Changes in Seroprevalence of Helicobacter pylori Infection over 20 Years in Jinju, Korea, from Newborns to the Elderly

Background@#The objective of this study was to examine changes in the prevalence of cytotoxic-associated gene A (CagA) positive Helicobacter pylori infection in Jinju, Korea, over the last 20 years. @*Methods@#Three cross-sectional analyses were conducted concurrently. A total of 1,305 serum samples were collected from 1994–1995, 2004–2005, and 2014–2015, respectively. The presence of immunoglobulin (Ig) G, IgA, and IgM antibodies against H. pylori CagA protein was examined by western blotting. @*Results@#Overall, seropositivity for anti-CagA IgG antibody was significantly decreased from 63.2% to 42.5% over the last 20 years (P < 0.001). Anti-CagA IgG seropositivities in children and young adults aged 10–29 years decreased from 1994 (60.0%–85.0%) to 2015 (12.5%– 28.9%). The age when plateau of increasing IgG seropositivity was reached in each study period shifted from the 15–19 year-old group in 1994–1995 (85.0%) to the 40–49 year-old group in 2014–2015 (82.5%). Overall seropositive rates of anti-CagA IgA and IgM antibodies did not change significantly either over the last 20 years. @*Conclusion@#H. pylori infection rate in children and young adults declined over 20 years in Jinju, probably due to improved sanitation, housing, or economy.

Proteome Analysis of Alkylhydroxide Peroxidase-Deficient Isogenic Mutant of Helicobacter pylori 26695

In order to investigate the antioxidant effect of alkylhydroxide peroxidase (ahpC) of Helicobacter pylori (H. pylori) 26695, an ahpC-deficient mutant (H. pylori 26695 ahpC::cat) was generated. ahpC-deficient mutant was grown slowly at lower pressure of oxygen (5% oxygen) compared to the H. pylori 26695. Whole cell proteins isolated form H. pylori 26695 and H. pylori 26695 ahpC::cat were analyzed by MALDI-TOF and tandem-MS. The expression of 15 proteins, including Ppa, HypB, GrpE, Elp, RecA, GroES, Mda66, RibE, NapA, GlnA, BioB, TrxB, Tsf, FumC and Icd, was more than doubled in H. pylori 26695 ahpC::cat. Production of 10 proteins such as UreG, FabE, Adk, Pnp, OorC, AtpA, AtpD, Nqq3, Pfr, and TagD decreased below 50% in H. pylori 26695 ahpC::cat compared to the H. pylori 26695. In microarray analysis, 9 genes including sul1, amiE, frxA, fecA, hyuA, and katA increased in transcription level in H. pylori 26695 ahpC::cat compared to H. pylori 26695. A total of 24 genes, including flaB, protein kinase C inhibitor, cag16, pabC, and sabA, reduced in transcription. 27 genes, including HP0889, showed common expression changes in ahpC, katA, and sodB-deficient mutations. As a result of this study, there were not many genes whose expression was commonly changed by the deletion of each of the three major antioxidant enzymes of H. pylori. These results showed the functions and regulation of the three antioxidant enzymes were different in H. pylori.

Characterization of Specific IgA Response to Antigenic Determinants of Helicobacter pylori Urease Encoded by ureA and ureB in Children

Helicobacter pylori (H. pylori), a causative agent of chronic gastritis and gastric cancer, has several virulent factors for own survival and progression toward gastric diseases in human stomach. Of those, H. pylori produces mainly urease (10~15% total protein weight) that neutralize the gastric acid for survival. Here, we identified the antigenic epitope of urease and then developed an ELISA using the antigen including the epitope of urease. We identified the antigenic epitope of urease that induces IgA antibodies in human using truncated mutants. Eight kinds of serially-truncated mutant of UreA and UreB were prepared and subjected to immunoblot using pooled sera of patients with gastric disorders. UreBEnd protein containing UreB epitope was produced and investigated its diagnostic value via ELISA in children. As a result, mutants having last 24 amino acid residues of UreB carboxyl terminus deleted did not show IgA-reactive band. The clones that contained the downstream of 448(th) amino acid in UreB showed IgA-reactive band. The serodiagnostic value of the UreBEnd recombinant protein including identified epitope was confirmed via IgA ELISA and shown to have 97% sensitivity and 100% specificity. These results demonstrated that carboxyl terminal region of UreB carries an antigenic epitope for IgA response in human. It may be useful for detecting H. pylori infection with improved test accuracy and minimum use of endoscopy.

Helicobacter pylori Antigens Inducing Early Immune Response in Infants

To identify the Helicobacter pylori antigens operating during early infection in sera from infected infants using proteomics and immunoblot analysis. Two-dimensional (2D) large and small gel electrophoresis was performed using H. pylori strain 51. We performed 2D immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) antibody immunoblotting using small gels on sera collected at the Gyeongsang National University Hospital from 4–11-month-old infants confirmed with H. pylori infection by pre-embedding immunoelectron microscopy. Immunoblot spots appearing to represent early infection markers in infant sera were compared to those of the large 2D gel for H. pylori strain 51. Corresponding spots were analyzed by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF-MS). The peptide fingerprints obtained were searched in the National Center for Biotechnology Information (NCBI) database. Eight infant patients were confirmed with H. pylori infection based on urease tests, histopathologic examinations, and pre-embedding immunoelectron microscopy. One infant showed a 2D IgM immunoblot pattern that seemed to represent early infection. Immunoblot spots were compared with those from whole-cell extracts of H. pylori strain 51 and 18 spots were excised, digested in gel, and analyzed by MALDI-TOF-MS. Of the 10 peptide fingerprints obtained, the H. pylori proteins flagellin A (FlaA), urease β subunit (UreB), pyruvate ferredoxin oxidoreductase (POR), and translation elongation factor Ts (EF-Ts) were identified and appeared to be active during the early infection periods. These results might aid identification of serological markers for the serodiagnosis of early H. pylori infection in infants.

Correlations between the CagA Antigen and Serum Levels of Anti-Helicobacter pylori IgG and IgA in Children

We tested correlations between anti-Helicobacter pylori IgG and IgA levels and the urease test, anti-CagA protein antibody, degree of gastritis, and age. In total, 509 children (0-15 years) were enrolled. Subjects were stratified as 0-4 years (n = 132), 5-9 years (n = 274), and 10-15 years (n = 103) and subjected to the urease test, histopathology, ELISA, and western blot using whole-cell lysates of H. pylori strain 51. The positivity rate in the urease test (P = 0.003), the degree of chronic gastritis (P = 0.021), and H. pylori infiltration (P < 0.001) increased with age. The median titer for anti-H. pylori IgG was 732.5 IU/mL at 0-4 years, 689.0 IU/mL at 5-9 years, and 966.0 IU/mL at 10-15 years (P < 0.001); the median titer for anti-H. pylori IgA was 61.0 IU/mL at 0-4 years, 63.5 IU/mL at 5-9 years, and 75.0 IU/mL at 10-15 years (P < 0.001). The CagA-positivity rate was 26.5% at 0-4 years, 36.5% at 5-9 years, and 46.6% at 10-15 years for IgG (P = 0.036), and 11.3% at 0-4 years, 18.6% at 5-9 years, and 23.3% at 10-15 years for IgA (P < 0.001). Anti-H. pylori IgG and IgA titers increased with the urease test grade, chronic gastritis degree, active gastritis, and H. pylori infiltration. Presence of CagA-positivity is well correlated with a high urease test grade and high anti-H. pylori IgG/IgA levels.

Helicobacter pylori Infection and Intestinal Metaplasia among Healthy Adolescents

BACKGROUND/AIMS: The purpose of our study was to investigate the change in incidence of intestinal metaplasia (IM) in healthy, young adults over 10 years. MATERIALS AND METHODS: Urease test and histopathology by endoscopic biopsies were performed from volunteers between 1995 and 2005. Histopathological grade was assessed using the updated Sydney System. RESULTS: In total, 714 subjects with a median age of 22.4 years were enrolled. Helicobacter pylori was observed at the antrum and body in 44.5% and 35.1%, respectively. IM limited to the antrum was present in 1.1% of the subjects. The degree of IM correlated negatively with age (P=0.04) but there was no correlation with H. pylori levels or the degree of chronic or active gastritis. Compared to the beginning of the study period, the positivity rate at the end of the study period droped to 45%. IM incidence did not change over the 11-year study period, whereas H. pylori-positivity and the frequency of chronic and active gastritis in the antrum and body dropped significantly over this period (P<0.05). CONCLUSIONS: This result suggests that other factors, besides chronic H. pylori infection or degree of gastritis, may contribute to the progression of atrophy to IM in healthy, young adults.

Anti-Helicobacter pylori Compounds from Maackia amurensis

Eight isoflavonoid compounds were isolated from the EtOAc fraction of Maackia amurensis which had shown the highest anti-Helicobacter pylori activity among the fractions, using medium pressure liquid chromatography and recrystallization. Based on the spectroscopic data including 1H-NMR, 13C-NMR, HMBC and MS data, the chemical structures of the isolates were determined to be (-)-medicarpin (1), afromosin (2), formononetin (3), tectorigenin (4), prunetin (5), wistin (6), tectoridin (7) and ononin (8). Anti-H. pylori activity of each compound was evaluated with broth dilution assay. As a result, (-)-medicarpin (1), tectorigenin (4) and wistin (6) showed anti-H. pylori activity. (-)-Medicarpin (1) exhibited the most potent growth inhibitory activity against H. pylori with the minimal inhibitory concentration (MIC)90 of 25 microM, and tectorigenin (4) with MIC90 of 100 microM ranked the second. This is the first study to show the anti-H. pylori activity of M. amurensis, and it is suggested that the stem bark of M. amurensis or the EtOAc fraction or the isolated compounds can be a new natural source for the treatment of H. pylori infection.

Association between Gastric pH and Helicobacter pylori Infection in Children / 대한소아소화기영양학회지

PURPOSE: To assess gastric pH and its relationship with urease-test positivity and histological findings in children with Helicobacter pylori infection. METHODS: Fasting gastric juices and endoscopic antral biopsy specimens were collected from 562 children and subjected to the urease test and histopathological examination. The subjects were divided into 3 age groups: 0-4, 5-9, and 10-15 years. The histopathological grade was assessed using the Updated Sydney System, while the gastric juice pH was determined using a pH meter. RESULTS: The median gastric juice pH did not differ significantly among the age groups (p=0.655). The proportion of individuals with gastric pH >4.0 was 1.3% in the 0-4 years group, 6.1% in the 5-9 years group, and 8.2% in 10-15 years (p=0.101). The proportions of moderate and severe chronic gastritis, active gastritis, and H. pylori infiltration increased with age (p<0.005). Urease-test positivity was higher in children with hypochlorhydria (77.8%) than in those with normal gastric pH (31.7%) (p<0.001). Chronic and active gastritis were more severe in the former than the latter (p<0.001), but the degree of H. pylori infiltration did not differ (20.9% vs. 38.9%; p=0.186). CONCLUSION: Gastric pH while fasting is normal in most children regardless of age. Urease-test positivity may be related to hypochlorhydria in children, and hypochlorhydria is in turn related to H. pylori infection.

Proteome Analysis of a Catalase-deficient Isogenic Mutant of Helicobacter pylori 26695

Helicobacter pylori, a gram-negative bacterium, is a causative agent of gastroduodenal diseases of human. Human immune system produces harmful reactive oxygen species to kill this bacterium that locates the microaerophilic mucous layer. H. pylori harbors various antioxidant enzymes including SodB, KatA and AhpC to protect the oxygen toxicity. We removed the catalase gene (katA) from H. pylori 26695 genome, and the change of profile of the gene expression of the mutant was analyzed by high resolution 2-DE followed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), tandem MS and microarray analysis. Eleven and 37 genes were upregulated and downregulated in the mutant respectively, either transcriptionally or translationally. Expression level of pfr and hp1588 that were decreased on protein level in the mutant was confirmed by RT-PCR analysis.

Correlation between Positive Rate and Number of Biopsy Samples on Urease Test in Childhood Helicobacter pylori Infection

To identify the correlation between the number of gastric biopsy samples and the positive rate, we compared the results of urease test using one and three biopsy samples from each 255 children who underwent gastroduodenoscopy at Gyeongsang National University Hospital. The children were divided into three age groups: 0-4, 5-9, and 10-15 yr. The gastric endoscopic biopsies were subjected to the urease test. That is, one and three gastric antral biopsy samples were collected from the same child. The results of urease test were classified into three grades: Grade 0 (no change), 1 (6-24 hr), 2 (1-6 hr), and 3 (<1 hr). The positive rate of urease test was increased by the age with no respect to the number of gastric biopsy samples (one biopsy P = 0.001, three biopsy P < 0.001). The positive rate of the urease test was higher on three biopsy samples as compared with one biopsy sample (P < 0.001). The difference between one and three biopsy samples was higher in the children aged 0-9 yr. Our results indicate that the urease test might be a more accurate diagnostic modality when it is performed on three or more biopsy samples in children.

Influencing Factors to Results of the Urease Test: Age, Sampling Site, Histopathologic Findings, and Density of Helicobacter pylori / 대한소아소화기영양학회지

PURPOSE: We investigated the positivity rate and the time period to the positive color change of the urease test in children and adults and assessed the correlation of the urease test to histopathologic findings. METHODS: From 1995 to 2000, endoscopic biopsies of the antrum and body were collected from 811 children and 224 adults and subjected to urease tests and histopathology. RESULTS: The positivity rate of the urease test was 49.4% for 0-4 years, 48.4% for 5-9 years, 47.3% for 10-15 years, and 62.5% for 20-29 years in the antrum. The positivity rate was 85.1% in 0-4 years, 82.3% in 5-9 years, 74.7% in 10-15 years, and 74.1% in 20-29 years for the body. In the antrum, the highest positivity rate was <1 hour for the group aged 10-29 years and 6-24 hours in the group <10 years old (p<0.0001). In the body, the highest positivity rate was <1 hour in adults and 6-24 hours in children (p<0.0001). The proportions of the positive reactions within 1 hour were similar for the antrum and the body. In the cases of more severe chronic gastritis, active gastritis, and Helicobacter pylori infiltration, a positive urease test reaction occurred more quickly (p<0.0001). CONCLUSION: There were significant differences in urease tests according to age and sampling site. The discrepancy between the antrum and the body was greater in younger children. These results might be related to the low density and patchy distribution of bacteria in children and in the body.

Gastric Autoantigenic Proteins in Helicobacter Pylori Infection

PURPOSE: This study tried to identify novel gastric autoimmune antigens that might be involved in aggravating the atrophic gastritis among patients with Helicobacter pylori infection using two-dimensional immunoblotting analysis. MATERIALS AND METHODS: Proteins from gastric mucosal antrectomy specimens and AGS cells (gastric adenocarcinoma cell lines derived from a Caucasian patient who had received no prior therapy) were 2-dimensionally immunoblotted separately with a pool of 300 sera from H. pylroi-infected patients at Gyeongsang National University Hospital. RESULTS: Thirty-eight autoantigenic proteins including alcohol dehydrogenase [NADP+], alpha enolase, gastrokine-1, gastric triacylglycerol lipase, heat shock 70 kDa protein 1, and peroxiredoxin-2 were identified in the gastric mucosal tissue. Fourteen autoantigenic proteins including programmed cell death 6-interacting protein, serum albumin and T-complex protein 1 subunit gamma were identified in the AGS cells. Albumin, alpha-enolase, annexin A3, cytoplasmic actin 1, heat shock cognate 71 kDa protein and leukocyte elastase inhibitor were commonly observed autoantigenic proteins in both gastric mucosal tissue and AGS cells. Alpha-enolase, glutathione S-transferase P, heat shock cognate 71 kDa protein, heat shock 70 kDa protein 1, human mitochondrial adenosine triphosphate synthase (ATP) subunit beta, mitochondrial 60 kDa heat shock protein, peroxiredoxin-2, 78 kDa glucose-regulated protein precursor, tyrosine-protein phosphatase non-receptor type 11 and Tryptophan-Aspartic acid (WD) repeat-containing protein 1 showed 60% or higher amino acid positivity. CONCLUSION: These newly identified gastric autoimmune antigens might be useful in the control and prevention of gastroduodenal disorders, and might be valuable in breaking the vicious circle that exists in gastroduodenal disorders if their pathophysiological roles could be understood in the progress of chronic atrophic gastritis, gastroduodenal ulcers, intestinal metaplasia, and gastric carcinogenesis.

Helicobacter pylori Infection and Duodenal Gastric Metaplasia in Healthy Young Adults / 대한소화기학회지

BACKGROUND/AIMS: Duodenal ulcers occur relatively frequently in adolescents, like in adults, and may relate to Helicobacter pylori infection and duodenal gastric metaplasia (DGM). This study investigated the association between H. pylori infection and DGM in healthy adults aged 20-29. METHODS: Between 1995 and 2005, endoscopic biopsies of the duodenum, antrum and body were taken from healthy, young volunteers, who were first-year medical students, faculty staff, residents, and research assistants of Gyeongsang National University in Jinju, Korea. Urease tests were performed and the extent of DGM and histopathological grades according to the Updated Sydney System were determined. RESULTS: In total, 662 subjects were enrolled (429 males and 233 females). The median age was 22.3 years. The overall incidence of DGM was 11.5% but DGM was more frequent in males (15.4%) than in females (4.3%) (p<0.0001). While H. pylori positivity rates changed significantly during the 1995-2005 period (p<0.01), the incidences of DGM did not. DGM was observed in 7.2% and 14.9% of subjects who were and were not colonized with H. pylori, respectively. DGM was also associated with less severe chronic gastritis and the absence of active gastritis in both the antrum and body, and the absence of follicles in the antrum (p<0.05). CONCLUSIONS: These findings suggested that DGM is not rare in healthy young adults and is unrelated to gastric H. pylori infection.

Changes in Anti-Group A Rotavirus Antibody Seroprevalence and Levels in the Western Gyeongnam Province of Korea Over 16 Years

To observe how anti-group A rotavirus antibody seropositivity rates and levels have changed in the western region of Gyeongnam Province, 2,030 serum samples collected at four collection periods (1989-1990, 1994-1995, 1999-2000, and 2004-2005) were tested by Enzyme-Linked Immunosorbent Assay for IgG, and IgA antibodies reacting to recombinant VP6 protein. The seroprevalences exhibit no regular patterns over a 16-yr period. For all four collection periods, the anti-rVP6 IgG levels rose steadily during the first 5 months of life, after which they remained high. However, the 2-9 yr and 10-39 yr groups had significantly higher IgG levels in 1999-2000 and 2004-2005, respectively, than in the other collection periods. The 1-5 mo, 40- > or = 60 yr, and 4-29 yr groups had significantly higher IgA levels in 1989-1990, 1999-2000, and 2004-2005, respectively. The 4 yr (25.0%), 5-9 yr (18.8%), 10-14 yr (41.1%), 20-29 yr (35.0%), and 30-39 yr (20.0%) groups in 2004-2005 had significant higher IgA seropositivity rate compared to the other three collection periods. These observations suggest that in the western region of Gyeongnam Province since the late 1990s, rotavirus reinfection has occurred more frequently than previously, with all ages being at risk.

Comparison of Gene Expression Patterns between Helicobacter pylor 26695 and its Superoxide Dismutase Isogenic Mutant

Helicobacter pylori, a causative agent of gastroduodenal diseases, is a Gram-negative microaerophilic bacterium. Although H. pylori locates in the microaerophilic mucous layer, the bacteria would come into contact harmful reactive oxygen species generated by host immune system. It has been reported that H. pylori harbors various defense mechanisms which can protect bacterial cells from oxygen exposure. The change of the gene expression profile of sodB-negative isogenic mutant of H. pylori 26695 was analyzed by high resolution 2-DE followed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem MS and microarray analysis. Eighteen genes and 41 genes were upregulated and downregulated respectively, either transcriptionally or translationally. Expression levels of three genes including trxB, yxjE and ribE that were changed both on a mRNA level and on a protein level were confirmed by RT-PCR analysis. However, change of expression levels of other major antioxidants such as KatA, AhpC and NapA were not detected, which means Sod is regulated by different way from that of KatA and AhpC. Mutant study of other antioxidant proteins may give us better understanding for the regulation of stress response in H. pylori.

Comparison of Four Commercial ELISA Kits and In-House Immunoblotting for Diagnosis of Helicobacter pylori Infection / 대한소아소화기영양학회지

PURPOSE: Commercial enzyme-linked immunosorbent assay (ELISA) kits have been considered less reliable for children than for adults. The aim of this study was to compare four ELISA kits and in-house immunoblotting based on the analysis of anti-H. pylori-IgG antibody reactivity. METHODS: A total of 399 serum samples were collected at the GNU Hospital during 1998-1999. All sera were tested using ELISA and immunoblotting. Statistically significant differences were determined by the chi2 test. RESULTS: The overall seropositivity rates using GAP IgG, Genedia IgG, HM-CAP, Pyloriset EIA-G, and immunoblotting were 13.0%, 25.1%, 18.3%, 15.8%, and 62.9%, respectively. Immunoblotting showed a higher seropositivity rate than did all four ELISA kits in all age groups. Genedia IgG had the highest seropositivity among the ELISA kits. The seropositivity rate for children aged 13 to 18 months was lowest, and that of children aged 15 years was highest (90.0%). The seropositivity rate for children aged 7 months to 5 years was significantly lower than that for children aged 6 to 15 years among the four ELISA kits (p<0.0001) and immunoblotting (p=0.02). CONCLUSION: Immunoblotting is the most sensitive test for detection of anti-Helicobacter pylori IgG antibodies among the serological tests in this study. These results emphasize the need for standardization when commercial ELISA tests are used in different nations or in young age groups. Immunoblotting could be a suitable noninvasive assay for serodiagnosis and seroepidemiologic study of H. pylori infection in Korean children.

Comparison of the Antibiotic Resistance of Helicobacter pylori Isolated in Jinju Over a 15-year Period

The aims of this study were to investigate the changing pattern of Helicobacter pylori antibiotic resistance in Jinju over a 15-year period. H. pylori strains were isolated from 170 adults living in Jinju from 1985-1989, 1990-1994 and 1995-1999, and from 23 adults living in Cheongju from 1995 to 1999. Susceptibility to erythromycin, clarithromycin, azithromycin, amoxicillin, tetracycline, metronidazole, furazolidone, levofloxacin, ciprofloxacin, moxifloxacin, and rifabutin was tested using the serial two-fold agar dilution method. Moxifloxacin resistance significantly increased in Jinju from 1985-1989 (0%) to 1995-1999 (14.9%) (p < 0.0001). Resistance to amoxicillin was increasesed trend to decreased trend from 1985 to 1999 (p = 0.033), whereas metronidazole resistance decreased from 37.5% to 21.3%. Resistance to furazolidone was greater from 1985-1989 (9.4%) than in 1995-1999 (2.1%). In comparing Jinju and Cheongju, minimal inhibitory concentrations (MICs) of tetracycline and levofloxacin among H. pylori isolated from Jinju were lower than for isolates from Cheonju (p < 0.05). The levofloxacin resistance rate was higher in Cheongju than in Jinju (p = 0.02). No macrolide resistance was observed in Cheongju. Overall, we did not observe any remarkable antimicrobial resistance increase of H. pylori strains isolated from Jinju over 15 years. The MIC distributions of antimicrobials and antimicrobial resistant rates were time- and region-specific among different strains. Future anti-H. pylori eradication regimens should be designed based on the changing patterns of antimicrobial resistance according to the resident area.

Proteomic Analysis of Thiol-active Proteins of Helicobacter pylori 26695

Helicobacter pylori are a capnophilic bacterium, which colonize gastric mucosa and are resistant to acidic and oxidative damage. Thiol-active proteins subserve redox functions in tolerating oxidative stress and environmental toxicants, such as hydrogen peroxide and hypochlorous acid. We analyzed disulfide-containing proteins of H. pylori strain 26695. Active disulfide-containing proteins were separated by thiol-affinity chromatography, displayed with two-dimensional electrophoresis (2-DE), and identified by MALDI-TOF-MS. Thirty-five putative disulfide proteins, including AhpC (HP1563), GroEL (HP0011), and FrdB (HP0191), were identified in this study. In addition, 4 disulfide proteins of HypB, FusA, TufB, and AhpC showed enhanced intensities in the periplasmic space when compared with the pellet, suggesting that these proteins might play roles in the first redox system against environmental oxidative stresses. Disulfide-containing proteins identified in this study will provide the standard landscape for constructing the proteome components responsible for redox regulation of H. pylori.

Helicobacter pylori Infection and Extraintestinal Manifestations in Children / 대한소아소화기영양학회지

Helicobacter pylori (H. pylori) may be one of the most common pathogen in gastrointestinal tract. Although several recent articles have reported a decline in the prevalence of H. pylori infection in both children and adults over the last several years, H. pylori infection usually occurs early in life and persists for a long time. The role of H. pylori in some digestive diseases, such as gastritis, ulcer and gastric cancer has been well established. And the possible role of H. pylori as a trigger for some extraintestinal diseases in children and adults has been considered in the last year. H. pylori infection might be associated with refractory iron deficiency anemia, idiopathic thrombocytopenic purpura, growth retardation and obesity etc, directly or indirectly. Most of the studies are classified as epidemiological, clinical researches about effects on extraintestinal manifestations after eradication, or case reports. This review describes the possibility of association with several extraintestinal diseases and H. pylori infection and their possible mechanisms based on reported studies in the world and our several studies, even though there are still many conflicting results about that.

Purification and Characterization of Helicobacter pylori gamma-Glutamyltranspeptidase

Gamma-glutamyltranspeptidase (GGT) was purified to electrophoretic homogeneity from the cell extract of H. pylori. The purified enzyme consisted of heavy and light subunits with molecular weights of 38 kDa and 21 kDa, respectively. N-terminal amino acid sequence of heavy and light subunits revealed that H. pylori GGT was processed into 3 parts for a signal peptide of 27 amino acid residues, a heavy subunit of 352 residues, and a light subunit of 188 residues during translation. The reaction rate for hydrolysis of gamma-GpNA was 84.4 micromol/min per milligram of protein, and that for the gamma-glutamyl transfer from gamma-GpNA to gly-gly was 23.8 micromol/min per milligram of protein. The apparent Km values of H. pylori GGT for gamma-glutamyl compounds were on the order of 10-3 to 10-4 M and those for acceptor peptides and amino acids were on the order of 10-1 to 10-2 M. The GGT protein kept approximately 80% of the initial enzymatic activity on incubation at 60degrees C for 15 min. The optimum temperature and pH for reactions of both hydrolysis and transpeptidation were 40degrees C and 9.0, respectively. The transpeptidation and hydrolysis reactions catalyzed by H. pylori GGT were strongly inhibited by L-Gln and moderately inhibited by L-Ala, L-Ser, beta-chloro-L-Ala, and L-Glu. These results demonstrated that the biochemical properties of H. pylori GGT are different from those of other bacterial GGTs. Further, H. pylori GGT might degrade glutathione in the gastric mucous layer of humans if the enzyme could be secreted in the bacterial niches.