2026 USA winner

Exposure to traumatic events is extremely common, and some people develop posttraumatic stress disorder (PTSD), a condition affecting mental and physical health, including the heart and cardiovascular system. Women are particularly vulnerable: they are more likely to develop PTSD after trauma and face greater risk of related heart disease compared to men. One underexplored explanation for this vulnerability involves the gut microbiome: bacteria and other microorganisms living in our digestive tract that influence immunity, metabolism, and brain function. Research suggests that traumatic stress disrupts these gut bacteria, which in turn may drive inflammation and harm cardiovascular health. A key molecule in this process is arginine, an amino acid that gut bacteria help produce and that plays a critical role in regulating blood vessel function, blood pressure, and immune responses. When arginine levels are low, cardiovascular risk increases.

This proposed project examines whether women with PTSD have disruptions in the gut bacteria responsible for arginine processing, whether these disruptions lead to lower arginine levels in the bloodstream, and whether reduced arginine availability contributes to measurable signs of cardiovascular dysfunction, such as elevated blood pressure, reduced heart rate variability, and stiffer blood vessels. By analyzing stool samples, blood samples, and cardiovascular measurements from 50 women (25 with PTSD, 25 healthy controls), this project aims to uncover a previously unrecognized biological pathway connecting trauma, gut health, and heart disease, laying the foundation toward greater understanding of the gut microbiome’s role in influencing chronic disease risk in trauma-related disorders and toward new treatment targets.

Questions to Therese Rajasekera

What inspired you to pursue this specific research project?

Posttraumatic stress disorder is increasingly understood as a psychiatric condition with sex-specific physical health consequences. Thus, this project is inspired by our desire to understand why women with trauma-related disorders are more susceptible to certain adverse cardiovascular events. The gut microbiome and its metabolic activity are an underexplored mechanism which may confer this vulnerability, particularly gut bacteria-produced metabolites which also influence blood pressure and blood vessel function. As such, this project seeks to lay the foundation for improving our understanding of the gut microbiome's role in shaping cardiovascular disease risk in women with trauma-related disorders. 

How will the Biocodex Microbiota Foundation Grant support contribute to the success and advancement of your research?

Broadly, I am passionate about uncovering how our body’s microbial communities influence health, especially women’s mental health outcomes. Understanding these communities' roles in modulating inflammatory processes that contribute to stress-related psychiatric disorders will provide a foundation for identifying novel biomarkers predictive of mental health risk and resilience. The Biocodex Microbiota Foundation's support moves us closer to this goal. This grant facilitates a novel and creative line of inquiry that will enable subsequent larger, more comprehensive assessments of the gut microbiota-linked mechanisms underlying cardiovascular disease risk in trauma-related disorders, including identification of therapeutic targets.