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Dual role of Helicobacter and Campylobacter species in IBD: a systematic review and meta-analysis

Castaño-Rodríguez N, Kaakoush NO, Lee WS, Mitchell HM

Gut, 2017 02;66(2):235-249.
PMID: 26508508 DOI: 10.1136/gutjnl-2015-310545

OBJECTIVE: To conduct a comprehensive global systematic review and meta-analysis on the association between Helicobacter pylori infection and IBD. As bacterial antigen cross-reactivity has been postulated to be involved in this association, published data on enterohepatic Helicobacter spp (EHS) and Campylobacter spp and IBD was also analysed.
DESIGN: Electronic databases were searched up to July 2015 for all case-control studies on H. pylori infection/EHS/Campylobacter spp and IBD. Pooled ORs (P-OR) and 95% CIs were obtained using the random effects model. Heterogeneity, sensitivity and stratified analyses were performed.
RESULTS: Analyses comprising patients with Crohn's disease (CD), UC and IBD unclassified (IBDU), showed a consistent negative association between gastric H. pylori infection and IBD (P-OR: 0.43, p value <1e-10). This association appears to be stronger in patients with CD (P-OR: 0.38, p value <1e-10) and IBDU (P-OR: 0.43, p value=0.008) than UC (P-OR: 0.53, p value <1e-10). Stratification by age, ethnicity and medications showed significant results. In contrast to gastric H. pylori, non H. pylori-EHS (P-OR: 2.62, p value=0.001) and Campylobacter spp, in particular C. concisus (P-OR: 3.76, p value=0.006) and C. showae (P-OR: 2.39, p value=0.027), increase IBD risk.
CONCLUSIONS: H. pylori infection is negatively associated with IBD regardless of ethnicity, age, H. pylori detection methods and previous use of aminosalicylates and corticosteroids. Antibiotics influenced the magnitude of this association. Closely related bacteria including EHS and Campylobacter spp increase the risk of IBD. These results infer that H. pylori might exert an immunomodulatory effect in IBD.
Autophagy in Helicobacter pylori Infection and Related Gastric Cancer

Castaño-Rodríguez N, Kaakoush NO, Goh KL, Fock KM, Mitchell HM

Helicobacter, 2015 Oct;20(5):353-69.
PMID: 25664588 DOI: 10.1111/hel.12211

Autophagy, a degradation pathway in which cytoplasmic content is engulfed and degraded by lysosomal hydrolases, plays a pivotal role in infection and inflammation. Given that defects in autophagy lead to increased susceptibility to infection, we investigated the role of autophagy in Helicobacter pylori-related gastric cancer (GC).
Genetic polymorphisms in the Toll-like receptor signalling pathway in Helicobacter pylori infection and related gastric cancer

Castaño-Rodríguez N, Kaakoush NO, Pardo AL, Goh KL, Fock KM, Mitchell HM

Hum Immunol, 2014 Aug;75(8):808-15.
PMID: 24929142 DOI: 10.1016/j.humimm.2014.06.001

Gastric cancer (GC) is a progressive process initiated by Helicobacter pylori-induced inflammation. Initial recognition of H. pylori involves Toll-like receptors (TLRs), central molecules in the host inflammatory response. Here, we investigated the association between novel polymorphisms in genes involved in the TLR signalling pathway, including TLR2, TLR4, LBP, MD-2, CD14 and TIRAP, and risk of H. pylori infection and related GC.
Fulltext The NOD-like receptor signalling pathway in Helicobacter pylori infection and related gastric cancer: a case-control study and gene expression analyses

Castaño-Rodríguez N, Kaakoush NO, Goh KL, Fock KM, Mitchell HM

PLoS One, 2014;9(6):e98899.
PMID: 24901306 DOI: 10.1371/journal.pone.0098899

Currently, it is well established that cancer arises in chronically inflamed tissue. A number of NOD-like receptors (NLRs) form inflammasomes, intracellular multiprotein complexes critical for generating mature pro-inflammatory cytokines (IL-1β and IL-18). As chronic inflammation of the gastric mucosa is a consequence of Helicobacter pylori infection, we investigated the role of genetic polymorphisms and expression of genes involved in the NLR signalling pathway in H. pylori infection and related gastric cancer (GC).
Fulltext Dysbiosis of the microbiome in gastric carcinogenesis

Castaño-Rodríguez N, Goh KL, Fock KM, Mitchell HM, Kaakoush NO

Sci Rep, 2017 11 21;7(1):15957.
PMID: 29162924 DOI: 10.1038/s41598-017-16289-2

The gastric microbiome has been proposed as an etiological factor in gastric carcinogenesis. We compared the gastric microbiota in subjects presenting with gastric cancer (GC, n = 12) and controls (functional dyspepsia (FD), n = 20) from a high GC risk population in Singapore and Malaysia. cDNA from 16S rRNA transcripts were amplified (515F-806R) and sequenced using Illumina MiSeq 2 × 250 bp chemistry. Increased richness and phylogenetic diversity but not Shannon's diversity was found in GC as compared to controls. nMDS clustered GC and FD subjects separately, with PERMANOVA confirming a significant difference between the groups. H. pylori serological status had a significant impact on gastric microbiome α-diversity and composition. Several bacterial taxa were enriched in GC, including Lactococcus, Veilonella, and Fusobacteriaceae (Fusobacterium and Leptotrichia). Prediction of bacterial metabolic contribution indicated that serological status had a significant impact on metabolic function, while carbohydrate digestion and pathways were enriched in GC. Our findings highlight three mechanisms of interest in GC, including enrichment of pro-inflammatory oral bacterial species, increased abundance of lactic acid producing bacteria, and enrichment of short chain fatty acid production pathways.
Fulltext Helicobacter pylori genetic diversity and gastro-duodenal diseases in Malaysia

Gunaletchumy SP, Seevasant I, Tan MH, Croft LJ, Mitchell HM, Goh KL, et al.

Sci Rep, 2014 Dec 11;4:7431.
PMID: 25503415 DOI: 10.1038/srep07431

Helicobacter pylori infection results in diverse clinical conditions ranging from chronic gastritis and ulceration to gastric adenocarcinoma. Among the multiethnic population of Malaysia, Indians consistently have a higher H. pylori prevalence as compared with Chinese and Malays. Despite the high prevalence of H. pylori, Indians have a relatively low incidence of peptic ulcer disease and gastric cancer. In contrast, gastric cancer and peptic ulcer disease incidence is high in Chinese. H. pylori strains from Chinese strains predominantly belong to the hspEAsia subpopulation while Indian/Malay strains mainly belong to the hspIndia subpopulation. By comparing the genome of 27 Asian strains from different subpopulations, we identified six genes associated with risk of H. pylori-induced peptic ulcer disease and gastric cancer. This study serves as an important foundation for future studies aiming to understand the role of bacterial factors in H. pylori-induced gastro-duodenal diseases.
Campylobacter concisus pathotypes are present at significant levels in patients with gastroenteritis

Underwood AP, Kaakoush NO, Sodhi N, Merif J, Seah Lee W, Riordan SM, et al.

J Med Microbiol, 2016 Mar;65(3):219-226.
PMID: 26698172 DOI: 10.1099/jmm.0.000216

Given that Campylobacter jejuni is recognized as the most common cause of bacterial gastroenteritis worldwide, recent findings showing comparable levels of Campylobacter concisus in patients with gastroenteritis would suggest that this bacterium is clinically important. The prevalence and abundance of Campylobacter concisus in stool samples collected from patients with acute gastroenteritis was examined using quantitative real-time PCR. The associated virulence determinants exotoxin 9 and zonula occludens toxin DNA were detected for Campylobacter concisus-infected samples using real-time PCR. Campylobacter concisus was detected at high prevalence in patients with gastroenteritis (49.7 %), higher than that observed for Campylobacter jejuni (∼5 %). The levels of Campylobacter concisus were putatively classified into clinically relevant and potentially transient subgroups based on a threshold developed using Campylobacter jejuni levels, as the highly sensitive real-time PCR probably detected transient passage of the bacterium from the oral cavity. A total of 18 % of patients were found to have clinically relevant levels of Campylobacter concisus, a significant number of which also had high levels of one of the virulence determinants. Of these patients, 78 % were found to have no other gastrointestinal pathogen identified in the stool, which strongly suggests a role for Campylobacter concisus in the aetiology of gastroenteritis in these patients. These results emphasize the need for diagnostic laboratories to employ identification protocols for emerging Campylobacter species. Clinical follow-up in patients presenting with high levels of Campylobacter concisus in the intestinal tract is needed, given that it has been associated with more chronic sequelae.
Fulltext Multiple Genome Sequences of Helicobacter pylori Strains of Diverse Disease and Antibiotic Resistance Backgrounds from Malaysia

Rehvathy V, Tan MH, Gunaletchumy SP, Teh X, Wang S, Baybayan P, et al.

Genome Announc, 2013;1(5).
PMID: 24051312 DOI: 10.1128/genomeA.00687-13

Helicobacter pylori causes human gastroduodenal diseases, including chronic gastritis and peptic ulcer disease. It is also a major microbial risk factor for the development of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Twenty-one strains with different ethnicity, disease, and antimicrobial susceptibility backgrounds were sequenced by use of Illumina HiSeq and PacBio RS platforms.
Genetic variants involved in innate immunity modulate the risk of inflammatory bowel diseases in an understudied Malaysian population

Luu LDW, Popple G, Tsang SPW, Vinasco K, Hilmi I, Ng RT, et al.

J Gastroenterol Hepatol, 2022 Feb;37(2):342-351.
PMID: 34888949 DOI: 10.1111/jgh.15752

BACKGROUND AND AIM: Inflammatory bowel diseases (IBD) are chronic gastrointestinal inflammatory conditions comprising two major subtypes: Crohn's disease (CD) and ulcerative colitis (UC). The incidence of IBD is increasing in Asian countries including Malaysia. The aim of this study was to determine whether 32 single nucleotide polymorphisms (SNPs) strongly associated with IBD from genome-wide association studies, performed mainly in Caucasian populations, are associated with IBD in a Malaysian population, correlating these findings with local and systemic inflammation.
METHODS: Selected SNPs were investigated in a Malaysian cohort comprising 36 IBD patients and 75 controls using customized matrix-assisted laser desorption ionization time-of-flight genotyping. Local mRNA and/or systemic protein levels of IL-10, IL-12, IL-22, IL-23, and TNF-α were measured in these same subjects.
RESULTS: ATG16L2 rs11235667 and LINC00824 rs6651252 was significantly associated with increased CD risk while IL12B rs56167332 was a significant protective factor. Three SNPs (SBNO2 rs2024092, CARD9 rs10781499, and rs17085007 between GPR12-USP12) were significantly associated with increased UC risk while NKX2-3 rs4409764 was a significant protective factor. After adjusting for age, gender, and ethnicity, SBNO2 rs2024092, ATG16L2 rs11235667, CARD9 rs10781499, and LINC00824 rs6651252 remained associated with IBD. Interestingly, the risk alleles of IL10 rs3024505, CARD9 rs1078149, and IL12 rs6556412 were associated with higher levels of IL-10, IL-22, and IL-23 in these same subjects, respectively.
CONCLUSIONS: This study identified eight SNPs associated with IBD and/or its subtypes in the Malaysia population, significantly advancing our understanding of the genetic contribution to IBD in this understudied population. Three of these SNPs modulated relevant cytokine levels and thus, may directly contribute to IBD pathogenesis.
Draft genome sequences of Helicobacter pylori isolates from Malaysia, cultured from patients with functional dyspepsia and gastric cancer

Gunaletchumy SP, Teh X, Khosravi Y, Ramli NS, Chua EG, Kavitha T, et al.

J Bacteriol, 2012 Oct;194(20):5695-6.
PMID: 23012278

Helicobacter pylori is the main bacterial causative agent of gastroduodenal disorders and a risk factor for gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. The draft genomes of 10 closely related H. pylori isolates from the multiracial Malaysian population will provide an insight into the genetic diversity of isolates in Southeast Asia. These isolates were cultured from gastric biopsy samples from patients with functional dyspepsia and gastric cancer. The availability of this genomic information will provide an opportunity for examining the evolution and population structure of H. pylori isolates from Southeast Asia, where the East meets the West.