Edward S. Schulman

Diagnosis and management of cough executive summary: ACCP evidence-based clinical practice guidelines

Recognition of the importance of cough in clinical medicine was the impetus for the original evidence-based consensus panel report on “Managing Cough as a Defense Mechanism and as a Symptom,” published in 1998,1 and this updated revision. Compared to the original cough consensus statement, this revision (1) more narrowly focuses the guidelines on the diagnosis and treatment of cough, the symptom, in adult and pediatric populations, and minimizes the discussion of cough as a defense mechanism; (2) improves on the rigor of the evidence-based review and describes the methodology in a separate section; (3) updates and expands, when appropriate, all previous sections; and (4) adds new sections with topics that were not previously covered. These new sections include nonasthmatic eosinophilic bronchitis (NAEB); acute bronchitis; nonbronchiectatic suppurative airway diseases; cough due to aspiration secondary to oral/pharyngeal dysphagia; environmental/occupational causes of cough; tuberculosis (TB) and other infections; cough in the dialysis patient; uncommon causes of cough; unexplained cough, previously referred to as idiopathic cough; an empiric integrative approach to the management of cough; assessing cough severity and efficacy of therapy in clinical research; potential future therapies; and future directions for research.

Differential effects of the complement peptides, C5a and C5a des Arg on human basophil and lung mast cell histamine release.

The ability of purified anaphylatoxins to induce human lung mast cell mediator release was investigated. In eight anti-IgE responsive (histamine release = 22 +/- 5%, mean +/- SEM) mast cell preparations of 1-96% purity, C5a and C5a des Arg (0.55 pg/ml to 55 micrograms/ml), failed to elicit or potentiate histamine release; lung fragments were similarly unresponsive. The related peptide C3a was also inactive. All anaphylatoxins failed to induce mast cell leukotriene C4 (LTC4) and prostaglandin D2 (PGD2) release. LTC4 release was also negligible from basophils where C5a was a potent histamine release stimulus. Supernatants from C5a-challenged mast cells remained fully active on basophils, excluding carboxypeptidase inactivation of C5a as an explanation for the lung mast cell results. In contrast to lung, skin mast cells were C5a-responsive (histamine release = 8 +/- 1%, at 55 micrograms/ml, n = 2). We conclude that C5a, though devoid of activity on the human lung mast cell, is a human basophil and skin mast cell secretagogue. These findings demonstrate significant organ-specific heterogeneity in mast cell responsiveness.

c-Kit immunophenotyping and metalloproteinase expression profiles of mast cells in interstitial lung diseases

Diverse interstitial lung diseases (ILD) demonstrate mesenchymal infiltration by an abundance of activated mast cells whose role in parenchymal fibrogenesis remains unclear. Since mast cells differentiate in a dynamic, tissue‐specific manner via signals transduced by c‐Kit receptor, we examined the effect of ILD microenvironments on c‐Kit expression and metalloproteinase phenotypes of mesenchymal mast cell populations. Immunohistochemical and flow cytometric analyses characterized surface expression of c‐Kit on mast cells in tissues obtained from patients with idiopathic pulmonary fibrosis, systemic sclerosis, sarcoidosis, and lymphangioleiomyomatosis, thus identifying a unique immunophenotype not shared by normal lung mast cells. Isolation of c‐Kit+/FcεRI+/CD34− mast cells via immunocytometric sorting of heterogeneous cell populations from mechanically disaggregated lung tissues permitted analysis of gene expression patterns by two‐step real‐time polymerase chain reaction. Transcriptional profiling identified expression of c‐Kit and the neutral serine proteases, tryptase and chymase, establishing the identity of sorted populations as mature mast cells. Mast cells harvested from ILD tissues demonstrated characteristic metalloproteinase phenotypes which included expression of matrix metalloproteinase (MMP)‐1 and a disintegrin and metalloproteinase (ADAM)‐9, ‐10, and ‐17. Immunohistochemical co‐localization guided by gene profiling data confirmed expression of chymase, MMP‐1, and ADAM‐17 protein in subpopulations of mast cells in remodelling interstitium. Gene profiling of harvested mast cells also showed increased transcript copy numbers for TNFα and CC chemokine receptor 2, which play critical roles in lung injury. We conclude that ILD microenvironments induce unique c‐Kit receptor and metalloproteinase mast cell phenotypes. Copyright

Obstructive sleep apnea syndrome and asthma: the role of continuous positive airway pressure treatment

OBJECTIVE To review the concept of a possible link between asthma and obstructive sleep apnea syndrome (OSAS) and the impact on asthma symptoms of treatment of OSAS with continuous positive airway pressure (CPAP) in patients with both conditions. DATA SOURCES The Ovid, MEDLINE, and PubMed databases from 1950 to the present were searched for relevant articles regarding a possible relationship between asthma and OSAS and the effectiveness of CPAP in treating OSAS. STUDY SELECTION Articles describing pathophysiologic conditions occurring in OSAS that may be linked to asthma pathogenesis were used for this review. RESULTS The data suggest that OSAS is an independent risk factor for asthma exacerbations. CPAP has been shown in prospective clinical studies to have a positive impact on asthma outcome in patients with concomitant OSAS. Ameliorative mechanisms of treatment with CPAP include mechanical and neuromechanical effects, gastroesophageal acid reflux suppression, local and systemic anti-inflammatory effects (including suppression of increased serum levels of inflammatory cytokines, chemokines, and vascular endothelial growth factor), cardiac function improvements, leptin level suppression, weight reduction, and sleep restoration. CONCLUSIONS Asthma and OSAS are increasingly troublesome public health issues. Mounting evidence implicates OSAS as a risk factor for asthma exacerbations, thereby linking these 2 major epidemics. We describe potential mechanisms whereby CPAP, the first line of therapy for OSAS, might modify airway smooth muscle function and asthma control in patients with both disorders. Despite the ever-increasing population of patients with both disorders, large, prospective, randomized controlled studies are necessary to more fully evaluate CPAP and asthma outcomes.

Adenosine 5'-triphosphate axis in obstructive airway diseases.

In recent years, significant progress has been made in our understanding of the pathophysiology behind obstructive airway diseases in general and asthma in particular; this knowledge, however, has not translated to major breakthroughs in the treatment of these disorders. Current therapeutic options are less than optimal and frequently are associated with systemic adverse effects. Recent studies indicate that endogenous purine nucleotides, adenosine 5´-triphosphate (ATP) in particular, could play a mechanistic role in obstructive airway diseases through their actions on multiple cell types relevant to these disorders, including mast cells, eosinophils, dendritic cells, and neurons. The pharmacologic modulation of ATP signal transduction in these cells represents an attractive new therapeutic target.

The role of 5-lipoxygenase products in preclinical models of asthma

BACKGROUND The action of 5-lipoxygenase on arachidonic acid generates potent inflammatory mediators that may contribute to the pathophysiology of asthma. METHODS Using the potent and selective 5-lipoxygenase inhibitor BI-L-239, we have examined the role of 5-lipoxygenase products in three animal models of asthma. RESULTS In vitro BI-L-239 inhibited 5-lipoxygenase product generation from human lung mast cells, alveolar macrophages, and peripheral blood leukocytes with a concentration that would provide 50% inhibition values of 28 to 340 nmol/L. A 36-fold selectivity for immunoreactive leukotriene C4 versus immunoreactive prostaglandin D2 inhibition was demonstrated in mast cells. In anesthetized cynomolgus monkeys, inhaled BI-L-239 provided dose-dependent inhibition of the inhaled Ascaris-induced immunoreactive leukotriene C4 release (maximum, 73%; bronchoalveolar lavage [BAL], 20 minutes), late-phase bronchoconstriction (maximum, 41%; +6 to 8 hours), and neutrophil infiltration (maximum, 63%; BAL, +8 hours). In conscious sheep, inhaled BI-L-239 provided dose-dependent inhibition of the inhaled Ascaris-induced late-phase bronchoconstriction (maximum, 66%; +6 to 8 hours) and increase in airway responsiveness (maximum, 82%; carbachol, +24 hours). The acute bronchoconstriction was shortened, and neutrophil infiltration diminished (maximum, 61%; BAL, +8 hours) in this model. Finally in conscious actively sensitized guinea pigs pretreated with pyrilamine and indomethacin, inhaled BI-L-239 attenuated acute bronchoconstriction (maximum, 80%; +5 to 15 minutes), leukocyte infiltration (58%; BAL, +3 days) and increase in airway responsiveness (100%; methacholine, +3 days) induced by three alternate-day ovalbumin inhalations. CONCLUSIONS In conclusion, results in these three animal models indicate that 5-lipoxygenase products may be major contributors to the bronchoconstriction (especially late phase), leukocyte infiltration, and airway hyperresponsiveness that characterize asthma.

Enhanced reseeding of decellularized rodent lungs with mouse embryonic stem cells

Repopulation of decellularized lung scaffolds (DLS) is limited due to alterations in the repertoire and ratios of the residual extracellular matrix (ECM) proteins, characterized by e.g., the retention of type I collagen and loss of glycoproteins. We hypothesized that pre-treatment of decellularized matrices with defined ECM proteins, which match the repertoire of integrin receptors expressed by the cells to be seeded (e.g., embryonic stem cells) can increase the efficacy of the reseeding process. To test this hypothesis, we first determined the integrin receptors profile of mouse embryonic stem cells (mESCs). Mouse ESCs express α3, α5, α6, α9 and β1, but not α1, α2 and α4 integrin subunits, as established by Western blotting and adhesion to laminin and fibronectin, but not to collagens type I and IV. Reseeding of DLS with mESCs was inefficient (6.9 ± 0.5%), but was significantly enhanced (2.3 ± 0.1 fold) by pre-treating the scaffolds with media conditioned by A549 human lung adenocarcinoma cells, which we found to contain ∼5 μg/ml laminin. Furthermore, pre-treatment with A549-conditioned media resulted in a significantly more uniform distribution of the seeded mESCs throughout the engineered organ as compared to untreated DLS. Our study may advance whole lung engineering by stressing the importance of matching the integrin receptor repertoire of the seeded cells and the cell binding motifs of DLS.

Hypoxia Enhances Differentiation of Mouse Embryonic Stem Cells into Definitive Endoderm and Distal Lung Cells

We investigated the effects of hypoxia on spontaneous (SP)- and activin A (AA)-induced definitive endoderm (DE) differentiation of mouse embryonic stem cells (mESCs) and their subsequent differentiation into distal pulmonary epithelial cells. SP differentiation for 6 days of mESCs toward endoderm at hypoxia of 1% O2, but not at 3% or 21% (normoxia), increased the expression of Sox17 and Foxa2 by 31- and 63-fold above maintenance culture, respectively. Treatment of mESCs with 20 ng/mL AA for 6 days under hypoxia further increased the expression of DE marker genes Sox17, Foxa2, and Cxcr4 by 501-, 1,483-, and 126-fold above maintenance cultures, respectively. Transient exposure to hypoxia, as short as 24 h, was sufficient to enhance AA-induced endoderm formation. The involvement of hypoxia-inducible factor (HIF)-1α and reactive oxygen species (ROS) in the AA-induced endoderm enrichment was assessed using HIF-1α(-/-) mESCs and the ROS scavenger N-acetylcysteine (NAC). Under SP conditions, HIF-1α(-/-) mESCs failed to increase the expression of endodermal marker genes but rather shifted toward ectoderm. Hypoxia induced only a marginal potentiation of AA-induced endoderm differentiation in HIF-1α(-/-) mESCs. Treatment of mESCs with AA and NAC led to a dose-dependent decrease in Sox17 and Foxa2 expression. In addition, the duration of exposure to hypoxia in the course of a recently reported lung differentiation protocol resulted in differentially enhanced expression of distal lung epithelial cell marker genes aquaporin 5 (Aqp5), surfactant protein C (Sftpc), and secretoglobin 1a1 (Scgb1a1) for alveolar epithelium type I, type II, and club cells, respectively. Our study is the first to show the effects of in vitro hypoxia on efficient formation of DE and lung lineages. We suggest that the extent of hypoxia and careful timing may be important components of in vitro differentiation bioprocesses for the differential generation of distal lung epithelial cells from pluripotent progenitors.

Hydrogen peroxide release from human eosinophils on fibronectin: scopoletin enhances eosinophil activation.

We have examined the release of H(2)O(2) from PAF or TNFalpha-stimulated human eosinophils on fibronectin (FN)-coated polystyrene plates. H(2)O(2) release was measured by the standard scopoletin-horseradish peroxidase (SCOP-HRP) method and compared with that measured by a new microplate fluorescent assay for H(2)O(2) using a novel HRP substrate A6550. We observed that the SCOP-HRP method gave a 25-fold higher estimate of H(2)O(2) release from eosinophils than did the A6550-HRP method. Microscopic examination of PAF or TNFalpha-stimulated eosinophils in buffer alone or A6550-HRP reaction mixture showed that the cells remained generally round, while eosinophils in SCOP-HRP reaction mixture were spread on the fibronectin-coated surface. Measurement of the cellular ATP content after PAF-stimulation showed that only eosinophils activated in SCOP-HRP had a 50% fall in ATP content. This supported our conclusion that measurement of H(2)O(2) release from eosinophils in SCOP-HRP reaction mixture is problematic since the SCOP-HRP system activates eosinophils. However, we also found that A6550-HRP, when present throughout the incubation, resulted in a lower estimate of H(2)O(2) release than expected. The method used to detect eosinophil H(2)O(2) release greatly influences the absolute amount of H(2)O(2) detected.

Low density lipoprotein (LDL) inhibits histamine release from human mast cells

We examined the effect of low density lipoprotein (LDL) on histamine release from purified human lung mast cells. LDL inhibited anti-IgE- induced histamine release in a dose-dependent manner, with 100 micrograms/ml LDL-protein inhibiting histamine release by 53 +/- 8% (mean +/- SEM); half-maximal inhibition occurred at 40-80 micrograms/ml. LDL also inhibited calcium ionophore A23187-induced histamine release in a dose-dependent manner, with 1 mg/ml of LDL inhibiting histamine release by 83 +/- 9%; half maximal inhibition occurred at 220-280 micrograms/ml. Inhibition by LDL was time-dependent: half-maximal inhibition of anti-IgE- induced histamine release by LDL occurred at 30-50 minutes of incubation. The inhibitory effect of LDL was independent of buffer calcium concentrations (0-5 mM) or temperature (0-37 degrees C). These data are consistent with a newly defined immunoregulatory role for LDL.