Immunosignature Analysis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

A random-sequence peptide microarray can interrogate serum antibodies in a broad, unbiased fashion to generate disease-specific immunosignatures. This approach has been applied to cancer detection, diagnosis of infections, and interrogation of vaccine response. We hypothesized that there is an immunosignature specific to ME/CFS and that this could aid in the diagnosis. We studied two subject groups meeting the Canadian Consensus Definition of ME/CFS. ME/CFS (n = 25) and matched control (n = 25) sera were obtained from a Canadian study. ME/CFS (n = 25) sera were obtained from phase 1/2 Norwegian trials (NCT01156909). Sera from six healthy controls from the USA were included in the analysis. Canadian cases and controls were tested for a disease immunosignature. By combining results from unsupervised and supervised analyses, a candidate immunosignature with 654 peptides was able to differentiate ME/CFS from controls. The immunosignature was tested and further refined using the Norwegian and USA samples. This resulted in a 256-peptide immunosignature with the ability to separate ME/CFS cases from controls in the international data sets. We were able to identify a 256-peptide signature that separates ME/CFS samples from healthy controls, suggesting that the hit-and-run hypothesis of immune dysfunction merits further investigation. By extending testing of both our signature and one previously reported in the literature to larger cohorts, and further interrogating the specific peptides we and others have identified, we may deepen our understanding of the origins of ME/CFS and work towards a clinically meaningful diagnostic biomarker.

Immunosignature Differentiation of Non-Infectious Meningoencephalomyelitis and Intracranial Neoplasia in Dogs

A variety of inflammatory conditions of unknown cause (meningoencephalomyelitis of unknown etiology-MUE) and neoplastic diseases can affect the central nervous system (CNS) of dogs. MUE can mimic intracranial neoplasia both clinically, radiologically and even in some cases, histologically. Serum immunosignature protein microarray assays have been used in humans to identify CNS diseases such as Alzheimer's and neoplasia, and in dogs, to detect lymphoma and its progression. This study evaluated the effectiveness of immunosignature profiles for distinguishing between three cohorts of dogs: healthy, intracranial neoplasia, and MUE. Using the learned peptide patterns for these three cohorts, classification prediction was evaluated for the same groups using a 10-fold cross validation methodology. Accuracy for classification was 100%, as well as 100% specific and 100% sensitive. This pilot study demonstrates that immunosignature profiles may help serve as a minimally invasive tool to distinguish between MUE and intracranial neoplasia in dogs.

Entropy is a Simple Measure of the Antibody Profile and is an Indicator of Health Status: A Proof of Concept

We have previously shown that the diversity of antibodies in an individual can be displayed on chips on which 130,000 peptides chosen from random sequence space have been synthesized. This immunosignature technology is unbiased in displaying antibody diversity relative to natural sequence space, and has been shown to have diagnostic and prognostic potential for a wide variety of diseases and vaccines. Here we show that a global measure such as Shannon's entropy can be calculated for each immunosignature. The immune entropy was measured across a diverse set of 800 people and in 5 individuals over 3 months. The immune entropy is affected by some population characteristics and varies widely across individuals. We find that people with infections or breast cancer, generally have higher entropy values than non-diseased individuals. We propose that the immune entropy as measured from immunosignatures may be a simple method to monitor health in individuals and populations.

Interactions of periodontal pathogens with megakaryocytic cells and platelets

Introduction: Cardiovascular disease (CVD) is a leading cause of morbidity, accounting for around 17.3 million deaths worldwide. Recent studies have linked periodontitis to CVD with the periodonto-pathogens Porphyromonas gingivalis and Tannerella forsythia thought to contribute and exacerbate atherosclerosis through interactions with platelets. To date, while platelet activation following challenge with periodonto-pathogens has been reported, the underlying mechanisms of these interactions are yet to be elucidated. The aim of this study is to determine how periodonto-pathogens interact with platelets using both megakaryocytic cells and isolated platelets.

Methods: To characterise expression levels of surface markers including ubiquitously expressed platelet-specific markers (CD41, CD42b) and platelet activation markers (CD62P, PAC-1), a multi-colour flow cytometry panel was developed using undifferentiated megakaryocytic cells CHRF-288-11 before validation using platelets isolated from healthy donors. Changes in levels of surface markers following bacterial challenge both with megakaryocytic cells and isolated platelets were determined using flow cytometry. Interaction with pathogens was visualised by platelet aggregometry and fluorescence microscopy using pathogen-specific antibodies.

Results and conclusions: Both pathogens invaded megakaryocytic cells as visualised by immunofluorescence microscopy. The pathogens also bound platelets causing increased levels of aggregation and upregulated expression of activation markers including in CD62P in flow cytometric assays.

Humoral Immunity Profiling of Subjects with Myalgic Encephalomyelitis Using a Random Peptide Microarray Differentiates Cases from Controls with High Specificity and Sensitivity

Myalgic encephalomyelitis (ME) is a complex, heterogeneous illness of unknown etiology. The search for biomarkers that can delineate cases from controls is one of the most active areas of ME research; however, little progress has been made in achieving this goal. In contrast to identifying biomarkers that are directly involved in the pathological process, an immunosignature identifies antibodies raised to proteins expressed during, and potentially involved in, the pathological process. Although these proteins might be unknown, it is possible to detect antibodies that react to these proteins using random peptide arrays. In the present study, we probe a custom 125,000 random 12-mer peptide microarray with sera from 21 ME cases and 21 controls from the USA and Europe and used these data to develop a diagnostic signature. We further used these peptide sequences to potentially uncover the naturally occurring candidate antigens to which these antibodies may specifically react with in vivo. Our analysis revealed a subset of 25 peptides that distinguished cases and controls with high specificity and sensitivity. Additionally, Basic Local Alignment Search Tool (BLAST) searches suggest that these peptides primarily represent human self-antigens and endogenous retroviral sequences and, to a minor extent, viral and bacterial pathogens.

Spaceflight modulates gene expression in the whole blood of astronauts

Astronauts are exposed to a unique combination of stressors during spaceflight, which leads to alterations in their physiology and potentially increases their susceptibility to disease, including infectious diseases. To evaluate the potential impact of the spaceflight environment on the regulation of molecular pathways mediating cellular stress responses, we performed a first-of-its-kind pilot study to assess spaceflight-related gene-expression changes in the whole blood of astronauts. Using an array comprised of 234 well-characterized stress-response genes, we profiled transcriptomic changes in six astronauts (four men and two women) from blood preserved before and immediately following the spaceflight. Differentially regulated transcripts included those important for DNA repair, oxidative stress, and protein folding/degradation, including HSP90AB1, HSP27, GPX1, XRCC1, BAG-1, HHR23A, FAP48, and C-FOS. No gender-specific differences or relationship to number of missions flown was observed. This study provides a first assessment of transcriptomic changes occurring in the whole blood of astronauts in response to spaceflight.

General Assessment of Humoral Activity in Healthy Humans

The humoral immune system is network of biological molecules designed to maintain a healthy homeostatic equilibrium. Because antibodies are an abundant and highly specific effector of immunological action, they are also an important reservoir of previous host exposures. Antibodies may play a major role in early detection of host challenge. Unfortunately, few practical methods exist for interpreting the information stored in antibody variable regions. Immunosignatures use a microarray of thousands of random sequence peptides to interrogate antibodies in a broad and unbiased fashion. The pattern of binding between antibody and peptide is reproducible. Once the system has been trained on a disease cohort, blinded samples can be reliably predicted. Although immunosignatures of both chronic and infectious disease have been extensively tested, less has been done to demonstrate how healthy immunosignatures change over time or between individuals. Here, we report the results of a study of immunosignatures of healthy persons over brief (12 h sampled once per hour), intermediate (32 days sampled once per day), and long (5 years sampled once every year) time spans. Using this information, we were also able to detect intentional and unintentional immunological perturbations in the form of a vaccine and an infection, respectively. Our findings suggest that, even with the variability inherent in healthy immunosignatures, a single person's immunosignature will remain constant over time. Over this healthy signature, vaccines and infections create subsignatures that are common across multiple people, even subsuming healthy fluctuations. These findings have implications for disease monitoring and early diagnosis.

Abstract WP218: A Blood Test Capable of Discriminating Between Real Strokes and Mimics

Introduction: stroke diagnosis is not always easy. Many non-vascular medical and neurological problems can mimic stroke, featuring focal neurological signs and symptoms of sudden onset. These patients can potentially be harmed by stroke-specific treatments, including fibrinolysis. Hence, a test capable of unveiling stroke mimics would be useful.

Hypothesis: A proteomic platform called immunosignaturing may be useful to distinguish between acute ischemic stroke and imitators.

Methods: plasma samples from 12 patients brought to the ER because of a stroke code were analyzed: 6 were diagnosed with acute ischemic stroke and 6 with seizures mimicking a stroke. Additional 12 samples from healthy volunteers were used as controls. Immunosignatures use microarrays with 10,000 random sequence peptides, which behave as antibody mimotopes. Antibody binding to microarray peptides is detected with secondary antibodies labeled with fluorescent dyes, then scanned with a laser. Resulting profiles are unique to each individual. Samples were run in duplicates, with good correlation between replicates, high signal and low background. Mann-Whitney U-test and Fisher‘s exact test were used to compare groups.

Results: samples were obtained within 130 minutes after symptoms onset. We found no differences between groups related to age, gender, or cardiovascular risk factors. Analysis of signature profiles revealed striking separation between stroke and seizure cases. The Figure depicts a heatmap comparing the stroke (yellow bar underneath) and seizure patients. Peptides with QADAP or QADLP motifs helped differentiate the groups.

Conclusions: We describe the first application of an antibody-profiling platform called immunosignaturing to the study of ischemic stroke and its imitators. Despite the small sample, these very preliminary results suggest that antibody signatures may help distinguish acute ischemic strokes from other conditions, deserving future research.

Pyocystis and prostate abscess in a hemodialysis patient in the emergency department

The urinary tract is an often forgotten and under-appreciated source of infection in anuric hemodialysis patients. Bladder abscess, also called pyocystis, is a severe complication of low urinary flow that can be difficult to detect, leading to delays in treatment and increased morbidity. The emergency physician should maintain a high suspicion for pyocystis, which can be quickly diagnosed by bedside ultrasound. We report a case of a hemodialysis patient with an initially minor presentation who developed sepsis secondary to pyocystis and prostate abscess.

Abstract B35: Use of random peptide array to discover cancer neo-antigens for vaccines and diagnostics

This abstract is being presented as a short talk in the scientific program. A full abstract is printed in the Proffered Abstracts section (PR10) of the Conference Proceedings.

Citation Format: Phillip Stafford, Josh Richer, Stephen Albert Johnston, Luhui Shen. Use of random peptide array to discover cancer neo-antigens for vaccines and diagnostics. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B35.

Abstract PR10: Use of random peptide array to discover cancer neo-antigens for vaccines and diagnostics

The humoral response to tumors could reveal tumor antigens recognized by immunosurveillance. We have developed the immunosignatures diagnostic technology to detect this tumor specific response. The technology profiles reactivity of sera antibodies on the HT330K chip with 330K addressable random peptides. We have shown that subjects with specific cancers have specific immunosignatures that are distinguished from health people and other cancers. Here we demonstrate that the signatures can be deciphered to indicate specific neo-antigens for any cancer.

Neo-antigens caused by mistranscription in tumors can be the sources of tumor antigens. We have set up a database of predicted chimeric tumor antigens encoded by trans-splicing transcripts analyzed from EST databases. These transcripts encode the neo-epitopes by producing frame shift (FS) peptides from shifted reading frames of the downstream genes. We hypothesize that these predicted neo-antigens are frequently expressed in cancers and recognized by the immune system. We predict that these neo-antigens can be deciphered by their immunosignatures.

To test the hypothesis, we assayed the sera from glioblastoma patients (GBM, n=16) and normal controls (NC, n=16) on the HT330K chip. The 1,000 most significantly different peptides between GBM and NC were selected. Recurrent motifs in these peptides were across searched in the neo-antigen database. The seven most frequently matched antigens were selected for further study: 2 of them were encoded by the in-frame fusion transcripts and others were encoded by the FS fusion transcripts.

To validate the antibody reactivity of 7 deciphered neo-antigens, three overlapping peptides encompassing each of the antigens were synthesized and printed with unrelated peptides on the CIM10K array, which contains total 10,000 peptides. We analyzed NC (n=69) and GBM (n=19) with the CIM10K array. The positive cut off value of each peptide is the average plus two fold standard deviations of the NC. A positive sample was indicated as positive to at least one peptide of the antigen. The highest positive rates of 7 antigens is 11.6% in NC and 57.9% in GBM. 34.8% NC were positive to at least one antigen, 15.9% to more than one and only 4.3% positive to more than two antigens. No NC was positive to more than three antigens. This indicated the reactivity to these antigens is random in NC. The positive percentage in GBM were 89.5%, 73.7% and 47.4% respectively. 26.3% GBM was positive to more than three antigens. The implication is that cancer patients had much higher reactivity to these putative neo-antigens.

To test if other cancers elicited reactions to these neo-antigens, we analyzed breast cancer sera (BC, n=95) with the CIM10K. Similar to GBM, 83.15% BC were positive to at least one antigen and 34.7% were positive to more than 3 antigens. Five of seven antigens had positive reactivity in more than 25% of patients in both GBM and BC.

To further characterize these neo-antigens, we designed primers for RT-PCR analysis. We detected and sequence confirmed five fusion transcripts in GBM cDNAs. Two of the FS transcripts were also detected in multiple BC cDNAs and several normal tissues with lower level. Our interpretation is that the processing of the FS variants is primarily post-transcriptional in normal tissue but this processing is defective in tumors.

Here we showed that the neo-antigens from predicted fusion transcripts are the targets of the cancer humoral immune response. The specific antibody response was only in cancer patients indicating that the expression of these antigens in normal tissues was below the sensitivity of the immune system. Most importantly, this work indicates that we can efficiently decipher neo-antigens from the immunosignatures of cancer subjects. This may be a new source of antigens for diagnosis and cancer vaccines.

This abstract is also presented as Poster B35.

Citation Format: Phillip Stafford, Josh Richer, Stephen Albert Johnston, Luhui Shen. Use of random peptide array to discover cancer neo-antigens for vaccines and diagnostics. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr PR10.

Time-Frequency Analysis of Peptide Microarray Data: Application to Brain Cancer Immunosignatures

One of the gravest dangers facing cancer patients is an extended symptom-free lull between tumor initiation and the first diagnosis. Detection of tumors is critical for effective intervention. Using the body’s immune system to detect and amplify tumor-specific signals may enable detection of cancer using an inexpensive immunoassay. Immunosignatures are one such assay: they provide a map of antibody interactions with random-sequence peptides. They enable detection of disease-specific patterns using classic train/test methods. However, to date, very little effort has gone into extracting information from the sequence of peptides that interact with disease-specific antibodies. Because it is difficult to represent all possible antigen peptides in a microarray format, we chose to synthesize only 330,000 peptides on a single immunosignature microarray. The 330,000 random-sequence peptides on the microarray represent 83% of all tetramers and 27% of all pentamers, creating an unbiased but substantial gap in the coverage of total sequence space. We therefore chose to examine many relatively short motifs from these random-sequence peptides. Time-variant analysis of recurrent subsequences provided a means to dissect amino acid sequences from the peptides while simultaneously retaining the antibody–peptide binding intensities. We first used a simple experiment in which monoclonal antibodies with known linear epitopes were exposed to these random-sequence peptides, and their binding intensities were used to create our algorithm. We then demonstrated the performance of the proposed algorithm by examining immunosignatures from patients with Glioblastoma multiformae (GBM), an aggressive form of brain cancer. Eight different frameshift targets were identified from the random-sequence peptides using this technique. If immune-reactive antigens can be identified using a relatively simple immune assay, it might enable a diagnostic test with sufficient sensitivity to detect tumors in a clinically useful way.

Epitope identification from fixed-complexity random-sequence peptide microarrays

Antibodies play an important role in modern science and medicine. They are essential in many biological assays and have emerged as an important class of therapeutics. Unfortunately, current methods for mapping antibody epitopes require costly synthesis or enrichment steps, and no low-cost universal platform exists. In order to address this, we tested a random-sequence peptide microarray consisting of over 330,000 unique peptide sequences sampling 83% of all possible tetramers and 27% of pentamers. It is a single, unbiased platform that can be used in many different types of tests, it does not rely on informatic selection of peptides for a particular proteome, and it does not require iterative rounds of selection. In order to optimize the platform, we developed an algorithm that considers the significance of k-length peptide subsequences (k-mers) within selected peptides that come from the microarray. We tested eight monoclonal antibodies and seven infectious disease cohorts. The method correctly identified five of the eight monoclonal epitopes and identified both reported and unreported epitope candidates in the infectious disease cohorts. This algorithm could greatly enhance the utility of random-sequence peptide microarrays by enabling rapid epitope mapping and antigen identification.

Scalable high-density peptide arrays for comprehensive health monitoring

There is an increasing awareness that health care must move from post-symptomatic treatment to presymptomatic intervention. An ideal system would allow regular inexpensive monitoring of health status using circulating antibodies to report on health fluctuations. Recently, we demonstrated that peptide microarrays can do this through antibody signatures (immunosignatures). Unfortunately, printed microarrays are not scalable. Here we demonstrate a platform based on fabricating microarrays (~10 M peptides per slide, 330,000 peptides per assay) on silicon wafers using equipment common to semiconductor manufacturing. The potential of these microarrays for comprehensive health monitoring is verified through the simultaneous detection and classification of six different infectious diseases and six different cancers. Besides diagnostics, these high-density peptide chips have numerous other applications both in health care and elsewhere.

The roles of HOXD10 in the development and progression of head and neck squamous cell carcinoma (HNSCC)

Background:

HOX gene expression is altered in many cancers; previous microarray revealed changes in HOX gene expression in head and neck squamous cell carcinoma (HNSCC), particularly HOXD10.

Methods:

HOXD10 expression was assessed by qPCR and immunoblotting in vitro and by immunohistochemistry (IHC) in tissues. Low-expressing cells were stably transfected with HOXD10 and the phenotype assessed with MTS, migration and adhesion assays and compared with the effects of siRNA knockdown in high-HOXD10-expressing cells. Novel HOXD10 targets were identified using expression microarrays, confirmed by reporter assay, and validated in tissues using IHC.

Results:

HOXD10 expression was low in NOKs, high in most primary tumour cells, and low in lymph node metastasis cells, a pattern confirmed using IHC in tissues. Overexpression of HOXD10 decreased cell invasion but increased proliferation, adhesion and migration, with knockdown causing reciprocal effects. There was no consistent effect on apoptosis. Microarray analysis identified several putative HOXD10-responsive genes, including angiomotin (AMOT-p80) and miR-146a. These were confirmed as HOXD10 targets by reporter assay. Manipulation of AMOT-p80 expression resulted in phenotypic changes similar to those on manipulation of HOXD10 expression.

Conclusions:

HOXD10 expression varies by stage of disease and produces differential effects: high expression giving cancer cells a proliferative and migratory advantage, and low expression may support invasion/metastasis, in part, by modulating AMOT-p80 levels.

Diagnosis and early detection of CNS-SLE in MRL/lpr mice using peptide microarrays

Background

An accurate method that can diagnose and predict lupus and its neuropsychiatric manifestations is essential since currently there are no reliable methods. Autoantibodies to a varied panel of antigens in the body are characteristic of lupus. In this study we investigated whether serum autoantibody binding patterns on random-sequence peptide microarrays (immunosignaturing) can be used for diagnosing and predicting the onset of lupus and its central nervous system (CNS) manifestations. We also tested the techniques for identifying potentially pathogenic autoantibodies in CNS-Lupus. We used the well-characterized MRL/lpr lupus animal model in two studies as a first step to develop and evaluate future studies in humans.

Results

In study one we identified possible diagnostic peptides for both lupus and altered behavior in the forced swim test. When comparing the results of study one to that of study two (carried out in a similar manner), we further identified potential peptides that may be diagnostic and predictive of both lupus and altered behavior in the forced swim test. We also characterized five potentially pathogenic brain-reactive autoantibodies, as well as suggested possible brain targets.

Conclusions

These results indicate that immunosignaturing could predict and diagnose lupus and its CNS manifestations. It can also be used to characterize pathogenic autoantibodies, which may help to better understand the underlying mechanisms of CNS-Lupus.

Gingipain-dependent degradation of mammalian target of rapamycin pathway proteins by the periodontal pathogen Porphyromonas gingivalis during invasion

Porphyromonas gingivalis and Tannerella forsythia are gram-negative pathogens strongly associated with periodontitis. Their abilities to interact, invade and persist within host cells are considered crucial to their pathogenicity, but the mechanisms by which they subvert host defences are not well understood. In this study, we set out to investigate whether P. gingivalis and T. forsythia directly target key signalling molecules that may modulate the host cell phenotype to favour invasion and persistence. Our data identify, for the first time, that P. gingivalis, but not T. forsythia, reduces levels of intracellular mammalian target of rapamycin (mTOR) in oral epithelial cells following invasion over a 4-h time course, via the action of gingipains. The ability of cytochalasin D to abrogate P. gingivalis-mediated mTOR degradation suggests that this effect is dependent upon cellular invasion. We also show that levels of several other proteins in the mTOR signalling pathway are modulated by gingipains, either directly or as a consequence of mTOR degradation including p-4E-BP1. Taken together, our data suggest that P. gingivalis manipulates the mTOR pathway, providing evidence for a potentially novel mechanism by which P. gingivalis mediates its effects on host cell responses to infection.

Abstract 4441: The ketogenic diet potentiates radiation therapy in a mouse model of glioma: effects on inflammatory pathways and reactive oxygen species

Patients with malignant brain tumors have a median survival of approximately one year following diagnosis, regardless of currently available treatments which include surgery, radiation and chemotherapy. Although there have been advances in the development of novel treatments, targeted therapies face the challenge of overcoming phenotypic variability resulting from tumor heterogeneity. One phenotypic trait shared by virtually all cancer cells is dysregulation of metabolism. It has therefore been postulated that one approach to treating brain tumors may be through metabolic alteration such as that which occurs through the use of the ketogenic diet (KD). The KD is high-fat, low-carbohydrate diet that has been utilized for the non-pharmacologic treatment of refractory epilepsy. We and others have shown that this diet enhances survival in mouse models of malignant gliomas. Further, radiation in combination with KD was synergistic, and survival was significantly increased over radiation treatment alone. To gain an understanding of the mechanism(s) by which the KD exerts anti-tumor effects and enhances the efficacy of radiation therapy we performed gene expression profiling analyses on tumor tissue and non-tumor containing brain using the Affymetrix GeneChip® Mouse Genome 430 2.0 array. To identify changes in gene expression representing chronic effects of KD and radiation plus KD we harvested tissue when the animals became symptomatic. We previously reported that tissue from animals maintained on the KD in the absence of radiation treatment showed a reduction in reactive oxygen species (ROS) and cyclooxygenase-2 (COX-2) expression compared to those maintained on a standard diet (Stafford et al, Nutr and Metab (7):74, 2010). We now report that peritumoral edema is significantly reduced early in tumor progression in animals fed the KD when compared to those fed a standard rodent diet. Furthermore, gene expression profiling of animals treated with radiation and KD demonstrated alterations in the chronic expression of crucial genes involved in radiation-induced inflammation including COX-2 and the nuclear transcription factor NF-кB, both of which are implicated in radioresistance. We are repeating these studies using tissues harvested shortly after radiation therapy to identify genes acutely affected by radiation therapy in animals fed a KD. Taken together, our data to date suggests that the KD may be interfering with the radiation-induced inflammatory signaling network implicated in tumor progression. A greater understanding of the effects of the ketogenic diet as an adjuvant therapy will allow for a more rational approach to its clinical use.

Citation Format: Eric C. Woolf, Phillip Stafford, Mohammed G. Abdelwahab, Kathryn Fenton, Mark C. Preul, Adrienne C. Scheck. The ketogenic diet potentiates radiation therapy in a mouse model of glioma: effects on inflammatory pathways and reactive oxygen species. [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 4441. doi:10.1158/1538-7445.AM2013-4441

Feasibility of an early Alzheimer's disease immunosignature diagnostic test

A practical diagnostic test is needed for early Alzheimer's disease (AD) detection. Immunosignaturing, a technology that employs antibody binding to a random-sequence peptide microarray, generates profiles that distinguish transgenic mice engineered with familial AD mutations (APPswe/PSEN1-dE9) from non-transgenic littermates. It can also detect an AD-like signature in humans. Here, we assess the changes in the immunosignature at different time points of the disease in mice and humans. We also evaluate the accuracy of the late-stage signature as a test to discriminate between young mice with familial AD mutations from non-transgenic littermates. Plasma samples from AD patients were assayed 3-12 months apart, while APPswe/PSEN1-dE9 and non-transgenic controls supplied plasma at monthly intervals until they reached 15 months of age. Microarrays with 10,000 random-sequence peptides were used to compare antibody binding patterns. These patterns gradually changed over the life-span of mice. Strong, characteristic signatures were observed in transgenic mice at early, mid and late stages, but these profiles had minimal overlap. The signature of young transgenic mice had an error rate of 18% at classifying plasma samples from late-stage transgenic mice. Conversely, the late-stage transgenic mice signature discriminated between young transgenic mice and littermates with an error rate of 21%. Less distinctive profiles were recognizable throughout the transgenic mice lifespan, being detectable as early as 2 months. The human signature had minimal change on short-term follow-up. Our results call for a reappraisal of the way incipient AD is studied, as biomarkers seen in late-stages of the disease may not be relevant in earlier stages.

Immunosignaturing can detect products from molecular markers in brain cancer

Immunosignaturing shows promise as a general approach to diagnosis. It has been shown to detect immunological signs of infection early during the course of disease and to distinguish Alzheimer’s disease from healthy controls. Here we test whether immunosignatures correspond to clinical classifications of disease using samples from people with brain tumors. Blood samples from patients undergoing craniotomies for therapeutically naïve brain tumors with diagnoses of astrocytoma (23 samples), Glioblastoma multiforme (22 samples), mixed oligodendroglioma/astrocytoma (16 samples), oligodendroglioma (18 samples), and 34 otherwise healthy controls were tested by immunosignature. Because samples were taken prior to adjuvant therapy, they are unlikely to be perturbed by non-cancer related affects. The immunosignaturing platform distinguished not only brain cancer from controls, but also pathologically important features about the tumor including type, grade, and the presence or absence of O⁶-methyl-guanine-DNA methyltransferase methylation promoter (MGMT), an important biomarker that predicts response to temozolomide in Glioblastoma multiformae patients.