Comparison of the biological activity of synthetic N-acylated asparagine or serine linked monosaccharide lipid A analogs

Review: D-Galactosamine lethality model: scope and limitations

D-Galactosamine (D-galN) is well established as sensitizing mice and other animals to the lethal effects of TNF, specifically, and by several orders of magnitude. Protection by anti-TNF neutralizing antibody is complete, as is (metabolically-based) protection by uridine. Sensitization occurs regardless of the origin of the released TNF, whether it is released from macrophages and/or T-cells. The same is true for the challenging agent which leads to the release of TNF, whether it is endotoxin, a superantigen, lipoprotein, bacterial DNA, or bacteria, either killed or proliferating. Most studies have utilized endotoxin as the challenging agent, and more than 70 agents have been reported to confer protection against LPS and/or TNF challenge in the model. The model has provided new insight regarding modes of protection, including from dexamethasone, which protects against challenge from LPS but not from challenge by TNF. The D-galN lethality model has also been used to test for synergistic behavior between different bacterial components, and to test for lethality when only small amounts of the challenging agent are available (lipid A chemistry).

Lipid A in cancer therapies preclinical results

Studies in animal models showed that the antitumoral effect of LPS and of their biologically active moiety, lipid A, is indirect and relies on the induction of an immune response both innate and specific, leading to cytokine production. They also affect tumor development by inhibiting tumor blood flow and induce necrosis as well as apoptosis of tumor cells. Lipids A have been tested in animals, either alone or as adjuvant in therapeutic vaccines. The efficacy of treatments depends on the type of molecule and on the protocol. In general, increased survival was obtained, accompanied in some cases by tumor regression and cure.