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 with structural and functional homology to human interleukin-8 (IL-8) and melanoma growth-stimulatory activity (MGSA/gro). We investigated the relationship between CINC and the production of chemotactic activity for neutrophils by rat alveolar macrophages after in vitro and in vivo treatment with endotoxin. After in vitro treatment with endotoxin, the chemotactic bioactivity produced by alveolar macrophages increased in a time- and dose-dependent manner. This increase in chemotactic activity was closely associated with increased levels of steady-state CINC mRNA. About 50% of the chemotactic activity was blocked by treatment with neutralizing concentrations of anti-CINC antibodies. We then evaluated the role of CINC in vivo in the development of neutrophilic alveolitis in rats, which results from a single intraperitoneal injection of endotoxin. In this model, peak numbers of neutrophils are recovered in lung lavage fluid 24 h after endotoxin injection. Steady-state CINC 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 nuclear factor kappa B (NF-kappa B). The CINC gene contains a binding site in the promoter region for NF-kB. Therefore, we sought to determine whether NF-kappa B binding to the CINC NK-kappa B motif was increased in nuclear extracts from rat lung lavage cells after exposure to endotoxin using gel mobility shift assays. Increased nuclear NF-kappa B binding activity was detected 2.5 h after in vivo treatment with endotoxin.(ABSTRACT TRUNCATED AT 250 WORDS)