Correlation of Helicobacter pylori and interleukin-8 mRNA expression in high risk gastric cancer population prediction

Immunomodulatory effects of live and pasteurized Lactobacillus crispatus strain RIGLD-1 on Helicobacter pylori-triggered inflammation in gastric epithelial cells in vitro

BACKGROUND

Helicobacter pylori infection is considered as the major risk factor for gastric adenocarcinoma. Today, the increasing emergence of antibiotic-resistant strains has drastically decreased the eradication rate of H. pylori infection. This study was aimed to investigate the inhibitory and modulatory effects of live and pasteurized Lactobacillus crispatus strain RIGLD-1 on H. pylori adhesion, invasion, and inflammatory response in AGS cell line.

METHODS AND RESULTS

The probiotic potential and properties of L. crispatus were evaluated using several functional and safety tests. Cell viability of AGS cells exposed to varying concentrations of live and pasteurized L. crispatus was assessed by MTT assay. The adhesion and invasion abilities of H. pylori exposed to either live or pasteurized L. crispatus were examined by gentamycin protection assay. The mRNA expression of IL-1β, IL-6, IL-8, TNF-α, IL-10, and TGF-ß genes was determined by RT-qPCR from coinfected AGS cells. ELISA was used for the detection of IL-8 secretion from treated cells. Both live and pasteurized L. crispatus significantly decreased H. pylori adhesion/invasion to AGS cells. In addition, both live and pasteurized L. crispatus modulated H. pylori-induced inflammation by downregulating the mRNA expression of IL-1β, IL-6, IL-8, and TNF-α and upregulating the expression of IL-10, and TGF-ß cytokines in AGS cells. Furthermore, H. pylori-induced IL-8 production was dramatically decreased after treatment with live and pasteurized L. crispatus.

CONCLUSIONS

In conclusion, our findings demonstrated that live and pasteurized L. crispatus strain RIGLD-1 are safe, and could be suggested as a potential probiotic candidate against H. pylori colonization and inflammation.

H. pylori infection induces CXCL8 expression and promotes gastric cancer progress through downregulating KLF4

Tumour-derived CXCL8 facilitates the movement of myeloid-derived suppressor cells, which are able to restrain antitumour immune responses to the tumour microenvironment. Kruppel-like factor 4 (KLF4) is a potential tumour suppressor in gastric cancer (GC). However, knowledge regarding correlations between KLF4 and CXCL8 in GC is limited. We use cellular and molecular biological methods to assess whether these two factors interact in GC. Expression CXCL8 and KLF4 was altered in human GC tissues compared to normal gastric tissues in opposite ways. Additionally, cytotoxin-associated gene A protein (CagA) gene transduction or Helicobacter pylori (H. pylori) infection upregulated CXCL8 expression. Knockdown of KLF4 expression increased CXCL8 protein and RNA expression, whereas its overexpression had the opposite effect. CXCL8-mediated enhancement of GC cell migration and proliferation was reversed by upregulation of KLF4 expression. Further mechanistic research revealed that KLF4 binds the CXCL8 promoter, suppressing CXCL8 transcription. Moreover, CXCL8 stimulation reduced KLF4 protein expression and promoted GC cell proliferation and migration, eventually promoting neoplasm growth in vivo. Together, our findings demonstrate that CagA promotes CXCL8 and inhibits KLF4. CXCL8 is a decisive downstream target gene of KLF4, and KLF4 negatively regulates CXCL8 in GC. Furthermore, CXCL8's negative regulation of KLF4 in vivo and in vitro, indicates that CagA may downregulate KLF4 by inducing CXCL8 expression, low expression of KLF4 further promotes that of CXCL8, forming a vicious circle in GC. Targeted KLF4 activation might improve the immunosuppressive microenvironment through direct negative regulation of CXCL8, providing a new potential target to strengthen the efficacy of immunotherapy in GC patients.

Interleukin-8 associated with chemosensitivity and poor chemotherapeutic response to gastric cancer

Background

Gastric cancer (GC) patients have been found to have developed chemotherapy resistance that has resulted in a lowering of their overall survival rates. Interleukin-6 (IL-6) and interleukin-8 (IL-8) could be responsible as the predictive biomarkers in monitoring drug resistance. We have developed a protocol to monitor drug treatment by testing ex vivo chemosensitivity and cytokine levels of primary gastric cultures obtained from endoscopic biopsies.

Methods

We studied 49 patients with distal GC who underwent primary surgical resection between June 2014 and December 2016 in the northern endemic region of Thailand. The clinical and pathological data of patients were recorded, and the cancer sub-type was classified. The correlation of cytokine IL-6 and IL-8 protein expression levels and chemotherapy sensitivity in primary gastric cultures was investigated. Endoscopic biopsies were collected before and/or after chemotherapy treatment followed by FOLFOXIV regimen (oxaliplatin + 5-FU/leucovorin). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to examine ex vivo chemosensitivity to cisplatin, oxaliplatin, 5-fluorouracil (5-FU) and irinotecan. Enzyme-linked immunosorbent assay (ELISA) was performed to investigate cytokine levels.

Results

Ex vivo drug treatment of 49 primary gastric cultures from naive patients revealed a significant correlation between basal levels of IL-8 and chemosensitivity to cisplatin (P=0.001) and oxaliplatin (P=0.001). IL-8 protein expression levels were significantly decreased in the early phase after cisplatin and oxaliplatin treatments leading to an increase in cell sensitivity to drug treatments. Among 49 patients, 11 patients were classified as partial or poor responders after drug interventions, in which case, second endoscopic biopsies were performed for determination of chemosensitivity and cytokine levels. The results demonstrated significant decreases in sensitivity to cisplatin (P=0.049) and oxaliplatin (P=0.014), meanwhile IL-8 protein expression levels were significantly increased by P=0.0423 in both drug treatments. There was no correlation of IL-6 and drug resistance when treatments of the primary gastric cultures involved each of the four chemotherapeutic drugs (P=0.0663).

Conclusions

Upregulation of IL-8 after drug intervention might be useful as predictive biomarker in monitoring drug resistance in GC patients; however, this needs to be confirmed among a larger number of patients and with control groups that are properly age-paired. The established primary gastric culture could serve as a valuable tool for chemotherapy screening, while the repeated usage of platinum drugs may result in drug resistance via upregulation of IL-8 levels.

Inflammatory responses induced by Helicobacter pylori on the carcinogenesis of gastric epithelial GES‑1 cells

Helicobacter pylori (HP) is a pathogenic bacterium associated with chronic gastritis, gastric ulcer and gastric cancer. In the present study, the primary carcinogenesis process of normal gastric epithelial cells (GES‑1) infected with HP was investigated. It was determined that infected gastric mucosal epithelial GES‑1 cells secreted increased interleukin‑8 (IL‑8) and IL‑23, and exhibited enhanced expression of inducible nitric oxide synthase and cyclooxygenase‑2, inducing inflammatory reactions and resulting in apoptosis. The bacterial infection significantly increased the expression of carcinogenesis‑associated genes, including p16, c‑Myc, p53 and p21, as well as the expression of cell surface signaling molecules cluster of differentiation 44 (CD44) and CD54 in GES‑1 cells or tissues of patients with gastritis and gastric cancer in vitro or in vivo. Simultaneously, the migration and invasion abilities of normal gastric epithelial GES‑1 cells were increased following HP infection. These observations demonstrated that the inflammatory response of HP infection could cause normal gastric epithelial cells to undergo significant cancerous reactions, indicating that HP is a risk factor for gastric cancer.

Interleukin 8 (-251 T>A) polymorphism in children and teenagers infected with Helicobacter pylori

Background

Helicobacter pylori (H. pylori) is a gram-negative bacterium that colonizes the human stomach and causes a variety of gastric diseases. This study evaluated the correlations between the -251 (T>A) (rs4073) polymorphism of interleukin-8 (IL-8), the etiology of gastric disease, and H. pylori infection in pediatric and adolescent patients.

Methods

DNA samples were obtained from 285 gastric biopsies from pediatric patients. H. pylori was detected by PCR, whereas PCR-RFLP was used to characterize the -251 (T>A) polymorphism of IL-8.

Results

The histological analysis revealed the presence of gastritis in 158 patients (55.44%). H. pylori was found in 71 samples (24.9%). The -251 (T>A) polymorphism revealed that 58 (29.47%) samples were TT, 143 (50.18%) samples were TA, and 84 (20.35%) samples were AA.

Conclusions

Our findings suggest that IL8-251 A allele may be an important risk factor for the development of gastric disease when associated with H. pylori infection.

A C-Terminal Coiled-Coil Region of CagL is Responsible for Helicobacter Pylori-Induced Il-8 Expression

Interleukin-8 (IL-8) is a potent neutrophil-activating chemokine which triggers the infiltration and migration of neutrophils into areas of bacterial infection. Helicobacter pylori-infected patient studies as well as animal models have revealed that H. pylori type I strains carrying an intact cytotoxin-associated gene pathogenicity island (cag-PAI) with a functional type IV secretion system (T4SS) induce IL-8 expression and secretion in gastric mucosa. This gastric mucosal IL-8 expression correlates with severe histological changes due to H. pylori infection. In the present study, we explored a new recognition pattern on the bacterial adhesion protein CagL inducing IL-8 expression in H. pylori-infected host cells. To analyze the secreted IL-8 concentration, we performed IL-8 enzyme-linked immunosorbent assay (ELISA). To investigate the H. pylori-induced IL-8 expression on the transcriptional level, we transiently transfected gastric epithelial cells (AGS) with a human IL-8 luciferase reporter construct. The results of this study demonstrate that specifically the C-terminal coiled-coil region of the H. pylori CagL protein, a protein described to be located on the tip of the T4SS-pilus, is responsible for several in vitro observations: 1) H. pylori-induced IL-8 secretion via the transforming growth factor (TGF)-α activated epidermal growth factor-receptor (EGF-R) signaling pathway; 2) H. pylori-induced elongation of the cells, a typical CagA-induced phenotype; and 3) the bridging of the T4SS to its human target cells. This novel bacterial-host recognition sequence allows a new insight into how H. pylori induces the inflammatory response in gastric epithelial cells and facilitates the development of precancerous conditions.