UC Davis

The microbiome, the collection of the different microorganisms living in the human body, is a topic that connects the realms of disease, development, health, and forensics. The microbial communities within the human body are influenced by a variety of factors including, medical history, physiology, diet, hygiene, and other behaviors. Like a fingerprint, each person’s microbiome is unique. In individuals who are immunocompromised, the microbiome can become imbalanced since bacterial colonies directly interact with an individual’s immune system. The immune system therefore plays an important role in establishing the content of the microbiome. This relationship between the immune system and the microbiome continues post-mortem. After an individual dies, the subsequent death of immune cells allows the bacteria that make up the microbiome to expand. This bacterial expansion triggers decomposition active decay. Because of the predictable role of the microbiome in decomposition, measuring microbial succession has shown great promise in helping to estimate a more accurate post-mortem interval (PMI). Although progress has been made in refining microbe-based calculations of PMI, immune system function at the time of death has not been closely examined as a factor that can impact the postmortem microbial succession estimation. The goal of this study is to explore the pattern of postmortem immune cell death, and how the death of immune cells impairs the accuracy of estimating PMI. Viability of intestinal immune cell subsets at different post mortem intervals were analyzed so that future studies can analyze how immune cell survival impacts bacterial succession. Ultimately, the goal of this research is to illuminate how immune status at the time of death can impact post-mortem microbial succession.