Analysis of gut microbial regulation of host gene expression along the length of the gut and regulation of gut microbial ecology through MyD88

BackgroundThe gut microbiota has profound effects on host physiology but local host-microbial interactions in the gut are only poorly characterised and are likely to vary from the sparsely colonised duodenum to the densely colonised colon. Microorganisms are recognised by pattern recognition receptors such as Toll-like receptors, which signal through the adaptor molecule MyD88.MethodsTo identify host responses induced by gut microbiota along the length of the gut and whether these required MyD88, transcriptional profiles of duodenum, jejunum, ileum and colon were compared from germ-free and conventionally raised wild-type and Myd88-/- mice. The gut microbial ecology was assessed by 454-based pyrosequencing and viruses were analysed by PCR.ResultsThe gut microbiota modulated the expression of a large set of genes in the small intestine and fewer genes in the colon but surprisingly few microbiota-regulated genes required MyD88 signalling. However, MyD88 was essential for microbiota-induced colonic expression of the antimicrobial genes Reg3β and Reg3γ in the epithelium, and Myd88 deficiency was associated with both a shift in bacterial diversity and a greater proportion of segmented filamentous bacteria in the small intestine. In addition, conventionally raised Myd88-/- mice had increased expression of antiviral genes in the colon, which correlated with norovirus infection in the colonic epithelium.ConclusionThis study provides a detailed description of tissue-specific host transcriptional responses to the normal gut microbiota along the length of the gut and demonstrates that the absence of MyD88 alters gut microbial ecology

Use of Ceftriaxone in Treating Cognitive and Neuronal Deficits Associated With Dementia With Lewy Bodies

Dementia with Lewy bodies (DLB) is caused by accumulation of Lewy bodies, destruction of mitochondria, and excess of glutamate in synapses, which eventually leads to excitotoxicity, neurodegeneration, and cognitive impairments. Ceftriaxone (CEF) reduces excitotoxicity by increasing glutamate transporter 1 expression and glutamate reuptake. We investigated whether CEF can prevent cognitive decline and neurological deficits and increase neurogenesis in DLB rats. Male Wistar rats infused with viral vector containing human alpha-synuclein (α-syn) gene, SNCA, in the lateral ventricle were used as a rat model of DLB. CEF (100 mg/kg/day, i.p.) was injected in these rats for 27 days. The active avoidance test and object recognition test was performed. Finally, the brains of all the rats were immunohistochemically stained to measure α-syn, neuronal density, and newborn cells in the hippocampus and substantia nigra. The results revealed that DLB rats had learning and object recognition impairments and exhibited cell loss in the nigrostriatal dopaminergic system, and hippocampal CA1, and dentate gyrus (DG). Additionally, DLB rats had fewer newborn cells in the DG and substantia nigra pars reticulata and more α-syn immune-positive cells in the DG. Treatment with CEF improved cognitive function, reduced cell loss, and increased the number of newborn cells in the brain. To our knowledge, this is the first study showing that CEF prevents loss of neurogenesis in the brain of DLB rats. CEF may therefore has clinical potential for treating DLB

Microbial regulation of Insulin-like peptide 5 and its implication on metabolism and bariatric surgery

The microbial community in our gastrointestinal tract, the gut microbiota, has great impact on our physiology. Particularly, the role for gut microbiota in host health and disease has been associated with modulation of gut hormones which are key players in the regulation of energy homeostasis. Recently, a new gut hormone, insulin-like peptide (INSL5) has been identified. In this thesis, we have studied the microbial regulation of INSL5 and its role on metabolism. Bariatric surgery is the most effective treatment for obesity and obesity-related diseases such as type 2 diabetes. There is increasing evidence that supports a role for gut hormones and gut microbiota in mediating the beneficial effects of bariatric surgery. Thus, in this thesis, we also investigated whether INSL5 and the gut microbiota directly contributes to the metabolic improvements following the bariatric procedure called vertical sleeve gastrectomy (VSG). In paper I, we found that Insl5 expression is higher in the colon of germ-free mice (mice that lack a microbiota), compared with their conventionally-raised control animals. We demonstrated that the elevated Insl5 expression in GF mice is a response to low energy levels, which could be restored by increasing the energy availability. In addition, we found that mice lacking INSL5 have slightly impaired hepatic glucose production during fasting. Thus we speculate that INSL5 might play a role in low energy conditions. In paper II, we observed that circulating fasting INSL5 levels were increased in human individuals following VSG. The high INSL5 levels were declined upon a meal test, suggesting a postprandial response. To test whether INSL5 contributes to the beneficial effects mediated by VSG, we performed VSG surgeries on wild-type and Insl5-knockout mice. The metabolic improvements in both groups of mice were similar after VSG. Therefore, we conclude that INSL5 is not required for the beneficial effects observed after VSG. In paper III, we characterized the longitudinal changes of the human gut microbiota after VSG, and we found that VSG strongly altered the microbiota composition. We showed that by transferring the VSG-altered gut microbiota from humans to mice, we also transferred the improvements in metabolic effects of VSG patients. We also showed that VSG surgery produced greater metabolic improvements in mice having a normal microbiota compared with germ-free mice. These results indicate that the gut microbiota is directly contributing to the beneficial effects mediated by VSG. In conclusion, INSL5 is a microbially regulated gut hormone which promotes hepatic glucose production during low energy conditions. INSL5 is also a gut hormone which increases after fasting following sleeve gastrectomy in humans, but it appears not to contribute to the beneficial effects observed after sleeve gastrectomy in mice. However, the gut microbiota plays an important role for the metabolic improvements mediated by sleeve gastrectomy

A study on usage of knowledge management tools in Singapore.

This research identifies that organizational culture is the only organizational factor that determines the successful implementation of KM tools, and IT firm are found to be more sucessful in the implementation of KM tools compared to non-IT firms

Insulin-like peptide 5 is a microbially regulated peptide that promotes hepatic glucose production

Objective: Insulin-like peptide 5 (INSL5) is a recently identified gut hormone that is produced predominantly by L-cells in the colon, but its function is unclear. We have previously shown that colonic expression of the gene for the L-cell hormone GLP-1 is high in mice that lack a microbiota and thus have energy-deprived colonocytes. Our aim was to investigate if energy deficiency also affected colonic Insl5 expression and to identify a potential role of INSL5. Methods: We analyzed colonic Insl5 expression in germ-free (GF), conventionally raised (CONV-R), conventionalized (CONV-D) and antibiotic-treated mice, and also assessed the effect of dietary changes on colonic Insl5 expression. In addition, we characterized the metabolic phenotype of Insl5−/− mice. Results: We showed that colonic Insl5 expression was higher in GF and antibiotic-treated mice than in CONV-R mice, whereas Insl5 expression in the brain was higher in CONV-R versus GF mice. We also observed that colonic Insl5 expression was suppressed by increasing the energy supply in GF mice by colonization or high-fat feeding. We did not observe any differences in food intake, gut transit or oral glucose tolerance between Insl5−/− and wild-type mice. However, we showed impaired intraperitoneal glucose tolerance in Insl5−/− mice. We also observed improved insulin tolerance and reduced hepatic glucose production in Insl5−/− mice. Conclusions: We have shown that colonic Insl5 expression is regulated by the gut microbiota and energy availability. We propose that INSL5 is a hormone that could play a role in promoting hepatic glucose production during periods of energy deprivation. Keywords: Insulin-like peptide 5 (INSL5), Gut microbiota, Liver, Colo

Microbially produced glucagon-like peptide 1 improves glucose tolerance in mice

Objective: The enteroendocrine hormone glucagon-like peptide 1 (GLP-1) is an attractive anti-diabetic therapy. Here, we generated a recombinant Lactococcus lactis strain genetically modified to produce GLP-1 and investigated its ability to improve glucose tolerance in mice on chow or high-fat diet (HFD). Methods: We transformed L. lactis FI5876 with either empty vector (pUK200) or murine GLP-1 expression vector to generate LL-UK200 and LL-GLP1, respectively, and determined their potential to induce insulin secretion by incubating primary islets from wild-type (WT) and GLP-1 receptor knockout (GLP1R-KO) mice with culture supernatant of these strains. In addition, we administered these strains to mice on chow or HFD. At the end of the study period, we measured plasma GLP-1 levels, performed intraperitoneal glucose tolerance and insulin tolerance tests, and determined hepatic expression of the gluconeogenic genes G6pc and Pepck. Results: Insulin release from primary islets of WT but not GLP1R-KO mice was higher following incubation with culture supernatant from LL-GLP1 compared with LL-UK200. In mice on chow, supplementation with LL-GLP1 versus LL-UK200 promoted increased vena porta levels of GLP-1 in both WT and GLP1R-KO mice; however, LL-GLP1 promoted improved glucose tolerance in WT but not in GLP1R-KO mice, indicating a requirement for the GLP-1 receptor. In mice on HFD and thus with impaired glucose tolerance, supplementation with LL-GLP1 versus LL-UK200 promoted a pronounced improvement in glucose tolerance together with increased insulin levels. Supplementation with LL-GLP1 versus LL-UK200 did not affect insulin tolerance but resulted in reduced expression of G6pc in both chow and HFD-fed mice. Conclusions: The L. lactis strain genetically modified to produce GLP-1 is capable of stimulating insulin secretion from islets and improving glucose tolerance in mice. Keywords: Lactococcus lactis, Glucose tolerance, Recombinant bacteria, GLP-

Implications of Continuous Noninvasive Finger Cuff Arterial Pressure Device Use during Cesarean Delivery for Goal-Directed Fluid Therapy Preload Optimization: A Randomized Controlled Trial

Background. Although fixed-volume conventional fluid preloading protocol fails to attenuate postspinal hypotension during cesarean delivery, the effect of goal-directed fluid therapy (GDFT) remains less explored. Continuous noninvasive finger cuff arterial pressure monitoring using devices such as the ClearSight System can provide the noninvasive stroke volume value, enabling clinicians to perform GDFT before spinal anesthesia; however, the efficacy of GDFT requires further elucidation. Method. In total, 71 consecutive full-term pregnant women were randomly divided into a control group (n=34) and a GDFT group (n=37). Before spinal anesthesia, the control group received a fixed dose (1000 mL) of crystalloid fluid, but the GDFT group received repeated 3 mL/kg body weight of crystalloid fluid challenges within 3 minutes with a 1-minute interval between each fluid challenge based on the stroke volume incremental changes obtained using the ClearSight System (targeting a stroke volume increase of ≥5% after a fluid challenge). The primary outcome was the incidence of postspinal hypotension. The secondary outcomes were total fluid volume, vasopressor dosage, hemodynamic parameter changes, maternal adverse effects, and neonatal profiles. Result. Women in the GDFT group received more fluid than did those in the control group (1132±108 vs. 1247±202 mL; p=0.0044), but the incidence of postspinal hypotension (79.4% vs. 73.0%,; p=0.5864) and norepinephrine dose (12.5±10.6 vs. 15.1±12.8 mcg, respectively; p=0.3512) was comparable between the two groups. Fewer women in the GDFT group experienced nausea (61.76% vs. 35.14%; p=0.0332). Neonatal outcomes (Apgar score and umbilical blood analysis) were comparable and typical in both groups. Conclusion. ClearSight-guided GDFT did not ameliorate postspinal hypotension but may reduce nausea. This trial is registered with NCT03013140

Applying magnetic-responsive nanocatalyst-liquid interface for active molecule manipulation to boost catalysis beyond diffusion limit

Efficient nanocatalysis requires swift delivery of reactants to catalytic sites, but the presence of diffusion-dominated, hydrodynamic boundary layers on all heterogeneous catalysts impedes fast chemical transformation. Here, efficient nanocatalysis is achieved by applying a magnetic-responsive nanocatalyst-liquid interface to create a vortex-like flow that rapidly pulls reactants from bulk solution to the catalyst, beyond the diffusion limit. Consequently, our design attains a >90 % degradation efficiency in 10-fold and 30-fold faster than traditional homogenization methods, respectively. This unique molecule delivery design will complement recent advances in active catalytic nanomaterials to realize ideal nanocatalysis in emerging chemical, energy, and environmental applications.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Nanyang Technological UniversitySubmitted/Accepted versionH.K.L. thanks the funding supports from Singapore Ministry of Education (AcRFTier 1 RS13/20 and RG4/21), Agency of Science, Technology and Research, Singapore (A*STAR; AME YIRG A2084c0158), and Nanyang Technological University start-up grants