Interleukin-1 beta-induced neutrophil recruitment and acute lung injury in hamsters.

Administering recombinant interleukin-1 beta (IL-1 beta) intratracheally caused lung neutrophil accumulation and lung injury in hamsters. The percentage of leukocytes that were neutrophils increased progressively in lavages from lungs of hamsters given 25, 50, or 100 ng IL-1 beta intratracheally 2 h before. Lung injury, reflected by increased lung lavage protein concentrations and lung lavage hemoglobin concentrations, increased 2 h after administering 100 ng IL-1 beta. Lung injury, reflected by lung wet weight/body weight ratios, followed similar patterns, with significant increases occurring 2 h after insufflating 50 or 100 ng IL-1. Our results indicate that increased concentrations of IL-1 beta in lung airways can cause neutrophil recruitment and lung injury in hamsters. This mechanism may contribute to the development of lung neutrophil accumulation and lung injury that characterizes ARDS patients who have increased airway levels of IL-1 beta.

Interleukin-1-induced lung neutrophil accumulation and oxygen metabolite-mediated lung leak in rats.

We found that intratracheal administration of recombinant interleukin-1 alpha (IL-1) into rats rapidly (< 5 h) increased neutrophils in lung lavages and caused an acute edematous lung injury which was reflected by lung albumin accumulation (lung leak) and histological abnormalities (perivascular cuffing). These IL-1-dependent processes were inhibited by prior administration of recombinant IL-1 receptor antagonist and did not occur following administration of heated IL-1. Several lines of evidence suggested that neutrophil-derived oxygen metabolites contributed to lung leak. First, lung leak did not occur in rats rendered neutropenic by vinblastine treatment 4 days before IL-1 administration but did occur in neutrophil-replete rats given vinblastine 1 day before IL-1 administration and control rats given IL-1. Second, treatment with a hydroxyl radical scavenger, dimethyl sulfoxide (DMSO) or a superoxide anion scavenger, manganese superoxide dismutase, decreased lung leak, lung lavage neutrophils, and histological abnormalities in rats given IL-1 intratracheally. Third, intratracheal IL-1 administration increased lung oxidized glutathione (GSSG) levels and expired H2O2 concentrations, and these two indices of oxidative stress were decreased by dimethyl sulfoxide or manganese superoxide dismutase treatment. We conclude that intratracheal administration of IL-1 increases neutrophils in the lung and causes a neutrophil and oxygen metabolite-dependent acute edematous lung injury.

Activity assays for characterizing the thrombolytic protein fibrolase.

Characterization of the thrombolytic agent fibrolase was accomplished employing specific proteolytic and thrombolytic assays. This paper describes a method to measure enzyme proteolytic activity using the oxidized beta-chain of insulin as a substrate. Advantages of this method include a short incubation time for substrate cleavage followed by an isocratic HPLC method with a retention time of approx. 5 min. Proteolytic activity can be rapidly and easily quantitated with this procedure. An azocasein assay was also used to quantitate proteolytic activity. This method was optimized with respect to substrate concentration and incubation time allowing for the rapid quantitation of fibrolase activity. A thrombolytic assay is described which employs fibrin plate clearance and has the advantage of rapid and accurate quantitation compared with previously described methods. It also allows for the standardization of fibrolase in plasmin-equivalent units.

In vivo evaluation of MDL 201,404YA, a novel inhibitor of human neutrophil elastase.

MDL 201,404YA (alternatively, CE-1037), a potent selective inhibitor of human neutrophil elastase (HNE), was tested both intratracheally and intravenously for its activity at inhibiting HNE. MDL 201,404YA given either i.t. or i.v. was effective in preventing the pulmonary hemorrhage which occurred after intratracheal instillation of HNE. Additional studies with MDL 201,404YA suggested that this compound remained active in the lung environment for at least 6 hours. Further evaluation of MDL 201,404YA suggested that it could inhibit the ongoing proteolysis caused by HNE when given 15 minutes after the initial HNE challenge. These data suggest that MDL 201,404YA may be effective therapeutically in treating conditions which result from an imbalance between elastase and its endogenous inhibitor alpha-1-proteinase inhibitor (alpha 1-PI).

Dimethyl sulfoxide decreases lung neutrophil sequestration and lung leak.

To investigate basic mechanisms of acute edematous lung injury (adult respiratory distress syndrome), the formylated tripeptide formyl-norleucyl-leucyl-phenylalanine (FNLP) was instilled intratracheally into hamsters. Intratracheal FNLP produced time-dependent and dose-dependent increases in neutrophils recoverable by lung lavage (neutrophil alveolitis) and leak of intravenously injected albumin into the extravascular lung space (lung leak). Treatment with dimethyl sulfoxide (DMSO) decreased (p less than 0.05) neutrophil alveolitis and lung leak in hamsters given FNLP intratracheally. The effect of DMSO on various neutrophil functions was also studied in vitro. Addition of DMSO at concentrations (about 0.20%) measured in plasma of hamsters given DMSO decreased (p less than 0.05) neutrophil chemotaxis but not neutrophil superoxide anion generation or adherence to cultured endothelial cell monolayers or nylon fiber in vitro. We conclude that intratracheal FNLP causes neutrophil alveolitis and lung leak and that DMSO treatment ameliorates these processes, possibly by inhibiting neutrophil chemotaxis.