Helicobacter pylori duodenal colonization in children

Single-cell profiling of environmental enteropathy reveals signatures of epithelial remodeling and immune activation

Environmental enteropathy (EE) is a subclinical condition of the small intestine that is highly prevalent in low- and middle-income countries. It is thought to be a key contributing factor to childhood malnutrition, growth stunting, and diminished oral vaccine responses. Although EE has been shown to be the by-product of a recurrent enteric infection, its full pathophysiology remains unclear. Here, we mapped the cellular and molecular correlates of EE by performing high-throughput, single-cell RNA-sequencing on 33 small intestinal biopsies from 11 adults with EE in Lusaka, Zambia (eight HIV-negative and three HIV-positive), six adults without EE in Boston, United States, and two adults in Durban, South Africa, which we complemented with published data from three additional individuals from the same clinical site. We analyzed previously defined bulk-transcriptomic signatures of reduced villus height and decreased microbial translocation in EE and showed that these signatures may be driven by an increased abundance of surface mucosal cells-a gastric-like subset previously implicated in epithelial repair in the gastrointestinal tract. In addition, we determined cell subsets whose fractional abundances associate with EE severity, small intestinal region, and HIV infection. Furthermore, by comparing duodenal EE samples with those from three control cohorts, we identified dysregulated WNT and MAPK signaling in the EE epithelium and increased proinflammatory cytokine gene expression in a T cell subset highly expressing a transcriptional signature of tissue-resident memory cells in the EE cohort. Together, our work elucidates epithelial and immune correlates of EE and nominates cellular and molecular targets for intervention.

Interleukin 8 (-251 T>A) polymorphism in children and teenagers infected with Helicobacter pylori

Background

Helicobacter pylori (H. pylori) is a gram-negative bacterium that colonizes the human stomach and causes a variety of gastric diseases. This study evaluated the correlations between the -251 (T>A) (rs4073) polymorphism of interleukin-8 (IL-8), the etiology of gastric disease, and H. pylori infection in pediatric and adolescent patients.

Methods

DNA samples were obtained from 285 gastric biopsies from pediatric patients. H. pylori was detected by PCR, whereas PCR-RFLP was used to characterize the -251 (T>A) polymorphism of IL-8.

Results

The histological analysis revealed the presence of gastritis in 158 patients (55.44%). H. pylori was found in 71 samples (24.9%). The -251 (T>A) polymorphism revealed that 58 (29.47%) samples were TT, 143 (50.18%) samples were TA, and 84 (20.35%) samples were AA.

Conclusions

Our findings suggest that IL8-251 A allele may be an important risk factor for the development of gastric disease when associated with H. pylori infection.

Helicobacter pylori enter and survive within multivesicular vacuoles of epithelial cells

Although intracellular Helicobacter pylori have been described in biopsy specimens and in cultured epithelial cells, the fate of these bacteria is unknown. Using differential interference contrast (DIC) video and immunofluorescence microscopy, we document that a proportion of cell-associated H. pylori enter large cytoplasmic vacuoles, where they remain viable and motile and can survive lethal concentrations of extracellular gentamicin. Entry into vacuoles occurs in multiple epithelial cell lines including AGS gastric adenocarcinoma, Caco-2 colon adenocarcinoma and MDCK kidney cell line, and depends on the actin cytoskeleton. Time-lapse microscopy over several hours was used to follow the movement of live H. pylori within vacuoles of a single cell. Pulsed, extracellular gentamicin treatments show that the half-life of intravacuolar bacteria is on the order of 24 h. Viable H. pylori repopulate the extracellular environment in parallel with the disappearance of intravacuolar bacteria, suggesting release from the intravacuolar niche. Using electron microscopy and live fluorescent staining with endosomal dyes, we observe that H. pylori-containing vacuoles are similar in morphology to late endosomal multivesicular bodies. VacA is not required for these events, as isogenic vacA- mutants still enter and survive within the intravacuolar niche. The exploitation of an intravacuolar niche is a new aspect of the biological life cycle of H. pylori that could explain the difficulties in eradicating this infection.

Antral nodularity and positive CagA serology are distinct and relevant markers of severe gastric inflammation in children with Helicobacter pylori infection

BACKGROUND

The aim of this study was to assess whether the endoscopic finding of antral nodularity and serum IgG antibodies to CagA are associated with higher grades of gastric inflammation.

MATERIALS AND METHODS

The comprehensive data of two previously published trials were reanalysed. One hundred and fifty-three children (median age 9.5 years) who underwent gastroscopy were included. Biopsy specimens from the antrum and corpus were taken to assess Helicobacter pylori status, gastritis score and lymphoid follicles. During endoscopy, antral nodularity was noted. Serum samples were assayed for IgG antibodies to CagA.

RESULTS

The presence of antral nodularity (nod+) and positive CagA serology (CagA+) were each found in 32 of the 77 (41.5%) children who had evidence of H. pylori infection. Cross tabulation showed that 20 children (26%) were nod+/CagA+, 12 (15.5%) nod+/CagA-, 12 (15.5%) nod-/CagA+ and 33 (43%) nod-/CagA-. Gastritis score was significantly lower in nod-/CagA- children than in nod+/CagA- (p =.004), nod-/CagA+ (p =.002) and nod+/CagA+ (p <.001), both in the antrum and corpus. Completely normal gastric histology was only found in the nod-/CagA- subgroup of H. pylori-infected children (eight of 33, 24%). Regression analysis showed that antral nodularity and positive CagA serology were related to severe gastric inflammation independently of each other and age. Separate analysis showed that inflammation (p <.001), activity (p <.001) and H. pylori density (p =.002) scores were significantly lower in nod-/CagA- children compared with nod+/CagA+ children. The number of lymphoid follicles in the gastric mucosa was related to antral nodularity (p =.003) and positive CagA serology (p =.043), independently of each other.

CONCLUSIONS

Antral nodularity and positive CagA serology are distinct and relevant markers of severe gastric inflammation in children with H. pylori infection. The lack of both findings in the same child reflects low-grade or no gastritis.

Helicobacter pylori infection and recurrent abdominal pain in Turkish children

BACKGROUND

Helicobacter pylori infection is primarily acquired in childhood. However, the association between H. pylori infection and recurrent abdominal pain (RAP) remains unclear.

MATERIALS AND METHODS

One hundred and forty-one children with and 21 without RAP underwent upper gastrointestinal endoscopy. At least five antral gastric biopsies were obtained from each patient and the presence of H. pylori infection was accepted when at least two out of four tests (histology, direct antral smear, culture, and rapid urease test) were positive. Patients with H. pylori infection underwent triple therapy with omeprazole, clarithromycin, and metronidazole.

RESULTS

Eighty-five out of 141 (60.3%) patients with RAP were H. pylori positive whereas 5 out of 21 (20.8%) patients without RAP were (p =.0037). Symptoms were disappeared in 87% of children whose H. pylori infection was eradicated compared with 41% of those in whom the infection was not eradicated (p =.0035).

CONCLUSIONS

It was concluded that children with RAP and H. pylori infection appear to benefit from eradication therapy in Turkey.

Distinction of gastric Helicobacter spp. in humans and domestic pets by scanning electron microscopy

BACKGROUND

A number of different Helicobacter spp. can colonize the stomach of humans and domestic pets. Difficulties encountered with primary isolation of these spiral microorganisms and their unusual inertia with respect to biochemical reactions still represent considerable obstacles to their characterization with classic tools. In addition, the high degree of similarity in the 16S rRNA sequence hampers differentiation of Helicobacter spp. using routine molecular biological assays.

MATERIALS AND METHODS

Samples from experimentally monoinfected mice, of naturally infected hosts, and of cultured strains were examined by scanning electron microscopy (SEM). In parallel, all samples were analyzed by molecular techniques to ascertain the Helicobacter spp. involved.

RESULTS

Using the mouse samples as a reference, microorganisms found in naturally infected hosts were identified by SEM as belonging to H. pylori, H. felis, or a group consisting of H. bizzozeronii and H. heilmannii. A further spiral microorganism with unique morphology was found in a dog that was positive for H. salomonis, but the organism could not be recovered from experimentally infected mice. In culture, most Helicobacter strains lost their ultrastructural characteristics.

CONCLUSIONS

When gastric Helicobacter spp. were collected from their natural habitat and examined by SEM, relevant differences could be detected between H. felis, H. bizzozeronii and H. heilmannii, and H. salomonis, respectively. SEM, therefore, seems to be a useful auxillary tool for the distinction of various gastric Helicobacter spp. as based on their ultrastructure.

Ethnic differences in intestinal disaccharidase values in children in Finland

BACKGROUND

Intestinal disaccharidase activities tend to be low in villous atrophy, but there are only a few reports of enzyme activities in children with normal villous architecture.

METHODS

In the current study the data were reviewed on disaccharidase activities in duodenal biopsy specimens of normal villous structure in 223 children undergoing upper gastrointestinal endoscopy in 1997 and 1998. The ancestry was Finnish in 188 children (median age 8.0 years; range, 0.2-18 years), African in 27 children (median age 5.0 years; range, 1-13 years), and other in eight children.

RESULTS

The mean activities of lactase, sucrase, and maltase were significantly higher in Finnish children than in children of African origin (P < 0.0001, P < 0.002, and P < 0.02, respectively). Lactase activity decreased with increasing age (P < 0.001), but age had no significant effect on maltase and sucrase activities. Among Finnish children, 31% (59/188) had lactase activity below the established reference range of 20 units (units are micromoles of substrate hydrolyzed per minute at 37 degrees C per gram of protein) and one child had a probable sucrase-isomaltase deficiency. When these 60 children with low enzyme activities were excluded, the geometric means were lactase, 35.7 units (95% confidence interval [CI], 32.8-38.6 units); maltase, 241 units (95% CI, 225-258 units); and sucrase, 57.5 units (95% CI, 53.5-61.6 units). Among the children of African origin, lactase activity was decreased in 67% (18/27). All three enzyme activities were decreased in parallel more often among the African children (8/27) than among the Finnish children (9/188; P < 0.002).

CONCLUSIONS

Ethnicity has a strong effect on disaccharidase values in children with normal villous structure. African children have lower activities of lactase, sucrase, and maltase in duodenal specimens than do children of Finnish origin.

Testing for serum IgG antibodies to Helicobacter pylori cytotoxin-associated protein detects children with higher grades of gastric inflammation

BACKGROUND

Little information is available about the relationships between Helicobacter pylori cytotoxin-associated protein (CagA) and clinicopathologic features in children. The purpose of this study was to test whether determining serum IgG antibodies to CagA is a useful tool for detecting more severe disease.

METHODS

One hundred twenty-seven consecutive children (age range, 0.75-17.8 years; median, 9.4 years) referred for gastroscopy were included in the study. Antral and corpus biopsies were taken for gastric histology and H. pylori detection. Major symptoms and endoscopic findings were recorded. A serum sample was drawn from each child and assayed for IgG antibodies CagA by a commercial enzyme-linked immunosorbent assay.

RESULTS

Sixty-three (50%) children had no evidence of H. pylori infection, 28 (22%) were H. pylori positive/CagA positive, and 36 (28%) were H. pylori positive/CagA negative. There were no differences in clinical diagnosis and occurrence of any predominant symptom according to H. pylori and CagA status. Findings of antral nodularity were more frequent (p = 0.003) in H. pylori-positive/CagA-positive children than in H. pylori-positive/CagA-negative children. The gastritis score was significantly higher in H. pylori-positive/CagA-positive children than in H. pylori-positive/CagA-negative children (5.7 +/- 1.9 vs. 3.8 +/- 1.6, respectively; p = 0.0003), either in the antral (p = 0.0002) or in the corpus (p = 0.001) mucosa. Inflammation (p = 0.0001) and activity (p = 0.0001) scores were both higher in H. pylori-positive/CagA-positive children than in H. pylori-positive/CagA-negative children, but the H. pylori density score was not significantly different (p = NS). In no case was normal gastric mucosa found in H. pylori-positive/ CagA-positive children. Lymphocytic gastritis (p = 0.0008) and lymphoid follicles (p = 0.000003) were a more frequent finding in H. pylori-positive children than in H. pylori negative children, irrespective of CagA status.

CONCLUSION

Testing for serum IgG to CagA detects higher grades of gastric inflammation among children with H. pylori infection. It may be useful in targeting H. pylori-positive/ CagA-positive children for antimicrobial therapy while reducing the need for endoscopy and gastric biopsy.