Clarithromycin Versus Metronidazole in First-Line Helicobacter Pylori Triple Eradication Therapy Based on Resistance to Antimicrobial Agents: Meta-Analysis

Background: International treatment guidelines for Helicobacter pylori infection recommend a proton pump inhibitor (PPI)/amoxicillin/clarithromycin (CAM) regimen (PAC) or PPI/amoxicillin/metronidazole (MNZ) regimen (PAM) as first-line therapy based on culture and sensitivity testing. As incidence rates of antimicrobial agent-resistant strains are changing year by year, it is important to reevaluate the efficacy of eradication regimens. We performed a meta-analysis to evaluate the efficacy and safety of PAC and PAM based on different locations categorized by the reported incidence of CAM- and MNZ-resistant strains. Methods: Randomized control trials (RCTs) comparing eradication rates between PAC and PAM first-line treatment up to December 2018 were included. We divided RCTs into four groups based on resistance to CAM (< 15% or ≥ 15%) and MNZ (< 15% or ≥ 15%). Results: A total of 27 studies (4825 patients) were included. Overall eradication rates between PAC and PAM were similar (74.8% and 72.5%, relative risk (RR): 1.13, 95% confidence interval (CI): 0.91–1.39, P = 0.27) in the intention-to-treat analysis. In areas with low MNZ- and high CAM-resistance rates, PAM had a significantly higher eradication rate than PAC (92.5% vs. 70.8%, RR: 0.29, 95% CI: 0.13–0.68). In areas with high MNZ- and low CAM-resistance rates, the eradication rate with PAC was only 72.9%. Conclusions: Overall eradication rates with PAC and PAM were equivalent worldwide. In low MNZ-resistance areas, PAM may be recommended as first-line therapy. However, the efficacy of PAC may be insufficient, irrespective of susceptibility to CAM

Emulsified Phosphatidylserine, Simple and Effective Peptide Carrier for Induction of Potent Epitope-Specific T Cell Responses

<div><p>Background</p><p>To induce potent epitope-specific T cell immunity by a peptide-based vaccine, epitope peptides must be delivered efficiently to antigen-presenting cells (APCs) <i>in vivo</i>. Therefore, selecting an appropriate peptide carrier is crucial for the development of an effective peptide vaccine. In this study, we explored new peptide carriers which show enhancement in cytotoxic T lymphocyte (CTL) induction capability.</p> <p>Methodology/Principal Findings</p><p>Data from an epitope-specific <i>in vivo</i> CTL assay revealed that phosphatidylserine (PS) has a potent adjuvant effect among candidate materials tested. Further analyses showed that PS-conjugated antigens were preferentially and efficiently captured by professional APCs, in particular, by CD11c⁺CD11b⁺MHCII⁺ conventional dendritic cells (cDCs) compared to multilamellar liposome-conjugates or unconjugated antigens. In addition, PS demonstrated the stimulatory capacity of peptide-specific helper T cells <i>in vivo</i>.</p> <p>Conclusions/Significance</p><p>This work indicates that PS is the easily preparable efficient carrier with a simple structure that delivers antigen to professional APCs effectively and induce both helper and cytotoxic T cell responses <i>in vivo</i>. Therefore, PS is a promising novel adjuvant for T cell-inducing peptide vaccines.</p> </div

Proliferation assay of epitope-specific helper T cells.

<p>CD4⁺ T cells from mice immunized with PS-conjugated or unconjugated peptide were co-cultured with activated BMDCs for 2 days in complete RPMI medium containing the indicated concentration of NP_311–325 peptide. Proliferation of NP_311–325-specific CD4⁺ Th cells was measured by BrdU uptake. The experiment was repeated three times with similar results. *p<0.05, **p<0.005</p

Confocal laser scanning microscopy analysis of splenocytes co-cultured with PS-conjugated antigens.

<p>(A, B) CD11b⁺ or CD11c⁺ cells were cultured with sfGFP, sfGFP-PS, DQ-OVA or DQ-OVA-PS plus Hoechst33342 for 60 min at 37°C. After the incubation, cells were washed with PBS, and then analyzed under a LSM780 confocal laser scanning microscope system. Blue: cell nucleus, Green: sfGFP or DQ-OVA, Red: CD11b or CD11c.</p

Mice immunized with PS-conjugated peptide induced epitope-specific CTL effectively <i>in vivo</i>.

<p>(A) B6 mice (3 to 4 mice per group) were immunized s.c. with each carrier-conjugated NP_366–374 (A/HK483) peptide or peptide without carrier in the presence of poly(I:C). Seven days after the immunization, bright CFSE-labeled target cells pulsed with peptide used for the immunization and dim CFSE-labeled target cells pulsed with an irrelevant peptide were injected i.v. as an <i>in vivo</i> cytotoxicity assay. Viability of the target cells in the spleen was examined 20 h after injection. Reduction ratios of epitope-specific target cells were calculated using the formula described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060068#s2" target="_blank">Materials and Methods</a>. (B) A24Tg mice (3 mice per group) were inoculated with PS- or liposome-conjugated NP_257–264 (A/HK483) peptide. The <i>in vivo</i> cytotoxicity assay was performed as described for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060068#pone-0060068-g001" target="_blank">Figure 1A</a>. n.s. indicates not significant. *p<0.01, **p<0.0001.</p

PS-conjugated Ags were captured by professional APCs effectively.

<p>(A) Splenocytes were classified into five subpopulations (I to V) based on the expression pattern of CD11b and CD11c. I:CD11b⁻CD11c⁻ cells, II:CD11b^intCD11c⁻ cells, III:CD11b^highCD11c⁻ cells, IV:CD11b⁺CD11c⁺ cells, V:CD11b⁻CD11c⁺ cells. (B, C) Each isolated population was co-cultured with sfGFP, sfGFP-PS or sfGFP-liposome for 60 min, and then the amount of uptake was analyzed by flow cytometry. (D, E) Each population of isolated cells was co-cultured with DQ-OVA or DQ-OVA-PS for 60 min, and then the efficiency of antigen degradation processing was analyzed by flow cytometry.</p

Frequency of epitope-specific CD8⁺ T cells in immunized mice.

<p>(A) PS-conjugated NP_366–374 (A/PR8) peptide, PS-conjugated OVA_257–264 peptide or unconjugated peptide was inoculated into B6 mice (3 to 4 mice per group). The <i>in vivo</i> cytotoxicity assay was performed as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060068#pone-0060068-g001" target="_blank">Figure 1</a>. *p<0.01, **p<0.0001. (B) Splenocytes from naïve mice and mice immunized with PS-conjugated or unconjugated peptide in the presence of poly(I:C) were stained with tetramer and anti-mouse CD8 Ab. The percentage indicates the tetramer-positive cells in total CD8⁺ cells. The experiment was repeated three times with similar results.</p