Skip to main content
Dr. Jack Gilbert

Your Microbiome and You: Promising Applications to Precision Health

Thalia Hua, MSc, Translational Medicine

At this week’s Medical Grand Rounds, the Department of Medicine had the pleasure of welcoming Dr. Jack Gilbert as a guest speaker from the University of California San Diego. Dr. Gilbert previously completed his post-doctoral training at Queen’s University in biochemistry and is currently appointed as a Professor in Pediatrics at the Scripps Institution of Oceanography. Coming from a diverse academic background, Dr. Gilbert showcased the importance of microbial ecology in human disease, specifically highlighting how the understanding of these ecosystems will lead us to the discovery of novel mechanisms for targeted patient therapy.


The human microbiome can be described as a collection of microorganisms that reside in a specific environment found in and around the body. These 40 trillion microbes (including those of bacterial, viral, and fungal origins) can be found distributed amongst a variety of sources such as oral, nasal, and vaginal cavities. Interestingly, the majority of these organisms are found in the gastrointestinal tract (specifically the colon), with a staggering ratio of 100 microbial genes for every human gene. Dr. Gilbert emphasized that the term “diversity” alone is not indicative of any particular health state, rather a balance of microbial function, which is commonly a result of a diverse selection of microorganisms, provides a better measure of one’s health status.


To this date, there are no two individuals that have been deemed “microbial doppelgängers”. Anything from diet, hours of sleep, to method of delivery at birth can affect the composition of the microbiome. Due to the significant variation between each individual, Dr. Gilbert highlighted the value of microbiome-wide association studies (MWAS) to better understand how we can link a complicated collection of microbes to an equally complicated collection of diseases. To accomplish this, MWAS specifically focuses on finding associations between microbes and disease variants. These associations can then be used to identify mechanistic pathways in hopes of finding biomarkers to act as novel disease targets.


Under the appropriate conditions set by our immune system, Dr. Gilbert explained that microbes release metabolites that are essential for human growth and development. This includes certain amino acids that are otherwise not metabolized by humans cells alone. In relation to this, Dr. Gilbert brought up the prevalence of neurological issues and stunted growth in Ghanaian and Jamaican children as a result of protein malnutrition. Researchers recently revealed that the consumption of cellulose can stimulate bacteria to increase their productivity and upregulate the production of these essential amino acids. Therefore, prescribing cellulose as a form of treatment for this population is highly feasible and is one of the many examples that showcase the translational applications of microbiota research.


With increasing use of antibiotics in modern society, Dr. Gilbert highlighted the importance of rich microbial sources in our environment through his research in the Amish and the Hutterites – two U.S agricultural populations with strikingly different rates of asthma. What Dr. Gilbert describes as “magic Amish dust” was found to be comprised of significant amounts of allergens and bacteria compared to the Hutterite house dust. The Amish house dust was found to elicit protective effects against asthma to the children by reducing levels of inflammatory immune cells in the respiratory tract, despite the two populations sharing similar genetic profiles. Dr. Gilbert explained that the rich microbial diversity found in the Amish house dust offered a source of training material for the children’s immune system to defend against. As a result, the Amish children had the opportunity to strengthen their immunological responses at an early age, allowing them to be resilient and prepared to fight against future diseases they encounter. Therefore, Dr. Gilbert’s research suggests that our new obsession to prevent certain diseases through excessive cleanliness may actually be the source of developing alternative diseases in return.


In our post-round discussion, Dr. Gilbert emphasized the importance of multidisciplinary collaboration in the field of academic research. Our understanding of the microbiome would have been impossible without acknowledging the critical relationships of these microbes to the intricate mechanisms of the human body. In order to improve the wellbeing of patients, researchers must be able to apply their findings in the context of the entire body because at the end of the day, scientific research is only as good as the sum of its parts.


On behalf of Queen’s University and the Translational Medicine graduate program, we thank Dr. Gilbert for sharing his academic experiences and valuable research insights of the microbiome.