The role of serum IL-17 and IL-6 as biomarkers of disease activity and predictors of remission in patients with lupus nephritis.
AIM
To determine the role of IL-17 and IL-6 in the pathogenesis of SLE as biomarkers of disease activity and predictors of remission and outcome of therapy in patients with active lupus nephritis.


METHODS
The study was carried out on 72 SLE female patients and 70 sex- and age-matched normal healthy subjects as controls. SLE disease activity was assessed in all patients with (SLEDAI-2k scores). Plasma levels of IL-6, and IL-17 were measured by enzyme linked immunosorbent assay and their levels were correlated with clinical manifestations of the disease and (SLEDAI-2k). ROC curve analysis was performed to determine the validity of both cytokines in prediction of activity and remission of active lupus nephritis.


RESULTS
SLE patients were found to have significantly higher levels of IL-17 (p<0.001) and IL-6 (p<0.001), in relation to normal subjects. Active group of patients had higher levels of both cytokines than the inactive one (P<0.001). Elevated serum levels of both cytokines were associated with active lupus nephritis, anemia and positively correlated with SLEDAI-2k scores (P=0.025 for IL-17 and P<0.001 for IL-6). There was a significant positive correlation between IL-6 and IL-17 serum concentrations during periods of disease activity (r=0.497, P=0.005) as well as during remission (r=0.662, P<0.001). ROC curve analysis for IL-6 and IL-17, as predictor of disease activity reviled, optimal cutoff level of 12.3 pg/ml and 19.7 pg/ml, with AUC=0.93, and 0.95, for both cytokines respectively, while as predictors of remission of active lupus nephritis, provide a cutoff value of IL-6 at 20.8 pg/ml, with AUC 0.80, and a cutoff value of IL-17 at 27.0 pg/ml, with AUC 0.82.


CONCLUSION
In conjunction with their major role in pathogenesis of SLE, baseline serum levels of IL-6 and IL-17 can be used as sensitive biomarkers for disease activity, as well as predictors of remission of lupus nephritis.