Abstract TP272: An Association Between Tlr And Jak Signaling Following Cerebral Ischemia: A Translational Approach

Abstract

Objectives: Toll like receptor (TLR) signaling emerged as a significant pathway in our whole genome peripheral blood study of ischemic stroke patients. In our dataset, TLR signaling is associated with stroke severity, can predict outcome and is influenced by age. The age-mediated effects on TLR expression and kinase signaling in response to cerebral ischemia are not well-characterized. The objective of this project was to confirm and further characterize our clinical findings in a preclinical aged stroke model by analyzing TLR gene expression and the kinase proteome. Methods: An SaBiosciences rat TLR PCR array was used to compare brain and blood gene expression in 3 (n=3) and 18 (n=3) month old rats that underwent embolic middle cerebral artery occlusion (MCAO) with tPA reperfusion and sacrificed at 24 hours. Blood samples were collected via femoral artery in Qiagen RNA protect tubes. Rats were perfused and then Brain tissue was collected in RNA later. A Kinetworks Protein Kinase Screen 1.2 was performed on infarcted cortex (n=4). Univariate and multivariate associations between old and young and blood and brain and group differences across sham and treatment were identified by the Mann-whitney U and ANOVA. Results: There was an 85% overlap in TLR related genes when comparing blood and brain. Kinase data revealed HPK1 expression was lowest in old MCAO (p=0.005); Jak2 expression was higher in old MCAO (0.03).There was a differential response of Pkc-a expression after MCAO, where it was increased in the young, but decreased in the aged (0.014). PKA expression increased after MCAO, but was lower in the aged (0.014). Conclusion: Our findings support the use of peripheral blood as a surrogate to monitor the response to cerebral ischemia and emphasize the clinical relevance of using age in preclinical models of ischemia. This data suggests a novel age-related mechanism of cross talk between TLR and JAK2 signaling that may occur through HPK1 and PKA. Additional clinical and preclinical studies are required to confirm this data and better characterize the kinase cross-talk between TLR and JAK2 signaling.