Date of Completion

Spring 5-11-2018

Project Advisor(s)

EC Lee, M Urban, C Pilbeam, N Broderick

University Scholar Major

Biological Sciences

Disciplines

Sports Sciences

Abstract

Previous investigations at the Falmouth Road Race (FRR; Falmouth, MA) suggest that combined exercise, heat, and dehydration stress increase circulating lipopolysaccharide, associated binding proteins, and downstream immune signaling. Lipopolysaccharide (LPS), a component of gram-negative bacterial membranes, may be released into circulation from the gut with increased gastrointestinal permeability observed post-exercise. Circulating LPS activates host immune cell signaling that can lead to inflammatory responses that upregulate pro-inflammatory gene expression (eg TNF-α, IL-1β), which if unchecked, may lead to pathophysiology (eg cell pyroptosis, exertional heat stroke (EHS), and sepsis). While subjects of the 2015 FRR (n=30) had elevated core temperature post race (39.87°C) compared to pre (36.87°C, p<0.05), there is unexplained variation in the relationship among the level of circulating LPS (2.90±2.6EU/ml pre vs. 3.48±4.0EU/ml post, p<0.05; Hycult Biotech, ELISA), core temperature, and diagnosis of EHS or exertional heat illness. Since some strains of bacteria induce a strong immune response while others do not, we aimed to determine if structural variations in LPS contribute to varying immune system activation during exercise-heat stress. We utilized extraction of LPS from pre-race and post-race plasma and FTIR spectroscopy to characterize structural variations in LPS in individuals of the 2015 and 2017 FRR, and conclude that other methods of analysis may be appropriate to fully understanding this relationship. Acknowledging the diversity of circulating LPS will be critical to answering fundamental questions about EHS pathophysiology and the interaction between gut health and exercise in stressful environments, as this approach has never been taken to examine whether structural variants may explain some of the variability in literature around LPS post exercise and as a potential biomarker for EHS.

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