Prevention of lipopolysaccharide-induced lethal toxicity by tyrosine kinase inhibitors

Pentoxifylline pretreatment fails to block the acute-phase response to Escherichia coli endotoxin in dwarf goats

The purpose of this study was to assess whether pentoxifylline, a drug that can inhibit the production and action of pro-inflammatory cytokines, had beneficial effects on the acute-phase response to E. coli endotoxin in the dwarf goat. First, the effects of 0.5 mg/kg per min pentoxifylline given intravenously over 15 min were examined in five goats. One week later, the clinical changes caused by i.v. injection of E. coli endotoxin (LPS: 0.1 microgram/kg) were determined. This endotoxin induced fever, tachycardia, inhibition of rumen motility, and decreases in plasma zinc and iron concentrations. Three weeks later, the effect of E. coli LPS were again determined immediately after pentoxifylline infusion in the same group of animals. It was concluded that a pharmacological dose of pentoxifylline has no protective effects on the acute-phase response reactions induced by a pyrogenic dose of E. coli LPS.

A protein kinase involved in the regulation of inflammatory cytokine biosynthesis

Production of interleukin-1 and tumour necrosis factor from stimulated human monocytes is inhibited by a new series of pyridinyl-imidazole compounds. Using radiolabelled and radio-photoaffinity-labelled chemical probes, the target of these compounds was identified as a pair of closely related mitogen-activated protein kinase homologues, termed CSBPs. Binding of the pyridinyl-imidazole compounds inhibited CSBP kinase activity and could be directly correlated with their ability to inhibit cytokine production, suggesting that the CSBPs are critical for cytokine production.

Signal-transduction therapy. A novel approach to disease management

In the past decade it has become apparent that many diseases result from aberrations in signaling pathways. These include proliferative diseases such as cancers, atherosclerosis and psoriasis and inflammatory conditions such as sepsis, rheumatoid arthritis and tissue rejection. These findings refocused the research of the medical community to seek new modalities for disease management which essentially consist of designing drugs which intercept cell signaling. In this review, the emerging success in using tyrosine kinase blockers and other signal interceptors, such as protein kinase C blockers, Ras blockers, Ca2+ signaling inhibitors and estrogen antagonists which inhibit growth of cancer cells in vitro and in vivo, will be discussed. These signal interceptors, especially tyrosine-kinase blockers, are also able to block inflammatory responses and the proliferation of vascular smooth muscle cells and psoriatic keratinocytes. The utility of signal interceptors in analyzing signal-transduction pathways is also discussed.

Inhibitors of protein kinases and phosphatases

Inhibitors of eukaryotic protein kinases and phosphatases are a chemically diverse array of natural and synthetic compounds, including medicines, potions and poisons. These substances are valuable pharmacological probes and affinity ligands for the kinases and phosphatases of signalling pathways, enhancing our knowledge of the cellular effects of the pathway in question. More broadly, this basic research is also leading to the development of drugs to control specific cellular responses, and enzyme-based assays to detect toxins in food and water.