CYTOKINE-INDUCED NEUTROPHIL CHEMOATTRACTANT MEDIATES NEUTROPHILIC ALVEOLITIS IN RATS - ASSOCIATION WITH NUCLEAR FACTOR KAPPA-B-ACTIVATION

Cytokine-induced neutrophil chemoattractant (CINC) is a rat cytokine w ith structural and functional homology to human interleukin-8 (IL-8) a nd melanoma growth-stimulatory activity (MGSA/gro). We investigated th e relationship between CINC and the production of chemotactic activity for neutrophils by rat alveolar macrophages after in vitro and in viv o treatment with endotoxin. After in vitro treatment with endotoxin, t he chemotactic bioactivity produced by alveolar macrophages increased in a time- and dose-dependent manner. This increase in chemotactic act ivity was closely associated with increased levels of steady-state CIN C mRNA. About 50% of the chemotactic activity was blocked by treatment with neutralizing concentrations of anti-CINC antibodies. We then eva luated the role of CINC in vivo in the development of neutrophilic alv eolitis in rats, which results from a single intraperitoneal injection of endotoxin. In this model, peak numbers of neutrophils are recovere d in lung lavage fluid 24 h after endotoxin injection. Steady-state CI NC mRNA levels in the lung peaked 2 h after endotoxin injection. Many cytokines whose transcription is induced during sepsis, including IL-8 and MGSA/gro, are thought to be transcriptionally regulated by nuclea r factor kappa B (NF-kappa B). The CINC gene contains a binding site i n the promoter region for NF-KB. Therefore, we sought to determine whe ther NF-kappa B binding to the CINC NK-kappa B motif was increased in nuclear extracts from rat lung lavage cells after exposure to endotoxi n using gel mobility shift assays. Increased nuclear NF-kappa B bindin g activity was detected 2.5 h after in vivo treatment with endotoxin. RelA (but not c-Rel) protein appears to be involved in CINC NA-kappa B binding. These studies suggest that CINC is involved in the developme nt of endotoxin-induced neutrophilic alveolitis in the rat model. In a ddition, elevated CINC mRNA levels are accompanied by increased NF-kap pa B binding activity in lung cells, suggesting possible CINC transcri ptional regulation via NF-kappa B.