ED Sciences de la Vie et de la Santé
Development of an innovative tubular lung organoid to model chronic obstructive pulmonary disease (COPD)
by Katharina RAASCH (Centre de recherche Cardio-Thoracique de Bordeaux)
The defense will take place at 14h00 - Amphithéâtre IHU Liryc Hôpital Xavier Arnozan Avenue du Haut Lévêque 33604 Pessac cedex
in front of the jury composed of
- Valérie BESNARD - Maîtresse de conférences - Université Sorbonne Paris Nord - Rapporteur
- Maja FUNK - Cadre scientifique - Institute of Lung Health and Immunity - Rapporteur
- Pascale DUFOURCQ - Professeure des universités - Université de Bordeaux - Examinateur
- Vincent SAUZEAU - Directeur de recherche - INSERM - Examinateur
Airflow limitation is the hallmark of obstructive pulmonary diseases, with the distal airways being a major site of obstruction. Despite the availability of multiple in vitro bronchial models, no culture system currently replicates the architecture and function of small airways in obstructive diseases. During my thesis, I aimed to engineer a so-called bronchioid model by encapsulating human bronchial adult stem cells derived from clinical samples within an alginate-based tubular scaffold. This system enabled the spontaneous self-organization of epithelial cells into a tubular structure mimicking the bronchiolar architecture. Collapse of the tube was observed within a few days; however, the addition of Y27632, a ROCK inhibitor, allowed the bronchioid to be maintained in culture for up to 21 days with good viability. Three-dimensional imaging, gene expression analysis (RT-qPCR and single cell transcriptomic) and flow cytometry confirmed epithelial differentiation into ciliated and goblet cells, as well as the formation of epithelial junctions. In bronchioids derived from cells from patients with COPD we evidenced altered differentiation of epithelial cells with a more secretory phenotype. Ciliary beating was observed, with a decreased frequency in bronchioids derived from COPD patients. Epithelial cells were infected with rhinovirus, which was introduced into the lumen of the model. It was also possible to establish an air–liquid interface by perfusing air at a controlled flow rate. This air–liquid interface appears to modulate the expression of certain genes. To further enhance the model, a concentric peripheral layer of smooth muscle cells was added, simulating the epithelial-mesenchymal trophic unit. Their capacity for contraction and proliferation was assessed, and epithelial-mesenchymal interactions were analysed using immunostaining, RT-qPCR, and flow cytometry. Here, we provide proof of concept for a perfusable bronchioid with proper mucociliary and contractile functions. The key advantages of this approach—air‒liquid interface integration, lumen accessibility, potential integration of different cell types, pathological feature recapitulation—position our pulmonary organoid model as a powerful tool for preclinical studies.
Decoding molecular and cellular mechanisms of POMC-lineage neuron programming in maternal obesity
by Ho Yin Thomas LEE (Neurocentre Magendie)
The defense will take place at 14h00 - Salle de conférences 1 et 2 146 rue Léo Saignat, 33000 Bordeaux, France
in front of the jury composed of
- Carmelo QUARTA - Chargé de recherche - Neruocentre Magendie, Bordeaux Neurocampus, Doctoral School of Health and Life Sciences, University of Bordeaux - Directeur de these
- Paolo GIACOBINI - Directeur de recherche - Lille Neuroscience & Cognition, University of Lille - Rapporteur
- Amandine GAUTIER-STEIN - Chargée de recherche - Institut National de la Santé et de la Recherche Médicale U1213, Université Claude Bernard Lyon - Rapporteur
- Muriel DARNAUDERY - Professeure des universités - NutriNeurO, Bordeaux Neurocampus, Soctoral School of Health and Life Sciences, University of Bordeaux - Examinateur
Globally, maternal obesity affects an estimated 39 million pregnancies annually and presents a significant public health concern, particularly in regions where prevalence exceeds 60%. Characterised by chronic low-grade inflammation and metabolic dysfunction, maternal obesity disrupts placental function and foetal development, contributing to long-term metabolic consequences in the offspring. This thesis investigates the molecular mechanisms through which maternal obesity programs offspring metabolic dysfunction, focusing on the hypothalamic transcription factor Tbx3 within the proopiomelanocortin (POMC) neuronal lineage. This study uses a mouse model to reveal that Tbx3 is a critical integrator of maternal metabolic cues during early hypothalamic development. Deletion of Tbx3 in POMC neurons predisposes male offspring to impaired glucose homeostasis and increased adiposity, markedly intensified by exposure to maternal obesity. Offspring lacking Tbx3 and exposed to a maternal high-fat diet throughout gestation and lactation exhibited severe metabolic phenotypes, including fasting hyperglycaemia, suppressed acute insulin secretion, and early-onset hyperleptinemia and hyperinsulinemia—hallmarks of metabolic syndrome. Ex vivo and in vivo analyses revealed early islet dysfunction and potential disruptions in neuro-pancreatic communication. In contrast, female offspring showed resilience to the metabolic impacts of maternal obesity, despite being affected by Tbx3 deletion alone, suggesting the presence of sex-specific protective mechanisms. Molecular profiling revealed that maternal obesity alters the expression of Tbx3, lineage specification genes (Ascl1), and functional markers (Pomc, Pcsk1) in POMC neurons during critical early postnatal periods. Transcriptomic analysis at postnatal day 2 identified distinct gene expression profiles for each experimental group, with convergence on pathways involved in neuronal fate, endocrine development, and hormonal signalling. Leptin signalling emerged as a potentially dysregulated upstream regulator. Lineage tracing showed that Tbx3 deletion leads to a progressive loss of POMC neurons, while maternal obesity predominantly affects the identity and function of the remaining neurons, dependent on Tbx3 presence. Histological assessments revealed that maternal obesity, compounded by Tbx3 deletion, impairs axonal projections from POMC neurons to key hypothalamic nuclei, potentially disturbing downstream circuits involved in energy homeostasis. The pronounced metabolic dysfunction observed in male offspring with Tbx3 deletion born to obese dams likely results from a synergistic effect: Tbx3 loss impairs both neuron number and connectivity. At the same time, maternal obesity further disrupts neuropeptidergic identity and signalling. Additionally, maternal obesity-induced leptin resistance during early development may interfere with autonomic innervation of peripheral metabolic organs, contributing to the severity of metabolic impairments in offspring. In conclusion, this thesis identifies Tbx3 within the POMC neuronal lineage as a vital developmental regulator whose function is susceptible to the maternal metabolic environment. These findings highlight how maternal obesity can interact with genetic susceptibility to impair hypothalamic development and offspring metabolic health in a sex-specific manner. Understanding these developmental origins provides a foundation for targeted interventions during critical windows, potentially disrupting the maternal transmission of metabolic disease risk.