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Activity in the Limulus amebocyte lysate assay and induction of tumor necrosis factor- by diverse Helicobacter pylori lipopolysaccharide preparations

Institute of Medical Microbiology, University of Bari, Bari, Italy, Department of Microbiology, University College, Galway, Ireland

D. Fumarola

Institute of Medical Microbiology, University of Bari, Bari, Italy, Department of Microbiology, University College, Galway, Ireland

G. Giuliani

Institute of Medical Microbiology, University of Bari, Bari, Italy, Department of Microbiology, University College, Galway, Ireland

E. Jirillo

Institute of Medical Microbiology, University of Bari, Bari, Italy, Department of Microbiology, University College, Galway, Ireland

A.P. Moran

Institute of Medical Microbiology, University of Bari, Bari, Italy, Department of Microbiology, University College, Galway, Ireland

Different chemically characterized H. pylori LPS preparations, such as smooth (S)- and rough (R)-form LPS, a completely dephosphorylated R-LPS, and three lipid A chemotypes, from the S- and R- form LPS (S- and R-lipid A) as well as a dephosphorylated derivative of S-lipid A, respectively, were evaluated for expression of potency in a quantitative chromogenic Limulus amebocyte (CLAL) lysate assay and for release of tumor necrosis factor- (TNF-) from activated human mononuclear cells. As far as the CLAL activity is concerned, no statistically significant differences could be observed between S- and R-LPS. Dephosphorylation of both R-LPS and S-lipid A caused a significant decrease of CLAL activity. In general terms, all the lipid A chemotypes were significantly less effective than the native LPS molecule and, in particular, R-lipid A expressed the lowest Limulus activity of all preparations. With regard to TNF- release, R-LPS was the most potent inducer of this cytokine, even though its dephosphorylation reduced activity. In conclusion, the results show that phosphate groups influence both CLAL activity and, to a lesser extent, TNF- release, and that the core oligosaccharide synergically cooperates with lipid A for the production of this cytokine, being, however, not essential for the expression of CLAL activity. Furthermore, preliminary structural data show that H. pylori D-glucosamine disaccharide backbone, besides being underphosphorylated at position 4', is also characterized by a reduced number of acyloxyacyl residues in comparison with enterobacterial lipid A. These findings, besides providing useful information on the structure-bioactivity relationships within H. pylori LPS, further support the evidence that this non-invasive, slow bacterium possesses the ability to modulate the local cellular immune response via LPS and related inflammatory cytokines.

Journal of Endotoxin Research, Vol. 2, No. 6, 455-462 (1995)
DOI: 10.1177/096805199600200609


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