Time Dimension Influences Severity of Stroke and Heightened Immune Response in Mice

Pradip K Kamat; Mohammad Badruzzaman Khan; Shahneela Siddiqui; Dylan Williams; Evila da Silva Lopes Salles; Sahar Emami Naeini; Ali S Arbab; Daniel R Rudic; Babak Baban; Krishnan M Dhandapani; David C Hess

doi:10.1007/s12975-023-01226-5

Time Dimension Influences Severity of Stroke and Heightened Immune Response in Mice

Transl Stroke Res. 2023 Dec 13. doi: 10.1007/s12975-023-01226-5. Online ahead of print.

Affiliations

¹ Departments of Neurology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA. pkamat@augusta.edu.
² Departments of Neurology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA.
³ Departments of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, USA.
⁴ Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, USA.
⁵ Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, USA.
⁶ Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta, USA.

PMID: 38091188
DOI: 10.1007/s12975-023-01226-5

Abstract

Ischemic stroke is caused by obstructed cerebral blood flow, which results in neurological injury and poor outcomes. Pro-inflammatory signaling from both residential and infiltrating immune cells potentiates cerebral injury and worsens patient outcomes after stroke. While the occurrence of a stroke exhibits a time-of-day-dependent pattern, it remains unclear whether disrupted circadian rhythms modulate post-stroke immunity. In this study, we hypothesized that stroke timing differentially affects immune activation in mice. Following middle cerebral artery occlusion (MCAO), circadian genes BMAL1, CLOCK, Cry1, and Cry2 elevated at ZT06, with a significant difference between ZT06 and ZT18. Conversely, expression of the negative limb circadian clock gene, Per1, decreased at ZT06 and ZT18 in stroke mice compared to sham. Paralleling these circadian gene expression changes, we observed a significant increase in TNF-α and a decrease in IL-10 expression at 48 h post-MCAO, when the procedure was performed at ZT06 (MCAO-ZT6), which corresponds to a deep sleep period, as compared to when the stroke was induced at ZT12 (MCAO-ZT12), ZT18 (MCAO-ZT18), or ZT0 (MCAO-ZT12). Similarly, increased pro-inflammatory, decreased anti-inflammatory monocytes, and increased NLRP3 were observed in blood, while changes in the expression of CD11b and Iba1 were noted within brain tissue at 48 h of MCAO-ZT06, as compared to MCAO-ZT18. Consistent with the increased immune response, infarct volume and sensorimotor deficits were greater in MCAO-ZT06 mice compared to MCAO-ZT18 mice at 48 h. Finally, we found reduced weight and length of the spleen while splenocytes showed significant time-dependent changes in Tregs, Bregs, and monocytes in MCAO-ZT06 mice. Taken together, this study demonstrates that circulating and splenic immune responses following ischemic stroke exhibit a circadian expression pattern which may contribute to time-of-day-dependent stroke outcomes.

Keywords: Circadian rhythm; Immune response; Inflammation; Neurobehavioral function; Stroke.

Grants and funding

1U01NS130590-01/NH/NIH HHS/United States