Probiotics for the Treatment of Gastric Diseases.

Common gastric diseases include chronic gastritis, gastric ulcers and gastric cancer. The etiology of gastric diseases is complicated, including genetics, diet, excessive smoking and drinking, environmental factors, and bacterial infections. As live microorganisms, probiotics can confer health benefits to the host. At present, probiotics have been widely used in the preparation of foods, health products, and medicines. Due to their positive effects in improving diarrhea, constipation, alleviating allergies, enhancing immunity, and maintaining intestinal homeostasis, studies worldwide have focused on whether probiotics also provide therapeutic effects on gastric diseases. Thus, this review summarizes the possible mechanism of probiotics in the treatment of gastric diseases and provides a reference for expanding not only their application but also that of other microecological agents.

Tanshinone IIA inhibits gastric cancer cell stemness through inducing ferroptosis.

Tanshinone IIA is the active constituent extracted from Salvia Miltiorrhza. Numerous studies have shown that Tanshinone IIA could inhibit tumor proliferation and metastasis, including gastric cancer. However, the effect of Tanshinone IIA on gastric cancer cell stemness stays unclear. Here, we found that Tanshinone IIA could reduce gastric cancer cell stemness through detecting spheroid-forming, flow cytometry analysis, and the expression of stemness markers (OCT3/4, ALDH1A1, and CD44). Mechanistically, Tanshinone IIA increased the level of lipid peroxides and decreased glutathione level in gastric cancer cells, both of which are the markers of ferroptosis. Similarly, ferroptosis inducers (erastin, sulfasalazine, and sorafenib) reduced gastric cancer cell stemness. Additionally, the inhibitory effects of Tanshinone IIA on GC cell stemness were reversed by ferroptosis inhibitor (Fer-1) or overexpression of SLC7A11, which is a critical ferroptosis inhibitor. Therefore, we revealed that Tanshinone IIA inhibited the stemness of gastric cancer cells partly through inducing ferroptosis.

CD4+ CD8αα+ T cells in the gastric epithelium mediate chronic inflammation induced by Helicobacter felis.

CD4+ CD8αα+ double-positive intraepithelial T lymphocytes (DP T cells), a newly characterized subset of intraepithelial T cells, are reported to contribute to local immunosuppression. However, the presence of DP T cells in Helicobacter. pylori -induced gastritis and their relationship with disease prognosis has yet to be elucidated. In this study, a chronic gastritis model was established by infecting mice with Helicobacter felis. Gastric-infiltrating lymphocytes were isolated from these mice and analyzed by flow cytometry. The frequency of DP T cells in H. felis-induced gastritis mice was higher than that in uninfected mice. The gastric DP T cells were derived from lamina propria cells but were predominantly distributed in the gastric epithelial layer. These gastric DP T cells also exhibited anti-inflammatory functions, and they inhibited the maturation of dendritic cells and proliferation of CD4+ T lymphocytes in vitro. Elimination of DP T cells simultaneously resulted in severe gastritis and a reduction of H. felis load in vivo. Finally, vaccine mixed with different adjuvants was used to explore the relationship between vaccine efficacy and DP cells. Silk fibroin as the vaccine delivery system enhanced vaccine efficacy by reducing the number of DP T cells. This study demonstrated that DP T cells perform an immunosuppressive role in Helicobacter felis-induced gastritis, and consequently, DP T cells may affect disease prognosis and vaccine efficacy.

Tumor Immune Microenvironment and Its Related miRNAs in Tumor Progression.

MiRNA is a type of small non-coding RNA, by regulating downstream gene expression that affects the progression of multiple diseases, especially cancer. MiRNA can participate in the biological processes of tumor, including proliferation, invasion and escape, and exhibit tumor enhancement or inhibition. The tumor immune microenvironment contains numerous immune cells. These cells include lymphocytes with tumor suppressor effects such as CD8+ T cells and natural killer cells, as well as some tumor-promoting cells with immunosuppressive functions, such as regulatory T cells and myeloid-derived suppressor cells. MiRNA can affect the tumor immune microenvironment by regulating the function of immune cells, which in turn modulates the progression of tumor cells. Investigating the role of miRNA in regulating the tumor immune microenvironment will help elucidate the specific mechanisms of interaction between immune cells and tumor cells, and may facilitate the use of miRNA as a predictor of immune disorders in tumor progression. This review summarizes the multifarious roles of miRNA in tumor progression through regulation of the tumor immune microenvironment, and provides guidance for the development of miRNA drugs to treat tumors and for the use of miRNA as an auxiliary means in tumor immunotherapy.

MiR-375 reduces the stemness of gastric cancer cells through triggering ferroptosis.

BACKGROUND: Gastric cancer stem cells (CSCs) are the main causes of metastasis and drug resistance. We previously indicated that miR-375 can inhibit Helicobacter pylori-induced gastric carcinogenesis; here, we aim to explore the effects and mechanisms of miR-375 on gastric cancer (GC) cell stemness. METHODS: Lentivirus infection was used to construct GC cells with ectopic expression of miR-375. In vitro and in vivo experiments, including analysis of tumor spheroid formation, CD44+ sub-population with stemness, stemness marker expression, and tumor-initiating ability, were performed to evaluate the effects of miR-375 on the stemness of GC cells. Furthermore, microarray and bioinformatics analysis were performed to search the potential targets of miR-375 in GC cells. Luciferase reporter, RNA immunoprecipitation, and RNA-FISH assays were carried out to verify the targeting of miR-375. Subsequently, combined with tissue microarray analysis, erastin-resistant GC cells, transmission electron microscopy, a series of agonists and oxidative stress markers, the underlying mechanisms contributing to miR-375-mediated effects were explored. RESULTS: MiR-375 reduced the stemness of GC cells in vitro and in vivo. Mechanistically, SLC7A11 was identified as a direct target of miR-375 and miR-375 attenuated the stemness of GC cells mainly through triggering SLC7A11-dependent ferroptosis. CONCLUSION: MiR-375 can trigger the ferroptosis through targeting SLC7A11, which is essential for miR-375-mediated inhibition on GC cell stemness. These results suggest that the miR-375/SLC7A11 regulatory axis could serve as a potential target to provoke the ferroptosis and thus attenuate the stemness of GC cells.

Helicobacter pylori induces gastric cancer via down-regulating miR-375 to inhibit dendritic cell maturation.

BACKGROUND: Recent studies and clinical samples have demonstrated that Helicobacter pylori could induce the downregulation of miR-375 in the stomach and promote gastric carcinogenesis. However, whether the immune cells are affected by Helicobacter pylori due to the downregulation of miR-375 is unclear. MATERIALS AND METHODS: In this study, we constructed an overexpression and knockdown of miR-375 and Helicobacter pylori infection cell models in vitro. In addition, the maturity of dendritic cells (DCs) and the expression of IL-6, IL-10, and VEGF at the transcriptional and translational levels were analyzed. Changes in the JAK2-STAT3 signaling pathway were detected. In vivo, the number changes in CD4+ T and CD8+ T cells and the size changes of tumors via models of transplantable subcutaneous tumors were also analyzed. RESULTS: A cell model of Helicobacter pylori and gastric cancer was used to identify the expression of miR-375 and the maturity of dendritic cells. This study found that Helicobacter pylori could downregulate miR-375, which regulates the expression of cytokines IL-6, IL-10, and VEGF in the stomach. MiR-375 regulated the expression of cytokines IL-6, IL-10, and VEGF through the JAK2-STAT3 signaling pathway in vitro. In addition, we found that Helicobacter pylori regulates the maturation of dendritic cells through miR-375. These results were further verified in vivo, and miR-375 diminishes tumor size was also demonstrated. This study showed that immature DCs caused a decrease in the number of CD4+ and CD8+ T cells. CONCLUSIONS: This study demonstrated that Helicobacter pylori can inhibit miRNA-375 expression in the stomach. Downregulated miR-375 activates the JAK2-STAT3 pathway. Activating the JAK2-STAT3 signaling pathway promotes the secretion of IL-6, IL-10, and VEGF, leading to immature differentiation of DCs and induction of gastric cancer.

Silk fibroin hydrogel as mucosal vaccine carrier: induction of gastric CD4+TRM cells mediated by inflammatory response induces optimal immune protection against Helicobacter felis.

Tissue-resident memory T (TRM) cells, located in the epithelium of most peripheral tissues, constitute the first-line defense against pathogen infections. Our previous study reported that gastric subserous layer (GSL) vaccination induced a "pool" of protective tissue-resident memory CD4+T (CD4+TRM) cells in the gastric epithelium. However, the mechanistic details how CD4+TRM cells form in the gastric epithelium are unknown. Here, our results suggested that the vaccine containing CCF in combination with Silk fibroin hydrogel (SF) broadened the distribution of gastric intraepithelial CD4+TRM cells. It was revealed that the gastric intraepithelial TRM cells were even more important than circulating memory T cells against infection by Helicobacter felis. It was also shown that gastric-infiltrating neutrophils were involved as indispensable mediators which secreted CXCL10 to chemoattract CXCR3+CD4+T cells into the gastric epithelium. Blocking of CXCR3 or neutrophils significantly decreased the number of gastric intraepithelial CD4+TRM cells due to reduced recruitment of CD4+T cells. This study demonstrated the protective efficacy of gastric CD4+TRM cells against H. felis infection, and highlighted the influence of neutrophils on gastric intraepithelial CD4+TRM cells formation.

Vaccine-induced gastric CD4+ tissue-resident memory T cells proliferate in situ to amplify immune response against Helicobacter pylori insult.

BACKGROUND: Tissue-resident memory T cells accelerate the clearance of pathogens during recall response. However, whether CD4+ TRM cells themselves can provide gastric immunity is unclear. MATERIALS AND METHODS: We established a parabiosis model between the enhanced green fluorescent protein and wild-type mice that the circulation system was shared, and the wild-type partner was vaccinated with H pylori vaccine composed of CCF and silk fibroin in gastric subserous layer to induce gastric EGFP+ CD4+ TRM cells. Antigen-specific EGFP+ CD4+ T cells and proliferous TRM cells were analyzed by flow cytometry. The colonization of H pylori was detected by quantitative real-time PCR. EGFP+ CD4+ TRM cells and the inflammation of the stomach were observed by histology. RESULTS: A parabiosis animal model was employed to identify the cells that introduced by vaccination in GSL. Antigen-specific EGFP+ CD4+ T cells could be detected at day 7 post-vaccination. Thirty days later, EGFP+ CD4+ TRM cells were established with a phenotype of CD69+ CD103- . Of note, we found that when circulating lymphocytes were depleted by FTY720 administration, these TRM cells could proliferate in situ and differentiate into effector Th1 cells after H pylori challenge. A decrease in H pylori colonization was observed in the vaccinated mice but not unvaccinated mice. Further, we found that although FTY720 was administrated, mounted pro-inflammatory myeloid cells still emerged in the stomach of the vaccinated mice, which might contribute to the reduction of H pylori colonization. CONCLUSIONS: Our study reveals that H pylori vaccine-induced CD4+ TRM cells can proliferate and differentiate in situ to enhance gastric local immunity during recall response.