Neutrophil-mediated injury to endothelial cells. Enhancement by endotoxin and essential role of neutrophil elastase

J Clin Invest. 1986 Apr;77(4):1233-43. doi: 10.1172/JCI112426.


The neutrophil has been implicated as an important mediator of vascular injury, especially after endotoxemia. This study examines neutrophil-mediated injury to human microvascular endothelial cells in vitro. We found that neutrophils stimulated by formyl-methionyl-leucyl-phenylalanine (FMLP), the complement fragment C5a, or lipopolysaccharide (LPS) (1-1,000 ng/ml) alone produced minimal endothelial injury over a 4-h assay. In contrast, neutrophils incubated with endothelial cells in the presence of low concentrations of LPS (1-10 ng/ml) could then be stimulated by FMLP or C5a to produce marked endothelial injury. Injury was maximal at concentrations of 100 ng/ml LPS and 10(-7) M FMLP. Pretreatment of neutrophils with LPS resulted in a similar degree of injury, suggesting that LPS effects were largely on the neutrophil. Endothelial cell injury produced by LPS-exposed, FMLP-stimulated neutrophils had a time course similar to that induced by the addition of purified human neutrophil elastase, and different from that induced by hydrogen peroxide (H2O2). Further, neutrophil-mediated injury was not inhibited by scavengers of a variety of oxygen radical species, and occurred with neutrophils from a patient with chronic granulomatous disease, which produced no H2O2. In contrast, the specific serine elastase inhibitor methoxy-succinyl-alanyl-alanyl-prolyl-valyl-chloromethyl ketone inhibited 63% of the neutrophil-mediated injury and 64% of the neutrophil elastase-induced injury. However, neutrophil-mediated injury was not inhibited significantly by 50% serum, 50% plasma, or purified alpha 1 proteinase inhibitor. These results suggest that, in this system, chemotactic factor-stimulated human neutrophil injury of microvascular endothelial cells is enhanced by small amounts of LPS and may be mediated in large part by the action of neutrophil elastase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Chloromethyl Ketones / pharmacology
  • Blood
  • Blood Proteins / pharmacology
  • Complement C5 / pharmacology
  • Complement C5a
  • Endothelium / pathology*
  • Endotoxins / pharmacology*
  • Humans
  • Hydrogen Peroxide / metabolism
  • In Vitro Techniques
  • Lipopolysaccharides / pharmacology
  • Microcirculation
  • Microscopy, Electron
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Neutrophils / drug effects
  • Neutrophils / enzymology*
  • Pancreatic Elastase / metabolism*
  • Time Factors
  • Tosyllysine Chloromethyl Ketone / pharmacology
  • alpha 1-Antitrypsin


  • Amino Acid Chloromethyl Ketones
  • Blood Proteins
  • Complement C5
  • Endotoxins
  • Lipopolysaccharides
  • alpha 1-Antitrypsin
  • Tosyllysine Chloromethyl Ketone
  • N-Formylmethionine Leucyl-Phenylalanine
  • methoxysuccinyl-alanyl-alanyl-prolyl-valine chloromethyl ketone
  • Complement C5a
  • Hydrogen Peroxide
  • Pancreatic Elastase