Usefulness of miRNA-338-3p in the diagnosis of pemphigus and its correlation with disease severity

BACKGROUND: Pemphigus is a common life-threatening, autoimmune bullous disease effecting both cutaneous and mucous membranes. Previous diagnosis of pemphigus is based on clinical presentations, histopathology, immunofluorescence and enzyme-linked immunosorbent assay. Furthermore, no laboratory parameters could be used to indicate disease severity. MicroRNAs are endogenous small RNAs, which could be used as diagnostic biomarkers for some autoimmune diseases. Previously, miR-338-3p has been proven significantly up-regulated in pemphigus patients. METHODS: Pemphigus patients (including pemphigus vulgaris and pemphigus foliaceus) with active lesions and with remission, patients diagnosed as bullous pemphigoid and healthy volunteers were recruited, and miR-338-3p expression level was measured using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). Active pemphigus patients accepting treatment were followed up for at least 2 weeks to investigate the expression change of miR-338-3p during treatment period. Target genes of miR-338-3p were screened through computer-aided algorithm and verified by RT-qPCR, Western blot and Luciferase activity assay. RESULTS: MiR-338-3p was specifically increased in patients diagnosed as pemphigus with active lesions. The expression level of miR-338-3p gradually decreased after effective treatment. MiR-338-3p expression was independently correlated with disease severity defined by PDAI (Pemphigus Disease Area Index) or ABSIS (Autoimmune Bullous Skin Disorder Intensity Score) criteria. Up-regulation of miR-338-3p could significantly suppress RNF114 expression at mRNA and protein level in vitro. DISCUSSION: MiR-338-3p could be used as a diagnostic biomarker of pemphigus in addition to other traditional methods. Up-regulation of MiR-338-3p was associated with more severe condition in pemphigus. RNF114 is the target gene of miR-338-3p, which probably participates in the regulation of disease activity of pemphigus.