Correlations between IFN scores and serum KYN/TRP pathway metabolite levels in subjects with SLE according to ISG expression subgroup
| ISG expression subgroup | IFN score method (z-scores) | KYN/TRP (rs) | P value | QA/KA (rs) | P value |
| IFN high (n=36) | ISG-A | 0.490 | 0.002* | 0.129 | 0.453 |
| 19 type I ISG | 0.487 | 0.003* | 0.216 | 0.205 | |
| IFN low (n=23) | ISG-A | −0.174 | 0.427 | −0.286 | 0.187 |
| 19 type I ISG | 0.269 | 0.215 | −0.210 | 0.335 | |
| IFN similar to HC(n=13) | ISG-A | 0.170 | 0.578 | −0.126 | 0.681 |
| 19 type I ISG | 0.242 | 0.426 | 0.000 | 1.000 |
Subjects with SLE were assigned to one of three subgroups: ‘IFN high’ (Z-IFN score ≥SD above HC mean), ‘IFN low’ (Z-IFN score ≥1 to <2) or ‘IFN similar to HC’ (Z-IFN score <1). In each subgroup, correlations between 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; KA, kynurenic acid; KYN, kynurenine; QA, quinolinic acid; rs, Spearman correlation; TRP, tryptophan.