Noradrenergic neurons regulate monocyte trafficking and mortality during gram-negative peritonitis in mice

J Immunol. 2013 May 1;190(9):4717-24. doi: 10.4049/jimmunol.1300027. Epub 2013 Mar 29.

Abstract

Effective host defense requires a robust, yet self-limited response to pathogens. A poorly calibrated response can lead to either bacterial dissemination due to insufficient inflammation or organ injury due to excessive inflammation. Recent evidence suggests that the cholinergic anti-inflammatory reflex helps calibrate the immune response. However, the influence of peripheral noradrenergic neurons, which are primarily sympathetic neurons, in regulating immunity remains incompletely characterized. Using a model of 6-hydroxydopamine-mediated noradrenergic nerve ablation, we show that elimination of noradrenergic neurons improves survival during Klebsiella pneumoniae peritonitis (67 versus 23%, p < 0.005) in mice. The survival benefit results from enhanced MCP-1-dependent monocyte recruitment and a subsequent decrease in bacterial loads. Splenectomy eliminated both the survival benefit of 6-hydroxydopamine and monocyte recruitment, suggesting that monocytes recruited to the peritoneum originate in the spleen. These results suggest that noradrenergic neurons regulate the immune response through two pathways. First, sympathetic nerve-derived norepinephrine directly restrains MCP-1 production by peritoneal macrophages during infection. Second, norepinephrine derived from the vagally innervated splenic nerve regulates splenic monocyte egress. Removal of these two modulators of the immune response enhances antibacterial immunity and improves survival. These results may have implications for how states of catecholamine excess influence the host response to bacterial infections.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adrenergic Neurons / immunology*
  • Adrenergic Neurons / metabolism
  • Adrenergic Neurons / microbiology
  • Animals
  • Cell Movement / immunology
  • Chemokine CCL2 / immunology
  • Chemokine CCL2 / metabolism
  • Cytokines / immunology
  • Cytokines / metabolism
  • Inflammation / immunology
  • Inflammation / metabolism
  • Inflammation / microbiology
  • Klebsiella Infections / immunology*
  • Klebsiella Infections / metabolism
  • Klebsiella Infections / microbiology
  • Klebsiella pneumoniae / immunology*
  • Macrophages / immunology
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Mast Cells / immunology
  • Mast Cells / metabolism
  • Mast Cells / microbiology
  • Mice
  • Mice, Inbred C57BL
  • Monocytes / immunology*
  • Monocytes / metabolism
  • Monocytes / microbiology
  • Peritonitis / immunology*
  • Peritonitis / metabolism
  • Peritonitis / microbiology
  • Spleen / immunology
  • Spleen / metabolism
  • Spleen / microbiology

Substances

  • Ccl2 protein, mouse
  • Chemokine CCL2
  • Cytokines