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La spondylarthrite ankylosante (SA), la forme la plus commune des spondylarthrites (SpA), est fortement associée à la molécule du CMH de classe I HLA-B27 mais le rôle de cet antigène d'histocompatibilité dans le développement de ces pathologies reste encore inexpliqué. L’étude des rats transgéniques HLA-B27, développant une pathologie inflammatoire spontanée ressemblant aux SpA, a permis de confirmer l’implication directe du HLA-B27 et de corréler l’apparition des symptômes avec une forte expression de cette molécule. De plus, il a été montré que l’HLA-B27 présentait une propension particulière au mauvais repliement et à la formation d’oligomères de chaînes lourdes. L’objectif de mon travail de thèse était de déterminer si le trafic et/ou la formation d’oligomères du HLA-B27 étaient corrélés à sa surexpression. Pour cela, notre équipe a développé des protéines de fusion (HLA-BYFP et HLA-BRLuc) ainsi que la technique BRET afin d’étudier les interactions HLA-B/HLA-B. Au moyen de ce système expérimental, nous avons montré la formation de vésicules intracellulaires riches en protéines HLA-B mal repliées lorsqu’elles étaient fortement exprimées, qu'il s'agisse d'allèles associés à la SA (HLA-B*2702, -05, et -07) ou non (HLA-B*2706, et -09, HLA-B*0702). Cependant, ce phénomène était significativement plus prononcé pour les sous-types associés à la SA. Dans les conditions de forte expression, nous avons également observé que les sous-types associés à la SA formaient des oligomères qui se comportent différemment de ceux formés par la protéine HLA-B7. Ce phénomène ne semble pas être dû au déclenchement de la réponse cellulaire « Unfolded Protein Response » (UPR) et n’est pas abrogé par l’inhibition du protéasome. / Ankylosing spondylitis (AS), the most common form of spondyloarthritis (SpA), is strongly associated with the MHC class I HLA-B27 molecule. Although this association has been largely studied, mechanisms of pathology remain unclear. Development of a spontaneous inflammatory disease resembling human SpA in HLA-B27 transgenic rats confirmed the direct involvement of HLA-B27 and allowed to associate disease development with high expression levels of this molecule. Moreover, the HLA-B27 protein has an enhanced propensity to misfold and form aberrant disulfide linked heavy chain oligomers in the endoplasmic reticulum and at the cell surface. The goal of my thesis work was to determine if the HLA-B27 traffic and/or its ability to form oligomers are involved in this requirement of overexpression. For that, our team has developed fusion proteins ((HLA-BYFP and HLA-BRLuc) and the BRET technique to study, in vitro, the HLA-B/HLA-B interactions. Using this experimental system, we have shown the formation of intracellular vesicles, in which misfolded/unfolded HLA-B proteins accumulated when they were highly expressed, for both AS-associated alleles (HLA-B*2702, -05, et -07) or not (HLA-B*2706, et -09, HLA-B*0702). This phenomenon is strongly pronounced for AS-associated subtypes. For high-level expression, we also observed that the AS-associated subtypes form oligomers that behave differently from those formed by the HLA-B7 control protein. This phenomenon doesn’t appear to be due to unfolded protein response (UPR) triggering and is not abrogated by proteasome inhibition.

Les vésicules hybrides polymère/lipides sont des structures récemment développées dans la littérature. Idéalement, celles-ci peuvent présenter la biocompatibilité et la biofonctionnalité des liposomes, ainsi que la robustesse, la faible perméabilité et la versatilité de fonctionnalisation chimique conférées par les chaînes de copolymères. Cependant, à ce jour, les facteurs régissant la séparation des phases dans ces membranes hybrides ne sont pas bien compris. Dans ce travail, nous avons étudié en détail la formation et la séparation de phases dans les membranes de vésicules géantes (GHUVs) et de taille nanométriques(100nm) (LHUVs) constituées de phospholipides en phase fluide ou gel et de copolymères à base de poly (diméthylsiloxane) et de poly (éthylène glycol). Différentes architectures(greffée, tribloc) et masses molaires ont été utilisées. La séparation de phase a été étudiée sur les vésicules géantes à l’échelle micrométrique et nanométrique respectivement par microscopie confocale et imagerie de fluorescence résolue en temps (FLIM), tandis que pour les LHUVs, différentes techniques comme la diffusion de neutrons, la Cryo-microscopie et la spectroscopie de fluorescence résolue dans le temps ont été combinées. Nous avons pu montrer que la fraction lipide/polymère, l'état physique du lipide et la tension de la ligne aux interfaces lipide/polymère modulable par la masse molaire et l'architecture du copolymère sont les facteurs importants régissant la formation et la structuration des vésicules hybrides. Enfin, nous avons montré que les propriétés élastiques de la membrane peuvent être modulées via la composition polymère lipide. / Hybrid copolymer/lipid vesicle are recently developed self-assembled structures that could present biocompatibility and biofunctionality of liposomes, as well as robustness, low permeability and functionality variability conferred by the copolymer chains. However, to date, physical and molecular parameters governing copolymer/lipid phase separation in these hybrid membranes are not well understood. In this work, we studied in detail the formation and phase separation in the membranes of both Giant Unilamellar Hybrid Vesicles(GHUVs) and Large Unilamellar Hybrid Vesicles (LHUVs) obtained from the mixture of phospholipids in the fluid (liquid disordered) or gel state (solid ordered) with various copolymers based on poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) (PEO) with different architectures (grafted, triblock) and molar masses. For GHUVs, phase separation at the micron scale and nanoscale was evaluated through confocal microscopy, and Fluorescence lifetime imaging microscopy technique (FLIM) respectively, where as acombination of Small angle neutron scattering (SANS), Cryo-transmission electron microscopy (Cryo-TEM) and Time-resolved Förster resonance energy transfer (TR-FRET) techniques was used for LHUVs. We demonstrate that the lipid/polymer fraction, lipid physical state, and the line tension at lipid polymer/lipid boundaries which can be finely modulated by the molar mass and architecture of the copolymer are important factors that govern the formation and structuration of hybrid vesicles. We also evidence that elasticity ofthe hybrid membrane can be modulated via the lipid polymer composition, through the use of micropipettes techniques.

La mucoviscidose est une maladie génétique due à des mutations du gène CFTR (Cystic Fibrosis Transmembrane conductance Regulator), conduisant à un défaut d'adressage de la protéine CFTR à la membrane apicale des cellules épithéliales, ou à un déficit de sa fonction de canal à ions chlorure. Ce travail a consisté à étudier les vésicules extracellulaires (EV), microvésicules (MV) et exosomes (Exo), comme vecteurs de la protéine CFTR et de son ARN messager. La preuve de concept du transfert de matériel biologique d'intérêt par l'intermédiaire d'EV, d'abord apportée sur un modèle de cellules animales (CHO), a été validée en cellules humaines. Les EV ont été isolées à partir de surnageant de Calu-3, cellules exprimant la protéine CFTR de manière endogène, et de A549 transduites par le vecteur adenoviral Ad5-GFP-CFTR, surexprimant la protéine de fusion GFP-CFTR. Les cellules cibles choisies, A549 et CF15, étaient déficientes en CFTR. Le transfert s'est révélé plus efficace en système homologue (A549/A549) qu'en système hétérologue (A549/CF15). Par ailleurs, l'utilisation d'inhibiteurs métaboliques suggère que les EV ne suivent pas une voie d'internalisation cellulaire unique, mais que plusieurs mécanismes sont mis en jeu, dont l'endocytose clathrine dépendante et la macropinocytose. Les deux types d'EV sont capables de rétablir la fonction canal associée au CFTR dans les cellules CF15 de façon dose-dépendante, mais avec un effet de seuil minimum. L'activité CFTR reste stable pendant 3 jours, et à un niveau encore détectable après 5 jours. Notre travail démontre l'intérêt potentiel des MV et Exo comme vecteurs de biothérapie de pathologies génétiques / Cystic fibrosis is a genetic disease in which its prognosis depends on the lung damage. It is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR), resulting in a dysfunctional CFTR protein normally located at the plasma membrane of epithelial cells. This thesis is a study of a novel therapeutic approach to use extracellular vesicles (EVs), microvesicles and exosomes, as transfer vectors for CFTR mRNA and protein to target cells. The proof of concept for the transfer of CFTR mRNA and protein was first done in the CHO hamster model. To validate this concept on human cells, we used human bronchial Calu-3 cells, which express the endogenous CFTR protein, and A549 lung epithelial cells transduced by the adenoviral vector Ad5-GFP-CFTR to overexpress the fusion exogenous protein GFP-CFTR. We show that EVs produced by these cells could transfer a new functionality to CF15 target cells carrying the CFTRdeltaF508 mutation and the transfer seems to be more efficient in a homologous cell system versus a heterologous system. Interestingly, the exosomes seem to be more efficient in CFTR transfer than the microvesicles. A study of the mechanism of EVs cellular uptake show that it is temperature dependent and that endocytosis and macropinocytosis are implicated. Collectively, this study demonstrates the potential application of EVs for CFTR transfer and functional correction of the genetic defect in human CF cells

Le psoriasis est une maladie de peau auto-immune et chronique. Le rhumatisme psoriasique est une de ses principales complications qui est très invalidante pour les patients. Cette pathologie reste encore incurable à ce jour. L'usage des médicaments disponibles actuellement dans le psoriasis est limité par leurs effets secondaires dépendant de la dose et de la durée d'utilisation. Le but de ce travail était de développer des nanovecteurs médicamenteux à base de lipides pour un usage topique, en particulier ciblant l'épiderme viable qui est le site principal de la physiopathologie du psoriasis, mais aussi le derme et au-delà pour atteindre les articulations endommagées. Grâce à une nouvelle technique que nous avons développé et optimisé, le double déplacement de solvants, basée sur une organisation des phospholipides en deux temps, nous avons préparé des vésicules lipidiques encapsulant du diclofénac d'une part et de la ciclosporine A 'autre part. Ensuite, nous avons évalué leur aptitude à traverser la peau et cibler les régions d'intérêt. Après une étude systématique permettant d'optimiser les paramètres de préparation, les vésicules lipidiques encapsulant le diclofénac et la cyclosporine A ont montré une efficacité d'encapsulation (EE%) comprise entre 50% et 90% respectivement, selon la concentration en phospholipides. Après réalisation des études in vitro sur peau de cochon, nous avons observé que la formulation contenant une concentration basse en phospholipides (8,5 mg / mL) permettait d'encapsuler plus de 80% du diclofénac et de cibler le derme et au-delà. La formulation de vésicules lipidiques chargées de cyclosporine A qui encapsule la quantité la plus élevée (environ 80%) était également celle contenant la concentration basse de phospholipides. Contrairement au diclofénac, cette formulation n'était pas la meilleure pour cibler une couche profonde de la peau comme l'épiderme viable, alors que c'était le cas pour la formulation avec une concentration élevée de phospholipides (15 mg / mL), bien que l'EE% était d'environ 55%. Le double déplacement de solvant est une technique très prometteuse de préparation de vésicules lipidiques, capable de produire une population monodisperse d'échelle nanométrique. Cette méthode n'est que légèrement impactée lors d'une transposition d'échelle et serait donc facile à mettre en oeuvre à l'échelle industrielle. Cette méthode a été conçue dès le début pour utiliser des solvants favorisant la pénétration cutanée mais l'étendue de ces applications reste à explorer / Psoriasis is an auto-immune and chronic skin disease. Psoriatic arthritis is the main complication which is very disabling for patients. This pathology still remains incurable to date. The currently psoriasis indicated medicines use is limited by their side effects which are dose and use duration dependent. The aim of this work was to develop lipid based nanocarriers for skin targeting, especially the viable epidermis which is the main site of psoriasis physiopathology but also the dermis and beyond in order to reach the damaged articulations. Thanks to a new technique we developed and optimized called the double solvent displacement, based on a two-step phospholipid organization, we prepared diclofenac and cyclosporine A loaded lipid vesicles. Then, we evaluated their potential to cross the skin and target the skin layers of interest. After a systematic study to optimize preparation parameters, diclofenac and cyclosporine A loaded lipid vesicles displayed an encapsulation efficiency (EE %) between 50% and 90% respectively, according to the phospholipid concentration. After in vitro skin studies, we observed that the formulation containing the lower phospholipid concentration (8.5 mg/mL) allowed to encapsulate more than 80% of diclofenac and also to target the dermis and beyond. The formulation of cyclosporine A loaded lipid vesicles which encapsulates the higher amount (around 80%) is also the one containing the lower phospholipid concentration. Unlike to diclofenac, this formulation was not the better to target the viable epidermis whereas the formulation with the higher phospholipid concentration (15 mg/mL) was even though the EE% was of around 55%. The double solvent displacement is a very promising technique of lipid vesicle preparation, capable to produce monodisperse population of nanoscale carriers. This method is hardly impacted during scale-up and would be easy to implement at an industrial scale. This method was designed from the beginning to use skin penetration enhancer solvents but the scope of its applications still remains to be explored

Mitochondria are dynamic; they alter their shape through fission, fusion and budding of vesicles. Mitochondrial vesicles serve as a quality control mechanism enabling these organelles to rid themselves of damaged lipids and proteins. Dysregulation in mitochondrial dynamics and quality control have been linked to Parkinson’s Disease, making the identification of molecules requisite for these processes a priority. We identified the endocytic protein, Sorting nexin 9 (Snx9) through a genome wide siRNA screen for genes which substantially alter mitochondrial morphology and therefore are important for its maintenance. In this work, the role of Snx9 in mitochondrial morphology is examined. Ultrastructural imaging of mitochondria within cells silenced for Snx9 revealed unbudded vesicles along a hyperfused mitochondrial reticulum suggesting a role for Snx9 in the release of these vesicles. The vesicular profiles contained concentric membranous whorls enriched for neutral lipids. Localization studies suggest the Parkinson’s disease genes, Parkin and Vps35 localize to the unbudded profiles.

Les microvésicules (MVs) sont des petites vésicules membranaires libérées par les cellules, ayant des effets bénéfiques et/ou délétères dans le sepsis. Nous avons déjà démontré que la délétion de l’isoforme non musculaire de la kinase de la chaîne légère de la myosine (MLCKnm) protège les souris contre le choc endotoxique en réduisant l'inflammation. Ici, nous avons évalué les conséquences de la délétion de MLCKnm sur le phénotype et les effets inflammatoires des MVs au cours du choc endotoxique. La délétion de MLCKnm augmente le taux circulant des MVs et ceux dérivées des cellules progénitrices. Les souris MLCKnm-/- présentent une augmentation du nombre des plaquettes, mais leurs capacité à libérer les MVs est réduite et une diminution du nombre des leucocytes et des MVs leucocytaires. Une diminution du relâchement de l’aorte a été observé chez les souris injectées avec des MVs dérivées des souris MLCKnm+/+ (MVsMLCKnm+/+), mais pas les MVs dérivées des souris MLCKnm-/- (MVsMLCKnm-/-). En présence de lipopolysaccharide (LPS), MVsMLCKnm+/+ augmentent la sécrétion des cytokines pro-inflammatoires par les cellules endothéliales de l’aorte de souris alors que les MVsMLCKnm-/- induisent la libération des cytokines anti-inflammatoires. L’injection des MVsMLCKnm-/-, prévient partiellement l'augmentation du stress oxydatif, nitrosatif, et la dysfonction endothéliale induites au niveau des souris par le LPS. Ces résultats montrent que MLCKnm joue un rôle important dans l'activation cellulaire, la libération des MVs, ainsi que le nombre des cellules circulantes. La délétion de MLCKnm permet de générer des MVs circulantes moins inflammatoires avec un potentiel protecteur. / Microvesicles (MVs), small membrane vesicles released from cells, have beneficial and/or deleterious effects in sepsis. We previously reported that non-muscle myosin light chain kinase (nmMLCK) deletion protects mice against endotoxic shock by reducing inflammation. Here, we evaluated the consequences of nmMLCK deletion on the phenotype and inflammatory effects of cell-derived MVs during endotoxic shock. nmMLCK deletion increased circulating levels of MVs. In nmMLCK-/- mice, platelet count was increased but the platelet ability to release MVs was reduced, and both leukocyte-derived MVs and leukocyte count were reduced. Endothelium-dependent relaxation of aorta was reduced in mice injected with MVs from nmMLCK+/+ (MVsnmMLCK+/+) but not from nmMLCK-/- mice (MVsnmMLCK-/-). In presence of lipopolysaccharide, MVsnmMLCK+/+ increased pro-inflammatory cytokine release by mouse aortic endothelial cells whereas MVsnmMLCK-/- enhanced anti-inflammatory secretome. Injection of MVsnmMLCK-/-, but not MVsnmMLCK+/+, prevented the increase of oxidative and nitrative stresses and reduced endothelial dysfunction in aorta from lipopolysaccharide-treated mice. Altogether, nmMLCK plays an important role in cellular activation and release of circulating MVs. Moreover, nmMLCK deletion generates MVs with low inflammatory properties and high protective effects.

Non-invasive and controlled release of bioactive compounds is an important goal in the development of drug delivery systems and novel biomaterials for tissue engineering. This project aims to exert spatio-temporal control over the release of bioactive compounds from phospholipid vesicle carriers by crosslinking them with superparamagnetic iron oxide nanoparticles to form a magnetic release nanostructure. The magnetic properties of the nanoparticles allow release to be triggered by an alternating magnetic field (AMF), which induces localised heating and “melts” the vesicle membranes. The aggregates can also be manipulated in space by a static magnetic field to create patterned materials. Incorporation of these aggregates into hydrogels has created novel responsive biomaterials. Controlled release of ascorbic acid-2-phosphate has been used to induce collagen production by chondrocytes, demonstrating an AMF triggered cellular response in vitro. The existing system has been redesigned after detailed characterisation and assessment of the performance of each component. Magnetic release has been extensively assessed using fluorescence techniques to quantify release, and optimised through the development of new silica-derived nanoparticle coatings and aggregate formulations informed by quantitative characterisation of nanoparticle functionalisation. The replacement of calcium alginate hydrogels as a 3D cell culture matrix with hyaluronic acid- based hydrogels was found to eliminate gel-induced leakage of vesicle contents and also improves the compatibility of the system with a greater range of cell types. Recently the effective encapsulation and AMF-triggered release of proteins including enzymes has been demonstrated and released enzymes have been demonstrated to retain their activity. Released trypsin was shown to retain proteolytic activity while hyaluronidase released into hyaluronan-derived hydrogels has been demonstrated to influence the rheological properties of the gel. A galactose-terminated lipid has been synthesised that enables specific targeting of the asialoglycoprotein (ASGPR) cell surface receptor receptor found in human hepatocytes, demonstrating the potential for customisation of the MNPV system to particular requirements.

A extensão relativa da dissociação iônica (α) de micelas de cloreto de hexadecildimetilamônio (CTACI), brometo de hexadecildimetilamônio (CTAB), vesículas de cloreto de dioctacecildimetilamônio (DODAC) e brometo de dioctadecildimetilamônio (DODAB) foram determinadas usando um método de dediazonização. O método de dediazonização consiste na determinação de produtos resultantes da lenta decomposição espontânea de tetrafluorborato de 2,4,6-trimetilbenzenodiazônio, seguida pela reação rápida do cátion fenílico com nucleófilos presentes no meio. Foi demostrado que este método determina a composição relativa da pseudofase aquosa interagregado. Os valores de α obtidos para CTACI e CTAB foram, respectivamente, 0,29 e 0,26, em excelente concordância com valores previamente publicados. O coeficiente de troca iônica para brometo/cloreto, determinado através do mesmo método, foi de 2,65, coincidindo com dados publicados. Estes valores confirmam o uso deste método para se obter tanto grau de dissociação iônica relativo como coeficientes de seletividade. O método foi também aplicado para a determinação do grau de dissociação iônica externo (αe e interno (αi) de vesículas de DODAC e DODAB. Para vesículas de DODAB sonicadas por tip obteve-se αe de 0,20; para vesículas de DODAC sonicadas em banho αe foi 0,20; para vesículas de DODAC sonicadas por tip αe foi 0,25 e para vesículas de DODAC grandes αe foi 0,11. Foi também determinado, pela primeira vez, o valor de 0,07 para o αi de vesículas grandes de DODAC. O conjunto de valores obtidos para αi e αe permitiram a análise quantitativa da catálise pelo compartimento aquoso interno e externo de vesículas sem a utilização de α como parâmetro ajustável. Foi modelado com sucesso a decomposição espontânea do íon 6-nitrobenzisoxazol-3-carboxilato e a hidrólise alcalina do ácido 5,5\'-ditiobis(2-nitrobenzóico). Este trabalho é a primeira análise quantitativa de reações modificadas por vesículas nos dois compartimentos usando dados independentes para dissociação iônica das superfícies vesiculares. / The relative extents of ion dissociation (α) from micelles of hexadecyltrimethylammonium (CTA) chloride (CTACl) and bromide (CTAB) and vesicles of dioctadecyldimethylammonium (DODA) chloride (DODAC) and bromide (DODAB) were determined using a dediazoniation method. The dediazoniation method consists in the determination of the products resulting from the slow spontaneous decomposition of 2,4,6-trimethylbenzene diazonium tetrafluoroborate, followed by fast reaction of the resulting phenyl cation with neighboring nucleophiles. This method was shown to determine the relative composition of the interaggregate aqueous pseudophase and, consequently, the degree of ion dissociation of the aggregate. The values of α obtained for CTACl and CTAB were, respectively, 0.29 and 0.26, in excellent agreement with previously published values. The ion exchange selectivity coefficient for bromide/chloride exchange, determined using the same method was 2.65, coinciding with published data. These values lend confidence to the use of this method for obtaining both relative dissociation degrees and ion selectivity coefficients. The method was also applied for the determination of the external (αe)as well as the internal (αi) α of DODAC and DODAB vesicles. For tip-sonicated DODAB vesicles αe was 0.20, for bath-sonicated DODAC αe was 0.20, for tip-sonicated DODAC αe was 0.25 and for large DODAC vesicles a was 0.11. We also determined, for the ftrst time, the a value of 0.07 for αi of large vesicles. The set of values obtained for αi and αe permitted quantitative analysis of two reaetions in both the internal and external aqueous compartments of vesicles without recourse to ion dissociation adjustable parameters. We successfully modeled the spontaneous decomposition of 6-nitrobenzisoxazol-3-carboxylate and the alkaline hydrolysis of 5,5\'-dithiobis(2-nitrobenzoate). This work is the first quantitative analysis of vesicle-modified reactions in both vesicle compartments using independent data for ion dissociation from vesicle\'s surfaces.

A acne vulgar é uma das doenças cutâneas mais comuns, apresentando como um de seus fatores fisiopatológicos primários a colonização pelo microrganismo Propionibacterium acnes. Atualmente, têm-se buscado terapias alternativas para o combate ao P. acnes, destacando-se alguns ácidos graxos, como o ácido laúrico (LA). O LA é uma molécula pouco solúvel em água, sendo possível sua incorporação em lipossomas. Os lipossomas apresentam capacidade de encapsulação/ liberação de ativos e impedem a desidratação da pele, tornando-se ingredientes inovadores na área de cosméticos. Foram preparados lipossomas de dipalmitoilfosfatidilcolina (DPPC) contendo diferentes concentrações de LA, que variaram de 0 a 50% da concentração total em mol, em quatro pHs: 9,0, 7,4, 5,0 e 3,0. Nestes pHs o estado de protonação do LA muda variando de 0 a -1. Os lipossomas foram extrusados por filtros com poros de 100 nm de diâmetro visando à obtenção de vesículas unilamelares grandes (LUV). As LUV foram caracterizadas quanto a sua estabilidade em condições de prateleira, temperatura de transição de fase da bicamada, encapsulamento no interior aquoso, liberação do LA, difusão das vesículas na pele e seus aspectos morfológicos foram caracterizados por espalhamento de raios-X a baixo ângulo (SAXS) e crio-microscopia eletrônica de transmissão. Estudos de estabilidade mostraram que independentemente da concentração de LA, as formulações são mais estáveis em pHs mais altos, quando LA está em sua maioria na forma de laurato. Os experimentos de DSC revelaram que em pHs 3,0 e 5,0 e concentrações maiores de LA, a interação deste ácido graxo com as bicamadas é favorecida, havendo um aumento da temperatura de transição de fase (Tm) e diminuição da cooperatividade. Análises de taxa de incorporação de sondas hidrofílicas confirmaram a presença de um compartimento aquoso interno para as vesículas de DPPC:LA. O LA conseguiu permear a pele no período avaliado e pouco LA foi liberado das vesículas em condições de temperatura ambiente. A morfologia das LUV se mostrou bem diferente da esperada e se observaram vesículas com mais de uma bicamada e outros formatos que não o esférico. Estes resultados podem auxiliar na otimização das condições para uma formulação que poderá ser usada no tratamento da acne, aumentando a eficácia do LA no sítio alvo. / Acne vulgaris is one of the most common skin diseases, presenting as one of its causes the microorganism Propionibacterium acnes colonization. Currently, it has been sought alternatives therapies against P. acnes, especially some fatty acids, like the lauric acid (LA). LA is a molecule with low water solubility, allowing its incorporation in liposomes. Liposomes have encapsulation/release capacity of drugs and promote skin lipids regeneration, becoming an innovative ingredient in cosmetics area. Dipalmitoylphosphatidylcholine (DPPC) vesicles containing different LA concentrations were prepared at pHs: 9.0, 7.4, 5.0 and 3.0. At these pHs the LA protonation changes and its charge varies from 0 to -1. The vesicles were extruded through filters containing pores of 100 nm to obtain large unilamellar vesicles (LUV) that were characterized for stability in shelf conditions, bilayer phase transition temperature, aqueous internal compartment encapsulation, LA release and in vitro skin permeation. Its morphological features were characterized by small angle X-ray scattering (SAXS) and cryo-electron transmission microscopy. Stability assays showed that, regardless LA concentration, formulations were more long-term stable in higher pHs, when LA is mostly in the form of laurate. The differential scanning calorimetry, DSC, experiments showed that, at pHs 3.0 and 5.0 and higher LA concentrations, the interaction between the bilayer and LA is favored, increasing phase transition temperature (Tm) and reducing cooperativity. Incorporation of hydrophilic probes confirmed the presence of an internal aqueous compartment in DPPC:LA vesicles. The LA managed to permeate the skin on the period evaluated and, in ambient conditions, low LA concentration was released from the vesicles. LUV containing more than one bilayer and non-spherical structures were observed. The obtained results may help in the optimization of the conditions for a formulation that can be used in the treatment of acne and improving the effectiveness of LA delivery to the target site.