Nowadays, therapeutic antibodies are the major and fastest growing class of biotherapeuticals. Since their invention, they are continuously developed to improve structural and functional... Show moreNowadays, therapeutic antibodies are the major and fastest growing class of biotherapeuticals. Since their invention, they are continuously developed to improve structural and functional characteristics. The high complexity of recently generated antibody derivatives, with various modifications induced during the manufacturing process itself leads to many proteoform variants of the desired product. These proteoforms can potentially exhibit altered activity. Therefore, an adequate characterization of the proteoforms, the assessment of their impact and careful monitoring of critical species is indispensable in order to guarantee effective and safe biopharmaceuticals. As the landscape of next-generation Ab formats continuously evolves, it is likewise of great importance to further develop appropriate analytical methods for their thorough attribute analysis. Hence, the focus of the research performed in this thesis is the development of multi-level approaches for the in-depth, primarily MS-based characterization of biopharmaceuticals to overcome the present restrictions and challenges arising e.g. by the implementation of complex Ab formats. Show less
Saint Lary, C.D. de; Kasbergen, L.M.R.; Bruijning-Verhagen, P.C.J.L.; Jeugd, H. van der; Chandler, F.; Hogema, B.M.; ... ; Visser, L.G. 2023
IntroductionIn 2020, the first Dutch West Nile virus (WNV) infected birds were detected through risk-targeted surveillance of songbirds. Retrospective testing of patients with unexplained... Show moreIntroductionIn 2020, the first Dutch West Nile virus (WNV) infected birds were detected through risk-targeted surveillance of songbirds. Retrospective testing of patients with unexplained neurological disease revealed human WNV infections in July and August 2020. Bird ringers are highly exposed to mosquito bites and possibly avian excrements during ringing activities. This study therefore investigates whether bird ringers are at higher risk of exposure to WNV and Usutu virus (USUV).MethodsDutch bird ringers were asked to provide a single serum sample (May – September 2021) and to fill out a survey. Sera were screened by protein microarray for presence of specific IgG against WNV and USUV non-structural protein 1 (NS1), followed by focus reduction virus neutralization tests (FRNT). Healthcare workers (2009–2010), the national immunity cohort (2016–2017) and blood donors (2021) were used as control groups without this occupational exposure.ResultsThe majority of the 157 participating bird ringers was male (132/157, 84%) and the median age was 62 years. Thirty-seven participants (37/157, 23.6%) showed WNV and USUV IgG microarray signals above background, compared to 6.4% (6/94) in the community cohort and 2.1% (2/96) in blood donors (p < 0.01). Two seroreactive bird ringers were confirmed WNV or USUV positive by FRNT. The majority of seroreactive bird ringers travelled to EU countries with reported WNV human cases (30/37, 81%) (p = 0.07). No difference was observed between bird ringers with and without previous yellow fever vaccination.DiscussionThe higher frequency of WNV and/or USUV IgG reactive bird ringers indicates increased flavivirus exposure compared to the general population, suggesting that individuals with high-exposure professions may be considered to complement existing surveillance systems. However, the complexity of serological interpretation in relation to location-specific exposure (including travel), and antibody cross-reactivity, remain a challenge when performing surveillance of emerging flaviviruses in low-prevalence settings. Show less
This thesis describes studies of individuals with systemic lupus erythematosus (SLE) presenting with neuropsychiatric (NP) symptoms at the Leiden NPSLE clinic. A diverse range of studies, including... Show moreThis thesis describes studies of individuals with systemic lupus erythematosus (SLE) presenting with neuropsychiatric (NP) symptoms at the Leiden NPSLE clinic. A diverse range of studies, including laboratory, radiological, clinical and patient´s reported outcomes are presented.The Leiden NPSLE clinic is a tertiary referral center for patients with SLE and neuropsychiatric (NP) symptoms. In the NPSLE clinic, patients are assessed by a multidisciplinary team. Thereafter, clinical, radiological and laboratory measures are weighed in a consensus meeting to correctly attribute the NP symptoms: related to lupus activity (NPSLE) or not. This extensive and standardized assessment of NPSLE, a rare and heterogenous disease lacking a gold standard, is unique and creates the opportunity to explore many aspects of NPSLE in well-defined phenotypes.In the first part of this thesis, we evaluate both classification and treatment of patients withSLE and NP symptoms. The second part of this thesis focuses on a diverse range of clinicaloutcomes of NPSLE, including both morbidity and mortality. The last part of this thesisassesses potential biomarkers for (specific manifestations of) NPSLE. 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
Using a variety of relevant preclinical mouse models, this thesis not only showed several ways to improve antibody-based cancer immunotherapy but also demonstrates the importance of the choice of... Show moreUsing a variety of relevant preclinical mouse models, this thesis not only showed several ways to improve antibody-based cancer immunotherapy but also demonstrates the importance of the choice of the model for the translational relevance of the preclinical observations. Show less
Introduction: The aim of this narrative review is to provide an overview of the literature on the possible immunologic pathophysiology of psychiatric manifestations of neuropsychiatric systemic... Show moreIntroduction: The aim of this narrative review is to provide an overview of the literature on the possible immunologic pathophysiology of psychiatric manifestations of neuropsychiatric systemic lupus erythematosus (NPSLE).Methods: A systematic search on PubMed was conducted. English studies with full text availability that investigated the correlation between blood-brain barrier (BBB) dysfunction, intrathecal synthesis of antibodies, antibodies, cytokines, chemokines, metalloproteinases, complement and psychiatric NPSLE manifestations in adults were included.Results: Both transient BBB-dysfunction with consequent access of antibodies to the cerebrospinal fluid (CSF) and intrathecal synthesis of antibodies could occur in psychiatric NPSLE. Anti-phospholipid antibodies, anti-NMDA antibodies and anti-ribosomal protein p antibodies seem to mediate concentration dependent neuronal dysfunction. Interferon-a may induce microglial engulfment of neurons, direct neuronal damage and production of cytokines and chemokines in psychiatric NPSLE. Several cytokines, chemokines and matrix metalloproteinase-9 may contribute to the pathophysiology of psychiatric NPSLE by attracting and activating Th1-cells and B-cells.Discussion: This potential pathophysiology may help understand NPSLE and may have implications for the diagnostic management and therapy of psychiatric NPSLE. However, the presented pathophysiological model is based on correlations between potential immunologic etiologies and psychiatric NPSLE that remain questionable. More research on this topic is necessary to further elucidate the pathophysiology of NPSLE. Show less
In this thesis we have analyzed an important number of laboratory, radiological, clinical and patient´s reported outcomes in systemic lupus erythematosus (SLE) patients presenting with... Show moreIn this thesis we have analyzed an important number of laboratory, radiological, clinical and patient´s reported outcomes in systemic lupus erythematosus (SLE) patients presenting with neuropsychiatric (NP) manifestations. Our studies are among the most robust to date in this field due to the large number of patients included, the prospective character and the standard assessment followed by a multidisciplinary expert consensus.Furthermore our studies include the novelty of a phenotypic characterization of all NP manifestations according to the suspected underlying pathophysiological mechanism (inflammation or immune-mediated vs. ischemic or thrombotic). These studies give more light to the understanding of the underlying pathophysiological mechanisms of nervous involvement in SLE. Show less
In this thesis, methods were developed, and antibody glycosylation was characterized in order to further the clinical application of antibody glycosylation analysis. New mass spectrometric... Show moreIn this thesis, methods were developed, and antibody glycosylation was characterized in order to further the clinical application of antibody glycosylation analysis. New mass spectrometric workflows were introduced in Chapters 2 and 8. Chapter 7 showed the differential characteristics of murine IgG glycosylation of different strains and highlighted the profound differences between humans and mice, with regard to IgG glycosylation. Chapters 4 and 8 showed the use of controlled human situations to study the regulatory mechanisms of IgG and IgA glycosylation. Finally, Chapters 3, 5 and 6, identified glycosidic differences with specified (patho)physiological conditions, which might be exploited for patient stratification in the future. Show less
Most lymphomas and leukemias are neo¬plasms of B cells. Due to the many different B cell development stages from which these neoplasms arise, the resulting diseases are quite heterogeneous, which... Show moreMost lymphomas and leukemias are neo¬plasms of B cells. Due to the many different B cell development stages from which these neoplasms arise, the resulting diseases are quite heterogeneous, which amongst other things is manifested in different tumor growth location, proliferation potential and surface antigen repertoire. Neverthe¬less, some population characteristics are found in almost all B cell malignancies as the cell-of-origin is identical. One of these is the cell surface antigen CD20. Originally used as a marker to distinguishing B cells from other lymphocytes, it quickly became a target for immunotherapy. Immuno-therapy is a treatment that makes use of immune system components to fight cancer, in this case by the injection of a monoclonal antibody specifically targeting one protein: CD20. The addition of CD20-targeting an¬tibodies to an anti-tumor treatment allows your immune system to recognize CD20-ex¬pressing B cells (diseased and healthy), and dispose of them. Overall, after several decades of research and therapeutic experience with antibodies targeting CD20, new functional discoveries as well as therapeutic advances are still being made, and CD20 therefore remains a highly attractive and fruitful target for the therapy of B cell malignancies as well as certain B-cell mediated autoimmune diseases. Show less
The aim of this thesis was to develop tools to detect and quantify HLA-specific memory B cells in peripheral blood of HLA-immunized individuals and to assess the applicability of the newly... Show moreThe aim of this thesis was to develop tools to detect and quantify HLA-specific memory B cells in peripheral blood of HLA-immunized individuals and to assess the applicability of the newly developed assays in the setting of clinical transplantation. Transplant patients who have already made a defense response to the foreign HLA on donor organ have an increased risk of developing antibody-mediated rejection, which may adversely affect the survival of the graft. In diagnostic HLA laboratories, serum of the patients is tested for the presence of HLA-specific antibodies before and after transplantation. Serum HLA antibodies are produced by plasma cells located in the bone marrow however, memory B cells can also play a role in antibody production against the donor organ. So far, the role of these cells has been neglected in the diagnostics. The research conducted in my PhD thesis enabled us to develop methods to detect HLA-specific memory B cells. By this means, patients who may potentially harbor HLA-specific memory B cells such as repeat transplant candidates, women receiving transplants from their partner or child and patients undergoing desensitization treatments may benefit from the assays that are described in this PhD thesis. Show less
Therapeutic proteins have become very successful in the treatment of various chronic and life-threatening diseases. However, besides their benefits, therapeutic proteins seem to have a common... Show moreTherapeutic proteins have become very successful in the treatment of various chronic and life-threatening diseases. However, besides their benefits, therapeutic proteins seem to have a common problem - the response of a patient’s immune system against the protein. This means that the immune system of the patient actively removes the drug from the body, thereby potentially decreasing or reversing the effect of the therapy. By now there is strong consensus that damaged and aggregated proteins are important risk factors. Protein aggregates are, due to their heterogeneity and often low quantity, challanging to characterize. Further, there is a large academic interest in understanding the mechanisms of aggregation and the role of non-proteinaceous particles in the process of protein aggregation and unwanted immunogenicity in order to design more effective and safe protein-based medicines. This PhD thesis supported that research effort by developing and improving analytical methodologies to detect the size, quantity and other properties of protein aggregates and particles, especially in the relevant nano- and micrometer size range. These techniques were then applied to study a so far unknown nanoparticulate impurity in pharmaceutical-grade sugars. Further, the results shown in this thesis revealed that these nanoparticulate impurities pose a threat to protein stability. Show less
The work presented in this thesis aimed at increasing our understanding of the effect of helminths on Plasmodium spp. immune response in co-infected individuals living in endemic countries. It... Show moreThe work presented in this thesis aimed at increasing our understanding of the effect of helminths on Plasmodium spp. immune response in co-infected individuals living in endemic countries. It presents data from studies conducted in rural and semi urban areas of Lambaréné (Gabon) where the burden of malaria and helminths is particularly important. Although scarce previous studies have indicated an effect of helminths on malaria outcomes and immune response to Plasmodium spp. parasite in co-infected subjects. However it is still debated how consistent is this effect across study sites and teams and what its immunological basis is. Show less
Immunoglobulin G (IgG) represents the most abundant antibody class in the human circulation. IgG consists of two heavy chains and two light chains. Parts of the heavy chains, together with the... Show moreImmunoglobulin G (IgG) represents the most abundant antibody class in the human circulation. IgG consists of two heavy chains and two light chains. Parts of the heavy chains, together with the light chains, form two fragment antigen binding (Fab) moieties, whilst the remainders of the two heavy chains form the fragment crystallizable (Fc) moiety. Human IgGs are glycosylated at the highly conserved N-glycosylation site asparagine 297 in the CH2 domain of each heavy polypeptide chain of the Fc part. Fully galactosylated N-glycans are positioned between the Fc polypeptide chains, resulting in an open Fc conformation which is required for high affinity binding to Fc_ receptors. Small changes in the Fc glycosylation can already have a profound influence on the interaction of the Fc portion with receptors modulating the anti and pro-inflammatory properties of IgG. Mass spectrometry provides great opportunities for deta iled structural characterization of protein glycosylation including protein identification, determination of site-specific glycosylation profiles, and structural characterization of glycans at the level of released glycans and glycopeptides. In this thesis novel approaches for fast, miniaturized and high-throughput analysis of IgG Fc N-glycosylation are presented, and the utility of these methods has been demonstrated for clinically relevant research questions. Show less
Duquesnoy, R.J.; Marrari, M.; Mulder, A.; Claas, F.H.J.; Mostecki, J.; Balazs, I. 2012
A vaccine against Plasmodium falciparum is needed to augment currently available malaria control tools. A handful of parasite antigens are at various stages of pre-clinical and clinical development... Show moreA vaccine against Plasmodium falciparum is needed to augment currently available malaria control tools. A handful of parasite antigens are at various stages of pre-clinical and clinical development. Amongst these is P. falciparum apical membrane antigen 1 (PfAMA1), an antigen expressed by asexual stage parasites and believed to be important for the parasite__s invasion of both red blood cells and liver cells. The immune response to PfAMA1 is mediated mainly by antibodies that prevent parasite invasion of host cells. PfAMA1 however shows allelic polymorphism, with anti-PfAMA1 antibody responses exhibiting strain-specificity. This thesis investigated multi-allele vaccine formulation strategies that would overcome the strain-specificity of antibody responses to PfAMA1. The main findings of this thesis are that i) different PfAMA1 alleles share epitopes to which functional cross-strain antibodies can be induced, ii) a three-allele PfAMA1 formulation yields the greatest proportion of functional cross-strain antibodies, and iii) three PfAMA1 alleles, irrespective of the adjuvant used for formulation and whether they are administrated as a multi-allele formulation or sequentially, induce similar proportions of cross-strain antibodies. Overall, a multi-allele formulation with three in silico-designed PfAMA1 candidates yields antibodies that inhibit several parasites in vitro and warrant their development as a human blood stage vaccine. Show less
