Naturwissenschaften
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Item The reactive pyruvate metabolite dimethylglyoxal in experimental disease models and the role of Ilvbl in its generation in the brain(2025) Costalunga, RiccardoReactive glucose metabolites are involved in neurological complications of diabetes by the generation of advanced glycated end products (AGEs), which are formed by the interaction between α-dicarbonyls and proteins. AGEs induce oxidative stress, inflammation and tissue damage and have been associated with neuropathy, nephropathy and retinopathy. So far, only the α-dicarbonyls 3-deoxyglucosone, glyoxal and methylglyoxal have been recognized as reactive glucose metabolites and associated with complications in diabetes. Only recently, the α-dicarbonyl dimethylglyoxal (DMG) has been categorized as mammal cellular pyruvate metabolite, and its levels were higher in the plasma of type-1 diabetic mice and in the serum of patients with diabetes. In this thesis, I investigated the α-dicarbonyl DMG in mouse models under pathological conditions and its metabolic pathway in mammals using liquid chromatography coupled to tandem mass spectrometry (LC-MS2). Here, plasma DMG concentrations were upregulated in mouse experimental models of type-1 and type-2 diabetes. In contrast, high-fat diet did not influence the serum levels of DMG, suggesting that diabetic conditions – but not obesity itself – are associated with plasma DMG upregulation and accumulation. Moreover, DMG levels were enormously augmented in the ipsilateral side of a mouse model of hyperglycemic stroke compared to sham control. Interestingly, DMG levels were also higher in the contralateral hemisphere of the brain of mice with stroke compared to sham controls, showing that the contralateral hemisphere is also affected by ischemic stroke. Furthermore, the current study confirmed that DMG is a post-glycolytic product in mammals and its levels are increased under hypoxic conditions in vitro. Then, I investigated the role of the gene ilvB acetolactate synthase-like (Ilvbl), the mammal orthologue gene of acetolactate synthase that generates DMG from pyruvate in bacteria, yeast and plants. Importantly, Ilvbl knockout reduced DMG levels in the brain of mice with type-1 diabetes or hyperglycemic stroke, showing that Ilvbl has conserved its role in DMG generation in mammals. Moreover, DMG interacted with lysine, generating the glycated amino acid Nε-3-hydroxy-2-butanonelysine (HBL), confirming that DMG is a reactive compound and can glycate proteins generating AGEs. Thus, DMG induced oxidative stress and neuroinflammation in mouse hippocampal neuronal (HT-22) cells, probably based on protein glycation. In conclusion, this study characterizes the α-dicarbonyl DMG in experimental models under pathological conditions, showing that DMG could play a significant role in diabetic complications and ischemic stroke complications. DMG is the only α-dicarbonyl generated after glycolysis, and the current discovery could explain why cells consuming lactate – such as neurons – are not protected by dicarbonyl stress. Importantly, this study shows that ILVBL plays a significant role in the DMG generation from pyruvate in the brain of acute or chronic hyperglycemic mice. Further investigation on DMG and the attenuation of its concentrations may lead to improvement in diabetic and ischemic stroke complications.Item The C5aR2 pathway as a novel checkpoint for B-2 cell activation in early autoimmunity(2025) Schanzenbacher, JovanItem High-content screen for cardiovascular modulators in zebrafish (Danio rerio)(2024) Vedder, Viviana LuisaOver the past two decades, cardiovascular diseases (CVDs) have remained the leading cause of death worldwide. Among these diseases, congenital heart disease is the most common type of human birth defect, affecting 1 in 100 live-born infants. It is crucial to identify new therapeutic targets and treatments for CVDs. Zebrafish are a suitable model for this task, as they can provide new insights into CVDs. Further, their small size and translucency make them an ideal model for high-content drug screenings. In this study, a phenotype-based high-content screening approach in zebrafish was established to identify cardiovascular modulators. Utilizing the ‘Acquifer Imaging Machine‘, 1,280 compounds of the Prestwick Chemical Library were screened for angiogenesis and heartbeat phenotypes. The previously established type III receptor tyrosine kinase inhibitor sunitinib malate, which inhibits angiogenesis in zebrafish, was used as a positive control. Additionally, the competitive 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) inhibitor atorvastatin, which was previously shown to cause severe heart phenotypes in zebrafish, served as a positive control for heart rate (HR) and heart morphology. HR was selected as a screening phenotype under the assumption that morphological and functional changes in the heart during development would result in altered HR. In search of angiogenesis modulators, blood vessel diameters of treated fish were measured for 320 of the 1,280 tested compounds. Application of different filters for known toxicities, previously published results and unknown targets, led to the identification of 11 promising hit compounds. Three of these compounds, namely desonide, oxibendazole, and azlocillin sodium salt, directly targeted angiogenesis by significantly reducing the diameter of intersegmental vessels. The remaining nine compounds affected the diameter of the dorsal aorta and/or dorsal vein. Of the 134 compounds significantly altering HR, 21 compounds repeatedly induced significant HR alterations in two different transgenic zebrafish lines. In this study, two main target clusters were identified for HR modulators: the histaminergic receptor H1 (HRH1) and the glucocorticoid receptor (NR3C1). While HRH1 is commonly associated with allergic reactions, it has also been linked to CVDs. All antagonistic hit compounds targeting HRH1 caused significant bradycardia with moderate to severe dose-dependent teratogenicity. In situ hybridization for various hrh probes revealed that hrh1 was the only detectable hrh in the heart at 3 days post fertilization (dpf), indicating its involvement in heart development. Additionally, the heart analysis tool pyHeart4Fish showed chamber-specific effects of HRH1 antagonists. Collectively, the data suggests that hrh1 plays a role in heart contractility and heart size. However, further investigation on the mechanism of action is necessary to comprehend how Hrh1 is involved in cardiogenesis and what long-term effects HRH1 antagonists can have on the developing embryo to determine drug safety for pregnant women. NR3C1 is a ligand-activated transcription factor known to be involved in inflammation, metabolism, and stress response. In this study involving zebrafish larvae, a group of six NR3C1 agonists was found to significantly increase HR at 48 hours post fertilization. While previous research had identified nr3c1's involvement in heart development in zebrafish, its role in arrhythmias remained unclear. Here, expression of nr3c1 was detected in the larval heart at 5 dpf using in situ hybridization. Further analysis using pyHeart4Fish revealed that NR3C1 agonists induced chamber-specific phenotypes, including atrioventricular block. A homology model of zebrafish Nr3c1 was also developed, which suggested that the agonists known to bind in humans may also bind in zebrafish. These findings support the use of zebrafish as a screening model for cardiovascular phenotypes and highlight the potential role of nr3c1 in CVDs.Item Combining in-depth immune profiling and multi-omics approaches identifies distinct signatures in the early stage of Systemic Sclerosis(2025-08-13) Ohmes, Justus MaximilianItem Single cell sequencing in development and disease(2025-05-20) Balachandran, SaranyaItem 850 nm Fourier domain mode-locked laser for ophthalmic optical coherence tomography imaging(2025) Klufts, MarieNon-invasive imaging techniques have become essential in medical diagnostics over the past few decades. Among these, Optical Coherence Tomography (OCT) offers micrometer resolution with millimeter-scale depth penetration, making it particularly valuable in ophthalmology. OCT captures backscattered light to generate 3D volumes. For eye imaging, wavelengths around 850 nm are ideal due to minimal absorption by the vitreous and high scattering in the upper retinal layers. Imaging speed is also critical, as faster speeds reduce motion artifacts. Swept-source OCT, using wavelength-tunable lasers, enables high-speed imaging. Fourier Domain Mode-Locked (FDML) lasers providing megahertz-level scan rates are ideal for this purpose. This thesis explores the development and application of FDML lasers for ophthalmic imaging. Unlike other tunable lasers, FDML lasers have a unique design that stores a full sweep in their fiber cavity for hundreds of round trips, avoiding rebuilding of lasing from spontaneous emission after tuning to new wavelengths offering high phase stability and long coherence length necessary for high quality OCT images. A new megahertz FDML laser at 850 nm would merge the unique advantages of this wavelength with the proven benefits of FDML lasers allowing for a low latency, dynamic view of the retina, opening new doors for real-time diagnostics. The first part delves into the challenges of developing an FDML laser around 850 nm, addressing issues like polarization mode dispersion, chromatic dispersion, and low gain/loss ratios. These factors contribute to the complexity of managing short wavelength OCT lasers, which explain their scarcity to date. The second part presents in-vivo ophthalmic OCT imaging results, with comparisons to other imaging techniques. The newly designed FDML laser demonstrates strong performance for OCT imaging, achieving an axial resolution below 10 µm, sensitivity above 84 dB, and a ranging depth of 1.4 cm. Also, its high phase stability, with a time jitter of 25 ps over 1,000 sweeps, makes it suitable for phaseresolved techniques. Retinal images were captured at 414,000 axial scans per second using a master-slave based calibration technique, at 828 kHz with bidirectional sweeping, and at 1.7 MHz using optical buffering with a single-k-calibration technique. While increased scattering at 850 nm limits choroidal imaging, most retinal layers of interest are clearly visible. This FDML laser highlights the advantages of short-wavelength, high-speed imaging and paves the way for new applications.Item Multi-omics analysis uncovers split formation and keratinocyte detachment as key drivers of long-lasting cellular effects in pemphigus vulgaris(2025-08-11) Guo, SenPemphigus Vulgaris (PV) is an autoimmune disease in which antibodies mistakenly target the adhesion proteins Desmoglein 1 (DSG1) and/or Desmoglein 3 (DSG3) on skin cells, leading to the loss of cell-cell adhesion and causing blistering. While the molecular changes following antibody binding in PV remain poorly understood, we investigated these downstream effects by analyzing gene and protein responses in two experimental models: human primary epidermal keratinocytes (HPEKs) and human skin organ culture (HSOC). Samples were treated with either PX43, a human-derived antibody fragment targeting DSG1 and DSG3, or AK23, a mouse-derived DSG3 antibody, alongside control treatments. In the HPEK model, PV antibody treatments did not trigger notable changes compared to controls at 5, 10, or 24 hours. However, in the HSOC model, only PX43 induced tissue splitting and significant changes in gene and protein expression, particularly in pathways linked to inflammation and immune signaling (e.g., TNFα, Interferon α/γ, IL2-STAT5, IL5-STAT3). Importantly, these molecular changes resembled those seen in wounded or inflamed skin, suggesting that physical damage from blister formation—not the antibody binding itself—is the primary driver of downstream cellular responses. This study reveals that tissue injury may be the main trigger for disease progression in PV, pointing toward new therapeutic targets that focus on modulating the wound response and inflammation, rather than the antibodies alone.Item Exploring structure-based discovery of antivirals targeting Human cytomegalovirus (HCMV)(2025-07-28) Thiyagaraj, DineshHuman cytomegalovirus (HCMV) causes widespread infections globally, typically remaining asymptomatic and latent. However, under conditions of immunosuppression, HCMV can reactivate and cause severe disease. The United States Food and Drug Administration (USFDA) has approved six antivirals for prevention and/or treatment of HCMV infection: Ganciclovir, Valganciclovir, Cidofovir, Foscarnet, Letermovir (only prophylaxis), and Maribavir. Despite their efficacy, these antivirals face one or more of the following challenges: toxicity, efficacy, and the emergence of drug resistance. This highlights the urgent need for novel antivirals that are both effective and safer, targeting essential viral proteins to minimize resistance. This study aimed to extend the available HCMV drugs by establishing structure-based drug design pipeline for three distinct HCMV protein targets, namely the pUL94/pUL99 complex, pUL98 and pUL77. I worked towards the structural characterization of two HCMV targets, employing crystallization methods in combination with crystallization enhancing scaffolds as “crystallization chaperones” as well as alternative methodologies like cryo-EM single particle analysis. The resulting atomic structures will pave the way for virtual screening of small molecules to identify potential antiviral candidates. Additionally, we aimed to establish a semi-automated virtual screening workflow and screen for protein-protein interaction inhibitors against HCMV pUL77. I initially expressed pUL98 in E.coli and purified it to homogeneity. Since initial robotic crystallization experiments remained unsuccessful, I employed sybodies and megabodies as “crystallization chaperones” for pUL98. Unfortunately, crystallizing pUL98 with sybodies or megabodies did not yield diffraction-quality crystals. For the pUL94/pUL99 complex sybodies were already available at the beginning of this thesis, and as crystallization also remained unsuccessful, we started a collaboration with the group of Maya Topf at CSSB; Hamburg, to characterize the complex structure using cryo-EM single particle analysis. To increase particle contrast in cryo-EM, I used the existing sybodies to engineer legobodies binding pUL94/pUL99, but the complex showed significant compositional and conformational heterogeneity, limiting the obtained resolution to ~6Å. Finally, I used the reported cryo-EM structure of the pUL77 pentamer to establish a consensus virtual screening workflow for pUL77 using multiple scoring functions, docking tools and additional screening parameters. This allowed us to identify consensus poses from two docking tools and attempt to improve probability of true-positive hits. Clustering algorithms were used to scrutinize the molecules further, enhancing the hit identification rate and lead selection. The shortlisted molecules from this screening workflow have been ordered and will be tested by our collaboration partners in cell culture models for HCMV infection. In conclusion, this work established a workflow for virtually screening molecules with improved hit rates, moving beyond reliance on docking scores alone. This workflow aims to enhance the efficiency of structure-based antiviral discovery targeting HCMV infection.Item Variability in biological correlates of nightmares and implications for the development of new treatment options(2024) Sayk, Clara Anna Luiseare very common in both the general population and individuals with psychiatric disorders. They can cause distress, sleep disturbance and impairment in daily functioning. Several biological correlates of nightmares have been investigated in the last decades, such as brain activity during sleep, changes in heart rate, electrodermal activity or cortisol levels. All of these measures indicate some form of hyperarousal which, together with impaired fear extinction, is indeed one of the central components of the integrative etiology model for nightmares. However, it is still unclear, how exactly hyperarousal and nightmares interact, i.e., whether hyperarousal actually is a causal mechanism or rather a byproduct of other processes. Likewise, it is still unknown whether it can be influenced through interventions for nightmares, such as imagery rehearsal therapy or - directly during sleep - with some form of stimulation or targeted memory reactivation (TMR). The aim of the three studies that constitute my thesis was to examine biological correlates of nightmares, especially cortical hyperarousal in individuals with frequent nightmares from different samples and the effects of imagery rehearsal therapy (IRT) and TMR on physiological correlates and nightmare symptoms using polysomnography and high-density EEG-measurements. The first two studies focused on physiological correlates of nightmares and the effects of IRT. Study 1 addressed how physiological correlates differ between individuals with frequent nightmares and healthy controls and how an 8-week IRT group intervention influences nightmare symptoms and physiological correlates. Participants with frequent nightmares showed increased beta and gamma activity compared to healthy controls and their gamma activity during REM was reduced after the intervention. In study 2, a similar paradigm was used to investigate the effects of imagery rehearsal therapy as an add-on to inpatient treatment for individuals with borderline personality disorder. While this study did not show any changes in physiological correlates, the intervention group experienced a significantly more pronounced reduction in anxiety, intrusions and hyperarousal. Study 3 investigated the effects of experimentally manipulating these biological correlates. More specifically, whether reactivating a relaxation exercise with TMR in participants with frequent nightmares reduced hyperarousal and nightmare symptoms. While the reactivation did lead to a reduction in spindle count and density, another form of cortical hyperarousal, there was no influence on nightmare symptoms. Taken together, I could demonstrate that i) increased (cortical) arousal plays an important role as biological correlate and shows sensitivity to treatment in various samples with frequent nightmares (participants with frequent nightmares but no severe co-morbidities as well as individuals with borderline personality disorder and frequent nightmares), ii) IRT is successful in reducing gamma activity and psychological arousal alongside nightmare symptoms and iii) the reactivation of relaxation associated contents influences spindle activity which is even associated with changes in subjective sleep disturbance, indicating that this is a promising novel technique to target hyperarousal. Future research should therefore focus on further attempts to experimentally manipulate cortical hyperarousal by stimulation methods or by reactivating IRT and should also include other factors of the integrative model of nightmare etiology, especially fear extinction.Item Untersuchung des Einflusses dreidimensionaler Kultivierung auf Neuronen und Schweißdrüsenzellen mit Fokus auf elektrophysiologischer Funktionalität(2025) Panzer, JörgTissue-Engineering und innovative Kulturmethoden haben das Potential, in vielen Bereichen der klinischen Forschung zu neuen Therapiemöglichkeiten zu führen. Dazu gehören unter anderem die Schmerzforschung mit der Suche nach molekularen Zielen für Medikamente, sowie der Forschungsbereich der Wundheilung und Hautrekonstruktion. Die Umgebung der in vitro kultivierten Zellen ist dabei ein essentieller Faktor für deren Differenzierung und Funktion. In der vorliegenden Arbeit wurde für die kommerzielle neuronale Zelllinie F11, sowie für humane Schweißdrüsen-abgeleitete Stammzellen (sweat gland derived stem cells, hSGSCs), untersucht, ob die 3D-Kultivierung in Form von multizellulären Sphäroiden einen Einfluss auf die gewebsspezifische Differenzierung hat. Um multizelluläre Sphäroide zu erzeugen, wurden die Zellen mit der liquid overlay Methode in Mikromulden aus Agarose kultiviert, was bei beiden Zelltypen zu einer spontanen Aggregation führte. Beide Zelltypen wurden in verschiedenen Medien in 2D und 3D kultiviert. Mittels RT-qPCR wurden auf mRNA-Ebene zelltypspezifische Genpanels analysiert, die Differenzierungsstatus und elektrophysiologische Aktivität ausgerichtet waren. Für die F11-Zellen zeigte sich bei zwei untersuchten Differenzierungsmarkern eine deutlich veränderte Expression. Das neuronale Strukturprotein Neurofilament M (Nefm) wurde in der 3D-Kultur vermehrt exprimiert, der Ca2+-Sensor Synaptotagmin 1 (Syt1) hingegen vermindert. Die Expression der weiteren Differenzierungsmarker sowie der untersuchten Ionenkanäle zeigte keine Unterschiede zwischen 2D- und 3D-Kultur. Diese Ergebnisse lassen nicht auf eine veränderte Funktionalität der Zellen durch 3DKultivierung in Sphäroiden schließen. Um die elektrophysiologische Funktionalität der Zellen zu untersuchen, wurde automatisiertes Patch-Clamping angewendet. An dissoziierten F11-Zellen konnten erfolgreich Messungen durchgeführt werden, die Sphäroide jedoch ließen sich mit dieser Methode nicht analysieren. Die Frage nach einer veränderten elektrophysiologischen Funktionalität durch 3D-Kultivierung konnte somit nicht abschließend geklärt werden. In den untersuchten hSGSCs konnte die Expression von wichtigen funktionellen Markern sekretorischer Schweißdrüsenzellen gezeigt werden. Die 3D-Kultivierung hatte einen deutlichen Effekt auf einige dieser Marker. Der muskarinerge Acetylcholinrezeptor M3 (CHRM3) und der calciumgesteuerte Calciumkanal ORAI1 wurden in 3D-Kultur verringert exprimiert, der calciumgesteuerte Chloridkanal Anoctamin 1 (ANO1, auch TMEM16A) wurde verstärkt exprimiert. Die Ergebnisse der Expressionsanalyse ließen auf eine veränderte Funktionalität in 3D- gegenüber 2D-Kultur schließen. Im PatchClamping konnten, wie bei F11-Zellen, nur Einzelzellen analysiert werden. Zur weiteren Untersuchung der Funktionalität wurde ein Calcium-Imaging-Assay durchgeführt. Dabei konnten keine signifikanten Unterschiede in der maximalen Calciumkonzentrationszunahme beobachtet werden. Der Anteil an stimulierbaren Zellen unterschied sich ebenfalls nicht signifikant voneinander. Die Kultivierung in einem Differenzierungsmedium führte bei hSGSCs zu einer erhöhten CHRM3-Expression in der Zellpopulation sowie einem erhöhten Anteil an MCH-reaktiven Zellen.Item Speech comprehension through the lens of auditory and motor brain rhythms(2025) Lubinus, Christina Anna-LenaItem Metabolic and cellular factors determining the therapeutic effects of dimethyl fumarate(2025-06-12) Kosińska, JoannaItem Lipidomic and structural characterization of the cell wall of Streptococcus pneumoniae(2025-05-13) Alshaar, BelalStreptococcus pneumoniae (Spn) is a Gram-positive bacterium that naturally colonizes various niches within the human body, but can also lead to infections with varying degrees of symptoms. Despite the availability of vaccines, Spn infections remain a significant health concern, exacerbated by the rising threat of antibiotic resistance. This growing challenge underscores the urgent need to explore new drug targets that are common across different strains. A particularly promising target is the pneumococcal cell wall, which has become a central point of structure-focused research. The cellular membrane, a key component of this wall, plays a crucial role in host-pathogen interactions. Nevertheless, the precise quantities of its components are still not well understood. This thesis presents a first-of-its-kind quantitative analysis of the pneumococcal lipidome, conducted in close collaboration with the group of Prof. Dr. Sven Hammerschmidt from the University of Greifswald. The implementation of a standardized pipeline applicable for in-depth microbial lipidomics on pneumococcal samples is described. Further, I examined how the knockout of selected genes influenced the membrane lipid composition. As a proof of concept, the wild-type serotype 2 strain S. pneumoniae D39 was compared to three mutant strains with single gene knockouts. The targeted mutant strains investigated here are: 1) tacL: TacL is responsible for the attachment of the polymeric teichoic acid chain on the glycolipid anchor, thus forming the lipoteichoic acid (LTA); 2) lgt: Lgt (diacylglyceryl transferase) catalyzes the diacylation of preprolipoproteins via a thioester bond by transferring a diacylglycerol moiety from a phosphatidylglycerol (PG) precursor; 3) cps: enzymes of the cps cluster are responsible for capsule polysaccharide formation. To date, such quantitative lipidome studies have not been performed for Spn. Methodically, shotgun lipidomics was employed and the development of a customized mix of internal standards ensured accurate quantitative analysis. The analysis allowed quantification of more than 100 lipids across the following six classes: diacylglycerol, glucosyldiacylglycerol (GlcDAG), galactosylglucosyldiacylglycerol (GalGlcDAG), cardiolipin, phosphatidylcholine and PG, with GlcDAG and GalGlcDAG being the predominant classes. Gas Chromatography-Mass Spectrometry (GC-MS) and Thin Layer Chromatography in conjunction with high-resolution tandem mass spectrometry were further utilized for the validation of identified lipid species. The lipid composition of tacL and lgt strains showed no significant changes compared to the wild type, while the non-encapsulated strain exhibited significant adaptations. Another aim of this thesis was to optimize a GC-MS method for the accurate quantification of pneumococcal wall glycopolymers, particularly wall teichoic acid and lipoteichoic acid. This is a challenging task for researchers in the field since decades. This quantification technique is anticipated to provide a basis for studying enzymes that affect teichoic acid levels without using radioactive materials in cultures and may also be used for capsule polysaccharide quantification, advancing our understanding of pneumococcal cell wall regulation. Preliminary results from this optimized method have already provided insights into how LytR, which plays an essential role in attaching the wall teichoic acid to the peptidoglycan, influences the teichoic acids ratio. In summary, a robust quantitative method for lipidome analysis has been established, along with a developed method which delivered the first successful proof of concept for teichoic acids quantification in Spn. These approaches enable future investigations into membrane homeostasis and biosynthesis regulation in other mutants or under various growth conditions.Item Antibody and B cell development after vaccination against COVID-19(2024) Buhre, Jana SophiaDuring the COVID-19 pandemic, new mRNA- and adenovirus-based vaccine formats encoding the viral spike protein (S) were developed. These newly developed vaccine formats have helped to successfully combat the pandemic. However, there is a high rate of breakthrough infections, which is why the vaccine induced immune responses should be investigated in detail. Both vaccine formats induce antibodies that have neutralizing functions via their Fab-part. The effect of IgG antibodies also depends on Fc-mediated effector functions, which are influenced by the IgG subclass and its Fc N-glycosylation pattern. At the beginning of this work, it was known that both vaccines induce IgG1 and IgG3 antibodies initially and especially after two vaccinations, but information on long-term antibody responses was lacking. The aim of this work was therefore to longitudinally describe and characterize the vaccine-induced IgG subclasses, their Fc N-glycosylation and their Fc-mediated effector functions. It was shown that the mRNA vaccines produced significantly higher IgG1 and IgG3 antibody levels in the short term compared to adenovirus-based vaccination, but that these levels equalized in the long term. In contrast to this equalization, late emerging IgG4 antibodies were only observed in people who received two mRNA vaccinations. It is generally assumed that IgG4, in contrast to IgG1 and IgG3, has a more inhibitory function. In functional assays, anti-S IgG1 was confirmed as a strongly activating subclass. In contrast, IgG4 antibodies, which increased with every vaccination, showed activating but also inhibitory immunomodulatory effects. These need to be further investigated in the future in order to better assess their role in the long-term vaccination response. In addition, a dynamic development of glycosylation was observed: Highly galactosylated and sialylated IgG antibodies appeared shortly after each vaccination, while significantly lower galactosylated and sialylated IgG antibodies were found in the long term. This wave pattern was described for all IgG subclasses and indicates that differently glycosylated antibodies exert different effector functions, which could mean a new general understanding of early and late antibody responses after vaccination. In contrast to this dynamic, the new vaccines were only able to induce afucosylated antibodies temporarily and only after the first vaccination. By investigating a cohort of patients with inflammatory diseases who received tumor necrosis factor (TNF) inhibitors during vaccination, the influence of TNF on the longitudinal antibody response and thus also on B-cell differentiation could be described. The patients showed lower IgG levels, altered antibody glycosylation patterns and reduced Fc-mediated effector functions both in the short and long term after repeated vaccination. Anti-TNF therapy not only reduced the long-lived IgG response, but also the short-lived IgG response resulting from the re-activation of memory cells. Accordingly, an increased risk of breakthrough infection was observed in patients treated with anti-TNF. These results suggest that patients receiving anti-TNF therapy may benefit little from a booster vaccination.Item Aparecium: Revealing the role of the zona incerta in central thyroid hormone action(2025) Maier, JuliaThe importance of thyroid hormones (THs) for regulation of body temperature and energy metabolism as well as brain functions such as mood is well established. This is most evident in hypo- or hyperthyroidism, which have severe consequences on these parameters. THs exert their effects via thyroid hormone receptors α (TRα) and β (TRβ). Similar to altered ligand availability, mutations in these receptors lead to several deficits, such as defaults in neuronal development and regulation of body temperature, as well as psychomotor alterations. However, it often remains unknown whether defects are caused by TH actions directly on tissue level or centrally in the brain, and in the latter case, which brain regions mediate the central effects of THs. To address this question, PET/CT scans of mice undergoing treatment with T3 were conducted and showed activation of the Zona Incerta (ZI), a region of the subthalamus, indicating its role in mediating effects of THs. To further investigate the effect of THs in the ZI, TH signalling was inhibited by introducing a dominant-negative TRα1 via adeno-associated virus (AAV) injection into the ZI. In a separate set up, inhibition was specific to dopaminergic neurons by injecting the AAVs into tyrosine hydroxylase-Cre mice. Analysing these mice revealed that inhibited TH signalling in the ZI caused an increase in basal metabolic rate (BMR) with increased fasting weight loss without affecting body temperature. In addition, it resulted in a chronic stress-like state, in which serum corticosterone was elevated, and a partial anxiety phenotype was present, as habituation to stressful situations was impaired. However, none of these effects were observed in the conditional model, demonstrating that they were not mediated by dopaminergic neurons. Taken together, the study identifies a new brain region for central actions of THs, the ZI, and implicate it as a key brain region in TH-meditated control of behaviour and energy metabolism.Item Gene-environment modifiers in Parkinson's disease(2025) Gabbert, CarolinItem Comparative analysis of host response in tuberculosis across species(2024-10-24) Tijani, Hawanot OlaitanIn tuberculosis (TB) studies, the extent to which host genome as well as transcriptome contribute to susceptibility and pathology has not been clearly defined. Globally still one of the most abundant infectious disease, numbers of TB cases caused by drug resistant agents of the Mycobacterium tuberculosis (M. tuberculosis) complex are increasing especially with onset of emerging and re-emerging viral diseases and other comorbidities. Our study aims to identify host specific differences in TB disease susceptibility and pathogenesis. Previously, we and others have demonstrated the detrimental role of neutrophils in necrosis, tissue damage and bacterial spread. We hypothesized that cell death modalities during the interaction of neutrophils and other myeloid cells in the lung determines pathogen restriction or spread and ultimately, disease exacerbation. We therefore designed an integrative systems biology approach from genome to cellular, tissue and animal model to better understand TB in vitro and in vivo. Inbred female congenic mice differing in their susceptibility to M. tuberculosis infection were studied before, during and after infection and compared to human leukocytes and RNA samples from excised lung tissue. Murine bone marrow derived macrophages from wild-type B6 in comparison to susceptible C3HeBFeJ and B6.C3Hsst1 mice showed differential responses to M. tuberculosis. Upon aerosol infection with M. tuberculosis, immune-competent but susceptible B6.I-9.3.19.8 and B6.C3Hsst1 had bigger lung lesions and higher bacterial loads than resistant B6 mice. Immune cell phenotyping of murine lung samples characterized by flow cytometry and immunohistochemistry revealed distinct composition of immune cells between susceptible and resistant mouse strains. Importantly, human PMN and PBMCs showed infection specific transcriptional profiles in vitro skewed towards active phagocytosis. Comparative analyses of both murine and human transcriptome identified unique genes for each data set and shared genes across the samples. Taken together, our findings will contribute to better understand TB disease processes in order to break disease transmission, reducing bacterial burden in active TB patients, shortening treatment duration, and eventually preventing disease development in latent TB cases.Item Multidrug resistance, population structure, and epidemiology of Mycobacterium tuberculosis complex strains from West Africa(2025-02-25) Blankson, Harriet Naa AfiaTuberculosis (TB) remains a global public health challenge, impacting millions of individuals and placing a substantial burden on healthcare systems worldwide. The causative agents of TB, Mycobacterium tuberculosis complex (MTBC) strains, engage in a complex interplay of factors that influence its transmission, evolution, and the emergence of drug-resistant strains. Despite commendable progress in TB control efforts, the persistent threat of multidrug-resistant TB(MDR-TB), characterized by resistance to both isoniazid (INH) and rifampicin (RIF), has significantly complicated treatment protocols. Recent recommendations by the World Health Organization (WHO) advocate for a new all-oral 6-month regimen to address MDR-TB. However, concerns arise with the development of resistance to fluoroquinolones (FQs) and bedaquiline (BDQ), potentially jeopardizing the regimen's efficacy. Documented outbreaks of MTBC strains, particularly of MDR strains, underscore the urgency of monitoring the transmission of MTBC strains, as it can impact diagnostics and treatment strategies in affected regions. Specific strains within MTBC lineages may exhibit unique traits, such as varying minimum inhibitory concentrations (MIC) or inherent resistance to specific drugs. Understanding the circulating MTBC strains in a country, their drug resistance profiles, and their evolutionary dynamics is imperative for effective TB management. To close these knowledge gaps, this thesis seeks to explore the multifaceted landscape of TB through epidemiological, molecular, and clinical perspectives. The research aims to unravel the genomic intricacies of MTBC strains, by investigating the transmission dynamics of rifampicin-resistant (RR)/MDR-TB in Sierra Leone and exploring the transmission dynamics and drug resistance patterns of the sublineage 4.6.2.2 Cameroon. By shedding light on these aspects, this thesis seeks to contribute to enhanced diagnostics and more effective treatment strategies and ultimately support the global mission to eradicate TB. In the study on RR/MDR-TB in Sierra Leone, whole genome sequencing (WGS) revealed high levels of drug resistance, with one in four strains being resistant to all first-line anti-TB drugs. While no FQ resistance was detected, five strains exhibited resistance to BDQ/clofazimine (CFZ) due to mutations in the Rv0678 gene. The study also revealed a greater diversity of drug resistance mutations, including borderline INH and RIF resistance mutations, which can potentially influence treatment options. The high cluster rate of over 40% indicated ongoing transmission of RR/MDR-TB strains, contributing to the burden of RR/MDR-TB in the country. Analysis of the 238 MTBC strains revealed a high diversity of strains in Sierra Leone. The presence of six major lineages (L) of MTBC strains (L1= 4%, L2 = 9%, L3= 0.8%, L4= 62%, L5= 2.9% and L6= 21%) were identified in Sierra Leone. Mycobacterium tuberculosis (Mtb) strains constitute 56%, while Mycobacterium africanum (Maf) L6 strains, account for 21% of MDR MTBC strains, which suggest a longitudinal outbreak with specific branches exhibiting resistance to multiple drugs, including BDQ/CFZ. Despite the high diversity, strains of certain sublineages 4.1.2.1. Haarlem, 4.8 mainly T and 2.2.1 Beijing Ancestral 3 and 6.3.3 West Africa 2 were implicated in the ongoing MDR transmissions. The global population structure and phylogeography of strains of the Cameroon sublineage were also investigated using WGS. The strains were classified into eight distinct clades, with strains originating from 24 countries across Africa, Asia, Australia, and Europe. A fourth of the strains were identified as transmission strains. The strains of two clades, C.5 and C.8, exhibited high clustering rates, indicating higher transmission potential. Drug resistance was also observed, with over 10% of the strains classified as MDR. The strains remained susceptible to BDQ/CFZ, except for two strains displaying resistance. Overall, these findings contribute to a comprehensive understanding of the transmission dynamics and drug resistance patterns of MTBC strains in Sierra Leone and the sublineage 4.6.2.2 Cameroon. The clades of strains that were defined, clusters, and global distribution emphasize the role of migration in the spread of these strains locally and beyond Africa. The insights gained from this research can inform and improve TB surveillance and control measures, both within Sierra Leone, West Africa, and in other parts of the world where the Cameroon sublineage strains have been identified.