Ethyl Pyruvate Provides Durable Protection Against Inflammation-Induced Intestinal Epithelial Barrier Dysfunction

Abstract

Ethyl pyruvate (EP) has been shown to be an effective anti-inflammatory agent. Herein, we sought to test the following hypotheses: 1) the pharmacological effects of EP persist after cells have been exposed to the compound in vitro, even if the cultures are washed to minimize the amount of EP that is retained in the media; 2) the pharmacological effects of EP persist in vivo, even after waiting a prolonged period (i.e., 6 h) after the last dose of the compound; and 3) the in vivo pharmacological effects of EP are distinct from those of the closely related compound, sodium pyruvate. Incubation of Caco-2 human enterocyte-like monolayers with cytomix, a mixture of interleukin-1beta, interferon-gamma, and tumor necrosis factor, increased permeability to the fluorescent macromolecule, FITC-labeled Dextran (mol wt 4,000 Da). Co-incubation of the cells with 5 mM EP ameliorated cytomix-induced hyperpermeability and induction of iNOS mRNA expression. EP was associated with similar pharmacological effects when cells were pre-incubated with the compound for 24 h prior and then washed extensively prior to adding the cytokine cocktail. Injecting C57Bl/6 mice with lipopolysaccharide (LPS) resulted in gut barrier dysfunction and hepatocellular injury. Although equivalent doses of both EP and sodium pyruvate ameliorated these phenomena, EP was more efficacious than pyruvate. Pretreatment with EP ameliorated the deleterious effects of LPS, even when the duration between the last dose of EP and the endotoxic challenge was 6 h. We conclude that EP provides durable protection against some of the deleterious effects of LPS or pro-inflammatory cytokines.

Ethyl Pyruvate Inhibits Nuclear Factor-κB-Dependent Signaling by Directly Targeting p65

“…Thus, the activity of ethyl pyruvate as an ROS scavenger might account for its antiinflammatory properties, since other ROS scavengers, such as N-acetylcysteine, are known to inhibit expression proinflammatory genes, at least under some conditions (Song et al, 2004). This notion, however, is not supported by observations recently reported by Sappington et al (2003a), who showed that transient exposure to ethyl pyruvate inhibits iNOS expression in immunostimulated Caco-2 human enterocyte-like cells, even when the compound is removed from the culture medium by thorough washing of the cells. In contrast to the ROS-scavenging hypothesis, which seems incompatible with the data obtained by Sappington et al (2003a), covalent modification of the p65 subunit of NF-B, as suggested by the findings reported herein, is entirely compatible with the observation that transient incubation with ethyl pyruvate provides a durable anti-inflammatory effect even in the absence of ongoing exposure to the compound.…”

HMGB1 in renal ischemic injury

“…EP is a pharmacological inhibitor of HMGB1 secretion (13,14,18,31,41,53,59,62,73,74,82); however, the precise mechanism(s) that mediate its inhibitory effects have not been identified as of yet. Treatment with EP has been shown to improve survival and alleviate organ dysfunction in a wide variety of preclinical models of critical illness (19,20) including the amelioration of IRI in organs (13,34,77,84) including the kidney (13).…”

Higher Hypochlorous Acid Scavenging Activity of Ethyl Pyruvate Compared to Its Sodium Salt

“…The well-described differences in the pharmacological effects of EtP and NaP [10][11][12][13][14][15][16] may reflect the greater lipophilicity of EtP. 16) Our data presented in Fig.…”

“…Despite its greater stability, EtP also appeared to be more effective than sodium pyruvate (NaP) under various stress conditions. [10][11][12][13][14][15][16] An in vivo model of LPS-induced hepatocellular injury indicated both EtP and NaP to have protective properties, although EtP was more efficacious.…”