3533 Delayed Administration Of Angiotensin Receptor (AT2R) Agonist C21 Downregulates Diabetes Induced Pro-Inflammatory Microglia Activation To Improve Cognitive & Functional Recovery Post Stroke: Therapeutic Indications For The Treatment Of Vascular Cognitive

OBJECTIVES/SPECIFIC AIMS: The study aim was to 1) elucidate mechanisms contributing to the evolution of PSCI using a clinically relevant model of diabetes, a major risk factor for stroke and cognitive impairment, and 2) develop angiotensin type 2 receptor (AT2R) agonism as a therapeutic target. METHODS/STUDY POPULATION: Diabetes was induced in male Wistar rats by a HFD & low dose streptozotocin combination. At 12-14 weeks of age a total of 69 control & diabetic rats were subjected to 1 hr middle cerebral artery occlusion (MCAO) or Sham surgery. 3 days post-MCAO, rats that met the pre-set inclusion criteria were administered C21 or saline in drinking water at a dose of 0.12 mg/kg/day Adhesive removal task (ART) & 2-trial Ymaze were utilized to test sensorimotor & cognitive function at baseline as well as 1, 2, 4 and 8 weeks post-stroke. At week 8 post-stroke cell suspensions from freshly harvested brains were analyzed by flow cytometry utilizing antibodies against cell surface markers for M1 (CD11b+/CD45 low/ CD86+/TNFa+), M2 (CD11b+/CD45 low/ CD206+/IL-10+), and residential microglia (CD11b+/CD45+/ TMEM119+). RESULTS/ANTICIPATED RESULTS: Control rats progressively recovered from stroke-induced functional deficits by week 8, while diabetics still remained impaired (P< 0.05). 8 weeks post-MCAO only diabetic rats exhibited a decline in sensorimotor (P< 0.05) and cognitive function (P< 0.05) compared to Shams. Delayed administration of C21 on D2 post-stroke halted the decline and improved sensorimotor (P< 0.05) and cognitive function (P< 0.01). Flow cytometric analyses indicate that 8 post-stroke vehicle diabetics had an elevated M1/M2 ratio within the ipsilateral prefrontal cortex and hippocampus (P< 0.01, 0.01). They also had a larger percentage of non-residential microglia/macrophages, indicative of compromised blood brain barrier (BBB) integrity. Treatment with C21 significantly lowered the M1/M2 ratio (P< 0.05) and improved the BBB integrity. DISCUSSION/SIGNIFICANCE OF IMPACT: Taken together this study suggests that the use of comorbid disease models such as diabetes, may allow for more translational evaluations of PSCI. Higher translational relevance may also lead to a higher number of successful clinical trials and more FDA approved stroke therapies. It also suggests that C21 may serve as a potential therapeutic to modulate the development of PSCI.