Liver fat deposition and mitochondrial dysfunction in morbid obesity: An approach combining metabolomics with liver imaging and histology

Table 1 Absolute concentration of single metabolites obtained by ¹H NMR metabolomic profiles

	Mean	SD	Kruskall-Wallis (P)	None		Low		Moderate		Severe		U Mann-Withney (P)
				Mean	SD	Mean	SD	Mean	SD	Mean	SD	N vs L	L vs M	M vs S	L vs S
Lipid-soluble metabolites (mmol/g liver)
Total cholesterol	5.19	1.71		2.74	0.51	5.03	2.15	5.89	0.68	5.99	1.06
Free cholesterol	1.32	0.40		1.09	0.18	1.52	0.41	1.36	0.42	1.00	0.27
Sterified cholesterol	3.87	1.65		1.66	0.70	3.50	1.82	4.54	1.01	4.99	1.31
Triglycerides	141.33	92.95	0.008	13.71	6.33	88.82	59.32	184.61	26.11	259.29	67.09		0.017		0.020
Diglycerides	8.04	3.22		10.35	7.42	8.40	2.37	8.55	2.70	4.91	0.96				0.039
Monoglycerides	0.73	0.20		0.69	0.25	0.80	0.28	0.77	0.12	0.57	0.06
Total phospholipids	22.75	5.86	0.046	29.44	7.74	24.28	1.56	23.75	1.65	13.59	6.03			0.025	0.020
PC	15.90	4.06		20.05	5.70	16.71	1.33	17.13	0.73	9.50	4.21			0.025	0.020
PE	10.59	2.31		12.37	2.58	11.13	0.33	11.52	0.79	6.79	2.75			0.025	0.020
Phosphatidylinositol	1.99	0.85	0.028	1.54	0.65	2.76	0.71	1.77	0.60	1.13	0.22		0.028		0.020
Phosphatidylserine	0.13	0.07		0.07	0.01	0.14	0.08	0.15	0.07	0.10	0.03
Lysophosphatidylcholine	1.07	0.75		0.62	0.07	0.82	0.20	1.59	1.22	1.02	0.25		0.045
Sphingomyelin	1.97	0.39		2.18	0.53	2.13	0.22	2.03	0.24	1.41	0.37				0.020
Plasmalogen	1.01	0.13		0.97	0.23	1.01	0.06	1.10	0.08	0.88	0.17
Lipid-soluble metabolites (%mol)
Omega-3 fatty acids	2.14	1.32	0.009	4.57	0.40	2.49	1.15	1.44	0.10	0.98	0.32		0.028		0.020
Oleic acid (18:1 ω-9)	24.53	4.37		16.42	1.70	24.34	4.29	26.62	1.15	26.81	2.95	0.045
Arachidonic (20:4 ω-6) + eicosapentaenoic (20:5 ω-3) acids	3.51	3.09	0.009	9.82	2.89	3.96	2.16	1.94	0.32	1.05	0.36		0.045	0.025	0.020
Docosahexaenoic acid (22:6 ω-3)	0.72	0.65	0.012	1.97	0.41	0.85	0.56	0.39	0.09	0.20	0.14		0.028		0.027
Linoleic acid (18:2 ω-6)	5.91	1.81	0.02	9.63	0.23	6.23	0.84	5.02	0.98	4.27	0.85	0.045			0.020
PUFA	20.41	17.58	0.009	55.73	12.60	23.43	12.9	11.55	1.71	5.57	3.11		0.028		0.020
MUFA, with PUFA	93.15	11.47	0.008	112.96	3.53	97.79	5.27	87.68	5.94	79.81	6.57	0.045	0.028		0.020
PUFA/MUFA ratio	0.20	0.14	0.015	0.49	0.09	0.23	0.11	0.13	0.02	0.07	0.03				0.020
PC/PE ratio	1.48	0.09		1.61	0.12	1.50	0.08	1.48	0.06	1.38	0.06
Aqueous-soluble metabolites (mmol/g liver)
Glucose-6-phosphate	32.65	13.3		41.69	32.96	35.63	7.94	34.27	4.46	17.96	12.1
Glycogen	2.19	2.34		2.57	0.62	1.70	0.81	2.95	4.11	1.66	1.67
UDPG	1.22	0.50		1.74	0.75	1.25	0.14	1.19	0.54	0.89	0.73
3-pyruvate	1.72	0.68		2.24	1.21	1.93	0.49	1.75	0.45	0.92	0.63
3-hidroxybutirate	0.76	0.35		1.04	0.86	0.71	0.25	0.69	0.25	0.78	0.40
Lactate	20.48	6.63		17.37	5.60	23.75	3.23	20.95	6.56	15.25	10.9
Fumarate	0.30	0.10		0.32	0.06	0.36	0.12	0.28	0.06	0.21	0.05				0.038
Free glycerol	1.64	0.94		1.53	0.28	1.48	0.26	1.47	0.39	2.35	2.29
NAD/NADH/NADPH	0.39	0.13		0.50	0.18	0.46	0.07	0.35	0.10	0.26	0.11				0.038
ATP/ADP/AMP	1.68	0.70		2.43	1.30	1.86	0.46	1.55	0.59	1.02	0.52				0.038
UTP/UDP/UMP	0.87	0.29		0.85	0.21	1.03	0.23	0.97	0.20	0.43	0.11			0.025	0.020
Uracil	0.04	0.02		0.03	0.01	0.05	0.02	0.04	0.01	0.02	0.02
Carnitine	1.16	0.59		2.16	0.82	1.11	0.35	1.02	0.50	0.83	0.56
Cholines	1.50	0.36		1.62	0.05	1.59	0.27	1.58	0.31	1.07	0.50
Acetates	0.48	0.11		0.45	0.02	0.54	0.08	0.49	0.13	0.39	0.12
Ascorbic acid	1.36	0.57		1.80	0.40	1.30	0.38	1.36	0.62	1.18	1.01
Leucine	0.55	0.10		0.50	0.02	0.59	0.09	0.59	0.10	0.44	0.02			0.025	0.020
Valine	0.60	0.13		0.55	0.01	0.66	0.09	0.65	0.12	0.42	0.07			0.025	0.020
Alanine	6.07	2.38		5.68	4.18	7.81	1.32	5.83	0.83	3.22	2.54		0.028		0.038
Isoleucine	0.25	0.05		0.23	0.01	0.26	0.04	0.29	0.06	0.19	0.02			0.025
Lysine	1.26	0.26		1.21	0.08	1.38	0.13	1.34	0.33	0.92	0.14				0.020
Glutamine	3.96	1.59		5.83	1.90	4.48	0.89	3.60	1.19	2.27	1.86
Glutamate	4.42	1.63	0.038	4.70	0.01	5.63	1.78	3.92	0.82	2.65	0.98				0.020
Methionine	0.80	0.24		0.76	0.24	0.84	0.23	0.70	0.18	0.90	0.42
Phenylalanine	0.26	0.05		0.25	0.02	0.29	0.03	0.27	0.04	0.17	0.05				0.020
Threonine	1.46	0.50		2.13	0.59	1.58	0.45	1.36	0.08	0.94	0.53
Tyrosine	0.20	0.05	0.026	0.16	0.04	0.24	0.02	0.21	0.04	0.14	0.05	0.045			0.020
Histidine	0.16	0.07		0.25	0.13	0.17	0.06	0.13	0.04	0.12	0.04
Taurine	12.53	4.07		17.03	1.55	13.68	4.14	11.57	1.46	8.81	5.38
Gluthathione oxidized	0.73	0.40		1.31	0.46	0.63	0.29	0.57	0.38	0.78	0.42
Creatine	3.16	1.24		4.39	0.78	3.74	0.73	2.89	0.91	1.61	1.37				0.038
Creatinine	0.15	0.04	0.010	0.15	0.01	0.19	0.02	0.12	0.02	0.10	0.05	0.045	0.006		0.020

PC: Phosphatidylcholine; PE: Phosphatidylethanolamine; PUFA: Polyunsaturated fatty acids; UDPG: Uridine diphosphate glucose; MUFA: Monounsaturated fatty acids.

Table 2 Selected variables to explore metabolic changes and anti-oxidative or anti-inflammatory effects prior to and one year after surgery

	Before surgery	After surgery	P value
BMI, kg/m2	45.4 (44.1-47.0)	32.3 (30.1-35.4)	< 0.001
Liver steatosis, %	30 (5-55)	6 (0-15)	< 0.001
Glucose, mmol/L	7.9 (6.7-10.1)	5.4 (4.6-6.2)	< 0.001
Insulin, pmol/L	114.2 (86.3-166.8)	66.9 (58.0-70.1)	< 0.001
HOMA2-IR	4.73 (1.85-10.67)	1.95 (1.30-5.80)	< 0.001
Total cholesterol, mmol/L	4.93 (4.59-5.24)	4.28 (4.05-4.87)	< 0.001
Triglycerides, mmol/L	1.76 (1.12-2.42)	1.08 (0.85-1.38)	< 0.001
HDL-cholesterol, mmol/ L	1.06 (0.94-1.23)	1.31 (1.02-1.44)	< 0.001
NEFAs, mmol/L	1.08 (0.85-1.48)	0.80 (0.61-0.96)	< 0.050
Bilirubin, mmol/L	8.2 (5.1-9.1)	9.1 (7.2-8.5)	NS
ALP, μKat/L	0.82 (0.70-1.1)	0.65 (0.54-0.92)	< 0.050
AST, μKat/L	1.03 (0.37-1.24)	0.82 (0.24-1.14)	NS
ALT, μKat/L	0.52 (0.43-1.25)	0.45 (0.33-0.97)	NS
GGT, μKat/L	0.34 (0.24-1.08)	0.30 (0.20-0.95)	NS
Amylase, μKat/L	0.67 (0.54-0.84)	0.42 (0.33-0.65)	< 0.050
Paraoxonase, U/L	214 (160-410)	360 (200-405)	< 0.050
Leptin, ng/mL	32.5 (21.2-40.1)	9.2 (6.3-11.1)	< 0.001
Adiponectin, ng/mL	4.2 (2.1-5.9)	7.5 (4.9-8.2)	< 0.001
Interleukin 6, pg/mL	0.52 (0.21-0.75)	0.43 (0.12-0. 59)	NS
Interleukin 8, pg/mL	1.86 (1.45-2.15)	1.42 (1.22-1.65)	NS
TNF-α, pg/mL	6.21 (4.35-7.82)	5.12 (3.95-7.36)	< 0.050
CCL2, pg/mL	510 (425-590)	395 (280-430)	< 0.001
Hs-CRP, mg/L	4.6 (1.5-7.2)	1.1 (0.3-1.67)	< 0.001

We only included participants with a complete dataset (n = 19). Values are expressed as median (interquartile range); AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; ALP: Alkaline phosphatase; GGT: Gamma-glutamyl transpeptidase; HOMA2-IR: Homeostatic model assessment index; NEFAs: Non-esterified fatty acids; TNF-α: Tumor necrosis factor-α; CCL2: Chemokine (C-C motif) ligand 2; Hs-CRP: High sensitivity C-reactive protein.