title: Strategies to alter the natural history of childhood asthma.
abstract: OBJECTIVE
  Asthma exhibits significant heterogeneity in occurrence and severity over the lifespan. Our goal is to discuss recent evidence regarding determinants of the natural history of asthma during childhood, and review the rationale behind and status of major efforts to alter its course.
  
  
  RESULTS
  Variations in microbial exposures are associated with risk of allergic disease, and the use of bacterial lysates may be a promising preventive strategy. Exposure to air pollution appears to be particularly damaging in prenatal and early life, and interventions to reduce pollution are feasible and result in clinical benefit. E-cigarette use may have a role in harm reduction for conventional cigarette smokers with asthma, but has undefined short-term and long-term effects that must be clarified. Vitamin D insufficiency over the first several years of life is associated with risk of asthma, and vitamin D supplementation reduces the risk of severe exacerbations.
  
  
  CONCLUSIONS
  The identification of risk factors for asthma occurrence, persistence and severity will continue to guide efforts to alter the natural history of the disease. We have reviewed several promising strategies that are currently under investigation. Vitamin D supplementation and air pollution reduction have been shown to be effective strategies and warrant increased investigation and implementation.
authors.affiliation: aDivision of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts bDivision of Pediatric Allergy, Immunology and Pulmonary Medicine, Department of Pediatrics, Washington University School of Medicine cSt Louis Children's Hospital, St Louis, Missouri dChanning Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Lee-Sarwar
authors.forename: L B
authors.initials: LB
authors.lastname: Bacharier
authors.forename: A A
authors.initials: AA
authors.lastname: Litonjua
mesh_terms: D000397:Air Pollution / Q000009:adverse effects; D000818:Animals; D001249:Asthma / Q000453:epidemiology* / Q000517:prevention & control; D001424:Bacterial Infections / Q000453:epidemiology*; D002648:Child; D066300:Electronic Nicotine Delivery Systems; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D018811:Maternal Exposure / Q000009:adverse effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology* / Q000517:prevention & control; D012306:Risk; D012907:Smoking / Q000009:adverse effects; D014807:Vitamin D
chemical_list: D014807:Vitamin D