Introduction

During severe acute pancreatitis (SAP), large amounts of reactive oxygen species (ROS) are produced in the abdominal cavity, which can directly damage abdominal organs and be absorbed into the blood, causing systemic inflammatory response syndrome and multiple organ dysfunction. Molecular hydrogen (H₂) can target to eliminate harmful ROS such as hydroxyl radical ^[1]. When severe inflammatory damage occurs in the pancreas, microthrombosis are widely produced, and the antioxidant effect is difficult to be fully exerted if H₂ is administered through circulation.

Aims & Methods

We have developed hydrogen-loaded nanoparticles (nano hydrogen) to bring H₂ into direct contact with the pancreas by intraperitoneal administration, providing a new strategy for the anti-inflammatory treatment of SAP. In this study, we investigated the pathophysiological mechanisms by which nano hydrogen ameliorates SAP.
In vivo, SAP was established by retrograde injection of sodium taurocholate through the rat pancreatic duct. Nano hydrogen (37.5 mg/kg) was injected intraperitoneally in the SAP + nano hydrogen group. The survival rate was calculated. Pathological scoring was performed. Neutrophil and macrophage infiltration, ultrastructural changes of acinar cells and vascular endothelial cells, and microthrombosis of pancreatic tissue were detected. In vitro, intracellular ROS of AR42J cells were measured using hydroxyphenyl fluorescein solution. Human umbilical vein endothelial cells (HUVECs) were stimulated with TNF-α, and nano hydrogen was used for intervention. RNA-seq was performed on rat pancreatic tissue and HUVEC samples. The expression of VCAM-1, ICAM-1 and NF-κB p65 in HUVECs was compared. β-galactosidase staining and markers of cellular senescence such as phosphorylated γ-H₂A.X, p53, p21, and p16 were detected. The opening of the mitochondrial permeability transition pore (MPTP) and mitochondrial membrane potential of HUVECs were assessed.

Results

After intraperitoneal administration of nano hydrogen into SAP rats, the survival rate increased by 66%, and the pathological score of pancreas dramatically decreased (p < 0.01). The neutrophil infiltration was significantly reduced (p < 0.01), and the ultrastructure of acinar cells and vascular endothelial cells was significantly improved. The pancreatic tissue of SAP rats had a large number of microthrombi, which were significantly reduced by nano hydrogen. Pancreatic vascular endothelial cells in SAP rats expressed p21.
Nano hydrogen significantly downregulated the dominant transcriptional events in SAP pancreas, such as leukocyte chemotaxis and migration and oxidative stress, and also significantly reduced the production of ROS in the acinar cells and the expression of VCAM-1, ICAM-1 and phosphorylated p65 after TNF-α stimulation of HUVECs (p < 0.01). RNA-seq analysis of HUVECs indicated that TNF-α induced cellular senescence, confirmed by positive β-galactosidase staining and significantly increased expression of phosphorylated γ-H₂A.X, total p53, phosphorylated p53, p21 (p < 0.05) and p16 (p < 0.01). MPTP opened and mitochondrial membrane potential disappeared in TNF-α-stimulated HUVECs. Nano hydrogen significantly attenuated the abovementioned manifestation.

Conclusion

Nano hydrogen can effectively eliminate ROS brought to the pancreas by neutrophil infiltration and etc., and improve vascular endothelial cell function, thus significantly improving pathological damage such as pancreatic necrosis, which has important translational value for clinical treatment.

References

1. Ohsawa I, Ishikawa M, Takahashi K, et al. Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals. Nat Med, 2007, 13(6): 688-694.

Introduction

Helicobacter pylori（H.pylori） is a major risk factor for gastric cancer. Our previous study found that activin A receptor type I (ACVR1) plays an important role in the pathogenesis of gastric mucosal lesions caused by Helicobacter pylori. Meanwhile, transcriptome data showed that ACVR1 was negatively correlated with POLD1, the gene encoding the catalytic subunit of EUkaryotic DNA polymerase (Pol δ) P125. However, the specific roles of ACVR1 and ACVR1 in H.pylori carcinogenesis remain unclear. This study investigated the molecular mechanism and potential association between H.pylori, ACVR1 and POLD1 in gastric cancer.

Aims & Methods

Gastric cancer cells, human tissue and mouse model were used in this study. We used helicobacter pylori infection models in vitro and in vivo, and Western blot, QRT-PCR, immunofluorescence, COIP, CCK8, Transwell and other tests for molecular, mechanism and function studies.To explore the role of Helicobacter pylori in DNA damage repair through ACVR1.

Results

Transcriptome data showed a negative correlation between ACVR1 and POLD1 expression. In vitro results showed that Hp infection could up-regulate the expression of ACVR1 and γ-H2AX, and decrease the expression of POLD1. After the deletion of ACVR1, the expression of POLD1 was increased. The expression of POLD1 decreased when ACVR1 was overexpressed. By predicting transcription factors, it was found that IRF3 could regulate the transcription of POLD1, and Hp infection could down-regulate the expression of IRF3, which was related to the virulence factor CagA. In addition, interference with the expression of POLD1 can up-regulate the expression of γ-H2AX, and inhibit cell proliferation, invasion and migration.

Conclusion

In summary, our study found that the ACVR1-IRF3-POLD1 signaling axis plays an important role in the process of Helicobacter pylori infection causing gastric cancer, and the ACVR1-IRF3-POLD1 axis can promote the occurrence of DNA damage while inhibiting the biobehavioral function of tumor cells.