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Elsaafien K, Sloan JM, Evans RG, Cochrane AD, Marino B, McCall PR, Hood SG, Yao ST, Korim WS, Bailey SR, Jufar AH, Peiris RM, Bellomo R, Miles LF, May CN, Lankadeva YR. Associations Between Systemic and Cerebral Inflammation in an Ovine Model of Cardiopulmonary Bypass. Anesth Analg 2023; 136:802-813. [PMID: 36928157 DOI: 10.1213/ane.0000000000006379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Intraoperative inflammation may contribute to postoperative neurocognitive disorders after cardiac surgery requiring cardiopulmonary bypass (CPB). However, the relative contributions of general anesthesia (GA), surgical site injury, and CPB are unclear. METHODS In adult female sheep, we investigated (1) the temporal profile of proinflammatory and anti-inflammatory cytokines and (2) the extent of microglia activation across major cerebral cortical regions during GA and surgical trauma with and without CPB (N = 5/group). Sheep were studied while conscious, during GA and surgical trauma, with and without CPB. RESULTS Plasma tumor necrosis factor-alpha (mean [95% confidence intervals], 3.7 [2.5-4.9] vs 1.6 [0.8-2.3] ng/mL; P = .0004) and interleukin-6 levels (4.4 [3.0-5.8] vs 1.6 [0.8-2.3] ng/mL; P = .029) were significantly higher at 1.5 hours, with a further increase in interleukin-6 at 3 hours (7.0 [3.7-10.3] vs 1.8 [1.1-2.6] ng/mL; P < .0001) in animals undergoing CPB compared with those that did not. Although cerebral oxygen saturation was preserved throughout CPB, there was pronounced neuroinflammation as characterized by greater microglia circularity within the frontal cortex of sheep that underwent CPB compared with those that did not (0.34 [0.32-0.37] vs 0.30 [0.29-0.32]; P = .029). Moreover, microglia had fewer branches within the parietal (7.7 [6.5-8.9] vs 10.9 [9.4-12.5]; P = .001) and temporal (7.8 [7.2-8.3] vs 9.9 [8.2-11.7]; P = .020) cortices in sheep that underwent CPB compared with those that did not. CONCLUSIONS CPB enhanced the release of proinflammatory cytokines beyond that initiated by GA and surgical trauma. This systemic inflammation was associated with microglial activation across 3 major cerebral cortical regions, with a phagocytic microglia phenotype within the frontal cortex, and an inflammatory microglia phenotype within the parietal and temporal cortices. These data provide direct histopathological evidence of CPB-induced neuroinflammation in a large animal model and provide further mechanistic data on how CPB-induced cerebral inflammation might drive postoperative neurocognitive disorders in humans.
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Affiliation(s)
- Khalid Elsaafien
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Cardiovascular Neuroscience Laboratory, Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
- Centre for Integrative Cardiovascular and Metabolic Diseases, Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida
| | - Jasmine M Sloan
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Cardiovascular Neuroscience Laboratory, Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Roger G Evans
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Andrew D Cochrane
- Department of Cardiothoracic Surgery, Monash Health, and Department of Surgery (School of Clinical Sciences at Monash Health), Monash University, Melbourne, Victoria, Australia
| | - Bruno Marino
- Cellsaving and Perfusion Resources, Melbourne, Victoria, Australia
| | - Peter R McCall
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
- Department of Critical Care, Melbourne Medical School, Melbourne, Victoria, Australiaand
| | - Sally G Hood
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
| | - Song T Yao
- Cardiovascular Neuroscience Laboratory, Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Willian S Korim
- Cardiovascular Neuroscience Laboratory, Department of Anatomy and Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Simon R Bailey
- Faculty of Veterinary Science, University of Melbourne, Melbourne, Victoria, Australia
| | - Alemayehu H Jufar
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Rachel M Peiris
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
| | - Rinaldo Bellomo
- Department of Critical Care, Melbourne Medical School, Melbourne, Victoria, Australiaand
| | - Lachlan F Miles
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
- Department of Critical Care, Melbourne Medical School, Melbourne, Victoria, Australiaand
| | - Clive N May
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Department of Critical Care, Melbourne Medical School, Melbourne, Victoria, Australiaand
| | - Yugeesh R Lankadeva
- From the Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health
- Department of Critical Care, Melbourne Medical School, Melbourne, Victoria, Australiaand
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