SEITE, Sophie, BRETON, Aude, NOVIKOV, Alexey, et al. all bacteria lipopolysaccharides are not endotoxins: Structure to activity relationships: vitreoscilla filiformis example. Journal of the American Academy of Dermatology, 2017, vol. 76, no 6, p. AB36.
Introduction: Endotoxins are the main components of the outer membrane of Gram-negative bacteria. Each bacterium possesses a specific lipopolysaccharides (LPS) structure. Chemically, endotoxins are LPS, but not all LPS are endotoxins. They are composed of two moieties: the polysaccharidic (PS) and the lipid A. The PS moiety is made of the so-called O-antigens linked to core oligosaccharides. They carry the antigenic properties of the molecule and can be used in vaccines as well as in bacterial detection tests. As an example, we studied Vitreoscilla filiformis, a Gram-negative bacterium isolated from spa waters and chosen for its beneficial effects on atopic dermatitis lesions.
Methods: First, the detailed structure of the V filiformis lipid A moiety was characterized. Secondly, a comparison of the structure to activity relationships of V filiformis LPS to others LPS, differentiated by the chain-length of their fatty acids, their linkage position on the glucosamines (GlcN), and their impact on the IL-6 and TNF-α inflammatory responses, caspase 3/7 activation and radical oxygen species (ROS) induction, and structurally different ones was performed.
Results: Structural differences depend on the bacterial genus, species and the natural heterogeneity of LPS and were associated with differences in biological activities.
Conclusions: This study point out the importance to fully characterize the lipid A structures of each bacteria, because LPS could be different in terms of fatty acids (FA) chain-length, FA number, and/or by their linkage position on the glucosamines. These details greatly impact the LPS biological activities. This study also confirms that V filiformis LPS are able to induce immunostimulation of the monocyte system: moderate cytokine release, ROS induction, mitogenicity and caspase activation without cellular death.