Downregulated expression of miR-155, miR-17, and miR-181b, and upregulated expression of activation-induced cytidine deaminase and interferon-α in PBMCs from patients with SLE.

Objective: Recent studies on systemic lupus erythematosus (SLE) revealed that microRNAs (miRNAs or miRs) were involved in its pathogenesis. However, only a limited number of miRNAs have been examined.

Methods: We performed quantitative real-time reverse transcription-polymerase chain reaction analyses of peripheral blood mononuclear cells (PBMCs) obtained from 31 untreated SLE patients and 31 healthy subjects to examine the expression levels of miR-155, miR-17, and miR-181b, as well as those of activation-induced cytidine deaminase (AID) and interferon-α (IFN-α) messenger RNAs (mRNAs). We examined the relationship between miR-181b, AID, and IFN-α with a luciferase reporter assay.

Results: The expression levels of miR-155, miR-17, and miR-181b were significantly lower in SLE patients than those in healthy controls, whereas those of AID and IFN-α mRNAs were significantly higher in SLE patients than those in healthy controls. The expression levels of miR-155, miR-17, and miR-181b inversely correlated with those of AID and IFN-α mRNAs in SLE patients. The results of the luciferase reporter assay revealed that miR-181b negatively regulated AID and IFN-α.

Conclusions: The results of the present study demonstrated for the first time that there is a differential expression and inverse correlation between the levels the miR-155, miR-17, and miR-181b and target molecules, AID and IFN-α mRNAs, in PBMCs of untreated SLE patients. These alterations may contribute to the pathogenesis of SLE.