Abstract WP226: Circadian Rhythm Influences Immune Response In Ischemic Stroke Mice

Background: Stroke leads to disability and death worldwide. There is evidence that stroke affects the immune system function, and the clock gene controls the immune system. Stroke elevates the inflammatory cascade. Immune response controls the stroke pathology. However, it is unclear if the circadian rhythm influences the immune system in ischemic stroke mice and affects stroke outcomes. Hypothesis: We hypothesized that immune response might be affected by a circadian rhythm that aggravates stroke pathology in a mouse suture occlusion model Methods: Seven to eight-month-old C57BL/6J (Wild Type, n=8-10 mice/group) mice were randomly assigned to do stroke at the different time points of the day following zeitgeber time at ZT0, ZT6, ZT12, and Z18. Cerebral Ischemia was induced by occlusion of the middle cerebral artery (MCAO) for 60 min. Whole blood was analyzed using flow cytometry, and we observed macrophages (M1, M2), neutrophils (N1, N2), Anti-inflammatory IL10, and pro-inflammatory TNF-α cytokines at 24h and 48h. Forty-eight hours after stroke, TTC staining was done to estimate brain infarction, and the infarct area was measured using NIH-Image J software. Results: There was a significant increase ( p p p p p Conclusion: This study demonstrates that mice brain infarcts are influenced by immune responses that aggravate stroke pathology during their sleep period (noon/ZT6) than during their awake period (midnight/ZT18).