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Park, Hyo Joon (David)

University of British Columbia

Previous studies have demonstrated that induction of ketosis by a ketogenic diet (KD), a high-fat, low-carbohydrate diet, can improve the pathophysiology that occurs after spinal cord injury (SCI). Thus, the potential beneficial effects of ketone esters (KE, ∆G®, a β-hydroxybutyrate diester) supplementation that can rapidly induce a metabolic state of ketosis were investigated. Following SCI, the NLRP3 inflammasome, an innate immune system receptor/sensor that regulates the activation of proinflammatory cytokines (e.g., IL-1β), is significantly upregulated. Therefore, the NLRP3 inflammasome may contribute to secondary degeneration after SCI. Starting three hours following C5 hemi-contusion (150kDyn), Sprague-Dawley rats (males 250-300g) were treated with oral gavage of water with free access to a standard diet (SD: 1004403, Dyets Inc) or oral gavage of ketone esters with free access to a standard diet supplemented with ketone esters (KE:1004404, Dyets Inc). Rats were euthanized at 1-, 2-, 7-, and 14-days post-injury, and three 5mm long pieces of the spinal cords (rostral, C4-C5; epicenter, C5-C6; caudal, C6-C7) were harvested immediately after PBS perfusion. Temporal (1, 2, 7, and 14 DPI) and positional (rostral, epicenter, and caudal) expression of the NLRP3 inflammasome components were analyzed by western blots, ELISA, and immunohistochemistry. Our data reveal that SCI, compared to sham operation, induced a significant increase of the NLRP3-associated components, with the peak of expression and activity occurring at 2 DPI. Importantly, upstream activators (NF-κB) and downstream effectors (e.g., Caspase-1 and Gasdermin D) of the inflammasome were transiently yet significantly downregulated in KE cohorts, suggesting that KE can beneficially modify the inflammatory response following SCI. In addition, our morphometric quantifications and density analysis of activated and quiescent microglia/macrophages at the injury site following SCI reveals that KE results in a lower proportion of activated microglia (i.e., the proportion of CD45⁻/Iba1⁺ over all Iba1⁺ cells) but not their density (number of cells per unit area), compared to SD. These findings demonstrate the potential neuroprotective benefits of KE supplementation initiated soon after SCI.

Text

2024-04-16

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87854

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/