The relationship between serum astroglial and neuronal markers and AQP4 and MOG autoantibodies

BACKGROUND

Certain demyelinating disorders, such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) exhibit serum autoantibodies against aquaporin-4 (αAQP4) and myelin oligodendrocyte glycoprotein (αMOG). The variability of the autoantibody presentation warrants further research into subtyping each case.

METHODS

To elucidate the relationship between astroglial and neuronal protein concentrations in the peripheral circulation with occurrence of these autoantibodies, 86 serum samples were analyzed using immunoassays. The protein concentration of glial fibrillary acidic protein (GFAP), neurofilament light chain (NFL) and tau protein was measured in 3 groups of subcategories of suspected NMOSD: αAQP4 positive (n = 20), αMOG positive (n = 32) and αMOG/αAQP4 seronegative (n = 34). Kruskal-Wallis analysis, univariate predictor analysis, and multivariate logistic regression with ROC curves were performed.

RESULTS

GFAP and NFL concentrations were significantly elevated in the αAQP4 positive group (p = 0.003; p = 0.042, respectively), and tau was elevated in the αMOG/αAQP4 seronegative group (p < 0.001). A logistic regression model to classify serostatus was able to separate αAQP4 seropositivity using GFAP + tau, and αMOG seropositivity using tau. The areas under the ROC curves (AUCs) were 0.77 and 0.72, respectively. Finally, a combined seropositivity versus negative status logistic regression model was generated, with AUC = 0.80.

CONCLUSION

The 3 markers can univariately and multivariately classify with moderate accuracy the samples with seropositivity and seronegativity for αAQP4 and αMOG.

Clinical evaluation of a novel plasma pTau217 electrochemiluminescence immunoassay in Alzheimer's disease

A growing literature suggests that plasma levels of tau phosphorylated at amino acid 217 (pTau217) performs similarly to cerebrospinal fluid (CSF) biomarkers and PET imaging to detect amyloid pathology and to provide diagnostic and prognostic information in Alzheimer's disease (AD), but a significant limiting factor thus far has been a lack of widely available immunoassays. We evaluated a novel pTau217 S-PLEX® assay developed by Meso Scale Discovery (MSD; Rockville, MD) in plasma from 131 individuals with AD confirmed by CSF biomarkers and controls. Technical performance of the assay was excellent with an LLOQ of 1.84 pg/mL and intra/interplate CVs of 5.5% (0.3-15.0%) and 5.7% (range 0.3-13.4%), respectively. The pTau217 plasma assay differentiated AD and controls with an AUC of 0.98 (95% CI 0.96-1.0) and pTau217 levels were 3.9-fold higher in individuals with AD. This performance was significantly better than what was observed for plasma pTau181, performed in parallel, and comparable to published data on existing pTau217 assays. While further clinical validation and head-to-head comparisons are needed to fully establish the role for the novel pTau217 S-PLEX assay, these data demonstrate the utility of the assay to detect AD pathology.

The relationship between serum astroglial and neuronal markers and AQP4 and MOG autoantibodies

Background

Certain demyelinating disorders, such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) exhibit serum autoantibodies against aquaporin-4 (αAQP4) and myelin oligodendrocyte glycoprotein (αMOG). The variability of the autoantibody presentation warrants further research into subtyping each case.

Methods

To elucidate the relationship between astroglial and neuronal protein concentrations in the peripheral circulation with occurrence of these autoantibodies, 86 serum samples were analyzed using immunoassays. The protein concentration of glial fibrillary acidic protein (GFAP), neurofilament light chain (NFL) and tau protein was measured in 3 groups of subcategories of suspected NMOSD: αAQP4 positive (n = 20), αMOG positive (n = 32) and αMOG/αAQP4 seronegative (n = 34). Kruskal-Wallis analysis, univariate predictor analysis, and multivariate logistic regression with ROC curves were performed.

Results

GFAP and NFL concentrations were significantly elevated in the αAQP4 positive group (p = 0.003; p = 0.042, respectively), and tau was elevated in the αMOG/αAQP4 seronegative group (p < 0.001). A logistic regression model to classify serostatus was able to separate αAQP4 seropositivity using GFAP + tau, and αMOG seropositivity using tau. The areas under the ROC curves (AUCs) were 0.77 and 0.72, respectively. Finally, a combined seropositivity versus negative status logistic regression model was generated, with AUC = 0.80.

Conclusion

The 3 markers can univariately and multivariately classify with moderate accuracy the samples with seropositivity and seronegativity for αAQP4 and αMOG.

Quantitative serology for SARS-CoV-2 using self-collected saliva and finger-stick blood

Convenient and widespread serology testing may alter the trajectory of the COVID-19 pandemic. This study seeks to leverage high-throughput, multiplexed serologic assays, which have been adopted as benchmarks for vaccine efficacy, to support large-scale surveys of SARS-CoV-2 immunity using finger-stick blood and/or saliva. Specifically, we optimized MSD’s serology assays, which were analytically validated for serum, to test self-collected finger-stick blood and saliva samples to identify prior infection. We show that these assays can be used with FDA-registered specimen collection devices to obtain quantitative measurements for self-collected samples. First, we show that salivary antibodies are stable without refrigeration or preservatives for at least 5 days. We selected classification thresholds for antibodies against SARS-CoV-2 N, RBD and Spike in finger-stick blood and saliva that provided 98% specificity in a set of individuals without known COVID-19 exposure. Using matched samples, we show that testing of saliva and finger-stick blood equivalently identified individuals with humoral responses to CoV-2 antigens. Moreover, we piloted a simple saliva collection kit that can be used to safely send samples through the mail using written instructions only. This work establishes key parameters to robustly assay self-collected finger-stick blood and saliva using quantitative immunoassays that could support large-scale serology testing.

Abstract 3346: Development of a multiplex screening panel for Akt signaling pathway biomarkers in cell and tissue lysate models

Major challenges face the large-scale implementation of intracellular tumor biomarkers for clinical diagnosis and therapeutic development. These challenges include non-quantitative results, insufficient assay sensitivity, and lack of multiplexing capability. For many studies, sample volumes are limited (e.g., tumor lysates); however, it is essential to extract as much biomarker information as possible from a given sample while maintaining the quality and consistency necessary to sustain ongoing studies. To address these challenges, MSD® has developed multiplex panels for assaying cell signaling biomarkers using fit-for-purpose methods that emphasize optimal multiplex combinations and rigorous development of critical reagents. Here we report the development and verification of a multiplex screening panel of immunoassays for simultaneous measurement of total and phosphorylated analytes of the Akt signalling pathway using MSD technology. Markers in the panel include phosphorylated and total forms of GSK3B, p70S6K, FOXO3a, PTEN, Akt, S6RP, PRAS40, and ERK1. We demonstrate the ability of these assays to measure analyte levels in multiple tumor-derived cell lines and human tissue samples (normal and tumor) with excellent sensitivity and performance. Most analytes can be quantified using no more than 10 µg of sample. By using recombinant proteins to calibrate some of the assays, we were able to quantify analytes in cultured cell lysates, including MCF-7 and Jurkat T-cells. Lack of analyte specificity is a well-known issue when multiplexing intracellular signaling analytes, especially those in a common signaling pathway such as the Akt pathway. Through rigorous optimization, we achieved non-specific binding less than or equal to 1% for all analytes in this panel. Spike recovery and dilution linearity were characterized to demonstrate matrix tolerance in tumor cell line and tissue lysates as well as dynamic ranges between 3 and 4 logs, allowing quantification of analytes at different abundance levels without using multiple dilutions. In conclusion, MSD MULTI-SPOT® Akt signaling assay panels have been developed and verified for measurement of intracellular tumor biomarkers of relevance to clinical diagnosis, therapeutic development, and treatment of various cancers. The accuracy, reliability, ease of use, and high-throughput features of these multiplex assays make them ideally suited for use in large-scale clinical studies.

Citation Format: Thomas W. Miller, Karen Tressler, Jill Dunty, Paula Eason, Leonid Dzantiev, Sripriya Ranganathan, Laura Schaefer, David Stewart, Pankaj Oberoi, Jacob Wohlstadter. Development of a multiplex screening panel for Akt signaling pathway biomarkers in cell and tissue lysate models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3346. doi:10.1158/1538-7445.AM2014-3346

Abstract 4731: Discovering cancer biomarkers using a novel cytokine screening panel

Cytokines and chemokines that are produced in the tumor micro-environment play major roles in tumorigenesis, tumor progression, and apoptosis. They are involved in the modulation of angiogenesis and consequently, in tumor growth and metastases. Cytokine/chemokine expression by tumor cells leads to tumor proliferation and enhances tumor cell survival. Profiling these biomarkers may be useful for cancer diagnosis. For example, biomarkers such as IFNγ, TNFα, IL-1β, MCP-1, and IL-8 are overexpressed in breast carcinoma; IL-2, IL-4, IL-6, IL-8, IL-10, IL-16, and TARC are associated with prostate cancer; and increased expression levels of TNFα, IL-6, and IL-1β are implicated in colon cancer.

We have developed and validated multiplexed panels of 30 assays that allow users to simultaneously detect cytokines and chemokines with high precision and accuracy in different human matrices. These panels detect IFNγ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, TNFα, IL-5, IL-7, GM-CSF, IL-1α, IL-17A, IL-15, IL-16, IL-12/IL-23 p40, TNFβ, and VEGF MIP-1α, MIP-1β, Eotaxin, Eotaxin-3, IP-10, TARC, IL-8 (high abundance), MDC, MCP-1, and MCP-4.

The MSD® platform has the ability to quantitate these biomarkers in multiple sample types with superior sensitivity and performance, quantifying many low abundance analytes at levels below 0.5 pg/mL.

A challenge with current multiplex assays is a lack of analytical validation and lot-to-lot reproducibility. These new multiplex panels were developed with highly characterized and qualified reagents, and the assays were developed in accordance with industry guidelines. The panels demonstrated suitable spike recovery and dilution linearity performance in different biological matrices. Diluents, other kit components, and an optimized assay protocol are provided to achieve optimum performance. Each assay in the panel is well characterized and shows low non-specific binding. Each has been evaluated for potential assay and analytical interference. Controls are available for each panel.

These panels are suitable tools for accurately quantitating cytokines and chemokines in various tumor samples. Data are presented for samples from normal subjects as well as samples from benign prostatic hyperplasia and prostate cancer patients (serum), cirrhosis and liver cancer patients (serum), kidney cancer patients (plasma), and colon cancer patients (serum).

Citation Format: Joseph Manimala, Prachi Gupte, Ashok Swaminathan, Jorge P. Tituana, Caitlin Hansen, Anu Mathew, David Stewart, Pankaj Oberoi, Jacob Wohlstadter. Discovering cancer biomarkers using a novel cytokine screening panel. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4731. doi:10.1158/1538-7445.AM2013-4731