Les contractions rythmiques résultent de l’activité stimulatrice du nœud sinusal dans le cœur et des cellules interstitielles de Cajal (CICs) dans les intestins. Nous avons découvert un nouveau syndrome résultant d’une combinaison de la maladie du nœud sinusal (MNS) et de la pseudo-obstruction intestinale chronique (POIC). Ce syndrome, que nous avons nommé Chronic Atrial and Intestinal Dysrhythmia (CAID), résulte d’une mutation récessive du gène SGO1 (K23E). Cependant, les rôles connus de SGO1 n'expliquent pas l'apparition postnatale du syndrome ni la pathologie spécifique, suggérant que des rôles non canoniques de SGO1 conduisent aux manifestations cliniques observées. Cette hypothèse est supportée par la comparaison de CAID avec les autres cohésinopathies qui présentent principalement des phénotypes développementaux sans ou avec des défauts légers du cycle cellulaire. Ce projet visait à une découverte non biaisée des mécanismes non canoniques expliquant le syndrome CAID en utilisant le dogme de la biologie moléculaire (ADN→ARNm→protéine) comme ligne directrice. Pour ce faire, nous avons effectué des criblages multi-omiques sur des fibroblastes de peau de patients CAID et de contrôles sains. Les résultats des criblages ont été validés par électrophysiologie, étude des voies de signalisation pertinentes, immunohistochimie, pyroséquençage des rétrotransposons LINE-1 et quantification des marques d’histones. Nos études multi-omiques ont confirmé des changements dans la régulation du cycle cellulaire, mais aussi dans la conduction cardiaque et la fonction des muscles lisses. Plus spécifiquement, plusieurs canaux potassiques étaient sous-régulés. L’électrophysiologie a confirmé une diminution du courant potassique rectifiant entrant (IK1). L'immunohistochimie des coupes intestinales de patients CAID a confirmé l’augmentation de l’expression de SGO1 et BUB1, un régulateur de la voie de signalisation TGF-β. De plus, la voie canonique de TGF-β est augmentée et est découplée de la voie non canonique. Au niveau épigénétique, une signature unique d’hyperméthylation et de fermeture de la chromatine a été observée. Ce qui est soutenu par l’augmentation de la méthylation de H3K9me3 et de H3K27me3. En conclusion, le syndrome CAID est associé à plusieurs changements ayant possiblement un effet cumulatif plutôt que d’une seule voie de signalisation dérégulée. Nos résultats désignent la perturbation du courant IK1, la dérégulation de la signalisation TGF-β, l’hyperméthylation de l’ADN et la compaction de la chromatine comme éléments conducteurs potentiels des manifestations cliniques observées. La voie TGF-β et les changements épigénétiques peuvent être ciblées par des médicaments existants, constituant ainsi des cibles thérapeutiques prometteuses pour le traitement du syndrome CAID. / Rhythmic contractions are driven by the pacemaker activity of the cardiac sinus node and the intestinal interstitial cells of Cajal (ICC). We have discovered a new syndrome resulting from a combination of sick sinus syndrome (SSS) and chronic intestinal pseudo-obstruction (CIPO). This syndrome, which we have named Chronic Atrial and Intestinal Dysrhythmia (CAID), results from a recessive mutation in the SGO1 gene (K23E). However, the known roles of SGO1 do not explain the postnatal onset of the syndrome nor the specific pathology, suggesting that non-canonical roles of SGO1 lead to the clinical manifestations observed. This hypothesis is supported by the comparison of CAID with other cohesinopathies which mainly exhibit developmental phenotypes without or with mild cell cycle defects. This project aimed towards an unbiased discovery of noncanonical mechanisms explaining CAID using the molecular biology dogma (DNA→mRNA→protein) as a guideline. We performed multi-omic screens on skin fibroblasts from CAID patients and healthy controls. Screening results were validated by electrophysiology, study of relevant signaling pathways, immunohistochemistry, LINE-1 retrotransposon pyrosequencing, and histone marks quantification. Our multiomics analyses confirmed changes in cell cycle regulation, but also in cardiac conduction and smooth muscle function. More specifically, several potassium channels were downregulated. Electrophysiology studies confirmed a decrease in the inward rectifier potassium current (IK1). Immunohistochemistry in CAID patient’s intestinal sections confirmed overexpression of SGO1 and BUB1, a regulator of TGF-β signaling pathway. Additionally, the canonical TGF-β signaling was increased and decoupled from noncanonical signaling. At the epigenetic level, CAID patient fibroblasts have a unique signature of hypermethylation and chromatin closure. This is supported by the increased methylation of H3K9me3 and H3K27me3. In conclusion, CAID syndrome is associated with several changes that, may have a cumulative effect rather than a single deregulated signaling pathway. Our results reveal the disturbance of the IK1 current, the deregulation of TGF-β signaling, DNA hypermethylation and chromatin accessibility changes as potential conductors of intestinal and cardiac manifestations of CAID syndrome. In particular, the TGF-β pathway and epigenetic changes, may be targeted by existing drugs, thus constituting promising therapeutic targets for the treatment of CAID syndrome.

<p>Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer in part due to inherent resistance to chemotherapy, including the first-line drug gemcitabine. Gemcitabine is a nucleoside pyrimidine analog that has long been the backbone of chemotherapy for PDAC, both as a single agent, and more recently, in combination with nab-paclitaxel. Since gemcitabine is hydrophilic, it must be transported through the hydrophobic cell membrane by transmembrane nucleoside transporters. Human equilibrative nucleoside transporter-1 (hENT1) and human concentrative nucleoside transporter-3 (hCNT3) both have important roles in the cellular uptake of the nucleoside analog gemcitabine. While low expression of hENT1 and hCNT3 has been linked to gemcitabine resistance clinically, mechanisms regulating their expression in the PDAC tumor microenvironment are largely unknown. We identified that the matricellular protein Cysteine-Rich Angiogenic Inducer 61 (CYR61) negatively regulates expression of hENT1 and hCNT3. CRISPR/Cas9-mediated knockout of CYR61 significantly increased expression of hENT1 and hCNT3 and cellular uptake of gemcitabine. CRSIPR-mediated knockout of CYR61 sensitized PDAC cells to gemcitabine-induced apoptosis. Conversely, adenovirus-mediated overexpression of CYR61 decreased hENT1 expression and reduced gemcitabine-induced apoptosis. We demonstrate that CYR61 is expressed primarily by stromal pancreatic stellate cells (PSCs) within the PDAC tumor microenvironment, with Transforming Growth Factor- β (TGF-β) inducing the expression of CYR61 in PSCs through canonical TGF-β-ALK5-Smad signaling. Activation of TGF-β signaling or expression of CYR61 in PSCs promotes resistance to gemcitabine in an in vitro co-culture assay with PDAC cells. Our results identify CYR61 as a TGF-β induced stromal-derived factor that regulates gemcitabine sensitivity in PDAC and suggest that targeting CYR61 may improve chemotherapy response in PDAC patients.</p> / Dissertation

<p>An important step in tumorgenesis is the acquisition of cellular immortality. Tumor cells accomplish this by activating the enzyme telomerase, and thereby avoiding replicative senescence. The aim of this thesis was to study the activity and regulation of telomerase in a panel of malignant cell types.</p><p>We found that TGF-β1 (transforming growth factor-β1) mediated differential effects on telomerase activity in five ATC (anaplastic thyroid carcinoma) cell lines. Cells that harbored a <i>p53</i> mutation responded by up-regulation of telomerase activity after TGF-β1 treatment, whereas cell lines displaying wt <i>p53 </i>responded by down-regulation of telomerase activity. Thus, these results indicate a possible connection between <i>p53</i> genotype and telomerase response to TGF-β1 treatment. Furthermore, the decreased telomerase activity appeared to be due to transcriptional repression of the <i>hTERT</i> promoter and the increased activity possibly involved hTERT activation via phosphorylation. </p><p>We have previously shown that IFNs (interferons) sensitize MM (multiple myeloma) cells to Fas-mediated apoptosis. In the present investigation both IFN-α and IFN-γ down regulated telomerase activity in the MM cell line U-266-1970. The mechanism underlying the reduction of telomerase activity by IFN was shown to be transcriptional repression of the <i>hTERT </i>gene. We suggest that one potential mechanism whereby IFN sensitize MM cells to Fas-mediated apoptosis is by repressing <i>hTERT</i> activity at the transcriptional level. </p><p>In the next study we demonstrated that basal telomerase activity is not a key determinant of sensitivity to cytotoxic drugs in ESCC (esophageal squamous cell carcinoma) cell lines. Furthermore, we observed no correlation between <i>c-Myc</i> amplification, <i>p53</i> mutations and high telomerase activity levels in these cell lines. </p><p>Finally, neuroblastoma cell lines were shown to up-regulate telomerase activity in response to hypoxic exposure and the main regulatory mechanism was not mediated by increased hTERT mRNA expression. This finding might constitute an adaptive stress response of tumor cells exposed to hypoxia. </p>

An important step in tumorgenesis is the acquisition of cellular immortality. Tumor cells accomplish this by activating the enzyme telomerase, and thereby avoiding replicative senescence. The aim of this thesis was to study the activity and regulation of telomerase in a panel of malignant cell types. We found that TGF-β1 (transforming growth factor-β1) mediated differential effects on telomerase activity in five ATC (anaplastic thyroid carcinoma) cell lines. Cells that harbored a p53 mutation responded by up-regulation of telomerase activity after TGF-β1 treatment, whereas cell lines displaying wt p53 responded by down-regulation of telomerase activity. Thus, these results indicate a possible connection between p53 genotype and telomerase response to TGF-β1 treatment. Furthermore, the decreased telomerase activity appeared to be due to transcriptional repression of the hTERT promoter and the increased activity possibly involved hTERT activation via phosphorylation. We have previously shown that IFNs (interferons) sensitize MM (multiple myeloma) cells to Fas-mediated apoptosis. In the present investigation both IFN-α and IFN-γ down regulated telomerase activity in the MM cell line U-266-1970. The mechanism underlying the reduction of telomerase activity by IFN was shown to be transcriptional repression of the hTERT gene. We suggest that one potential mechanism whereby IFN sensitize MM cells to Fas-mediated apoptosis is by repressing hTERT activity at the transcriptional level. In the next study we demonstrated that basal telomerase activity is not a key determinant of sensitivity to cytotoxic drugs in ESCC (esophageal squamous cell carcinoma) cell lines. Furthermore, we observed no correlation between c-Myc amplification, p53 mutations and high telomerase activity levels in these cell lines. Finally, neuroblastoma cell lines were shown to up-regulate telomerase activity in response to hypoxic exposure and the main regulatory mechanism was not mediated by increased hTERT mRNA expression. This finding might constitute an adaptive stress response of tumor cells exposed to hypoxia.

Ο ρινικός πολύποδας (ΡΠ) είναι μια χρόνια φλεγμονώδης νόσος του ρινικού βλεννογόνου, η οποία χαρακτηρίζεται από διήθηση φλεγμονωδών κυττάρων, όπως ηωσινόφιλα, λεμφοκύτταρα και πλασμοκύτταρα, τροποποιήσεις στη διαφοροποίηση του επιθηλίου και ανάπλαση ιστού, που περιλαμβάνει υπερπλασία της βασικής μεμβράνης, συσσώρευση εξωκυττάριου υλικού και οίδημα. Ο παράγοντας αναστολής της μετανάστευσης μακροφάγων (MIF) είναι μία μοναδική κυτταροκίνη με σημαντικό ρόλο στο σηπτικό σόκ και στις χρόνιες φλεγμονώδεις και αυτοάνοσες ασθένειες.Παράγεται από ενεργοποιημένα Τ-κύτταρα, μακροφάγα αλλά και από ποικιλία άλλων κυττάρων. Εκτός των άλλων, έχει βρεθεί ότι επάγει την έκφραση της IL-6 από διάφορα κύτταρα και ανταγωνίζεται την κατασταλτική επίδραση των γλυκοκορτικοειδών στην έκφρασή της. Απαντάται σε αυξημένα επίπεδα στο ρινικό πολύποδα. Ο αυξητικός παράγοντας μετασχηματισμού-β1 (TGF-β1) θεωρείται ένας αντιφλεγμονώδης παράγοντες, ο οποίος ανταγωνίζεται τη δράση της IL-1β και του TNF-α, στην έκφραση της ΜΜΡ-1 και ΜΜΡ-3. Διεγείρει επίσης την έκφραση του ΤΙΜΡ-1, του κολλαγόνου τύπου Ι και της IL-6 και λόγω των δράσεών του αυτών εμπλέκεται ισχυρά στις διαδικασίες ίνωσης. Απαντάται σε σημαντικά επίπεδα στο ρινικό πολύποδα. Η IL-6 είναι μία Th2 πολυλειτουργική κυτταροκίνη η οποία εμπλέκεται σε ποικίλες φλεγμονώδεις καταστάσεις. Διεγείρει την ανάπτυξη των ινοβλαστών, αυξάνει τη σύνθεση και εναπόθεση του κολλαγόνου και μειώνει την αποικοδόμησή του. Απαντάται σε αυξημένα επίπεδα στο ρινικό πολύποδα και θεωρείται σημαντικός παθαγενετικός παράγοντας μέσω της επαγωγής του σχηματισμού των πλασμοκυττάρων και της σύνθεσης συστατικών του στρώματος, και της προαγωγής της σύνθεσης και εναπόθεσης κολλαγόνου και της ανάπλασης ιστού. Σκοπός της παρούσης εργασίας είναι η μελέτη της συμβολής του MIF και του TGF-β1 στη παραγωγή της IL-6 από ινοβλάστες ρινικού πολύποδα, των σηματοδοτικών μονοπατιών που εμπλέκονται, και η διερεύνηση της πιθανής συνεργειακής δράσης τους στην έκφραση της κυτταροκίνης. Τόσο ο TGF-β1 (0,01-1 ng/ml) όσο και ο MIF (1-100 ng/ml) προκάλεσαν διέγερση της έκφραση της IL-6 σε ινοβλάστες ρινικού πολύποδα κατά δοσοεξαρτώμενο τρόπο, η οποία κατεστάλλει σημαντικά από αναστολέις των ΜΑΡ κινασών και της ΡΙ-3 κινάσης. Ο TGF-β1 (1 ng/ml) προκάλεσε επίσης χρονοεξαρτώμενη αύξηση στα επίπεδα της IL-6 γιά χρόνο επώασης μέχρι 2 ώρες, τα οποιά έμεινα σταθερά στη συνέχεια μέχρι τις 72 ώρες επώασης, επαγωγή της παραγωγής ενδοκυτταρικών ενεργών ειδών οξυγόνου (ROS) με μέγιστο σε δύο χρόνους επώασης 20 και 180 λεπτά, και ενεργοποίηση των ERK κινασών από 15-60 λεπτά επώασης, με μέγιστη ενεργοποίηση στα 30 λεπτά, και στη συνέχεια πτώση στα επίπεδα του μάρτυρα. Ενώ ο MIF σε συγκέντρωση 1-100 ng/ml προκάλεσε μικρή μείωση στην έκφραση της φωσφατάσης-1 των ΜΑΡΚ (ΜΚΡ-1), ο TGF-β1 αντίθετα, σε συγκέντρωση 1 ng/ml προκάλεσε αύξηση στην έκφραση της ΜΚΡ-1 σε δύο χρόνους επώασης 0,5 και 24 ώρες. Μετά από επώαση των ινοβλαστών ρινικού πολύποδα παρουσία TGF-β1 (1 ng/ml) και MIF (100 ng/ml) μαζί, δεν παρατηρήθηκε συνεργειακή επίδραση στην έκφραση της IL-6. Ενώ τόσο ο TGF-β1 όσο και ο MIF προκάλεσαν διέγερση στην έκφραση της IL-6 από ινοβλάστες πνεύμονα, δεν παρατηρήθηκε και πάλι συνεργειακή επίδρασή τους στην έκφραση της κυτταροκίνης αυτής. Συμπερασματικά, φαίνεται ότι ο MIF, ενώ ανταγωνίζεται την κατασταλτική επίδραση των γλυκοκορτικοειδών στην έκφραση της IL-6 μέσω της ρύθμισης των επιπέδων της ΜΚΡ-1, δεν έχει την ίδια επίδραση στην έκφραση της IL-6 από τον TGF-β1, μέσω ρύθμισης της έκφρασης της φωσφατάσης αυτής. Από την άλλη μεριά η επαγωγή της έκφρασης της ΜΚΡ-1 από τον TGF-β1 φαίνεται να μην επηρεάζει την παραγωγή της IL-6 για μικρούς χρόνους επώασης, μέχρι 2 ώρες, πιθανόν λόγω της ανασταλτικής επίδρασης των ROS, που επάγονται από τον TGF-β1, στη δράση της ΜΚΡ-1, ενώ την επηρεάζει για μεγάλους χρόνους επώασης , εξ ού και τα σταθερά επίπεδα της IL-6 μέχρι και 72 ώρες επώασης. / Nasal polyp (NP) is a chronic inflammatory condition of nasal mucosa, characterized by infiltration of inflammatory cells such as eosinophils, lymphocytes and plasma cells, alterations in epithelial differentiation and tissue reconstruction, involving hyperplasia of basal membrane, accumulation of extracellular material and edema. Macrophage migration inhibitory factor (MIF) is a unique cytokine, the role of which in chronic inflammatory and autoimmune diseases and septic shock pathogenesis is very important. MIF is produced by activated T-lymphocytes, macrophages and a plethora of other cells. MIF appears to antagonize the suppressive effect of glucocorticoids as well as induce the expression of IL-6 in multiple cells. High levels of MIF are detected in nasal polyps. Transforming growth factor- β1 (TGF-β1) is an anti-inflammatory factor antagonizing the positive effect of IL-1β and TNF-α on the expression of MMP-1 and MMP-3, TGF-β1 also stimulates the expression of TIMP-1, collagen type I and IL-6; because of these effects, TGF-β1 is involved in the process of fibrosis. TGF-β1 levels in nasal polyps are significantly elevated. IL-6 is a cytokine participating in Th2 response and consequently is involved in a subset of inflammatory reactions. IL-6 stimulates the growth of fibroblasts, increases the production and deposition of collagen and it decreases its degradation. IL-6 is found in nasal polyps at elevated levels and it is thought to be an important pathogenic factor acting mainly in tissue reconstruction, stimulation of plasma cell differentiation, production of stromal material, promotion of collagen synthesis and deposition. The purpose of this paper is to study the effect of MIF and TGF-β1 in IL-6 production by fibroblasts isolated from nasal polyps, dissect the signaling pathways involved, and investigate their synergistic effect on the production of IL-6. Both TGF-β1 (0, 01-1 ng/ml) and MIF (1-100 ng/ml) induced IL-6 expression in nasal polyp fibroblasts in a dose-dependent manner. This effect was significantly suppressed by inhibitors of MAP and PI-3 kinase pathways. TGF-β1 (1 ng/ml) also induced IL-6 expression within 2 hours of administration. Elevated IL-6 levels remained unchanged for 72h further. TGF-β1 also promoted the production of intracellular reactive oxygen species (ROS), which peaked in 20 and 180 minutes and the activation of ERK kinase, peaked in 30 minutes. While MIF, at a concentration of 1-100 ng/ml, caused a slight decrease in the expression of phospatase-1 of MAPK (MKP-1), TGF-β1, at a concentration of 1 ng/ml, increased the expression of MKP-1. No synergistic effect on IL-6 expression was detected after incubating nasal polyp and lung fibroblasts together with TGF-β1 (1 ng/ml) and MIF (100 ng/ml). In conclusion, while MIF antagonizes the suppressive effect of glucocorticoids on the expression of IL-6 by regulating the levels of MKP-1, it fails to antagonize the TGF-β1 inducing effect on IL-6 via MKP-1. The induction of MKP-1expression by TGF-β1 is not affecting the production of IL-6 after short incubation periods; this effect can be explained by the inhibitory effect of TGF-β1 induced ROS on MKP-1. After prolong incubation with TGF-β1 (up to 72 hours), IL-6 levels remain elevated.

No description available.

Vascular remodelling due to excessive proliferation and apoptosis resistance of pulmonary arterial smooth muscle (PASMCs) and endothelial cells (ECs) has been attributed to the pathogenesis of pulmonary arterial hypertension (PAH). It is an incurable cardiovascular disorder, which leads to right heart failure and death, if left untreated. Heterozygous germline mutations in the bone morphogenetic protein receptor type II (BMPR2) have been linked with the majority (~75%) of the familial form of the disease (HPAH). Mutations in the BMPR2 gene impinge upon the BMP signalling which perturbs the balance between BMP and TGF-β pathways leading to the clinical course of the disease. Current therapies were discovered prior to the knowledge that PAH has substantial genetic components. Hence, this study aims to identify novel therapeutic intervention and provide novel insights into how the dysfunctional BMPRII signalling contributes to the pathogenesis of PAH. This work demonstrates that cryptolepines and FDA approved drugs (doxorubicin, taxol, digitoxin and podophyllotoxin) inhibit the excessive proliferation and induce apoptosis in BMPR2 mutant PASMCs by modulating the BMP and TGF-β pathways. Moreover, established drug PTC124 has also been tested but has failed to promote translational readthrough. I have also shown that dysregulated apoptosis of PASMCs and HPAECs is mediated through the BMPRII-ALK1-BclxL axis. Finally, the siRNA screen targeting approximately 1000 genes has identified novel proteins including PPP1CA, IGF-1R, MPP1, MCM5 and SRC each capable of modulating the BMPRII signalling. Taken together, this study for the very first time has identified novel compounds with pro-BMP and anti-TGFβ activities which may provide therapeutic intervention prior to or after the onset of PAH. / Commonwealth Scholarship Commission in the UK / The full text will be available at the end of the embargo period, 31st July 2024.

Introduction : La prééclampsie (PE) est un trouble hypertensif caractérisé par une tension artérielle au-dessus de 140/90 mmHg et touche 2 à 8% des grossesses globalement. À ce jour, la plupart des médicaments ne peuvent traiter ou prévenir la PE. La thrombospondine-1 (THBS1) est un facteur anti-angiogénique et un activateur principal du TGF-β, ce qui pourrait également être impliqué dans l'altération de l'angiogenèse dans les placentas prééclamptiques. Objectif : Notre objectif est de décrire l'expression de la THBS1 et de tester l’effet d’un inhibiteur, le peptide LSKL, sur la vascularisation placentaire dans les placentas d'un modèle murin de PE (in vivo) et sur la capacité angiogénique des cellules endothéliales placentaires humaines (in vitro). Méthodes : L'expression de THBS1 a été mesurée dans les placentas de souris par western blot et dans les placentas humains par immunohistochimie (IHC). Des cellules endothéliales placentaires (pECs) extraites de placentas humains et des souris enceintes hétérozygotes femelles surexprimant la rénine et l’angiotensinogène humaines (hR+A+) sont traitées avec LSKL, ou son peptide témoin SLLK (cellules : 30 μmol/L pendant24h ; animal 129 μmol/mL s.c. au jour de gestation 14,5). Des pEC ont été soumises à des conditions contrôle (8% d’oxygène) ou hypoxie (0,5% d’oxygène) ou thrombine (10 unités/mL) pendant 24 h. L’angiogenèse cellulaire a été évaluée sur matrigel, les protéines évaluées par western blot et la localisation de la THBS1 ainsi que la vascularisation placentaire par IHC. Résultats : Le traitement avec LSKL augmente le nombre de tubes formées dans les pECs exposées à la thrombine ou à l’hypoxie. L’inhibiteur de la voie canonique du TGF-β, ALK5/Smad2/3 (SB-505124, SB), n’a pas modifié la capacité de formation de tubes, contrairement à l’inhibiteur de la voie non canonique, TAK1/p38 ((5Z) -7-oxozeaenol, (OXO) qui a réduit la capacité angiogénique (p<0,05). Chez le modèle de souris de PE, LSKL a significativement amélioré la vascularisation placentaire, évaluée par le contenu des cellules endothéliales CD31+ marquées par IHC (p<0,05), qui s’est accompagnée d’une phosphorylation réduite de TAK1 et ERK dans ce tissu. Conclusion : Nos résultats indiquent une augmentation de l’expression de la THBS1 dans les vaisseaux et cellules endothéliales placentaires des grossesses atteintes de PE, ainsi qu’un effet pro-angiogénique placentaire du LSKL par inhibition de la vie non-canonique du TGF-β. Ces résultats contribueront à identifier de nouvelles cibles thérapeutiques capables d'améliorer la vascularisation placentaire dans PE. / Introduction: Pre-eclampsia (PE) is a hypertensive disorder characterized by blood pressure above 140/90 mmHg and affects 2% to 8% of pregnancies globally. To date, most drugs cannot treat or prevent PE. Thrombospondin-1 (THBS1) is an anti-angiogenic factor and a major activator of TGF-β, which may also be involved in impaired angiogenesis in pre-eclamptic placentas. Objective: Our aim is to describe the expression of THBS1 and to test the effect of its inhibitor, LSKL peptide, on placental vascularization in placentas from a mouse model of PE (in vivo) and on the angiogenic capacity of human placental endothelial cells (in vitro). Methods: THBS1 expression was measured in placentas of mouse by western blot and in human placentas by immunohistochemistry (IHC). Placental endothelial cells (pECs) extracted from hu-man placentas and pregnant female heterozygous mice overexpressing human renin and angio-tensinogen (hR+A+) were treated with LSKL or its control peptide SLLK (cells: 30 μmol/L for 24h; animals: 129 μmol/mL subcutaneously on gestation day 14.5). pECs were subjected to control conditions (8% oxygen) or hypoxia (0.5% oxygen) or thrombin (10 units/mL) for 24 hours. Cellular angiogenesis was assessed on Matrigel, proteins were evaluated by western blot, and the locali-zation of THBS1 as well as placental vascularization were examined by immunohistochemistry (IHC). Results: Treatment with LSKL increased the number of tubes formed in pECs exposed to thrombin or hypoxia. The inhibitor of the canonical TGF-β pathway, ALK5/Smad2/3 (SB-505124, SB), did not alter tube formation capacity, unlike the inhibitor of the non-canonical pathway, TAK1/p38 ((5Z)-7-oxozeaenol, (OXO)), which reduced angiogenic capacity. In the mouse model of PE, LSKL significantly improved placental vascularization, assessed by CD31+ endothelial cell content marked by IHC, which was accompanied by reduced phosphorylation of TAK1 and ERK in this tissue. Conclusion: Our results indicate an increase in THBS1 expression in the vessels and placental endothelial cells of pregnancies affected by PE, as well as a pro-angiogenic effect of LSKL through the inhibition of the non-canonical TGF-β pathway. These findings contribute to identifying new therapeutic targets capable of improving placental vascularization in PE.

Oral Submucous Fibrosis (OSF) is a chronic inflammatory disease resulting in progressive fibrosis of the oral tissues that can cause difficulty in chewing, swallowing, speaking, and mouth opening. Epidemiological studies have shown that OSF is a precancerous condition and 2-8% of the OSF patients develop squamous cell carcinoma. This disease affects 0.5% of the population in the Indian subcontinent and is now a growing public health issue in many parts of the world. Habit of chewing betel quid has been proposed as an important etiological factor in the development of this disease and is coline, a principle alkaloid of areca nut is considered as major causative factor for OSF development. But the exact molecular mechanism of OSF pathogenesis is not known. Therefore, we set the following objectives for this study: 1) Gene expression profiling of OSF using microarray. 2) Role of areca nut constituents in OSF pathogenesis. 3) Effect of areca nut on epithelial and fibroblast cells. In order to delineate the possible molecular mechanism of OSF pathogenesis, we took microarray approach and identified differentially regulated genes in ten OSF tissues against eight pooled normals using whole human genome oligonucleotide arrays. Microarray results revealed differential expression of 5288 genes (p≤0.05 and Fold change≥1.5), among them 2884 were up-regulated and 2404 were down-regulated. Validation employing quantitative real-time PCR and immunohistochemistry confirmed up-regulation of transforming growth factor-β1 (TGF-β1), TGFBI, THBS1, SPP1, TIG1 and down-regulation of bone morphogenic protein 7 (BMP7), C4orf7 and ALOX12 in OSF tissues. Furthermore, activation of TGF-β pathway was evident in OSF tissues as demonstrated by p-SMAD2 strong immunoreactivity. Analysis of IHC data showed that in all the normal tissues and in 70% of the OSF tissues the expression of TGF-β and BMP7 are inversely correlated. In good correlation, treatment of keratinocytes (HaCaT) by TGF-βdown-regulated BMP7, while BMP7 expression could not be detected in fibroblast cells. Hence, the imbalance between TGF-βand BMP7 signalling, which are positive and negative modulators of extracellular matrix production, respectively may trigger the manifestation of OSF. We also studied the regulation few genes (CTGF, TGM2 and THBS1) identified in OSF microarray in response to TGF-βand arecoline. TGF-βwas able to induce all the above genes in both HaCaT and hGF cells but arecoline could only induce TGM2 in hGF and THBS1 in HaCaT. Therefore TGF-βpathway came out to be the most important pathway in OSF microarray and subsequent validations. But areca nut constituents responsible for TGF-βpathway activation and the source (epithelial or fibroblast cells) through which it activates TGF-βare not known. In an attempt to understand the role of areca nut and its constituents in inducing TGF-βsignalling in epithelial cells, we performed microarray on epithelial cells (HaCaT) treated with areca nut water extract. Surprisingly, 64% of the differentially regulated genes by areca nut water extract matched with TGF-βinduced gene expression profile. To find out areca nut induced genes through TGF-β, epithelial cells were treated with areca nut in presence of ALK5 (TβRI) inhibitor. Out of 64% differentially induced genes, 57% genes induced by areca nut got compromised in presence of ALK5 and 7% were independently induced by areca nut, highlighting the effect of areca nut via TGF-β. Accordingly, areca nut treatment induced both p-SMAD2 and TGF-βdownstream targets TGFBI, TGM2, TMEPAI and THBS1 in HaCaT cells. One possible mechanism of TGF-βsignalling induction by areca nut could be via induced ligand (TGF-β2) and its activator (THBS1). Induction of TGF-β2 ligand by areca nut was shown at both RNA (Real Time) and protein (ELISA) levels. To find out areca nut components responsible for inducing TGF-β signalling, areca nut fractionation was performed which gave three fractions namely, Ethyl acetate (polyphenol), water supernatant (alkaloids) and Dichloromethane (impurity). Out of these; polyphenol and alkaloid fractions were found to be responsible for the induction of TGF-β signalling and its downstream targets. Upon treatment with purified components, catechin and tannin of polyphenol fraction and arecoline, arecaidine and guvacine of alkaloid fraction were found to be responsible for inducing TGF-β signalling, as seen by increased appearance of phopho-SMAD2 in HaCaT cells. Areca nut treatment on human gingival fibroblast cells (hGF) did not induce TGF-β signalling, highlighting that the source of TGF-β induction by areca nut could possibly be the epithelium. Further treatment of areca nut along with TGF-β on hGF cells potentiated TGF-β effect both in terms of TGF-β downstream targets like TGFBI, TGM2, TMEPAI, COL1A1 etc and activation of fibroblast by inducing α-SMA. Increasing concentration of areca nut is cytotoxic on HaCaT cells and pro-proliferative on hGF cells. This could provide a possible explanation for epithelial atrophy and proliferating fibroblast cells in connective tissue of OSF patients. Further exploration on HaCaT cell cytotoxicity by areca nut suggests the involvement of Reactive Oxygen Species (ROS) as a key molecule induced by areca nut. Compromising ROS generation by NAC (N-Acetyl-L-Cysteine) led to reversal of Sub-G1 peak induced by areca nut in HaCaT cells. This highlighted that cell death caused by areca nut could be ROS mediated. Areca nut treatment on hGF cells did not induce ROS generation, leading to no cytotoxicity on these cells. A possible explanation of this differential ROS generation can be due to dose dependent suppression of Catalase activity by areca nut in HaCaT cells but not in hGF cells. We also compared cytotoxicity of areca nut with all the alkaloids and found a good match with arecoline as both of them induce ROS, apoptotic ladder formation, annexin V positivity, suppression of Catalase activity and the cell death induced by them was compromised by NAC. The above results indicated that arecoline could be a mediator of areca nut water extract cytotoxicity on HaCaT cells. Betel nut chewer’s oral epithelium gets regularly exposed to areca nut and hence this exposure could be cytotoxic to oral epithelial cells too. We performed Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) in normal and OSF tissues. Our data showed 62.5% of OSF patients having significant percentage of epithelial cells with TUNEL positivity (Labeling index = 2-60%) compared to all normal tissues that were TUNEL negative. TUNEL positivity was predominantly seen in the upper keratin and supra basal layer of the epithelium. We also studied proliferation status of OSF epithelium and observed that 3-17% (LI) of epithelial cells in all normal tissues showed Ki-67 positivity in the germinal layer of epithelium. However, 65% of the OSF patients showed staining for Ki-67 (LI=.2-58%) in their epithelium. Also analysis of TUNEL positive and Ki-67 positive sections indicated that OSF patients with high TUNEL positivity have high Ki-67 labeling index, but stains in the supra basal or keratin layer (TUNEL) and basal layer (Ki-67) of epithelium respectively. This induced proliferation of epithelial cells could be the result of heavy apoptosis in the outer epithelium. But as these patients are regularly exposed to areca nut, this increased proliferation may not be able to cope up with the heavy apoptosis induced by areca nut, leading to atrophied epithelium. To understand the germinal status of OSF atrophied epithelium we performed staining for OCT4 in OSF tissues. To our surprise there were no OCT4 positive nuclei in the epithelium of 53% of OSF patients but a regular spread of OCT4 positivity has been seen in the epithelium of normal subjects. In conclusion, this thesis highlights the involvement of TGF-β pathway in OSF patho-physiology. In addition, activation of TGF-β pathway by areca nut constituents has been demonstrated. Moreover, the atrophied epithelium of OSF appears to be a consequence of apoptosis and stem cell deprivation. Taken together, areca nut perhaps causes atrophy of the epithelium and activates TGF-β pathway that may lead to manifestation of OSF.