Circular RNAs hsa-circ0000175 and hsa-circ0044235 in plasma are novel biomarkers for new-onset rheumatoid arthritis

Dysregulated circular RNAs in rheumatoid arthritis: Cellular roles and clinical prospects

Rheumatoid arthritis (RA) is still a healthcare challenge, although current therapeutic strategies have substantially improved its clinical outcomes. The development of novel biomarkers and treatments can increase the likelihood of identification and disease remission in RA patients, especially for patients with seronegative RA and difficult-to-treat RA (D2T RA). Circular RNAs (circRNAs), a novel non-coding RNA species, have been reported to play crucial roles in various biological process of RA. The mechanistic functions of the dysregulated circRNAs in RA are primarily associated with miRNA sponging and regulating transcription. CircRNAs acting as miRNA sponges are further summarized by cell types, including fibroblast-like synoviocytes (FLSs), lymphocytes, macrophages, chondrocytes, and mesenchymal stem cells (MSCs)-/plasma-secreted exosomes. Besides, a description of dysregulated circRNAs in blood, synovial tissue and cartilage tissue suggests their diagnostic potential for RA. In addition, some directions for future research are provided to open the possibility that dysregulated cell- and tissue- specific circRNAs constituting a fresh reservoir of therapeutic targets, and biomarkers for diagnosis, predicting response to therapy, drug selection or patient stratification for RA.

Circular RNA hsa_circ_0000175 Serves as a Potential Biomarker for Rheumatoid Arthritis via miR-31-5p/GSDME Axis

Rheumatoid arthritis (RA) is a common inflammatory autoimmune disease characterized by synovial inflammation and joint damage. Previous studies have shown that pyroptosis plays an important role in the pathogenesis of RA. In this study, the effects of circular RNA hsa_circ0000175 on pyroptosis and inflammation of RA were evaluated. Serum levels of circ_0000175 and miR-31-5p were determined by RT-qPCR, and the correlation between them was evaluated by Spearman correlation analysis. Fibroblast-like synoviocytes (FLSs) were extracted and prepared for in vitro study. The subcellular localization of circ_0000175 was detected by FISH assay. Pyroptosis and inflammatory cytokines interleukin (IL)-1β, IL-18 and IL-6 were measured by flow cytometry and ELISA, respectively. RNA pull-down and luciferase reporter assays verified the interaction between circ_0000175 and miR-31-5p. Western blot was used to detect the differential expression of pyroptosis-related factors (GSDME-N, GSDMD-N, cleaved caspase-1 and cleaved caspase-3). Circ_0000175 level was increased but miR-31-5p expression was decreased in PBMCs of RA patients and LPS/ATP-treated FLSs, companied with negative correlation. Moreover, miR-31-5p was a target of circ_0000175 in RA-FLSs. Silencing of circ_0000175 or overexpression of miR-31-5p significantly alleviated LPS/ATP-induced pyroptosis in FLSs through both caspase-1/GSDMD and caspase-3/GSDME pathways. Additionally, GSDME was identified as the target of miR-31-5p. The inhibitory effects of circ_0000175 depletion on pyroptosis and inflammation in RA-FLSs treated with LPS/ATP were strengthened by GSDME knockdown. Circ_0000175 can induce pyroptosis and trigger inflammatory response during the occurrence of RA through the miR-31-5p/GSDME axis, which provides a novel therapeutic target for RA treatment.

Plasma Circular-RNA 0005567 as a Potential Marker of Disease Activity in Rheumatoid Arthritis

Circular RNAs (circRNAs) are noncoding molecules and are generated through back splicing, during which the 5' and 3' ends are covalently joined. Consequently, the lack of free ends makes them stable and resistant to exonucleases, and they become more suitable biomarkers than other noncoding RNAs. The aim of the study was to find an association between selected circRNAs and disease activity in patients with RA. A total of 71 subjects, 45 patients with RA and 26 healthy controls (HCs), were enrolled. In the RA group, 24 patients had high disease activity (DAS-28-ESR > 5.1) and 21 individuals were in remission (DAS-28-ESR ≤ 2.6). The cell line SW982 was used to evaluate the biological function of circ_0005567. The concentration of circ_0005567 in RA patients was elevated compared to HCs (median, 177.5 [lower-upper quartile, 83.13-234.6] vs. 97.83 [42.03-145.4], p = 0.017). Patients with high disease activity had a higher concentration of circ_0005567 than the control group (185.4 [112.72-249.25] vs. 97.83 [42.03-145.4], p = 0.015). In the cell line model, we found an association between circ_0005567 and miR-194-5p concentration and increased expression of mRNAs that may be related to cell proliferation. The plasma concentration of circ_0005567 may be a new potential biomarker associated with disease activity in patients with RA.

Dysregulation of circRNAs in rheumatoid arthritis, with special emphasis on circRNAs secreted by exosomes and the crosstalk between circRNAs and RNA methylations

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease caused by a variety of unknown factors. It mainly occurs in the small joints of hands and feet, leading to cartilage destruction and bone erosion. Various pathologic mechanisms such as exosomes and RNA methylations are involved in the pathogenesis of RA.

METHODS

This work searches PubMed, Web of Science (SCIE) and Science Direct Online (SDOL) databases, it role of abnormally expressed circulating RNAs (circRNAs) in the pathogenesis of RA was summarized. And the relationship between circRNAs and exosomes and methylations.

RESULTS

Both the abnormal expression of circRNAs and the sponge effect of circRNAs on microRNAs (miRNAs) affect the pathogenesis of RA by regulating target genes. CircRNAs affect the proliferation, migration and inflammatory reaction of RA-fibroblast-like synovial cells (FLSs), circRNAs in peripheral blood mononuclear cells (PBMCs) and macrophages also participate in the pathological mechanism of RA (Fig. 1). CircRNAs in exosomes are closely related to the pathogenesis of RA. In addition, exosomal circRNAs and the relationship between circRNAs and RNA methylations are closely related to the pathogenesis of RA.

CONCLUSION

CircRNAs play an important role in the pathogenesis of RA and have the potential to be a new target for the diagnosis and treatment of RA. However, the development of mature circRNAs for clinical application is not a small challenge.

Implications and theragnostic potentials of circular RNAs in rheumatic diseases

Circular RNAs (circRNAs), a class of non-coding RNAs (ncRNAs), are highly stable and ubiquitous molecules that exhibit tissue-specific expression. Accumulating evidence has shown that aberrant expression of circRNAs can play a role in the pathogenesis of several diseases. Rheumatic diseases are a varied group of autoimmune and inflammatory disorders affecting mainly the musculoskeletal system. Notably, circRNAs, which are essential immune system gene modulators, are strongly linked to the occurrence and progression of autoimmune disorders. Here, we present and discuss the current findings concerning the roles, implications and theragnostic potentials of circRNAs in common rheumatic diseases, including ankylosing spondylitis (AS), osteoarthritis (OA), osteoporosis (OP), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Crohn's disease (CD), and gout. This review aims to provide new insights to support the development of novel diagnostic and therapeutic strategies for these disabling diseases.

Hsa_circ_0008301 as a potential biomarker of disease activity for primary Sjogren's syndrome: Increased expression in peripheral blood of patients with primary Sjogren's syndrome

OBJECTIVES

To explore the expression level, association with disease activity and clinical significance of hsa_circ_0008301 in the peripheral blood of patients with primary Sjögren's syndrome (pSS).

METHODS

We selected 70 pSS patients hospitalized under the Rheumatology service line at the General Hospital of Ningxia Medical University from September 2018 to June 2021 as the disease group, in which general data and clinical indicators were collected. Fifty-three patients with healthy physical examinations for the same period were selected as the healthy control group, and 32 patients with non-pSS rheumatic diseases were selected as the disease control group. We collected peripheral blood samples and used fluorescence quantitative PCR to detect the expression level of hsa_circ_0008301. In addition, we analyzed the association of the expression level of hsa_circ_0008301 with the clinical characteristics and disease activity of pSS patients. A receiver operating characteristic curve was used to evaluate the diagnosis and the disease activity value of hsa_circ_0008301 in patients with pSS. Meanwhile, we analyzed the differential expression of hsa_circ_0008301 in 24 pSS patients selected from the disease group before and after treatment.

RESULTS

The relative expression of hsa_circ_0008301 in the peripheral blood of pSS patients was significantly higher than that in the control groups including healthy control group and disease control group. The expression level of hsa_circ_0008301 was high in pSS patients with a course of disease ≥ 10 years, fatigue symptoms, platelets < 100*10^9/L, erythrocyte sedimentation rate ≥ 50 mm/h, immunoglobulin IgG > 16 g/L, complement C3 < 0.9 g/L, ESSDAI score ≥ 5 and positively correlated with the above groups. Furthermore, ROC analysis showed that hsa_circ_0008301 was statistically significant between pSS patients and healthy controls. We selected patients from the disease group before and after treatment and showed that the expression level of hsa_circ_0008301 decreased significantly after treatment, compared with before. The area under the curve (AUC) was 0.825 (95% CI: 0.754 ∼ 0.897; P < 0.0001). The AUC of hsa_circ_0008301 in pSS patients and the disease control group was 0.673 (95% CI: 0.563 ∼ 0.782; P = 0.005), the sensitivity was 40.00%, the specificity was 93.70%, the optimal truncation value was > 0.0420, and the maximum Youden index was 0.337. In addition, ROC analysis revealed that hsa_circ_0008301 was statistically significant between disease-active patients and stable patients. The AUC value was 0.681 (95% CI: 0.553 ∼ 0.809; P = 0.010), the sensitivity was 65.90%, the specificity was 72.40%, the optimal truncation value was > 0.0285, and the maximum Youden index was 0.383. ROC analysis indicated that hsa_circ_0008301 has some value in the diagnosis and disease activity of patients with pSS. Comparison of 24 pSS patients selected from the disease group before and after treatment showed that the expression level of hsa_circ_0008301 decreased significantly after treatment compared with before treatment (Z =  - 4.257, P < 0.0001). ROC analysis indicated that hsa_circ_0008301 has some value in the diagnosis and disease activity of patients with pSS.

CONCLUSIONS

Hsa_circ_0008301 is expressed in higher levels in the peripheral blood of patients with pSS, which is related to the disease activity. It may be involved in the occurrence and development of pSS and may have a potential biomarker for the disease.

MiR-144-3p induced by SP1 promotes IL-1β-induced pyroptosis in chondrocytes via PTEN/PINK1/Parkin axis

Rheumatoid arthritis (RA) often leads to functional disabilities and deformities. MiRNA plays a vital role in cell pyroptosis. Nevertheless, the function and underlying mechanism of miR-144-3p in pyroptosis during the progression of RA remains unclear. In this study, N1511 cells were stimulated with IL-1β to construct a RA model. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was performed to assess the cell viability. Cell pyroptosis was detected by flow cytometry. The levels of inflammatory cytokines (TNF-α, IL-6, and IL-18) were assessed by enzyme-linked immunosorbent assay (ELISA). The relationship among specific protein 1 (SP1), microRNA-144-3p (miR-144-3p), and phosphatase and tensin homolog (PTEN) was explored by dual-luciferase reporter assay, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP), respectively. The level of miR-144-3p in N1511 cells was upregulated by IL-1β. MiR-144-3p knockdown inhibited IL-1β-induced pyroptosis in N1511 cells, and the expressions of NOD-like receptor family pyrin domain containing 3 (NLRP3), Cleaved caspase-1, Gasdermin D (GSDMD), and Cleaved caspase-3 in IL-1β-stimulated N1511 cells were increased. The levels of inflammatory cytokines in N1511 cells were increased by IL-1β, which were restored by miR-144-3p knockdown. MiR-144-3p knockdown abolished IL-1β-induced inactivation of putative kinase 1 (PINK1)/Parkin RBR E3 ubiquitin-protein (Parkin) signalling. Moreover, transcription factor SP1 could upregulate miR-144-3p expression and miR-144-3p negatively regulated PTEN expression. In summary, MiR-144-3p induced by SP1 could promote IL-1β-induced chondrocyte pyroptosis via inhibiting PTEN expression and suppressing the activation of PINK1/Parkin signalling, which provided a new strategy against RA.