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Industrial hog farming is associated with altered circulating immunological markers
Journal article   Peer reviewed

Industrial hog farming is associated with altered circulating immunological markers

Jonathan N Hofmann, Meredith S Shiels, Melissa C Friesen, Troy J Kemp, Anil K Chaturvedi, Charles F Lynch, Christine G Parks, Ligia A Pinto, Allan Hildesheim, Michael C R Alavanja, …
Occupational and environmental medicine (London, England), Vol.75(3), pp.212-217
03/2018
DOI: 10.1136/oemed-2017-104519
PMCID: PMC5841451
PMID: 29055885
url
https://www.ncbi.nlm.nih.gov/pmc/articles/5841451View
Open Access

Abstract

The previously observed inverse association between hog farming and risk of lung cancer in the Agricultural Health Study (AHS) has been attributed to endotoxin exposure, the levels of which are particularly high in industrial hog confinement facilities. We conducted an investigation to explore the potential biological mechanisms underlying this association, as well as other immunological changes associated with hog farming. Serum immune marker levels were measured using a multiplexed bead-based assay in 61 active hog farmers and 61 controls matched on age, phlebotomy date and raising cattle. Both groups comprised non-smoking male AHS participants from Iowa. We compared natural log-transformed marker levels between hog farmers and controls using multivariate linear regression models. Circulating levels of macrophage-derived chemokine (CCL22), a chemokine previously implicated in lung carcinogenesis, were reduced among hog farmers (17% decrease; 95% CI -28% to -4%), in particular for those with the largest operations (>6000 hogs: 26% decrease; 95% CI -39% to -10%; p =0.002). We also found that hog farmers had elevated levels of other immune markers, including macrophage inflammatory protein-3 alpha (MIP-3A/CCL20; 111% increase, 95% CI 19% to 273%), basic fibroblast growth factor (FGF-2; 93% increase, 95% CI 10% to 240%) and soluble interleukin-4 receptor (12% increase, 95% CI 1% to 25%), with particularly strong associations for MIP-3A/CCL20 and FGF-2 in winter. These results provide insights into potential immunomodulatory mechanisms through which endotoxin or other exposures associated with hog farming may influence lung cancer risk, and warrant further investigation with more detailed bioaerosol exposure assessment.
Animal Husbandry Humans Middle Aged Agricultural Workers' Diseases - epidemiology Chemokine CCL22 - blood Male Biomarkers - blood Fibroblast Growth Factor 2 - blood Case-Control Studies Immunity - drug effects Chemokine CCL20 - blood Lung Neoplasms - immunology Animals Lung Neoplasms - epidemiology Lung Neoplasms - etiology Swine Iowa - epidemiology Aged Agricultural Workers' Diseases - etiology Agricultural Workers' Diseases - immunology

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