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Muramic acid, endotoxin, 3-hydroxy fatty acids, and ergosterol content explain monocyte and epithelial cell inflammatory responses to agricultural dusts.

Poole-JA; Dooley-GP; Saito-R; Burrell-AM; Bailey-KL; Romberger-DJ; Mehaffy-J; Reynolds-SJ
J Toxicol Environ Health, A 2010 Jan; 73(10):684-700
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.
Agricultural-industry; Agricultural-processes; Agricultural-workers; Agriculture; Animal-husbandry-workers; Bacterial-dusts; Biological-effects; Cytology; Cytotoxic-effects; Dust-exposure; Dust-particles; Exposure-assessment; Exposure-levels; Exposure-methods; Farmers; Health-hazards; Inhalation-studies; Microscopic-analysis; Particulate-dust; Particulates; Pulmonary-system-disorders; Respiratory-infections; Respiratory-irritants; Work-environment; Worker-health; Work-operations; Workplace-studies
Jill A. Poole, MD, Pulmonary, Critical Care, Sleep & Allergy Section, University of Nebraska Medical Center, 985300 The Nebraska Medical Center, Omaha, NE 68198-5300, USA
Publication Date
Document Type
Journal Article
Email Address
Funding Type
Cooperative Agreement; Agriculture; Grant
Fiscal Year
Identifying No.
Cooperative-Agreement-Number-U50-OH-008085; Grant-Number-R01-OH-008539
Issue of Publication
Priority Area
Agriculture, Forestry and Fishing
Source Name
Journal of Toxicology and Environmental Health, Part A: Current Issues
Performing Organization
Colorado State University - Ft. Collins
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division