Induced sputum: comparison between isotonic and hypertonic saline solution inhalation in patients with asthma

Sputum induction and its diagnostic applications in inflammatory airway disorders: a review

Sputum induction is a technique that covers the induction and the subsequent processing of the expectorate primarily for the analysis of cells and different inflammatory biomarkers present in the airways to further understand the pathophysiology of different inflammatory respiratory disorders such as asthma and chronic obstructive pulmonary disease (COPD) as well as the diagnosis of lung diseases such as lung cancer, tuberculosis, and Pneumocystis jirovecii pneumonia. It is a non-invasive, safe, cost-effective, and reliable technique reported to exhibit a high success rate. However, due to being technically demanding and time-consuming and having the need of employing trained staff, this technique is only used in restricted research centres and in limited centres of clinical use. When the sputum is collected after induction, the primary goal is to obtain a differential cell count and evaluate the molecular biomarkers of airway inflammation such as eosinophil cationic protein, eosinophil-derived neurotoxin, major basic protein, tryptase, cytokine production [e.g., interleukin (IL)-5], albumin, and fibrinogen. In addition, cytospins from the processed sputum are used for immunocytochemical staining of cellular products such as EG-2 reactive protein, granulocyte-macrophage colony-stimulating factor, tumour necrosis factor alpha, and IL-8 that play significant roles in understanding the pathophysiology of inflammatory airway diseases. Nowadays, this technique can be further used by performing an additional analysis such as flow cytometry and in situ hybridisation on the sputum supernatant to investigate more the immune response and pathophysiological process of such various respiratory diseases. In addition, the application of sputum fluid phase to assess the biomarkers could be used more routinely in pathological laboratories for diagnosing lung cancer, COPD, and asthma as well as for monitoring lung cancer progression and asthma and COPD treatment, allowing for early detection and a better treatment provided by the clinicians.

Methodological Aspects of Induced Sputum

We aimed to conduct a state-of-the-art review of the current literature and offer further insights into the methodological aspects concerning induced sputum. The increasing popularity of sputum induction as a non-invasive and cost-effective method for obtaining lower airway secretions from patients who cannot produce sputum naturally has led to extensive research and applications in respiratory conditions like asthma and COPD. This technique allows for analysis of the cellular and biochemical components of the sputum to take place, providing insights into airway inflammation, immune cells, and help in predicting treatment response. Furthermore, induced sputum enables various analyses, including microRNA and gene expression studies and immunophenotyping. The procedure is generally safe and well tolerated, even in patients with airflow limitations; however, monitoring lung function is essential, especially in those with airway hyperresponsiveness. Optimal saline solution concentration and inhalation duration have been investigated, recommending a 15-20 min induction with hypertonic saline. Expectoration involves coughing at the end of each inhalation time. Careful handling during sputum processing is necessary for obtaining accurate results in cell cytology, immunocytochemistry, and in situ hybridization. Overall, induced sputum offers significant advantages as a preferred alternative for large-scale and repeated airway sampling, despite some technical demands and limitations.

Elevated eosinophils, IL5 and IL8 in induced sputum in asthma patients with accelerated FEV1 decline

BACKGROUND

Some patients with asthma present with accelerated lung function decline. This phenomenon is mostly associated with severe exacerbations and with poor asthma control.

OBJECTIVE

Our aim was to detect the extent of FEV1 decline in patients with mild asthma and to discriminate clinical, functional and inflammatory factors associated with accelerated FEV1 decline.

METHODS

We recruited 50 patients with mild asthma for pulmonary function testing and induced sputum sampling 12-15 years after the initial diagnosis. In 33 patients, from whom sputum of a good quality was obtained, inflammatory cells were counted and concentrations of cytokines IL-2, IL-4, IL-5, IL-8, IL-10, IFN-γ, angiogenin and VEGF in the sputum were measured by cytometric bead array.

RESULTS

Eighteen of 33 patients presented with accelerated FEV1 decline of more than 30 ml/year, with a mean (SEM) of 43.2 (3.9) ml/year, compared to 15 control patients with a FEV1 decline of 14.4 (2.1) ml/year. In the accelerated FEV1 decline group, we found elevated sputum levels of IL5 with a median (IQR) of 1.8 (0.4-3.2) pg/ml vs. 0.2 (0.1-1.2) pg/ml, p = 0.04; IL8 with a mean (SEM) of 1503 (194) pg/ml vs. 938 (177) pg/ml, p = 0.04; and eosinophils with a median (IQR) of 223 (41-1020) cells/μl vs. 39 (1-190) cells/μl, p = 0.03. No significant differences in other measured parameters were detected between the two groups.

CONCLUSION

Elevated sputum eosinophils, IL5 and IL8, which have a potential to stimulate airway remodelling, might be a useful non-invasive biomarkers and therapeutic targets of accelerated FEV1 decline in asthma patients.

Elevated complement factor H levels in asthmatic sputa

BACKGROUND

The alternative pathway of the complement system is known to play a role in the generation of asthmatic airway inflammation, but its regulatory complement protein, factor H has not been investigated in this disease.

PURPOSE

Our aim was to determine the local bronchial complement factor H (CFH) levels in asthma, and to investigate its relationship with complement activation, systemic CFH concentrations and clinical characteristics of patients.

METHODS

Induced sputum and plasma were collected from 21 healthy and 26 asthmatic subjects, and complement factor H and SC5b-9 concentrations were assessed by ELISA. Total protein concentrations were determined by biuret-reaction based microassay system from induced sputa.

RESULTS

CFH was detectable in 81 % of healthy and 100 % of asthmatic subjects, while SC5b-9 exceeded the detection limit in 62 % of healthy subjects and 85 % of asthmatic patients. Sputum CFH concentrations and CFH/protein ratios were increased in samples from asthmatic patients, and correlated with loss of lung function, asthma control, severity and medication intensity, but not with plasma CFH concentrations. Sputum CFH/protein ratios were in positive correlation also with sputum eosinophilic cell counts in asthma. SC5b-9 concentrations were not higher in the asthmatic sputa, although they correlated with sputum CFH concentrations.

CONCLUSIONS

CFH level is elevated on asthmatic airway surface, and may be associated with uncontrolled inflammation in asthma.

Measures of asthma control

PURPOSE OF REVIEW

Over the past decade, the concept of asthma control as distinct from asthma severity has been clearly defined. Well controlled asthma is the goal of therapy in all asthma patients. This review is a comprehensive description of the tools currently available for a methodical assessment of different aspects of asthma control in clinical practice and research.

RECENT FINDINGS

Several questionnaires for assessing asthma control have been extensively validated in adults. In children, validation data are less extensive. Considerable overlap exists between asthma control measures and measures of asthma-specific quality of life. Asthma-specific quality-of-life questionnaires have been used as primary outcome measures in major clinical trials evaluating asthma therapy. Biomarkers that reflect eosinophilic inflammation of the airways are used as intermediate outcome measures to reflect the biological basis of asthma control. There is some controversy, however, over which biomarkers are best incorporated into therapeutic algorithms that attempt to achieve maximal asthma control while minimizing treatment intensity.

SUMMARY

In designing clinical studies to evaluate different asthma therapies, researchers will find this review to be a useful resource in terms of choosing the appropriate tool for assessing asthma control. This is also a valuable resource for a methodical assessment of response to asthma therapy in routine clinical care.

Comparing the efficacy of nebulizer recombinant human DNase and hypertonic saline as monotherapy and combined treatment in the treatment of persistent atelectasis in mechanically ventilated newborns

BACKGROUND

The purpose of the present study was to compare the cost-effectiveness and efficacy of nebulizer recombinant human DNase (rhDNase) and hypertonic saline (HS) as monotherapy and combined treatment in neonatal atelectasis.

METHODS

Eighty-seven newborns with persistent atelectasis who did not respond to traditional treatment were studied retrospectively. Group 1 did not receive nebulizer drugs; Group 2 received 7%HS; Group 3 received rhDNase; and Group 4 received both 7%HS and rhDNase. Subjects' chest X-ray scores, partial pressure of CO(2), respiratory rate, fraction of inspired oxygen (FiO(2)) peak inspiratory pressure, atelectasis healing rate, median duration of nebulizer treatment and costs were compared.

RESULTS

Percentages of improvement in atelectasis on Day 3 of treatment in Group 1, Group 2, Group 3 and Group 4 were 27, 70, 81 and 95%, respectively, while median duration of treatment was 8.1, 3.3, 2.9 and 2.4 days, respectively. Comparison of chest X-ray scores, partial pressure of CO(2), respiratory rate, FiO(2) and peak inspiratory pressure values before and 48 h after treatment did not yield a significant difference for the control group (P > 0.05), while a marked improvement was observed in other groups for all parameters (P < 0.05). The most distinct improvement was in Group 4, followed by Group 3.

CONCLUSIONS

Although both the combined treatment with HS and rhDNase and their monotherapies are effective in the treatment of persistent atelectasis in newborns receiving mechanical ventilation, their combined use produces higher efficacy. The efficacy of rhDNase is superior to monotherapy with HS. Use of these two treatments concomitantly reduces the cost. To the best of our knowledge, the present study is the first to use HS alone or in combination with rhDNase in newborn patients.

Complement factor C5a in acute exacerbation of Chronic Obstructive Pulmonary Disease

The complement component C5a is a potent inflammatory peptide, which may be involved in the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD). We analysed the induced sputum and plasma of 28 patients with stable COPD, 12 healthy smokers and 7 non-smokers. In 13 of the patients with COPD, we also observed paired samples during acute exacerbation. The concentrations of C5a/C5a desArg and C3a/C3a desArg were measured using cytometric bead array. Both C5a and C3a concentrations in induced sputum of stable patients with COPD were significantly increased compared to the control groups of healthy smokers and non-smokers. In addition, there was a significant elevation in C5a values in exacerbation of COPD that was independent from the airway C3a levels. Airway C5a levels were negatively correlated with forced expiratory volume in first second (FEV1)% predicted and diffusing capacity of the lung (TLCO). Plasma C5a concentrations in patients with COPD were significantly higher than in healthy smokers, but no further significant systemic C5a elevation was detected with acute exacerbation of COPD. There was no important difference in local or systemic C5a concentrations between healthy smokers and non-smokers. These in vivo results clearly show that local and systemic C5a concentrations in COPD are elevated, and that the local, in contrast to systemic, C5a concentrations additionally increase in the acute exacerbation of COPD. It seems that the cigarette smoke is not related to C5a increase. The elevated local and systemic C5a levels, and additional individual local C5a increase during the exacerbation support the importance of C5a in COPD.

Induced sputum: a window to lung pathology

Sputum is recognized as a sampling method for the monitoring and assessment of chronic lung diseases such as asthma, COPD (chronic obstructive pulmonary disease) and cystic fibrosis. Sputum samples the central airways and its protein components (e.g. mucins and cytokines), cellular components (e.g. eosinophils and neutrophils) and microbiological components (e.g. viruses and bacteria) can be used as markers of disease severity, exacerbation, susceptibility or progression. This paper describes the basic constituents of induced sputum and how these influence the quantification and identification of novel biomarkers of chronic lung diseases using techniques such as proteomics.

MMP9 modulates tight junction integrity and cell viability in human airway epithelia

The family of zinc- and calcium-dependent matrix metalloproteases (MMPs) play an important role in remodeling of the airways in disease. Transcriptional regulation by proinflammatory cytokines increases lymphocyte-derived MMP9 levels in the airway lumen of asthmatics. Moreover, the levels of the MMP9 inhibitor, tissue inhibitor of metalloprotease (TIMP1), are decreased leading to increased protease activity. The mechanism by which MMP9 activity leads to asthma pathogenesis and remodeling remains unclear. Using a model of well-differentiated human airway epithelia, we found that apical MMP9 significantly increases transepithelial conductance. Moreover, apical MMP9 treatment decreased immunostaining of tight junction proteins suggesting disruption of barrier function. Consistent with this, viruses gained access to the epithelial basolateral surface after MMP9 treatment, which increased infection efficiency. All of these effects were blocked by TIMP1. In addition, loss of epithelial integrity correlated with increased epithelial cell death. Thus we hypothesized that MMP9 exerts its effects on the epithelium by cleaving one or more components of cell-cell junctions and triggering anoikis. Taken together, these data suggest that a component of airway remodeling associated with asthma may be directly regulated by MMP9.

Nebulized hypertonic saline in the treatment of viral bronchiolitis in infants

OBJECTIVE

To investigate the use of nebulized 3% hypertonic saline (HS) for treating viral bronchiolitis in moderately ill hospitalized infants by a prospective, randomized, double-blinded, controlled, multicenter trial.

STUDY DESIGN

A total of 96 infants (mean age, 4.7 months; range, 0.3 to 18 months) admitted to the hospital for treatment of viral bronchiolitis were recruited from 3 regional pediatric centers over 3 bronchiolitis seasons (December 2003 to May 2006). Patients were randomized to receive, in a double-blind fashion, repeated doses of nebulized 3% HS (treatment group) or 0.9% normal saline (NS; control group), in addition to routine therapy ordered by the attending physician. The principal outcome measure was hospital length of stay (LOS).

RESULTS

On an intention-to-treat basis, the infants in the HS group had a clinically relevant 26% reduction in LOS to 2.6 +/- 1.9 days, compared with 3.5 +/- 2.9 days in the NS group (P = .05). The treatment was well tolerated, with no adverse effects attributable to the use of HS.

CONCLUSIONS

The use of nebulized 3% HS is a safe, inexpensive, and effective treatment for infants hospitalized with moderately severe viral bronchiolitis.

Neutrophils in induced sputum from healthy children: role of interleukin-8 and oxidative stress

BACKGROUND

It is unclear why the neutrophil differential count in induced sputum (IS) from normal children is highly variable. Since levels of neutrophil chemoattractant cytokines and oxidative stress are determinants of airway neutrophilia in animal models, we sought to determine the association between IS neutrophils from healthy children and (i) interleukin-8 (IL-8) and (ii) the oxidative stress marker 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG).

METHODS

IS was done using hypertonic saline. The proportion (differential %) and the absolute number of IS neutrophils were determined by light microscopy. IS IL-8 and 8-oxodG were determined using ELISA. Spearman's rank correlation (Rs) was used to assess relationship between variables.

RESULTS

Adequate IS samples for analysis were obtained from 64/114 healthy children. The median (interquartile range) neutrophil differential count (n=64) was 20.6% (5.67-56), and absolute neutrophil count (n=53) was 0.11x10(6) (0.01-0.77). Both the % neutrophils, and the absolute neutrophil count were associated with IL-8 (Rs=0.67, p<0.0001 and 0.60, p<0.0001, respectively), but there was no association between IS neutrophil variables and 8-oxodG (n=40). The repeatability (intraclass correlation coefficient-Ri) of the neutrophil differential count was 0.58 (n=15).

CONCLUSIONS

The variation in the proportion and number of neutrophils in the lower airway of healthy children is associated with IL-8, but not with oxidative stress. The IS neutrophil differential count in healthy children is relatively stable over several months.

Repeated sputum inductions induce a transient neutrophilic and eosinophilic response

INTRODUCTION

Sputum induction is a tool to monitor airway inflammation, yet it may induce by itself a neutrophilic response when repeated within 24 to 48 h. This limits its repeated use in clinical trials.

OBJECTIVE

We aimed to investigate the induction and resolution of inflammation generated by repeated sputum inductions.

SUBJECTS AND DESIGN

Sixteen healthy intermittent smokers participated in a study on the short-term effects of smoking. The nonsmoking arm consisted of seven successive sputum inductions with increasing time intervals (3, 6, 12, 24, 48, and 96 h). Inflammatory cellular characteristics and different soluble mediators were investigated.

MEASUREMENTS AND RESULTS

The median percentage of sputum neutrophils increased significantly from baseline to 6 h (58.9% [range, 31.8 to 94.2%] to 83.2% [range, 26.7 to 98.3%], respectively). Surprisingly, the percentage of eosinophils also increased significantly from baseline to 6, 12, 24, and 48 h, as follows: 0.3% (range, 0.0 to 1.2%) to 1.7% (range, 0.0 to 15.5%), 2.2% (range, 0.5 to 12.5%), 1.2% (range, 0.0 to 4.8%), and 0.8% (range, 0.0 to 2.8%), respectively. Interleukin-8 increased significantly from baseline to 24 h (1,553 pg/mL [range, 462 to 8,192 pg/mL] to 2,178 pg/mL [range, 666 to 128,544 pg/mL]).

CONCLUSIONS

Repeated sputum inductions should preferably be avoided within 48 h. It induces not only a short-lived neutrophilic response but also a prolonged eosinophilic inflammatory response in healthy subjects, possibly by local changes in osmolarity, and subsequent epithelial and/or mast cell activation.

Carbon in airway macrophages and lung function in children

BACKGROUND

Epidemiologic studies indirectly suggest that the inhalation of carbonaceous particulate matter impairs lung function in children. Using the carbon content of airway macrophages as a marker of individual exposure to particulate matter derived from fossil fuel, we sought direct evidence of this association.

METHODS

Airway macrophages were obtained from healthy children through sputum induction, and the area of airway macrophages occupied by carbon was measured. Lung function was measured with the use of spirometry. We modeled the exposure to primary particulate matter (PM) that is less than 10 mum in aerodynamic diameter (PM10) at or near each child's home address. Linear regression was used to evaluate associations between carbon content of alveolar macrophages and variables that may affect individual exposure. To determine whether lung function that is reduced for other reasons is associated with an increase in the carbon content of airway macrophages, we also studied children with severe asthma.

RESULTS

We were able to assess the carbon content of airway macrophages in 64 of 114 healthy children (56 percent). Each increase in primary PM10 of 1.0 microg per cubic meter was associated with an increase of 0.10 microm2 (95 percent confidence interval, 0.01 to 0.18) in the carbon content of airway macrophages, and each increase of 1.0 microm2 in carbon content was associated with a reduction of 17 percent (95 percent confidence interval, 5.6 to 28.4 percent) in forced expiratory volume in one second, of 12.9 percent (95 percent confidence interval, 0.9 to 24.8 percent) in forced vital capacity, and of 34.7 percent (95 percent confidence interval, 11.3 to 58.1 percent) in the forced expiratory flow between 25 and 75 percent of the forced vital capacity. The carbon content of airway macrophages was lower in children with asthma than in healthy children.

CONCLUSIONS

There is a dose-dependent inverse association between the carbon content of airway macrophages and lung function in children. We found no evidence that reduced lung function itself causes an increase in carbon content.

A functional polymorphism in MMP-9 is associated with childhood atopic asthma

Although MMP-9 has been suggested to be important in inflammation and in the connective tissue remodeling associated with asthma, the genetic influences of the polymorphisms of MMP-9 are unclear. To examine whether polymorphisms in MMP-9 are associated with childhood atopic asthma, we identified a total of 17 polymorphisms and conducted an association study with asthma (n = 290) and controls (n = 638). 2127G>T and 5546G>A (R668Q) were significantly associated with the risk of childhood atopic asthma (p = 0.0032 and 0.0016, respectively). In haplotype analysis, we also found a positive association with a haplotype (p = 0.0053). MMP-9 was expressed in cultured human bronchial epithelial cells, and the mRNA expression level was upregulated by dsRNA. Furthermore, the promoter SNP -1590C>T, in strong linkage disequilibrium with 2127G>T, enhanced the transcriptional level of MMP-9. Thus, the MMP-9 gene might be involved in the development of asthma through functional genetic polymorphisms.

Use of exhaled breath condensate in the study of airway inflammation after hypertonic saline solution challenge

STUDY OBJECTIVES

Hypertonic saline solution inhalation is suspected to produce airway inflammation.

DESIGN

The aim of this study was to verify this hypothesis by measuring inflammatory markers in exhaled breath condensate (EBC) collected before and after sputum induction with hypertonic and isotonic saline solution.

PATIENTS AND METHODS

We enrolled 10 patients with asthma, 10 patients with COPD, and 7 healthy subjects with no history of lung disease. Levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha were measured in EBC by a specific enzyme immunoassay kit. Exhaled pH was measured after deaeration/decarbonation by bubbling with argon (350 mL/min) for 10 min by means of a pH meter.

MEASUREMENTS AND RESULTS

Exhaled IL-6 and TNF-alpha concentrations were greater and pH was decreased compared to baseline after hypertonic saline solution inhalation in each group of subjects studied. No changes were observed following isotonic saline solution inhalation. Concentrations of IL-6, TNF-alpha, and pH in EBC correlated.

CONCLUSIONS

These findings suggest that hypertonic saline solution inhalation could cause a low-grade inflammation in airways, and levels of inflammatory markers such as IL-6, TNF-alpha, and pH in EBC may be a useful noninvasive way to assess and monitor airway inflammation.

Carbon loading of alveolar macrophages in adults and children exposed to biomass smoke particles

Exposure to carbonaceous particles from biomass burning is associated with increased respiratory morbidity in both women and children in the developing world. However, the amount of carbon reaching lower airway cells has not been determined in these populations. Alveolar macrophages (AM) remove inhaled particulate matter (PM), and are implicated in the pathogenesis of PM-induced lung disease. In this study, we aimed to compare AM carbon loading in women and children exposed to biomass PM in Gondar, Ethiopia, with individuals exposed to fossil-fuel PM in the developed world (Leicester, UK). To achieve these aims, we sampled AM from Ethiopian mothers and children, and from UK adults and children using induced sputum (IS). AM were imaged under light microscopy, and the total two-dimensional surface area of carbon within each AM determined by image analysis. AM containing carbon were detected in all subjects. The total surface area of carbon per AM was higher in Ethiopian women (n=10) compared with UK adults (n=10, median 9.19 vs. 0.71 microm2/AM, p=0.0002). Similarly, the total surface area of carbon per AM was higher in Ethiopian children (n=10) compared with UK children (n=10, 3.32 vs. 0.44 microm2/AM, p=0.0002). However, loading in Ethiopian children was lower than paired maternal levels (3.32 vs. 9.19 microm2/AM, p=0.011). We conclude that analysis of AM obtained by induced sputum is a practical way of quantifying natural exposure of the lower airway to carbonaceous particles from the burning of biomass fuels.

Inhaling to mitigate exhaled bioaerosols

Humans commonly exhale aerosols comprised of small droplets of airway-lining fluid during normal breathing. These "exhaled bioaerosols" may carry airborne pathogens and thereby magnify the spread of certain infectious diseases, such as influenza, tuberculosis, and severe acute respiratory syndrome. We hypothesize that, by altering lung airway surface properties through an inhaled nontoxic aerosol, we might substantially diminish the number of exhaled bioaerosol droplets and thereby provide a simple means to potentially mitigate the spread of airborne infectious disease independently of the identity of the airborne pathogen or the nature of any specific therapy. We find that some normal human subjects expire many more bioaerosol particles than other individuals during quiet breathing and therefore bear the burden of production of exhaled bioaerosols. Administering nebulized isotonic saline to these "high-producer" individuals diminishes the number of exhaled bioaerosol particles expired by 72.10 +/- 8.19% for up to 6 h. In vitro and in vivo experiments with saline and surfactants suggest that the mechanism of action of the nebulized saline relates to modification of the physical properties of the airway-lining fluid, notably surface tension.

Is nebulized saline a placebo in COPD?

Background

Many trials of nebulized therapy have used nebulized saline as a "placebo". However, nebulized isotonic saline is sometimes used to assist sputum expectoration and relieve breathlessness in COPD patients. We designed this study to establish if nebulized saline had a placebo effect or a clinical effect.

Methods

40 patients were studied following hospital admission for exacerbated COPD (mean FEV1 30% predicted). Patients were randomised to single-blind administration of either 4 mls of nebulized isotonic saline using an efficient nebulizer (active group n = 20) or an inefficient nebulizer (placebo group n = 20). Spirometry and subjective breathlessness scores (Modified Likert Scale) were measured before nebulized treatment and 10 minutes after treatment.

Results

There was no significant change in FEV1 after active or placebo nebulized saline treatment. Patients reported a 4% improvement in mean breathlessness score following placebo (Wilcoxon test; p = 0.37) compared with 23% improvement following active nebulized saline (p = 0.0001). 65% of patients given active nebulized saline but only 5% of the placebo group reported that mucus expectoration was easier after the treatment.

Conclusions

This study lends support to the current use of nebulized saline to relieve breathlessness (possibly by facilitating sputum clearance) in COPD patients. Lung function was not affected. Nebulized saline can therefore be used as a placebo in bronchodilator studies involving COPD patients but it cannot be used as a placebo in trials assessing symptom relief.

Matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases mRNA transcripts in the bronchial secretions of asthmatics

Asthma is a chronic inflammatory disease characterized by profound extracellular matrix changes referred to as bronchial remodelling. In this study, we evaluated matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) mRNA expression in bronchial secretions of asthmatics and correlated MMPs modulations with the lung function as a reflection of the bronchial extracellular matrix remodelling. Quantitative RT-PCR was performed on cell pellets obtained from induced sputum in order to detect the mRNAs for MMP-1, -2, -3, -8, -9, -12, -13 TIMP-1, -2, while semiquantitative RT-PCR was performed to assess the expression of MMP-7, monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor-beta(1) (TGF-beta(1)). The mRNA transcripts for MMP-1, TIMP-1 and monocyte chemoattractant protein-1 (MCP-1) were increased in cell pellets of induced sputum from asthmatics when compared to controls (P<0.05), and the intensity of MMP-1 mRNA expression inversely correlated with the FEV(1) in asthmatics (r=-0.49, P<0.05). The MMP-1 mRNA/TIMP-1 mRNA ratio correlated with the levels of MCP-1 mRNA in asthmatics (r=0.47, P<0.05). There were no differences between the groups with respect to mRNA coding for MMP-2, -3, -7, -8, -9, -12, -13, -14, TIMP-2 and TGF-beta(1). We conclude that cells contained in the bronchial secretions from asthmatics express higher amounts of mRNA for MMP-1 and TIMP-1, perhaps related to an increased expression of MCP-1, which might contribute to the extracellular matrix changes observed during airway remodelling.

Complement factors c3a, c4a, and c5a in chronic obstructive pulmonary disease and asthma

Studies of animal models have shown that the activation of the complement system could have a role in chronic obstructive pulmonary disease (COPD) and asthma by promoting inflammation and enhancing airway hyperresponsiveness. We sought to determine whether the levels of complement factors C3a, C4a, and C5a are elevated at the site of inflammation in patients with COPD and patients with asthma. We analyzed the induced sputum of seven patients with COPD, ten patients with asthma, and twelve healthy nonsmokers. The concentrations of anaphylatoxins in the induced sputum were measured by cytometric bead array. We found significantly increased C5a/C5a desArg concentrations in supernatants of the induced sputum of patients with COPD (P = 0.007) and those with asthma (P = 0.002) compared with the control group. In patients with COPD the C5a/C5a desArg concentrations were significantly negatively correlated with lung diffusion coefficient (r = -0.71, P = 0.035). There was no significant difference in C3a/C3a desArg or C4a/C4a desArg measurements between the three groups of subjects. These in vivo results propose the involvement of complement factor C5a in the pathogenesis of COPD and asthma.

A comparative study of eicosanoid concentrations in sputum and urine in patients with aspirin-intolerant asthma

BACKGROUND

Although many studies have assumed that the overproduction of cysteinyl- leukotrienes (cys-LTs) and an imbalance of arachidonic acid metabolism may be plausible causes for the pathogenesis of aspirin-intolerant asthma (AIA), there has been little experimental evidence to substantiate this notion in lower airways of patients with AIA.

OBJECTIVES

The purpose of this study was to compare the eicosanoid concentrations in sputum and urine from patients with AIA.

METHODS

The concentrations of sputum cys-LTs, prostaglandin E2 (PGE2), PGF2alpha, PGD2 and thromboxane B2 were measured to assess local concentrations of eicosanoids in patients with AIA and in those with aspirin-tolerant asthma (ATA). The concentrations of two urinary metabolites, leukotriene E4 (LTE4) and 9alpha11betaPGF2, were also measured to corroborate the relationship between the eicosanoid biosynthesis in the whole body and that in lower airways.

RESULTS

The concentration of PGD2 in sputum was significantly higher in patients with AIA than in those with ATA (median, 5.3 pg/mL vs. 3.1 pg/mL, P < 0.05), but there was no significant difference in the concentration of the corresponding metabolite, 9alpha11betaPGF2, between the two groups. No differences were noted in the concentrations of other prostanoids in sputum between the two groups. The sputum cys-LT concentrations showed no differences between the two groups, in spite of the observation that the concentration of urinary LTE4 was significantly higher in patients with AIA than in those with ATA (median, 195.2 pg/mg-cre vs. 122.1 pg/mg-cre, P < 0.05). There was a significant correlation among the concentration of cys-LTs, the number of eosinophils and the concentration of eosinophil-derived neurotoxin (EDN) in sputum.

CONCLUSION

The urinary concentration of LTE4 does not necessary reflect cys-LT biosynthesis in lower airways. A significantly higher concentration of PGD2 in sputum from patients with AIA suggests the possible ongoing mast cell activation in lower airways.