Slide 1 Pro/Con: Pets Prevent Allergies and Asthma
Slide 2 Special thanks to: n Dr. Dennis Ownby n Dr. Matt Perzanowski n Dr. Erica von Mutius and Dr. Charlotte Braun-Fahrlander n Dr. Andy Liu n Colleagues and participants from the Epidemiology of Home Allergens and Asthma Study
Slide 3 WHO definition of prevention of allergic diseases Primary prevention: Prevention of immunological sensitization (IgE antibodies) Secondary prevention: Prevention of developing an allergic disease (e.g. atopic dermatitis, allergic rhinitis, allergic asthma) Tertiary prevention: Treatment of asthma and allergic disease. Genetically predisposed individual Allergic sensitization Allergic asthma Exacerbation of asthma symptoms Allergen exposure Prevention of Allergy and Allergic Asthma. World Health Organization, 2003.
Slide 4 Primary Prevention: Doctor, I m pregnant Should I get a pet to protect my child from allergy? Should it be a dog or a cat? Or, should I give our pet a new home?
Slide 5 Primary or Secondary Prevention: I want to protect my baby from allergy Should I get a cat? Or not
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Slide 7 Meta-analysis of Farm & Pet Exposure vs Allergy Risk: Pets OR = 0.83 CI 0.73-0.96 Tse K, Horner AJ. Seminar Immunopath 2008;30:53-62
Slide 8 Representative (confusing) prospective studies: Responses to pets vary: should these study results be averaged? >2 cats/dogs = less allergy, tal IgE association among kids with family history of asthma Cats protective against wheeze for children without maternal asthma Cat increase risk of wheeze for children with maternal asthma Cats protect against asthma incidence, but only among child with family history of asthma
Slide 9 Plos One 2012;7:e43214
Slide 10 Another recent systematic review Perinatal Cat and Dog Exposure and the Risk of Asthma and Allergy in the Urban Environment: A Systemic Review of Longitudinal Studies Conclusion: perinatal pets, especially dogs, may reduce the development of allergic disease in those without a family history of allergy. But how does that inform clinical guidelines? Lodge et al Clinical Developmental Immunology 2012: 176484
Slide 11 Biologic plausibility n Pets = intense allergen exposure n Pets = bacteria, viruses, parasites = hygiene hypothesis n Pets = altered human microbiome
Slide 12 Do Pets Alter Home Dust Microbiome n 337 bacterial taxa significantly increased in dogowning homes Proteobacteria (112 taxa) Actinobacteria (63 taxa) Firmicutes (47 taxa) Bacteroidetes (41 taxa) Spirochaetes (22 taxa) Verrucomicrobia (7 taxa) These are phyla common in the human gastrointestinal tract Endotoxin is a marker for gram negative bacteria, and may have a functional role in protection against allergy But. Fujimura KE, et al. J Allergy Clin Immunol 2010;126:410-412
Slide 13 Intestinal bacteria are essential for immune maturation (Maynard et al. Nature 2012)
Slide 14 Endotoxin: Friend & Foe? Endotoxin IL-12 Th1 Treg IFN-!" IL-10 Atopy Inflammation Remodeling Allergy Asthma timing dosage environmental co-factors genetics Th2 IL-4 IL-5 IL-13 Atopy Inflammation Remodeling Allergy Asthma Endotoxin - Liu AH. JACI, 109:379-392, 2002.!
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Slide 16 n Why Pet Exposure is Not Like Smoking Exposure Pets can be good, bad or indifferent Parental smoking is never good for the child, though the extent to which smoking is bad for risk of early-life respiratory illness, wheeze and asthma development may vary n How Pet Exposure is Similar to Smoking Exposure They both represent a mix of a variety of exposures
Slide 17 n What is pet exposure? Allergen exposure Inhaled and ingested microbial exposure Exposure to support or stress (bites) Exercise Conclusions n Early-life pet exposure is probably associated with asthma onset n The evidence for the direction of the association (beneficial, risk factor, no association) varies, and it varies more for cat than for dog ownership.
Slide 18 Conclusions n Variability in response to pet allergens or microbes likely depends on Dose from pet in the home Timing of exposure Inheritance Background dose of pet allergen in the community The microbial organisms that the pet carries Unmeasured or measured cofactors influencing susceptibility to allergy, airway inflammation, airway irritability and asthma
Slide 19 Conclusions n Enough studies have been done on the relation of pet ownership in pregnancy/early life and allergy/ asthma development n To advance Primary Prevention, more research is needed: About the cofactors influencing response to pets About the influences of the microbial flora of pets on: Gastrointestinal flora development of children Immune development
Slide 20 Conclusions n We know that asthma + pet allergy + pet in the home = reduced asthma control n Decisions about pet ownership during pregnancy and the early life of the child should be made on the basis of: Pet allergies with clinical significance amongst those in the household (tertiary prevention needs). Personal preference love of or fear of pets Time and resources to care for the pet Housing regulations about pet ownership
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