Table 2.

Summary of potential biomarkers of ankylosing spondylitis by plasma, urine and tissue metabolomic analysis

Metabolite	Sample type	Statusa	Chemical shift	Correlation coefficient (AS vs HC)b	VIP valueb	FCc	P valued
Leucine	Plasma	↓	0.96 (d), 0.97 (d), 1.72 (m), 1.72 (m), 3.73 (t)	−0.452	0.698	0.932	0.045
Valine	Plasma	↓	1.00 (d), 1.05 (d), 2.28 (m), 3.62 (d)	−0.302	1.090	0.86	<0.001
3-HB	Plasma	↑	1.20 (d), 2.32 (dd), 2.42 (dd), 4.16 (m)	0.422	1.328	1.254	<0.001
Alanine	Plasma	↓	1.48 (d), 3.77 (q)	−0.332	1.664	0.770	<0.001
NAG	Plasma	↑	2.05 (s)	0.570	0.065	1.207	<0.001
Methionine	Plasma	↑	2.14 (s), 2.16 (m), 2.65 (t), 3.87 (t)	0.597	1.701	1.325	<0.001
TG (L1, L2, L3, L5, L7, L8)	Plasma	↓	0.86 (t), 0.88 (t), 1.27 (m), 2.01 (m), 2.76 (m), 5.30 (m)	−0.400	0.977	0.814–1.077	<0.05
Acetone	Plasma	↑	2.23 (s)	0.298	1.358	1.415	<0.001
Acetoacetate	Plasma	↑	2.29 (s)	2.294	0.884	1.249	<0.001
Betaine	Plasma	↑	3.26 (s), 3.91 (s)	0.334	0.287	1.038	0.030
Glycerol	Plasma	↑	3.65 (dd), 3.56 (dd), 3.77 (m)	0.328	1.400	1.207	<0.001
Glucose	Plasma	↓	3.42 (dd), 3.54 (dd), 3.71 (dd), 3.78 (m), 3.84 (m), 5.26 (d)	−0.317	0.559	0.909	0.013
Glutamate	Plasma	↓	2.07 (m), 2.35 (m), 3.75 (m)	−0.374	1.300	0.789	<0.001
Butyrate	Urine	↓	0.90 (t), 1.56 (m), 2.16 (t)	−0.447	1.533	0.896	0.003
Creatinine	Urine	↓	3.04 (s), 3.93 (s)	−0.331	1.330	0.814	0.018
Glycine	Urine	↑	3.56 (s)	3.392	1.088	1.298	0.009
Hippurate	Urine	↑	7.84 (d), 7.64 (t), 7.56 (dd)	0.421	0.772	1.320	0.017
PAG	Urine	↓	8.03 (d), 7.36 (m), 7.37 (m), 7.43 (m)	−0.306	1.213	0.895	0.028
Glutamate	Urine	↓	2.07 (m), 2.35 (m), 3.75 (m)	−0.429	1.541	0.919	0.002
2-PY	Urine	↑	7.83 (dd), 8.55 (d)	0.461	0.700	1.182	0.049
TG (L2, L3, L5, L6, L7, L8)	Tissue	↑	0.88 (t), 1.27 (m), 2.01 (m), 2.30 (m), 2.76 (m), 5.33 (m)	0.946	1.060	2.490–7.039	<0.001
Choline	Tissue	↓	4.14 (m), 4.29 (m), 5.26 (m)	−0.680	0.718	0.242	<0.001

Abbreviations: AS Ankylosing spondylitis, VIP Variable importance for projection, FC Fold change, 3-HB 3-Hydroxybutyrate, NAG N-acetyl glycoprotein, TG Triglycerides, PAG Phenylacetylglycine, 2-PY 2-Pyridone-3-carboxamide, L1 CH ₃(CH₂)_n., L2 CH ₃CH₂CH₂C=, L3 -(CH ₂)_n-, L5 -CH ₂C = C-, L6 CH ₂CO, L7 C = CCH ₂C = C, L8 -CH = CH-

^aRelative concentrations compared with healthy control subjects: ↑ = up-regulated; ↓ = down-regulated

^bCorrelation coefficient and VIP value were obtained from orthogonal projection to latent structures discriminant analysis

^cFold change between patients with AS and healthy control subjects

^d P value determined using Student’s t test