Screening and analysis for autophagy-related lncRNA in fibroblast-like synoviocytes from patients with rheumatoid arthritis.

Abstract

Long non-coding RNA (lncRNA) has become a key epigenetic regulator that regulates gene expression and affects a variety of biological processes. LncRNA plays an important role in the occurrence and development of rheumatoid arthritis (RA). The study on lncRNA in peripheral blood cells of RA patients has been reported. However, there is no study on autophagy regulation by lncRNA in RA patients. This study aims to provide a new direction for the diagnosis and treatment of RA via screening the changes of lncRNAs in RA fibroblast-like synoviocytes (RA-FLSs) before and after autophagy and finding the key lncRNAs targeting RA-FLSs autophagy. Synovial tissues of 6 RA patients after knee and hip joint surgery were obtained, and RA-FLSs were cultured to the 5th generation for further experiments (tissue culture method). After treatment with mTOR inhibitor PP242, the expression of LC3-II was detected by Western blotting. Total RNAs of 3 cases of RA-FLSs before and after treatment with mTOR inhibitor PP242 were extracted by TRIzol and screened by Agilent Human ceRNA Microarray 2019 (4×180 K, design ID: 086188) chip. The lncRNAs with significantly changed expression levels were selected (difference multiple≥2.0, P<0.05). Bioinformatics technology was used to analyze the gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of the differentially expressed lncRNAs, and to explore the possible role of differentially expressed lncRNAs in the pathogenesis of RA. Subsequently, ENST00000584721.1 and ENST00000615939.1 were identified in all the 6 samples of RA-FLSs using real-time RT-PCR, which were selected by previous chip screen combined with GO enrichment analysis and KEGG analysis. RA-FLSs were successfully isolated and cultured from the synovial tissues of the patient's knee or hip joint. After 6 RA-FLSs were treated with PP242, the expression level of autophagy marker protein LC3-II was increased (P<0.05). PP242 induced autophagy in RA-FLSs. LncRNA sequencing analysis showed that a total of 591 lncRNAs were significantly changed, of which 428 were up-regulated and 163 were down-regulated.Go analysis showed that these differentially expressed lncRNAs were associated with negative regulation of Th17 function, T cell related cytokines production, and TGF-β receptor signaling pathway, as well as IL-6 receptor complex formation and type I TGF-β receptor binding. KEGG analysis showed that autophagy pathway, TGF-β, TNF-α, IL-17 signaling pathway, and Th17, Th1, Th2, osteoclast differentiation pathway were the most abundant signal pathways of differentially expressed lncRNAs during autophagy. The expression of ENST00000584721.1 was up-regulated (P<0.05) and the expression ofENST00000615939.1 was down-regulated (P<0.05) in RA-FLSs undergoing autophagy, by using real-time RT-PCR validation which was in consistent with the microarray results. The reliability of microarray screening differential genes was confirmed. GO analysis showed that ENST00000584721.1 and ENST00000615939.1 were related to ribosome transport and autophagy assembly, respectively. KEGG analysis showed that ENST00000584721.1 was related to mitogen-activated protein kinase (MAPK) signaling pathway, and ENST00000615939.1 was related to FoxO signaling pathway. Differentially expressed lncRNAs in RA-FLSs have been identified with microarray analysis. In RA, differential expression of lncRNAs is involved in the autophagy of RA-FLSs. The underlying mechanisms based on bioinformatics analysis include regulating the secretion of cytokines, such as IL-6, TGF-β, TNF-α and IL-17, participating in the immune cell differentiation, such as Th17, Th1, Th2 cells and osteoclasts, as well as regulating the autophagy pathway, MAPK, FoxO, and other signaling pathways. It has been verified that the expression of ENST0000584721.1 is up-regulated and ENST0000615939.1 is down-regulated after autophagy of RA FLSs, which provides a good experimental basis for further study on the mechanism of lncRNA in RA-FLSs autophagy.