The Expression And Clinical Significance Of Serum Dickkopf 1 And SOST In Ankylosing Spondylitis

Objective:To investigate the clinical significance of the expressions of the bone formation related factors,such as serum Dickkopf 1(Dkk-1),Sclerostin(SOST),bone morphogenetic protein-2(BMP-2),25-hydroxy-vitaminD(25-OH-VitD),and their correlations between the activity and severity of disease in ankylosing spondylitis(AS)patients.Methods:88 AS outpatients,26 rheumatoid arthritis(RA)outpatients and 26 healthy controls(HC)were collected in the Second Affiliated hospital of Zhejiang University School ofMedicine between March 2015 and July 2015.The expressions of serum Dkk-1,SOST,BMP-2,25-OH-VitD were compared between these three groups;Correlation analysis of Dkk-1 and other serum indexes with disease activity score(ASDAS)and imaging evaluation of spine(mSASSS score)were performed.Results:The male:female ratio of AS patients was about 3:1,with the average age of 36.5± 13.5,the average disease duration of 10.4±10.3 years;Serum Dkk-1 in AS patientswas significantly higher than that of RA patients and healthy controls(1855±84.58 vs1416±115.20,1855±84.58 vs 1406±99.76,P<0.05),serum SOST increased significantly in the AS patients compared to the healthy controls(106±6.75 vs 62.78±6.39,P<0.05).There was no statistical difference in BMP-2 and VitD between these three groups.There was no statistical difference between Dkk-1,SOST and different disease activity scores(ASDAS-CRP and ASDAS-ESR).The correlation analysis suggested negative correlation between serum SOST and mSASSS(P=0.019,r2=0.062);Dkk-1 had a trend of positive correlation with mSASSS,but with no statistical significance(P>0.05);Dkk-1 and SOST had negative correlation(P=0.013,r2=0.07);Dkk-1 and VitD had a weak positive correlation(P=0.027,r2=0.061),there was no correlation with the other serum indexes.Conclusion:The expressions of serum Dkk-1 and SOST are increased in AS patients,but are independent of disease activity.The expressions of Dkk-1 and SOST are negatively correlated and SOST is negatively correlated to the spinal ossification,which suggests that they are potential markers during spine ossification process in AS,but the specificmechanism remains to be investigated.