An efficient proteomics-based approach for the screening of autoantibodies

Autoantibodies as biomarkers for breast cancer diagnosis and prognosis

Breast cancer is the most common cancer in women worldwide and is a substantial public health problem. Screening for breast cancer mainly relies on mammography, which leads to false positives and missed diagnoses and is especially non-sensitive for patients with small tumors and dense breasts. The prognosis of breast cancer is mainly classified by tumor, node, and metastasis (TNM) staging, but this method does not consider the molecular characteristics of the tumor. As the product of the immune response to tumor-associated antigens, autoantibodies can be detected in peripheral blood and can be used as noninvasive, presymptomatic, and low-cost biomarkers. Therefore, autoantibodies can provide a possible supplementary method for breast cancer screening and prognosis classification. This article introduces the methods used to detect peripheral blood autoantibodies and the research progress in the screening and prognosis of breast cancer made in recent years to provide a potential direction for the examination and treatment of breast cancer.

Analysis of the Repertoires of Circulating Autoantibodies' Specificities as a Tool for Identification of the Tumor-Associated Antigens: Current Problems and Solutions

Circulating autoantibodies against tumor-associated autoantigens (TAA) may serve as valuable biomarkers for a wide range of diagnostic purposes. Modern immunology offers a large variety of methods for in-depth comparative analysis of the repertoires of circulating antibodies' antigenic specificities in health and disease. Nevertheless, this research field so far has met somewhat limited clinical success, while numerous data on the repertoires of circulating autoantibodies' specificities in cancer patients are poorly integrated into the contemporary picture of the immunological and molecular landscapes of human tumors. This review is an attempt to identify and systematize the key and essentially universal conceptual and methodological limitations of analyses of the repertoires of circulating antibodies' antigenic specificities in cancer (expression bias, redundancy of TAA repertoires, identification of natural IgG, the absence of the pathogenetically relevant context in the experimental systems used to detect TAA), as well as to discuss potential and already known methodological improvements that may significantly increase the detectability of the pathogenetically relevant and diagnostically significant bona fide TAA.

Tumor-Associated Antigens (TAAs) for the Serological Diagnosis of Osteosarcoma

Osteosarcoma (OS) is the most common form of malignant bone tumor found in childhood and adolescence. Although its incidence rate is low among cancers, the prognosis of OS is usually poor. Although some biomarkers, such as p53, have been identified in OS, the association between the biomarkers and clinical outcome is not well understood. Thus, it is necessary to establish a method to identify patients diagnosed with OS at an early stage. It is becoming obvious that anti-tumor-associated antigens (TAAs) autoantibodies (TAAbs) in sera could be used as serological biomarkers in the detection of many different types of cancers. This notion indicates that TAAbs are considered as immunological “sentinels” associated with tumorigenesis underlying molecular events. It provides new insights into the molecular and cellular biology of the differential diagnosis of cancers. What’s more, it is reported that a customized TAA array could significantly increase the sensitivity/specificity. TAA arrays also have great application prospects in detecting cancer at an early stage, monitoring cancer progression, discovering new therapeutic targets, and designing personalized treatment. In this review, we provide an overview of the TAAs identified in OS as well as the possibility that TAAs and TAAbs system be used as biomarkers in the immunodiagnosis and prognosis of OS.

Optimizing cancer immunotherapy: Is it time for personalized predictive biomarkers?

Cancer immunotherapy, a treatment that selectively augments a patient's anti-tumor immune response, is a breakthrough advancement in personalized medicine. A subset of cancer patients undergoing immunotherapy have displayed robust and long-lasting therapeutic responses. Currently, the spotlight is on the use of blocking antibodies against the T-cell checkpoint molecules, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programed cell death-1 (PD-1)/programed death-ligand 1 (PD-L1), which have been effectively used to combat many cancers types. Despite the overall enthusiasm, immune checkpoint blockade inhibitors suffer from significant limitations such as high cost, serious toxicity in a substantial proportion of patients, and a response rate as low as 10%-40% in some clinical trials. Consequently, there is an urgent and unmet medical need for companion biomarkers that could both predict the response of individual patients to these therapies, and provide the means for precise monitoring of their therapeutic outcome. In this era of precision medicine, predictive biomarkers are a hot commodity because they can effectively separate responders from non-responders, and spare non-responders from serious therapy-related toxicity. Emerging predictive biomarkers for immune checkpoint blockade are: PD-L1 expression, increased amounts of tumor-infiltrating lymphocytes, increased mutational load and mismatch repair deficiency. Other well-studied biomarkers include inflammatory infiltrate, absolute lymphocyte count and lactate dehydrogenase levels. We review recent progress on predictive cancer biomarkers in immunotherapy, with a special emphasis on serum autoantibodies that have the potential to be personalized for optimal clinical outcomes.

Autoantibodies as Potential Biomarkers in Breast Cancer

Breast cancer is a major cause of mortality in women; however, technologies for early stage screening and diagnosis (e.g., mammography and other imaging technologies) are not optimal for the accurate detection of cancer. This creates demand for a more effective diagnostic means to replace or be complementary to existing technologies for early discovery of breast cancer. Cancer neoantigens could reflect tumorigenesis, but they are hardly detectable at the early stage. Autoantibodies, however, are biologically amplified and hence may be measurable early on, making them promising biomarkers to discriminate breast cancer from healthy tissue accurately. In this review, we summarized the recent findings of breast cancer specific antigens and autoantibodies, which may be useful in early detection, disease stratification, and monitoring of treatment responses of breast cancer.

Hypochlorite converts cysteinyl-dopamine into a cytotoxic product: A possible factor in Parkinson's Disease

The dopamine oxidation product cysteinyl-dopamine has attracted attention as a contributor to the death of dopaminergic neurons in Parkinson's disease. Treatment of cysteinyl-dopamine with hypochlorite yields an even more cytotoxic product. This product has potent redox-cycling activity and initiates production of superoxide in PC12 cells. Taurine, which scavenges hypochlorite, protects PC12 cells from cysteinyl-dopamine but not from the hypochlorite product, suggesting that the product, not cysteinyl-dopamine itself, is toxic. Furthermore, rotenone, which enhances expression of the hypochlorite-producing enzyme myeloperoxidase, increases the cytotoxicity of cysteinyl-dopamine but not of the hypochlorite product. This suggests that dopamine oxidation to cysteinyl-dopamine followed by hypochlorite-dependent conversion to a cytotoxic redox-cycling product leads to the generation of reactive oxygen species and oxidative stress and may contribute to the death of dopaminergic neurons.

Plasma IgG autoantibody against actin-related protein 3 in liver fluke Opisthorchis viverrini infection

Opisthorchiasis secondary to Opisthorchis viverrini infection leads to cholangiocellular carcinoma through chronic inflammation of the bile ducts and possibly inducing autoimmunity. It was hypothesized that plasma autoantibodies directed against self-proteins are biomarkers for opisthorchiasis. Plasma from patients with opisthorchiasis was tested using proteins derived from immortalized cholangiocyte cell lines, and spots reacting with plasma were excised and subjected to LC-MS/MS. Seven protein spots were recognized by IgG autoantibodies, and the highest matching scored protein was actin-related protein 3 (ARP3). The antibody against ARP3 was tested in plasma from 55 O. viverrini-infected patients, 24 patients with others endemic parasitic infections and 17 healthy controls using Western blot and ELISA. Immunoreactivity against recombinant ARP3 was significantly more prevalent in opisthorchiasis compared to healthy controls at Western blotting and ELISA (P < 0.05). Plasma ARP3 autoantibody titres were also higher in opisthorchiasis compared to healthy individuals (P < 0.01) and other parasitic infections including Strongyloides stercoralis (P < 0.001), echinostome (P < 0.05), hookworms (P < 0.001) and Taenia spp. (P < 0.05). It was further characterized in that the ARP3 autoantibody titre had a sensitivity of 78.18% and specificity of 100% for opisthorchiasis. In conclusion, it may be suggested that plasma anti-ARP3 might represent a new diagnostic antibody for opisthorchiasis.

An Optimized Fluorescence-Based Bidimensional Immunoproteomic Approach for Accurate Screening of Autoantibodies

Serological proteome analysis (SERPA) combines classical proteomic technology with effective separation of cellular protein extracts on two-dimensional gel electrophoresis, western blotting, and identification of the antigenic spot of interest by mass spectrometry. A critical point is related to the antigenic target characterization by mass spectrometry, which depends on the accuracy of the matching of antigenic reactivities on the protein spots during the 2D immunoproteomic procedures. The superimposition, based essentially on visual criteria of antigenic and protein spots, remains the major limitation of SERPA. The introduction of fluorescent dyes in proteomic strategies, commonly known as 2D-DIGE (differential in-gel electrophoresis), has boosted the qualitative capabilities of 2D electrophoresis. Based on this 2D-DIGE strategy, we have improved the conventional SERPA by developing a new and entirely fluorescence-based bi-dimensional immunoproteomic (FBIP) analysis, performed with three fluorescent dyes. To optimize the alignment of the different antigenic maps, we introduced a landmark map composed of a combination of specific antibodies. This methodological development allows simultaneous revelation of the antigenic, landmark and proteomic maps on each immunoblot. A computer-assisted process using commercially available software automatically leads to the superimposition of the different maps, ensuring accurate localization of antigenic spots of interest.

Simultaneous immunoblotting analysis with activity gel electrophoresis and 2-D gel electrophoresis

Diffusion blotting method can couple immunoblotting analysis with another biochemical technique in a single polyacrylamide gel, however, with lower transfer efficiency as compared to the conventional electroblotting method. Thus, with diffusion blotting, protein blots can be obtained from an SDS polyacrylamide gel for zymography assay, from a native polyacrylamide gel for electrophoretic mobility shift assay (EMSA) or from a 2-D polyacrylamide gel for large-scale screening and identification of a protein marker. Thereafter, a particular signal in zymography, electrophoretic mobility shift assay, and 2-dimensional gel can be confirmed or identified by simultaneous immunoblotting analysis with a corresponding antiserum. These advantages make diffusion blotting desirable when partial loss of transfer efficiency can be tolerated or be compensated by a more sensitive immunodetection reaction using enhanced chemiluminescence detection.

Acquisition of useful sero-diagnostic autoantibodies using the same patients'sera and tumor tissues

Cancer tissues are comprised of various components including tumor cells and the surrounding tumor stroma, which consists of the extracellular matrix and inflammatory cells. Since the tumor stroma plays critical roles in tumor development, investigation of the tumor stroma in addition to tumor cells is important to identify useful tumor-associated markers. To discover novel and useful sero-diagnostic markers, a comparative study of tumor-associated autoantibodies (AAbs) in sera from lung adenocarcinoma (AC) patients was investigated by two-dimensional immunoblotting with AC cell lines or each autologous AC tissues. Autoantigens identified from tissue and cell line samples comprised 58 (45 antigens) and 53 spots (41 antigens), respectively. Thirty-six proteins including Transforming growth factor-beta-induced protein ig-h3 (BIGH3) and Hyaluronan and proteoglycan link protein 1 (HAPLN1) were detected only from tissues, 32 proteins only from cell lines, and 9 proteins from both. BIGH3 and HAPLN1 expressions were confirmed in the tumor stroma, but not in AC cell lines by immunostaining and immunoblotting. These data suggest that autologous tumor tissue and serum are important to coincidently detect AAbs derived from the tumor stroma in addition to tumor cells.

The necessity of and strategies for improving confidence in the accuracy of western blots

Western blotting is one of the most commonly used laboratory techniques for identifying proteins and semi-quantifying protein amounts; however, several recent findings suggest that western blots may not be as reliable as previously assumed. This is not surprising since many labs are unaware of the limitations of western blotting. In this manuscript, we review essential strategies for improving confidence in the accuracy of western blots. These strategies include selecting the best normalization standard, proper sample preparation, determining the linear range for antibodies and protein stains relevant to the sample of interest, confirming the quality of the primary antibody, preventing signal saturation and accurately quantifying the signal intensity of the target protein. Although western blotting is a powerful and indispensable scientific technique that can be used to accurately quantify relative protein levels, it is necessary that proper experimental techniques and strategies are employed.

Using immunomic approach to enhance tumor-associated autoantibody detection in diagnosis of hepatocellular carcinoma

To explore the possibility of using a mini-array of multiple tumor-associated antigens (TAAs) as an approach to the diagnosis of hepatocellular carcinoma (HCC), 14 TAAs were selected to examine autoantibodies in sera from patients with chronic hepatitis, liver cirrhosis and HCC by immunoassays. Antibody frequency to any individual TAA in HCC varied from 6.6% to 21.1%. With the successive addition of TAAs to the panel of TAAs, there was a stepwise increase of positive antibody reactions. The sensitivity and specificity of 14 TAAs for immunodiagnosis of HCC was 69.7% and 83.0%, respectively. This TAA mini-array also identified 43.8% of HCC patients who had normal alpha-fetoprotein (AFP) levels in serum. In summary, this study further supports the hypothesis that a customized TAA array used for detecting anti-TAA autoantibodies can constitute a promising and powerful tool for immunodiagnosis of HCC and may be especially useful in patients with normal AFP levels.

Serologic autoantibodies as diagnostic cancer biomarkers--a review

Current diagnostic techniques used for the early detection of cancers are successful but subject to detection bias. A recent focus lies in the development of more accurate diagnostic tools. An increase in serologic autoantibody levels has been shown to precede the development of cancer disease symptoms. Therefore, autoantibody levels in patient blood serum have been proposed as diagnostic biomarkers for early-stage diagnosis of cancers. Their clinical application has, however, been hindered by low sensitivity, specificity, and low predictive value scores. These scores have been shown to improve when panels of multiple diagnostic autoantibody biomarkers are used. A five-marker biomarker panel has been shown to increase the sensitivity of prostate cancer diagnosis to 95% as compared with 12.2% for prostate-specific antigen alone. New potential biomarker panels were also discovered for lung, colon, and stomach cancer diagnosis with sensitivity of 76%, 65.4%, and 50.8%, respectively. Studies in breast and liver cancer, however, seem to favor single markers, namely α-2-HS-glycoprotein and des-γ-carboxyprothrombin with sensitivities of 79% and 89% for the early detection of the cancers. The aim of this review is to discuss the relevance of autoantibodies in cancer diagnosis and to outline the current methodologies used in the detection of autoantibodies. The review concludes with a discussion of the autoantibodies currently used in the diagnosis of cancers of the prostate, breast, lung, colon, stomach, and liver. A discussion of the potential future use of autoantibodies as diagnostic cancer biomarkers is also included in this review.

Autoantibody biomarkers identified by proteomics methods distinguish ovarian cancer from non-ovarian cancer with various CA-125 levels

PURPOSE

CA-125 has been a valuable marker for detecting ovarian cancer, however, it is not sensitive enough to detect early-stage disease and not specific to ovarian cancer. The purpose of our study was to identify autoantibody markers that are specific to ovarian cancer regardless of CA-125 levels.

METHODS

Top-down and iTRAQ quantitative proteomics methods were used to identify high-frequency autoantibodies in ovarian cancer. Protein microarrays comprising the recombinant autoantigens were screened using serum samples from various stages of ovarian cancer with diverse levels of CA-125 as well as benign and healthy controls. ROC curve and dot blot analyses were performed to validate the sensitivity and specificity of the autoantibody markers.

RESULTS

The proteomics methodologies identified more than 60 potential high-frequency autoantibodies in ovarian cancer. Individual serum samples from ovarian cancer stages I-IV compared to control samples that were screened on a microarray containing native recombinant autoantigens revealed a panel of stage I high-frequency autoantibodies. Preliminary ROC curve and dot blot analyses performed with the ovarian cancer samples showed higher specificity and sensitivity as compared to CA-125. Three autoantibody markers exhibited higher specificity in various stages of ovarian cancer with low and normal CA-125 levels.

CONCLUSIONS

Proteomics technologies are suitable for the identification of protein biomarkers and also the identification of autoantibody biomarkers when combined with protein microarray screening. Using native recombinant autoantigen arrays to screen autoantibody markers, it is possible to identify markers with higher sensitivity and specificity than CA-125 that are relevant to early detection of ovarian cancer.

Early lung cancer diagnosis by biosensors

Lung cancer causes an extreme threat to human health, and the mortality rate due to lung cancer has not decreased during the last decade. Prognosis or early diagnosis could help reduce the mortality rate. If microRNA and tumor-associated antigens (TAAs), as well as the corresponding autoantibodies, can be detected prior to clinical diagnosis, such high sensitivity of biosensors makes the early diagnosis and prognosis of cancer realizable. This review provides an overview of tumor-associated biomarker identifying methods and the biosensor technology available today. Laboratorial researches utilizing biosensors for early lung cancer diagnosis will be highlighted.

Tumor-associated autoantibodies as diagnostic and prognostic biomarkers

In the process of tumorigenesis, normal cells are remodeled to cancer cells and protein expression patterns are changed to those of tumor cells. A newly formed tumor microenvironment elicits the immune system and, as a result, a humoral immune response takes place. Although the tumor antigens are undetectable in sera at the early stage of tumorigenesis, the nature of an antibody amplification response to antigens makes tumor-associated autoantibodies as promising early biomarkers in cancer diagnosis. Moreover, the recent development of proteomic techniques that make neo-epitopes of tumor-associated autoantigens discovered concomitantly has opened a new area of ‘immuno-proteomics’, which presents tumor-associated autoantibody signatures and confers information to redefine the process of tumorigenesis. In this article, the strategies recently used to identify and validate serum autoantibodies are outlined and tumor-associated antigens suggested until now as diagnostic/prognostic biomarkers in various tumor types are reviewed. Also, the meaning of autoantibody signatures and their clinical utility in personalized medicine are discussed. [BMB Reports 2012; 45(12): 677-685]

Application of a high throughput method of biomarker discovery to improvement of the EarlyCDT(®)-Lung Test

BACKGROUND

The National Lung Screening Trial showed that CT screening for lung cancer led to a 20% reduction in mortality. However, CT screening has a number of disadvantages including low specificity. A validated autoantibody assay is available commercially (EarlyCDT®-Lung) to aid in the early detection of lung cancer and risk stratification in patients with pulmonary nodules detected by CT. Recent advances in high throughput (HTP) cloning and expression methods have been developed into a discovery pipeline to identify biomarkers that detect autoantibodies. The aim of this study was to demonstrate the successful clinical application of this strategy to add to the EarlyCDT-Lung panel in order to improve its sensitivity and specificity (and hence positive predictive value, (PPV)).

METHODS AND FINDINGS

Serum from two matched independent cohorts of lung cancer patients were used (n = 100 and n = 165). Sixty nine proteins were initially screened on an abridged HTP version of the autoantibody ELISA using protein prepared on small scale by a HTP expression and purification screen. Promising leads were produced in shake flask culture and tested on the full assay. These results were analyzed in combination with those from the EarlyCDT-Lung panel in order to provide a set of re-optimized cut-offs. Five proteins that still displayed cancer/normal differentiation were tested for reproducibility and validation on a second batch of protein and a separate patient cohort. Addition of these proteins resulted in an improvement in the sensitivity and specificity of the test from 38% and 86% to 49% and 93% respectively (PPV improvement from 1 in 16 to 1 in 7).

CONCLUSION

This is a practical example of the value of investing resources to develop a HTP technology. Such technology may lead to improvement in the clinical utility of the EarlyCDT--Lung test, and so further aid the early detection of lung cancer.

Immunohistochemical analysis of medullary breast carcinoma autoantigens in different histological types of breast carcinomas

BACKGROUND

On the past decade a plethora of investigations were directed on identification of molecules involved in breast tumorogenesis, which could represent a powerful tool for monitoring, diagnostics and treatment of this disease. In current study we analyzed six previously identified medullary breast carcinoma autoantigens including LGALS3BP, RAD50, FAM50A, RBPJ, PABPC4, LRRFIP1 with cancer restricted serological profile in different histological types of breast cancer.

METHODS

Semi-quantitative immunohistochemical analysis of 20 tissue samples including medullary breast carcinoma, invasive ductal carcinoma, invasive lobular carcinoma and non-cancerous tissues obtained from patients with fibrocystic disease (each of five) was performed using specifically generated polyclonal antibodies. Differences in expression patterns were evaluated considering percent of positively stained cells, insensitivity of staining and subcellular localization in cells of all tissue samples.

RESULTS

All 6 antigens predominantly expressed in the most cells of all histological types of breast tumors and non-cancerous tissues with slight differences in intensity of staining and subcellular localization. The most significant differences in expression pattern were revealed for RAD50 and LGALS3BP in different histological types of breast cancer and for PABPC4 and FAM50A antigens in immune cells infiltrating breast tumors.

CONCLUSIONS

This pilot study made possible to select 4 antigens LGALS3BP, RAD50, PABPC4, and FAM50A as promising candidates for more comprehensive research as potential molecular markers for breast cancer diagnostics and therapy.

VIRTUAL SLIDES

The virtual slides' for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1860649350796892.

Identification of novel autoantigens by a triangulation approach

High titer autoantibodies, which are often associated with specific clinical phenotypes, are useful diagnostically and prognostically in systemic autoimmune diseases. In several autoimmune rheumatic diseases (e.g. myositis and Sjogren's syndrome), 20-40% of patients are autoantibody negative as assessed by conventional assays. The recent discovery of new specificities (e.g., anti-MDA5) in a subset of these autoantibody-negative subjects demonstrates that additional specificities await identification. In this manuscript, we describe a rapid multidimensional method to identify new autoantigens. A central foundation of this rapid approach is the use of an antigen source in which a pathogenic pathway active in the disease is recapitulated. Additionally, the method involves a modified serological proteome analysis strategy which allows confirmation that the correct gel plug has been removed prior to sending for sequencing. Lastly, the approach uses multiple sources of information to enable rapid triangulation and identification of protein candidates. Possible permutations and underlying principles of this triangulation strategy are elaborated to demonstrate the broad utility of this approach for antigen discovery.

Galectin-3 secretion and tyrosine phosphorylation is dependent on the calpain small subunit, Calpain 4

Cell adhesion and migration are important events that occur during embryonic development, immune surveillance, wound healing and in tumor metastasis. It is a multi-step process that involves both mechanical and biochemical signaling that results in cell protrusion, adhesion, contraction and retraction. Each of these events generates mechanical forces into the environment measured as traction forces. We have previously found that the calpain small subunit, Calpain 4, is required for normal traction forces, and that this mechanism is independent of the catalytic activities of the holoenzymes that are formed between Calpain 4 and each of the proteolytic heavy chains of Calpain 1 and 2. To define a potential mechanism for the Calpain 4 regulation of traction force, we have evaluated the levels of tyrosine phosphorylation, a hallmark of force dependent signaling within focal adhesions. Using 2D gel electrophoresis we compared tyrosine phosphorylation profiles of Calpain 4 deficient mouse embryonic fibroblasts (MEFs) to the levels in wildtype MEFs and MEF's deficient in the large catalytic subunits, Capn1 and Capn2. Of particular interest, was the identification of Galectin-3, a galactose binding protein known to interact with integrins. Galectin-3 has previously been shown to regulate cell adhesion and migration in both normal and tumor cells; however its full mechanism remains elusive. We have found that Calpain 4 is essential for the tyrosine phosphorylation of galectin-3, and its ultimate secretion from the cell, and speculate that its secretion interferes with the production of traction forces.

An antibody-based biomarker discovery method by mass spectrometry sequencing of complementarity determining regions

Autoantibodies are increasingly used as biomarkers in the detection of autoimmune disorders and cancer. Disease specific antibodies are generally detected by their binding to specific antigens. As an alternative approach, we propose to identify specific complementarity determining regions (CDR) of IgG that relate to an autoimmune disorder or cancer instead of the specific antigen(s). In this manuscript, we tested the technical feasibility to detect and identify CDRs of specific antibodies by mass spectrometry. We used a commercial pooled IgG preparation as well as purified serum IgG fractions that were spiked with different amounts of a fully human monoclonal antibody (adalimumab). These samples were enzymatically digested and analyzed by nanoLC Orbitrap mass spectrometry. In these samples, we were able to identify peptides derived from the CDRs of adalimumab. These peptides could be detected at an amount of 110 attomole, 5 orders of magnitude lower than the total IgG concentration in these samples. Using higher energy collision induced dissociation (HCD) fragmentation and subsequent de novo sequencing, we could successfully identify 50% of the detectable CDR peptides of adalimumab. In addition, we demonstrated that an affinity purification with anti-dinitrophenol (DNP) monoclonal antibody enhanced anti-DNP derived CDR detection in a serum IgG background. In conclusion, specific CDR peptides could be detected and sequenced at relatively low levels (attomole-femtomole range) which should allow the detection of clinically relevant CDR peptides in patient samples.

The identification of auto-antibodies in pancreatic cancer patient sera using a naturally fractionated Panc-1 cell line

The immunogenic nature of cancer can be explored to distinguish pancreatic cancer from related non-cancer conditions. We describe a liquid-based microarray approach followed by statistical analysis and confirmation for discovery of auto-immune biomarkers for pancreatic cancer. Proteins from the Panc-1 pancreatic cancer cell line were fractionated using a 2-D liquid separation method into over 1052 fractions and spotted onto nitrocellulose coated glass slides. The slides were hybridized with 37 pancreatic cancer sera, 24 chronic pancreatitis sera and 23 normal sera to detect elevated levels of reactivity against the proteins in spotted fractions. The response data obtained from protein microarrays was first analyzed by Wilcoxon Rank-Sum Tests to generate two lists of fractions that positively responded to the cancer sera and showed p-values less than 0.02 in the pairwise comparison between cancer specimens and normal and chronic pancreatitis specimens. The top 3 fractions with the lowest correlations were combined in receiver operating characteristic analyses. The area-under-the-curve (AUC) values are 0.813 and 0.792 for cancer vs. normal and cancer vs. pancreatitis respectively. Outlier-Sum statistics were then applied to the microarray data to determine the existence of outliers exclusive in cancer sera. The selected fractions were identified by LC-MS/MS. We further confirmed the occurrence of outliers with three proteins among cancer samples in a confirmation experiment using a separate dataset of 165 serum samples containing 48 cancer sera and 117 non-cancer controls. Phosphoglycerate kinase 1 (PGK1) elicited greater reactivity in 20.9% (10 in 48) of the samples in the cancer group, while no outlier was present in the non-cancer groups.

Identification of a new panel of serum autoantibodies associated with the presence of in situ carcinoma of the breast in younger women

PURPOSE

We examined the feasibility of using a panel of autoantibodies to multiple tumor-associated proteins as a method for early detection of breast cancer and, more particularly, carcinoma in situ (CIS).

EXPERIMENTAL DESIGN

PPIA, PRDX2, and FKBP52 were identified as early-stage breast cancer autoantigens by proteomic approaches. The seroreactivity of a panel of antibodies consisting of these three antigens and two previously described autoantigens, HSP60 and MUC1, was tested on 235 samples (60 from primary breast cancer patients, 82 from CIS patients, and 93 from healthy controls) with the use of specific ELISAs. FKBP52, PPIA, and PRDX2 mRNA and protein expression levels were evaluated by reverse transcription-PCR and immunohistochemistry in early-stage breast tumors.

RESULTS

Three of five autoantibodies, FKBP52, PPIA, and PRDX2, showed significantly increased reactivity in primary breast cancer and CIS compared with healthy controls. When combined, the five markers significantly discriminated primary breast cancer [receiver operating characteristic area under the curve, 0.73; 95% confidence interval (95% CI), 0.60-0.79] and CIS (receiver operating characteristic area under the curve, 0.80; 95% CI, 0.71-0.85) from healthy individuals. Importantly, the receiver operating characteristic-area under the curve value of the autoantibody panel was able to distinguish CIS, including high grades, from healthy controls in women under the age of 50 years (receiver operating characteristic area under the curve, 0.85; 95% CI, 0.61-0.92). Finally, only FKBP52 mRNA and protein levels were found to be increased in CIS and primary breast cancer compared with healthy breast tissue.

CONCLUSIONS

This autoantibody assay against a panel of five antigens allows for an accurate discrimination between early-stage breast cancer, especially CIS, and healthy individuals. These results could be of interest in detecting early breast cancer as an aid to mammography, especially in women under the age of 50 years with aggressive cancers.

Autoantibody to tumor antigen, alpha 2-HS glycoprotein: a novel biomarker of breast cancer screening and diagnosis

We sought to identify a new serum biomarker for breast cancer screening and diagnosis using stepwise proteomic analysis of sera from breast cancer patients to detect the presence of autoantibodies that react with urinary protein. Two-dimensional immunoblotting was done for screening autoimmunogenic tumor antigens in the urine of breast cancer patients. Reactive spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Among urinary proteins separated by two-dimensional electrophoresis, 13 spots showed strong reactivity with pooled sera from breast cancer patients or control sera. By mass spectrometry, we identified alpha 2-HS glycoprotein (AHSG) as a tumor antigen. Peripheral blood was obtained from 81 women diagnosed with breast cancer before surgery and 73 female donors without evidence of any malignancy for the individual analysis. In one-dimensional Western blot analysis, AHSG autoantibody was detected in 64 of 81 breast cancer patients (79.1%) and in 7 of 73 controls (9.6%). The sensitivity of this test in breast cancer patients was 79.0%. Our results suggest that AHSG and anti-AHSG autoantibody may be useful serum biomarkers for breast cancer screening and diagnosis.

Simultaneous immunoblotting analysis with activity gel electrophoresis and 2-D gel electrophoresis

Diffusion blotting method can couple immunoblotting analysis with another biochemical technique in a single polyacrylamide gel, however, with lower transfer efficiency as compared with the conventional electroblotting method. Thus, with diffusion blotting, a protein blot can be obtained from a sodium dodecyl sulfate polyacrylamide gel for zymography assay, from a native polyacrylamide gel for electrophoretic mobility shift assay (EMSA), or from a two-dimensional (2-D) polyacrylamide gel for large-scale screening and identification of a protein marker. Therefore, a particular signal in zymography, EMSA, and 2-D gel can be confirmed or identified by simultaneous immunoblotting analysis with a corresponding antiserum. These advantages make diffusion blotting desirable when partial loss of transfer efficiency can be tolerated or can be compensated by a more sensitive immunodetection reaction using enhanced chemiluminescence substrates.

Molecular characterisation and expression analysis of SEREX-defined antigen NUCB2 in gastric epithelium, gastritis and gastric cancer

NUCB2 is an EF-hand Ca²⁺ binding protein that has been implicated in various physiological processes like calcium homeostasis, hypothalamic regulation of feeding and TNF receptor shedding. In our previous study we identified NUCB2 as a potential tumour antigen eliciting autoantibody responses in 5.4% of gastric cancer patients but not in the healthy individuals. The current study aimed to elucidate the molecular mechanism underlying NUCB2 immunogenicity and to gain an insight into the physiological functions of NUCB2 in the stomach. mRNA expression analysis demonstrated that NUCB2 is ubiquitously expressed in normal tissues, including lymphoid tissues, and downregulated in gastric tumours when compared with the adjacent relatively normal stomach tissues. The search for molecular alterations resulted in the identification of novel mRNA variants transcribed from an alternative promoter and expressed predominantly in gastric cancers. Western blot analysis demonstrated that the protein levels correspond to mRNA levels and revealed that NUCB2 is phosphorylated in gastric mucosa. Furthermore, a 55 kDa isoform, generated presumably by yet an unidentified post-translational modification was detected in gastric tumours and AGS gastric cancer cells but was absent in the relatively normal gastric mucosa and thereby might have served as a trigger for the immune response against NUCB2. Staining of stomach tissue microarray with anti-NUCB2 antibody revealed that it is expressed in the secretory granules of chief cells and in the cytoplasm of parietal cells in the functioning gastric glands which are lost in atrophic glands and tumour cells. Hence we propose that NUCB2 may be implicated in gastric secretion by establishing an agonist-releasable Ca²⁺ store in ER or Golgi apparatus, signalling via heterotrimeric G_α proteins and/or mediating the exocytosis of the secretory granules.

Phosphoglycerate kinase 1 as a candidate of tumor-associated antigen identified from esophageal squamous cell carcinoma

AIM: To investigate and identify novel tumor-associated antigens in esophageal squamous cell carcinoma (ESCC).

METHODS: Modified serological proteome analysis (mSERPA) strategy was used to separate and identify the candidate proteins. The subcellular protein fractions (cytosolic, membrane and nuclear fractions) of ESCC cell lines and EC0156 cells were extracted first and then cytosolic proteins were separated using SDS-PAGE. The separated proteins were incubated with different serum of ESCC patients (29 cases) or healthy controls (28 cases) respectively, and then one of the positive bands in 43 kDa was excised followed by in-gel tryptic digestion. Separated peptides were identified using a high definition mass spectrometry (HDMS). Western blot and immunohistochemical staining (IHC) were used to validate possible candidates.

RESULTS: Successful compartmental protein extraction was demonstrated by specific organelle markers. Serum samples of ESCC patients bound EC0156 cytoplasmic protein, suggesting selective recognition of tumor-associated antigen. 43 kDa protein band showed significantly higher positive binding rate with serum of ESCC patients (41.4%, 12/29) than with serum of healthy individuals (3.6%, 1/28). Five high-confidence proteins were identified from the 43 kDa band using HDMS including phosphoglycerate kinase 1 (PGK1), β-actin, proteasome 26S subunit, S-adenosylhomocysteine hydrolase and hosphoribosylaminoimidazole carboxylase. Immunohistochemistry. Western blot analysis showed that PGK1 was located in both cytoplasm and nucleus, and had a higher expression in cancer tissues (69.23%, 18/26) than in normal esophageal epithelia.

CONCLUSION: The mSERPA strategy is useful for tumor-associated antigen identification. As a new candidate of tumor-associated antigen, PGK1 was over-expressed in ESCC which may play a role in tumorigenesis of ESCC.

Autoantibodies to tumor-associated antigens: reporters from the immune system

Although autoantibodies have been recognized as participants in pathogenesis of tissue injury, the collateral role of autoantibodies as reporters from the immune system identifying cellular participants in tumorigenesis has not been fully appreciated. The immune system appears to be capable of sensing aberrant structure, distribution, and function of certain cellular components involved in tumorigenesis and making autoantibody responses to the tumor-associated antigens (TAAs). Autoantibodies to TAAs can report malignant transformation before standard clinical studies and may be useful as early detection biomarkers. The autoantibody response also provides insights into factors related to how cellular components may be rendered immunogenic. As diagnostic biomarkers, specific TAA miniarrays for identifying autoantibody profiles could have sufficient sensitivity in differentiating between types of tumors. Such anti-TAA profiles could also be used to monitor response to therapy. The immune system of cancer patients reveals the immune interactive sites or the autoepitopes of participants in tumorigenesis, and this information should be used in the design of immunotherapy.

Identification of tumor antigens that elicit a humoral immune response in breast cancer patients' sera by serological proteome analysis (SERPA)

BACKGROUND

In this study we applied a serological proteomics-based approach (SERPA) to identify tumor antigens that commonly induce a humoral immune response in patients with infiltrating ductal breast carcinomas.

METHODS

Sera obtained at the time of diagnosis from 40 patients with invasive breast cancer and 42 healthy controls were screened individually for the presence of IgG antibodies to MCF-7 cell line proteins. Immunoreactive proteins were isolated and subsequently identified by MALDI-TOF mass spectrometry.

RESULTS

We identified 26 proteins that reacted with antibodies in the sera from breast cancer patients. Among these antigens, a significantly higher frequency occurs against the molecular chaperone HSP60, the tumor suppressor prohibitin, beta-tubulin, the haptoglobin-related protein and peroxiredoxin-2. Immunoreactivity to hnRNPK, Mn-SOD and F1-ATPase was also clearly detected in the patients group, whereas scarcely in control sera. By contrast, two other antigens identified as cytokeratins 8 and 18, as well as, F1-actin were found to elicit humoral immune responses in both control and breast cancer patients' sera.

CONCLUSIONS

The immunoproteomic approach implemented here offers a powerful tool for determining novel tumor antigens that elicit a humoral immune response in patients with invasive breast cancer. These antigens and/or their related circulating antibodies may display clinical usefulness as potential diagnostic markers and provide a means for a better understanding of the molecular mechanisms underlying breast cancer development.

Proteomics-based identification of autoantibody against heat shock protein 70 as a diagnostic marker in esophageal squamous cell carcinoma

Detection of novel tumor-related antigens and autoantibodies in cancer patients is expected to facilitate the diagnosis of early-stage malignant tumor and establish effective new immunotherapies. The purpose of this study was to identify novel tumor antigens in an esophageal squamous cell carcinoma (ESCC) cell line (TE-2) and related autoantibodies in sera from patients with ESCC using a proteomics-based approach. TE-2 proteins were separated by two-dimensional polyacrylamide gel electrophoresis, followed by Western blot analysis in which sera from patients with ESCC, healthy controls and patients with other cancers were tested for primary antibodies. Positive spots were excised from silver-stained gels and analyzed by matrix-assisted laser disorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). Sera from patients with ESCC yielded multiple spots, one of which was identified as heat shock protein 70 (Hsp70) by MALDI-TOF/TOF-MS. Concentrations of serum Hsp70 autoantibody were significantly higher for patients with ESCC (mean, 0.412+/-0.096 mg/ml) than for patients with gastric (0.236+/-0.112 mg/ml, P<0.001) or colon cancer (0.231+/-0.120 mg/ml, P<0.001) or healthy individuals (0.207+/-0.055 mg/ml, P<0.001) by enzyme-linked immunosorbent assay. We have identified an autoantibody against Hsp70 in ESCC patients. The proteomic approach implemented herein offers a powerful tool for identifying novel serum markers that may display clinical utility against cancer.

Identification of plasma membrane autoantigens in autoimmune hepatitis type 1 using a proteomics tool

Autoimmune hepatitis (AIH) is a liver disease with circulating autoantibodies predominantly directed against widely held cellular components. Because AIH is a liver-specific disease, autoantibodies against plasma membrane antigens may be involved in its pathogenesis and have been reported; however, no definite identification has been described. We thus investigated the fine specificity of anti-hepatocyte plasma membrane autoantibodies in type 1 AIH (AIH-1) using a proteomic tool. A plasma membrane-enriched fraction was validated using enzymatic activity and western blot analysis experiments. Sera from AIH-1 patients (n = 65) and from 90 controls, that is, healthy blood donors (n = 40) and patients with systemic diseases (n = 20) or other liver diseases (n = 30), were studied by immunoblot performed with plasma membrane proteins resolved by either sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) or 2-dimensional (2D) electrophoresis. Proteins contained in the immunoreactive spots were identified by sequences provided by ion-trap mass spectrometry. Hepatocytes probed with sera were also studied using confocal immunofluorescence and immunoelectron microscopy. The more prominent bands stained by patient sera were located at 38 kDa, 48, 50, 52 kDa, 62 kDa, 70 kDa, and a 95-kDa double band. Six proteins with known potential plasma membrane expression were identified: liver arginase (38 kDa), cytokeratins (CK) 8 and 18 (48-52 kDa), heat shock proteins (HSP) of 60, 70, 90 kDa, and valosin-containing protein (VCP) of 92 kDa. The presence of anti-membrane antibodies was confirmed by immunofluorescence and immunoelectron microscopy.

CONCLUSION

Overall, our data demonstrate that liver arginase, CK 8/18, HSP 60, HSP 70, HSP 90, and VCP represent potential candidate targets on liver membrane for autoantibodies in AIH-1.

Using proteomics to identify targets of antiendothelial cell antibodies

Antiendothelial cell antibodies represent a heterogeneous group of antibodies directed against a variety of antigen determinants of endothelial cells. Antibodies reacting with endothelial structures have been detected in sera from patients with autoimmune vasculitis, both primary and secondary to systemic connective tissue diseases. It may interfere with several functions and, therefore, may be a pathophysiological relevance. The analysis of the antigens recognized by antiendothelial cell antibodies showed that the antibodies are directed against a heterogeneous family of both constitutive and nonconstitutive surface endothelial proteins. Proteomics is a field of science that evaluates a large number of proteins expressed from a given cell line or organism. The technology of proteomics has been used as a method for discovering the target protein specific to a particular disease by searching for the expression or modification of the protein. Recently, progress has been made in defining the target antigens of these antibodies and proteomic technologies is one of them. This review will focus on the proteomic technologies in searching autoantigens/autoantibodies associated with disease of the endothelium.

Pattern of serum immunoreactivity against breast cancer cell lysates may predict severity of disease in breast cancer patients

Humoral tumor-specific immunity has been investigated as a potential tool to identify tumor-associated antigens and evaluate cancer diagnosis and prognosis. Using SDS-PAGE and western blotting techniques we investigated the humoral immune response against tumor cell antigens in 36 breast cancer patients, 17 node-positive (NP) and 19 node-negative (NN). As a source of antigens, we prepared protein lysates from four breast cancer cell lines (AU565, BT474, MCF-7 and MDA-MB-231) which in vitro exhibit different features of invasion, estrogen receptor/progesterone receptor status and HER2/neu expression thereby potentially representing mild to aggressive forms of clinical disease. A higher number of immunocomplexes Ag-Ab were formed when serum from NN patients was immunoreacted against lysates from AU565 and MCF-7 in comparison to serum from NP patients (P < 0.01). BT474 cells were not a good antigenic source. MDA-MB-231 cells could not significantly discriminate between NN and NP patients since both groups showed higher amounts of reactivity against the lysate. However, comparative analysis of protein preparations purified from MCF-7 and MDA-MB-231 cells and immunodetected concomitantly with the same serum samples showed that serum from patients with cancers with worse prognosis (stage, nodality, HER2/neu and hormonal status) reacted more intensely to proteins purified from the relatively more invasive cell line MDA-MB-231 compared to MCF-7. These findings suggest that the study of serum antibody reactivity to antigens purified from breast cancer cell lines with different invasive properties should be further investigated for its potential in providing beneficial prognostic information in breast cancer.

Cancer immunomics: from serological proteome analysis to multiple affinity protein profiling

Cancer remains one of the leading causes of death worldwide. Thus, to identify any useful biomarkers is still a need. We performed "cancer immunomics" to identify autoantibody signatures produced in response to the presence of either breast or colorectal cancer. SERological proteome analysis (SERPA) was performed by two-dimensional (2-D) electrophoresis separation, immunoblotting, image analysis, and mass spectrometry. Alternatively, to identify the antigens recognized by the autoantibodies of cancer patients, we developed an approach combining 2-D immunoaffinity chromatography, enzymatic digestion of the isolated antigens, nano flow separation of the resulting peptides, and identification: MAPPing (multiple affinity protein profiling). By these approaches we identified both proteins recognized by autoantibodies independently of a cancer status, and a limited number of proteins reacting preferentially with cancer sera.

Simultaneous analysis of multiple serum proteins adhering to the surface of medical grade polydimethylsiloxane elastomers

Although polydimethylsiloxane (PDMS, silicone) elastomers are presumed to be chemically inert and of negligible toxicity, they induce a prompt acute inflammatory response with subsequent fibrotic reactions. Since local inflammatory and fibrotic side effects are associated with the proteinaceous film on the surface of silicone implants, the process of protein adherence to silicone is of practical medical relevance, and interesting from theoretical, clinical and biotechnological perspectives. It is hypothesized that the systemic side effects resembling rheumatoid and other connective tissue diseases may be triggered by local immunological changes, but this functional relationship has yet to be defined. Because the proteinaceous film on the surface of silicone has been identified as a key player in the activation of host defense mechanisms, we propose a test system based on a proteomics screen to simultaneously identify proteins adsorbed from serum to the surface of silicone. Herein, we describe protein adsorption kinetics on the surface of silicone implants, correlate the adhesion properties of serum proteins with the occurrence of adverse reactions to silicone, and successfully discriminate their signature on the silicone surface in a blinded study of patients suffering from fibrotic reactions (as determined by Baker scale) to silicone implants.

Protein sequence information by matrix-assisted laser desorption/ionization in-source decay mass spectrometry

Proteins from biological samples are often identified by mass spectrometry (MS) with the two following "bottom-up" approaches: peptide mass fingerprinting or peptide sequence tag. Nevertheless, these strategies are time-consuming (digestion, liquid chromatography step, desalting step), the N- (or C-) terminal information often lacks and post-translational modifications (PTMs) are hardly observed. The in-source decay (ISD) occurring in a matrix assisted laser desorption/ionization (MALDI) source appears an interesting analytical tool to obtain N-terminal sequence, to identify proteins and to characterize PTMs by a "top-down" strategy. The goal of this review deals with the usefulness of the ISD technique in MALDI source in proteomics fields. In the first part, the ISD principle is explained and in the second part, the use of ISD in proteomic studies is discussed for protein identification and sequence characterization.

Proteomics in cancer

Proteomic studies have generated numerous datasets of potential diagnostic, prognostic, and therapeutic significance in human cancer. Two key technologies underpinning these studies in cancer tissue are two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry (MS). Although surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF)-MS is the mainstay for serum or plasma analysis, other methods including isotope-coded affinity tag technology, reverse-phase protein arrays, and antibody microarrays are emerging as alternative proteomic technologies. Because there is little overlap between studies conducted with these approaches, confirmation of these advanced technologies remains an elusive goal. This problem is further exacerbated by lack of uniform patient inclusion and exclusion criteria, low patient numbers, poor supporting clinical data, absence of standardized sample preparation, and limited analytical reproducibility (in particular of 2D-PAGE). Despite these problems, there is little doubt that the proteomic approach has the potential to identify novel diagnostic biomarkers in cancer. In therapeutic proteomics, the challenge is significant due to the complexity systems under investigation (i.e., cells generate over 10(5) different polypeptides). However, the most significant contribution of therapeutic proteomics research is expected to derive not from single experiments, but from the synthesis and comparison of large datasets obtained under different conditions (e.g., normal, inflammation, cancer) and in different tissues and organs. Thus, standardized processes for storing and retrieving data obtained with different technologies by different research groups will have to be developed. Shifting the emphasis of cancer proteomics from technology development and data generation to careful study design, data organization, formatting, and mining is crucial to answer clinical questions in cancer research.

Usefulness of autoantigens depletion to detect autoantibody signatures by multiple affinity protein profiling

Patients with cancer produce specific autoantibodies against protein antigens present in limited amount among a large background of immunoglobulins (Igs), nonrelevant as biomarkers, including natural antibodies. Multiple affinity protein profiling (MAPPing) that combines 2-D immunoaffinity chromatography, enzymatic digestion of the isolated proteins, and identification by MS/MS, may facilitate the identification of these so far unknown patient antibodies. The first immunoaffinity chromatography is crucial, as it is used for selectively removing proteins (autoantigens) recognized by natural antibodies. Application of this depletion step to colon cancer cell proteins is specifically described along with the identification of the natural autoantigens, as well as the coupling of this depletion step with the next steps. By enabling to separate antibody-binding proteins recognized by either natural autoantibodies or patient-specific antibodies this approach may contribute significantly towards the definition of autoantibody signatures.

Cancer immunomics using autoantibody signatures for biomarker discovery

The increased incidence of autoantibodies in malignancies has been described since the 1970s. Thus the ability to determine molecular fingerprinting of autoantibodies (antibody signatures) may provide useful clinical diagnostic and prognostic information. This review describes the use of several proteomics approaches for the identification of antigens recognized by these autoantibodies. Serological proteome analysis combines separation of tumor cell proteins on two-dimensional gel electrophoresis gels, Western blotting with sera of patients and healthy subjects, and identification of the detected antigens by MS. Alternatively multiple affinity protein profiling combines isolation of the antigens recognized by patient antibodies by two-dimensional immunoaffinity chromatography and identification by MS/MS. The use and limitations of reverse phase protein microarrays for testing patient serum containing autoantibodies are also considered. Lastly the most important difficulty of any proteomically identified autoantibody signature is validation in patient cohorts or clinical samples.

The laboratory approach to the diagnosis of autoimmune diseases: is it time to change?

Array technology and proteomics are about to launch the era of multiplexed analysis, which allows simultaneous detection of numerous autoantibody specificities and the possibility of defining broad autoantibody profiles. This will probably improve disease staging, risk stratification, prognosis and treatment. However, although these technologies are very promising, they are still in their infancy, and therefore need to undergo strict analytical and clinical validation processes. The latter should involve clinicians and pathologists in prospective, multicentric studies conducted on large numbers of patients to define the specific significance of the various autoantibody profiles. Establishing common standards for the publication and sharing of microarray-generated data will be important for this purpose. Only when these studies have been completed will these new technologies find a place in clinical laboratories. Although we are entering a decade which will probably see a radical change in the diagnostic approach to autoimmune diseases, we do not yet have sufficient knowledge to apply proteomic technologies on a large scale. For the time being, therefore, it is advisable to continue using well-established approaches and diagnostic algorithms such as those reported in the international guidelines, which have been prepared in accordance with the principles of appropriateness and evidence-based medicine.

Use of proteomics in analysis of autoimmune diseases

Autoimmune diseases are common by diseases characterized by disorders of immune responses and autoimmune impairment involving multiple tissues, organs and systems. The autoantigens (Ags)/autoantibodies (Abs) are not only hallmarks but also involved in pathogenesis of autoimmune diseases. In recent years, proteomics technologies have been used and demonstrated effective in searching new Ags/Abs as well as disease biomarkers in autoimmune diseases.