. 2023 Aug 8;10:1215039. doi: 10.3389/fmolb.2023.1215039

TABLE 5.

Relevant metabolites in SSc patients identified through targeted metabolomics studies.

Sample type	Sample size	Analytical technique	Quantified metabolite	Concentration patients vs. controls (mean ± SD)	Study
Plasma	SSc: 60	HPLC-FLD	Homocysteine	11.8 (10.3–14.5) vs. 6.5 (5.4–8.8) µmol/L ^b	Caramaschi et al. (2007)
	Controls: 30	HPLC-FLD	Homocysteine	11.8 (10.3–14.5) vs. 6.5 (5.4–8.8) µmol/L ^b	Caramaschi et al. (2007)
	SSc: 15	GC-MS ^a	Malondialdehyde	20.3 vs. 2.48 nmol/L	Tikly et al. (2006)
	Controls: 13	GC-MS ^a	Malondialdehyde	20.3 vs. 2.48 nmol/L	Tikly et al. (2006)
	SSc: 71	HPLC-FLD	Homocysteine	11.1 vs. 6.9 μmol/L	Caramaschi et al. (2003)
	Controls: 30	HPLC-FLD	Homocysteine	11.1 vs. 6.9 μmol/L	Caramaschi et al. (2003)
	SSc: 40	HPLC-MS ^a	Vitamin D	25.77 (±12.84) vs. 35.08 (±9.07) ng/mL	Atteritano et al. (2016)
	Controls: 40	HPLC-MS ^a	Vitamin D	25.77 (±12.84) vs. 35.08 (±9.07) ng/mL	Atteritano et al. (2016)
	SSc: 42 Controls: 27	HPLC-TQ-MS	Glutamine	689 (±122.3) vs. 618.4 (±165.3) µmol/L	Smolenska et al. (2020)
			Proline	178.8 (±55.2) vs. 152.5 (±47.3) µmol/L
			1-Methylhistidine	5.7 (±3.9) vs. 4.1 (±1.5) µmol/L
			Asymmetric dimethylarginine	0.344 (±0.112) vs. 0.289 (±0.10) µmol/L
			Betaine	64.8 (±20.8) vs. 52.8 (±17.8) µmol/L
			Tryptophan	32.5 (±9.6) vs. 40.8 (±12.3) µmol/L
			Methylnicotinamide	0.312 (±0.166) vs. 0.232 (±0.106) µmol/L
Serum	SSc: 10	HPLC-QTRAP-MS	Arachidonoyl (20:4)-LPA	2.54 (±0.15) vs. 1.15 (±0.37) nmol/mL	Tokumura et al. (2009)
	Controls: 13	HPLC-QTRAP-MS	Arachidonoyl (20:4)-LPA	2.54 (±0.15) vs. 1.15 (±0.37) nmol/mL	Tokumura et al. (2009)
	SSc- PAH: 15	HPLC-FLD	Arginine	97.28 (±27.4) vs. 117.45 (±26.07) µmol ^c	Thakkar et al. (2016)
	SSc Non-PAH: 30	HPLC-FLD	Asymmetric dimethylarginine Symmetric dimethylarginine	0.76 (±0.14) vs. 0.59 (±0.07) µmol ^c 0.76 (±0.26) vs. 0.46 (±0.07) µmol ^c	Thakkar et al. (2016)
Urine	SSc: 11	GC-EI-MS	15-F-2t-isoprostane	178 (±32) vs. 95 (±1) µmoles/mmole of creatinine	Cracowski et al. (2002)
	Controls: 11	GC-EI-MS	15-F-2t-isoprostane	178 (±32) vs. 95 (±1) µmoles/mmole of creatinine	Cracowski et al. (2002)
	SSc: 43	HPLC-UV	8-isoprostaglandin-F2a	341.7 vs. 147.6 pg/mg creatinine	Volpe et al. (2006)
	Controls: 43	HPLC-UV	8-isoprostaglandin-F2a	341.7 vs. 147.6 pg/mg creatinine	Volpe et al. (2006)
Exhaled breath	SSc: 46	GC-FID	Ethane	5.27 vs. 2.72 µmol ${m l}^{- 1}$ ${C O}_{2}$	Cope et al. (2006)
Exhaled breath	Controls: 21	GC-FID	Ethanol	32.5 vs. 76.0 µmol ${m l}^{- 1}$ ${C O}_{2}$	Cope et al. (2006)

^{^a}

Detector is not specified in the document.

^{^b}

IQR, interquartile range.

^{^c}

Comparison between SSc, patients with PAH vs. SSc, patients without PAH.

Abbreviations: SSc, Systemic sclerosis; SD, standard deviation; PAH, pulmonary arterial hypertension; GC-MS, Gas chromatography-mass spectrometry; HPLC-TQ-MS, High-performance liquid chromatography coupled to triple-stage quadrupole mass spectrometer; HPLC-QTRAP-MS, High-performance liquid chromatography quadrupole-linear ion trap hybrid mass spectrometry; HPLC-FLD, High-performance liquid chromatography with fluorescence detection; GC-EI-MS, gas chromatography electron impact mass spectrometry; HPLC-UV, High-performance liquid chromatography with on-line UV, system; CGC-FID, capillary gas chromatography flame ionization detection.