Serine Protease Inhibitors Modulate Smoke-Induced Chemokine Release From Human Lung Fibroblasts Running Title: Protease inhibitors and smoke extract

Smoking is associated with lung inflammation and a protease-antiprotease imbalance. We previously reported that cigarette smoke extract (CSE) stimulates human lung fibroblasts to release chemotactic cytokines. We hypothesized that serine protease inhibitors might modulate lung fibroblast release of chemotactic cytokines in response to CSE. To test this hypothesis, serine protease inhibitors (FK706, α1-antitrypsin, methoxysuccinyl-Ala-Ala-Pro-Val chloromethyl ketone; SPCK, or Nα-p-tosyl-L-lysine chloromethyl ketone; TLCK) were evaluated for their capacity to attenuate the release of neutrophil chemotactic activity (NCA) and monocyte chemotactic activity (MCA) from human fetal lung fibroblasts (HFL-1) by the blind-well chemotactic chamber. Metalloproteinases and cysteine proteinases were not examined in this study. Similarly, the release and gene expression of chemokines and nuclear factor – κB (NF-κB) activation were measured by means of enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction. Release of NCA, MCA, chemotactic chemokines including interleukin (IL)-8, granulocyte colony stimulating factor (G-CSF), monocyte chemoattractant protein (MCP)-1, and granulocyte-macrophage CSF (GM-CSF), and the expression of IL-8 and MCP-1 mRNA were attenuated by FK706. Furthermore, FK706 suppressed NF-κB activation. These data suggest that serine protease inhibitors attenuate the CSE-induced release of NCA and MCA from HFL-1 and that the inhibitory action of anti-proteases might depend on NF-κB signaling pathway.