Le follicule pileux (FP) est un appendice cutané animé par un cycle régénératif dynamique provoquant des modifications de son microenvironnement. Les cellules de Langerhans (CLs), sentinelles de l’épiderme, sont en partie localisées à proximité du FP. Cette association spatiale nous a conduit à explorer le possible impact du cycle pileux sur l’homéostasie des CLs. Durant mon doctorat, nous avons mis en évidence (1) une augmentation de la prolifération des CLs au cours de l’anagène (phase de pousse du poil), (2) le mécanisme moléculaire sous-jacent impliquant une variation d’expression folliculaire de l’IL-34, une cytokine cruciale dans l’homéostasie des CLs et (3) un départ accru des CLs vers les ganglions lymphatiques en catagène (phase de régression du FP) concomitant avec le recrutement de cellules susceptibles d’être des précurseurs des CLs.Par ailleurs, la structure de la peau ainsi que la densité et le type de FP peuvent varier selon la région corporelle considérée. Nous avons émis l’hypothèse de variations locales dans la composition du système immunitaire cutané. Notre étude, focalisée sur les cellules dendritiques cutanées, a démontré l’existence d’une hétérogénéité de ces cellules en fonction de la zone de peau considérée. / The hair follicle (HF) is a skin appendage endowed with a dynamic regenerating cycle. This renewal remodels the HF microenvironment. Langerhans cells (LCs) are epidermal immune sentinels, a part of which localizes close to the HF. This spatial association led us to explore whether the HF cycle could impact on LC homeostasis. During my doctorate, we uncovered an anagen (HF growing phase)-associated burst of LC proliferation with dividing cells associated with the HF. Using mouse models of HF loss and hair cycle manipulation, we showed that HFs are dispensable for initial formation of the LC network but critical for the proliferation burst. We correlated it to a cyclic variation of IL-34 expression, a crucial cytokine for LC homeostasis, by a specific subset of HF cells. In addition, catagen (HF regression phase) is characterized by the departure of LCs to draining lymph nodes and the concomitant recruitment of a potential LC precursor.The skin structure as well as the density and type of HFs vary across body areas. This observation led us to assess the possibility of local variations in skin immune cells composition. Our study, focused on cutaneous dendritic cells, highlighted an heterogeneity in those cells according to the skin area considered.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Sugar is one of the most widely used products in the treatment of wounds in veterinary medicine. Its main advantage is the hygroscopic effect on tissues and the bacterial death by plasmolysis, making it a bactericidal agent due to the physical effect observed, without leading to bacterial resistance as it might occur with antibiotic therapy. The objective of this experiment was to compare cicatricial evolution in cutaneous wounds with the topical use of sugar both granulated and in the form of a gel. For such, 16 canine wounds were treated, where eight received treatment with granulated sugar (group A) and eight with sugar gel (group G). Evaluations such as mensurations of the wounded areas, bacteriological cultures and observation of the aspect of the lesions were done weekly from the moment of the first examination until the formation of enough granulation tissue to suspend the use of the products. When comparing the decline in the area between groups no statistical difference was observed at any time. However, when the areas were analyzed in each group's interval, it was possible to notice a statistically significant decline between days 1-14 and 7-14 in the group treated with sugar. In the group treated with the gel, beside those intervals, a significant decline was also noticed between days 1-7. In terms of the frequency of negative bacteriological culture, there was no statistical difference between groups, not even in the different moments of each group. The time taken for the granulation tissue to be fully formed varied from 7 to 14 days in both groups. As to applicability, the gel showed better adhesion to the wounds and filling of the product subcutaneously more effectively than the granulated sugar. The conclusion reached is that both the sugar and the gel were effective in healing the animals' wounds in this experiment, the gel having demonstrated precocity in cicatricial retraction in the first seven days. / O açúcar é um dos produtos mais utilizados para tratamento de feridas em medicina veterinária. Sua principal vantagem é o efeito higroscópico nos tecidos e morte das bactérias por plasmólise, tornando-o um bactericida pelo efeito físico realizado, sem levar à resistência bacteriana, como poderia ocorrer na terapia antibiótica. O objetivo desse experimento foi comparar a evolução cicatricial de feridas cutâneas com o uso tópico de açúcar na forma granulada e na forma de gel. Para tal, foram tratadas 16 feridas de cães, onde oito receberam tratamento com açúcar granulado (grupo A) e oito com gel de açúcar (grupo G). Avaliações como mensurações das áreas das feridas, culturas bacteriológicas e observação quanto ao aspecto das lesões foram realizadas semanalmente desde o momento do atendimento até a formação de tecido de granulação suficiente para suspender o uso dos produtos. Na comparação da diminuição da área entre os grupos não se observou diferença estatística em nenhum momento. Entretanto, quando as áreas foram analisadas nos intervalos de cada grupo, pôde-se perceber diminuição estatisticamente significativa entre os dias 1 e 14 e 7 e 14 no grupo tratado com açúcar. No grupo tratado com gel, além desses intervalos, também se percebeu diminuição significativa entre os dias 1 e 7. Com relação a frequência de cultura bacteriológica negativa, não houve diferença estatística entre os grupos, nem nos diferentes momentos de cada grupo. O tempo para completa formação de tecido de granulação variou entre sete e 14 dias em ambos os grupos. Quanto à aplicabilidade, o gel demonstrou melhor adesão nas feridas e preenchimento do produto no subcutâneo de forma mais efetiva que o açúcar granulado. Conclui-se que tanto o gel quanto o açúcar foram efetivos na cicatrização das feridas dos animais desse experimento, sendo que o gel demonstrou precocidade na retração cicatricial nos primeiros sete dias.

Na+/K+-ATPase has been shown to regulate the sweating and cutaneous vascular responses during exercise; however, similar studies have not been conducted to assess the roles of the Na-K-2Cl cotransporter (NKCC) and K+ channels. Additionally, it remains to be determined if these mechanisms underpinning the heat loss responses differ with exercise intensity. Eleven young (24±4 years) males performed three 30-min semi-recumbent cycling bouts at low (30% VO2peak), moderate (50% VO2peak), and high (70% VO2peak) intensity exercise, respectively, each separated by 20-min recovery periods. Using intradermal microdialysis, four forearm skin sites were continuously perfused with either: 1) lactated Ringer solution (Control), 2) 6 mᴍ ouabain (Na+/K+-ATPase inhibitor), 3) 10 mᴍ bumetanide (NKCC inhibitor), or 4) 50 mᴍ BaCl2 (non-specific K+ channel inhibitor); sites at which we assessed local sweat rate (LSR) and cutaneous vascular conductance (CVC). Inhibition of Na+/K+-ATPase attenuated LSR compared to Control during the moderate and high intensity exercise bouts (both P˂0.01), whereas attenuations with NKCC and K+ channel inhibition were only apparent during the high intensity exercise bout (both P≤0.05). Na+/K+-ATPase inhibition augmented CVC during all exercise intensities (all P˂0.01), whereas CVC was greater with NKCC inhibition during the low intensity exercise only (P˂0.01) and attenuated with K+ channel inhibition during the moderate and high intensity exercise conditions (both P˂0.01). We show that Na+/K+-ATPase, NKCC and K+ channels all contribute to the regulation of sweating and cutaneous blood flow but their influence is dependent on the intensity of exercise.

Contexte: Simuler le comportement du complexe peau/tissu sous-cutané (CPTSC) au cours d'une chirurgie présente de nombreuses difficultés liées principalement à sa complexité anatomique qui génère un comportement mécanique complexe. Les modèles de simulation existants sur ce sujet se présentent majoritairement sous forme d'une mono-couche homogène et isotrope de comportement élastique linéaire. Ils ne prennent jamais en considération les moyens d'union conjonctifs du CPTSC pourtant responsables de la complexité de son comportement mécanique. L'augmentation tissulaire chirurgicale et en particulier l'autogreffe adipocytaire vise à restituer un volume corporel amputé par exemple par un traumatisme ou par une chirurgie carcinologique. A l'heure actuelle, seule l'expérience du chirurgien permet de prévoir l'effet d'une chirurgie d'augmentation tissulaire dans un contexte préopératoire donné. Un outil de simulation et de prévision fiable permettrait d'améliorer l'adhésion des patients à certains protocoles de traitement lourds, d'éviter certaines impasses thérapeutiques ou pourrait servir de support pédagogique.Objectifs: Dans un but de simulation et de prévision chirurgicale, nous avons souhaité développer un modèle mécanique du complexe peau tissu sous-cutané entièrement paramétrable par certaines données morphologiques des patients et adaptable à toute les régions du corps.Patients et méthodes: Afin de confirmer l'existence d'un modèle organisationnel générique du CPTSC, nous avons fait plusieurs acquisitions en IRM 3T de l'ensemble du corps. Ces acquisitions nous ont permis de mettre en évidence une organisation générique du CPTSC qui à été la base d'un modèle géométrique générique paramétrable. Afin de reconstituer l'architecture lobulaire du tissu adipeux et afin de restituer l'effet mécanique des moyens d'unions conjonctifs du CPTSC, nous avons construit de manière procédurale, à l'aide d'une tesselation de Voronoï, l'anatomie lobulaire et les septas inter-lobulaires. Une modélisation mécanique hybride a été réalisée grâce à la plateforme SOFA afin de respecter fidèlement l'organisation complexe du tissu de soutient collagénique. Pour valider le comportement mécanique de notre modèle, nous avons transcrit puis comparer les paramètres de tests d'indentation in vivo à notre modèle générique. Concernant l'augmentation tissulaire, nous avons simulé le phénomène de peau d'orange et les effets de l'autogreffe adipocytaire au dessus et en dessous du plan de fascia superficialis. Nous avons ensuite étudié les conséquences biomécaniques des fasciotomies qui sont utilisées en pratique courante. Nous avons finalement inclus ce modèle générique dans un modèle de face généré à partir des acquisitions IRM afin de simuler une autogreffe adipocytaire au niveau de la face. Résultats: Le modèle générique, paramétré de manière spécifique, nous a permis de transcrire de manière réaliste les tests d'indentation au niveau de l'avant-bras. Les simulations d'injection de graisse autologue ont pu simuler fidèlement les constatations opératoires et nous avons par ailleurs été capable de simuler le phénomène de peau d'orange en s'appuyant sur certaines de ses hypothèses physiopathologique. La simulation des fasciotomies nous a permis d'étudier pour la première fois l'effet mécanique de cette procédure. L'inclusion du modèle procédural dans un modèle géométrique spécifique de la face, acquis à partir de nos images IRM 3T, a pu aboutir à une simulation d'une autogreffe adipocytaire dans la joue. Conclusion: Malgré la mécanique complexe des tissus mous, nous avons pu établir un modèle mécanique fiable qui peut être spécifié de manière paramétrique. Après une phase de validation clinique et certaines améliorations mécaniques, nous souhaitons mettre au point des modèles spécifiques utilisables en simulation chirurgicale. / Background: Simulate the skin / subcutaneous tissue complex behavior presents many difficulties mainly related to its anatomical complexity that generates a complex mechanical behavior. Current simulation models on this subject appear mainly in the form of a homogeneous single layer of isotropic and linear elastic behavior. They never take into account the connective means of union of the skin and subcutaneous tissue which are responsible of the complexity of the mechanical behavior. The surgical tissue augmentation procedures and in particular autologous fat grafting aims to restore corporal volumes after a trauma or a carcinologic surgery. Currently, only the experience of the surgeon can predict the effect of a surgical tissue augmentation in a given preoperative context. A simulation and reliable prediction tool would improve patient adherence to certain protocols of heavy treatment, would avoid certain therapeutic impasses or could be used as a teaching aid.Objectives: As a surgical prevision and simulation tool, we wanted to develop a mechanical model of the skin / subcutaneous complex fully configurable by certain morphological data of patients and adaptable to any parts of the body. Patients and methods: To confirm the existence of a generic organizational model of subcutaneous tissue, we made several acquisitions in 3T MRI of the whole body. These acquisitions allowed us to highlight a generic pattern of organization of subcutaneous tissue that has been the basis of a generic geometric model fully configurable. To reconstruct the lobular architecture of adipose tissue and to restore the mechanical effect of the connective means of union, we constructed in a procedural manner, using a Voronoi tessellation. Hybrid mechanical modeling was performed with the SOFA framework. To validate the mechanical behavior of our model, we parametrized our generic model and transcribed the parameters of an in vivo indentation test and compare the results. Concerning tissue augmentation procedures, we simulated the phenomenon of cellulite and the effects of autologous fat grafting above and below the plane of superficial fascia. We then studied the biomechanical consequences of fasciotomies which are used in current practice. We finally included in our generic model of a face model generated from MRI acquisitions to simulate autologous adipocyte at the level of the cheek. Results: The model, allowed us to transcribe realistically indentation tests at the level of the forearm. Autologous fat injection simulations have faithfully simulate the operative findings and we have also been able to simulate the phenomenon of cellulite relying on some of its pathophysiological hypotheses. The simulation of fasciotomies has allowed us to study for the first time, the mechanical effect of this procedure. The inclusion of procedural model in a specific geometric model of the face result in an acurate simulation cheek fat grafting. Conclusion: Despite the complex mechanics of non visceral soft tissues, we have established a reliable mechanical model that can be specified parametrically. After a phase of clinical validation and some mechanical improvements, we hope to develop specific models used in surgical simulation.

This work sought to investigate the clinical phenotypes and molecular basis of cardio-facio-cutaneous syndrome (CFC), a germline disorder of the Ras-MAPK pathway, like Noonan syndrome (NS) and neurofibromatosis type I, caused by mutations in genes encoding proteins that act within this signal transduction pathway. CFC is most commonly due to mutation in BRAF, and less commonly MAP2K1, MAP2K2 or KRAS. A proportion of patients currently have no mutation identified. Mutations and clinical features of patients with a molecular diagnosis of CFC were investigated, which demonstrated a wide range of causative mutations, and some unclassified variants. Both known and novel clinical features of CFC were identified. A strong association between severe contractures and the p.(Tyr130Cys) mutation in MAP2K1 was found, which has not previously been reported. In contrast to the large number of patients with a confirmed molecular diagnosis, several with a highly suggestive clinical phenotype have been found to have no mutationin any of the known CFC genes. The molecular basis of these presentations was investigated by conventional Sanger sequencing of candidate genes. Fourteen patients with the p.(Ser2Gly) mutation in SHOC2 were identified, with clinical presentations consistent with CFC, NS or CS. Target enrichment and massively parallel sequencing of selected genes was undertaken in ten patients. Mutations in known genes were identified in four patients (including the positive control). Candidate causative variants in novel genes were suggested in two further patients, one of which was confirmed on Sanger sequencing. Whole exome sequencing of patient-parent trios was also undertaken to identify de novo variants. Three trios were analysed, and in one patient with a clinical diagnosis of CFC, a frameshift mutation in NF1 was identified, which was confirmed by Sanger sequencing to be present and de novo. The molecular effects of CFC-associated mutations in BRAF on Ras-MAPK pathway signalling were studied in cell culture systems, using Western blotting for ERK1/2 phosphorylation, in vitro kinase assays and luciferase assays, to assess activity of downstream targets of the Ras-MAPK pathway. Altered pathway activity was demonstrated for novel variants that had not previously been characterised at the molecular level, which was in keeping with the findings of the effects of previously studied mutations. The cardiac phenotype in animal models of CFC, CS and NS/CFC was explored using expression microarrays to identify potentially important genes and pathways in the pathogenesis of hypertrophic cardiomyopathy (a progressive but potentially treatable disease feature) in these conditions. A signature of increased expression of Myh7, the embryonic form of myosin, was identified in the heart of the mouse model of CFC due to a B-Raf mutation at four weeks postnatal age, but comparative analysis suggested significant differences in either the mechanisms causing cardiac phenotypes, or the timescales over which these may exert their effects, in the three models. In summary, the most significant findings of this work were that SHOC2 mutation is a frequent cause of a severe NCFC presentation, and massively parallel sequencing can be an effective means of molecular investigation of this group of disorders. Novel features of CFC syndrome that were identified include severe contractures in association with p.(Tyr130Cys) mutations in MAP2K1. The analysis of mouse models of the NCFCs was hampered by heterogeneity within the expression microarray results, and low levels of expression of the H-Ras mutant allele in the mouse model of Costellosyndrome.

Les lymphomes cutanés primitifs B comprennent 2 formes indolentes (lymphomes des centres folliculaires et de la zone marginale) et une forme clinique agressive, le lymphome B diffus à grandes cellules de type jambe. Si le lymphome des centres folliculaires ne présente le plus souvent pas la translocation t(14;18) à l'origine d'une dérégulation de BCL2 caractéristique des lymphomes folliculaires ganglionnaires, elle peut être identifiée en FISH dans 8,7% des cas et représenter un risque d'extension extra-cutanée. En revanche, l'étude de l'oncogenèse des lymphomes B de type jambe révèle des mécanismes communs d'oncogenèse avec les lymphomes B diffus à grandes cellules ganglionnaires, avec une répartition différente des altérations. Notamment, la mutation du gène MYD88L265P qui encode une protéine adaptatrice de la voie des Toll-like récepteurs responsable de l'activation constitutive de la voie NFκB, est très fréquemment observée (69% des cas) et est associée à une survie spécifique plus courte. De plus, contrairement aux autres lymphomes cutanés B, les cellules tumorales sont porteuses de multiples anomalies comme des translocations ou des délétions. D'autres arguments issus de l'analyse des séquences des gènes des immunoglobulines nous permettent de présumer que la cellule d'origine est un lymphocyte B mature, post-centre germinatif. Le fort taux de mutations identifiées reflète l'hypermutation somatique acquise à l'occasion du passage par le centre germinatif, mais l'expression d'un isotype primaire d'anticorps (IgM) suggère un blocage de la différentiation plasmocytaire terminale notamment pour la commutation isotypique. / Cutaneous B-cell lymphomas are represented by indolent B-cell lymphomas (follicle center and marginal zone), and primary cutaneous diffuse large B-cell lymphoma, leg-type which is characterized by an aggressive behavior. Primary cutaneous follicle center lymphoma usually do not harbor the t(14;18) translocation, which is characteristic of nodal follicular lymphoma and conduct to BCL2 overexpression. However, it can be observed by FISH in 8.7% of cutaneous cases and seems to be associated with extra-cutaneous disease. In contrast, primary cutaneous diffuse large B-cell lymphoma, leg-type shows common genetic alterations with its nodal counterpart diffuse large B-cell lymphoma, suggestive of common oncogenesis pathways, with distinct frequencies and repartition ofmutations. Especially, the MYD88L265P mutation that encodes an important adaptator protein of the Toll-like receptor pathway, activating NFκB, is very frequent (69% of cases) and associated with a shorter specific survival. Moreover, contrary to indolent primary cutaneous B-cell lymphoma, tumour cells often harbor multiple genetic alterations such as translocations and deletions. The analysis of the immunoglobulin genes sequences led us to suppose that the cell of origin could be a post germinal-center mature B-cell. Highly mutated sequences are the reflection of the germinal center passage, but IgM expression suggests a terminal differentiation blockage, notably with a class switch recombination defect.

No description available.

The study aimed to assess whether a short-term, high-intensity cold acclimation protocol would modulate finger vasomotor [i.e., finger temperature (TF), cold induced vasodilation (CIVD)] responses and regional thermo-perception to localized cooling. Six men performed a hand cold provocation (consisting of a 30-min immersion in 8°C water), while being whole-body immersed, once, in 21°C water (i.e., cold trial; HYPO), and, the following day, in 35.5°C water (i.e., normothermic trial; NORM). The local cold provocations were repeated, in the same order, after 10 days. In the intervening period, the subjects undertook a whole-body cold acclimation pro-tocol, consisting of daily whole-body 14°C-water immersions for 5 consecutive days, for a maximum of 2 h, while the skin temperature of the right hand was maintained at 35.6 (0.1)°C. Thermal (rectal temperature, skin temperature, finger temperature) cardiorespiratory (mean arterial pressure (MAP), heart rate and oxygen uptake), and perceptual responses (thermal sensation and comfort, pain, affective valence) were monitored throughout the trials. The acclimation protocol resulted in hypothermic adaptation (i.e., habituation), which was characterized by a modest reduction in shivering and an attenuation of whole-body thermal discomfort. The main finding of the study was that, regardless of subjects’ thermal status, the 5-day whole-body cold acclimation protocol did not alter TF (P > 0.1) and CIVD responses (P > 0.2) during local cold stress. Yet, after the acclimation, the cold-induced increase in MAP was reduced and tended to be reduced during the HYPO (P = 0.05) and NORM (P = 0.14) local cold provocation trials, respectively. Furthermore, the perceived thermal discomfort and pain in the immersed hand appeared to be alleviated in all post-acclimation trials.

Cat hair receptors were studied to determine whether they could be distinguished by the following receptive field characteristics: thickness of innervated guard hairs, distance between innervated follicles and receptive field size. Initially the receptors were classified as G1, GI, G2 or D on the basis of their velocity requirements for excitation, their degree of linear directionality, their vibrational sensitivity, and whether they were activated by movement of down hairs. It was found that the thickest guard hairs on the posterior aspect of a cat's hindleg were usually 4-5 times thicker than the thinnest guard hairs from the same area and that G1, GI and G2 neurons innervated the full range of guard hair thicknesses available. Although there was a tendency for thicker guard hairs to be more heavily innervated, none of the neurons studied innervated thick guard hairs exclusively. While movement of the down hair and most guard hairs within D-mechanoreceptive fields easily evoked activity, a few guard hairs were regularly found for which mechanical displacement did not elicit a discharge even though they were well within the receptive field. Receptive field sizes and nearest neighbor distances between innervated follicles were smaller for D than for G1, GI and G2 receptors and greater for G1 than GI and G2 receptors.

The purpose of this study was to characterize a novel technique to study neurogenic control of cutaneous vasodilation. We monitored skin blood flow (SkBF) during in-vivo electrical stimulation (e-stim) intended to activate cutaneous nerves and used intradermal microdialysis to deliver receptor antagonists to characterize their contribution to cutaneous vasodilation. We examined the role of acetylcholine receptors (RACh), nitric oxide (NO), and vasoactive intestinal peptide receptors (RVIP) on the cutaneous vasodilation induced by e-stim in the absence of the sympathetic adrenergic nervous system. Six men and three women participated in the study. Three intradermal microdialysis probes were placed in the skin of the dorsal side of their forearm. The adrenergic nervous system was eliminated by delivery of a cocktail of phentolamine (0.01 mg/ml), propranolol (1 mM), and BIBP-3226 (10 µM). At one skin site atropine (0.1 mg/ml) was delivered to block RACh. At a second site we blocked nitric oxide synthase (NOS, 10 mM L-NAME) and RACh. Finally at the third site, we blocked RACh, NOS, and RVIP (0.47 mg/ml VIP10-28). The SkBF response to 1 minute stages of graded increases in frequency (0.2, 1, 2, 4, 8, and 32 Hz) at a current of 1.0 ± 0.1 mA was used to generate a stimulus-response curve before and after drug delivery. At skin site 1 RACh blockade decreased the area under curve (AUC) by 4% from 614 ± 279 to 591 ± 331 (p>0.05). Nitric oxide synthase and RACh blockade reduced the vasodilator response to e-stim by 23% from 1036 ± 457 to 801 ± 448 AUC (p>0.05). Combined NOS, RACh, and RVIP blockade reduced the vasodilator response by 48% from 802 ± 412 to 418 ± 268 AUC (p=0.07). RACh blockade had no effect on the vasodilator response to e-stim. However, in these preliminary studies both NOS and RVIP blockade provided some attenuation of the cutaneous vasodilator response associated with e-stim. Additional studies will focus on these two neurotransmitters as this novel method is refined. Advantages of e-stim include activating the sympathetic nervous system without activating local and humoral factors and studying neurotransmitters in an in-vivo setting during rest, thermal stress, or exercise.