http://www.erj.ersjournals.com/cgi/content/full/26/5/887
The effects of Aspergillus fumigatus challenge on exhaled and nasal NO levels
H. J. Stark1, J. T. Randell1, M-R. Hirvonen2, M. K. Purokivi1, M. H. Roponen2 and H. O. Tukiainen1
1 Dept of Respiratory Medicine, Kuopio University Hospital, and 2 Dept of Environmental Health, National Public Health Institute, Kuopio, Finland.
ABSTRACT
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
ACKNOWLEDGEMENTS
REFERENCES
Several studies have previously shown that exposure to indoor air microbes from moisture-damaged buildings can cause adverse health effects. Aspergillus fumigatus is one of the best-documented moulds causing health problems to those exposed.
In this study, inhalation of a commercial A. fumigatus solution was assessed, to establish if it would have effects on fractional exhaled (FeNO) and nasal (FnNO) nitric oxide levels and on lung function. The results were compared with placebo challenge.
A total of 28 subjects were divided into three study groups: group 1 had been exposed to occupational mould; group 2 consisted of atopic subjects; and group 3 was a control group. Some 3 h after A. fumigatus challenge, there was a considerable increase in FeNO, and a significant difference was observed between the A. fumigatus and placebo inhalations. The difference was seen in all study groups. No such differences were found in the levels of FnNO or nitrite in nasal lavage fluid. Subjects reported significantly more frequent respiratory tract symptoms after the A. fumigatus inhalation compared with placebo challenge.
In conclusion, it was shown here that inhalation challenge of Aspergillus fumigatus elevated fractional exhaled nitric oxide levels. An increase in fractional exhaled nitric oxide may serve as an indicator of respiratory inflammation of acute mould exposure.
Worldwide epidemiological studies have indicated that exposure to indoor air microbes present in moisture-damaged buildings is a potential cause of adverse health effects 1. Although there is a strong association between exposure to mouldy buildings and adverse health effects in the occupants of those buildings, the aetiological factors and mechanisms behind the reported symptoms are still unclear.
An increase in fractional exhaled nitric oxide (FeNO) concentrations is associated with several inflammatory diseases, such as asthma 2. Increased fractional nasal nitric oxide (FnNO) levels have been reported in patients with seasonal rhinitis 3. In addition, an elevated level of nitric oxide (NO) assessed as nitrite in nasal lavage fluid (NAL) has been detected after occupational exposure to microbes from moisture-damaged buildings 4, 5. However, no significant differences have been detected in the levels of FeNO between subjects exposed to microbes from a moisture-damaged building and control subjects 6.
It has been noted that the concentrations of airborne bacteria and fungal spores in moisture-damaged buildings are higher than in reference buildings 7. Conversely, the cytotoxicity and inflammatory potential of the same microbes can vary between different strains 8, and are also dependent on the conditions that the microbes grow in 9. Many of the fungi and bacteria isolated from moisture-damaged buildings produce secondary metabolites, which can be hazardous and cause health problems 10. Among those microbes Aspergillus spp. are common toxin producers and they are also opportunistic pathogens, capable of infecting lungs if the host defence of the exposed individual is suppressed 11. Within Aspergillus spp., Aspergillus fumigatus has been frequently isolated from the indoor air of moisture-damaged buildings where the occupants have a history of respiratory symptoms 12. This is of particular interest, as A. fumigatus may cause pulmonary aspergillosis with varying degrees of severity 13. It also produces highly toxic secondary metabolites such as gliotoxin, which can be harmful to health 14.
The main goal of this study was to assess if a commercial-purified A. fumigatus extract had acute effects on FeNO, FnNO and lung function. In addition, the effects of A. fumigatus challenge on the production of NO, assessed as nitrite, in NAL was measured. The results of A. fumigatus inhalation were compared with placebo challenge (allergen diluent). Since A. fumigatus can cause unexpected health effects, challenging human subjects via the inhalation of microbial extracts from moisture-damaged buildings cannot be approved for ethical reasons. Therefore, an extract officially approved by the Finnish National Agency for Medicine was used in this study.
One further area of interest was whether a subject's background was associated with a different response after the challenge. Therefore, the subjects were categorised into three different groups depending on their history: a group with chronic occupational exposure to moisture-damaged building microbes (referred to later as chronic mould exposure), a group of atopic subjects and a control group.
METHODS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
ACKNOWLEDGEMENTS
REFERENCES
Subjects
A total of 28 subjects volunteered to participate in the study. All the subjects were hospital personnel and they were working in two different hospital buildings in eastern Finland. The presence of moisture and mould problems in one of the buildings was confirmed by technical and microbiological investigations. The mean age of the subjects was 45 yrs (27–60). All but one of the subjects were females. The subjects were categorised into three groups as follows. Group 1: 13 subjects working in a moisture-damaged building, who are referred to in the following text as the mould-exposed group; group 2: five atopic nonasthmatic subjects without mould exposure; and group 3: a control group including 10 nonatopic, nonasthmatic subjects with no known mould exposure.
None of the subjects had experienced upper or lower respiratory tract infections during the 6 weeks prior to the study. Those taking any medication were excluded and no hard exercise was permitted during the days when measurements were taken. Smoking was not allowed during the study. Subjects in group 1 had experienced chronic mould exposure for several years. They had normal working days during the study period. Those diagnosed bronchial asthma were excluded. The study was approved by Kuopio University Ethical Committee. The subject characteristics are shown in table 1.
Protocols
Each subject randomly underwent two challenges where they inhaled A. fumigatus or placebo solution via a nebuliser (Spira elektro 2 flowmeterTM; Respiratory Care Center, Hämeenlinna, Finland) using an oronasal mask. The inhalation aerosol was generated from a 1-mL sample reservoir, with the nebulising pressure adjusted to 2 bar (flow rate 7.5 mL·min–1). The nebulisation time was 0.4 s, causing a mean±SD volume uptake of 6.5±0.3 µL of the solution per breath. The subjects inhaled each solution 60 times using controlled tidal volume respiration during a period of 5 min, and this was followed by a rest period of 5 min and subsequent spirometric measurements.
Forced expiratory volume in one second (FEV1) was measured in triplicate before the challenges, and the greatest value was used as the baseline. Four series of 10-fold dilutions of commercial A. fumigatus allergen (ALK-ABELLO, Madrid, Spain) were prepared immediately before the challenges and the inhalation was started with the lowest dilution. A. fumigatus solution was a purified allergen product accepted to be marketed in Finland by the National Agency for Medicine. The subjects inhaled the allergen at a starting dilution of 0.01 mg·mL–1 until the maximal concentration of 10 mg·mL–1 was administered. FEV1 was measured 5 min after each inhaled concentration. The difference between the baseline and lowest FEV1 was observed. The allergen diluent (physiological salt solution) was used as placebo. The placebo challenge protocol was identical to the A. fumigatus challenge, although the concentration of the solution did not change during the challenge. The challenges were performed 1 week apart at the same time of the day.
Lung function tests
Standard spirometric values (Medikro 905 SpirometerTM; Medikro, Kuopio, Finland) and pulmonary diffusion capacity (Type 2200 Sensor Medics BVTM; Sensor Medics, Bilthoven, The Netherlands) were measured according to American Thoracic Society guidelines 15, 16. Reference values compiled by Viljanen et al. 17 for the Finnish population were used. Baseline levels of spirometry and diffusion capacity were measured before the exposures. Lung function measurements were repeated 24 h after both exposures. The levels of FEV1 were monitored during the exposures, as described above. Peak expiratory flow (PEF) values were assessed before both challenges. PEF values were observed during the challenges and 3, 6 and 24 h after them.
Symptom questionnaire
After each inhalation of the A. fumigatus or placebo solution, the subjects filled in a standardised questionnaire with respect to upper (irritation of eyes, rhinorrhea, blocked nose, sneezing) and lower (cough, phlegm, dyspnoea) airway symptoms. The lungs of the patients were auscultated by a doctor before the exposures and after each inhalation to determine possible wheezing. The patients were asked to report if they had experienced any respiratory symptoms during the subsequent 24 h after the exposures.
Measurement of FeNO and FnNO
FeNO was measured using a chemiluminescence analyser (Sievers Model 280 NOATM; Sievers Instruments Inc., Boulder, CO, USA), according to the manufacturer's instructions using the same protocol previously described by Purokivi et al. 18. When measuring FeNO, the subjects performed a slow vital capacity manoeuvre for 30 s against a fixed expiratory resistance. The pressure level during exhalation was optimised by following the computer screen online to reach a constant flow rate during exhalation. Exhaled air flowed through a nonbreathing valve into a Teflon tubing system connected to the analyser. Recordings were taken using the single-breath program, and they were seen on a computer screen online. The relative SD between three exhaled samples was expected to be
The effects of Aspergillus fumigatus challenge on exhaled and nasal NO levels
H. J. Stark1, J. T. Randell1, M-R. Hirvonen2, M. K. Purokivi1, M. H. Roponen2 and H. O. Tukiainen1
1 Dept of Respiratory Medicine, Kuopio University Hospital, and 2 Dept of Environmental Health, National Public Health Institute, Kuopio, Finland.
ABSTRACT
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
ACKNOWLEDGEMENTS
REFERENCES
Several studies have previously shown that exposure to indoor air microbes from moisture-damaged buildings can cause adverse health effects. Aspergillus fumigatus is one of the best-documented moulds causing health problems to those exposed.
In this study, inhalation of a commercial A. fumigatus solution was assessed, to establish if it would have effects on fractional exhaled (FeNO) and nasal (FnNO) nitric oxide levels and on lung function. The results were compared with placebo challenge.
A total of 28 subjects were divided into three study groups: group 1 had been exposed to occupational mould; group 2 consisted of atopic subjects; and group 3 was a control group. Some 3 h after A. fumigatus challenge, there was a considerable increase in FeNO, and a significant difference was observed between the A. fumigatus and placebo inhalations. The difference was seen in all study groups. No such differences were found in the levels of FnNO or nitrite in nasal lavage fluid. Subjects reported significantly more frequent respiratory tract symptoms after the A. fumigatus inhalation compared with placebo challenge.
In conclusion, it was shown here that inhalation challenge of Aspergillus fumigatus elevated fractional exhaled nitric oxide levels. An increase in fractional exhaled nitric oxide may serve as an indicator of respiratory inflammation of acute mould exposure.
Worldwide epidemiological studies have indicated that exposure to indoor air microbes present in moisture-damaged buildings is a potential cause of adverse health effects 1. Although there is a strong association between exposure to mouldy buildings and adverse health effects in the occupants of those buildings, the aetiological factors and mechanisms behind the reported symptoms are still unclear.
An increase in fractional exhaled nitric oxide (FeNO) concentrations is associated with several inflammatory diseases, such as asthma 2. Increased fractional nasal nitric oxide (FnNO) levels have been reported in patients with seasonal rhinitis 3. In addition, an elevated level of nitric oxide (NO) assessed as nitrite in nasal lavage fluid (NAL) has been detected after occupational exposure to microbes from moisture-damaged buildings 4, 5. However, no significant differences have been detected in the levels of FeNO between subjects exposed to microbes from a moisture-damaged building and control subjects 6.
It has been noted that the concentrations of airborne bacteria and fungal spores in moisture-damaged buildings are higher than in reference buildings 7. Conversely, the cytotoxicity and inflammatory potential of the same microbes can vary between different strains 8, and are also dependent on the conditions that the microbes grow in 9. Many of the fungi and bacteria isolated from moisture-damaged buildings produce secondary metabolites, which can be hazardous and cause health problems 10. Among those microbes Aspergillus spp. are common toxin producers and they are also opportunistic pathogens, capable of infecting lungs if the host defence of the exposed individual is suppressed 11. Within Aspergillus spp., Aspergillus fumigatus has been frequently isolated from the indoor air of moisture-damaged buildings where the occupants have a history of respiratory symptoms 12. This is of particular interest, as A. fumigatus may cause pulmonary aspergillosis with varying degrees of severity 13. It also produces highly toxic secondary metabolites such as gliotoxin, which can be harmful to health 14.
The main goal of this study was to assess if a commercial-purified A. fumigatus extract had acute effects on FeNO, FnNO and lung function. In addition, the effects of A. fumigatus challenge on the production of NO, assessed as nitrite, in NAL was measured. The results of A. fumigatus inhalation were compared with placebo challenge (allergen diluent). Since A. fumigatus can cause unexpected health effects, challenging human subjects via the inhalation of microbial extracts from moisture-damaged buildings cannot be approved for ethical reasons. Therefore, an extract officially approved by the Finnish National Agency for Medicine was used in this study.
One further area of interest was whether a subject's background was associated with a different response after the challenge. Therefore, the subjects were categorised into three different groups depending on their history: a group with chronic occupational exposure to moisture-damaged building microbes (referred to later as chronic mould exposure), a group of atopic subjects and a control group.
METHODS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
ACKNOWLEDGEMENTS
REFERENCES
Subjects
A total of 28 subjects volunteered to participate in the study. All the subjects were hospital personnel and they were working in two different hospital buildings in eastern Finland. The presence of moisture and mould problems in one of the buildings was confirmed by technical and microbiological investigations. The mean age of the subjects was 45 yrs (27–60). All but one of the subjects were females. The subjects were categorised into three groups as follows. Group 1: 13 subjects working in a moisture-damaged building, who are referred to in the following text as the mould-exposed group; group 2: five atopic nonasthmatic subjects without mould exposure; and group 3: a control group including 10 nonatopic, nonasthmatic subjects with no known mould exposure.
None of the subjects had experienced upper or lower respiratory tract infections during the 6 weeks prior to the study. Those taking any medication were excluded and no hard exercise was permitted during the days when measurements were taken. Smoking was not allowed during the study. Subjects in group 1 had experienced chronic mould exposure for several years. They had normal working days during the study period. Those diagnosed bronchial asthma were excluded. The study was approved by Kuopio University Ethical Committee. The subject characteristics are shown in table 1.
Protocols
Each subject randomly underwent two challenges where they inhaled A. fumigatus or placebo solution via a nebuliser (Spira elektro 2 flowmeterTM; Respiratory Care Center, Hämeenlinna, Finland) using an oronasal mask. The inhalation aerosol was generated from a 1-mL sample reservoir, with the nebulising pressure adjusted to 2 bar (flow rate 7.5 mL·min–1). The nebulisation time was 0.4 s, causing a mean±SD volume uptake of 6.5±0.3 µL of the solution per breath. The subjects inhaled each solution 60 times using controlled tidal volume respiration during a period of 5 min, and this was followed by a rest period of 5 min and subsequent spirometric measurements.
Forced expiratory volume in one second (FEV1) was measured in triplicate before the challenges, and the greatest value was used as the baseline. Four series of 10-fold dilutions of commercial A. fumigatus allergen (ALK-ABELLO, Madrid, Spain) were prepared immediately before the challenges and the inhalation was started with the lowest dilution. A. fumigatus solution was a purified allergen product accepted to be marketed in Finland by the National Agency for Medicine. The subjects inhaled the allergen at a starting dilution of 0.01 mg·mL–1 until the maximal concentration of 10 mg·mL–1 was administered. FEV1 was measured 5 min after each inhaled concentration. The difference between the baseline and lowest FEV1 was observed. The allergen diluent (physiological salt solution) was used as placebo. The placebo challenge protocol was identical to the A. fumigatus challenge, although the concentration of the solution did not change during the challenge. The challenges were performed 1 week apart at the same time of the day.
Lung function tests
Standard spirometric values (Medikro 905 SpirometerTM; Medikro, Kuopio, Finland) and pulmonary diffusion capacity (Type 2200 Sensor Medics BVTM; Sensor Medics, Bilthoven, The Netherlands) were measured according to American Thoracic Society guidelines 15, 16. Reference values compiled by Viljanen et al. 17 for the Finnish population were used. Baseline levels of spirometry and diffusion capacity were measured before the exposures. Lung function measurements were repeated 24 h after both exposures. The levels of FEV1 were monitored during the exposures, as described above. Peak expiratory flow (PEF) values were assessed before both challenges. PEF values were observed during the challenges and 3, 6 and 24 h after them.
Symptom questionnaire
After each inhalation of the A. fumigatus or placebo solution, the subjects filled in a standardised questionnaire with respect to upper (irritation of eyes, rhinorrhea, blocked nose, sneezing) and lower (cough, phlegm, dyspnoea) airway symptoms. The lungs of the patients were auscultated by a doctor before the exposures and after each inhalation to determine possible wheezing. The patients were asked to report if they had experienced any respiratory symptoms during the subsequent 24 h after the exposures.
Measurement of FeNO and FnNO
FeNO was measured using a chemiluminescence analyser (Sievers Model 280 NOATM; Sievers Instruments Inc., Boulder, CO, USA), according to the manufacturer's instructions using the same protocol previously described by Purokivi et al. 18. When measuring FeNO, the subjects performed a slow vital capacity manoeuvre for 30 s against a fixed expiratory resistance. The pressure level during exhalation was optimised by following the computer screen online to reach a constant flow rate during exhalation. Exhaled air flowed through a nonbreathing valve into a Teflon tubing system connected to the analyser. Recordings were taken using the single-breath program, and they were seen on a computer screen online. The relative SD between three exhaled samples was expected to be
Vastaukset 1
Vanhimmat
Joo, kuten arvasin, niin tässä on tutkittu ns. perinteistä IgE-välitteistä allergiaa.
Ovat tutkineet altistetuilta myös IgE-vasta-aineet ja keltään ei löytynyt A. fumigatuksen IgE-vasta-ainetta, joten tulokset ovat negatiiviset. Kellään ei siis ollut A.fumigatuksen aiheuttamaa IgE-allergiaa eli astmaa.
Kun kysyin Lääkelaitokselta, että onko ttl:llä lupa käyttää tätä allergeeniuutetta altistuskokeissaan, niin sieltä vastattiin, että EI! Lisättiin, että voivat kyllä käyttää OMALLA VASTUULLA.
Tähän kyseiseen kokeeseen oli lupa annettu Kuopion yliopston eettiseltä toimikunnalta. Työterveyslaitoksella ei ole tietääkseni mistään päin lupaa käyttää tätä uutetta.
Siis, jos tässä kokeessa verestä löytyi A. fumigatuksen IgE-vasta-ainetta ja puhallustehot pienenivät vaaditun määrän, niin kyseisellä henkilöllä oli A. fumigatuksen aiheuttama astma. Kellään ei ollut näin!. Jos pelkät puhallustehot vain laskivat, niin kyseessä on vain ahtauttava keuhkoputkitulehdus.
Minusta tämä koe oli aika uhkarohkea, koska osa tutkittavista oli altistunut kosteusvauriorakennuksista. Tiedossa nimittäin on melko yleisesti, että A. fumigatus voi aiheuttaa homepölykeuhkoa.
ystävällisin hometerveisin
Pekka Nikkola