (CD154) and impair T-cell functions.

The interaction of CD40 expressed by immunocompetent cells with its ligand CD154 on the surface of T-helper cells plays a crucial role in the immune response. Recently, the presence of CD40 was also demonstrated on a variety of carcinomas. Whereas the critical relevance of CD40 in cytotoxic T-cell priming via dendritic cells is already established, the biological role of CD40/CD154 interactions in nonhematopoetic cells is still unclear. In the present study we demonstrate that CD154 expression density is down-regulated on activated T cells on interaction with CD40+ tumor cells. Naive T cells cocultured with CD40+carcinoma showed impaired functionality as indicated by a reduced frequency of IFN-gamma secreting cells, reduced interleukin 2 secretion, impaired proliferation, and a lack of CD154 re-expression on restimulation. In distinction, T-cell effector lysing capacity was not impaired by CD40-expressing tumor cell targets. The present results suggest that in marked contrast to antigen-presenting cells, CD40 expression on carcinoma cells suppresses T-cell activation. Our findings support the statement that CD40 functions are context dependent and imply a new function for CD40 expressed on nonantigen-presenting cells.

Personalized health care beyond oncology: new indications for immunoassay-based companion diagnostics.

Personalized health care (PHC) is an evolving field of medicine aimed at providing the right therapy to the right patient at the right time. This approach often incorporates the use of companion diagnostics (CDx) assays that provide information essential for the safe and effective use of the corresponding drug. In addition to oncology, many other therapy areas, such as cardiovascular, neurological, and infectious and inflammatory diseases, may benefit from PHC, owing to disease complexity and heterogeneity. Furthermore, although most U.S. Food and Drug Administration-approved CDx are based on molecular-based technologies, immunoassays can provide a significant contribution to the evolution of CDx in patient management. In this review we discuss how the incorporation of biomarker immunoassays into routine diagnostic testing may allow early and definitive detection of Alzheimer's disease and enable population enrichment in clinical trials. In addition, we will describe how biomarker-based CDx immunoassays have potential utility for stratifying patients with asthma based on their potential response to therapy and for selecting treatment according to phenotypic profile. Continued research into the underlying disease pathology and development of accurate and reliable diagnostic assays may ensure that PHC becomes the future standard for many indications.

The Clinical and Health Economic Value of Clinical Laboratory Diagnostics.

The ultimate goal of diagnostic testing is to guide disease management in order to improve patient outcomes and patient well-being. Patient populations are rarely homogenous and accurate diagnostic tests can dissect the patient population and identify those patients with similar symptoms but very different underlying pathophysiology that will respond differently to different treatments. This stratification of patients can direct patients to appropriate treatment and is likely to result in clinical benefits for patients and economic benefits for the healthcare system. In this article we look at the clinical and economic benefits afforded by clinical laboratory diagnostics in three disease areas that represent substantial clinical and healthcare burdens to society; heart failure, Alzheimer's disease and asthma.