Abstract
MicroRNAs (miRNAs) are evolutionarily conserved, non-coding RNA molecules approximately 18–25 nucleotides in length that regulate gene expression at the post-transcriptional level. Their principal mechanism of action is post-transcriptional gene silencing via RNA interference, achieved by binding to complementary sequences within target messenger RNAs (mRNAs). Accumulating evidence has highlighted the pivotal role of miRNAs in the development, differentiation, and function of immune cells, as well as in maintaining immune homeostasis. A more comprehensive understanding of the complex molecular networks governed by these miRNAs may provide valuable insights into disease mechanisms, facilitate clinical decision-making, and ultimately improve patient outcomes. The remarkable stability of miRNAs, together with their presence in the systemic circulation encapsulated within extracellular vesicles, has attracted considerable interest in their clinical application. These characteristics make circulating miRNAs promising candidates as diagnostic biomarkers for the early detection of disease and as prognostic indicators for disease progression and evaluating therapeutic efficacy. Furthermore, an increasing number of miRNA-based studies across diverse immune-related disorders have revealed their potential as therapeutic targets. The integration of synergistic therapeutic strategies and complementary miRNA-based approaches may further enhance treatment efficacy and contribute to the development of novel precision-medicine interventions for immune-related diseases. In this review, we comprehensively discuss the biogenesis and biological functions of miRNAs and examine their regulatory roles in the pathogenesis of rheumatoid arthritis (RA), inflammatory bowel disease (IBD), multiple sclerosis (MS), psoriasis, systemic lupus erythematosus (SLE), and atopic dermatitis (AD). We are also evaluating the potential of these miRNAs as diagnostic and prognostic biomarkers, and their promising properties as therapeutic targets in the treatment of immune system-related diseases. These selected diseases represent key immune disorders in which miRNAs serve as strong biomarker candidates for early diagnosis (diagnostic) and disease course (prognostic) due to their stability in systemic circulation and their presence within extracellular vesicles. These six diseases constitute the cluster of “immune-related disorders,” where miRNA-based studies are steadily increasing, and these molecules hold the highest potential as novel therapeutic targets.