Helicobacter pylori Infection—A Risk Factor for Irritable Bowel Syndrome? An Updated Systematic Review and Meta-Analysis

Risk factors for developing irritable bowel syndrome: systematic umbrella review of reviews

BACKGROUND

Irritable bowel syndrome (IBS) is a debilitating disorder affecting 4-9% of the global population. It is a multifaceted disorder with complex and varied causes. This review aims to consolidate the evidence regarding IBS risk factors by examining existing systematic reviews and meta-analyses, covering potential genetic, immunological, psychological, and dietary causes.

METHODS

Systematic literature searches were conducted in MEDLINE, Embase and Cochrane library databases. Study selection and data extraction were conducted independently by four authors, with discrepancies resolved by consensus with a senior author. Systematic reviews examining risk factors of IBS development were eligible for review. Results were narratively synthesized. Quality of reviews were analysed using AMSTAR 2, and evidence were appraised using GRADE methodology.

RESULTS

A total of 69 systematic reviews were included in this study. Most reviews were of "critically low" quality, while the remaining were "low" quality. Common shortcomings included the absence of a list of excluded studies with justifications for their exclusion and inadequate consideration of the risk of bias in individual studies. Eight major categories of risk factors for IBS identified were as follows: dietary, genetic, environmental, psychological, gut microbiome, socio-economic, physiological, and pathological, albeit overlaps exist. The most frequently reported risk factors for IBS development were female gender and anxiety disorders, with overall GRADE evaluation of "low"; depression and gastroenteritis, with overall GRADE evaluation of "moderate".

CONCLUSIONS

Clinical practice should prioritize recognition of these risk factors. Future reviews should improve their reporting of results based on the PRISMA guidelines, to enhance the quality of research in this field.

PROTOCOL REGISTRATION

PROSPERO CRD42023493739.

Selenium deficiency induces irritable bowel syndrome: Analysis of UK Biobank data and experimental studies in mice

Irritable bowel syndrome (IBS) patients exhibit significantly lower levels of serum selenium (Se) compared to healthy controls. This study integrates a prospective cohort analysis and animal experiments to investigate Se deficiency as a potential risk factor for IBS. Using data from the UK Biobank, a longitudinal analysis was conducted to explore the associations between dietary Se intake and the risk of incident IBS. In animal study, C57BL/6 mice were fed diets with normal (0.2 ppm) or low (0.02 ppm) Se levels to assess the impacts of Se deficiency on IBS symptoms. Furthermore, we performed 16 S rRNA sequencing, untargeted colonic fecal metabolomics analysis, and colon transcriptome profiling to uncover the regulatory mechanisms underlying Se deficiency-induced IBS. The analysis of UK Biobank data revealed a significant correlation between low dietary Se levels and an increased incidence of IBS. In the experimental study, a low Se diet induced IBS symptoms, evidenced by elevated abdominal withdrawal reflex scores, colon inflammation, and severe pathological damage to the colon. Additionally, the low Se diet caused disturbances in gut microbiota, characterized by an increase in Faecalibaculum and Helicobacter, and a decrease in Bifidobacterium and Akkermansia. Combined colonic fecal metabolomics and colon transcriptome analysis indicated that Se deficiency might trigger IBS through disruptions in pathways related to "bile excretion", "steroid hormone biosynthesis", "arachidonic acid metabolism", and "drug metabolism-cytochrome P450". These findings underscore the significant adverse effects of Se deficiency on IBS and suggest that Se supplementation should be considered for IBS patients.

No evidence for a causal link between Helicobacter pylori infection and Irritable bowel syndrome: a Mendelian randomization study

Background

Although clinical studies have revealed a potential link between Helicobacter pylori (H. pylori) infection and irritable bowel syndrome (IBS), the causal relationship between them remains unknown. The objective of this study was to investigate whether H. pylori infection is causally associated with IBS.

Method

A two-sample Mendelian randomization (MR) analysis using the inverse variance weighted (IVW), weighted mode, weighted median and MR-Egger methods was performed. We used the publicly available summary statistics data sets of genome-wide association studies (GWAS) for H. pylori infection in individuals of European descent (case = 1,058, control = 3,625) as the exposure and a GWAS for non-cancer illness code self-reported: IBS (case = 10,939, control = 451,994) as the outcome.

Results

We selected 10 single nucleotide polymorphisms at genome-wide significance from GWASs on H. pylori infection as the instrumental variables. The IVW, weighted mode, weighted median and MR-Egger methods all provided consistent evidence that suggests a lack of causal association between H. pylori and IBS. MR-Egger regression revealed that directional pleiotropy was unlikely to be biasing the result (intercept = -1e-04; P = 0.831). Cochran's Q-test and the funnel plot indicated no evidence of heterogeneity and asymmetry, indicating no directional pleiotropy.

Conclusion

The results of MR analysis support that H. pylori infection may not be causally associated with an increased risk of IBS.

Systematic review and meta-analysis of calculating degree of comorbidity of irritable bowel syndrome with migraine

BACKGROUND

Irritable bowel syndrome (IBS) and migraines are often comorbid each other. These disorders are likely to be bidirectionally linked through the gut-brain axis and share several underlying mechanisms including central nervous system sensitization. However, quantitative analysis of comorbidity was not reported enough. The aim of this systematic review and meta-analysis was to calculate the present degree of comorbidity of these two disorders.

METHODS

A literature search was performed searching for articles describing IBS or migraine patients with the same inverse comorbidity. Pooled odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (CIs) were then extracted. The total effect estimates were determined and presented by random effect forest plots for the group of articles with IBS patients with migraine and the group of articles on migraine sufferers with comorbid IBS separately. The average results of these plots were compared.

RESULTS

The literature search resulted in initial 358 articles and final 22 articles for the meta-analysis. The total OR values obtained were 2.09 [1.79 - 2.43] in IBS with comorbid migraine or headache, 2.51 [1.76 - 3.58] for migraineurs with comorbid IBS and an overall HR of 1 .62 [1.29 - 2.03] was found for cohort studies of migraine sufferers with comorbid IBS. A similar expression of a selection of other comorbidities was found in IBS and migraine patients, especially for depression and fibromyalgia a strong similarity was found in their expression rate.

CONCLUSIONS

This systematic review with meta-analysis was the first to combine data on IBS patients with comorbid migraine and migraineurs with comorbid IBS. The fact that closely related existential rates were observed between these two groups should be used as motivation for future research to further investigate these disorders for why this similarity occurs. Mechanisms involved in central hypersensitivity such as genetic risk factors, mitochondrial dysfunction and microbiota are particularly good candidates. Experimental designs in which therapeutic methods for these conditions can be exchanged or combined may also lead to the discovery of more efficient treatment methods.

Efficacy and Safety of Polaprezinc-Based Therapy versus the Standard Triple Therapy for Helicobacter pylori Eradication: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Helicobacter pylori (H. pylori) is the most prevalent etiology of gastritis worldwide. H. pylori management depends mainly on antibiotics, especially the triple therapy formed of clarithromycin, amoxicillin, and proton pump inhibitors. Lately, many antibiotic-resistant strains have emerged, leading to a decrease in the eradication rates of H. pylori. Polaprezinc (PZN), a mucosal protective zinc-L-carnosine complex, may be a non-antibiotic agent to treat H. pylori without the risk of resistance. We performed a systematic review and meta-analysis to evaluate the efficacy and safety of a PZN-based regimen for the eradication of H. pylori. This study used a systematic review and meta-analysis synthesizing randomized controlled trials (RCTs) from WOS, SCOPUS, EMBASE, PubMed, and Google Scholar until 25 July 2022. We used the odds ratio (OR) for dichotomous outcomes presented with the corresponding 95% confidence interval (CI). We registered our protocol in PROSPERO with ID: CRD42022349231. We included 3 trials with a total of 396 participants who were randomized to either PZN plus triple therapy (n = 199) or triple therapy alone (control) (n = 197). Pooled OR found a statistical difference favoring the PZN arm in the intention to treat and per protocol H. pylori eradication rates (OR: 2.01 with 95% CI [1.27, 3.21], p = 0.003) and (OR: 2.65 with 95% CI [1.55, 4.54], p = 0.0004), respectively. We found no statistical difference between the two groups regarding the total adverse events (OR: 1.06 with 95% CI [0.55, 2.06], p = 0.85). PZN, when added to the triple therapy, yielded a better effect concerning the eradication rates of H. pylori with no difference in adverse event rates, and thus can be considered a valuable adjuvant for the management of H. pylori. However, the evidence is still scarce, and larger trials are needed to confirm or refute our findings.