Isolation of a foodborne Bacillus cereus strain and its effect on intestinal mucosal immunity-associated factors and gut microbial community in mice / 生物工程学报

Bacillus cereus is a common foodborne pathogen. Accidently eating food contaminated by B. cereus will cause vomiting or diarrhea, and even death in severe cases. In the present study, a B. cereus strain was isolated from spoiled rice by streak culture. The pathogenicity and drug resistance of the isolated strain were analyzed by drug sensitivity test and PCR amplification of virulence-associated gene respectively. Cultures of the purified strain were injected intraperitoneally into mice to examine their effects on intestinal immunity-associated factors and gut microbial communities, to provide references for the pathogenic mechanism and medication guidance of these spoilage microorganisms. The results showed that the isolated B. cereus strain was sensitive to norfloxacin, nitrofurantoin, tetracycline, minocycline, ciprofloxacin, spectinomycin, clindamycin, erythrocin, clarithromycin, chloramphenicol, levofloxacin, and vancomycin, but resistant to bactrim, oxacillin and penicillin G. The strain carries seven virulence-associated genes including hblA, hblC, hblD, nheA, nheB, nheC and entFM, which are involved in diarrhea-causing toxins production. After infecting mice, the isolated B. cereus strain was found to cause diarrhea in mice, and the expression levels of immunoglobulins and inflammatory factors in the intestinal mucosae of the challenged mice were significantly up-regulated. Gut microbiome analysis showed that the composition of gut microbial community in mice changed after infection with B. cereus. The abundance of the uncultured_bacterium_f_Muribaculaceae in Bacteroidetes, which is a marker of body health, was significantly decreased. On the other hand, the abundance of uncultured_bacterium_f_Enterobacteriaceae, which is an opportunistic pathogen in Proteobacteria and a marker of dysbacteriosis, was significantly increased and was significantly positively correlated with the concentrations of IgM and IgG. These results showed that the pathogenic B. cereus carrying diarrhea type virulence-associated gene can activate the immune system by altering the composition of gut microbiota upon infection.

Self-assembled aggregations in Coptidis Rhizoma decoction dynamically regulate intestinal tissue permeability through Peyer's patch-associated immunity / 中草药·英文版

Objective: To investigate the dynamic regulation of self-assembled aggregations (SAA) in Coptidis Rhizoma decoction on the permeability of intestinal tissue and the mechanism underlying. Methods: The effects of SAA on berberine (Ber) absorption were respectively analyzed in an in situ intestinal perfusion model and in an Ussing Chamber jejunum model with or without Peyer's patches (PPs). The expression levels of ZO-1, Occludin and Claudin-1 were detected by immunofluorescence to evaluate the tight junction (TJ) between intestinal epithelium cells. The expression levels of T-box-containing protein expressed in T cells, signal transducers and activators of tranion-6, retinoic acid receptor-related orphan receptor γt and forkhead box P3 in PPs were detected by the reverse transcription-polymerase chain reaction and the secretions of interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-17 (IL-17) and transforming growth factor-β (TGF-β) in PPs were evaluated by immunohistochemistry, to reflect the differentiation of T lymphocyte in PPs to helper T (Th) cell 1, Th2, Th17 and regulatory T (Treg) cell. To confirm the correlation between SAA in Coptidis Rhizoma decoction, PPs-associated immunity and intestinal epithelium permeability, SAA were administrated on an Ussing Chamber jejunum model with immunosuppressed PPs and evaluated its influences on intestinal tissue permeability and TJ proteins expression. Results: SAA in Coptidis Rhizoma decoction could dose-dependently promote Ber absorption in jejunum segment, with the participation of PPs. The dose-dependent and dynamical regulations of SAA on permeability of intestinal tissue and TJ proteins expression level between intestinal epithelium cells occurred along with the dynamically changed T lymphocyte differentiation and immune effectors secretion in PPs. The administration of SAA on immunosuppressed PPs exhibited dose-dependent PPs activation, inducing dynamic promotion on intestinal tissue permeability and inhibition on TJ proteins expression. Conclusion: SAA can improve the Ber absorption in small intestine, through the PPs-associated immunity induced dynamic regulation on intestinal tissue permeability and TJ proteins expression. These findings might enlighten the research of traditional Chinese medicine decoction.

The function of T helper type 17 cell in intestinal mucosal immunity / 国际儿科学杂志

The intestinal mucosa is the biggest lymph organ in human body, which consists of the first line of defensive system with the respiratory mucosa and urinary mucosa. The intestinal mucosa is responsible to defend bacteria, viruses, dietary pathogens, non-steroid anti-inflammatory drug and so on. If the intestinal mucosal immune system is destroyed, the human will suffer many diseases such as infectious diseases,autoimmune diseases. Therefore, it plays an important part in physical health. T helper type 17 (Th17) cells different from Th1 cells and Th2 cells are a distinct lineage of T cells. The discovery of Th17 cells has ruined the constitutional pattern of Th1/Th2. Th17 cells, which are important parts of intestinal mucosal immune system,play critical roles in intestinal autoimmune diseases, tissue inflammation and the infection of various pathogenic bacteria. This paper will review the differentiation of Th17 cell and its function in intestinal mucosal barrier,intestinal autoimmune diseases and intestinal infectious diseases.

Effect of ShengJiangXieXinTang on the intestinal mucosal immune barrier of rats receiving Irinotecan / 中国免疫学杂志

Objective:To observe modulation of gut functions and intestinal mucosal immune barrier by ShengJiangXieXinTang in rats receiving Irinotecan(CPT-11).Methods:Sprague Dawley male rats(n=18)were randomly assigned to three groups:(1)herb group (using ShengJiangXieXinTang by oral administration once a day from day 1 to day 9 and being injected with 150 mg/kg?d CPT-11 on day 4 and 5 into the tail vein); (2)diarrhea control group: using distilled water instead of ShengJiangXieXinTang,with the same treatment of CPT-11 as the herb group; (3)normal control group: using normal saline instead of CPT-11, distilled water instead of ShengJiangXieXinTang,and with the same treatment of as the CPT-11 herb group.The animals were scored in terms of delayed-onset of diarrhea. Rats were killed on day 10,collecting ileum,cecum and colon for pathological examination.The damages in intestinal mucosa were assessed under light microscope according to the criterion of chiu's score.CD4+,CD8+T-lymphocytes and SIgA were enumerated by immunohistochemical staining and calculated by imaging analyzer.Results:Compared with diarrhea control group,the incidence of diarrhea and the damage in intestinal mucosa of the herb group was milder(P