Examining the effect of short-term oral ketone supplementation on markers of NLRP3 inflammasome activation in individuals with obesity

Background: The NLRP3 inflammasome, an innate immune sensor, has been implicated in the progression in a number of chronic inflammatory diseases and represents an important therapeutic target. The ketone body, beta-hydroxybutyrate (BHB) has been shown to attenuate NLRP3 activation in murine and in vitro models. However, these findings have not yet been replicated in humans. Methods: We conducted a randomized, double-blind, placebo-controlled, crossover study in humans with obesity (N = 14). We tested the hypothesis that elevation of blood BHB by ingestion of an exogenous ketone monoester drink (KME) 3x/day for 14 days would attenuate basal NLRP3 activation and would reduce NLRP3 sensitivity to activation in response to an inflammatory challenge. NLRP3 activation was quantified by magnitude of caspase-1 activation and secreted IL-1b. We also conducted an exploratory in vitro experiment in parallel to the in vivo study in which whole blood from each participant was cultured with lipopolysaccharide (LPS) and increasing concentrations of BHB. Results: KME supplementation elevated blood BHB concentration to ~2 mM. Monocyte caspase-1 activation was reduced in response to an inflammatory stimulus following 14-days of KME compared to placebo (time x condition interaction, χ²(1)=3.80, P = 0.05). Similarly, low-to-moderate, but not high, concentrations of BHB in culture appeared to attenuate IL-1b secretion in a dose-dependent manner. However, basal caspase-1 activation and plasma cytokines remained unchanged. Conclusions: Fourteen days of KME, which elevates BHB to low-to-moderate levels, appears to attenuate NLRP3 activation in human monocytes exposed to an inflammatory stimulus. This is the first study to replicate this concept in an in vivo/ex vivo human model. Future research should investigate the potential therapeutic effect of KME in human disease that exhibit excessive NLRP3 activation.Health and Social Development, Faculty of (Okanagan)Health and Exercise Sciences, School of (Okanagan)Graduat

Impact of fasting & ketogenic interventions on the NLRP3 inflammasome: A narrative review

Overactivation of the NLRP3 inflammasome is implicated in chronic low-grade inflammation associated with various disease states, including obesity, type 2 diabetes, atherosclerosis, Alzheimer's disease, and Parkinson's disease. Emerging evidence, mostly from cell and animal models of disease, supports a role for ketosis in general, and the main circulating ketone body beta-hydroxybutyrate (BHB) in particular, in reducing NLRP3 inflammasome activation to improve chronic inflammation. As a result, interventions that can induce ketosis (e.g., fasting, intermittent fasting, time-restricted feeding/eating, very low-carbohydrate high-fat ketogenic diets) and/or increase circulating BHB (e.g., exogenous ketone supplementation) have garnered increasing interest for their therapeutic potential. The purpose of the present review is to summarize our current understanding of the literature on how ketogenic interventions impact the NLRP3 inflammasome across human, rodent and cell models. Overall, there is convincing evidence that ketogenic interventions, likely acting through multiple interacting mechanisms in a cell-, disease- and context-specific manner, can reduce NLRP3 inflammasome activation. The evidence supports a direct effect of BHB, although it is important to consider the myriad of other metabolic responses to fasting or ketogenic diet interventions (e.g., elevated lipolysis, low insulin, stable glucose, negative energy balance) that may also impact innate immune responses. Future research is needed to translate promising findings from discovery science to clinical application

Acute high-intensity interval exercise reduces human monocyte Toll-like receptor 2 expression in type 2 diabetes

Acute highintensity interval exercise reduces human monocyte Toll-like receptor 2 expression in type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 312: R529 -R538, 2017. First published January 25, 2017; doi:10.1152/ajpregu.00348.2016.-Type 2 diabetes (T2D) is characterized by chronic low-grade inflammation that contributes to disease pathophysiology. Exercise has anti-inflammatory effects, but the impact of high-intensity interval training (HIIT) is not known. The purpose of this study was to determine the impact of a single session of HIIT on cellular, molecular, and circulating markers of inflammation in individuals with T2D. Participants with T2D (n 10) and healthy age-matched controls (HC; n 9) completed an acute bout of HIIT (7 1 min at ~85% maximal aerobic power output, separated by 1 min of recovery) on a cycle ergometer with blood samples obtained before (Pre), immediately after (Post), and at 1 h of recovery (1-h Post). Inflammatory markers on leukocytes were measured by flow cytometry, and TNF- was assessed in both LPS-stimulated whole blood cultures and plasma. A single session of HIIT had an overall anti-inflammatory effect, as evidenced by 1) significantly lower levels of Toll-like receptor (TLR) 2 surface protein expression on both classical and CD16 monocytes assessed at Post and 1-h Post compared with Pre (P 0.05 for all); 2) significantly lower LPSstimulated TNF- release in whole blood cultures at 1-h Post (P 0.05 vs. Pre); and 3) significantly lower levels of plasma TNF- at 1-h Post (P 0.05 vs. Pre). There were no differences between T2D and HC, except for a larger decrease in plasma TNF- in HC vs. T2D (group time interaction, P 0.05). One session of low-volume HIIT has immunomodulatory effects and provides potential antiinflammatory benefits to people with, and without, T2D

Examining the Effect of Consuming C8 Medium-Chain Triglyceride Oil for 14 Days on Markers of NLRP3 Activation in Healthy Humans

Chronic, low-grade inflammation is associated with the development of numerous diseases and is mediated in part by overactivation of the NLRP3 inflammasome. The ketone body beta-hydroxybutyrate (βHB) suppresses the NLRP3 inflammasome and alters intracellular signalling pathways in vitro and in animal models; however, this effect has not yet been shown in vivo in humans. The purpose of this single-arm pilot trial was to determine if consuming 15 mL of C8 medium-chain triglyceride (trioctanoin; MCT) oil, which induces mild elevation of βHB, twice daily (30 mL total) for 14 days would suppress markers of NLRP3 inflammasome activation in young, healthy humans while following their habitual diet. Consuming a single dose of 15 mL of C8 MCT oil significantly raised blood βHB from fasting at 60 minutes and 120 minutes post ingestion (both P0.05). Acetylation of histone H3 on the lysine residue 9 was unchanged (P<0.05) and acetylation of lysine residue 14 was decreased (P<0.05) following 14 days of supplementation. Thus, adding twice daily C8 MCT oil supplementation to the habitual diet of young, healthy humans does not appear to suppress NLRP3 inflammasome activation

The Impact of Acute Ingestion of a Ketone Monoester Drink on LPS-Stimulated NLRP3 Activation in Humans with Obesity

Activation of the NOD-like receptor pyrin-domain containing 3 (NLRP3) inflammasome is associated with chronic low-grade inflammation in metabolic diseases such as obesity. Mechanistic studies have shown that β-hydroxybutyrate (OHB) attenuates activation of NLRP3, but human data are limited. In a randomized, double-blind, placebo-controlled crossover trial (n = 11) we tested the hypothesis that acutely raising β-OHB by ingestion of exogenous ketones would attenuate NLRP3 activation in humans with obesity. Blood was sampled before and 30 min post-ingestion of a ketone monoester drink ((R)-3-hydroxybutyl (R)-3-hydroxybutyrate, 482 mg/kg body mass) or placebo. A 75 g oral glucose load was then ingested, and a third blood sample was obtained 60 min following glucose ingestion. NLRP3 activation was quantified by assessing monocyte caspase-1 activation and interleukin (IL)-1β secretion in ex vivo lipopolysaccharide (LPS)-stimulated whole-blood cultures. LPS-stimulated caspase-1 activation increased following glucose ingestion (main effect of time; p = 0.032), with no differences between conditions. IL-1β secretion did not differ between conditions but was lower 60 min post-glucose ingestion compared to the fasting baseline (main effect of time, p = 0.014). Plasma IL-1β was detectable in ~80% of samples and showed a decrease from fasting baseline to 60 min in the ketone condition only (condition × time interaction, p = 0.01). In individuals with obesity, an excursion into hyperglycemia following ingestion of a glucose load augments LPS-induced activation of caspase-1 in monocytes with no apparent impact of raising circulating β-OHB concentration via ingestion of exogenous ketones. Exogenous ketone supplementation may impact plasma IL-1β, but these findings require confirmation in studies with larger sample sizes.Health and Social Development, Faculty of (Okanagan)Health and Exercise Sciences, School of (Okanagan)ReviewedFacult

Carbohydrate restriction with postmeal walking effectively mitigates postprandial hyperglycemia and improves endothelial function in type 2 diabetes

Postprandial hyperglycemia has deleterious effects on endothelial function. Restricting carbohydrate intake and postmeal walking have each been shown to reduce postprandial hyperglycemia, but their combination and subsequent effects on endothelial function have not been investigated. Here, we sought to examine the effect of blunting postprandial hyperglycemia by following a low-carbohydrate diet, with or without postmeal walking exercise, on markers of vascular health in type 2 diabetes (T2D). In a randomized crossover design, individuals with T2D (n \u3c 11) completed three 4-day controlled diet interventions consisting of 1) low-carbohydrate diet alone (LC), 2) low-carbohydrate diet with 15-min postmeal walks (LC \u3e Ex), and 3) low-fat control diet (CON). Fasting blood samples and brachial artery flow-mediated dilation (%FMD) were measured before and after each intervention. Total circulating microparticles (MPs), endothelial MPs, platelet MPs, monocyte-platelet aggregates, and adhesion molecules were assessed as biomarkers of vascular health. There was a significant condition = time interaction for %FMD (P \u3c 0.01), with post hoc tests revealing improved %FMD after LC \u3e Ex (\u3e0.8 ± 1.0%, P \u3c 0.02), with no change after LC or CON. Endothelial MPs were significantly reduced with the LC diet by ~45% (from 99 ± 60 to 44 ± 31 MPs/μl, P \u3c 0.02), with no change after LC \u3e Ex or CON (interaction: P \u3c 0.04). Total MPs were lower (main effect time: P \u3c 0.02), whereas monocyte-platelet aggregates were higher (main effect time: P = 0.01) after all interventions. Plasma adhesion molecules and C-reactive protein were unaltered. Attenuating postprandial hyperglycemic excursions using a low-carbohydrate diet combined with postmeal walking appears to be an effective strategy to improve endothelial function in individuals with T2D. NEW & NOTEWORTHY Carbohydrate restriction and postmeal walking lower postprandial hyperglycemia in individuals with type 2 diabetes. Here, we show that the combination significantly improved endothelial function and that carbohydrate restriction alone reduced circulating endothelial microparticles in individuals with type 2 diabetes. Listen to this article\u27s corresponding podcast at http://ajpheart.pod-bean.com/e/low-carb-diet-and-exercise-improve-endothelial-health/