Hydroxychloroquine suppresses interferon-inducible genes and B-cell activating factor in patients with incomplete and new onset systemic lupus erythematosus

Objective Hydroxychloroquine (HCQ) is commonly used as first line treatment for systemic lupus erythematosus (SLE). Interferon (IFN) -inducible gene expression, IFN-gamma induced protein 10 (IP-10) and B-cell activating factor (BAFF) are early mediators in SLE. The purpose of this study is to analyze the effects of HCQ on these factors. Methods Patients with incomplete SLE (iSLE) (ANA titer ≥1:80, symptoms <5 years, ≥ 1 objectified clinical ACR or SLICC criterion), or new onset, mild SLE were included when HCQ treatment was started for clinical reasons. Blood samples were taken at start and after 16 weeks. Three SLE-related IFN-inducible genes were measured in whole blood by RT-PCR, and an IFN score was calculated. Serum levels of IP-10 and BAFF were measured using ELISA. Results In total, nine patients were included: seven with iSLE and two with new onset SLE. The median SLEDAI was four. After 16 weeks of treatment with HCQ, the expression of IFN- inducible genes decreased in eight of nine patients, and the IFN-3 score decreased significantly (p=0.012). There was a trend towards lower IP-10 levels (p=0.078), and a significant decrease in BAFF-levels (p=0.023). Conclusion HCQ suppresses IFN score and BAFF levels in patients with incomplete or new onset SLE, and there is a trend towards lowering IP-10 levels. As these biomarkers are early mediators in SLE, this might support the hypothesis that HCQ could possibly influence disease progression.. However, prospective research with a larger sample size and longer follow up is needed.