The aim of this thesis is to investigate the role of chronic inflammation as well as acute inflammatory response on muscle aging. We conclude that high chronic inflammation is associated with low... Show moreThe aim of this thesis is to investigate the role of chronic inflammation as well as acute inflammatory response on muscle aging. We conclude that high chronic inflammation is associated with low muscle strength, while high acute pro-inflammatory response is associated with high muscle strength. Show less
Uveal melanoma is a highly malignant intraocular tumor with quite homogeneous tumor tissue and a diffuse leukocytic infiltration. In contrast with many other malignancies, the presence of... Show moreUveal melanoma is a highly malignant intraocular tumor with quite homogeneous tumor tissue and a diffuse leukocytic infiltration. In contrast with many other malignancies, the presence of infiltrating macrophages and T cells is associated with a poor prognosis rather than a good one. The clear link between inflammation and this malignancy provides a paradigm for macrophage plasticity and function. Macrophages in uveal melanoma have an M2-like phenotype and are associated with the loss of one specific chromosome - monosomy 3. The central players involved in this process and discussed include macrophages, T lymphocytes, chemokines and cytokines, including the macrophage-attraction molecules. When a tumor acquires the ability to release significant amounts of macrophage-attraction molecules it causes the expansion of a population of myeloid immature cells that may not only help the tumor to suppress immune reactions but also aid in the construction of new blood vessels for tumor growth. A better understanding of the molecular basis of a local myelomonocytic cell population will bring a better understanding of the immunopathology of this disease and will lead to therapeutic interventions in uveal melanoma. This thesis focuses on the roles of the local inflammatory microenvironment in the development and progression of uveal melanoma. Show less
Helminth parasites are able to induce immune regulation in their host. Suppression of the host immune system is beneficial for both the parasite, by inhibiting anti-parasite immunity, and for the... Show moreHelminth parasites are able to induce immune regulation in their host. Suppression of the host immune system is beneficial for both the parasite, by inhibiting anti-parasite immunity, and for the host, by preventing tissue damage due to excessive inflammation. There are indications that in countries where parasites have been eliminated the immune regulatory network is impaired, leading to inflammatory diseases such as allergies and asthma. An important player in immune regulation is the regulatory T cell (Treg). We have shown that the number and/or function of Tregs were indeed enhanced in several helminth and also malaria infections in humans. Tregs were not only involved in suppression of anti-parasite responses, but also of responses to other infections or vaccines. We further investigated the effect of helminth elimination in a randomized placebo-controlled trial. Treatment of helminths led to a strong increase in __mainly pro-inflammatory__ immune responses, which confirms the importance of immune regulation during infection. Furthermore, the prevalence of malaria was transiently increased and allergy was slightly on the rise in treated school children. These results further endorse the possible beneficial effects of helminthic therapy, which is currently being tested in a number of clinical trials. Show less
Osteoarthritis (OA) mainly affects the articular cartilage covering the bones. In this thesis we investigated the relation between levels of inflammatory mediators, genes involved in their... Show moreOsteoarthritis (OA) mainly affects the articular cartilage covering the bones. In this thesis we investigated the relation between levels of inflammatory mediators, genes involved in their regulation and the disease status of OA. We investigated the role of genetic variation at the interleukin(IL)-1 gene cluster in the innate bio-availability of IL-1beta. A haplotype that associated to low innate bio-availability also associated to higher hand OA scores. Although this is counterintuitive with respect to the generally accepted hypothesis that a pro-inflammatory status is detrimental to the cartilage it underlines a complex relationship between inflammation and OA. For the C-reactive protein we identified a haplotype associated to high CRP levels as well as to severe hand OA, which is more in line with expected directions of associations. Analysis of baseline cytokine and chemokine levels indicated that chemokine levels associated to hand OA scores, again with low levels associated to high OA scores. In a follow up functional genomic analysis of a previously identified OA susceptibility gene (DIO2) in our studies we show that the risk allele of this gene is transcribed at higher levels as compared to the non-risk allele. Furthermore, we showed increased DIO2 protein presence in OA affected cartilage. Show less
The studies described in this thesis focus on gene therapeutic strategies to target pathological vascular wall remodeling after PT(C)A or bypass surgery. Inflammatory processes and extracellular... Show moreThe studies described in this thesis focus on gene therapeutic strategies to target pathological vascular wall remodeling after PT(C)A or bypass surgery. Inflammatory processes and extracellular proteases, both activated by mechanical and vascular injury caused by these interventions, are thought to contribute largely to the development of post-angioplasty restenosis and vein graft disease. Therefore, viral and non-viral gene therapy techniques were used in these studies to deliver genes encoding protective as well as inhibiting proteins in order to modulate the inflammatory cascade (i.e. IL-10 and the MCP-1/CCR-2 pathway) in the first part of this thesis and the plasminogen activator and MMP-system in the second part. Finally, the expression of several involving genes was blocked locally by RNA interference techniques in the last part of this thesis. The possibilities and effects of these gene therapy applications were studied in cell cultures, in a human saphenous vein organ culture model and in two mouse models of restenosis and vein graft disease. Altogether, these studies provided more insight into the pathophysiology of post-interventional remodeling and several potential therapeutic strategies were assessed. Show less
The aim of this thesis was to gain more insight in the involvement of inflammatory processes in vessel wall remodeling seen after PTA or bypass surgery and put these processes in the perspective of... Show moreThe aim of this thesis was to gain more insight in the involvement of inflammatory processes in vessel wall remodeling seen after PTA or bypass surgery and put these processes in the perspective of restenosis, vein graft failure and potential therapeutic preventive strategies. Therefore, we firstly focused on inflammation in general, using the anti-inflammatory agent Dexamethasone, assessing the effects of such a broad approach on restenosis and vein graft remodeling. Then, we further focused on some specific parts of the immune system, namely Interleukin 10 (IL10), chemokines and the complement cascade. Il10 was chosen because it is one of the most studied anti-inflammatory cytokines and this property makes it a potential candidate for ant-restenosis therapy. Furthermore, it was hypothesized that chemokines are involved in vascular remodeling, since they are generally known for their regulatory properties regarding influx of inflammatory cells to tissues and this is one of the first phenomena seen in vascular remodeling. The complement cascade was studied in this context since it contains pro-inflammatory activity and some end-products of the cascade, like chemokines, are potent chemotactic agents. Show less
In dit promotieonderzoek is zijn de effecten van vetstapeling en ontstekingsreactie tijdens het proces van atherosclerose. We hebben aangetoond dat het ontstekingsremmende eiwit interleukine-9, een... Show moreIn dit promotieonderzoek is zijn de effecten van vetstapeling en ontstekingsreactie tijdens het proces van atherosclerose. We hebben aangetoond dat het ontstekingsremmende eiwit interleukine-9, een stof die door bepaalde immunologische cellen geproduceerd wordt, een remmende werking heeft op het ontstaan van atherosclerose in het algemeen en van vetstapeling in macrofagen in het bijzonder. Aan de andere kant blijkt uit mijn promotieonderzoek dat vetstapeling van macrofagen de gevoeligheid van deze cellen voor ontstekingen beïnvloedt. LPS is in staat om een zeer sterke ontstekingsreactie te stimuleren en om de expressie van verschillende genen die betrokken zijn bij vetstapeling te beïnvloeden. Door gebruik te maken van muizen die geen scavenger receptor BI (SR-BI) tot expressie brengen, hebben we aangetoond dat SR-BI beschermd tegen de door LPS gestimuleerde ontstekingsreactie. Tevens blijkt dat een dieet met een hoog cholesterol gehalte een grote invloed heeft op parenchymcellen in de lever. Voornamelijk FABP5 en vier nieuwe vetzuurbindende eiwitten lijken een belangrijke rol te spelen in de reactie van deze cellen op het dieet. Ook het ontstekingremmende interleukine 10, waarvan bekend is dat het atherosclerose kan remmen en een verlaging van cholesterol in het bloed kan veroorzaken, beïnvloedt vele genen betrokken bij vethuishouding in parenchymcellen van de lever. Show less
