Clinical utility of serum autotaxin in systemic lupus erythematosus: association with disease activity and renal involvement

Abstract Background Emerging evidence indicates that autotaxin (ATX) produced by plasmacytoid dendritic cells contributes to immune dysregulation and the pathogenesis of systemic lupus erythematosus (SLE). ATX is closely associated with type I interferon signaling, highlighting its potential role as a biomarker and key mediator of SLE. The study aimed to assess serum ATX levels in SLE patients compared with healthy controls and to evaluate their associations with clinical manifestations, laboratory findings, and disease activity, with particular emphasis on renal involvement. Patients and methods The study included 60 SLE patients and 30 age- and sex-matched controls. Disease activity was assessed using the SLE Disease Activity Index 2000 (SLEDAI-2K). Patients were classified into those with active lupus nephritis (ALN; renal SLEDAI-2K ≥ 4) and those with no-renal activity (NRA; renal SLEDAI-2K = 0). Serum ATX levels were measured using enzyme-linked immunosorbent assay (ELISA). Results The patients were 51 females and 9 males, with a mean age of 33.7 ± 9.3 years. Thirty-one patients had ALN and 29 had NRA. Serum ATX levels were significantly higher in SLE patients than in controls (2023.4 ± 1955.6 vs. 932.5 ± 147.6 pg/ml, p < 0.001). Patients with ALN had significantly higher serum ATX levels than those with NRA (2694.9 ± 2557.6 vs. 1305.5 ± 130.7 pg/ml, p < 0.001) and controls ( p < 0.001 in both), whereas no significant difference was observed between NRA and controls ( p = 0.358). Serum ATX demonstrated excellent diagnostic performance in differentiating SLE patients from controls. At a cut-off value of > 1147 pg/ml, it achieved 96.7% sensitivity, 92.9% specificity, with an area under the curve (AUC) of 0.989 ( p < 0.001). It also accurately discriminated ALN patients from those with NRA, at a cut-off value of > 1571 pg/ml, it yielded 90.3% sensitivity, 100% specificity, with an AUC of 0.992 ( p < 0.001). In multivariate regression analysis, only the renal SLEDAI-2K score remained an independent predictor of elevated serum ATX levels (β = 302.2, p = 0.01). Conclusion Serum ATX may represent a promising biomarker for assessing disease activity in SLE patients, with particular relevance to renal involvement, warranting further validation in larger prospective studies.