title: Asbestos modulates thioredoxin-thioredoxin interacting protein interaction to regulate inflammasome activation.
abstract: BACKGROUND
  Asbestos exposure is related to various diseases including asbestosis and malignant mesothelioma (MM). Among the pathogenic mechanisms proposed by which asbestos can cause diseases involving epithelial and mesothelial cells, the most widely accepted one is the generation of reactive oxygen species and/or depletion of antioxidants like glutathione. It has also been demonstrated that asbestos can induce inflammation, perhaps due to activation of inflammasomes.
  
  
  METHODS
  The oxidation state of thioredoxin was analyzed by redox Western blot analysis and ROS generation was assessed spectrophotometrically as a read-out of solubilized formazan produced by the reduction of nitrotetrazolium blue (NTB) by superoxide. Quantitative real time PCR was used to assess changes in gene transcription.
  
  
  RESULTS
  Here we demonstrate that crocidolite asbestos fibers oxidize the pool of the antioxidant, Thioredoxin-1 (Trx1), which results in release of Thioredoxin Interacting Protein (TXNIP) and subsequent activation of inflammasomes in human mesothelial cells. Exposure to crocidolite asbestos resulted in the depletion of reduced Trx1 in human peritoneal mesothelial (LP9/hTERT) cells. Pretreatment with the antioxidant dehydroascorbic acid (a reactive oxygen species (ROS) scavenger) reduced the level of crocidolite asbestos-induced Trx1 oxidation as well as the depletion of reduced Trx1. Increasing Trx1 expression levels using a Trx1 over-expression vector, reduced the extent of Trx1 oxidation and generation of ROS by crocidolite asbestos, and increased cell survival. In addition, knockdown of TXNIP expression by siRNA attenuated crocidolite asbestos-induced activation of the inflammasome.
  
  
  CONCLUSIONS
  Our novel findings suggest that extensive Trx1 oxidation and TXNIP dissociation may be one of the mechanisms by which crocidolite asbestos activates the inflammasome and helps in development of MM.
authors.forename: Joyce K
authors.initials: JK
authors.lastname: Thompson
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Westbom
authors.forename: Maximilian B
authors.initials: MB
authors.lastname: MacPherson
authors.forename: Brooke T
authors.initials: BT
authors.lastname: Mossman
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Heintz
authors.forename: Page
authors.initials: P
authors.lastname: Spiess
authors.affiliation: Department of Pathology, University of Vermont, College of Medicine, Burlington, VT 05405, USA. arti.shukla@uvm.edu.
authors.forename: Arti
authors.initials: A
authors.lastname: Shukla
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D017638:Asbestos, Crocidolite / Q000633:toxicity*; D015153:Blotting, Western; D020170:Caspase 1 / Q000378:metabolism; D045744:Cell Line, Tumor; D003683:Dehydroascorbic Acid / Q000378:metabolism; D004137:Dinitrochlorobenzene / Q000633:toxicity; D004789:Enzyme Activation / Q000187:drug effects; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D055785:Gene Knockdown Techniques; D006801:Humans; D007249:Inflammation / Q000473:pathology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D054481:Thioredoxin Reductase 1 / Q000378:metabolism; D013879:Thioredoxins / Q000187:drug effects* / Q000235:genetics
chemical_list: D000975:Antioxidants; D004137:Dinitrochlorobenzene; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C491203:TXN protein, human; D017638:Asbestos, Crocidolite; D013879:Thioredoxins; D007770:L-Lactate Dehydrogenase; D054481:Thioredoxin Reductase 1; D020170:Caspase 1; D000111:Acetylcysteine; D003683:Dehydroascorbic Acid