title: Hypertonic saline up-regulates A3 adenosine receptor expression of activated neutrophils and increases acute lung injury after sepsis.
abstract: OBJECTIVE
  Hypertonic saline resuscitation reduces tissue damage by inhibiting polymorphonuclear neutrophils. Hypertonic saline triggers polymorphonuclear neutrophils to release adenosine triphosphate that is converted to adenosine, inhibiting polymorphonuclear neutrophils through A2a adenosine receptors. Polymorphonuclear neutrophils also express A3 adenosine receptors that enhance polymorphonuclear neutrophil functions. Here we investigated whether A3 receptors may diminish the efficacy of hypertonic saline in a mouse model of acute lung injury.
  
  
  METHODS
  Randomized animal study and laboratory investigation.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  The effect of A3 receptors on the efficacy of hypertonic saline resuscitation was assessed in A3 receptor knockout and wild-type mice. Animals were treated with hypertonic saline (7.5% NaCl, 4 mL/kg) before or after cecal ligation and puncture, and acute lung injury and mortality were determined. The effect of timing of hypertonic saline exposure on A3 receptor expression and degranulation was studied in vitro with isolated human polymorphonuclear neutrophils.
  
  
  RESULTS
  Treatment of human polymorphonuclear neutrophils with hypertonic saline before stimulation with formyl methionyl-leucyl-phenylalanine inhibited A3 receptor expression and degranulation, whereas hypertonic saline-treatment after formyl methionyl-leucyl-phenylalanine-stimulation augmented A3 receptor expression and degranulation. Acute lung injury in wild-type mice treated with hypertonic saline after cecal ligation and puncture was significantly greater than in wild-type mice pretreated with hypertonic saline. This aggravating effect of delayed hypertonic saline-treatment was absent in A3 receptor knockout mice. Similarly, mortality in wild-type mice with delayed hypertonic saline-treatment was significantly higher (88%) than in animals treated with hypertonic saline before cecal ligation and puncture (50%). Mortality in A3 receptor knockout mice remained only 50% regardless of timing of hypertonic saline administration.
  
  
  CONCLUSIONS
  Polymorphonuclear neutrophil A3 receptors expression determines whether hypertonic saline resuscitation inhibits or aggravates polymorphonuclear neutrophil-induced acute lung injury. These findings suggest that A3 antagonists could improve the efficacy of hypertonic saline resuscitation by reducing side effects in patients whose polymorphonuclear neutrophils are activated before hypertonic saline treatment.
authors.affiliation: Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Reinhard
authors.initials: R
authors.lastname: Pauzenberger
authors.forename: Mark I
authors.initials: MI
authors.lastname: Hirsh
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Junger
mesh_terms: D000818:Animals; D015550:Cell Degranulation; D006801:Humans; D008168:Lung / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism / Q000502:physiology*; D010196:Pancreatic Elastase / Q000378:metabolism; D010529:Peritoneal Cavity; D009195:Peroxidase / Q000378:metabolism; D011897:Random Allocation; D043684:Receptor, Adenosine A3 / Q000096:biosynthesis*; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000378:metabolism*; D012462:Saline Solution, Hypertonic / Q000009:adverse effects*; D018805:Sepsis / Q000150:complications*; D013997:Time Factors
chemical_list: D043684:Receptor, Adenosine A3; D012462:Saline Solution, Hypertonic; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009195:Peroxidase; D010196:Pancreatic Elastase