Acute changes in sputum collected from exposed human subjects in mining conditions

Abstract

Neprilysin (NEP) is a key cell surface peptidase in the maintenance of airway homeostasis and the development of pulmonary disorders. However, little information is available about the effect of particulate matter (PM) on airway NEP. In this controlled human exposure study, changes in induced sputum were measured in eleven subjects at baseline, overshot (OS) mucking, and diesel exhaust (DE) exposure days. Neither OS condition nor DE exposure was found to induce significant changes in total protein, but DE induced significant increases in cell numbers of macrophages and epithelium. Moreover, significant increases in soluble NEP were observed following OS mining dust particulates (0.43 ± 0.06, p = 0.023) and DE exposure (0.30 ± 0.04, p = 0.035) when compared with the baseline control (0.40 ± 0.03), with 42% and 31% average net increase, respectively. Pearson’s correlation analyses indicated that sputum NEP activity were significantly associated with personal exposure product [Elemental carbon concentration, mg/m3 X time, min. (C X T)]. Data suggest that the changes in NEP activity may be an early, accurate endpoint for airway epithelial injury and provided a new insight into the mechanism of the airway effects in these exposure conditions.

A Pilot Study of Airborne Hazards and Other Toxic Exposures in Iraq War Veterans

“…Many of the increased symptoms associated with deployment are considered in the medical community as "acute", meaning an external source acts as an irritant creating an allergen-cascade reaction. This includes forming B-cells and Immunoglobulin-E (IgE) antibodies which react to the foreign antigen in the form of symptoms such as loss of smell, burning eyes and irritated throat, coughing, and discolored phlegm [18]. Upon leaving Iraq and removing the irritant(s) causing the reaction, those specific symptoms showed a decrease.…”