Biodiversity, microbiota, and childhood allergies and asthma: variation across space and time.

An increasing number of studies (including studies conducted here at CPHR/RCHH) show that proximity to a natural environment may protect against asthma and allergies. Although the reasons for this aren’t clear, the “Biodiversity Hypothesis” (which is similar to the “Hygiene Hypothesis”) suggests that it may be because reduced biodiversity (through urbanisation) has led to changes in environmental and human microbiota, which, in turn, has increased the risk of allergic conditions.

 We know that our microbiota affect immunity, and that changes in gut microbiota may be associated with both development of, and protection from allergies/asthma. However, the pathways involved are largely unknown. The assumption that biodiversity loss leads to reduced microbial exposure and increased disease risk has only recently begun to be tested, and the complex interactions between plant diversity, environmental and human microbiota, immunity, and disease, remain unclear.

 This research programme consists of three complementary studies specifically exploring the role of biodiversity in the causation and prevention of asthma and allergy. These studies will:

1) build on another study of urban school children examining plant diversity and risk of allergy and asthma, and assess interactions between plant diversity and environmental and human microbiota;

2) develop a cohort study of infants (6-24 months) recruited from day-care centres in urban and rural areas (with different levels of exposure to plant diversity) to assess links across plant diversity, gut microbiota, and allergies in early life; and

3) building on an international study, assess associations between gut microbiota, airway microbiota and asthma phenotypes across high- and low/middle-income countries.  

 The overall aim is to increase our understanding of the modifiable causes and mechanisms of allergies and asthma, which will allow the development of new approaches to interventions and community-based prevention strategie