Chronic rhinosinusitis (CRS) is a chronic inflammatory disease that can be subdivided into chronic rhinosinusitis sans nasal polyps (CRSsNP), chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD). Nasal polyps are a hallmark feature of CRSwNP and AERD. Although, the pathophysiology of polypogenesis is thought to be multifactorial, type 2 (allergic-type) immune responses and epithelial remodeling are considered to be central features. In polyp disease, epithelial remodeling and dysfunction leads to decreased epithelial diversity, with increased basal cells and decreased goblet and ciliated cells. A role for Wnt signaling is well established in cancer and fibrotic diseases, and recent studies have indicated that Wnt signaling is also upregulated in sinonasal polyposis, a non-cancerous disease. Wisp1, a downstream mediator of the Wnt pathway, is significantly increased in polyp disease compared to non-polyp disease. Wnt pathway ligands have been reported to induce the proliferation and impair differentiation of airway basal cells, but the direct effect of the downstream Wnt pathway gene, Wisp1, on respiratory basal epithelial cells is unknown. This study aims to investigate the role of Wisp1 on the proliferation, cell migration, and differentiation of human respiratory epithelial cells. In the current study, we found increased expression of WISP1 in nasal polyps examined directly ex vivo. Histological analysis of nasal polyps and WISP1 expression in primary basal epithelial cell cultures suggested epithelial production of Wisp1 as a feature of nasal polyposis. Using submerged and air-liquid interface (ALI) cell cultures, the effect of Wisp1 on proliferation, cell migration and differentiation was investigated. Increased basal cell accumulation and loss of differentiation are hallmarks of sinonasal polyposis. The chronic inflammatory environment present in polyp disease includes chronic increased WISP1 expression, which endorses a role for this protein in disease. The results of this study suggest that prolonged exposure to Wisp1 may lead to an increase in the cellular mass of respiratory basal epithelial cells, while limiting their ability to differentiate, thus allowing for unchecked accumulation. Taken together, our results suggest that Wisp1 may contribute to central features of nasal polyposis, thus identifying this protein as a potential target for future therapeutic intervention.

Background. The Cysteine-rich protein, Connective tissue growth factor, and Nephroblastoma overexpressed protein (CCN) family of matricellular proteins are signaling molecules found in the extracellular space, which can have pro-angiogenic, anti-inflammatory and anti-fibrotic properties. Their expression and role in repair and remodeling after myocardial infarction (MI) remains to be better elucidated. In this study, the age-associated expression of Nov (CCN3) and Wisp1 (CCN4) were examined post-MI in mice. Methods and Results. In vivo, MI was induced in young (6 week) and old (12-14 months) mice. Cardiac function was assessed by echocardiography, showing that LVEF was reduced in old mice (33.9%) at 14 days post-MI compared to young mice (43.9%; p=0.002). RT-qPCR analysis of harvested myocardial tissue revealed that mRNA expression of several matricellular proteins in healthy tissue was decreased by 2.5- to 5-fold in old compared to young mice (p=0.03 for Nov, p=0.04 for Wisp1, p=0.0002 for TnC, p=0.04 for TSP-1). Post-MI, mRNA expression of Nov was reduced in the infarct (by up to 13-fold; p<0.03) and border zone (by up to 16-fold; p<0.002) in old compared to young mice. Nov and Wisp1 protein expression was also reduced in old compared to young mice in the infarct and border zones; specifically, for Nov in the infarct zone (p=0.01) and the border zone (p=0.009) at 2 days post-MI and for Wisp1 in the infarct zone at 2 days (p=0.0003) and 14 days (p=0.003), along with 7 days post-MI in the border zone (p=0.0003). To identify possible sources of matricellular proteins, in vitro culture experiments were performed. The expression of Nov protein was increased (1.9-fold; p=0.006) in TGF-B stimulated cardiac fibroblasts after 48h, as was the expression of the myofibroblast marker a-SMA (1.7-fold; p=0.035). Wisp1 mRNA expression was increased (4.5-fold; p=0.03) in stimulated cardiac fibroblasts after 48h in a hypoxic environment. There was also a trend for increased mRNA expression of Nov (p=0.118) and Wisp1 (p=0.121) in M2 macrophages. Cardiac fibroblasts treated with Nov+TGF-B exhibited greater proliferation (by 29%; p0.01), as did those treated with Wisp1+TGF-B (by 16%; p<0.05). Treatment with Nov or Wisp1 led to an increase in viability of cardiac fibroblasts both in the presence (Nov; p=0.0004, Wisp1; p=0.01) and absence of TGF-B (Nov; p=0.0005, Wisp1; p=0.003). Summary. There is an age-associated difference in the expression of matricellular proteins Nov and Wisp1 between both healthy and MI mice. In vitro studies suggest that cardiac fibroblasts may produce Nov and Wisp1 upon their activation to myofibroblasts. The presence of these proteins was also shown to increase the proliferation and viability of fibroblasts. Therefore, reduced levels of Nov and Wisp1 in old mice may negatively affect the repair and remodeling process post-MI compared to young mice. A better understanding of Nov and Wisp1 function in aging and post-MI repair may help identify novel therapeutic targets for limiting damage post-MI and improving repair and heart function.

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Les immunothérapies de type immune checkpoint blockade (ICB) ont révolutionné les approches thérapeutiques en oncologie médicale et ont largement contribué au fait que l’immunothérapie est maintenant considérée comme le quatrième pilier des traitements anticancer, aux côtés d’approches traditionnelles telles que la chirurgie, la radiothérapie et la chimiothérapie. Malgré les résultats encourageants des études cliniques évaluant ce type d’immunothérapie, la majorité des patients décèderont des suites de leur maladie. Conséquemment, le domaine de recherche visant à comprendre les mécanismes de résistance aux immunothérapies est en expansion constante. Plusieurs stratégies visant à améliorer les issues cliniques ont été proposées, parmi lesquelles figurent: 1) la recherche de nouvelles cibles thérapeutiques dans le microenvironnement immun tumoral et; 2) les études de combinaisons thérapeutiques où une immunothérapie est jumelée à d’autres types de modalités thérapeutiques potentiellement synergiques. Chacune des études présentées dans cette thèse de recherche s’apparente à l’une ou l’autre de ces stratégies. Dans le cadre de notre première étude, nous démontrons que la protéine WISP1 représente une cible prometteuse à l’intérieur du microenvironnement de plusieurs types de tumeurs solides étant donné son association avec différentes variables pronostiques et proinflammatoires, ainsi qu’avec un programme épigénétique complexe, la transition épithélialemésenchymateuse (Epithelial-Mesenchymal Transition; EMT). De plus, nous démontrons que les niveaux d’expression de WISP1 sont significativement plus élevés au sein des tumeurs démontrant une résistance primaire aux immunothérapies de type ICB, particulièrement lorsque qu’une signature reliée à l’EMT peut être retrouvée de façon concomitante. Pour notre deuxième étude, nous avons utilisé des modèles murins in vivo de cancer pulmonaire non à petites cellules KRAS-mutés afin de tester différentes combinaisons thérapeutiques jumelant une thérapie dite ciblée (i.e., un inhibiteur de MEK) a différentes immunothérapies de type ICB. Nos résultats démontrent que l’ajout d’une immunothérapie anti-CTLA-4 à l’inhibiteur de MEK AZD6244 (selumetinib) et une immunothérapie anti-PD-L1 augmente significativement la survie, et que ces bénéfices sont associés à une diminution de marqueurs reliés à l’EMT. Il existe donc un lien commun entre ces deux études qui repose sur l’importance de l’EMT comme facteur favorisant la résistance thérapeutique aux immunothérapies. De plus, nous démontrons pour la première fois que les bénéfices associés à la triple combinaison thérapeutique susmentionnée peuvent être corrélés à une diminution d’expression de marqueurs liés à l’EMT. Par conséquent, nos résultats sont discutés en tant que base potentielle pour de futures études visant à réduire la résistance thérapeutique reliée à l’EMT. Nous discutons également de la valeur translationnelle de nos résultats à travers le développement d’une étude clinique. / Immune checkpoint blockade (ICB) has revolutionized therapeutic approaches in the field of medical oncology and has largely contributed to the fact that immunotherapy is now being regarded as the fourth pillar of cancer treatment alongside surgery, radiotherapy and chemotherapy. Despite encouraging results from clinical trials using ICB, most patients ultimately relapse or succumb to their disease. Therefore, the field of immunotherapeutic resistance research is rapidly expanding. Many strategies to improve ICB responses have been undertaken, including: 1) the search for novel, actionable targets in the immune tumor microenvironment (TME) and; 2) therapeutic combination studies where an ICB backbone is combined with different, synergistic treatment modalities. Each of the studies presented in this research thesis embraces one of these strategies. In our first study, we show that WISP1 represents a promising TME target in multiple solid tumor types by demonstrating its association with prognostic and pro-inflammatory variables, as well as to a complex epigenetic program termed Epithelial-Mesenchymal Transition (EMT). Furthermore, we show that increased WISP1 expression is associated to primary resistance to ICB, particularly when EMT-related signatures are found concomitantly. In our second study, we used in vivo mouse models of KRAS-mutant Non-Small Cell Lung Cancer (NSCLC) to test different therapeutic combinations of targeted therapies (i.e., MEK inhibitor) and ICB. We found that the addition of anti-CTLA-4 ICB to MEK inhibitor AZD6244 (selumetinib) and anti-PD-L1 ICB increases survival, and that these benefits are associated with the downregulation of EMT-related markers. Therefore, there exists a common link between these studies, which relies on the significance of EMT as a detrimental factor within the TME and its association with ICB resistance. Moreover, we show for the first time that the benefits of ICB combination therapy can be associated to the downregulation of EMT markers in vivo. Consequently, we discuss how our results may constitute the basis for future work aiming at reducing EMT-mediated therapeutic resistance, as well as the translational relevance of our pre-clinical results through the development of a clinical trial.