H pylori receptor MHC class II contributes to the dynamic gastric epithelial apoptotic response

Eosinophilic gastrointestinal disorders and the role for the epithelium in pathogenesis and treatment

PURPOSE OF REVIEW

This review aims to provide an overview of the current understanding of eosinophilic gastrointestinal disorders (EGIDs) and the role of the epithelium in influencing disease pathogenesis to inform and devise future therapeutic strategies.

RECENT FINDINGS

Changes in epithelial cell structure, functions, and integrity are observed in EGIDs. In eosinophilic esophagitis (EoE), the esophageal epithelium has been shown to play key roles in perpetuating the inflammatory response in EoE through the expression of pro-inflammatory cytokines and immunological cell-surface proteins. Similar mechanisms appear to exist in the other EGIDs, including eosinophilic gastritis (EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). Because of the increasing rarity of each non-EoE EGID, research focusing on how the epithelium is modulating disease in each lower gastrointestinal compartment is still in its rudimentary stages.

SUMMARY

While there has been significant progress in understanding the role of the epithelium in EoE, further research is needed to obtain a better understanding of the mechanisms mediating epithelial-immune crosstalk in non-EoE EGIDs. Using EoE-epithelial cell research to inform future EGID investigations could lead to the development of new therapeutic interventions, such as targeted therapies to restore epithelial barrier function and reduce inflammation, to improve rare disease-patient quality of life.

An Evaluation of Urease A Subunit Nanocapsules as a Vaccine in a Mouse Model of Helicobacter pylori Infection

Using removable silica templates, protein nanocapsules comprising the A subunit of Helicobacter pylori urease (UreA) were synthesised. The templates were of two sizes, with solid core mesoporous shell (SC/MS) silica templates giving rise to nanocapsules of average diameter 510 nm and mesoporous (MS) silica templates giving rise to nanocapsules of average diameter 47 nm. Both were shown to be highly monodispersed and relatively homogenous in structure. Various combinations of the nanocapsules in formulation were assessed as vaccines in a mouse model of H. pylori infection. Immune responses were evaluated and protective efficacy assessed. It was demonstrated that vaccination of mice with the larger nanocapsules combined with an adjuvant was able to significantly reduce colonisation.

Helicobacter pylori impedes acid-induced tightening of gastric epithelial junctions

Gastric infection by Helicobacter pylori is the most common cause of ulcer disease and gastric cancer. The mechanism of progression from gastritis and inflammation to ulcers and cancer in a fraction of those infected is not definitively known. Significant acidity is unique to the gastric environment and is required for ulcer development. The interplay between gastric acidity and H. pylori pathogenesis is important in progression to advanced disease. The aim of this study was to characterize the impact of acid on gastric epithelial integrity and cytokine release and how H. pylori infection alters these responses. Human gastric epithelial (HGE-20) cells were grown on porous inserts, and survival, barrier function, and cytokine release were studied at various apical pH levels in the presence and absence of H. pylori. With apical acidity, gastric epithelial cells demonstrate increased barrier function, as evidenced by increased transepithelial electrical resistance (TEER) and decreased paracellular permeability. This effect is reduced in the presence of wild-type, but not urease knockout, H. pylori. The epithelial inflammatory response is also modulated by acidity and H. pylori infection. Without H. pylori, epithelial IL-8 release decreases in acid, while IL-6 release increases. In the presence of H. pylori, acidic pH diminishes the magnitude of the previously reported increase in IL-8 and IL-6 release. H. pylori interferes with the gastric epithelial response to acid, contributing to altered barrier function and inflammatory response. H. pylori diminishes acid-induced tightening of cell junctions in a urease-dependent manner, suggesting that local pH elevation promotes barrier compromise and progression to mucosal damage.

Effects of lactobacillus on phosphorylated p38 mitogen-activated protein kinase and apoptosis in SGC-7901 cells treated with lipopolysaccharide of Helicobacter pylori

AIM: To investigate effects of lactobacillus bulgaricus (LBG) on the levels of phosphorylated p38 mitogen-activated protein kinase (P-p38MAPK) and apoptosis index (AI) in gastric cancer cell line SGC-7901 treated with lipopolysaccharide of H. pylori Sydney strain 1 (H. pylori SS1-LPS).

METHODS: Human gastric cancer cell line SGC-7901 was treated with H. pylori SS1-LPS at the concentration of 2.5×10³, 2.5×10⁴, 2.5 ×10⁵ EU/L, respectively, after pretreatment for 1 h with 10 mmol/L SB203580 (blocker of p38MAPK) or 1×10¹³ CFU/L LBG. The level of P-p38MAPK was analyzed by immunocytochemistry after 2 h of H. pylori SS1-LPS treatment. The cell activity was detected by MTT assay after 4、5 and 6 h of treatment, and the apoptosis was measured by flow cytometry at the 6^th hour.

RESULTS: H. pylori SS1-LPS inhibited cell activity (0.164 ± 0.028 vs 0.622 ± 0.068, P < 0.05) and up-regulated the level of P-p38MAPK (79.771 ± 1.424 vs 4.075 ± 0.135, P < 0.01) and AI value (10.000% ± 0.510% vs 4.175% ± 0.206%, P < 0.05) in a dose-dependent manner. The level of P-p38MAPK and AI value in SGC-7901 cells were not significantly different between LBG pretreatment group and the controls, and the cell activity and AI value were not markedly different between SB203580 pretreatment group and the controls.

CONCLUSION: H. pylori SS1-LPS may induce the apoptosis of SGC-7901 cells by activating the phosphorylation of p38MAPK, while LBG can prevent H. pylori SS1-LPS-induced apoptosis of SGC-7901 cells by inhibiting the phosphorylation of p38MAPK.