Performance of a Multiplex Serological Helicobacter pylori Assay on a Novel Microfluidic Assay Platform

A noninvasive multianalytical approach establishment for risk assessment and gastric cancer screening

Effective screening and early detection are critical to improve the prognosis of gastric cancer (GC). Our study aims to explore noninvasive multianalytical biomarkers and construct integrative models for preliminary risk assessment and GC detection. Whole genomewide methylation marker discovery was conducted with CpG tandems target amplification (CTTA) in cfDNA from large asymptomatic screening participants in a high-risk area of GC. The methylation and mutation candidates were validated simultaneously using one plasma from patients at various gastric lesion stages by multiplex profiling with Mutation Capsule Plus (MCP). Helicobacter pylori specific antibodies were detected with a recomLine assay. Integrated models were constructed and validated by the combination of multianalytical biomarkers. A total of 146 and 120 novel methylation markers were found in CpG islands and promoter regions across the genome with CTTA. The methylation markers together with the candidate mutations were validated with MCP and used to establish a 133-methylation-marker panel for risk assessment of suspicious precancerous lesions and GC cases and a 49-methylation-marker panel as well as a 144-amplicon-mutation panel for GC detection. An integrated model comprising both methylation and specific antibody panels performed better for risk assessment than a traditional model (AUC, 0.83 and 0.63, P < .001). A second model for GC detection integrating methylation and mutation panels also outperformed the traditional model (AUC, 0.82 and 0.68, P = .005). Our study established methylation, mutation and H. pylori-specific antibody panels and constructed two integrated models for risk assessment and GC screening. Our findings provide new insights for a more precise GC screening strategy in the future.

Association between Helicobacter pylori antibodies determined by multiplex serology and gastric cancer risk: A meta-analysis

BACKGROUND AND AIMS

Previous studies have reported the association between limited number of Helicobacter pylori (H. pylori) antigens and gastric cancer (GC) risk. The present study evaluated the association between serum antibodies against 15 different H. pylori proteins measured by using multiplex serology assay and GC risk.

METHODS

We searched PubMed databases, Embase, Web of Science, and Cochrane Library for relevant articles. A meta-analysis was used to pool studies and to estimate odds ratios (ORs) with 95% confidence intervals (95%CIs) of different H. pylori antigens associated with GC risk. Heterogeneity was investigated using Cochran's Q test and I-squared statistic.

RESULTS

Nine studies were identified, with a total of 3209 GC cases and 6964 controls. Five H. pylori virulence factors were significantly associated with non-cardia GC risk at p-value <0.0033 including: CagA (OR = 3.22, 95%CI: 2.10-4.94), HP0305 (OR = 1.72, 95%CI: 1.32-2.25), HyuA (OR = 1.42, 95%CI: 1.13-1.79), Omp (OR = 1.83, 95%CI: 1.30-2.58), and VacA (OR = 2.05, 95%CI: 1.67-2.52). However, none of the 15 antigens was associated with cardia GC risk. In subgroup analysis by ethnicity, we identified 7 antigens associated with the risk of non-cardia GC among East Asian while only two antigens were identified in European population. Nevertheless, CagA and GroEL showed a stronger association in Caucasian (CagA OR = 5.83, 95%CI: 3.31-10.26; GroEL OR = 3.66, 95%CI: 1.58-8.50) compared with East Asian (CagA OR = 2.20, 95% CI: 1.85-2.61; GroEL OR = 1.47, 95%CI: 1.29-1.68).

CONCLUSIONS

This study determined that H. pylori infection increases the risk of non-cardia GC with differential effects by its virulence factors and with different patterns among East Asian and European populations. These results advance the understanding of the effect of H. pylori on GC.

Evaluation of the diagnostic value of FliD, a Helicobacter pylori flagellar protein

Novel immunodominant antigens are urgently required for diagnosis and vaccine of Helicobacter pylori(HP). FliD, an important colonization factor was cloned and expressed(rFliD) to evaluate the levels of specific-IgG, IgM and IgA antibodies in the serum of patients by ELISA. Rabbit anti-rFliD polyclonal antibody (pAb) was obtained by subcutaneous injections of rFliD. The rFliD-specific IFN-γ and IL-4 of peripheral blood mononuclear cells and CD4⁺ T cells from human were analyzed by enzyme-linked immunospot and flow cytometry. We found that the levels of rFliD-specific IgG, IgM and IgA were significantly higher in HP-infected-patients compared with healthy controls. IgG, IgM and IgA had diagnostic sensitivities of 92.6, 89.8 and 83.2%; specificities of 91.1, 88.7 and 64.6%; and areas under the receiver operating curves of 0.97, 0.96 and 0.92, respectively. Furthermore, rFliD-pAb was used in the immunohistochemical analysis of gastritis and gastric cancer tissues from patients infected with HP. The levels of rFliD-specific IFN-γ and IL-4 were significantly elevated in HP-infected patients and exhibited a T helper type 1-dominant subtype. These findings indicate that rFliD exhibits high validity as a biomarker in HP diagnosis and may also be a potent antigen for vaccine design due to its high cellular and humoral immune response.

A retrospective study assessing the acceleration effect of type I Helicobacter pylori infection on the progress of atrophic gastritis

Based on the antibody typing classification, Helicobacter pylori infection can be divided into type I H. pylori infection and type II H. pylori infection. To observe the effects of different H. pylori infection types on the distribution of histopathological characteristics and the levels of three items of serum gastric function (PG I, PG II, G-17). 1175 cases from October 2018 to February 2020 were collected with ratio 1:2. All patients were performed with ¹⁴C-Urea breath test (¹⁴C-UBT), H. pylori antibody typing classification, three items of serum gastric function detection, painless gastroscopy, pathological examination, etc. According to H. pylori antibody typing classification, patients were divided into three groups: type I H. pylori infection group, type II H. pylori infection group and control group. Significant difference existed among type I H. pylori infection group, type II H. pylori infection group and control group in inflammation and activity (χ² = 165.43, 354.88, P all < 0.01). The proportion of three groups in OLGA staging had statistic difference (χ² = 67.99, P all < 0.01); Compared with type II H. pylori infection group and control group, the level of pepsinogen I, pepsinogen II, gastrin17 in type I H. pylori infection group increased, and PG I/PG II ratio (PG I/PG II ratio, PGR) decreased, which was statistically significant (χ² = 35.08, 166.24, 134.21, 141.19; P all < 0.01). Type I H. pylori infection worsened the severity of gastric mucosal inflammation and activity. H. pylori infection was prone to induce atrophy of gastric mucosa, while type I H. pylori infection played a key role in promoting the progress of atrophic gastritis and affected the level of serum gastric function. The study indicated that the eradication of H. pylori should be treated individually.

Epitope peptides of Helicobacter pylori CagA antibodies from sera by whole-peptide mapping

BACKGROUND

Helicobacter pylori CagA has been found to be immuno-dominant protein and utilized for the diagnosis of the infection with cagA-positive strains. It is important to characterize the peptide epitopes capable of detecting serum anti-CagA antibodies to understand CagA immunogenicity.

METHODS

Sera from 171 Japanese patients were subjected for the epitope mapping study. Eighty seven peptides were designed from the CagA consensus sequence and were used for ELISA protocol to test the serum samples. The reacting anti-CagA IgG amounts to specific peptides were measured and compared.

RESULTS

The study revealed a strong reactivity of two peptides (c7-NNTEPIYAQVNKKKAGQAT and c8-AGQATSPEEPIYAQVAKKV) in H. pylori-infected group. Interestingly, these two peptides contained the well-known EPIYA-A and EPIYA-B region, respectively, which are two out of three CagA phosphorylation domains. Tyrosine-phosphorylation of these peptides reduced their reactivity in most sera. Moreover, additional peptides' mapping and chimeric-peptides' experiments indicated that the amino acids (QV and KK) accommodated in right-side flanking regions of both EPIYA-motifs were essential for their strong reactivity, whereas the third EPIYA-motif containing peptide (c12-GRSASPEPIYATIDFDEA) with differing flanking amino acids was not reactive in most cases.

CONCLUSIONS

Our results suggest that the amino acid sequences constituted in the two reactive peptides are the important immunogenic regions of CagA which would be useful to develop next-generation peptide-based diagnostic assays.

Encoded particle microfluidic platform for rapid multiplexed screening and characterization of aptamers against influenza A nucleoprotein

Aptamers represent interesting bioreceptor alternatives to antibodies when developing a bioassay and are selected by the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process. After selection, an extensive characterization process is essential to verify the binding affinity and specificity of aptamer candidates, which is the most time-consuming and costly step. In this study, we assessed a new microfluidic platform, namely Evalution™, as a rapid and high throughput aptamer characterization platform. To do this, we first selected aptamers against influenza A nucleoprotein (infA NP) by performing magnetic bead-based SELEX. The selected aptamer candidates were subsequently screened using Evalution™ for their binding kinetics and specificity towards infA NP. All aptamers showed dissociation constants (K_D) in the low nanomolar range (from 13 to 41 nM), and differential binding behavior towards control proteins, such as BSA and influenza B nucleoprotein (infB NP). Among 5 selected candidates, one aptamer (NP5) exhibited a significant discrimination between infA NP and infB NP and was further used to benchmark the kinetic analysis of Evalution™ (K_D = 41 nM) with an SPR platform (K_D = 17 nM). These results suggested that NP5 has the potential to be used for developing sensitive and infA NP specific aptamer-based assay. Moreover, the presented platform proved to be an efficient aptamer characterization tool for performing typical aptamer characterization experiments like binding kinetics (due to the real-time monitoring feature) and specificity assessment in a high-throughput manner due to the multiplexing capacity.

Current understanding and management of Helicobacter pylori infection: an updated appraisal

In addition to its role in gastric conditions, Helicobacter pylori has been found to contribute to the development of several non-gastric issues in recent years. Eradication therapy is the only effective management strategy to minimize the H. pylori-related gastric cancer and extra-gastric complications. For an effective “test and treat” strategy, diagnosis and therapy are both important. Because the infection is usually asymptomatic, patient selection is a critical issue for timely diagnosis and many clinical and demographic factors should be considered. Clarithromycin and metronidazole resistance rates also need to be considered while eradication therapy is offered. In this report, we discuss the issues which must be taken into account for the correct and timely diagnosis and for the antibiotic therapy-based management of H. pylori infection.