L’activateur tissulaire du plasminogène est une sérine protéase initialement découverte dans le compartiment vasculaire et qui joue un rôle prépondérant dans le processus de fibrinolyse. De manière intéressante, le tPA est également présent dans le parenchyme cérébral, où il est notamment exprimé par les neurones. Le tPA est impliqué dans de nombreuses fonctions cérébrales dont la plasticité synaptique, les processus de mémoire et d’apprentissage ainsi que dans la survie et la mort neuronales. Le tPA est capable d’augmenter la signalisation calcique induite par une activation des récepteurs N-Méthyl-D-Aspartate (NMDAR) : un mécanisme à la base de la plasticité synaptique mais également de la mort neuronale excitotoxique. Cependant, il peut également activer les récepteurs du facteur de croissance épidermique (EGFR) pour induire un effet anti-apoptotique sur les neurones. Afin de mieux comprendre les différentes fonctions du tPA sur les neurones, nous nous sommes intéressés à la distribution et au trafic intracellulaire du tPA. Pour cela, nous avons créé un nouvel outil afin d’imager le tPA dans les neurones en temps réel: un plasmide codant pour une protéine fusion, le tPA-HaloTag®.Premièrement, nos résultats montrent que le tPA est présent dans les axones et les dendrites des neurones corticaux matures en culture et qu’il est majoritairement présent dans le compartiment post-synaptique. Cette étude a également permis de voir que le tPA est stocké et libéré par des vésicules d’exocytose VAMP2, qu’il peut être endocyté par des vésicules Rab5, recyclé par des vésicules Rab11 et dégradé par des vésicules Rab7. Deuxièmement, nous avons montré que le tPA est présent dans les mêmes vésicules synaptiques que le facteur neurotrophique issu du cerveau (BDNF) : une neurotrophine importante pour le bon fonctionnement cérébral et dont la maturation dépend de l’activité protéolytique du tPA. Ce travail fournit une meilleure compréhension du rôle et de la distribution du tPA dans les neurones et ouvre de nouvelles voies de recherche dans l’implication de du tPA et du BDNF dans la survie neuronale. / Tissue-type Plasminogen Activator (tPA) is a serine protease, firstly discovered for its fibrinolytic role in the vascular compartment. Interestingly, tPA is also present in the brain parenchyma, being notably expressed by neurons. tPA displays important roles in synaptic plasticity(Danny Baranes et al., 1998; Melchor and Strickland, 2006), learning, memory processes(R Madani et al., 1999; R Pawlak et al., 2002), neuronal survival and death. tPA is able to promote N-Methyl-D-Aspartate Receptors (NMDAR)-induced calcium influx, promoting synaptic plasticity or excitotoxic neuronal death. tPA is also able to activate Epidermal Growth Factor Receptors (EGFR), a mechanism mediating its anti-apoptotic effect. To better understand the different functions of tPA on neurons, we studied the pattern of distribution and trafficking of neuronal tPA. For that, we designed a new tool to image tPA in living neurons: a plasmid encoding for a tPA-HaloTag® fusion protein. We first found that tPA is present in both axons and dendrites of mature cultured cortical neurons and preferentially at the post-synaptic part. Our results also showed that tPA is stored and released by VAMP2 exocytotic vesicles, and can be endocytosed by Rab5 vesicles, recycled by Rab11 vesicles and degraded by Rab7 vesicles. Furthermore, tPA is localized and sorted in the same vesicles than Brain-Derived Neurotrophic Factor (BDNF), one of the most important neurotrophins, Interestingly, BDNF maturation is dependent of tPA proteolytic activity. This work provides a better understanding of the role and distribution of tPA in living neurons and opens new avenues into the involvement of tPA and BDNF in neuronal survival.

L'ischémie cérébrale est une pathologie complexe impliquant une cascade de mécanismes cellulaires qui conduisent, entre autres, à une augmentation de l’autophagie dans les neurones. Bien que l’activation de l’autophagie dans l’AVC ischémique soit aujourd’hui un fait avéré, le rôle de l'activateur tissulaire du plasminogène (tPA ; médicament utilisé dans la phase aigüe de l’AVC ischémique et neuromodulateur du système nerveux central) n’a jamais été décrit. Le tPA est une sérine protéase initialement découverte dans le compartiment vasculaire jouant un rôle important dans la fibrinolyse. Mais le tPA est aussi exprimé dans le parenchyme cérébral où il intervient dans le système glutamatergique, la plasticité synaptique et la survie neuronale. Afin de mieux comprendre les effets moléculaires du tPA dans l’autophagie, nous avons utilisé un modèle in vitro d'ischémie cérébrale consistant à sevrer en oxygène et en glucose (OGD) puis à réoxygéner des neurones corticaux primaires murins avec ou sans tPA. Nous avons confirmé, dans un premier temps, que l’OGD induit une autophagie délétère via une diminution de l’axe PI3K/Akt/mTORC1. Nous avons ensuite étudié l’effet du tPA sur l’autophagie induite par l’OGD. Nos résultats démontrent que le tPA protège les neurones de la mort induite par l’OGD en réduisant l’autophagie via l’activation du récepteur du facteur de croissance à l'insuline (IGF-1R, un récepteur tyrosine kinase) et de la voie PI3K/Akt/mTOR. Ce travail de thèse a donc permis de décrire le rôle neuroprotecteur et anti-autophagique du tPA, et d’identifier un nouveau récepteur cible du tPA : IGF-1R. / Cerebral ischemia is a complex pathology involving a cascade of cellular mechanisms leading, among other things, to an increase of neuronal autophagy. The activation of autophagy in ischemic stroke conditions is now well accepted, but the role of tissue-type plasminogen activator (tPA, a drug used in the acute phase of ischemic stroke, and a neuromodulator) on this pathway has never been studied. tPA is a serine protease originally discovered in the vascular compartment, that plays an important role in fibrinolysis. Interestingly, tPA is also expressed in the cerebral parenchyma where it is involved in the glutamatergic neurotransmission, synaptic plasticity and neuronal survival. To better understand molecular effects of tPA on autophagy, we used an in vitro model of cerebral ischemia consisting in an oxygen and glucose deprivation (OGD) followed by reoxygenation, on murine primary cortical neurons with or without tPA. First we reported that OGD enhances deleterious autophagy through the decrease of PI3K/Akt/mTOR pathways. Then, we investigated the effect of tPA on OGD-induced autophagy. Our results demonstrate that tPA protects neurons from OGD-induced death by reducing autophagy through Insulin Growth Factor Receptor (IGF-1R, a tyrosine kinase receptor) and an increase of PI3K/Akt/mTOR pathways. This thesis has made it possible to describe the neuroprotective and anti-autophagic effect of tPA, and to identify a new target receptor for tPA: IGF-1R.

Background: Clinical factors associated with exclusion from recombinant tissue plasminogen activator in both men and women are not completely understood. The aim of this study is to determine whether there is a gender difference in clinical risk factors that excluded ischemic stroke patients with a history of smoking from recombinant tissue plasminogen activator. Methods: Retrospective data from a stroke registry were analyzed, and multivariable linear regression models were used to determine gender differences. Logistic regression models determined exclusion clinical risk factors for thrombolysis in male and female acute ischemic stroke patients with a history of smoking, while sequentially adjusting for sociodemographic, clinical, and stroke-related variables. The Kaplan–Meier survival analysis was used to determine the exclusion probabilities of men and women with a history of smoking within the stroke population. Results: Of the 1,446 acute ischemic stroke patients eligible for recombinant tissue plasminogen activator, 379 patients with a history of smoking were examined, of which 181 received recombinant tissue plasminogen activator while 198 were excluded from receiving recombinant tissue plasminogen activator. Of the 198 patients, 75 females and 123 males were excluded from receiving recombinant tissue plasminogen activator. After multivariable adjustment for age, National Institutes of Health scores, and stroke-related factors, females who present with weakness/paresis on initial examination (OR = 0.117, 95% CI, 0.025–0.548) and men who present with a history of previous transient ischemic attack (OR = 0.169, 95% CI, 0.044–0.655), antiplatelet medication use (OR = 0.456, 95% CI, 0.230–0.906), and weakness/paresis on initial examination (OR = 0.171, 95% CI, 0.056–0.521) were less likely to be excluded from recombinant tissue plasminogen activator (thrombolysis therapy). Conclusions: In an ischemic stroke population with a history of smoking, female smokers are more likely to be excluded from thrombolysis therapy in comparison to men, even after adjustment for confounding variables.

PURPOSE: Hemothorax, the collection of blood in the intrapleural space, commonly arises in patients suffering from thoracic trauma. Fluid collections in this space can compromise cardiac and respiratory function and if left untreated, can result in hypovolemic crisis. Fluid is often successfully drained via a tube thoracostomy, in which an intercostal drain is inserted into the pleural space. If residual blood remains, however, clotting may occur and result in a retained hemothorax (RH). Intrapleural administration of tissue plasminogen activator (tPA), a fibrinolytic drug typically utilized in ischemic stroke, has been shown to be both a safe and effective technique to hydrolyze RH clots and reduce the need for more invasive surgical interventions. The present study aims to evaluate the safety and efficacy of tPA administration at Boston Medical Center (BMC) and compare this data to those of prior studies. This study will also investigate if tPA as a definitive treatment for RH, could reduce the need for additional interventions such as surgical procedures including Video-Assisted Thoracoscopic Surgery (VATS) and/or invasive thoracaotomy. Hospital/intensive care unit (ICU) lengths of stay (LOS), ventilator time, and complication rates will be used to determine if tPA may allow for a significant decrease in patient cost and burden of care versus surgery. An analysis of patient demographics and injury data will be used to determine the individual factors that could be used to predict the success of tPA as a definitive treatment. Using evidence-based treatment protocols, the aforementioned data will be critically evaluated to determine the appropriate timing and sequential positioning of tPA administration in the treatment algorithm for retained hemothorax. METHODS: A single-institution retrospective chart review was conducted of patients treated for traumatic pneumohemothorax by the Department of Acute Care and Trauma Surgery at Boston Medical Center. A study on predictive factors of the development of retained hemothorax included all such patients that presented to the emergency department (ED) between May 2014 and June 2016. Demographic and injury characteristics were analyzed to determine if patients from specific groups or with specific injuries are more prone to develop RH. To evaluate the safety of intrapleural tissue plasminogen activator, the incidence of complications such as post-trauma infection and mortality were determined in patients that were administered tPA to resolve retained hemothorax between May 2014 through December 2016. Next, utilizing an expanded data set, the efficacy of tPA was evaluated by determining the percentage of cases in which tPA was able to definitively resolve RH. Secondary efficacy data including average hospital length of stay, average ICU length of stay, average mechanical ventilation time, and rate of readmission were compared between various interventions as well. Finally, to elucidate the risk factors for RH and independent predictors of tPA as a definitive treatment, demographic data including age, ethnicity, and gender as well as injury data including mechanism of injury, the presence or absence of multisystem trauma, and the presence or absence of specific injuries such as rib fracture, pulmonary contusion, or diaphragmic insult were collected. RESULTS: A statistically significant positive correlation was observed between the likelihood of developing RH and both abdominal alimentary tract and extremity injuries, indicating that these injuries may serve as predictive factors for RH development. In a study investigating the safety of intrapleural tPA, there was no statistically significant difference in post-trauma infection rates between individuals treated with tPA and those who were not. Additionally, tPA treatment was associated with a lower mortality rate. Efficacy studies revealed that tPA therapy was associated with a statistically significant decrease in mechanical ventilation time, as compared to surgical intervention, however, tPA carried a RH resolution rate of just 43% with one patient experiencing a major adverse systemic reaction to the drug. Finally, demographic and injury data were analyzed to determine predictive factors of tPA success, but no statistically significant relationships were observed between any of these characteristics and the outcome of tPA therapy. CONCLUSION: Intrapleural tPA is a safe and effective alternative to more invasive surgical procedures. The success rate of tPA therapy in the present study was less than previous studies have indicated, however, the potential decreased ventilation time is important for preventing ventilator associated pneumonia (VAP) and the high rate of mortality it carries. Although the success rate is lower than expected, tPA should still be considered in the RH treatment protocol, prior to surgery, to decrease required ventilation time and potentially prevent the need for more invasive interventions with higher costs, morbidity, mortality rates, and patient burden.

Angioedema is a localized, non-pitting, non-dependent, submucosal, and subcutaneous swelling resulting from the extravasation of fluid into the interstitium due to the increased production of plasma kinins and histamine. It can present with urticaria or anaphylaxis and is usually associated with angiotensin-converting enzyme inhibitors (ACEis), complement deficiencies, or the side effects of tissue plasminogen activator (tPA). Orolingual angioedema following tPA for acute ischemic stroke is a transient, self-resolving hemifacial swelling contralateral to neurological deficits that can rarely progress to the airway, compromising it and leading to a life-threatening situation if not managed promptly.

京都大学 / 新制・課程博士 / 博士(人間健康科学) / 甲第24292号 / 人健博第107号 / 新制||人健||8(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 藤井 康友, 教授 岡 昌吾, 教授 滝田 順子 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM

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