Protective efficacy of a hydroxy fatty acid against gastric Helicobacter infections.

BACKGROUND: We have previously revealed that omega-3 polyunsaturated fatty acids can prevent Helicobacter pylori infection by blocking the futalosine pathway, an alternative route for menaquinone (MK) biosynthesis. MATERIALS AND METHODS: 1, Different H. pylori strains were grown in liquid media supplemented with linoleic acid, an omega-6 fatty acid, or its 10-hydroxy derivative, 10-hydroxy-cis-12-octadecenoic acid (HYA), in the presence or absence of MK. The bacterial numbers in the media were estimated by plating; 2, C57BL/6NCrl mice received drinking water supplemented with different fatty acids starting from 1 week before infection with H. pylori or Helicobacter suis until the end of the experiment. The gastric colonization levels of H. pylori or H. suis were determined 2 weeks after infection by plating or quantitative PCR, respectively; 3, Mice were given HYA, starting 1 week before infection with H. suis and continuing until 6 months after infection, for analysis of the gastric conditions. RESULTS: 1, A low concentration (20 µmol/L) of HYA in culture broth suppressed the growth of H. pylori, and this inhibition was reduced by MK supplementation; 2, HYA treatment protected mice against H. pylori or H. suis infection; 3, HYA treatment suppressed the formation of lymphoid follicles in the gastric mucus layer after H. suis infection. CONCLUSIONS: HYA prevents gastric Helicobacter infections by blocking their futalosine pathways. Daily HYA supplementation is effective for the prevention of gastric mucosa-associated lymphoid tissue lymphoma induced by persistent infection with H. suis.

Narrow-spectrum inhibitors targeting an alternative menaquinone biosynthetic pathway of Helicobacter pylori.

We aimed to identify narrow-spectrum natural compounds that specifically inhibit an alternative menaquinone (MK; vitamin K2) biosynthetic pathway (the futalosine pathway) of Helicobacter pylori. Culture broth samples of 6183 microbes were examined using the paper disc method with different combinations of 2 of the following 3 indicator microorganisms: Bacillus halodurans C-125 and Kitasatospora setae KM-6054(T), which have only the futalosine pathway of MK biosynthesis, and Bacillus subtilis H17, which has only the canonical MK biosynthetic pathway. Most of the active compounds isolated from culture broth samples were from the families of polyunsaturated fatty acids (PUFAs). Only one compound isolated from the culture broth of Streptomyces sp. K12-1112, siamycin I (a 21-residue lasso peptide antibiotic), targeted the futalosine pathway. The inhibitory activities of representative PUFAs and siamycin I against the growth of B. halodurans or K. setae were abrogated by supplementation with MK. Thereafter, the growth of H. pylori strains SS1 and TN2GF4 in broth cultures was dose-dependently suppressed by eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or siamycin I, and these inhibitory effects were reduced by supplementation with MK. Daily administration of EPA (100 µM), DHA (100 µM), or siamycin I (2.5 µM) in drinking water reduced the H. pylori SS1 colonization in the gastric mucosa of C57BL/6 mice by 96%, 78%, and 68%, respectively. These data suggest that EPA, DHA, and siamycin I prevented H. pylori infection by inhibiting the futalosine pathway of MK biosynthesis.

Mouse Models for Assessing the Protective Efficacy of Lactobacillus gasseri SBT2055 against Helicobacter suis Infection Associated with the Development of Gastric Mucosa-Associated Lymphoid Tissue Lymphoma.

BACKGROUND: Helicobacter suis strain TKY infection has been strongly associated with the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma in a C57BL/6J mouse model. MATERIALS AND METHODS: 1. C57BL/6J mice were intragastrically administered Lactobacillus strains once daily with 10(8)-10(9) colony-forming units (CFU), starting 2 days before intragastric infection with H. suis TKY (approximately 1 × 10(4) copies of 16S rRNA genes) or H. pylori Sydney strain 1 (SS1; 3 × 10(8) CFU) and continuing for 14 days after infection. 2. C57BL/6J mice were given powdered feed mixed with lyophilized L. gasseri SBT2055 (LG2055) cells (5 × 10(8) CFU/g), starting 2 weeks before intragastric infection with H. suis TKY and continuing 12 months after infection. RESULTS: 1. Among the 5 Lactobacillus strains that we examined, only LG2055 exhibited significantly preventive efficacy against both H. suis TKY and H. pylori SS1 at day 15 after infection. 2. Dietary supplementation with LG2055 protected mice from the formation of round protrusive lesions in the gastric fundus 12 months after infection with H. suis TKY, whereas such lesions had developed in the gastric fundus of nonsupplemented mice 12 months after infection. In addition, the formation of lymphoid follicles in gastric mucus layers was suppressed by dietary LG2055 at 3 months after infection. CONCLUSIONS: LG2055 administration is effective for suppressing the progression of gastric MALT lymphoma by reducing H. suis colonization.

Comparative efficacies of different antibiotic treatments to eradicate nontypeable Haemophilus influenzae infection.

BACKGROUND: Nonencapsulated and nontypeable Haemophilus influenzae (NTHi) is a major cause of human respiratory tract infections. Some strains of NTHi can cause invasive diseases such as septicemia and meningitis, even if H. influenzae is not generally considered to be an intracellular pathogen. There have been very few reports about the therapeutic efficacy of antibiotics against respiratory tract infection caused by NTHi in mice because it is difficult for H. influenzae to infect mice. Therefore, we evaluated the efficacy of antibiotics against NTHi in both a cell culture model and a mouse model of infection. METHODS: We used six strains of NTHi isolated from adult patients with chronic otitis media, namely three beta-lactamase-negative ampicillin (AMP)-resistant (BLNAR) strains and three beta-lactamase-negative AMP-susceptible (BLNAS) strains, to evaluate the efficacy of AMP, cefcapene (CFPN), levofloxacin (LVX), clarithromycin (CLR), and azithromycin (AZM) in both a cell culture infection model and a mouse infection model. In the cell culture infection model, strains that invade A549 human alveolar epithelial cells were treated with each antibiotic (1 mug/ml). In the mouse infection model, female C57BL/6 mice were intraperitoneally injected with cyclophosphamide (200 mg/kg) three days before intranasal infection with 1 x 109 colony-forming units (CFU) of NTHi and on the day of infection. After infection, the mice were orally administered each antibiotic three times daily for three days, except for AZM, which was administered once daily for three days, at a dose of 100 mg/kg/day. RESULTS: In the cell culture infection model, it was found that two BLNAR strains were able to enter the cell monolayers by the process of macropinocytosis, and treatment with LVX yielded good bactericidal activity against both strains inside the cells. In the mouse infection model, no bacteria were detected by means of plating the lung homogenates of LVX-treated mice at day 4 after infection, while more than 105 CFU of bacteria per tissue sample were detected in nontreated mice. CONCLUSION: Our findings show the outcome and rich benefits of fluoroquinolone treatment of respiratory infections caused by either invasive or noninvasive BLNAR strains of NTHi.