Background/Purpose:   Individuals with clinically suspect arthralgia (CSA) with positivity of antibodies to citrullinated protein antigens (ACPA) have articular symptoms without clinical signs of arthritis. CSA patients are considered at high risk for progression to RA. The altered expression of miRNAs contributes to the development and maintenance of autoimmune diseases. Moreover, miRNAs appear promising diagnostic and/or prognostic biomarkers. We aimed to investigate differentially expressed peripheral blood mononuclear cell (PBMC)-contained and cell-free circulating miRNAs in CSA and healthy controls (HC).

Methods: The study included 19 CSA individuals and 23 HC. Clinical disease activity assessments (DAS28, SDAI) and disease activity assessed by patient on VAS were performed. By definition, all patients had swollen joint count 0. Ultrasound (US) of 28 small joints was performed in CSA to evaluate subclinical synovitis. Total RNA from plasma and PBMC was isolated using phenol-chloroform extraction or miRNeasy Mini Kit. A comprehensive analysis of miRNAs was performed using TaqMan® Low Density Array (TLDA) in 5 samples per group. The expression of miR-451a was further validated by single assays and normalized to RNU44 for PBMC or an average of 3 spike-in C. elegans controls for circulating miRNAs. dCt was used for relative quantification.

Results: All CSA patients were ACPA+ with CRP 9.1±19.6 mg/l. 9 CSA patients had no activity on US (grey scale≤1 and power doppler=0). Out of the 380 miRNAs analysed by TLDA, 194 miRNAs were detected in PBMC of CSA and 198 in HC while 125 circulating miRNAs were detected in plasma of CSA and 124 in HC. TLDA analysis revealed 2.43x higher levels of miR-451a in PBMC and 1.55x lower levels of circulating miR-451a in CSA compared to HC. Further validation confirmed 3.19x higher expression of miR-451a in PBMC in CSA compared to HC (p=0.001). These levels in CSA significantly correlated with DAS28(CRP) (r=0.575; p=0.010), SDAI (r=0.676; p=0.004) and VAS (r=0.484; p=0.036), but not with tender joint count (r=0.401; p=0.089), ESR (r=-0.042; p=0.869) or CRP (r=0.238; p=0.328). No difference in expression of circulating miR-451a or association with disease activity was demonstrated. Subclinical activity as per US findings had no effect on the levels of miR-451 in PBMC or plasma. There was no correlation between circulating and PBMC levels of miR-451a (r=0.265; p=0.124)

Conclusion: Although CSA cannot be considered a disease itself, and is rather a clinical suspicion of a disease, high levels of miR-451 in PBMC distinguish these at high risk individuals from HC. Moreover, miR-451 reflects the activity at this pre-clinical phase. Acknowledgement: MHCR 023728 and SVV 260263 projects.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/high-levels-of-mir-451a-differentiate-patients-at-risk-of-developing-ra-from-healthy-controls/