Neuroprotective Effects of Annexin A1 Tripeptide after Deep Hypothermic Circulatory Arrest in Rats

Abstract

Resolution agonists, including lipid mediators and peptides such as annexin A1 (ANXA1), are providing novel approaches to treat inflammatory conditions. Surgical trauma exerts a significant burden on the immune system that can affect and impair multiple organs. Perioperative cerebral injury after cardiac surgery is associated with significant adverse neurological outcomes such as delirium and postoperative cognitive dysfunction. Using a clinically relevant rat model of cardiopulmonary bypass (CPB) with deep hypothermic circulatory arrest (DHCA), we tested the pro-resolving effects of a novel bioactive ANXA1 tripeptide (ANXA1sp) on neuroinflammation and cognition. Male rats underwent 2 h CPB with 1 h DHCA at 18°C, and received vehicle or ANXA1sp followed by timed reperfusion up to postoperative day 7. Immortalized murine microglial cell line BV2 were treated with vehicle or ANXA1sp and subjected to 2 h oxygen–glucose deprivation followed by timed reoxygenation. Microglial activation, cell death, neuroinflammation, and NF-κB activation were assessed in tissue samples and cell cultures. Rats exposed to CPB and DHCA had evident neuroinflammation in various brain areas. However, in ANXA1sp-treated rats, microglial activation and cell death (apoptosis and necrosis) were reduced at 24 h and 7 days after surgery. This was associated with a reduction in key pro-inflammatory cytokines due to inhibition of NF-κB activation in the brain and systemically. Treated rats also had improved neurologic scores and shorter latency in the Morris water maze. In BV2 cells treated with ANXA1sp, similar protective effects were observed including decreased pro-inflammatory cytokines and cell death. Notably, we also found increased expression of ANXA1, which binds to NF-κB p65 and thereby inhibits its transcriptional activity. Our findings provide evidence that treatment with a novel pro-resolving ANXA1 tripeptide is neuroprotective after cardiac surgery in rats by attenuating neuroinflammation and may prevent postoperative neurologic complications.

Neuroinflammation and Perioperative Neurocognitive Disorders

“…Cardiac models of surgery, recapitulating cardiopulmonary bypass and deep hypothermic circulatory arrest, have been established to assess neurological complications and perioperative inflammation. 35 Notably, cardiac surgery triggers widespread changes in cognition that differ from abdominal surgery, while both generate substantial hippocampal neuroinflammation (ie, microglial activation). 36 This suggests that distinct pathways may be involved in the response to injury in different organs, and further studies are needed to dissect these pathways.…”

The Role of Neuroinflammation in Postoperative Cognitive Dysfunction: Moving From Hypothesis to Treatment

“…As opposed to preventing the production of pro-inflammatory cytokines or oxidative species, lipid mediators such as resolvins, lipoxins, and maresins have begun to receive attention as possible resolvers of neuroinflammation (4, 129). In a rat model of CPB with deep hypothermic circulatory arrest, the resolution agonist annexin A1 was shown to (1) reduce systemic and neural pro-inflammatory cytokines due to inhibition of NF-κB, (2) inhibit microglial activation, and mitigate declines in Morris water maze performance at postoperative day 3 (204). Currently, no human trials exist on the role of these lipid mediators in POCD, although these agents may become more promising as more animal data become available.…”

Annexin-A1 tripeptide attenuates surgery-induced neuroinflammation and memory deficits through regulation of the NLRP3 inflammasome

“…ANXA1 is also highly expressed on macrophages, facilitating efferocytosis of apoptotic neutrophils and overall resolution of inflammation (Scannell et al, 2007;Dalli et al, 2012). The pro-resolving effects of ANXA1sp may target this critical step at the level of the BBB, although our peptide also exerts potent antiinflammatory effects on systemic cytokines (Zhang et al, 2017). Thus, ANXA1sp effects on the CNS may result from an overall dampening of the pro-inflammatory milieu rather than, or in addition to, a direct effect on the BBB.…”

“…Several peptides (Ac2-26, Ac2-12, and Ac2-6) have been derived from the full-length N-terminal domain of ANXA1 and they have been tested in several inflammatory conditions (Sheikh and Solito, 2018). We have developed a small peptide (ANXA1sp) with potent anti-inflammatory effects on NF-κB signaling and organ-preserving functions (Zhang et al, 2010;Zhang et al, 2017;Ma et al, 2019). Based on preclinical and clinical results on the involvement of interleukin (IL)-1β signaling in PNDs (Cibelli et al, 2010;Cape et al, 2014), we have hypothesized that NLRP3 inflammasome activation orchestrates postoperative neuroinflammation.…”