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 8

NR blunts monocytic type I IFN in healthy volunteers and in monocytes from patients with SLE.

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NR blunts monocytic type I IFN in healthy volunteers and in monocytes fr...
(A) Relative mRNA expression of IFNB, CXCL10, and TNFA in cryopreserved monocytes from healthy volunteers exposed to the placebo or NR for 7 days (n = 8–10 individuals/group). (B) IFN-β and (C) TNF-α production measured by ELISA in parallel from cryopreserved monocytes described in Figure 7A (n = 8 individuals/group). (D) Venn diagram showing 22 overlapping DE genes between controls versus SLE (GSE131525) and placebo versus NR comparison (this study). (E) Heatmap on relative levels of 13 overlapping DE genes that were downregulated by NR. (F) A box plot of NAD+ concentration for the indicated SLEDAI score on the x axis is depicted. The dot/circle on each box plot represents individual NAD+ measurement for the indicated SLEDAI score. A trend line was generated using LOESS (locally estimated scatter plot smoothing). (G) IFN-β production induced by LPS (10 ng/mL for 6 hours) was measured by ELISA in monocytes from patients with SLE with different disease activity (inactive: SLEDAI ≤4; active: SLEDAI >4) that incubated with vehicle or NR for 16 hours (n = 17 for SLE inactive group; n = 16 for SLE active group). (H) Levels of NAD+, NMN, and ADPR from whole blood of healthy volunteers (HV) and patients with SLE measured by LC-MS (n = 16 for HV group; n = 19 for SLE group). (I) Representative immunoblot and quantification of LC3-II in SLE monocytes incubated with vehicle or NR for 16 hours and then stimulated with LPS (10 ng/mL) for 2 hours. Data were analyzed by unpaired 2-tailed Student’s t test (A–C, H, and I) or paired 2-tailed Student’s t test (G). All data represented as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001.