Yuan Gao

Yuan Gao’s PhD research at Deakin focused on investigating the relationship between maternal gut microbiome during pregnancy and infant food allergy in early life.

Why did you decide to do a PhD?

I had been working in the microbiome industry for three years before I decided to start my PhD. I was trained to perform streamlined analyses, but never completely understood the theory. That made the interpretation of the findings a huge challenge to me, not to mention to convert medical basis into practical use. I realised I needed systematic education on the aspects ranging from study design, statistics, to critical thinking, to acquire the ability to complete the medical research on my own. Fortunately, I was introduced to my supervisor, Professor Peter Vuillermin from Deakin University, who is a paediatrician and Director of Research at Barwon Health, and Professor Hanne Frøkiær from the University of Copenhagen. Peter is also one of the leaders in assembling the Barwon Infant Study (BIS) cohort, on which my PhD project was mostly based. I knew that I would be able to access all the resources in both universities as a joint PhD student, as well as learn all the research skills from both groups.

What support did Deakin and your supervisor provide during your PhD journey?

I received a stipend from Deakin during my PhD, which covered most of my living costs, enabling me to focus on my studies. Deakin also offered travel grants for conference attendance where I presented my work and learnt from experts from other fields.

My supervisor, Peter Vuillermin has always been supportive and encouraging. Due to the COVID pandemic, the BIS samples were not sequenced in time, so I was way behind schedule. In the last year of my PhD, I just started my last project. Even with the tight schedule looming over us, Peter still believed in me and offered me all the data and support needed. After we completed the last project in my thesis, I was reluctant and afraid to present in public. He encouraged me, “in order to overcome galeophobia, you have to face the shark!” I ended up winning the 2022 Best Research Paper of the Year at Barwon Health and Deakin University with a presentation. He triggers my enthusiasm for science and makes me believe that I can make a difference to the world.

How is your research linked to industry?

We recently found that babies with older siblings had a much more mature gut microbiome by one year of age, which further reduced the risk of food allergy. There is an increasing incidence of childhood food allergy in the last decade, especially in industrialised countries. In Australia, around one in every 10 babies develops food allergies, which is the highest rate in the world. Understanding the basis of the protective effect of older siblings on food allergy may not only inform the potential treatment, but also prevention strategies for more susceptible children from developing allergies in early life.

Did you complete an internship during your PhD?

I was supposed to spend at least six months at the University of Copenhagen. However, due to the COVID pandemic, I was unable to travel to Denmark. So, I took an internship at Walter and Eliza Hall Institute (WEHI) of Medical Research in Melbourne with Professor Leonard Harrison and his team. That experience made the last stage of my PhD journey quite busy but extremely enjoyable and fruitful. The WEHI team have also been working on a birth cohort, which has a similar structure to the BIS cohort. However, their works were based on the next-generation type of microbiome data, from which I have gained analysis skills that can be applied in my PhD study and future works.

What impact will your research work have on the world?

The association between larger household size and decreased risk of allergic disease was first described over 30 years ago and formed the basis of the hygiene hypothesis. Although the association between larger household size and or greater sibling numbers and decreased allergic disease has been replicated in more than 20 studies, the underlying mechanism remains unknown. For the first time, we found in BIS that around 63% of the protective effect of increased sibling numbers on allergic outcomes was mediated by accelerated maturation of the infant’s gut microbiota during the second six months of infancy. Humans harbour thousands and thousands of microbes. What we found suggests that the function of the gut microbiota is possibly conveyed by the whole rather than a single taxon, drawing attention to the entire gut microbiota for further studies.

What’s next? Where do you hope your PhD will take you?

I will continue to work in the health industry as a research fellow with both Deakin University and WEHI. With all the available resources at both institutes, I will continue to investigate whether the maturation of the gut microbiota during infancy is associated with other allergic outcomes and asthma, and investigate the underlying basis of the gut microbiota maturity. The goal is to convert these findings into guidelines or strategies for the public to protect children from allergic diseases and asthma in early life.