Prostate cancer (PCa) is the second most prevalent cancer among men worldwide when assessing age-standardized incidence rates. The primary method for early PCa diagnosis involves measuring the... Show moreProstate cancer (PCa) is the second most prevalent cancer among men worldwide when assessing age-standardized incidence rates. The primary method for early PCa diagnosis involves measuring the serum concentration of prostate-specific antigen (PSA), with elevated levels (> 3 ng/mL in the Netherlands) indicating the potential presence of PCa. However, the conventional PSA test exhibits a low specificity. Thus, clinical challenges persist, including the differentiation between PCa and benign prostatic hyperplasia and distinguishing indolent PCa from aggressive forms. This underscores the need for a more specific biomarker for early PCa detection and stratification. Previous studies have reported altered glycosylation features in two prostate-secreted glycoproteins, PSA and prostatic acid phosphatase (PAP) in PCa patients, e.g. variation in sialylation, fucosylation and the level of LacdiNAc . The aim of this thesis was to identify PCa biomarkers for early detection and to improve patient stratification, focusing specifically on the glycomic profiles of PSA and PAP. In addition, as PSA plays an important role with regard to fertility, its glycosylation -in relation to male infertility- was also touched upon. For this purpose, mass spectrometry (MS) based glycoproteomic methods were established to map the glycoprofiles of PSA and PAP derived from various biofluids. Show less
Wang, W.; Nier, C.R. de; Wuhrer, M.; Lageveen-Kammeijer, G.S.M. 2023
Prostate-specific antigen (PSA) is a well-known clinical biomarker in prostate cancer (PCa) diagnosis, but a better test is still needed, as the serum-level-based PSA quantification exhibits... Show moreProstate-specific antigen (PSA) is a well-known clinical biomarker in prostate cancer (PCa) diagnosis, but a better test is still needed, as the serum-level-based PSA quantification exhibits limited specificity and comes with poor predictive value. Prior to PSA, prostatic acid phosphatase (PAP) was used, but it was replaced by PSA because PSA improved the early detection of PCa. Upon revisiting PAP and its glycosylation specifically, it appears to be a promising new biomarker candidate. Namely, previous studies have indicated that PAP glycoforms differ between PCa and non-PCa individuals. However, an in-depth characterization of PAP glycosylation is still lacking. In this study, we established an in-depth glycoproteomic assay for urinary PAP by characterizing both the micro- and macroheterogeneity of the PAP glycoprofile. For this purpose, PAP samples were analyzed by capillary electrophoresis coupled to mass spectrometry after affinity purification from urine and proteolytic digestion. The developed urinary PAP assay was applied on a pooled DRE (digital rectal examination) urine sample from nine individuals. Three glycosylation sites were characterized, namely N-94, N-220, and N-333, via N-glycopeptide analysis. Taking sialic acid linkage isomers into account, a total of 63, 27, and 4 N-glycan structures were identified, respectively. The presented PAP glycoproteomic assay will enable the determination of potential glycomic biomarkers for the early detection and prognosis of PCa in cohort studies. Show less
In a typical glycosylation reaction, a donor is activated to form a (variety of) electrophilic species which can react with a nucleophilic acceptor, following a reaction mechanism having both SN1... Show moreIn a typical glycosylation reaction, a donor is activated to form a (variety of) electrophilic species which can react with a nucleophilic acceptor, following a reaction mechanism having both SN1 and SN2 character. On the SN1-side of the spectrum oxocarbenium ions partake in the mechanism while covalent intermediates act as the product forming intermediates on the SN2-side. The result of a glycosylation reaction is influenced by the properties of both donor and acceptor and can be affected by external factors as well. Because the challenges in carbohydrate synthesis are typically solved for a specific synthetic problem, a general understanding of what effect changing a single variable has on the mechanistic pathway, and thus the (stereochemical) outcome is not available. This in turn means that synthesis of glycosidic bonds typically requires a considerable amount of optimisation at the expense of a significant amount of time and resources. The goal of this thesis is to systematically investigate how changes in stereochemistry and protecting group patterns on the donor and acceptor affect the mechanism and outcome of glycosylation reactions, to enable a more rational design of synthesis routes. Show less
The research described in this thesis focused on the use of bioorthogonal antigens to investigate immunological processes in antigen presenting cells. Bioorthogonal antigens are antigenic proteins... Show moreThe research described in this thesis focused on the use of bioorthogonal antigens to investigate immunological processes in antigen presenting cells. Bioorthogonal antigens are antigenic proteins produced through recombinant expression in a methionine auxotrophic E. coli strain. This allows for the replacement of methionine residues with the bioorthogonal non-canonical amino acid, azidohomoalanine (Aha), that resembles methionine. Aha contains an azide group that enables the selective and rapid visualization or enrichment of the antigen after a biological experiment using alkyne-modified fluorophores or alkyne-containing resins, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The research involved studying the effects of post-translational modifications (PTMs), antigen complexation and glycosylation of antibodies in immune complexes on the uptake, proteolysis, and T cell activation by dendritic cells (DCs) of Aha-containing antigens. Additionally, a new method was developed to enrich low abundant bioorthogonal antigenic fragments from complex mixtures. This method can be used in future studies to identify processed Aha-containing fragments from immune cells that are preserved for T cell presentation. Show less
Protein glycosylation has profound implications in a wide range of molecular and biological processes occurring in cancer, where specific changes in the glycan structures have shown to be... Show moreProtein glycosylation has profound implications in a wide range of molecular and biological processes occurring in cancer, where specific changes in the glycan structures have shown to be associated with the development and progression of the disease paving the way for the development of new clinical biomarkers as well as providing specific targets for therapeutic intervention, patient stratification and personalized medicine. Protein glycosylation is also critical for the development of biopharmaceuticals, as even minor shifts in manufacturing procedures can substantially impact the bioactivity, safety, and efficacy of therapeutic proteins. Although a variety of mass spectrometric and chromatographic methods are available for the identification and characterization of glycans from complex sample mixtures, the lack of standardized protocols across platforms often results in inconsistent results, making data integration and comparison challenging. Furthermore, most of the current technology for the study of intact glycans would not be suitable for the rapid analysis of large sample sets, mainly due to limitations in sample throughput. The scope of this thesis is to establish standardized, high-throughput glycomics technologies for the quantitative analysis of protein N- and O-glycosylation and improve current methodologies in order to facilitate the characterization of intact oligosaccharides from in vitro established model systems. Show less
The conserved region (Fc) of IgG antibodies dictates the interactions with designated receptors thus defining the immunological effector functions of IgG. Amino acid sequence variations in the Fc,... Show moreThe conserved region (Fc) of IgG antibodies dictates the interactions with designated receptors thus defining the immunological effector functions of IgG. Amino acid sequence variations in the Fc, recognized as subclasses and allotypes, as well as post-translational modifications (PTMs) modulate these interactions. Yet, the high similarity of Fc sequences hinders allotype-specific PTM analysis by state-of-the-art bottom-up methods and current subunit approaches lack sensitivity and face co-elution of near-isobaric allotypes.To circumvent these shortcomings, we present a nanoscale reversed-phase (RP) HPLC-MS workflow of intact Fc subunits for comprehensive characterization of Fc proteoforms in an allotype- and subclass-specific manner. Polyclonal IgGs were purified from individuals followed by enzymatic digestion releasing single chain Fc subunits (Fc/2) that were directly subjected to analysis. Chromatographic conditions were optimized to separate Fc/2 subunits of near-isobaric allotypes and subclasses allowing allotype and proteoform identification and quantification across all four IgG subclasses. The workflow was complemented by a semi-automated data analysis pipeline based on the open-source software Skyline followed by post-processing in R. The approach revealed pronounced differences in Fc glycosylation between donors, besides inter-subclass and inter-allotype variability within donors. Notably, partial occupancy of the N-glycosylation site in the CH3 domain of IgG3 was observed that is generally neglected by established approaches. The described method was benchmarked across several hundred runs and showed good precision and robustness.This methodology represents a first mature Fc subunit profiling approach allowing truly subclass- and allotype-specific Fc proteoform characterization beyond established approaches. The comprehensive information obtained paired with the high sensitivity provided by the miniaturization of the approach guarantees applicability to a broad range of research questions including clinically relevant (auto)antibody characterization or pharmacokinetics assessment of therapeutic IgGs. Show less
Marco, F. di; Blümel, G.; Blöchl, C.; Wuhrer, M.; Huber, C.G. 2023
BackgroundGonadotropins are a class of heavily glycosylated protein hormones, thus extremely challenging to characterize by mass spectrometry. As biopharmaceuticals, gonadotropins are prescribed... Show moreBackgroundGonadotropins are a class of heavily glycosylated protein hormones, thus extremely challenging to characterize by mass spectrometry. As biopharmaceuticals, gonadotropins are prescribed for the treatment of infertility and are derived from different sources: either from pooled urine of pregnant women or upon production in genetically modified Chinese Hamster Ovary cells. Human chorionic gonadotropin (hCG) is sold as a biopharmaceutical under the name Pregnyl® (urinary hCG, u-hCG) and Ovitrelle® (recombinant hCG, r-hCG), and recombinant human follicle stimulating hormone (r-hFSH) is marketed as Gonal-f®. Recently, we reported the exhaustive characterization of r-hCG at different structural levels.ResultsWe implement size exclusion (SE) HPLC-MS to automatize the acquisition of native mass spectra of r-hCG dimer, but also u-hCG and r-hFSH, comparing the drug products up to intact heterodimer level. A hybrid HPLC-MS approach was employed for the characterization of r-hCG, u-hCG and r-hFSH drug products at different structural levels. Released glycans were analyzed by porous graphitized carbon (PGC)-HPLC-MS/MS, glycopeptides by reversed-phase (RP)-HPLC-MS/MS, subunits by RP-HPLC-MS and finally the intact native heterodimers by semi-automated online buffer exchange SE-HPLC-MS. The data were integrated using bioinformatic tools, to finally unravel the composition of 1481 co-existing dimeric glycoforms for r-hCG, 1167 glycoforms for u-hCG, and 1440 glycoforms for r-hFSH, and to compare critical quality attributes of the different drug products such as their degree of sialylation and O-glycosylation.Significance and noveltyThe strong alliance of bioanalytics and bioinformatics data integration at the different structural levels allowed the identification of more than thousand different glycoforms of r-hCG, u-hCG, and r-hFSH. The results showed that these biopharmaceuticals differ considerably in their glycosylation patterns and highlight the importance of in-depth characterization of biopharmaceuticals for quality control. Show less
Proteins are widely known as key players that fulfill crucial roles at the molecular level in the human body but also for their involvement in many processes in everyday life. For example, proteins... Show moreProteins are widely known as key players that fulfill crucial roles at the molecular level in the human body but also for their involvement in many processes in everyday life. For example, proteins can be used as medicine in health care or for their enzymatic function in the food industry. All these proteins do not exist as a single species but rather as a complex mixture of structural variants, so-called proteoforms. This heterogeneity results mainly from the presence of post-translational modifications (PTMs), such as glycosylation and glycation. To further complicate this matter, these PTMs can induce structural as well as functional changes. To allow in-depth structural and functional characterization of these proteoforms, novel analytical approaches are required to resolve proteoform heterogeneity while persevering protein nativity. The hyphenation of native separation techniques with mass spectrometry has emerged as a powerful approach to reliably study these aspects. The work in this thesis describes the (further) development and application of such methodologies for biopharmaceutical and biotechnological products. Show less
Coillie, J. van; Pongracz, T.; Rahmoller, J.; Chen, H.J.; Geyer, C.E.; Vught, L.A. van; ... ; UMC COVID-19 S HCW Study Grp 2022
Background: Afucosylated IgG1 responses have only been found against membrane-embedded epitopes, including anti-S in SARS-CoV-2 infections. These responses, intrinsically protective through... Show moreBackground: Afucosylated IgG1 responses have only been found against membrane-embedded epitopes, including anti-S in SARS-CoV-2 infections. These responses, intrinsically protective through enhanced Fc gamma RIIIa binding, can also trigger exacerbated pro-inflammatory responses in severe COVID-19. We investigated if the BNT162b2 SARS-CoV-2 mRNA also induced afucosylated IgG responses. Methods: Blood from vaccinees during the first vaccination wave was collected. Liquid chromatography-Mass spectrometry (LC-MS) was used to study anti-S IgG1 Fc glycoprofiles. Responsiveness of alveolar-like macrophages to produce proinflammatory cytokines in presence of sera and antigen was tested. Antigen-specific B cells were characterized and glycosyltransferase levels were investigated by Fluorescence-Activated Cell Sorting (FACS). Findings: Initial transient afucosylated anti-S IgG1 responses were found in naive vaccinees, but not in antigen -experienced ones. All vaccinees had increased galactosylated and sialylated anti-S IgG1. Both naive and antigen -experienced vaccinees showed relatively low macrophage activation potential, as expected, due to the low antibody levels for naive individuals with afucosylated IgG1, and low afucosylation levels for antigen-experienced individuals with high levels of anti-S. Afucosylation levels correlated with FUT8 expression in antigen-specific plasma cells in naive individuals. Interestingly, low fucosylation of anti-S IgG1 upon seroconversion correlated with high anti-S IgG levels after the second dose. Interpretation: Here, we show that BNT162b2 mRNA vaccination induces transient afucosylated anti-S IgG1 responses in naive individuals. This observation warrants further studies to elucidate the clinical context in which potent afucosylated responses would be preferred. Copyright (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Show less
Immunoglobulin G (IgG) antibodies can exert their functions via both Fab-mediated neutralization and Fc-mediated effector functions, both of which are crucial for protective immunity in COVID-19.... Show moreImmunoglobulin G (IgG) antibodies can exert their functions via both Fab-mediated neutralization and Fc-mediated effector functions, both of which are crucial for protective immunity in COVID-19. Importantly, effector functions and resulting inflammatory responses are impacted by the structure of N-glycans linked to the Fc-tail of IgG. Studying antibody glycosylation in emerging infectious diseases such as SARS-CoV-2 allows to gain insight into specific glycan signatures at the early stages of infection, and to investigate whether these reflect how the disease would progress. For example, low fucosylation is a common glyco-phenotypic signature of IgG1 produced against the spike (S) protein of severely ill SARS-CoV-2 infected patients early on in their disease course, but has likewise been described in other disease settings, where the antigen is presented in the context of host-cell membranes (Chapter 2). In this thesis, antibody glycomics signatures of SARS-CoV-2 infection and vaccination have been explored using an established liquid chromatography – mass spectrometry-based method relying on affinity-isolation and proteolytic digestion of both total and anti-S IgG. In Chapter 3, the glycosylation of SARS-CoV-2 anti-S IgG antibodies were found to be vastly skewed relative to total IgG and to change in a highly dynamic fashion. Moreover, IgG glycosylation was shown to be an early severity marker and showed patient stratification potential, with predicting power for intensive care admission within a hospitalized patient population. Early detection of a pro-inflammatory glycosylation pattern may provide a broader intervention window and decrease the number of ICU-admissions. Furthermore, anti-S IgG1 glycosylation levels obtained with LC-MS show promise to supplement clinical parameters and biomarkers of inflammation, that have together been used for the severity score calculation of hospitalized COVID-19 patients. Similarly to SARS-CoV-2 infection, antibodies generated against the spike protein upon BNT162b2 mRNA vaccination also induced a transient afucosylated anti-S IgG1 response in antigen naïve individuals, albeit to a lower extent than in severely ill patients, exemplifying the influence of the type of immunization on antibody glycosylation (Chapter 4). Upon vaccination, the observed initial, mild afucosylated response was additionally accompanied by low fucosyltransferase (FUT8) expression in antigen-specific plasma cells. Furthermore, the observed initial anti-S IgG afucosylation signature may aided mounting a stronger immune response, as indicated by its correlation with antibody amounts following the second vaccination dose. Given the impact of glycosylation on antibody function, deciphering theunderlying regulatory mechanisms influencing IgG glycosylation will be of great importance to better understand the inflammatory potential, vaccine efficacy and protective capacity of vaccine- or pathogen-induced IgG in both body fluids and tissues in the future.In Chapter 5 and 6, the reaction steps of a previously developed linkage-specific sialic acid derivatization workflow were studied in more detail. Key players in such reactions are catalyst, of which novel types with different physico-chemical properties were introduced in Chapter 5. In Chapter 6, prior lactone formation was found to be a prerequisite for subsequent amidation of α2,3-linked sialic acids, which proceeds via direct aminolysis of the C2 lactone. Together, these new insights will be beneficial for the rational optimization of high-throughput (MALDI-)MS-based glycomics and glycoproteomics workflows relying on linkage-specific sialic acid derivatization. Show less
Het onderzoek beschreven in dit proefschrift is gericht op de identificatie en karakterisering van regulatoren en/of effectoren van TGF-β-signalering en TGF-β-geïnduceerde EMT in pancreas-, long-... Show moreHet onderzoek beschreven in dit proefschrift is gericht op de identificatie en karakterisering van regulatoren en/of effectoren van TGF-β-signalering en TGF-β-geïnduceerde EMT in pancreas-, long- en borstkankertypes. Deze nieuw geïdentificeerde componenten en mechanismen kunnen worden onderzocht voor de ontwikkeling van geneesmiddelen voor kankertherapie. Show less
Levink, I.J.M.; Klatte, D.C.F.; Hanna Sawires, R.G.; Vreeker, G.C.M.; Ibrahim, I.S.; Burgt, Y.E.M. van der; ... ; Mesker, W.E. 2022
Background: Surveillance of individuals at risk of developing pancreatic ductal adenocarcinoma (PDAC) has the potential to improve survival, yet early detection based on solely imaging modalities... Show moreBackground: Surveillance of individuals at risk of developing pancreatic ductal adenocarcinoma (PDAC) has the potential to improve survival, yet early detection based on solely imaging modalities is challenging. We aimed to identify changes in serum glycosylation levels over time to earlier detect PDAC in high-risk individuals. Methods: Individuals with a hereditary predisposition to develop PDAC were followed in two surveillance programs. Those, of which at least two consecutive serum samples were available, were included. Mass spectrometry analysis was performed to determine the total N-glycome for each consecutive sample. Potentially discriminating N-glycans were selected based on our previous cross-sectional analysis and relative abundances were calculated for each glycosylation feature. Results: 165 individuals ("FPC-cohort" N = 119; Leiden cohort N = 46) were included. In total, 97 (59%) individuals had a genetic predisposition (77 CDKN2A, 15 BRCA1/2, 5 STK11) and 68 (41%) a family history of PDAC without a known genetic predisposition (>10-fold increased risk of developing PDAC). From each individual, a median number of 3 serum samples (IQR 3) was collected. Ten individuals (6%) developed PDAC during 35 months of follow-up; nine (90%) of these patients carried a CDKN2A germline mutation. In PDAC cases, compared to all controls, glycosylation characteristics were increased (fucosylation, tri-and tetra-antennary structures, specific sialic linkage types), others decreased (complex-type diantennary and bisected glycans).The largest change over time was observed for tri-antennary fucosylated glycans, which were able to differentiate cases from controls with a specificity of 92%, sensitivity of 49% and accuracy of 90%. Conclusion: Serum N-glycan monitoring may support early detection in a pancreas surveillance program.(c) 2022 The Authors. Published by Elsevier B.V. on behalf of IAP and EPC. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Show less
The surface of eukaryotic cells contains a very dense layer of oligosaccharides called glycans that are linked to protein and lipid carriers and play an important role in cell-cell and cell... Show moreThe surface of eukaryotic cells contains a very dense layer of oligosaccharides called glycans that are linked to protein and lipid carriers and play an important role in cell-cell and cell-extracellular matrix interactions. Cancer-induced changes in glycosylation have an impact on the function of major glycoproteins in the human colon, therefore studies focused on colorectal cancer (CRC)-specific glycosylation signatures can provide novel insights into onset and progression of this disease. The major focus of this thesis was to investigate mucin type O-glycosylation signatures of CRC. For this purpose, a protocol for in-depth analysis of N- and O-glycans obtained from cell lines was developed (Chapter 2) using nanoscale porous graphitized carbon liquid chromatography coupled to mass spectrometry (PGC-nano-LC-MS). In Chapter 3 additional conditions were optimized in the MS methodology by using polar protic dopant (methanol and isopropanol) enriched nitrogen gas to increase sensitivity on the MS and tandem MS level. In Chapter 4 we applied the methodology developed in Chapter 2 to the analysis of O-glycosylation signatures of 26 different CRC cell lines. This analysis resulted in the characterization of more than 150 O-glycan structures and increased our understanding of glycan expression in the analyzed cell lines. To gain further understanding in the mechanisms underlying glycomic changes with colon cell differentiation, we explored changes in the cell line glycome and proteome upon spontaneous and butyrate-stimulated differentiation in in vitro cell culture (Chapter 5). By performing an integrative approach, we generated hypotheses about glycosylation signatures of specific cell adhesion proteins, which may play an important role in cancer progression. The localization of glycans on the cell surface and their role in biological processes are important in cancer pathogenesis, making them potential candidates for glycan targeting immunotherapy. Therefore, we further optimized the methodology to enable comprehensive analysis of N- and O-glycans from specific regions of formalin-fixed, paraffin-embedded tissues using laser capture microdissections and applied it for the analysis of selected regions of CRC tissues and their patient-matched colon mucosa controls (Chapter 6). We identified specific tumor-associated carbohydrate antigens (TACAs) that show expression only in the tumor samples, with no or limited expression in the normal colon mucosa. Since TACAs are present in high abundance on the surface of cancer cells which are linked to many different proteins, these are very promising targets for the development of tumor-specific immunotherapy. Show less
Therapeutic proteins have been successfully developed for advancing medical treatments. They are usually large molecules produced by host cells and have a high degree of complexity compared to... Show moreTherapeutic proteins have been successfully developed for advancing medical treatments. They are usually large molecules produced by host cells and have a high degree of complexity compared to synthetic small molecule-based therapeutics. The complexity is mainly attributed to the heterogenic nature of post-translational modifications (PTMs). Glycosylation is one of the main drivers of protein heterogeneity. Since each modification may potentially impact the safety and efficacy, analyticalmethods for the structural and functional characterization of protein-based therapeutics are highly demanded. This thesis presents novel mass spectrometry (MS)-based methods for the analysis of therapeutic glycoproteins. It covers aspects of glycobioinformatics and sample preparation for improved bottom-up glycoproteomic analysis. Further, the profiling of complex intact glycoproteins by matrix-assisted laser desorption ionization (MALDI) Fourier transform ion cyclotron resonance (FT-ICR) MS is demonstrated. Finally, Fc gamma receptor III affinity chromatography combined with online MS detection is presented for novel proteoform-resolved structure-function insights of monoclonal antibodies. Show less
Lippold, S.; Thavarajah, R.; Reusch, D.; Wuhrer, M.; Nicolardi, S. 2021
Recombinant human erythropoietin (EPO) is a complex therapeutic glycoprotein with three N- and one O-glycosylation sites. Glycosylation of EPO influences its safety and efficacy and is defined as a... Show moreRecombinant human erythropoietin (EPO) is a complex therapeutic glycoprotein with three N- and one O-glycosylation sites. Glycosylation of EPO influences its safety and efficacy and is defined as a critical quality attribute. Thus, analytical methods for profiling EPO glycosylation are highly demanded. Owing to the complexity of the intact protein, information about EPO glycosylation is commonly derived from released glycan and glycopeptide analysis using mass spectrometry (MS). Alternatively, comprehensive insights into the glycoform heterogeneity of intact EPO are obtained using ESI MS-based methods with or without upfront separation of EPO glycoforms. MALDI MS, typically performed with TOF mass analyzers, has been also used for the analysis of intact EPO but, due to the poor glycoform resolution, has only provided limited glycoform information. Here, we present a MALDI FT-ICR MS method for the glycosylation profiling of intact EPO with improved glycoform resolution and without loss of sialic acid residues commonly observed in MALDI analysis. Three EPO variants were characterized in-depth and up to 199 glycoform compositions were assigned from the evaluation of doubly-charged ions, without any deconvolution of the mass spectra. Key glycosylation features such as sialylation, acetylation, and N- acetyllactosamine repeats were determined and found to agree with previously reported data obtained from orthogonal analyses. The developed method allowed for a fast and straightforward data acquisition and evaluation and can be potentially used for the high-throughput comparison of EPO samples throughout its manufacturing process. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Show less
Biomarker molecules are analyzed in clinical tests to diagnose a disease, but often these test lack sensitivity or specificity. Also, for many diseases there is not even a blood based test... Show moreBiomarker molecules are analyzed in clinical tests to diagnose a disease, but often these test lack sensitivity or specificity. Also, for many diseases there is not even a blood based test available, while blood collection is relatively low invasive. For breast- and pancreatic cancer, there are several proteins that could potentially serve as biomarkers in blood, but these are not yet specific enough to use for diagnostic testing. Further research on other types of biomarkers may therefore be a valuable addition to eventually be able to develop a blood test. Methods for glycosylation profiling from serum and dried bloodspots with mass spectrometry were developed and applied to pancreatic- and breast cancer biomarker studies. Differences were found between profiles of healthy and sick persons for pancreatic cancer, but no clear differences were seen for breast cancer. This is probably due to the many different forms of breast cancer which result in different profiles. In the future, combining different types of markers from serum might ensure that differences between healthy and sick, between different diseases and between types of disease can be identified. This could lead to the development of a blood test for the early detection of cancer and other diseases. Show less
Wang, W.; Kaluza, A.; Nouta, J.; Nicolardi, S.; Ferens-Sieczkowska, M.; Wuhrer, M.; ... ; Haan, N. de 2021
An altered total seminal plasma glycosylation has been associated with male infertility, and the highly abundant seminal plasma glycoprotein prostate-specific antigen (PSA) plays an important role... Show moreAn altered total seminal plasma glycosylation has been associated with male infertility, and the highly abundant seminal plasma glycoprotein prostate-specific antigen (PSA) plays an important role in fertilization. However, the exact role of PSA glycosylation in male fertility is not clear. To understand the involvement of PSA glycosylation in the fertilization process, analytical methods are required to study the glycosylation of PSA from seminal plasma with a high glycoform resolution and in a protein-specific manner. In this study, we developed a novel, high-throughput PSA glycopeptide workflow, based on matrix-assisted laser desorption/ionization-mass spectrometry, allowing the discrimination of sialic acid linkage isomers via the derivatization of glycopeptides. The method was successfully applied on a cohort consisting of seminal plasma from infertile and fertile men (N = 102). Forty-four glycopeptides were quantified in all samples, showing mainly complex-type glycans with high levels of fucosylation and sialylation. In addition, N,N-diacetyllactosamine (LacdiNAc) motives were found as well as hybrid-type and high mannose-type structures. Our method showed a high intra- and interday repeatability and revealed no difference in PSA glycosylation between fertile and infertile men. Next to seminal plasma, the method is also expected to be of use for studying PSA glycopeptides derived from other biofluids and/or in other disease contexts. Show less
Schistosomiasis is an acute and chronic disease caused by blood dwelling parasitic trematodes of the genus Schistosoma, and it is classified as the second most socioeconomically devastating... Show moreSchistosomiasis is an acute and chronic disease caused by blood dwelling parasitic trematodes of the genus Schistosoma, and it is classified as the second most socioeconomically devastating parasitic disease, second only to malaria. Currently the wormload is determined by the Kato-Katz method, which is not always reliable. In order to prepare diagnostic tools able to capture specific anti-carbohydrate antibodies or develop conjugate vaccines targeting these carbohydrate structures, sufficient amounts of well-defined fragments are needed. This thesis describes the synthesis of several glycans of these glycans present on the S. mansoni parasite, focusing mainly on the Circulating Anodic Antigen (CAA) and glycans bearing the unique α-(1-2)-L-Fucose-α-(1-2)-L-Fucose motifs. These glycans have been attached to gold nanoparticles and these particles were screened against several monoclonal antibodies and sera of individuals suffering from schistosomiasis. Show less
Rheumatoid arthritis (RA) is an auto-inflammatory disease, affecting ~1% of the world population. RA is hallmarked by the presence of autoantibodies, one of the well-known autoantibodies in RA are... Show moreRheumatoid arthritis (RA) is an auto-inflammatory disease, affecting ~1% of the world population. RA is hallmarked by the presence of autoantibodies, one of the well-known autoantibodies in RA are the anti-citrullinated protein antibodies (ACPA). ACPA is highly specific for RA and about 70-80% of the RA patients are positive for ACPA. Previously, we discovered that ACPA-IgG are extensively glycosylated in the variable (V) region. In this thesis, we determined that over 90% of the ACPA-IgG carries glycans in the v-domain were as only 17% of the conventional IgG carries additional glycans. Additionally, the glycans were highly sialylated. Intriguingly, we also showed that the glycans are introduced via somatic hyper mutations in the germinal center reaction. Furthermore, we discovered that ACPA-IgG v-domain glycosylation is a predictive marker for the development of ACPA positive RA. Lastly, we found that the binding strength is not influenced by the glycans but it influences the amount of available binding sites. Nevertheless, the ACPA-BCR still overcome negative selection which might suggest that the glycans can trigger an alternative way for positive selection in the germinal center. This will be subject for further studies regarding the role of ACPA-IgG v-domain glycosylation. Show less
Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by systemic and persistent inflammation of the joints. Around 50-80% of the RA patients harbour either one or multiple types... Show moreRheumatoid arthritis (RA) is a chronic autoimmune disease characterized by systemic and persistent inflammation of the joints. Around 50-80% of the RA patients harbour either one or multiple types of autoantibodies, under which also Anti-Citrullinated Protein Antibodies (ACPA). ACPA are highly specific for RA and are strongly associated with the severity of arthritis. The studies described in this thesis aim to explore the structure and biological function of ACPA and the B cells producing these ACPA.The studies highlight the importance of the synovial environment for the survival of ACPA B cells. Moreover, we demonstrate that the variable region of ACPA-IgG differs from that of ACPA-IgM by the introduction of glycans, and that glycans in the constant part of antibodies can be modulated by influences from the micro-environment. This may affect the biological functions of the antibodies. Furthermore, we show that ACPA can bind to so-called Fc gamma receptor I on immune cells which could be a potential effector mechanisms of ACPA. These findings demonstrate that the structure and environment of ACPA play an important role in the ACPA immune response and provide multiple arguments for the active contribution of ACPA in the chronic inflammation of RA. Show less
