Increased long noncoding RNA LINK-A contributes to rheumatoid synovial inflammation and aggression
Jingnan Wang, … , Liuqin Liang, Hanshi Xu
Jingnan Wang, … , Liuqin Liang, Hanshi Xu
Published December 8, 2021
Citation Information: JCI Insight. 2021;6(23):e146757. https://doi.org/10.1172/jci.insight.146757.
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Research Article Immunology

Increased long noncoding RNA LINK-A contributes to rheumatoid synovial inflammation and aggression

Abstract

Fibroblast-like synoviocytes (FLSs) play a key role in controlling synovial inflammation and joint destruction in rheumatoid arthritis (RA). The contribution of long noncoding RNAs (lncRNAs) to RA is largely unknown. Here, we show that the lncRNA LINK-A, located mainly in cytoplasm, has higher-than-normal expression in synovial tissues and FLSs from patients with RA. Synovial LINK-A expression was positively correlated with the severity of synovitis in patients with RA. LINK-A knockdown decreased migration, invasion, and expression and secretion of matrix metalloproteinases and proinflammatory cytokines in RA FLSs. Mechanistically, LINK-A controlled RA FLS inflammation and invasion through regulation of tyrosine protein kinase 6–mediated and leucine-rich repeat kinase 2–mediated HIF-1α. On the other hand, we also demonstrate that LINK-A could bind with microRNA 1262 as a sponge to control RA FLS aggression but not inflammation. Our findings suggest that increased level of LINK-A may contribute to FLS-mediated rheumatoid synovial inflammation and aggression. LINK-A might be a potential therapeutic target for RA.

Authors

Jingnan Wang, Chuyu Shen, Ruiru Li, Cuicui Wang, Youjun Xiao, Yu Kuang, Minxi Lao, Siqi Xu, Maohua Shi, Xiaoyan Cai, Liuqin Liang, Hanshi Xu

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Figure 1

Increased levels of lncRNA LINK-A in FLSs and synovial tissues from patients with RA.

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Increased levels of lncRNA LINK-A in FLSs and synovial tissues from pati...
(A) Total RNA harvested from RA FLSs (n = 5) and HC FLSs (n = 5) was screened by microarray analysis. Microarray heatmap of distinguishable expression profiles of lncRNAs. (B) Volcano plot shows differentially expressed lncRNAs between RA FLSs and HC FLSs. P < 0.05, by Student’s t test. (C) RACE assay of LINK-A. The image shows amplification products of 5′ and 3′ ends of LINK-A. M, marker. (D) Verification of LINK-A by RT-qPCR in HC FLSs and RA FLSs. Ct values were normalized to GAPDH. Data are presented as the mean ± SD. (E) Expression of LINK-A in RA FLSs treated with IL-1β (10 ng/mL), TNF-α (10 ng/mL), IL-6 (10 ng/mL), IL-17 (10 ng/mL), LPS (10 ng/mL), methotrexate (MTX, 10 μg), and dexamethasone (DXM, 1 μg) for 24 hours. (F) Effect of MTX (10 μg) on TNF-α–induced LINK-A expression. (G and H) Cellular localization of LINK-A was measured by RNA FISH assay. Shown are representative images of LINK-A (red) and nuclei (blue) from 5 different RA patients and HCs. Graph (H) shows the quantification of staining intensity for 5 different RA patients and HCs. Original magnification, ×400. (I and J) LINK-A expression, evaluated by ISH staining, in synovial tissues from HCs and RA patients. Shown are representative images (I) and quantification of the percentage of LINK-A–positive cells (J) from 5 different RA patients and HCs. A scrambled probe was used as a negative control. White arrows indicate LINK-A–positive (red) cells. Original magnification, ×630. *P < 0.05, **P < 0.01, ***P < 0.001 versus HC FLSs or control (CON); ###P < 0.001 versus TNF-α, by Student’s 2-tailed t test or 1-way ANOVA (for E and F).