Shu Wen

c-Myc downregulation: a critical molecular event in resveratrol-induced cell cycle arrest and apoptosis of human medulloblastoma cells

The correlation of c-Myc expression with resveratrol-induced turnover of medulloblastoma cells was investigated in this study by checking (1) c-Myc expression in medulloblastoma tissues and cell lines (UW228-2 and UW228-3), (2) the in vitro effect of resveratrol on c-Myc expression and (3) the influences of c-Myc inhibition in cell growth and survival. Immunohistochemical staining of human medulloblastomas and noncancerous cerebellar tissues revealed that 8 out of 11 tumor tissues (72.7%) expressed c-Myc, in which 4 cases (50%) showed intensified nuclear labeling. RT-PCR, Western blotting, immunocytochemical and immunofluorescence stainings revealed c-Myc downregulation accompanied with growth suppression and apoptosis. Flow cytometry analysis showed S phase arrest in resveratrol-treated cell populations. Transfection of c-Myc directed antisense oligonucleotides to the cultured medulloblastoma cells could reduce c-Myc expression, inhibit cell growth and arrest the cell cycle at S phase. Our results thus for the first time demonstrate that c-Myc downregulation is a critical molecular event of resveratrol-mediated anti-medulloblastoma activity, which is closely associated with growth suppression, cell cycle arrest and apoptosis of medulloblastoma cells.

Dynamic signaling for neural stem cell fate determination

Central nervous system (CNS) development starts from neural stem cells (NSCs) which ultimately give rise to the three major cell types (neurons, oligodendrocytes and astrocytes) of the CNS. NSCs are specified in space- and time-related fashions, becoming spatially heterogeneous and generating a progressively restricted repertoire of cell types. Mammalian NSCs produce different cell types at different time points during development under the influence of multiple signaling pathways. These pathways act in a dynamic web mode to determine the fate of NSCs via modulating the expression and activity of distinct set of transcription factors which in turn trigger the transcription of neural fate-associated genes. This review thus introduces the major signal pathways、transcription factors and their cross-talks and coordinative interactions in NSC fate determination.

Fecal microbiota transplantation and bacterial consortium transplantation have comparable effects on the re-establishment of mucosal barrier function in mice with intestinal dysbiosis

Fecal microbiota transplantation (FMT) is a promising therapy, despite some reports of adverse side effects. Bacterial consortia transplantation (BCT) for targeted restoration of the intestinal ecosystem is considered a relatively safe and simple procedure. However, no systematic research has assessed the effects of FMT and BCT on immune responses of intestinal mucosal barrier in patients. We conducted complementary studies in animal models on the effects of FMT and BCT, and provide recommendations for improving the clinical outcomes of these treatments. To establish the dysbiosis model, male BALB/c mice were treated with ceftriaxone intra-gastrically for 7 days. After that, FMT and BCT were performed on ceftriaxone-treated mice for 3 consecutive days to rebuild the intestinal ecosystem. Post-FMT and post-BCT changes of the intestinal microbial community and mucosal barrier functions were investigated and compared. Disruption of intestinal microbial homeostasis impacted the integrity of mucosal epithelial layer, resulting in increased intestinal permeability. These outcomes were accompanied by overexpression of Muc2, significant decrease of SIgA secretion, and overproduction of defensins and inflammatory cytokines. After FMT and BCT, the intestinal microbiota recovered quickly, this was associated with better reconstruction of mucosal barriers and re-establishment of immune networks compared with spontaneous recovery (SR). Although based on a short-term study, our results suggest that FMT and BCT promote the re-establishment of intestinal microbial communities in mice with antibiotic-induced dysbiosis, and contribute to the temporal and spatial interactions between microbiota and mucosal barriers. The effects of BCT are comparable to that of FMT, especially in normalizing the intestinal levels of Muc2, SIgA, and defensins.

Epigenetic background of neuronal fate determination

The development of the central nervous system (CNS) starts from neural stem cells (NSCs). During this process, NSCs are specified in space- and time-related fashions, becoming spatially heterogeneous and generating a progressively restricted repertoire of cell types: neurons, astrocytes and oligodendrocytes. The processes of neurodevelopment are determined reciprocally by intrinsic and external factors which interface to program and re-program the profiling of fate-determination gene expression. Multiple signaling pathways act in a dynamic web mode to determine the fate of NSCs through modulating the activity of a distinct set of transcription factors which in turn trigger the transcription of neural fate-determination genes. Accumulating evidence reveals that during CNS development, multiple epigenetic factors regulate the activities of extracellular signaling and corresponding transcription factors in a coordinative manner, leading to the formation of a system with sophisticated structure and magic functions. This review aims to introduce recent advances in the epigenetic background of neural cell fate determination.

Association between Polycystic Ovary Syndrome and Gut Microbiota

Polycystic ovary syndrome (PCOS) is the most frequent endocrinopathy in women of reproductive age. It is difficult to treat PCOS because of its complex etiology and pathogenesis. Here, we characterized the roles of gut microbiota on the pathogenesis and treatments in letrozole (a nonsteroidal aromatase inhibitor) induced PCOS rat model. Changes in estrous cycles, hormonal levels, ovarian morphology and gut microbiota by PCR-DGGE and real-time PCR were determined. The results showed that PCOS rats displayed abnormal estrous cycles with increasing androgen biosynthesis and exhibited multiple large cysts with diminished granulosa layers in ovarian tissues. Meanwhile, the composition of gut microbiota in letrozole-treated rats was different from that in the controls. Lactobacillus, Ruminococcus and Clostridium were lower while Prevotella was higher in PCOS rats when compared with control rats. After treating PCOS rats with Lactobacillus and fecal microbiota transplantation (FMT) from healthy rats, it was found that the estrous cycles were improved in all 8 rats in FMT group, and in 6 of the 8 rats in Lactobacillus transplantation group with decreasing androgen biosynthesis. Their ovarian morphologies normalized. The composition of gut microbiota restored in both FMT and Lactobacillus treated groups with increasing of Lactobacillus and Clostridium, and decreasing of Prevotella. These results indicated that dysbiosis of gut microbiota was associated with the pathogenesis of PCOS. Microbiota interventions through FMT and Lactobacillus transplantation were beneficial for the treatments of PCOS rats.

Intestinal dysbacteriosis induces changes of T lymphocyte subpopulations in Peyer’s patches of mice and orients the immune response towards humoral immunity

The large numbers of human intestinal microorganisms have a highly co-evolved relationship with the immune system. Dysbacteriosis of intestinal microbiota induces alterations of immune responses, and is closely related to disease development. Peyer’s patches are immune sensors in intestine which exert essential functions during development of inflammatory disease. However, interactions between commensal bacteria and PPs have been poorly characterized. In this study, changes of lymphocyte subpopulations and production of cytokines in PPs of mice with intestinal dysbacteriosis were investigated. The ceftriaxone-induced dysbacteriosis caused a notable change in populations of T lymphocytes, their subpopulations in PPs and expressions of various cytokines. Our results suggest intestinal dysbacteriosis in mice reduces immune tolerance in PPs and orients immune response towards humoral immunity.

Long-term use of ceftriaxone sodium induced changes in gut microbiota and immune system

Antibiotic administration, while facilitating clearance of targeted infections, also perturbs commensal microbial communities. Previous studies have all focused on the effects of short term use of antibiotics. Here, we focus on the effects of long term use of antibiotic on gut microbiota and immunity. BALB/c mice received saline or different doses of ceftriaxone sodium (100, 200 and 400 mg/mL) via daily gavage for 150 days. Alterations of fecal microbiota, small intestine histopathology, body weight, spleen index, serum IgG, mucus SIgA, IFN-γ/IL-4 ratio, CD4/CD8 ratio and CD4+CD25+ cells were evaluated. Long term ceftriaxone sodium administration resulted in gut microbiota dysbiosis, intestine histological lesions, growth inhibition, spleen index reducing. The immune defense ability reduced as serum IgG and mucus SIgA decreased significantly. Not only the immune defense, long term ceftriaxone administration also affected immune regulation. The IFN-γ/IL-4 and CD4/CD8 ratios increased, the CD4+CD25+ cells reduced on days 30 and 60 after ceftriaxone administration. However, after 90 days of ceftriaxone administration, the IFN-γ/IL-4, CD4/CD8 ratios and CD4+CD25+ cells restored, which indicated a new balance of immune regulation had been formed. Overall, these findings contribute to our understanding of long term antibiotic administration influencing gut microbiota and immunity.

Transplantation of a bacterial consortium ameliorates trinitrobenzenesulfonic acid-induced colitis and intestinal dysbiosis in rats.

AIM To investigate the effects of a defined bacterial consortium on trinitrobenzenesulfonic acid (TNBS)-induced colitis and intestinal dysbiosis in rats. MATERIALS & METHODS Rats with TNBS-induced colitis were treated with ceftriaxone and/or a mixture of ten bacterial strains isolated from mouse feces for continuous 24 days. Macroscopic and histopathological parameters in colonic tissue were compared, as were myeloperoxidase enzyme activity and cytokine levels. Patterns of intestinal microbiota were assessed by PCR-denaturing gradient gel electrophoresis, the abundance of selected microbial groups was evaluated by qPCR. RESULTS & CONCLUSION Transplantation of the bacterial consortium showed anti-inflammatory activity in the intestines of rats with TNBS-induced colitis and contributed to the rapid re-establishment of intestinal microbial equilibrium. A defined bacterial consortium may be a viable therapeutic option for the treatment inflammatory bowel disease.

Effects of ceftriaxone-induced intestinal dysbacteriosis on dendritic cells of small intestine in mice.

Intestinal microflora plays a pivotal role in the development of the innate immune system and is essential in shaping adaptive immunity. Dysbacteriosis of intestinal microflora induces altered immune responses and results in disease susceptibility. Dendritic cells (DCs), the professional antigen‐presenting cells, have gained increasing attention because they connect innate and adaptive immunity. They generate both immunity in response to stimulation by pathogenic bacteria and immune tolerance in the presence of commensal bacteria. However, few studies have examined the effects of intestinal dysbacteriosis on DCs. In this study, changes of DCs in the small intestine of mice under the condition of dysbacteriosis induced by ceftriaxone sodium were investigated. It was found that intragastric administration of ceftriaxone sodium caused severe dysteriosis in mice. Compared with controls, numbers of DCs in mice with dysbacteriosis increased significantly (P = 0.0001). However, the maturity and antigen‐presenting ability of DCs were greatly reduced. In addition, there was a significant difference in secretion of IL‐10 and IL‐12 between DCs from mice with dysbacteriosis and controls. To conclude, ceftriaxone‐induced intestinal dysbacteriosis strongly affected the numbers and functions of DCs. The present data suggest that intestinal microflora plays an important role in inducing and maintaining the functions of DCs and thus is essential for the connection between innate and adaptive immune responses.

Gut Microbiome Associates With Lipid-Lowering Effect of Rosuvastatin in Vivo

Background: Statin has been widely used to treat hyperlipidemia because of its high potency in decreasing cholesterol levels. The present study aimed to examine the lipid-lowering effect of rosuvastatin and the composition, diversity and species abundance of gut microbiome in association with rosuvastatin efficacy. Trial registration: ChiCTR-ORC-17013212 at the First Affiliated Hospital of Dalian Medical University, November 2, 2017. Results: Totally 64 patients with hyperlipidemia were treated with 10 mg/day of rosuvastatin for 4–8 weeks. Blood lipid indicators triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low-density lipoprotein cholesterol (LDL-C) were measured before and after the treatment. Stool samples were collected right after the treatment. Following total DNA extraction and PCR amplification of 16S rRNA gene, Illumina sequencing was performed for gut microbiome identification, classification and characterization. All the patients showed a significant blood lipid reduction after the treatment. The patients were grouped according to parallel manner design. Group I had 33 patients whose blood lipid levels dropped to the normal levels from week 4, with 58.5% reduction in LDL-C and 26.6% reduction in TC. Group II had 31 patients whose blood lipid levels were still above the normal levels after 8 weeks therapy, but with 41.9% reduction in LDL-C and 31.2% reduction in TC. Based on Operational Taxonomic Unit data, Alpha-diversity by Shannon Index was different between the two groups, and beta-diversity by Principle Component Analysis exhibited separated patterns of the two groups. The differences were also observed in the relative-abundance at phylum, family, and genus levels of the two groups. Linear discriminate analysis illustrated that the abundance of 29 taxa was higher in group I, while the abundance of other 13 taxa was higher in group II. Phyla Firmicutes and Fusobacteria had negative correlation to LDL-C level, but Cyanobacteria and Lentisphaerae had a positive correlation to LDL-C level. Moreover, gender and age were also found somehow correlated to microbial community composition. Conclusion: Rosuvastatin therapy had different blood lipid-lowering effect on hyperlipidemia. The gut microbiota exhibited variation in community composition, diversity and taxa in association to rosuvastatin hypolipidemic effect. These results indicate that modulation of gut microflora, especially the negative/positive correlated species might strengthen statin efficacy in statin-inadequate patients.