Urinary metabolic insights into host-gut microbial interactions in healthy and IBD children

Table 1 Urinary metabolite overview in healthy and inflammatory bowel disease children at baseline

Metabolites	Healthy	IBD baseline	P value
2-hydroxybutyric acid	324.2 ± 228.5	401.9 ± 306.8	0.335
3-(3-hydroxyphenyl)-3-hydroxypropanoic acid	85.1 ± 242.2	240.6 ± 488.6	0.168
3-aminoisobutanoic acid	7278 ± 8267.9	12302.4 ± 15388.8	0.166
3-hydroxyisovaleric acid	12675.2 ± 14366.2	13929.9 ± 6198.6	0.722
3-hydroxyphenylacetic acid	6618.8 ± 7906.4	3579.7 ± 4269.6	0.134
3-methyl-2-oxovaleric acid	12049.5 ± 5596.6	13764.2 ± 4303.2	0.269
4-hydroxybenzoic acid	1659.4 ± 835.8	1660.6 ± 735.9	0.996
4-hydroxycinnamic acid	1749 ± 2142.3	4655.3 ± 5127.8	0.013
Adipic acid	5757.5 ± 3488.3	6806.6 ± 6403.6	0.485
Alpha-hydroxyisobutyric acid	7514.4 ± 4562.7	10645.1 ± 5098.4	0.036
Aminoadipic acid	23462.2 ± 13757.6	24927 ± 13309.2	0.722
Beta-alanine	3554.8 ± 2690.1	3730.4 ± 2705.5	0.830
Butyric acid	594 ± 329.1	754.4 ± 551	0.230
Caproic acid	337.3 ± 393.0	423.4 ± 412.3	0.480
Caprylic acid	113.7 ± 233.6	114.2 ± 335.3	0.996
Cis-aconitic acid	126743 ± 94692.1	217610 ± 154442.2	0.019
Citraconic acid	1487.4 ± 719.3	1877.1 ± 529.1	0.051
Citramalic acid	13454 ± 11088.9	29200.5 ± 23835.6	0.005
Citric acid	1521627.7 ± 1117692.9	2010896.5 ± 1470323.3	0.211
Dodecanoic acid	76 ± 118.3	95.1 ± 230.1	0.718
Dopamine	25594.1 ± 15600.7	46132.8 ± 4070.5	0.000
Ethylmethylacetic acid	354.4 ± 161.6	300 ± 108.3	0.208
Fumaric acid	4447.5 ± 5258.8	8002.2 ± 5704.2	0.036
Gamma-aminobutyric acid	8011.9 ± 2433.5	9501.4 ± 2144.3	0.038
Glutaric acid	6350.9 ± 2956.9	8011.9 ± 3153	0.077
Glyceric acid	24294.2 ± 44555.4	34244.8 ± 54085.6	0.503
Glycine	90591.2 ± 73998.7	150330 ± 121868.4	0.048
Glycolic acid	85357.2 ± 57207.8	98641.7 ± 50868.8	0.424
Hippuric acid	579641.8 ± 409879.0	435904.9 ± 374381.5	0.234
Homogentisic acid	395731.6 ± 236443.5	706581.6 ± 61533.7	0.000
Indoleacetic acid	58737.6 ± 40343.9	107584.7 ± 107498.1	0.040
Isocitric acid	418285.5 ± 291898.4	767013.4 ± 476267.9	0.004
Isovaleric acid	96.7 ± 125.3	53.8 ± 103.4	0.228
Itaconic acid	7961.3 ± 6523.3	12949.6 ± 11408.9	0.071
L-2-hydroxyglutaric acid	14028.4 ± 7911.3	25645.4 ± 16050.4	0.003
L-alanine	26378.1 ± 18928.9	36445.6 ± 16618.3	0.070
L-alpha-aminobutyric acid	1777.6 ± 1093.0	1826.9 ± 1158.2	0.885
L-asparagine	16684.8 ± 15672.4	25642.5 ± 14904.9	0.059
L-aspartic acid	2801.2 ± 833.5	3708.1 ± 1242	0.005
L-cysteine	7833.5 ± 5012.7	12771 ± 4681.6	0.002
L-glutamic acid	18551.2 ± 13284.8	29044.7 ± 18203.4	0.030
L-histidine	300484.2 ± 313800.2	328182 ± 163648.8	0.726
L-isoleucine	1874.2 ± 954.0	3149.4 ± 1492.8	0.001
L-leucine	4028.1 ± 3120.4	5677.4 ± 4266.7	0.141
L-lysine	38409.7 ± 46071.6	46194.7 ± 36720.6	0.545
L-methionine	1236.4 ± 696.3	2195.1 ± 1206.4	0.002
L-phenylalanine	18545.8 ± 14394.6	26167 ± 13952.9	0.082
L-proline	1131.5 ± 512.2	2020.9 ± 1099.8	0.001
L-tryptophan	26500.2 ± 13737.3	33639.1 ± 12697.3	0.082
L-tyrosine	63971.6 ± 55716.2	84163.3 ± 63553.6	0.264
L-valine	4892.5 ± 2641.4	7343.2 ± 3296.4	0.008
Malonic acid	493 ± 486.4	663.3 ± 547.4	0.277
Methylsuccinic acid	1655.6 ± 861.4	2484.1 ± 1188.1	0.009
N-acetyltryptophan	82232.1 ± 58726.0	112567.4 ± 56382.5	0.088
Nicotinic acid	1293.3 ± 1311.8	2104.1 ± 1204	0.039
Ornithine	7948.8 ± 2592.9	11968.9 ± 4307.9	0.000
Ortho-hydroxyphenylacetic acid	1265.1 ± 770.7	1915.5 ± 1233.6	0.035
Oxoglutaric acid	23844.7 ± 20947.4	34260.9 ± 33676.2	0.209
Phenol	266.1 ± 168.1	282 ± 165.2	0.753
Phenylacetic acid	3055.4 ± 2506.3	5635.2 ± 5749.6	0.048
Phenyllactic acid	729.1 ± 1365.9	2726.7 ± 2958.9	0.004
P-hydroxyphenylacetic acid	8991.4 ± 5587.6	16438.3 ± 9973.0	0.003
Pimelic acid	2203 ± 1453.7	3343.5 ± 1728.2	0.021
Pyroglutamic acid	39396.7 ± 14482.8	52204.6 ± 19506.9	0.015
Salicyluric acid	3342.8 ± 1712.7	4135.9 ± 1498.5	0.112
Suberic acid	8538.8 ± 5594.7	12987.5 ± 5378.1	0.010
Succinic acid	23748.9 ± 18864.3	34383.7 ± 30189.9	0.154
Tartaric acid	5156.1 ± 9387.3	11376.5 ± 27499.5	0.291
Vanillic acid	2838.1 ± 5734.4	3091.8 ± 3028.7	0.861
12_ketoLCA	11.5 ± 2.4	13.5 ± 4.5	0.072
3_DHCA	13.4 ± 11.9	17 ± 15.7	0.396
7_DHCA	145.5 ± 276.1	267.1 ± 439.7	0.267
7_ketoLCA	10.9 ± 2.9	13.6 ± 7.2	0.093
Beta-CA	12.9 ± 10.4	26.1 ± 27.0	0.029
Beta-UCA	42.1 ± 93.8	114.8 ± 168.0	0.074
CA	182.3 ± 237.0	266 ± 322.5	0.327
CDCA	21.9 ± 9.7	24.9 ± 11.2	0.346
CDCA_24GLN	79.6 ± 49.1	168 ± 151.2	0.008
CDCA_3GLN	64.1 ± 45.2	149.1 ± 105.5	0.001
DCA	45.2 ± 28.7	40.2 ± 31.0	0.588
GCA	84.4 ± 43.2	151.8 ± 162.6	0.051
GCDCA	39.8 ± 20.6	51.3 ± 25.1	0.105
GDCA	34.5 ± 33.4	30.4 ± 15.9	0.627
GHCA	36.7 ± 17.6	49.4 ± 41.5	0.171
GHDCA	14.4 ± 2.6	12.3 ± 0.6	0.002
GLCA	8.4 ± 5.7	4.8 ± 4.2	0.026
GUDCA	15.5 ± 17.5	39.5 ± 47.9	0.025
HCA	10.3 ± 1.5	10.5 ± 1.5	0.768
HDCA	17.1 ± 35.3	15.2 ± 10.2	0.820
LCA	19.1 ± 6.6	22.4 ± 32.6	0.621
LCA_S	22.5 ± 11.9	22.6 ± 22.2	0.989
NORCA	154.3 ± 116.0	181.4 ± 133.4	0.476
NORDCA	9.2 ± 1.5	9.3 ± 0.4	0.679
TCA	24.6 ± 8.2	26 ± 11.9	0.652
TCDCA	23.4 ± 7.7	23.4 ± 5.6	0.99
THCA	13.7 ± 3.0	18.4 ± 11.4	0.052
TUDCA	8.2 ± 1.6	9 ± 1.2	0.099
UCA	108.2 ± 135.4	268.4 ± 310.0	0.024
UDCA	11.6 ± 1.4	13.1 ± 2.0	0.008

Metabolite data are reported as mean ± SD of their urinary concentrations, in ng/mL for GC-MS metabolites, and nmol/L for the bile acids. P value from standard t-test is reported as a qualitative indicator for metabolic variations between the two groups of children. 12-KetoLCA: 12-ketolithocholic acid; 3_DHCA: 3-dehydrocholic acid; 7_DHCA: 7-dehydrocholic acid; 7_KetoLCA: 7-ketolithocholic acid; 3βCA: 3β-Cholic acid; βUCA: β-ursocholic acid; CA: Cholic acid; CDCA: Chenodeoxycholic acid; CDCA_24GLN: Chenodeoxycholic acid 24-Acyl-β-D-glucuronide; CDCA_3GLN: Chenodeoxycholic acid-3-β-D-glucuronide; DCA: Deoxycholic acid; GCA: Glycocholic acid; GCDCA: Glycochenodeoxycholic acid; GDCA: Glycodeoxycholic acid; GHCA: Glycohyocholate; GHDCA: Glycohyodeoxycholate; GLCA: Glycolithocholate; GUDCA: Glycoursodeoxycholic acid; HCA: γ-muricholic acid/hyocholic acid; HDCA: α-hyodeoxycholic acid; LCA: Lithocholic acid; LCA_S: Lithocholic acid 3 sulfate; NORCA: Nor cholic acid; NORDCA: 3α,12α-dihydroxynorcholanate/23-nordeoxycholic acid; TCA: Taurocholic acid; TCDCA: Taurochenodeoxycholic acid; THCA: Taurohyocholate; TUDCA: Tauroursodeoxycholic acid; UCA: Ursocholic acid; UDCA: Ursodeoxycholic acid.

Table 2 Overview of influential metabolites discriminating healthy and inflammatory bowel disease patients

Metabolic pathways	Metabolites	Comparison healthy - IBD subjects at
		Baseline		6 mo		12 mo
		VIP	r	VIP	r	VIP	r
Tca cycle	Methylsuccinic acid	1.3	0.4	1.2	0.2	1.0	0.1
	Fumaric acid	1.2	0.3	1.0	0.3	1.1	0.2
	2-hydroxyglutaric acid	1.4	0.5	1.3	0.4	1.3	0.3
	Isocitric acid	1.4	0.4	1.3	0.3	1.2	0.2
Glutathione metabolism	Cysteine	1.5	0.5	1.2	0.3	1.4	0.4
	Glycine	1.2	0.3	1.3	0.3	1.2	0.3
	Glutamic acid	1.2	0.3	1.3	0.3	1.2	0.3
	Pyroglutamic acid	1.3	0.4	1.3	0.3	1.0	0.1
Neurostransmitter metabolism	Gamma-Aminobutyric acid	1.2	0.3	1.2	0.3	1.0	0.1
	Dopamine	1.6	0.7	1.8	0.6	1.1	0.4
	Homogentisic acid	1.6	0.7	1.8	0.6	1.1	0.4
Bacterial metabolism	3-hydroxyphenylacetic acid	1.3	-0.5	1.2	-0.4	1.1	-0.3
	Hippuric acid	1.0	-0.3	1.2	-0.4	1.6	-0.5
	Indoleacetic acid	1.3	0.4	1.3	0.4	1.0	0.1
	4-hydroxyphenylacetic acid	1.3	0.5	1.1	0.3	1.0	0.2
	Phenyllactic acid	1.1	0.4	0.6	0.2	1.4	0.5
Other	Salicyluric acid	1.2	0.4	0.9	0.2	1.0	0.4
Dicarboxylic acid metabolism	Suberic acid	1.3	0.5	1.5	0.5	1.1	0.3
Bile acids	Beta-UCA	1.5	0.6	1.0	0.4	0.7	0.2
	GUDCA	1.3	0.5	1.5	0.5	1.9	0.7
	THCA	1.0	0.4	0.3	0.1	1.3	0.4
	UDCA	1.4	0.6	1.7	0.6	1.8	0.6
	GHDCA	1.3	-0.5	1.3	-0.5	1.0	-0.3
Amino acid metabolism	Aspartic acid	1.3	0.4	0.8	0.2	1.4	0.4
	Histidine	1.1	0.3	1.1	0.2	0.9	0.1
	Isoleucine	1.5	0.4	1.6	0.4	1.3	0.2
	Methionine	1.5	0.5	1.6	0.5	1.4	0.4
	Phenylalanine	1.3	0.3	1.2	0.2	1.1	0.1
	Proline	1.4	0.5	1.4	0.4	1.2	0.3
	Tryptophan	1.2	0.3	1.2	0.2	1.1	0.2
	Tyrosine	1.1	0.2	1.0	0.1	1.0	0.1
	Valine	1.3	0.3	1.3	0.3	1.1	0.1
	N-acetyltryptophan	1.2	0.3	1.2	0.2	1.1	0.2
	Ornithine	1.4	0.5	1.7	0.5	1.7	0.5
	Aminoadipic acid	1.0	0.0	1.2	0.3	1.1	0.1

IBD: Inflammatory bowel disease; TCA: Taurocholic acid; bUCA: Beta-ursocholic acid; GUDCA: Glycoursodeoxycholic acid; THCA: Taurohyocholate; UDCA: Ursodeoxycholic acid; GHDCA: Glycohyodeoxycholate.

Table 3 Overview of influential metabolites discriminating ulcerative colitis and Crohn’s disease patients

Comparison UC - CD subjects at metabolites	Baseline		6 mo		12 mo
	VIP	r	VIP	r	VIP	r
DCA	1.6	0.5	1.4	0.5	0.8	0.2
7-ketoLCA	1.1	0.3	1.2	0.4	1.8	0.5
Beta-UCA	0.3	0.1	2.0	0.7	1.0	0.3

UC: Ulcerative colitis; CD: Crohn’s disease; DCA: Deoxycholic acid; 7_KetoLCA: 7-ketolithocholic acid; bUCA: Beta-ursocholic acid.

Table 4 Overview of metabolites associated with anthropometric parameters

Metabolic pathways	Metabolites	Anthropometric parameters
		Fat mass %		BMI		BMI z-score		Body weight
		r	VIP	r	VIP	r	VIP	r	VIP
TCA cycle	L-2-hydroxyglutaric acid	0.41	1.57	0.22	1.23	0.29	1.36	0.14	1.07
	Oxoglutaric acid	0.48	1.66	0.29	1.32	0.35	1.41	0.13	0.91
	Succinic acid	0.39	1.50	0.17	1.12	0.24	1.24	0.10	0.98
Bacterial metabolism	3-hydroxyphenylacetic acid	0.44	1.49	0.27	1.20	0.29	1.22	0.23	1.07
	Hippuric acid	0.32	1.27	0.27	1.27	0.28	1.26	0.19	1.03
	Phenol	0.44	1.42	0.42	1.57	0.48	1.68	0.26	1.10
Bile acids	12_ketoLCA	0.34	1.13	0.41	1.53	0.40	1.40	0.39	1.48
	DCA	0.48	1.62	0.48	1.82	0.50	1.76	0.52	2.02
	GDCA	0.48	1.58	0.49	1.85	0.47	1.66	0.53	2.01
	GHDCA	0.38	1.28	0.49	1.81	0.42	1.47	0.45	1.69
	GLCA	0.19	0.87	0.32	1.28	0.30	1.17	0.43	1.69
	LCA	0.35	1.16	0.37	1.40	0.34	1.20	0.41	1.57
	NORDCA	0.37	1.25	0.45	1.65	0.44	1.54	0.57	2.13
	TUDCA	-0.12	0.81	-0.32	1.35	-0.31	1.27	-0.43	1.65
	UCA	-0.30	0.96	-0.38	1.39	-0.33	1.16	-0.35	1.42
	UDCA	-0.11	0.70	-0.42	1.60	-0.38	1.39	-0.44	1.65
Amino acid metabolism	Aminoadipic acid	0.36	1.41	0.22	1.20	0.25	1.23	0.17	1.06
	L-Asparagine	0.26	0.89	0.34	1.33	0.36	1.30	0.27	1.21
	L-Histidine	0.30	1.33	0.33	1.48	0.34	1.47	0.31	1.42
	L-Methionine	0.31	1.39	0.16	1.16	0.24	1.29	0.09	1.03
	L-Proline	0.30	1.35	0.15	1.13	0.23	1.27	0.10	1.06
	L-Tryptophan	0.32	1.39	0.29	1.41	0.34	1.50	0.22	1.21
	L-Tyrosine	0.27	1.29	0.23	1.26	0.26	1.32	0.15	1.07
	N-acetyltryptophan	0.32	1.42	0.28	1.41	0.33	1.50	0.22	1.23

12-KetoLCA: 12-ketolithocholic acid; DCA: Deoxycholic acid; GDCA: Glycodeoxycholic acid; GHDCA: Glycohyodeoxycholate; GLCA: Glycolithocholate; LCA: Lithocholic acid; NORDCA: 3α,12α-dihydroxynorcholanate/23-nordeoxycholic acid; TUDCA: Tauroursodeoxycholic acid; UCA: Ursocholic acid; UDCA: Ursodeoxycholic acid.