Les eczémas [eczéma allergique de contact (EAC) et l'eczéma atopique (EA)] sont des dermatoses inflammatoires fréquentes des pays industrialisés. Elles sont induites suite au recrutement et à l'activation dans la peau de lymphocytes T spécifiques d'allergènes, qui sont présents dans notre environnement, et qui sont habituellement très bien tolérés par la majoritédes individus exposés. Ce travail de thèse porte sur un aspect novateur de la physiopathologie des eczémas, à savoir : la contribution des lymphocytes T mémoires résidants (LTrm) dans la peau à la chronicité et à la sévérité de ces maladies.Capitalisant sur des modèles précliniques pertinents ainsi que sur des échantillons cliniques prélevés chez les patients, ce travail a permis d'acquérir de nouvelles connaissances : (i) de nombreux LTrm CD8+ spécifiques colonisent les lésions d'eczéma (ii) ils s'accumulent avecla persistance de l'allergène dans la peau, (iii) ils jouent un rôle majeur dans les récidives de la maladie, mais (iv) ils expriment à leur surface divers récepteurs inhibiteurs, tels que PD-1 ou TIM-3, qui empêchent la survenue de réponses allergiques excessives.Ces travaux apportent donc des informations majeures sur la nature unique des LTrm CD8+ spécifiques d'allergènes et des mécanismes qui contrôlent leur réactivation, afin de préserver l'intégrité de la peau et la survenue de réactions chroniques sévères. Le développement des nouvelles stratégies thérapeutiques ciblant la réactivation des LTrm via leurs récepteursinhibiteurs pourrait permettre de restaurer la tolérance chez les individus allergiques / Allergic contact dermatitis (ACD) and atopic dermatitis (AD), also referred to contact or atopic eczema, are frequent skin inflammatory diseases with increasing prevalence and high socioeconomic impact in Western countries. Eczemas are the prototype of skin delayed-type hypersensitivity reactions. Skin lesions are induced by the recruitment and activation in the skin of effector/memory T cells specific for environmental antigens that are innocuous to healthy non-allergic individuals.The aim of this work was to better understand the pathophysiology of eczemas by a comprehensive analysis of the contribution of skin resident memory T cells (Trm) to the chronicity and severity of these diseases.Capitalizing on relevant preclinical eczema models and on clinical samples collected from allergic patients, this work showed that: (i) numerous allergen-specific CD8+Trm colonize the eczema lesion, (ii) they accumulate in the epidermis in response to the long-term persistence of the allergen in the skin, (iii) they are instrumental for the recurrence of eczema, but (iv) theyexpress several inhibitory check point receptors (ICRs, such as PD-1, TIM-3) at their surface, which keep them in check to prevent the development of severe immunopathology.Thus, our work provides important information for considering the unique nature of hapteninduced CD8+ Trm and the mechanisms that prevent their unwanted reactivation and subsequent development of chronic or severe skin allergy. The development of therapeutic strategies targeting the reactivation of skin Trm in situ via their ICRs should open new avenues to restore tolerance in allergic individuals

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-10-10T13:46:10Z No. of bitstreams: 1 ingridpimentelcunhamagalhaesdesouzalima.pdf: 1571962 bytes, checksum: 521511b66ed89adf27b01a59f98c7cfc (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-10-16T13:34:14Z (GMT) No. of bitstreams: 1 ingridpimentelcunhamagalhaesdesouzalima.pdf: 1571962 bytes, checksum: 521511b66ed89adf27b01a59f98c7cfc (MD5) / Made available in DSpace on 2018-10-16T13:34:14Z (GMT). No. of bitstreams: 1 ingridpimentelcunhamagalhaesdesouzalima.pdf: 1571962 bytes, checksum: 521511b66ed89adf27b01a59f98c7cfc (MD5) Previous issue date: 2018-08-24 / O objetivo do presente estudo é avaliar a positividade do teste cutâneo de contato alérgico de leitura tardia para Dermatophagoides pteronyssinus, Dermatophagoides farinae e Blomia tropicalis em pacientes com doenças respiratórias como rinite alérgica e/ou asma com ou sem dermatite atópica. A maioria dos trabalhos existentes nessa área de pesquisa se refere ao emprego desse método diagnóstico na dermatite atópica, mas, neste estudo, a amostra é composta, principalmente, de pacientes com doenças respiratórias. Blomia tropicalis é um ácaro muito incidente no Brasil e só há dois trabalhos que envolvem o emprego deste ácaro da poeira domiciliar típico de países de clima tropical. Os pacientes foram selecionados pela história clínica e foram divididos em dois grupos: I- pacientes com doenças respiratórias, como asma e/ou rinite alérgica, com dermatite atópica e II- pacientes somente com doenças respiratórias. Foi realizado teste cutâneo de leitura imediata e teste de cutâneo de contato alérgico de leitura tardia para os três ácaros no mesmo dia. O teste de contato alérgico foi retirado em 48 horas. A análise estatísitica foi realizada em porcentagens e a tabela 1 apresenta as variáveis por sexo e por grupo estudado. Setenta e quatro pacientes, com idades de 2 a 60 anos, foram incluídos neste estudo; 16 no grupo I e 58 no grupo II. Considerando o teste cutâneo de leitura imediata, o ácaro mais prevalente foi o Dermatophagoides pteronyssinus, seguido pelo Dermatophagoides farinae e Blomia tropicalis. Em relação ao teste cutâneo de contato alérgico de leitura tardia, o ácaro que induziu maior positividade foi o Dermatophagoides farinae (78,4%), seguido pelo Dermatophagoides pteronyssinus (77%) e Blomia tropicalis (52,7%). Comparando o teste cutâneo de leitura imediata com o teste cutâneo de contato alérgico de leitura tardia, 53 pacientes (71,6%) foram positivos para ambos os testes, e 30 (56,6%) foram positivos ao mesmo ácaro. Foram identificados seis pacientes (8%) que tinham história clinica positiva para alergia e só apresentavam positividade no teste cutâneo de contato alérgico de leitura tardia. Estes resultados sugerem que o teste cutâneo de contato alérgico de leitura tardia é relevante e deve ser considerado como um teste diagnóstico adicional, em pacientes com história clínica positiva para doenças respiratórias, com teste cutâneo de leitura imediata negativa. / The aim of this study is to evaluate the positivity rates of atopy patch tests for Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis in patients with respiratory diseases such as asthma and allergic rhinitis with or without atopic dermatitis. Most studies have been performed with atopic dermatitis patients, but in our study, most of the patients had respiratory conditions. Blomia tropicalis is a mite that is prevalent in tropical areas, such as Brazil, and only two publications include these three mites, which are present in Brazil. The patients’ clinical histories were collected, and the patients were subjected to skin prick and patch tests with the three different house dust mites on the same day. The patch tests were examined 48 hours later, and then, the patients were divided into two groups: I- patients with respiratory diseases, such as asthma and/or rhinitis, and atopic dermatitis and II-patients with only respiratory diseases. The statistical analysis results are presented as percentages, and Table 1 presents the variables by gender and groups studied. A total of 74 patients ranging in age from 2 to 60 years old were included in this study; 16 patients were included in group I and 58 were included in group II. In the skin prick tests, the most prevalent mite that evoked a reaction was Dermatophagoides pterronyssinus, followed by Dermatophagoides farinae and Blomia tropicalis. Regarding the atopy patch tests, the mite that most frequently induced a positive reaction was Dermatophagoides farinae (78.4%), followed by Dermatophagoides pteronyssinus (77%) and Blomia tropicalis (52.7%). A comparison between the skin prick and atopy patch tests revealed that 53 patients (71.6%) were positive on both tests, and 30 (56.6%) patients were positivite for the same mite. We found six patients (8%) who had a positive clinical history of allergy and only exhibited positivity on the atopy patch test. These results suggest that the mite atopy patch test is relevant and should be considered as an additional test for patients with clinical histories of allergic respiratory disease who have negative prick test results.

Contexte : La prévalence de l'asthme et des allergies a augmenté au cours de ces dernières décennies,en particulier chez les enfants et dans le monde occidental. Cette augmentation de la prévalence estdevenue un problème très grave de santé publique et pourrait être liée à une combinaison deprédisposition génétique, de facteurs environnementaux et des changements dans le mode de vie, ycompris les habitudes alimentaires. Cependant, les études épidémiologiques concernant les maladiesallergiques chez l’enfant en relation avec l'alimentation sont rares.Objectifs : Ce travail analyse la littérature récente traitant l'alimentation, les habitudes alimentaires et lanutrition en relation avec les maladies allergiques chez les enfants en tenant compte de la méthodologieutilisée pour évaluer les habitudes alimentaires. En outre, il évalue en premier lieu l'association entre leshabitudes alimentaires et l'asthme et les maladies allergiques et en deuxième lieu la relation entrel'asthme et le surpoids/l’obésité dans l’étude des six villes françaises.Méthodes : MEDLINE/PubMed et Cochrane Database of Systematic Reviews ont été utilisés pour larevue de la littérature concernant l'alimentation et les maladies allergiques. Des études transversales ontété menées à Bordeaux, Clermont-Ferrand, Créteil, Marseille, Reims, Strasbourg sur 7 432 enfantsscolaires, choisis au hasard et âgés de 9-11 ans. Des questionnaires adressés aux parents, basés surl'Enquête internationale sur l'asthme et les allergies dans l'enfance (ISAAC), ont été utilisés pourrecueillir des informations sur les maladies allergiques et les facteurs de risque potentiels, y compris unquestionnaire de fréquence alimentaire pour évaluer les habitudes alimentaires des enfants. Des testscutanés aux allergènes communs ont été effectués afin d'identifier l'existence d'une hypersensibilitéallergique et des tests d’effort ont été effectués pour évaluer l'asthme à l’effort.Résultats : Les apports moyens de 12 principaux produits alimentaires consommés par les élèves ontété calculées et trois profils alimentaires ont été extraits par analyse en composantes principales:l’alimentation proche du régime méditerranéen, l’alimentation à base d’oméga-3 et de poissons gras etl’alimentation non équilibrée. Les risques relatifs des maladies allergiques ont été estimés par des odds7ratios (OR) et le contrôle des facteurs de confusion a été réalisé par des régressions logistiques. Lessifflements, l’asthme et la rhinite sont plus fréquents chez les garçons que chez les filles. En analysemultivariée, l’alimentation à base d’oméga-3 avait un effet protecteur contre l'asthme vie et l’asthmesévère chez les enfants (OR ajusté: 0,77 ; IC 95%: [0,62 -0,96] et OR ajusté: 0,55 ; IC 95%: [0,32 -0,94]respectivement). L’adhérence à une alimentation proche du régime méditerranéen et riche enantioxydants semble avoir un effet protecteur contre les maladies allergiques. Le surpoids et l’obésitéont été positivement associés avec l’asthme vie chez les enfants ne présentant pas de sifflements (ORajusté: 1,98 ; IC 95%: [1,06 -3,70]) et ont été de même associé positivement avec la rhinite vie et larhinite 12 mois chez les enfants présentant des sifflements (OR ajusté: 1,63 ; IC 95%: [1,09 -2,45] etOR ajusté: 2,20 ; IC 95%: [1,13 -4,27] respectivement), mais pas avec l’asthme à l’effort.Conclusion: Dans l'ensemble, l'adhésion à un régime alimentaire sain, y compris les antioxydants et lesoméga-3 semble avoir un effet protecteur sur l'asthme et les allergies chez les enfants. Le surpoids etl’obésité a été associé significativement avec l’asthme chez les enfants non atopiques et la rhiniteallergique chez les enfants atopiques. Des études prospectives longitudinales sont donc nécessaires pourpouvoir évaluer les relations de causalité. / Background: The prevalence of asthma and allergy has risen in recent decades, especially amongchildren and in the Western world. This increase in prevalence has become a serious public healthproblem and might be related to a combination of genetic predisposition, environmental factors, andlifestyle changes, including dietary habits. However, epidemiological studies concerning childhood dietrelatedallergic diseases are scarce.Objectives: This work reviews published literature dealing with diet, dietary patterns and nutrition inrelation with allergic diseases among children taking into account the methodology used to evaluatedietary patterns. Moreover, it assesses primary the association between food patterns and asthma andallergic diseases and secondary the relation between asthma and overweight/obesity in the French SixCities Study.Methods: MEDLINE/PubMed and Cochrane Database of Systematic Reviews were used for theliterature review concerning diet and allergic diseases. Cross-sectional studies were conducted inBordeaux, Clermont-Ferrand, Créteil, Marseille, Reims, and Strasbourg among 7432 randomly selectedschoolchildren aged 9-11 years. Parental questionnaires, based on the International Study on Asthmaand Allergies in Childhood (ISAAC), were used to collect information on allergic diseases and potentialrisk factors including a food frequency questionnaire to evaluate dietary habits. Skin prick testing tocommon allergens was performed to identify the existence of an allergic hypersensitivity and exercisetest was performed to assess Exercise-Induced Asthma (EIA).Results: The mean intakes of 12 main food items were calculated and three food patterns wereextracted by principal component analysis labeled: the Mediterranean-like diet, the diet rich in omega-3fatty acids and the unhealthy diet. Relative risks of allergic diseases were estimated as odds ratios (OR)and confounders control was performed with multiple logistic regressions. Wheezing, asthma andrhinitis were more prevalent in boys than in girls. In the multivariate analysis, diet rich in omega-3 wasprotective for lifetime and severe asthma in children (adjusted OR: 0.77; 95% CI: [0.62 -0.96] and9adjusted OR: 0.55; 95% CI: [0.32 -0.94] respectively). Adherence to the Mediterranean-like diet rich inantioxidants tended to be protective against allergic diseases. Overweight and obesity were positivelyassociated with lifetime asthma in non-wheezing children (adjusted OR: 1,98 ; 95% CI: [1,06 -3,70])and were also positively associated with lifetime and past year allergic rhinitis in wheezing children(adjusted OR: 1.63; 95% CI: [1.09 -2.45] and adjusted OR: 2.20; 95% CI: [1.13 -4.27] respectively), butwere not associated with EIA.Conclusion: Overall, adherence to a healthy diet including antioxidants and omega-3 fatty acids seemsto have a protective effect on asthma and allergy in childhood. Overweight and obesity weresignificantly associated with asthma in non-atopic children and with allergic rhinitis in atopic children.Prospective longitudinal studies should be necessary for evaluation of causal relations.

Background: Evidence-based treatment algorithms, successfully established for asthma, are missing for atopic eczema (AE). Objectives: To investigate whether treatment according to an evidence-based algorithm is an effective and applicable concept for the management of AE. Methods: Based on a systematic literature review, we developed an evidence-based severity-score-oriented treatment algorithm for AE and compared its effectiveness to that of an individualised symptom-oriented treatment (individual therapy) in a randomised controlled trial. Sixty-three participants were randomised to algorithm (n = 32) or individual therapy (n = 31) and treated accordingly for 12 months. Study end points included difference between baseline SCORAD and mean SCORAD under treatment (primary end point), quality of life and treatment utilisation. Analysis was by intention to treat (registration: ClinicalTrials.gov:NCT00148746). Results: No statistically significant differences in clinical or subjective response were observed between groups. Treatment following the algorithm and individual treatment both effectively controlled AE. Mean SCORAD reductions were 47% (95% confidence interval, CI = 38–55; algorithm) and 42% (95% CI = 29–54; individual). Clinical response was paralleled by improved quality of life in both groups. Physicians adhered to the algorithm option in 93% of their treatment decisions. Conclusion: Treatment following an evidence-based algorithm is an effective and applicable concept for the management of AE but does not show clear advantages compared to individualised treatment in a dermatological setting. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Background: Financial constraints challenge evidence of the effectiveness of dermatological inpatient management. Objective: To evaluate the effectiveness of hospitalization in atopic dermatitis and psoriasis regarding initial and sustained benefits. Methods: Prospective study on adults with psoriasis vulgaris (n = 22) and atopic dermatitis (n = 14). At admission, discharge, and 3 months after discharge, validated outcomes of objective and subjective disease severity were assessed by trained investigators. Results: Hospitalization resulted in substantial benefit in quality of life and clinical disease severity. Looking at mean scores, the observed benefit appeared stable until 3-month follow-up. The analysis of individual patient data revealed significant changes in disease severity between discharge and 3-month follow-up with some patients relapsing, others further improving. Reasons for hospitalization and treatment performed were not related to sustained benefit. Conclusions: In psoriasis vulgaris and atopic dermatitis, hospitalization effectively improved quality of life and clinical disease severity. Further research should focus on prognostic factors for sustained improvement. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Background: Pimecrolimus cream 1% is a non-steroid, selective inflammatory cytokine inhibitor indicated for atopic dermatitis (AD). Objective: To compare the safety and efficacy of pimecrolimus cream 1%-based treatment versus conventional therapy in adults with moderate AD. Methods: Patients were randomized to receive pimecrolimus cream 1% (n = 62) or vehicle (n = 68) at the first signs/symptoms of AD, for 24 weeks as required. A moderately potent topical corticosteroid (prednicarbate 0.25% cream) was allowed in both groups to treat flares. Results: Corticosteroids were required on fewer days in the pimecrolimus group, compared with the vehicle group (9.7 vs. 37.8%, p < 0.001). Furthermore, 59.7% of pimecrolimus-treated patients experienced no flares during the study period, compared with 22.1% of vehicle-treated patients (p < 0.001). Pimecrolimus cream 1% was well tolerated throughout the study. Conclusion: For adults with moderate AD, pimecrolimus cream 1% is well tolerated, reduces the incidence of flares, reduces/eliminates corticosteroid use, improves long-term disease control and enhances the patients’ quality of life. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Background: Pimecrolimus cream (Elidel®, SDZ ASM 981), a non-steroid inhibitor of inflammatory cytokines, is effective in the treatment of atopic dermatitis (AD). We assessed whether early treatment of AD signs/symptoms reduces the need for topical corticosteroids. Objective: To investigate the efficacy and safety of pimecrolimus cream 1% in the long-term management of adult AD. Methods: 192 adults with moderate to severe AD were randomised (1:1) for twice daily (b.i.d.) treatment of early signs or symptoms of AD with either pimecrolimus cream 1% or vehicle cream (control group) to prevent progression to flares. Treatment was given as needed for 24 weeks. In the event of flares, a moderately potent corticosteroid (prednicarbate 0.25% cream) was permitted as rescue medication in both groups. The percentage of days on which a topical corticosteroid was used to treat disease flares was the main outcome measure. Results: Corticosteroid medication was used on 14.2% (95% confidence interval, CI: 8.3–21.1) of the days of the 24-week treatment period in the pimecrolimus group and on 37.2% (95% CI: 30.4–44.0) of the days in the control group (p < 0.001). In total, 44.8% (43/96) of patients in the pimecrolimus group did not experience a flare compared with 18.8% (18/96) of patients in the control group. The median time to first flare was 144 days in the pimecrolimus group and 26 days in the control group (p < 0.001). Pimecrolimus treatment was also associated with improvement in signs and symptoms of AD, pruritus, patients’ self-assessment and quality of life. Conclusions: Pimecrolimus cream 1% b.i.d. is an effective, well-tolerated, long-term treatment for AD in adults, substantially reducing the number of flares compared to a conventional therapy and consequently reducing or eliminating the need for corticosteroid treatment. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Allergic manifestations are increasingly common in infants and children. Accumulating evidence suggests that the ‘epidemic’ increase of childhood allergy may be associated with environmental factors such as stress. Although the impact of stress on the manifestation and exacerbation of allergy has been demonstrated, the underlying mechanisms of stress-induced exacerbation are still obscure. A growing number of studies have suggested an altered hypothalamus-pituitary-adrenal (HPA) axis function to stress in allergic children. It is speculated that a dysfunctional HPA axis in response to stress may facilitate and/or consolidate immunological aberrations and thus, may increase the risk for allergic sensitization and exacerbation especially under stressful conditions. In the present review the potential impact of a hyporesponsive as well as a hyperresponsive HPA axis on the onset and chronification of childhood allergy is summarized. Moreover, potential factors that may contribute to the development of an aberrant HPA axis responsiveness in allergy are discussed. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

La pathogenèse de la sacculite anale demeure incomprise. Cette condition semble cependant être plus fréquente chez les chiens atopiques. La sacculite anale se traite principalement avec un antibiotique. Avec la montée de l’antibiorésistance, il est important de mieux comprendre sa pathogenèse afin de prévenir la maladie et trouver des traitements alternatifs aux antibiotiques. Cette étude visait donc à comparer le microbiote bactérien et les cytokines pro-inflammatoires dans les sacs anaux de chiens sains à ceux de chiens atopiques, afin de déterminer si des changements pourraient être à l’origine des sacculites anales chez les chiens atopiques. L’hypothèse de ce projet était que le microbiote bactérien et les cytokines pro-inflammatoires dans les sacs anaux des chiens sains diffèrent de ceux des chiens atopiques traités ou non traités. Les principaux objectifs de cette étude étaient donc de caractériser le microbiote bactérien (MB) des sacs anaux des chiens atopiques recevant ou non un traitement (oclacitinib, cetirizine ou immunothérapie allergénique) et de déterminer si la concentration de certaines cytokines pro-inflammatoires libérées dans les sacs anaux variait entre les chiens sains et les chiens atopiques non traités (CANT) et les chiens atopiques traités (CAT). Des écouvillons floqués ont été utilisés pour échantillonner le rectum et les sécrétions provenant des sacs anaux de 15 chiens sains, six CAT et 14 CANT pour l’analyse du microbiote bactérien. L’extraction de l’acide désoxyribonucléique a été effectuée avec le kit commercial DNeasy PowerSoil. Le séquençage de la région V4 du gène de l’acide ribonucléique ribosomique 16S a ensuite été réalisé avec la plateforme Illumina MiSeq. Pour l’analyse des cytokines, le contenu des sacs anaux de 15 chiens sains, 12 CANT et cinq CAT a été prélevé dans un microtube. Chaque microtube a été mélangé au vortex. Le surnageant a ensuite été prélevé. Les microtubes contenant le surnageant ont ensuite été congelés à -80°C jusqu’à leur analyse. La concentration de l’interféron gamma, des interleukines (IL)-2, 6, 8, 10 et 12/23p40, de la protéine chimiotactique 1 des monocytes, du facteur de croissance des nerfs bêta, du facteur de cellules souches, du facteur de nécrose tumorale alpha (TNF-α) et du facteur de croissance de l’endothélium vasculaire A a été mesurée avec le test multiplex de Luminex. L’appartenance à la communauté était différente entre les sacs anaux des chiens sains et des CANT, des chiens sains et des CAT et des CANT et des CAT (P = 0,002, P = 0,013 et P = 0,012, respectivement). La structure de la communauté était différente entre les chiens sains et les CANT (P = 0,003) et entre les CANT et les CAT (P = 0,017), mais pas entre les chiens sains et les CAT (P = 0,332). Toutes les cytokines pro-inflammatoires évaluées ont été détectées dans les sacs anaux de chiens sains, de CANT et de CAT. Il n’y avait aucune différence significative entre les groupes, excepté pour l’IL-8 et le TNF-α, où l’IL-8 était plus élevée dans les sacs anaux des CANT en comparaison avec ceux des CAT (P = 0,02), et le TNF-α était en concentration plus faible dans les sacs anaux des chiens sains comparativement aux sacs anaux des CAT (P = 0,04). Il y a une dysbiose dans les sacs anaux de chiens atopiques, ce qui pourrait expliquer pourquoi les chiens atopiques semblent prédisposés à développer des sacculites anales bactériennes. Les traitements (oclacitinib, cetirizine et immunothérapie allergénique) semblent également modifier la composition du microbiote bactérien dans les sacs anaux des chiens atopiques pour qu’elle se rapproche de celle des chiens sains. L'IL-8 pourrait également jouer un rôle dans le développement de la sacculite anale. D’autres études évaluant un plus large nombre de cytokines permettraient possiblement de mettre en évidence des cytokines ayant un rôle important lors de sacculite anale chez les chiens atopiques. / The pathogenesis of anal sacculitis is not well understood. However, this condition appears to be more common in atopic dogs. Anal sacculitis is primarily treated with antibiotic therapies. With the rise of antimicrobial resistance, it is important to better understand the pathogenesis of anal sacculitis in order to prevent the disease and find alternative treatments to antibiotics. The present study aimed to compare the bacterial microbiota and pro-inflammatory cytokines in the anal sacs of healthy dogs with those of atopic dogs, in order to determine if there are changes that could explain anal sacculitis in atopic dogs. The hypothesis of this project was that the bacterial microbiota and proinflammatory cytokines in the anal sacs of healthy dogs differ from those of treated and untreated atopic dogs. The main objectives of this study were therefore to characterize the bacterial microbiota of the anal sacs of atopic dogs receiving or not a treatment (oclacitinib, cetirizine or allergen-specific immunotherapy) and to determine if the concentration of certain proinflammatory cytokines released in the anal sacs differed between healthy, untreated atopic dogs (UAD) and treated atopic dogs (TAD). Flocked swabs were used to sample the rectum and secretions from the anal sacs of 15 healthy dogs, six TAD and 14 UAD for bacterial microbiota analysis. Deoxyribonucleic acid extraction was performed with the commercial DNeasy PowerSoil kit. Sequencing of the V4 region of the 16S ribosomal ribonucleic acid gene was then performed with the Illumina MiSeq platform. For cytokine analysis, the contents of the anal sacs of 15 healthy dogs, 12 UAD, and five TAD were collected in a microtube. Each microtube was vortexed before the supernatant was collected. The microtubes containing the supernatant were then frozen at -80°C until analysis. The concentration of interferon gamma, interleukin (IL)-2, 6, 8, 10, and 12/23p40, monocyte chemotactic protein 1, nerve growth factor beta, stem cell factor, tumor necrosis factor-alpha (TNF-α), and vascular endothelial growth factor-A were measured with the Luminex multiplex assay. Community membership was different between the anal sacs of healthy dogs and UAD, healthy dogs and TAD, and UAD and TAD (P = 0.002, P = 0.013, and P = 0.012, respectively). Community structure was different between healthy dogs and UAD (P = 0.003) and between UAD and TAD (P = 0.017), but not between healthy dogs and TAD (P = 0.332). All proinflammatory cytokines assessed were detected in the anal sacs of healthy dogs, UAD, and TAD. There were no significant differences between groups except for IL-8 and TNF-α. IL-8 was higher in UAD anal sacs compared to TAD anal sacs (P = 0.02) and TNF-α was in lower concentration in healthy dog anal sacs compared to TAD anal sacs (P = 0.04). There is a dysbiosis between the anal sacs of UAD and TAD which might explain why atopic dogs seem predisposed to bacterial anal sacculitis. Treatments received by atopic dogs (oclacitinib, cetirizine and allergen-specific immunotherapy) shift the microbiota of the anal sacs towards that of healthy dogs. IL-8 may also play a role in the development of anal sacculitis. Further studies on a larger number of cytokines may identify cytokines that are important in the pathogenesis of anal sacculitis in atopic dogs.

Atopic dermatitis (AD) and other atopic diseases are strongly related to skinbarrier dysfunction, a biomeasure which has limited and unsatisfactory assessmenttechniques. Machine learning (ML) powered electrical impedance spectroscopy(EIS) has been shown to differentiate defective barrier function in mice and adults. Techniques such as principal component analysis (PCA) andsupport vector classifiers (SVC) can be used as ML tools to evaluate EIS measurements. EIS measurements taken on unaffected skin of children aged between 4 monthsand 3 years were collected and analysed using the children’s AD status. Measurements were grouped into one of four groups based on this AD status; No AD (No AD was developed up until 2 years of age), Pre AD (measurements takenbefore the onset of AD), AD remission (measurements taken after the onset ofAD) and AD flare (measurements taken during active AD). A SVC model was trained on the raw EIS measurement data to distinguish measurements from twoof the binarized AD status groups; AD flare and No AD. An additional SVC model was trained on the No AD group, distinguishing measurements based onbinarized age groups: measurements taken at 4 months against measurements taken at 3 years of age. The AD model tested on AD flare against No AD within the test set yielded AUC of 0.92, with a sensitivity and specificity of 89.29% and 88.89% respectively. When testing on all groups of the test set, Pre AD and AD remission groups had group means between the AD flare and No AD groups. No data bias against age was detected in the model. The results of the age model showed that age could be chronologically identified by the age model. The AD model was able to differentiate active AD children from children never experiencing AD symptoms on visually unaffected skin and in turn detecting skin barrier dysfunction. Separate studies would need to be conducted to test the predictive power and external validity of the model. Age is a significant factor to consider when designing ML models using EIS data in children, with proper balance in the training set a data bias within the model can be avoided. EIS is a versatile technique due to its data rich nature. Machine learning powered electrical impedance spectroscopy measurements are able to detect skin barrier dysfunction. Age is a significant factor when measuring EIS on children, but can be managed. / Atopisk dermatit (AD) och andra atopiska sjudomar är starkt kopplade tillhudbarrärdefekter, en hudegenskap där diagnosverktygen är begränsade och otillräckliga. Maskininlärning (ML) i kombination med elektrisk impedansspektroskopi (EIS) har visats att kunna differentiera defekta hudbarrärer i möss och hos vuxna människor. Tekniker såsom principalkomponentanalys (PCA) och stödvektormaskiner (SVM) kan användas som ML verktyg för att utvärdera EIS-mätningar. Statistiska analysverktyg såsom reciever operator characteristics (ROC) tillsammans med arean under kurvan (AUC) och andra precisionsmått kan användas för att utvärdera ML modeller. EIS-mätningar utförda på opåverkad hud hos barn mellan 4 månader och 3 års ålder samlades och analyserades med hjälp av barnens atopiska status. Samtliga mätningarna grupperades i en av totalt fyra grupper baserade på deras atopiska status; Ingen AD (Ingen AD hade utvecklats upp till 2 års ålder), Pre AD (mätningarna togs innan sjukdomsförloppet), AD remission (mätningarna togs efter sjukdomsförloppet) och AD aktiv (mätningarn togs under sjukdomsförloppet). En SVM modell tränades på EIS-rådata för att särskilja mellan två av grupperna binärt; AD aktiv och ingen AD. En ytterliggare SVM modell tränades på endast ingen AD-gruppen för att särskilja mellan mätningarna tagna vid åldrarna 4 månader och 3 år, omgjorta till binära grupper.  AD modellen testades med en jämförelse mellan AD aktiv-gruppen och ingen AD-gruppen med test data och resulterade i en AUC på 0.92, med en respektive sensitivitet och specificitet på 89.29\% samt 88.89\%. Modellen testades även på de ytterliggare grupperna i test datan, Pre AD och AD remission som båda hade gruppmedelvärden som låg mellan AD aktiv-gruppens och ingen AD-gruppens. Inga systematiska fel med avseende på barnens ålder hittades i AD-modellen. Resultaten från ålders-modellen visade på att modellen kunde rangordna mätningarna baserat på ålder. AD-modellen kunde differentiera barn med aktiv AD mot barn som aldrig hade uppvisat atopiska symptom på opåverkad hud, vilket innebär en differentiering av hudbarrärdefekter. Separata studier är nödvändiga för att testa prediktiv prestanda hos modellen samt dess externa validitet. Ålder är en signifikant faktor när ML modeller med EIS-data ska designas, men med tillräcklig balans i träningsdatan kan systematiska fel förhindras. EIS är en versatil teknik med avseense på dess datakomplexitet. EIS tillsammans med maskininlärning kan särskilja defekta hudbarriärer hos barn. Ålder är en signifikant faktor när EIS mäts på barn, men kan hanteras.