Adiposity affects human response to inhaled organic dust

Abstract

Swine containment facilities are often highly contaminated with organic dusts that often contain varying levels of endotoxins and other microbial products. This study was performed to evaluate the effect of obesity on the inflammatory response induced by chronic or acute exposure to swine confinement buildings (SCB). Two separate studies were performed; Study I included 36 SCB long-time workers and a control group of 35 matched male hospital workers never exposed to SCB. In Study II, 14 naïve healthy young subjects (8 overweight and 6 lean) volunteered to be acutely exposed to a SCB environment for 5 hr. Markers of sub-clinical inflammation linked to obesity (C-reactive protein (CRP), interleukin 6 (IL-6)) or to active inflammation (soluble adhesion molecules, IL-8, TNF) were measured. In the first study, positive correlations were found between girth circumference and serum levels of IL-6 (r = 0.57, P = 0.0003) and CRP (r = 0.62, P < 0.0001) in the control group. These correlations were however blunted or lost in the SCB workers group who showed positive correlations between girth circumference and soluble l-selectin (r = 0.34, P = 0.04), TNFalpha (r = 0.37, P = 0.03), ICAM-1 (r = 0.61, P < 0.0001). In the second study involving acute SCB exposure of naïve volunteers, no significant differences were observed between normal weight and overweight subjects for white blood cells, nasal lavage cell counts, and IL-8 levels. However, higher levels of CRP, TNF, and IL-6 were detected in overweight volunteers compared to those who were lean. In pig farmers (Study I), environmentally induced chronic inflammation appears to blunt the sub-clinical inflammation linked to obesity, whereas in naïve volunteers of Study II, environmentally induced acute inflammation seems to have a potentiating effect on obesity-related inflammatory markers.