Table 3.

Correlations between IFN scores and serum KYN/TRP pathway metabolite levels in subjects with SLE according to ISG and monocyte-associated gene expression subgroups

ISG expression subgroup	Monocyte-associated gene expression subgroup	IFN score method (z-scores)	KYN/TRP (rs)	P value	QA/KA (rs)	P value
IFN high (n=36)	Monocyte high (n=23)	ISG-A	0.504	0.014*	0.429	0.041*
		19 type I ISG	0.532	0.009*	0.419	0.046*
	Monocyte low (n=13)	ISG-A	0.440	0.133	−0.132	0.668
		19 type I ISG	0.330	0.271	0.044	0.887
IFN low (n=23)	Monocyte high (n=17)	ISG-A	−0.289	0.260	−0.326	0.202
		19 type I ISG	0.336	0.188	−0.252	0.328
	Monocyte low (n=6)	ISG-A	0.547	0.261	0.137	0.796
		19 type I ISG	0.429	0.396	0.073	0.890
IFN similar to HC (n=13)	Monocyte high (n=8)	ISG-A	−0.071	0.867	−0.199	0.637
		19 type I ISG	0.048	0.911	−0.024	0.955
	Monocyte low (n=5)	ISG-A	0.785	0.116	0.110	0.861
		19 type I ISG	0.500	0.391	0.100	0.873

In addition to the ISG expression subgroups previously described in table 2, subjects with SLE were further designated as either ‘monocyte high’ (monocyte-associated gene expression >HC mean) or ‘monocyte low’ (monocyte-associated gene expression ≤HC mean). In each subgroup, correlations between both IFN scores (derived from ISG-A and the 19 type I ISG) and metabolite ratios are displayed.

*Remained significant after Benjamini-Hochberg correction for multiple comparisons.

HC, healthy control; IFN, interferon; ISG, interferon-stimulated gene; KYN, kynurenine; QA, quinolinic acid; TRP, tryptophan.