Rheumatoid arthritis and non-coding RNAs; how to trigger inflammation

Identification of novel biomarker hsa_circ_0003914 for rheumatoid arthritis from plasma exosomes

Rheumatoid arthritis (RA) is a complex autoimmune disease featuring invasive and infiltrative fibroblast-like synoviocytes (FLS) that lead to joint damage. While current RA pathological mechanisms remain incompletely defined, exosomes have been implicated as having the potential to drive disease progression due to their ability to deliver different types of biomolecules to tissues effected by RA. One potentially disease exacerbating molecule type found in exosomes are Circular RNAs (circRNAs), which are highly stable and have been previously implicated in RA pathogenesis. Here, we examine hsa_circ_0003914, a circRNA found in exosomes located in blood plasma, for a role in RA. Plasma exosomes were isolated and injected into collagen-induced arthritis (CIA) mice, followed by functional experiments to analyze the influence of exosomes on FLS formation. Sequencing revealed the presence of hsa_circ_0003914 in exosomes, so we examined its association with clinical markers in RA. Finally, the role for hsa_circ_0003914 in RA was directly confirmed through in vivo and in vitro experiments. We found that plasma exosomes isolated from RA patients could aggravate the disease of CIA mice, compared to exosomes isolated from healthy control patients. Hsa_circ_0003914 was highly enriched in the exosomes of RA patients. Mechanistically, Hsa_circ_0003914 promoted abnormal cell proliferation, migration, invasion and stimulated the secretion of inflammatory cytokines in FLSs through targeting NF-κB/p65 signaling pathway. Interestingly, knockdown of hsa_circ_0003914 rescued disease phenotypes in CIA mice. Taken together, these data implicate hsa_circ_0003914 as a potential therapeutic target for the prevention and management of RA.

Role of LncRNA MIAT in Diabetic Complications

Long non-coding RNA (LncRNA) refers to a large class of RNAs with over 200 nucleotides that do not have the function of encoding proteins. In recent years, more and more literature has revealed that lncRNA is involved in manipulating genes related to human health and disease, playing outstanding biological functions, which has attracted widespread attention from researchers. The newly discovered long-stranded non-coding RNA myocardial infarction-related transcript (LncRNA MIAT) is abnormally expressed in a variety of diseases, especially in diabetic complications, and has been proven to have a wide range of effects. This review article aimed to summarize the importance of LncRNA MIAT in diabetic complications, such as diabetic cardiomyopathy, diabetic nephropathy, and diabetic retinopathy, and highlight the latest findings on the pathway and mechanism of its participation in regulating diabetic complications, which may aid in finding new intervention targets for the treatment of diabetic complications. LncRNA MIAT competitively binds microRNAs to regulate gene expression as competitive endogenous RNAs. Thus, this review article has reviewed the biological function and pathogenesis of LncRNA MIAT in diabetic complications and described its role in diabetic complications. This paper will help in finding new therapeutic targets and intervention strategies for diabetes complications.

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.

Role of CD93 in Health and Disease

CD93 (also known as complement protein 1 q subcomponent receptor C1qR1 or C1qRp), is a transmembrane glycoprotein encoded by a gene located on 20p11.21 and composed of 652 amino acids. CD93 can be present in two forms: soluble (sCD93) and membrane-bound (CD93). CD93 is mainly expressed on endothelial cells, where it plays a key role in promoting angiogenesis both in physiology and disease, such as age-related macular degeneration and tumor angiogenesis. In fact, CD93 is highly expressed in tumor-associated vessels and its presence correlates with a poor prognosis, poor immunotherapy response, immune cell infiltration and high tumor, node and metastasis (TNM) stage in many cancer types. CD93 is also expressed in hematopoietic stem cells, cytotrophoblast cells, platelets and many immune cells, i.e., monocytes, neutrophils, B cells and natural killer (NK) cells. Accordingly, CD93 is involved in modulating important inflammatory-associated diseases including systemic sclerosis and neuroinflammation. Finally, CD93 plays a role in cardiovascular disease development and progression. In this article, we reviewed the current literature regarding the role of CD93 in modulating angiogenesis, inflammation and tumor growth in order to understand where this glycoprotein could be a potential therapeutic target and could modify the outcome of the abovementioned pathologies.

Modulation of NRF2/KEAP1 Signaling in Preeclampsia

Placentation is a key and tightly regulated process that ensures the normal development of the placenta and fetal growth. Preeclampsia (PE) is a hypertensive pregnancy-related disorder involving about 5-8% of all pregnancies and clinically characterized by de novo maternal hypertension and proteinuria. In addition, PE pregnancies are also characterized by increased oxidative stress and inflammation. The NRF2/KEAP1 signaling pathway plays an important role in protecting cells against oxidative damage due to increased reactive oxygen species (ROS) levels. ROS activate NRF2, allowing its binding to the antioxidant response element (ARE) region present in the promoter of several antioxidant genes such as heme oxygenase, catalase, glutathione peroxidase and superoxide dismutase that neutralize ROS, protecting cells against oxidative stress damages. In this review, we analyze the current literature regarding the role of the NRF2/KEAP1 pathway in preeclamptic pregnancies, discussing the main cellular modulators of this pathway. Moreover, we also discuss the main natural and synthetic compounds that can regulate this pathway in in vivo and in vitro models.