Toll-like receptor 4 variants reduce airway response in human subjects at high endotoxin levels in a swine facility

• Published in: Journal of allergy and clinical immunology Vol. 123; no. 5; pp. 1034 - 1040.e2
• Main Authors: Senthilselvan, Ambikaipakan, Dosman, James A., Chénard, Liliane, Burch, Lauranell H., Predicala, Bernardo Z., Sorowski, Randine, Schneberger, David, Hurst, Tom, Kirychuk, Shelley, Gerdts, Volker, Cormier, Yvon, Rennie, Donna C., Schwartz, David A.
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01.05.2009; Elsevier; Elsevier Limited
• Subjects: Air Pollutants, Occupational - immunology; Airway hyperresponsiveness; Allergens - immunology; Allergy and Immunology; Animals; Asthma; Biological and medical sciences; Biomedical research; Blood; blood counts; Cytokines; Cytokines - blood; endotoxin; Endotoxins - immunology; Female; Fundamental and applied biological sciences. Psychology; Fundamental immunology; gene-environment interaction; Housing, Animal; Humans; Hypersensitivity - immunology; Hypersensitivity - metabolism; Immunopathology; Indoor air quality; Inhalation Exposure; Leukocyte Count; Lung - immunology; Lung - metabolism; lung function; Male; Medical sciences; Polymorphism; Polymorphism, Genetic; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Studies; Sus scrofa; swine confinement facility; Toll-Like Receptor 4 - genetics; Toll-Like Receptor 4 - immunology; Toll-like receptor 4 variants; Young Adult; gene-environment interaction; blood counts; PC 20; Airway hyperresponsiveness; FVC; lung function; FEV 1; cytokines; swine confinement facility; Toll-like receptor 4 variants; TLR4; endotoxin; FEF 25-75; Forced expiratory volume in the first second; Forced vital capacity; Toll-like receptor 4; Methacholine dose required for a 20% decrease in FEV 1; Forced expiratory flow between 25% and 75% of forced vital capacity; Toll like receptor 4; Genetic variability; Hyperreactivity; Respiratory system; Endotoxin; Respiratory tract; Lung function; Immunology; Swine; Ungulata; Human; Immunopathology; Cytokine; Genotype; Variant; Toxin; Vertebrata; Mammalia; Genotype environment interaction; Artiodactyla; Blood cell count
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2009.02.019

Toll-like receptor 4 (TLR4) variants have been shown to reduce the respiratory responses to inhaled LPS in controlled experiments among healthy volunteers. We sought to investigate whether naive subjects with TLR4 variants showed reduced respiratory response to a complex aerosol including endotoxin as a major constituent. Twenty-nine nonsmoking, nonatopic healthy subjects with TLR4 299/399 polymorphisms and 29 age- and sex-matched, wild-type TLR4 control subjects were exposed for 5 hours each in a noncontaminated environment (baseline day) and in a swine confinement facility (exposure day). There were 16 men and 13 women in each of the 2 age- and sex-matched groups. TLR4 polymorphic subjects who were exposed to high endotoxin levels (≥1550 EU/m 3) had less reduction in the percentage across-shift change in FEV 1 from baseline than did wild-type subjects exposed to similar endotoxin levels. Among subjects exposed to higher endotoxin levels, the mean differences in the percentage across-shift changes between baseline and exposure days were significantly less in TLR4 polymorphic subjects compared with those seen in wild-type subjects in FEV 1 (−8.48% ± 1.52% [mean ± SE] vs −11.46% ± 1.79%, P = .001), forced expiratory flow between 25% and 75% of forced vital capacity (−18.30% ± 1.99% vs −24.14% ± 3.28%, P = .009), and FEV 1/forced vital capacity ratio (−5.40% ± 0.56% vs −8.53% ± 1.51%, P = .04). These patterns were not observed in IL-6 levels from serum and nasal lavage fluid, IL-8 levels from nasal lavage fluid, white blood cell counts, or blood differential counts. The association between TLR4 variants and reduced airway responsiveness to inhaled particulate was observed at high endotoxin concentrations, creating the possibility of certain threshold phenomena for the apparent protective effect of TLR4 variants.