Serum peptidome based biomarkers searching for monitoring minimal residual disease in adult acute lymphocytic leukemia

Clinical Peptidomics in Acute Leukemias: Current Advances and Future Perspectives

The study of circulating peptides in the blood offers significant opportunities for diagnosing, stratifying, and managing various diseases. With recent technological advances and the ongoing need to understand complex diseases such as acute leukemias (AL), peptidomic analysis of peripheral blood, especially serum and plasma, has become increasingly important for studying human biology and pathophysiology. Here, we provide insights and perspectives on technological developments and potential clinical applications using widely used peptidomic analysis methods. We discuss examples where peptidomics using serum or plasma has contributed to the understanding of AL. Specifically, we highlight the scarcity of peptidomic studies applied to AL and emphasize the importance of exploring this area, as the few published studies present promising results that can significantly contribute to precision medicine.

Mass Spectrometry Contribution to Pediatric Cancers Research

For over four decades, mass spectrometry-based methods have provided a wealth of information relevant to various challenges in the field of cancers research. These challenges included identification and validation of novel biomarkers for various diseases, in particular for various forms of cancer. These biomarkers serve various objectives including monitoring patient response to the various forms of therapy, differentiating subgroups of the same type of cancer, and providing proteomic data to complement datasets generated by genomic, epigenetic, and transcriptomic methods. The same proteomic data can be used to provide prognostic information and could guide scientists and medics to new and innovative targeted therapies The past decade has seen a rapid emergence of epigenetics as a major contributor to carcinogenesis. This development has given a fresh momentum to MS-based proteomics, which demonstrated to be an unrivalled tool for the analyses of protein post-translational modifications associated with chromatin modifications. In particular, high-resolution mass spectrometry has been recently used for systematic quantification of chromatin modifications. Data generated by this approach are central in the search for new therapies for various forms of cancer and will help in attempts to decipher antitumor drug resistance. To appreciate the contribution of mass spectrometry-based proteomics to biomarkers discovery and to our understanding of mechanisms behind the initiation and progression of various forms of cancer, a number of recent investigations are discussed. These investigations also include results provided by two-dimensional gel electrophoresis combined with mass spectrometry.

Oxidative Modification Status of Human Serum Albumin Caused by Chronic Low-Dose Radiation Exposure in Mamuju, Sulawesi, Indonesia

The recently discovered high-level natural background radiation area (HBRA) of Mamuju in Indonesia provides a unique opportunity to study the biological effects of chronic low-dose radiation exposure on a human population. The mean total effective dose in the HBRA was approximately 69.6 mSv y^-1 (range: 47.1 to 115.2 mSv y^-1), based on a re-evaluation of the individual radiation exposure dose; therefore, proteomic analyses of serum components and oxidative modification profiling of residents living in the HBRA were reconducted using liquid chromatography-tandem mass spectrometry. The analysis of the oxidative modification sequences of human serum albumin revealed significant moderate correlations between the radiation dose and the modification of 12 sequences, especially the 111th methionine, 162nd tyrosine, 356th tyrosine, and 470th methionine residues. In addition, a dose-dependent variation in 15 proteins of the serum components was detected in the serum of residents exposed to chronic low-dose radiation. These findings suggest that the alterations in the expression of specific proteins and the oxidative modification responses of serum albumin found in exposed humans may be important indicators for considering the effects of chronic low-dose radiation exposure on living organisms, implying their potential utility as biomarkers of radiation dose estimation.

Serum proteomics screening intercellular adhesion molecule-2 improves intermediate-risk stratification in acute myeloid leukemia

Background

The clinical risk classification of acute myelocytic leukemia (AML) is largely based on cytogenetic and molecular genetic detection. However, the optimal treatment for intermediate-risk AML patients remains uncertain. Further refinement and improvement of prognostic stratification are therefore necessary.

Objectives

The aim of this study was to identify serum protein biomarkers to refine risk stratification in AML patients.

Design

This study is a retrospective study.

Methods

Label-free proteomics was used to identify the differential abundance of serum proteins in AML patients. Transcriptomic data were combined to identify key altered markers that could indicate the risk rank of AML patients. The survival status was assessed by Kaplan-Meier and multivariate Cox regression analyses.

Results

We delineated serum protein expression in a population of AML patients. Many biological processes were influenced by the identified differentially expressed proteins. Association analysis of transcriptome data showed that intercellular adhesion molecule-2 (ICAM2) had a higher survival prediction value in the intermediate-risk AML group. ICAM2 was detrimental for intermediate-risk AML, regardless of whether patients received bone marrow transplantation. ICAM2 well distinguishes the intermediate group of patients, whose probability of survival is comparable to that of patients with the ELN-2017 according to the reference classification. In addition, newly established stratified clinical features were associated with leukemia stem cell scores.

Conclusion

The inclusion of ICAM2 expression into the AML risk classification according to ELN-2017 was a good way to transfer patients from three to two groups. Thus, providing more information for clinical decision-making to improve intermediate-risk stratification in AML patients.

Albumin/fibrinogen ratio, a predictor of chemotherapy resistance and prognostic factor for advanced gastric cancer patients following radical gastrectomy

Background

The objective of this study was to investigate potential predictors of chemotherapy resistance in patients with advanced gastric cancer (GC) following radical gastrectomy.

Methods

Eligible stage II/III GC patients with adjuvant chemotherapy after radical gastrectomy were enrolled in this study. A receiver operating characteristic (ROC) curve analysis was performed to assess the predictive and optimal cut-off values of continuous variables for chemotherapy resistance. Potential risk factors for chemotherapy resistance were determined with binary univariate and multivariate analyses. Potential prognostic factors for overall survival (OS) were determined by COX regression analysis. The association between survival and AFR level was examined using the Kaplan–Meier curve analysis.

Results

A total of 160 patients were included in the data analysis, and 41 patients achieved chemotherapeutic resistance with an incidence of 25.6%. Pretreatment albumin/fibrinogen ratio (AFR) (cut-off value: 10.85, AUC: 0.713, P < 0.001) was a predictor for chemotherapeutic resistance by ROC curve analysis. Low AFR (< 10.85) was an independent risk factor of chemotherapeutic resistance as determined by the univariate and multivariate logistic regression analyses (OR: 2.55, 95%CI: 1.21–4.95, P = 0.005). Multivariate COX regression analyses indicated low AFR as a prognostic factor for 5-year OS (HR: 0.36, 95%CI: 0.15–0.73, P = 0.011). Low AFR was associated with poorer 5-year disease-free survival and overall survival.

Conclusions

This study indicated that a low level of pretreatment AFR could serve as an independent predictor of chemotherapy resistance and postoperative prognosis in GC patients following radical gastrectomy.

Label-Free Quantitative Comparison of Cervical Mucus Peptides in Subjects With Endocervical Adenocarcinoma and Adenocarcinoma in Situ

Purpose:

To uncover potential diagnostic biomarkers for endocervical adenocarcinoma (EAC) and adenocarcinoma in situ (AIS).

Experimental design:

Quantitative label-free liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) peptidomics strategies were employed to profile 8 cervical mucus (CM) samples, including 3 EAC cases, 2 AIS cases and 3 normal controls (Ctrl).

Results:

Among the 3721 exclusive peptides identified, 12 (5 up-regulated and 7 down-regulated) endogenous peptides were significantly expressed in EAC compared to healthy controls (EAC/Ctrl); 10 (7 up-regulated and 3 down-regulated) endogenous peptides were significantly expressed in AIS compared to healthy controls (AIS/Ctrl); 11 (6 up-regulated and 5 down-regulated) endogenous peptides were significantly expressed in EAC compared to AIS (EAC/AIS) (absolute fold change ≥1.5, Benjamini-Hochberg adjusted p-value ≤0.05). Among these identifications, annexin A1 (ANXA1) was found to be down-regulated both in EAC and AIS, and its unique peptide (FIENEEQEYVQTVK) may be promising indicators for cervical glandular epithelial lesions.

Conclusion:

This is the first study to utilize CM peptidomics in cervical glandular malignancies, which may reveal the novel noninvasive biomarkers for EAC and AIS.

Fibrinogen alpha chain promotes the migration and invasion of human endometrial stromal cells in endometriosis through focal adhesion kinase/protein kinase B/matrix metallopeptidase 2 pathway†

Fibrinogen alpha chain (FGA), a cell adhesion molecule, contains two arginyl-glycyl-aspartic acid (RGD) cell adhesion sequences. Our previous study demonstrated that FGA, as an up-regulated protein in endometriosis (EM), was closely related to disease severity and involved in the development of EM. However, the biological functions and underlying mechanism of FGA in EM have not been fully understood. To explore the roles of FGA in EM, we analyzed the effects of FGA on the biological behaviors of human primary eutopic endometrial stromal cells (EuESC). The results indicated FGA knockdown suppressed the migration and invasion ability of EuESC, which also altered the distribution of cytoskeletal filamentous and cell morphology. Western blot analysis demonstrated that knockdown of FGA attenuated the migration-related protein levels of vimentin and matrix metallopeptidase 2 (MMP-2), but not integrin subunit alpha V (ITGAV) and integrin subunit beta 3 (ITGB3). Meanwhile, integrin-linked transduction pathways were detected. We found FGA knockdown significantly suppressed the expression of focal adhesion kinase (FAK) level and protein kinase B (AKT) phosphorylation, without extracellular-signal-regulated kinase (ERK) dependent pathways. Treatment with the AKT inhibitor MK2206 or RGD antagonist highly decreased the effects of FGA on the migration and invasion of EuESC. RGD antagonist treatment strongly inhibited FAK- and AKT-dependent pathways, but not ERK pathways. Our data indicated that FGA may enhance the migration and invasion of EuESC through RGD sequences binding integrin and activating the FAK/AKT/MMP-2 signaling pathway. This novel finding suggests that FGA may provide a novel potential approach to the treatment of EM, which provides a new way to understand the pathogenesis of EM.

Isoform 1 of Fibrinogen Alpha Chain Precursor is a Potential Biomarker for Steroid-Induced Osteonecrosis of the Femoral Head

PURPOSE

Early diagnosis is crucial to increase the chances of conservation treatment for patients with steroid-induced osteonecrosis of the femoral head (SIONFH). This study aimed to identify serum peptides as potential biomarkers to diagnose SIONFH.

EXPERIMENTAL DESIGN

The serum proteome of 32 SIONFH patients and 24 healthy controls are analyzed using magnetic bead-based weak cation exchange (MB-WCX) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). Next, candidate biomarkers are identified using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Candidate biomarkers are then validated using ELISA and western blotting.

RESULTS

39 peaks are identified and the expression fold changes of seven peaks in the two groups are greater than 1.5. Three peaks (m/z: 1077.84 Da; m/z: 1061.78 Da; m/z: 1099.56 Da) tend to be upregulated, while four peaks (m/z: 3973.92 Da; m/z: 7766.53 Da; m/z: 3957.31 Da; m/z: 4212.02 Da) tend to be down-regulated in SIONFH patients. The peak for a 1077.84 Da peptide is identified as Isoform 1 of the Fibrinogen alpha chain precursor (FGA). ELISAs and western blot analyses reveal that the expression of FGA is significantly higher in SIONFH patients than healthy controls.

CONCLUSION AND CLINICAL RELEVANCE

FGA is overexpressed in SIONFH patients, and thus, is a novel potential biomarker for SIONFH.

Proteomic Analysis of Cerebrospinal Fluid From Patients With Extranodal NK-/T-Cell Lymphoma of Nasal-Type With Ethmoidal Sinus Metastasis

Objective: Extranodal natural killer /T-cell lymphoma (ENKTL) is an aggressive and unusual subtype of non-Hodgkin lymphoma (NHL) that it is related with the Epstein-Barr virus (EBV). CSF is considered as an ideal source of high-concenrtation disease-related proteins. We aimed at identifying the proteomic markers changes of CSF in ENKTL patients and used such changes to diagnose ENKTL.

Materials and methods: In this study, CSF samples were acquired from hospitalization patients from the Cancer Center of West China Hospital, Chengdu, China. Comparative proteomic profiling are commonly used to do label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS). And in this study the same method was used to characterize the variety of proteins in ENKTL patients and none-ENKTL people.

Results: In the aggregate, 421 non-excrescent and functional proteins were identified among the samples. Of these proteins, 45 proteins quantified match the involved criteria. HRG, TIMP-1, SERPINA3, FGA, FGG, TF, FGB, APP, and AGT were significantly up-regulated.

Discussion: We discovered that some proteins were significantly up-regulated. Also, these proteins themselves or with others proteins may be potential markers to diagnose ENKTL. The changes of proteomics may be a potential method to precisely identify the pathogenesis of the ENKTL.

A comparative proteomic study of plasma in Colombian childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Owing to the incorporation of risk-adapted therapy and the arrival of new directed agents, the cure rate and survival of patients with ALL have improved dramatically, get near to 90%. In Latin American countries, the mortality rates of ALL are high, for example in Colombia, during the last decade, ALL has been the most prevalent cancer among children between 0–14 years of age. In the face of this public health problem and coupled with the fact that the knowledge of the proteome of the child population is little, our investigation proposes the study of the plasma proteome of Colombian children diagnosed with B-cell ALL (B-ALL) to determine potential disease markers that could reflect processes altered by the presence of the disease or in response to it. A proteomic study by LC-MS/MS and quantification by label-free methods were performed in search of proteins differentially expressed between healthy children and those diagnosed with B-ALL. We quantified a total of 472 proteins in depleted blood plasma, and 25 of these proteins were differentially expressed (fold change >2, Bonferroni-adjusted P-values <0.05). Plasma Aggrecan core protein, alpha-2-HS-glycoprotein, coagulation factor XIII A chain and gelsolin protein were examined by ELISA assay and compared to shotgun proteomics results. Our data provide new information on the plasma proteome of Colombian children. Additionally, these proteins may also have certain potential as illness markers or as therapeutic targets in subsequent investigations.

Fibrinogen alpha chain is up-regulated and affects the pathogenesis of endometriosis

RESEARCH QUESTION

In the group's previous study, fibrinogen alpha chain (FGA) was identified as an up-regulated differential protein that was highly expressed in women with endometriosis. The current study investigated the expression and effects of FGA in endometriosis. It also evaluated the effects of FGA on human endometrial stromal cells and studied the possible mechanism.

DESIGN

This was a cross-sectional analysis of FGA expression in plasma and endometrial tissue of matched eutopic and ectopic samples from women with endometriosis undergoing laparoscopic surgery and samples from women without endometriosis. Forty-four patients with endometriosis and 32 healthy control subjects who donated plasma for FGA analysis, including 26 matched cases of eutopic and ectopic endometria from endometriosis patients and 22 endometria from healthy control subjects, were analysed. The effects of FGA were studied in a human endometrial stromal cell line after transfection with FGA short interfering RNA (siRNA).

RESULTS

FGA concentrations in serum and expression in eutopic and ectopic endometrial tissue were significantly higher in women with endometriosis than controls (P < 0.05 and P < 0.01 respectively), whereas FGA expression was not significantly different in eutopic compared with ectopic endometrial tissues from the same patients. High FGA concentrations in serum were related to disease stage and ovarian involvement, but were not affected by age and menstrual cycle. The knockdown of FGA expression by FGA siRNA inhibited hEM15A cellular adhesion, migration and invasion, and attenuated matrix metalloproteinase-2 (MMP-2) expression.

CONCLUSIONS

High FGA expression in endometriosis was closely related to disease severity and affected cell adhesion, migration and invasion, which might play an important role in the pathogenesis of endometriosis.

Identification of serum proteins AHSG, FGA and APOA-I as diagnostic biomarkers for gastric cancer

Background

The development of clinically accessible biomarkers is critical for the early diagnosis of gastric cancer (GC) in patients. High-throughput proteomics techniques could not only effectively generate a serum peptide profile but also provide a new approach to identify potentially diagnostic and prognostic biomarkers for cancer patients.

Methods

In this study, we aim to identify potentially discriminating serum biomarkers for GC. In the discovery cohort, we screened potential biomarkers using magnetic-bead-based purification and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in 64 samples from 32 GC patients that were taken both pre- and post-operatively and 30 healthy volunteers that served as controls. In the validation cohort, the expression patterns and diagnostic values of serum FGA, AHSG and APOA-I were further confirmed by ELISA in 42 paired GC patients (pre- and post-operative samples from 16 patients with pathologic stage I/II and 26 with stage III/IV), 30 colorectal cancer patients, 30 hepatocellular carcinoma patients, and 28 healthy volunteers.

Results

ClinProTools software was used and annotated 107 peptides, 12 of which were differentially expressed among three groups (P < 0.0001, fold > 1.5). These 12 peptide peaks were further identified as FGA, AHSG, APOA-I, HBB, TXNRD1, GSPT2 and CAKP5. ELISA data suggested that the serum levels of FGA, AHSG and APOA-I in GC patients were significantly different compared with healthy controls and had favorable diagnostic values for GC patients. Moreover, we found that the serum levels of these three proteins were associated with TNM stages and could reflect tumor burden.

Conclusion

Our findings suggested that FGA, AHSG and APOA-I might be potential serum biomarkers for GC diagnosis.

Effects of different sources of protein on the growth performance, blood chemistry and polypeptide profiles in the gastrointestinal tract digesta of newly weaned piglets

To determine the effects of different sources of protein on the growth performance of newly weaned piglets, 72 newly weaned piglets were randomly assigned to three groups fed different diets (soya bean, casein and dried distillers' grain with solubles (DDGS) feeds). Casein and DDGS feeds consisted of soya bean feed in which 5% of the CP was replaced with casein- or DDGS-derived CP respectively. Blood and chyme samples were collected from each piglet 2 h post-feeding on days 0 and 28 of the feeding period. The DDGS feed decreased DMI (p = 0.024) and increased FCR (p = 0.025) due to lower nitrogen utilization (p = 0.078) than those of other feeds. Total amino acid content in chyme demonstrated that casein feed digested rapidly in the duodenum (p = 0.005), whereas DDGS feed was digested primarily in the distal jejunum (p = 0.003) and ileocecum (p = 0.002). However, polypeptide profiles in chyme exhibited a pattern different from those of amino acids. There were no differences in the polypeptide profiles in the stomachs of piglets fed soya bean or casein feeds (p > 0.05), but soya bean group had greater amounts of small polypeptides (mass under m/z 3000 Da) in the duodenum (p = 0.052) than other groups. In contrast, the DDGS feed group had more large polypeptides (m/z 3000-4000 Da) in the stomach than the other groups (p < 0.001). In addition, 10 pairs of polypeptides with matching masses were identified in the plasma and digesta, indicating that polypeptides may have been transported across the intestinal epithelial cells and into the blood. Taken together, substitution of 5% of the CP in soya bean meal-based feed with DDGS-derived CP decreased the growth performance of newly weaned piglets due to poor digestibility and N utilization of DDGS feed, as well as untimely digestion of casein feed.

Standardisation of minimal residual disease in multiple myeloma

The assessment of the effectiveness of chemotherapy in oncology cannot disregard the concept of minimal residual disease (MRD). In fact, the efforts of numerous scientific groups all over the world are currently focusing on this issue, with the sole purpose of defining sensitive, effective assessment criteria that are, above all, able to give acceptable, easily repeatable results worldwide. Regarding this issue, especially with the advent of new drugs, multiple myeloma is one of the haematologic malignancies for which a consensus has not yet been reached. In this review, we analyse various techniques that have been used to improve the sensitivity of response, aimed at reducing the cut-off values previously allowed, as well as serological values like serum-free light chain, or immunophenotypic tools on bone marrow or peripheral blood, like multi-parameter flow cytometry, or molecular ones such as allele-specific oligonucleotide (ASO)-qPCR and next-generation/high-throughput sequencing technologies (NGS). Moreover, our discussion makes a brief reference to promising techniques, such as mass spectrometry for identifying Ig light chain (LC) in peripheral blood, and the assessment of gene expression profile not only in defining prognostic risk at the diagnosis but also as a tool for evaluation of response.

Involvement of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells

Leukemia is a type of hematopoietic stem cell malignant cloned disease with high mortality. Cisplatin-based chemotherapy is one of the most common treatments for leukemia. Similar to other chemotherapeutic agents, cisplatin resistance has become a serious issue in cancer therapy. In the present study, we investigated the role of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells. Firstly, the L1210 cell line resistant to cisplatin (L1210/DDP) was established. Compared to its parental cell line, the IC50 value of cisplatin in the L1210/DDP cells was increased 10-fold. Mitofusins (Mfn1 and Mfn2), mitochondrial outer membrane fusion proteins, were markedly upregulated in the L1210/DDP cells, whereas the expression of fission protein Drp1 and inner membrane fusion protein OPA1 were not significantly altered. In addition, mitofusins were also upregulated in the parental L1210 cells subjected to cisplatin stress. To investigate the role of mitochondrial dynamics in the antineoplastic activity of cisplatin, the effect of mitochondrial division inhibitor (Mdivi)-1 on cisplatin‑induced cell death, caspase-3 cleavage and ROS production was examined in L1210 cells. We found that 5 µM of Mdivi-1 efficiently attenuated cisplatin-induced cell death, caspase activation and intracellular ROS increase in L1210 cells. Our data indicated that mitochondrial dynamics play an important role in the antineoplastic activity of cisplatin, and mitofusin-mediated mitochondrial fusion may be involved in the process of cisplatin resistance in leukemia cells. Therefore, the present study revealed that mitochondrial dynamics may be a potential target used to improve the antineoplastic activity of cisplatin in leukemia in the future.

Proteome analysis of sheep B lymphocytes in the course of bovine leukemia virus-induced leukemia

Presented are the results of a study of the expression pattern of different proteins in the course of bovine leukemia virus-induced leukemia in experimental sheep and I discuss how the obtained data may be useful in gaining a better understanding of the pathogenesis of the disease, diagnosis, and for the selection of possible therapeutic targets. In cattle, the disease is characterized by life-long persistent lymphocytosis leading to leukemia/lymphoma in about 5% of infected animals. In sheep, as opposed to cattle, the course of the disease is always fatal and clinical symptoms usually occur within a three-year period after infection. For this reason, sheep are an excellent experimental model of retrovirus-induced leukemia. This model can be useful for human pathology, as bovine leukemia virus is closely related to human T-lymphotropic virus type 1. The data presented here provide novel insights into the molecular mechanisms of the bovine leukemia virus-induced tumorigenic process and indicate the potential marker proteins both for monitoring progression of the disease and as possible targets of pharmacological intervention. A study of the proteome of B lymphocytes from four leukemic sheep revealed 11 proteins with altered expression. Among them, cytoskeleton and intermediate filament proteins were the most abundant, although proteins belonging to the other functional groups, i.e. enzymes, regulatory proteins, and transcription factors, were also present. It was found that trypsin inhibitor, platelet factor 4, thrombospondin 1, vasodilator-stimulated phosphoprotein, fibrinogen alpha chain, zyxin, filamin-A, and vitamin D-binding protein were downregulated, whereas cleavage and polyadenylation specificity factor subunit 5, non-POU domain-containing octamer-binding protein and small glutamine-rich tetratricopeptide repeat-containing protein alpha were upregulated. Discussed are the possible mechanisms of their altered expression and its significance in the bovine leukemia virus-induced leukemogenic process. Impact statement The submitted manuscript provides new data on the molecular mechanisms of BLV-induced tumorigenic process indicating the potential marker proteins both for monitoring the progression of the disease and as possible targets of pharmacological intervention. This is to my knowledge the first study of the proteome of the transformed lymphocytes in the course of bovine leukemia virus-induced leukemia in susceptible animals. BLV can be considered as useful model for related human pathogen - HTLV-1, another member of the deltaretrovirus genus evolutionary closely related to BLV. Information gathered in this study can be useful to speculate on possible shared mechanisms of deltaretrovirus-induced carcinogenesis.

Identification of biomarkers for endometriosis using clinical proteomics

Background:

We investigated possible biomarkers for endometriosis (EM) using the ClinProt technique and proteomics methods.

Methods:

We enrolled 50 patients with EM, 34 with benign ovarian neoplasms and 40 healthy volunteers in this study. Serum proteomic spectra were generated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) combined with weak cationic exchange (WCX) magnetic beads. Possible biomarkers were analyzed by a random and repeat pattern model-validation method that we designed, and ClinProtools software, results were refined using online liquid chromatography-tandem MS.

Results:

We found a cluster of 5 peptides (4210, 5264, 2660, 5635, and 5904 Da), using 3 peptides (4210, 5904, 2660 Da) to discriminate EM patients from healthy volunteers, with 96.67% sensitivity and 100% specificity. We selected 4210 and 5904 m/z, which differed most between patients with EM and controls, and identified them as fragments of ATP1B4, and the fibrinogen alpha (FGA) isoform 1/2 of the FGA chain precursor, respectively.

Conclusions:

ClinProt can identify EM biomarkers, which – most notably – distinguish even early-stage or minimal disease. We found 5 stable peaks at 4210, 5264, 2660, 5635, and 5904 Da as potential EM biomarkers, the strongest of which were associated with ATP1B4 (4210 Da) and FGA (5904 Da); this indicates that ATP1B4 and FGA are associated with EM pathogenesis.