Biochemistry and cell biology of bacterial endotoxins

Abstract

and multi-organ failure. The resulting septic shock syndrome has a mortality rate of 20-50% and causes approximately 100,000 deaths annually in the USA [5]. On the other hand, low doses of LPS are thought to be beneficial for the host, e.g. by causing immunostimulation and enhanced resistance to infections and malignancy [6]. The harmful as well as the beneficial host responses to LPS are mediated by endogenous mediators, cytokines, which are released by various cells, e.g. monocytes/macrophages, vascular cells, polymorphonuclear cells and T cells [7][8][9][10][11][12][13], the most important cytokine-producing being the cells of the monocyte/macrophage lineage.The obvious biomedical importance of LPS during infection, trauma and shock and its immunostimulatory and anti-tumor activity have attracted the attention of the scientific community and resulted in great efforts for the elucidation of -the structure of LPS and the mechanisms of its biological action. This contribution summarizes our kno$ledge about the chemical composition and structure of LPS and the mechanisms of LPS action. Structure of bacterial endotoxinsThe general structure of LPS is shown in Fig. 1. LPS consist of a lipid (the lipid A) which anchors the molecule in the outer membrane and which is covalently substituted by a saccharide portion. This

The lipopolysaccharides of the phytopathogen Xanthomonas campestris pv. campestris induce an oxidative burst reaction in cell cultures of Nicotiana tabacum

“…The small amount of data concerning the activities of LPS in plants or in plant cell cultures is in contrast to numerous reports about enterobacterial LPS and their interaction with components of the innate immune system (Schletter et al 1995;Holst et al 1996). Further studies will show to what extent the role of LPS in pathogen recognition is similar in animals and plants.…”

“…The outstanding role of endotoxins (LPS) in the induction of defence responses in cells of the immune system (Holst et al 1996) led us to the question of whether the LPS of the phytopathogen Xanthomonas campestris is Fig. 4A, B Induction of a refractory state in tobacco cell cultures following a pre-incubation with YE or LPS Xcc .…”

“…The presence of LPS could therefore be used by plants as a signal for pathogen attack to elicit defence-related reactions. This hypothesis is supported by the fact that LPS are unique to Gramnegative bacteria and represent a major stimulator of defence reactions in animal cells (Holst et al 1996). At present, not very much is known about LPS as elicitors of plant defence reactions.…”

Lipopolysaccharide-Induced Upregulation of Tumor Necrosis Factor-α (TNF-α) and TNF Receptors in Rat Sciatic Nerve

“…After peripheral nerve injury, Schwann cells have been reported to produce TNF-α (Wagner and Myers 1996). LPS has been reported to cause hyperalgesia (Watkins et al 1994(Watkins et al , 1995Reeve et al 2000), is known to enhance not only TNF-α synthesis and release (Holst et al 1996) but also the expression of TNFR2 and, to a lesser extent, of TNFR1 (Nadeau and Rivest 1999). Li et al (2004) showed that LPS induced expression of TNF-α in rat DRG exclusively in non-neuronal cells, but in sciatic nerve, its expression pattern is unknown.…”

Structural characterization of the lipid A from the LPS of the haloalkaliphilic bacterium Halomonas pantelleriensis

“…Instead, H. magadiensis displayed acyloxacyl derivatives for both 2′ and 3′ positions of GlcNII, whereas H. pantelleriensis displayed only acyloxacyl for 2′ position of the same residue. The biological activity of lipid A strongly depends on its primary structure, especially the fatty acid composition and distribution (Holst et al 1996;Seydel et al 2000). As the lipid A of H. magadiensis displayed a strong antagonist activity (Ialenti et al 2006), it will be very interesting to observe the biological activity of the lipid A from H. pantelleriensis strain to check if there are any structure-activity relationships.…”