Serum exosomal tRNA-derived small RNAs as diagnostic biomarkers for primary Sjögren's syndrome: a combined model with autoantibodies.

objectiveThe identification of reliable biomarkers for the early diagnosis and monitoring of primary Sjögren's syndrome (pSS) remains a critical clinical need. Extracellular vesicles (EVs), which carry diverse molecular cargo, including tRNA-derived small RNAs (tsRNAs), have emerged as novel regulators of immune responses. This study aimed to profile EV-associated tsRNAs in pSS and evaluate their diagnostic potential.

methodsSerum EVs were isolated from pooled samples (20 individuals per pool) of pSS patients and age- and sex-matched healthy controls (HCs). High-throughput tsRNA sequencing was performed to identify differentially expressed candidates. In the training cohort (23 pSS and 23 HCs), candidate tsRNAs were quantified in serum EVs using SYBR Green-based RT-qPCR. The top two tsRNAs were validated in an independent cohort of 92 individuals (46 pSS and 46 HCs). The diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis. Bioinformatic analyses were conducted to explore the potential functional pathways associated with the identified tsRNAs.

resultsAmong the differentially expressed tsRNAs, serum exosomal levels of tRNA-Val-CAC_5_end and tRNA-His-GTG_5_end were significantly elevated in pSS patients compared to HCs. ROC analysis revealed that tRNA-Val-CAC_5_end had an AUC of 0.9750 (95% CI, 0.9496-1.000), while tRNA-His-GTG_5_end demonstrated a higher AUC of 0.9759 (95% CI, 0.9513-1.000). When compared to conventional pSS markers, anti-SSA and anti-SSB antibodies showed AUCs of 0.9966 (95% CI, 0.9893-1.000) and 0.9725 (95% CI, 0.9444-1.000), respectively. Integrating tsRNAs with autoantibodies enhanced diagnostic accuracy, with the combination of both candidate tsRNAs with anti-SSA achieving the highest AUC of 0.9971 (95% CI, 0.9907-1.000). Bioinformatic analyses further suggested that these tsRNAs may be involved in immune regulation by modulating key signaling pathways, providing mechanistic insights into their clinical relevance.

conclusionThis study identifies EV-derived tsRNAs as promising non-invasive biomarkers for the early diagnosis and monitoring of pSS. These findings offer new perspectives on EV-mediated tsRNA regulation in autoimmune diseases and highlight their translational potential for clinical applications. Key Points • Two serum exosomal tsRNAs (tRNA-Val-CAC_5_end, tRNA-His-GTG_5_end) are upregulated in pSS; combined with anti-SSA, they form a diagnostic model with AUC 0.9971. • This tsRNA panel performed well in anti-SSA/SSB seronegative pSS, with its combination reaching an AUC of 0.9881. • Expression changes of the two tsRNAs are independent of inflammation and immunosuppressive therapy; they are hypothesized to be involved in pSS-related neuro-immune pathogenic mechanisms.