Signaling Pathway In Rheumatoid Arthritis Research Articles

In Rheumatoid Arthritis, A Review of ncRNAs Related to NF-κB Signaling Pathways.

Rheumatoid arthritis (RA) is an autoimmune disease with no known cure that results in joint deformities and dysfunction, significantly impacting the quality of life of patients. The abnormal NF-ＫB signaling pathway in RA has emerged as a crucial research area for the development of RA therapies, with non-coding RNAs (ncRNAs) serving as a potentially meaningful avenue to regulate it. Thus, understanding the role of ncRNAs in RA and the identification of new therapeutic targets have become pressing issues in the field. In this review, we aim to summarize recent studies on ncRNAs that regulate the NF-ＫB signaling pathway in RA, including miRNAs, lncRNAs, and circRNAs, as well as the mechanisms by which drugs modulate NF-Ｋ B activity. By highlighting these recent advances, we hope to promote further research into targeted RA therapy and provide novel directions and ideas for researchers in the field.

Blockade of the interleukin-6 signaling pathway in rheumatoid arthritis: Effects on obesity, adipocytokines and glucose metabolism

Interleukin (IL) 6 is one of the key cytokines whose role in the inflammation development in rheumatoid arthritis (RA), is well proven. The pleiotropic effects of the cytokine and biologic agents that inhibit its action have been studied much worse. The review provides information on the effects of IL-6 and blocking its signaling pathway on adipose tissue, glucose metabolism and adipocytokine levels in RA. It has been shown that prolonged blockade of IL-6 receptors does not lead to the adipose tissue accumulation and improves glycemic control, although it is not clear whether such effect is associated only with the anti-inflammatory properties of tocilizumab and sarilumab. Moreover, the mechanism of this beneficial effect is not fully understood, since the data on increased sensitivity of peripheral tissues to insulin during tocilizumab treatment are ambiguous. Perhaps changes in the relationship of adipocytokines or hormones play a certain role.

Role and Therapeutic Potential for Targeting Fibroblast Growth Factor 10/FGFR1 in Relapsed Rheumatoid Arthritis.

Fibroblast-like synoviocytes (FLSs) contribute to inflammation and joint damage in rheumatoid arthritis (RA). However, the regulatory mechanisms of FLSs in relapse and remission of RA remain unknown. Identifying FLS heterogeneity and their underlying pathogenic roles may lead to discovering novel disease-modifying antirheumatic drugs. Combining single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics, we sequenced six matched synovial tissue samples from three patients with relapse RA and three patients in remission. We analyzed the differences in the transcriptomes of the FLS subsets between the relapse and remitted phases. We validated several key signaling pathways using quantitative real-time PCR(qPCR)and multiplex immunohistochemistry (mIHC). We further targeted the critical signals in vitro and in vivo using the collagen-induced arthritis (CIA) model in rats. Lining and sublining FLS subsets were identified using scRNA-seq. Differential analyses indicated that the fibroblast growth factor (FGF) pathway was highly activated in the lining FLSs from patients with relapse RA for which mIHC confirmed the increased expression of FGF10. Although the type I interferon pathway was also activated in the lining FLSs, in vitro stimulation experiment suggested that it was independent of the FGF10 pathway. FGF10 knockdown by small interfering RNA in FLSs significantly reduced the expression of receptor activator of NF-κB ligand. Moreover, recombinant FGF10 protein enhanced bone erosion in the primary human-derived pannus cell culture, whereas the FGF receptor (FGFR) 1 inhibitor attenuated this process. Finally, administering an FGFR1 inhibitor displayed a therapeutic effect in a CIA rat model. The FGF pathway is a critical signaling pathway in relapse RA. Targeted tissue-specific inhibition of FGF10/FGFR1 may provide new opportunities to treat patients with relapse RA.

Targeting transcription factors for therapeutic benefit in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a destructive inflammatory autoimmune disease that causes pain and disability. Many of the currently available drugs for treating RA patients are aimed at halting the progression of the disease and alleviating inflammation. Further, some of these treatment options have drawbacks, including disease recurrence and adverse effects due to long-term use. These inefficiencies have created a need for a different approach to treating RA. Recently, the focus has shifted to direct targeting of transcription factors (TFs), as they play a vital role in the pathogenesis of RA, activating key cytokines, chemokines, adhesion molecules, and enzymes. In light of this, synthetic drugs and natural compounds are being explored to target key TFs or their signaling pathways in RA. This review discusses the role of four key TFs in inflammation, namely NF-κB, STATs, AP-1 and IRFs, and their potential for being targeted to treat RA.

Exploring the molecular mechanism of Sishen Decoction in the treatment of rheumatoid arthritis.

BackgroundTo explore the potential targets and mechanism of action of Sishen Decoction in the treatment of rheumatoid arthritis (RA) using a network pharmacology approach.MethodsFirstly, we analyzed the differentially expressed genes in the Gene Expression Omnibus (GEO) database and constructed a protein-protein interaction (PPI) network using potential core target proteins determined by the STRING platform and Cytoscape software. We also performed gene ontology functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis, and gene set enrichment analysis (GSEA) on the potential targets, and then used the disease target database to download targets related to RA pathogenesis. The relevant targets were intersected with the action targets of Sishen Decoction to obtain the potential targets considered for the treatment of RA with Sishen Decoction.ResultsThe GSE55235 and GSE77298 datasets were downloaded from the GEO database for analysis, and 73 genes with abnormally high expression in RA and 26 genes with abnormally low expression in RA were obtained by taking the intersection of highly expressed genes and low expression genes in RA. The results of KEGG and Metascape showed that the differential genes were enriched in inflammation-related signaling pathways such as leukocyte migration, myeloid leukocyte-mediated immunity, and lymphocyte activation, as well as bone activation and bone development, which are closely related to RA. In the exploration of the drug targets of Sishen Decoction for the treatment of RA, it was found that Sishen Decoction may regulate the interleukin (IL)-17) signaling pathway, tumour necrosis factor (TNF) signaling pathway, and chemokine signaling pathway in RA by targeting MMP9 and CXCR4.ConclusionsThis study explored the potential targets and signaling pathways of Sishen Decoction in the treatment of RA, which may help to illustrate the mechanisms involved in the action of Sishen Decoction and better understand its anti-RA role in the inhibition of angiogenesis, synovial proliferation, and bone destruction.

Indigenous Nigeria medicinal herbal remedies: A potential source for therapeutic against rheumatoid arthritis.

Rheumatoid arthritis (RA) is a debilitating disease associated with locomotion impairment, and conventional therapeutic drugs are not optimal for managing RA. There is an avalanche of medications used for the management of RA. Still, studies have shown that they are associated with severe side effects, including hepatotoxicity, retinopathy, and cardiotoxicity disorders of the central nervous system (CNS), skin, blood, and infections. Complementary and alternative medicine (CAM) is currently gaining attention as a novel panacea for managing debilitating diseases, such as RA. Nigerian folk herbal remedies are replete with a plethora of curative medicine, albeit unvalidated scientifically but with seemingly miraculous provenance. Studies of the identification of bioactive compounds present in these botanicals using advanced spectral analytical techniques have enhanced our understanding of the role of Nigerian herbal remedies in the treatment and management of RA. Interestingly, experimental studies abound that the bioactive compounds present in the extracts of plant botanicals protected animals from the development of RA in different experimental models and reduced the toxicity associated with conventional therapeutics. Validated mechanisms of RA amelioration in human and animal models include suppression of the expression of NF-κB, IL-1β, TNF-α, IL-6, IL-8, IL-17, IL-23, chemokines, TGF-β, RANKL, RANK, iNOS, arginase, COX-2, VEGFA, VEGFR, NFATC1, and TRAP in the synoviocytes. Decreased ROS, NO, MDA, carbonyl groups, and PGE2 in the synovial fluid increased the expression of PPARα/γ; antioxidant and anti-inflammatory molecules also improve RA etiology. In this mini-review, we discuss the global burden of RA, the novel role of plant-based botanicals as potential therapeutics against signaling pathways in RA. Also addressed is the possible repurposing/reprofiling of plant botanicals to increase their therapeutic index among RA patients that patronize traditional healers in Nigeria with a global projection.

A narrative review of the role of the Notch signaling pathway in rheumatoid arthritis.

Background and ObjectiveRheumatoid arthritis (RA) is a chronic autoimmune disease affected by genetics and the environment factors. Its early diagnosis and treatment are difficult, and the infection risk is serious. The treatment effects for most patients were not significant, which has become a difficult challenge to overcome. Cell signals play an important role in regulating basic cellular activities such as immunity. Notch signaling is a near secretory signal that can affects many processes of cell normal morphogenesis, including the differentiation of pluripotent progenitor cells, apoptosis, cell proliferation and the formation of cell boundary. In addition, the expression and activation of Notch signaling are increased in the synovial cells and vascular endothelial cells of RA patients. The purpose of this review was to elucidate the related mechanisms of Notch signaling in RA progression, as well as the potential therapeutic value of Notch signaling in a variety of autoimmune diseases.MethodsLiteratures about Notch signaling and RA were extensively reviewed to analyze and discuss.Key Content and FindingsThis article briefly reviews the role of Notch signaling in RA. It also summarizes the functional role of Notch signaling in the treatment of RA, with the goal to provide a new treatment option for RA patients.ConclusionsIn this review, the approach we discussed focuses on Notch signaling as a potential therapeutic target against RA, enriching therapeutic strategies for inflammatory diseases including RA.

Polyphenols Targeting MAPK Mediated Oxidative Stress and Inflammation in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune disorder, predominantly symmetric, which causes joint inflammation, cartilage degeneration and bone erosion, resulting in deformity and the loss of physical function. Although the management of RA has steadily improved, the pathophysiological mechanism is incompletely elucidated, and therapeutic options are still limited. Due to shortcomings in the efficacy or safety profiles of conventional RA therapies, therapeutic alternatives have been considered. Therefore, natural extracts containing polyphenolic compounds can become promising adjuvant agents for RA global management, due to their antioxidant, anti-inflammatory and apoptotic properties. Polyphenols can regulate intracellular signaling pathways in RA and can generate different immune responses through some key factors (i.e., MAPK, interleukins (ILs 1 and 6), tumor necrosis factor (TNF), nuclear factor light k chain promoter of activated receptor (NF-κB), and c-Jun N-terminal kinases (JNK)). The critical function of the Toll like-receptor (TLR)-dependent mitogen-activating protein kinase (MAPK) signaling pathway in mediating the pathogenic characteristics of RA has been briefly discussed. Oxidative stress can trigger a change in transcription factors, which leads to the different expression of some genes involved in the inflammatory process. This review aims to provide a comprehensive perspective on the efficacy of polyphenols in mitigating RA by inhibiting signaling pathways, suggesting future research perspectives in order to validate their use.

Tofacitinib Suppresses Several JAK-STAT Pathways in Rheumatoid Arthritis In Vivo and Baseline Signaling Profile Associates With Treatment Response.

ObjectiveCurrent knowledge on the actions of tofacitinib on cytokine signaling pathways in rheumatoid arthritis (RA) is based on in vitro studies. Our study is the first to examine the effects of tofacitinib treatment on Janus kinase (JAK) - signal transducer and activator of transcription (STAT) pathways in vivo in patients with RA.MethodsSixteen patients with active RA, despite treatment with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), received tofacitinib 5 mg twice daily for three months. Levels of constitutive and cytokine-induced phosphorylated STATs in peripheral blood monocytes, T cells and B cells were measured by flow cytometry at baseline and three-month visits. mRNA expression of JAKs, STATs and suppressors of cytokine signaling (SOCS) were measured from peripheral blood mononuclear cells (PBMCs) by quantitative PCR. Association of baseline signaling profile with treatment response was also investigated.ResultsTofacitinib, in csDMARDs background, decreased median disease activity score (DAS28) from 4.4 to 2.6 (p < 0.001). Tofacitinib treatment significantly decreased cytokine-induced phosphorylation of all JAK-STAT pathways studied. However, the magnitude of the inhibitory effect depended on the cytokine and cell type studied, varying from 10% to 73% inhibition following 3-month treatment with tofacitinib. In general, strongest inhibition by tofacitinib was observed with STAT phosphorylations induced by cytokines signaling through the common-γ-chain cytokine receptor in T cells, while lowest inhibition was demonstrated for IL-10 -induced STAT3 phosphorylation in monocytes. Constitutive STAT1, STAT3, STAT4 and STAT5 phosphorylation in monocytes and/or T cells was also downregulated by tofacitinib. Tofacitinib treatment downregulated the expression of several JAK-STAT pathway components in PBMCs, SOCSs showing the strongest downregulation. Baseline STAT phosphorylation levels in T cells and monocytes and SOCS3 expression in PBMCs correlated with treatment response.ConclusionsTofacitinib suppresses multiple JAK-STAT pathways in cytokine and cell population specific manner in RA patients in vivo. Besides directly inhibiting JAK activation, tofacitinib downregulates the expression of JAK-STAT pathway components. This may modulate the effects of tofacitinib on JAK-STAT pathway activation in vivo and explain some of the differential findings between the current study and previous in vitro studies. Finally, baseline immunological markers associate with the treatment response to tofacitinib.

A comprehensive transcriptomic analysis of alternate interferon signaling pathways in peripheral blood mononuclear cells in rheumatoid arthritis.

Interferon (IFN) signaling pathways play crucial roles in the pathogenesis of rheumatoid arthritis (RA). Prior studies have mainly studied mixed alterations in the IFN signaling pathway in RA, but these studies have not been sufficient to elucidate how imbalanced IFN signaling subtly influences immune cells. Single-cell RNA (scRNA) sequencing makes it possible to better understand the alternations in the interferon signaling pathways in RA. In the present study, we found that IFN signaling pathways were activated in natural killer (NK) cells, monocytes, T cells, B cells, and most immune cell subclasses in RA. We then explored and analyzed the connections between abnormal IFN signaling pathways and cellular functional changes in RA. Single-Cell rEgulatory Network Inference and Clustering (SCENIC) analysis and gene regulatory network (GRN) construction were also performed to identify key transcription factors in RA. Finally, we also investigated altered IFN signaling pathways in multiple RA peripheral blood samples, which indicated that abnormal IFN signaling pathways were universally observed in RA. Our study contributes to a better understanding of the delicate and precise regulation of IFN signaling in the immune system in RA. Furthermore, common alternations in IFN signaling pathway-related transcription factors could help to identify novel therapeutic targets for RA treatment.

Bioinformatic Prediction of Neuropathic Pain Signaling Pathways in Rheumatoid Arthritis after high throughput miRNA analysis

microRNAs (miRNAs) are a special subgroup of RNAs which work to prevent the expression of genes at the post‐transcriptional level by “silencing” them. That is, gene expression is prevented. This ultimately affects the pathways that they are a part of and the products produced by these pathways. Due to the ability of miRNA to bind to any base pair complementary to its own thus inhibiting expression of the sequence it is bound to, they are often involved in multiple cellular pathways. The relation between a specific clinical outcome and an exact pathway that a miRNA is involved is hard to establish because of the sheer number of potential pathways one miRNA could be involved in. Bioinformatic predictions are useful because they allow us to identify the most probable pathway. That is, through the careful analysis of miRNA’s targets and the prediction of the targets’ interactions in biological mechanisms. In this project, we predicted the pathways related to deregulation of miR‐223‐3p and miR‐16‐5p. Both miRNAs were correlated with neuropathy‐related clinical measures (neuropathic pain (ID Pain) and the Toronto Clinical Neuropathy Score (TCNS) respectively (Pearson Coeff.ID Pain=0.556, p=0.014) and (Pearson Coeff.TCNS= −0.5, p=0.02)). To predict possible neuropathic pain signalling pathways in people afflicted with rheumatoid arthritis, we used the miRDB database. We identified 1,485 targets and selected targets with scores of 60+ to carry out a gene ontology analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG). Conducted through DAVID Software from the Laboratory of Human Retrovirology and Immunoinformatics, KEGG identified 72 pathways as the most likely affected by deregulation of miR‐223‐3p and miR‐16‐5p. Several pathways on this list including the FoxO, neurotrophin and sphingolipid signalling pathways are related to pain and neuropathic outcomes. Future studies will have to determine whether both miRNAs affect these pathways directly and in relationship to RA.Support or Funding InformationSupport for student stipends, supplies, and/or equipment used in this research was supplied by the Program for Research Initiatives in Science and Math (PRISM) at John Jay College. PRISM is funded by the Title V program within the U.S. Department of Education; the PAESMEM program through the National Science Foundation; and New York State’s Graduate Research and Technology Initiative and NYS Education Department CSTEP program.

MiR-129-5p regulates cell proliferation and apoptosis via IGF-1R/Src/ERK/Egr-1 pathway in RA-fibroblast-like synoviocytes.

It is reported that miR-129-5p plays an important role in various diseases, but its effect on rheumatoid arthritis (RA) and the potential mechanism remain to be clarified. In the present research, we aimed to investigate the effect of miR-129-5p on RA and the special molecular mechanism. First, the expression of miR-129-5p was analyzed in RA patients and RA Fibroblast-like synoviocytes (RA-FLSs) by RT-PCR assay. The cell viability, apoptotic rate and the relative expression of caspase-3 and caspase-8 were measured by CCK-8, Annexin-FITC/propidium iodide (PI) and ELISA, respectively. Luciferase reporter assay was performed to investigate the target of miR-129-5p. The results revealed that the expression of miR-129-5p was down-regulated in RA patients and RA-FLSs. In addition, miR-129-5p inhibited cell proliferation and induced apoptosis of RA-FLS. Furthermore, luciferase reporter assay demonstrated that insulin-like growth factor-1 receptor (IGF-1R) was the direct target of miR-129-5p, and IGF-1R promoted cell proliferation and inhibited apoptosis by activating Src/ERK/Egr-1 signaling. Furthermoremore, the Src/ERK/Egr-1 signaling pathway was suppressed by miR-129-5p. Collectively, the results of the present study suggested that miR-129-5p regulated cell proliferation and apoptosis via IGF-1R/Src/ERK/Egr-1 signaling pathway in RA.

MAST3 modulates the inflammatory response and proliferation of fibroblast-like synoviocytes in rheumatoid arthritis

Via promoting synovitis, pannus growth and cartilage/bone destruction, fibroblast-like synovial cells (FLSs) play a significant role in the pathogenesis of rheumatoid arthritis (RA). In our study, rats were induced with complete freund’s adjuvant (CFA) to be animal models for studying the RA pathogenesis. Microtubule-associated Serine/Threonine-protein kinase 3 (MAST3) has been documented to play a critical role in regulating the immune response of IBD (Inflammatory bowel disease) and involved in the process of cytoskeleton organization, intracellular signal transduction and peptidyl-serine phosphorylation, but its role in the progression of RA remains unknown and is warranted for investigation. So, we tried our best to investigate the mechanism and signaling pathway of MAST3 in RA progression. In the synovial tissue and FLSs of AA rats, we have found that MAST3 was significantly up-regulated than normal. Furthermore, MAST3 overexpression could promote proliferation and inflammatory response of FLSs. In the aspect of mechanism, we discovered that the expression of MAST3 might involve in NF-κB signaling pathway in RA. On the whole, our results suggested that MAST3 might promote the proliferation and inflammation of FLSs by regulating NF-κB signaling pathway.

Long Non-coding RNA HIX003209 Promotes Inflammation by Sponging miR-6089 via TLR4/NF-κB Signaling Pathway in Rheumatoid Arthritis.

Accumulating studies have suggested that long non-coding RNAs (lncRNAs) have drawn more and more attention in rheumatoid arthritis (RA), which can function as competitive endogenous RNAs (ceRNAs) in inflammation and immune disorders. Previously, we have found that lncRNA HIX003209 is differentially expressed in RA. However, the precise mechanism of lncRNA HIX003209 in RA is still vague. We aim to elucidate the role and its targeted microRNA of lncRNA HIX003209 in RA as ceRNA. Significantly increased expression of lncRNA HIX003209 was observed in the peripheral blood mononuclear cells (PBMCs) from RA cases. It was positively associated with TLR2 and TLR4 in RA. Besides, peptidoglycan (PGN) and lipopolysaccharide (LPS) could enhance the expression of lncRNA HIX003209, which reversely promoted the proliferation and activation of macrophages through IκBα/NF-κB signaling pathway. Moreover, HIX003209 was involved in TLR4-mediated inflammation via targeting miR-6089 in macrophages. LncRNA HIX003209 functions as a ceRNA and exaggerates inflammation by sponging miR-6089 through TLR4/NF-κB pathway in macrophages, which offers promising therapeutic strategies for RA.

Interleukin-35 stimulates tumor necrosis factor-α activated osteoblasts differentiation through Wnt/β-catenin signaling pathway in rheumatoid arthritis

Interleukin (IL)-35 plays an important role in the pathogenesis of rheumatoid arthritis (RA), which is characterized by tumor necrosis factor (TNF)-α activated bone loss beginning early and persisting over time. The aim of this study was to explore the effects and signaling pathway of IL-35 on osteoblasts differentiation in MC3T3E1 cells and TNF-α activated MC3T3E1 cells. A microenvironment was established with low concentration and short-term treatment of TNF-α to mimic inflammatory activated osteoblasts of RA in vitro. The role of IL-35 on osteoblasts proliferation and apoptosis were assessed using cell counting kit (CCK)-8 assay and flow cytometry, respectively. Alkaline phosphatase (ALP) activity was measured by p-nitrophenyl phosphate assay. Extracellular matrix mineralization was measured by Alizarin red S staining. Osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) in response to IL-35 were investigated using real-time polymerase chain reaction and western blot analysis. Wnt/β-catenin signaling pathway in osteoblasts was investigated. In basal and TNF-α activated osteoblasts, IL-35 promoted proliferation and inhibited apoptosis. Basal and TNF-α activated ALP activity and mineralization in vitro was increased stimulated by IL-35. Furthermore, IL-35 increased the basal and TNF-α activated OPG expression and decreased basal and TNF-α activated RANKL expression. Blocking Wnt/β-catenin signaling pathway with Dickkopf (Dkk)-1 inhibited the osteogenic effects of IL-35. IL-35 stimulates basal and TNF-α activated osteoblasts differentiation through the Wnt/β-catenin signaling pathway, thus highlighting the IL-35 for pharmaceutical and medicinal applications for treating RA bone loss.

MicroRNA and exosome: Key players in rheumatoid arthritis.

Rheumatoid arthritis (RA) is known as one of important autoimmune disorders which can lead to joint pain and damage throughout body. Given that internal (ie, genetic and epigenetic alterations) and external factors (ie, lifestyle changes, age, hormones, smoking, stress, and obesity) involved in RA pathogenesis. Increasing evidence indicated that cellular and molecular alterations play critical roles in the initiation and progression of RA. Among various targets and molecular signaling pathways, microRNAs (miRNAs) and their regulatory networks have key roles in the RA pathogenesis. It has been showed that deregulation of many miRNAs involved in different stages of RA. Hence, identification of miRNAs and their signaling pathways in RA, could contribute to new knowledge which help to better treatment of patients with RA. Besides miRNAs, exosomes have been emerged as key messengers in RA pathogenesis. Exsosomes are nanocarriers which could be released from various cells and lead to changing of behaviors recipient cells via targeting their cargos (eg, proteins, messenger RNAs, miRNAs, long noncoding RNAs, DNAs). Here, we summarized several miRNAs involved in RA pathogenesis. Moreover, we highlighted the roles of exosomes in RA pathogenesis.

Calreticulin induced endothelial ICAM-1 up-regulation associated with tristetraprolin expression alteration through PI3K/Akt/eNOS/p38 MAPK signaling pathway in rheumatoid arthritis

The present study was undertaken to determine whether extracellular calreticulin (CRT) participates in the regulation of ICAM-1in rheumatoid arthritis (RA) and further explore the potential mechanism. Our results showed that ICAM-1 and VCAM-1 levels were positively correlated with CRT levels in RA serum and synovial fluid, respectively. In RA synovial tissue, increased co-expressions of CRT and ICAM-1 in vascular endothelium and perivascular areas and elevated co-location of CRT and VCAM-1 localized predominantly to lining layer were observed compared to those in OA. In in vitro HUVECs model, enhanced ICAM-1expression and increased phosphorylation levels of Akt and eNOS were detected in the presence of CRT. Increased phosphorylated eNOS was significantly inhibited by a PI3K inhibitor LY294002 and elevated ICAM-1expression was partially blocked by the inhibitors of both PI3K and eNOS (L-NAME). It has been certified that the RNA-binding protein TTP targets AU-rich elements in the ICAM-1 3′-UTR and suppresses ICAM-1 expression. Knocking down TTP in HUVECs led to an increased induction of ICAM-1 by CRT. We have currently known that activation of p38 downstream kinase MK-2 leads to phosphorylation and inactivation of human TTP. The block of p38 MAPK/MK-2 signaling led to decreased protein expression and mRNA stability of TTP and ICAM-1. Furthermore, L-NAME and/or LY294002 pre-treated HUVECs manifested decreased p38 and MK-2 phosphorylation, which was accompanied by reduced TTP and ICAM-1 protein expression as well as decreased mRNA stability. Our results suggested that CRT could promote ICAM-1 expression in endothelial cells through PI3K/Akt/eNOS/p38 MAPK signaling mediated TTP accumulation, probably in an inactive form, which may provide a possible proinflammatory mechanism of CRT in RA.

Dyrk1A promotes the proliferation, migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis via down-regulating Spry2 and activating the ERK MAPK pathway.

Fibroblast-like synoviocytes (FLSs) play an essential role in rheumatoid arthritis (RA) by promoting synovitis, pannus growth and cartilage/bone destruction. Increased proliferation, migration and invasion of FLSs greatly contribute to RA initiation and progression. Dual-specificity tyrosine-regulated kinase 1A (Dyrk1A), a serine/threonine kinase, regulates MAPK pathway activation, and governs the proliferation and differentiation of neuronal progenitor cells and cancer cells. Till now, the expression and possible function of Dyrk1A in RA FLSs have not been explored. In this study, we detected an increased expression of Dyrk1A both in the synovial tissues of RA patients and in a TNF-α-induced FLSs activation model. CCK-8 and Edu assays revealed that Dyrk1A knockdown inhibited TNF-α-induced FLSs proliferation. Moreover, inhibiting Dyrk1A expression apparently prevented the migration and invasion capability of FLSs accompanied by a decreased MMP-3 and -9 expression. To investigate the molecular mechanism through which Dyrk1A modulates FLSs activities, we evaluated the effects of Dyrk1A on Spry2, a negativity modulator of ERK MAPK pathway. Western blot assay demonstrated that Dyrk1A silencing significantly increased Spry2 expression and suppressed the phosphorylation of ERK in TNF-α-treated FLSs. Taken together, our results indicated that Dyrk1A might promote FLSs proliferation, migration and invasion by suppressing Spry2 expression and activating the ERK MAPK signaling pathway in RA.

Blocking of YY1 reduce neutrophil infiltration by inhibiting IL-8 production via the PI3K-Akt-mTOR signaling pathway in rheumatoid arthritis

Our previous study revealed that Yin Yang 1(YY1) played an important part in promoting interleukin (IL)-6 production in rheumatoid arthritis (RA). However, whether YY1 has any role in regulation of IL-8 in RA remains unclear. YY1 and IL-8 expression in RA patients were analyzed by real-time polymerase chain reaction (PCR). Ingenuity pathway analysis (IPA) was used to analyze the signaling pathway involved in YY1-induced IL-8 production. The expression of YY1 and proteins involved in the pathway were detected by Western blot and enzyme-linked immunosorbent assay (ELISA). Migration of neutrophils was performed by chemotaxis assay. In this study, we found that high expression of IL-8 was positively associated with YY1 expression in RA. Blocking YY1 expression by YY1-short hairpin (sh)RNA lentivirus reduced IL-8 production. Mechanistically, we showed YY1 activated IL-8 production via the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway. Further, using a co-culture system consisting of peripheral blood mononuclear cells (PBMC) and neutrophils, we found that migration of neutrophils would be inhibited by YY1 RNA interference. Finally, using the collagen-induced arthritis animal model, we showed that treatment with the YY1-shRNA lentivirus led to reduction of IL-8 levels and attenuation of inflammation and neutrophil infiltration in vivo. Our results reveal a role of YY1 involved in neutrophil infiltration in RA via the PI3K/Akt/mTOR/IL-8 signaling pathway. YY1 may be a new therapeutic target for treatment of RA.

Anti-Inflammatory Effects of HDL in Mice With Rheumatoid Arthritis Induced by Collagen.

To investigate the anti-inflammatory effects of high-density lipoprotein (HDL) in mice with rheumatoid arthritis (RA) induced by collagen. Male DBA/1 mice (8-week-old) were divided into three groups: control (treated with saline), collagen-induced arthritis (CIA), and CIA + HDL. CIA was induced with bovine type II collagen, and after the injection of bovine type II collagen, the CIA + HDL group received an injection of HDL on day 28 followed by HDL injections four times every 3 days. Mice were weighed, the paws were scored, and paw thickness was measured beginning on day 21. Additionally, the levels of tumor necrosis factor-alpha (TNF-α) and IL-6 were measured by ELISA kits, tissue sections of paws were stained with hematoxylin and eosin, and the inflammatory signaling pathway was analyzed by western blotting. We found that the production of pro-inflammatory cytokines TNF-α and IL-6 in mice which received HDL decreased 45.14 and 35.02%, respectively. And we also found that HDL could significantly decrease the level of anti-type-II-collagen IgG2a and inhibit the neutrophil infiltration and cell proliferation and protect the ankle joint from type II collage-induced injury. Western blot analysis indicated that HDL could also inhibit the activation of the NF-κB, MAPK, and ERK signaling pathways in RA mice. HDL can inhibit the inflammation induced by bovine type II collagen and the development of RA.