Jb. Cochran et al., The effect of a tyrosine kinase inhibitor on endotoxin mortality and splenocyte mediator production in the neonatal rat, SHOCK, 11(1), 1999, pp. 35-38
Tyrosine kinases mediate cellular signal transduction to endotoxin. A class
of tyrosine kinase inhibitors, the tyrphostins, have been shown to protect
mice from endotoxin-induced lethality. Neonatal rats and mice have been sh
own to be uniquely susceptible to lethal endotoxic shock. In our study, the
effect of a lipophilic tyrphostin, AG 556, on endotoxin-induced neonatal a
nd adult mortality and in vitro neonatal splenic cell thromboxane (TxB(2)),
tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO) production
were examined. Neonatal rats (<24 h old) were administered tyrphostin (100
mu g subcutaneous) 2 h before an approximate LD,, dose of Salmonella enteri
tidis endotoxin (.024 mg/kg/intracardiac). There was a significant decrease
in mortality in the animals pretreated with 100 mu g of tyrphostin (29% mo
rtality in the treated group, n = 41 versus 53% in the vehicle control grou
p, n = 40; p < .05). Also in adult rats tyrphostin (5 mg/kg intraperitoneal
) 2 h before endotoxin (10 mg/kg intravenous) significantly improved surviv
al (50% drug treated versus 84% in control, n = 12/group; p < .05). Adheren
t neonatal splenic cell mediator production of TxB(2), TNF-alpha, and NO (m
easured by nitrite) in tyrphostin pretreated splenic cells were compared wi
th endotoxin-stimulated splenic cells in vitro. The studies (n = 4) demonst
rate an increase (p < .05) in the production of TxB(2), TNF-alpha, and NO i
n the endotoxin- (10 mu g/mL) stimulated adherent splenic cells compared wi
th basal. Tyrphostin pretreatment (10, 20, 50 mu M) produced a dose-depende
nt decrease (p < .05) in endotoxin-stimulated TxB(2) and TNF-alpha producti
on. NO production was not significantly reduced. in conclusion, tryphostin
appears to have a protective effect on mortality in both adult and neonatal
rat endotoxic shock. Tyrphostin decreased specific mediator production in
stimulated neonatal cells. Thus, inhibition of signal transduction pathways
of endotoxin activation by tyrosine kinase inhibition may provide an effec
tive approach to treat endotoxic shock in the neonate.