Inflammatory Effects of Inhaled Endotoxin-Contaminated Metal Working Fluid Aerosols in Rats

Abstract

Exposure to aerosols generated from water-soluble metal-working fluids (MWF) is associated with numerous respiratory symptoms consistent with an acute pulmonary inflammatory event. Previous studies in mice and guinea pigs have implicated endotoxin contamination of MWF as the causative agent responsible for inducing pulmonary neutrophilia and decrements in airway conductance. However, little information is known about the relationship between endotoxin-contaminated MWF exposure and changes in airway physiology. The present study, utilizing a rat model, has demonstrated that exposure to 10 mg/m3 with endotoxin (0 to 3.2 micrograms/m3) resulted in a time- and concentration-dependent migration of neutrophils in the lung tissue's interstitial spaces as well as the lavageable airways. In contrast to other airborne toxicants, where neutrophil infiltration of the lung has been associated with hyperresponsive airways, the endotoxin-induced neutrophilia observed in the present study was not associated with airway hyperresponsiveness to challenge with the muscarinic agent methacholine or with permeability damage to the lung. Bronchoalveolar lavage (BAL)-recovered neutrophils demonstrated no adverse effects as a result of endotoxin-contaminated MWF exposure. In contrast, a population of alveolar macrophages was observed to be enlarged in size and demonstrated an increased sensitivity to oxidative metabolism when challenged with phorbol myristate acetate, consistent with being at a relatively high state of activation. These results suggest that while endotoxin contamination of MWF is capable of producing an acute inflammatory event, other predisposition factors may be required to induce alterations in pulmonary physiology.

Airway Symptoms and Biological Markers in Nasal Lavage Fluid in Subjects Exposed to Metalworking Fluids

“…However, it does illustrate that the MWF used in the production, over time, probably becomes more likely to cause airway inflammation. It has previously been suggested that endotoxin contamination of MWF is the causative agent responsible for inducing an inflammatory response in airways [12], [47]. In relation to our protein findings, it has recently been shown that recombinant SPLUNC1 reduces TNF-α release from activated macrophages [39] and may be important to prevent dehydration of the airway mucosa [48].…”

Metalworking Fluid with Mycobacteria and Endotoxin Induces Hypersensitivity Pneumonitis in Mice

“…Often the predominant organisms are gramnegative bacteria, such as Pseudomonas (6). These organisms give rise to endotoxin, which can achieve relatively high concentrations and pose a risk of inflammatory lung disease (11,12,30,41). When machining fluids are repeatedly treated with certain biocides, resistant organisms survive, whereas others are eliminated.…”

The Relationship between Workplace Environment and Metabolic Syndrome

“…The mechanism through which metalworking fluid causes respiratory disease is believed to be mainly inhalation of mist contaminated with micro-organisms and various chemical additives in the fluid that are known to be stimulants of the respiratory tract. 22 On the other hand, animal experiments show that some components of the metalworking fluid would cause acute inflammation and oxidative stress in the body. 23 In fact, the low-level persistent inflammatory response exists in those chronically exposed to meta working fluid, is recognized as an important factor in the pathogenesis of metabolic syndrome.…”