Oral Bacteria and History of Allergic Disease in Children: A Pilot Study

The purpose of this study is to examine the feasibility of and to establish methods for a future study that will investigate associations between oral bacteria and allergic diseases in children. Rates of allergic diseases such as asthma, hay fever, and eczema have increased in the U.S. over the past several decades. One explanation for those increases is the Hygiene Hypothesis, which contends that decreases in microbial exposures have made the population more reactive to environmental allergens. Reports of protective associations for various infections and exposures to farms, pets, siblings, and day care have provided support for the Hypothesis. Preliminary work by NIEHS researchers suggests that some oral bacterial exposures may be beneficial. NIEHS researchers recently reported that elevated serum antibody concentrations to two common oral pathogens were associated with lower prevalences of asthma, wheeze, and hay fever in the U.S. population. Using a mouse model, NIEHS researchers found that immune responses involved in allergic airway inflammation could be modulated by infection with an oral pathogen. To further investigate these associations in humans, NIEHS researchers, in collaboration with UNC researchers, are planning an observational study that will collect saliva samples from and allergy information on child patients at the UNC-Chapel Hill School of Dentistry. Because we anticipate that several hundred children might have to be enrolled, we are proposing to test methods in a pilot study of 60 children. Twenty children will be recruited from each of three pediatric clinics. A research assistant will obtain the parent's consent and the child's assent and administer a questionnaire to the parent. The child's dentist will collect one teaspoon of saliva by having the child chew a piece of inert wax and spit into a sterile collection cup. Samples will be transported to the NIEHS and analyzed for bacterial species and for allergy-related cytokines. The specific aims for this pilot study are: 1) to identify the most efficient recruitment strategies, 2) to estimate response rates, 3) to estimate the distribution of allergic diseases among the children, 4) to identify any problematic consent form and questionnaire items, 5) to optimize saliva collection and laboratory protocols, and 6) to estimate statistical parameters required for more precise sample size calculations. Information gained from this pilot study will allow us to decide whether a larger study among this clinic population is feasible and to design a more efficient study if we decide to proceed.