title: Aberrant IgA responses to the gut microbiota during infancy precede asthma and allergy development.
abstract: BACKGROUND
  Although a reduced gut microbiota diversity and low mucosal total IgA levels in infancy have been associated with allergy development, IgA responses to the gut microbiota have not yet been studied.
  
  
  OBJECTIVE
  We sought to determine the proportions of IgA coating together with the characterization of the dominant bacteria, bound to IgA or not, in infant stool samples in relation to allergy development.
  
  
  METHODS
  A combination of flow cytometric cell sorting and deep sequencing of the 16S rDNA gene was used to characterize the bacterial recognition patterns by IgA in stool samples collected at 1 and 12 months of age from children staying healthy or having allergic symptoms up to 7 years of age.
  
  
  RESULTS
  The children with allergic manifestations, particularly asthma, during childhood had a lower proportion of IgA bound to fecal bacteria at 12 months of age compared with healthy children. These alterations cannot be attributed to differences in IgA levels or bacterial load between the 2 groups. Moreover, the bacterial targets of early IgA responses (including coating of the Bacteroides genus), as well as IgA recognition patterns, differed between healthy children and children with allergic manifestations. Altered IgA recognition patterns in children with allergy were observed already at 1 month of age, when the IgA antibodies are predominantly maternally derived in breast-fed children.
  
  
  CONCLUSIONS
  An aberrant IgA responsiveness to the gut microbiota during infancy precedes asthma and allergy development, possibly indicating an impaired mucosal barrier function in allergic children.
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Autoimmunity and Immune Regulation, Linköping University, Linköping, Sweden; Department of Health and Genomics, FISABIO Foundation, Center for Advanced Research in Public Health, Valencia, Spain; Institute of Agrochemistry and Food Technology, Spanish National Research Council (IATA-CSIC), Department of Biotechnology, Unit of Lactic Acid Bacteria and Probiotics, Valencia, Spain.
authors.forename: Majda
authors.initials: M
authors.lastname: Dzidic
authors.affiliation: Department of Clinical and Experimental Medicine, Division of Paediatrics, Linköping University, Linköping, Sweden.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Abrahamsson
authors.affiliation: Department of Health and Genomics, FISABIO Foundation, Center for Advanced Research in Public Health, Valencia, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Artacho
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Björkstén
authors.affiliation: Institute of Agrochemistry and Food Technology, Spanish National Research Council (IATA-CSIC), Department of Biotechnology, Unit of Lactic Acid Bacteria and Probiotics, Valencia, Spain.
authors.forename: Maria Carmen
authors.initials: MC
authors.lastname: Collado
authors.affiliation: Department of Health and Genomics, FISABIO Foundation, Center for Advanced Research in Public Health, Valencia, Spain. Electronic address: mira_ale@gva.es.
authors.forename: Alex
authors.initials: A
authors.lastname: Mira
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Autoimmunity and Immune Regulation, Linköping University, Linköping, Sweden. Electronic address: maria.jenmalm@liu.se.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Jenmalm
mesh_terms: D001419:Bacteria / Q000302:isolation & purification; D058491:Bacterial Load; D002648:Child; D002675:Child, Preschool; D005243:Feces / Q000382:microbiology*; D005260:Female; D000069196:Gastrointestinal Microbiome; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology* / Q000382:microbiology*; D007070:Immunoglobulin A / Q000276:immunology*; D007223:Infant; D008297:Male
chemical_list: D007070:Immunoglobulin A
keywords: Allergic disease; IgA index; IgA recognition patterns; asthma; childhood; gut microbiota; microbiome composition; secretory IgA