C/EBPε mediates nicotinamide-enhanced clearance of Staphylococcus aureus in mice
Pierre Kyme, … , H. Phillip Koeffler, George Y. Liu
Pierre Kyme, … , H. Phillip Koeffler, George Y. Liu
Published August 27, 2012
Citation Information: J Clin Invest. 2012;122(9):3316-3329. https://doi.org/10.1172/JCI62070.
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Research Article Infectious disease

C/EBPε mediates nicotinamide-enhanced clearance of Staphylococcus aureus in mice

Abstract

The myeloid-specific transcription factor, CCAAT/enhancer-binding protein ε (C/EBPε) is a critical mediator of myelopoiesis. Mutation of this gene is responsible for neutrophil-specific granule deficiency in humans, a condition that confers susceptibility to Staphylococcus aureus infection. We found that C/EBPε-deficient mice are severely affected by infection with S. aureus, and C/EBPε deficiency in neutrophils contributes to the infectious phenotype. Conversely, exposure to the epigenetic modulator nicotinamide (vitamin B3) increased expression of C/EBPε in WT myeloid cells. Further, nicotinamide increased the activity of C/EBPε and select downstream antimicrobial targets, particularly in neutrophils. In a systemic murine infection model as well as in murine and human peripheral blood, nicotinamide enhanced killing of S. aureus by up to 1,000 fold but had no effect when administered to either C/EBPε-deficient mice or mice depleted of neutrophils. Nicotinamide was efficacious in both prophylactic and therapeutic settings. Our findings suggest that C/EBPε is an important target to boost killing of bacteria by the innate immune system.

Authors

Pierre Kyme, Nils H. Thoennissen, Ching Wen Tseng, Gabriela B. Thoennissen, Andrea J. Wolf, Kenichi Shimada, Utz O. Krug, Kunik Lee, Carsten Müller-Tidow, Wolfgang E. Berdel, W. David Hardy, Adrian F. Gombart, H. Phillip Koeffler, George Y. Liu

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Figure 3

NAM augments killing of S. aureus by a C/EBPε-dependent mechanism.

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NAM augments killing of S. aureus by a C/EBPε-dependent mechanism. (A)...
(A) Effect of NAM on clearance of S. aureus by human blood. Human blood (n = 4) was pretreated with NAM or PBS for 24 hours and inoculated with S. aureus (6.5 × 103 CFU/ml). The number to the right of the blot indicates fold change compared with ACTB. (B) NAM does not have direct antistaphylococcal activity. S. aureus (~104 CFU/ml) was treated with NAM or THB. (C) Effect of ex vivo NAM treatment on viability of human myeloid cells. Human blood (n = 5) was treated ex vivo with PBS or 1 mM NAM, and CBC was performed to determine the absolute (ABS) neutrophil and monocyte count for each volunteer at 0 and 24 hours. (D) Effect of NAM on clearance of S. aureus by murine blood. Blood from WT and Cebpe–/– mice (n = 6/group) was treated with NAM or PBS for 24 hours and then inoculated with S. aureus (~104 CFU/ml). Images show CFUs after 3 hours. (E) Effect of NAM on in vivo clearance of S. aureus. WT (n = 9) or Cebpe–/– mice (n = 7) were treated daily with NAM or PBS, beginning 24 hours prior to i.p. S. aureus (~107 CFUs) infection. CFU counts in WT and Cebpe–/– mice at 48 hours p.i. Dashed lines indicate limit of detection. One out of seven Cebpe–/– mice from each treatment group died and were excluded from analysis. (A, B, and D) Data are mean ± SEM. (C and D) Red bars indicate mean. Symbols indicate individual samples. *P < 0.05; **P < 0.01; ***P < 0.001.