muramidase and Respiratory-Distress-Syndrome

Macrophages have a wide variety of activities and it is largely unknown how the diverse phenotypes of macrophages contribute to pathological conditions in the different types of tissue injury in vivo. In this study we established a novel animal model of acute respiratory distress syndrome caused by the dysfunction of alveolar epithelial type II (AE2) cells and examined the roles of alveolar macrophages in the acute lung injury. The human diphtheria toxin (DT) receptor (DTR), heparin-binding epidermal growth factor-like growth factor (HB-EGF), was expressed under the control of the lysozyme M (LysM) gene promoter in the mice. When DT was administrated to the mice they suffered from acute lung injury and died within 4 days. Immunohistochemical examination revealed that AE2 cells as well as alveolar macrophages were deleted via apoptosis in the mice treated with DT. Consistent with the deletion of AE2 cells, the amount of surfactant proteins in bronchoalveolar lavage fluid was greatly reduced in the DT-treated transgenic mice. When bone marrow from wild-type mice was transplanted into irradiated LysM-DTR mice, the alveolar macrophages became resistant to DT but the mice still suffered from acute lung injury by DT administration. Compared with the mice in which both AE2 cells and macrophages were deleted by DT administration, the DT-treated LysM-DTR mice with DT-resistant macrophages showed less severe lung injury with a reduced amount of hepatocyte growth factor in bronchoalveolar lavage fluid. These results indicate that macrophages play a protective role in noninflammatory lung injury caused by the selective ablation of AE2 cells.

Topics: Animals; Cytokines; Diphtheria Toxin; Heparin-binding EGF-like Growth Factor; Hepatocyte Growth Factor; Humans; Hyaluronan Receptors; In Situ Nick-End Labeling; Intercellular Signaling Peptides and Proteins; Lung; Macrophages, Alveolar; Mice; Mice, Inbred C57BL; Mice, Transgenic; Muramidase; Pulmonary Alveoli; Receptors, Cell Surface; Respiratory Distress Syndrome

Although prolonged Gram-negative sepsis with high permeability alveolar edema, a well documented cause of adult respiratory distress syndrome, has been shown to result in surfactant alterations, the effects of acute endotoxemia on the lung surfactant system are largely unknown. In this study, lethal endotoxemia (> 80% mortality at 24 h) resulting in severe, rapid leukopenia with progressive thrombocytopenia was achieved through intraperitoneal injection of adult Fischer 344 rats with 3.5 mg of Escherichia coli endotoxin/kg. After assessment of pulmonary mechanics under general anesthesia, endotoxin-injected rats and appropriate controls were killed at 4, 8, and 12 h for morphological and biochemical analyses. Morphometric estimation of surfactant membrane subtypes in bronchoalveolar lavage fluid revealed prominent alterations including significant decrease (45%) in tubular myelin 12 h post-endotoxin, with a threefold increase in lamellar body-like forms at 8 and 12 h. Acute endotoxicosis resulted in decrease of total dynamic compliance, whereas pulmonary resistance remained unchanged. These changes were associated with margination of polymorphonuclear leukocytes in lung microcirculation, multifocal septal edema, and decrease in lamellar body lysozyme specific activity at 12 h. Alveolar edema, as determined by measurement of total protein in cell-free bronchoalveolar lavage fluid, was absent in both controls and endotoxin-injected rats. The results indicate that bloodborne lung injury induced by lethal endotoxicosis initiates acute perturbation of secreted surfactant membranes with pulmonary dysfunction in the absence of high protein alveolar edema.

Topics: Acute Disease; Animals; Biological Products; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Endotoxins; Lung; Male; Muramidase; Myelin Sheath; Proteins; Pulmonary Surfactants; Rats; Rats, Inbred F344; Respiratory Distress Syndrome; Toxemia; Tumor Necrosis Factor-alpha

The role of lipoxygenase metabolites in the pathogenesis of endotoxin (LPS)-induced lung injury remains to be clarified. We investigated the contribution of peptide leukotrienes to LPS-induced acute lung injury using a potent antagonist, ONO-1078 (ONO). Experimental groups consisted of a saline group (n = 10), an LPS group (n = 9) injected intravenously with 2 mg E. coli LPS, an ONO group (n = 8) receiving 30 mg/kg of intraperitoneal ONO, and an LPS+ONO group (n = 6) receiving 30 mg/kg of ONO intraperitoneally 10 min before the LPS injection. The [125I]albumin lung plasma ratio, which is a parameter of acute lung injury, was significantly increased (p < 0.01) in the LPS group compared with the saline, ONO, and LPS+ONO groups. The [125I]albumin BAL fluid plasma ratio was also increased (p < 0.01) in the LPS group compared with the other groups. ONO pretreatment attenuated the LPS-induced increases in neutrophil counts in the BAL fluid. In vitro studies showed that ONO suppresses the neutrophil chemotaxis induced by LTB4, zymosan-activated serum, and FMLP. We conclude that (1) ONO-1078 attenuates LPS-induced acute lung injury; and (2) this effect appears mainly a result of its potent antagonistic actions against peptide leukotrienes and also, in part, the suppression of neutrophil chemotaxis.

Topics: Albumins; Animals; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Chromones; Endotoxins; Escherichia coli; Female; Guinea Pigs; Leukocyte Count; Lipopolysaccharides; Lung; Muramidase; Neutrophils; Organ Size; Respiratory Distress Syndrome; SRS-A; Superoxides

The activity of NAG, lysozyme and PMN-elastase has been investigated in the superior vena caval and left atrium blood collected from patients who underwent open heart surgery. The effect of various types of respiration on the enzyme release has been also documented. Concentration gradients between v. cava sup. and left atrium has been used as an index for pulmonary damage post operatively. We found a time dependent increase of all enzymes during extracorporeal circulation. However, only the release of NAG and lysozyme is characteristic for pulmonary damage. We observed significant higher enzyme release from the lung after Apnea ventilation compared with the PEEP and low frequency ventilation group. Also significant higher NAG and lysozyme activity was found in patients who needed longer respiration post-operatively. PMN-elastase seems to be not suitable for diagnosis of post perfusion lung because the main amount of elastase released by mechanical destroy of the granulocytes.

Topics: Acetylglucosaminidase; Cardiac Surgical Procedures; Cardiopulmonary Bypass; Humans; Lysosomes; Muramidase; Neutrophils; Pancreatic Elastase; Respiration, Artificial; Respiratory Distress Syndrome

Hydrogen peroxide levels were measured in the breath condensate of 43 patients receiving mechanical ventilation. In 16 patients the mean breath condensate peroxide level was 1.68 +/- 0.35 mumol/l on the day they met diagnostic criteria for adult respiratory distress syndrome (ARDS). The peak breath condensate peroxide level in the 27 patients in whom ARDS did not develop was significantly lower (0.34 +/- 0.08 mumol/l). Plasma lysozyme, a measure of in-vivo neutrophil turnover, was significantly higher in ARDS than in non-ARDS patients (9.2 +/- 2.2 U/ml v 3.4 +/- 1.1 U/ml). These findings support the hypothesis that neutrophil activation and oxidant production are involved in the pathogenesis of ARDS.

Topics: Breath Tests; Humans; Hydrogen Peroxide; Leukocyte Count; Muramidase; Neutrophils; Oxygen; Respiration, Artificial; Respiratory Distress Syndrome

Topics: Blood Bactericidal Activity; Blood Donors; Blood Preservation; Blood Transfusion; Cell Adhesion; Chemotaxis, Leukocyte; Granulocytes; Humans; Hydrogen Peroxide; Lactoferrin; Leukocyte Count; Muramidase; Peroxidase; Phagocytosis; Respiratory Distress Syndrome; Superoxides

Complement-mediated neutrophil activation (CMNA) has been implicated as an important pathophysiologic mechanism contributing to acute microvascular lung injury in the adult respiratory distress syndrome (ARDS). Using cardiopulmonary bypass (CPB) as a clinical model for complement-mediated microvascular injury, we studied the effects of methylprednisolone (MPSS) pretreatment on manifestations of CMNA in 28 pediatric patients undergoing CPB. Six patients not receiving MPSS served as controls. Results demonstrated that MPSS did not prevent complement activation as noted by 4.5- and 7.7-fold increases in plasma C3a des Arg levels during and immediately after CPB, respectively. However, detectable in vivo and in vitro manifestations of CMNA were altered. Neutropenia during CPB was attenuated to 65% of prebypass values compared with 47% in the control group. Neutrophil selective chemotactic desensitization toward C5a/C5a des Arg during the on bypass and postbypass periods was evident in the control group (0.41 and 0.76 cm specific migration, respectively) and prevented in the MPSS group (1.55 and 2.00 cm specific migration, respectively). We conclude that CMNA during CPB is ameliorated and/or prevented by MPSS pretreatment. These findings suggest that MPSS pretreatment may ameliorate complement-mediated microvascular (lung) injury in CPB and ARDS.

Topics: Anaphylatoxins; Cardiopulmonary Bypass; Chemotactic Factors; Chemotaxis, Leukocyte; Child, Preschool; Complement Activation; Complement C3; Complement C3a; Complement C5; Complement C5a, des-Arginine; Complement System Proteins; Female; Glucuronidase; Humans; Male; Methylprednisolone; Muramidase; Neutropenia; Neutrophils; Postoperative Complications; Premedication; Respiratory Distress Syndrome