Table 2

Metabolites in kynurenine pathway (LC-MS/MS data) in SLE, controls and SLE subgroups

Tryptophan (μM)*Kynurenine (nM)*Quinolinic acid (nM)*Kynurenine/tryptophan*Quinolinic acid/kynurenine*
SLE cohort (n=132)56.55±23965.9±530545.8±4800.019±0.0150.57±0.30
Controls (n=30)61.83±14712.0±230379.5±1500.012±0.00480.54±0.15
SLE versus controlsP=0.10 P=0.0001 P=0.001 P<0.0001 P=0.44
SLEDAI <6 (n=82)58.34±25977.8±590511.6±4500.019±0.0160.54±0.27
SLEDAI ≥6 (n=50)53.60±19946.3±440602.0±5400.020±0.0120.63±0.35
Active SLEDAI† versus control P=0.03 P=0.003 P=0.007 P=0.0002 P=0.14
Inactive SLEDAI versus controlP=0.35 P=0.0008 P=0.02 P=0.0002 P=0.93
Active versus inactive SLEDAIP=0.22P=0.72P=0.32P=0.97P=0.14
SLAM <7 (n=54)58.86±28909.9±570498.4±4900.018±0.0150.54±0.26
SLAM ≥7 (n=78)54.95±191005±510578.6±4800.020±0.0140.60±0.33
Active SLAM‡ versus control P=0.04 P<0.0001 P=0.001 P<0.0001 P=0.28
Inactive SLAM versus controlP=0.51 P=0.03 P=0.10 P=0.006 P=0.98
Active versus inactive SLAMP=0.37P=0.33P=0.35P=0.36P=0.32
Severe fatigue (n=100)§54.17±20958.7±510538.6±4400.020±0.0140.59±0.33
No/limited fatigue (n=29)64.17±31939.1±630527.9±6100.017±0.0160.52±0.22
Severe fatigue versus control P=0.02 P=0.0003 P=0.002 P<0.0001 P=0.32
No/limited fatigue versus controlP=0.71P=0.07P=0.20P=0.12P=0.62
Severe versus no/limited fatigueP=0.11P=0.88P=0.93P=0.34P=0.21

  • *Mean±SD. P values obtained using Mann-Whitney U test.

  • †Active disease=SLEDAI ≥6.

  • ‡Active disease=SLAM ≥7.

  • §No/limited fatigue were defined as FSS <4 and severe fatigue as FSS 4–7.

  • FSS, Fatigue Severity Scale; SLAM, Systemic Lupus Activity Measures; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index.