Downregulation of miR-885-5p Promotes NF-κB Pathway Activation and Immune Recruitment in Cutaneous Lupus Erythematosus.

Cutaneous lupus erythematosus (CLE) has a specific microRNA expression profile. MiR-885-5p has been found to be downregulated in the epidermis of CLE lesions; however, its biological role in the disease has not been studied. In this study, we show that miR-885-5p is markedly reduced in CLE keratinocytes (KCs) with IFN-α and UVB being strong miR-885-5p regulators in vitro. Microarray expression profiling of anti‒miR-885-5p‒transfected KCs identified PSMB5 as a direct target. Specific inhibition of miR-885-5p increased epidermal proliferation by modulating keratin 16 gene K16, BIRC5, TP63, and CDK4 proliferative genes and promoted NF-κB signaling pathway in human primary KCs by increasing IκBα degradation. Silencing PSMB5 rescued the effect of miR-885-5p inhibition, indicating that miR-885-5p regulates proliferation and NF-κB activation by targeting PSMB5 in KCs. In addition, inhibition of miR-885-5p increased the ability of KCs to attract leukocytes in a PSMB5-independent manner. We identified TRAF1 as another direct target, and its silencing reduced leukocyte migration. Collectively, our findings suggest that UVB and IFN-ɑ downregulate miR-885-5p in CLE KCs, leading to epidermal inflammation by NF-κB activity enhancement and proliferation through PSMB5 and immune recruitment through TRAF1. Our data indicate that miR-885-5p is a potential therapeutic target in CLE.