Serum and urine metabolomic fingerprinting in diagnostics of inflammatory bowel diseases

Table 1 Demographic data and clinical profile of patients

	Ulcerative colitis	Crohn's disease	Healthy controls
Number of patients	24	19	17
Sex (male/female)	15/9	11/8	8/9
Average age (mean/range)	40.7 (18-70)	35.8 (18-61)	44.7 (24-62)
Mean activity score	6.1 (0-13)	6.7 (1-18)	-
SCCAI/HBI (range)
Number of patients in active/remission phase of disease	12/12	16/3	-
Average disease duration (yr)	8.2 (0.1-32)	5.5 (0.3-21)	-

SCCAI: Simple clinical colitis activity index; HBI: Harvey-bradshaw index.

Table 2 The partial least-squares-discriminant analysis models obtained from proton nuclear magnetic resonance-based analysis of serum samples

Comparison	Model	P value	Q2 (cum)	Number of latent variables
CD vs UC	PLS-DA	0.069	0.43	2
CD active vs UC active	PLS-DA	0.798	0.46	2
IBD active vs Control	PLS-DA	< 0.001	0.79	4
IBD remission vs Control	PLS-DA	0.372	0.26	2
IBD active vs IBD remission	PLS-DA	0.002	0.76	2

CD: Crohn’s disease; UC: Ulcerative colitis; IBD: Inflammatory bowel diseases; PLS-DA: Partial least-squares-discriminant analysis.

Table 3 Significantly changed serum metabolites

Metabolite	Percentage difference					Relative Standard Deviation (%)
	CD vs UC	CD active vs UC active	IBD active vs control	IBD remission vs control	IBD active vs IBD remission	CD	CD active	UC	UC active	IBD active	IBD remission	Control
Lipids LDL CH3-(CH2)n-	-7.2	-4.0	-11.6	0.4	-11.9a	20.7	20.5	20.4	18.1	19.2	20.9	24.8
Lipids VLDL CH3-(CH2)n-	-6.4	-6.0	-12.9	-2.2	-10.9c	18.3	18.9	20.9	26.0	22.2	13.7	24.0
Leucine	1.2	0.7	15.3a	11.6	3.3	25.1	25.9	19.9	21.2	23.6	19.3	10.8
Isoleucine	6.2	6.5	23.6ac	12.4	9.9	22.2	20.5	22.5	24.8	22.1	22.0	13.9
3-Hydroxybutyrate	-6.5	3.8	52.6ac	45.9	4.6	50.2	48.1	76.8	53.9	49.6	94.4	34.1
Unk1 δ 1.39 ppm	4.9	1.8	9.3ac	-3.0	12.7ac	11.3	10.4	10.4	7.5	9.2	10.0	10.8
Alanine	12.2c	13.7	8.5	6.0	2.4	22.1	24.1	24.3	27.5	25.8	19.8	16.2
N-acetylated compounds	8.9ac	3.2	16.1ac	1.0	15.0ac	11.1	11.3	14.1	13.1	12.0	11.1	8.4
Acetoacetate	-2.8	4.4	77.3a	50.7	17.7	79.8	76.7	97.9	79.8	76.6	118.6	49.1
Citrate	2.6	2.5	-3.9	-10.9	7.9	20.5	20.2	23.9	26.1	22.4	21.5	27.5
Dimethylamine	-4.5	- 6.0	14.5	16.1ac	-1.5	23.4	25.4	16.3	16.9	21.8	15.0	22.7
Creatine	5.5	-4.1	-14.7c	-13.7	-1.1	24.9	22.6	31.4	31.0	26.2	32.9	28.4
Dimethyl sulfone	-0.9	4.0	-31.0ac	-22.9a	-10.5	31.2	33.1	30.1	25.6	29.8	30.4	36.1
Choline + PC + GPC	-5.0	-0.6	-15.0a	-2.2	-13.0	21.5	21.9	24.0	21.2	21.2	23.3	27.9
Glycine	6.8	0.8	26.6ac	13.7	11.3	20.3	21.2	24.6	26.8	23.3	19.9	21.2
Phenylalanine	6.8	0.1	19.8ac	-0.6	20.5ac	25.9	26.4	22.3	20.7	23.7	18.8	18.4
Histidine	2.6	7.8	-16.4ac	-6.7	-10.4	33.2	36.3	22.6	26.4	32.5	16.6	19.0
Formate	-10.1	-22.7c	27.3	32.4	-3.8	48.5	51.1	32.5	30.6	42.7	34.2	45.6
Lactate	4.1	10.3	17.8c	13.2	4.1	20.7	19.9	28.1	29.4	24.0	26.8	36.5

Percentage difference was calculated based on the mean values of relative signal integrals in each group. The calculations were made from left to right, e.g., a positive value in IBD active vs Control means that a particular metabolite exhibits higher concentration in patients with active IBD compared to the Control group,

^aP < 0.05 using the Student's t test,

^cP < 0.05 using the Mann-Whitney-Wilcoxon test. CD: Crohn’s disease; UC: Ulcerative colitis; IBD: Inflammatory bowel diseases; LDL: Low-density lipoproteins; VLDL: Very low-density lipoproteins; PC: Phosphocholine; GPC: Glycerophosphocholine; Unk1: Unknown metabolite.

Table 4 The partial least-squares-discriminant analysis models obtained from proton nuclear magnetic resonance-based analysis of urine samples

Comparison	Model	P value	Q2 (cum)	Number of latent variables
CD vs UC	PLS-DA	0.388	0.1	2
CD active vs UC active	PLS-DA	1.000	-0.2	2
IBD active vs control	PLS-DA	0.003	0.6	4
IBD remission vs control	PLS-DA	0.037	0.31	2
IBD active vs IBD remission	PLS-DA	0.003	0.38	3

CD: Crohn’s disease; UC: Ulcerative colitis; IBD: Inflammatory bowel diseases; PLS-DA: Partial least-squares-discriminant analysis.

Table 5 Significantly changed urine metabolites

Metabolite	Percentage difference					Relative Standard Deviation (%)
	CD vs UC	CD active vs UC active	IBD active vs control	IBD remission vs control	IBD active vs IBD remission	CD	CD active	UC	UC active	IBD active	IBD remission	Control
Citrate	6.9	-4.0	-32.7c	-47.6ac	28.3	73.2	72.8	91.4	111.7	90.4	45.1	57.8
Hippurate	7.2	29.7	-53.3ac	-35.1c	-28.1	66.6	61.3	123.5	70.7	64.9	122.9	78.4
Glycine	23.3	11.4	12.6	-29.8a	60.3ac	43.6	40.1	47.9	45.9	42.0	36.3	50.3
Alanine	-0.2	-12.2	-9.1	-30.3ac	30.3	36.8	36.0	47.7	49.4	42.8	34.9	51.7
Formate	2.9	1.5	-17.0	-30.6ac	19.5	47.1	42.1	37.4	37.2	39.4	45.3	38.8
Trigonelline	-10.2	139.6	-73.5ac	-51.7	-45.1	148.3	144.8	137.4	64.3	150.8	121.9	133.7
Acetoacetate	-6.2	82.2	7.8	85.1c	-41.7c	125.9	133.8	122.5	58.0	129.3	108.4	92.3
Taurine	7.0	21.7	-28.1ac	-31.8ac	5.5	66.5	66.1	35.1	35.0	57.8	38.3	41.4
Succinate	2.3	-11.4	-63.7ac	-51.8ac	-24.7	128.9	120.5	93.6	95.4	107.4	111.1	74.1
2-hydroxyisobutyrate	17.3	30.2	-68.1c	-66.8	-3.9	41.5	44.9	38.4	31.4	42.9	37.2	256.5
Unk2 with 4-hydroxyphenyl group δ 6.85 ppm	0.8	-5.0	78.5ac	33.1	34.1	63.8	62.2	73.0	81.9	70.4	53.3	45.3

Percentage difference was calculated based on the mean values of relative signal integrals in each group. The calculations were made from left to right, e.g., a positive value in IBD active vs Control means that a particular metabolite exhibits higher concentration in patients with active IBD compared to the Control group,

^aP < 0.05 using the Student's t test,

^cP < 0.05 using the Mann-Whitney-Wilcoxon test. CD: Crohn’s disease; UC: Ulcerative colitis; IBD: Inflammatory bowel diseases; Unk2: Unknown metabolite.