Kristian Doyle
Associate Professor, BIO5 Institute
Associate Professor, Immunobiology
Associate Professor, Neurology
Associate Professor, Neuroscience - GIDP
Associate Professor, Neurosurgery
Associate Professor, Psychology
Member of the Graduate Faculty
Research Scientist
Primary Department
Department Affiliations
(520) 626-7013
Work Summary
Approximately 795,000 Americans suffer a stroke each year, and 400,000 will experience long-term disability. The number of stroke survivors in the population is expected to double by 2025. Currently, treatments for stroke patients are limited to tissue plasminogen activator (TPA), but its use is limited to the first few hours after stroke. Therefore, the goal of our research is to develop new therapeutics that can promote repair and recovery in this rapidly growing population.
Research Interest
The Doyle lab investigates the role of the immune system in causing dementia after stroke. Up to 30% of stroke patients develop dementia in the months and years after their stroke and we are testing the hypothesis that in some patients this is due to a chronic inflammatory response that persists at the site of the stroke infarct. We suspect that in the weeks, months and possibly years after stroke, neurotoxic inflammatory mediators, including T cells, cytokines and antibodies, leak out of the stroke infarct and cause bystander damage to the surrounding tissue, which then both impairs recovery, and in some instances leads to cognitive decline. In support of this hypothesis we have data that demonstrates that inflammation persists for months at the site of the infarct after stroke, and that a single stroke can directly lead to the development of immune-mediated delayed cognitive deficits. We are currently in the process of targeting different components of the prolonged inflammatory response to stroke to determine if post stroke dementia can be treated by selectively ablating individual immune mediators such as B lymphocytes, T lymphocytes, and CCR2. Keywords: Neuroinflammation, stroke, dementia, Alzheimer's disease

Publications

Bartlett, M. J., Flores, A. J., Dollish, H. K., Farrell, D. C., Parent, K. L., Besselsen, D. G., Heien, M. L., Doyle, K., Cowen, S. L., Steece-Collier, K., Sherman, S. J., & Falk, T. (2017). Neuroplastic mechanism of sub-anesthetic ketamine treatment to reduce development of L-DOPA-induced dyskinesia. Science Translational Medicine.
BIO5 Collaborators
David G Besselsen, Kristian Doyle
Doyle, K. P., Cekanaviciute, E., Mamer, L. E., & Buckwalter, M. S. (2010). TGFβ signaling in the brain increases with aging and signals to astrocytes and innate immune cells in the weeks after stroke. Journal of neuroinflammation, 7, 62.

TGFβ is both neuroprotective and a key immune system modulator and is likely to be an important target for future stroke therapy. The precise function of increased TGF-β1 after stroke is unknown and its pleiotropic nature means that it may convey a neuroprotective signal, orchestrate glial scarring or function as an important immune system regulator. We therefore investigated the time course and cell-specificity of TGFβ signaling after stroke, and whether its signaling pattern is altered by gender and aging.

Pollak, J., Doyle, K. P., Mamer, L., Shamloo, M., & Buckwalter, M. S. (2012). Stratification substantially reduces behavioral variability in the hypoxic-ischemic stroke model. Brain and behavior, 2(5), 698-706.

Stroke is the most common cause of long-term disability, and there are no known drug therapies to improve recovery after stroke. To understand how successful recovery occurs, dissect candidate molecular pathways, and test new therapies, there is a need for multiple distinct mouse stroke models, in which the parameters of recovery after stroke are well defined. Hypoxic-ischemic stroke is a well-established stroke model, but behavioral recovery in this model is not well described. We therefore examined a panel of behavioral tests to see whether they could be used to quantify functional recovery after hypoxic-ischemic stroke. We found that in C57BL/6J mice this stroke model produces high mortality (approximately one-third) and variable stroke sizes, but is fast and easy to perform on a large number of mice. Horizontal ladder test performance on day 1 after stroke was highly and reproducibly correlated with stroke size (P 18% foot faults and 2.1-fold larger strokes. This group exhibited significant functional deficits for as long as 3 weeks on the horizontal ladder test and through the last day of testing on automated gait analysis (33 days), rotarod (30 days), and elevated body swing test (EBST) (36 days). No deficits were observed in an automated activity chamber. We conclude that stratification by horizontal ladder test performance on day 1 identifies a subset of mice in which functional recovery from hypoxic-ischemic stroke can be studied.

Bahjat, F. R., Williams-Karnesky, R. L., Kohama, S. G., West, G. A., Doyle, K. P., Spector, M. D., Hobbs, T. R., & Stenzel-Poore, M. P. (2011). Proof of concept: pharmacological preconditioning with a Toll-like receptor agonist protects against cerebrovascular injury in a primate model of stroke. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism, 31(5), 1229-42.

Cerebral ischemic injury is a significant portion of the burden of disease in developed countries; rates of mortality are high and the costs associated with morbidity are enormous. Recent therapeutic approaches have aimed at mitigating the extent of damage and/or promoting repair once injury has occurred. Often, patients at high risk of ischemic injury can be identified in advance and targeted for antecedent neuroprotective therapy. Agents that stimulate the innate pattern recognition receptor, Toll-like receptor 9, have been shown to induce tolerance (precondition) to ischemic brain injury in a mouse model of stroke. Here, we demonstrate for the first time that pharmacological preconditioning against cerebrovascular ischemic injury is also possible in a nonhuman primate model of stroke in the rhesus macaque. The model of stroke used is a minimally invasive transient vascular occlusion, resulting in brain damage that is primarily localized to the cortex and as such, represents a model with substantial clinical relevance. Finally, K-type (also referred to as B-type) cytosine-guanine-rich DNA oligonucleotides, the class of agents employed in this study, are currently in use in human clinical trials, underscoring the feasibility of this treatment in patients at risk of cerebral ischemia.

Doyle, K. P., Fathali, N., Siddiqui, M. R., & Buckwalter, M. S. (2012). Distal hypoxic stroke: a new mouse model of stroke with high throughput, low variability and a quantifiable functional deficit. Journal of neuroscience methods, 207(1), 31-40.

C57BL/6J are the most commonly used strain of mouse for stroke experiments but vascular anatomy of the Circle of Willis within this strain is extremely variable and the cortex has extensive collateralization. This causes large variability in stroke models that target the middle cerebral artery proximally and confers resistance to ischemia in those that target it distally. We tested the hypothesis that by combining distal middle cerebral artery occlusion with 1h of hypoxia, we could generate a large lesion that causes a behavioral deficit with low variability. We found that this new distal hypoxic (DH) model of stroke generates a lesion with a volume of 25% of the ipsilateral hemisphere, extends to the motor cortex and causes a behavioral deficit. It also has a very clear border, exceptionally low variability, and can be performed by a single surgeon on up to 30 animals a day. Moreover, survivability is 100% in young adult animals, the model can be performed on old animals, and therapeutic intervention can reduce infarct volume. Therefore DH stroke is an excellent complement to existing stroke models and could be used for preclinical studies in C57BL/6J mice.