Increased long noncoding RNA LINK-A contributes to rheumatoid synovial inflammation and aggression
Jingnan Wang, Chuyu Shen, Ruiru Li, Cuicui Wang, Youjun Xiao, Yu Kuang, Minxi Lao, Siqi Xu, Maohua Shi, Xiaoyan Cai, Liuqin Liang, Hanshi Xu
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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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 3

Effects of lncRNA LINK-A knockdown on proinflammatory cytokines, proliferation, and apoptosis of RA FLSs.

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Effects of lncRNA LINK-A knockdown on proinflammatory cytokines, prolife...
RA FLSs were transfected with LINK-A siRNA (si-LINK-A-2 or si-LINK-A-3) or control siRNA (siC). (A) Effect of LINK-A knockdown on the expression of IL-1β, IL-6, and IL-8. Cytokine expression was detected using RT-qPCR assay. Ct values were normalized to β-actin values. Data are presented as the mean ± SD. (B) Effect of LINK-A knockdown on the secretion of IL-1β, IL-6, and IL-8. Cytokine levels were measured using ELISA. Data are presented as the mean ± SD. (C and D) Effect of LINK-A knockdown on proliferation of RA FLSs. CCK-8 (C) or EdU incorporation assay (D) was used to evaluate the growth or proliferation. Representative images show proliferation of RA FLSs labeled with EdU (red) and nuclei stained with Hoechst 33342 (blue) (original magnification, ×100). Graphs indicate the mean ± SD of more than 5 independent experiments involving different RA patients. (E) Effect of LINK-A knockdown on apoptosis of RA FLSs. The cellular apoptosis rate was evaluated by annexin V and propidium iodide (PI) staining and measured by flow cytometry. Representative flow plots are shown. The apoptosis graph represents the mean ± SD percentage of 3 independent experiments involving different RA patients. *P < 0.05 versus siC, **P < 0.01, and ***P < 0.001 versus siC; #P < 0.05, ##P < 0.01 versus TNF-α + siC, by 1-way ANOVA.