Objective To explore the relationships of serum sclerostin and Dickkopf-1 (DKK-1) levels with severity of disease in patients with systemic lupus erythematosus (SLE).

Methods A total of 126 patients with SLE from January 2020 to January 2022 were selected as SLE group, and the patients in the SLE group were divided into mild active group (n=46), moderate active group (n=42) and severe active group (n=38) according to SLE disease activity index (SLEDAI) score; 70 healthy people in the same period were selected as control group. The serum levels of Sclerostin and DKK-1 in both groups were detected by enzyme-linked immunosorbent assay. Pearson correlation analysis was used to explore the correlations of the serum Sclerostin and DKK-1 levels with biochemical indicators in the SLE group. Multivariate Logistic regression model was used to analyze the factors affecting the severity of disease in SLE patients. Receiver operating characteristic (ROC) curve was used to assess the values of serum Sclerostin and DKK-1 in evaluating the severity of disease in SLE patients.

Results Serum levels of Sclerostin, DKK-1, erythrocyte sedimentation rate and anti-double stranded DNA antibody (anti-dsDNA antibody) in the SLE group were significantly higher than those in the control group, while the levels of leukocyte count, hemoglobin, lymphocyte count, platelet, complement C3 and C4 were significantly lower than those in the control group (P < 0.01). Pearson correlation analysis results showed that serum levels of Sclerostin and DKK-1 in the SLE group were significantly negatively correlated with leukocyte count, hemoglobin, lymphocyte count, platelet, complement C3 and complement C4 (P < 0.01), and were significantly positively correlated with erythrocyte sedimentation rate and anti-dsDNA antibody (P < 0.01). The serum levels of Sclerostin and DKK-1 in the severe active group were significantly higher than those in the moderate active group and mild active group, and the serum levels of Sclerostin and DKK-1 in the moderate active group were significantly higher than those in the mild active group (P < 0.05). Elevated levels of serum Sclerostin and DKK-1 were the independent risk factors affecting the severity of SLE. The area under the curve (AUC) of serum Sclerostin combined with DKK-1 for predicting high activity of SLE was 0.919 (95%CI, 0.862 to 0.956), which was significantly higher than 0.833 of serum Sclerostin (Z=4.978, 95%CI, 0.809 to 0.851, P < 0.001) and 0.841 of DKK-1 (Z=4.213, 95%CI, 0.810 to 0.867, P < 0.001).

Conclusion The increased expression levels of serum Sclerostin and DKK-1 in SLE patients are related to the severity of SLE, and are the independent risk factors affecting the severity of SLE. The combination of serum Sclerostin and DKK-1 has a high predictive value for the severity of SLE.