Brief Article
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Dec 14, 2013; 19(46): 8758-8763
Published online Dec 14, 2013. doi: 10.3748/wjg.v19.i46.8758
Association between TNF-α and IL-1β genotypes vs Helicobacter pylori infection in Indonesia
Yang Zhao, Jing-Wen Wang, Tsutomu Tanaka, Akihiro Hosono, Ryosuke Ando, Shinkan Tokudome, Soeripto, FX Ediati Triningsih, Tegu Triono, Suwignyo Sumoharjo, EY Wenny Astuti Achwan, Stephanus Gunawan, Yu-Min Li
Yang Zhao, Department of Cancer Center, Second Hospital of Lanzhou University, Lanzhou 730030, Gansu Province, China
Yang Zhao, Jing-Wen Wang, Tsutomu Tanaka, Akihiro Hosono, Shinkan Tokudome, Department of Public Health, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Aichi, Japan
Jing-Wen Wang, Bell Research Center for Reproductive Health and Cancer, Medical Corporation Kishokai, Nagoya 458-0818, Aichi, Japan
Ryosuke Ando, Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Aichi, Japan
Shinkan Tokudome, Department of Nutritional Epidemiology, National Institute of Health and Nutrition, Tokyo 162-8636, Japan
Soeripto, FX Ediati Triningsih, Tegu Triono, Suwignyo Sumoharjo, EY Wenny Astuti Achwan, Department of Anatomic Pathology, Gadjah Mada University Faculty of Medicine, Daerah Istimewa Yogyakarta 55281, Indonesia
Stephanus Gunawan, Department of Biomedical Research Unit, General Hospital of West Nusa Tenggara Province, Mataram 83117, Lombok, Indonesia
Yu-Min Li, First Department of General Surgery, Second Hospital of Lanzhou University, Lanzhou 730030, Gansu Province, China
Yu-Min Li, Gansu Provincial Key Laboratory of Digestive System Tumors, Lanzhou 730030, Gansu Province, China
Author contributions: Zhao Y performed the majority of experiments and wrote the manuscript; Wang JW give a help in statistics of the study; Tanaka T implementation of the H. pylori detection to collected samples by Urea breath test; Hosono A and Ando R participated sample collection in the local of Indonesia; Tokudome S designed the study and provided funding for this work; Soeripto, Triningsih FXE, Triono T, Sumoharjo S, Achwan EYWA, Gunawan S provided the collection of all the human material to this work; Li YM give a help to wrote the manuscript.
Correspondence to: Yu-Min Li, PhD, Professor, First Department of General Surgery, Second Hospital of Lanzhou University, 82 Cuiyingmen, Lanzhou 730030, Gansu Province, China. liym@lzu.edu.cn
Telephone: +86-931-8942744 Fax: +86-931-8458109
Received: July 17, 2013
Revised: October 9, 2013
Accepted: October 19, 2013
Published online: December 14, 2013

Abstract

AIM: To investigate the correlation between the Helicobacter pylori (H. pylori) infection and host genetic background of healthy populations in Indonesia.

METHODS: In March 2007, epidemiological studies were undertaken on the general population of a city in Indonesia (Mataram, Lombok). The participants included 107 men and 187 women, whose ages ranged from 6 to 74 years old, with an average age of 34.0 (± 14.4) (± SD). The H. pylori of subject by UBT method determination, and through the polymerase chain reaction with confronting two-pair primers (PCR-CTPP) method parsing the single nucleotide polymorphism of interleukin (IL)-8, IL-4, IL-1β, CD14, tumor necrosis factor (TNF-α) and tyrosine-protein phosphates non-receptor type 11 (PTPN11) genotypes. The experimental data were analyzed by the statistical software SAS.

RESULTS: The H. pylori infection rates in the healthy Indonesian population studied were 8.4% for men and 12.8% for women; no obvious differences were noted for H. pylori infection rates by sex or age. TC genotypes of IL-4, TC and CC genotypes of TNF-α, and GA genotypes of PTPN11, were higher in frequency. Both CC and TC genotype of TNF-α T-1031C loci featured higher expressions in the healthy Indonesian population Indonesia studied of (OR = 1.99; 95%CI: 0.67-5.89) and (OR = 1.66; 95%CI: 0.73-3.76), respectively. C allele of IL-1β T-31C gene locus was at a higher risk (OR = 1.11; 95%CI: 0.70-1.73) of H. pylori infection, but no statistical significance was found in our study.

CONCLUSION: We reveal that the association between the TNF-α and IL-1β genotypes may be the susceptibility of H. pylori in the studied population.

Key Words: Helicobacter pylori, Tumor necrosis factor, Interleukin-1β, Infection, Allele

Core tip: We found single nucleotide polymorphism of tumor necrosis factor-α and allele of interleukin-1β having high frequency in the healthy Indonesian population, which may be associated with potential contact with Helicobacter pylori (H. pylori) infection. Throughout, H. pylori studies were conducted in patients, and treatment was based on quadruple antibiotics to eradicate H. pylori infection in clinical trials. However, the implications of the individual differences in recurrent infections and drug resistance of H. pylori and other issues must be addressed. Therefore, vaccine development for prevention of H. pylori will be a topical issue in the coming years.



INTRODUCTION

Helicobacter pylori (H. pylori) is a microaerophilic (G-) bacteria that colonizes the area of stomach and duodenum, causing chronic inflammation of the gastric mucosa, the development of the stomach ulcers and even gastric cancer[1]. H. pylori is a class I carcinogen, and has been identified by the WHO as a cancer-causing prokaryotes[2]. More than 50% of the world’s population infected with H. pylori, but 80% of people infected with H. pylori show no symptoms[3]. The H. pylori infection occurs mainly in economically underdeveloped regions, and the H. pylori infection rates of China, Japan and Korea were higher than developed countries[4-6], while the infection rates of Thailand and Vietnam were higher than Indonesia in Southeast Asia[7]. Regarding the ethnic groups of Singapore, H. pylori infection and the incidence of digestive diseases was higher in the Indian and Chinese than the Malay population[8]. The above studies have shown that H. pylori infection and geographical, ethnic and host genetic background is relational, and that the bacteria play a key role in the development of gastric cancer.

Single nucleotide polymorphism (SNP) is caused by a single nucleotide mutation in the genomic level DNA sequence polymorphisms. It is the most common type of genetic variation in humans. Accounting for more than 90% of all known polymorphisms, SNP is widespread in the human genome and there is a close relationship between the incidences of the disease[9]. Interleukin-8 (IL-8) is an important regulatory factor in the development of gastritis for H. pylori associated infection[10]. The interleukin-4 (IL-4) promotes HLA class II antigen expression in B-cells[11], and IL-1β protein is an important inflammatory mediator, involved in infected H. pylori of the stomach inflammation reaction[12,13]. Have a study reported that the cluster of differentiation 14 (CD14) is an important receptor in the submission of H. pylori lipopolysacharide (LPS). The relationship is between CD14 with the weakening of the immune response in the body to LPS of H. pylori and to reduce the proinflammatory cytokine secretion levels[14]. Tumor necrosis factor-α (TNF-α) is involved in inflammation, immune regulation and tissue repair, and the TNF-α is an important factor in the development of digestive diseases[15]. The tyrosine-protein phosphates non-receptor type 11 (PTPN11) gene is located in chromosome 12, and it has been found that the expression product of SHP-2 to participate in the cytotoxin-associated protein A (cagA) deformation caused by gastric epithelial cells eventually causes gastric cancer[16].

The purpose of this study was to investigate the correlation of H. pylori infection in a healthy Indonesian population and host genetic background, and to reveal susceptibility genes of H. pylori, as well as new strategies for the prevention and treatment of gastric cancer.

MATERIALS AND METHODS
Study population

In recent years, we have conducted long-term international cooperation in research, exploring the impact of environmental factors on the risk factors of gastric cancer in Southeast Asia, including the countries of Thailand, Vietnam and Indonesia, as well as Gansu Province in China. In March 2007, epidemiological studies were undertaken on the general population of a city in Indonesia (Mataram, Lombok). The participants included 107 men and 187 women, whose ages ranged from 6 to 74 years old, with an average age of 34.0 (± 14.4) (± SD). We detected and analyzed the H. pylori of the observation target as well as the genetic background of the host, namely the IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 genotypes. All the subjects’ informed consent was approved by the Nagoya City University Graduate School of Medical Ethics Committee.

Urea breath test

H. pylori infection was determined by UBT, UBiT-IR300 kits (Otsuka Pharmaceutical Co., Tokyo, Japan) with ≥ 2.5‰ considered as positive. All subjects were classified as H. pylori -positive (+) or -negative (-) in this study[7,8].

Genotyping of DQA1 and DQB1

A template of genomic DNA was isolated from 100 μl of peripheral blood leukocytes by the Nucleic Acid Purification System (MagExtractor MFX-6000 TOYOBO, Japan). We carried out a single nucleotide polymorphism (SNP) analysis of the IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 genotypes by two pairs of polymerase chain reaction (PCR-CTPP)[17-21].

Statistical analysis

Differences in distribution by age according to prevalence of H. pylori infection were examined by t-test, while differences in distribution by sex and genotype were assessed with a Chi-square test. Hardy-Weinberg equilibrium was examined for IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 gene polymorphisms. Multi-comparisons for IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 genotypes were made according to the Bonferroni method. Associations of the IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 genotypes and SNP with H. pylori infection were examined by OR and 95%CI using unconditional logistic regression analysis. Statistical significance was determined as P < 0.05. All the statistical analyses were performed using the SAS software package (version 9.1).

RESULTS

The positive H. pylori infection rate as a whole was 11.2% in Mataram (Table 1). No obvious differences were noted for H. pylori infection rates by sex or age. TC genotypes of IL-4, TC and CC genotypes of TNF-α, and GA genotypes of PTPN11 were frequent. Individuals carrying TC and CC allele of TNF-α was noted to be at higher risk of H. pylori infection, compared with those carrying TT allele of TNF-α (OR = 1.66, 95%CI: 0.73-3.76) and (OR = 1.99, 95%CI: 0.67-5.85), We also found TT and CT genotypes of CD14 C-159T (OR = 1.09, 95%CI: 0.37-3.20) and (OR = 1.26, 95%CI: 0.50-3.19), but no statistical significance was found in our study (Table 2). We found C allele had a higher frequency than T allele of IL-1β genotype in the studied population (OR = 1.11, 95%CI: 0.70-1.73), but again no statistical significance was found (Table 3).

Table 1 Helicobacter pylori infection by sex and age in Indonesian people n (%).
IndonesiaH. pylori (+)n= 33H. pylori (-)n= 261
Sex
Male9 (8.4)98 (91.6)
Female24 (12.8)163 (87.2)
Age, yr
≤ 3012 (9.6)113 (90.4)
31-409 (11.5)69 (88.5)
41-507 (14.6)41 (85.4)
51-603 (9.4)29 (90.6)
≥ 602 (18.2)9 (81.8)
Mean age, yr36.3 ± 14.6 (SD)33.7 ± 14.4 (SD)
Table 2 Association between Helicobacter pylori infection and interleukin 1β, interleukin 4, interleukin 8, CD14, tumor necrosis factor-α, tyrosine-protein phosphates non-receptor type 11 single nucleotide polymorphism in Indonesian people n (%).
PolymorphismH. pylori (+)n= 33H. pylori (-)n= 261OR195%CI1
IL-1β T-31C
TT8 (24.2)59 (22.6)ref
CC8 (24.2)73 (28.0)0.820.29-2.32
TC17 (51.5)129 (49.4)1.050.42-2.59
TC/CC25 (75.8)202 (77.4)0.960.41-2.26
IL-4 T-33C
TT15 (45.5)128 (49.0)ref
CC2 (6.1)19 (7.3)0.830.17-3.99
TC16 (48.5)114 (43.7)1.240.58-2.64
CC/TC18 (54.5)133 (51.0)1.180.56-2.45
IL-8 T-251A
TT14 (42.4)98 (37.6)ref
AA8 (24.2)49 (18.8)1.250.48-3.27
TA11 (33.3)114 (43.7)0.740.32-1.72
TA/AA19 (57.6)163 (62.5)0.890.42-1.88
CD14 C-159T
CC7 (21.2)65 (24.9)ref
TT8 (24.2)65 (24.9)1.090.37-3.20
CT18 (54.6)131 (50.2)1.260.50-3.19
CT/TT26 (78.8)196 (75.1)1.20.50-2.92
TNF-α T-1031C
TT11 (33.3)120 (46.0)ref
CC6 (18.2)36 (13.8)1.990.67-5.89
TC16 (48.5)105 (40.2)1.660.73-3.76
CC/TC22 (66.7)141 (54.0)1.740.80-3.76
PTPN11 G/A at intron 3
GG17 (51.5)151 (57.9)ref
AA1 (3.0)17 (6.5)0.60.07-4.86
GA15 (45.5)93 (35.6)1.490.70-3.15
GA/AA16 (48.5)110 (42.2)1.370.65-2.85
Table 3 Association between Helicobacter pylori infection and allele of interleukin 1β, interleukin 4, interleukin 8, CD14, tumor necrosis factor-α, tyrosine-protein phosphates non-receptor type 11 in Indonesian people n (%).
AlleleH. pylori (+)n= 66H. pylori (-)n= 522OR195%CI
IL-1β T-31C
T33 (50.0)247 (47.3)ref
C33 (50.0)275 (52.7)1.100.70-1.73
IL-4 T-33C
T46 (69.7)370 (70.9)ref
C20 (30.3)152 (29.1)0.950.58-1.56
IL-8 T-251A
T39 (59.1)310 (59.4)ref
A27 (40.9)212 (40.6)0.990.62-1.57
CD14 C-159T
C32 (48.5)261 (50.0)ref
T34 (51.5)261 (50.0)0.950.60-1.49
TNF-α T-1031C
T38 (57.6)345 (66.1)ref
C28 (42.4)177 (33.9)0.730.46-1.15
PTPN11 G/A at intron 3
G49 (74.2)395 (75.7)ref
A17 (25.8)127 (24.3)0.940.56-1.57
DISCUSSION

In 50% of the world’s population was infected H. pylori infection rates in developing countries were higher than in developed countries, and it has been reported that hosts at an early age have been infected[22]. Indonesia, located in Southeast Asia, is a developing country, but we found that the country has an H. pylori infection rate which was very low. We investigated associations between SNP of the host IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 gene polymorphisms and H. pylori prevalence in an Indonesian population with an H. pylori infection rate of 11.2% in people residing in Mataram, Lombok Island. Although SNP of host IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 genotype with H. pylori infection were not found to have statistical significance in our study, we saw that an observation target who had the CC and TC genotype of TNF-α gene were at a higher risk of contracting H. pylori infection. Perhaps, TNF-α gene plays a key role in the H. pylori infection process.

H. pylori is widely present in the environment, and it can be isolated in surface waters[23], i.e., transmitted by the fecal - oral route[24]. Studies have shown that through certain digestive diseases and strains of H. pylori, Cytotoxin-associated protein A (cagA) is now known as the most important virulence factors of H. pylori[25]. CagA is an H. pylori cag poison island (cag-PAI) flag, and by cag-PAI coded protein is composed of a bacterial type IV secretion system into gastric epithelial cells, which ultimately causes gastric mucosal epithelium, the morphological changes of the cells and the formation of a hummingbird-like structure[26]. Host infected cagA-positive H. pylori is less likely to cause digestive diseases, but may damage the gastric mucosal barrier and is cagA related. H. pylori infection with strains, geographical, ethnic, and environmental and host genetic background was a correlation.

The IL-8 as a neutrophil chemoattractant and activating factor, which relates to H. pylori infection, resulting in second messenger of the mucosal inflammatory response in the H. pylori pathogen city, plays an important role of intermediary. But what components of H. pylori surface play a major role in the induction of IL-8 expression is still one of the main points about H. pylori pathogenesis. Of H. pylori cytotoxin-associated protein (cagA) and vacuolating cytotoxin (vacA) on gastric epithelial IL-8 secretion, showing expression of cagA and vacA H. pylori strains (vacA+, cagA+) direct stimulation of gastric epithelial cell lines IL-8 mRNA expression and protein secretion of IL-8, suggests that expression of the gene product and cagA H. pylori strains induced gastric epithelial expression of IL-8 in the main factors[11]. In addition to H. pylori gastric epithelial cells directly stimulating the production of IL-8, the inflammation locally produced of TNF-α, transcription factor activation of the IL-1, was also an up-regulated expression of IL-8[11]. Furthermore H. pylori, in addition to the expression of IL-8 induced gastric epithelial cells, also stimulates gastric epithelial cells TNF-α, IL-1β expression[27,28]. In H. pylori infection, IL-8 chemotaxis of neutrophil infiltration and epithelial damage caused by H. pylori vacuoles toxins can promote mucous membrane endocytosis bacterial products and induction of mucosal phagocytic cells to secrete cytokines IL-1β, TNF-α and IL-8; neutrophils are attracted to the infected local, while neutrophils becomes the main source of iL-1, TNF-α and iL-8 induced inflammatory cytokines. Neutrophil elastase also relates to the epithelial cells induced by IL-8 gene expression, suggesting that the neutrophil enzyme release cytokines can induce a continuity of the inflammatory process itself[29], and H. pylori-induced IL-8, IL-1β cytokine expression throughout the entire H. pylori infection period[30]. Studies found that Protein-tyrosine phosphatase, non-receptor-Type11 (PTPN11) encoding Srchomology 2 domain-containing pro-Tein tyrosine phosphatase-2 (SHP-2) in CagA-induced gastric epithelial cell deformation, that eventually cause the gastric process, played a very important role, and the genetic background of the PTPN11 shows certain racial difference[31,32]. The IL-4 by CD4+ T cell subsets, B cells and mast cells secreted pleiotropic cytokines involved in inflammation, mucosal repair, cell proliferation and apoptosis and other physiological and pathological processes; changes in the expression levels may also affect pathogenesis of H. pylori infection, resulting in a host of different clinical results. The H. pylori infection caused by non-ulcerative gastritis can lead to local Th0 cells producing and secreting large amounts of cytokines IL-4; however, in patients with peptic ulcers, H. pylori infection can be caused by the polarization of Th1 cells[33]. Studies suggest that the CD14 gene C/T mutation may lead to the activation of the CD14 promoter enhanced transcription of the CD14 gene, while monocytes’ high expression of CD14 and CD14 can regulate the secretion of LPS-induced IL-1 and TNF-α[15,34]. TNF-gene coding region mutations may affect TNF-α activity, caused by TNF-α allele or genetic type associated with H. pylori associated gastric duodenal disease susceptibility. In an infected H. pylori host of Japan, it was found that the genotype of the TNF-α-857 C/C and 1031 C/C group serological detection of H. pylori was the lowest positive rate, and in the TNF-α-857 T/T and TNF-B-1031 T/T genotype the serum H. pylori positive rate was the highest[35]. The C/C and T/C genotypes of TNF-α T-1031C locus were at the highest risk from H. pylori infection in our study.

The development of gastric cancer is a complex process, H. pylori infection is caused by one of the risk factors of gastric cancer. In addition, there are environmental factors, social factors, host genetic background and lifestyle. Directly use hand grasp to pilaf is very common, and the schistosome liver disease has also been often reported in Indonesia[36]; however, H. pylori infection and gastric cancer incidence rate were very low. In addition, have also been reports that complications of the esophagus caused by reflux esophagitis after sterilization of cancer have tended to increase[37]. And resistant strains of H.pylori by sterilization treatment have been reported[38].Therefore, it appears that sterilization treatment is not the best means of prevention of gastric cancer. This study explored H. pylori infection with immune response gene polymorphisms in a healthy Indonesian population. Although there was no statistical significance in SNP of IL-8, IL-4, IL-1β, CD14, TNF-α and PTPN11 gene polymorphisms, we found SNP of TNF-αT-1031C locus was the highest risk of H. pylori infection. Our study provides the basis for future research data, and a new direction for the prevention of H. pylori infection.

ACKNOWLEDGMENTS

The authors would like to thank Prof. Dr. Karel Geboes, Prof. Dr. Wim Ceelen, Sowath Ly and Dr. Kathleen Lambein for their help in editing this manuscript. They declare that there is no conflict of interest with this work.

COMMENTS
Background

Helicobacter pylori (H. pylori) infection in developing countries is high in comparison with developed countries. Indonesia is a developing country located in Southeast Asia, but the prevalence of H. pylori in Indonesia is lower than other countries of Southeast Asia.

Innovations and breakthroughs

Throughout, H. pylori studies were conducted in patients, and treatment was based on quadruple antibiotics to eradicate H. pylori infection in clinical settings. However, the implications of the individual differences in recurrent infections and drug resistance of H. pylori and other issues must be addressed. The authors observed that the object was a healthy crowd, which reveals that in the host genetic background there is a certain association with H. pylori infection.

Applications

This study provided basic vaccine development data for the prevention of H. pylori, and for the prevention of gastric cancer through the advancement of new ideas.

Terminology

H. pylori is a Gram-negative, microaerophilic bacterium found in the stomach. It was identified in 1982 by the Australian scientists Barry Marshall and Robin Warren, who found that it was present in patients with chronic gastritis and gastric ulcers, conditions that were not previously believed to have a microbial cause. It is also linked to the development of duodenal ulcers and stomach cancer. However, over 80 percent of individuals infected with the bacterium are asymptomatic, and it has been postulated that it may play an important role in the natural stomach ecology.

Peer review

The manuscript is interesting, but the absence of statistical significance is an important issue.

Footnotes

P- Reviewer: Ozturk Y S- Editor: Wen LL L- Editor: A E- Editor: Zhang DN

References
1.  Backert S, Schwarz T, Miehlke S, Kirsch C, Sommer C, Kwok T, Gerhard M, Goebel UB, Lehn N, Koenig W. Functional analysis of the cag pathogenicity island in Helicobacter pylori isolates from patients with gastritis, peptic ulcer, and gastric cancer. Infect Immun. 2004;72:1043-1056.  [PubMed]  [DOI]
2.  Vogiatzi P, Cassone M, Luzzi I, Lucchetti C, Otvos L, Giordano A. Helicobacter pylori as a class I carcinogen: physiopathology and management strategies. J Cell Biochem. 2007;102:264-273.  [PubMed]  [DOI]
3.  Brown LM. Helicobacter pylori: epidemiology and routes of transmission. Epidemiol Rev. 2000;22:283-297.  [PubMed]  [DOI]
4.  Brown LM, Thomas TL, Ma JL, Chang YS, You WC, Liu WD, Zhang L, Pee D, Gail MH. Helicobacter pylori infection in rural China: demographic, lifestyle and environmental factors. Int J Epidemiol. 2002;31:638-645.  [PubMed]  [DOI]
5.  Tokudome S, Soeripto FX, Ananta I, Suzuki S, Kuriki K, Akasaka S, Kosaka H, Ishikawa H, Azuma T, Moore MA. Rare Helicobacter pylori infection as a factor for the very low stomach cancer incidence in Yogyakarta, Indonesia. Cancer Lett. 2005;219:57-61.  [PubMed]  [DOI]
6.  Lee JH, Kim N, Chung JI, Kang KP, Lee SH, Park YS, Hwang JH, Kim JW, Jeong SH, Lee DH. Long-term follow up of Helicobacter pylori IgG serology after eradication and reinfection rate of H. pylori in South Korea. Helicobacter. 2008;13:288-294.  [PubMed]  [DOI]
7.  Tokudome S, Samsuria Soeripto WD, Triningsih FX, Suzuki S, Hosono A, Triono T, Sarjadi IW, Miranti IP, Ghadimi R, Moore MA. Helicobacter pylori infection appears essential for stomach carcinogenesis: observations in Semarang, Indonesia. Cancer Sci. 2005;96:873-875.  [PubMed]  [DOI]
8.  Hamlet AK, Erlandsson KI, Olbe L, Svennerholm AM, Backman VE, Pettersson AB. A simple, rapid, and highly reliable capsule-based 14C urea breath test for diagnosis of Helicobacter pylori infection. Scand J Gastroenterol. 1995;30:1058-1063.  [PubMed]  [DOI]
9.  Kang JY, Wee A, Math MV, Guan R, Tay HH, Yap I, Sutherland IH. Helicobacter pylori and gastritis in patients with peptic ulcer and non-ulcer dyspepsia: ethnic differences in Singapore. Gut. 1990;31:850-853.  [PubMed]  [DOI]
10.  Collins FS, Brooks LD, Chakravarti A. A DNA polymorphism discovery resource for research on human genetic variation. Genome Res. 1998;8:1229-1231.  [PubMed]  [DOI]
11.  Crabtree JE, Wyatt JI, Trejdosiewicz LK, Peichl P, Nichols PH, Ramsay N, Primrose JN, Lindley IJ. Interleukin-8 expression in Helicobacter pylori infected, normal, and neoplastic gastroduodenal mucosa. J Clin Pathol. 1994;47:61-66.  [PubMed]  [DOI]
12.  Ellis MK, Zhao ZZ, Chen HG, Montgomery GW, Li YS, McManus DP. Analysis of the 5q31 33 locus shows an association between single nucleotide polymorphism variants in the IL-5 gene and symptomatic infection with the human blood fluke, Schistosoma japonicum. J Immunol. 2007;179:8366-8371.  [PubMed]  [DOI]
13.  Arend WP, Guthridge CJ. Biological role of interleukin 1 receptor antagonist isoforms. Ann Rheum Dis. 2000;59 Suppl 1:i60-i64.  [PubMed]  [DOI]
14.  El-Omar EM. The importance of interleukin 1beta in Helicobacter pylori associated disease. Gut. 2001;48:743-747.  [PubMed]  [DOI]
15.  Hubacek JA, Rothe G, Pit’ha J, Skodová Z, Stanĕk V, Poledne R, Schmitz G. C(-260)--> T polymorphism in the promoter of the CD14 monocyte receptor gene as a risk factor for myocardial infarction. Circulation. 1999;99:3218-3220.  [PubMed]  [DOI]
16.  Hellmig S, Bartscht T, Fischbach W, Fölsch UR, Schreiber S. Interleukin-10 (-819 C/T) and TNF-A (-308 G/A) as risk factors for H. pylori-associated gastric MALT-lymphoma. Dig Dis Sci. 2008;53:2007-2008.  [PubMed]  [DOI]
17.  Fujihara J, Shiwaku K, Yasuda T, Yuasa I, Nishimukai H, Iida R, Takeshita H. Variation of interleukin 8 -251 A>T polymorphism in worldwide populations and intra-ethnic differences in Japanese populations. Clin Chim Acta. 2007;377:79-82.  [PubMed]  [DOI]
18.  Togawa S, Joh T, Itoh M, Katsuda N, Ito H, Matsuo K, Tajima K, Hamajima N. Interleukin-2 gene polymorphisms associated with increased risk of gastric atrophy from Helicobacter pylori infection. Helicobacter. 2005;10:172-178.  [PubMed]  [DOI]
19.  Migita K, Maeda Y, Abiru S, Nakamura M, Komori A, Miyazoe S, Nakao K, Yatsuhashi H, Eguchi K, Ishibashi H. Polymorphisms of interleukin-1beta in Japanese patients with hepatitis B virus infection. J Hepatol. 2007;46:381-386.  [PubMed]  [DOI]
20.  Hamajima N, Rahimov B, Malikov Y, Abdiev S, Ahn KS, Bahramov S, Kawai S, Nishio K, Naito M, Goto Y. Associations between a PTPN11 polymorphism and gastric atrophy--opposite in Uzbekistan to that in Japan. Asian Pac J Cancer Prev. 2008;9:217-220.  [PubMed]  [DOI]
21.  Ishida Y, Goto Y, Kondo T, Kurata M, Nishio K, Kawai S, Osafune T, Naito M, Hamajima N. Eradication rate of Helicobacter pylori according to genotypes of CYP2C19, IL-1B, and TNF-A. Int J Med Sci. 2006;3:135-140.  [PubMed]  [DOI]
22.  Hamajima N, Saito T, Matsuo K, Kozaki K, Takahashi T, Tajima K. Polymerase chain reaction with confronting two-pair primers for polymorphism genotyping. Jpn J Cancer Res. 2000;91:865-868.  [PubMed]  [DOI]
23.  Klein PD, Graham DY, Gaillour A, Opekun AR, Smith EO. Water source as risk factor for Helicobacter pylori infection in Peruvian children. Gastrointestinal Physiology Working Group. Lancet. 1991;337:1503-1506.  [PubMed]  [DOI]
24.  McKeown I, Orr P, Macdonald S, Kabani A, Brown R, Coghlan G, Dawood M, Embil J, Sargent M, Smart G. Helicobacter pylori in the Canadian arctic: seroprevalence and detection in community water samples. Am J Gastroenterol. 1999;94:1823-1829.  [PubMed]  [DOI]
25.  Kusters JG, van Vliet AH, Kuipers EJ. Pathogenesis of Helicobacter pylori infection. Clin Microbiol Rev. 2006;19:449-490.  [PubMed]  [DOI]
26.  Yamaoka Y, Orito E, Mizokami M, Gutierrez O, Saitou N, Kodama T, Osato MS, Kim JG, Ramirez FC, Mahachai V. Helicobacter pylori in North and South America before Columbus. FEBS Lett. 2002;517:180-184.  [PubMed]  [DOI]
27.  Goto Y, Ando T, Yamamoto K, Tamakoshi A, El-Omar E, Goto H, Hamajima N. Association between serum pepsinogens and polymorphismof PTPN11 encoding SHP-2 among Helicobacter pylori seropositive Japanese. Int J Cancer. 2006;118:203-208.  [PubMed]  [DOI]
28.  Takagi A, Kamiya S, Koga Y, Ohta U, Kobayashi H, Shirai T, Harasawa S, Miwa T. Analysis of interleukin-8 secretion induced by Helicobacter pylori from the gastric epithelial cell line MKN45: a mechanism independent of the intensity of cytotoxicity. J Gastroenterol Hepatol. 1997;12:368-372.  [PubMed]  [DOI]
29.  Genta RM. The immunobiology of Helicobacter pylori gastritis. Semin Gastrointest Dis. 1997;8:2-11.  [PubMed]  [DOI]
30.  Jung HC, Kim JM, Song IS, Kim CY. Helicobacter pylori induces an array of pro-inflammatory cytokines in human gastric epithelial cells: quantification of mRNA for interleukin-8, -1 alpha/beta, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant protein-1 and tumour necrosis factor-alpha. J Gastroenterol Hepatol. 1997;12:473-480.  [PubMed]  [DOI]
31.  Hatakeyama M. Oncogenic mechanisms of the Helicobacter pylori CagA protein. Nat Rev Cancer. 2004;4:688-694.  [PubMed]  [DOI]
32.  Backert S, Ziska E, Brinkmann V, Zimny-Arndt U, Fauconnier A, Jungblut PR, Naumann M, Meyer TF. Translocation of the Helicobacter pylori CagA protein in gastric epithelial cells by a type IV secretion apparatus. Cell Microbiol. 2000;2:155-164.  [PubMed]  [DOI]
33.  Israel DA, Peek RM. pathogenesis of Helicobacter pylori-induced gastric inflammation. Aliment Pharmacol Ther. 2001;15:1271-1290.  [PubMed]  [DOI]
34.  Netea MG, Kullberg BJ, van der Meer JW. Lipopolysaccharide-induced production of tumour necrosis factor and interleukin-1 is differentially regulated at the receptor level: the role of CD14-dependent and CD14-independent pathways. Immunology. 1998;94:340-344.  [PubMed]  [DOI]
35.  Hamajima N, Shibata A, Katsuda N, Matsuo K, Ito H, Saito T, Tajima K, Tominaga S. Subjects with TNF-A-857TT and -1031TT genotypes showed the highest Helicobacter pylori seropositive rate compared with those with other genotypes. Gastric Cancer. 2003;6:230-236.  [PubMed]  [DOI]
36.  Garjito TA, Sudomo M, Abdullah M, Nurwidayati A. Schistosomiasis in Indonesia: past and present. Parasitol Int. 2008;57:277-280.  [PubMed]  [DOI]
37.  Qian B, Ma S, Shang L, Qian J, Zhang G. Effects of Helicobacter pylori eradication on gastroesophageal reflux disease. Helicobacter. 2011;16:255-265.  [PubMed]  [DOI]
38.  Mégraud F. Basis for the management of drug-resistant Helicobacter pylori infection. Drugs. 2004;64:1893-1904.  [PubMed]  [DOI]