Urine Proteome Changes in a TNBS-Induced Colitis Rat Model.

PURPOSE: Urine is an important resource for biomarker research. Urine proteins reflect not only renal diseases but also changes in other organs in the body. However, urine has rarely been used to reflect on inflammatory bowel disease. EXPERIMENTAL DESIGN: In the present study, a trinitrobenzene sulfonic acid (TNBS)-induced colitis rat model is used to mimic the human inflammatory bowel disease Crohn's disease (CD). Urine samples are analyzed by label-free and TMT-labeled proteomic quantitative methods. RESULTS: 77 urinary proteins are significantly changed in the colitis rats compared with that in the controls. These proteins are further validated by parallel reaction monitoring (PRM) targeted proteomic quantitative methods. Based on the human protein tissue atlas, carbonic anhydrase 1, ribonuclease pancreatic gamma type, and neutral and basic amino acid transport protein rBAT are highly enriched in the gastrointestinal tract. Among the nine PRM-validated proteins, carbonic anhydrase 1, neutrophil collagenase, and neutrophil gelatinase associated lipocalin were previously reported as IBD-associated proteins (all exhibiting consistent trends with the observation herein), whereas the others are newly discovered by this study. CONCLUSIONS AND CLINICAL RELEVANCE: The results provide valuable clues for future study of urine biomarker of inflammatory bowel disease and Crohn's disease.

High-resolution MS/MS metabolomics by data-independent acquisition reveals urinary metabolic alteration in experimental colitis.

INTRODUCTION: Traditional high-resolution MS1 based untargeted metabolomics suffers from low sensitivity, while low-resolution MS/MS based multiple reaction monitoring increases sensitivity at the cost of metabolite coverage and the mass accuracy. OBJECTIVES: To evaluate and apply the high-resolution MS/MS level untargeted metabolomics. METHODS: SWATH based data-independent acquisition (DIA) was optimized to obtain MS/MS of all precursor ions. RESULTS: SWATH-MS/MS could rescue MS1 obscured or saturated metabolites and potentially provide diagnostic fragments to differentiate isomers. For SWATH-MS/MS, 4944 out of 21492 (23.0%) and 2289 out of 12831 (17.8%) fragment ion features significantly changed (Fold change > 1.5, P < 0.05) between Normal and experimental acute ulcerative colitis (UC) groups in positive and negative ion mode, respectively. For SWATH-MS1, 1022 out of 4818 (21.2%) and 353 out of 2266 (15.6%) features significantly changed in positive and negative ion mode, respectively. By deciphering the metabolite profiles with high-resolution MS/MS, it allows versatile post-acquisition data mining such as open detection of different sub-metabolome. The method revealed a global urinary metabolic alteration and increased glucuronide and sulfate sub-metabolome in UC. The major limitation of untargeted SWATH-MS/MS is increased interferences derived from wider Q1 isolation window. CONCLUSIONS: SWATH-MS/MS is a versatile metabolomics strategy, merging the coverage of high-resolution untargeted metabolomics and the sensitivity of MS/MS.

Modulation of urinary siderophores by the diet, gut microbiota and inflammation in mice.

Mammalian siderophores are believed to play a critical role in maintaining iron homeostasis. However, the properties and functions of mammalian siderophores have not been fully clarified. In this study, we have employed Chrome Azurol S (CAS) assay which is a well-established method for bacterial siderophores study, to detect and quantify mammalian siderophores in urine samples. Our study demonstrates that siderophores in urine can be altered by diet, gut microbiota and inflammation. C57BL/6 mice, fed on plant-based chow diets which contain numerous phytochemicals, have more siderophores in the urine compared to those fed on purified diets. Urinary siderophores were up-regulated in iron overload conditions, but not altered by other tested nutrients status. Further, germ-free mice displayed 50% reduced urinary siderophores, in comparison to conventional mice, indicating microbiota biotransformation is critical in generating or stimulating host metabolism to create more siderophores. Altered urinary siderophores levels during inflammation suggest that host health conditions influence systemic siderophores level. This is the first report to measure urinary siderophores as a whole, describing how siderophores levels are modulated under different physiological conditions. We believe that our study opens up a new field in mammalian siderophores research and the technique we used in a novel manner has the potential to be applied to clinical purpose.

Transient false-positive urine human chorionic gonadotropin in septic shock.

Point-of-care testing for urine human chorionic gonadotropin (hCG) allows rapid diagnosis of pregnancy and pregnancy-related disorders at the bedside. Urine hCG test kits use enzyme-linked immunosorbent assay technology and incorporate 2 types of monoclonal antibody in a sandwich structure. There have been case reports in a variety of disease states reporting interference with this method leading to false-positive results. We describe the case of a nonpregnant female presenting to the emergency department with septic shock secondary to severe colitis. Three sequential urine tests using the Clearview hCG test kit (Alere Limited, Stockport, United Kingdom) yielded positive results, whereas quantitative serum analysis was negative for hCG. This initial test result reverted to a true-negative result after 48 hours, suggesting the transient passage of an interferent into the urine at the time of initial testing. This may have been a molecule produced as part of the host inflammatory response or from bacterial synthesis of an interferent with hCG-like antigenic structure. It is important that clinicians are aware of the mechanisms and limitations of urine hCG testing and maintain a low threshold to undertake early serum hCG testing to confirm diagnosis.

Early detection of renal injury using urinary vanin-1 in rats with experimental colitis.

Renal complications are often detected in patients with inflammatory bowel disease (IBD). Because conventional markers such as serum creatinine and ß2-microglobulin are not sensitive and/or specific, a new renal biomarker is needed. We have recently identified urinary vanin-1 as an early biomarker for the detection of nephrotoxicant-induced renal injury. In this study, we compared the usefulness of urinary vanin-1 with other newly developed biomarkers [urinary monocyte chemoattractant protein-1 (MCP-1), kidney injury molecule-1 (Kim-1) and N-acetyl-beta-D-glucosaminidase (NAG)] for the detection of renal complications in rats with experimental colitis. On day 2 after intracolonic injection of 2,4,6-trinitrobenzene sulfonic acid (TNBS), male Wistar rats developed not only colitis, but histologically evident renal injury. Urinary vanin-1 started to elevate on day 1, whereas serum creatinine and urinary excretions of glucose, total protein, albumin, Kim-1, MCP-1 and NAG significantly increased only on day 2. The mRNA expressions of vanin-1 and Kim-1 significantly increased in the kidney, but not in the colon. In addition, vanin-1 did not appear in the blood. On the other hand, colonic mRNA expression and the serum concentration of MCP-1 were significantly higher in the TNBS-treated rats than in the control animals. These results suggest that, in contrast to MCP-1, urinary vanin-1 and Kim-1 mainly originated from the kidney rather than the colon in this model. Compared with Kim-1 and MCP-1, vanin-1 might be an earlier biomarker for the detection of renal injury in rats with experimental colitis.

Metabolite profiling of plasma and urine from rats with TNBS-induced acute colitis using UPLC-ESI-QTOF-MS-based metabonomics--a pilot study.

The incidence of inflammatory bowel disease, a relapsing intestinal condition whose precise etiology is still unclear, has continually increased over recent years. Metabolic profiling is an effective method with high sample throughput that can detect and identify potential biomarkers, and thus may be useful in investigating the pathogenesis of inflammatory bowel disease. In this study, using a metabonomics approach, a pilot study based on ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) was performed to characterize the metabolic profile of plasma and urine samples of rats with experimental colitis induced by 2,4,6-trinitrobenzene sulfonic acid. Acquired metabolic profile data were processed by multivariate data analysis for differentiation and screening of potential biomarkers. Five metabolites were identified in urine: two tryptophan metabolites [4-(2-aminophenyl)-2,4-dioxobutanoic acid and 4,6-cihydroxyquinoline], two gut microbial metabolites (phenyl-acetylglycine and p-cresol glucuronide), and the bile acid 12α-hydroxy-3-oxocholadienic acid. Seven metabolites were identified in plasma: three members of the bile acid/alcohol group (cholic acid, 12α-hydroxy-3-oxocholadienic acid and cholestane-3,7,12,24,25-pentol) and four lysophosphatidylcholines [LysoPC(20:4), LysoPC(16:0), LysoPC(18:1) and LysoPC(18:0)]. These metabolites are associated with damage of the intestinal barrier function, microbiota homeostasis, immune modulation and the inflammatory response, and play important roles in the pathogenesis of inflammatory bowel disease. Our results positively support application of the metabonomic approach in study of the pathophysiological mechanism of inflammatory bowel disease.

Identification of urinary biomarkers of colon inflammation in IL10-/- mice using Short-Column LCMS metabolomics.

The interleukin-10-deficient (IL10(-/-)) mouse develops colon inflammation in response to normal intestinal microflora and has been used as a model of Crohn's disease. Short-Column LCMS metabolite profiling of urine from IL10(-/-) and wild-type (WT) mice was used, in two independent experiments, to identify mass spectral ions differing in intensity between these two genotypes. Three differential metabolites were identified as xanthurenic acid and as the glucuronides of xanthurenic acid and of α-CEHC (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman). The significance of several differential metabolites as potential biomarkers of colon inflammation was evaluated in an experiment which compared metabolite concentrations in IL10(-/-) and WT mice housed, either under conventional conditions and dosed with intestinal microflora, or maintained under specific pathogen-free (SPF) conditions. Concentrations of xanthurenic acid, α-CEHC glucuronide, and an unidentified metabolite m/z 495(-)/497(+) were associated with the degree of inflammation in IL10(-/-) mice and may prove useful as biomarkers of colon inflammation.

Experimental colitis impairs linear bone growth independent of nutritional factors.

BACKGROUND: Poor linear growth frequently complicates chronic inflammatory bowel disease in children. Circulating inflammatory mediators may play a role in this growth delay. We evaluated the effect of experimental colitis on bone growth in a nutritionally controlled rat model. METHODS: Experimental colitis was induced in male Sprague-Dawley rats (125-150 g) by enema with trinitrobenzene sulfonic acid in 50% ethanol on day 1 and 11 of a 14-day protocol. Control animals were pair-fed and all animals received a liquid rat diet (1 kcal/ml). Twenty-four-hour urine, collected on days 2 and 12 and serum samples, collected at death, were analyzed for calcium, zinc, and magnesium. Serum samples from a separate set of animals were studied for serial interleukin-6 levels. Right proximal tibias were processed for growth-plate histomorphometry, in which linear growth is proportional to the heights of the proliferative zone, and terminal hypertrophic chondrocyte, but inversely proportional to the height of the resting zone. RESULTS: Histology confirmed active inflammation in the animals given trinitrobenzene sulfonic acid. Weight gain and both urinary excretion and serum levels of zinc, calcium, and magnesium did not differ between treatment and nontreatment groups. Histologically, there was impaired linear bone growth. The resting zone was greater in the colitis group (94.5 +/- 32.6 microns versus 3.9 +/- 5.4 microns; p < 0.05); the proliferative zone was smaller in the colitis group (123.7 +/- 18.2 microns versus 78.9 +/- 11.2; p < 0.05 micron); the terminal hypertrophic chondrocyte was reduced in the colitis group (19.5 +/- 1.4 microns versus 28.8 +/- 3.6 microns; p < 0.05). At 6 and 24 hours after induction, the level of interleukin-6 was elevated in the colitis group. CONCLUSIONS: Experimental colitis results in a decreased linear bone growth, independent of nutritional intake. Circulating cytokines derived from intestinal inflammation may contribute to the suppression of bone growth.