An Overview of Autophagy in Helicobacter pylori Infection and Related Gastric Cancer

The role of miRNAs in pathogenesis, diagnosis, and therapy of Helicobacter pylori infection, gastric cancer-causing bacteria: Special highlights on nanotechnology-based therapy

Helicobacter pylori (H. pylori) infection and consequent inflammation in the stomach are widely recognized as major contributors to gastric cancer (GC) development. Recent investigations have placed considerable emphasis on uncovering the controlling influence of small RNA molecules known as microRNAs (miRNAs) in H. pylori-related diseases, particularly gastric cancer. This review aims to offer a comprehensive understanding of the intricate roles fulfilled by miRNAs in conditions associated with H. pylori infection. Exploring miRNA biogenesis pathways reveals their intimate connection with H. pylori infection, shedding light on the underlying molecular mechanisms driving disease progression and identifying potential intervention targets. An examination of epidemiological data surrounding H. pylori infection, including prevalence, risk factors, and transmission routes, underscores the imperative for preventive measures and targeted interventions. Incorporating insights from miRNA-related research into these strategies holds promise for enhancing their efficacy in controlling H. pylori spread. The symptoms, underlying mechanisms, and virulent characteristics of the bacteria highlight the intricate relationship between H. pylori and host cells, influencing the course of diseases. Within this complex web, miRNAs play pivotal roles, regulating various facets of H. pylori's development. MicroRNAs intricately involved in directing the immune response against H. pylori infection serve as key players in molding host defense mechanisms and impacting the bacterium's evasion tactics. Utilizing this knowledge holds the potential to drive forward groundbreaking therapeutic strategies. The diagnostic and prognostic capabilities of miRNAs in H. pylori infection highlight their effectiveness as non-invasive indicators for identifying diseases and evaluating risk. Integration of miRNA signatures into diagnostic algorithms holds promise for enhancing early detection and management of H. pylori-related diseases. MiRNA-based therapeutics offer a promising avenue for combatting H. pylori-induced gastric cancer, targeting specific molecular pathways implicated in tumorigenesis. H. pylori infection induces dysregulation of several miRNAs that contribute to antibiotic resistance, inflammation, and gastric cancer progression, including downregulation of tumor-suppressive miR-7 and miR-153 and upregulation of oncogenic miR-671-5p and miR-155-5p, which promote carcinogenesis and inflammation. Additionally, H. pylori manipulates host immune responses by upregulating miRNAs such as let-7f-5p, let-7i-5p, miR-146b-5p, and miR-185-5p that suppress HLA class II expression and antigen presentation, facilitating immune evasion and chronic gastritis that predispose to gastric cancer. Future research endeavors should focus on refining these therapeutic modalities and identifying novel targets to optimize clinical outcomes. By elucidating the multifaceted roles of miRNAs in H. pylori infection, this review provides invaluable insights into disease pathogenesis, diagnostics, and therapeutics, and the role of some nanoparticles in combating the H. pylori infection. Continued research efforts are imperative for translating these insights into clinical practice and addressing the global burden of H. pylori-related diseases.

Non-coding RNAs as potential mediators of resistance to lung cancer immunotherapy and chemotherapy

Lung cancer is a common cause of cancer-related death globally. The majority of lung cancer patients initially benefit from chemotherapy and immunotherapy. However, as the treatment cycle progresses and the disease evolves, the emergence of acquired resistance leads to treatment failure. Many researches have shown that non-coding RNAs (ncRNAs) not only influence lung cancer progression but also act as potential mediators of immunotherapy and chemotherapy resistance in lung cancer, mediating drug resistance by regulating multiple targets and pathways. In addition, the regulation of immune response by ncRNAs is dualistic, forming a microenvironment for inhibits/promotes immune escape through changes in the expression of immune checkpoints. The aim of this review is to understand the effects of ncRNAs on the occurrence and development of lung cancer, focusing on the role of ncRNAs in regulating drug resistance of lung cancer.

A Comparative Analysis of the Clinical Application of a Novel Helicobacter pylori Serum Antibody Typing Test and the 13C-Urea Breath Test

Background/Objectives: To compare and analyze the application of a Helicobacter pylori (H. pylori, Hp) serum antibody typing test (Hp-sATT) and the 13C-urea breath test (13C-UBT) in the diagnosis of Hp infection against an empirical therapy background. Methods: The detection of Hp-sATT using a combination of the quantum dot immunofluorescence method and the 13C-UBT was carried out in 237 patients who visited the Department of Gastroenterology at Beijing Tsinghua Changgung Hospital. The diagnostic consistency and correlation with gastric lesions of the two detection methods were analyzed by integrating the detection results, clinical information, and special staining of Hp in histopathological tissues (SS-Hp). Results: For the 13C-UBT, 104 (43.88%) cases were positive and 133 (56.12%) were negative. Positive results were found in 127 (53.59%) patients by using the Hp-sATT, with 67 (28.27%) cases of Type I Hp infection and 60 (25.32%) cases of Type II Hp infection. The consistency analysis between the Hp-sATT and 13C-UBT for all the patients showed a Kappa value of 0.339 (p < 0.001); the consistency analysis between the Hp-sATT and the 127 patients with SS-Hp showed a Kappa value of 0.427 (p < 0.001); and the consistency analysis between the 13C-UBT and the 127 patients with SS-Hp indicated a Kappa value of 0.621 (p < 0.001). However, in 191 patients without a history of Hp eradication, the consistency analysis results for the three methods improved, with Kappa values of 0.467 (p < 0.001) and 0.457 (p < 0.001) for the Hp-sATT with the 13C-UBT and SS-Hp, respectively, and 0.646 (p < 0.001) for the 13C-UBT with SS-Hp. In addition, a positive correlation was found between the signal values of anti-urease antibodies and the Delta Over Baseline (DOB) values of the 13C-UBT. The results also indicated that Hp-infected patients exhibited more pronounced gastric lesions, while cases with Type I Hp infection did not. Conclusions: In patients without a history of Hp eradication, the consistency between the Hp-sATT and 13C-UBT is moderate. However, Hp eradication therapy can reduce the consistency of the test results. When screening for Hp infection using the Hp-sATT, it is necessary to consider the patient's history of Hp eradication.

SphK2 promotes the progression of Helicobacter pylori-positive gastric cancer by regulating the Ras/MEK/ERK pathway

BACKGROUND

Helicobacter pylori (H. pylori) infection promotes gastric cancer (GC) through various mechanisms. It causes inflammation and damage to the gastric mucosa, thereby increasing the risk of developing GC. Sphingolipids can act as signaling molecules that activate or inhibit intracellular signaling pathways, and abnormal sphingolipid metabolism may promote tumorigenesis and metastasis. This study aimed to explore the relationship among sphingosine kinase 2 (SphK2) expression, GC progression, and H. pylori infection.

METHODS

Expression profile data for SphK2 were extracted from public datasets. Normal human gastric mucosal and GC cells were co-incubated with H. pylori, and SphK2 expression in these cells was detected using western blotting. GC cells with SphK2 overexpression and knockdown were established, and the effects of SphK2 and H. pylori on the proliferation, migration, and invasion abilities of GC cells were verified using CCK-8, EdU, and Transwell assays. The expression of Ras/MEK/ERK pathway-related proteins was detected using western blotting, and the secretion of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β in GC cells was detected using ELISA.

RESULTS

SphK2 is highly expressed in GC cells and is associated with a poor prognosis. The expression of SphK2 in GC cells is related to H. pylori infection. SphK2 overexpression promotes the proliferation, migration, and invasion of GC cells and enhances the pro-inflammatory effects of H. pylori.

CONCLUSION

SphK2 promotes the progression of H. pylori-positive GC by activating the Ras/MEK/ERK pathway.

Increased autophagy activity regulated by LC3B gene promoter DNA methylation is associated with progression to active pulmonary tuberculosis disease

BACKGROUND

This study aims to explore the role of autophagy-associated genes (ATG) and their epigenetic markers in the progression of mycobacterium tuberculosis (M. tb) infection, and to test the effects of de-methylation agents on macrophage functions against TB.

METHODS

ATG expressions and their gene promoter DNA methylation levels of blood immune cells were measured in 60 patients with active pulmonary TB disease, 31 subjects with latent TB infection (LTBI), and 15 non-infected healthy subjects (NIHS). An in vitro monocytic THP-1 cell culture model under M. tb-specific antigen stimuli was applied.

RESULTS

LC3B protein expression of blood M1/M2a monocyte, ATG5 protein expression of M2a, and mean DNA methylation levels of the LC3B gene promoter region of peripheral blood mononuclear cells were all increased in active TB patients versus either LTBI or NIHS group. The LC3B methylation levels were negatively correlated with its protein expressions. The discrimination of active TB disease from LTBI or NIHS was optimally captured by prediction scores, which combined LC3B (+) percentage of blood M1/M2a monocyte, LC3B gene promoter DNA methylation level, male gender, and body mass index. LC3B and ATG5 expressions of both blood M2a and neutrophil were decreased after 6-month anti-TB therapy, but hypermethylated LC3B gene promoter persisted. In vitro 5-Aza-2'-deoxycytidine treatment improved bactericidal, apoptosis and phagocytosis functions through augmenting autophagy flux via mechanisms other than demethylation of the LC3B gene promoter in THP-1 cells.

CONCLUSIONS

Increased LC3B expression and LC3B gene promoter hypermethylation may serve as biomarkers for progression of M. tb infection, while use of de-methylation agent may be a potential approach to host-directed immunotherapy in active TB disease.

A Prognostic Riskscore Model Related to Helicobacter pylori Infection in Stomach Adenocarcinoma

Background: Helicobacter pylori (HP) is associated with the development of various stomach diseases, one of the major risk factors for stomach adenocarcinoma (STAD). Methods: The HP infection score between tumor and normal groups was compared by single-sample gene set enrichment analysis (ssGSEA). The key modules related to HP infection were identified by weighted gene coexpression network analysis (WGCNA), and functional enrichment analysis was conducted on these module genes. Further, the limma package was used to screen the differentially expressed genes (DEGs) between HP-positive and HP-negative STAD. The prognostic genes were obtained to construct the riskscore model, and the performance of the model was validated. The correlation between riskscore and tumor immune microenvironment (TIME) was analyzed by Spearman's method. The single-cell atlas of HP-positive STAD was delineated. The mRNA expression levels of the prognostic genes were verified using STAD cells, and the migration and invasion capacities of STAD cells were evaluated by using the wound healing assay and transwell assay. Results: The HP infection score in the tumor group was significantly higher than that in the normal group. The purple and royal blue modules showed higher correlation with HP infection in STAD, and these module genes were enriched in the immune-related pathway. Further, five prognostic genes (CTLA4, CPVL, EMB, CXCR4, and FAM241A) were screened from the HP infection-related DEGs, which were utilized for establishing the riskscore model, with good robustness. Riskscore exhibited strong correlation with TIME in STAD. Single-cell atlas of HP-positive STAD revealed that CXCR4 is highly expressed in Epithelial Cell 1, Epithelial Cell 2, and parietal cells of the tumor group. CPVL, EMB, CTLA4, FAM241A, and CXCR4 showed high expression in STAD cells, and the silencing of CPVL could suppress the migration and invasion of STAD cells. Conclusion: This study established a riskscore model based on HP infection-related genes, which could provide reference for prognostic prediction and treatment targets of STAD.

The Aging Stomach: Clinical Implications of H. pylori Infection in Older Adults-Challenges and Strategies for Improved Management

Aging is a multifactorial biological process characterized by a decline in physiological function and increasing susceptibility to various diseases, including malignancies and gastrointestinal disorders. Helicobacter pylori (H. pylori) infection is highly prevalent among older adults, particularly those in institutionalized settings, contributing to conditions such as atrophic gastritis, peptic ulcer disease, and gastric carcinoma. This review examines the intricate interplay between aging, gastrointestinal changes, and H. pylori pathogenesis. The age-associated decline in immune function, known as immunosenescence, exacerbates the challenges of managing H. pylori infection. Comorbidities and polypharmacy further increase the risk of adverse outcomes in older adults. Current clinical guidelines inadequately address the specific needs of the geriatric population, who are disproportionately affected by antibiotic resistance, heightened side effects, and diagnostic complexities. This review focuses on recent advancements in understanding H. pylori infection among older adults, including epidemiology, diagnostics, therapeutic strategies, and age-related gastric changes. Diagnostic approaches must consider the physiological changes that accompany aging, and treatment regimens need to be carefully tailored to balance efficacy and tolerability. Emerging strategies, such as novel eradication regimens and adjunctive probiotic therapies, show promise for improving treatment outcomes. However, significant knowledge gaps persist regarding the impact of aging on H. pylori pathogenesis and treatment efficacy. A multidisciplinary approach involving gastroenterologists, geriatricians, and other specialists is crucial to providing comprehensive care for this vulnerable population. Future research should focus on refining diagnostic and therapeutic protocols to bridge these gaps, ultimately enhancing clinical outcomes and reducing the burden of H. pylori-associated diseases in the aging population.

Targeting the mTOR-Autophagy Axis: Unveiling Therapeutic Potentials in Osteoporosis

Osteoporosis (OP) is a widespread age-related disorder marked by decreased bone density and increased fracture risk, presenting a significant public health challenge. Central to the development and progression of OP is the dysregulation of the mechanistic target of the rapamycin (mTOR)-signaling pathway, which plays a critical role in cellular processes including autophagy, growth, and proliferation. The mTOR-autophagy axis is emerging as a promising therapeutic target due to its regulatory capacity in bone metabolism and homeostasis. This review aims to (1) elucidate the role of mTOR signaling in bone metabolism and its dysregulation in OP, (2) explore the interplay between mTOR and autophagy in the context of bone cell activity, and (3) assess the therapeutic potential of targeting the mTOR pathway with modulators as innovative strategies for OP treatment. By examining the interactions among autophagy, mTOR, and OP, including insights from various types of OP and the impact on different bone cells, this review underscores the complexity of mTOR's role in bone health. Despite advances, significant gaps remain in understanding the detailed mechanisms of mTOR's effects on autophagy and bone cell function, highlighting the need for comprehensive clinical trials to establish the efficacy and safety of mTOR inhibitors in OP management. Future research directions include clarifying mTOR's molecular interactions with bone metabolism and investigating the combined benefits of mTOR modulation with other therapeutic approaches. Addressing these challenges is crucial for developing more effective treatments and improving outcomes for individuals with OP, thereby unveiling the therapeutic potentials of targeting the mTOR-autophagy axis in this prevalent disease.

Helicobacter pylori CagA mediated mitophagy to attenuate the NLRP3 inflammasome activation and enhance the survival of infected cells

Helicobacter pylori (H. pylori) is one of the most common bacterial infections in the world, and its key virulence component CagA is the leading cause of gastric cancer. Mitophagy is a form of selective autophagy that eliminates damaged mitochondria and is essential for some viruses and bacteria to evade the immune system. However, the mechanisms by which CagA mediates H. pylori-induced mitophagy and NLRP3 inflammasome activation remain elusive. In this study, we reported that H. pylori primarily uses its CagA to induce mitochondrial oxidative damage, mitochondrial dysfunction, dynamic imbalance, and to block autophagic flux. Inhibition of mitophagy led to an increase in NLRP3 inflammasome activation and apoptosis and a decrease in the viability of H. pylori-infected cells. Our findings suggested that H. pylori induces mitochondrial dysfunction and mitophagy primarily via CagA. It reduces NLRP3 inflammasome activation to evade host immune surveillance and increases the survival and viability of infected cells, potentially leading to gastric cancer initiation and development. Our findings provide new insights into the pathogenesis of H. pylori-induced gastric cancer, and inhibition of mitophagy may be one of the novel techniques for the prevention and treatment of this disease.

Programmed cell death in Helicobacter pylori infection and related gastric cancer

Programmed cell death (PCD) plays a crucial role in maintaining the normal structure and function of the digestive tract in the body. Infection with Helicobacter pylori (H. pylori) is an important factor leading to gastric damage, promoting the Correa cascade and accelerating the transition from gastritis to gastric cancer. Recent research has shown that several PCD signaling pathways are abnormally activated during H. pylori infection, and the dysfunction of PCD is thought to contribute to the development of gastric cancer and interfere with treatment. With the deepening of studies on H. pylori infection in terms of PCD, exploring the interaction mechanisms between H. pylori and the body in different PCD pathways may become an important research direction for the future treatment of H. pylori infection and H. pylori-related gastric cancer. In addition, biologically active compounds that can inhibit or induce PCD may serve as key elements for the treatment of this disease. In this review, we briefly describe the process of PCD, discuss the interaction between different PCD signaling pathways and the mechanisms of H. pylori infection or H. pylori-related gastric cancer, and summarize the active molecules that may play a therapeutic role in each PCD pathway during this process, with the expectation of providing a more comprehensive understanding of the role of PCD in H. pylori infection.

Progranulin inhibits autophagy to facilitate intracellular colonization of Helicobacter pylori through the PGRN/mTOR/DCN axis in gastric epithelial cells

Helicobacter pylori (H. pylori) infection is the primary risk factor for the progress of gastric diseases. The persistent stomach colonization of H. pylori is closely associated with the development of gastritis and malignancies. Although the involvement of progranulin (PGRN) in various cancer types has been well-documented, its functional role and underlying mechanisms in gastric cancer (GC) associated with H. pylori infection remain largely unknown. This report demonstrated that PGRN was up-regulated in GC and associated with poor prognosis, as determined through local and public database analysis. Additionally, H. pylori induced the up-regulation of PGRN in gastric epithelial cells both in vitro and in vivo. Functional studies have shown that PGRN promoted the intracellular colonization of H. pylori. Mechanistically, H. pylori infection induced autophagy, while PGRN inhibited autophagy to promote the intracellular colonization of H. pylori. Furthermore, PGRN suppressed H. pylori-induced autophagy by down-regulating decorin (DCN) through the mTOR pathway. In general, PGRN inhibited autophagy to facilitate intracellular colonization of H. pylori via the PGRN/mTOR/DCN axis. This study provides new insights into the molecular mechanisms underlying the progression of gastric diseases, suggesting PGRN as a potential therapeutic target and prognostic predictor for these disorders.

An antibiotic-free platform for eliminating persistent Helicobacter pylori infection without disrupting gut microbiota

Helicobacter pylori (H. pylori) infection remains the leading cause of gastric adenocarcinoma, and its eradication primarily relies on the prolonged and intensive use of two antibiotics. However, antibiotic resistance has become a compelling health issue, leading to H. pylori eradication treatment failure worldwide. Additionally, the powerlessness of antibiotics against biofilms, as well as intracellular H. pylori and the long-term damage of antibiotics to the intestinal microbiota, have also created an urgent demand for antibiotic-free approaches. Herein, we describe an antibiotic-free, multifunctional copper-organic framework (HKUST-1) platform encased in a lipid layer comprising phosphatidic acid (PA), rhamnolipid (RHL), and cholesterol (CHOL), enveloped in chitosan (CS), and loaded in an ascorbyl palmitate (AP) hydrogel: AP@CS@Lip@HKUST-1. This platform targets inflammatory sites where H. pylori aggregates through electrostatic attraction. Then, hydrolysis by matrix metalloproteinases (MMPs) releases CS-encased nanoparticles, disrupting bacterial urease activity and membrane integrity. Additionally, RHL disperses biofilms, while PA promotes lysosomal acidification and activates host autophagy, enabling clearance of intracellular H. pylori. Furthermore, AP@CS@Lip@HKUST-1 alleviates inflammation and enhances mucosal repair through delayed Cu2+ release while preserving the intestinal microbiota. Collectively, this platform presents an advanced therapeutic strategy for eradicating persistent H. pylori infection without inducing drug resistance.

MicroRNAs in Helicobacter pylori-infected gastric cancer: Function and clinical application

Gastric cancer (GC) is the leading cause of cancer-related death worldwide, and it is associated with a combination of genetic, environmental, and microbial risk factors. Helicobacter pylori (H. pylori) is classified as a type I carcinogen, however, the exact regulatory mechanisms underlying H. pylori-induced GC are incompletely defined. MicroRNAs (miRNAs), one of small non-coding RNAs, negatively regulate gene expression through binding to their target genes. Dysregulation of miRNAs is crucial in human cancer. A noteworthy quantity of aberrant miRNAs induced by H. pylori through complex regulatory networks have been identified. These miRNAs substantially affect genetic instability, cell proliferation, apoptosis, invasion, metastasis, autophagy, chemoresistance, and the tumor microenvironment, leading to GC development and progression. Importantly, some H. pylori-associated miRNAs hold promise as therapeutic tools and biomarkers for GC prevention, diagnosis, and prognosis. Nonetheless, clinical application of miRNAs remains in its infancy with multiple issues, including sensitivity and specificity, stability, reliable delivery systems, and off-target effects. Additional research on the specific molecular mechanisms and more clinical data are still required. This review investigated the biogenesis, regulatory mechanisms, and functions of miRNAs in H. pylori-induced GC, offering novel insights into the potential clinical applications of miRNA-based therapeutics and biomarkers.

Autophagy induced by Helicobacter Pylori infection can lead to gastric cancer dormancy, metastasis, and recurrence: new insights

According to the findings of recent research, Helicobacter Pylori (H. pylori) infection is not only the primary cause of gastric cancer (GC), but it is also linked to the spread and invasion of GC through a number of processes and factors that contribute to virulence. In this study, we discussed that H. pylori infection can increase autophagy in GC tumor cells, leading to poor prognosis in such patients. Until now, the main concerns have been focused on H. pylori's role in GC development. According to our hypothesis, however, H. pylori infection may also lead to GC dormancy, metastasis, and recurrence by stimulating autophagy. Therefore, understanding how H. pylori possess these processes through its virulence factors and various microRNAs can open new windows for providing new prevention and/or therapeutic approaches to combat GC dormancy, metastasis, and recurrence which can occur in GC patients with H. pylori infection with targeting autophagy and eradicating H. pylori infection.

Synthesis, characterization, anticancer efficacy evaluation of ruthenium(II) and iridium(III) polypyridyl complexes toward A549 cells

A new ligand DFIP (2-(dibenzo[b,d]furan-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its two complexes iridium(III) [Ir(ppy)₂(DFIP)](PF₆) (ppy = 2-phenylpyridine, Ir1) and ruthenium(II) [Ru(bpy)₂(DFIP)](PF₆)₂ (bpy = 2,2'-bipyridine, Ru1) were synthesized and characterized. The anticancer effects of the two complexes on A549, BEL-7402, HepG2, SGC-7901, HCT116 and normal LO2 cells were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complex Ir1 shows high cytotoxic activity on A549, BEL-7402, SGC-7901 and HepG2, Ru1 exhibits moderate anticancer activity toward A549, BEL-7402 and SGC-7901 cells. The IC₅₀ values of Ir1 and Ru1 toward A549 are 7.2 ± 0.1 and 22.6 ± 1.4 μM, respectively. The localization of complexes Ir1 and Ru1 in the mitochondrial, intracellular accumulation of reactive oxygen species (ROS) levels, and the changes of mitochondrial membrane potential (MMP) and cytochrome c (cyto-c) were investigated. Apoptosis and cell cycle were detected by flow cytometry. Immunogenic cell death (ICD) was used to detect the effects of Ir1 and Ru1 on the A549 using a confocal laser scanning microscope. The expression of apoptosis-related proteins was detected by western blotting. Ir1 and Ru1 can increase the intracellular ROS levels and release cyto-c, reduce the MMP, leading to the apoptosis of A549 cells and blocking the A549 cells at the G0/G1 phase. Additionally, the complexes caused a decrease of the expression of polyADP-ribose polymerase (PARP), caspase 3, Bcl-2 (B-cell lymphoma-2), PI3K (phosphoinositide-3 kinase) and upregulated the expression of Bax. All these findings indicated that the complexes exert anticancer efficacy to induce cell death through immunogenic cell death, apoptosis, and autophagy.

Gastric microbiota in gastric cancer: Different roles of Helicobacter pylori and other microbes

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide. The gastric microbiota plays a critical role in the development of GC. First, Helicobacter pylori (H. pylori) infection is considered a major risk factor for GC. However, recent studies based on microbiota sequencing technology have found that non-H. pylori microbes also exert effects on gastric carcinogenesis. Following the infection of H. pylori, gastric microbiota dysbiosis could be observed; the stomach is dominated by H. pylori and the abundances of non-H. pylori microbes reduce substantially. Additionally, decreased microbial diversity, alterations in the microbial community structure, negative interactions between H. pylori and other microbes, etc. occur, as well. With the progression of gastric lesions, the number of H. pylori decreases and the number of non-H. pylori microbes increases correspondingly. Notably, H. pylori and non-H. pylori microbes show different roles in different stages of gastric carcinogenesis. In the present mini-review, we provide an overview of the recent findings regarding the role of the gastric microbiota, including the H. pylori and non-H. pylori microbes, in the development of GC.

Differences in gastric microbiota and mucosal function between patients with chronic superficial gastritis and intestinal metaplasia

Chronic superficial gastritis (CSG) and intestinal metaplasia (IM) can further develop into gastric cancer, which seriously endangers the health of people all over the world. In this study, the differences in gastric microbiota between CSG patients and IM patients were detected by 16S rRNA gene sequencing. As the expression levels of mucin and CDX2 are closely related to IM, the expression differences of mucin (MUC2 and MUC5AC) and CDX2 in the gastric mucosa of CSG patients and IM patients were detected by Western blot and qRT-PCR. The results showed that both Faith_pd and Observed_species indexes of microbiota in the gastric juice of CSG patients were significantly higher than those of IM patients. At the genus level, Thermus and Anoxybacillus were dominant in the gastric juice of IM patients, and Helicobacter was dominant in the gastric juice of CSG patients. Non-metric multidimensional scaling (NMDS) demonstrated that the dispersion of samples in the CSG group is greater than that in the IM group, and some samples in the CSG group are clustered with samples in the IM group. The KEGG metabolic pathway difference analysis of gastric juice microbiota in CSG and IM patients revealed that the gastric juice microbiota in the CSG and IM patients were significantly enriched in the amino acid metabolism, carbohydrate metabolism, and metabolism of cofactors and vitamins, and the functional differences between the two groups were mainly concentrated in the bacterial secretion system (VirB1, VirB2, VirB3, VirD2, and VirD4). In conclusion, there are significant differences in gastric microbiota and mucosal function between the CSG and IM patients. Moreover, the results of this study may provide a new means for the detection of CSG and IM and a new direction for the prevention and treatment of CSG and IM.

Vacuolating Cytotoxin A Triggers Mitophagy in Helicobacter pylori-Infected Human Gastric Epithelium Cells

Helicobacter pylori (H. pylori)-derived vacuolating cytotoxin A (VacA) causes damage to various organelles, including mitochondria, and induces autophagy and cell death. However, it is unknown whether VacA-induced mitochondrial damage can develop into mitophagy. In this study, we found that H. pylori, H. pylori culture filtrate (HPCF), and VacA could activate autophagy in a gastric epithelial cell line (GES-1). VacA-caused mitochondrial depolarization retards the import of PINK1 into the damaged mitochondria and evokes mitophagy. And, among mass spectrometry (LC-MS/MS) identified 25 mitochondrial proteins bound with VacA, Tom20, Tom40, and Tom70, TOM complexes responsible for PINK1 import, were further identified as having the ability to bind VacA in vitro using pull-down assay, co-immunoprecipitation, and protein–protein docking. Additionally, we found that the cell membrane protein STOM and the mitochondrial inner membrane protein PGAM5 also interacted with VacA. These findings suggest that VacA captured by STOM forms endosomes to enter cells and target mitochondria. Then, VacA is transported into the mitochondrial membrane space through the TOM complexes, and PGAM5 aids in inserting VacA into the inner mitochondrial membrane to destroy the membrane potential, which promotes PINK1 accumulation and Parkin recruitment to induce mitophagy. This study helps us understand VacA entering mitochondria to induce the mitophagy process.