title: Inflammation in methotrexate-induced pulmonary toxicity occurs via the p38 MAPK pathway.
abstract: Methotrexate (MTX) has been widely used for the treatment of inflammatory diseases and rheumatoid arthritis (RA), as well as a variety of tumors. However, MTX-induced toxicity is a serious and unpredictable side effect of this therapy and an important clinical problem. We used microarray analysis to examine MTX-induced gene expression in a human lung epithelial cell line (BEAS-2B) and identified 10 differentially expressed genes related to the p38 mitogen-activated protein kinase (MAPK) pathway, including IL-1beta, MKK6, and MAPKAPK2. Differential gene expression was confirmed via real-time RT-PCR. To determine the functional significance of MTX-induced p38 MAPK activation, we used a p38 MAPK inhibitor (SB203580) to block the p38 MAPK cascade. We also used protein array technology to investigate the modulated expression of pro- and anti-inflammatory cytokines in BEAS-2B cells. MTX activated IL-1beta expression and induced the phosphorylation of various proteins in the p38 MAPK cascade, including TAK1, MKK3/MKK6, p38 MAPK, MAPKAPK2, and HSP27. Finally, HSP27 activation may increase IL-8 secretion, resulting in a pulmonary inflammatory response such as pneumonitis. Although IL-1beta and IL-8 expression increased, the expression of IL-4, IL-6, IL-12, TNF-alpha, MIP-1alpha, and MIP-1beta decreased in a dose-dependent manner. These results suggest that the modulation of cytokine expression may play an important role in MTX-induced pulmonary toxicity.
authors.affiliation: Cellular and Molecular Toxicology Laboratory, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, Republic of Korea.
authors.forename: Youn-Jung
authors.initials: YJ
authors.lastname: Kim
authors.forename: Mee
authors.initials: M
authors.lastname: Song
authors.forename: Jae-Chun
authors.initials: JC
authors.lastname: Ryu
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008727:Methotrexate / Q000633:toxicity*; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D011014:Pneumonia / Q000139:chemically induced* / Q000201:enzymology / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D016207:Cytokines; D048051:p38 Mitogen-Activated Protein Kinases; D008727:Methotrexate