ABSTRACT
The role of platelet-activating factor (PAF), a phospholipid inflammatory mediator, in Escherichia coli O157:H7-associated hemolytic uremic syndrome (HUS) is unknown. PAF is synthesized by diverse cells and is degraded by PAF-acetylhydrolase (PAF-AH). Deficient PAF-AH activity results from a G-->T transversion at position 994 of exon 9. We examined children infected with E. coliO157:H7 to determine if PAF levels or the PAF-AH ( G994T) mutation reflects the risk of developing HUS. Plasma PAF concentrations were determined using chloroform/methanol extraction, thin layer chromatography purification, and scintillation proximity assay in 10 patients with uncomplicated infection (UI), 10 infected patients who subsequently developed HUS (pre-HUS), 5 HUS patients, and 8 healthy controls. The PAF-AH ( G994T) allele frequency was determined in 52 UI children, 15 with HUS, and 11 controls. Wilcoxon rank sum tests were performed to test differences in location (median) of pairs of groups. PAF levels were higher in the UI ( P=0.04) and pre-HUS ( P=0.01) groups than in healthy controls. No subject had the PAF-AH ( G994T) allele. Thus, elevated plasma PAF levels occur in E. coliO157:H7-infected children, even without HUS, but diminish when HUS develops. The PAF-AH ( G994T) allele does not contribute to the risk of developing HUS.
Subject(s)
Escherichia coli Infections/blood , Escherichia coli O157 , Platelet Activating Factor/metabolism , Blood Cell Count , Child, Preschool , DNA/analysis , Female , Genotype , Hemolytic-Uremic Syndrome/epidemiology , Humans , Logistic Models , Male , Mutation/genetics , Platelet Activating Factor/genetics , Prospective Studies , Risk AssessmentABSTRACT
Release of human lung mast cell tryptase may be important in the pathophysiology of asthma. We examined the effect of the reversible, nonelectrophilic tryptase inhibitor MOL 6131 on airway inflammation and hyper-reactivity in a murine model of asthma. MOL 6131 is a potent selective nonpeptide inhibitor of human lung mast cell tryptase based upon a beta-strand template (K(i) = 45 nM) that does not inhibit trypsin (K(i) = 1,061 nM), thrombin (K(i) = 23, 640 nM), or other serine proteases. BALB/c mice after i.p. OVA sensitization (day 0) were challenged intratracheally with OVA on days 8, 15, 18, and 21. MOL 6131, administered days 18-21, blocked the airway inflammatory response to OVA assessed 24 h after the last OVA challenge on day 22; intranasal delivery (10 mg/kg) had a greater anti-inflammatory effect than oral delivery (10 or 25 mg/kg) of MOL 6131. MOL 6131 reduced total cells and eosinophils in bronchoalveolar lavage fluid, airway tissue eosinophilia, goblet cell hyperplasia, mucus secretion, and peribronchial edema and also inhibited the release of IL-4 and IL-13 in bronchoalveolar lavage fluid. However, tryptase inhibition did not alter airway hyper-reactivity to methacholine in vivo. These results support tryptase as a therapeutic target in asthma and indicate that selective tryptase inhibitors can reduce allergic airway inflammation.
Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/therapeutic use , Bronchial Diseases/drug therapy , Piperidines/therapeutic use , Serine Endopeptidases/metabolism , Serine Proteinase Inhibitors/therapeutic use , Animals , Asthma/drug therapy , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Bronchial Diseases/immunology , Bronchial Diseases/pathology , Bronchial Hyperreactivity/drug therapy , Bronchoalveolar Lavage Fluid/immunology , Cell Movement , Cytokines/biosynthesis , Eosinophils/immunology , Humans , Inflammation/drug therapy , Inflammation/immunology , Inflammation/pathology , Lung/immunology , Lung/metabolism , Lung/pathology , Mice , Mice, Inbred BALB C , Models, Molecular , Mucus/metabolism , Ovalbumin/immunology , Piperidines/chemistry , Piperidines/pharmacology , Pulmonary Edema/drug therapy , Pulmonary Edema/pathology , Pulmonary Eosinophilia/drug therapy , Serine Proteinase Inhibitors/chemistry , Serine Proteinase Inhibitors/pharmacology , Tryptases , Vascular Cell Adhesion Molecule-1/metabolismABSTRACT
Airway inflammation and remodeling in chronic asthma are characterized by airway eosinophilia, hyperplasia of goblet cells and smooth muscle, and subepithelial fibrosis. We examined the role of leukotrienes in a mouse model of allergen-induced chronic lung inflammation and fibrosis. BALB/c mice, after intraperitoneal ovalbumin (OVA) sensitization on Days 0 and 14, received intranasal OVA periodically Days 14-75. The OVA-treated mice developed an extensive eosinophil and mononuclear cell inflammatory response, goblet cell hyperplasia, and mucus occlusion of the airways. A striking feature of this inflammatory response was the widespread deposition of collagen beneath the airway epithelial cell layer and also in the lung interstitium in the sites of leukocytic infiltration that was not observed in the saline-treated controls. The cysteinyl leukotriene(1) (CysLT(1)) receptor antagonist montelukast significantly reduced the airway eosinophil infiltration, mucus plugging, smooth muscle hyperplasia, and subepithelial fibrosis in the OVA-sensitized/challenged mice. The presence of Charcot-Leyden-like crystals in airway macrophages and the increased interleukin (IL)-4 and IL-13 mRNA expression in lung tissue and protein in BAL fluid seen in OVA-treated mice were also inhibited by CysLT(1) receptor blockade. These data suggest an important role for cysteinyl leukotrienes in the pathogenesis of chronic allergic airway inflammation with fibrosis.
