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Biomedical subjects

J M Drazen

Publications and source records attributed to J M Drazen.

At least 91 records · Page 5Linked to original sources
PubMed1998

cAMP-response-element-binding-protein-binding protein (CBP) and p300 are transcriptional co-activators of early growth response factor-1 (Egr-1).

Egr-1 (early-growth response factor-1) is a sequence-specific transcription factor that plays a regulatory role in the expression of many genes important for cell growth, development and the pathogenesis of disease. The transcriptional co-activators CBP (cAMP-response-element-binding-protein-binding protein) and p300 interact with sequence-specific transcription factors as well as components of the basal transcription machinery to facilitate RNA polymerase II recruitment and transcriptional initiation. Here we demonstrate a unique way in which Egr-1 physically and functionally interacts with CBP/p300 to modulate gene transcription. CBP/p300 potentiated Egr-1 mediated expression of 5-lipoxygenase (5-LO) promoter-reporter constructs, and the degree of trans-activation was proportional to the number of Egr-1 consensus binding sites present in wild-type and naturally occurring mutants of the 5-LO promoter. The N- and C-terminal domains of CBP interact with the transcriptional activation domain of Egr-1, as demonstrated by a mammalian two-hybrid assay. Direct protein-protein interactions between CBP/p300 and Egr-1 were demonstrated by glutathione S-transferase fusion-protein binding and co-immunoprecipitation/Western-blot studies. These data suggest that CBP and p300 act as transcriptional co-activators for Egr-1-mediated gene expression and that variations between individuals in such co-activation could serve as a genetic basis for variability in gene expression.

Animals↗
PubMed1998

New directions in asthma drug therapy.

A new generation of biologically informative treatments has altered our understanding of the disease--transforming what used to be viewed as a single entity into a family of airway disorders driven by different proinflammatory mediators. Although inhaled corticosteroids have been the treatment of choice for most patients, research is increasingly aimed at developing inhibitors targeted to specific effector systems.

Anti-Asthmatic Agents↗
PubMed1998

Pulmonary infiltrates, eosinophilia, and cardiomyopathy following corticosteroid withdrawal in patients with asthma receiving zafirlukast.

CONTEXT: Zafirlukast is a potent leukotriene antagonist that recently was approved for the treatment of asthma. As use of this drug increases, adverse events that occur at low frequency or in populations not studied in premarketing clinical trials may become evident. OBJECTIVE: To describe a clinical syndrome associated with zafirlukast therapy. DESIGN: Case series. PATIENTS: Eight adults (7 women and 1 man) with steroid-dependent asthma who received zafirlukast. MAIN OUTCOME MEASURES: Development of a clinical syndrome characterized by pulmonary infiltrates, cardiomyopathy, and eosinophilia following the withdrawal of corticosteroid treatment. RESULTS: The clinical syndrome developed while patients were receiving zafirlukast from 3 days to 4 months and from 3 days to 3 months after corticosteroid withdrawal. All 8 patients developed leukocytosis (range, 14.5-27.6 x 10(9)/L) with eosinophilia (range, 0.19-0.71). Six patients had fever (temperature >38.5 degrees C), 7 had muscle pain, 6 had sinusitis, and 6 had biopsy evidence of eosinophilic tissue infiltration. The clinical syndrome improved with discontinuation of zafirlukast treatment and reinitiation of corticosteroid treatment or addition of cyclophosphamide treatment. COMMENT: Development of pulmonary infiltrates, cardiomyopathy, and eosinophilia may have occurred independent of zafirlukast use or may have resulted from an allergic response to this medication. We suspect that these patients may have had a primary eosinophilic infiltrative disorder that had been clinically recognized as asthma, was quelled by steroid treatment, and was unmasked following corticosteroid withdrawal facilitated by zafirlukast.

Adult↗
PubMed1998

Pharmacogenetics of the 5-lipoxygenase pathway in asthma.

It is now well appreciated that asthma is a chronic inflammatory disease of the airways; among the inflammatory cells that have been implicated in the asthmatic lesion are eosinophils and mast cells. Although these cells have the capacity to produce a number of distinct chemical mediators, the cysteinyl leukotrienes have recently been identified as important mediators of the asthmatic response. The leukotrienes are derived from arachidonic acid released from membrane phospholipids by the action of phospholipases. The archidonic acid so released in the presence of the 5-lipoxygenase (5-LO) activating protein becomes a substrate for the enzyme 5-LO. This enzyme catalyses the stereo-specific addition of molecular oxygen to arachidonic acid to form the product known as leukotriene A4. Leukotriene A4 subsequently becomes a substrate for one of two enzymes, leukotriene A4 epoxide hydrolase or LTC4 synthase. The former catalyses the formation of LTB4 while the later catalyses the formation of the cysteinyl leukotrienes. Thus the enzyme 5-LO is critically posed to serve as a regulator of leukotriene synthesis. 5-LO action is known to be regulated at a number of levels; the mechanisms include regulation of action of the mature protein and regulation of 5-LO gene transcription and translation; there is good reason to believe that all forms of 5-LO regulation are highly interdependent. In this regard we describe the presence and functional consequences of a series of naturally occurring mutations in 5-LO core promoter. These mutations modify gene transcription in vitro, and may have functional consequences in vivo.

Animals↗
PubMed1998

Modulation of aquaporin 4 and the amiloride-inhibitable sodium channel in perinatal rat lung epithelial cells.

During the perinatal period, a dramatic reversal of lung transepithelial ion and water transport occurs that involves the amiloride-inhibitable Na+ channel (ENaC). Aquaporin (AQP) water channel proteins facilitate cell membrane water transport. We now report that AQP-4, localized to basolateral membranes of airway epithelial cells, increases its mRNA expression in developing lung eightfold during the 2 days before birth to reach a peak on the first postnatal day in the lungs but not in brains or kidneys of neonatal rats. AQP-4 and the alpha-, beta-, and gamma-subunits of ENaC are both expressed by cultured rat fetal distal lung epithelial (FDLE) cells. AQP-4 and ENaC expression increase in FDLE cells cultured on uncoated permeant filters compared with matched control cells cultured on filters containing extracellular matrix derived from fetal lung epithelial cells. Similarly, AQP-4 expression increases in FDLE cells exposed to 21% O2 compared with cells exposed to 3% O2. These data demonstrate that AQP-4 expression is highest on the first day after birth in neonatal rat lungs. Exposure to ambient 21% O2 may contribute to increases in AQP-4 and ENaC expression to facilitate water transport across neonatal airway epithelia in the immediate postnatal period.

Amiloride↗
PubMed1998

Endogenous pulmonary nitric oxide in the regulation of airway microvascular leak.

Endogenous nitric oxide (NO) is an important modulator of airway function, but its role in the regulation of airway microvascular leak (AMVL) remains unclear. Thus we assessed the effects of NO synthase (NOS) inhibition on expired NO (ENO) levels and on AMVL measured by the Evans blue dye technique in guinea pigs. In control unsensitized animals, systemic NG-nitro-L-arginine methyl ester (L-NAME) reduced ENO by 70 +/- 8% (P < 0.01) and reduced AMVL by 92 +/- 1 and 44 +/- 17% (P < 0.05 for both) in the extrapulmonary and intrapulmonary airways, respectively. In animals sensitized and challenged with intratracheal antigen, markedly increased levels of AMVL and ENO were similarly attenuated by L-NAME. In contrast, aminoguanidine, a relatively selective type II NOS inhibitor, reduced ENO in both antigen-sensitized and control unsensitized animals by 39 +/- 3% (P < 0.01) but had no effect on AMVL. These data indicate that endogenous pulmonary NO contributes to both basal and antigen-stimulated levels of AMVL in guinea pigs and that this NO-dependent activity does not appear to be derived from type II NOS.

Animals↗
PubMed1998

Expired nitric oxide after bronchoprovocation and repeated spirometry in patients with asthma.

Compared with normal individuals, subjects with asthma have elevated levels of expired nitric oxide (NO). These levels are hypothesized to reflect the degree of airway inflammation. Expired NO levels rise during the late phase of allergen challenge and decrease in asthmatics after steroid treatment. Isocapnic cold air hyperventilation (ISH) is believed to cause airway narrowing through noninflammatory mechanisms. We measured mixed expired NO in 10 individuals with atopic asthma who underwent both ISH challenge and allergen challenge, and compared these measurements with the change in expired NO that occurred after serial spirometry alone. We found that ambient NO levels affected mixed expired NO. Controlling for inspired NO, we found that repeated spirometry alone produced a significant fall in mixed expired NO (p < 0.01) that was maximal after 30 min (36.6 +/- 8.5% fall). After allergen and ISH challenges, expired NO was elevated relative to levels after repeated spirometry (p < 0.01 and p = 0.065, respectively). In addition, we found that prechallenge expired NO levels were significantly correlated with the magnitude of the late fall in FEV1 following allergen challenge (r = 0.80, p < 0.01). These data demonstrate that repeated spirometry results in reduced mixed expired NO and suggest that both ISH and allergen-induced bronchoconstriction share pathobiologic mechanisms that produce increases in mixed expired NO.

Adult↗
PubMed1998

Genetic epidemiology of severe, early-onset chronic obstructive pulmonary disease. Risk to relatives for airflow obstruction and chronic bronchitis.

Severe alpha-1-antitrypsin deficiency is the only proven genetic risk factor for chronic obstructive pulmonary disease (COPD). We have assembled a cohort of 44 probands with severe, early-onset COPD, who do not have severe alpha-1-antitrypsin deficiency. A surprisingly high prevalence of females (79.6%) was found. Assessment of the risk to relatives of these early-onset COPD probands for airflow obstruction and chronic bronchitis was performed to determine whether significant familial aggregation for COPD, independent of alpha-1-antitrypsin deficiency, could be demonstrated. First- degree relatives of early-onset COPD probands had significantly lower FEV1 and FEV1/FVC values than control subjects (p < 0.01), despite similar pack-years of smoking. Reduced spirometric values in first-degree relatives of early-onset COPD probands were found only in current or ex-cigarette smokers. The mean FEV1 in current or ex-smoking first-degree relatives was 76.1 +/- 20.9% predicted compared to 89.2 +/- 14.4% predicted in current or ex-smoking control subjects (p < 0.01); in lifelong nonsmokers, the mean FEV1 was 93.4% predicted for both control subjects and first-degree relatives of early-onset COPD probands. Generalized estimating equations, adjusting for age and pack-years of smoking, demonstrated increased odds of reduced FEV1 and chronic bronchitis in current or ex-smoking first-degree relatives of early-onset COPD probands. Using a new method to estimate relative risk from relative odds, we estimate that the relative risks for FEV1 below 60%, FEV1 below 80%, and chronic bronchitis are each approximately three in current or ex-smoking first-degree relatives of early-onset COPD probands. The increased risk to relatives of early-onset COPD probands for reduced FEV1 and chronic bronchitis, limited to current or ex-smokers, suggests genetic risk factor(s) for COPD that are expressed in response to cigarette smoking.

Bronchitis↗
PubMed1998

Inflammatory cell distribution within and along asthmatic airways.

Asthmatic airways are infiltrated with inflammatory cells that release mediators and cytokines into the microenvironment. In this study, we evaluated the distribution of CD45-positive leukocytes and eosinophils in lung tissue from five patients who died with severe asthma compared with five patients with cystic fibrosis. For morphometric analysis, the airway wall was partitioned into an "inner" area (between basement membrane and smooth muscle) and an "outer" area (between smooth muscle and alveolar attachments). Large airways (with a perimeter greater than 3.0 mm) from patients with asthma or cystic fibrosis had a greater density of CD45-positive cells (p < 0.05) and eosinophils (p < 0.001) in the inner airway region compared with the same airway region in small airways. Furthermore, in small airways, asthmatic lungs showed a greater density of CD45-positive cells (p < 0.01) and eosinophils (p < 0.01) in the outer compared with the inner airway wall region. These observations indicate that there are regional variations in inflammatory cell distribution within the airway wall in patients with asthma that are not observed in airways from patients with cystic fibrosis. We speculate that this inflammatory cell density in peripheral airways in severe asthma may relate to the peripheral airway obstruction characteristic of this condition.

Adolescent↗
PubMed1998

Leukotrienes as mediators of airway obstruction.

The cysteinyl leukotrienes are potent mediators of airway narrowing derived from the lipoxygenation of arachidonic acid and the adduction of glutathione to this eicosanoid backbone. In lower animals and humans, the cysteinyl leukotrienes are among the most potent airway contractile substances ever identified. Furthermore, these moieties can be recovered from the urine during induced or spontaneous asthma attacks. Most important, inhibition of the synthesis of the leukotrienes or prevention of their action at the CysLT1 receptor is associated with an improvement in the airway dysfunction that occurs in both induced and spontaneous asthma. These data indicate that the cysteinyl leukotrienes have a clinically significant role in the airway obstruction that characterizes asthma.

Airway Obstruction↗
PubMed1998

Reduction of antigen-induced airway hyperreactivity and eosinophilia in ICAM-1-deficient mice.

A murine model of asthma is described in which we examined the role of intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of airway reactivity, pulmonary eosinophilia, and inflammation. We sensitized wild-type control [C57BL/6J, (+/+)] and ICAM-1 knockout [C57BL/6J-ICAM-1, (-/-)] mice to ovalbumin (OVA), and challenged them with OVA delivered by aerosol (OVA-OVA) to induce a phenotype consistent with an asthmatic response. Bronchial responsiveness to methacholine and counts of cell numbers and measurements of eosinophil content and cytokine levels in bronchoalveolar lavage fluid (BALF) were significantly attenuated in ICAM-1(-/-) mice as compared with (+/+) mice. We also showed that the absence of ICAM-1 had no significant affects on the production of serum IgE antibody, but did have an effect on ex vivo lymphocyte proliferation. Additionally, immunohistochemistry: (1) revealed increased staining for vascular cell adhesion molecule-1 (VCAM-1) after antigen challenge in the ICAM-1(-/-) mice but not in the ICAM-1(+/+) controls; and (2) confirmed the presence of alternatively spliced forms of ICAM-1 in the lungs of ICAM-1(-/-) mice. Thus, despite the availability of alternate adhesion pathways in ICAM-1(-/-) mice, the absence of ICAM-1 prevented eosinophils from entering the airways. In summary, we found that the ICAM-1 knockout mice exhibited a significantly inhibited response to aerosol antigen challenge for most of the parameters examined, and conclude that ICAM-1 is an important ligand mediating T-cell proliferation in response to antigen, eosinophil migration into the airways, and the development of airway hyperreactivity (AHR) in allergen-sensitized and -challenged mice.

Animals↗
PubMed1998

Egr-1 and Sp1 interact functionally with the 5-lipoxygenase promoter and its naturally occurring mutants.

5-Lipoxygenase (5-LO), an enzyme essential for the formation of leukotrienes, is functionally modulated by a number of mechanisms, including transcriptional controls. The 5-LO promoter has a unique G+C-rich sequence, located between 176 and 147 base pairs upstream of the ATG translation start site, which contains five tandem Sp1 (a zinc-finger transcription factor) consensus binding sites overlapping five tandem early growth response protein 1 (Egr-1), a zinc-finger transcription factor, consensus binding sites. A family of naturally occurring mutations has been identified that consists of additions or deletions of these binding sites. The role of these overlapping Sp1/Egr-1 sites in the regulation of 5-LO transcription and the effects of these mutations on transcriptional regulatory mechanisms are unknown. We now show that Sp1 and Egr-1 bind specifically to the G+C-rich promoter sequence using in vitro deoxyribonuclease I footprinting. Both Sp1 and Egr-1 activate 5-LO promoter-reporter constructs in a minimally active drosophila SL2 cotransfection system, and the G+C-rich sequence is involved in this process. Moreover, studies comparing mutant promoter function indicate that both Sp1 and Egr-1 trans-activation are proportional to the number of Sp1/Egr-1 consensus binding sites within the G+C-rich sequence. It is possible that basal and inducible 5-LO gene transcriptions are mediated by an interplay of Sp1, Egr-1, and other transcription factors within the G+C-rich promoter region, and the naturally occurring mutations alter transcription by modifying their trans-activation potential.

Animals↗
PubMed1997

Antileukotrienes in the treatment of asthma.

PURPOSE: To review the activity in clinical models, the efficacy, and the safety of antileukotrienes as a new class of antiasthma treatment. DATA SOURCES: English-language trials identified from the archival literature, including the MEDLINE database, through 1996; bibliographic references; and textbooks. STUDY SELECTION: Reports from placebo-controlled, double-blind, randomized trials were selected. DATA EXTRACTION: Study designs and results were extracted from the clinical trial reports. Statistical evaluation of combined results was not attempted. DATA SYNTHESIS: The various classes of antileukotrienes have shown activity in clinical models of asthma, including exercise-induced, cold air hyperventilation-induced, allergen-induced, and aspirin-induced bronchoconstriction. In addition, the antileukotrienes partially reverse spontaneous bronchoconstriction in asthmatic persons, an effect additive to that of inhaled beta 2-agonists. Clinical trials of the antileukotrienes have shown clinical benefit, as measured by reductions in asthma symptom scores, improvements in air flow obstruction, and reductions in the rescue use of inhaled beta 2-agonists. Some, but not all, of the antileukotrienes have been shown to cause liver microsomal activation with increases in hepatic aminotransferase levels. CONCLUSIONS: Antileukotrienes are an important new therapy for asthma. Inhibition of leukotriene synthesis or action has a beneficial effect in the treatment of both induced and spontaneous asthma. These results show that leukotrienes are important mediators of the asthmatic response. In addition, encouraging results have been obtained from clinical trials of antileukotrienes; however, these results do not yet provide guidelines for the optimal clinical use of antileukotrienes in asthma treatment. Such recommendations await the results of further studies.

Animals↗
PubMed1997

Comparison of the ontogeny of protein gene product 9.5, chromogranin A and proliferating cell nuclear antigen in developing human lung.

Pulmonary neuroendocrine cell products, especially bombesin-like peptides, are important modulators of fetal lung growth, morphogenesis and maturation. In the present study, we describe the ontogeny of protein gene product 9.5 (PGP 9.5) in 28 midtrimester human fetal lungs, in comparison to chromogranin A (CGA), a marker of differentiated neuroendocrine cells, and proliferating cell nuclear antigen (PCNA), which is expressed by actively dividing cells. PGP 9.5 immunostaining colocalized with CGA in many cells, although the peak abundance of PGP 9.5 preceded that of CGA by 4 to 6 weeks. In addition, a novel staining pattern was noted for PGP 9.5: diffuse cytoplasmic staining of undifferentiated epithelial cells, which was demonstrated by all of the airways before 15 weeks gestation. After gestational week 15, only the smallest airways demonstrated this pattern. PCNA immunostaining demonstrated age-dependent regional variation. All samples had approximately 25% epithelial cells immunopositive for PCNA. Between 11 and 14 weeks gestation over 50% of the mesenchymal cells were PCNA positive. This mesenchymal staining decreased after 14 weeks, and was rare by week 19. There was no definite correlation between the immunostaining for PGP 9.5 and that for PCNA, although PGP 9.5 positive cells were usually PCNA negative. These observations suggest that other growth factors produced by non-neuroendocrine epithelial cells also participate in lung development.

Chromogranin A↗
PubMed1997

Expression of eotaxin by human lung epithelial cells: induction by cytokines and inhibition by glucocorticoids.

Eotaxin is a potent and specific eosinophil chemoattractant that is mobilized in the respiratory epithelium after allergic stimulation. Pulmonary levels of eotaxin mRNA are known to increase after allergen exposure in sensitized animals. In this study we demonstrate that TNF alpha and IL-1beta induce the accumulation of eotaxin mRNA in the pulmonary epithelial cell lines A549 and BEAS 2B in a dose-dependent manner. Cytokine-induced A549 cell mRNA accumulation was maximal at 4 h and was significantly enhanced when the cells were costimulated with IFNgamma. TNFalpha- and IL-1beta-induced increases in eotaxin mRNA were diminished in a dose-dependent manner by the glucocorticoid dexamethasone and were augmented by the protein synthesis inhibitor cycloheximide. Cytokine-induced increases in eotaxin mRNA expression correlated with increased eotaxin protein production and secretion, and dexamethasone inhibition of cytokine-induced eotaxin mRNA augmentation was associated with diminished eotaxin protein secretion. These findings, together with the known kinetics of TNF alpha and IL-1beta mobilization in asthmatic airways and the potent eosinophil chemotactic effects of eotaxin, define a mechanism linking inflammatory cytokine mobilization to eosinophil recruitment that may be relevant to the pathogenesis of asthma.

Animals↗