Differential expression of lncRNA in the serum of ankylosing spondylitis patients

Objective To investigate the differential expression of lncRNA in the serum of ankylosing spondylitis (AS) patients, with the goal of findingnew potential biomarkers for the diagnosis and targeted treatment of AS. Methods A total of 19 AS patients and 19 age-matched healthy controls treated at Nanjing Drum Tower Hospitalfrom January 2017 to September 2017 were recruited. Average age were 38.74±7.42 (range, 25-51) and 37.00±6.86 (range, 26-50). High-throughput lncRNA sequencing technology was used to detect differently expressed lncRNAs in the serum of 3 AS patients and 3 healthy controls. Target lncRNAs for further validation were selected according to the P values and fold-changes. In the rest of the serum samples (16 AS patients and 16 healthy controls), Trizol-based technique was used to extract total RNA, and after reverse transcription to obtain cDNA, RT-qPCR was preformed to confirm the sequencing results. Results Using high-throughput lncRNA sequencing, a total of 41 up-regulated and 2 down-regulated lncRNAs were detected in the serum of AS patients. After sorted by the P values, 4 lncRNAswith a fold-change larger than 2 were chosen as the target genes for RT-qPCR (ENST00000365494.1, P=2.6×10-277, fold-change: 2.05; ENST00000364938.1, P=2.49×10-77, fold-change: 2.19; ENST 00000363046.1, P=2.67×10-29, fold-change: 2.51; ENST00000384756.1, P=6.17×10-21, fold-change: 2.28). RT-qPCR results showed the relative expression of lncRNA ENST00000365494.1 was 1.80±0.22 (P=0.304), lncRNA ENST00000364938.1was 0.78±0.07 (P=0.417), lncRNA ENST00000363046.1was 1.28±0.24 (P=0.793), lncRNA ENST00000384756.1 was 1.52±0.25 (P=0.611)and tendency of up-regulation was found in 3 of them, which was consistent with the sequencing results. However, the difference did not achieve statistical significance. Conclusion Sequencing result could not be confirmed by RT-qPCR with a larger sample size, which implied the differential expression of lncRNA might not exist in the peripheral blood of AS patients, and further studies regarding lncRNA in AS could focus more on its differential expression and function in the focal tissue. Key words: Spondylitis, ankylosing; Regulatory sequences, ribonucleic acid; Gene expression