Boosting NAD+ blunts TLR4-induced type I IFN in control and systemic lupus erythematosus monocytes
Jing Wu, Komudi Singh, Amy Lin, Allison M. Meadows, Kaiyuan Wu, Vivian Shing, Maximilian Bley, Shahin Hassanzadeh, Rebecca D. Huffstutler, Mark S. Schmidt, Luz P. Blanco, Rong Tian, Charles Brenner, Mehdi Pirooznia, Mariana J. Kaplan, Michael N. Sack
Jing Wu, Komudi Singh, Amy Lin, Allison M. Meadows, Kaiyuan Wu, Vivian Shing, Maximilian Bley, Shahin Hassanzadeh, Rebecca D. Huffstutler, Mark S. Schmidt, Luz P. Blanco, Rong Tian, Charles Brenner, Mehdi Pirooznia, Mariana J. Kaplan, Michael N. Sack
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Clinical Research and Public Health Inflammation Metabolism

Boosting NAD+ blunts TLR4-induced type I IFN in control and systemic lupus erythematosus monocytes

Abstract

BACKGROUND Fasting and NAD+-boosting compounds, including NAD+ precursor nicotinamide riboside (NR), confer antiinflammatory effects. However, the underlying mechanisms and therapeutic potential are incompletely defined.METHODS We explored the underlying biology in myeloid cells from healthy volunteers following in vivo placebo or NR administration and subsequently tested the findings in vitro in monocytes extracted from patients with systemic lupus erythematosus (SLE).RESULTS RNA-Seq of unstimulated and LPS-activated monocytes implicated NR in the regulation of autophagy and type I IFN signaling. In primary monocytes, NR blunted LPS-induced IFN-β production, and genetic or pharmacological disruption of autophagy phenocopied this effect. Given that NAD+ is a coenzyme in oxidoreductive reactions, metabolomics was performed and identified that NR increased the inosine level. Inosine supplementation similarly blunted autophagy and IFN-β release. Finally, because SLE exhibits type I IFN dysregulation, we assessed the NR effect on monocytes from patients with SLE and found that NR reduced autophagy and IFN-β release.CONCLUSION We conclude that NR, in an NAD+-dependent manner and in part via inosine signaling, mediated suppression of autophagy and attenuated type I IFN in myeloid cells, and we identified NR as a potential adjunct for SLE management.TRIAL REGISTRATION ClinicalTrials.gov registration numbers NCT02812238, NCT00001846, and NCT00001372.FUNDING This work was supported by the NHLBI and NIAMS Intramural Research divisions.

Authors

Jing Wu, Komudi Singh, Amy Lin, Allison M. Meadows, Kaiyuan Wu, Vivian Shing, Maximilian Bley, Shahin Hassanzadeh, Rebecca D. Huffstutler, Mark S. Schmidt, Luz P. Blanco, Rong Tian, Charles Brenner, Mehdi Pirooznia, Mariana J. Kaplan, Michael N. Sack

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Figure 2

Bioinformatic characterization of RNA-Seq data.

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Bioinformatic characterization of RNA-Seq data. (A) Pathway enrichment r...
(A) Pathway enrichment results showing top 10 DE gene pathways modulated by NR in response to LPS stimulation. The x axis represents negative log10-transformed q values where bar plot color is scaled to transformed q values. (B) Volcano plot showing all the genes from the refed placebo versus NR comparison after LPS activation. The statistically significant type I IFN genes are highlighted in red circles and labeled. (C) GeneMANIA consolidated pathway network analysis shows IFN pathway genes (circular nodes) connected to the indicated pathway hubs (diamond-shaped node). The fold-change information is overlaid on this network. NR-linked downregulated genes are represented as blue nodes and the upregulated genes as red nodes. (D) Quantitative RT-PCR analysis of type 1 IFN pathway–related genes in monocytes from healthy volunteers taking a placebo or NR for 7 days (n = 7–8 individuals/group). Data were normalized to 18S rRNA and are represented as mean ± SEM. *P < 0.05. Unpaired 2-tailed Student’s t test.