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Magnetic Resonance Imaging 27 (2009) 79–86

Metabolism of the colonic mucosa in patients with inflammatory boweldiseases: an in vitro proton magnetic resonance spectroscopy study

Krithika Balasubramaniana, Sandeep Kumara, Rajeev R. Singha, Uma Sharmaa, Vineet Ahujab,Govind K. Makhariab, Naranamangalam R. Jagannathana,⁎

aDepartment of NMR, All India Institute of Medical Sciences, New Delhi 110 029, IndiabDepartment of Gastroenterology and Human Nutrition, All India Institute of Medical Sciences, New Delhi 110 029, India

Received 27 November 2007; revised 17 May 2008; accepted 17 May 2008

Abstract

Metabolism of the colonic mucosa of patients with ulcerative colitis (UC; n=31) and Crohn's disease (CD; n=26) and normal mucosa(control, n=26) was investigated using in vitro high-resolution proton magnetic resonance spectroscopy. Of the 31 UC patients, 20 were inthe active phase and 11 were in the remission phase of the disease. Out of 26 CD patients, 20 were in the active phase, while 6 were in theremission phase of the disease. Twenty-nine metabolites were assigned unambiguously in the perchloric acid extract of colonic mucosa. Inthe active phase of UC and CD, significantly lower (P≤.05) concentration of amino acids (isoleucine, leucine, valine, alanine, glutamate andglutamine), membrane components (choline, glycerophosphorylcholine and myo-inositol), lactate and succinate were observed compared tonormal mucosa of controls. Patients in the active phase of UC and CD also showed increased level of α-glucose compared to normal mucosa.Altered level of metabolites indicates decreased protein and carbohydrate metabolism, thereby decreased energy status and deterioration ofmucosa integrity during chronic inflammation. In the remission phase of UC and CD, the concentration of most of the metabolites wassimilar to controls except for lower values of lactate, glycerophosphorylcholine and myo-inositol in UC and Lac in CD. Formate wassignificantly lower in patients with the active phase of UC compared to patients with the active phase of CD, suggesting the potential of invitro MRS in the differentiation of these two diseases.© 2009 Elsevier Inc. All rights reserved.

Keywords: Inflammatory bowel disease (IBD); Ulcerative colitis (UC); Crohn's disease (CD); In vitro proton magnetic resonance spectroscopy (MRS);Perchloric acid extraction; Metabolite concentration

1. Introduction

Inflammatory bowel disease (IBD) is a chronic inflam-mation of the intestine and consists of ulcerative colitis (UC)and Crohn's disease (CD). A combination of clinical,endoscopic, histopathological, serological and radiologicalfeatures is used to differentiate UC from CD [1,2]. While adifferentiation between UC and CD is possible in up to 80–85% of patients, in 15–20% a distinction between the tworemains a challenge [3,4]. Distinction between UC and CD

⁎ Corresponding author. Department of NMR and MRI Facility, AlIndia Institute of Medical Sciences, New Delhi 110029, India. Tel.: +91 112659 3253; fax: +91 11 2658 8663.

E-mail address: jagan1954@hotmail.com (N.R. Jagannathan).

0730-725X/$ – see front matter © 2009 Elsevier Inc. All rights reserved.doi:10.1016/j.mri.2008.05.014

l

is, however, extremely essential, as these two conditionsrequire different approaches of therapy and surgery.

Genomics [5], proteomics [5] and metabolomics [6,7] inrecent years are being explored to distinguish UC and CD atthe molecular level. While genomic and proteomic studieslook into genes and gene products involved in the diseaseprocesses, metabolomics provides the metabolic profile oftissues, blood or body fluids. Magnetic resonance spectro-scopy (MRS) is a useful technique that provides informationon the early biochemical changes at the molecular level thatcould signal initiation of the disease processes [8–14]. Anadvantage of in vitro MRS is that simultaneously a largenumber of metabolites can be detected which are difficult toassess using standard biochemical methods. The inherentsensitivity of proton (1H) nuclei in metabolites of interestmakes it as an important tool to elucidate the biochemistry of

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cells and tissues in normal and diseased states. Moreover,spectral acquisition at high field yields high sensitivity andbetter spectral resolution and provides an opportunity forabsolute quantitation of metabolites. Human samples such asbreast tissue [9], lymph nodes [10], colon tissue and mucosa[11], and body fluids [12] have been studied by in vitro 1HMRS providing insight into the alterations of metabolicpathways in the pathological state. In addition, the use ofmultivariate analysis combined with MRS data has beendocumented to be of diagnostic value in various diseases[12,13]. Bezabeh et al. [13] reported the results of ex vivoproton MRS combined with multivariate spectral analysis ofpatients with IBD. Recently, in vitro 1H NMR study of fecalextracts of patients with UC and CD showed high level ofglycerol as a dominant feature in CD [14].

The objectives of the present study were (i) to characterizethe colonic mucosa of patients with IBD using in vitro high-resolution 1H MRS and (ii) to determine the absoluteconcentration of the various metabolites in patients with UC,CD and controls, and to understand the metabolic alterationsin these gastrointestinal diseases.

2. Materials and methods

2.1. Patients recruitment

Twenty-six patients with CD and 31 with UC attendingthe gastroenterology clinic of our institution were included inthis study. The diagnosis of CD was made on the basis of thepresence of characteristic clinical manifestations (chronicdiarrhea, hematochezia, abdominal pain and intestinalobstructive manifestations), endoscopic features (skiplesions, asymmetrical involvement, deep ulcers, aphthousulcers, ileocecal valve involvement and terminal ilealinvolvement) and histological evidences (acute on chroniccolitis, presence of inflammation extending beyond themuscularis mucosae, lymphoid follicles and granuloma).The involvement of the small intestine was assessed bybarium meal followed by small bowel enema and/orretrograde ileoscopy. Disease activity was assessed usingthe Crohn's Disease Activity Index [15], and location andbehavior of the disease were classified using the modifiedMontreal classification [16]. All patients were treatedaccording to standard guidelines. The diagnosis of UC wasbased on the combination of clinical, endoscopic andhistological characteristics. The severity of UC was assessedusing Truelove and Witts' [17] criteria, and the extent of thedisease was determined by using a videocolonoscope.

To facilitate analysis, patients with CD and UC wereclassified into two subgroups based on the activity of thedisease, namely, active (A) or remission (R) phase. Of 31patients with UC, 20 were in the active phase [UC(A)], whilethe remaining 11 were in the remission phase of the disease[UC(R)]. Similarly, of 26 patients with CD, 20 were in theactive phase [CD(A)], the rest (6) were in the remissionphase [CD(R)].

2.2. Controls (normal mucosa)

Twenty-six subjects undergoing colonoscopic examina-tion for obscure gastrointestinal bleeding and colonicpolyps where the colon was observed to be normal servedas controls for this study. In subjects with colonic polyps,the biopsies were taken from an area away from the polyps,while in those with occult gastrointestinal bleeding, biopsieswere taken only if the colon appeared normal. All patientswere treated according to standard treatment regimen. Aninformed consent was taken from each patient andcontrol, and the institute's ethics committee approvedthe study.

2.3. Collection of mucosal biopsies

The colonic biopsies were obtained from both controlsand patients with UC and CD during routinely performedcolonoscopy examination. Ten biopsies were collected fromthe abnormal (inflamed) regions from each patient. Similarly,10 mucosal biopsies were collected from the normal(colonoscopically normal) area of controls. The tissuesamples (weight in the range 23–88 mg) obtained weresnap frozen in liquid nitrogen and stored at −35°C untilfurther use.

2.4. Perchloric acid extraction

Water-soluble metabolites were extracted from the tissuesfollowing perchloric acid extraction as discussed earlier[8,10]. Frozen tissues were weighed, crushed and thenthoroughly homogenized in 6% perchloric acid. Thehomogenate was then centrifuged at 10,000 rpm for10 min after which the supernatant was collected. Thesupernatant was then neutralized using 3 M potassiumhydroxide, and the precipitated perchlorate salt (KClO4) wasremoved by centrifugation. The supernatant obtained wasthen lyophilized for 8–10 h. The resulting sample wasdissolved in 0.6 ml of deuterium oxide. 3-Trimethyl silylpropionic acid (TSP) (0.5 mM) was added to the sample thatserved both as a chemical shift and as a concentrationreference for the proton MRS studies.

2.5. MR Spectroscopy

Proton MRS was carried out at 400.13 MHz (Avance,BRUKER, Switzerland). One dimensional (1D) spectra withwater suppression were acquired using a standard 5-mmdedicated multinuclear broadband inverse probe at 25°C.The typical parameters used were spectral width=5000 Hz,data points=32 K, relaxation delay=14 s, number ofscans=256. The chemical shifts of the resonances werereferenced to TSP at 0.00 ppm. 0.3-Hz line broadening wasapplied before processing the spectrum.

Two-dimensional (2D) correlated spectroscopy (COSY)and total correlated spectroscopy (TOCSY) pulse sequenceswere used for unambiguous assignment of resonances.COSY correlates the chemical shifts of 1H nuclei whichare J-coupled and only two to three covalent bonds apart,

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while in TOCSY cross peaks are observed between allmembers of a coupled network (including long-rangecouplings). The parameters used were 2 K data points inF2 dimension, spectral width of 5000 Hz and a relaxationdelay of 2 s. The number of increments was 256, and 64 freeinduction decays per increment were acquired. A mixingtime of 75 ms was used for TOCSY experiments. Theconcentration of the metabolites was determined bycomparing the integrated intensity of the isolated resonancesof the compounds of interest with that of the TSP signal [18].

Fig. 1. (A–C) One-dimensional 1H NMR spectra of perchloric acid extracts of colonAMP, adenosine mono-phosphate; ATP, adenosine tri-phosphate.

The absolute concentration of only those metabolites thatshowed well-resolved resonances in the 1D spectrum wasdetermined [18].

2.6. Statistical analysis

Since the concentration values followed a non-normal(skewed) distribution, the nonparametric method Kruskal–Wallis one-way analysis of variance was used for compar-ison among the five study groups using STATA 9 software(College Station, TX, USA). The concentration values for

ic tissues obtained from control, UC(A) and CD(A) subjects. Abbreviations

:

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each metabolite were combined from all the groups into asingle set. These observations were ranked from lowest tohighest, with tied ranks included wherever appropriate. Theresulting ranks were then replaced to the groups where theybelonged to and substituted for the raw observations thatgave rise to them. If a significant difference was observedamong the groups using Kruskal–Wallis test at P set at≤.05,individual comparison between all groups was carried outusing the nonparametric multiple comparison method givenby Conover [19]. Data are presented as median value withthe range.

3. Results

3.1. Spectral assignments

Fig. 1 shows the representative 1D MR spectra of themucosal biopsies of controls and patients with active phaseof UC and CD. Assignments of the resonances from variousmetabolites were carried out using COSY and TOCSY andby comparing the chemical shift values of similar samplesreported in the literature [8–10]. Fig. 2 shows therepresentative TOCSY spectrum of colonic mucosal tissueobtained from a patient with UC. In all, 29 metabolites wereassigned unambiguously in controls and patients with IBD.The chemical shifts of the various resonances assigned areshown in Table 1. Resonances due to several amino acids wereeasily identified in the 1DMR spectrum (Fig. 1). Peaks due tothe methyl protons of isoleucine (Ile), leucine (Leu) and valine

Fig. 2. Two-dimensional total correlation spectrum (2D TOCSY) of perchloricAbbreviation: β-OHB, β-hydroxybutyrate.

(Val) appear between 0.95 and 1.04 ppm (Fig. 1). The δ-CH3

protons of Ile at 0.95 ppm showed coupling with its γ-CH2 at1.25 and 1.46 ppm, respectively (Fig. 2). Similarly theresonances of lysine (Lys), arginine (Arg), alanine (Ala),aspartate (Asp), glutamate (Glu), glutamine (Gln), cysteine(Cys) and histidine (His) were assigned using TOCSY.

Resonances due to organic acids like acetate (Ace) andpyruvate (Pyr) were observed as singlet at 1.91 and 2.37ppm, respectively (Fig. 1). The singlet at 8.46 ppm wasassigned to formate (For). Methyl protons of lactate (Lac)were observed as a doublet at 1.33 ppm and showedconnectivity with its α-CH (quartet) proton at 4.10 ppm inTOCSY (Fig. 2). A doublet corresponding to H1′ of α-anomer of glucose (Glc) was observed at 5.23 ppm, whileother resonances were assigned using TOCSYpeaks. The H1and H3 protons of myo-inositol (mI) were observed at 3.54ppm which showed connectivity with its H2 at 4.07 ppm.Peaks due to N(CH3) protons of glycerophosphorylcholine(GPC) and phosphorylcholine (PC) resonate at 3.23 ppm,while that of choline (Cho) was assigned at 3.20 ppm. The N(CH3) singlet of creatine (Cr) and phosphocreatine (PCr) wasobserved at 3.02 ppm.

3.2. Concentration of metabolites in UC, CD and controls

The concentrations are expressed as median (range) andwide variation is observed in both patients and controls(normal mucosa) (see Table 2). Significantly lower(P≤.05) concentration of Ile/Leu/Val, Lac, Ala, succinate(Suc), Glu+Gln, Cho, GPC, mI and For, and higher

acid extract of colonic mucosal tissue obtained from patient with UC

.

Table 1Chemical shift of metabolites observed

Metabolite Chemical shift (ppm)

Isoleucine (Ile) 0.95 (δ-CH3), 0.96 (γ-CH3), 1.25 (γ-CH2), 1.46 (γ-CH2), 1.96 (β-CH), 3.68 (α-CHLeucine (Leu) 0.96 (δ-CH3), 0.95 (δ-CH3), 1.69 (γ-CH), 1.71 (β-CH2), 3.65 (α-CH)Valine (Val) 1.00 (γ-CH3), 2.21 (β-CH), 3.52 (α-CH)β-Hydroxybutyrate (β-OHB) 1.27 (γ-CH3), 4.15 (β-CH)Lactate (Lac) 1.33 (CH3), 4.11 (CH)Alanine (Ala) 1.45 (β-CH3), 3.75 (α-CH)Arginine (Arg) 1.68 (γ-CH2), 1.81 (β-CH2), 3.23 (δ-CH2), 3.61 (α-CH)Lysine (Lys) 1.47 (γ-CH2), 1.72 (δ-CH2), 1.82 (β-CH2), 3.02 (ɛ-CH2), 3.59 (α-CH)Acetate (Ace) 1.92 (CH3)Glutamate (Glu) 2.04 (β-CH2), 2.32 (γ-CH2), 3.66 (α-CH)Glutamine (Gln) 2.08 (β-CH2), 2.34 (γ-CH2), 3.67 (α-CH)Pyruvate (Pyr) 2.37 (CH3)Succinate (Suc) 2.41 (CH3)Dimethylamine (DMA) 2.72 (CH3)Aspartate (Asp) 2.68 (β-CH), 2.81 (α-CH2)Cr/PCr 3.04 (CH3), 3.93 (CH2)Choline (Cho) 3.20 (N (CH3)), 4.16 (β-CH2), 3.60 (α-CH2)GPC/PC 3.64 (H1), 3.75 (H2), 3.91 (H3), 4.32 (H4), 3.68 (H5), 3.23 (N (CH3))Myo-Inositol (mI) 3.27 (H5), 3.61 (H4, H6), 4.07 (H2), 3.54 (H1, H3)α-Glucose (α-Glc) 3.42 (H4′), 3.53 (H2′), 3.72 (H3′), 3.84 (H5′), 5.22 (H1′), 3.84 (CH2)β-Glucose (β-Glc) 3.41 (H4′), 3.47 (H5′), 3.49 (H3′), 3.22 (H2′), 3.72 (CH2), 3.90 (CH2)Adenosine (Ade) 6.04 (H1′), 8.20 (base)ATP 6.14 (H1′), 8.27 (base), 8.54 (base)Formate (For) 8.46 (CH)Histidine (His) 3.12 (β-CH2), 3.22 (β-CH2), 3.96 (α-CH)Cysteine (Cys) 3.07 (β-CH2), 4.00 (α-CH)Taurine (Tau) 3.25 (CH2NH), 3.41 (CH2SO3)

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concentration of α-Glc were observed in patients with theactive phase of UC and CD in comparison to controls (Fig. 3).In the remission phase of UC and CD, the concentration ofmost of the metabolites was similar to controls except forlower values of Lac, GPC and mI in UC and Lac in CD. Inaddition, a higher level of Glc was observed in patients withUC(R) compared to controls. In patients with UC(A), formatewas significantly lower compared to that observed in theremission phase, while in patients with CD(A), Ile/Leu/Val,Cho and GPC were significantly lower compared to those inthe remission phase. Formate was significantly lower in

Table 2Median (range) values of the concentration (mmol/kg wet weight) and the P values of the various metabolites between controls and patients with UC and CD

Metabolites Control (a) UC (A) (b) UC (R) (c) CD (A) (d) CD (R) (e) P value ≤.05

Ile/Leu/Val 3.9 (0.6–13.7) 2.36 (1.1–7.5) 2.29 (1.0–11.9) 2.46 (1.5–5.0) 5.16 (1.3–6.6) P (a,b), (a,d), (d,e)

Lac 12.9 (4.1–41.4) 5.31 (1.8–8.1) 6.6 (2–22.2) 5.61 (2.3–9.2) 6.97 (4.1–15.0) P (a,b), (a,c), (a,d)

Ala 6.3 (0–19.5) 3.27 (0–10.1) 4.4 (1.6–12.3) 3.61 (0–7.0) 6.7 (2.7–10.9) P (a,b),(a,d)

Arg/Leu/Lys 1.4 (0–6.6) 2.21 (0–8.3) 1.92 (0–17.6) 2.13 (0–5.5) 2.6 (0–6.2) P (a,b)

Ace 2.52 (0–7–20.3) 1.82 (0–13.2) 1.67 (0.9–1.1) 1.9 (0–8.23) 2.38 (0.9–8.3) –Glu+Gln 10.4 (0.6–32.3) 6.48 (3.1–11.9) 6.55 (3.4–19.3) 6.99 (3.3–14.2) 9.5 (5.5–18.4) P (a,b),(a,d)

Suc 2.3 (0–6.2) 1.2 (0–2.2) 1.46 (0.8–10.01) 1.57 (0.8–2.4) 2.74 (1.1–3.9) P (a,b),(a,d)

Cr/PCr 1.68 (0.6–5.2) 1.1 (0.5–2.6) 1.37 (0.4–4.6) 1.37 (0.5–3.1) 1.6 (0.8–2.5) –Cho 1.0 (0.2–3.4) 0.52 (0–2) 0.69 (0.4–2.2) 0.53 (0.3–1.9) 1.3 (0.6–2.6) P (a,b), (a,d), (b,c), (d,e

GPC 3.0 (1.1–8.3) 1.31 (0.8–2.4) 1.54 (0.8–3.7) 1.43 (0.8–2.5) 2.08 (1.2–3.8) P (a,b),(a,c),(a,d), (d,e)

mI 11.9 (5.0–52.1) 5.6 (0.5–7.5) 7.11 (2.8–25.7) 6.10 (2.8–10.9) 7.5 (4.8–26.5) P (a,b),(a,c),(a,d)

α-Glc 2.06 (0–12.7) 5.8 (0–22.3) 8.0 (0.52.8) 14.9 (0–30.4) 16.8 (0–40.3) P (a,b),(a,c),(a,d)

For 2.52 (0.7–6.7) 1.03 (0–2.43) 2.4 (0.6–9.6) 1.4 (0.8–3.2) 2.00 (0.7–4.5) P (a,b),(a,d),(b,d), (b,c)

)

patients with UC(A) compared to patients with CD(A)(Table 2 and Fig. 3).

4. Discussion

Under normal physiological conditions, approximately1.5 L of fluid reaches the colon, of which only about 100–200 ml is excreted in stool, while the rest is absorbed by thecolonic mucosa through an energy-dependent Na+-K+

ATPase pump located on its basolateral membrane to preventdiarrhea. Anaerobic bacteria present in the colonic lumen

)

Fig. 3. Box plots showing differences in the concentrations of Lac, Glu+Gln, Cho, GPC, mI, For and α-Glc between control, UC and CD.

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digest a number of undigested foods like complex sugars toshort chain fatty acids (SCFA). These SCFAs are essentialnutrient sources for colonic epithelium. However, duringgastrointestinal diseases such as UC and CD, the structure ofmucosal lining is altered which disturbs its normal function.UC is characterized by superficial ulcerations, friability,distortion of mucosal vascular pattern, crypt abscess andexudates limited to the mucosa and submucosa of the colon.Crohn's disease features include discrete ulcerations, apthoidulcers, cobblestone appearance of the mucosa, and can affectany region of the gastrointestinal tract except the rectum[20,21]. Despite these features, differentiating the twodiseases based on anatomical changes is often difficult.

Suboptimal function of the mucosa leads to nutritionaldeficiencies, thereby resulting in low energy status, whichin turn alters the structural and functional integrity of themucosa [22]. In the present investigation, we evaluatedthe metabolic status of colonic mucosa in controls and inthe active and remission phases of UC and CD to get aninsight into the biochemical mechanism associated with thealtered structural integrity of the mucosa and to determine thebiomarkers for their differentiation using in vitro 1H MRS.Several interesting observations emerged from this study.

A significant decrease in the concentration of Glu/Gln,Ile/Leu/Val and Ala was observed in the active phase of thedisease (UC and CD) compared to controls, while in theremission phase their concentrations were similar to controls.About 30% of the total energy requirement of the intestinalmucosa is met through the reducing equivalents generatedduring the conversion of Gln to Ala [23,24]. The amidegroup derived during this process is important for main-tenance of the mucosal membrane integrity through theproduction of hexosamines which are components ofmembrane glycoproteins and amino sugars [23,24]. Gluta-mine also maintains the secretory IgA level that prevents theattachment of bacteria to the mucosal cells [25] and furthermodulates the inflammatory activity of IL-8 and TNF-α [26].Reduction in Ile, Leu and Val may be attributed to chronicinflammation and decreased muscle protein metabolism [26]that may lead to deterioration of the mucosal lining.

Decreased levels of membrane metabolites like GPC, Choand mI may be due to changes in mucosal membraneintegrity in UC and CD. Cho is essential for synthesis of lipidcomponents such as phosphorylcholine (PC) and sphingo-myelin of cell membrane [27]. The mechanism of action ofmI is not yet fully understood; however, it is known that mImetabolizes to phosphatidylinositol, which is incorporatedinto the membrane structure [28].

The concentration of For was lower in patients with UC(A) than in patients with CD(A) and may serve as abiomarker for distinction between active UC and CD.However, its specific involvement in the metabolism ofmucosa is not clear. Short chain fatty acids such as formate,butyrate, acetate and propionate are produced by thebacterial fermentation of unabsorbed carbohydrates in thecolonic lumen [29]. They not only provide 70% of the energy

required by the colonic epithelium but also promoteabsorption of sodium in the colon [30]. Studies haveshown decreased metabolism of SCFAs in patients withIBD which could be due to defective uptake from fecaleffluents [6,29,30]. This may occur due to improper functionof the Na+-K+ pump in the mucosal membrane possibly dueto changes in the mucosal membrane integrity.

Glucose serves as an energy source for normal intestinalmucosa [31,32], and its utilization and, consequently, Lacproduction are reduced during malnutrition and starvation, acommon symptom observed in IBD [33–35]. Low level ofLac and high level of α-Glc observed thus indicate theinability of the colonic mucosal cells to utilize Glc for itsenergy needs in UC and CD. In addition, exudation of Lacfrom the inflamed colonic mucosa supports the reduction inits level in the mucosa while its concentration in the feces isincreased [36]. The concentration of Lac may also differ dueto anaerobic respiration on exposure of the tissue to roomtemperature during biopsy. However, in the present study,the samples were snap frozen in liquid nitrogen as soon asthey were removed and stored at −35°C.

Bezabeh et al. [13] demonstrated differences in Tau(taurine), Lys and lipid in UC and CD using ex vivo NMRand multivariate analysis. However, in our study theconcentration of Tau and Lys could not be determined dueto overlap with other resonances and loss of lipid duringextraction. The concentration values in the normal mucosa ofour study showed broad agreement with most metabolitesreported by Moreno and Arus [11] using in vitro MRS exceptfor Glu, Gln and Ala. Also, the concentration of branchedchain amino acids of normal mucosa observed by us issimilar to that reported by Ahlman et al. [37] andOllenschlager et al. [38] using ion-exchange chromatogra-phy except for Glu and Gln. These differences may be due todifferences in the methodology and heterogeneity of thesubjects investigated.

In patients with the remission phase of UC and CD, theconcentration of most metabolites was similar to the normalmucosa of controls, which is consistent with the healing ofthe colonic ulcerations. This is in agreement with the resultsreported by Den Hond et al. [39] wherein significantly lowerbutyrate oxidation has been shown in patients with active UCin comparison to controls but it was not decreased in mostpatients with inactive UC.

5. Conclusion

The present study showed lower carbohydrate and proteinmetabolism resulting in low energy and altered mucosalintegrity in patients with UC and CD, especially during theactive phase of the disease. The concentration of formate inthe colonic biopsies was significantly lower in patients withthe active phase of UC than in patients with the active phaseof CD, suggesting the potential application of in vitro MRSin the differentiation of these two diseases. In the remission

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phase of the disease, the concentration of most of themetabolites was similar to that observed in normal mucosa ofcontrols. Although this pilot study provides insight into themetabolic state of the colonic mucosa in patients with IBD,further investigation in a large cohort of patients possibly athigh field and by considering the variations of several factorslike severity, duration of the disease, etc, is required.

Acknowledgments

The authors would like to acknowledge Prof. S.N.Dwivedi and other staffs of the Department of Biostatisticsfor help.

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