Helicobacter pylori infection aggravates diet-induced nonalcoholic fatty liver in mice

Diet-pathobiont interplay in health and inflammatory bowel disease

The intestinal microbiota plays a crucial role in maintaining host health by participating in various beneficial functions. However, under certain conditions, it can contribute to the development of inflammatory bowel disease (IBD) and other chronic inflammatory conditions. Importantly, not all commensal microbiota members are drivers of inflammation. A specific subset of commensal bacteria, known as pathobionts, can exhibit pathogenic potential under specific circumstances. Their inflammatory potential is modulated by several factors, including the host's genetic background and the surrounding microbiota. Furthermore, diet has emerged as a critical factor influencing the gut microbiota, with some studies highlighting its role in modulating pathobionts. This review will delve into the role played by pathobionts in chronic intestinal inflammation, in both mouse models as well as in humans, with a focus on the interplay between dietary factors and pathobiont members of the intestinal microbiota. Understanding the complex relationships between diet, pathobionts, and chronic inflammation could pave the way for diet-based therapeutic strategies aimed at managing chronic inflammatory conditions.

Potential mechanisms and therapeutic prospects of the association between Helicobacter pylori infection and metabolic dysfunction-associated steatohepatitis

Helicobacter pylori (H. pylori) infection is a known inducer of various gastrointestinal diseases, including gastritis, gastric ulcers, and gastric cancer. However, in recent years, research on the potential association between H. pylori infection and metabolic dysfunction-associated steatohepatitis (MASH) has been scarce. This large-scale multicenter study, covering more than 360 hospitals across 26 medical systems in the United States, systematically evaluated the association between H. pylori infection and MASH. This paper reviews the innovative aspects of this study, discusses its significance in the current research field of H. pylori and liver diseases, analyzes potential molecular mechanisms, and suggests future research directions and therapeutic prospects.

Helicobacter pylori cagA/vacAs1-m1 strain is associated with high risk of fibrosis in metabolic-dysfunction-associated steatotic liver disease

INTRODUCTION AND OBJECTIVES

Recent studies have suggested an association between H. pylori and metabolic dysfunction associated steatotic liver disease (MASLD). We aim to evaluate the association of H. pylori virulence genes with non-invasive markers of liver injury and fibrosis in MASLD subjects.

PATIENTS AND METHODS

A total of 362 dyspeptic patients who underwent gastroscopy were selected. Biochemical, clinical parameters, ultrasound, FIB-4 score, liver stiffness measurement (LSM) by vibration-controlled transient elastography (VCTE), gastric biopsies, and H. pylori virulence genes (cagA, vacA) were evaluated.

RESULTS

A cohort comprised of 61 % women and 39 % men with a median age of 52 (40-60) years. MASLD was observed in 42 %, and H. pylori-positive in 45 %. No differences were observed regarding H. pylori status at co-morbid metabolic conditions. In MASLD cohort, H. pylori-positive was associated with higher AST, ALT, FIB-4 and LSM. Indeed, carriers of cagA/vacA-s1/m1-positive allelic combination were associated with higher AST, ALT, FIB-4 and LSM but not cagA/vacA-s1/m1-negative. The OR for high-risk of significant/advanced- fibrosis by VCTE (≥8 kPa) with H. pylori-positive was 2.56 (95 % CI, 1.2-5.75) and for cagA/vacA-s1/-m1-positive allelic carriers was 4.01 (95 % CI, 1.38-11.56), but non-significant association in cagA/vacA-s1/-m1-negative. After adjusting for age, gender, diabetes, BMI and hypertension the OR for VCTE ≥8 kPa with H. pylori-positive was 2.43 (95 % CI, 1.88-12.44), and cagA/vacA-s1/m1-positive allelic carriers was 4.06 (95 % CI, 1.22-14.49).

CONCLUSIONS

In our cohort of functional dyspepsia (FD) patients with MASLD, H. pylori was associated with non-invasive markers of liver injury and fibrosis. Carriers of cagA/vacA-s1/m1-positive allelic combination showed an independent risk of significant/advanced fibrosis by VCTE.

The interplay between Helicobacter pylori infection and rs738409 PNPLA3 in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Recent studies have suggested an association between H. pylori and metabolic-disfunction associated fatty liver disease (MASLD). However, epidemiologic studies have yielded inconsistent results. We aim to evaluate the association of H. pylori and G-allele PNPLA3 in MASLD diagnosis, and markers of severity.

METHODS

A multi-center cross-sectional study was conducted. A total 224 functional dyspepsia (FD) patients cohort who underwent gastroscopy was selected. Biochemical, clinical parameters, ultrasound, FIB-4 score, LSM by VCTE, gastric biopsies, H. pylori status, and rs738409 PNPLA3 were evaluated. A second retrospective cohort of 86 patients with biopsy-proven MASLD who underwent gastroscopy with gastric biopsies was analyzed.

RESULTS

In the FD cohort MASLD was observed in 52%, and H. pylori-positive in 51%. H. pylori infection was associated with MASLD prevalence, but in multivariate analyses adjusted for G-allele PNPLA3, it became not significant. Then in MASLD-only dyspeptic cohort, H. pylori infection was significantly linked to elevated serum AST levels and increased liver stiffness measurements, suggesting a potential role in liver injury and fibrosis. Histopathological analysis in biopsy-proven MASLD patients further supported these findings, showing a significant association between H. pylori infection and increased NAS score, fibrosis stage, and prevalence of MASH. Notably, the combination of H. pylori infection and G-allele PNPLA3 appeared to exacerbate MASLD severity beyond individual effects.

CONCLUSIONS

Our results suggest that H. pylori infection may play a role in the progression of liver injury and fibrosis in patients with MASLD, especially in those with specific genetic predispositions.

Helicobacter pylori infection exacerbates metabolic dysfunction-associated steatotic liver disease through lipid metabolic pathways: a transcriptomic study

BACKGROUND

The relationship between Helicobacter pylori (H. pylori) infection and metabolic dysfunction-associated steatotic liver disease (MASLD) has attracted increased clinical attention. However, most of those current studies involve cross-sectional studies and meta-analyses, and experimental mechanistic exploration still needs to be improved. This study aimed to investigate the mechanisms by which H. pylori impacts MASLD.

METHODS

We established two H. pylori-infected (Cag A positive and Cag A negative) mouse models with 16 weeks of chow diet (CD) or high-fat diet (HFD) feeding. Body weight, liver triglyceride, blood glucose, serum biochemical parameters, inflammatory factors, and insulin resistance were measured, and histological analysis of liver tissues was performed. Mouse livers were subjected to transcriptome RNA sequencing analysis.

RESULTS

Although H. pylori infection could not significantly affect serum inflammatory factor levels and serum biochemical parameters in mice, serum insulin and homeostatic model assessment for insulin resistance levels increased in CD mode. In contrast, H. pylori Cag A + infection significantly aggravated hepatic pathological steatosis induced by HFD and elevated serum inflammatory factors and lipid metabolism parameters. Hepatic transcriptomic analysis in the CD groups revealed 767 differentially expressed genes (DEGs) in the H. pylori Cag A + infected group and 1473 DEGs in the H. pylori Cag A- infected group, and the "nonalcoholic fatty liver disease" pathway was significantly enriched in KEGG analysis. There were 578 DEGs in H. pylori Cag A + infection combined with the HFD feeding group and 820 DEGs in the H. pylori Cag A- infected group. DEGs in the HFD groups were significantly enriched in "fatty acid degradation" and "PPAR pathway." Exploring the effect of different Cag A statuses on mouse liver revealed that fatty acid binding protein 5 was differentially expressed in Cag A- H. pylori. DEG enrichment pathways were concentrated in the "PPAR pathway" and "fatty acid degradation."

CONCLUSIONS

Clinicians are expected to comprehend the impact of H. pylori on MASLD and better understand and manage MASLD. H. pylori infection may exacerbate the development of MASLD by regulating hepatic lipid metabolism, and the H. pylori virulence factor Cag A plays a vital role in this regulation.

Helicobacter pylori components increase the severity of metabolic syndrome and its hepatic manifestations induced by a high fat diet

The metabolic syndrome, often accompanied by hepatic manifestations, is a high-risk factor for developing cardiovascular disease. Patients with metabolic dysfunction associated with steatohepatic disease (MASDL) are at significant risk of developing coronary artery disease. Atherosclerosis is a systemic inflammatory disorder in which several factors, including dietary or infectious factors, can cause an inflammatory response. Helicobacter pylori (HP) bacteria have been implicated in the progression of proatherogenic vascular endothelial lesions, moreover, our previous study in an experimental in vivo model of Cavia porcellus showed that HP components and high-fat substances acted synergistically in promoting vascular endothelial inflammation, leading to an early onset of a proatherogenic environment. In the present study, our goal was to determine the contribution of HP components to the development of hepatic manifestations of metabolic syndrome in an experimental model. Our results showed that HP infection in animals exposed to a high-fat diet increased oxidative stress and lipid peroxidation, followed by endothelial lipid deposition, impaired endothelial apoptosis, cell lysis, and increased vascular stiffness. Finally, histopathological analysis of liver tissue showed signs of MASLD development in HP-infected animals fed a high-fat diet.

An update: is there a relationship between H. pylori infection and nonalcoholic fatty liver disease? why is this subject of interest?

Helicobacter pylori (H. pylori) infection is thought to impact various extragastric diseases, including nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease. Meanwhile, the pathogenesis of NAFLD needs further research, and effective treatment for this disease remains elusive. In this mini-review, we enumerate and ponder on the evidence demonstrating an association between H. pylori infection and NAFLD. Primarily, we delve into high-quality meta-analyses and clinical randomized controlled trials focusing on the association studies between the two. We also discuss clinical studies that present opposite conclusions. In addition, we propose a mechanism through which H. pylori infection aggravates NAFLD: inflammatory cytokines and adipocytokines, insulin resistance, lipid metabolism, intestinal barrier and microbiota, H. pylori outer membrane vesicles and H. pylori-infected cell-extracellular vesicles. This mini-review aims to further explore NAFLD pathogenesis and extragastric disease mechanisms caused by H. pylori infection.

The Effects of Helicobacter pylori-Derived Outer Membrane Vesicles on Hepatic Stellate Cell Activation and Liver Fibrosis In Vitro

INTRODUCTION

Helicobacter pylori is a prevalent pathogenic bacterium that resides in the human stomach. Outer membrane vesicles (OMVs) are known as nanosized cargos released by H. pylori, which have been proposed to have a key role in disease progression, pathogenesis, and modulation of the immune system. There are multiple evidences for the role of H. pylori in extragastroduodenal illnesses especially liver-related disorders. However, the precise mechanism of H. pylori extragastroduodenal pathogenesis still remains unclear. In the current study, we aimed to determine the impact of H. pylori-isolated OMVs on hepatic stellate cell (HSC) activation and expression of liver fibrosis markers.

MATERIALS AND METHODS

Five H. pylori clinical strains with different genotype profiles were used. Helicobacter pylori OMVs were isolated using ultracentrifugation and were analyzed by scanning electron microscopy (SEM) and dynamic light scattering (DLS). Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis was applied to determine protein components of H. pylori-derived OMVs. Cell viability of LX-2 human hepatic stellate cell line exposed to OMVs was measured by MTT assay. LX-2 cells were treated with OMVs for 24 h. The gene expression of α-SMA, E-cadherin, vimentin, snail, and β-catenin was analyzed using quantitative real-time PCR. The protein expression of α-SMA, as a well-studied profibrotic marker, was evaluated with immunocytochemistry.

RESULTS

Our results showed that H. pylori strains released round shape nanovesicles ranging from 50 to 500 nm. Totally, 112 various proteins were identified in OMVs by proteomic analysis. The isolated OMVs were negative for both CagA and VacA virulence factors. Treatment of HSCs with H. pylori-derived OMVs significantly increased the expression of fibrosis markers.

CONCLUSIONS

In conclusion, the present study demonstrated that H. pylori-derived OMVs could promote HSC activation and induce the expression of hepatic fibrosis markers. Further research is required to elucidate the definite role of H. pylori-derived OMVs in liver fibrosis and liver-associated disorders.

Non-alcoholic fatty liver disease is not independently associated with Helicobacter pylori in a central European screening cohort

BACKGROUND

The association between Helicobacter pylori (Hp) infection and non-alcoholic fatty liver disease (NAFLD) is subject of a contentious debate. Data mainly stem from Asian cohorts whereas European data are scarce. We, therefore, investigated an Austrian colorectal cancer screening cohort for an association between Hp and NAFLD.

METHODS

In total, 5338 consecutive participants undergoing screening colonoscopy at a single center in Austria were evaluated in this cross-sectional study. The primary risk factor was being Hp negative or positive. The primary endpoint was the presence of NAFLD defined by ultrasound (NAFLD; primary endpoint). Uni- and multivariable logistic regression models were fitted to obtain odds ratios (OR) and 95% confidence intervals (95%CI). Finally, this association was analyzed in a subgroup of 1128 patients in whom NAFLD was diagnosed by transient elastography (TE, secondary endpoint).

RESULTS

NAFLD prevalence defined by ultrasound did not differ between Hp positive (48%) and negative patients (45%, P=0.097). Accordingly, in uni- (OR 1.12 95% CI 0.98-1.29; P=0.098) and multivariable analysis adjusting for different risk factors (aOR 0.96 95%CI 0.82-1.13; P=0.601) no independent association was found. On subgroup analysis, NAFLD diagnosed by TE was more prevalent in the Hp positive compared to the Hp negative group (49% vs. 38%, P=0.004) and these patients also had higher steatosis grades. However, after adjustment for risk factors, no independent association between Hp positivity and NAFLD diagnosed by TE (aOR 1.26 95%CI 0.89-1.78; P=0.194) was confirmed.

CONCLUSIONS

In this Central European cohort, Hp-positivity was not associated with the diagnosis of NAFLD. Although Hp positive patients seem to be more likely to have a concomitant NAFLD diagnosis, this association might rather relate to a cardiometabolic risk phenotype than causality.

No evidence for a causal link between Helicobacter pylori infection and nonalcoholic fatty liver disease: A bidirectional Mendelian randomization study

Although clinical studies have shown the possible relationship between Helicobacter pylori (H. pylori) infection and the development of nonalcoholic fatty liver disease (NAFLD), their causal relationship is still unknown. This bidirectional Mendelian randomization (MR) study aimed to investigate the causal link between H. pylori infection and NAFLD. Two previously reported genetic variants SNPs rs10004195 and rs368433 were used as the instrumental variables (IVs) of H. pylori infection. The genetic variants of NAFLD were extracted from the largest genome-wide association study (GWAS) summary data with 1,483 cases and 17,781 controls. The exposure and outcome data were obtained from the publicly available GWAS dataset. Then, a bidirectional MR was carried out to evaluate the causal relationship between H. pylori infection and NAFLD. In addition, the GWAS data were also collected to explore the causal relationship between H. pylori infection and relevant clinical traits of NAFLD, including triglycerides, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG), and body mass index (BMI). Genetically predicted H. pylori infection showed no association with NAFLD both in FinnGen GWAS (OR, 1.048; 95% CI, 0.778-1.411; value of p = 0.759) and the GWAS conducted by Anstee (OR, 0.775; 95% CI, 0.475-1.265; value of p = 0.308). An inverse MR showed no causal effect of NAFLD on H. pylori infection (OR,0.978;95% CI, 0.909-1.052; value of p = 0.543). No significant associations were observed between H. pylori infection and the levels of triglycerides, LDL-C, HDL-C, or FBG, while H. pylori infection was associated with an increase in BMI. These results indicated that there was no genetic evidence for a causal link between H. pylori and NAFLD, suggesting that the eradication or prevention of H. pylori infection might not benefit NAFLD and vice versa.

The effect of lipid metabolism regulator anthocyanins from Aronia melanocarpa on 3T3-L1 preadipocytes and C57BL/6 mice via activating AMPK signaling and gut microbiota

This study investigated lipid metabolism regulation by anthocyanins from Aronia melanocarpa (AAM) in 3T3-L1 preadipocytes and high fat diet (HFD) mice. Ultra-performance liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry analysis identified the constituents of AAM, which decreased lipid content and inflammation in 3T3-L1 cells without cytotoxicity. Meanwhile, taking normal diet and orlistat mice as references, AAM supplementation improved blood lipid levels and adipocyte degeneration, promoted beneficial gut microbial growth, and maintained lipid metabolism in HFD mice. Furthermore, AAM activated the AMP-activated protein kinase (AMPK) signaling pathway, accompanied by the regulation of adipogenic transcription factors and their target genes in vitro and in vivo. Collectively, our data demonstrated that AAM exhibits anti-adipogenic activities that were partially mediated by the AMPK pathway and gut microbiota regulation. This study provides new insight into the regulation of lipid metabolism by AAM and suggests that AAM has potential therapeutic effects on hyperlipidemia.

Modeling Diet-Induced Metabolic Syndrome in Rodents

Standardized animal models represent one of the most valuable tools available to understand the mechanism underlying the metabolic syndrome (MetS) and to seek for new therapeutic strategies. However, there is considerable variability in the studies conducted with this essential purpose. This review presents an updated discussion of the most recent studies using diverse experimental conditions to induce MetS in rodents with unbalanced diets, discusses the key findings in metabolic outcomes, and critically evaluates what we have been learned from them and how to advance in the field. The study includes scientific reports sourced from the Web of Science and PubMed databases, published between January 2013 and June 2020, which used hypercaloric diets to induce metabolic disorders, and address the impact of the diet on metabolic parameters. The collected data are used as support to discuss variables such as sex, species, and age of the animals, the most favorable type of diet, and the ideal diet length to generate metabolic changes. The experimental characteristics propose herein improve the performance of a preclinical model that resembles the human MetS and will guide researchers to investigate new therapeutic alternatives with confidence and higher translational validity.

Active Helicobacter pylori Infection is Independently Associated with Nonalcoholic Steatohepatitis in Morbidly Obese Patients

Nonalcoholic fatty liver disease (NAFLD) emerges as an important global burden and Helicobacter pylori infection (Hp-I) has been suggested as a risk factor of NAFLD, although controversy exists. This retrospective study aimed to investigate a potential impact of active Hp-I on NAFLD severity in morbidly obese patients, subjected to bariatric surgery and gastric biopsy for documentation of Hp-I. Of 64 eligible participants, 15 (23.4%) were diagnosed with active Hp-I, showing higher rates of nonalcoholic steatohepatitis (NASH) than those without Hp-I (86.7% vs. 26.5%, respectively; p < 0.001). Concerning histological lesions, steatosis grade (p = 0.027), ballooning (p < 0.001), lobular inflammation (p = 0.003), and fibrosis stage (p < 0.001) were also more severe in Hp-I positive patients. Likewise, liver function tests, insulin resistance, dyslipidemia, and arterial hypertension were significantly higher in Hp-I positive patients. Hp-I was independently positively associated with NASH (beta = 3.27; p = 0.002), severe NASH (beta = 2.37; p = 0.018), and the presence of fibrosis (beta = 3.86; p = 0.001) in a binary regression model, after adjustment for potential confounders. In conclusion, active Hp-Ι was independently associated with NASH and fibrosis, findings offering potential clinical implication.

Microbiota and nonalcoholic fatty liver disease: promising prospects for clinical interventions?

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is becoming the most important cause of chronic liver disease in Western countries but no pharmacological therapy is currently available. Growing evidence suggests that the microbiota plays a role in the occurrence and evolution of this disease, namely through the production of bioactive metabolites.

RECENT FINDINGS

Omics technologies (metagenomic, metabolomic, and phenomic data) allow providing a robust prediction of steatosis. More than just correlations, causative effects of certain bacterial metabolites have been evidenced in vitro and in rodent models. Butyrate has been shown to be a potent metabolic and inflammatory modulator in the liver. Several aromatic amino-acids such as phenylacetic acid, imidazole propionate, and 3-(4-hydroxyphenyl)lactate have been identified as potential inducers of steatosis and hepatic inflammation, whereas indolic compounds (indole and indole-3-acetate) seem to preserve liver integrity. Current clinical trials aim at evaluating the efficacy of novel approaches (functional foods, prebiotic and probiotics, and fecal microbial transplants).

SUMMARY

The microbiota brings new hopes in the management of nonalcoholic fatty liver diseases, including nonalcoholic steatohepatitis. Adequate intervention studies in targeted patients are needed to unravel the relevance of such approaches in the management of those liver diseases.

Review: Helicobacter pylori and extragastric diseases

In the last year, many studies have demonstrated a potential role of Helicobacter pylori in the pathogenic mechanisms of different extragastric diseases. While the role of H pylori in idiopathic thrombocytopenic purpura, idiopathic iron deficiency anemia, and vitamin B12 deficiency has already been demonstrated, there is growing evidence of other related conditions, especially cardiovascular, metabolic, and neurologic disorders, including neurodegenerative diseases. A summary of the results of the most relevant studies published over the last year on this attractive topic is presented in this review.

Association between Helicobacter pylori infection and nonalcoholic fatty liver disease: a systemic review and meta-analysis

Although clinical studies have shown possible links of Helicobacter pylori infection with the development of nonalcoholic fatty liver disease (NAFLD), the results remain controversial. The aim of this meta-analysis is to investigate the association between H. pylori infection and NAFLD. A comprehensive search of relevant studies was performed up to November 2018. Data on H. pylori infection in NAFLD patients and controls were extracted. Odds ratio (OR) and 95% confidence interval (CI) were calculated using a random-effects model. Twelve studies involving 27 400 NAFLD patients and 60 347 controls were included. The pooled overall OR of H. pylori infection in NAFLD patients compared with controls was 1.36 (95% CI: 1.22-1.53, I=89.6%, P=0.000). Meta-regression and subgroup analysis showed that the sample size and the case-control ratio may have accounted for some of the heterogeneity. When stratified by publication year, the diagnostic method used for H. pylori, and Newcastle-Ottawa Scale scores, the OR remained significant. However, possible publication bias was observed. Of the 12 studies, six had carried out multivariable analysis after adjusting for potential confounders. The pooled results from these studies still indicated a higher risk of NAFLD in patients infected with H. pylori (OR=1.17, 95% CI: 1.01-1.36, I=72.4%, P=0.003). There is a 36% increased risk of NAFLD in patients with H. pylori infection. Further studies are warranted to investigate whether eradication of H. pylori is useful in the prevention and treatment of NAFLD.