Citations

Abstract A reliable predictor of benefit from corticosteroid treatment in patients with chronic airflow limitation is needed. In a single-blind, sequential crossover trial of placebo and prednisone (30 mg/day) treatment, with each given for 2 wk, we investigated whether an increased proportion of sputum eosinophils ( ≥ 3%) predicts a beneficial effect of prednisone in smokers with severe obstructive bronchitis. Patients were seen before and after each treatment. Clinical measurements were made blind to the laboratory findings and vice-versa. Eighteen of 20 patients completed the study. Eight had sputum eosinophilia and similar clinical and physiologic characteristics to those of 10 patients without a finding of sputum eosinophilia. Only in patients with sputum eosinophilia did prednisone, as compared with placebo, produce a statistically significant and clinically important mean effect on effort dyspnea of 0.8 (95% confidence interval [CI]: 0.3 to 1.2), p = 0.008, and in quality of life of 1.96 (95% CI: 0.5 to 3.3), p = 0.01, associated with a small improvement in FEV1 of 0.11 L (95% CI: − 0.04 to 0.23 L), p = 0.05. In these patients, prednisone also produced a significant decline in the median sputum eosinophil percentage, from 9.7% to 0.5% (p = 0.002), eosinophil cationic protein (ECP), from 6,000 μ g/L to 1,140 μ g/L (p < 0.001), and fibrinogen, from 25.3 mg/L to 5.4 mg/L (p < 0.001). These findings indicate that in smokers with severe airflow limitation, sputum eosinophilia predicts a beneficial effect of prednisone treatment. Improvement in FEV1, after prednisone treatment in this population, is small, and may not be appreciated in clinical practice.

Abstract The effect of zafirlukast (Z) to alter the inflammatory response to segmental antigen challenge (SAC) was assessed by bronchoalveolar lavage (BAL) in this double-blind, placebo-controlled, two-period, crossover trial in 11 allergic asthmatic patients. Patients with asthma and positive skin tests to antigen received 7 d of treatment with Z (20 mg twice daily) or placebo (P) during two trial periods 14 to 21 d apart. At steady state (Day 5), patients underwent SAC followed by BAL immediately after challenge and 48 h later. Purified alveolar macrophages were analyzed ex vivo for phorbol myristate acetate (PMA)-driven superoxide release. Results were analyzed by analysis of variance (ANOVA). Forty-eight hours after SAC, Z therapy was associated with significantly reduced BAL lymphocytes and alcian blue–positive cells (presumably basophils) compared with P (p < 0.01), with a trend toward reduced numbers of alveolar macrophages (p = 0.06). PMA-driven superoxide release by purified alveolar macrophages was significantly reduced 48 h after SAC in the Z versus P arms (p < 0.05). Reduction of basophil influx, mediator release, and cellular activation may be important in attenuating the late phase of asthma. Collectively, the data suggest that zafirlukast therapy alters cellular infiltration and activation associated with antigen challenge.

Abstract In general, inflammatory cells cross basement membranes by producing proteinases. To investigate the role of proteinases in eosinophil basement membrane migration, we studied peripheral blood eosinophils in Matrigel®-coated chemotaxis chambers. Electron microscopy showed degradation of the Matrigel® layer when eosinophils, added to the upper chamber, transmigrated the membrane in the presence of both platelet-activating factor (PAF) in the lower chamber and interleukin (IL)-5 in both chambers. In the absence of either or both PAF and IL-5, no changes occurred in the Matrigel® layer. Matrigel® transmigration of eosinophils induced by PAF and IL-5 was inhibited by 1,10-phenanthroline, batimastat, 3,4-dichloroisocoumarin, chymostatin, and a neutralizing antibody for the matrix metalloproteinase (MMP)-9, indicating that serine proteinase(s) and MMP, specifically MMP-9, were involved in the transmigration of eosinophils through Matrigel®. In contrast, eosinophil migration through a bare membrane was not affected by batimastat. Using gelatin zymography and immunoblotting, MMP-9 was detected in the migration upper chamber supernatant of the eosinophil transmigration assay and in the conditioned medium of eosinophils. Release of MMP-9 by eosinophils was increased by IL-5, PAF, or both, but the substrate-degrading activity of MMP-9 was increased only in the presence of both IL-5 and PAF, indicating that the releasing and activating mechanisms of MMP-9 are involved in eosinophil basement membrane migration. This study implicates MMP-9 in basement membrane migration of eosinophils and suggests its involvement in inflammatory diseases where tissue eosinophilia plays a role.

Abstract Accumulation of eosinophils in the lung with concomitant tissue damage are defining histopathologic features of human asthma. Through degranulation and the release of proinflammatory proteins such as major basic protein (MBP), eosinophils may perpetuate this inflammatory response. We investigated the extent of eosinophil degranulation in a murine model of allergic pulmonary inflammation. In this paradigm, the mice develop pulmonary eosinophilia, mucus hypersecretion, tissue damage, and airway edema and hyperreactivity. To evaluate the degree of eosinophil degranulation, we used a polyclonal antibody to murine MBP (mMBP) to perform dot blot analysis of bronchoalveolar lavage (BAL) cells and fluids, and immunohistochemical fluorescent analysis of lung tissue sections. After ovalbumin antigen challenge, we were unable to detect immunoreactive mMBP in the BAL fluids from either nonsensitized or sensitized mice. However, after lysis of the recoverable BAL cells, we were able to detect mMBP by immunoblot analysis, with the levels of immunoreactive mMBP directly related to the number of recoverable eosinophils. We also examined paraffin-embedded, lung tissue sections for patterns of mMBP deposition. Whereas lung sections from allergic mice revealed prominent peribronchial eosinophilia after antigen challenge, tissue sections from nonsensitized animals rarely displayed eosinophils. Despite the presence of numerous eosinophils, no immunohistologic evidence of extracellular mMBP could be found in antigen-challenged allergic mice. Furthermore, rechallenged allergic mice displayed a significant increase in the number of recruited pulmonary eosinophils but all immunoreactive mMBP was still intracellular. We conclude that the recruited pulmonary eosinophils have not substantially degranulated. These results suggest that, in this murine model of allergic inflammation, eosinophil degranulation and release of mMBP does not contribute to the observed pulmonary inflammation and airway hyperreactivity.

Abstract We evaluated the ability of eosinophil granule major basic protein (MBP) to stimulate interleukin (IL)-8 production by neutrophils. MBP over the concentration range of 0.1 to 10 μM stimulated the release of up to approximately 8 ng/ml IL-8. Incubation with 2 μM MBP showed that, after a 1 h lag, the level of IL-8 release increased with time for approximately 10 h. At the 2 μM concentration, eosinophil cationic protein, eosinophil-derived neurotoxin, and eosinophil peroxidase did not stimulate significant levels of IL-8 production. MBP stimulated 2-fold increases in IL-8 messenger RNA (mRNA) after 1 and 3 h of incubation, which were blocked by pretreatment with actinomycin D. However, stimulation with MBP did not produce an increase in the binding activity of nuclear factor (NF)-κB or activator protein-1. No NF–IL-6 binding activity was detected in the same nuclear extracts. In addition, stimulation with MBP prolonged the stability of IL-8 mRNA. MBP also induced transient increases in mRNA for macrophage inflammatory protein (MIP)-1α and MIP-1β, but did not stimulate the release of either chemokine. These findings indicate that MBP is selective among the eosinophil granule proteins as a stimulus for neutrophil IL-8 release and, further, that stimulation of neutrophil IL-8 release by MBP involves both transcriptional and posttranscriptional regulation. We postulate that MBP-induced release of IL-8 by neutrophils may contribute to the pathophysiology of acute asthma and other inflammatory lung diseases.

In heart failure (HF), the cardiac hormone natriuretic peptides (NPs) atrial (ANP), B-type (BNP), and C-type (CNP) play a key role to protect cardiac remodeling. The proprotein convertases corin and furin process their respective pro-NPs into active NPs. Here we define in a canine model of HF furin and corin gene and protein expression in normal and failing left atrium (LA) or ventricle (LV) testing the hypothesis that the NP proproteins convertases production is altered in experimental HF. Experimental canine HF was produced by rapid right ventricular pacing for 10 days. NPs, furin, and corin mRNA expression were determined by quantitative RT-PCR. Protein concentration or expression was determined by immunostaining, radioimmunoassay, or Western blot. Furin and corin proteins were present in normal canine LA and LV myocardium and vasculature and in smooth muscle cells. In normal canines, expression of NPs was dominant in the atrium compared with the ventricle. In experimental early stage HF characterized with marked atrial fibrosis, ANP, BNP, and CNP mRNA, and protein concentrations were higher in HF LA but not HF LV compared with normals. In LA, corin mRNA and protein expressions in HF were lower, whereas furin mRNA and protein expressions were higher than normals. NPs and furin expressions were augmented in the atrium in experimental early stage HF and, conversely, corin mRNA and protein expressions were decreased with atrial remodeling. Selective changes of these NP convertases may have significance in the regulation of pro-NP processing and atrial remodeling in early stage HF.