Dissertation Defense: A Single Cell and Spatial Transcriptomic Investigation of Traumatic Brain Injury: Novel insights into endothelial-derived Eph signaling
Dissertation Defense: A Single Cell and Spatial Transcriptomic Investigation of Traumatic Brain Injury: Novel insights into endothelial-derived Eph signaling
Caroline de Jager
Graduate Student, Translational Biology, Medicine, and Health
Graduate Research Assistant, Theus Lab
December 10, 2024, at 1:00p.m.
Room 118, Steger Hall
About this Dissertation
A staggering number of injury related disabilities and deaths are connected to traumatic brain injury (TBI) worldwide. Traumatic brain injury (TBI) involves an intricate and multifaceted cascade of events, starting with an initial mechanical impact followed by secondary injury brought on by numerous physiological changes that involve significant dysfunction at the cellular and molecular level. One major predictor of severe TBI outcome is the extent of blood-brain barrier (BBB) disruption, which under normal conditions prevents the passage of bacteria, neurotoxins, and macromolecules from entering the brain. Disruption of the BBB is linked to worse clinical outcomes in patients in both the acute, subacute, and chronic phases. However, the principal mechanisms responsible for regulating BBB permeability, where, and for how long that permeability occurs following TBI remains to be elucidated. Previous research has shown increased mRNA and protein expression of ephrin receptor A4 (EphA4), a well-established axon guidance molecule, within hours and days following TBI. This study is the first comprehensive investigation of the role of endothelial cell-specific EphA4 in TBI on regulating the BBB using advanced techniques like single-cell RNA and spatial transcriptomic sequencing, in addition to our newly established dual dye-labeling system. The central hypothesis is that endothelial cell-specific deletion of EphA4 enhances BBB integrity, characterized by changes in single cell gene expression consistent with improved barrier function, altered cellular metabolism, and reduced neuroinflammation within the BBB niche. This hypothesis will be tested by leveraging spatial sequencing to identify upregulation of genes associated with BBB stability and neuroprotection and utilizing a novel approach for assessing BBB permeability that addresses the limitations of traditional Evans Blue Dye (EBD) assays, including lack of spatial resolution, enabling precise analysis of molecular weight-dependent extravasation patterns.
More About the Candidate and Project
- Education and Training
- Committee Members
- Publications and Presentations
- Honors and Awards and Service
Education
Virginia Tech, Translational Biology, Medicine, and Health, Ph.D. Candidate
Virginia Tech, B.S. Clinical Neuroscience
Training
Graduate Research Assistant, Theus Lab
Mentor
Michelle H. Theus, Ph.D., Professor, Molecular and Cellular Neurobiology; Director, Neurotrauma Research Program
Committee Members
- Kylene Kehn-Hall, Ph.D., Professor, VA-MD College of Veterinary Medicine
- John Rossmeisl, DVM, MS, DACVIM, Associate Department Head, Department of Small Animal Clinical Sciences
- Hehuang Xie, Ph.D., Professor, VA-MD College of Veterinary Medicine
Publications
Kowalski EA, Soliman E, Kelly C, Basso EKG, Leonard J, Pridham KJ, Ju J, Cash A, Hazy A, de Jager C, Kaloss AM, Ding H, Hernandez RD, Coleman G, Wang X, Olsen ML, Pickrell AM, Theus MH. Monocyte proinflammatory phenotypic control by ephrin type A receptor 4 mediates neural tissue damage. JCI Insight. 2022 Aug 8;7(15):e156319. doi: 10.1172/jci.insight.156319. PMID: 35737458; PMCID: PMC9462496.
Alison Cash, Caroline de Jager, Thomas Brickler, Eman Soliman, Alexandra M. Kaloss, Yumeng Zhu, Kevin J. Pridham, Jatia Mills, Jing Ju, Erwin Kristobal Gudenschwager Basso, Michael Chen, Zachary Johnson, Yianni Sotiropoulos, Xia Wang, Hehuang Xie, John B. Matson, and Michelle H. Theus. Endothelial deletion of EPH receptor A4 alters single-cell profile and Tie2/Akap12 signaling to preserve blood-brain barrier integrity. PNAS. 2023 Jan 30.
Soliman, Eman, et al. “Efferocytosis is restricted by axon guidance molecule EPHA4 via ERK/STAT6/MERTK signaling following brain injury.” Journal of Neuroinflammation, vol. 20, no. 1, 9 Nov. 2023, https://doi.org/10.1186/s12974-023-02940-5.
Gudenschwager Basso, Erwin K., et al. “Immunoregulatory and neutrophil-like monocyte subsets with distinct single-cell transcriptomic signatures emerge following brain injury.” Journal of Neuroinflammation, vol. 21, no. 1, 3 Feb. 2024 ,https://doi.org/10.1186/s12974-024-03032-8.
Fritsch, Lauren E., et al. “Sting-dependent signaling in microglia or peripheral immune cells orchestrates the early inflammatory response and influences brain injury outcome.” The Journal of Neuroscience, 15 Feb. 2024, https://doi.org/10.1523/jneurosci.0191-23.2024.
Presentations
ORAL PRESENTATIONS
De Jager, C. D., Cash, A., Brickler, T, & Theus, M.H. (2022). Vascular-Immune crosstalk in the
Regulation of Blood Brain Barrier breakdown following trauma. Precision Neuroscience conference. Roanoke, Virginia.
de Jager, C. D. Communicating Science Presentation for the Nutshell Games. Virginia Tech (2023) "Proteins on Blood Vessels Influence the Severity of Traumatic Brain Injury".
de Jager, C. D., Medgenome Webinar (2024). Using Spatial Transcriptomics to Investigate Altered Gene Expression in Traumatic Brain Injury. GenomeWeb.
POSTER PRESENTATIONS
de Jager, C. D., Cash, A., Hehuang, X. , & Theus, M.H. (2024). A Spatial Investigation of Blood-Brain Barrier Disruption in a Murine Model of Controlled Cortical Impact. National Neuroscience Symposium, San Francisco, CA.
de Jager, C. D., Cash, A., Brickler, T, & Theus, M.H. (2023). Single-cell Seq identifies Akap12 as a key capillary-specific gene involved in EphA4/Tie2 control of blood-brain barrier integrity. Translational Biology, Medicine, and Health 2023 Winter Symposium. Roanoke, Virginia.
de Jager, C. D., Cash, A., Brickler, T, & Theus, M.H. (2022). Interrogating Blood Brain Barrier
Dysfunction in Traumatic Brain Injury. 12th Annual Traumatic Brain Injury Conference. Washington, D.C.
de Jager, C. D., Cash, A., Brickler, T, & Theus, M.H. (2022). Vascular-Immune crosstalk in the
regulation of Blood Brain Barrier breakdown following trauma. American Society for
Neurochemistry (ASN) conference. Roanoke, Virginia.
de Jager, C. D., Cash, A., Brickler, T, & Theus, M.H. (2022). Interrogating Blood Brain Barrier
Dysfunction in Traumatic Brain Injury*. Graduate and Postdoctoral Student Symposium at Virginia Tech (GPSS). Roanoke, Virginia. *Honorable Mention.
de Jager, C. D., Cash, A., Brickler, T, & Theus, M.H. (2021). Interrogating Blood Brain Barrier
Dysfunction in Traumatic Brain Injury. American Society for Neural Therapy and Repair
(ASNTR) conference. Clearwater, Florida.
Honors and Awards
TBMH Student of the Year Award Recipient 2024
TBMH Student of the Year Award Nomination for Education 2022
TBMH Student of the Year Award Nomination for Community 2022 and 2023
Service
Established Chapter Advisor for Synapse National 2020 – 2021
Roanoke Graduate Student Association (RGSA) Wellness Chair 2021 – 2022
Teaching Assistant Translational Biology, Medicine, and Health Fall 2021 - Spring 2022