Background/Purpose: The altered expression of miRNAs contributes to the pathophysiology of inflammatory conditions. In addition, circulating miRNAs may serve as promising therapeutic and prognostic biomarkers. Our aim was to investigate the effect of anti-TNF therapy on the levels of circulating miRNAs in patients with ankylosing spondylitis (AS).

Methods: Our study included 19 AS patients. Disease activity scores (ASDAS-CRP, BASDAI) and laboratory parameters of disease activity were obtained at baseline (M0), month 3 (M3) and 12 (M12) after initiation of anti-TNF therapy. Total RNA was isolated from plasma using miRNeasy Serum/Plasma Kit (Qiagen). A comprehensive analysis of miRNAs was performed using TaqMan Low Density Array (TLDA) in 3 patients at M0, M3 and M12. dCt method was used for relative quantification: dCt=Ct(miRNA)–Ct(array average). Seventeen miRNAs with >1.5-fold change in the expression prior and after the therapy initiation in all 3 samples were selected for next validation using single assays. The levels of miRNAs in validation measurements were normalized to an average of 3 spike-in controls of C. elegans origin: dCt=Ct(spike-in average)-Ct(miRNA). Data were analyzed using ANOVA with Bonferroni corrections and Spearman’s correlation coefficient.

Results:

All AS patients had high disease activity (BASDAI 6.3±1.5, ASDAS 4.1±0.7, CRP 32.5±28.9mg/l, ESR 40.1±19.6mm/h) prior commencing anti-TNF therapy with a good therapeutic response at M3 (BASDAI 2.8±1.2, ASDAS 2.15±0.65, CRP 9.8±13.6mg/l, ESR 15.2±21.3mm/h, p<0.001 for all comparisons) and M12 (BASDAI 2.3±1.7, ASDAS 1.9±0.9, CRP 7.4±9.6mg/l, ESR 13.7±12.2mm/h, p<0.001 for all comparisons).

Out of all 380 miRNAs analyzed by TLDA, 125 miRNAs were detected in all samples, 148 miRNAs were detected at M0, 154 at M3 and 151 at M12. Validation of 17 selected miRNAs confirmed significant downregulation of miR-145 at M3 (TLDA 1.59-change; single assays 1.62-change, p=0.024), but the downregulation did not reach statistical significance at M12 (TLDA 1.46-change; single assays 1.11-change, p>0.05)

At baseline, miR-145 positively correlated with VAS (r=0.450, p=0.048). In addition, the decrease in miR-145 expression from M0 to M3 significantly correlated with disease activity improvement over time from M3 to M12 as per BASDAI (ΔBASDAI M3/12=-0.50±1.93, r=0.670, p=0.002) and ASDAS scores (ΔASDAS M3/12=-0.28±0.70, r=0.614, p=0.005) and VAS at M12 (r=0.528, p=0.020). In line with this observation, high levels of miR-145 at M3 significantly correlated with disease activity worsening based on an increase in ASDAS from M3 to M12 (r=0.595, p=0.007) and higher ASDAS (r=0.535, p=0.018) and VAS (r=0.564, p=0.012) at M12.

Conclusion:

We propose that an early change in miR-145 levels may be a predictor of future outcome of AS patients as it’s early decrease after anti-TNF initiation correlated with further disease activity improvement. These data, similarly to previous studies showing correlation of miR-145 with CRP and pro-inflammatory IL-6 (Cell Biochem Funct. 2015;33(5)), suggest potential use of circulating miRNAs as biomarkers of treatment response in AS.

Acknowledgement: Grant projects 17-33127A and SVV 260373.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/circulating-mir-145-as-a-marker-of-therapeutic-response-to-anti-tnf-therapy-in-patients-with-ankylosing-spondylitis/