The aim of this study was to investigate the regulatory role of the
c-JUN N-terminal kinase (JNK) pathway on
interleukin (IL)-8 and
tumor necrosis factor (TNF)-α expression in alveolar macrophages (AMs) of injured lung.
Lung injury was induced in the New Zealand white rabbit by applying continuous
mechanical ventilation with or without inhibitor of JNK (
SP600125), p38 (
SB203580), or ERK (
PD98059). Non-ventilated rabbits (controls) were compared with the different ventilation-days groups, and untreated rabbits ventilated for 3 days (controls) were compared with the different inhibitor groups. We found that
mechanical ventilation caused significant decreases in partial pressures of
carbon dioxide (pCO2) and
oxygen (pO2) of untreated rabbits (all times, P<0.05), but the inhibitor-treated groups showed no change in either blood-gas
indicator (all times, P>0.05).
Mechanical ventilation caused time-dependent increases in
mRNA and
protein levels of TNF-α and
IL-8 in AMs and in serum of untreated rabbits, with the peak levels occurring at day 3 of ventilation. The SP600125-treated group showed significantly decreased TNF-α expression, but no significant change in
IL-8 expression. Neither the SB203580- nor PD98059-treated groups showed any significant change in TNF-α or
IL-8 expression. MAPKs' inhibitors could reduce
mechanical ventilation-induced
inflammation, and
SP600125 produced the most robust decrease in
inflammation.
Mechanical ventilation-induced
lung injury stimulates
IL-8 and TNF-α expression in rabbit AMs in a time-dependent manner. The JNK pathway plays an important role in
mechanical ventilation-stimulated TNF-α expression in AMs, but the injury-stimulated
IL-8 expression may be regulated by other signaling pathways.