Pretreatment with chitosan oligosaccharides attenuate experimental severe acute pancreatitis via inhibiting oxidative stress and modulating intestinal homeostasis.

Severe acute pancreatitis (SAP) is a severe acute abdominal disease. Recent evidence shows that intestinal homeostasis is essential for the management of acute pancreatitis. Chitosan oligosaccharides (COS) possess antioxidant activity that are effective in treating various inflammatory diseases. In this study we explored the potential therapeutic effects of COS on SAP and underlying mechanisms. Mice were treated with COS (200 mg·kg-1·d-1, po) for 4 weeks, then SAP was induced in the mice by intraperitoneal injection of caerulein. We found that COS administration significantly alleviated the severity of SAP: the serum amylase and lipase levels as well as pancreatic myeloperoxidase activity were significantly reduced. COS administration suppressed the production of proinflammatory cytokines (TNF-α, IL-1ß, CXCL2 and MCP1) in the pancreas and ileums. Moreover, COS administration decreased pancreatic inflammatory infiltration and oxidative stress in SAP mice, accompanied by activated Nrf2/HO-1 and inhibited TLR4/NF-κB and MAPK pathways. We further demonstrated that COS administration restored SAP-associated ileal damage and barrier dysfunction. In addition, gut microbiome analyses revealed that the beneficial effect of COS administration was associated with its ability to improve the pancreatitis-associated gut microbiota dysbiosis; in particular, probiotics Akkermansia were markedly increased, while pathogenic bacteria Escherichia-Shigella and Enterococcus were almost eliminated. The study demonstrates that COS administration remarkably attenuates SAP by reducing oxidative stress and restoring intestinal homeostasis, suggesting that COS might be a promising prebiotic agent for the treatment of SAP.

Characterization of the duodenal bacterial microbiota in patients with pancreatic head cancer vs. healthy controls.

An increasing number of reports have demonstrated that there is an association between the presence of pathogenic microorganisms and pancreatic cancer. However, the role of the duodenal microbiota in pancreatic carcinogenesis remains unknown. In this study, duodenal mucosal microbiota was analyzed in 14 patients with pancreatic head cancer and 14 healthy controls using 16S rRNA gene pyrosequencing methods. Plasma endotoxin activity and the concentrations of the proinflammatory cytokine IL-6 and C-reactive protein (CRP) were measured in blood samples. The urea breath test was used to detect Helicobacter pylori infections. Endoscopic duodenal mucosal biopsies were evaluated by histological examinations. Statistical comparisons of inflammatory factors revealed significantly higher levels of CRP and IL-6 in the pancreatic cancer group as compared to healthy controls. Patients with pancreatic cancer also had a higher incidence of H. pylori infections and showed mucosal changes, including villous abnormalities and diffuse inflammatory cell infiltration in the lamina propria. The sequences analysis showed that based on linear discriminant analysis effect size (LEfSe) analysis at the genus level, Acinetobacter, Aquabacterium, Oceanobacillus, Rahnella, Massilia, Delftia, Deinococcus, and Sphingobium were more abundant in the duodenal mucosa of pancreatic cancer patients, whereas the duodenal microbiotas of healthy controls were enriched with Porphyromonas, Paenibacillus, Enhydrobacter, Escherichia, Shigella, and Pseudomonas. These results reveal a picture of duodenal microbiota in pancreatic head cancer patients that could be useful in future trials investigating the role of gut microbiota in pancreatic cancer.

Impact of multiple quaternary ammonium salts on dynamic properties of BSA adsorption layer at different pH values.

The interaction mechanism of multiple quaternary ammonium salts (MQAS) with bovine serum albumin (BSA) was examined by the fluorescence quenching method and circular dichroism (CD) spectra. Moreover, the effects of MQAS on the dynamic properties of BSA adsorption layers at different pH values were investigated using dilational interfacial rheology. Results show that the quenching constants increase with an increase in pH values and decrease with an increase in the experiment temperature at pH 5.3. The quenching mechanism is static quenching, and the electrostatic force dominates the interaction between MQAS and BSA at pH 5.3. Due to three positive head groups, MQAS can significantly affect the dynamic interfacial activity of BSA molecules at a relatively low concentration. At pH 4.3, the electrostatic repulsion is unfavorable for the formation of MQAS/BSA complexes. Consequently, MQAS molecules will replace BSA molecules from the interface by competitive adsorption. At the pH value above the isoelectric point of BSA, the electrostatic attraction is better for the formation of MQAS/BSA complexes, which exhibit a rapid adsorption rate and an enhanced interfacial activity. Moreover, the kinetic dependencies of interfacial dilational elasticity for the MQAS/BSA mixtures become nonmonotonous. The appearance of the maximum interfacial elasticity values can be attributed to the formation of tails and loops, which suggests that the addition of MQAS destroys the secondary and tertiary structure of protein in the bulk phase. In addition, the effects of MQAS on the secondary structure of protein were demonstrated by CD spectra.

Porous SiO2 -coated ultrasmall selenium particles nanospheres attenuate cerulein-induce acute pancreatitis in mice by downregulating oxidative stress.

OBJECTIVE: To investigate the potential therapeutic role of porous SiO2 -coated ultrasmall selenium particles nanospheres (Se@SiO2 nanospheres) pretreatment in acute pancreatitis (AP) and to investigate the related mechanism. METHODS: C57BL/6 mice were randomized to the normal control (CON) group, the AP (induced by cerulein injection) (CAE) group, and AP pretreated with Se@SiO2 nanocomposites at 1 and 2 mg/kg (CAE + 1 or 2 mg/kg Se@SiO2 ) groups, respectively. Serum levels of amylase and lipase, inflammatory cytokines (interleukin [IL]-6, IL-1ß and tumor necrosis factor [TNF]-α), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine (Cr) were measured, and histopathology was performed to examine the tissue samples of the pancreas, lungs, kidneys and liver. Immunofluorescence assay of reactive oxygen species (ROS), myeloperoxidase (MPO) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling were conducted, and levels of MPO, malondialdehyde, superoxide dismutase and glutathione were evaluated. Finally, Western blot analysis was used to evaluate protein expressions of Nrf2, HO-1, NQO1, TLR4, MyD88 and p-p65 in pancreatic tissue. RESULTS: Se@SiO2 nanospheres alleviated pathological damage to the pancreas, and reduced pancreatic enzymes and inflammatory cytokines. Injury to other organs such as the liver, lungs and kidneys was also alleviated, as indicated by decreased ALT, AST, BUN, and Cr levels as well as improved histopathology. Moreover, Se@SiO2 nanospheres reduced oxidative stress, and ultimately inhibited TLR4/ MyD88/p-p65 pathway and increased the protein expressions of NQO1, Nrf2, and HO-1. CONCLUSION: Se@SiO2 nanospheres may alleviate AP by relieving oxidative stress and targeting the TLR4/Myd88/p-p65 and NQO1/Nrf2/HO-1 pathways.