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 6

A SIRT3 agonist blunts inflammasome activation and improves mitochondrial function.

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A SIRT3 agonist blunts inflammasome activation and improves mitochondria...
(A) Evaluation of IL-1β release in response to inflammasome activation in control and SIRT3 siRNA–treated THP-1–derived macrophages to assess the effect of NR on IL-1β secretion in the presence of SIRT3 or its depletion (n = 4). (B) Flow diagram of studies performed on blood draw from the normal volunteer blood draw protocol. (C–H) NR administration to PBMCs from healthy volunteers to evaluate the effect on (C) inflammasome induction–mediated IL-1β secretion (n = 8), (D and E) SIRT3 substrate acetylation levels (n = 6), (F) mitochondrial superoxide dismutase activity (n = 6), and (G and H) ATP-induced mitochondrial ROS levels (n = 3). (I and J) NR effect on PBMCs extracted in the refed state, showing an augmentation of maximal respiratory capacity. A representative oxygen consumption rate (OCR) tracing and a histogram are shown, including the data from all the subject cells studied (n = 5). Maximal respiration was assessed in response to dinitrophenol (DNP) and proton leak as the difference in oxygen consumption between inhibition of ATP synthase with oligomycin and the inhibition of mitochondrial respiration with antimycin A (Ant) and rotenone (Rot). Statistical analyses of experiments in this figure were performed using paired 2-tailed t tests.