Carbon-14-Labeled Microbes to Track the Fates of Microbial Metabolites: A Potential Technical Approach to Define the Gut-Brain Axis in Animal Models

Doris Lam | 22-FS-002

Project Overview

To date, there is no direct method to monitor the physiological cross talk between the gut and brain despite the availability of both animal model and experimental tools (e.g., germ-free mice, antibiotic treatments) (Kennedy, King, and Baldridge 2018). Instead, the indirect approach typically employed relies on the analysis of metabolite expression in biological samples (feces, plasma, cerebral spinal fluid, and tissue) in clinical and rodent specimens. However, this approach is often confounded by other components, specifically immune and endocrine modulators, within the interactive network of the gut-brain axis. In this project, we evaluate whether we can leverage microbial metabolism to transfer radiocarbons (14C) labeled on the metabolite of interest to the catabolite (or metabolized end product) in vitro; a novel labelling technique that can allow us to track microbial metabolism in the gut and potentially track the gut-brain communication when applied in vivo. To accomplish our goal, we have evaluated whether the 14C-labeled L-glutamic acid can be transferred to the microbial catabolite, -aminobutyric acid (GABA), a major inhibitory neurotransmitter in the central nervous system (CNS), using a simple monoculture of Lactobacillus brevis, a bacteria strain known to produce high amounts of GABA via the enzyme glutamate decarboxylase.

Mission Impact

This work supports Lawrence Livermore National Laboratory's core competency in Bioscience and Bioengineering. Demonstrating the feasibility to transfer of 14C to GABA in a simple bacteria system will set the foundation to apply this approach in a more complex microbial community, relevant to the native gut. For examples, post-traumatic stress disorder and anxiety, known to have a higher incidental rate in the Military and evaluate the therapeutic efficacy of manipulating the gut microbiome of the warfighter to prevent or ameliorate work hazard-induced NPD. 

Publications, Presentations, and Patents

Baliu-Rodriguez, D., Stewart, B., Mayali, X., Stuart, R., Enright H.A., and Lam, D. "14C-labeled microbes to track the fates of microbial metabolites." (2022). Society of Toxicology. Nashville, TN, USA. LLNL-ABS-842478.

Adams, J. B., T. Vargason, D. W. Kang, R. Krajmalnik-Brown, and J. Hahn. 2019a. "Multivariate Analysis of Plasma Metabolites in Children with Autism Spectrum Disorder and Gastrointestinal Symptoms Before and After Microbiota Transfer Therapy." Processes 7 (11): 18. ://WOS:000502263700032.

Adams, James B., Troy Vargason, Dae-Wook Kang, Rosa Krajmalnik-Brown, and Juergen Hahn. 2019b. "Multivariate Analysis of Plasma Metabolites in Children with Autism Spectrum Disorder and Gastrointestinal Symptoms Before and After Microbiota Transfer Therapy." Processes 7 (11).

Ambrosini, Y. M., D. Borcherding, A. Kanthasamy, H. J. Kim, A. A. Willette, A. Jergens, K. Allenspach, and J. P. Mochel. 2019. "The Gut-Brain Axis in Neurodegenerative Diseases and Relevance of the Canine Model: A Review." Front Aging Neurosci 11: 130.

Cuomo, A., G. Maina, G. Rosso, B. Beccarini Crescenzi, S. Bolognesi, A. Di Muro, N. Giordano, A. Goracci, S. M. Neal, M. Nitti, F. Pieraccini, and A. Fagiolini. 2018. "The Microbiome: A New Target for Research and Treatment of Schizophrenia and its Resistant Presentations? A Systematic Literature Search and Review." Front Pharmacol 9: 1040.

Kang, D. W., J. B. Adams, D. M. Coleman, E. L. Pollard, J. Maldonado, S. McDonough-Means, J. G. Caporaso, and R. Krajmalnik-Brown. 2019. "Long-term benefit of Microbiota Transfer Therapy on autism symptoms and gut microbiota." Sci Rep 9 (1): 5821.

Kang, Dae-Wook, James B. Adams, Ann C. Gregory, Thomas Borody, Lauren Chittick, Alessio Fasano, Alexander Khoruts, Elizabeth Geis, Juan Maldonado, Sharon McDonough-Means, Elena L. Pollard, Simon Roux, Michael J. Sadowsky, Karen Schwarzberg Lipson, Matthew B. Sullivan, J. Gregory Caporaso, and Rosa Krajmalnik-Brown. 2017. "Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study." Microbiome 5 (1): 10.

Kennedy, E. A., K. Y. King, and M. T. Baldridge. 2018. "Mouse Microbiota Models: Comparing Germ-Free Mice and Antibiotics Treatment as Tools for Modifying Gut Bacteria." Front Physiol 9: 1534.

Kim, Y. K., and C. Shin. 2018. "The Microbiota-Gut-Brain Axis in Neuropsychiatric Disorders: Pathophysiological Mechanisms and Novel Treatments." Curr Neuropharmacol 16 (5): 559-573.

Kurokawa, S., T. Kishimoto, S. Mizuno, T. Masaoka, M. Naganuma, K. C. Liang, M. Kitazawa, M. Nakashima, C. Shindo, W. Suda, M. Hattori, T. Kanai, and M. Mimura. 2018. "The effect of fecal microbiota transplantation on psychiatric symptoms among patients with irritable bowel syndrome, functional diarrhea and functional constipation: An open-label observational study." J Affect Disord 235: 506-512.

Rogers, G. B., D. J. Keating, R. L. Young, M. L. Wong, J. Licinio, and S. Wesselingh. 2016. "From gut dysbiosis to altered brain function and mental illness: mechanisms and pathways." Mol Psychiatry 21 (6): 738-48.