The activities of various types of antiulcer agents against Helicobacter pylori (formerly called Campylobacter pylon) strains were determined by an agar dilution method. Among the compounds tested, two benzimidazole proton pump inhibitors, lansoprazole (AG-1749) and omeprazole, were found to have significant activities against this organism. The activity of lansoprazole was comparable to that of bismuth citrate, with MICs ranging from 3.13 to 12.5 ,ug/ml, and fourfold more potent than that of omeprazole. A major metabolite and two acid-converted rearrangement products of lansoprazole also exhibited good activities comparable or superior to that of the parent compound. Exposure to lansoprazole of H. pylori growing in a liquid medium led to an extensive loss of viability without a reduction in culture turbidity and produced an aberrant bacterial morphology characterized by the irregular constriction of cells and the collapse of cell surface structures. The antibacterial activity of lansoprazole and its related compounds was selective against H. pylori; common aerobic and anaerobic bacteria and Campylobacterjejuni were not inhibited by 100 ,ug/ml.

Lipoteichoic acid (LTA) derived from Staphylococcus aureus is reported to be a ligand of Toll-like receptor 2 (TLR2). In this study, we demonstrated that lipoproteins obtained from S. aureus are potent activators of TLR2. A fraction obtained by Triton X-114 phase partitioning activated cells through TLR2. The fraction contained proteins and LTA. The activity was detected in compounds in a mass range of 12-40 kDa. Proteinase K digested the active compounds into lower molecular weight active materials <10 kDa. In contrast, hydrofluoric acid treatment, which decomposes LTA, did not alter the molecular mass of the active compounds. Further, most of the activity was abrogated by lipoprotein lipase digestion. These results suggested that lipoproteins are predominant TLR2 ligands in S. aureus cell wall components.

Serum from Mycobacterium bovis BCG-infected mice that had been challenged with lipopolysaccharide (LPS) exhibited a marked ability to induce gamma interferon (IFN-y) in cultures of spleen cells of normal mice in the presence of interleukin-2 (IL-2). The inducing activity became detectable in the circulatory system about 90 min after LPS challenge, disappeared at around 5 h, and was observable upon 640x dilution of the serum. Addition of monoclonal anti-IL-2 receptor antibody to the culture inhibited the induction by the serum. The activity induced high levels of IFN-y even in nylon wool-nonadherent cells, while concanavalin A failed to do so. Serum from uninfected mice challenged with LPS contained no such activity. The molecular weight of the active substance, estimated by gel filtration, was about 70,000. There were pronounced differences among mouse strains in the activities of the sera prepared, which paralleled the amounts of IFN-y produced in vivo. However, the levels of IFN-y produced in whole spleen cells and in nylon wool-nonadherent cells from mice of various strains were the same when stimulated with competent serum. These results indicate the existence of an unidentified factor that induces IFN-y in cooperation with IL-2 in macrophage-depleted splenocytes. They also suggest that IFN-,y production in vivo is not genetically controlled at the lymphocyte level but, rather, at the level of synthesis of the unknown factor.

The gastric proton pump inhibitor lansoprazole, its active analog AG-2000, and omeprazole dose dependently inhibited urease activity extracted with distilled water from Helicobacterpylori cells; the 50%1 inhibitory concentrations were between 3.6 and 9.5 ,M, which were more potent than those of urease inhibitors, such as acetohydroxamic acid, hydroxyurea, and thiourea. These compounds also inhibited urease activity in intact cells of H. pylori and Helicobacter mustelae but did not inhibit ureases from other bacteria, such as Proteus vulgaris, Proteus mirabilis, and Providencia rettgeri. The mechanism of urease inhibition was considered to be blockage of the SH groups of H. pylori urease, since SH residues in the enzyme decreased after preincubation with lansoprazole and glutathione or dithiothreitol completely abolished the inhibitory action. The SH-blocking reagents A -ethylmaleinide and idoacetamide were also examined for their inhibition of the urease activity; their 5W0 inhibitory tontentrations were 100-to 1,000-fold higher than those of lansoprazole. These results suggest that lansoprazole and omeprazole can potently and selectively inhibit H. pylori urease and that inhibition may be related to earlier findings indicating that these compounds have selective activity against HP growth.

The eradication rate of V-AC treatment in the CAM-susceptible H. pylori-infected patients was <90%, as was that by PPI-AC, thus V-AC is not ideal regimen in CAM-susceptible H. pylori. However, the 82.9% eradication rate of V-AC in the CAM-resistant infections may indicate the potential of V-AC with modified dose, dosing interval, and treatment duration. (UMIN000016337).