Serum exosomal miR-146a-3p associates with disease severity and efficacy of sublingual immunotherapy in allergic rhinitis

•Serum exosome-derived miRNAs were differentially expressed in AR patients.•Serum exosomal miRNA-146a-3p levels were significantly upregulated in AR patients.•Serum exosomal miRNA-146a-3p levels were correlated with disease severity in AR patients.•Serum exosomal miRNA-146a-3p was a novel biomarker for predicting the efficacy of SLIT. Sublingual immunotherapy (SLIT) is an effective treatment for allergic rhinitis (AR), but its efficacy is variable among individuals. This study aimed to characterize serum exosome-derived microRNAs (miRNAs) and evaluate their abilities in predicting the efficacy of SLIT in AR. RNA sequencing was performed to explore differentially expressed exosomal miRNAs in serum exosomes between AR patients and healthy controls (HCs). Sequencing analysis results were verified in an independent cohort, and the correlations between the levels of exosome-derived miRNAs and disease severity were evaluated. The most promising miRNAs were further tested in two AR cohorts treated with SLIT to assess their abilities in predicting short and long-term efficacy, respectively. The exosome-derived miRNAs profiling in the AR group was significantly different from the HC group, and differentially expressed genes were enriched and clustered in pathways such as PI3K-Akt and ErbB signalling pathways. The top three most significant miRNAs were verified by reverse transcription-polymerase chain reaction (qRT-PCR), and results showed that miR-146a-3p levels were significantly elevated in the AR group and correlated with the total and specific gE levels, the visual analogue scale of the total nasal symptom score (all p