BACKGROUND

Psoriasis is a chronic, inflammatory skin disease. MicroRNAs (miRNAs) are an abundant class of non-coding RNA molecules. Recent studies have shown that multiple miRNAs are abnormally expressed in patients with psoriasis. The upregulation of miR-374a-5p has been associated with psoriasis severity. However, the specific role of miR-374a-5p in the pathogenesis of psoriasis remain unclear.

METHODS

qRT-PCR was employed to validate the expression of miR-374a-5p in psoriatic lesions and in a psoriasis-like cell model constructed using a mixture of M5 (IL-17A, IL-22, OSM, IL-1α, and TNF-α). HaCaT cells were transfected with miR-374a-5p mimic/inhibitor, and assays including EdU, CCK-8, and flow cytometry were conducted to evaluate the effect of miR-374a-5p on cell proliferation. The expression of inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α was verified by qRT-PCR. Bioinformatics analysis and dual-luciferase reporter gene assay were performed to detect the downstream target genes and upstream transcription factors of miR-374a-5p, followed by validation of their expression through qRT-PCR and Western blotting. A psoriasis-like mouse model was established using imiquimod cream topical application. The psoriasis area and severity index scoring, hematoxylin-eosin histology staining, and Ki67 immunohistochemistry were employed to validate the effect of miR-374a-5p on the psoriatic inflammation phenotype after intradermal injection of miR-374a-5p agomir/NC. Additionally, the expression of pathway-related molecules and inflammatory factors such as IL-1β, IL-17a, and TNF-α was verified by immunohistochemistry.

RESULTS

Upregulation of miR-374a-5p was observed in psoriatic lesions and the psoriasis-like cell model. In vitro experiments demonstrated that miR-374a-5p not only promoted the proliferation of HaCaT cells but also upregulated the expression of inflammatory cytokines, including IL-1β, IL-6, IL-8, and TNF-α. Furthermore, miR-374a-5p promoted skin inflammation and epidermal thickening in the Imiquimod-induced psoriasis-like mouse model. Mechanistic studies revealed that miR-374a-5p led to downregulation of WIF1, thereby activating the Wnt5a/NF-κB signaling pathway. The transcription factor p65 encoded by RELA, as a subunit of NF-κB, further upregulated the expression of miR-374a-5p upon activation. This positive feedback loop promoted keratinocyte proliferation and abnormal inflammation, thereby facilitating the development of psoriasis.

CONCLUSION

Our findings elucidate the role of miR-374a-5p upregulation in the pathogenesis of psoriasis through inhibition of WIF1 and activation of the Wnt5a/NF-κB pathway, providing new potential therapeutic targets for psoriasis.