MicroRNAs in psoriasis and psoriatic arthritis: a narrative review of potential diagnostics and current challenges

Background and Objective: Psoriasis (PsO) and psoriatic arthritis (PsA) are diseases characterized by inflammatory processes and distinct manifestations, with clinical and pathophysiological overlap. Early differentiation between these pathologies is essential to guide therapeutic approaches and interventions. MicroRNAs (miRNAs), small non-coding RNA molecules that regulate gene expression post-transcriptionally, are emerging as potential molecular biomarkers for this purpose. This narrative review synthesizes evidence on circulating and cellular miRNAs that are differentially expressed in PsO and PsA, using human biological samples. Methods: A comprehensive search of PubMed and Web of Science identified full-text articles published in English from 2010 to April 2025 using the terms “psoriasis”, “psoriatic arthritis”, and “microRNA”. Eligible studies quantified miRNAs in human serum, plasma, peripheral blood mononuclear cells (PBMCs), or extracellular vesicles. Studies based solely on in silico approaches, in vitro experiments without human validation, or animal models were excluded. Data were narratively integrated, with emphasis on study design, sample type, methodological variability, and differential miRNA signatures between PsO and PsA. Key Content and Findings: Across 17 studies, recurrent miRNAs included miR-146a-5p, miR-21-5p, miR-92a-3p, miR-126-3p, miR-let-7b-5p, and miR-140. miR-146a-5p consistently emerged as a key mediator of Toll-like receptor (TLR)/nuclear factor kappa B (NF-κB) signaling and osteoclast activation, while miR-21-5p was broadly associated with inflammatory responses and therapeutic modulation. Several miRNAs demonstrated more substantial discriminatory potential for PsA, particularly miR-92a-3p, miR-let-7b-5p, miR-30e-5p, miR-941, and miR-210-3p, as well as members of the miR-23a-27a-24-2 and miR-26a/miR-130a clusters, especially in PBMCs and extracellular vesicles. However, methodological heterogeneity, ranging from differences in sample type, normalization strategies, and analytical platforms to variable clinical criteria, substantially limits cross-study comparability and reduces immediate translational applicability. Conclusions: Although several miRNAs show promise as candidate biomarkers to differentiate PsO from PsA or predict progression to the articular phenotype, evidence remains inconsistent and highly context-dependent. Large, multicenter, and methodologically standardized studies are required for validation. Methodological standardization in sample collection, analytical platforms, and data normalization is essential to enable reproducibility and facilitate clinical implementation.