9-10-epoxy-12-octadecenoate and Respiratory-Distress-Syndrome

Topics: Adult; Burns; Female; Humans; Linoleic Acids; Male; Middle Aged; Respiratory Distress Syndrome; Toxins, Biological

It is well known that pulmonary influx of neutrophils is involved in lung injury in patients with adult respiratory distress syndrome (ARDS). Neutrophils are major contributors to the self-defence mechanism, however, adverse effects of neutrophils have also been recognized. Recently, we found that a highly toxic substance, 9, 10-epoxy-12-octadecenoate (leukotoxin) is biosynthesized by human neutrophils. This study was designed to investigate whether or not leukotoxin participates in lung injury in ARDS and coagulation abnormality which is often associated with ARDS. Intravenous injection of leukotoxin (100 mumol/kg) caused acute edematous lung injury, which was evidenced by increased lung weight, albumin concentrations, and angiotensin converting enzyme activities in lung lavages. Pulmonary capillary endothelial damage and pulmonary edema were observed by electron microscopy. Moreover, considerable amounts of leukotoxin were detected in lung lavage fluid of rats exposed to pure oxygen for 60 h and patients with ARDS. An increased number of neutrophils and albumin concentrations were also observed in these lavage fluids. Intravenous injection of leukotoxin (100 mumol/kg) induced coagulation abnormalities such as disseminated intravascular coagulation. Increased levels of plasma leukotoxin were detected in ARDS patients with coagulation abnormalities. These results suggest that leukotoxin biosynthesized by neutrophils is an important contributor to lung injury in ARDS and associated coagulation abnormalities.

Topics: Albumins; Animals; Bronchoalveolar Lavage Fluid; Humans; Linoleic Acids; Neutrophils; Peptidyl-Dipeptidase A; Rats; Respiratory Distress Syndrome

In spite of the development of various antibiotics, management of elderly patients with pneumonia remains an important problem. It is suggested that adult respiratory distress syndrome (ARDS) and disseminated intravascular coagulation (DIC) often occur in elderly patients with pneumonia. Although neutrophils are suggested to be involved in the genesis of these conditions, details remain unknown. We demonstrated that a highly cytotoxic substance, 9,10-epoxy-12-octadecenoate, is biosynthesized from linoleate by human neutrophils, thus it was named leukotoxin. Leukotoxin was detected in lung lavages from patients with ARDS. In these lung lavages, increases in albumin concentration and angiotensin converting enzyme (ACE) activity were also observed. Similar results were observed in lung lavages from rats after exposure to hyperoxia for 60 hours in an experimental model of ARDS. Intravenous administration of leukotoxin (100 mumol/kg) caused lung edema. Albumin concentration and ACE activity were increased in lung lavages of rats receiving leukotoxin. In contrast, these changes were not observed in rats administered with linoleate. Furthermore, administration of leukotoxin (100 mumol/kg) caused coagulation abnormality, i.e., increase in fibrin-fibrinogen degradation products, decrease in fibrinogen, and prolongation of activated partial thromboplastin time and prothrombin time. Administration of linoleate did not induce these changes. It is indicated that O2- was produced by respiratory burst enzyme located in neutrophil plasma membrane, and that hydroxyl radicals derived from O2- by Fenton reaction were responsible for leukotoxin synthesis. From our results, leukotoxin, a product of hydroxyl radicals and linoleate, might be responsible for the genesis of ARDS and DIC.

Topics: Adult; Aged; Analysis of Variance; Animals; Bronchoalveolar Lavage Fluid; Chemical Phenomena; Chemistry; Disseminated Intravascular Coagulation; Female; Humans; Linoleic Acids; Lung; Male; Middle Aged; Neutrophils; Rats; Rats, Inbred Strains; Respiratory Distress Syndrome

Topics: Animals; Aorta; Blood Pressure; Dogs; Hemodynamics; Humans; Leukocytes; Linoleic Acids; Regional Blood Flow; Respiratory Distress Syndrome; Toxins, Biological

Pulmonary influxed neutrophils have been suggested to be involved in the development of hyperoxia-induced lung injury. We recently revealed that a highly toxic substance, 9,10-epoxy-12-octadecenoate, is biosynthesized by human neutrophils, thus it was named leukotoxin. Because hyperoxia-induced lung injury is a model of adult respiratory distress syndrome (ARDS), this study was designed to investigate whether or not leukotoxin is involved in the genesis of pulmonary oxygen toxicity and ARDS. After exposure to hyperoxia for 60 h, rats showed acute pulmonary edema, which was evidenced by increased lung weight, albumin concentrations, and angiotensin-converting enzyme (ACE) activities in lung lavages. These changes were correlated with an increased number of neutrophils. We detected leukotoxin in lung lavages of rats after exposure to hyperoxia for 60 h by high performance liquid chromatography and gas-chromatography/mass spectrometry. After intravenous injection of leukotoxin (100 mumol/kg) to rats, acute edematous lung injury occurred showing increases in lung weight, lung lavage albumin concentrations, and lung lavage ACE activities. In the lung lavages obtained from 5 patients with ARDS, significant increases in albumin concentrations and ACE activities were observed compared with those from subjects without pulmonary disease. Moreover, considerable amounts of leukotoxin, 38.5 +/- 21.9 nmol/lung lavage, were observed in the lavages from patients with ARDS. These findings suggest that leukotoxin plays an important role in the genesis of acute edematous lung damage in pulmonary oxygen toxicity, and that leukotoxin also links with the development of lung injury observed in patients with ARDS.

Topics: Animals; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Exotoxins; Female; Humans; Leukocyte Count; Linoleic Acids; Neutrophils; Oxygen; Pulmonary Edema; Rats; Rats, Inbred Strains; Respiratory Distress Syndrome