Extracellular matrix components and regulators in the airway smooth muscle in asthma

There is an intimate relationship between the extracellular matrix (ECM) and smooth muscle cells within the airways. Few studies have comprehensively assessed the composition of different ECM components and its regulators within the airway smooth muscle (ASM) in asthma. With the aid of image analysis, the fractional areas of total collagen and elastic fibres were quantified within the ASM of 35 subjects with fatal asthma (FA) and compared with 10 nonfatal asthma (NFA) patients and 22 nonasthmatic control cases. Expression of collagen I and III, fibronectin, versican, matrix metalloproteinase (MMP)-1, -2, -9 and -12 and tissue inhibitor of metalloproteinase-1 and -2 was quantified within the ASM in 22 FA and 10 control cases. In the large airways of FA cases, the fractional area of elastic fibres within the ASM was increased compared with NFA and controls. Similarly, fibronectin, MMP-9 and MMP-12 were increased within the ASM in large airways of FA cases compared with controls. Elastic fibres were increased in small airways in FA only in comparison with NFA cases. There is altered extracellular matrix composition and a degradative environment within the airway smooth muscle in fatal asthma patients, which may have important consequences for the mechanical and synthetic functions of airway smooth muscle.

Expression of smooth muscle and extracellular matrix proteins in relation to airway function in asthma

Background: Smooth muscle content is increased within the airway wall in patients with asthma and is likely to play a role in airway hyperresponsiveness. However, smooth muscle cells express several contractile and structural proteins, and each of these proteins may influence airway function distinctly. Objective: We examined the expression of contractile and structural proteins of smooth muscle cells, as well as extracellular matrix proteins, in bronchial biopsies of patients with asthma, and related these to lung function, airway hyperresponsiveness, and responses to deep inspiration. Methods: Thirteen patients with asthma (mild persistent, atopic, nonsmoking) participated in this cross-sectional study. FEV1 % predicted, PC20 methacholine, and resistance of the respiratory system by the forced oscillation technique during tidal breathing and deep breath were measured. Within 1 week, a bronchoscopy was performed to obtain 6 bronchial biopsies that were immunuhistochemically stained for alpha-SM-actin, desmin, myosin light chain kinase (MLCK), myosin, calponin, vimentin, elastin, type III collagen, and fibronectin. The level of expression was determined by automated densitometry. Results: PC20 methacholine was inversely related to the expression of alpha-smooth muscle actin (r = -0.62), desmin (r = -0.56), and elastin (r = -0.78). In addition, FEV1% predicted was positively related and deep inspiration-induced bronchodilation inversely related to desmin (r = -0.60), MLCK (r = -0.60), and calponin (r = -0.54) expression. Conclusion: Airway hyperresponsiveness, FEV1% predicted, and airway responses to deep inspiration are associated with selective expression of airway smooth muscle proteins and components of the extracellular matrix.

Airway epithelium mediates the anti-inflammatory effects of exercise on asthma

Airway epithelium plays an important role in the asthma physiopathology. Aerobic exercise decreases Th2 response in murine models of allergic asthma, but its effects on the structure and activation of airway epithelium in asthma are unknown. BALB/c mice were divided into control, aerobic exercise, ovalbumin-sensitized and ovalbumin-sensitized plus aerobic exercise groups. Ovalbumin sensitization occurred on days 0, 14, 28, 42, and aerosol challenge from day 21 to day 50. Aerobic exercise started on day 22 and ended on day 50. Total cells and eosinophils were reduced in ovalbumin-sensitized group submitted to aerobic exercise. Aerobic exercise also reduced the oxidative and nitrosative stress and the epithelial expression of Th2 cytokines, chemokines, adhesion molecules, growth factors and NF-kB and P2X7 receptor. Additionally, aerobic exercise increased the epithelial expression of IL-10 in non-sensitized and sensitized animals. These findings contribute to the understanding of the beneficial effects of aerobic exercise for chronic allergic airway inflammation, suggesting an immune-regulatory role of exercise on airway epithelium. (C) 2011 Elsevier B.V. All rights reserved.

Repeated stress reduces mucociliary clearance in animals with chronic allergic airway inflammation

We evaluated if repeated stress modulates mucociliary clearance and inflammatory responses in airways of guinea pigs (GP) with chronic inflammation. The GP received seven exposures of ovalbumin or saline 0.9%. After 4th inhalation, animals were submitted to repeated forced swim stressor protocol (5x/week/2 weeks). After 7th inhalation, GP were anesthetized. We measured transepithelial potential difference, ciliary beat frequency, mucociliary transport, contact angle, cough transportability and serum cortisol levels. Lungs and adrenals were removed, weighed and analyzed by morphometry. Ovalbumin-exposed animals submitted to repeated stress had a reduction in mucociliary transport, and an increase on serum cortisol, adrenals weight, mucus wettability and adhesivity, positive acid mucus area and IL-4 positive cells in airway compared to non-stressed ovalbumin-exposed animals (p < 0.05). There were no effects on eosinophilic recruitment and IL-13 positive cells. Repeated stress reduces mucociliary clearance due to mucus theological-property alterations, increasing acid mucus and its wettability and adhesivity. These effects seem to be associated with IL-4 activation. (C) 2010 Elsevier B.V. All rights reserved.

Airway smooth muscle thickness in asthma is related to severity but not duration of asthma

Asthma is characterised by an increased airway smooth muscle (ASM) area (ASMarea) within the airway wall. The present study examined the relationship of factors including severity and duration of asthma to ASMarea. The perimeter of the basement membrane (PBM) and ASMarea were measured on transverse sections of large and small airways from post mortem cases of fatal (n=107) and nonfatal asthma (n=37) and from control subjects (n=69). The thickness of ASM (ASMarea/PBM) was compared between asthma groups using multivariate linear regression. When all airways were considered together, ASMarea/PBM (in millimetres) was increased in nonfatal (median 0.04; interquartile range 0.013-0.051; p=0.034) and fatal cases of asthma (0.048; 0.025-0.078; p<0.001) compared with controls (0.036; 0.024-0.042). Compared with cases of nonfatal asthma, ASMarea/PBM was greater in cases of fatal asthma in large (p<0.001) and medium (p<0.001), but not small, airways. ASMarea/PBM was not related to duration of asthma, age of onset of asthma, sex or smoking. No effect due to study centre, other than that due to sampling strategy, was found. The thickness of the ASM layer is increased in asthma and is related to the severity of asthma but not its duration.

Bronchoscopic lung-volume reduction with Exhale airway stents for emphysema (EASE trial): randomised, sham-controlled, multicentre trial

Background Airway bypass is a bronchoscopic lung-volume reduction procedure for emphysema whereby transbronchial passages into the lung are created to release trapped air, supported with paclitaxel-coated stents to ease the mechanics of breathing. The aim of the EASE (Exhale airway stents for emphysema) trial was to evaluate safety and efficacy of airway bypass in people with severe homogeneous emphysema. Methods We undertook a randomised, double-blind, sham-controlled study in 38 specialist respiratory centres worldwide. We recruited 315 patients who had severe hyperinflation (ratio of residual volume [RV] to total lung capacity of >= 0.65). By computer using a random number generator, we randomly allocated participants (in a 2:1 ratio) to either airway bypass (n=208) or sham control (107). We divided investigators into team A (masked), who completed pre-procedure and post-procedure assessments, and team B (unmasked), who only did bronchoscopies without further interaction with patients. Participants were followed up for 12 months. The 6-month co-primary efficacy endpoint required 12% or greater improvement in forced vital capacity (FVC) and 1 point or greater decrease in the modified Medical Research Council dyspnoea score from baseline. The composite primary safety endpoint incorporated five severe adverse events. We did Bayesian analysis to show the posterior probability that airway bypass was superior to sham control (success threshold, 0.965). Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00391612. Findings All recruited patients were included in the analysis. At 6 months, no difference between treatment arms was noted with respect to the co-primary efficacy endpoint (30 of 208 for airway bypass vs 12 of 107 for sham control; posterior probability 0.749, below the Bayesian success threshold of 0.965). The 6-month composite primary safety endpoint was 14.4% (30 of 208) for airway bypass versus 11.2% (12 of 107) for sham control (judged non-inferior, with a posterior probability of 1.00 [Bayesian success threshold >0.95]). Interpretation Although our findings showed safety and transient improvements, no sustainable benefit was recorded with airway bypass in patients with severe homogeneous emphysema.

The Effects of Continuous Positive Airway Pressure on Prehypertension and Masked Hypertension in Men With Severe Obstructive Sleep Apnea

Obstructive sleep apnea and hypertension are common conditions that frequently coexist. Continuous positive airway pressure (CPAP) reduces blood pressure in patients with obstructive sleep apnea and sustained hypertension. However, the impact of CPAP on patients with obstructive sleep apnea and prehypertension and masked hypertension, conditions associated with increased cardiovascular risk, is unknown. Thirty-six male patients (age, 43 +/- 7 years; body mass index, 28.8 +/- 3.0 kg/m(2)) with untreated severe obstructive sleep apnea (apnea-hypopnea index, 56 +/- 22 events/hr on polysomnography) with diagnostic criteria for prehypertension and/or masked hypertension, based on office and 24-hour ambulatory blood pressure monitoring, respectively, were studied. The patients randomized to no treatment (control; n=18) or CPAP (n=18) for 3 months had similar frequency of prehypertension and masked hypertension at study entry. There were no significant changes in blood pressure in patients randomized to the control group. In contrast, patients randomized to CPAP presented significant reduction in office systolic (from 126 +/- 5 to 121 +/- 7 mm Hg; P=0.001) and a trend for diastolic blood pressure (from 75 +/- 7 to 73 +/- 8 mm Hg; P=0.08) as well as a significant decrease in daytime and nighttime systolic and diastolic blood pressure (P < 0.05 for each comparison). There was a significant reduction in the frequency of prehypertension (from 94% to 55%; P=0.02) and masked hypertension (from 39% to 5%; P=0.04) only in the CPAP group. In conclusion, effective CPAP therapy promotes significant reduction in the frequency of prehypertension and masked hypertension by promoting significant blood pressure reductions in patients with severe obstructive sleep apnea. (Hypertension. 2011;57[part 2]:549-555.)

Subchronic effects of nasally instilled diesel exhaust particulates on the nasal and airway epithelia in mice

Diesel exhaust is the major source of ultrafine particles released during traffic-related pollution. Subjects with chronic respiratory diseases are at greater risk for exacerbations during exposure to air pollution. This study evaluated the effects of subchronic exposure to a low-dose of diesel exhaust particles (DEP). Sixty male BALB/c mice were divided into two groups: (a) Saline: nasal instillation of saline (n = 30); and (b) DEP: nasal instillation of 30 mu g of DEP/10 mu l of saline (n = 30). Nasal instillations were performed 5 days a week, over 30 and 60 days. Animals were anesthetized with pentobarbital sodium (50 mg/kg intraperitoneal [i.p.]) and sacrificed by exsanguination. Bronchoalveolar lavage (BAL) fluid was performed to evaluate the inflammatory cell count and the concentrations of the interleukin (IL)-4, IL-10, and IL-13 by enzyme-linked immunosorbent assay (ELISA). The gene expression of oligomeric mucus/gel-forming (Muc5ac) was evaluated by real-time polymerase chain reaction (PCR). Histological analysis in the nasal septum and bronchioles was used to evaluate the bronchial and nasal epithelium thickness as well as the acidic and neutral nasal mucus content. The saline group (30 and 60 days) did not show any changes in any of the parameters. However, the instillation of DEP over 60 days increased the expression of Muc5ac in the lungs and the acid mucus content in the nose compared with the 30-day treatment, and it increased the total leukocytes in the BAL and the nasal epithelium thickness compared with saline for 60 days. Cytokines concentrations in the BAL were detectable, with no differences among the groups. Our data suggest that a low-dose of DEP over 60 days induces respiratory tract inflammation.

Salbutamol improves markers of epithelial function in mice with chronic allergic pulmonary inflammation

We investigated the effects of salbutamol on the markers of epithelial function in a murine model of chronic allergic pulmonary inflammation by recording the ciliary beat frequency (CBF) and the transepithelial potential difference (PD) in vivo. Mice were sensitized and received four challenges of ovalbumin (OVA group) or 0.9% saline (control group). Forty-eight hours after the 4th inhalation, we observed eosinophilia in the bronchoalveolar lavage and epithelium remodeling with stored acid mucus in the OVA group (P < 0.001). No difference in the baseline CBF was noticed between the groups; however, the OVA group had a significantly lower baseline PD (P = 0.013). Salbutamol increased the CBF in all groups studied, and the dose response curve to salbutamol increased the PD in the OVA group from 10(-4) M to 10(-2) M. We suggest that salbutamol affects the CBF and the depth of the periciliary layer, which, in great part, determines the ability of the cilia to propel the mucus layer. This effect may have a positive impact on airway mucociliary transport in asthma and may have clinical implications. (C) 2011 Elsevier B.V. All rights reserved.

Study into the use of continuous positive airway pressure in obstructive sleep apnoea-hypopnoea syndrome patients with daytime drowsiness

Background: Obstructive sleep apnoea-hypopnoea syndrome (OSAHS) is a respiratory disorder with high morbidity and mortality. Continuous positive airway pressure (CPAP) is the most commonly prescribed conservative treatment for adults with OSAHS. CPAP therapy normalises or decreases OSAHS symptoms and can reduce and prevent OSAHS complications. Aims: To evaluate adherence to nasal CPAP treatment and CPAP impact on daytime drowsiness. Method: A sample of 20 patients evaluated for daytime drowsiness using the Epworth sleepiness scale and interviewed for adherence to nasal CPAP use. Results: There was a significant decrease in the level of daytime sleepiness of the patients users of nasal CPAP (p=0.017); patients not using nasal CPAP experienced a decrease without statistical significance (p=0.162). 100% of CPAP users reported benefits and 50% of these reported related discomforts. Conclusions: Patients with OSAHS that use CPAP have a greater reduced level of sleepiness than those who do not use it.

Obstructive Sleep Apnea in Patients on Conventional and Short Daily Hemodialysis

Obstructive sleep apnea (OSA) is common among patients on maintenance hemodialysis. However, the factors associated with the origin of OSA as well as the cardiovascular consequences in this population are not completely understood. We evaluated, by standard overnight polysomnography, 24-hour ambulatory blood pressure (BP) monitoring and echocardiography in 30 patients (14 males, age 34 +/- 11 years, BMI 23.2 +/- 5.2) - 15 on short daily hemodialysis (SDH) and 15 matched patients on conventional hemodialysis (CHD). The hemodialysis dose (standard Kt/V) was higher in patients on SDH than on CHD (p = 0.001). OSA (apnea-hypopnea index 1 5 events/h) was present in 13 patients (43%). Patients with OSA were predominantly males (77 vs. 44%), presented a higher BMI (25.5 +/- 6.2 vs. 21.5 +/- 3.6), a larger neck circumference (38 +/- 1 vs. 34 +/- 1 cm) and a lower Kt/V (2.6 +/- 0.3 vs. 2.2 +/- 0.1) than patients with no OSA (p < 0.05). Neck circumference and lower Kt/V were independently associated with OSA on multivariate analysis. No patient with Kt/V > 2.5 (n = 10) presented OSA. On the other hand, hypertensive patients with OSA needed more BP control pills (p = 0.03). Despite similar BP control, patients with OSA presented a higher interventricular septum thickness (11.5 +/- 0.5 vs. 9.9 +/- 0.3 mm; p = 0.011). In conclusion, among patients on maintenance hemodialysis, the traditional risk factors for OSA are present and interact with hemodialysis efficiency. Among these patients, OSA is associated with difficult BP control and heart remodeling suggesting that OSA may contribute to poor cardiovascular outcome. Copyright (c) 2008 S. Karger AG, Basel

Effects of Residual Oil Fly Ash (ROFA) in Mice with Chronic Allergic Pulmonary Inflammation

transition metals, which are involved in the pathological effects of PM. The objective of this study was to investigate the effects of intranasal administration of ROFA on pulmonary inflammation, pulmonary responsiveness, and excess mucus production in a mouse model of chronic pulmonary allergic inflammation. BALB/c mice received intraperitoneal injections of ovalbumin (OVA) solution (days 1 and 14). OVA challenges were performed on days 22, 24, 26, and 28. After the challenge, mice were intranasally instilled with ROFA. After forty-eight hours, pulmonary responsiveness was performed. Mice were sacrificed, and lungs were removed for morphometric analysis. OVA-exposed mice presented eosinophilia in the bronchovascular space (p < .001), increased pulmonary responsiveness (p < .001), and epithelial remodeling (p = .003). ROFA instillation increased pulmonary responsiveness (p = .004) and decreased the area of ciliated cells in the airway epithelium (p = .006). The combined ROFA instillation and OVA exposure induced a further increase in values of pulmonary responsiveness (p = .043) and a decrease in the number of ciliated cells in the airway epithelium (p = .017). PM exposure results in pulmonary effects that are more intense in mice with chronic allergic pulmonary inflammation.

pcDNA-IL-12 vaccination blocks eosinophilic inflammation but not airway hyperresponsiveness following murine Toxocara canis infection

We have investigated the effect of pcDNA3-CpG and pcDNA-IL-12, delivered by intradermal gene gun administration, on the blood/lung eosinophilia, airway hyperresponsiveness as well as the immune response in a murine model of toxocariasis. Our results demonstrated that pcDNA-IL-12 but not pcDNA3-CpG vaccination Led to a persistent tower blood/bronchoalveolar eosinophilia following Toxocaro conis infection, as pcDNA3-CpG led only to an early transient blockage of eosinophil transmigration into bronchoalveolar fluid following T canis infection. Prominent Type-1 immune response was pointed out as the halt-mark of T canis infection following pcDNA-IL-12 vaccination. Outstanding IFN-gamma/IL-4 ratio besides tow levels of IgG1 with subsequent high IgG2a/IgG1 ratio further characterized a Type-1 polarized immunological profile in pcDNA-IL-12-vaccinated animals. Nevertheless, only pcDNA3-CpG was able to prevent airway hyperresponsiveness induced by T canis infection. The persistent airway hyperresponsiveness observed in pcDNA-IL-12-vaccinated animals demonstrated that the airway constriction involved other immunological mediator than those blocked by pcDNA-IL-12. Together, these data indicated that pcDNA-IL-12 and pcDNA3-CpG vaccines have distinct therapeutic benefits regarding the eosinophilic inflammation/airway hyperresponsiveness triggered by T canis infection, suggesting their possible use in further combined therapeutic interventions. (c) 2007 Elsevier Ltd. All rights reserved.

Metalloproteinase inhibition ameliorates hypertension and prevents vascular dysfunction and remodeling in renovascular hypertensive rats

Altered activity of matrix metalloproteinases (MMPs) is implicated in the vascular remodeling of hypertension. We examined whether increased MMP-2 expression/activity plays a role in the vascular remodeling and dysfunction found in the two-kidney, one-clip (2K-1C) hypertension. Sham operated or 2K-1C hypertension rats were treated with doxycycline 30 mg/(kg day) (or vehicle). Systolic blood pressure was monitored weekly. After 8 weeks of treatment, aortic rings were isolated to assess endothelium-dependent and independent relaxations. Quantitative morphometry of structural changes, collagen, and elastin contents in the aortic wall were studied in hematoxylin/eosin, Sirius Red, and Orceine stained aortic sections, respectively. Aortic MMP-2 levels were determined by gelatin zymography and aortic MMP-2 proteolytic activity was measured using DQ gelatin as the substrate after MMP-2 was captured by a specific antibody and immobilized on a microplate. Aortic MMP-2/tissue inhibitor of metalloprotemases (TIMP)-2 mRNA levels were determined by real time RT-PCR. Doxycycline attenuated 2K-1C hypertension (215 +/- 8 mmHg versus 167 +/- 13 mmHg in 2K-1C rats and 2K-1C + doxy rats, respectively; P < 0.01) and prevented the 35% reduction in endothelium-dependent vasorelaxation found in 2K-1C rats. Doxycycline prevented the increases in media thickness, and was associated with lower media/lumen and cross-sectional areas (all P<0.01). Doxycycline also prevented excessive collagen and elastin deposition in the vascular wall. Increased MMP-2 and Pro-MMP-2 levels and MMP-2 activity were found in the aortas of 2K-1C rats (all P<0.05). A 21-fold increase (P<0.001) in the ratio of MMP-2/TIMP-2 mRNA expression was found in the 2K-1C group, whereas this ratio remained unaltered in 2K-1C+doxy rats. Our results suggest that MMP-2 plays a role in 2K-1C hypertension and its structural and functional vascular changes, which were attenuated by doxycycline. (C) 2007 Elsevier Ireland Ltd. All rights reserved.

Matrix Metalloproteinase Inhibition Improves Cardiac Dysfunction and Remodeling in 2-Kidney, 1-Clip Hypertension

Background: Enhanced cardiac matrix metalloproteinase activity (MMPs) has been associated with ventricular remodeling and cardiac dysfunction. It is unknown whether MMPs contribute to systolic/diastolic dysfunction and compensatory remodeling in 2-kidney, 1-clip (2K1C) hypertensive rats. To test this hypothesis, we used 2K1C rats after 2 weeks of surgery treated or not with a nonspecific inhibitor of MMPs (doxycycline). Methods and Results: We found that blood pressure and +/-dP/dt increased in 2K1C rats compared with sham groups, and these parameters were attenuated by doxycycline treatment (P < .05). Doxycycline also reversed cardiac hypertrophy observed in 2K1C rats (P < .05). Hypertensive rats showed increased MMP-2 levels in zymograms and in the tissue by immunofluorescence (P < .05) compared with sham groups. Increased total gelatinolytic activity was observed in untreated 2K1C rats when compared with sham groups (P < .05). Doxycycline decreased total gelatinolytic activity in 2K1C rats to control levels (P < .05). Conclusion: An imbalance in gelatinolytic activity, with increased MMP-2 levels and activity underlies the development of morphological and functional alterations found in the compensatory hypertrophy observed in 2K1C hearts. Because function and structure were restored by doxycycline, the inhibition of MMPs or their modulation may provide beneficial effects for therapeutic intervention in cardiac hypertrophy. (J Cardiac Fail 2010;16:599-608)