Clinical relevance of plasma miR-21 in new-onset systemic lupus erythematosus patients.

Background: Plasma miR-21 is widely investigated as biomarker in many diseases. Recent studies show that miR-21 participates in the development of systemic lupus erythematosus (SLE). The aim of this study was to evaluate the expression profile of miR-21 in the plasma of SLE patients.

Methods: Relative quantities of plasma miR-21 both in SLE patients and healthy controls were determined by relative qRT-PCR under endogenous and exogenous controls. The diagnostic value of plasma miR-21 was evaluated in SLE patients. Data of some SLE-associated clinical parameters were collected.

Results: Eighty participants from Central China were recruited. Forty-four participants were new-onset SLE patients and the others were healthy controls. Plasma miR-21 level in SLE patients was higher than that of healthy controls (P = 0.031). Receiver operating characteristic analysis of plasma miR-21 revealed an Area Under Curve (AUC) of 0.64 ± 0.06 (95% CI: 0.51-0.76, P = 0.03854) when differentiating SLE from healthy controls. The level of plasma miR-21 was not associated with the level of white blood cells (P = 0.4284), red blood cells (P = 0.4079), and platelets (P = 0.4961), but significantly correlated with the level of plasma complement C3 (r = -0.5297, P = 0.0004), C4 (r = -0.4732, P = 0.0020), and serum uric acid (r = 0.3932, P = 0.0121) in SLE patients.

Conclusions: Plasma miR-21 in SLE patients from Central China is overexpressed. Since circulating miR-21 is aberrantly expressed in many diseases, the applying of it as a disease biomarker should be considered carefully.