Muramic acid, endotoxin, 3-hydroxy fatty acids, and ergosterol content explain monocyte and epithelial cell inflammatory responses to agricultural dusts.
In agricultural and other environments, inhalation of airborne microorganisms is linked to respiratory disease development. Bacterial endotoxins, peptidoglycans, and fungi are potential causative agents, but relative microbial characterization and inflammatory comparisons amongst agricultural dusts are not well described. The aim of this study was to determine the distribution of microbial endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, and ergosterol and evaluate inflammatory responses in human monocytes and bronchial epithelial cells with various dust samples. Settled surface dust was obtained from five environments: swine facility, dairy barn, grain elevator, domestic home (no pets), and domestic home with dog. Endotoxin concentration was determined by recombinant factor C (rFC). 3-OHFA, muramic acid, and ergosterol were measured using gas chromatography-mass spectrometry. Dust-induced inflammatory cytokine secretion in human monocytes and bronchial epithelial cells was evaluated. Endotoxin-independent dust-induced inflammatory responses were evaluated. Endotoxin and 3-OHFA levels were highest in agricultural dusts. Muramic acid, endotoxin, 3-OHFA, and ergosterol were detected in dusts samples. Muramic acid was highest in animal farming dusts. Ergosterol was most significant in grain elevator dust. Agricultural dusts induced monocyte tumor necrosis factor (TNF) alpha, interleukin (IL)-6, IL-8, and epithelial cell IL-6 and IL-8 secretion. Monocyte and epithelial IL-6 and IL-8 secretion was not dependent on endotoxin. House dust(s) induced monocyte TNFalpha, IL-6, and IL-8 secretion. Swine facility dust generally produced elevated responses compared to other dusts. Agricultural dusts are complex with significant microbial component contribution. Large animal farming dust(s)-induced inflammation is not entirely dependent on endotoxin. Addition of muramic acid to endotoxin in large animal farming environment monitoring is warranted.
Poole
Jill A
JA
Omaha Veterans Administration Medical Center, Omaha, Nebraska, USA. japoole@unmc.edu
Dooley
Gregory P
GP
Saito
Rena
R
Burrell
Angela M
AM
Bailey
Kristina L
KL
Romberger
Debra J
DJ
Mehaffy
John
J
Reynolds
Stephen J
SJ
D000383:Agriculture; D000395:Air Pollutants, Occupational / Q000009:adverse effects / Q000032:analysis*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D004285:Dogs; D004391:Dust / Q000032:analysis*; D004731:Endotoxins / Q000009:adverse effects / Q000032:analysis*; D004875:Ergosterol / Q000009:adverse effects / Q000032:analysis*; D005227:Fatty Acids / Q000009:adverse effects / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006880:Hydroxy Acids / Q000009:adverse effects / Q000032:analysis; D019570:Inhalation Exposure; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D009112:Muramic Acids / Q000009:adverse effects / Q000032:analysis*; D016273:Occupational Exposure / Q000009:adverse effects; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism; D013552:Swine
D000395:Air Pollutants, Occupational; D018925:Chemokines; D004391:Dust; D004731:Endotoxins; D005227:Fatty Acids; D006880:Hydroxy Acids; D009112:Muramic Acids; D004875:Ergosterol
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