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Stephen I Rennard,1 Shawn X Sun,2 Stavros Tourkodimitris,2 Paul Rowe,2 Udo M Goehring,3 Dirk Bredenbröker,3 Peter M A Calverley4 1Division of Pulmonary, Critical Care, Sleep and Allergy, University of Nebraska Medical Center, Omaha, NE, USA; 2Forest Research Institute, Jersey City, NJ, USA; 3Takeda Pharmaceuticals International GmbH, Zurich, Switzerland; 4Department of Clinical Science, University of Liverpool, Liverpool, UK Purpose: Breathlessness is a predominant symptom of chronic obstructive pulmonary disease (COPD), making it a valuable outcome in addition to lung function to assess treatment benefit. The phosphodiesterase-4 inhibitor roflumilast has been shown to provide small but significant improvements in dyspnea, as measured by the transition dyspnea index (TDI), in two 1-year studies in patients with severe to very severe COPD. Patients and methods: To provide a more comprehensive assessment of the impact of roflumilast on dyspnea, post hoc analyses of four 1-year roflumilast studies (M2-111, M2-112, M2-124, and M2-125) in patients with moderate to very severe COPD were conducted. Results: In this pooled analysis (N=5,595), roflumilast significantly improved TDI focal scores versus placebo at week 52 (treatment difference, 0.327; P

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Abstract Background Phosphodiesterase 4 (PDE4) inhibitors increase intracellular cyclic adenosine monophosphate (cAMP), leading to regulation of inflammatory cell functions. Roflumilast is a potent and targeted PDE4 inhibitor. The objective of this study was to evaluate the effects of roflumilast on bronchoconstriction, airway hyperresponsiveness (AHR), and airway inflammation in mild asthmatic patients undergoing allergen inhalation challenge. Methods 25 subjects with mild allergic asthma were randomized to oral roflumilast 500 mcg or placebo, once daily for 14 days in a double-blind, placebo-controlled, crossover study. Allergen challenge was performed on Day 14, and FEV1 was measured until 7 h post challenge. Methacholine challenge was performed on Days 1 (pre-dose), 13 (24 h pre-allergen), and 15 (24 h post-allergen), and sputum induction was performed on Days 1, 13, 14 (7 h post-allergen), and 15. Results Roflumilast inhibited the allergen-induced late phase response compared to placebo; maximum % fall in FEV1 (p = 0.02) and the area under the curve (p = 0.01). Roflumilast had a more impressive effect inhibiting allergen-induced sputum eosinophils, neutrophils, and eosinophil cationic protein (ECP) at 7 h post-allergen (all p = 0.02), and sputum neutrophils (p = 0.04), ECP (p = 0.02), neutrophil elastase (p = 0.0001) and AHR (p = 0.004) at 24 h post-allergen. Conclusions This study demonstrates a protective effect of roflumilast on allergen-induced airway inflammation. The observed attenuation of sputum eosinophils and neutrophils demonstrates the anti-inflammatory properties of PDE4 inhibition and supports the roles of both cell types in the development of late phase bronchoconstriction and AHR. Trial Registration ClinicalTrials.gov: NCT01365533

Abstract Background As chronic obstructive pulmonary disease (COPD) is a heterogeneous disease it is unlikely that all patients will benefit equally from a given therapy. Roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor, has been shown to improve lung function in moderate and severe COPD but its effect on exacerbations in unselected populations was inconclusive. This led to the question of whether a responsive subset existed that could be investigated further. Methods The datasets of two previous replicate, randomized, double-blind, placebo-controlled, parallel-group studies (oral roflumilast 500 μg or placebo once daily for 52 weeks) that were inconclusive regarding exacerbations were combined in a post-hoc, pooled analysis to determine whether roflumilast reduced exacerbations in a more precisely defined patient subset. Results The pooled analysis included 2686 randomized patients. Roflumilast significantly decreased exacerbations by 14.3% compared with placebo (p = 0.026). Features associated with this reduction were: presence of chronic bronchitis with or without emphysema (26.2% decrease, p = 0.001), presence of cough (20.9% decrease, p = 0.006), presence of sputum (17.8% decrease, p = 0.03), and concurrent use of inhaled corticosteroids (ICS; 18.8% decrease, p = 0.014). The incidence of adverse events was similar with roflumilast and placebo (81.5% vs 80.1%), but more patients in the roflumilast group had events assessed as likely or definitely related to the study drug (21.5% vs 8.3%). Conclusions This post-hoc, pooled analysis showed that roflumilast reduced exacerbation frequency in a subset of COPD patients whose characteristics included chronic bronchitis with/without concurrent ICS. These observations aided the design of subsequent phase 3 studies that prospectively confirmed the reduction in exacerbations with roflumilast treatment. Trials registration ClinicalTrials.gov identifiers: NCT00076089 and NCT00430729.

Background: Evaluation of cardiovascular safety for new therapies for COPD is important because of a high prevalence of cardiac comorbidities in the COPD population. Hence, we evaluated the effects of roflumilast, a novel oral phosphodiesterase 4 inhibitor developed for the treatment and prevention of COPD exacerbations, on major adverse cardiovascular events (MACEs)., Methods: Intermediate- and long-term placebo-controlled clinical trials of roflumilast in COPD were pooled and assessed for potential cardiovascular events. Studies comprised 14 12- to 52-week placebo-controlled trials in patients with moderate to very severe COPD. All deaths and serious nonfatal cardiovascular events were evaluated by an independent adjudication committee blinded to study and treatment. The MACE composite of cardiovascular death, nonfatal myocardial infarction, and stroke was analyzed according to treatment group., Results: Of 6,563 patients receiving roflumilast, 52 experienced MACEs (14.3 per 1,000 patient-years), and of 5,491 patients receiving placebo, 76 experienced MACEs (22.3 per 1,000 patient-years). The MACE composite rate was significantly lower for roflumilast compared with placebo (hazard ratio, 0.65; 95% CI, 0.45-0.93; P = .019)., Conclusions: A lower rate of cardiovascular events was observed with roflumilast than with placebo in patients with COPD, indicating the lack of a cardiovascular safety signal when treating patients with COPD. Potential cardiovascular benefits of roflumilast should be evaluated in future controlled clinical trials.

Background: COPD exacerbations are associated with increased morbidity and mortality and can accelerate disease progression. The best predictor of future exacerbations is a history of previous exacerbations, which helps identify a frequent exacerbator phenotype. This post hoc analysis evaluated the effect of roflumilast, a drug known to reduce the COPD exacerbation rate, on exacerbation status., Methods: Pooled data from two 1-year, placebo-controlled, roflumilast (500 μg once daily) studies in patients with symptomatic COPD and severe airflow obstruction were evaluated (studies M2-124 and M2-125, ClinicalTrials.gov identifiers NCT00297102 and NCT00297115). A total of 3,091 patients were included in this analysis (62.5% with GOLD [Global Initiative for Chronic Obstructive Lung Disease] III COPD and 29.2% with GOLD 4 COPD). Based on their exacerbation frequency status in the previous year, patients were classified as frequent (two or more events) or infrequent (fewer than two events) exacerbators. Exacerbation frequency was analyzed at baseline and at year 1., Results: Among frequent exacerbators treated with roflumilast, 32.0% still had frequent exacerbations at year 1 compared with 40.8% of placebo-treated patients (risk ratio, 0.799; P = .0148). Among infrequent exacerbators, 17.5% of roflumilast-treated patients became frequent exacerbators at year 1 compared with 22.9% of those taking placebo (risk ratio, 0.768; P = .0018). The reduction in severe exacerbations leading to hospitalization/death was similar between subgroups and occurred independently of concomitant long-acting β2-agonists or previous inhaled corticosteroid treatment. When analyzed by severity of airflow limitation, 26.4% of roflumilast-treated frequent exacerbators with GOLD III COPD remained frequent exacerbators at year 1 compared with 38.9% of those taking placebo (P = .0042)., Conclusions: Treatment with roflumilast shifts patients from the frequent to the more stable infrequent exacerbator state., Trial Registry: ClinicalTrials.gov; No.: NCT00297102 and NCT00297115; URL: www.clinicaltrials.gov.

The purpose of this study was to investigate the effects of 500 μg roflumilast, taken once daily for 12 weeks, on airway physiology during rest and exercise in patients with moderate-to-severe chronic obstructive pulmonary disease. This randomised, double-blind, placebo-controlled, parallel-group study was conducted in 250 patients with a post-bronchodilator forced expiratory volume in 1 s (FEV(1)) of 30-80% predicted and a functional residual capacity of ≥ 120% pred. Pre- and post-bronchodilator spirometry and body plethysmography, and pre-bronchodilator constant work rate cycle exercise at 75% of peak work rate were evaluated. Exercise measurements included ventilation, breathing pattern, inspiratory capacity (IC) and arterial oxygen saturation measured by pulse oximetry (S(p,O(2))). Compared with placebo, 12 weeks of treatment with roflumilast was associated with: small but progressive increases in pre- and post-bronchodilator FEV(1) and FEV(1)/forced vital capacity; small decreases in specific airway resistance; and no significant changes in resting vital capacity, IC or measurements of lung hyperinflation. There was no treatment effect on exercise endurance time. At a standardised exercise time after roflumilast, compared with placebo, IC increased by 0.12 L (p = 0.008) and S(p,O(2)) increased by 0.7% (p = 0.020); peak ventilation increased by 1.9 L · min(-1) (p = 0.014). Roflumilast treatment was associated with progressive improvement of airway function but not lung hyperinflation. Newly described non-bronchodilator effects of roflumilast included small but consistent improvements in air trapping and S(p,O(2)) during exercise.

Background and Objective: Roflumilast, an oral, selective phosphodiesterase 4 inhibitor, has been shown to reduce exacerbations and improve pulmonary function in patients with COPD. This study examined the efficacy, safety and tolerability of roflumilast in Asian patients with COPD., Methods: Patients with COPD were randomized 1:1 to enter a 12-week treatment period and receive either oral roflumilast, 500 µg once daily, or placebo, following a single-blind, 4-week baseline period in which all patients received placebo. The primary end point was mean change in FEV₁ from baseline to each postrandomization visit during the treatment period. Other spirometric lung function measurements were evaluated as secondary end points. COPD exacerbations were monitored. Safety was assessed from clinical laboratory tests, vital signs, physical examination (including electrocardiogram) and monitoring of adverse events (AEs)., Results: Of 551 patients recruited, 410 were randomized and received at least one dose of study medication (roflumilast, n = 203; placebo, n = 207). Superiority of roflumilast over placebo was demonstrated by a statistically significant difference in postbronchodilator FEV₁ (79 mL, P < 0.0001). Other spirometry end points, including prebronchodilator FEV₁, pre-and postbronchodilator FEV₆, forced vital capacity and peak expiratory flow significantly favoured roflumilast over placebo. AEs were more common with roflumilast than with placebo, but were comparable with those reported in previous studies., Conclusions: Roflumilast, 500 µg once daily, improves pulmonary function in Asian patients with COPD. The safety and tolerability of roflumilast in this population was similar to that in a Caucasian population., (© 2011 The Authors. Respirology © 2011 Asian Pacific Society of Respirology.)

Background: Phosphodiesterase 4 (PDE4) inhibitors increase intracellular cyclic adenosine monophosphate (cAMP), leading to regulation of inflammatory cell functions. Roflumilast is a potent and targeted PDE4 inhibitor. The objective of this study was to evaluate the effects of roflumilast on bronchoconstriction, airway hyperresponsiveness (AHR), and airway inflammation in mild asthmatic patients undergoing allergen inhalation challenge., Methods: 25 subjects with mild allergic asthma were randomized to oral roflumilast 500 mcg or placebo, once daily for 14 days in a double-blind, placebo-controlled, crossover study. Allergen challenge was performed on Day 14, and FEV1 was measured until 7 h post challenge. Methacholine challenge was performed on Days 1 (pre-dose), 13 (24 h pre-allergen), and 15 (24 h post-allergen), and sputum induction was performed on Days 1, 13, 14 (7 h post-allergen), and 15., Results: Roflumilast inhibited the allergen-induced late phase response compared to placebo; maximum % fall in FEV1 (p = 0.02) and the area under the curve (p = 0.01). Roflumilast had a more impressive effect inhibiting allergen-induced sputum eosinophils, neutrophils, and eosinophil cationic protein (ECP) at 7 h post-allergen (all p = 0.02), and sputum neutrophils (p = 0.04), ECP (p = 0.02), neutrophil elastase (p = 0.0001) and AHR (p = 0.004) at 24 h post-allergen., Conclusions: This study demonstrates a protective effect of roflumilast on allergen-induced airway inflammation. The observed attenuation of sputum eosinophils and neutrophils demonstrates the anti-inflammatory properties of PDE4 inhibition and supports the roles of both cell types in the development of late phase bronchoconstriction and AHR., Trial Registration: ClinicalTrials.gov: NCT01365533.

The oral, selective phosphodiesterase type-4 inhibitor roflumilast reduces exacerbations and improves lung function in patients with severe-to-very severe chronic obstructive pulmonary disease (COPD). We investigated the efficacy and safety of roflumilast used concomitantly with long-acting β(2)-agonists (LABAs) to reduce exacerbations, and the influence of exacerbation history. Pooled data were analysed from two 12-month, placebo-controlled roflumilast (500 μg once daily) studies involving 3,091 patients with severe-to-very severe COPD. Approximately half of patients used concomitant LABAs; 39% used concomitant short-acting muscarinic antagonists (SAMAs); 27% were frequent exacerbators (two or more exacerbations per year). Roflumilast reduced the rate of moderate or severe exacerbations, with LABA (rate ratio (RR) 0.79, 95% CI 0.69-0.91; p=0.001) or without LABA (RR 0.85, 95% CI 0.74-0.99; p=0.039) and prolonged time both to first (p=0.035 with LABA, p=0.300 without LABA) and second (p=0.018 with LABA, p=0.049 without LABA) exacerbations. Frequent exacerbators experienced a reduction in moderate or severe exacerbations (RR 0.78, 95% CI 0.66-0.91; p=0.002). Similarly, roflumilast remained effective with concomitant SAMA. No differences arose in adverse events between these subgroups. Roflumilast may be used to reduce exacerbations and improve dyspnoea and lung function, without increasing adverse events in COPD patients receiving concomitant LABAs.

Objective: This study assesses the potential of the phosphodiesterase 4 inhibitor roflumilast to affect cardiac repolarization., Methods: In this randomized, placebo-controlled study (n = 80), 40 healthy subjects received moxifloxacin 400 mg p.o. (positive control for prolongation of QT/heart-rate corrected QT [QTc]) and another 40 received placebo. After a 1-day washout, subjects received placebo or ascending doses of roflumilast 500 (therapeutic dose), 750 or 1000 μg/day p.o., for 14, 7 and 14 days, respectively. QT intervals were measured and corrected for heart rate with a Fridericia algorithm (QTc(F)). The primary endpoint was the largest mean time-matched change in QTc(F) from baseline (day 1). Safety and tolerability were monitored., Results: Moxifloxacin gave a maximum time-matched change in QTc(F) versus baseline of 6.79 ms. Repeated administration of roflumilast 500 and 1000 μg resulted in maximum QTc(F) changes from baseline of -3.23 and -4.81 ms, respectively, confirming the absence of any QT/QTc prolongation at therapeutic and supra-therapeutic dosing. There were no changes in other electrocardiographic variables or time intervals, and roflumilast was well tolerated., Conclusions: Repeated administration of roflumilast at doses ≤ 1000 μg/day had no effect on cardiac repolarization or overall cardiac safety evaluations in healthy subjects., Clinical Trial Registration Number: ISRCTN63818313

Background: As chronic obstructive pulmonary disease (COPD) is a heterogeneous disease it is unlikely that all patients will benefit equally from a given therapy. Roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor, has been shown to improve lung function in moderate and severe COPD but its effect on exacerbations in unselected populations was inconclusive. This led to the question of whether a responsive subset existed that could be investigated further., Methods: The datasets of two previous replicate, randomized, double-blind, placebo-controlled, parallel-group studies (oral roflumilast 500 μg or placebo once daily for 52 weeks) that were inconclusive regarding exacerbations were combined in a post-hoc, pooled analysis to determine whether roflumilast reduced exacerbations in a more precisely defined patient subset., Results: The pooled analysis included 2686 randomized patients. Roflumilast significantly decreased exacerbations by 14.3% compared with placebo (p = 0.026). Features associated with this reduction were: presence of chronic bronchitis with or without emphysema (26.2% decrease, p = 0.001), presence of cough (20.9% decrease, p = 0.006), presence of sputum (17.8% decrease, p = 0.03), and concurrent use of inhaled corticosteroids (ICS; 18.8% decrease, p = 0.014). The incidence of adverse events was similar with roflumilast and placebo (81.5% vs 80.1%), but more patients in the roflumilast group had events assessed as likely or definitely related to the study drug (21.5% vs 8.3%)., Conclusions: This post-hoc, pooled analysis showed that roflumilast reduced exacerbation frequency in a subset of COPD patients whose characteristics included chronic bronchitis with/without concurrent ICS. These observations aided the design of subsequent phase 3 studies that prospectively confirmed the reduction in exacerbations with roflumilast treatment., Trials Registration: ClinicalTrials.gov identifiers: NCT00076089 and NCT00430729.

Background: Roflumilast is a targeted oral once-daily administered phosphodiesterase 4 (PDE4) inhibitor with clinical efficacy in chronic obstructive pulmonary disease (COPD). Results from in vitro studies with roflumilast indicate that it has anti-inflammatory properties that may be applicable for the treatment of COPD., Methods: In a crossover study, 38 patients with COPD (mean (SD) age 63.1 (7.0) years, post-bronchodilator forced expiratory volume in 1 s (FEV(1)) 61.0 (12.6)% predicted) received 500 microg roflumilast or placebo once daily for 4 weeks. Induced sputum samples were collected before and after 2 and 4 weeks of treatment. Differential and absolute cell counts were determined in whole sputum samples. Markers of inflammation were determined in sputum supernatants and blood. Spirometry was performed weekly., Results: Roflumilast significantly reduced the absolute number of neutrophils and eosinophils/g sputum compared with placebo by 35.5% (95% CI 15.6% to 50.7%; p = 0.002) and 50.0% (95% CI 26.8% to 65.8%; p<0.001), respectively. The relative proportion of sputum neutrophils and eosinophils was not affected by treatment (p>0.05). Levels of soluble interleukin-8, neutrophil elastase, eosinophil cationic protein and alpha(2)-macroglobulin in sputum and the release of tumour necrosis factor alpha from blood cells were significantly reduced by roflumilast compared with placebo treatment (p<0.05 for all). Post-bronchodilator FEV(1) improved significantly during roflumilast compared with placebo treatment with a mean difference between treatments of 68.7 ml (95% CI 12.9 to 124.5; p = 0.018)., Conclusion: PDE4 inhibition by roflumilast treatment for 4 weeks reduced the number of neutrophils and eosinophils, as well as soluble markers of neutrophilic and eosinophilic inflammatory activity in induced sputum samples of patients with COPD. This anti-inflammatory effect may in part explain the concomitant improvement in post-bronchodilator FEV(1).

Background: The central role of chronic inflammation of the airways in asthma pathogenesis is supported by the efficacy of corticosteroids in controlling clinical symptoms. However, the search continues for potentially safer anti-inflammatory alternatives. Roflumilast is an oral, once-daily phosphodiesterase type 4 inhibitor with anti-inflammatory activity in preclinical models of asthma and chronic obstructive pulmonary disease., Objective: To investigate the dose-ranging efficacy and safety of roflumilast in patients with mild-to-moderate asthma., Methods: Patients (N = 693) were randomized in a double-blind, parallel-group, phase 2/3 study. After a 1- to 3-week placebo run-in period, patients (mean forced expiratory volume in 1 second [FEV1], 73% of predicted) were randomized to receive 100, 250, or 500 microg of roflumilast once daily for 12 weeks. The primary end point was change from baseline in FEV1; secondary end points included change from baseline in morning and evening peak expiratory flow., Results: Roflumilast use significantly increased FEV1 (P < .001 vs baseline). Improvements from baseline in FEV1 at the last visit were 260, 320, and 400 mL for the 100-, 250-, and 500-microg dose groups, respectively. Roflumilast, 500 microg, was superior to roflumilast, 100 microg, by 140 mL in improving FEV1 (P = .002). There were also significant improvements from baseline in morning and evening peak expiratory flow in all the dose groups (P < or = .006). Roflumilast was well tolerated at all doses tested. Most adverse events were mild to moderate in intensity and transient., Conclusion: These results support the emerging role of roflumilast, 500 microg/d, in the treatment of asthma.

Background: Asthma is a chronic inflammatory disease with increasing incidence worldwide. Roflumilast is an oral, once-daily inhibitor of phosphodiesterase type 4 that prevents the breakdown of cyclic adenosine monophosphate levels, leading to inhibition of proinflammatory signaling., Objective: The objective of this study was to investigate the effects of repeated doses of 250 or 500 microg of roflumilast on asthmatic airway responses to allergen., Methods: Twenty-three patients with mild asthma with an FEV1 of 70% of predicted value or greater were enrolled in a randomized, double-blind, placebo-controlled, 3-period crossover study. Patients participated in 3 treatment periods (7-10 days) separated by washout periods (2-5 weeks). Patients received 250 microg of oral roflumilast, 500 microg of roflumilast, or placebo once daily. Allergen challenge was performed at the end of each treatment period, followed by FEV1 measurements over the ensuing 24 hours., Results: Late asthmatic reactions (LARs) were reduced by 27% (P = .0110) and 43% (P = .0009) in patients treated with 250 and 500 microg of roflumilast, respectively, versus placebo. Roflumilast, 250 and 500 microg, also attenuated early asthmatic reactions by 25% (P = .0038) and 28% (P = .0046), although not to the same extent as LAR attenuation. Roflumilast was well tolerated. No serious adverse events or discontinuations caused by adverse events were reported., Conclusion: Once-daily oral roflumilast modestly attenuated early asthmatic reactions and, to a greater extent, LARs to allergen in patients with mild allergic asthma. Pronounced suppression of late responses in an allergen challenge model suggests that roflumilast might have anti-inflammatory activity, which could provide clinical efficacy in chronic inflammatory pulmonary diseases, such as asthma.

Mucus secretion of the airways is under the control of a variety of intracellular second messenger systems. Cyclic nucleotides such as cGMP, coupled to the recently discovered nitric oxide system, and cAMP are of outstanding interest in this respect. The present study used the modified Ussing chamber technique and mucins labelled with (35)SO(4) to investigate mucus secretion in the rat trachea to clarify the contribution of these different second messenger systems to the control of mucin secretion.A variety of drugs affecting either the generation or the breakdown of the respective cyclic nucleotides were used. Neither drugs interfering with nitric oxide synthase nor the phosphodiesterase isoenzyme responsible for cGMP breakdown nor cGMP analogues were able to affect mucus secretion. In contrast, stimulation of adenylate cyclase or inhibition of the respective phosphodiesterase resulted in a potent increase of mucus secretion. In conclusion, we failed to show the involvement of the nitric oxide/cGMP system, whereas the cAMP system seems to be a very efficient regulator of mucus secretion in the rat trachea.

In sleep-disordered breathing (SDB), the greatest clinical relevance attaches to obstructive sleep apnea on account of its high prevalence and its concomitance with diseases of the cardiovascular system. The high mortality rate of untreated patients is believed to be due to the consequences of these latter diseases. Thus, for example, in addition to systemic arterial hypertension, elevated rates of such disorders as pulmonary hypertension, right heart insufficiency, coronary heart disease, myocardial infarction and stroke are also found. Up until quite recently bradycardic and tachycardic arrhythmias occurring during sleep have been held responsible of the increased mortality rate of these patients. Till the mid-eighties the prevalence of bradycardic arrhythmias was reported to be more than 30%. However, the importance of cardiac arrhythmias has been overestimated, as is supported in particular by current studies on large non-selected samples showing a much lower prevalence of apnea-related arrhythmias. In the differential diagnosis, however, consideration must be given to SDB in patients with nocturnal arrhythmias and heart rate variations.

Vasoactive intestinal polypeptide (VIP) is known as an important regulator of airway function. It has been suggested that VIP is involved in the pathogenesis of asthma due to its relaxant effects on smooth muscles. The present study was designed to characterize the effects of the peptides of the VIP family on airway mucus secretion. The peptides VIP, PHI, PACAP-27, PACAP-38, GLP-I, exendin-4, helodermin, helospectin I and helospectin II were investigated using isolated rat trachea. Data show that PACAP-27 is the most potent stimulator of airway mucus secretion (225% stimulation). The rank order of potency was PACAP-27 > VIP > helospectin II > PHI > exendin-4 = helodermin = helospectin I = PACAP-38. The addition of the protease inhibitor thiorphan enhanced the effects of PHI and helodermin, but not of the other peptides. These data show that the peptides of the VIP family stimulate airway mucus secretion differently.

The present study was designed to characterize the effects of unselective and isoenzyme-selective phosphodiesterase inhibitors on airway mucus secretion. The isolated rat trachea was incubated in a modified Ussing chamber. Mucus macromolecules were metabolically labelled with 35S. The inhibitors were applied at the luminal side. The unselective phosphodiesterase inhibitors theophylline, enprofylline and 3-isobutyl-methylxanthine stimulated mucus secretion in a concentration-dependent manner with half-maximum effects (EC50 values) at 690 microM, 400 microM and 46 microM, respectively. The adenosine antagonist 8-phenyltheophylline did not significantly stimulate mucus output, suggesting a negligible role of adenosine in the cellular mechanisms of mucus secretion. Adenosine itself did not increase radiolabel output. Rolipram, an inhibitor of phosphodiesterase isoenzyme IV, and zardaverine, which inhibits the isoenzymes III and IV, increased potently macromolecule output with EC50 values of 40 nM and 6 microM, respectively. The selective inhibitors of phosphodiesterase isoenzymes III and V, motapizone and zaprinast, did not influence airway mucus release, suggesting a relatively low activity of isoenzymes III and V in glands of rat trachea. The stimulatory effect of theophylline on airway mucus secretion may contribute to its beneficial action in chronic obstructive airway disease. Our data suggest that this effect is mediated predominantly by phosphodiesterase isoenzyme IV.

Amylin is a peptide containing 37 amino acids that is mainly expressed in pancreatic B-cells and cosecreted with insulin. It is the major component of the islet amyloid typically found in non-insulin-dependent diabetes mellitus. The amylin mRNA is present in RNA isolated from lung, and amylin receptors have been detected in lung membranes. Recently, amylin was shown to be a potent stimulator of airway mucus secretion. In this study, we characterized the site of amylin expression in rat trachea using a highly specific antiserum and the functional interaction of amylin with somatostatin-14 in mucus secreting cells. Amylin-like immunoreactivity is present in epithelial cells of submucous gland acini. The expression pattern varies, since some acini showed strong staining while others were negative. In addition, some columnar cells of the tracheal lining epithelium are strongly stained. Amylin applied submucosally is a potent stimulator of airway mucus secretion. Somatostatin inhibits this effect. Amylin may influence airway mucus secretion by paracrine and endocrine mechanisms, and our data suggest that amylin and somatostatin belong to the increasing number of peptides that are known to influence airway function.