No abstract

The endogenous mediator nitric oxide (NO) blocked apoptosis of Jurkat cells elicited by staurosporine, anti-CD95 or chemotherapeutics, and switched death to necrosis. The switch in the mode of cell death was dependent on the ATP loss elicited by NO. This affected two distinct steps of the apoptotic cascade. First, the release of cytochrome c from mitochondria was delayed by NO. Second, processing of procaspases-3/7 to the active proteases was prevented even after cytochrome c had been released. Thus, NO interferes with execution steps of apoptosis both upstream and downstream of cytochrome c release.

Keratinocyte growth factor (KGF) promotes epithelial growth and differentiation and has potent effects on the liver. The coinjection of lipopolysaccharide (LPS) and D-galactosamine (GalN) results in hepatic failure in mice. Mechanistically, LPS-induced tumor necrosis factor (TNF) triggers hepatocyte apoptosis, which is enhanced by GalNarrested transcription. Similarly, the combination of TNF and actinomycin D (ActD) causes hepatocyte apoptosis in vitro. We studied the effect of KGF on LPS and GalNinduced hepatic failure in vivo and on TNF-and ActDinduced hepatocyte apoptosis in vitro, where it was compared with those of hepatic growth factor (HGF) and epidermal growth factor (EGF). Mice treated with human recombinant KGF (1 mg/kg subcutaneously) 24 hours before intraperitoneal coinjection of LPS and GalN sustained prolonged survival compared with control mice, although overall mortality was not changed. The counts of apoptotic hepatocytes, serum alanine and aspartate transaminases, and DNA fragments in the cytosolic fraction of liver homogenates were higher in control mice than in treated mice 6 hours after LPS and GalN coinjection, before any mortality occurred. In vitro, hepatocytes pretreated with KGF exhibited reduced TNF-and ActD-induced cell damage and DNA fragmentation, similar to hepatocytes pretreated with HGF and EGF. In conclusion, KGF prolongs survival during LPS-and GalN-induced hepatic failure by temporarily protecting hepatocytes against apoptosis. It also protects hepatocytes in vitro against TNF-and ActDinduced apoptosis. (HEPATOLOGY 1998;27:1584-1591.)

Twenty-four healthy male volunteers received either placebo or 75, 150, or 300 microg filgrastim (recombinant methionyl human granulocyte colony-stimulating factor) for 12 days to study effects on monocytes and lymphocytes. In all filgrastim-treated groups, tumor necrosis factor alpha (TNF-alpha), interleukin-12 (IL-12), and interferon gamma (IFN-gamma) release by whole blood in response to endotoxin (lipopolysaccharide) was reduced. IL-12 added in vitro to lipopolysaccharide-stimulated blood of filgrastim-treated donors restored IFN-gamma and TNF-alpha release, suggesting that the anti-inflammatory effect of granulocyte colony-stimulating factor is exercised through IL-12 suppression. Phytohemagglutinin- or anti-CD3 antibody-induced lymphocyte proliferation ex vivo was reduced by 60% from day 5 to day 15, after a 50% increase at day 2 with concomitant doubled IL-2 release. In vivo, filgrastim induced doubling of all T-cell populations by day 8. Filgrastim decreased proinflammatory cytokine production and lymphocyte proliferation ex vivo throughout prolonged treatment at all doses. This indicates that endogenous granulocyte colony-stimulating factor may counterregulate the inflammatory cytokine cascade and implies a potential indication for filgrastim in chronic inflammatory conditions.