Comparison Between Hypertonic and Isotonic Saline-Induced Sputum in the Evaluation of Airway Inflammation in Subjects With Moderate Asthma

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The aim of this study was to assess whether hyperosmolarity affects granulocyte mediator levels in induced sputum of asthmatic subjects.A total of 32 mild-to-moderate asthmatics, who inhaled either hypertonic (HS; 4.5% NaCl) or isotonic (IS; 0.9% NaCl) solutions for 15 min, were studied. Selected sputum was used for analysis. Eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO) and free neutrophil elastase (NE) were measured in sputum supernatant.Sample weight, total and differential cell counts, as well as viability and squamous cell percentage were no different after the two tests. No significant differences in ECP, EPX, MPO or NE levels were observed between HS-and IS-induced sputum. Repeatability of the two tests was good for macrophages, neutrophils, eosinophils, ECP, EPX and NE, but not for lymphocytes and MPO.In conclusion, hyperosmolarity does not affect sputum cell counts and the levels of most granulocyte degranulation markers examined in this study, confirming that both hypertonic and isotonic solutions can be reliably used to induce sputum in asthmatics. Hypertonic saline (HS) inhalation is currently used to collect sputum from the airways of asthmatic subjects who do not produce sputum spontaneously. However, in high-risk subjects, inhalation with isotonic saline (IS) is recommended, at least at the beginning of sputum induction [1]. Thus, it is important that sputum samples collected after either induction method have a similar composition. Several studies have compared the cell composition of sputum obtained after the two different methods of induction and showed good concordance for inflammatory cell percentages [2-4]; however, few studies have compared the concentrations of soluble mediators in the sputum supernatant [5].A large number of in vivo and in vitro studies have shown that hypertonic solutions modify mediator release from inflammatory cells by acting as a strong stimulus for cell activation [6-8], or, conversely, by inhibiting leukocyte degranulation [5,9]. In sputum induction, the hypertonic solution might increase osmolarity of the airway lining fluid, thus influencing mediator release from granulocytes during inhalation or sputum processing, or both.Therefore, the aim of this study was to compare preformed soluble mediator levels derived from eosinophils and neutrophils, such as eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO) and neutrophil elastase (NE), in induced sputum obtained by means of either HS or IS inhalation in mild-to-moderate asthmatic subjects. In addition, the total and differential cell counts were also evaluated in the same sputum samples. Subjects and methods SubjectsA total of 44 mild-to-moderate asthmatic subjects, who were recruited from the authors9 asthma clinic, were examined. Asthma was diagnosed at the time of the first examination, according to internationally accepted criteria [10], after assessing reversible airway obstruction and/or nonspecific bronchial hyperresponsiveness ...

Section: Discussionsupporting

confidence: 74%

mentioning

confidence: 99%

Granulocyte markers in hypertonic and isotonic saline-induced sputum of asthmatic subjects

Cianchetti

Bacci²,

Ruocco³

et al. 2004

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“…It has been shown previously that induced sputum does not have a significantly different cellular composition when compared with spontaneous sputum from subjects with COPD [12]. Moreover, another study showed that inhalation of hypertonic saline yielded more cells than inhalation of normal saline, yet with a similar differential count [13]. The differences in cellular counts between induced sputum and BW and BAL fluid, therefore, probably reflect differences between compartments in the lung.…”

Section: Discussionmentioning

confidence: 88%

Comparison of induced sputum with bronchial wash, bronchoalveolar lavage and bronchial biopsies in COPD

Rutgers¹,

Timens²,

Kaufmann³

et al. 2000

194

132

It is unclear how cellular and soluble inflammatory markers in induced sputum relate to markers in lavage fluid and biopsies in chronic obstructive pulmonary disease (COPD). This was investigated and also the possible differences between subjects with COPD and healthy controls assessed.Eighteen nonatopic subjects with COPD and 11 healthy controls were studied. Sputum was induced by inhalation of hypertonic saline. The airways were lavaged, using the first 50 mL for bronchial wash (BW) and the subsequent 150 mL for bronchoalveolar lavage (BAL), and biopsies were taken from subsegmental carinae.Neutrophils were the predominant cell type in sputum in COPD (median 77.3%) but not in BW (5.5%) and BAL fluid (1.7%). Differential cell counts in sputum did not correlate with the counts in BW or BAL fluid or biopsies, whereas sputum eosinophil cationic protein (ECP) levels correlated with BW fluid ECP levels (r=0.66, p=0.007) and sputum interleukin-8 (IL-8) concentration with BAL fluid IL-8 concentration (r= 0.52, p=0.026). Subjects with COPD had a higher percentage of sputum neutrophils and eosinophils and higher concentrations of ECP and IL-8 than healthy controls. The higher percentages of eosinophils and concentrations of ECP were also seen in BW and BAL fluid. Finally, higher numbers of macrophages and eosinophils were found in biopsies.In conclusion, induced sputum is derived from a different compartment from BW and BAL fluid and biopsies. Induced sputum may be useful for studying the contribution of luminal neutrophils and eosinophils in chronic obstructive pulmonary disease. Eur Respir J 2000; 15: 109±115.

“…The concentration of saline used for sputum induction has ranged 0.9-7% in different studies [5,8,12,25]. Some investigators change concentration during the procedure, starting with 3% and subsequently increasing to 4 and 5% [9,10].…”

Section: Concentration Of Saline Solution and Nebuliser Outputmentioning

confidence: 99%

“…There is no difference in the cellular composition of sputum induced with either isotonic or hypertonic saline [25], and different saline concentrations do not affect total and differential cell counts in selected portions of induced sputum [18]. To date, only one study has investigated whether increasing saline concentration during induction has any advantage over using a single concentration [18].…”

Section: Concentration Of Saline Solution and Nebuliser Outputmentioning

confidence: 99%

Sputum induction

Chanez¹,

Holz²,

Ind³

et al. 2002

125

The aim of sputum induction is to collect an adequate sample of secretions from lower airways in subjects who do not produce sputum spontaneously in order to study the features of airway inflammation in asthma and other respiratory disorders. Inhalation of isotonic or hypertonic solutions administered by nebulisation has been demonstrated to induce a small amount of airway secretion that can be expectorated and analysed. The mechanisms by which this occurs are not known, but both direct and indirect mechanisms are likely to be involved. It is believed that the increased osmolarity of the airway lining fluid increases vascular permeability in the bronchial mucosa and induces production of mucus by submucosal glands. Animal studies have shown that hypertonic saline increases vascular permeability in the airways, and this effect can be modulated by capsaicin [1]. However, in vivo instillation of hypertonic solution into the airways of animals and humans induces an increase in the levels of several mediators but no rise in levels of albumin or other markers of increased vascular permeability [2,3]. Therefore, this hypothesis has not been confirmed, and only preliminary measurements of sputum osmolarity after induction have been reported with conflicting results [4]. Conversely, previous reports have demonstrated increased clearance of secretions from the airways in humans after administration of hypertonic saline aerosol [5], perhaps by facilitating the collection of small amounts of pre-existing airway secretions.Although sputum induction has been used extensively since the 1990s, few methodological studies have examined the influence of various technical factors on the feasibility and repeatability of sputum induction and collection. As with other techniques, the lack of a "gold standard" makes it hard to evaluate the influence of these technical factors on the adequacy and accuracy of sputum induction.The technique of sputum induction consists of inhaling an aerosol of saline (either normal or hypertonic) over different time-periods. Volunteers/ patients are instructed to expectorate into a container. Various issues must be considered with regard to this procedure: 1) facilities, equipment and personnel; 2) bronchodilator pretreatment; 3) pulmonary function monitoring; 4) concentration of saline solution and nebuliser output; 5) duration of inhalation; 6) expectoration technique; 7) spontaneous versus induced sputum; and 8) frequency of sputum induction. The influence of these factors on the feasibility of the technique must be evaluated in terms of the success rate, repeatability and accuracy of the results obtained.