The parasitic helminth Schistosoma mansoni is a potent inducer of type 2 immune responses by stimulating dendritic cells (DCs) to prime T helper 2 (Th2) responses. We previously found that S. mansoniShow moreThe parasitic helminth Schistosoma mansoni is a potent inducer of type 2 immune responses by stimulating dendritic cells (DCs) to prime T helper 2 (Th2) responses. We previously found that S. mansoni soluble egg antigens (SEA) promote the synthesis of Prostaglandin E2 (PGE2) by DCs through ERK-dependent signaling via Dectin-1 and Dectin-2 that subsequently induces OX40L expression, licensing them for Th2 priming, yet the ligands present in SEA involved in driving this response and whether specific targeting of PGE2 synthesis by DCs could affect Th2 polarization are unknown. We here show that the ability of SEA to bind Dectin-2 and drive ERK phosphorylation, PGE2 synthesis, OX40L expression, and Th2 polarization is impaired upon cleavage of high-mannose glycans by Endoglycosidase H treatment. This identifies high-mannose glycans present on glycoproteins in SEA as important drivers of this signaling axis. Moreover, we find that OX40L expression and Th2 induction are abrogated when microsomal prostaglandin E synthase-1 (mPGES) is selectively inhibited, but not when a general COX-1/2 inhibitor is used. This shows that the de novo synthesis of PGE2 is vital for the Th2 priming function of SEA-stimulated DCs as well as points to the potential existence of other COX-dependent lipid mediators that antagonize PGE2-driven Th2 polarization. Lastly, specific PGE2 inhibition following immunization with S. mansoni eggs dampened the egg-specific Th cell response. In summary, our findings provide new insights in the molecular mechanisms underpinning Th2 induction by S. mansoni and identify druggable targets for potential control of helminth driven-Th2 responses. Show less
In this thesis, several aspects and cellular players involved in the immune response to (HPV-induced) tumors were investigated. In chapter 2 a detailed analysis of HPV-specific immunity in a large... Show moreIn this thesis, several aspects and cellular players involved in the immune response to (HPV-induced) tumors were investigated. In chapter 2 a detailed analysis of HPV-specific immunity in a large group of patients with HPV-induced cervical cancer (CxCa) in relation to HLA-types and prognostic factors was performed. In 30% of the tested patients, circulating HPV specific T cells were found, most often in patients with deeply infiltrating tumors. In this group, patients with HPV specific proliferative immunity displayed better disease free survival. It was shown earlier by Piersma et al [69] that only in 30% of TIL populations, HPV specific T cells were found. In chapter 3 an in depth analysis of the breadth and type of HPV specific T-cell populations in tumor infiltrating T cell (TIL) cultures or LN cells from HPV 16 or 18 positive CxCa patients was performed. We found that if patients displayed a HPV-specific T cell response, this was surprisingly broad. Despite recognition, a number of cells did not produce type 1 cytokines and therefore we tested what TLR-agonist was able to support cytokine induction by these T cells. In chapter 4 we asked the question whether HPV-specific T cells play a role in HPV-induced HNSCC. We hypothesize that HPV-induced tumors are more immunogenic and stimulate strong T-cell reactivity to the viral oncoproteins in contrast to HPV-negative tumors. We set up a pilot study to investigate whether HPV is present in HNSCC in the Dutch patient population and at which anatomical site. Accordingly, blood and tumor infiltrating T cells were analyzed for the presence of functional HPV specific T cells. The lack of T cell responses in CxCa patients and the __poised__ function of tumor-antigen specific T cells could be a lack of proper priming by DC. Therefore we investigated in chapter 5A the effects of CxCa produced soluble factors on the differentiation of antigen presenting cells (APC). Several tumor cell lines hampered DC differentiation or even skewed monocyte differentiation into tolerogenic tumor promoting M2 macrophages. We identified the factors responsible for this and investigated the outcome of the interaction of HPV specific T-cell clones with these macrophages. Since patients with advanced or recurrent disease are treated with platinum based chemotherapy we investigated the immune-modulating effect of this therapy on tumor cells, tumor-modulated APC and subsequent interaction with T cells. This ongoing work is summarized in chapter 5B. Therapeutic vaccination is being developed for treatment of chronic infections and cancer, and aims to generate protective T-cell immunity. Although some clinical successes have been reported, particularly in the field of cancer vaccination, there is still much to be gained in terms of efficacy [91,92]. Especially the adjuvant used and the route of administration of vaccines are critical factors that determine the type and memory of the resulting T-cell response. Intradermal vaccination is an attractive method for diseases in the skin such as HPV induced tumors and melanomas since the induced T cells get skin-homing instructions. In chapter 5 we showed already that highly pure DC can become activated by the addition of several different TLR agonists in vitro. To assess the effect of these TLR agonists on the APC present in the dermis, a human skin-explant model was used to analyze the phenotype and function of the APC migrating out the skin upon TLR-injection. These results are described in chapter 6. Surprisingly, only few TLR-agonists turned out to induce activation of the migrating cells. The current treatment of patients with advanced colorectal cancer consists of chemotherapy together with the MAb bevacizumab that blocks soluble VEGF. The addition of a second antibody that targets tumor expressed EGFR (cetuximab) to this treatment did not result in the expected disease free survival benefit in a large randomized phase III study (CAIROII). Analysis of gene polymorphisms in the Fc__Receptors revealed that patients with the high affinity FCGR3A polymorphism did significantly worse upon addition of cetuximab to the standard treatment. As colon cancers are generally infiltrated with macrophages we tested the hypothesis that membrane bound antibodies could activate tumor promoting M2 macrophages and that this would happen more efficiently in patients with high affinity FCGRIIIA in chapter 7. In chapter 8 the work of this thesis is discussed in light of recent literature. Show less
The main objective of the research described in this thesis is to demonstrate the relevance of biomarkers on the selection of the dose range of COX inhibitors for effective analgesic and anti... Show moreThe main objective of the research described in this thesis is to demonstrate the relevance of biomarkers on the selection of the dose range of COX inhibitors for effective analgesic and anti-inflammatory response, as opposed to the focus on behavioural measures of pain and inflammation advocated by the current paradigm for the development of non-steroidal anti-inflammatory drugs (NSAIDs). To this end, the relationship between drug concentration and the corresponding inhibition of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) was investigated for a range of COX inhibitors with varying degrees of selectivity, and hence with differential effects on the selected biomarkers. Thanks to the use of a mechanism-based approach, attention is also given to translational pharmacology in drug development. We evaluate whether 1) estimates of drug action in vitro are predictive of the effect in vivo, 2) animal data in vivo reflect drug effect on biomarkers in humans and 3) whether inflammatory conditions modify the extent of drug effect as compared to healthy conditions. A recommendation and guideline for best practices in the development of COX inhibitors is anticipated from this analysis. Show less
