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Risk Factors for Recurrent Wheezing in Children:

Risk Factors for Recurrent Wheezing in Children:. Allergens. Dennis R. Ownby, MD Chief, Division of Allergy, Immunology, Rheumatology Georgia Health Sciences University Augusta, GA, USA. In the past year I have been: A consultant to CarboNix, LLC

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Risk Factors for Recurrent Wheezing in Children:

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  1. Risk Factors for Recurrent Wheezing in Children: Allergens Dennis R. Ownby, MD Chief, Division of Allergy, Immunology, Rheumatology Georgia Health Sciences University Augusta, GA, USA

  2. In the past year I have been: A consultant to CarboNix, LLC Advisory board, Merck Childhood Asthma Network No discussion of off label drug use Research Support: National Institutes of Health Legal Fees: None Gifts: None Disclosures

  3. Concepts to Explore • Does allergen exposure promote or allow allergic disease • Is exposure to some allergens typically associated with exposure to some other immunomodulatory influence

  4. Accepted Knowledge • Most children with asthma are sensitized to allergens • Strong association between allergic sensitization and persistence of asthma • Stronger association between sensitization to perennial allergens and asthma than seasonal allergens

  5. Early Allergen Sensitization and Chronic Asthma in Children • German MAS Study • 1314 children: birth to 13 years of age • Allergen exposure at 6 & 18 months and at 3, 4, 5 years • Lung function at 7, 10 ,13 years • IgE’s at 1, 2, 3, 5, 6, 7 and 10 years Illi S, et al. Lancet 2006;368:763-770

  6. Prevalence of Current Wheezing: Birth to 13 Years Non-atopic, n=94 Atopic, n=59 at school age Illi S, et al. Lancet 2006;368:763-770

  7. Effect of Sensitization at ≤ 3 Years and Lung Function at 13 Years of Age NS = not sensitized S/LE = sensitized to dust mite ± cat, low exposure at 3 and 5 years S/HE = sensitized to dust mite ± cat, high exposure at 3 and 5 years Illi S, et al. Lancet 2006;368:763-770

  8. Dust mite allergen exposure: the first allergen though to “cause” the development of asthma.

  9. Mite Allergen Exposure and Disease • Dust mites: sensitization at 2-10 μg/g of dust in most studies • For nonallergic children higher “threshold” of 20 μg/g • Mite allergen consistently related to asthma in many countries • Mite allergen related to rhinitis and atopic dermatitis, anaphylaxis from ingestion • Actual daily “dose” of allergen unknown

  10. Previous Findings • Sporik et al, NEJM 1990 RR = 4.8 for asthma at age 11 associated with Der p 1>10 μg/g dust at 1-2 yrs • Burr et al, Arch Dis Child 1993 No association between dust mite levels at 1 yr and wheeze or atopy or +ST to mites at 7 yrs • Lau et al, Lancet 2000 No association between dust mite levels in infancy and asthma at 7 yrs • Johnson et al, J Allergy Clin Immunol 2004 No association between dust mite levels in infancy and seroatopy, atopy or asthma at 6-7 yrs

  11. Dust Mite Exposure and Wheezing in MAS = 1st quartile of dust mite at 6 months of age = 4th quartile of dust mite at 6 months of age Lau S, et al. Paediatric Resp Rev 2002;3:265-272

  12. Childhood Allergy Study (CAS) • 835 middle-class children living in suburbs of Detroit, MI, recruited at birth • Selected by geographic area of residence, not selected for allergic risk factors • Yearly questionnaires concerning home environment and home visits at 2 & 4 years • Evaluation between 6 & 7 years for asthma and allergy Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  13. Clinical Evaluation at 6 – 7 Years • Medical history and physical examination • Skin puncture tests: mites (D. farinae, D. pteronyssinus), Phleum pratense, Ambrosia artemisiifolia, cat, and dog • Specific IgE to same allergens plus Alternaria alternata (DPC AlaSTAT) • Total IgE (DPC AlaSTAT) • Spirometry and methacholine challenge • 474 children completed study Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  14. CAS Exposure Variables • Clinical diagnoses of infection from medical records • Upper respiratory infections, URI (otitis media, cough, croup, rhinitis, viral syndrome, etc) • Lower respiratory infections, LRI (bronchitis, pneumonia, wheezing, etc) • Day care exposure • Number of older siblings Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  15. Examined Children (n=480) • Age, years 6.72 range 6.1- 7.7 • Girls:boys 242:232 1.04:1 • Atopic 165/470 34.4% • Seroatopic 147/407 36.1% • +BHR 105/462 22.7% • Ever Asthma 45/427 10.5% • Current Asthma 33/473 7.0% • Current Atopic Asthma 25/473 5.2% Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  16. Outcomes by Dust Mite Allergen > 10μg/gm* All Children VariableOR95% CIP-value +DM SPT 1.09 0.58-2.06 0.78 +DM IgE 1.19 0.57-2.50 0.64 Atopy 1.13 0.66-1.94 0.66 Seroatopy 1.02 0.58-1.81 0.93 +BHR 0.53 0.27-1.04 0.07 Asthma 0.68 0.27-1.70 0.41 Current Atopic Asthma 0.74 0.21-2.62 0.64 *adjusted for gender, firstborn status, cord blood IgE, parental education and history of allergies and asthma, and early exposure to household cats or dogs, tobacco smoke or daycare. Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  17. Outcomes by Dust Mite Allergen > 10 μg/gm for Children with No Family History* VariableOR95% CIP-value +DM SPT 0.40 0.13-1.19 0.100 +DM IgE 0.53 0.16-1.79 0.308 Atopy 0.69 0.29-1.62 0.392 Seroatopy 0.62 0.26-1.49 0.286 +BHR 0.62 0.26-1.49 0.285 Asthma 2.80 0.66-11.9 0.163 Current Atopic Asthma 1.52 0.22-10.6 0.67 *adjusted for gender, firstborn status, cord blood IgE, parental education, early exposure to household cats or dogs, tobacco smoke or daycare. Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  18. Outcomes by Dust Mite Allergen > 10 μg/gm for Children with a Positive Family History* VariableOR95% CIP-value +DM SPT 2.09 0.93-4.73 0.076 +DM IgE 2.08 0.77-5.61 0.150 Atopy 1.72 0.83-3.59 0.147 Seroatopy 1.73 0.77-3.87 0.182 +BHR 0.46 0.15-1.41 0.175 Asthma 0.27 0.03-2.12 0.212 Current Atopic Asthma 0.39 0.05-3.13 0.376 *adjusted for gender, firstborn status, cord blood IgE, parental education, early exposure to household cats or dogs, tobacco smoke or daycare. Johnson CC, et al. J Allergy Clin Immunol 2004;114:105-10

  19. Multivariable Models Predicting Allergic Sensitization at 6-7 Years Specific IgE +Skin Prick Test

  20. Land of Low Allergen Exposure • 161 Kuwaity children, 9-16 years with asthma and 303 healthy controls • Few pets in homes for religious reasons • Dry climate • relative humid low, 15%-30% • low levels of dust mites Hassan MS et al. J Allergy Clin Immunol 2004;114:1389-94

  21. Land of Low Allergen Exposure • Allergen levels in 383 mattresses • Der p 1, 99.7% below detection • Der f 1, 98.1% below detection • Fel d 1, 15.2% below detection, median 0.14 • Can f 1, 83.4% below detection • Bla g 1, 51.9% below detection, median 0.05 • Cat ownership: 4.1% • Dog ownership: 1.5% Hassan MS et al. J Allergy Clin Immunol 2004;114:1389-94

  22. Land of Low Allergen Exposure Allergen Asthma Control Skin test 158 303 Dust mites 31 (20%) 13 (4%) Cat 73 (46%) 46 (15%) Dog 55 (35%) 31 (10%) Hassan MS et al. J Allergy Clin Immunol 2004;114:1389-94

  23. Pets Contribute More than Allergens to Homes • 18 house dust samples from WHEALS • 6 ≥ 1 dogs, 6 ≥ 1 cat, 6 without pets • PhyloChip analysis of microbial taxa present • Insufficient DNA in 2 dust samples • Homes with dogs • More types of bacteria present, richer, p < .04 • More diverse, p < .04 Fujimura KE, et al. J Allergy Clin Immunol 2010;126:410-412

  24. Bacterial Communities in House Dust from Dog verses No-Pet Households Fujimura KE, et al. J Allergy Clin Immunol 2010;126:410-412

  25. Pets Alter Home Dust Microbiome • 337 bacterial taxa significantly increased in dog-owning 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 Fujimura KE, et al. J Allergy Clin Immunol 2010;126:410-412

  26. Movement of Bacteria from House Dust to Infant Gut • Hand-to-mouth activity • Well studied by toxicologists • Studies demonstrate that hand-to-mouth activity relates dust and infant concentrations of toxins

  27. Soil and House Dust Ingestion by Children U.S. EPA. Child Specific Exposure Factors Handbook 2008 Soil and dust ingestion directly related to hand to mouth and object to mouth activity in children Hand to mouth activity is highly variable in children and varies indoors and outdoors Average dust ingestion is 30–100 mg/day for children 6 months – 11 years of age Pica (ingestion of large quantities of soil ~5 gm/day) is relatively common in children

  28. Multi-center European study (PARSIFAL) 14,893 children 5-13 years-of-age Farm milk inversely associated with asthma, adjOR = 0.74 (95% CI 0.61-0.88) Rhinoconjunctivitis, sensitization to pollen and food mixes also significantly inversely associated with farm milk Role of Unpasteurized Milk Waser M, et al. Clinical Exp Allergy 2006;37:661-670

  29. 563 children, 7-16 years, living in Finnish- and Russian-Karelia Skin prick tested with 14 common allergens and foods Finnish children significantly more sensitization – 48% vs 16% Multivariable analysis – sex, cat < 1 yr, density of microbes in water Drinking Water Microbes and Atopy Von Hertzen L, et al. Allergy 2007;62:288-292

  30. Does Pet Ownership Impact House Dust and Stool Microbiota? Lynch S, et al. unpublished

  31. Conclusions • Exposure to allergens allows predisposed persons to become sensitized by exposure dose not change the person’s predisposition • Exposures to allergens are often associated with exposures to other agents which alter immune responses • Microbes ingested by children in infancy have strong effects on the risk of developing allergic sensitivity and disease

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