Beating childhood allergies with the great outdoors

According to a 2019 report in The Straits Times, childhood eczema is on the rise in Singapore. Emerging principal investigator at the Singapore Institute for Clinical Sciences (SICS) and mother of two, Dr Evelyn Loo, reveals that the great outdoors may hold the key to preventing such allergies in little ones.

Kids at the playground

A large number of studies – such as the International Study of Asthma and Allergies in Childhood (ISAAC) – shows a growing prevalence of allergic diseases such as asthma, allergic rhinitis, eczema and food allergies worldwide. However, the significant variation in the prevalence of these diseases between the East and the West (Western countries generally have higher rates of allergic diseases than Asian countries although these diseases have been increasing in the Asia Pacific region in recent years) suggest that there may be location-specific factors such as environment, lifestyle, and microbial exposure affecting allergic disease prevalence.

Eczema on the rise
Based on a report in The Straits Times on 30 June 2019, one in five school-going children in Singapore has atopic dermatitis, the most common form of eczema – and doctors interviewed said that the number of cases could rise further. This could be due to urbanisation and an increase in socioeconomic status where there is decreased exposure to environmental microbes due to better living conditions. Interestingly, it's also been found that allergic disease rates are higher in boys (based on literature in the field).

The first manifestation of the atopic march and allergic phenotype typically starts with eczema. The skin is the primary interface with the external environment and is largely influenced by the biodiversity of the external environment. Skin microbiota not only play a pivotal role in growth, homeostatic regulation and development of keratinocytes, but also affect host immunity. Hence, factors that affect the composition of the skin microbiome not only influence the risk of cutaneous disease but also other inflammatory non-communicable diseases.

Through studies under GUSTO – Singapore’s largest birth cohort study – we’ve found a distinct and different microbial profile between different collection sites as well as between houses of subjects with and without eczema. The results show that constant exposure to human-associated bacteria with proinflammatory roles over critical periods, such as preconception, pregnancy and early postnatal period within the first year of life, are associated with the development of eczema in offspring while environmental microbiota exposure prevents the development of eczema.

Head out for protection
Evidence indicates that microbial environment within the early life window, pregnancy and postnatally during the first years of life, is key in determining allergy predisposition/risk. It is possible that the microbial environment we are exposed to in early life is instrumental in shaping a robust immunity, possibly through modulation of the human microbiome (skin, gut and airway).

Findings from our cohort studies also show that exposure to a diversity of microbes in early life is important in preventing allergy, therefore it is advisable for children – especially those at risk – to head outdoors. Bring your children to parks and nature reserves frequently, so as to expose them to protective environmental bacteria.

By evaluating the effect of environmental microbiota on host microbiota and immunity, we hope that we will be able to pave the way for intervention studies where environmental exposure can be modified via lifestyle changes, probiotic therapy, sprays, skin patches, and more. Given that we can’t change our genetic makeup, environmental factors are important in disease prevention as they are potentially modifiable.

Dr Evelyn Loo's research interests include the study of epidemiology of a child's health, as well as identifying critical periods where environmental microbiome can exert the most influence and factors that can affect environmental microbiome. Armed with a better understanding of the interactions between environmental microbiome and allergens, Dr Loo hopes that her research will be useful in the implementation of strategies to prevent childhood diseases such as eczema.