A cluster of type II interferon-regulated genes associates with disease activity in patients with systemic lupus erythematosus

• Published in: Journal of autoimmunity Vol. 132; p. 102869
• Main Authors: Siddiqi, Kanwal Zahid, Zinglersen, Amanda Hempel, Iversen, Katrine Kjær, Rasmussen, Niclas Stefan, Nielsen, Christoffer Tandrup, Jacobsen, Søren
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2022
• Subjects: Disease activity; Interferon signature; Interferon-regulated genes; SLEDAI-2K; Systemic lupus erythematosus; SLEDAI-2K; Interferon-regulated genes; Systemic lupus erythematosus; Interferon signature; Disease activity
• ISSN: 0896-8411; 1095-9157
• DOI: 10.1016/j.jaut.2022.102869

Upregulation of interferon-regulated genes (IRGs), denoted IFN signature, in peripheral blood has been used as an indirect measure of IFN pathway activation in patients with systemic lupus erythematosus (SLE). However, it has not been determined, which IFN signatures that optimally reflect clinical disease activity.
In this study, we determined an IFN signature based on the expression of 128 IRGs in whole blood from 34 SLE patients in a cross-sectional (CS) study, 11 with active lupus nephritis followed longitudinally (LS) and 15 healthy controls. Blood samples were collected in PAXgene tubes and RNA was extracted and purified using a PAXgene blood RNA kit (Qiagen). Gene expression was measured using the NanoString nCounter Gene Expression platform.
The CS SLE patients with higher disease activity displayed thrice as many upregulated IRGs (n = 46) as the rest. These IRGs clustered in three groups, consisting of IRGs known to be predominantly stimulated by type I (gene cluster K1) and type II (gene clusters K2 and 3) IFNs. SLEDAI-2K scores associated with the K2 and K3 gene scores (β = 0.372 and β = 0.419, both p < 0.015) but not with K1. In the longitudinal study, the mean SLEDAI-2K score decreased after an average follow-up of 360 days (β = −2.08, P = 5.09 × 10−12). The mean K1, K2 and K3 gene scores did not change over time, however longitudinal changes in SLEDAI-2K and K3 scores were associated (β = 0.814, p = 0.007).
This study validates the presence of type I IRG subsets that do not associate with disease activity in SLE patients. The novel finding in this study is the association between a type II IRG subset and disease activity. Both findings may have significant implications for choosing IRGs defining clinically relevant IFN signatures.
•Interferon signatures in SLE are complex and consisted of both type I and type II interferon-regulated genes.•Type I interferon-regulated genes were stably upregulated in SLE patients over time, independent of disease activity.•Type II interferon-regulated genes were preferentially upregulated in SLE patients with higher disease activity.•Fluctuations in disease activity over time were associated with expression of type II interferon regulated genes.