title: Effects of the mTOR inhibitor rapamycin on monocyte-secreted chemokines.
abstract: BACKGROUND
  Mammalian target of rapamycin (mTOR) inhibitors, such as sirolimus and its derivative, everolimus, are potent immunosuppressive and antiproliferative drugs. Inflammatory diseases are characterized by immunological dysfunction, and monocyte recruitment underlies the mechanism of cell damage. Chemokines attract inflammatory cells to sites of inflammation. Interleukin-8 (IL-8/CXCL8); the monocyte chemoattractant protein-1 (MCP-1/CCL2); the regulated on activation, normal T cell expressed, presumably secreted protein (RANTES/CCL5); the macrophage inflammatory protein (MIP)-1α (CCL3); and MIP-1β (CCL4) are involved in the pathogenesis of inflammation. However, whether mTOR inhibitors moderate the production of chemokines in monocytes remains unclear.
  
  
  METHODS
  A human monocyte cell line, THP-1, and primary monocytes obtained from human volunteers, were stimulated using lipopolysaccharide (LPS), and then treated with sirolimus. The expression of the MCP-1, RANTES, IL-8, MIP-1α, MIP-1β, and TNF-α proteins was measured using enzyme-linked immunosorbent assays, and intracellular signalling was examined using western blotting.
  
  
  RESULTS
  Sirolimus significantly suppressed the LPS-induced expression of MCP-1, IL-8, RANTES, MIP-1α, and MIP-1β in the THP-1 cells and human primary monocytes. The mitogen-activated protein kinase (MAPK) inhibitors that were examined suppressed the LPS-induced expression of MCP-1, IL-8, RANTES, MIP-1α, and MIP-1β. In addition, sirolimus suppressed the LPS-induced phosphorylation of p38 and p65 in the THP-1 and human primary monocytes.
  
  
  CONCLUSIONS
  Sirolimus downregulates the expression of chemokines in monocytes, including MCP-1, RANTES, IL-8, MIP-1α, and MIP-1β, by inhibiting the NF-κB-p65 and MAPK-p38 signalling pathways.
authors.forename: Hugo You-Hsien
authors.initials: HY
authors.lastname: Lin
authors.forename: Kai-Ting
authors.initials: KT
authors.lastname: Chang
authors.forename: Chi-Chih
authors.initials: CC
authors.lastname: Hung
authors.forename: Chang-Hung
authors.initials: CH
authors.lastname: Kuo
authors.forename: Shang-Jyh
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Hung-Chun
authors.initials: HC
authors.lastname: Chen
authors.forename: Chih-Hsing
authors.initials: CH
authors.lastname: Hung
authors.forename: Sheng-Fung
authors.initials: SF
authors.lastname: Lin
mesh_terms: D000873:Anthracenes / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018925:Chemokines / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000873:Anthracenes; D018925:Chemokines; D005419:Flavonoids; D008070:Lipopolysaccharides; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; C432165:pyrazolanthrone; D058570:TOR Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D020123:Sirolimus