Introduction

CagA is a virulence factor of Helicobacter pylori (H. pylori) and is a type IV secretion system effector that acts as an inflammatory driver in gastric epithelial cells. While delivered into the gastric epithelial cells, CagA is usually degraded through autophagy. Thus, the induction of CagA degradation in H. pylori-infected epithelial cells is an essential protection from the host against gastritis. However, the molecular mechanism of CagA degradation through autophagy remains elusive. Therefore, elucidating the molecular mechanism of host regulation of CagA degradation could provide potential intervention strategies for H. pylori-related gastritis. In this study, we report that AU-rich element RNA-binding factor 1 (AUF1) is necessary for inhibition of CagA degradation.

Aims & Methods

In the co-culture experiment of gastric epithelial cells and H. pylori in vitro, knockdown or overexpression of AUF1 was performed, and the effect of AUF1 on CagA degradation was detected by protein degradation assay. Western blot, transmission electron microscopy and immunofluorescence assay were used to detect the effect of AUF1 on H. pylori-induced autophagy. The mCherry-GFP-LC3 reporter system, Lysotracker Red staining, and PDMPO staining were used to detect the acidification of lysosomes. RNA immunoprecipitation and RNA-pulldown assay were used to detect the interaction of AUF1 and CTSD mRNA. Transcriptome analysis was used to explore the changes of pathway in gastric epithelial cells with H. pylori by knockdown AUF1. Immunohistochemical staining was used to detect the expression and subcellular localization of AUF1 and CTSD in gastric mucosa of patients of H. pylori-gastritis. Cell supernatant exosomes were collected by ultracentrifugation, and the effect of AUF1 on CagA in exosomes was detected by interfering with AUF1 expression.

Results

After H. pylori infection in gastric epithelial cells, AUF1 knockdown can promote autophagy flux, promote the formation of autophagy lysosome and lysosome acidification, thus promoting the autophagy degradation of CagA, and autophagy inhibitor BafA1 can counteract the promoting degradation effect of AUF1 knockdown. On the contrary, overexpression of AUF1 inhibited autophagy flux and autophagy degradation of CagA. Mechanically, we found that AUF1 can bind to the 3'UTR region of cathepsin D (CTSD) mRNA, thereby reducing the stability of CTSD mRNA, downregulating the expression of CTSD, and inhibiting the degradation of CagA. In addition, after AUF1 knockdown in H. pylori-infected gastric epithelial cells, transcriptome analysis showed that the inflammatory pathway was significantly inhibited, and the expressions of inflammatory factors such as IL-6, IL-8 and TNF-α were also significantly down-regulated. On the contrary, overexpression of AUF1 significantly promoted the inflammatory pathway. In addition, AUF1 expression and cytoplasmic translocation were enhanced by H. Pylori. After inhibiting the degradation of CagA, AUF1 also leads to the increase of CagA in exosomes, thus promoting extracellular inflammation.

Conclusion

H. pylori CagA up-regulates the expression of AUF1 and promotes its distribution to the cytoplasm. At the same time, AUF1 inhibits the autophagic degradation of CagA by inhibiting the expression of CTSD. Then, the accumulated intracellular CagA promotes the intracellular inflammation and can also be secreted to promote extracellular inflammation. Our findings identify AUF 1 as a novel negative regulator of autolysosome formation and suggest that dysregulation of AUF1 expression leads to an increased risk of H. pylori-gastritis.

References

• 1. White EJ, Matsangos AE, Wilson GM. AUF1 regulation of coding and noncoding RNA. Wiley Interdiscip Rev RNA. 2017;8(2):10.1002/wrna.1393.
• 2. Chang WL, Yeh YC, Sheu BS. The impacts of H. pylori virulence factors on the development of gastroduodenal diseases. J Biomed Sci. 2018;25(1):68.
• 3. Yang Y, Shu X, Xie C. An Overview of Autophagy in Helicobacter pylori Infection and Related Gastric Cancer. Front Cell Infect Microbiol. 2022;12:847716.
• 4. sugawa H, Suzuki H, Saya H, et al. Reactive oxygen species-induced autophagic degradation of Helicobacter pylori CagA is specifically suppressed in cancer stem-like cells. Cell Host Microbe. 2012;12(6):764-777.
• 5. Raju D, Hussey S, Ang M, et al. Vacuolating cytotoxin and variants in Atg16L1 that disrupt autophagy promote Helicobacter pylori infection in humans. Gastroenterology. 2012;142(5):1160-1171.
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Disclosure

The authors declare no conflict of interest.

Introduction

Cardiovascular disease (CVD) is the leading cause of death in NAFLD patients. Increased plasma proneurotensin (pro-NT) levels were found to identify the presence and severity of NAFLD. The association between pro-NT and incident major cardiovascular events has been confirmed.

Aims & Methods

To evaluate the association of serum pro-neurotensin with cardiovascular risk in NAFLD patients. A cross-sectional cohort included sixty patients with NAFLD and documented CVD, sixty patients with NAFLD without documented CVD and 60 healthy controls. Liver function tests, liver enzymes, lipid profile, fasting blood glucose, abdominal ultrasound and serum proneurotensin were done.

Results

Proneurotensin was significantly higher in the NAFLD group as compared to controls, P <0.0001. Proneurotensin levels were significantly higher in patients with established CVD in addition to NAFLD as compared to NAFLD only patients P <0.0001. Serum proneurotensin showed significant positive correlation with Framingham score and NAFLD Fibrosis Score P <0.0001. Reciever operating characteristic (ROC) curve demonstrated a cut-off value >24.5 ng/L for proneurotensin as a predictor of NAFLD with 64.2% sensitivity and 96.7% specificity, (AUC) = 0.862, P < 0.001. And a cut-off value >28.5 ng/L for proneurotensin as a predictor of CVD in NAFLD patients, with 83.3% sensitivity and 78.3% specificity, (AUC) = 0.854, P < 0.001.

Conclusion

serum proneurotensin is significantly higher in NAFLD patients established CVD than NAFLD only patients and healthy subjects. It can be considered as a marker of CVD risk in such patients

References

1. Ilaria Barchetta, Flavia Agata Cimini, Frida Leonetti, Danila Capoccia, Claudio Di Cristofano, Gianfranco Silecchia, Marju Orho-Melander, Olle Melander, Maria Gisella Cavallo; Increased Plasma Proneurotensin Levels Identify NAFLD in Adults With and Without Type 2 Diabetes, The Journal of Clinical Endocrinology & Metabolism, Volume 103, Issue 6, 1 June 2018, Pages 2253–2260

Disclosure

nothing to disclose.

Introduction

Early detection and removal of colorectal adenomatous lesions is effective in reducing the incidence and mortality of colorectal cancer. To achieve this, it is important to improve the detection of colorectal lesions. Newly endoscopy technology, texture and color enhancement imaging (TXI) is expected to enhance visibility of lesion by adjusting the color, structure, and brightness of images taken with white-light imaging (WLI) using EVIS X1 system (Olympus Medical Systems Co., Tokyo, Japan). Our previous retrospective study indicated that TXI improve the detection of colorectal neoplastic lesions. However, it is unclear that ability of detection in TXI is superior to that of WLI.

Aims & Methods

We conducted a prospective multicenter randomized controlled trial to verify the efficacy of TXI in the detection of colorectal neoplastic lesions, when compared with WLI (jRCT1032230089).This trial was conducted at 8 institutions in Japan between May and November 2023. The eligibility criteria included patients aged 20–80 years who were scheduled for screening, post-endoscopic surveillance, or work-up for a positive fecal immunochemical test or abdominal symptoms. Patients were randomly assigned (1:1) to TXI or WLI (control group). In all colonoscopies, EVIS X1 system and CF-EZ1500DI were used. The primary endpoint was mean adenoma per procedure (MAP) in per protocol set (PPS). Other endpoints included adenoma detection rate (ADR), advanced ADR (advanced adenoma: more than 10 mm in diameter, villous or tubulovillous in histology, or high-grade dysplasia), polyp detection rate (PDR), and flat polyp detection rate (FDR). We assumed the TXI mode observations to have an improvement effect of MAP with a difference of δ=0.3 on WLI and the standard deviations of MAP in TXI and WLI were expected to be 1.8 and 1.3, respectively. The required number of subjects for analysis was calculated to be 960, considering an expected dropout rate of 10%, when the two-sided significance level was set at 0.05 and power at 0.8.

Results

A total of 960 patients were enrolled. In PPS, 896 patients were analyzed (451 in TXI and 445 in WLI). In MAP, there was no statistically significant difference between the groups (TXI: 1.4 [95% CI: 1.2-1.6] vs. WLI: 1.5 [1.3-1.7]). ADR was similar in the groups (57.21% [52.49-61.82] vs. 55.96 [51.20-60.63]). Advanced ADR tend to be higher in TXI than WLI (11.09% [8.34-14.35] vs. 8.54[6.11-11.53]). PDR was significantly higher in TXI than WLI (82.48% [78.65-85.88] vs. 74.38 [70.06-78.38]. FDR was significantly higher in TXI than WLI (76.50% [72.31-80.34] vs. 70.34 [65.86-74.55]).

Conclusion

This trial could not show the superiority of TXI over WLI in MAP and ADR. However, it showed that of TXI over WLI in PDR and FDR, indicating that TXI may have ability to detect more flat colorectal lesions which have malignant potential or are difficult to detect.