This thesis aimed to assess the impact of bacterial vaginosis (BV) and caesarean section scars on subfertility. In chapter 2 the relationship between (asymptomatic) bacterial vaginosis and... Show moreThis thesis aimed to assess the impact of bacterial vaginosis (BV) and caesarean section scars on subfertility. In chapter 2 the relationship between (asymptomatic) bacterial vaginosis and pregnancy rates during intra uterine insemination or in vitro fertilization treatment (IVF) is investigated. The incidence of BV was 26%. This chapter reveals a higher incidence of miscarriages and a tendency to lower live birth rates among participants testing positive for BV. Chapter 3 showed that a simple pH-measurement could accurately predict if subfertile participants are BV positive. During fertility treatments, the vaginal microbiome of participants changes, as shown in chapter 4. Chapter 5 shows no difference in the time to pregnancy based on BV-status in participants at initial fertility assessment. However, participants with a lower chance to conceive tended to have a longer time to pregnancy if they were BV positive. Chapter 6 shows that participants with a previous caesarean delivery had significant lower live birth rates during IVF treatment compared to a previous vaginal delivery. The review of chapter 7 showed an adverse effect on live birth rates in persons with a caesarean scar niche. A potential relationship between abnormal microbiome (or BV) and a niche could not be accurately assessed. Show less
This thesis described the further development of the controlled human hookworm model and several applications of this model. First, the hookworm egg excretion is modelled over time using Bayesian... Show moreThis thesis described the further development of the controlled human hookworm model and several applications of this model. First, the hookworm egg excretion is modelled over time using Bayesian statistics, resulting in the description of a plateau phase in egg output. Repeated infections a re then investigated as a means to improve the accuracy and statistical power of this output as an outcome measure. The hereby established model is then applied in an immunization study, which shows that it is possible to develop a protective response against short-term larval infection. The skin phase and IgG1 seem to play a role in the development of this protection. Furthermore, gut microbiome changes during controlled hookworm infection are described. Also, volunteers’ motivations and decision making process are investigated, resulting in the characterization of controlled human infection participants as ‘deliberate decision-makers’ and not ‘money-oriented risk-takers’. Following up on the findings in the study described, the importance of a multidisciplinary approach for the improvement of controlled human infection trials is argued in the discussion, with several recommendations made for further collaborative efforts in order to maximise social and scientific output of these studies. Show less
Background: Faecal microbiota transplantation [FMT] shows some effcacy in treating patients with ulcerative colitis [UC], although variability has been observed among donors and treatment regimens.... Show moreBackground: Faecal microbiota transplantation [FMT] shows some effcacy in treating patients with ulcerative colitis [UC], although variability has been observed among donors and treatment regimens. We investigated the effect of FMT using rationally selected donors after pretreatment with budesonide or placebo in active UC. Methods: Patients ≥18 years old with mild to moderate active UC were randomly assigned to 3 weeks of budesonide [9 mg] or placebo followed by 4-weekly infusions of a donor faeces suspension. Two donors were selected based on microbiota composition, regulatory T cell induction and short-chain fatty acid production in mice. The primary endpoint was engraftment of donor microbiota after FMT. In addition, clinical effcacy was assessed. Results: In total, 24 patients were enrolled. Pretreatment with budesonide did not increase donor microbiota engraftment [p = 0.56] nor clinical response, and engraftment was not associated with clinical response. At week 14, 10/24 [42%] patients achieved [partial] remission. Remarkably, patients treated with FMT suspensions from one donor were associated with clinical response [80% of responders, p < 0.05] but had lower overall engraftment of donor microbiota. Furthermore, differences in the taxonomic composition of the donors and the engraftment of certain taxa were associated with clinical response. Conclusion: In this small study, pretreatment with budesonide did not signifcantly infuence engraftment or clinical response after FMT. However, clinical response appeared to be donor-dependent. Response to FMT may be related to transfer of specifc strains instead of overall engraftment, demonstrating the need to characterize mechanisms of actions of strains that maximize therapeutic beneft in UC. Show less
BackgroundPeople living with HIV (PLWH), even when viral replication is controlled through antiretroviral therapy (ART), experience persistent inflammation. This inflammation is partly attributed... Show moreBackgroundPeople living with HIV (PLWH), even when viral replication is controlled through antiretroviral therapy (ART), experience persistent inflammation. This inflammation is partly attributed to intestinal microbial dysbiosis and translocation, which may lead to non-AIDS-related aging-associated comorbidities. The extent to which living with HIV - influenced by the infection itself, ART usage, sexual orientation, or other associated factors - affects the biological age of the intestines is unclear. Furthermore, the role of microbial dysbiosis and translocation in the biological aging of PLWH remains to be elucidated. To investigate these uncertainties, we used a systems biology approach, analyzing colon and ileal biopsies, blood samples, and stool specimens from PLWH on ART and people living without HIV (PLWoH) as controls.ResultsPLWH exhibit accelerated biological aging in the colon, ileum, and blood, as measured by various epigenetic aging clocks, compared to PLWoH. Investigating the relationship between microbial translocation and biological aging, PLWH had decreased levels of tight junction proteins in the intestines, along with increased microbial translocation. This intestinal permeability correlated with faster biological aging and increased inflammation. When investigating the relationship between microbial dysbiosis and biological aging, the intestines of PLWH had higher abundance of specific pro-inflammatory bacteria, such as Catenibacterium and Prevotella. These bacteria correlated with accelerated biological aging. Conversely, the intestines of PLWH had lower abundance of bacteria known for producing the anti-inflammatory short-chain fatty acids, such as Subdoligranulum and Erysipelotrichaceae, and these bacteria were associated with slower biological aging. Correlation networks revealed significant links between specific microbial genera in the colon and ileum (but not in feces), increased aging, a rise in pro-inflammatory microbe-related metabolites (e.g., those in the tryptophan metabolism pathway), and a decrease in anti-inflammatory metabolites like hippuric acid.ConclusionsWe identified specific microbial compositions and microbiota-related metabolic pathways that are intertwined with intestinal and systemic biological aging. This microbial signature of biological aging is likely reflecting various factors including the HIV infection itself, ART usage, sexual orientation, and other aspects associated with living with HIV. A deeper understanding of the mechanisms underlying these connections could offer potential strategies to mitigate accelerated aging and its associated health complications.1fCw832AZENtKENNTh8vkGVideo AbstractConclusionsWe identified specific microbial compositions and microbiota-related metabolic pathways that are intertwined with intestinal and systemic biological aging. This microbial signature of biological aging is likely reflecting various factors including the HIV infection itself, ART usage, sexual orientation, and other aspects associated with living with HIV. A deeper understanding of the mechanisms underlying these connections could offer potential strategies to mitigate accelerated aging and its associated health complications.1fCw832AZENtKENNTh8vkGVideo Abstract Show less
Tweel, M.M. van den; Munckhof, E.H.A. van den; Zanden, M. van der; Molijn, A.C.; Lith, J.M.M. van; Cessie, S. le; Boers, K.E. 2023
PurposeThis study investigates the role of bacterial vaginosis (BV) on pregnancy rates during various fertility treatments. BV is known to influence several obstetric outcomes, such as preterm... Show morePurposeThis study investigates the role of bacterial vaginosis (BV) on pregnancy rates during various fertility treatments. BV is known to influence several obstetric outcomes, such as preterm delivery and endometritis. Only few studies investigated the effect of BV in subfertile women, and studies found a negative effect on fecundity especially in the in vitro fertilisation population.MethodsObservational prospective study, 76 couples attending a fertility clinic in the Netherlands between July 2019 and June 2022, undergoing a total of 133 attempts of intra uterine insemination, in vitro fertilization or intra cytoplasmatic sperm injection. Vaginal samples taken at oocyte retrieval or insemination were analysed on qPCR BV and 16S rRNA gene microbiota analysis of V1-V2 region. Logistic regression with a Generalized Estimated Equations analysis was used to account for multiple observations per couples.ResultsA total of 26% of the 133 samples tested positive for BV. No significant differences were observed in ongoing pregnancy or live birth rates based on BV status (OR 0.50 (0.16-1.59), aOR 0.32 (0.09-1.23)) or microbiome community state type. There was a tendency of more miscarriages based on positive BV status (OR 4.22 (1.10-16.21), aOR 4.28 (0.65-28.11)) or community state type group III and IV. On baseline qPCR positive participants had significantly higher body mass index and smoked more often. Odds ratios were adjusted for smoking status, body mass index, and socioeconomic status.ConclusionBacterial vaginosis does not significantly impact ongoing pregnancy rates but could affect miscarriage rates. Show less
The aim of this thesis was to study novel tools and biomarkers for improved detection of vulvar premalignant disease and aid the investigation of potential new drug targets for the indication of... Show moreThe aim of this thesis was to study novel tools and biomarkers for improved detection of vulvar premalignant disease and aid the investigation of potential new drug targets for the indication of vulvar and HPV-driven diseases.Firstly, this thesis focuses on the recognition and validation of imaging-based biomarkers for recognition of diseases of the skin and external genitalia. Clinical studies were performed using 3D photography, dermatoscopy optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) on vulvar HSIL, lichen sclerosus, cutaneous warts and anogenital warts. These techniques were subsequently implemented in a clinical trial in which a novel small molecule was tested for safety and exploratory efficacy for the treatment of cutaneous warts.Furthermore, this thesis explores sequencing-based biomarkers for vulvar disease, facilitating insight into the aetiology of vulvar diseases and identifying potential new therapeutic targets. The currently available literature on the vulvar microbiome composition was investigated and expanded in an observational study characterising the vulvar microbiome composition of healthy volunteers, vulvar HSIL patients and lichen sclerosus patients. Lastly, a perspective on recent developments in the field of premalignant vulvar disease is provided, with recommendations for future applications of the biomarkers studied in this thesis. Show less
Background: Gut bacteria play a crucial role in the metabolism of bile acids (BA). Whether an association exists between the fecal microbiota composition and circulating BA levels in humans is... Show moreBackground: Gut bacteria play a crucial role in the metabolism of bile acids (BA). Whether an association exists between the fecal microbiota composition and circulating BA levels in humans is poorly understood. Here, we investigated the relationship between fecal microbiota diversity and composition with plasma levels of BA in young adults. Methods: Fecal microbiota diversity/composition was analyzed with 16S rRNA sequencing in 80 young adults (74% women; 21.9 +/- 2.2 years old). Plasma levels of BA were measured using liquid chromatography-tandem mass spectrometry. PERMANOVA and Spearman correlation analyses were used to investigate the association between fecal microbiota parameters and plasma levels of BA. Results: Fecal microbiota beta (P = 0.025) and alpha diversity indexes of evenness (rho = 0.237, P = 0.033), Shannon (rho = 0.313, P = 0.004), and inverse Simpson (rho = 0.283, P = 0.010) were positively associated with plasma levels of the secondary BA glycolithocholic acid (GLCA). The relative abundance of genera belonging to the Firmicutes and Bacteroidetes phyla was positively correlated with plasma levels of GLCA (all rho = 0.225, P = 0.049). However, the relative abundance of species from Firmicutes and Bacteroidetes phyla were negatively correlated with plasma levels of primary and secondary BA (all rho = - 0.220, P = 0.045), except for the relative abundance of Bacteroides vulgatus, Alistipes onderdonkii, and Bacteroides xylanisolvens species (Bacteroidetes phylum) that were positively correlated with the plasma levels of GLCA. Conclusions:The relative abundance of specific fecal bacteria species is associated with plasma levels of BA in young adults. However, further investigations are required to validate whether the composition of the gut microbiota can regulate the plasma concentrations of BA in humans. Show less
BackgroundGut bacteria play a crucial role in the metabolism of bile acids (BA). Whether an association exists between the fecal microbiota composition and circulating BA levels in humans is poorly... Show moreBackgroundGut bacteria play a crucial role in the metabolism of bile acids (BA). Whether an association exists between the fecal microbiota composition and circulating BA levels in humans is poorly understood. Here, we investigated the relationship between fecal microbiota diversity and composition with plasma levels of BA in young adults.MethodsFecal microbiota diversity/composition was analyzed with 16S rRNA sequencing in 80 young adults (74% women; 21.9 ± 2.2 years old). Plasma levels of BA were measured using liquid chromatography-tandem mass spectrometry. PERMANOVA and Spearman correlation analyses were used to investigate the association between fecal microbiota parameters and plasma levels of BA.ResultsFecal microbiota beta (P = 0.025) and alpha diversity indexes of evenness (rho = 0.237, P = 0.033), Shannon (rho = 0.313, P = 0.004), and inverse Simpson (rho = 0.283, P = 0.010) were positively associated with plasma levels of the secondary BA glycolithocholic acid (GLCA). The relative abundance of genera belonging to the Firmicutes and Bacteroidetes phyla was positively correlated with plasma levels of GLCA (all rho ≥ 0.225, P ≤ 0.049). However, the relative abundance of species from Firmicutes and Bacteroidetes phyla were negatively correlated with plasma levels of primary and secondary BA (all rho ≤ − 0.220, P ≤ 0.045), except for the relative abundance of Bacteroides vulgatus, Alistipes onderdonkii, and Bacteroides xylanisolvens species (Bacteroidetes phylum) that were positively correlated with the plasma levels of GLCA.ConclusionsThe relative abundance of specific fecal bacteria species is associated with plasma levels of BA in young adults. However, further investigations are required to validate whether the composition of the gut microbiota can regulate the plasma concentrations of BA in humans. Show less
Background Gut bacteria play a crucial role in the metabolism of bile acids (BA). Whether an association exists between the fecal microbiota composition and circulating BA levels in humans is... Show moreBackground Gut bacteria play a crucial role in the metabolism of bile acids (BA). Whether an association exists between the fecal microbiota composition and circulating BA levels in humans is poorly understood. Here, we investigated the relationship between fecal microbiota diversity and composition with plasma levels of BA in young adults.Methods Fecal microbiota diversity/composition was analyzed with 16S rRNA sequencing in 80 young adults (74% women; 21.9 +/- 2.2 years old). Plasma levels of BA were measured using liquid chromatography-tandem mass spectrometry. PERMANOVA and Spearman correlation analyses were used to investigate the association between fecal microbiota parameters and plasma levels of BA.Results Fecal microbiota beta (P = 0.025) and alpha diversity indexes of evenness (rho = 0.237, P = 0.033), Shannon (rho = 0.313, P = 0.004), and inverse Simpson (rho = 0.283, P = 0.010) were positively associated with plasma levels of the secondary BA glycolithocholic acid (GLCA). The relative abundance of genera belonging to the Firmicutes and Bacteroidetes phyla was positively correlated with plasma levels of GLCA (all rho = 0.225, P = 0.049). However, the relative abundance of species from Firmicutes and Bacteroidetes phyla were negatively correlated with plasma levels of primary and secondary BA (all rho = - 0.220, P = 0.045), except for the relative abundance of Bacteroides vulgatus, Alistipes onderdonkii, and Bacteroides xylanisolvens species (Bacteroidetes phylum) that were positively correlated with the plasma levels of GLCA.Conclusions The relative abundance of specific fecal bacteria species is associated with plasma levels of BA in young adults. However, further investigations are required to validate whether the composition of the gut microbiota can regulate the plasma concentrations of BA in humans. Show less
Borry, M.; Forsythe, A.; Valtueña, A.A.; Hübner, A.; Ibrahim, A.; Quagliariello, A; ... ; Fellows Yates, J.A. 2023
Background: Access to sample-level metadata is important when selecting public metagenomic sequencing datasets for reuse in new biological analyses. The Standards, Precautions, and Advances in... Show moreBackground: Access to sample-level metadata is important when selecting public metagenomic sequencing datasets for reuse in new biological analyses. The Standards, Precautions, and Advances in Ancient Metagenomics community (SPAAM, https://spaam-community.github.io) has previously published AncientMetagenomeDir, a collection of curated and standardised sample metadata tables for metagenomic and microbial genome datasets generated from ancient samples. However, while sample-level information is useful for identifying relevant samples for inclusion in new projects, Next Generation Sequencing (NGS) library construction and sequencing metadata are also essential for appropriately reprocessing ancient metagenomic data. Currently, recovering information for downloading and preparing such data is difficult when laboratory and bioinformatic metadata is heterogeneously recorded in prose-based publications. Methods: Through a series of community-based hackathon events, AncientMetagenomeDir was updated to provide standardised library-level metadata of existing and new ancient metagenomic samples. In tandem, the companion tool 'AMDirT' was developed to facilitate automated metadata curation and data validation, as well as rapid data filtering and downloading. Results: AncientMetagenomeDir was extended to include standardised metadata of over 5000 ancient metagenomic libraries. The companion tool 'AMDirT' provides both graphical- and command-line interface based access to such metadata for users from a wide range of computational backgrounds. We also report on errors with metadata reporting that appear to commonly occur during data upload and provide suggestions on how to improve the quality of data sharing by the community.Conclusions: Together, both standardised metadata and tooling will help towards easier incorporation and reuse of public ancient metagenomic datasets into future analyses. Show less
Als gevolg van de grote technologische vooruitgang in de gezondheidszorg worden in toenemende mate gegevens verzameld tijdens de uitvoering van klinische onderzoeken. Het is evenwel essentieel om... Show moreAls gevolg van de grote technologische vooruitgang in de gezondheidszorg worden in toenemende mate gegevens verzameld tijdens de uitvoering van klinische onderzoeken. Het is evenwel essentieel om te beseffen dat gegevens op zich van weinig of geen waarde zijn. Ten behoeve van hun optimale bruikbaarheid dienen gegevens geanalyseerd, geïnterpreteerd en verwerkt te worden. Machine learning-strategieën kunnen hiertoe nuttige en adequate oplossingen bieden. Dit proefschrift bevat machine learning-benaderingen toegepast op verschillende klinische datasets. De klassieke gegevens bestaan uit elektrische signalen van het electrocardiogram (ecg) verkregen bijgezonde proefpersonen, de innovatieve gegevens zijn afkomstig vanmetingen in een rijsimulator, en de opkomende gegevens zijn afgeleid van dna-analyse van de micro-organismen die op de huid voorkomenvan patiënten met huidziekten. We toonden aan dat het aantal ECG’s van invloed was op de nauwkeurigheid van geschatte verlenging van het qt-interval voor alle ingezette qt-correctieformules. Met behulp van SHapley AdditiveexPlanations (shap)-waarden werd de impact van de individuele kenmerken op de voorspelling van fysiologische leeftijd van het hart bepaald. We maakten gebruik van machine learning voor een betere beoordeling van de rijprestaties van bestuurders die medicijnen gebruikten. Tot slot lieten we zien dat de belangrijkste micro-organismen voor discriminatie van seborrroische dermatitis – naast Cutibacterium en Staphylococcus – kwamen relatief weinig voor, waardoor men deze micro-organismen in standaardanalyses eenvoudig over het hoofd kan zien. Daarmee hebben we aangetoond dat machine learning kanworden toegepast op gegevens die zijn afgeleid van klinische onderzoeken om in een vroeg stadium het effect van medicijnen en andere interventies op te sporen en te evalueren. Show less
Fagernäs Z.; Salazar-García, D.C.; Haber Uriarte, M.; Avilés Fernández, A.; Henry A.G.; Lomba Maurandi, J.; ... ; Warinner, C. 2022
The oral cavity is a heterogeneous environment, varying in factors such as pH, oxygen levels, and salivary flow. These factors affect the microbial community composition and distribution of species... Show moreThe oral cavity is a heterogeneous environment, varying in factors such as pH, oxygen levels, and salivary flow. These factors affect the microbial community composition and distribution of species in dental plaque, but it is not known how well these patterns are reflected in archaeological dental calculus. In most archaeological studies, a single sample of dental calculus is studied per individual and is assumed to represent the entire oral cavity. However, it is not known if this sampling strategy introduces biases into studies of the ancient oral microbiome. Here, we present the results of a shotgun metagenomic study of a dense sampling of dental calculus from four Chalcolithic individuals from the southeast Iberian peninsula (ca. 4500–5000 BP). Interindividual differences in microbial composition are found to be much larger than intraindividual differences, indicating that a single sample can indeed represent an individual in most cases. However, there are minor spatial patterns in species distribution within the oral cavity that should be taken into account when designing a study or interpreting results. Finally, we show that plant DNA identified in the samples is likely of postmortem origin, demonstrating the importance of including environmental controls or additional lines of biomolecular evidence in dietary interpretations. Show less
BACKGROUND & AIMS: Patients with multiple recurrent Clostridioides difficile infection (rCDI) have a disturbed gut microbiota that can be restored by fecal microbiota trans-plantation (FMT).... Show moreBACKGROUND & AIMS: Patients with multiple recurrent Clostridioides difficile infection (rCDI) have a disturbed gut microbiota that can be restored by fecal microbiota trans-plantation (FMT). Despite extensive screening, healthy feces donors may carry bacteria in their intestinal tract that could have long-term health effects, such as potentially procarci-nogenic polyketide synthase-positive (pks+) Escherichia coli. Here, we aim to determine whether the pks abundance and persistence of pks+ E coli is influenced by pks status of the donor feces. METHODS: In a cohort of 49 patients with rCDI treated with FMT and matching donor samples-the largest cohort of its kind, to our knowledge-we retrospectively screened fecal metagenomes for pks+ E coli and compared the presence of pks in patients before and after treatment and to their respective donors. RESULTS: The pks island was more prevalent (P = .026) and abundant (P < .001) in patients with rCDI (pre-FMT, 27 of 49 [55%]; median, 0.46 reads per kilobase per million [RPKM] pks) than in healthy donors (3 of 8 donors [37.5%], 11 of 38 samples [29%]; median, 0.01 RPKM pks). The pks status of patients post-FMT depended on the pks status of the donor suspension with which the patient was treated (P = .046). Particularly, persistence (8 of 9 cases) or clearance (13 of 18) of pks+ E coli in pks+ patients was correlated to pks in the donor (P = .004). CONCLUSIONS: We conclude that FMT contrib-utes to pks+ E coli persistence or eradication in patients with rCDI but that donor-to-patient transmission of pks+ E coli is unlikely. Show less
Antibiotics provided humanity resilience to the majority of bacterial infections. An important trade-off is the emergence of antimicrobial resistance, and a diminished and perturbed microbiota,... Show moreAntibiotics provided humanity resilience to the majority of bacterial infections. An important trade-off is the emergence of antimicrobial resistance, and a diminished and perturbed microbiota, resulting in an increased susceptibility for Clostridioides difficile infections. For both C. difficile and multidrug resistant micro-organisms (MDRO), asymptomatic colonisation of the gut plays an important role in the development of infection. The aim of this thesis is to better understand the role of the microbiota in defence against infections with C. difficile and MDRO. The first part describes the epidemiology and detection of asymptomatically colonized individuals. It concludes that though asymptomatic colonization of MDRO and C. difficile can become a nidus for nosocomial (hospital) infection and transmission, its prevalence is still low in the Netherlands. The second part of this thesis focuses on eradication and/or treatment of these micro-organisms with ‘fecal microbiota transplantation’ of healthy donor feces. It describes the establishment of the Netherlands Donor Feces Bank, and the research, experiences and successes of FMT in the treatment of patients with recurrent C. difficile infections and MDRO. The experience of this thesis may help the establishment, utilization, standardization and maturation of stool banks and research institutes of the next-generation of microbiota modifying therapies. Show less
Schistosome infection is recognized as a potentially modifiable risk factor for HIV in women by the World Health Organization. Alterations in cervicovaginal bacteria have been associated with HIV... Show moreSchistosome infection is recognized as a potentially modifiable risk factor for HIV in women by the World Health Organization. Alterations in cervicovaginal bacteria have been associated with HIV acquisition and have not been studied in schistosome infection. We collected cervical swabs from Tanzanian women with and without S. mansoni and S. haematobium to determine effects on cervicovaginal microbiota. Infected women were treated, and follow-up swabs were collected after 3 months. 16S rRNA sequencing was performed on DNA extracted from swabs. We compared 39 women with S. mansoni with 52 uninfected controls, and 16 with S. haematobium with 27 controls. S. mansoni-infected women had increased abundance of Peptostreptococcus (p = 0.026) and presence of Prevotella timonesis (p = 0.048) compared to controls. High-intensity S. haematobium infection was associated with more diverse cervicovaginal bacterial communities than uninfected controls (p = 0.0159). High-intensity S. mansoni infection showed a similar trend (p = 0.154). At follow-up, we observed increased alpha diversity in S. mansoni (2.53 vs. 1.72, p = 0.022) and S. haematobium (2.05 vs. 1.12, p = 0.066) infection groups compared to controls. Modifications in cervicovaginal microbiota, particularly increased diversity and abundance of taxa associated with bacterial vaginosis and HIV (Peptostreptococcus, Prevotella), were associated with schistosome infection. Show less
The human body is colonized by microorganisms, collectively referred to as the human microbiota. Microbiota disturbance has been associated with a wide range of diseases and is the focus of many... Show moreThe human body is colonized by microorganisms, collectively referred to as the human microbiota. Microbiota disturbance has been associated with a wide range of diseases and is the focus of many research initiatives. The most widely used approach is based on sequencing of the 16S rRNA gene. This method can also be very valuable for clinical microbiology as it enables identification of a theoretically unlimited number of bacteria present in a specimen and permits (semi)quantitative information about the composition of a microbial community. In this thesis we investigated whether 16S rRNA gene profiling would have added value for direct diagnostics and/or as an indirect tool for evaluating cheaper diagnostic tests or evaluating treatments. The studies in this thesis were focused on respiratory tract infections, bacterial vaginosis, atopic dermatitis or male genital lichen sclerosus. The main challenge of 16S rRNA gene profiling is the clinical interpretation of relative abundance of the identified bacteria in clinical specimens. More clinical studies with appropriate control groups are needed to define and validate clinically relevant cut-off values, to measure microbiota variability over time and to determine microbial phenotypes. The clinical value of 16S rRNA gene profiling will probably become clear in the forthcoming years. Show less
In recent years, preclinical studies have illustrated the potential role of intestinal bacterial composition in the risk of stroke and post-stroke infections. The results of these studies suggest... Show moreIn recent years, preclinical studies have illustrated the potential role of intestinal bacterial composition in the risk of stroke and post-stroke infections. The results of these studies suggest that bacteria capable of producing volatile metabolites, including trimethylamine-N-oxide (TMAO) and butyrate, play opposing, yet important roles in the cascade of events leading to stroke. However, no large-scale studies have been undertaken to determine the abundance of these bacterial communities in stroke patients and to assess the impact of disrupted compositions of the intestinal microbiota on patient outcomes. In this prospective case-control study, rectal swabs from 349 ischemic and hemorrhagic stroke patients (median age, 71 years; IQR: 67-75) were collected within 24 h of hospital admission. Samples were subjected to 16S rRNA amplicon sequencing and subsequently compared with samples obtained from 51 outpatient age- and sex-matched controls (median age, 72 years; IQR, 62-80) with similar cardiovascular risk profiles but without active signs of stroke. Plasma protein biomarkers were analyzed using a combination of nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS). Alpha and beta diversity analyses revealed higher disruption of intestinal communities during ischemic and hemorrhagic stroke compared with non-stroke matched control subjects. Additionally, we observed an enrichment of bacteria implicated in TMAO production and a loss of butyrate-producing bacteria. Stroke patients displayed two-fold lower plasma levels of TMAO than controls (median 1.97 vs 4.03 mu M, Wilcoxonp < 0.0001). Finally, lower abundance of butyrate-producing bacteria within 24 h of hospital admission was an independent predictor of enhanced risk of post-stroke infection (odds ratio 0.77,p = 0.005), but not of mortality or functional patient outcome. In conclusion, aberrations in trimethylamine- and butyrate-producing gut bacteria are associated with stroke and stroke-associated infections. Show less
Purpose of Review Caregivers of children with a chronic illness are a neglected group in medical research and patient care, and are frequently confronted with chronic psychological distress. The... Show morePurpose of Review Caregivers of children with a chronic illness are a neglected group in medical research and patient care, and are frequently confronted with chronic psychological distress. The biological consequences of this chronic distress are unclear but highly relevant, as these caregivers have a lifelong task in caring for their child. In this review, the authors specifically describe caregiver distress related to autism spectrum disorder (ASD), but the review may be relevant to other chronic diseases, including cancer. Recent Findings Epidemiological evidence illustrates the increased mortality risk in caregivers of children with ASD although some individual factors appear to diminish these risks. Biological studies demonstrate that caregiver distress can lead to dysregulation of the hypothalamic-pituitary-adrenal-axis, a pro-inflammatory state of the immune and central nervous system, and gut microbiome imbalance. Caregivers of children with a chronic illness like ASD deserve more health-related attention with respect to their psychological and physical well-being. Such attention would benefit individual caregivers, as well as their children, as both are highly interconnected. Structural psychological and physical screening of caregivers can be considered. Show less
Rheumatoid arthritis is a heterogeneous disease, which can be, based on data combining genetic risk factors and autoantibodies, sub-classified into ACPA-positive and -negative RA. Presence of ACPA... Show moreRheumatoid arthritis is a heterogeneous disease, which can be, based on data combining genetic risk factors and autoantibodies, sub-classified into ACPA-positive and -negative RA. Presence of ACPA and RF as well as rising CRP-levels in some patients years before onset of clinical symptoms indicate that relevant immune responses for RA development are initiated very early. ACPA are highly specific for RA, whereas RF can also be found among healthy (elderly) individuals and patients with other autoimmune diseases or infection. The most important genetic risk factor for RA development, the shared epitope alleles, resides in the MHC class II region. Shared epitope alleles, however, only predispose to the development of ACPA-positive RA. Smoking is thus far the most important environmental risk factor associated with the development of RA. Studies on synovitis have shown the importance not only of adaptive but also of innate immune responses. In summary of the various results from immunological changes in blood and synovial tissue, the extension of the immune response from a diffuse myeloid to a lympho-myeloid inflammation appears to be associated with a more successful therapeutic response to biologics. With respect to advances in synovitis research, new targets for treatment against pathological subsets of immune cells or fibroblasts are already on the horizon. However, alternative strategies involving the microbiome may play an important role as well and research in this field is growing rapidly. Show less
This thesis combines field and laboratory studies to address some of the most pressing questions in the field of microplastic research. Specifically, the thesis addresses the topic of microplastics... Show moreThis thesis combines field and laboratory studies to address some of the most pressing questions in the field of microplastic research. Specifically, the thesis addresses the topic of microplastics in the freshwater environment. The research presented covers both the environmental presence and abundance of microplastics, in addition to ecological effects, investigated using observational and experimental studies. These studies give a greater understanding of the abundance, types and sources of microplastics in freshwater systems in the UK, how organisms and chemicals interact with microplastics and the potential ecological effects on a range of freshwater organisms from different functional feeding groups and trophic levels. Show less
