Bone fragility is a profound complication of type 1 diabetes mellitus (T1DM), increasing patient morbidity. Within the mineralized bone matrix, osteocytes build a mechanosensitive network that... Show moreBone fragility is a profound complication of type 1 diabetes mellitus (T1DM), increasing patient morbidity. Within the mineralized bone matrix, osteocytes build a mechanosensitive network that orchestrates bone remodeling; thus, osteocyte viability is crucial for maintaining bone homeostasis. In human cortical bone specimens from individuals with T1DM, we found signs of accelerated osteocyte apoptosis and local min-eralization of osteocyte lacunae (micropetrosis) compared with samples from age-matched controls. Such morphological changes were seen in the relatively young osteonal bone matrix on the periosteal side, and micropetrosis coincided with microdamage accumulation, implying that T1DM drives local skeletal aging and thereby impairs the biomechanical competence of the bone tissue. The consequent dysfunction of the osteocyte network hampers bone remodeling and decreases bone repair mechanisms, potentially contributing to the enhanced fracture risk seen in individuals with T1DM.Statement of significanceType 1 diabetes mellitus (T1DM) is a chronic autoimmune disease that causes hyperglycemia. In-creased bone fragility is one of the complications associated with T1DM. Our latest study on T1DM-affected human cortical bone identified the viability of osteocytes, the primary bone cells, as a poten-tially critical factor in T1DM-bone disease. We linked T1DM with increased osteocyte apoptosis and local accumulation of mineralized lacunar spaces and microdamage. Such structural changes in bone tissue suggest that T1DM speeds up the adverse effects of aging, leading to the premature death of osteocytes and potentially contributing to diabetes-related bone fragility.(c) 2023 The Author(s). Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ ) Show less
Tuberculosis (TB) is the most prevalent bacterial infectious disease in the world, caused by the pathogen Mycobacterium tuberculosis (Mtb). In this study, we have used Mycobacterium marinum (Mm)... Show moreTuberculosis (TB) is the most prevalent bacterial infectious disease in the world, caused by the pathogen Mycobacterium tuberculosis (Mtb). In this study, we have used Mycobacterium marinum (Mm) infection in zebrafish larvae as an animal model for this disease to study the role of the myeloid differentiation factor 88 (Myd88), the key adapter protein of Toll-like receptors. Previously, Myd88 has been shown to enhance innate immune responses against bacterial infections, and in the present study, we have investigated the effect of Myd88 deficiency on the granuloma morphology and the intracellular distribution of bacteria during Mm infection. Our results show that granulomas formed in the tail fin from myd88 mutant larvae have a more compact structure and contain a reduced number of leukocytes compared to the granulomas observed in wild-type larvae. These morphological differences were associated with an increased bacterial burden in the myd88 mutant. Electron microscopy analysis showed that the majority of Mm in the myd88 mutant are located extracellularly, whereas in the wild type, most bacteria were intracellular. In the myd88 mutant, intracellular bacteria were mainly present in compartments that were not electron-dense, suggesting that these compartments had not undergone fusion with a lysosome. In contrast, approximately half of the intracellular bacteria in wild-type larvae were found in electron-dense compartments. These observations in a zebrafish model for tuberculosis suggest a role for Myd88-dependent signalling in two important phenomena that limit mycobacterial growth in the infected tissue. It reduces the number of leukocytes at the site of infection and the acidification of bacteria-containing compartments inside these cells. Show less
First, we described a method to quantify NETs which has the potential to monitor autoantigen load in the setting of autoimmune diseases where NETs play a role in its pathophysiology. The use of... Show moreFirst, we described a method to quantify NETs which has the potential to monitor autoantigen load in the setting of autoimmune diseases where NETs play a role in its pathophysiology. The use of confocal microscopy with multiple z-stacks, makes it a sensitive method. We provided a context of how NETs can be quantified in SLE and AAV. We demonstrated that not all NETs are created equally and translation of NET formation to a digital quantification creates a narrow view. We showed higher ex vivo NET formation in AAV patients with active disease compared to AAV patients with an underlying infection supporting that excessive NET formation is an autoimmune phenomenon. Also, we demonstrated that the observed excessive NET formation is independent of ANCAs.In the next part of this thesis, we focused on new treatments in lupus nephritis. Most importantly, the results of the Sybiose study are shown; a phase 2 proof-of-concept study that included 15 patients with severe, refractory SLE treated with rituximab and belimumab. We showed that RTX+BLM has the ability to reduce autoantibodies, thereby indirectly reducing excessive NET formation in SLE, presumably due to the targeting of autoreactive B cells. Further, we observed a clinical response in our patients while tapering immunosuppressive medication. Show less
In this thesis the zebrafish tail fin infection model is presented, which enables the study of a complex immune response towards (myco)bacterial infection using a combination of light and electron... Show moreIn this thesis the zebrafish tail fin infection model is presented, which enables the study of a complex immune response towards (myco)bacterial infection using a combination of light and electron microscopy. The induction of autophagy upon a mycobacterial infection as an important innate immune response was visualized using correlative light and electron microscopy. Studying the role of leukocyte dynamics and function during the course of infection provided new insights into the complex host-pathogen interactions. Using a myd88 mutant zebrafish line it was shown that the recruitment of leukocytes towards the site of infection and subsequent phagocytosis of bacteria is dependent on MyD88-mediated signaling. With the advancement of medical translational studies using zebrafish disease models, the tail fin infection model may 104 5 provide new opportunities to develop novel therapies against pathogenic infections like tuberculosis. Show less
Brackeva, B.; Punt, V. de; Kramer, G.; Costa, O.; Verhaeghen, K.; Stange, G.; ... ; Martens, G.A. 2015
The aim of the work included in this PhD thesis was to explore the diverse application possibility of using NIR fluorescent probes with specific properties to visualize and characterize cancer and... Show moreThe aim of the work included in this PhD thesis was to explore the diverse application possibility of using NIR fluorescent probes with specific properties to visualize and characterize cancer and cell death. In this thesis, we mainly focus on optical imaging and its application, both at microscopic and macroscopic level. Because we believe optical imaging in particular represents a technology that has unique potential to exploit further our knowledge in preclinical research. First, we imaged breast tumors and their metastases using combinations of four NIR fluorescent probes that possess different optical imaging properties. Then, we studied two different NIR fluorescent probes, PSVue and a heat shock protein-90 alkylator (NIR fluorescent conjugate of GSAO), which can be used to non-invasively imaging cell death with different optical modules in a mouse model of traumatic brain injury. Next, we employed the NIR fluorescently tagged GSAO as a biomarker for monitoring breast cancer cell death after chemotherapy. Moreover, we provides a general discussion about the advantages and the challenging that the state-of-art optical imaging is facing and shares some future prospective. This thesis ends with a summary that outlined the major findings of studies described in different chapters and explored the clinical implications. Show less
Slingerland, M.; Cerella, C.; Guchelaar, H.J.; Diederich, M.; Gelderblom, H. 2013
Colorectal cancer (CRC) is a complicated disease in which both genetic pre-desposition and environmental factors are important. Patients with inflammatory bowel disease (IBD) have an increased risk... Show moreColorectal cancer (CRC) is a complicated disease in which both genetic pre-desposition and environmental factors are important. Patients with inflammatory bowel disease (IBD) have an increased risk of developing CRC, and it is believed that treatment of IBD patients with 5-Aminosalicylic acid (5-ASA) reduces the CRC risk. The general purpose of the studies described in this thesis was to evaluate the effect of 5-ASA on the development of CRC, as well as determining the feasibility of introducing 5-ASA as an adjuvant therapy for CRC patients. Animal research showed that chronic 5-ASA medication has the ability to prevent colitis-associated CRC, confirming results from 5-ASA medication in IBD patients. Although 5-ASA was not able to prevent the development of sporadic CRC, 5-ASA treatment was found to hold a great promise for the treatment of CRC, by exerting CRC growth inhibiting, anti-progression and cell death inducing effects, and should be considered to be implemented in a future treatment strategy to CRC. Besides this, the determination of cell death products in the circulation of CRC patients and within the tumour, holds a great promise for selection of CRC patient treatment and patient folluw-up. Show less
In this thesis we focus on atherosclerosis as the main cause of cardiovascular disease. Since inflammation and cell death are important processes in the onset and progression of atherosclerosis, we... Show moreIn this thesis we focus on atherosclerosis as the main cause of cardiovascular disease. Since inflammation and cell death are important processes in the onset and progression of atherosclerosis, we investigate the role of several genes involved in inflammation and cell death in the vessel wall and their effect on atherosclerosis. We use several ways to modulate gene expression. Examples from different chapters are whole body deletion of TNF (2), local gene targeting of Fas Ligand to the cap of the plaque (3), conditional gene targeting of mdm2, thereby upregulating p53 (4), and beta-galactosidase (5), and pharmacological targeting of PPARs (6). In this thesis we use various mouse models of atherosclerosis, such as the apoE deficient mouse, the "humanized" apoE3*Leiden mouse and accelerated atherosclerosis induced by collar placement. Show less
