A mechanistic target of rapamycin complex 1/2 (mTORC1)/V-Akt murine thymoma viral oncogene homolog 1 (AKT1)/cathepsin H axis controls filaggrin expression and processing in skin, a novel mechanism for skin barrier disruption in patients with atopic dermatitis

Background Filaggrin, which is encoded by the filaggrin gene (FLG), is an important component of the skin's barrier to the external environment, and genetic defects in FLG strongly associate with atopic dermatitis (AD). However, not all patients with AD have FLG mutations. Objective We hypothesized that these patients might possess other defects in filaggrin expression and processing contributing to barrier disruption and AD, and therefore we present novel therapeutic targets for this disease. Results We describe the relationship between the mechanistic target of rapamycin complex 1/2 protein subunit regulatory associated protein of the MTOR complex 1 (RAPTOR), the serine/threonine kinase V-Akt murine thymoma viral oncogene homolog 1 (AKT1), and the protease cathepsin H (CTSH), for which we establish a role in filaggrin expression and processing. Increased RAPTOR levels correlated with decreased filaggrin expression in patients with AD. In keratinocyte cell cultures RAPTOR upregulation or AKT1 short hairpin RNA knockdown reduced expression of the protease CTSH. Skin of CTSH-deficient mice and CTSH short hairpin RNA knockdown keratinocytes showed reduced filaggrin processing, and the mouse had both impaired skin barrier function and a mild proinflammatory phenotype. Conclusion Our findings highlight a novel and potentially treatable signaling axis controlling filaggrin expression and processing that is defective in patients with AD

An Epigenome-Wide Association Study of Total Serum Immunoglobulin E Concentration

Immunoglobulin E (IgE) is a central mediator of allergic (atopic) inflammation. Therapies directed against IgE benefit hay fever1 and allergic asthma1,2. Genetic association studies have not yet identified novel therapeutic targets or pathways underlying IgE regulation3-6. We therefore surveyed epigenetic association between serum IgE concentrations and methylation at loci concentrated in CpG islands (CGI) genome-wide in 95 nuclear pedigrees, using DNA from peripheral blood leukocytes (PBL). We validated positive results in additional families and in subjects from the general population. We show here replicated associations with a meta-analysis false discovery rate <10−4 between IgE and low methylation at 36 loci. Genes annotated to these loci encode known eosinophil products, and also implicate phospholipid inflammatory mediators, specific transcription factors, and mitochondrial proteins. We confirmed that methylation at these loci differed significantly in isolated eosinophils from subjects with and without high IgE levels. The top three loci accounted for 13% of IgE variation in the primary subject panel, explaining 10 fold higher variance than that derived from large SNP GWAS3,4. The study identifies novel therapeutic targets and biomarkers for patient stratification for allergic diseases

Genomic and ecologic characteristics of the airway microbial-mucosal complex

S ummary paragraph Lung diseases due to infection and dysbiosis affect hundreds of millions of people world-wide 1-4 . Microbial communities at the airway mucosal barrier are conserved and highly ordered 5 , reflecting symbiosis and co-evolution with human host factors 6 . Freed of selection to digest nutrients for the host, the airway microbiome underpins cognate management of mucosal immunity and pathogen resistance. We show here the results of the first systematic culture and whole-genome sequencing of the principal airway bacterial species, identifying abundant novel organisms within the genera Streptococcus, Pauljensenia, Neisseria and Gemella . Bacterial genomes were enriched for genes encoding antimicrobial synthesis, adhesion and biofilm formation, immune modulation, iron utilisation, nitrous oxide (NO) metabolism and sphingolipid signalling. RNA-targeting CRISPR elements in some taxa suggest the potential to prevent or treat specific viral infections. Homologues of human RO60 present in Neisseria spp. provide a possible respiratory primer for autoimmunity in systemic lupus erythematosus (SLE) and Sjögren syndrome. We interpret the structure and biogeography of airway microbial communities from clinical surveys in the context of whole-genome content, identifying features of airway dysbiosis that may presage breakdown of homeostasis during acute attacks of asthma and chronic obstructive pulmonary disease (COPD). We match the gene content of isolates to human transcripts and metabolites expressed late in airway epithelial differentiation, identifying pathways that can sustain host interactions with the microbiota. Our results provide a systematic basis for decrypting interactions between commensals, pathogens, and mucosal immunity in lung diseases of global significance

Genome-wide Association Analysis Identifies PDE4D as an Asthma-Susceptibility Gene

Asthma, a chronic airway disease with known heritability, affects more than 300 million people around the world. A genome-wide association (GWA) study of asthma with 359 cases from the Childhood Asthma Management Program (CAMP) and 846 genetically matched controls from the Illumina ICONdb public resource was performed. The strongest region of association seen was on chromosome 5q12 in PDE4D. The phosphodiesterase 4D, cAMP-specific (phosphodiesterase E3 dunce homolog, Drosophila) gene (PDE4D) is a regulator of airway smooth-muscle contractility, and PDE4 inhibitors have been developed as medications for asthma. Allelic p values for top SNPs in this region were 4.3 × 10−07 for rs1588265 and 9.7 × 10−07 for rs1544791. Replications were investigated in ten independent populations with different ethnicities, study designs, and definitions of asthma. In seven white and Hispanic replication populations, two PDE4D SNPs had significant results with p values less than 0.05, and five had results in the same direction as the original population but had p values greater than 0.05. Combined p values for 18,891 white and Hispanic individuals (4,342 cases) in our replication populations were 4.1 × 10−04 for rs1588265 and 9.2 × 10−04 for rs1544791. In three black replication populations, which had different linkage disequilibrium patterns than the other populations, original findings were not replicated. Further study of PDE4D variants might lead to improved understanding of the role of PDE4D in asthma pathophysiology and the efficacy of PDE4 inhibitor medications

Éthique et intégrité scientifique dans la recherche biomédicale. Débats sur la confiance, la robustesse et la pertinence

International audienceBecause it is directly implicated in major social issues, biomedical research is a paradigmatic field for working in ethics to cross-reference epistemic, social, and political issues. This chapter shows that the ethics and scientific integrity of biomedical research has grasped this challenge by placing the transversal concern of trust at the heart of its approach. This question of trust is put into perspective with that of trustworthiness, which is closely linked to it, and which is described as a way of thinking together with the robustness of methods, evidence, results, and the social, ethical, and contextual relevance of trade-offs about them. In a context of increasing media coverage of scientific misconduct and profound changes in the scientific landscape, the ethics of biomedical research thus invites us to take up the complex question of the links between trust and trustworthiness.Parce qu'elle est directement impliquée dans des enjeux sociaux majeurs, la recherche biomédicale est un domaine paradigmatique pour travailler en éthique le croisement des enjeux épistémiques, sociaux et politiques. Cet article montre que l'éthique et l'intégrité scientifique de la recherche biomédicale ont su se saisir de cet enjeu en plaçant la préoccupation transversale de la confiance au cœur de leur démarche. Cette question de la confiance est mise en perspective avec celle de la fiabilité, qui lui est étroitement liée, et décrite comme une manière de penser ensemble la robustesse des méthodes, des preuves, des résultats, et la pertinence sociale, éthique et contextuelle des arbitrage à leur sujet. Dans un contexte de médiatisation croissante des inconduites scientifiques et de profondes mutations du paysage scientifique, l'éthique de la recherche biomédicale nous invite ainsi à nous saisir de la question complexe des liens entre confiance et fiabilité