The Circadian Clock Controls Immune Checkpoint Pathway in Sepsis

Cell Rep. 2018 Jul 10;24(2):366-378. doi: 10.1016/j.celrep.2018.06.026.


Sepsis and septic shock are associated with life-threatening organ dysfunction caused by an impaired host response to infections. Although circadian clock disturbance impairs the early inflammatory response, its impact on post-septic immunosuppression remains poorly elucidated. Here, we show that Bmal1, a core circadian clock gene, plays a role in the regulation of host immune responses in experimental sepsis. Mechanistically, Bmal1 deficiency in macrophages increases PKM2 expression and lactate production, which is required for expression of the immune checkpoint protein PD-L1 in a STAT1-dependent manner. Consequently, targeted ablation of Pkm2 in myeloid cells or administration of anti-PD-L1-neutralizing antibody or supplementation with recombinant interleukin-7 (IL-7) facilitates microbial clearance, inhibits T cell apoptosis, reduces multiple organ dysfunction, and reduces septic death in Bmal1-deficient mice. Collectively, these findings suggest that the circadian clock controls the immune checkpoint pathway in macrophages and therefore represents a potential therapeutic target for lethal infection.

Keywords: Bmal1; IL-7; Pd-l1; Pkm2; Stat1; checkpoint; circadian clock; macrophages; metabolism; sepsis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ARNTL Transcription Factors / metabolism
  • Animals
  • B7-H1 Antigen / metabolism
  • Circadian Clocks*
  • Humans
  • Lactates / metabolism
  • Macrophage Activation
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Monocytes / metabolism
  • Myeloid Cells / metabolism
  • Phenotype
  • Pyruvate Kinase / metabolism
  • STAT1 Transcription Factor / metabolism
  • Sepsis / immunology*
  • Sepsis / physiopathology*
  • THP-1 Cells
  • Up-Regulation


  • ARNTL Transcription Factors
  • Arntl protein, mouse
  • B7-H1 Antigen
  • Cd274 protein, mouse
  • Lactates
  • STAT1 Transcription Factor
  • Pkm protein, mouse
  • Pyruvate Kinase