Effects of nano titanium dioxide on gut microbiota based on human digestive tract microecology simulation system in vitro / 北京大学学报(医学版)

OBJECTIVE@#To explore the effects of oral exposure to titanium dioxide nanoparticles (TiO2 NPs) on the composition and structure of human gut microbiota.@*METHODS@#The particle size, shape, crystal shape and degree of agglomeration in ultrapure water of TiO2 NPs were characterized. The in vitro human digestive tract microecological simulation system was established by simulating the fluid environment and physical conditions of stomach, small intestine and colon, and the stability of the simulation system was evaluated. The bacterial communities were extracted from human feces and cultured stably in the simulated system. They were exposed to 0, 20, 100 and 500 mg/L TiO2 NPs, respectively, and the bacterial fluids were collected after 24 h of exposure. The effect of TiO2 NPs on the composition and structure of human gut microbiota was analyzed by 16S rRNA sequencing technology. Linear discriminant analysis effect size (LEfSe) was used to screen differential bacteria, and the Kyoto encyclopedia of genes and genomes (KEGG) database for functional prediction.@*RESULTS@#The spherical and anatase TiO2 NPs were (25.12±5.64) nm in particle size, while in ultra-pure water hydrated particle size was (609.43±60.35) nm and Zeta potential was (-8.33±0.22) mV. The in vitro digestive tract microecology simulation system reached a relatively stable state after 24 hours, and the counts of Enterococci, Enterobacte-rium, and Lactobacillus reached (1.6±0.85)×107, (5.6±0.82)×107 and (2.7±1.32)×107, respectively. 16S rRNA sequencing results showed that compared with the control group, the number and evenness of gut microbiota were not significantly affected at phylum, class, order, family and genus levels in TiO2 NPs groups (20, 100 and 500 mg/L). The relative abundance of some species was significantly changed, and a total of 42 different bacteria were screened between the TiO2 NPs groups (20, 100 and 500 mg/L) and the control group [linear discriminant analysis(LDA) score>3], represented by Enterobacter, Bacteroidaceae, Lactobacillaceae, Bifidobacteriaceae and Clostridium. Further predictive analysis of gut microbiota function showed that TiO2 NPs might affect oxidative phosphorylation, energy meta-bolism, phosphonate and phosphonate metabolism, and methane metabolism (P < 0.05).@*CONCLUSION@#In human digestive tract microecological simulation system, TiO2 NPs could significantly change the composition and structure of human gut microbiota, represented by Enterobacter and probiotics, and may further affect a variety of metabolism and function of the body.

Effects of titanium dioxide nanoparticles on fecal metabolome in rats after oral administration for 90 days / 北京大学学报(医学版)

OBJECTIVE@#To explore the effects and related mechanisms of oral exposure titanium dioxide nanoparticles (TiO2 NPs) for 90 days on the intestinal and the gut microbiota of rats, through fecal metabolomics.@*METHODS@#Twelve 4-week-old clean-grade Sprague Dawley (SD) rats were randomly de-vided into 2 groups by body weight, treated with TiO2 NPs at dose of 0 or 50 mg/kg body weight everyday respectively for 90 days. The solution of each infection was freshly prepared and shocked fully by ultrasonic. Characterization of the particle size, crystal form, purity, and specific surface area of TiO2 NPs was conducted. And the fresh feces of the rats were collected on the 90th day. After lyophilized and hydrophilic phase extraction, ultra performance liquid chromatography-Q-exactive orbitrap-high-resolution mass spectrometry system (UPLC-QEMS) was utilized for non-targeted determination of fecal meta-bolites. The metabolites were identified and labeled through Compound Discoverer 3.0 software, and used for subsequent metabolomics analysis. Bioinformatics analysis was carried out including unsupervised principal component analysis and supervised orthogonal projection to latent structure discriminant analysis for the differential metabolites between the two groups. The differential metabolites were followed-up for Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis.@*RESULTS@#Compared with the control group, the body weight of the rats was significantly reduced (P<0.05) in the treatment group. A total of 22 metabolites in fecal metabolomics showed significant changes. Among them, xanthine, 1-methyladenine, 3-hydroxypyridine, methionine sulfoxide, pyridoxine, 1,5-isoquinolinediol, N-acetylornithine, N-acetyl-D-galactosamine, L-citrulline, L-methionine, leucine, DL-tryptophan, L-ornithine, 4-methyl-5-thiazoleethanol, and L-glutamic acid totaled 15 metabolites increased significantly. N-acetylhistamine, D-pipecolinic acid, imidazolelactic acid, L-valine, 2,3,4,6-tetramethylpyrazine, caprolactam, and histamine totaled 7 metabolites decreased significantly. N-acetylhistamine, L-valine and methionine sulfoxide were changed more than 16 times. Analysis of KEGG pathway revealed that the two metabolic pathways arginine biosynthesis and aminoacyl-tRNA biosynthesis were significantly changed (false discover rate < 0.05, pathway impact > 0.1).@*CONCLUSION@#Oral exposure to TiO2 NPs for 90 days could disrupt the metabolism of the intestine and gut microbiota, causing significant changes in metabolites and metabolic pathways which were related to inflammatory response, oxidative stress, glucose homeostasis, blood system and amino acid homeostasis in rat feces. It is suggested that the toxic effect of TiO2 NPs on rats may be closely related to intestinal and gut microbiota metabolism.

C-reactive protein/albumin ratio as a novel inflammation-based prognostic index for predicting outcomes of patients with colorectal cancer / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the association of C-reactive protein/albumin ratio (CAR) with the prognosis of patients with colorectal cancer and compare the prognostic value of CAR with other inflammation-based prognostic scoring systems.</p><p><b>METHODS</b>We retrospectively evaluated 163 newly diagnosed colorectal cancer patients in Nanfang Hospital between January, 2007 and December, 2014. All recommended cutoff values of the clinicopathological factors were defined using receiver- operating characteristic (ROC) curve analyses. We evaluated the prognostic value of CAR in comparison with Glasgow Prognostic Score (GPS) and neutrophil lymphocyte ratio (NLR) with the area under the ROC curve. Univariate and multivariate analyses using the Cox proportional hazards model were performed to identify the factors closely associated with overall survival of the patients. Kaplan-Meier analysis was used to compare overall survival curves between patients with a high CAR and those with a low CAR.</p><p><b>RESULTS</b>The recommended cutoff value of CAR was 0.132. Kaplan-Meier analysis and log rank test demonstrated a significant difference in the overall survival between patients with a low CAR (<0.132) and those with a high CAR (≥0.132) (2157.0∓395.3 vs 1661.0∓136.4 days, P<0.001). The area under the ROC curve of CAR, NLR and GPS was 0.656, 0.550 and 0.642, respectively, indicating a better prognostic value of CAR. Univariate analyses showed that age, C-reactive protein, albumin, CAR, NLR, GPS, platelet, TMN stage, Dukes stage and chemotherapy regimens were associated with the overall survival of the patients (P<0.05). Multivariate analyses showed that TMN stage [HR=1.689 (95%CI: 1.146-2.488), P=0.008] and Dukes stage [HR=2.447 (95%CI: 1.349-4.441), P=0.003] were associated with the overall survival of the patients.</p><p><b>CONCLUSIONS</b>Similar to the previously reported inflammation-based prognostic systems (GPS and NLR), CAR is useful for predicting the survival of patients with colorectal cancer and can be complementary to the two prognostic scoring systems.</p>