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Körper – Ordnungen – Weltverhältnisse. Historisch-somatologische Perspektiven auf den verglichenen Körper am Beispiel des Kulturkontakts mit dem Osmanischen Reich im Spiegel deutschsprachiger Reiseberichte des 16.-18. Jahrhunderts
No full textLnc-ing cardiotoxicity to cancer drugs: role of long non-coding RNAs in TKI-related cardiotoxicity
No full textCancer therapy has increased the lifespan of cancer patients worldwide. Nevertheless, the improved survival has uncovered a rising number of cardiovascular adverse events associated with or directly caused by cancer treatment. Novel targeted therapies such as small molecule tyrosine kinases inhibitors (TKIs) have been shown to be cardiotoxic, especially in the already heart-diseased population. Secondary cardiovascular events might be caused by on- and/or off-target toxicities due to the inhibition of these important receptors also expressed in the heart.
The fms-like tyrosine kinase 3 (Flt3) is a tyrosine kinase receptor mainly expressed in early hematopoietic progenitor cells and its mutation leads to constitutive activation that drives acute myeloid leukemia. The lab previously demonstrated a cytoprotective role of Flt3 activation after myocardial infarction (MI) in mice by injecting intramyocardially recombinant Flt3-ligand, which resulted in improved post-MI remodeling and function. We also found that the Flt3-targeting TKI quizartinib increases apoptotic cell death and worsens maladaptive remodeling after MI. Currently, long non-coding RNAs (lncRNAs), the largest class of non-coding RNAs, have emerged as master regulators of the gene regulatory network and they play a major role in cardiovascular disease pathophysiology. Through their cell type specificity and their actions on epigenetic, post-transcriptional and translational processes, they represent attractive molecules for therapeutic targeting.
Our research showed that the hidden cardiotoxicity of quizartinib, which manifests in the infarcted heart, is associated with a distinct expression pattern of lncRNAs. This altered transcriptomic landscape unveils a pool of possible therapeutic targets for cardioprotection. We identified a novel candidate lncRNA XLOC_044469, which was enriched in cardiac fibroblast, upregulated in quizartinib-treated infarcted hearts and which highly correlated with cardiac dysfunction and remodeling parameters. It was found to be localized within the transcription factor Basonuclin 2 (Bnc2) locus, which similarly showed upregulation in quizartinib-treated infarcted mouse hearts and strong correlation with cardiac dysfunction and remodeling parameters. Furthermore, the apparent locus conservation in humans could harbor translational value, which could be explored for therapeutic targeting. Finally, quizartinib-treated infarcted hearts showed a distinct expression pattern of protein-coding genes, with enrichment of gene sets related to cardiac contractility and energy handling. Via a mitochondrial activity assay, we demonstrated alterations in cellular respiration and ATP production of cardiomyocytes in response to quizartinib in a dose-dependent manner.
Although many cancer therapies are already known for their cardiovascular side effects, more studies investigating cancer drug-related cardiotoxicity are necessary, since most clinical trials exclude the most vulnerable patients, who have cardiovascular risk factors or underlying cardiac diseases. As we observed in our study, cardiovascular toxicity might only happen in the already diseased heart. In this regard, the lncRNA landscape may harbor great potential for the discovery of future therapeutic targets for cardioprotection against TKI-related cardiotoxicities
Identification and characterization of substances interfering with steroid metabolizing enzymes and retinoic acid-related orphan receptor γt activity
Get PDFSteroid hormones regulate a wide range of physiological processes by activating nuclear receptors, which then act as transcription factors to control the expression of their target genes. Toxicological safety assessments of chemicals to which humans may be exposed also include a section on endocrine assessments, which often focus on direct effects on the nuclear receptors of the sex steroid hormones, namely the androgen and the estrogen receptors. The effects of chemicals on pre receptor control, which includes the biosynthesis of the steroid hormones themselves, as well as on other nuclear receptors such as the immunomodulating retinoic acid related orphan receptor γt (RORγt) activity have been investigated insufficiently so far. This thesis aims to identify and characterize substances that interfere with steroid metabolizing enzymes and RORγt activity. We have addressed this goal in three different projects, which are focusing on different areas of endocrinology.
The steroidogenic enzyme 11β hydroxysteroid dehydrogenase type 2 (HSD11B2), is involved in the pre receptor control of the mineralocorticoid receptor (MR) by inactivating 11 hydroxylated glucocorticoids, that can bind and activate the MR. This ensures the receptors specificity for its natural ligand, aldosterone. Inhibition of HSD11B2 can lead to pseudohyperaldosteronism, an effect that has also been described in clinical case studies with patients treated with the azole antifungals itraconazole and posaconazole. In the first project, we assessed species specific susceptibility towards azole fungicide dependent HSD11B2 inhibition. The results of this investigation provided a possible explanation, why this adverse drug effect was missed during clinical trials. The human HSD11B2 homolog was strongly inhibited by both azole fungicides, while the rat enzyme was only moderately inhibited. Mouse and zebrafish homologs were only weakly inhibited. Using predictions based on homology modeling of HSD11B2 and analysis of chimeric enzyme variants, we were able to identify the C terminal region and the amino acid residues at positions 170 and 172 as relevant structural elements that are partly responsible for the species specific differences between the mouse and human homologs. This study highlights that such species specific differences in the inhibition of steroidogenic enzymes by chemicals may be relevant for toxicological investigations and should therefore be considered in future studies. As an extension of this project, we summarized the methods used for the analysis of the enzymatic activity of HSD11B2 together with further assessment possibilities for the in vitro enzyme activity determination of HSD11B2 and 11β hydroxysteroid dehydrogenase type 1 (HSD11B1) in two chapters for the book series 'Methods in Enzymology'. HSD11B1 catalyzes the reverse reaction of HSD11B2, reducing 11 keto glucocorticoids to their active 11β hydroxy forms.
Parabens and UV filters are used as additives in body care products and cosmetics to increase their shelf life. These compounds have been measured in various human matrices, including fetal samples, and are known to have antiandrogenic effects by blocking androgen receptor (AR) activity. To date, the influence of these chemicals on the pre receptor control of AR, specifically the androgen biosynthesis, is poorly understood. 3α hydroxysteroid dehydrogenases (3α HSD) are steroidogenic enzymes that can catalyze one of the last two synthesis steps in the backdoor pathway of the most potent androgen, 5α dihydrotestosterone (DHT). Androgen mediated AR activation is required for normal male genitalia formation during embryogenesis.
In the second project, we investigated the effects of parabens and UV filters on the enzymatic activity of different 3α HSDs that can produce DHT in the backdoor pathway using a novel, radiometric enzyme activity assay. We have identified several parabens and benzophenone type UV filters as the first inhibitors of the 3α HSD 17β hydroxysteroid dehydrogenase type 6 (HSD17B6) with IC50 values in the mid and high nanomolar range. Said identified inhibitors were analyzed for their structure-activity relationship using a novel HSD17B6 homology model, which highlighted the importance of the 4-hydroxylated phenyl head group present in both substance classes. The addition of a methyl group to the 4-hydroxy group resulted in a loss of inhibitory capacity in 4-methoxylated benzophenones, as it prevented the formation of a hydrogen bond with the amide group of the cofactor nicotinamide adenine dinucleotide (NAD+) in the binding pocket of the homology model.
Parabens and UV filters, like many other chemicals, have so far mainly been investigated for their direct effects on the androgen and estrogen receptors. RORγt is involved in immune response regulation and is essential for the differentiation of T helper 17 cells and their expression of pro inflammatory interleukins. Excessive activation of RORγt has been associated with inflammatory and autoimmune diseases such as psoriasis.
In the third project, we evaluated the effect of parabens and UV filters on RORγt activity using a previously established tetracycline inducible reporter gene assay in Chinese hamster ovary cells. We identified hexylparaben, benzylparaben and benzophenone 10 as potent RORγt agonists with EC50 values within the higher nanomolar and lower micromolar range. Those RORγt agonists were also able to enhance pro inflammatory cytokine expression in a mouse EL4 T lymphocyte model. Together with structurally similar chemicals which we identified by virtual screening of a cosmetics database, the chemicals identified as RORγt agonists in this study showed additive effects on the receptor activity when assessed as mixtures.
Additional experiments are required to determine whether parabens and UV filters can reach the concentrations described in the second and third projects to exert potential antiandrogenic effects in organs expressing HSD17B6, or possibly aggravate existing inflammatory and autoimmune diseases through the additional RORγt activation.
As an additional, fourth project, we examined three case studies of Tunisian patients diagnosed with 17β hydroxysteroid dehydrogenase type 3 (HSD17B3) deficiencies for their underlying molecular causes. HSD17B3 is a steroidogenic enzyme that is exclusively expressed in the testes and catalyzes the last enzymatic step of testosterone synthesis. Testosterone, a potent androgen, is essential for normal male sexual development. Pathogenic mutations in the HSD17B3 gene can lead to undervirilization of the male sexual organs due to insufficient testosterone production during embryogenesis, which is why HSD17B3 deficiencies are classified as 46,XY disorders of sexual development. Genetic analysis of the three patients revealed in one patient the first homozygous mutation in the catalytic tetrad of HSD17B3, p.K202M, for which we were able to show a complete loss of function using a radiometric enzyme activity assay. The second patient was a compound heterozygote with a paternally inherited, already characterized, inactive truncation mutation p.C206X and a maternally inherited splice site mutation (c.490 6 T > C) for which we could show by means of a splicing assay that the mutation causes skipping of exon 7 during mRNA splicing which presumably results in a truncated and inactive enzyme. The last patient turned out to have a homozygous p.C206X mutation of HSD17B3. Consanguineous marriages can promote the emergence and establishment of deleterious mutations such as the ones identified in this project. This study highlights the importance of genetic counseling and the sensitization of medical personnel towards HSD17B3 deficiencies.
The projects conducted in this thesis address relevant limitations of endocrine studies that are part of safety assessments of chemicals. By assessing species specific inhibition of HSD11B2 by azole fungicides, and identifying parabens and UV filters as modulators of HSD17B6 and RORγt activities, we have created a foundation for further research. The methods and homology models described in the respective projects of this thesis may prove to be valuable tools for future studies
Modelling diagnostic error to improve estimation of helminth treatment efficacy, age-specific prevalence and enhance comparison of diagnostic tools
Get PDFBackground: According to the latest global disease burden estimates roughly 1.1 billion people suffer from neglected tropical diseases (NTDs), from which over a billion are infected with soil-transmitted helminths (STHs) or Schistosoma leading to a considerable public health burden. For instance, children mainly suffer from anaemia and growth stunting while adults may develop chronic diseases, which can also result in confined function of affected organs. With financial support from different organisations and donations from pharmaceutical companies, numerous interventions have been implemented to reduce the burden of NTDs. In some cases, specific NTDs have been eliminated. The main interventions are preventive chemotherapy (PC), water, sanitation and hygiene (WASH) and information, education and communication (IEC). However, much remains to be done, and hence, in 2020, the World Health Organization (WHO) put forth a road map for the control and elimination of the NTDs.
To reach the best possible outcomes, control programmes need to be informed about the impact of interventions. This requires prevalence and infection intensity estimates at baseline and following interventions. To assess the prevalence and efficacy of treatments, tools that are widely used lack accuracy, and hence, result in underestimated prevalences and overestimated cure rates (CRs). Highly sensitive diagnostic techniques are available, but rarely applied in the field. It is therefore important to include the diagnostic error to obtain ‘true’ estimates to accurately inform disease control programmes.
Goal and objectives: The overreaching goal of this PhD thesis was to improve estimation of diagnostic error taking into account variation in egg counts from day- to-day and slide-to-slide to evaluate the performance of diagnostics, disease burden and the efficacy of treatments to better guide control and elimination efforts of NTDs. The specific objectives were to (i) estimate the performance of diagnostic tools against Schistosoma haematobium; (ii) translate prevalence thresholds from urine filtration into reagent strip; (iii) assess the efficacy of drug therapies against STHs; (iv) assess the sensitivity of diagnostics for different Schistosoma species and STHs; and (v) estimate age-dependent prevalence for S. mansoni using Bayesian methods.
Methods: In Chapter 2, I developed a model to compare diagnostic methods for S. haematobium, namely urine filtration and reagent strip. Urine filtration results consisted of egg counts, while reagent strip results were semi-quantitative, wherefore two different distributions were assumed. To estimate the prevalence, the infected and non-infected individuals were separated. As the data consist of specimen taken on five consecutive days subjected to two different tests, I was able to take into account diagnostic error and hence, estimate infection intensity-dependent sensitivity. Moreover, by running extensive simulations of hypothetical populations in diverse transmission settings, we relate WHO prevalence thresholds from urine filtration into reagent strip.
In Chapter 3, I developed a transmission model to conduct a meta-analysis on CR and egg reduction rate (ERR) for an ensemble of drug therapies against hook- worm. The prevalence, which is defined as harbouring at least one fertilized female worm, and the CRs were estimated by incorporating a mixture modelling approach. The model was fitted to data from six randomized controlled trials. At baseline and treatment follow-up, two specimen per study participant were collected over consec- utive days, which enabled us to take into account diagnostic error and estimate the infection intensity-dependent sensitivity of the Kato-Katz test for hookworm.
In Chapter 4, I extended the egg count model of Chapter 3 and included the density-dependent fecundity to estimate CR and ERR for several drug therapies against Trichuris trichiura. Moreover, the infection intensity-dependent sensitivity of the Kato-Katz test was estimated for T. trichiura.
In Chapter 5, I extended a transmission model and included diagnostic error to estimate age-dependent prevalence curves for S. mansoni and predicted the preva- lence of adults from the prevalence of school-aged children. The model was fitted to data from Uganda, which was collected by the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) and consists of specimen taken on consecutive days (two days for two years, three days for one year). This enabled estimating the infection intensity-dependent sensitivity of the Kato-Katz test for S. mansoni.
Results: The diagnostic accuracy of reagent strip was equivalent to urine filtra- tion data obtained on a single day, when traces were considered negative. A 10% and 50% urine filtration prevalence based on a single day sampling corresponds to 11.2% and 48.6% prevalence by reagent strip, respectively, when traces were con- sidered negative, and 17.6% and 57.7%, respectively, when traces were considered positive.
Taking the diagnostic error into account resulted in considerably lower CRs for drug therapies against hookworm than previously reported. Overall, of all treat- ments analyzed, mebendazole administered in six dosages of 100 mg each was the most efficacious treatment with a CR of 88% (95% Bayesian credible interval: 79- 95%). Diagnostic sensitivity of Kato-Katz for hookworm varied with the infection intensity and sampling effort. For an infection intensity of 50 eggs per gram of stool (EPG), the sensitivity is close to 60%; for two Kato-Katz thick smears it increased to 76%.
The treatment with the highest CR against T. trichiura was the combination therapy of albendazole plus pyrantel pamoate plus oxantel pamoate with a CR of 79% and an ERR of 91%. Albendazole plus oxantel pamoate showed the highest ERR of 97% and a CR of 69%. For 24 EPG, the sensitivity was around 50% for a single and increased to almost 70% for duplicate Kato-Katz thick smears.
For 24 EPG, the sensitivity of Kato-Katz for S.mansoni was estimated to be 55%, 77% and 99% for simple, duplicate and quadruplicate thick smears.
Conclusions/significance: The main contribution of this PhD thesis to the field of mathematical modelling in public health is the development or extension of modelling frameworks to accurately compare the performance of diagnostics, assess their sensitivity, estimate treatment efficacy and age-specific prevalence. In more detail: (i) reagent strip and urine filtration were compared for detection of S. haematobium; (ii) the intensity-dependent sensitivity for different sampling schemes was estimated for aforementioned diagnostic tools as well as the Kato-Katz technique for hookworm and T. trichiura; (iii) the efficacy of different treatments against hook- worm and T. trichiura were assessed; (iv) the age-specific prevalence for S. mansoni was estimated; and the prevalence in adults was predicted from the prevalence in school-aged children for S. mansoni. The higher accuracy compared to existing studies was achieved by taking into account diagnostic error and the transmission mechanism.
If reagent strip instead of urine filtration would be employed in schistosomiasis control programmes, the costs could be substantially reduced and proceedings would be more efficient. Moreover, the treatment efficacy and infection intensity- dependent sensitivity estimates for different sampling schemes may be considered in aforementioned programmes to make decisions about suitable drug therapies and sampling designs
Understanding transport mechanisms across the human blood-brain barrier in Alzheimer's disease
Get PDFSummary for a Lay Audience in English
The blood-brain barrier (BBB) is a critical guardian that controls what substances can pass
from the bloodstream into the brain. It is made up of specialized cells, the so-called brain
endothelial cells between blood and brain that form tight connections, allowing only certain
molecules like gases and small fat-soluble substances to pass through easily. Other essential
nutrients and larger molecules need special transport systems to get across. One of these
transport systems involves the transferrin receptor (TfR), which helps move iron into the brain.
Iron is vital for brain function, and the TfR ensures it gets where it needs to go. ApoE4 is a
genetic variant of the apolipoprotein E (ApoE) that significantly increases the risk of developing
Alzheimer's disease (AD). ApoE4 can make the BBB more permeable, meaning it becomes
leakier and less effective at protecting the brain. This can lead to various problems, including
disrupted transport of essential molecules and increased risk of brain damage.
To study how ApoE4 affects the BBB and to develop new treatments for AD, scientists use
different experimental models. These include lab-grown cells, animal models, and samples
from human patients. In my research, I used stem cells to create brain endothelial cells with
the ApoE4 genetic variant to investigate how this risk factor affects transport across the BBB
via the TfR. I found that ApoE4 changes the way membrane-bound compartments, called
endosomes, transport substances like transferrin, disrupting iron balance in the cells.
Besides working with single types of two-dimensional (2D) brain cells, I also explored advanced
models called complex in vitro models (CIVMs). These include organoids (miniature, simplified
versions of organs) and microphysiological systems, which mimic the human BBB more closely
than traditional methods, in three dimensions (3D). These models can provide valuable insights
into how diseases develop and how drugs can be designed to treat them. In my research, I
adapted and optimized tissue technologies and advanced digital tools from histopathology for
CIVMs, primarily using BBB organoids for preclinical safety tests. My work aims to increase
the translatability of the development of new treatments from non-clinical to clinical and
therefore increased the success of developing novel treatments e.g. for AD.
In summary, understanding and improving the BBB through advanced models is essential for
developing effective drugs for brain disorders like AD. These models help ensure that new
treatments are safe and effective before they reach clinical trials, ultimately benefiting patients
Diversity and compartmentalisation of monocytes and macrophages in patients with liver cirrhosis
Get PDFLiver cirrhosis is a widespread systemic condition with increasing global prev-alence. Individuals with cirrhosis are particularly vulnerable to bacterial infec-tions, which can trigger acute decompensation (AD) and acute-on-chronic liver failure (ACLF), both of which are linked to high rates of morbidity and mortality, with limited treatment options beyond transplantation. Mononuclear phago-cytes are crucial to innate immune responses and serve as a primary defense mechanism against pathogens. The study investigated the heterogeneity of macrophages and monocytes subsets and their compartment-specific varia-tions related to disease progression in liver cirrhosis. Distinct subsets identi-fied here included AXL-expressing and CD52-expressing cells, which play critical roles in regulating innate immune responses and contribute to the complex pathogenesis of immuneparesis in patients with cirrhosis. Strong correlations with clinical parameters, cirrhosis severity scores, infectious com-plications, and mortality highlight their clinical significance, and suggest their potential as biomarkers for innate immune function integrity on the one hand and as immunotherapeutic targets on the other.
Initial investigations focused on monocyte and macrophage dysfunction in AD/ACLF stages of cirrhosis, where the risk of infection and subsequent mor-bidity and mortality is highest. Previous studies by the research group showed an increase in monocytic subsets, such as M-MDSC, occurring in compen-sated cirrhosis with increasing prevalence along with disease progression and highet proportions in AD/ACLF patients, and MERTK-expressing monocytes occurring in patients with AD/ACLF. AXL-expressing monocytes were found to increase with cirrhosis progession from mild to more severe stage, but disap-pear again in AD/ACLF stage of cirrhosis. With disease progression, these dysfunctional monocytic subsets prevailed over regular monocytes in the cir-culation of cirrhotic patients in relation to certain stages of disease. These distinct subsets exhibited unique immune-regulatory functions and immune-suppressive capabilities, compared to regular monocytes. AXL-expressing monocytes demonstrated attenuated inflammatory cytokine production and T-cell activation and enhanced efferocytosis and maintained phagocytosis of E.coli. MERTK+ monocytes have immune-regulatory function and dampen the immune response. Futhermore, those monocytes showed enhanced efferocy-tosis capacity. M-MDSC exhibit immune-suppressive properties, significantly decreasing T cell proliferation, low cytokine responses and reduced bacterial uptake.
AXL, MERTK, and Tyro-3, members of the TAM receptor tyrosine kinases (RTK) family, inhibit TLR-signaling, cytokine receptor-mediated activation, and apoptotic cell removal in monocytes/macrophages. Loss of these RTK leads to liver disease with characteristic apoptotic cell accumulation. In this study, over 90% of liver macrophages expressed AXL in homeostasis, with a reduction in AXL-expressing resident liver macrophages paralleling cirrhosis progression. Interestingly, this process was reversible, as shown by changes in AXL ex-pression in patients transitioning between Child B and Child C stages.
Immunohistochemistry indicated AXL-expressing macrophages were abun-dant in hepatic plates, while MERTK-expressing macrophages were enriched in both hepatic plates and areas of fibrosis. Phenotypically, AXL-expressing hepatic macrophages under physiological conditions were mature, indicating a need for tolerance at the portal-systemic circulation barrier. The proportion of macrophages phagocytosing gram-negative E.coli decreased in cirrhosis, with AXL-expressing monocytes showing increased migratory potential.
Compartment-specific AXL-expression was also assessed in other tissues, including the gut, peritoneum, lymph nodes, and bone marrow. Intestinal mac-rophages exhibited reduced AXL-expression with cirrhosis progression, simi-lar to hepatic macrophages. Peritoneal macrophages showed lower AXL-expression but higher MERTK-expression compared to monocyte-derived macrophages (MDM). Notably, AXL+ macrophages were absent in the bone marrow but accumulated in the circulation and lymph nodes of advanced cir-rhosis patients, supporting the hypothesis of enhanced migration potential.
These findings, which suggested a stage-specific heterogeneity in monocytes and macrophages during cirrhosis evolution, and prompted an unbiased ap-proach to investigate the underlying pathophysiology of immune. The study employed single-cell RNA sequencing (scRNA-Seq) to systematically decode the stage-specific heterogeneity of circulating monocytes in cirrhosis patients. Seven monocytic clusters were identified, representing classical, non-classical, intermediate monocytes, and M-MDSC, with varying prevalences among different cirrhosis stages. These clusters exhibited distinct marker gene expressions and functions, with inflammatory responses, phagocytosis, and complement system upregulated in compensated cirrhosis but downregulated in decompensated stages, indicating immuneparesis onset.
CD52 expression on monocytes emerged as a significant finding, with en-hanced expression in compensated and NAD cirrhosis compared to healthy controls. CD52high monocytes displayed an activated state, with increased phagocytosis capacity, cytokine production potential, and adhesion/migration behavior, and presence of CD52 expressing cells was associated with surviv-al. Interestingly, CD52 expression was downregulated or absent in AD/ACLF stages. Plasma components influenced CD52-expression levels, with bacterial particles elevating CD52 expression, while AD/ACLF plasma dampened phagocytosis capacity.
The study also explored the clinical relevance of CD52-expression on mono-cytes and soluble CD52 (sCD52) in the bloodstream as non-invasive bi-omarkers for cirrhosis severity and innate immune function. Elevated phospho-lipase C (PLC) plasma levels correlated with reduced CD52 surface expres-sion and increased sCD52 plasma levels, suggesting PLC as a potential tar-get for stabilizing CD52 on monocytes. The findings highlight the significance of the CD52 pathway as a clinically relevant biomarker and potential immuno-therapeutic target in cirrhosis management.
In conclusion, the study demonstrates that with cirrhosis progression, CD52+ and AXL+ hepatic macrophages decrease while CD52+ and AXL+ circulating monocytes increase, reflecting changes in innate immune function. The study provides insights into the potential therapeutic modulation of the AXL-GAS6 and CD52-PLC pathways to enhance innate immune responses, reduce infec-tion susceptibility, and improve survival in cirrhosis patients
Tumor recognition by MR1T cells
No full textMR1T cells are a recently discovered population of MR1-restricted unconventional T cells. They are heterogeneous, express variable T cell receptors, and respond to antigens present in tumor cells of different tissue origins. To utilize their anti-tumor potential in therapy, it is essential to fully comprehend the range of MR1T recognition of tumors and identify the structure of tumor-related antigens.
My PhD project aimed to characterize the breadth of MR1T reactivity towards different types of cancer cell lines, organoids, and primary tumors. MR1T cells demonstrated different recognition patterns, with some examining a broad cross-reactivity between almost all tested tumors. In contrast, others were only activated in the presence of a small subset of tumor cells.
A significant finding was that some cancer cells had a far superior ability to stimulate the majority of MR1T clones. This led us to investigate the features of highly stimulatory tumors, focusing on the metabolic changes that could lead to generation of MR1T antigens. We discovered critical metabolic pathways significantly altered in highly stimulatory tumors, including the metabolism of arachidonic acid, glutathione, taurine and hypotaurine, and pyrimidines. These findings shed light on the mechanism of MR1T recognition of cells with altered metabolism, which allows for the accumulation of specific metabolites that give rise to MR1T antigens. These studies have implications beyond cancer, as changes in cell metabolism are also observed in other diseases, including infectious and autoimmune diseases
Chiral recognition on molecular nanowires from square planar platinum(II) complexes
No full textThis thesis presents the preparation and structural assignment of a novel chiral Pt(II) complex A by introducing an atropisomeric moiety at the periphery of monodentate isocyanide ligands. The overall charge-neutral complexes were completed by the bis-anionic tridentate trifluoromethyltriazolylpyridine (trzpy) ligand. A set of reference complexes comprised of new combinations of monodentate alkynyl- or isocyanide ligands with the known tridentate hexbzimpy and trzpy ligands was prepared. Absorption and emission spectroscopy of the resulting 1 and 4, showed the aggregate formation depending on concentration and solvent polarity. Furthermore, the novel atropisomeric Pt(II) complex, complex A, displayed the anticipated solvent-dependent aggregation towards chiral nanostructures. These nanostructures were investigated by scanning electron microscope imaging, NMR spectroscopy, circular dichroism, and UV vis absorption. Enantiospecific sensing of selected VOCs was investigated from the nanostructured system of complex A.
Indeed, interactions of enantiomeric small molecules with the crystal lattice provoked amplified changes in the absorption of complex A, exhibiting enantiospecific sensing behavior. In four different VOCs, namely R/S-2-BuOH, R/S-1-PhEtOH, R/S-α-pinene, and R/S-limonene the R and S enantiomers could be differentiated. Complex A aggregated to form a colloidal dispersion, which formed a new metal—metal-to-ligand charge transfer absorption band at 385 nm. Addition of enantiomers significantly affected the absorbance, which allowed for direct differentiation by UV-vis absorption measurements. The effect could also be measured by circular dichroism, further highlighting the stereospecific interactions between each enantiomer with aggregated complex A. UV-vis titrations of each selected VOC enantiomer revealed enantiospecific changes at sub-stoichiometric amounts. For the first time, reversible enantiospecific sensing has been realized from a molecular nanostructured material, especially from less functionalized enantiomer pairs (R/S-α-pinene, and R/S -limonene)
B cell responses in vaccination and chronic viral infection
No full textIn order to develop a suitable and tailored vaccine providing protection against a disease, it is key to understand the mechanisms that underly immune control of the infection as well as the mode of action of the vaccine. To address both elements, we first developed a tool to facilitate the study of lymphocyte subsets in vivo. Therefore, we engineered Adeno-associated viral vectors (AAVs) to deliver various depletion antibodies (depletion-AAVs) targeting lymphocyte subsets that allow for the long-term elimination of such after a single administration. Depletion-AAVs permit the simultaneous elimination of several lymphocyte subsets and can be administered to mice of different genetic background. By employing depletion-AAVs, we gained new insights into the mechanisms that underly immune control of chronic viral infection and identified the fundamental role of B cells therein. Furthermore, we provided a detailed characterization of the B cell response induced by a novel and promising vaccine candidate, the recombination Orf virus vector, which could ultimately serve to prevent chronic infection
Physiological differences in cardiopulmonary exercise testing between children and adults
No full textPurpose: This study examines age- and sex-related physiological differences in cardiopulmonary exercise testing (CPET) between children and adults, focusing on ventilatory thresholds (VT) and oxygen uptake efficiency slope and plateau (OUES; OUEP).
Methods: The cross-sectional analysis comprised 24 children (7–11 years), 20 moderately-trained (MTA) and 20 well-trained (WTA) adults (20–30 years). They performed a maximal CPET on a cycle ergometer, while respiratory responses were measured. Linear regression models analyzed differences by age and sex of the key outcome parameters VT1, VT2, OUES and OUEP.
Results: Children exhibited higher absolute VO2 at VT1 (d=.66) and VT2 (d=.58) values than MTA but slightly lower VO2 at VT2 values compared to WTA (d=.35). Adults demonstrated higher OUES (MTA: d=.37; WTA: d=1.45) and OUEP (MTA: d=.81; WTA: d=.60) values than children. However, children had higher relative OUES when adjusted for body mass (OUESrel) (MTA: d=.1.80; WTA: d=.87). Males demonstrated higher values as females for VO2 at VT2 (d=.81), OUES (d=.79) and OUEP (d=.41), respectively. In contrast, females had higher VO2 at VT1 (d=.59) and VT2 (d=.44) relative to VO2peak as males.
Conclusion: These findings suggest that compared to adults, children rely more on oxidative metabolism, reflected in higher ventilatory thresholds relative to their aerobic capacity. Absolute OUES and OUEP increased with age, but OUESrel values indicate that maturation influences efficiency more than body mass, reflecting underlying metabolic and physiological differences. These age- and sex-specific patterns highlight the need for further longitudinal research to clarify the roles of growth and training on these parameters.
Keywords
CPET, children, Ventilatory Thresholds, Oxygen Uptake Efficiency, Maturatio