Intestinal Flora is a Key Factor in Insulin Resistance and Contributes to the Development of Polycystic Ovary Syndrome.

CONTEXT: The key gut microbial biomarkers for polycystic ovarian syndrome (PCOS) and how dysbiosis causes insulin resistance and PCOS remain unclear. OBJECTIVE: To assess the characteristics of intestinal flora in PCOS and explore whether abnormal intestinal flora can affect insulin resistance and promote PCOS and whether chenodeoxycholic acid (CDCA) can activate intestinal farnesoid X receptor (FXR), improving glucose metabolism in PCOS. SETTING AND DESIGN: The intestinal flora of treatment-naïve PCOS patients and hormonally healthy controls was analyzed. Phenotype analysis, intestinal flora analysis, and global metabolomic profiling of caecal contents were performed on a letrozole-induced PCOS mouse model; similar analyses were conducted after 35 days of antibiotic treatment on the PCOS mouse model, and glucose tolerance testing was performed on the PCOS mouse model after a 35-day CDCA treatment. Mice receiving fecal microbiota transplants from PCOS patients or healthy controls were evaluated after 10 weeks. RESULTS: Bacteroides was significantly enriched in treatment-naïve PCOS patients. The enrichment in Bacteroides was reproduced in the PCOS mouse model. Gut microbiota removal ameliorated the PCOS phenotype and insulin resistance and increased relative FXR mRNA levels in the ileum and serum fibroblast growth factor 15 levels. PCOS stool-transplanted mice exhibited insulin resistance at 10 weeks but not PCOS. Treating the PCOS mouse model with CDCA improved glucose metabolism. CONCLUSIONS: Bacteroides is a key microbial biomarker in PCOS and shows diagnostic value. Gut dysbiosis can cause insulin resistance. FXR activation might play a beneficial rather than detrimental role in glucose metabolism in PCOS.

[A machine learning model based on initial gut microbiome data for predicting changes of Bifidobacterium after prebiotics consumption].

OBJECTIVE: To investigate the effects of prebiotics supplementation for 9 days on gut microbiota structure and function and establish a machine learning model based on the initial gut microbiota data for predicting the variation of Bifidobacterium after prebiotic intake. METHODS: With a randomized double-blind self-controlled design, 35 healthy volunteers were asked to consume fructo-oligosaccharides (FOS) or galacto-oligosaccharides (GOS) for 9 days (16 g per day). 16S rRNA gene high-throughput sequencing was performed to investigate the changes of gut microbiota after prebiotics intake. PICRUSt was used to infer the differences between the functional modules of the bacterial communities. Random forest model based on the initial gut microbiota data was used to identify the changes in Bifidobacterium after 5 days of prebiotic intake and then to build a continuous index to predict the changes of Bifidobacterium. The data of fecal samples collected after 9 days of GOS intervention were used to validate the model. RESULTS: Fecal samples analysis with QIIME revealed that FOS intervention for 5 days reduced the intestinal flora alpha diversity, which rebounded on day 9; in GOS group, gut microbiota alpha diversity decreased progressively during the intervention. Neither FOS nor GOS supplement caused significant changes in ß diversity of gut microbiota. The area under the curve (AUC) of the prediction model was 89.6%. The continuous index could successfully predict the changes in Bifidobacterium (R=0.45, P=0.01), and the prediction accuracy was verified by the validation model (R=0.62, P=0.01). CONCLUSION: Short-term prebiotics intervention can significantly decrease α-diversity of the intestinal flora. The machine learning model based on initial gut microbiota data can accurately predict the changes in Bifidobacterium, which sheds light on personalized nutrition intervention and precise modulation of the intestinal flora.

Cronobacter carriage in neonate and adult intestinal tracts.

A total of 7 Cronobacter strains were isolated from 703 fecal samples collected in Jinan from June 13 to December 30, 2011, with the positive rate of Cronobacter spp. being 1.0% (95% confidence interval 0.6%-1.4%). Three Cronobacter sakazakii stains were isolated from 157 fecal samples of healthy neonates (95% confidence interval 0.4%-5.5%). This number was slightly higher than that isolated from 273 fecal samples of healthy adults, in which 1 strain of C. sakazakii and 1 strain of Cronobacter malonaticus were isolated, and that from 173 fecal samples of adults with acute diarrhea, in which 1 strain of C. sakazakii and 1 strain of C. malonaticus were isolated, but the differences were not statistically significant (P>0.05). The Cronobacter isolates were all from different genetic sources. It should be noted that Cronobacter carriage may cause infection under certain conditions, especially in neonates.

[Plasma membrane-related Ca(2+)-ATPase-1 gene silencing promotes insulin secretion in islet beta cells NIT].

OBJECTIVE: To assess the effect of RNA interference-mediated gene silencing of plasma membrane-related Ca(2+)-ATPase-1 (PMR1) gene on the insulin secretion in islet beta cells NIT-1 in vitro. METHODS: A small interfering RNA duplex (siPMR1) corresponding to the nucleotides 337-357 of mouse PMR1 cDNA was introduced into NIT-1 cells via liposomes. The gene silencing effect was assessed by RT-PCR, and the total insulin level in the transfected cells was measured by radioimmunoassay. RESULTS: Transfection with siPMR1 resulted in obviously reduced PMR1 expression and increased insulin secretion in NIT-1 cells. CONCLUSION: The synthesized siPMR1 can significantly silence the expression of PMR1 and promote the secretion of insulin in the islet cells in vitro, which shed light on further studies of RNAi-based therapy of diabetes.

[High glucose lowers insulin receptor substrate 2 expression and induces apoptosis in mouse islet cells in vitro].

OBJECTIVE: To investigate the role of insulin receptor substrate 2 (IRS2) and Bax on mouse islet cell apoptosis in the presence of high glucose in vitro. METHODS: The pancreatic islet cells were isolated from Kunming mice and divided into 6 groups (G1-G6 groups) for a 72-h culture in the media containing different concentrations of glucose (5.6, 7.8, 11.1, 16.7, 22.2, and 27.6 mmol/L, respectively). Insulin secretion by the cells was evaluated by radioimmunoassay, and the expressions of IRS2 and Bax were detected using immunocytochemistry and immunofluorescence assay, respectively. Hoechst33342 staining was employed to observe the cell apoptosis. RESULTS: Exposure to 5.6-11.1 mmol/L glucose resulted in increased insulin secretion and progressive elevation of IRS2 and Bax expression, whereas the cell apoptosis underwent no obvious changes. In the presence of glucose above 16.7 mmol/L, the percentages of apoptotic islet cells increased with glucose concentration, but insulin secretion and IRS2 expression decreased; Bax expression significantly increased in the presence of high-concentration glucose. CONCLUSION: Prolonged exposure of mouse islet cells to high glucose induces apoptosis and impairs insulin secretion of the cells. Decreased IRS2 expression and increased Bax expression may play an important role in the glucotoxicity in mouse islet cells.

[Effects of sustained-release alpha-lipoic acid tablet on blood lipid, blood sugar and insulin in hyperlipidemic New Zealand rabbits].

OBJECTIVE: To evaluate the effect of sustained-release alpha-lipoic acid tablets (SRLA) on blood lipid, glucose and insulin levels in hyperlipidemic New Zealand rabbits. METHODS: Twenty-four New Zealand rabbits were randomized into normal diet group, high-fat diet group, and high-fat diet + SRLA (300 mg/tablet) group with corresponding feed. At the beginning and 4 weeks after the feeding, the serum levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), blood glucose, and serum insulin were measured, and insulin sensitivity index (ISI) was calculated. RESULTS: Four weeks after feeding with high-fat diet, the insulin levels was elevated and the ISI lowered in the New Zealand rabbits, indicating successful establishment of the animal model of hyperlipidemia. Compared with the high-fat diet group, the serum levels of TG, TC, LDL-C and insulin were significantly reduced (P<0.05), and the ISI was significantly increased (P<0.05) in high fat diet + SRLA group. But no statistically significant difference was found in the blood glucose among the 3 groups. CONCLUSION: SRLA can significantly correct blood lipid and insulin disorders in hyperlipidemic New Zealand rabbits and prevent the occurrence of insulin resistance and hyperlipidemia.

[High-performance liquid chromatography for determining plasma alpha-lipoic acid in New Zealand rabbits].

OBJECTIVE: To establish a method for determining the content of alpha-lipoic acid in New Zealand rabbit plasma. METHODS: Alpha-lipoic acid in the plasma samples was purified by solid-phase extractor and analyzed on an HYPERSIL C18 column with isocratic mobile phase consisting of potassium dihydrogen phosphate-acetonitrile (50:50, v/v) at a flow rate of 1.0 ml/min and detection wavelength of 230 nm. RESULTS: The standard curve was linear in the range of 5-100 microg/L (r=1) and the average recovery was 77.4%-82.1%. The relative standard deviations of intra-day and inter-day assay were within 1.5%-8.9%. CONCLUSION: The method is sensitive, accurate and simple for determining plasma alpha-lipoic acid levels in New Zealand rabbits.