Differences in antibody levels to H. pylori virulence factors VacA and CagA among African Americans and whites in the Southeast USA

Prevalence of the cagA Virulence Factor Varies by Race Among Helicobacter pylori -Infected Patients Undergoing Upper Endoscopy

INTRODUCTION

We designed a race-conscious study to assess the presence of Helicobacter pylori v irulence factor cagA in a retrospective cohort of patients with active H. pylori infection.

METHODS

We compared cagA status by race in gastric tissue samples from 473 patients diagnosed with active H. pylori infection from 2015 to 2019.

RESULTS

H. pylori + Black patients were 2 times more likely to be cagA + than H. pylori + White patients (82% vs 36%, P < .0001).

DISCUSSION

Presence of cagA is common among endoscopy patients with active H. pylori infection; appropriate testing and treatment of H. pylori can both reduce gastric cancer risk and address health disparities.

Dual burden of infectious and chronic disease in low-resource U.S. communities: examining relationships between infection, adiposity, and inflammation

BACKGROUND

Rising global obesity rates are linked with inflammation and associated morbidities. These negative outcomes are generally more common in low-resource communities within high-income countries; however, it is unclear how frequent infectious disease exposures in these settings may influence the relationship between adiposity and inflammation.

AIM

We test associations between adiposity measures and distinct forms of inflammation among adults (n = 80) living in low-resource U.S. communities experiencing high levels of obesity and pathogen exposure.

SUBJECTS AND METHODS

Adiposity measures included BMI and percent body fat. Inflammation measures included systemic inflammation (C-reactive protein [CRP]) and localised intestinal inflammation (faecal calprotectin [FC]). The relationship between a condition characterised by elevated inflammation (Helicobacter pylori infection) and adiposity was also considered.

RESULTS

Adiposity was not significantly related to FC concentration. However, both adiposity measures were positively related with odds of CRP elevation and H. pylori infection was associated with significantly lower adiposity measures (all p < 0.05).

CONCLUSION

For this disadvantaged U.S. sample, the association between adiposity and inflammation varies by the systemic/localised nature of inflammation and the likely underlying cause of inflammation. Defining these associations will improve understanding of how rising obesity rates shape long-term health inequities, with implications for more effective intervention design.

Wood cookstove use is associated with gastric cancer in Central America and mediated by host genetics

Biomass cookstove food preparation is linked to aero-digestive cancers, mediated by ingested and inhaled carcinogens (e.g., heterocyclic amines, and polycyclic aromatic hydrocarbons). We investigated the association between gastric adenocarcinoma, wood cookstove use, H. pylori CagA infection and risk modification by variants in genes that metabolize and affect the internal dose of carcinogens. We conducted a population-based, case-control study (814 incident cases, 1049 controls) in rural Honduras, a high-incidence region with a homogeneous diet and endemic H. pylori infection, primarily with the high-risk CagA genotype. We investigated factors including wood cookstove use, H. pylori CagA serostatus, and 15 variants from 7 metabolizing genes, and the interactions between wood stove use and the genetic variants. Male sex (OR 2.0, 1.6-2.6), age (OR 1.04, 1.03-1.05), wood cookstove use (OR 2.3, 1.6-3.3), and CagA serostatus (OR 3.5, 2.4-5.1) and two SNPs in CYP1B1 (rs1800440 and rs1056836) were independently associated with gastric cancer in multivariate analysis. In the final multivariate model, a highly significant interaction (OR 3.1, 1.2-7.8) was noted between wood cookstove use and the rs1800440 metabolizing genotype, highlighting an important gene-environment interaction. Lifetime wood cookstove use associates with gastric cancer risk in the high-incidence regions of Central America, and the association is dependent on the rs1800440 genotype in CYP1B1. H. pylori CagA infection, wood cookstove use and the rs1800440 genotype, all of which are highly prevalent, informs who is at greatest risk from biomass cookstove use.

Rural Embodiment and Community Health: an Anthropological Case Study on Biocultural Determinants of Tropical Disease Infection and Immune System Development in the USA

Purpose of Review

Biocultural methods are critically important for identifying environmental and socioeconomic factors linked with tropical disease risk and outcomes. For example, embodiment theory refers to the process by which lived experiences impact individual biology. Increased exposure to pathogens, chronic psychosocial stress, and unequal resource access are all outcomes linked with discrimination and poverty. Through lived experiences, race and socioeconomic inequality can literally become embodied-get under the skin and affect physiology-impacting immune responses and contributing to lifelong health disparities. Yet, few studies have investigated tropical disease patterns and associated immune function using embodiment theory to understand lasting physiological impacts associated with living in a high-pathogen environment.

Recent Findings

Here, we use preliminary data drawn from the Rural Embodiment and Community Health (REACH) study to assess whether pathogen exposure and immune stimulation within a sample of children from the Mississippi Delta are associated with household income. We also test whether immune marker levels-assessed with enzyme-linked immunosorbent assays using dried blood spot samples-vary between the REACH sample and a similarly aged nationally representative NHANES sample. Immune marker levels did not differ significantly between REACH participants living below vs. above the federal poverty line, yet immunoglobulin E levels-a marker of macroparasite infection-were higher among REACH study participants compared to the NHANES sample.

Summary

These results may suggest community-level pathogenic exposures (i.e., parasitic infections) are embodied by REACH participants with implications for long-term immune function, potentially resulting in immune aspects that differ from nationally representative samples.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40475-023-00282-z.

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.

Prevalence of Virulence Genes and Antigen Pattern in Helicobacter pylori-Infected Patients and The Level of Some Inflammatory Cytokines Compared with Non-infected Individuals

Background: The worldwide prevalence of Helicobacter pylori is about 50%. This bacterium needs a number of virulence factors for pathogenesis. Objectives: This study aimed to determine the prevalence of virulence genes (ureB, cytotoxin-associated gene A [cagA], and vacuolating cytotoxin [vacA]), as well as the antigenic profile in H. pylori strains. Methods: Eighty-five patients with abdominal pain, including 46 H. pylori-positive and 39 H. pylori-negative cases, were enrolled in this study. The serum levels of interleukin (IL)-17F, tumor necrosis factor α (TNF-α), and interferon γ (IFN-γ) cytokines were measured by multiplex kits and flow cytometry. After molecular identification by the ureC gene, vacA, cagA, and ureB genes were detected by polymerase chain reaction (PCR). Finally, after antigenic extraction, the whole-cell protein was exhibited by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE). Results: The prevalence of vacA, ureB, and cagA genes were 91.3%, 67.39%, and 50%, respectively. The frequency of genes and cell surface antigens were not significantly different based on the gastritis severity (P > 0.05). IL-17F significantly (P = 0.046) increased in the presence of 19.5 kDa (outer membrane protein [OMP]). Moreover, the OMP antigen significantly enhanced immunoglobulin A (IgA; P = 0.013). In the presence of the 66-kDa (ureB) antigen, the serum level of IFN-γ increased (p = 0.041). Finally, the CagA protein led to increased IgG antibody levels (p = 0.027). Conclusions: Early detection of H. pylori infection can play a crucial role in managing it. Our results suggest that IL-17F, TNF-α, and IFN-γ cytokines could be diagnostic markers. However, further studies are required to fully investigate this suggestion.

Racial Differences in Helicobacter pylori Prevalence in the US: A Systematic Review

BACKGROUND AND AIMS:

Helicobacter pylori remains an important risk factor for noncardia gastric cancer and a spectrum of disease from H. pylori infection to gastric cancer. As a step toward improved clinical strategies for gastric cancer prevention, we assessed racial differences in prevalence of H. pylori from studies across the United States. This systematic review provides a comprehensive evaluation of the literature regarding racial differences in H. pylori in the United States.

METHODS:

MEDLINE, Embase, and Web of Science database searches were performed through May 26, 2021. Ultimately, 25 studies that reported H. pylori infection prevalence by race were included.

RESULTS:

All studies included in the review documented higher H. pylori prevalence in Blacks and Hispanics than in whites. The ratio of H. pylori prevalence for Blacks compared to non-Hispanic whites ranged from 1.3 to 5.4, and the ratio for Hispanics compared to non-Hispanic whites ranged from 1.8 to 4.4. Of the 5 studies that examined H. pylori CagA prevalence by race, 4 found higher prevalence among Blacks and Hispanics compared to whites, with CagA prevalence ranging from 19% to 77% in whites, 62% to 90% in Blacks, and 64% to 74% in Hispanics.

CONCLUSION:

In this review, across 25 studies, varying in underlying population, time period, and geographic location, Blacks and Hispanics appeared to have a higher prevalence of H. pylori infection than whites. This increased prevalence of H. pylori among populations also at a higher risk of gastric cancer is relevant in the clinical setting for decision-making related to H. pylori testing and gastric cancer prevention.

Ornithine decarboxylase (ODC1) gene variant (rs2302615) is associated with gastric cancer independently of Helicobacter pylori CagA serostatus

The primary cause of gastric cancer is chronic infection with Helicobacter pylori (H. pylori), particularly the high-risk genotype cagA, and risk modification by human genetic variants. We studied 94 variants in 54 genes for association with gastric cancer, including rs2302615 in ornithine decarboxylase (ODC1), which may affect response to chemoprevention with the ODC inhibitor, eflornithine (difluoromethylornithine; DFMO). Our population-based, case-control study included 1366 individuals (664 gastric cancer cases and 702 controls) from Western Honduras, a high incidence region of Latin America. CagA seropositivity was strongly associated with cancer (OR = 3.6; 95% CI: 2.6, 5.1). The ODC1 variant rs2302615 was associated with gastric cancer (OR = 1.36; p = 0.018) in a model adjusted for age, sex, and CagA serostatus. Two additional single nucleotide polymorphisms (SNPs) in CASP1 (rs530537) and TLR4 (rs1927914) genes were also associated with gastric cancer in univariate models as well as models adjusted for age, sex, and CagA serostatus. The ODC1 SNP association with gastric cancer was stronger in individuals who carried the TT genotype at the associating TLR4 polymorphism, rs1927914 (OR = 1.77; p = 1.85 × 10-3). In conclusion, the ODC1 variant, rs2302615, is associated with gastric cancer and supports chemoprevention trials with DFMO, particularly in individuals homozygous for the T allele at rs1927914.

Association of Combined Sero-Positivity to Helicobacter pylori and Streptococcus gallolyticus with Risk of Colorectal Cancer

Previously, we found that risk of colorectal cancer (CRC) is increased in individuals with serum antibody response to both Helicobacter pylori (HP) Vacuolating Cytotoxin (VacA) toxin or Streptococcus gallolyticus (SGG) pilus protein Gallo2178. In the present analysis, we tested the hypothesis that combined seropositivity to both antigens is a better indicator of CRC risk than seropositivity to single antigens. We used multiplex serologic assays to analyze pre-diagnostic serum for antibody responses from 4063 incident CRC cases and 4063 matched controls from 10 US cohorts. To examine whether combined SGG Gallo2178 and HP VacA sero-status was associated with CRC risk, we used conditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Compared to dual sero-negative individuals, there was no increased risk for individuals sero-positive to SGG Gallo2178 only (OR: 0.93; 95% CI: 0.66–1.31) or to HP VacA only (OR: 1.08; 95% CI: 0.98–1.19). However, dual sero-positive individuals had a >50% increased odds of developing CRC (OR: 1.54; 95% CI: 1.16–2.04), suggesting an interaction between antibody responses to these two pathogens and CRC risk (p_interaction = 0.06). In conclusion, this study suggests that dual sero-positivity to HP VacA and SGG Gallo2178 is an indicator of increased risk of CRC.