Patients with severe infection have an increased risk of cardiovascular events. A possible underlying mechanism is inflammation-induced platelet aggregation. We investigated whether... Show morePatients with severe infection have an increased risk of cardiovascular events. A possible underlying mechanism is inflammation-induced platelet aggregation. We investigated whether hyperaggregation occurs during infection, and whether aspirin inhibits this. In this multicentre, open-label, randomised controlled trial, patients hospitalised due to acute infection were randomised to receive 10 days of aspirin treatment (80 mg 1dd or 40 mg 2dd) or no intervention (1:1:1 allocation). Measurements were performed during infection (T1; days 1-3), after intervention (T2; day 14) and without infection (T3; day > 90). The primary endpoint was platelet aggregation measured by the Platelet Function Analyzer (R) closure time (CT), and the secondary outcomes were serum and plasma thromboxane B2 (sTxB2 and pTxB2). Fifty-four patients (28 females) were included between January 2018 and December 2020. CT was 18% (95%CI 6;32) higher at T3 compared with T1 in the control group (n = 16), whereas sTxB2 and pTxB2 did not differ. Aspirin prolonged CT with 100% (95%CI 77; 127) from T1 to T2 in the intervention group (n = 38), while it increased with only 12% (95%CI 1;25) in controls. sTxB2 decreased with 95% (95%CI - 97; - 92) from T1 to T2, while it increased in the control group. pTxB2 was not affected compared with controls. Platelet aggregation is increased during severe infection, and this can be inhibited by aspirin. Optimisation of the treatment regimen may further diminish the persisting pTxB2 levels that point towards remaining platelet activity. This trial was registered on 13 April 2017 at EudraCT (2016-004303-32). Show less
Antimicrobial drugs constitute a fundamental part of modern medicine. The global rise in antimicrobial resistance poses a major threat to global health. Optimising antimicrobial treatment... Show moreAntimicrobial drugs constitute a fundamental part of modern medicine. The global rise in antimicrobial resistance poses a major threat to global health. Optimising antimicrobial treatment strategies in patients offers an important direction to address this challenge. In this thesis, we describe how quantitative characterisation of the drug, the pathogen, and the patients, and how these three factors interact, can help to achieve this goal. To this end, we used a combination of state-of-the-art in silico model-based approaches to analyse and integrate experimental data from in vitro models, and clinical data from healthy volunteers and patients. We developed models describing infection site drug exposure, antimicrobial resistance evolution, and host response biomarker dynamics. We explored the impact of infection on pulmonary pharmacokinetics, evolutionary-based treatment strategies, and the utility host response biomarker for treatment monitoring. The work in this thesis builds towards developing novel strategies to optimise antimicrobial treatments and showcases the importance on interdisciplinary collaborations. Show less
The research described in this thesis has, using the zebrafish as a model system, shed new light on the intricate relationship between TB and DM2, in particular on the role of leptin, SHP-1 and... Show moreThe research described in this thesis has, using the zebrafish as a model system, shed new light on the intricate relationship between TB and DM2, in particular on the role of leptin, SHP-1 and glucocorticoids.Leptin plays an important role during TB infection and has a huge impact on insulin sensitivity in zebrafish larvae. Similarly to what has been observed in the murine model, leptin deficiency in zebrafish increased the bacterial burden and mortality during the infection, leading to hyperglycemia and the development of insulin resistance. In addition, a novel SHP-1/SHP-2 inhibitor, NSC-87877, was shown to represent a promising anti-diabetic drug that can be used for further DM2 research, as it is able to rescue the phenotype of the leptin-deficient zebrafish and to restore glucose transport to the tissues. In contrast to metformin, NSC-87877 can act at very early developmental stages and inhibits the function of SHP-1 and factors that underlay impaired glucose metabolism, whereas metformin is mostly known to improve insulin sensitivity. Additionally, treatment with the glucocorticoid beclomethasone attenuates the metabolic changes associated with the infection, and transcriptional alterations induced by beclomethasone treatment suggest that genes involved in glucose metabolism, insulin and leptin signaling all play an important role in the modulation of the metabolism.Our data show that zebrafish larvae represent an interesting model system to investigate the complex pathology of TB, and the studies described in this thesis in which this model has been used have provided novel insights into the molecular mechanisms underlying wasting syndrome and the possibilities for adjunctive glucocorticoid therapy to alleviate this metabolic state. Show less
Upon infection or vaccination, naïve CD8+ T cells clonally expand and differentiate into antigen-specific effector cell populations, which turn into phenotypically diverse memory CD8+ T cell... Show moreUpon infection or vaccination, naïve CD8+ T cells clonally expand and differentiate into antigen-specific effector cell populations, which turn into phenotypically diverse memory CD8+ T cell subsets that differ in their cytokine polyfunctionality, cytolytic capacity and homing properties. The circulating memory CD8+ T cell pool can be largely classified in two major subsets: effector memory T (TEM) and central memory T (TCM) cells. Contrary to the classical view that lymphocytes continuously recirculate, tissue-resident memory T (TRM) cells have been discovered as cells with the unique ability to reside in tissues with limited recirculation through the blood. Antigen-specific CD8+ TRM cells are induced upon antigen encounter and localize to many different tissues, including barrier tissues, where they play a crucial role in protection against infectious and malignant disease. Within these major circulating and resident T cell subsets a variety of phenotypes and functions exists. However, the development of the heterogeneous populations of memory T cells is not fully understood. In this thesis we dissect the development and heterogeneity of antigen-specific circulating and tissue-resident CD8+ T cells upon vaccination and infection, study their protective capacity in infectious and malignant disease and use this information to improve vaccination and immunotherapeutic strategies. Show less
Background: Evidence indicates that inflammatory processes are involved in radicular pain as well as in resorption of herniated disc tissue. Furthermore there are indications that the presence of... Show moreBackground: Evidence indicates that inflammatory processes are involved in radicular pain as well as in resorption of herniated disc tissue. Furthermore there are indications that the presence of vertebral end plate pathology (Modic changes; MC) is associated with a negative effect on inflammation. It is hypothesized that in patients with MC, the (possibly bacterial induced) inflammation will be accompanied by pro inflammatory cytokines that worsen the outcome, and that in patients without MC, the inflammation is accompanied by cytokines that induce a resorption process to accelerate recovery.Methods: This prospective cohort study will include 160 lumbar and 160 cervical patients (total of 320), which are scheduled for surgery for either a lumbar or cervical herniated disc with ages between 18 and 75. The main and interaction effects of local bacterial infection (culture), inflammatory cells in disc material (immunohistology), MC (MRI), and blood biomarkers indicating inflammation or infection (blood sample evaluation) will be evaluated. Clinical parameters to be evaluated are leg pain on the 11 point NRS pain scale, Oswestry (lumbar spine) or Neck (cervical spine) Disability Index, Global Perceived Recovery, Womac Questionnaire, and medication status, at baseline, and after 6, 16, 26 and 52 weeks.Discussion: Gaining insight in the aetiology of pain and discomfort in radiculopathy caused by a herniated disc could lead to more effective management of patients. If the type of inflammatory cells shows to be of major influence on the rate of recovery, new immunomodulating treatment strategies can be developed to decrease the duration and intensity of symptoms. Moreover, identifying a beneficial inflammatory response in the disc through a biomarker in blood could lead to early identification of patients whose herniations will resorb spontaneously versus those that require surgery. Show less
Agrawal, R.; Testi, I.; Lee, C.S.; Tsui, E.; Blazes, M.; Thorne, J.E.; ... ; COVID-19 Imt Study Grp 2021
Background Immunomodulatory therapy (IMT) is often considered for systemic treatment of non-infectious uveitis (NIU). During the evolving coronavirus disease-2019 (COVID-19) pandemic, given the... Show moreBackground Immunomodulatory therapy (IMT) is often considered for systemic treatment of non-infectious uveitis (NIU). During the evolving coronavirus disease-2019 (COVID-19) pandemic, given the concerns related to IMT and the increased risk of infections, an urgent need for guidance on the management of IMT in patients with uveitis has emerged. Methods A cross-sectional survey of international uveitis experts was conducted. An expert steering committee identified clinical questions on the use of IMT in patients with NIU during the COVID-19 pandemic. Using an interactive online questionnaire, guided by background experience and knowledge, 139 global uveitis experts generated consensus statements for IMT. In total, 216 statements were developed around when to initiate, continue, decrease and stop systemic and local corticosteroids, conventional immunosuppressive agents and biologics in patients with NIU. Thirty-one additional questions were added, related to general recommendations, including the use of non-steroidal anti-inflammatory drugs (NSAIDs) and hydroxychloroquine. Results Highest consensus was achieved for not initiating IMT in patients who have suspected or confirmed COVID-19, and for using local over systemic corticosteroid therapy in patients who are at high-risk and very high-risk for severe or fatal COVID-19. While there was a consensus in starting or initiating NSAIDs for the treatment of scleritis in healthy patients, there was no consensus in starting hydroxychloroquine in any risk groups. Conclusion Consensus guidelines were proposed based on global expert opinion and practical experience to bridge the gap between clinical needs and the absence of medical evidence, to guide the treatment of patients with NIU during the COVID-19 pandemic. 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
The emergence of Coronavirus Disease 19 (COVID-19) as a pandemic has claimed hundreds of thousands of lives worldwide since its initial breakout. With increasing reports from clinical observations... Show moreThe emergence of Coronavirus Disease 19 (COVID-19) as a pandemic has claimed hundreds of thousands of lives worldwide since its initial breakout. With increasing reports from clinical observations and autopsy findings, it became clear that the disease causes acute respiratory distress syndrome (ARDS), as well as a broad spectrum of systemic and multiorgan pathologies, including angiopathy, endothelialitis, and thrombosis. Coagulopathy is associated with the activity of megakaryocytes, which play crucial roles in modulating the platelet homeostasis. Only a few autopsy reports include findings on thrombosis formation and the presence of megakaryocytes. Here we review and summarize the possible involvement and the pathophysiology of the thromboembolic events in COVID-19 patients based on post-mortem reports. We reviewed post-mortem reports from March 2020 to September 2020. Eleven autopsy reports that demonstrated thromboembolic involvement findings, either macroscopically or microscopically, were included in this review. All studies reported similar pulmonary gross findings. Not all studies described thrombi formation and megakaryocyte findings. Pulmonary embolism, coagulopathy, severe endothelial injury, and widespread thrombosis are frequent in COVID-19 patients, following many patients with high-level D-Dimer, increased fibrinogen, abnormal prothrombic coagulation, and thrombocytopenia. Reports showed that thrombus was also found in the lower extremities' deep veins and the prostatic venous plexus. In conclusion, a complex interaction of SARS-CoV-2 virus invasion with platelets, leukocytes, endothelial cells, inflammation, immune response, and the possible involvement of megakaryocytes may increase the cumulative risk of thrombosis by a yet unclear cellular and humoral interaction. Show less
AimsInduction heating is a noninvasive, nonantibiotic treatment modality that can potentially be used to cause thermal damage to the bacterial biofilm on the metal implant surface. The purpose of... Show moreAimsInduction heating is a noninvasive, nonantibiotic treatment modality that can potentially be used to cause thermal damage to the bacterial biofilm on the metal implant surface. The purpose of this study was to determine the effectiveness of induction heating on killing Staphylococcus epidermidis from biofilm and to determine the possible synergistic effect of induction heating and antibiotics.MethodsS. epidermidis biofilms were grown on titanium alloy (Ti6Al4V) coupons for 24 hours (young biofilm) and seven days (mature biofilm). These coupons with biofilm were heated to temperatures of 50 degrees C, 55 degrees C, 60 degrees C, 65 degrees C, 70 degrees C, 80 degrees C, and 90 degrees C for 3.5 minutes and subsequently exposed to vancomycin and rifampicin at clinically relevant concentrations.ResultsFor the young biofilm, total eradication was observed at 65 degrees C or higher for 3.5 minutes followed by 24 hours of vancomycin 10 mg/l and rifampicin 1 mg/l. For the mature biofilm, total eradication was observed at 60 degrees C for 3.5 minutes followed by 24 hours of vancomycin 10 mg/l and rifampicin 1 mg/l. Total eradication was also observed at 60 degrees C for 3.5 minutes followed by 24 hours of vancomycin 1 mg/l and rifampicin 1 mg/l followed by anotherthermal shock of 60 degrees C for 3.5 minutes (two thermal shocks).ConclusionInduction heating of Ti6Al4V coupons is effective in reducing bacterial load in vitro for S. epidermidis biofilms. Induction heating and antibiotics have a synergistic effect resulting in total eradication of the biofilm at 60 degrees C or higher for clinically relevant concentrations of vancomycin and rifampicin. Show less
Background: Non-contact induction heating (NCIH) is a noninvasive treatment modality that can be used to cause thermal damage to bacterial biofilms on a metal implant surface in the context of a... Show moreBackground: Non-contact induction heating (NCIH) is a noninvasive treatment modality that can be used to cause thermal damage to bacterial biofilms on a metal implant surface in the context of a prosthetic joint infection. The purpose of this study was (1) to determine the effectiveness of NCIH on killing Staphylococcus aureus from biofilm and (2) to determine the possible synergistic effect of NCIH and cocktails of antibiotics and N-acetylcysteine (NAC). Methods: Staphylococcus aureus biofilms were grown on titanium alloy (Ti6Al4V) coupons. These coupons were heated to 50 degrees C, 60 degrees C, 70 degrees C, 80 degrees C, and 90 degrees C for 3.5 min and subsequently exposed to cocktails of vancomycin, rifampicin and NAC at clinically relevant concentrations over 24 h. Results: In the control group without induction heating, 2.2*10(7) colony forming units (CFU)/cm(2) were observed. At 50 degrees C, 60 degrees C, 70 degrees C, 80 degrees C, and 90 degrees C, a reduction of 0.3-log, 3.9-log, 4.2-log, 4.3-log, and 6.6-log CFU/cm(2) were observed, respectively. There was synergy between antibiotics and induction heating that resulted in less than 100 CFU/cm(2) remaining after 3.5 min at 60 degrees C, and exposure to vancomycin and rifampicin. Total eradication was observed at 80 degrees C. Total eradication was also observed at 60 degrees C and a cocktail of antibiotics with NAC. Conclusion: Induction heating of titanium alloy coupons is effective for the reduction of bacterial load in vitro in S. aureus biofilms. Induction heating and cocktails of antibiotics and NAC have a synergistic effect that results in the total eradication of the biofilm at 60 degrees C and higher for clinically relevant concentrations of vancomycin, rifampicin and NAC. Show less
General significance: Histo-blood group glycans have a unique linking position in the complex network of genes, oncodevelopmental biological processes, and disease mechanisms. Thus, they are highly... Show moreGeneral significance: Histo-blood group glycans have a unique linking position in the complex network of genes, oncodevelopmental biological processes, and disease mechanisms. Thus, they are highly promising targets for novel approaches in the field of personalized medicine. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc. (C) 2015 Elsevier B.V. All rights reserved. Show less
Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to... Show morePreface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use immunosuppressants or who have chronic diseases. The clinic is closely connected to the department of Infectious Diseases at LUMC. The setting of a travel clinic within an academic medical hospital, provides unique circumstances for medical research, like an experienced team of nurses, expertise regarding immunization, a constant flux of travellers and the knowledge and infrastructure that is required for research into microbiology, virology and parasitology. Examples of research that stem from this clinic are projects on immunization against malaria, yellow fever, travellers' diarrhea, poliomyelitis and hepatitis B, vaccination of immunocompromised patients, and projects on travel related acquisition of extended spectrum ß-lactamase producing Enterobacteriacae and on the utility of post-travel screening of asymptomatic travellers for parasites. Show less
Until a few years ago, only two human polyomaviruses (JC and BK) were known to infect humans and cause severe illness in immunocompromised hosts. Since 2007, at least eleven new polyomaviruses... Show moreUntil a few years ago, only two human polyomaviruses (JC and BK) were known to infect humans and cause severe illness in immunocompromised hosts. Since 2007, at least eleven new polyomaviruses became known that infect humans. Among them is the polyomavirus associated with trichodysplasia spinulosa (TSPyV). In Chapter 1 of this dissertation, the main focus is on the recent developments in studying the newly identified human polyomaviruses until mid-2014. This introductory chapter sets the stage for further investigation into TSPyV infection, pathogenesis, evolution and host adaptation, which is detailed in Chapter 2. To study causality between TSPyV infection and TS disease, in Chapter 3, the prevalence, load and localization of this virus is described. In Chapter 4, the cellular mechanisms behind disruption of cellular proliferation and TS spicule formation by TSPyV Large T-antigen is investigated. By In-silico analysis, in Chapter 5, the identification of a polyomavirus evolution and adaptation mechanism called COCO-VA is highlighted. Subsequently, in Chapter 6, TSPyV genome sequences are tested to gain more insight into this COCO-VA mechanism. Finally, in Chapter 7, the findings described in this dissertation are discussed with regard to several TSPyV aspects, and compared to existing knowledge about polyomaviruses in a broader context. Show less
Insects are the most diverse group of animals on earth. They inhabit nearly all terrestrial habitats. One of the factors underlying this success is the ability of insect eggs to survive in adverse... Show moreInsects are the most diverse group of animals on earth. They inhabit nearly all terrestrial habitats. One of the factors underlying this success is the ability of insect eggs to survive in adverse conditions. For a long time the ability to survive these adverse conditions has been attributed to maternal investment in the form of a protective eggshell. In this thesis, I show that contrary to common belief, insect eggs are far from helpless. The insect egg itself develops a cellular layer around the egg called the serosa. This serosa protects the developing embryo from dehydration which enables it to survive in dry habitats. The serosa furthermore protects against infection, mounting an impressive immune response upon the entry of bacteria in the egg. The data presented in this thesis show the importance of the serosa in the survival of the insect egg. I propose that this multifunctional serosa contributed to the great success of insects. Show less
This thesis is focused on the innate immune defence mechanisms responsible for controlling mycobacterial growth after infection. To provide a detailed description of the host__s innate immune... Show moreThis thesis is focused on the innate immune defence mechanisms responsible for controlling mycobacterial growth after infection. To provide a detailed description of the host__s innate immune response to M. marinum infection, zebrafish gene expression levels were analysed by RNA sequencing at various time points during infection and correlated with imaging data of the process of pathogenesis. We demonstrate that the scavenger receptor Marco (macrophage receptor with collagenous structure) is a key player in the rapid phagocytosis of M. marinum and we use gene expression analysis in combination with gene knockdown studies to show that it is also essential in the establishment of an initial transient pro-inflammatory response to M. marinum infection. Once phagocytosed, M. marinum is capable of avoiding killing mechanisms of the host cell and can continue to grow within macrophages. This is the period when Membrane Attack Complex/Perforin proteins are involved in killing intracellular bacteria by their pore-forming activities. We reveal the regulatory mechanisms and function of two macrophage specific genes, mpeg1 and mpeg1.2 (macrophage expressed gene 1.2). The results from this thesis complement knowledge obtained from other model organisms by providing new insights into both counteracting and supporting mechanisms underlying the innate immune response. Show less
The work presented in this thesis has provided new insights into the mechanisms involved in the regulation of innate immune responses in zebrafish embryos. Furthermore, cell-specific transcriptome... Show moreThe work presented in this thesis has provided new insights into the mechanisms involved in the regulation of innate immune responses in zebrafish embryos. Furthermore, cell-specific transcriptome profiling studies identified novel marker genes for distinguishing immune cell types, which is highly useful information to fulfill the demand for new fluorescent reporter lines and lineage-specific antibodies in the zebrafish model. We have shown that Ptpn6, a protein tyrosine phosphatase homolog of human SHP1, functions as a critical negative regulator, required for a properly balanced innate immune response and for controlling infections with bacterial pathogens. In Salmonella typhimurium infection, ptpn6 deficiency caused a general hyperinduction of pro-inflammatory genes, which was contraproductive as it impaired the infection control. In Mycobacterium marinum infection, a more specific effect of ptpn6 deficiency on matrix metalloproteinase gene expression was found as a major underlying cause of increased bacterial burden. We further concluded that Ptpn6 functions as a much stronger negative regulator than infection-inducible miRNAs of the miR-146 family, which may be involved in more subtle fine-tuning of the innate immune response. Knowledge about the distinct roles of Ptpn6 and miR-146 miRNAs has practical applicability in regard to their potential as therapeutic targets for inflammatory diseases and cancer. Show less
