Helicobacter pylori lipopolysaccharide:Biological activities in vitro and in vivo,pathological correlation to human chronic gastritis and peptic ulcer

AIM:To determine the biological activity of Helicobacter pylori(H pylori) lipopolysaccharide (H-LPS) and understandpathological correlation between H-LPS and human chronicgastritis and peptic ulcer.METHODS:H-LPS of a clinical Hpyloristrain and LPS ofEscherichia coli strain O55:B5 (E-LPS) were extracted byphenol-water method.Biological activities of H-LPS andE-LPS were detected by limulus lysate assay,pyrogen assay,blood pressure test and PBMC induction test in rabbits,cytotoxicity test in NIH 3T3 fibroblast cells and lethalitytest in NIH mice.By using self-prepared rabbit anti-H-LPSserum as the first antibody and commercial HRP-labeledsheep anti-rabbit sera as the second antibody,H-LPS inbiopsy specimens from 126 patients with chronic gastritis(68 cases) or gastric ulcer (58 cases) were examined byimmunohistochemistry.RESULTS:Fibroblast cytotoxicity and mouse lethality ofH-LPS were weaker than those of E-LPS.But the ability ofcoagulating limulus lysate of the two LPSs was similar(+/0.5 ng/mL).At 0.5 h after H-LPS injection,the bloodpressures of the 3 rabbits rapidly declined.At 1.0 h afterH-LPS injection,the blood pressures in 2 of the 3 rabbits fellto zero causing death of the 2 animals.For the other onerabbit in the same group,its blood pressure graduallyelevated.At 0.5 h after E-LPS injection,the blood pressuresof the three rabbits also quickly declined and thenmaintained at low level for approximately 1.0 h.At 0.5 hafter injection with H-LPS or E-LPS,PBMC numbers ofthe rabbits showed a remarkable increase.The totalpositivity rate of H-LPS from 126 biopsy specimens was60.3%(76/126).H-LPS positivity rate in the biopsy specimensfrom chronic gastritis (50/68,73.5%) was significantly higherthan that from gastric ulcer (26/58,44.8%) (x~2=10.77,P<0.01).H-LPS positivity rates in biopsy specimens fromchronic superficial gastritis (38/48,79.2%) and chronicactive gastritis (9/10,90.0%) were significantly higher thanthat of the patients with atrophic gastritis (3/10,30.0%)(x~2=7.50-9.66,P<0.01).CONCLUSION:The biological activities of H-LPS were weaker than those of E-LPS,the activities of H-LPS oflowering rabbit blood pressure and inducing rabbit PBMCwere relatively stronger.H-LPS may play a critical role ininducing inflammatory reaction in human gastritis.