Treatment of Helicobacter pylori infection 2016

Antimicrobial Peptide Hydrogel with pH-Responsive and Controllable Drug Release Properties for the Efficient Treatment of Helicobacter pylori Infection

Helicobacter pylori is the primary cause of gastric adenocarcinoma, which afflicts more than half of the world's population and seriously affects human health. However, achieving efficient treatment of H. pylori infection by effective drug delivery and bioavailability after oral administration remains a challenge due to the harsh microenvironment, short drug retention time, and physiological barriers in the stomach. Moreover, H. pylori has shown resistance to many clinical antibiotics. Antimicrobial peptides (AMPs) exhibit substantial therapeutic efficacy against H. pylori, while they are not likely to induce drug resistance, suggesting their potential utility for the treatment of diseases related to H. pylori. In this paper, we report the design and synthesis of an AMP (GE33) hydrogel with pH-responsive and controlled peptide release properties, in which the minimal inhibitory concentration of the AMP against H. pylori is as low as 1 μg/mL. GE33 self-assembles into a stable peptide hydrogel under neutral pH conditions but decomposes into monomers or oligomers under acidic conditions. Upon oral administration of the hydrogel, the acidic gastric environment would facilitate rapid release of active AMP molecules from the hydrogel and immediate targeting of H. pylori in the stomach wall. Additionally, the remaining peptide is protected in the hydrogel, extending its retention time in the stomach, so that persistent drug release is achieved. The controlled and sustained release manner of the active molecule GE33, which enhances drug bioavailability, along with its excellent bactericidal efficacy opens a great potential for treating H. pylori infection.

High dose PPI-amoxicillin dual therapy for the treatment of Helicobacter pylori infection: a systematic review with meta-analysis

BACKGROUND

Helicobacter pylori resistance to amoxicillin remains rare in many regions. Proton pump inhibitor-amoxicillin-containing high dose dual therapy (HDDT) has been proposed to treat H. pylori infection. We aimed to assess the effectiveness and safety of PPI-amoxicillin HDDT for treatment of H. pylori infection in comparison with other regimens.

METHODS

Databases, including PubMed, Embase, and the Cochrane Register of Controlled Trials, were searched to find relevant publications. Randomized controlled trials comparing HDDT with control regimens for H. pylori eradication in adult patients were included. The primary outcome was eradication rate by intention-to-treat analysis. Adverse events were analyzed as second outcome.

RESULTS

A total of 15 trials with 3818 patients qualified for inclusion. The eradication rate of HDDT was neither significantly inferior nor superior to the recommended regimens such as triple therapy, bismuth quadruple therapy, and non-bismuth quadruple therapy [relative risk (RR): 1.00, 95% confidence interval (CI): 0.96-1.05, p = 0.870]. This finding was robust through subgroup analyses and sensitivity analyses. Trial sequential analysis showed that HDDT was equivalent to control regimens, and further similar trials were unlikely to alter the conclusions of this analysis. The frequency of adverse events was significantly lower in HDDT group (RR: 0.48, 95% CI: 0.37-0.64, p < 0.001).

CONCLUSION

HDDT was equivalent to recommended first-line or rescue regimens with fewer adverse effects. The evidence from this meta-analysis supports the use of HDDT as first-line or rescue treatment for H. pylori infection.

TRIAL REGISTRATION

PROSPERO CRD42019133002.

Intraluminal therapy for Helicobacter pylori infection

BACKGROUND AND AIM

Several strategies have been proposed to increase the eradication rate of Helicobacter pylori. However, the widespread increasing resistance rates to current multiple-dose oral antibiotic therapies call for alternative therapeutic approaches. We aim to develop a novel intraluminal therapy for H. pylori infection (ILTHPI).

METHODS

From April 2017 to December 2017, 100 H. pylori-infected treatment-naïve patients with upper abdominal pain or discomfort underwent endoscopic examinations and concomitant ILTHPI, which comprised the control of intragastric pH, the irrigation of gastric mucosal surface with a mucolytic agent, and the application of single-dose medicaments containing antibiotic powders. The safety profiles while conducting ILTHPI and adverse events after ILTHPI were evaluated. The success of eradication was assessed based on the result of the ¹³ C-urea breath test 6 weeks after ILTHPI. In addition, a patient with successful ILTHPI was reconfirmed by a negative H. pylori stool antigen test four to 6 months after ILTHPI to exclude short-term recurrence.

RESULTS

All the 100 enrolled patients completed the ILTHPI with good safety profiles and mild adverse events (6%). Five patients dropped out, and 51 of 95 patients (53.7%) achieved successful eradication immediately after endoscopic examinations. All 51 patients revealed negative stool H. pylori antigen tests four to 6 months after successful ILTHPI. No short-term recurrence was observed.

CONCLUSIONS

We have developed a novel therapeutic approach. With the ILTHPI, H. pylori can be eradicated immediately by administrating a single-dose regimen while conducting an endoscopic examination.

CLINICAL TRIALS NUMBER

NCT03124420.

Clinical relevance of point mutations in the 23S rRNA gene in Helicobacter pylori eradication: A prospective, observational study

Clarithromycin-based triple therapy is prescribed worldwide for Helicobacter pylori eradication. However, increases in the clarithromycin resistance of H pylori are thought to be responsible for eradication failure. Here, we studied whether point mutations in domain V of the 23S rRNA gene can affect H pylori eradication failure in a prospective, open-label, observational study. Of the 755 enrolled patients, 299 patients (39.6%) had positive Campylobacter-like organism (CLO) tests. DNA sequencing analysis of H pylori 23S rRNA in 295 patients revealed that 2143G was the most frequent point mutation (24.7% of patients), followed by the 2182T mutation (11.5%). The overall eradication failure rate was 20.9% (42/201) in clarithromycin-based triple therapy. Patients with the 2143G had an approximately 60% eradication failure rate, which suggested that 2143G was a high-risk genotype for eradication failure. Patients with the 2182C genotype without 2143G had an 8.7% failure rate, and patients without 2143G or 2182C had only a 4.3% failure rate. The presence of 2143G, which was associated with previous eradication history and female sex, was an independent risk factor for eradication failure. In conclusion, the 2143G point mutation in the 23S rRNA of H pylori was an independent risk factor for eradication failure in clarithromycin-based triple therapy. Personalized tailored therapy based on the genotypes of 23S rRNA can increase eradication success rates in H pylori infections.

Macrolide use in the previous years is associated with failure to eradicate Helicobacter pylori with clarithromycin-containing regimens

BACKGROUND

There is some evidence that prior use of macrolide antibiotics is a useful predictor of the likelihood of standard triple therapy failure in Helicobacter pylori eradication. In this study, we have evaluated whether previous intake of macrolides correlates with failure to eradicate H. pylori using two different first-line clarithromycin-containing regimens.

MATERIALS AND METHODS

Retrospective study of 212 patients with H. pylori infection treated with one of two first-line clarithromycin-containing regimens: 108 patients treated with triple therapy for 10 days and 104 patients treated with concomitant therapy for 10 days. The intake of macrolides (clarithromycin, azithromycin, and other macrolides) prior to the eradication therapy was obtained from the electronic medical record, which contains information regarding all the medication prescribed to the patients since the year 2004.

RESULTS

One hundred of 212 patients (47.2%) had received at least one treatment with macrolides during the years prior to the eradication therapy. H. pylori eradication rates were significantly lower in patients with previous use compared to patients without previous use of macrolides, both with triple therapy (60.8% vs 92.9%; P < .0001) and with concomitant therapy (85.7% vs 98.2%; P = .024).

CONCLUSIONS

Previous use of macrolides correlates with a low H. pylori eradication rate with triple and concomitant clarithromycin-containing regimens. In addition, our study shows that in patients without previous use of macrolides, triple therapy achieves per-protocol eradication rates over 90%.

Enrichment of Helicobacter pylori mutant strains after eradication therapy analyzed by gastric wash-based quantitative pyrosequencing

The eradication of Helicobacter pylori reduces the risk of gastric cancer. A clear understanding of the factors underlying mixed infection with multiple clarithromycin-susceptible and clarithromycin-resistant H. pylori strains is necessary to design more effective therapies against H. pylori. We aimed to assess how the abundance and prevalence of H. pylori strains vary after clarithromycin-based eradication therapy. Using gastric wash samples, which represent the entire stomach, we sequentially analyzed the abundance and prevalence of H. pylori DNA by 23S ribosomal RNA pyrosequencing before and 1, 2, and 3 years after eradication therapy. Low levels of H. pylori DNA were still detectable at the first-year follow-up in all samples with negative post-treatment urea breath test results. The abundance of H. pylori DNA decreased significantly until the 2-year follow-up, but it switched to an increase at the 3-year follow-up. Importantly, the ratio of the prevalence of mutant strains to the prevalence of wild-type strains had already increased at the first-year follow-up and continued to increase, suggesting the selection and growth of clarithromycin-resistant strains during the follow-up periods. Being sensitive and representative, our assay will be useful in effectively addressing gastric cancer development by enhancing the long-term success of intervention strategies and consecutive surveillance for H. pylori eradication.

Helicobacter pylori gene silencing in vivo demonstrates urease is essential for chronic infection

Helicobacter pylori infection causes chronic active gastritis that after many years of infection can develop into peptic ulceration or gastric adenocarcinoma. The bacterium is highly adapted to surviving in the gastric environment and a key adaptation is the virulence factor urease. Although widely postulated, the requirement of urease expression for persistent infection has not been elucidated experimentally as conventional urease knockout mutants are incapable of colonization. To overcome this constraint, conditional H. pylori urease mutants were constructed by adapting the tetracycline inducible expression system that enabled changing the urease phenotype of the bacteria during established infection. Through tight regulation we demonstrate that urease expression is not only required for establishing initial colonization but also for maintaining chronic infection. Furthermore, successful isolation of tet-escape mutants from a late infection time point revealed the strong selective pressure on this gastric pathogen to continuously express urease in order to maintain chronic infection. In addition to mutations in the conditional gene expression system, escape mutants were found to harbor changes in other genes including the alternative RNA polymerase sigma factor, fliA, highlighting the genetic plasticity of H. pylori to adapt to a changing niche. The tet-system described here opens up opportunities to studying genes involved in the chronic stage of H. pylori infection to gain insight into bacterial mechanisms promoting immune escape and life-long infection. Furthermore, this genetic tool also allows for a new avenue of inquiry into understanding the importance of various virulence determinants in a changing biological environment when the bacterium is put under duress.

Helicobacter pylori is a bacterial pathogen that chronically infects half the global population and is a major contributor to the development of peptic ulcers and stomach cancer. H. pylori has evolved to survive in the stomach and one important adaptation is the enzyme urease. The bacteria cannot establish an infection in the host without this enzyme, and although widely postulated, the requirement of urease for chronic infection of the host has not been tested experimentally as conventional urease mutants are incapable of colonization. To overcome this constraint, a genetic system was introduced that allowed for the making of H. pylori strains in which urease expression could be turned off after the bacteria have colonised the stomach. We show for the first time that this enzyme is not only important for initial colonization but that it is also very important for maintaining chronic infection. We also show that if urease is turned off, the bacterium can mutate several different genes in order to restore urease expression. The genetic approach described here opens up opportunities to studying genes involved in the chronic stage of H. pylori infection to gain insight into how the bacterium is able to avoid clearance by the immune system and how it is able to adapt to changing biological environments.

The Helicobacter pylori J99 jhp0106 Gene, under the Control of the CsrA/RpoN Regulatory System, Modulates Flagella Formation and Motility

CsrA has been shown to positively control the expression of flagella-related genes, including flaA and flaB, through regulating expression of an alternative sigma factor RpoN in Helicobacter pylori J99. Here, we aimed to characterize the CsrA regulatory system by comparative transcriptomic analysis carried out with RNA-seq on strain J99 and a csrA mutant. Fifty-three genes in the csrA mutant were found to be differentially expressed compared with the wild-type. Among CsrA-regulated genes, jhp0106, with unclear function, was found located downstream of flaB in the J99 genome. We hypothesized that flaB-jhp0106 is in an operon under the control of RpoN binding to the flaB promoter. The RT-qPCR results showed the expression of jhp0106 was decreased 76 and 92% in the csrA and rpoN mutants, respectively, compared to the wild-type. Moreover, mutations of the RpoN binding site in the flaB promoter region resulted in decreased expression of flaB and jhp0106 and deficient motility. Three-dimensional structure modeling results suggested that Jhp0106 was a glycosyltransferase. The role of jhp0106 in H. pylori was further investigated by constructing the jhp0106 mutant and revertant strains. A soft-agar motility assay and transmission electron microscope were used to determine the motility and flagellar structure of examined strains, and the results showed the loss of motility and flagellar structure in jhp0106 mutant J99. In conclusion, we found jhp0106, under the control of the CsrA/RpoN regulatory system, plays a critical role in H. pylori flagella formation.