Exhaled nitric oxide and bronchial responsiveness in healthy subjects exposed to organic dust

Abstract

Exhaled nitric oxide and bronchial responsiveness in healthy subjects exposed to organic dust. B-M. Sundblad, B-M. Larsson, L. Palmberg, K. Larsson. #ERS Journals Ltd 2002. ABSTRACT: Inhalation of organic dust from swine houses causes an intense inflammatory reaction in the respiratory tract, and increased bronchial responsiveness to methacholine in healthy subjects. The aims of the present study were to investigate whether exhaled nitric oxide (NO) is a marker of the inflammation caused by exposure to organic dust (swine dust), whether there is a relationship between an increase in exhaled NO and bronchial responsiveness, and also whether wearing a half-mask influences the airway reaction (assessed by exhaled NO) and the increased bronchial responsiveness.Thirty-three healthy nonatopic, nonsmoking subjects were exposed during 3 h of light work in a swine confinement building. Eleven of the subjects were wearing a half-mask and 22 were unprotected. Lung function, bronchial responsiveness and exhaled NO were measured before and after exposure.The provocative concentration causing a 20% fall in forced expiratory volume in one second fell by 2.7 (2.1-4.1) (median (25th-75th percentiles)) doubling concentration steps in subjects without a half-mask and by 1.5 (0.9-2.9) doubling concentration steps in subject wearing a mask. Exhaled NO increased from 7.5 (5.7-13.7) parts per billion (ppb) before to 13.4 (10.5-17.5) ppb after exposure in the unprotected group and was unaltered (8.3 (6.1-14.1) to 8.6 (6.6-14.6) ppb) in the group wearing a half-mask. There was no correlation between NO increase and provocative dose causing a 20% fall in the forced expiratory volume in one second decrease.In conclusion, bronchial responsiveness and exhaled nitric oxide increased after exposure to a swine confinement facility. Half-mask abolished the increase in exhaled nitric oxide levels, but influenced the increase in bronchial responsiveness to a minor extent. These results indicate that these two outcome measures reflect different aspects of airway inflammation induced by exposure to a farming environment. Eur Respir J 2002; 20: 426-431.

Acute respiratory effects of exposure to ammonia on healthy subjects

“…We had reason to believe that ammonia or other gases were possible candidates for that activation (34,35,36). The wearing of a respiratory protection device with a particle filter during swine dust exposure had no effect on complement activation, a minor effect on increased bronchial responsiveness, but a dramatic effect on the inflammatory airway response (3). Since the exposure did not induce any significant change in C3b in plasma, ammonia did not activate the complement in this study.…”

“…The use of a halfmask with a particle filter during exposure attenuates the inflammatory response but only slightly influences the increase in bronchial responsiveness (3). These results suggest that gases may be responsible for the increase that occurs in bronchial responsiveness after swine house exposure.…”

“…During the exposure, the participants rated the level of perceived discomfort on a questionnaire with 10 questions in Swedish (table 1), immediately before, during (3,28,58,88,118,148 and 178 minutes from the start of exposure), and after (270 minutes from the onset of exposure) the exposure. A 0-100 mm visual analogue scale (VAS) (0 = no symptoms, 100 = severe symptoms) was used for the ratings.…”

Effect of respirators equipped with particle or particle-and-gas filters during exposure in a pig confinement building

“…The upper and lower airway inflammatory reaction in healthy, previously unexposed persons is characterized by a multifold increase in inflammatory cells, predominately neutrophilic granulocytes and pro-inflammatory cytokines such as interleukins 6 and 8 (IL-6 and IL-8, respectively) and tumor necrosis factor (TNF) in blood and nasal and bronchoalvolar lavage fluid (4,5,8,9). When respirators with a particle filter were used during a 3-hour exposure in a pig confinement building the increase in exhaled nitric oxide, as well as the inflammatory response in the nose, were considerably attenuated in a group wearing a mask when compared with an unprotected group (7,10). Mask usage has undisputable protective effects on airway inflammation and exhaled nitric oxide after exposure; nevertheless, the use of a mask did not influence the increase in bronchial responsiveness.…”

“…In healthy nonfarmers, exposure in pig confinement facilities causes a massive influx of inflammatory cells (2)(3)(4)(5) into the respiratory tract, and about a threefold increase in bronchial responsiveness to methacholine (6,7). The upper and lower airway inflammatory reaction in healthy, previously unexposed persons is characterized by a multifold increase in inflammatory cells, predominately neutrophilic granulocytes and pro-inflammatory cytokines such as interleukins 6 and 8 (IL-6 and IL-8, respectively) and tumor necrosis factor (TNF) in blood and nasal and bronchoalvolar lavage fluid (4,5,8,9).…”