asthma; human airway smooth muscle; cell culture; cell proliferation; hyperplasia

We hypothesize that a cell-type-specific absence of C/EBPalpha is responsible for the enhanced proliferation of bronchial smooth-muscle cells derived from subjects with asthma and that it explains the failure of glucocorticoids to inhibit proliferation in vitro.

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SummaryThe platelet aggregation test is widely used for the diagnosis of heparin-induced thrombocytopenia (HIT), a potentially serious complication of heparin therapy. We have evaluated its sensitivity and specificity in comparison with those of the 14C-serotonin release test. The sensitivity of the platelet aggregation test was found to vary with the heparin concentration and the donor of the platelets used in the test. The optimal heparin concentrations were between 0.1 and 1.0 U/ml. Using these heparin concentrations, the mean sensitivity varied from 39% (with the least reactive platelets) to 81% (with the most reactive platelets). In comparison, the sensitivity of the release test ranged from 65% to 94%. The specificities of the platelet aggregation test were 82%, 90% and 100% for the following control groups: (1) non-thrombocytopenic patients given heparin, (2) patients with thrombocytopenia due to other causes, and (3) normal controls not given heparin, respectively. The corresponding specificities for the release test was 94%, 90% and 100%. The specificities can be further increased to 100% for all controls with the adoption of a two-point system which defines a positive result as one in which platelet aggregation occurs with a low heparin concentration (0.5 U/ml) but not with 100 U heparin/ml. For optimal results, a two-point platelet aggregation test should be performed with heparin concentrations of 0.5 and 100 U/ml and using platelets of more reactive donors.

The lung is composed of airways and lung parenchyma, and the extracellular matrix (ECM) contains the main building blocks of both components. The ECM provides physical support and stability to the lung, and as such it has in the past been regarded as an inert structure. More recent research has provided novel insights revealing that the ECM is also a bioactive environment that orchestrates the cellular responses in its environs. Changes in the ECM in the airway or parenchymal tissues are now recognized in the pathological profiles of many respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). Only recently have we begun to investigate whether these ECM changes result from the disease process, or whether they constitute a driving factor that orchestrates the pathological outcomes. This review summarizes our current knowledge of the alterations in the ECM in asthma, COPD, and IPF, and the contributions of these alterations to the pathologies. Emerging data suggest that alterations in the composition, folding or rigidity of ECM proteins may alter the functional responses of cells within their environs, and in so doing change the pathological outcomes. These characteristics highlight potential avenues for targeting lung pathologies in the future. This may ultimately contribute to a better understanding of chronic lung diseases, and novel approaches for finding therapeutic solutions. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

No abstract

Airway and/or lung remodeling, involving exaggerated extracellular matrix (ECM) protein deposition, is a critical feature common to pulmonary diseases including chronic obstructive pulmonary disease (COPD), asthma, and idiopathic pulmonary fibrosis (IPF). Fibulin-1 (Fbln1), an important ECM protein involved in matrix organization, may be involved in the pathogenesis of these diseases. We found that Fbln1 was increased in COPD patients and in cigarette smoke–induced (CS-induced) experimental COPD in mice. Genetic or therapeutic inhibition of Fbln1c protected against CS-induced airway fibrosis and emphysema-like alveolar enlargement. In experimental COPD, this occurred through disrupted collagen organization and interactions with fibronectin, periostin, and tenascin-c. Genetic inhibition of Fbln1c also reduced levels of pulmonary inflammatory cells and proinflammatory cytokines/chemokines (TNF-α, IL-33, and CXCL1) in experimental COPD. Fbln1c−/− mice also had reduced airway remodeling in experimental chronic asthma and pulmonary fibrosis. Our data show that Fbln1c may be a therapeutic target in chronic respiratory diseases.

Platelet function is influenced by the platelet thioldisulfide balance. Platelet activation resulted in 440% increase in surface protein thiol groups. Two proteins that presented free thiol(s) on the activated platelet surface were protein-disulfide isomerase (PDI) and glycoprotein 1b␣ (GP1b␣). PDI contains two active site dithiols/disulfides. The active sites of 26% of the PDI on resting platelets was in the dithiol form, compared with 81% in the dithiol form on activated platelets. Similarly, GP1b␣ presented one or more free thiols on the activated platelet surface but not on resting platelets. Anti-PDI antibodies increased the dissociation constant for binding of vWF to platelets by ϳ50% and PDI and GP1b␣ were sufficiently close on the platelet surface to allow fluorescence resonance energy transfer between chromophores attached to PDI and GP1b␣. Incubation of resting platelets with anti-PDI antibodies followed by activation with thrombin enhanced labeling and binding of monoclonal antibodies to the N-terminal region of GP1b␣ on the activated platelet surface. These observations indicated that platelet activation triggered reduction of the active site disulfides of PDI and a conformational change in GP1b␣ that resulted in exposure of a free thiol(s).The platelet thiol-disulfide balance is important for platelet function. Perturbation of platelet thiol status effects platelet aggregation and release. The low M r thiol compounds, reduced glutathione (GSH), cysteine, and 6-mercaptopurine, inhibit platelet aggregation induced by several agonists, while the disulfide-bond reducing agents dithiothreitol and ␤-mercaptoethanol promote aggregation (1). In addition, reaction of platelet sulfhydryl groups with the thiol specific compounds, diamide and N-ethylmaleimide, inhibits in vitro aggregation and clot retraction (2-5). These results imply that certain platelet thiol groups are critical for platelet aggregation. Furthermore, the observation that specific depletion of platelet GSH by 1-chloro-2,4-dinitrobenzene only marginally effects platelet aggregability implies that the critical thiol groups are associated with protein (6). In support of this notion, Yamada et al. (7) have shown that the anti-platelet aggregation actions of 2,2Ј-dithiobis(N-2-hydroxypropylbenzamide) are mediated through interaction of the compound with platelet protein thiol groups.Protein-disulfide isomerase (PDI) 1 is a noncovalent homodimer with a subunit molecular mass of 57 kDa that catalyzes thiol-disulfide interchanges that can result in formation, reduction, or rearrangement of protein disulfide bonds. It is generally considered that PDI is important for proper folding and disulfide bonding of nascent proteins in the endoplasmic reticulum (8 -10). PDI also functions as the ␤ subunits of prolyl-4-hyroxylase (11, 12) and the ␤ subunit of triglyceride transfer protein complex (13,14). Bovine aortic endothelial cells (15), rat hepatocytes (16), rat pancreatic cells (17), and human B cells (18,19) secrete PDI which associates with the cell su...