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 4

Refeeding initiates NLRP3 inflammasome priming via NF-κB signaling.

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Refeeding initiates NLRP3 inflammasome priming via NF-κB signaling. (A) ...
(A) Transcript levels encoding TNFA and inflammasome components IL1B, IL18, and NLRP3. Refeeding increases the expression of all the mRNAs (n = 8). (B) Representative protein levels of signaling molecules activating the NLRP3 inflammasome. Increased phosphorylation of NF-κB and IκBα shows their activation in the fed state. The NLRP3 complex component — NLRP3 and IL-1β — levels are also increased in the fed state. The relative quantitative changes (n = 5–7) are shown in C. Note, the refeeding effects on gene transcript, phosphoprotein, and protein levels are evident at baseline and do not require exogenous inflammasome priming. The fasting to 3-hour–refed transcript and steady-state protein levels were analyzed using paired 2-tailed t tests. (D) Serum levels of soluble CD14, as a marker of endotoxin activity (n = 11). (E) Histogram showing changes in IL-1β release from THP-1–derived macrophages supplemented with fasted and refed sera in the presence and absence of the NF-κB pathway inhibitor PS-1145 (n = 11). The inhibition of NF-κB signaling abolished the excess IL-1β secretion using the refed sera, whether it was administered during the serum incubation alone and/or when maintained through the priming and activation of the inflammasome. Statistical testing for changes in IL-1β levels was performed using 2-way ANOVA.