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The aim of my project was to develop and apply focused ultrasound stimulation (FUS) to study the human brain. Recently, TFUS was proposed as an advantageous alternative technique for non-invasive modulation of human brain activity. Compared to transcranial magnetic stimulation and transcranial direct current stimulation, the two most-used techniques for neuromodulation, TFUS is more focal and allow to target deeper brain structures with a reduced effect on surrounding cortical tissue. I first determined the sonication parameters to use according to international safety guidelines. Then, I used the prototype I designed to characterize the effects of TFUS sonication over the primary somatosensory cortex using somatosensory-evoked potentials elicited by transcutaneous electrical stimulation of the median nerve (MN). We report the successful modulation of early SEPs potentials (N20 and P27) for TFUS applied 200ms before the delivery of MN stimulation., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2023

The goal of radiation therapy is to deliver a sufficient dose to cancer cells while keeping the exposure of healthy tissue as low as possible to avoid toxicity. Conventional radiotherapy has benefited from technological advances to deliver more conformal doses to the tumor, yet these techniques are still constrained to the natural interaction of photons with matter. Unlike photons, protons slow down as they pass through the patient, releasing most of their energy at the end of their trajectory in the form of what is known as the Bragg peak. By taking advantage of this feature, it is possible to precisely localize the dose peaks in the tumor, reducing the exposure of surrounding healthy tissue. Radiation therapy treatments are planned based on a pre-treatment image to simulate the patient’s anatomy. However, patients are not static, and variations in the anatomy, such as weight loss, are frequent during a treatment course of several weeks. Proton therapy is especially sensitive to anatomical changes along the proton beam path, which alter the position of the Bragg peaks and can strongly deteriorate the initially planned dose. The adaptation of the initial plan is therefore required to preserve the quality of the treatment. Online adaptation in proton therapy, with the patient in the treatment position, aims to provide a rapid response to anatomical changes to compensate for proton dose distortions ensuring accurate treatment delivery. In this thesis, we investigate different strategies to automatically perform online adaptation to facilitate its clinical implementation in proton therapy. Eventually, online adaptation would allow clinicians to achieve greater control over the delivery of conformal proton dose distributions, reducing toxicity and improving patients’ quality of life., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2023

Strong evidence indicates that physical activity and exercise are key interventions for use in the management of patients with cancer. Despite the known benefits of exercise across the entire cancer care continuum, research remains necessary to identify specific exercise prescriptions for the pretreatment and the treatment phases. In the present thesis, we investigated for the pretreatment phase, in two systematic reviews, the current evidence for prehabilitation in patients with cancer. The first demonstrated that a combined aerobic and resistance prehabilitation may benefit patients with various cancer types. The second reported the feasibility, safety and some benefits of prehabilitation in patients with esophagogastric cancer. Then, we reported, in two pilot studies, the feasibility, safety and preliminary effectiveness of prehabilitation with a telerehabilitation system in patients with esophagogastric and colon cancer. For the treatment phase, we emphasized, in a narrative review, that exercise performed by cancer patients during radiotherapy may manage some treatment-related adverse effects. Then, we founded in a randomized controlled trial, that high-intensity interval training (HIIT) and resistance training displayed beneficial effects on cancer-related fatigue and functional exercise capacity in prostate cancer patients undergoing radiotherapy as compared to usual care. Finally, the feasibility and safety of HIIT and resistance training were demonstrated in rectal cancer patients undergoing neoadjuvant chemoradiotherapy., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

In Oncology, chemoresistance is often responsible for therapeutic failure. In this work where we used human cancer models, we investigated whether precise metabolic changes could account for chemoresistance. Not only in cisplatin-resistant ovarian cancer but also in temozolomide-resistant glioblastoma, we evidenced highly oxidative chemoresistant phenotypes depending on mitophagy. Consequently, inhibiting either mitophagy by more largely blocking autophagy or cell respiration by targeting Complex I in the electron transport chain with olaparib allowed to resensitize cancer cells to cisplatin and/or to temozolomide. We propose that these two approaches used in combination therapies with selected forms of chemotherapy would be attractive for countering cancer chemoresistance., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Metabolic plasticity in cancer cells makes very challenging the use of metabolism-targeting agents as monotherapy due to resistance establishment. Moreover, the use of these drugs as anticancer treatments will not only affect cancer cells, but also immune cells in the tumor microenvironment and thereby might abrogate the beneficial effects of immunotherapy. In the first part of our work, we report that exposure to 3-bromopyruvate, a glycolysis inhibitor, renders cancer cells vulnerable to the blockade of monocarboxylate transporter 4 activity, which prevents resistant cells to growth. In the second part of this thesis, we show that acute treatment of activated T cells with fatty acid oxidation inhibitor leads to an increase of their proliferation in vitro, and to higher cytotoxic capacities towards melanoma cancer cells. Altogether our data offer metabolism-targeting therapeutic strategies to overcome resistance from plastic cancer cells and to potentiate benefits of immunotherapies., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Alcohol use disorder (AUD) is a major public health problem affecting 5 to 10% of the population. Chronic alcohol abuse induces alterations in the composition of the gut microbiota, which are correlated with psychological symptoms, suggesting the involvement of the gut-brain axis in the development of addiction. Among dietary component able to modulate the microbiota, dietary fibers are of particular interest. In a first study we investigated the link between dietary fiber intake and psychological symptoms in AUD patients. We found that only a proportion of AUD patients displays alterations in the gut microbiota composition. This dysbiosis is associated with higher craving scores and impaired sociability. Finally, our intervention study aiming to supplement AUD patients with inulin shows that 1) it does not lead to gastro-intestinal intolerance, 2) it induces specific changes in the gut microbiota, 3) it has limited impact on biological and behavioural outcomes, 4) it increases sociability score. If our results show the importance of prebiotic dietary fiber in AUD patients, further studies are needed to define an adapted strategy targeting the gut microbiota to improve metabolic and behavioural alterations in these patients., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Immunotherapy based on monoclonal antibodies targeting the immune checkpoints PD-1 and PD-L1 has revolutionized the treatment of cancer over the last decade. Notwithstanding this success in the clinic, our understanding of the mode of action of anti-PD-1/L1 therapies is still evolving, and the recent literature has brought major revisions in the field. During this work, we first designed a new therapeutic approach to deliver anti-PD-L1 treatment. We engineered tumor-specific CD8 T cells for the intratumoral delivery of an anti-PD-L1 blocking nanobody in a mouse tumor model. We demonstrated the therapeutic superiority of this approach as compared to the systemic injection of anti-PD-L1 antibody, which is the current mode of administration in cancer patients. Our strategy allowed an excellent distribution of anti-PD-L1 nanobody on PD-L1-expressing cells at the tumor site, while systemically injected antibody was trapped in the vicinity of blood vessels. Our results therefore shed light on the poor intratumoral penetration of anti-PD-L1 antibody and suggested that this phenomenon is limiting therapeutic efficacy. Furthermore, we showed that our targeted delivery approach reduced systemic exposure to PD-L1 blocking therapy, which might reduce the risk of developing auto-immune side effects. In parallel, we studied the suppressive activity of PD-L1 in tumor cells and in myeloid cells. Using two different approaches, our results converged to the demonstration that PD-L1 on tumor cells was less potent that PD-L1 on myeloid cells to engage PD-1 on T cells. We hypothesized that PD-L1 on tumor cells might be implicated in protein interactions preventing its binding to PD-1. This led us to suggest a previously unknown protein interaction involving PD-L1 in tumor cells. Finally, we observed that PD-L1 appeared on CD8 T cells upon co-culture with PD-L1-expressing tumor cells. We tried to decipher the mechanisms underlying this intriguing observation, and preliminary results poin, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Cochlear implant (CI) is the most effective solution for the restoration of hearing function in severe to profound sensorineural hearing loss. The main objective of this PhD thesis is to answer the question: « Does AI-assisted programming of a cochlear implant provide similar or better results than manual programming, with less time investment for the patient and the clinician? ». A first study that was conducted in 4 French-speaking centers in Belgium and in France showed a large variability of CI programming within and between centers. This context supports the use of a tool using artificial intelligence, such as the Fitting to Outcome eXpert® (FOX®). A pilot study on 2 subjects who had limited results with their manually programmed CI showed encouraging benefits. Secondly, FOX® was used on a larger scale in 2 prospective interventional studies. The first study evaluated the benefits of using FOX® in former patients who had been implanted and formerly manually programmed for several years. 89% of the subjects showed better auditory performances (psychoacoustic battery A§E®) with the FOX® map than with the manual map. This significant but not systematic gain is discussed, considering the impact of FOX® as a novelty among other factors. The second study compared the manual and FOX® types of programming in a randomised longitudinal study with a crossover design in newly implanted "naïve" subjects. The crossover design involved each group changing programming type at one year post-activation. The FOX® group achieved better speech test results more rapidly than the manual group and maintained these results at one year post-activation. Due to the crossover, FOX® improved the results of 81% of the patients initially programmed manually. In terms of time gain, the number of programming sessions decreased by 55% over one year in patients initially programmed with FOX® compared to those initially programmed manually. A general discussion and a conclusion nuance the results., L’implant cochléaire (IC) est la solution la plus efficace, en termes de restauration de la fonction auditive, dans le cadre d’une surdité neurosensorielle sévère à profonde. L’objectif principal de cette thèse de doctorat est de répondre à la question : « La programmation d’un implant cochléaire assistée par l’intelligence artificielle donne-t-elle des résultats semblables voire meilleurs que ceux obtenus par la programmation manuelle, avec moins d’investissement en temps pour le patient et le clinicien ? ». Une première étude réalisée auprès de 4 centres francophones en Belgique et en France rend compte de la grande variabilité des programmations d’ICs intra et inter-centres. Ce contexte justifie l’apport d’un outil utilisant l’intelligence artificielle, comme le Fitting to Outcome eXpert® (FOX®). Une étude pilote sur 2 sujets présentant des résultats limités avec leur IC programmé manuellement relève des bénéfices encourageants. Ensuite, FOX® est utilisé à plus grande échelle dans 2 études prospectives interventionnelles. La première évalue son apport chez d’anciens patients implantés et programmés manuellement depuis des années. 89% des sujets présentent de meilleures performances auditives (batterie psychoacoustique A§E®) avec la map FOX® qu’avec la map manuelle. Ce gain significatif mais non systématique se discute, en tenant compte, entre autres, de l’impact du FOX® en tant que nouveauté. La deuxième compare chez de nouveaux sujets implantés « naïfs » les types de programmation, manuelle et FOX®, dans une étude longitudinale randomisée avec un cross-over. Le design cross-over implique que chaque groupe change de type de programmation à un an post-activation. Le groupe FOX® obtient plus rapidement de meilleurs résultats aux tests vocaux que le groupe manuel, résultats qu’il maintient à un an post-activation. Suite au cross-over, FOX® améliore les résultats de 81% patients initialement programmés manuellement. Au niveau du gain de temps, le nombre de sessions d, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Gram-negative ESKAPE pathogens are responsible for increases in multidrug-resistant infections worldwide. Poor permeability and active efflux cause intrinsic resistance to many antibiotics. Besides, these pathogens can also adopt specific lifestyles like intracellular survival and biofilm formation where bacteria can switch to dormant phenotypes poorly responsive to antibiotics. This thesis investigated the capacity of the polyaminoisoprenyl potentiator NV716 to revive disused antibiotics against Gram-negative bacteria using planktonic, intracellular and biofilm models. We showed that NV716 re-sensitizes Gram-negative bacteria to disused antibiotics by binding to the lipopolysaccharides (LPS) of the outer membrane, permeabilizing this membrane as well as downregulating quorum sensing regulated processes. Therefore, our work highlights a strong potential for this compound as an adjuvant therapy against difficult-to-treat Gram-negative organisms, and suggests that NV716 deserves further investigations, notably in in-vivo models of infections., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

During liver development, the formation of the bile ducts, hepatic arteries and periportal mesenchyme is interdependent. However, how bile duct development is coordinated with morphogenesis of the vasculature and mesenchyme, and how bile duct lumina form and connect with the canaliculi remains unclear. By combining molecular biology, transgene technology and computational modelling, we found that Slit-Robo signalling, which is active in the mesenchyme, is required for hepatic artery morphogenesis. Furthermore, we propose that the orientation of cholangiocyte division, the dynamics of cholangiocyte differentiation, and osmotic effects are the main drivers of biliary lumen formation. Finally, we provide a first description of how bile duct lumina connect with canaliculi in embryonic livers, and identified Claudin7 as a marker of the cells delineating these junctions., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Cancer cachexia is a complex multi-organ syndrome characterized by unintentional weight loss, weakness, and muscle atrophy. In addition, fat depletion, thermogenesis, and systemic inflammation were reported in clinical and/or preclinical models. It affects up to 70% of cancer patients, depending on cancer type, and is responsible for at least 22% of cancer deaths. Cancer cachexia does not only result in increased mortality rates but also in increased morbidity and reduced tolerance to anti-cancer treatments. More knowledge regarding the contribution of hepatic alterations to the pathogenesis is currently emerging. Our hypothesis is that bile acid profiles and metabolism are altered in cancer cachexia, and that these alterations may contribute to the cachectic features. Therefore, the main objective of this thesis was to investigate this hypothesis, with the ultimate goals of deciphering the mechanisms linking bile acids to the pathophysiology of the disease, and identifying innovative therapeutic targets to improve the management of cancer cachexia. Hepatic whole transcriptome analysis of the well-established C26 cachectic mouse model identified alterations in several inflammatory pathways as well as other pathways, including bile acid metabolism. We found out that the hepatobiliary transport system was deeply impaired in cachectic mice, leading to increased hepatic inflammatory cytokines and neutrophil recruitment to the liver of cachectic mice, and this occurred independently of food intake. Targeting bile acids using cholestyramine, a bile acid sequestrant, reduced hepatic inflammation, without affecting the hepatobiliary transporters. Of note, treatment with the neutralizing IL-6 antibody counteracted the change in expression of genes involved in hepatobiliary transport, bile acid synthesis and inflammation. Coherently, analysis of the serum bile acid profile in a cohort of 94 colorectal cancer patients with or without cachexia revealed increased serum bile acid, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Radiotherapy is used in more than 50% of cancer treatments and is thus of the utmost importance in the field of cancer care. The clinical aim of such treatment is to achieve locoregional tumor control with targeted ionizing radiation while minimizing the complication risks for the patient. To this end, the use of ions such as protons is particularly adequate, due to the high dose they deposit at the end of their path. This results in highly conformal dose distributions, with sharp dose gradients around target volumes, enabling excellent sparing of healthy tissues. The generalisation of magnetic steering of protons (pencil beam scanning) and intensity modulated proton therapy further improves the conformity. However, the presence of high dose gradients and localized energy deposition peaks make proton plans particularly sensitive to the uncertainties involved in the preparation and the execution of the treatments. Several strategies exist for managing the uncertainties and mitigate their effect. Among them, accurate methods for computing the dose that will be delivered to the patient are of paramount importance, enabling this way safe treatment planning and reliable quality assurance (QA). For QA, in particular, independent Monte Carlo dose engines are undeniably optimal, providing accurate dose verification in independent conditions. However, their inherent statistical uncertainty can hinder a proper interpretation of QA outputs, and their clinical integration remains challenging, time-consuming and, subsequently, a source of errors. This thesis aims at proposing tools to facilitate a correct and efficient use of independent Monte Carlo dose calculation in proton therapy, so that we can move towards a safer delivery of this treatment modality., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

We aimed to evaluate the potential of traditionally used Pakistani plants for inflammatory bowel diseases and to identify their active constituents. Starting from 5 Pakistani plants, we obtained 25 non-cytotoxic extracts of which 5 showed an interesting activity in decreasing pro-inflammatory cytokines expression in LPS-activated J774 macrophages. Among these, the methanol extract of Salvadora oleoides underwent a bio-guided fractionation and one of the most active fractions, dereplicated by HPLC-HRMS/MS analysis, was putatively found rich in galactolipids that could be responsible for at least a part of the observed activity. The extract was also found to be not toxic by in vivo acute and sub-acute toxicity tests and was tested, per os, in a DSS-induced colitis mice model, but did not reduce the extent of colon inflammation. We also investigated the methanol and ethyl acetate extracts of Convolvulus arvensis and putatively identified 45 compounds by dereplication (HPLC-HRMS/MS analysis and molecular networking). The 6 major compounds were quantified by HPLC-PDA in both extracts and 4 of them were found to significantly decrease LPS-induced J774 macrophage activation, supporting the traditional use of the plant., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Arginase 1 (Arg1) is a key hydrolase involved in the urea cycle and in the immune system. Arg1 is upregulated in various types of cancers and plays crucial roles in the regulation of tumor growth and metastasis. Thus, Arg1 is an increasingly attractive target for cancer therapy. In this thesis, we aimed to find new scaffolds. A reliable enzymatic evaluation method of chemical libraries such as that of 5-bromo-2-amino-thiazole was set up. A molecular modeling approach (SBDD) led to a better understanding of the possibilities and limitations in the Arg1 inhibitors design for the study of larger scaffolds. A Fragment-Based approach (FBDD) was then developed. A screening of coordinating motif libraries found two hits: 2-furanylboronic acid and cyclohexylboronic acid. Finally, we attempt to optimize these two hits and discussed about the challenges of obtaining such derivatives., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Hodgkin lymphoma (HL) is a lymphoid neoplasm that originates from mature germinal center B cells. The etiopathogenesis of HL has a significant genetic component, however, few studies have investigated genetic predisposition to familial HL. We identified two potential HL-predisposing genes, CCNF and HK3. Variants in CCNF (a cell cycle regulated ubiquitin ligase) caused decreased binding to its ubiquitylation targets, possibly leading to defects in DNA replication and repair and cell cycle progression. Variants in HK3 (which catalyzes the first step of glycolysis) hamper or abolish the enzyme’s function. Loss of HK3, which is expressed in the tumor niche, may affect the anti-tumor activity of immune cells thereby conferring a more permissive immune microenvironment. Finally, the occurrence of variants in both CCNF and HK3 in one HL family provides us with a unique opportunity to pursue a proof-of-concept of oligogenic effects in predisposition to familial HL., Le lymphome de Hodgkin (LH) est un néoplasme lymphoïde des lymphocytes B matures provenant des centres germinatifs. Il a été démontré que la prédisposition génétique joue un rôle important dans le développement du LH familial, cependant peu d’études l’ont étudiée. Nous avons identifié deux gènes candidats prédisposant au LH : CCNF et HK3. Nous avons démontré que les variants dans CCNF, une ubiquitine ligase, provoquent la diminution de sa capacité à lier ses cibles, entraînant potentiellement des défauts de réplication et de réparation de l'ADN et de la progression du cycle cellulaire. Les variants dans HK3, enzyme catalysant la première étape de la glycolyse, entravent sa fonction. HK3 étant exprimée par le microenvironnement tumoral, sa perte de fonction pourrait affecter l'activité antitumorale des cellules immunitaires, altérant ainsi le microenvironnement immunitaire. Enfin, les variants de CCNF et HK3 affectant une même famille nous offre l’opportunité d’étudier les effets oligogéniques dans la prédisposition au LH familial., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Chronic alcohol consumption is one of the leading causes of chronic liver disease and liver-related deaths worldwide. Only up to 20% of patients with an alcohol use disorder (AUD) progress to advanced stages of alcohol-associated liver disease (ALD) from the benign form of the disease, namely simple steatosis. This process is usually silent at early disease stages and the mechanisms underlying disease progression are yet incompletely understood. Recent reports have highlighted the role of the gut-liver axis in ALD. However, data in early human ALD were scarce. Therefore, this PhD work aimed at investigating dysfunctions of the intestinal barrier in AUD patients and their relationship with activation of immune responses contributing to ALD progression. We here revealed a specific diminution of effector immune cells in the duodenal mucosa and the presence of a tolerogenic immune status associated with changes in the gut microbiota and elevated translocation of microbial products in patients with progressive ALD. These microbial products activated circulating monocytes and liver inflammatory responses, thus contributing to systemic inflammation and ALD progression. The results of this PhD thesis support the contribution of gut barrier dysfunctions in human ALD pathogenesis., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Overweight and obesity are now considered as multifactorial pathologies, affecting 39% of the world’s population. The dysregulation of food intake in favor of hedonic food intake (based on the pleasure, and linked to the brain reward system) rather than food intake based on the energy needs of the body (homeostatic), has been identified as one of the main cause of body weight gain. Identifying factors contributing to this dysregulation of food intake would limit the obesity epidemic, the prevalence of metabolic disease associated with obesity, and healthcare costs. Our team and others have broadly described the roles and mechanisms by which the gut microbiota influences hunger and satiety to regulate food intake in function of the energy needs. However, the roles of gut microbes in the hedonic food intake have been poorly investigated so far. The mechanisms behind the dysregulations of hedonic food intake associated with obesity are still unknown. The aim of this PhD work is to investigate the roles of the gut microbiota as a potential therapeutic target to tackle dysregulations of the hedonic/reward system in the context of obesity. We aim to know if the gut microbiota is involved in the hedonic responses to food intake in physiological and pathological conditions (obesity). Our objective is to prove the causal role of the gut microbiota in reward dysregulations associated with obesity. After that, we investigated the mediators of the gut-brain axis influencing the reward responses to food intake. Finally, we studied the underlying mechanisms of the roles of the gut microbiota in hedonic/reward responses to food intake. We used the fecal material transplantation model in mice to prove the causal role of the gut microbiota in the reward system on a behavioral and neuronal points of view. Thanks to metabolomics studies, we were able to identify a gut-derived metabolite as a potential mediator in the gut-brain axis influencing the reward system. Moreover, we have demo, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Cancer cachexia is a complex multi-organ syndrome characterised by body weight loss, weakness, muscle atrophy and fat depletion. The modulation of the gut microbiota, an important regulator of the host metabolism, has shown therapeutic potential. To evaluate the contribution of gut microbiota alterations to the metabolic dysfunctions observed in cancer cachexia, we first investigated the role of Klebsiella oxytoca. We found that this Enterobacteriaceae species acts as a gut pathobiont by altering the gut barrier function in cachectic mice. Then, a multi –omics strategy revealed multiple host metabolic alterations and a reduction of different beneficial intestinal bacterial activities in cachectic mice. Finally, we used a multi –omics approach to show that acute myeloid leukemic patients display gut microbiome alterations at diagnosis. Such alterations may contribute to metabolic and inflammatory dysregulations in those patients. By combining preclinical and clinical data, this thesis work pinpoints important metabolic and microbial alterations in cancer cachexia and shows the interest of this research field for future therapeutic applications., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Acetyl-CoA carboxylase (ACC) catalyzes the first step of de novo lipogenesis. We previously demonstrated that ACC activation promotes thrombus formation by increasing platelet arachidonic acid (AA)-containing phosphatidylethanolamine plasmalogen (PEP) content and thromboxane A2 (TxA2) generation. Therefore, we hypothesized that ACC deletion could be a protective mechanism against thrombus formation, especially in prothrombotic diseases such as atherosclerosis. We discovered that platelet-specific ACC1 deletion reduced thrombus formation on collagen-coated surface under flow conditions via a decrease in AA-containing PEP content leading to a subsequent decrease in TxA2 and dense granule secretion. Interestingly, two hours treatment with CP640.186, a pharmacological ACC inhibitor, impaired platelet aggregation via an increase in tubulin acetylation level rather than a change in phospholipid composition., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Cardiovascular diseases are the leading cause of death in the world. Among them, heart failure is a complex syndrome characterized by the inability of the heart to sustain proper cardiac output to meet metabolic demands of organs. The deleterious outcome of this progressive disease is associated with chronic cardiac hypertrophy and a general increase in protein O-GlcNAcylation, an emerging post-translational modification. Our team has previously highlighted that the reduction of O-GlcNAcylation following AMPK activation prevents the development of cardiac hypertrophy. In the present work, we show that AMPK-mediated inhibition of O-GlcNAcylation not only reverses cardiomyocyte hypertrophy in vitro, but also improves cardiac function in an in vivo model of cardiac hypertrophy. In addition, proteomic analysis allowed us to identify numerous O-GlcNAcylated proteins, rainsing novel potential therapeutic strategies for the treatment of heart failure., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Tumor development is characterized by both genetic and epigenetic alterations that lead to gene expression changes. One of such transcriptomic changes is the aberrant activation of a group of germline-specific genes in a variety of tumors of somatic origin. The spurious activation of this group of genes is due to the DNA demethylation of their promoter region in tumor cells, a phenomenon associated with the global loss of DNA methylation that often accompanies tumorigenesis. Several of these “cancer-germline” genes were found to exert pro-tumoral functions, or evoke an immune response. Cancer-germline genes are therefore attracting much interest, as they constitute promising targets for anti-cancer therapies with the hope of limited side effects due to their highly restricted pattern of expression. Whether additional tissue-specific gene clusters become activated in tumors, be it by DNA demethylation or not, remains unanswered. Most studies, indeed, have used transcriptomic approaches that were biased towards testis-specific genes. In the present work, we aimed to fill this gap by combining omics data of lung adenocarcinoma (LUAD) tissues and cell lines, as well as normal lung and alveolar type II cells (AT2), the cells of origin of LUAD, without imposing any criteria of expression specificity to the ectopically activated genes we were looking for. We divided our work in two complementary axes. In the first part, we asked whether the global loss of DNA demethylation in tumors is also associated with the ectopic activation of somatic-specific gene clusters in LUAD. We found that, indeed, promoter DNA demethylation in these cells leads to the transcriptional induction of genes displaying selective expression in gastro-intestinal tissues (colon and small intestine), and of genes specific to stratified squamous epithelia (esophagus, skin and vagina). Interestingly, our data show that ectopic activation of this latter group of genes in LUAD is associated with poor progno, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Malaria and Neglected Tropical Diseases such as Human African Trypanosomiasis (HAT) and leishmaniasis still remain nowadays a global healthcare concern and the severe therapeutic limitations and resistance threats make crucial the research for innovative drugs. Given the antiparasitic potential of pentacyclic triterpenic esters, hemi-synthesis of new derivatives, ADME profile analysis and formulation design were explored on selected promising compounds. The selected compounds were a mixture of C-27 natural triterpenic esters (8TTE) isolated from the twigs of Keetia leucantha, and the C-3 hemi-synthetic ester, ursolic acid 3-O-phenyl propionate (UAOPP), both effective in vitro and in vivo against malaria and HAT, respectively. Bioisosters of UAOPP were also hemi-synthesized using one step synthesis. The stability profiles in biological environments and metabolic analysis of the lead compounds were investigated with a validated analytical method. To improve their bioavailability, specific bioactive triterpenic esters’ formulations were designed and tested for the in vitro antiparasitic activity and intestinal absorption/permeability using a validated more sensitive analytical method. This work contributes to the bioactive triterpenic esters development both from natural and (hemi-)synthetic sources as orally active antiparasitic drugs., Le paludisme et les maladies tropicales négligées telles que la trypanosomiase humaine africaine (THA) et la leishmaniose restent encore de nos jour un problème de santé mondial et les limitations thérapeutiques sévères et l'apparition de résistances rendent cruciale la recherche de médicaments innovants. Compte tenu du potentiel antiparasitaire des esters triterpéniques pentacycliques, l'hémi-synthèse de nouveaux dérivés, l'analyse du profil ADME et la conception de formulations ont été explorées sur des composés prometteurs sélectionnés. Les composés sélectionnés étaient un mélange d'esters triterpéniques naturels en C-27 (8TTE) isolé des tiges de Keetia leucantha, et l'ester hémi-synthétique en C-3, l'acide ursolique 3-O-phényl propionate (UAOPP), tous deux efficaces in vitro et in vivo contre le paludisme et la THA, respectivement. Des bioisostères d'UAOPP ont également été hémi-synthétisés en utilisant une voie de synthèse en une étape. Les profils de stabilité en milieux biologiques et l'analyse métabolique des composés principaux ont été étudiés avec une méthode analytique validée. Pour améliorer leur biodisponibilité, des formulations spécifiques d'esters triterpéniques bioactifs ont été conçues et testées in vitro pour leur activité antiparasitaire et l'absorption/perméabilité intestinale avec une méthode analytique validée plus sensible. Ces travaux contribuent au développement d'esters triterpéniques bioactifs provenant à la fois de sources naturelles et (hemi-)synthétiques en tant que médicaments antiparasitaires actifs par voie orale., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

The loss of plasma membrane from red blood cells (RBCs) through the budding and release of extracellular vesicles (EVs) affects their shape, deformability and functionality. Although oxidative stress appears as the main triggering factor for RBC vesiculation, the role of plasma membrane properties is largely overlooked. We here addressed if plasma membrane biophysical properties as well as lipid transversal and lateral distribution could contribute to the RBC vesiculation process upon RBC storage and in hereditary spherocytosis, a membrane fragility disease. Results indicate that, in contrast to spherocytosis, the release of EVs during hypothermic storage in blood tubes and in RBC concentrates is accompanied by the successive impairment of RBC membrane rigidity, lateral heterogeneity in lipid domains and transversal asymmetry. Our data open the way to use EVs or lipid domains for quality control in transfusion centers and to target domains to minimize vesiculation in RBC concentrates., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Tumor cells use different mechanisms to avoid immune recognition. One of these is the induction of the enzymes indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3 dioxygenase (TDO) responsible for catabolizing the essential amino acid tryptophan into kynurenine. The aim of this work was to elucidate the pathway that translates these metabolic changes into T-lymphocyte malfunction within the tumor microenvironment. We show that through the aryl hydrocarbon receptor (AHR), CD4+ T lymphocytes from DBA/2 mice, differentiate significantly more into immunosuppressive regulatory T cells (Treg) when cultured in absence of tryptophan. More importantly, we found that under tryptophan-depleted conditions, AHR was significantly upregulated rendering it more sensitive to ligands such as kynurenine. Overall, our findings provide new insights into the respective role of tryptophan depletion and kynurenine production in IDO1/TDO-mediated immunosuppression., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Glioblastoma is the most common and aggressive brain cancer. The low median survival of patients diagnosed with this disease makes it an unmet medical need. Nowadays, immunotherapeutic treatments have shown remarkable results in some populations of cancer patients but are rather ineffective in improving glioblastoma patients’ outcomes when used in monotherapy. The aim of this Ph.D. thesis is to contribute to the research of glioblastoma treatments by developing combination strategies of drug delivery systems to potentiate immunotherapy efficacy. The strategies used in this work include a DNA vaccine encoding glioblastoma-associated antigens, immune checkpoint blockades, and an immunogenic chemotherapeutic agent delivered locally. Our findings confirm the benefit of combination strategies to improve the immune response and increase the survival of glioblastoma., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Endometriosis is an inflammatory gynecological pathology that affects approximately 10% of women worldwide and can cause subfertility. In 30% of patients, the endometriotic tissue is resistant to progestin treatment. The objective of my thesis was to characterize and define the potential role of the protein Progesterone Receptor Membrane Component 1 (PGRMC1), described as a "fertility stabilizer", in the human endometrium and endometriosis. A spatiotemporal regulation of PGRMC1 was identified with a predominant expression on the surface of the proliferative endometrium and potentially reduced in endometriosis. My results (i) discredit the AG-205 inhibitor, a major tool in the study of PGRMC1, (ii) demonstrate the repressive activity of PGRMC1 towards MMP-3 and (iii) suggest that it regulates cell proliferation during the menstrual cycle. PGRMC1 could thus control endometrial tissue remodeling, which is crucial for fertility., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Lors de leur exposition prolongée avec leur antigène, les lymphocytes T CD8 ont une capacité atténuée à proliférer, produire des cytokines, et expriment le récepteur PD-1. Ils sont nommés « épuisés ». Le rôle des facteurs de transcription impliqués dans l’épuisement est incertain car il est difficile de distinguer les changements qui relèvent de l’activation d’un lymphocyte T, de ceux qui conduisent à leur épuisement. De plus, la majorité des études réalisées compare des lymphocytes T CD8 épuisés, donc chroniquement activés, à des lymphocytes T CD8 au repos. Dans cette thèse, nous avons examiné le rôle du facteur de transcription IRF4 sur la fonction des lymphocytes T CD8 humains en forçant son expression par transduction lentivirale ou en l’invalidant par CRISPR/Cas9. Puis, nous avons analysé si les lymphocytes T CD8 infiltrés dans des tumeurs ovariennes humaines co-expriment des marqueurs d’épuisement et d’activation, ainsi que le facteur de transcription IRF4., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

This thesis aims to study extracellular vesicles (EVs) in thyroid cancer (TC) hoping to understand their role in cancer progression and to identify new biomarkers for the differential diagnosis between TC and benign nodules. Using a mouse model mimicking human TC, we isolated and characterized EVs from control and cancerous thyroid tissues. We identified tumor-derived EV-miRNAs by sequencing. More abundant EV-miRNAs were mostly deregulated in tumor cells and could affect immune-related pathways. We thus propose that tumor cells secrete more EVs containing a deregulated miRNA signature and that this could affect the immune microenvironment. Finally, the diagnostic value of a few miRNA candidates was assessed by quantifying their levels in plasma-EVs from patients with thyroid diseases, suggesting the diagnostic potential of EV-enclosed miR-146b-5p and miR-21a-5p, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

The dose concentration at the end of the proton range has the potential to significantly reduce exposure of healthy tissues to radiation, while maintaining the curative dose to the tumor. However, the beneficial effect of protons comes at the cost of increased sensitivity to treatment uncertainties, which can lead precisely to over-exposure of healthy tissues. The main objective of this thesis is the development of treatment planning methods that ensure robustness, while avoiding the possible loss of plan quality at the moment of delivery. The focus lies on establishing sound confidence levels for treatment planning and the integration of target volume uncertainty, previously unconsidered in the planning process. Overall, the concepts developed in this thesis regarding robust dose optimization and statistical analysis, offer better tools for managing the trade-offs and robustness of treatments. This can bring us one step closer to delivering on promises made in proton therapy., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Colorectal anastomotic leakage is a serious surgical complication, and the local microbiota is suggested to have a strong influence on anastomosis healing. As the existing murine anastomotic leakage models have major limitations to assess the consequences of local microbiota manipulation, we developed and described a novel intestinal wound healing model called the “Colonoscopic Leakage Model”. Using this model, our experiments demonstrate that A. muciniphila, a next-generation beneficial bacterium, improves wound healing after transmural colonic wall defect through mechanisms possibly involving IL22 signaling and requiring MyD88 in the intestinal cells. Results of a proof-of- concept pilot study, show that in healthy humans, colonic administration of A. muciniphila is well-tolerated and changes the expression of genes involved in the immune pathways., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Surgical site infections are one of the most common healthcare associated infections and contribute significantly to increase the patient's morbidity, healthcare costs and antibiotic resistance. In Benin, due mainly to the irrational prescription of antibiotics, and poor infection prevention and control programs, we observed a scarcity of local data regarding the rates of SSIs and the frequency of multi drug bacteria isolated (MDR). Almost all Gram negative bacteria isolated on pus samples were resistant to at least five classes of antibiotics. Moreover, healthcare workers missed two opportunities out of three to apply hand hygiene and when HH was applied, technique and duration were not appropriate. Our interventions focused on implementation of world health organization multimodal strategy with high availability of alcohol-based hand rub solution in hospitals. However, future work is needed to largely describe the molecular epidemiology of MDR., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Telomeres protect the ends of our chromosomes. The replicative immortality of cancer cells depends on the activation of a telomere maintenance mechanism: the telomerase or an alternative lengthening of telomeres (ALT) mechanism. ALT is activated in about 10% of tumors but this prevalence increases greatly in pediatric tumors. The latter are in need of targeted therapies but, to date, there is still no therapy targeting ALT. In this thesis, we identified TSPYL5 (testis-specific Y-encoded-like protein 5) as a critical protein for ALT+ cell viability, opening new perspectives for anti-ALT targeted therapies. We also established a mouse xenograft model with human ALT+ cancer cells to test the efficiency of future anti-ALT compounds. The lack of good tools for the diagnosis of ALT also led us to the development of a new robust test on tumor sections. Finally, we provided additional evidence that replicative stress induces some characteristics of ALT telomeres., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

The inappropriate utilization of antibiotics drove to a global public health threat: the antimicrobial resistance. Several strategies were set up to fight the problem such as Infection Prevention and Control which aims to improve the use of antibiotic. Our work identified the bottlenecks of the rational use of antibiotics in Benin in the context of the user fees exemption policy in caesarean section with a national free kit. The findings of our five studies showed: - a misuse, overuse, and underuse of antibiotics before, during and after caesarean section, - a low level of knowledge of antibiotic prophylaxis in healthcare professionals, a lack of confidence in the kit, and some general disagreement with the policy, - some cases of overdosage of active ingredient, - a mixed knowledge of antibiotics and their utilization by patients, - a low involvement of end-implementers during the policy formulation, a mixed-consensual context without scientific evidence-based considerations in the choice of antibiotics in the kit. The analysis of these findings revealed that the bottlenecks of the rational use of antibiotics were in all levels of the Benin healthcare system (healthcare professionals, patients and policymakers). Considering the burden the inappropriate use of antibiotics induces for patient and public health, it is imperative to implement actions to improve the use of antibiotics. Based on the literature, a program named “antimicrobial stewardship” permits to coordinate a set of actions for promoting the prudent use of antimicrobials, with the ultimate goal of optimizing clinical outcomes while minimizing unfavorable consequences including resistance selection as well as adverse drug reactions. This program includes various actions for all actors of the healthcare system such as patient education, healthcare professional training and involvement in Infection Prevention and Control strategies, and policymakers’ commitment. The implementation of this kind of program, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2022

Medical devices-associated infections are characterised by the formation of a biofilm that encapsulates the microorganisms in an extracellular matrix. The thesis focused on inter-kingdom biofilms, when at least a bacterium and a fungus are present. They are hard to treat infections with high failure rates. Our aim was to determine if the disruption of the biofilm matrix with hydrolytic enzymes could potentiate the activity of the antimicrobials against inter-kingdom biofilms. An in-vitro three-species biofilm model was set up co-culturing the bacteria S. aureus and E. coli, and the fungus C. albicans. The results confirmed that the antimicrobials on their own had a limited activity, but the enzymes permitted the antimicrobials to reduce further the biofilm biomass and C. albicans culturable cells. The inclusion of the strategy proposed in this thesis to current clinical practices could lead to a better outcome of the treatment of inter-kingdom medical device-associated infections., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

A growing body of evidence indicates that mitochondria play a key role in many disorders as well as in cancer progression and response to treatment. Next to being the main cellular energy generator through respiration, mitochondria are also the major producer of superoxide and other downstream reactive oxygen species in the cell. In this thesis, we aimed to develop an integrated electron paramagnetic resonance (EPR) toolbox enabling the assessment of mitochondrial (dys)function by measuring the oxygen consumption rate and superoxide production in a same cellular or mitochondrial preparation. This EPR toolbox was used for the benefit of two different projects: discovering potential radiosensitizers in anticancer therapy (like statins) and assessing the impact of agents such as Boscalid and Bixafen, which are succinate dehydrogenase inhibitors (SDHI), on the mitochondrial function of human cells., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Sickle cell disease is the most common genetic disease affecting more than five million people worldwide. For its treatment, compounds such as senicapoc and voxelotor have recently proven their efficacy in clinical studies with sickle cell patients. However, their low aqueous solubility and sensitivity to metabolism make them poorly bioavailable by the oral route. This project aims to develop self-emulsifying systems to increase the aqueous solubility and oral bioavailability of senicapoc and voxelotor. Self-emulsifying systems loaded with senicapoc and voxelotor were developed and optimized. These formulations increased both the aqueous solubility and cellular transport of senicapoc and voxelotor through enterocyte monolayers (Caco-2). The lipid formulation loaded with voxelotor significantly increased its oral bioavailability compared to a suspension., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

In cystic fibrosis (CF), recurrent pulmonary infections suggest lung impaired mucosal immunity. The epithelium and the secretion of immunoglobulin A (IgA) by polymeric immunoglobulin receptor (pIgR) are major lines of mucosal defence. Therefore, this thesis aimed at assessing airway epithelial function (IgA secretion) and differentiation in CF. We observed an enhanced bronchoepithelial pIgR and IgA production in the CF lung, indicating upregulated humoral mucosal immunity due to Th17 host immune response against infection. By contrast, in the absence of infection, cell and animal experiments displayed a negative regulation of pIgR expression upon CFTR F508del mutation, associated with unfolded protein response. We also showed a ciliated cell defect and several signatures of impairment of the airway epithelium integrity, including epithelial-to-mesenchymal transition, in CF lung and cell. In conclusion, this thesis reveals in CF a complex interplay between dedifferentiated epithelial cells and (Pseudomonas aeruginosa) infection, which connects CFTR dysfunction, unfolded protein response activation, and a (Th17) host immune response to IgA secretion in the lung., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

The transplantable engineered ovary is a promising approach to restore fertility in women and prepubertal girls at high risk of metastatic cancers. It is essentially a 3D matrix encapsulating isolated preantral follicles and ovarian cells. These cells are responsible for extracellular matrix and bioactive factor synthesis, as well as vascularization, and some will be recruited to differentiate into theca cells (TCs). Although TCs play a pivotal role in follicle development and steroid production, there is not much information on their recruitment and differentiation in human ovaries. Studies in animal models suggest two hypotheses on the origin of TCs: (i) a subpopulation of precursor TCs or (ii) all stromal cells are able to differentiate into TCs. To shed light on TC populations and their origin in the human ovary, we first investigated their steroidogenic pathway. We then assessed the presence of a subpopulation of precursor TCs in human fetal, prepubertal, reproductive-age and postmenopausal ovaries. While we could not identify them, we demonstrated that TCs could differentiate in vitro from stromal cells isolated from human postmenopausal ovarian cortex., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Malignant mesothelioma is a disease caused by inhalation of needle-like shaped particles and whose pathogenesis is not yet fully elucidated. A long-lasting general inflammation caused by persistent mesotheliomagenic particles is not sufficient to explain mesothelioma onset. Indeed, challenging data have shown that mesothelioma occurs without chronic inflammation. Our research team previously helped to discover that, beside inflammation, particles such as silica also induce a selective, rapid and sustained accumulation of immunosuppressive cells (regulatory T lymphocytes, myeloid derived suppressive cells and M2/regulatory macrophages) participating to fibrogenesis. To determine whether carcinogenic particles such as asbestos and carbon nanotubes (CNT) also elicit immunosuppressive responses, we investigated the impact of these particles on macrophage turnover, phenotype and immunosuppressive activity. With that purpose, we intraperitoneally injected mesotheliomagenic CNT-7 (needle-like, Mitsui & Co) and non-mesotheliomagenic CNT-T (tangled, Nagoya University) particles in Wistar rats and compared the effects on peritoneal macrophage subpopulations. We showed that macrophages die very rapidly in the attempt to phagocyte mesotheliomagenic CNT. They are later replenished by monocytic-derived small peritoneal macrophages (SPM-like macrophages) possessing comparable immunosuppressive functions and signatures to Tumor-Associated Macrophages (TAM), which infiltrate mesothelioma and block T cell antitumor activities. Early immunosuppressive SPM-like macrophages express and release the shed form of the immunoregulatory syndecan-1 glycoprotein, which could explain the immunosuppression that they exert on T cells. Non-mesotheliomagenic peritoneal responses induced by CNT-T are, in contrast, characterized by a recruitment of self-proliferating large peritoneal macrophages (LPM-like macrophages) that correspond to homeostatic macrophages without immunosuppressive activity. Our o, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Staphylococcus aureus is an etiological agent involved in a multitude of infectious diseases, ranging from minor skin infections to more serious diseases. Bacterial persisters are subpopulations that adopt a transient phenotype characterized by a non-growing state and a tolerance to lethal concentrations of antibiotics. When the antibiotic treatment is discontinued, persisters give rise to a population that is, again, mostly drug susceptible. Their rare and transient nature has long hampered their experimental study, but there is now rising evidence on their implication in relapses of chronic infections. A switch to a persister phenotype has been suggested to occur inside eukaryotic cells for only very few intracellular bacteria, and the mechanisms leading to their formation are still poorly understood. Given the capacity of S. aureus to promote persistent or recurrent infections, we demonstrated that antibiotics could induce persisters within host cells and thus explain the impossibility of eradicating intracellular reservoirs. Our data further indicate that permissive host cells can host alternatively persistent bacterial forms upon antibiotic exposure, and replicative forms upon antibiotic removal and could therefore constitute a viable reservoir and a source of dissemination. Further transcriptomic analysis contributed to a better understanding of the mechanism of persistence formation. Persisters remained metabolically active and redirect energy-consuming processes to the benefit of multiple stress responses that contribute to the maintenance of vital processes, notably cell wall, DNA and transcription. In non-permissive cells, host cell oxidative stress modulates dormancy of S. aureus persisters, which may then reach different levels of dormancy but remain infectious, unveiling complex strategies developed by S. aureus to cope with the host and antibiotic treatments., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

The infection by the human immunodeficiency virus (HIV) is typically treated using a combination of pharmacological agents targeting different stages of the viral cycle. Darunavir is a second-generation protease inhibitor that occupies a place of choice in this therapeutic arsenal and for which an important inter-individual pharmacokinetic variability has been described in the literature. First, we characterized darunavir pharmacokinetics by developing a population model based on data collected in a large cohort of HIV patients. Alpha-1 acid glycoprotein level, sex, and genetic polymorphisms in the CYP3A5 and SLCO3A1 genes were found to be significant predictors of darunavir pharmacokinetics. The model was thoroughly evaluated using internal and external validation techniques. The model also allowed us to simulate the effect of alternative dose regimens in populations representative of clinical practice. A reduction of the standard 800 mg once-daily dosage to 600 or 400 mg once-daily was found to be safe in a large proportion of patients, based on commonly defined pharmacokinetic targets for this molecule. On the other hand, intermittent therapy (five out of seven days) constituted an unsafe option in most subjects. Whether individual patients could benefit from these alternative regimens could be predicted by our model. Additionally, optimal sampling strategies for darunavir were derived, showing how to best design future studies or how to optimize therapeutic monitoring for this drug. Finally, in vitro experiments helped determine the contribution of polymorphisms in the P-glycoprotein gene to the aforementioned variability. These experiments showed that neither the c.1199G>A polymorphism nor the haplotype defined by c.1236C>T, c.2677G>T and c.3435C>T influence intracellular accumulation of darunavir., L'infection par le virus de l'immunodéficience humaine (VIH) est typiquement traitée par une combinaison d'agents pharmacologiques ciblant différentes étapes du cycle viral. Le darunavir est un inhibiteur de protéase de seconde génération qui occupe une place de choix dans cet arsenal thérapeutique et pour lequel une importante variabilité pharmacocinétique inter-individuelle a été décrite dans la littérature. Premièrement, nous avons caractérisé la pharmacocinétique du darunavir en développant un modèle de population sur base de données collectées dans une large cohorte de patients VIH-positifs. Il a été démontré que le taux d’alpha-1 glycoprotéine acide, le sexe, et des polymorphismes dans les gènes CYP3A5 et SLCO3A1 étaient des prédicteurs significatifs de la pharmacocinétique du darunavir. Le modèle a été évalué en profondeur par le biais de techniques de validation interne et externe. Le modèle a également permis de simuler l’effet de régimes posologiques alternatifs dans des populations représentatives de la pratique clinique. Une réduction de la dose journalière standard de 800 mg à 600 ou 400 mg a été démontrée sure pour une large proportion de patients, sur base de cibles pharmacocinétiques couramment définies pour cette molécule. En revanche, la thérapie intermittente (cinq jours sur sept) ne constituait pas une option sure pour la plupart des sujets. L’existence d’un bénéfice individuel de ces stratégies alternatives pourrait être prédite par notre modèle. Par ailleurs, des stratégies de prélèvement optimales pour le darunavir ont été définies, montrant comment concevoir de futures études de manière optimale ou comment optimiser le monitoring thérapeutique pour ce médicament. Enfin, des expériences in vitro ont permis d’établir la contribution de polymorphismes dans le gène de la P-glycoprotéine à la variabilité précédemment mentionnée. Ces expériences ont montré que ni le polymorphisme c.1199G>A ni l’haplotype défini par c.1236C>T, c.2677G>T et c.3435C>T, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Background The deficit in social cognition in schizophrenia has been demonstrated in numerous studies and metaanalyses. However, previous studies have focused on a group evaluation of social cognition, without exploring interindividual and intergroup variations on populations of different cultures. In addition, the international literature is focused on data from industrialized countries. In Africa, and particularly in the Democratic Republic of Congo, there are no data. Methods We conducted case-control studies of 60 and 58 subjects respectively in the Democratic Republic of Congo and Belgium to determine the variability of performance in social cognition evaluated by the ClaCos, in its various components, between subjects of different cultures (patients and healthy controls Belgians and Congolese) and within the Belgian and Congolese groups. The ClaCos explores the areas of social cognition described by Green et al., 2008 : the TREF (facial emotion recognition test) for emotional perception, PerSo for social Perception and social Knowledge, MASC (Movie for the Assessment of Social Cognition) for Theory of Mind and AIHQ for Attribution Style. This battery also allows the evaluation of empathy performance by the QCAE and subjective abilities in social cognition by the ACSO. Results The results of the recognition of emotions among schizophrenic patients in the Democratic Republic of Congo (DRC) (GMB Kitoko et al., 2019) and the social perception and social knowledge of schizophrenic patients in Belgium (GMB Kitoko et al., 2020) have been published in the form of V articles in scientific journals. Overall, patients with schizophrenia showed impaired and heterogeneous performance in all social cognition assessment tasks, within each group and between groups in two countries. Social cognitive abilities were partially independent from patients' neurocognitive abilities, and clinical symptoms. In both groups, patients showed deficits in facial emotion recognition. These r, (MED - Sciences médicales) -- UCL, 2021

Current immunotherapy is less effective in breast cancer than in melanoma. However, “TILs” (tumor-infiltrating lymphocytes) are a prognostic factor and a predictive biomarker for chemotherapy response but few are really tumor-specific. TILs are also observed in ductal carcinoma in situ (DCIS), the earliest stage of breast cancer. We cannot predict which DCIS will progress towards invasive breast cancer (IBC). As DCIS could be more immunogenic than IBC, we studied the specificity of CD8+ and Treg (regulatory T cell) TILs extracted from 17 DCIS by reconstructing their TCR and screening them for recognition of various tumor antigens. For the CD8 TCRs, the results were negative. For Tregs TCRs, we observed the recognition of a mutated antigen by the most predominant clonotype of one tumor. Moreover, we observed activated Tregs in 64% of our DCIS samples. These results suggest that the tumor micro-environnement could already be immunosuppressive at the in situ stage of breast cancer., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

The objective of this thesis was to assess the functional exercise capacity and lung function in congenital heart disease (CHD) pediatric population. In the first study we observed that the most severe CHD patients show a lower exercise capacity and lung function. The observed correlation between cardiopulmonary exercise test (CPET) and spirometry was weak to moderate. The second study showed that the most frequent detected pattern was restrictive, while obstructive pattern was more frequent in non-cyanotic patients. In the third study, we observed that there was no training effect in children during the 6-minute walk test (6MWT), but there was an encouragement effect on the walked distance. For this reason, we think that guidelines should take these results into account. The fourth study revealed that in healthy children, the 1-minute Sit-to-Stand test (STST) is useful to quantify heart rate response during submaximal exercise. In the fifth study, we proposed an alternative equation to be used in those cases where CPET cannot be performed, containing the STST as a surrogate of peakVO2 in CHD children. Finally, in the sixth and last study, we did a validation of the Physical Activity Questionnaire in French., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Protein kinase RNA-activated (PKR) and Double-stranded RNA-specific adenosine deaminase (ADAR1) are two double stranded RNA binding proteins, respectively involved in the antiviral response to viruses and in the metabolism of dsRNA molecules. PKR is a cellular protein kinase, that in response to dsRNA molecules generated during viral infections, gets activated and phosphorylates the translation initiation factor, eIF2a, leading to translational shutoff and apoptosis. As PKR thereby acts as a potent antiviral effector, many viruses evolved mechanisms to counteract its antiviral response. Previous studies showed that Theiler’s murine encephalomyelitis virus (TMEV), a cardiovirus belonging to the Picornaviridae family, can block PKR activation through the activity of its Leader (L) protein, an accessory protein of the virus known to block IFN gene transcription and perturb nucleocytoplasmic trafficking. In the first part of this thesis I contributed to a work showing that the L protein likely renders PKR insensitive to dsRNA molecules, possibly through the activation of cellular kinases. Next, we analyzed PKR phosphorylation modifications in the hope to identify potential phosphorylation sites responsible for PKR inhibition by TMEV L. We observed that the Ser6 residue located 3aa before the first double-stranded RNA binding motif (DRBM1) of PKR could be phosphorylated. A phospho-mimetic mutation of this site was inhibiting PKR activation after poly(I:C) transfection or viral infection, especially when combined to a phospho-mimetic mutation of the Ser97 residue, located 3aa before the second double- stranded RNA binding motif (DRBM2). We propose a model according to which phosphorylation occurring upstream of DRBMs would tighten the interaction of the DRBMs with the catalytic domain, blocking PKR in a closed conformation, and making it unable to be activated. ADAR1 is an editing enzyme, causing deamination of adenosines into inosines in dsRNA molecules, thus destabilizi, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Cancer immunotherapies, such as monoclonal antibodies (mAbs) directed against PD-1, aim at boosting immune responses against tumor cells. They have become a standard of care for several types of cancer. However, a majority of patients do not respond to current immunotherapies. Resistance to PD-1 blockade can in part be explained by the action of TGF-b1, an immunosuppressive cytokine activated notably by regulatory T cells (Tregs) via a mechanism that requires protein GARP. We developed antibodies against GARP:TGF-b1 complexes that block TGF-b1 activation by Tregs and we evaluated their anti-tumor efficacy in tumor-bearing mice. We observed that anti-GARP:TGF-b1 mAbs induce the regression of tumors otherwise resistant to anti-PD-1, and we showed that combined blockade of GARP:TGF-b1 and PD-1 can exert anti-tumor activity via multiple modes of action. This may prove important for the selection of cancer patients who could benefit from this novel form of immunotherapy in the clinics., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

Tryptophan 2, 3-dioxygenase (TDO2) is a heme-containing enzyme constitutively expressed at high concentrations in the liver and responsible for L-tryptophan (L-Trp) homeostasis. TDO2 catalyses the cleavage of L-Trp’s pyrrole ring to produce N’-formylkynurenine; the first step of the kynurenine pathway. The expression of TDO2 in cancer cells leads to the depletion of L-Trp and an increase of KP catabolites, overall resulting in the suppression of the anti-tumour immune response. The present work describes the development of new (1H-indol-3-yl)-heterocyclic derivatives as TDO2 inhibitors through rational design, inspired from existing inhibitors. Evaluation of these compounds provided new insights regarding the structural modulations that can be accommodated inside the active site of TDO2 and their effect on inhibitory potency. Finally, in this same series of inhibitors, we also investigated the integration of a selenium atom as a bioisostere of lower molecular weight chalcogens., (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021

The cell envelope is essential for bacterial survival, as it forms a protective barrier that shelters the cell from its environment. This envelope consists of an outer and an inner membrane; both membranes are separated by the periplasm. In the periplasm, a mesh-like layer called peptidoglycan, or murein, is present and is important for cell shape and the protection against osmotic shock. The cell envelope includes three groups of proteins. During my thesis, I focused on studying one of these groups, which is lipoproteins. Lipoproteins, as their name subtly suggest, are globular proteins that are covalently linked to a lipid moiety which anchors them in one of the two membranes. This subset of proteins is involved in a wide range of vital bacterial processes. Lipoproteins can be retained in the inner membrane (IM) or can be transported to the outer membrane (OM). The sorting and targeting of lipoproteins between the two membranes is controlled by the Lol (Localization of lipoproteins) system. In this thesis, I show that lipoprotein sorting is affected by the presence of an intrinsically disordered region, that we call a linker, that is present at the N-terminal of half OM lipoproteins. First, I show that deleting the linker re-routes OM lipoproteins to the IM, which has functional consequences. Moreover, I found that the length, but not the sequence, of this linker is important for correct lipoprotein sorting, on the condition that the linker stays unstructured. Second, I provide mechanistic details on the function of the linker, showing that the disordered region works in a Lol-dependent manner. Finally, I propose a model where the linker optimizes OM targeting as well as the surface exposure of lipoproteins., (SP - Sciences de la santé publique) -- UCL, 2021

AMP-activated protein kinase (AMPK) is important for metabolic control in many tissues but its role in white adipose tissue (WAT) is controversial. AMPK activation has been reported to have both anti- and pro- lipolytic effects. Furthermore, AMPK activation has been proposed to have no effect or to inhibit glucose uptake. The main aim of this study was to investigate the mechanism by which AMPK activation regulates metabolism in WAT using a pharmacological activator combination. The first part of the thesis focused on insulin-stimulated lipogenesis and phosphorylation state of lipogenic enzymes in WAT. The second part deals with effects of AMPK activation on lipogenesis and lipolysis. In the last part, a MS-based phosphoproteomics strategy was set up with a view to searching for metabolic targets in WAT, (BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2021