Linjing Zhao

Distinct urinary metabolic profile of human colorectal cancer.

A full spectrum of metabolic aberrations that are directly linked to colorectal cancer (CRC) at early curable stages is critical for developing and deploying molecular diagnostic and therapeutic approaches that will significantly improve patient survival. We have recently reported a urinary metabonomic profiling study on CRC subjects (n = 60) and health controls (n = 63), in which a panel of urinary metabolite markers was identified. Here, we report a second urinary metabonomic study on a larger cohort of CRC (n = 101) and healthy subjects (n = 103), using gas chromatography time-of-flight mass spectrometry and ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry. Consistent with our previous findings, we observed a number of dysregulated metabolic pathways, such as glycolysis, TCA cycle, urea cycle, pyrimidine metabolism, tryptophan metabolism, polyamine metabolism, as well as gut microbial-host co-metabolism in CRC subjects. Our findings confirm distinct urinary metabolic footprints of CRC patients characterized by altered levels of metabolites derived from gut microbial-host co-metabolism. A panel of metabolite markers composed of citrate, hippurate, p-cresol, 2-aminobutyrate, myristate, putrescine, and kynurenate was selected, which was able to discriminate CRC subjects from their healthy counterparts. A receiver operating characteristic curve (ROC) analysis of these markers resulted in an area under the receiver operating characteristic curve (AUC) of 0.993 and 0.998 for the training set and the testing set, respectively. These potential metabolite markers provide a novel and promising molecular diagnostic approach for the early detection of CRC.

Melamine-Induced Renal Toxicity Is Mediated by the Gut Microbiota

Melamine is converted to cyanuric acid by the gut microbe Klebsiella, leading to melamine-cyanurate-urate coprecipitation that is associated with nephrotoxicity. An Unwitting Microbial Culprit in Melamine Toxicity? A tragic incident in China in 2008 involving the deliberate and illicit supplementation of milk with melamine resulted in the deaths of children from renal failure and highlighted the toxicity of this compound. In a new study, Zheng et al. study the toxicity of melamine in rats and report that microbial metabolism of melamine is crucial for forming the key metabolite that causes kidney damage. They discover that a species of Klebsiella can form cyanuric acid from melamine, which then forms complex precipitates that lead to kidney stone formation. The gut microbiota in general play an important role in human health and are known to affect the metabolism and toxicity of a number of drugs. The new findings suggest that individual variation in the gut microbial composition of children exposed to melamine may have been important in the observed patterns of mortality in exposed individuals. Melamine poisoning has become widely publicized after a recent occurrence of renal injury in infants and children exposed to melamine-tainted milk in China. This renal damage is believed to result from kidney stones formed from melamine and uric acid or from melamine and its cocrystallizing chemical derivative, cyanuric acid. However, the composition of the stones and the mechanism by which the stones are formed in the renal tubules are unknown. We report that cyanuric acid can be produced in the gut by microbial transformation of melamine and serves as an integral component of the kidney stones responsible for melamine-induced renal toxicity in rats. Melamine-induced toxicity in rats was attenuated and melamine excretion increased after antibiotic suppression of gut microbial activity. We further demonstrated that melamine is converted to cyanuric acid in vitro by bacteria cultured from normal rat feces; Klebsiella was subsequently identified in fecal samples by 16S ribosomal DNA sequencing. In culture, Klebsiella terrigena was shown to convert melamine to cyanuric acid directly. Rats colonized by K. terrigena showed exacerbated melamine-induced nephrotoxicity. Cyanuric acid was detected in the kidneys of rats administered melamine alone, and the concentration after Klebsiella colonization was increased. These findings suggest that the observed toxicity of melamine may be conditional on the exact composition and metabolic activities of the gut microbiota.

Metabonomics identifies serum metabolite markers of colorectal cancer.

Recent studies suggest that biofluid-based metabonomics may identify metabolite markers promising for colorectal cancer (CRC) diagnosis. We report here a follow-up replication study, after a previous CRC metabonomics study, aiming to identify a distinct serum metabolic signature of CRC with diagnostic potential. Serum metabolites from newly diagnosed CRC patients (N = 101) and healthy subjects (N = 102) were profiled using gas chromatography time-of-flight mass spectrometry (GC-TOFMS) and ultraperformance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS). Differential metabolites were identified with statistical tests of orthogonal partial least-squares-discriminant analysis (VIP > 1) and the Mann-Whitney U test (p < 0.05). With a total of 249 annotated serum metabolites, we were able to differentiate CRC patients from the healthy controls using an orthogonal partial least-squares-discriminant analysis (OPLS-DA) in a learning sample set of 62 CRC patients and 62 matched healthy controls. This established model was able to correctly assign the rest of the samples to the CRC or control groups in a validation set of 39 CRC patients and 40 healthy controls. Consistent with our findings from the previous study, we observed a distinct metabolic signature in CRC patients including tricarboxylic acid (TCA) cycle, urea cycle, glutamine, fatty acids, and gut flora metabolism. Our results demonstrated that a panel of serum metabolite markers is of great potential as a noninvasive diagnostic method for the detection of CRC.

Phylogenetic analysis of intestinal bacteria in the Chinese mitten crab (Eriocheir sinensis)

Aims:  To identify the dominant intestinal bacteria in the Chinese mitten crab, and to investigate the differences in the intestinal bacteria between pond‐raised and wild crabs.

The in vivo and in vitro study of polysaccharides from a two-herb formula on ulcerative colitis and potential mechanism of action.

ETHNOPHARMACOLOGICAL RELEVANCE Lycium barbarum and Astragalus membranaceus are two traditional medicinal herbs widely used in China for nourishing Yin and reinforcing Qi. The purpose of the study was to investigate the prophylactic and curative effects of crude polysaccharides (QHPS) extracted from a two-herb formula composed of Lycium barbarum and Astragalus membranaceus at a ratio of 2:3 in colitis rats, and to further elucidate the potential mechanism of action in epithelial cell proliferation in vitro. MATERIALS AND METHODS An acetic acid (AA)-induced ulcerative colitis rat model was applied in the study. Two independent protocols were used to assess the prophylactic and curative effects of QHPS, respectively, in which rats were either pre-treated with QHPS (0.18g/kg) for 14 days prior to AA induction, or post-treated with QHPS for 7 days after AA induction. The stool consistency and weight loss were used to evaluate disease activity. The morphological changes in intestinal mucosa at the end of the experiments were observed. The serum levels of endotoxin (EDT), diamine oxidase (DAO) and d-lactate (DLA), important biochemical markers for evaluating intestinal mucosal structure and function, were measured. In the in vitro mechanistic studies, rat intestinal epithelial cells (IEC-6) were used to access for epithelium regeneration. RESULTS The intra-colonic instillation of AA induced ulcerative colitis in rat, as indicated by diarrhea, weight loss, and colonic mucosal damage. Both prophylactic and curative treatments effectively reduced the weight loss and diarrhea and attenuated the colonic mucosal damage associated with inducible colitis. The significant increase in serum levels of DAO, DLA and EDT was induced by AA and inhibited by QHPS treatment. Moreover, QHPS could significantly stimulate IEC-6 proliferation in a dose-dependent manner (p<0.05). CONCLUSION The present study indicated for the first time that polysaccharides extracted from this two-herb formula can protect against experimental ulcerative colitis, presumably by promoting the recovery of the intestinal barrier.

Metabolic Signatures of Kidney Yang Deficiency Syndrome and Protective Effects of Two Herbal Extracts in Rats Using GC/TOF MS

Kidney Yang Deficiency Syndrome (KDS-Yang), a typical condition in Chinese medicine, shares similar clinical signs of the glucocorticoid withdrawal syndrome. To date, the underlying mechanism of KDS-Yang has been remained unclear, especially at the metabolic level. In this study, we report a metabolomic profiling study on a classical model of KDS-Yang in rats induced by hydrocortisone injection to characterize the metabolic transformation using gas chromatography/time-of-flight mass spectrometry. WKY1, a polysaccharide extract from Astragalus membranaceus and Lycium barbarum, and WKY2, an aqueous extract from a similar formula containing Astragalus membranaceus, Lycium barbarum, Morinda officinalis, Taraxacum mongolicum, and Cinnamomum cassia presl, were used separately for protective treatments of KDS-Yang. The changes of serum metabolic profiles indicated that significant alterations of key metabolic pathways in response to abrupt hydrocortisone perturbation, including decreased energy metabolism (lactic acid, acetylcarnitine), lipid metabolism (free fatty acids, 1-monolinoleoylglycerol, and cholesterol), gut microbiota metabolism (indole-3-propionic acid), biosynthesis of catecholamine (norepinephrine), and elevated alanine metabolism, were attenuated or normalized with different degrees by the pretreatment of WKY1 or WKY2, which is consistent with the observations in which the two herbal agents could ameliorate biochemical markers of serum cortisone, adrenocorticotropic (ACTH), and urine 17-hydroxycorticosteroids (17-OHCS).

Investigation into in vitro and in vivo models using intestinal epithelial IPEC-J2 cells and Caenorhabditis elegans for selecting probiotic candidates to control porcine enterotoxigenic Escherichia coli.

To identify a fast, economic and reliable method for preselecting lactic acid‐producing bacterial (LAB) isolates to control enterotoxigenic Escherichia coli (ETEC).

A panel of free fatty acid ratios to predict the development of metabolic abnormalities in healthy obese individuals.

Increasing evidences support that metabolically healthy obese (MHO) is a transient state. However, little is known about the early markers associated with the development of metabolic abnormalities in MHO individuals. Serum free fatty acids (FFAs) profile is highlighted in its association with obesity-related insulin resistance, type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD). To examine the association of endogenous fatty acid metabolism with future development of metabolic abnormalities in MHO individuals, we retrospectively analyzed 24 [product FFA]/[precursor FFA] ratios in fasting sera and clinical data from 481 individuals who participated in three independent studies, including 131 metabolic healthy subjects who completed the 10-year longitudinal Shanghai Diabetes Study (SHDS), 312 subjects cross-sectionally sampled from the Shanghai Obesity Study (SHOS), and 38 subjects who completed an 8-week very low carbohydrate diet (VLCD) intervention study. Results showed that higher baseline level of oleic acid/stearic acid (OA/SA), and lower levels of stearic acid/palmitic acid (SA/PA) and arachidonic acid/dihomo-γ-linolenic acid (AA/DGLA) ratios were associated with higher rate of MHO to MUO conversion in the longitudinal SHDS. Further, the finding was validated in the cross-sectional and interventional studies. This panel of FFA ratios could be used for identification and early intervention of at-risk obese individuals.

Serum stearic acid/palmitic acid ratio as a potential predictor of diabetes remission after Roux-en-Y gastric bypass in obesity

Endogenous fatty acid metabolism that results in elongation and desaturation lipid products is thought to play a role in the development of type 2 diabetes mellitus (T2DM). In this study, we evaluated the potential of estimated elongase and desaturase activities for use as predictive markers for T2DM remission after Roux‐en‐Y gastric bypass (RYGB). The results of a targeted metabolomics approach from 2 independent studies were used to calculate 24 serum FA concentration ratios (product/precursor). Gene expression data from an open public data set was also analyzed. In a longitudinal study of 38 obese diabetic patients with RYGB, we found higher baseline stearic acid/palmitic acid (S/P) ratio. This ratio reflects an elovl6‐encoded elongase enzyme activity that has been found to be associated with greater possibility for diabetes remission after RYGB [odds ratio, 2.16 (95% CI 1.10–4.26)], after adjustment for age, gender, body mass index, diabetes duration, glycosylated hemoglobin A1c, and fasting C‐peptide. Our results were validated by examination of postsurgical elovl6 gene expression in morbidly obese patients. The association of S/P with the metabolic status of obese individuals was further validated in a cross‐sectional cohort of 381 participants. In summary, higher baseline S/P was associated with greater probability of diabetes remission after RYGB and may serve as a diagnostic marker in preoperative patient assessment. —Zhao, L., Ni, Y., Yu, H., Zhang, P., Zhao, A., Bao, Y., Liu, J., Chen, T., Xie, G., Panee, J., Chen, W., Rajani, C., Wei, R., Su, M., Jia, W., Jia, W. Serum stearic acid/palmitic acid ratio as a potential predictor of diabetes remission after Roux‐en‐Y gastric bypass in obesity. FASEB J. 31, 1449–1460 (2017) www.fasebj.org