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Exposure to bacteria in swine-house dust and acute inflammatory reactions in humans
W Zhiping1, P Malmberg, B M Larsson
1National Institute for Working Life, Solna, Sweden.
Abstract:
Inhalation of swine-house dust may cause an acute airway inflammatory condition (organic dust toxic syndrome). Thirty-eight healthy subjects were exposed to swine dust while weighing swine for 3 h. We studied the correlation between acute health effects and the inhaled bacterial exposure markers peptidoglycan (the main constituent of the cell walls of gram-positive bacteria, but also present in lesser amounts in gram-negative bacteria) and lipopolysaccharides (LPS; present only in gram-negative bacteria). LPS activity in airborne dust was measured with the Limulus amebocyte lysate assay (LPS(LAL)), and the total LPS was estimated from 3-hydroxy fatty acids, which were measured with gas chromatography-mass spectrometry (GC-MS) (LPS(GC-MS)). Peptidoglycan was estimated from muramic acid measured with GC-MS. The median (25th to 75th percentile) concentration of inhalable dust was 21 (16 to 25) mg/m3. LPS(LAL) was 1.2 (0.9 to 1.4) microg/m3; LPS(GC-MS) was 3.9 (2.5 to 4.9) microg/m3; and the peptidoglycan concentration in airborne dust was 6.5 (2.7 to 13) microg/m3. All exposure markers correlated significantly with an increase in serum interleukin-6. LPS(LAL) showed the highest correlation (r2 = 0.29) and total inhaled dust the lowest (r2 = 0.09). LPS(LAL) also correlated with symptoms and with an increase in bronchial responsiveness and decrease in vital capacity (VC). Peptidoglycan, but not LPS(LAL), correlated with an increase in the blood granulocyte concentration and in body temperature. The results suggest that several microbial agents in inhaled swine-house dust may contribute to acute systemic health effects.
Insights
Inhaling swine dust can cause organic dust toxic syndrome. Bacterial components like lipopolysaccharides (LPS) and peptidoglycan in dust correlate with inflammatory responses and acute health effects in healthy subjects.
Area of Science:
- Environmental Health
- Occupational Medicine
- Toxicology
Background:
- Swine-house dust exposure is linked to acute airway inflammation, known as organic dust toxic syndrome.
- Bacterial components, including peptidoglycan and lipopolysaccharides (LPS), are present in swine dust and may contribute to health effects.
Purpose of the Study:
- To investigate the correlation between inhaled bacterial exposure markers (peptidoglycan and LPS) and acute health effects in subjects exposed to swine dust.
- To compare the efficacy of different measurement methods for LPS (Limulus amebocyte lysate assay - LPS(LAL) and gas chromatography-mass spectrometry - LPS(GC-MS)).
Main Methods:
- Thirty-eight healthy subjects were exposed to swine dust for 3 hours.
- Airborne dust, peptidoglycan (via muramic acid), LPS(LAL), and LPS(GC-MS) were measured.
- Serum interleukin-6, bronchial responsiveness, vital capacity, blood granulocyte concentration, and body temperature were assessed.
Main Results:
- All measured exposure markers (LPS(LAL), LPS(GC-MS), peptidoglycan) correlated significantly with increased serum interleukin-6.
- LPS(LAL) demonstrated the highest correlation with interleukin-6 (r2 = 0.29) and was also associated with symptoms, increased bronchial responsiveness, and decreased vital capacity.
- Peptidoglycan correlated with increased blood granulocyte concentration and body temperature, but LPS(LAL) did not.
Conclusions:
- Inhaled swine dust contains microbial agents, including LPS and peptidoglycan, that contribute to acute systemic health effects.
- LPS(LAL) appears to be a significant marker for inflammatory responses and respiratory effects following swine dust exposure.
- Both LPS and peptidoglycan may play distinct roles in the acute toxicological response to swine dust inhalation.