Trichostatin A, an Inhibitor of Histone Deacetylase, Inhibits the Viability and Invasiveness of Hypoxic Rheumatoid Arthritis Fibroblast-Like Synoviocytes via PI3K/Akt Signaling

Epi-revolution in rheumatology: the potential of histone deacetylase inhibitors for targeted rheumatoid arthritis intervention

Autoimmune diseases hold significant importance in the realm of medical research, prompting a thorough exploration of potential therapeutic interventions. One crucial aspect of this exploration involves understanding the intricate processes of histone acetylation and deacetylation. Histone acetylation, facilitated by histone acetyl transferases (HATs), is instrumental in rendering DNA transcriptionally active. Conversely, histone deacetylases (HDACs) are responsible for the removal of acetyl groups, influencing gene expression regulation. The upregulation of HDACs, observed in various cancers, has steered attention towards histone deacetylase inhibitors (HDACi) as promising anti-cancer agents. Beyond cancer, HDACi has demonstrated anti-inflammatory properties, prompting interest in their potential therapeutic applications for inflammatory diseases such as rheumatoid arthritis (RA). RA, characterized by the immune system erroneously attacking healthy cells, leads to joint inflammation. Recent studies suggest that HDACi could offer a viable therapeutic strategy for RA, with potential mechanisms including the inhibition of synovial tissue growth and suppression of pro-inflammatory cytokines. Furthermore, HDACi may exert protective effects on bone and cartilage, common targets in RA pathology. In-depth investigations through in vivo and histopathology studies contribute to the ongoing discourse on the therapeutic benefits of HDACis in the context of RA treatment.

Novel HIF-1α Inhibitor AMSP-30m Mitigates the Pathogenic Cellular Behaviors of Hypoxia-Stimulated Fibroblast-Like Synoviocytes and Alleviates Collagen-Induced Arthritis in Rats via Inhibiting Sonic Hedgehog Pathway

Synovial hypoxia-inducible factor 1α (HIF-1α) is a prospective therapeutic target for rheumatoid arthritis (RA). AMSP-30 m, a novel HIF-1α inhibitor, was reported to have notable anti-arthritic effects in rats with adjuvant-induced arthritis. However, its roles in inhibiting the pathogenic behaviors of fibroblast-like synoviocytes (FLS) and the involved mechanisms remain unknown. Here, AMSP-30 m inhibited proliferation and induced apoptosis in hypoxia-induced RA FLS (MH7A cell line), as evidenced by decreased cell viability, reduced Ki67-positive cells, G0/G1 phase arrest, lowered C-myc and Cyclin D1 protein levels, emergence of apoptotic nuclear fragmentation, raised apoptosis rates, and activation of caspase 3. Furthermore, AMSP-30 m prevented hypoxia-induced increases in pro-inflammatory factor production, MMP-2 activity, migration index, migrated/invasive cells, and actin cytoskeletal rearrangement. In vivo, AMSP-30 m alleviated the severity of rat collagen-induced arthritis (CIA). Mechanically, AMSP-30 m reduced HIF-1α expression and blocked sonic hedgehog (Shh) pathway activation in hypoxia-induced MH7A cells and CIA rat synovium, as shown by declines in pathway-related proteins (Shh, Smo, and Gli-1). Particularly, the combination of Shh pathway inhibitor cyclopamine enhanced AMSP-30 m's inhibitory effects on the pathogenic behaviors of hypoxia-stimulated MH7A cells, whereas the combination of Shh pathway activator SAG canceled AMSP-30 m's therapeutic effects in vitro and in CIA rats, implying a close involvement of Shh pathway inhibition in its anti-arthritic effects. We likewise confirmed AMSP-30 m's anti-proliferative role in hypoxia-induced primary CIA FLS. Totally, AMSP-30 m suppressed hypoxia-induced proliferation, inflammation, migration, and invasion of MH7A cells and ameliorated the severity of rat CIA via inhibiting Shh signaling.

IL-1β stimulated human umbilical cord mesenchymal stem cells ameliorate rheumatoid arthritis via inducing apoptosis of fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is characterized by synovial proliferation and lymphocyte accumulation leading to progressive damage of the periarticular bone and the articular cartilage. The hyperplasia of the synovial intima lining mainly consists of fibroblast-like synoviocytes-rheumatoid arthritis (HFLS-RA) which exhibit apoptosis-resistance, hyper-proliferation, and high invasiveness. The therapeutic efficacy of mesenchymal stem cells (MSCs) treatment in RA has been shown to be due to its immuno-regulatory ability. However, the exact factors and mechanisms involved in MSCs treatment in RA remain unclear. In this study, TRAIL receptor-Death receptor 4 (DR4), DR5, and LFA-1 ligand-intercellular adhesion molecule-1 (ICAM-1) were upregulated in IL-1β-stimulated HFLS-RA. We demonstrated that the total cell number of IL-1β-stimulated hUCMSCs adhering to IL-1β-stimulated HFLA-RA increased via LFA-1/ICAM-1 interaction. Direct co-culture of IL-1β-stimulated hUCMSCs with IL-1β-stimulated HFLS-RA increased the apoptosis of HFLS-RA. RA symptoms in the CIA mouse model improved after administration of IL-1β-stimulated hUCMSCs. In conclusion, IL-1β-stimulated hUCMSCs adhering to HFLS-RA occurred via LFA-1/ICAM-1 interaction, apoptosis of HFLS-RA was induced via TRAIL/DR4, DR5 contact, and RA symptoms and inflammation were significantly improved in a CIA mouse model. The results of this study suggest that IL-1β-stimulated hUCMSCs have therapeutic potential in RA treatment.

Epigenetic Regulation in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease. The etiology of RA remains undetermined and the pathogenesis is complex. There remains a paucity of ideal therapeutic drugs and treatment strategies. The epigenetic modifications affect and regulate the function and characteristics of genes through mechanisms, including DNA methylation, histone modification, chromosome remodeling, and RNAi, thereby exerting a significant impact on the living state of the body. Recently, the phenomenon of epigenetic modification in RA has garnered growing research interest. The application of epigenetically modified methods is the frontier field in the research of RA pathogenesis. This review highlights the research on the pathogenesis of RA based on epigenetic modification in the recent five years, thereby suggesting new methods and strategies for the diagnosis and treatment of RA.

Ellagic Acid Alleviates Rheumatoid Arthritis in Rats through Inhibiting MTA1/HDAC1-Mediated Nur77 Deacetylation

Ellagic acid (EA) was reported to play protective roles in rheumatoid arthritis (RA). It was found that the level of metastasis-associated gene 1 (MTA1)/histone deacetylase 1 (HDAC1) protein complex was downregulated by polyphenols in several human disorders. Notably, inhibition of MTA1 or HDAC1 has anti-inflammatory effects on RA. Therefore, our study is aimed at investigating whether EA prevents RA progression through regulating the MTA1/HDAC1 complex. Herein, the human fibroblast-like synoviocyte (FLS) cell line MH7A was treated with TNF-α to induce an inflammation model in vitro and then incubated with different concentrations of EA. Western blot analysis showed that EA reduced MTA1 expression in a dose-dependent manner in MH7A cells. Then, TNF-α-treated MH7A cells were incubated with EA alone or together with MTA1 overexpression plasmid (pcDNA-MTA1), and we found that EA inhibited proliferation, inflammation cytokine levels, and oxidative stress marker protein levels and promoted apoptosis in MH7A cells, while MTA1 overexpression abolished these effects. Moreover, coimmunoprecipitation assay verified the interaction between MTA1 and HDAC1. EA downregulated the MTA1/HDAC1 complex in MH7A cells. MTA1 knockdown inhibited proliferation, inflammation, and oxidative stress and promoted apoptosis in MH7A cells, while HDAC1 overexpression reversed these effects. Moreover, chromatin immunoprecipitation assay indicated that EA inhibited HDAC1-mediated Nur77 deacetylation. Rescue experiments demonstrated that Nur77 knockdown reversed the effects of EA on MH7A cell biological behaviors. Additionally, EA treatment attenuated arthritis index, paw swelling, synovial hyperplasia, and inflammation in collagen-induced arthritis (CIA) rats. In conclusion, EA inhibited proliferation, inflammation, and oxidative stress and promoted apoptosis in MH7A cells and alleviated the severity of RA in CIA rats though downregulating MTA1/HDAC1 complex and promoting HDAC1 deacetylation-mediated Nur77 expression.

m6A RNA Methylation in Systemic Autoimmune Diseases-A New Target for Epigenetic-Based Therapy?

The general background of autoimmune diseases is a combination of genetic, epigenetic and environmental factors, that lead to defective immune reactions. This erroneous immune cell activation results in an excessive production of autoantibodies and prolonged inflammation. During recent years epigenetic mechanisms have been extensively studied as potential culprits of autoreactivity. Alike DNA and proteins, also RNA molecules are subjected to an extensive repertoire of chemical modifications. N6-methyladenosine is the most prevalent form of internal mRNA modification in eukaryotic cells and attracts increasing attention due to its contribution to human health and disease. Even though m6A is confirmed as an essential player in immune response, little is known about its role in autoimmunity. Only few data have been published up to date in the field of RNA methylome. Moreover, only selected autoimmune diseases have been studied in respect of m6A role in their pathogenesis. In this review, I attempt to present all available research data regarding m6A alterations in autoimmune disorders and appraise its role as a potential target for epigenetic-based therapies.

DNA Methylation as a Future Therapeutic and Diagnostic Target in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a long-term autoimmune disease of unknown etiology that leads to progressive joint destruction and ultimately to disability. RA affects as much as 1% of the population worldwide. To date, RA is not a curable disease, and the mechanisms responsible for RA development have not yet been well understood. The development of more effective treatments and improvements in the early diagnosis of RA is direly needed to increase patients' functional capacity and their quality of life. As opposed to genetic mutation, epigenetic changes, such as DNA methylation, are reversible, making them good therapeutic candidates, modulating the immune response or aggressive synovial fibroblasts (FLS-fibroblast-like synoviocytes) activity when it is necessary. It has been suggested that DNA methylation might contribute to RA development, however, with insufficient and conflicting results. Besides, recent studies have shown that circulating cell-free methylated DNA (ccfDNA) in blood offers a very convenient, non-invasive, and repeatable "liquid biopsy", thus providing a reliable template for assessing molecular markers of various diseases, including RA. Thus, epigenetic therapies controlling autoimmunity and systemic inflammation may find wider implications for the diagnosis and management of RA. In this review, we highlight current challenges associated with the treatment of RA and other autoimmune diseases and discuss how targeting DNA methylation may improve diagnostic, prognostic, and therapeutic approaches.

Proximity ligation assay to study protein-protein interactions of proteins on two different cells

Protein-protein interactions (PPI) by homo-, hetero- or oligo-merization in the cellular environment regulate cellular processes. PPI can be inhibited by antibodies, small molecules or peptides, and this inhibition has therapeutic value. A recently developed method, the proximity ligation assay (PLA), provides detection of PPI in the cellular environment. However, most applications using this assay are for proteins expressed in the same cell. We employ PLA for the first time to study PPI of cell surface proteins on two different cells. Inhibition of PPI using a peptide inhibitor is also quantified using this assay; PLA is used to detect PPI of CD2 and CD58 between Jurkat cells (T cells) and human fibroblast-like synoviocyte-rheumatoid arthritis cells that are important in the immune response in the autoimmune disease rheumatoid arthritis. This assay provides direct evidence of inhibition of PPI of two proteins on different cell surfaces.

Regulation of Chemokines and Cytokines by Histone Deacetylases and an Update on Histone Decetylase Inhibitors in Human Diseases

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) counteract with each other to regulate gene expression by altering chromatin structure. Aberrant HDAC activity was reported in many human diseases including wide range of cancers, viral infections, cardiovascular complications, auto-immune diseases and kidney diseases. HDAC inhibitors are small molecules designed to block the malignant activity of HDACs. Chemokines and cytokines control inflammation, immunological and other key biological processes and are shown to be involved in various malignancies. Various HDACs and HDAC inhibitors were reported to regulate chemokines and cytokines. Even though HDAC inhibitors have remarkable anti-tumor activity in hematological cancers, they are not effective in treating many diseases and many patients relapse after treatment. However, the role of HDACs and cytokines in regulating these diseases still remain unclear. Therefore, understanding exact mechanisms and effector functions of HDACs are urgently needed to selectively inhibit them and to establish better a platform to combat various malignancies. In this review, we address regulation of chemokines and cytokines by HDACs and HDAC inhibitors and update on HDAC inhibitors in human diseases.

MicroRNA-126 affects rheumatoid arthritis synovial fibroblast proliferation and apoptosis by targeting PIK3R2 and regulating PI3K-AKT signal pathway

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation and destruction of the joints as well as an increased risk of cardiovascular disease. RA synovial fibroblasts (RASFs) are involved in the progression of RA and release pro-inflammatory cytokines. On the other hand, microRNAs (miRs) may help control the inflammatory response of immune and non-immune cells. Therefore, our study used lentiviral expression vectors to test the effects of miR-126 overexpression on RASF proliferation and apoptosis. Luciferase experiments verified the targeting relationship between miR-126 and PIK3R2 gene. The co-transfection of anti-miR-126 and PIK3R2 siRNA to RASFs were used to identify whether PIK3R2 was directly involved in proliferation and apoptosis of miR-126-induced RASFs. Real-time polymerase chain reaction (PCR) was used to detect miR-126 and PIK3R2 expressions. MTT assay was used to detect cell proliferation. Flow cytometry was used to detect cell apoptosis and cell cycle. Western blotting was used to detect PIK3R2, PI3K, AKT and p-AKT proteins. After Lv-miR-126 infected RASFs, the relative expression of miR-126 was significantly enhanced. MiR-126 promoted RASF proliferation and inhibited apoptosis. Levels of PIK3R2 decreased while total PI3K and p-AKT levels increased in RASFs overexpressing miR-126. Co-transfection of anti-miR-126 and PIK3R2 siRNA also increased PI3K and p-AKT levels as well as RASF proliferation and reduced apoptosis, as compared to anti-miR-126 treatment alone. Finally, luciferase reporter assays showed that miR-126 targeted PIK3R2. Our data indicate that miR-126 overexpression in RASFs inhibits PIK3R2 expression and promotes proliferation while inhibiting apoptosis. This suggests inhibiting miR-126 may yield therapeutic benefits in the treatment of RA.

Epigenetic regulation in B-cell maturation and its dysregulation in autoimmunity

B cells have a critical role in the initiation and acceleration of autoimmune diseases, especially those mediated by autoantibodies. In the peripheral lymphoid system, mature B cells are activated by self or/and foreign antigens and signals from helper T cells for differentiating into either memory B cells or antibody-producing plasma cells. Accumulating evidence has shown that epigenetic regulations modulate somatic hypermutation and class switch DNA recombination during B-cell activation and differentiation. Any abnormalities in these complex regulatory processes may contribute to aberrant antibody production, resulting in autoimmune pathogenesis such as systemic lupus erythematosus. Newly generated knowledge from advanced modern technologies such as next-generation sequencing, single-cell sequencing and DNA methylation sequencing has enabled us to better understand B-cell biology and its role in autoimmune development. Thus this review aims to summarize current research progress in epigenetic modifications contributing to B-cell activation and differentiation, especially under autoimmune conditions such as lupus, rheumatoid arthritis and type 1 diabetes.

Novel biomolecule lycopene-reduced graphene oxide-silver nanoparticle enhances apoptotic potential of trichostatin A in human ovarian cancer cells (SKOV3)

Background

Recently, there has been much interest in the field of nanomedicine to improve prevention, diagnosis, and treatment. Combination therapy seems to be most effective when two different molecules that work by different mechanisms are combined at low dose, thereby decreasing the possibility of drug resistance and occurrence of unbearable side effects. Based on this consideration, the study was designed to investigate the combination effect of reduced graphene oxide-silver nanoparticles (rGO-AgNPs) and trichostatin A (TSA) in human ovarian cancer cells (SKOV3).

Methods

The rGO-AgNPs were synthesized using a biomolecule called lycopene, and the resultant product was characterized by various analytical techniques. The combination effect of rGO-Ag and TSA was investigated in SKOV3 cells using various cellular assays such as cell viability, cytotoxicity, and immunofluorescence analysis.

Results

AgNPs were uniformly distributed on the surface of graphene sheet with an average size between 10 and 50 nm. rGO-Ag and TSA were found to inhibit cell viability in a dose-dependent manner. The combination of rGO-Ag and TSA at low concentration showed a significant effect on cell viability, and increased cytotoxicity by increasing the level of malondialdehyde and decreasing the level of glutathione, and also causing mitochondrial dysfunction. Furthermore, the combination of rGO-Ag and TSA had a more pronounced effect on DNA fragmentation and double-strand breaks, and eventually induced apoptosis.

Conclusion

This study is the first to report that the combination of rGO-Ag and TSA can cause potential cytotoxicity and also induce significantly greater cell death compared to either rGO-Ag alone or TSA alone in SKOV3 cells by various mechanisms including reactive oxygen species generation, mitochondrial dysfunction, and DNA damage. Therefore, this combination chemotherapy could be possibly used in advanced cancers that are not suitable for radiation therapy or surgical treatment and facilitate overcoming tumor resistance and disease progression.

Thioredoxin 1 is associated with the proliferation and apoptosis of rheumatoid arthritis fibroblast-like synoviocytes

We aimed to investigate the possible effects of thioredoxin 1 (Trx1) on the proliferation and apoptosis of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) and elucidate the possible mechanisms involved. We investigated the distribution and expression of Trx1 in synovial tissues from RA and osteoarthritis (OA) patients by immunohistochemistry and real-time polymerase chain reaction (RT-PCR) analyses. RA-FLSs were isolated and cultured under normoxic (21% oxygen) or hypoxic (3% oxygen) concentrations. Transfection of Trx1-siRNAs and a Trx1 overexpression construct was conducted to manipulate the expression of Trx1. Protein expression was detected by Western blot. Doxorubicin (Adriamycin, ADR) was used to induce apoptosis. LY-294002 was used for the inhibition of PI3K-Akt. Cell proliferation and apoptosis were determined by MTS (3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium, inner salt) assay and flow cytometry, respectively. The mRNA and protein expression of Trx1 in RA tissues was higher than that in OA tissues. The expression levels of Trx1 and cell proliferation in RA-FLSs were increased under hypoxia in comparison to those under normoxia. In hypoxia, downregulation of Trx1 significantly suppressed FLS proliferation, and the expression of PI3Kp85, phospho-Akt, and Bcl-2, while notably increased FLS apoptosis and the expression of active Caspase3 and Bax. In normoxia, Trx1 overexpression promoted the FLS proliferation and the expression of PI3Kp85, phospho-Akt, and Bcl-2, but inhibited FLS apoptosis and the expression of active Caspase3 and Bax in FLSs. Such effects were partially repressed by LY-294002 treatment. Trx1 may play an important role in regulating the proliferation and apoptosis of RA-FLSs by modulating PI3K-Akt activation.

Epigenetic alterations in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis is an immune-mediated disease that primarily affects diarthrodial joints. Susceptibility and severity of this disease are influenced by nongenetic factors, such as environmental stress, suggesting an important role of epigenetic changes. In this review, we summarize the epigenetic changes (DNA methylation, histone modification and miRNA expression) in fibroblast-like synoviocytes, which are the joint-lining mesenchymal cells that play an important role in joint inflammation and damage. We also review the effects of these epigenetic changes on rheumatoid arthritis pathogenesis and discuss their therapeutic potential.