Hypersensitivity Pneumonitis Due to Metalworking Fluid Exposures: Response

Abstract

We thank Dr Barber and colleagues for their very specific comment on the role of nontuberculous mycobacteria in metalworking fluid (MWF) hypersensitivity pneumonitis (HP) that followed our broad narrative review of HP in our recent article in CHEST.1Lacasse Y Girard M Cormier Y Recent advances in hypersensitivity pneumonitis.Chest. 2012; 142: 208-217Abstract Full Text Full Text PDF PubMed Scopus (130) Google Scholar We also read with interest their systematic review of respiratory outbreaks associated with exposure to water-based MWF, to which they refer.2Burton CM Crook B Scaife H Evans GS Barber CM Systematic review of respiratory outbreaks associated with exposure to water-based metalworking fluids.Ann Occup Hyg. 2012; 56: 374-388Crossref PubMed Scopus (58) Google Scholar We noted that eight of the 27 outbreaks included in their review involved patients with HP. Microbial contamination of MWF samples was variable. Mycobacteria were detected in MWF in 12 outbreaks; mycobacteria were also tested but not detected in three others. However, no detail was provided regarding the methods used to detect mycobacteria in MWF. Although mycobacteria are ubiquitous in aqueous environments, identifying them is particularly difficult. Bacterial culture methods lack sensitivity. Establishing a link between mycobacteria and HP is further complicated by the fact that the immunogenic properties of HP agents do not seem to be linked to their viability, because animal models of HP use dead organisms or whole cell extracts.3Israël-Assayag E Fournier M Cormier Y Blockade of T cell costimulation by CTLA4-Ig inhibits lung inflammation in murine hypersensitivity pneumonitis.J Immunol. 1999; 163: 6794-6799PubMed Google Scholar, 4Thorne PS Adamcakova-Dodd A Kelly KM O'neill ME Duchaine C Metalworking fluid with mycobacteria and endotoxin induces hypersensitivity pneumonitis in mice.Am J Respir Crit Care Med. 2006; 173: 759-768Crossref PubMed Scopus (62) Google Scholar Our group developed a DNA extraction method and real-time polymerase chain reaction assay capable of quantifying mycobacterial load in environmental samples using a dual-labeled probe to specifically detect Mycobacterium immunogenum.5Veillette M Page G Thorne PS Duchaine C Recovery and quantification of Mycobacterium immunogenum DNA from metalvorking fluids using dual-labeled probes.J ASTM Int. 2005; 2: 1-9Crossref Scopus (10) Google Scholar This method proved more sensitive than DNA extraction alone and standard culture.6Veillette M Pagé G Thorne PS Duchaine C Real-time PCR quantification of Mycobacterium immunogenum in used metalworking fluids.J Occup Environ Hyg. 2008; 5: 755-760Crossref PubMed Scopus (14) Google Scholar Our group also found that MWFs are more often contaminated by bacteria (mostly Pseudomonas pseudoalcaligenes) than by mycobacteria (M immunogenum).7Gilbert Y Veillette M Duchaine C Metalworking fluids biodiversity characterization.J Appl Microbiol. 2010; 108: 437-449Crossref PubMed Scopus (53) Google Scholar In the same work environment, M immunogenum was not found in air samples.8Gilbert Y Veillette M Meriaux A Lavoie J Cormier Y Duchaine C Metalworking fluid-related aerosols in machining plants.J Occup Environ Hyg. 2010; 7: 280-289Crossref PubMed Scopus (23) Google Scholar An explanation may be that high-level air contamination with mycobacteria in machining plants is intermittent only and depends on sporadic use of MWF-generating aerosols. We would certainly agree that HP could occur in mycobacteria-free workplaces. However, that M immunogenum is related to MWF-HP is more than an attractive hypothesis. M immunogenum in MWF has been linked to HP outbreaks in several reports.2Burton CM Crook B Scaife H Evans GS Barber CM Systematic review of respiratory outbreaks associated with exposure to water-based metalworking fluids.Ann Occup Hyg. 2012; 56: 374-388Crossref PubMed Scopus (58) Google Scholar Animal models clearly demonstrate that MWFs containing mycobacteria can induce granulomatous lung disease, peribronchiolar lymphocytosis, increased cell concentrations in lavage, and upregulation of several cytokines.4Thorne PS Adamcakova-Dodd A Kelly KM O'neill ME Duchaine C Metalworking fluid with mycobacteria and endotoxin induces hypersensitivity pneumonitis in mice.Am J Respir Crit Care Med. 2006; 173: 759-768Crossref PubMed Scopus (62) Google Scholar These findings are consistent with HP. To our knowledge, such a model does not exist with Pseudomonas species or any other bacteria isolated from MWFs. Contamination of MWFs with mycobacteria is often underestimated because of laboratory methods that lack sensitivity to detect them. We would be pleased to apply the methods we developed in our laboratory to MWF samples from the United Kingdom. Other contributions: The authors thank Caroline Duchaine, PhD. Hypersensitivity Pneumonitis Due to Metalworking Fluid ExposuresCHESTVol. 143Issue 4PreviewWe read with interest the recent article by Lacasse et al1 (CHEST July 2012), which provided a comprehensive update on hypersensitivity pneumonitis (HP). We would like to comment, however, on the section relating to HP due to metalworking fluid (MWF) exposure and, in addition, highlight the experience in the United Kingdom in this area.2 Our group has recently published a review article summarizing the microbiologic and immunologic findings from all previously published MWF outbreaks.3 We have also investigated a number of MWF-HP outbreaks in the United Kingdom. Full-Text PDF