Fasting and refeeding differentially regulate NLRP3 inflammasome activation in human subjects
Javier Traba, … , Richard M. Siegel, Michael N. Sack
Javier Traba, … , Richard M. Siegel, Michael N. Sack
Published November 3, 2015
Citation Information: J Clin Invest. 2015;125(12):4592-4600. https://doi.org/10.1172/JCI83260.
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Clinical Research and Public Health Metabolism

Fasting and refeeding differentially regulate NLRP3 inflammasome activation in human subjects

Abstract

BACKGROUND. Activation of the NLRP3 inflammasome is associated with metabolic dysfunction, and intermittent fasting has been shown to improve clinical presentation of NLRP3 inflammasome–linked diseases. As mitochondrial perturbations, which function as a damage-associated molecular pattern, exacerbate NLRP3 inflammasome activation, we investigated whether fasting blunts inflammasome activation via sirtuin-mediated augmentation of mitochondrial integrity.

METHODS. We performed a clinical study of 19 healthy volunteers. Each subject underwent a 24-hour fast and then was fed a fixed-calorie meal. Blood was drawn during the fasted and fed states and analyzed for NRLP3 inflammasome activation. We enrolled an additional group of 8 healthy volunteers to assess the effects of the sirtuin activator, nicotinamide riboside, on NLRP3 inflammasome activation.

RESULTS. In the fasting/refeeding study, individuals showed less NLRP3 inflammasome activation in the fasted state compared with that in refed conditions. In a human macrophage line, depletion of the mitochondrial-enriched sirtuin deacetylase SIRT3 increased NLRP3 inflammasome activation in association with excessive mitochondrial ROS production. Furthermore, genetic and pharmacologic SIRT3 activation blunted NLRP3 activity in parallel with enhanced mitochondrial function in cultured cells and in leukocytes extracted from healthy volunteers and from refed individuals but not in those collected during fasting.

CONCLUSIONS. Together, our data indicate that nutrient levels regulate the NLRP3 inflammasome, in part through SIRT3-mediated mitochondrial homeostatic control. Moreover, these results suggest that deacetylase-dependent inflammasome attenuation may be amenable to targeting in human disease.

TRIAL REGISTRATION. ClinicalTrials.gov NCT02122575 and NCT00442195.

FUNDING. Division of Intramural Research, NHLBI of the NIH.

Authors

Javier Traba, Miriam Kwarteng-Siaw, Tracy C. Okoli, Jessica Li, Rebecca D. Huffstutler, Amanda Bray, Myron A. Waclawiw, Kim Han, Martin Pelletier, Anthony A. Sauve, Richard M. Siegel, Michael N. Sack

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Figure 5

SIRT3 levels modify NLRP3 activation and acetylation of SOD2.

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SIRT3 levels modify NLRP3 activation and acetylation of SOD2. (A) Repres...
(A) Representative immunoblot of steady-state levels of SIRT1, SIRT2, SIRT3, and SIRT5 following the siRNA knockdown of each isoform in THP-1 cells. The relative changes represent the values from 3 separate experiments. (B) IL-1β release in response to inflammasome activation in the sirtuin knockdown THP-1 cells (n = 11). (C) Inflammasome activation with wild-type and deacetylase mutant SIRT3 overexpression in THP-1 cells (n = 4). *P < 0.05. (D) Mitochondrial superoxide dismutase activity in PBMC mitochondria isolated in the fasted and fed states (n = 4). (E) Representative immunoblot analysis of relative SOD2 protein acetylation on K68 in the fed and fasted states. The relative quantitative change in SOD2 acetylation is shown in F (n = 4). (G) Histogram showing relative release of IL-1β in control and SIRT3-overexpressing cells in response to inflammasome activation in the absence of or presence of ROS inhibition with mitoTEMPO and DPI (n = 5). (H) Histogram showing the same studies as performed in F, with the exception of testing the effect of SIRT3 knockdown rather than overexpression (n = 5). Statistical analysis of changes in IL-1β secretion levels was performed using 2-way ANOVA and analysis of changes in SOD2 activity and acetylation was performed using a paired 2-tailed t test.