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Wounding of the cornea generates lateral electric fields (EFs) and initiates the expression of hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF; Chiang et al., 1992; Wilson et al., 1999a). Therefore, these biologically generated EFs and endogenous growth factors may be of particular significance during wound healing. In the presence of an EF (150 mV/mm) cultured corneal epithelial cells (CECs) oriented perpendicular, directed cathodally and migrated at an enhanced rate. The induction times, induction thresholds and response patterns for these behaviours in increasing field strengths, indicated that they may operate through separate and parallel pathways. The application of either HGF or KGF enhanced the rate of CEC migration but neither affected the extent of CEC orientation or directionality. The distribution of HGF receptors (HGFR) was found to be exclusive to the cell body in the presence of an EF, the receptors accumulated cathodally. Moreover, the asymmetrical accumulation of HGFR in the presence of an EF correlated with the direction of CEC migration. The application of both HGF and an EF activated extracellular-signal regulated kinase (ERK) a mitogen-activated protein kinase. Furthermore, in the presence of an EF the observed ERK activation was greater in the cathodal facing half of the CECs. Inhibition of ERK reduced the extent of HGF and EF-enhanced CEC migration rate but did not alter EF-induced CEC cathodal directionality or perpendicular orientation. The HGF- and EF-enhancement of CEC migration rate may involve the activation of ERK and with the downstream liberation of leukotrienes and phosphorylation of MLCK, would culminate in actin contraction and polymerisation respectively. The potential clinical relevance for this work would concern the topical application of HGF and exogenous application of EFs to corneal epithelial wounds in order to augment healing in patients where this process is slow or deficient.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20250号 / 医博第4209号 / 新制||医||1020(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 伊達 洋至, 教授 戸口田 淳也, 教授 開 祐司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Submitted by Maria Anália Conceição (marianaliaconceicao@gmail.com) on 2016-06-27T19:07:25Z No. of bitstreams: 1 Publico-NOVO-20.pdf: 888503 bytes, checksum: 0e3c78bc6040c66cc6712fddc9beb7a9 (MD5) / Approved for entry into archive by Maria Anália Conceição (marianaliaconceicao@gmail.com) on 2016-06-27T19:08:15Z (GMT) No. of bitstreams: 1 Publico-NOVO-20.pdf: 888503 bytes, checksum: 0e3c78bc6040c66cc6712fddc9beb7a9 (MD5) / Made available in DSpace on 2016-06-27T19:08:15Z (GMT). No. of bitstreams: 1 Publico-NOVO-20.pdf: 888503 bytes, checksum: 0e3c78bc6040c66cc6712fddc9beb7a9 (MD5) Previous issue date: 2015 / Introdução: Queimadura extensa e profunda é um trauma complexo que necessita de cuidados intensivos no tratamento agudo. Intervenções terapêuticas para atenuar a resposta inflamatória aguda e acelerar a cicatrização podem contribuir na redução da morbimortalidade e nos custos do tratamento. Estudos demonstram a importância do fator de crescimento de queratinócito (KGF) na cicatrização de feridas. Objetivo: Avaliar a ação do KGF na expressão de 84 genes marcadores da cicatrização em cultura primária de queratinócitos humanos oriundos de pacientes com queimadura. Métodos: Após a obtenção de fragmentos de pele de quatro pacientes com queimadura (grupo queimadura) e de quatro pacientes hígidos (grupo controle), foi realizada a cultura de queratinócitos humanos primários e distribuídas em quatro grupos: GQ+ (n = 4 – queratinócitos de queimadura tratadas com KGF), GQ- (n = 4 – queratinócitos de queimadura sem tratamento), GC+ (n = 4 – queratinócitos do grupo controle tratadas com KGF) e GC- (n = 4 – queratinócitos do grupo controle sem tratamento). A análise da expressão gênica foi feita por qPCR Array, realizando seis comparações: 1) GC+ versus GC-; 2) GQ- versus GC-; 3) GQ+ versus GC-; 4) GQ+ versus GQ-, 5) GQ+ versus GC+ e 6) GQ- versus GC+. Resultados: A comparação 1 apresentou um gene hiporregulado e um hiperregulado. As comparações 2 e 3 apresentaram os mesmos cinco genes hiporregulados. A comparação 4 não apresentou genes diferencialmente expressos. A comparação 5 apresentou 26 genes hiporregulados e 7 hiperregulados. E a comparação 6 apresentou 25 genes hiporregulados e 11 genes hiperregulados. Conclusão: A suplementação de KGF à cultura de queratinócitos de pacientes com queimadura não determinou a expressão gênica diferencial dos genes marcadores da cicatrização. / Introduction: Severe burn injury is a complex trauma that needs intensive care in the acute setting. Therapeutic interventions that aim to attenuate the acute inflammatory response and to accelerate the healing may contribute to reducing morbidity, mortality and treatment costs. Several studies have demonstrated the importance of keratinocyte growth factor (KGF) in wound healing. Objective: Evaluate the effect of KGF in the expression of 84 wound healing genes in human primary keratinocytes cultured from patients with burn. Methods: After obtaining viable fragments of skin from four healthy (control group) and four burn patients, human primary keratinocytes was cultured and divided into 4 groups: GQ+ (n = 4 – keratinocytes of severe burn patients treated with KGF), GQ- (n = 4 – untreated keratinocytes of severe burn patients), GC+ (n = 4 – keratinocytes of control group treated with KGF) and GC- (n = 4 – untreated keratinocytes of control group). The gene expression's analysis was performed with qPCR Array, making six comparisons: 1) GC+ versus GC -; 2) GQversus GC-; 3) GQ+ versus GC-; 4) GQ+ versus GQ-, 5) GQ+ versus GC+ and 6) GQversus GC+. Results: Comparison 1 showed one down and one up-regulated genes. Comparisons 2 and 3 showed the same five down-regulated genes. Comparison 4 did not show statistically significant gene expression. Comparison 5 showed 26 downregulated and 7 up-regulated genes. And comparison 6 showed 25 down-regulated and 11 up-regulated genes. Conclusion: Supplementation of KGF to the culture of keratinocytes from patients with burn injury not determined the differential gene expression of genes markers of wound healing

Lipid synthesis is required for cell growth and is subject to pharmacologic regulation. Keratinocyte growth factor (KGF) stimulates proliferation and lipogenesis in H292 cells, a pulmonary epithelial cancer cell line, but the signaling pathways are not known. KGF stimulated the expression of the transcription factors sterol-regulatory element binding protein-1 (SREBP-1), CCAAT/enhancer binding protein α (C/EBPα), and C/EBPδ and two key enzymes involved in lipogenesis, FAS and stearoyl coenzyme A desaturase-1 (SCD-1). We found that KGF induced rapid activation of Akt, p70 S6K, JNK, and extracellular signal-regulated (ERK). Induction of SREBP-1, SCD-1, and FAS by KGF was inhibited by the JNK inhibitor SP600125 and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 but not by the ERK inhibitor PD98059. Using FAS and SCD-1-luciferase promoter constructs, we observed that KGF stimulated the transcription of these promoters and that exogenous cholesterol inhibited the induction. Mutation of the SREBP-1 binding site in the SCD-1 promoter abolished the effect of KGF on SCD-1 transcription. In addition, overexpression of active SREBP-1 directly stimulated SCD-1 and FAS. Conversely, adenovirus-mediated overexpression of a dominant negative form of SREBP-1 inhibited the KGF effect on FAS and SCD-1 expression. In summary, we conclude that KGF requires both PI3K and JNK signaling pathways to induce SREBP-1, which in turn induces SCD-1 and FAS expression in H292 cells.

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La fibrose pulmonaire idiopathique (FPI) et le syndrome de détresse respiratoire aiguë (SDRA) de l’adulte constituent des affections sévères du poumon distal, avec un pronostic sombre pour les patients. A ce jour, aucun traitement n’est réellement efficace. De manière intéressante, une hypoxie alvéolaire est retrouvée dans ces pathologies.La thérapie cellulaire utilisant des cellules souches mésenchymateuses humaines (CSMh) pourrait représenter un intérêt thérapeutique chez l’Homme. Cependant, leurs mécanismes d’action sont multiples et encore mal définis. Aussi, nous avons testé in vitro l’hypothèse selon laquelle les CSMh pourraient exercer un effet cytoprotecteur paracrine sur les cellules épithéliales alvéolaires (CEA) soumises à l’hypoxie.Dans une première étude, nous avons montré qu’une exposition prolongée à l’hypoxie telle que celle rencontrée au cours de la FPI induisait des modifications phénotypiques des CEA primaires de rat, évocatrices d’une transition épithélio-mésenchymateuse (TEM). On observe une perte progressive d’expression des marqueurs épithéliaux (TTF1, AQP5, ZO-1 et E-Cadhérine), couplée à l’apparition tardive de marqueurs mésenchymateux (α-SMA et Vimentine). Ces modifications phénotypiques s’accompagnent de l’expression dès les premières heures d’hypoxie de facteurs de transcription impliqués dans la TEM (SNAI1, TWIST1 et ZEB1) ou induits par l’hypoxie (HIF-1α et HIF-2α), et de protéines induisant la TEM (TGF-β1 et CTGF). La co-culture des CEA avec des CSMh en fond de puits prévient les modifications phénotypiques induites par l’hypoxie ainsi que l’expression des facteurs pro-TEM TWIST1, ZEB1, TGF-β1 et CTGF. Cet effet bénéfique des CSM est en partie expliqué par la sécrétion d’un facteur de croissance épithélial, le KGF.Dans une deuxième étude, nous avons confirmé que les CEA entraient en apoptose en condition hypoxique, via l’induction de deux voies de signalisations hypoxiques pro-apoptotiques. D’une part, les facteurs de transcription induits par l’hypoxie HIF sont stabilisés, et une cible pro-apoptotique, Bnip3, est induite. D’autre part, l’hypoxie induit une accumulation d’espèces réactives à l’oxygène délétère pour la cellule, perturbant l’équilibre redox de la cellule, endommageant l’ADN, et conduisant à l’apoptose. Cette accumulation pourrait résulter notamment d’une diminution de l’activité des enzymes anti-oxydantes SOD, en hypoxie. Le manque d’oxygène entraine également l’expression de CHOP, facteur de transcription pro-apoptotique impliqué dans le stress du réticulum endoplasmique, qui va13inhiber l’expression de la protéine anti-apoptotique Bcl-2. Nous avons montré que la culture des CEA en présence de milieu conditionné de CSMh (mc-CSMh) permet de prévenir partiellement l’apoptose des CEA en hypoxie, en modulant la voie de signalisation HIF, et en prévenant l’accumulation et les effets délétères des ROS. L’effet protecteur des CSM impliquerait le KGF comme observé lors de la première étude, mais également le HGF.Ces deux études indiquent que les CSMh sont susceptibles d’exercer des effets cytoprotecteurs paracrines vis-à-vis des CEA soumises à l’hypoxie aiguë ou prolongée, en limitant d’une part les modifications phénotypiques évocatrices de TEM, et d’autre part l’apoptose des CEA via la modulation des voies de signalisations hypoxiques. La sécrétion par les CSMh de KGF et de HGF, facteurs de croissance épithéliaux connus pour leurs effets bénéfiques sur les CEA, explique en partie les effets protecteurs paracrines des CSMh. Nos résultats suggèrent que les effets cytoprotecteurs des CSMh vis-à-vis des CEA pourraient contribuer aux effets bénéfiques des CSMh observés in vivo dans différents modèles animaux de fibrose induite, ou lors d’agressions alvéolaires aiguës. / Acute or chronic alveolar injuries provoke massive apoptosis of alveolar epithelial cells (AEC) that compromises an efficient repair of the alveolar epithelium and leads to lung diseases such as ARDS or IPF. These disorders are commonly associated with local alveolar hypoxia aggravating their progression through the stimulation of AEC apoptosis. Administration of allogenic mesenchymal stem cells (MSCs) has been shown to limit lung inflammation and fibrosis in murine models of alveolar injury, through a still poorly understood paracrine mechanism. In a first study, we showed that long term exposure of AEC in hypoxia leads to phenotypic alterations which looks like epithelio-mesenchymal transition (EMT). Co-culture with MSCs prevent hypoxia-induced EMT.In a second work, we studied whether MSC could protect AEC from hypoxia-induced apoptosis and the mechanisms involved. hMSC-conditioned media (hMSC-CM) significantly reduced hypoxia-induced apoptosis of AEC. Such a anti-apoptotic effect was also obtained with ROS scavenger N-acetylcystein or HIF1a inhibitor YC-1. hMSC-CM decreased the protein expression of HIF1α and HIF2α and of their pro-apoptotic target Bnip3 in hypoxic AEC. hMSC-CM also reduced ROS accumulation in hypoxic AEC by enhancing the activity of anti-oxidant enzymes and prevented the induction of CHOP, a pro-apoptotic factor induced by ROS signaling. The paracrine effect of hMSC was partly dependent on KGF and HGF secretion. hMSC prevent via a paracrine effect hypoxia-induced apoptosis of AEC by modulating hypoxic and ROS signaling.These two studies show that MSCs exert cytoprotective effects in vitro against hypoxia-induced apoptosis and EMT in AEC

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