This thesis contains several investigations into the contribution of complement proteins, especially C1q, in several human diseases. Additionally, human autoantibodies against C1q (anti-C1q) are... Show moreThis thesis contains several investigations into the contribution of complement proteins, especially C1q, in several human diseases. Additionally, human autoantibodies against C1q (anti-C1q) are studied, cloned and characterized in order to further the understanding of their role in autoimmune disease. Show less
Acute cardiovascular syndromes, including myocardial infarction or stroke, are the principal cause of death in the Western society. The main underlying pathology of cardiovascular diseases is... Show moreAcute cardiovascular syndromes, including myocardial infarction or stroke, are the principal cause of death in the Western society. The main underlying pathology of cardiovascular diseases is atherosclerosis, which is caused by the accumulation of lipids and inflammatory cells in the vessel wall, in so-called atherosclerotic plaques. Current therapies mainly target the disturbed lipid homeostasis, but recent clinical trials have shown a clear benefit in treating patients with anti-inflammatory drugs. However, more specific targeting is required to avoid unwanted side effects. In this thesis, we have generated a detailed atlas of all the cells present in human atherosclerotic plaques using a novel state-of-the-art technique called single-cell RNA sequencing. This data set can be applied as a powerful tool to select potential drug targets with a functional relevance for atherosclerosis. We showed that the majority of the immune cells in the human atherosclerotic plaque consisted of T cells. Subsequently, we identified a pro-inflammatory population of T cells that likely responds to a plaque-derived antigen, suggesting that atherosclerosis has an autoimmune-like component. Finally, we have applied our single-cell atlas to define and validate targets to intervene with the recruitment and activation of mast cells and other immune cells in atherosclerosis. Show less
This work has described synthetic strategies towards well-defined structures resembling capsular polysaccharide (CPS) fragments, CPS mimics, teichoic acid (TA) fragments as well as a third... Show moreThis work has described synthetic strategies towards well-defined structures resembling capsular polysaccharide (CPS) fragments, CPS mimics, teichoic acid (TA) fragments as well as a third-generation ring-closing tandem metathesis (RCM) linker to better exploit the potential of automated synthesis. The synthesis of diheteroglycan (DHG) fragments of the Gram-positive Enterococcus faecalis have been described and preliminary biological properties shown. CPS-mimics of Neisseria meningitidis A, a Gram-negative bacterium and one of the major causes of bacterial meningitis, could provide an alternative to the inherent instability of current glycoconjugate vaccines. TA fragments presented in this thesis, typical for Gram-positive bacteria, have been equipped with labile D-alanine appendages to further investigate their biological relevance in interactions with the host immune system. A tandem-RCM linker has been developed and tested on a carbohydrate automated synthesizer, providing a proof of concept of its use. Show less
Kidney transplantation is the best treatment option for patients with kidney failure. Unfortunately many patients lose their allograft due to (chronic) rejection. Rejection is caused by the immune... Show moreKidney transplantation is the best treatment option for patients with kidney failure. Unfortunately many patients lose their allograft due to (chronic) rejection. Rejection is caused by the immune reaction of the recipient against the donor’s human leukocyte antigens (HLA). While traditional kidney allocation is based on HLA matching on the antigen level, matching on the epitope level could be more feasible. Furthermore, epitope mismatch analysis could be used for post-transplant risk stratification, enabling the personalisation of immunosuppressive treatment for kidney transplant recipients. In this thesis, the basic science and clinical application of HLA epitopes in kidney transplantation are discussed. Show less
Colorectal cancer is one of the most diagnosed cancer types worldwide and incidence remains on the rise, especially in patients under 50. The prognosis for patients with CRC differs greatly and... Show moreColorectal cancer is one of the most diagnosed cancer types worldwide and incidence remains on the rise, especially in patients under 50. The prognosis for patients with CRC differs greatly and although immunotherapy has shown promising results in a number of cancer types, not all CRC patients respond well to these treatments. This can in part be attributed to the differences in T cell infiltration between cancers but does not one on one translate to clinical response. Moreover, the activity of specific immune cells can directly influence other immune cells, both in an activating and inhibitory manner. This highlights the complexity of the tumour immune microenvironment and requires an comprehensive multiplex approach to simultaneously investigate all the players of the tumour immune microenvironment. Furthermore, the interaction between different immune cells and between those and cancer cells is essential to take into account, hence the need for an approach that combines multiplex immunophenotyping with spatial cell context. This will provide hints into the behaviour of the players of the tumour immune microenvironment and aid the understanding of CRC, but potentially of other cancer types as well. In this work we developed and applied multispectral immunophenotyping methodologies to strengthen our understanding of CRC Show less
Skin-penetrating parasites have something in common; they all need to evade the initial immune response in the skin in order to avoid being evicted by their hostile host and establish an infection.... Show moreSkin-penetrating parasites have something in common; they all need to evade the initial immune response in the skin in order to avoid being evicted by their hostile host and establish an infection. To do so, they are equipped with the necessary cunning stratagems. For example, they can act directly on immune cells to alter their function and they can optimize their migration patterns to their hostile environment. This thesis is aimed at unravelling those mechanisms. We study two devastating parasitic diseases: Malaria and Schistosomiasis. Both deadly and debilitating parasitic diseases, with over 200 million (malaria) and over 240 million (schistosomiasis) cases annually; the need for potent vaccines is evident. Whole weakened parasites can be used to vaccinate individuals against parasitic diseases like malaria. However, delivery of these parasites in the skin, as is commonly done in vaccinations, reduces their protectivity. We hypothesize that this reduction is caused by parasite-mediated immune-regulatory mechanisms that are initiated upon their first encounter with immune cells in the skin. We investigated whether skin penetrating parasites exploit these existing mechanisms in human skin in order to enhance their survival. Show less
This dissertation covered several relevant cycles of placebo research with the main aim to optimize placebo effects in medical contexts. Firstly, a literature review described how the immune system... Show moreThis dissertation covered several relevant cycles of placebo research with the main aim to optimize placebo effects in medical contexts. Firstly, a literature review described how the immune system can be impacted by placebo effects and their underlying learning theories. In the following chapter, these learning theories were integrated to form an optimal research design by means of pharmacological conditioning to fit a specific patient group: children with juvenile idiopathic arthritis. Secondly, this dissertation focused on developing placebo information strategies to harness placebo beliefs and educate persons about the relevancy of placebo effects in practice. These insights are valuable because treatment expectations can have a positive or negative effect on treatment outcomes. Finally, insights from placebo learning theories and placebo information strategies were combined in an integrative experimental research design. This research design employed a more ethical form of placebo use because participants were made aware of placebos, called open-label placebos. In this last study we demonstrated that open-label placebo analgesia can be induced by combining learning theories and placebo information strategies. Altogether, this dissertation provided insights in learning mechanisms, communication strategies, and research paradigms that involve the optimization of placebo effects in medical context. Show less
This thesis contains a variety of information about the natural and vaccine induced immunity against the human papillomavirus. The spontaneously induced HPV-specific humoral response after... Show moreThis thesis contains a variety of information about the natural and vaccine induced immunity against the human papillomavirus. The spontaneously induced HPV-specific humoral response after infection was assessed in population-based studies. The vaccine-induced changes in HPV-seroprevalence among the HPV unvaccinated Dutch population aged 0-89 years, where we compared the HPV-seroprevalence before the introduction of the HPV vaccine with data of approximately six years post-implementation of the national HPV vaccination program. Also, the HPV immune status of the Dutch Caribbean population just after introduction of HPV vaccination was determined. Moreover, the longitudinal relation between the hr-HPV antibody levels and the prevalence of HPV infections in three-dose vaccinated girls were studied. And more insight was gained into humoral and cellular immune responses after just a one-dose of the HPV vaccine. At last, the kinetics of innate and adaptive immune responses directly after vaccination different HPV vaccines were investigated. In the coming years some important changes are expected regarding HPV screening and vaccination. The effectiveness of the one-dose schedule will become clear as clinical trials end. In the Netherlands, a sex-neutral vaccination will be implemented soon. These changes will need to be monitored to provide scientific answers about the effectiveness and immunogenicity. Show less
Pregnancy can be seen as an immunologic paradox. Even though the fetus expresses paternally inherited alloantigens it is protected from rejection by a proper regulation of the maternal immune... Show morePregnancy can be seen as an immunologic paradox. Even though the fetus expresses paternally inherited alloantigens it is protected from rejection by a proper regulation of the maternal immune system. With the studies described in this thesis, we want to get more insight in the immunologic mechanisms that play a role in pregnancy. The results of this research can help to identify underlying etiologies in patients with unexplained pregnancy complications, such as recurrent miscarriage. Identifying these causes is important for providing answers and taking away anxiety in these couples, and eventually for the development of effective therapies. Furthermore, elucidating the mechanism leading to survival or rejection of the fetal allograft is not only essential for our understanding of processes leading to normal and abnormal pregnancies, but may also result in important concepts in the field of transplantation and autoimmunity. Show less
Atherosclerosis is the most important underlying process that drives cardiovascular disease, and is characterized by an accumulation of cholesterol which triggers an inflammatory response in the... Show moreAtherosclerosis is the most important underlying process that drives cardiovascular disease, and is characterized by an accumulation of cholesterol which triggers an inflammatory response in the vessel wall. This results in the recruitment of many types of inflammatory cells towards the plaques that form in the vessel wall, among which are CD8+ T-cells. In this thesis, the role of CD8+ T-cells in the advanced stages of lesion development has been investigated, as this is the most clinically relevant stage of the disease. This thesis demonstrates that CD8+ T-cells exert a protective function. We show that the absence of CD8+ T-cells in a mouse model results in less stable atherosclerotic lesions with increased numbers of inflammatory cells. In a subsequent study, we show that CD8+ T-cells express an enzyme that inhibits the inflammatory process. We also show that injecting a specific subset of CD8+ T-cells is protective against the development of atherosclerotic lesions in mice. Importantly, we show that this data can be translated to atherosclerosis development in humans, as we demonstrate similar results using patient material obtained from endarterectomy surgery. Finally, we show that developing therapies directed towards activating CD8+ T-cells may be of value to inhibit the immune response, and thus reduce the risk of cardiovascular disease. Show less
During pregnancy a unique situation arises in which the mother's immune system accepts the fetus, which carries both maternal and paternal genes, and does not reject it as can occur in solid organ... Show moreDuring pregnancy a unique situation arises in which the mother's immune system accepts the fetus, which carries both maternal and paternal genes, and does not reject it as can occur in solid organ transplantation. The aim of this dissertation was to unravel the immunological mechanisms that ensure tolerance during a healthy pregnancy and uncover how alterations could contribute to the development of pregnancy complications, such as pre-eclampsia and preterm birth.We applied the new technique mass cytometry and the associated computational analyzes to map all immune cells of the mother during a healthy pregnancy. Furthermore, we demonstrated the presence of three types of functional regulatory CD4+ T cells, identified a phenotype of CD8+ T cells that can offer both tolerance and immunity against infections, and demonstrated potential cross-reactivity of T cells against fetal allo-antigens. The results described in this thesis have contributed to a better understanding of healthy pregnancies and form a basis on which further research can be built. Show less
In the clinic, several forms of immunotherapy are combined with the standard treatments, including chemotherapy. Translational studies trying to understand the different outcomes in patients have... Show moreIn the clinic, several forms of immunotherapy are combined with the standard treatments, including chemotherapy. Translational studies trying to understand the different outcomes in patients have led to new questions and hypotheses. The studies described in this thesis are to answer some of these questions. We revealed the immunostimulatory effect of the chemotherapy agent; cisplatin. Next, we studied the mechanism of relapse following immunotherapy with HPV16 SLP vaccination in mice. We demonstrated that unsuccessful immunotherapy results in immune editing and secondary resistance. To overcome this, the combination therapies are required. Moreover, we showed the importance of IL-6 producing by tumors in dampening anti-tumor response. To induce a long-term sustained effector T cell response, we examined the potency of mouse cytomegalovirus as a viral vector-based vaccine. We demonstrated that the demarcated thresholds of vaccine-specific T cells correlate to tumor protection. Recognizing the fact that at each phase of the antitumor immune response a different type of help might have to be provided to obtain maximal therapeutic efficacy, the correct timing of various types of chemotherapeutic agents or immune modulators when used in combination is discussed. Finally, we discussed the general aspects and relevance of the studies mentioned in this thesis. Show less
Antibiotic resistance is an increasing problem in the battle against (bacterial) infectious diseases. The emergence of drug-resistant Mycobacterium tuberculosis (Mtb) threatens to render... Show moreAntibiotic resistance is an increasing problem in the battle against (bacterial) infectious diseases. The emergence of drug-resistant Mycobacterium tuberculosis (Mtb) threatens to render tuberculosis (TB) untreatable. Efforts to develop novel antibiotics have so far been unsuccessful, calling for additional approaches for treatment of bacterial infections. Intracellular pathogens like Mtb and Salmonella can survive in the host by manipulating host cell signaling. This provides opportunities for novel therapeutic strategies by targeting the host, rather than the bacterium (host-directed therapy). In this thesis we report the development and application of novel (in vitro and in vivo) methods for identifying host genes and proteins involved in host control of intracellular bacteria, as well as chemical compounds that target host molecules as a basis for drug development for host-directed therapies. As a result, we report the identification of RTK inhibitors, the novel kinase inhibitor 97i, the human kinase family PCTAIRE and the host protein DRAM1 as promising leads for further drug development for host-directed therapeutic strategies for intracellular bacterial infections. Show less
In normal pregnancy the fetus, although a semi-allograft, is tolerated by the maternal immune system. It has been suggested that an inadequate maternal allo-immune response to the paternal... Show moreIn normal pregnancy the fetus, although a semi-allograft, is tolerated by the maternal immune system. It has been suggested that an inadequate maternal allo-immune response to the paternal antigens of the fetus is responsible for a proportion of the unexplained recurrent miscarriage. In chapter 2 we provide an overview on the possible role of the HLA system in recurrent miscarriage. No consistent conclusions can be drawn since the observed odd ratios found were relatively small and the risk of bias in the selected studies was high. In chapter 3 we compared the genetic polymorphisms of HLA-G in women with recurrent miscarriage with women with uneventful pregnancy. The HLA-G UTR-4 haplotype was less frequently observed in women with recurrent miscarriage, suggesting an immunoregulatory role of this haplotype. The combined results from chapter 4, chapter 6 and chapter 7 suggest that in a portion of women with unexplained recurrent miscarriage antibody-mediated rejection of the fetal allograft may play a role. We showed in chapter 8 that human seminal plasma contains all kinds of immunoregulatory factors and has an immunomodulatory effect on T cells. In chapter 9 a matched case-control study practicing oral sex was negatively associated with the occurrence of recurrent miscarriage. Show less
In this thesis, new insights in the complex and intertwined relationship between viral infections, T cells and natural killer cells after allogeneic HSCT in children are provided and discussed.... Show moreIn this thesis, new insights in the complex and intertwined relationship between viral infections, T cells and natural killer cells after allogeneic HSCT in children are provided and discussed. Patients are at high risk of viral complication during the T cell deficient period early after HSCT. When viral infections occur, interventions to bridge the period until the recovery of antiviral T cell immunity are of great importance to improve the clinical outcome after HSCT. Besides antiviral medication and the use of adoptive immunotherapy, NK cells may play a role in the protection against viruses when T cells are not available to perform their task. Show less
In dit proefschrift hebben wij de invloed van mestcellen in dierexperimentele modellen voor reumatoïde artritis en aderverkalking bestudeerd met een focus op de rol van mestcellen in de (sub)... Show moreIn dit proefschrift hebben wij de invloed van mestcellen in dierexperimentele modellen voor reumatoïde artritis en aderverkalking bestudeerd met een focus op de rol van mestcellen in de (sub)-klinische fases van het ziekteproces, waarin er een actieve immuunrespons ontwikkeld was. Ook hebben wij de aanwezigheid van verschillende soorten antistoffen in het serum van cardiovasculaire patiënten onderzocht. Wij hebben de niveaus van antilichamen gecorreleerd aan klinische observaties zoals body mass index (BMI), lipidenprofiel, klinische diagnose van vaatlijden, samenstelling van de atherosclerotische plaque en de uitkomst van de ziekte. Show less
LCH lesions are characterized by accumulating LCH-cells, which are related to Langerhans and/or Dendritic cells, and the presence of other elements of the immune system. A significant proportion of... Show moreLCH lesions are characterized by accumulating LCH-cells, which are related to Langerhans and/or Dendritic cells, and the presence of other elements of the immune system. A significant proportion of LCH-cells display somatic mutations in proteins that drive the constitutive activation of the MAPK-pathway. Outcome is heterogeneous and unpredictable. The main goal of this thesis was to gain insight to the pathogenesis of Langerhans Cell Histiocytosis (LCH) by studying the genetic and immunologic ‘finger-prints’ of therapy-naive LCH lesions. We found a few biomarkers that could predict the outcome of LCH. These include the expression of a chemokine receptor, CXCR4, on LCH-cells and the degree of lymphoid aggregation within the LCH lesions. We found an ever functionally intact IFN-γ-signalling loop in LCH patients and the presence of activated and regulatory T-cells. However, neither an activated or immunosuppressive environment in LCH lesions was associated with a particular LCH manifestation form or outcome. We found another MAPK-pathway activating mutation in LCH-cells which was sensitive towards the FDA approved BRAF-inhibitor vemurafenib. The research described in this thesis support the concept that LCH lesions should be seen as a ‘cocktail’ of genetically aberrant LCH-cells which accumulate at sites with a mixed immunological background. Show less
The worldwide resurgence of whooping cough (pertussis), even in highly vaccinated populations, demands improved pertussis vaccines. In this thesis a systems vaccinology approach is applied to... Show moreThe worldwide resurgence of whooping cough (pertussis), even in highly vaccinated populations, demands improved pertussis vaccines. In this thesis a systems vaccinology approach is applied to deepen knowledge of the immune responses evoked by different pertussis vaccines and compare this with a Bordetella pertussis infection since the latter induces robust protection. Infection-induced responses in mice conferred sterilizing protection that is caused by systemic immunity but more importantly by mucosal IgA, T-helper (Th)1/Th17 responses, and ‘trained’ innate immune cells in the lungs. An experimental outer membrane vesicle vaccine (omvPV) was compared with the two licensed vaccines, acellular vaccine (aPV), whole-cell vaccine (wPV) as well as a B. pertussis infection. OmvPV evoked a different immunoproteomic profile with respect to antibody levels, antigen specificity, and subclass distribution. Furthermore, omvPV confers equal protection in mice as wPV, but with a lower inflammatory response. In this thesis it is also shown that the immunization route is critical. Although subcutaneous omvPV immunization is effective, pulmonary administration lead to superior protection, comparable to infection-induced immunity and included hallmarks of protection such as pulmonary Th17 cells and mucosal IgA. The molecular and cellular signatures described in this thesis may have an important contribution to enhanced pertussis immunity. Show less
The human herpesvirus Epstein-Barr virus (EBV) is a large DNA virus that infects over 90% of the adult world population. EBV is the causative agent of infectious mononucleosis and EBV infection is... Show moreThe human herpesvirus Epstein-Barr virus (EBV) is a large DNA virus that infects over 90% of the adult world population. EBV is the causative agent of infectious mononucleosis and EBV infection is associated with various malignancies. EBV establishes lifelong infections in immunocompetent hosts. To counteract the host’s immune defence, EBV acquired numerous immune evasion mechanisms. During latency of EBV, viral protein synthesis is limited or absent, making the virus-infected cells virtually invisible to the immune system. Evasion mechanisms of EBV active during primary infection as well as in reactivation are necessary for establishment of latent infection and prolonged replication. Studying viral evasion not only helps to understand EBV, but also the human immune system. Viral molecules interfering with antigen presentation by HLA I and HLA II have been identified previously, but so far, it was unclear how EBV interferes with the lipid antigen-presenting molecule CD1d. The work described in this thesis shows EBV’s mechanism to interfere with cell surface expression of CD1d. Further, a novel immune evasion molecule that obstructs antigen-presentation during the late lytic phase of EBV infection was identified and its working mechanism was unravelled. Understanding viral immune evasion mechanisms may aid in developing therapies for EBV-associated diseases. Show less
