Emodin induces ferroptosis in colorectal cancer through NCOA4-mediated ferritinophagy and NF-κb pathway inactivation

Ferroptosis is a new programmed cell death characterized by iron-dependent lipid peroxidation. Targeting ferroptosis is considered a promising strategy for anti-cancer therapy. Recently, natural compound has gained increased attention for their advantage in cancer treatment, and the exploration of natural compounds as ferroptosis inducers offers a hopeful avenue for advancing cancer treatment modalities. Emodin is a natural anthraquinone derivative in many widely used Chinese medicinal herbs. In our previous study, we predicted that the anti-cancer effect of Emodin might related to ferroptosis by using RNA-seq in colorectal cancer (CRC). Thus, in this study, we aim to investigate the molecular mechanism underlying Emodin-mediated ferroptosis in CRC. Cell-based assays including CCK-8, colony formation, EdU, and Annexin V/PI staining were employed to assess Emodin's impact on cell proliferation and apoptosis. Furthermore, various techniques such as FerroOrange staining, C11-BODIPY 581/591 staining, iron, MDA, GSH detection assay and transmission electron microscopy were performed to examine the role of Emodin in ferroptosis. Additionally, specific NCOA4 knockdown cell lines were generated to elucidate the involvement of NCOA4 in Emodin-induced ferroptosis. Moreover, the effects of Emodin on ferroptosis were further confirmed through the application of inhibitors, including Ferrostatin-1, 3-MA, DFO, and PMA. As a results, Emodin inhibited proliferation and induced apoptosis in CRC cells. Emodin could decrease GSH content, xCT and GPX4 expression, meanwhile increasing ROS generation, MDA, and lipid peroxidation, and these effects could reverse by ferroptosis inhibitor, Ferostatin-1, iron chelator DFO, autophagy inhibitor 3-MA and NCOA4 silencing. Moreover, Emodin could inactivate NF-κb pathway, and PMA, an activator of NF-κb pathway could alleviate Emodin-induced ferroptosis in CRC cells. Xenograft mouse model also showed that Emodin suppressed tumor growth and induced ferroptosis in vivo. In conclusion, these results suggested that Emodin induced ferroptosis through NCOA4-mediated ferritinophagy by inactivating NF-κb pathway in CRC cells. These findings not only identified a novel role for Emodin in ferroptosis but also indicated that Emodin may be a valuable candidate for the development of an anti-cancer agent.

Single-cell RNA sequencing reveals myeloid and T cell co-stimulation mediated by IL-7 anti-cancer immunotherapy

BACKGROUND

Immune checkpoint inhibitors unleash inhibitory signals on T cells conferred by tumors and surrounding stromal cells. Despite the clinical efficacy of checkpoint inhibitors, the lack of target expression and persistence of immunosuppressive cells limit the pervasive effectiveness of the therapy. These limitations may be overcome by alternative approaches that co-stimulate T cells and the immune microenvironment.

METHODS

We analyzed single-cell RNA sequencing data from multiple human cancers and a mouse tumor transplant model to discover the pleiotropic expression of the Interleukin 7 (IL-7) receptor on T cells, macrophages, and dendritic cells.

RESULTS

Our experiment on the mouse model demonstrated that recombinant IL-7 therapy induces tumor regression, expansion of effector CD8 T cells, and pro-inflammatory activation of macrophages. Moreover, spatial transcriptomic data support immunostimulatory interactions between macrophages and T cells.

CONCLUSION

These results indicate that IL-7 therapy induces anti-tumor immunity by activating T cells and pro-inflammatory myeloid cells, which may have diverse therapeutic applicability.

The acute phase reactant orosomucoid-2 directly promotes rheumatoid inflammation

Acute phase proteins involved in chronic inflammatory diseases have not been systematically analyzed. Here, global proteome profiling of serum and urine revealed that orosomucoid-2 (ORM2), an acute phase reactant, was differentially expressed in rheumatoid arthritis (RA) patients and showed the highest fold change. Therefore, we questioned the extent to which ORM2, which is produced mainly in the liver, actively participates in rheumatoid inflammation. Surprisingly, ORM2 expression was upregulated in the synovial fluids and synovial membranes of RA patients. The major cell types producing ORM2 were synovial macrophages and fibroblast-like synoviocytes (FLSs) from RA patients. Recombinant ORM2 robustly increased IL-6, TNF-α, CXCL8 (IL-8), and CCL2 production by RA macrophages and FLSs via the NF-κB and p38 MAPK pathways. Interestingly, glycophorin C, a membrane protein for determining erythrocyte shape, was the receptor for ORM2. Intra-articular injection of ORM2 increased the severity of arthritis in mice and accelerated the infiltration of macrophages into the affected joints. Moreover, circulating ORM2 levels correlated with RA activity and radiographic progression. In conclusion, the acute phase protein ORM2 can directly increase the production of proinflammatory mediators and promote chronic arthritis in mice, suggesting that ORM2 could be a new therapeutic target for RA.

Identification of MYH9 as a key regulator for synoviocyte migration and invasion through secretome profiling

OBJECTIVES

'Invasive pannus' is a pathological hallmark of rheumatoid arthritis (RA). This study aimed to investigate secretome profile of synovial fibroblasts of patients with RA (RA-FLSs), a major cell type comprising the invasive pannus.

METHODS

Secreted proteins from RA-FLSs were first identified using liquid chromatography-tandem mass spectrometry analysis. Ultrasonography was performed for affected joints to define synovitis severity at the time of arthrocentesis. Expression levels of myosin heavy chain 9 (MYH9) in RA-FLSs and synovial tissues were determined by ELISA, western blot analysis and immunostaining. A humanised synovitis model was induced in immuno-deficient mice.

RESULTS

We first identified 843 proteins secreted from RA-FLSs; 48.5% of the secretome was associated with pannus-driven pathologies. Parallel reaction monitoring analysis of the secretome facilitated discovery of 16 key proteins related to 'invasive pannus', including MYH9, in the synovial fluids, which represented synovial pathology based on ultrasonography and inflammatory activity in the joints. Particularly, MYH9, a key protein in actin-based cell motility, showed a strong correlation with fibroblastic activity in the transcriptome profile of RA synovia. Moreover, MYH9 expression was elevated in cultured RA-FLSs and RA synovium, and its secretion was induced by interleukin-1β, tumour necrosis factor α, toll-like receptor ligation and endoplasmic reticulum stimuli. Functional experiments demonstrated that MYH9 promoted migration and invasion of RA-FLSs in vitro and in a humanised synovitis model, which was substantially inhibited by blebbistatin, a specific MYH9 inhibitor.

CONCLUSIONS

This study provides a comprehensive resource of the RA-FLS-derived secretome and suggests that MYH9 represents a promising target for retarding abnormal migration and invasion of RA-FLSs.

Role of high-temperature requirement serine protease A 2 in rheumatoid inflammation

BACKGROUND

High-temperature requirement serine protease A 2 (HtrA2) is known to be involved in growth, unfolded protein response to stress, apoptosis, and autophagy. However, whether HtrA2 controls inflammation and immune response remains elusive.

METHODS

Expression of HtrA2 in the synovial tissue of patients was examined using immunohistochemistry and immunofluorescence staining. Enzyme-linked immunosorbent assay was used to determine the concentrations of HtrA2, interleukin-6 (IL-6), interleukin-8 (IL-8), chemokine (C-C motif) ligand 2 (CCL2), and tumor necrosis factor α (TNFα). Synoviocyte survival was assessed by MTT assay. For the downregulation of HtrA2 transcripts, cells were transfected with HtrA2 siRNA.

RESULTS

We found that the concentration of HtrA2 was elevated in rheumatoid arthritis (RA) synovial fluid (SF) than in osteoarthritis (OA) SF, and its concentrations were correlated with the number of immune cells in the RA SF. Interestingly, HtrA2 levels in the SF of RA patients were elevated in proportion to synovitis severity and correlated with the expression of proinflammation cytokines and chemokines, such as IL-6, IL-8, and CCL2. In addition, HtrA2 was highly expressed in RA synovium and primary synoviocytes. RA synoviocytes released HtrA2 when stimulated with ER stress inducers. Knockdown of HtrA2 inhibited the IL1β-, TNFα-, and LPS-induced release of proinflammatory cytokines and chemokines by RA synoviocytes.

CONCLUSION

HtrA2 is a novel inflammatory mediator and a potential target for the development of an anti-inflammation therapy for RA.

The use of animal models in rheumatoid arthritis research

The pathological hallmark of rheumatoid arthritis (RA) is a synovial pannus that comprises proliferating and invasive fibroblast-like synoviocytes, infiltrating inflammatory cells, and an associated neoangiogenic response. Animal models have been established to study these pathological features of human RA. Spontaneous and induced animal models of RA primarily reflect inflammatory aspects of the disease. Among various induced animal models, collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) models are widely used to study the pathogenesis of RA. Improved transplantation techniques for severe combined immunodeficiency (SCID) mouse models of RA can be used to evaluate the effectiveness of potential therapeutics in human tissues and cells. This review provides basic information on various animal models of RA, including CIA and CAIA. In addition, we describe a SCID mouse coimplantation model that can measure the long-distance migration of human RA synoviocytes and cartilage destruction induced by these cells.

Perspectives on single-nucleus RNA sequencing in different cell types and tissues

Single-cell RNA sequencing has become a powerful and essential tool for delineating cellular diversity in normal tissues and alterations in disease states. For certain cell types and conditions, there are difficulties in isolating intact cells for transcriptome profiling due to their fragility, large size, tight interconnections, and other factors. Single-nucleus RNA sequencing (snRNA-seq) is an alternative or complementary approach for cells that are difficult to isolate. In this review, we will provide an overview of the experimental and analysis steps of snRNA-seq to understand the methods and characteristics of general and tissue-specific snRNA-seq data. Knowing the advantages and limitations of snRNA-seq will increase its use and improve the biological interpretation of the data generated using this technique.

HtrA2 regulates α-Synuclein-mediated mitochondrial reactive oxygen species production in the mitochondria of microglia

Aggregation and misfolding of α-Synuclein (α-Syn), a causative agent for Parkinson's disease (PD), and oxidative stress are tightly implicated in the pathogenesis of PD. Although more than 20 genes including HtrA2 have been identified as causative genes for PD, the molecular mechanisms underlying the pathophysiological functions between HtrA2 and α-Syn in the pathogenesis of PD remain unclear. This study shows that HtrA2 serine protease selectively recognizes and interacts with the NAC region of α-Syn. Interestingly, we found that HtrA2 causes proteolysis of α-Syn to prevent mitochondrial accumulation of α-Syn, thereby inhibiting the production of reactive oxygen species (ROS) in the mitochondria. We have further demonstrated that HtrA2 knockdown promotes α-Syn-mediated mitochondrial ROS production, thereby activating microglial cells. This study is the first to demonstrate that the HtrA2/α-Syn cellular partner may play a crucial role in the pathogenesis of PD and provide new insights into the pathological processes and effective therapeutic strategies for PD.

Genetic deficiency of nuclear factor of activated T cells 5 attenuates the development of osteoarthritis in mice

OBJECTIVES

This study is aimed to investigate the role of nuclear factor of activated T cells 5 (NFAT5), originally known as the osmosensitive mammalian transcription factor, in the pathogenesis of osteoarthritis (OA) in mice.

METHODS

OA was induced in male C57BL/6 (wild-type) and NFAT5 haplo-insufficient (NFAT5+/-) mice via destabilization of the medial meniscus (DMM) surgery. OA severity and synovial inflammation were histologically assessed. Expression of CCL2, inflammatory cytokines, cartilage degrading enzymes was determined in the knee joints and cultured chondrocytes from wild-type and NFAT5^+/- mice.

RESULTS

NFAT5 expression was significantly upregulated in the knee joint of a mouse after DMM surgery. NFAT5 deficiency decreased the severity of synovial inflammation and osteoarthritic changes in cartilage and subchondral bone. Moreover, NFAT5 deficiency also decreased the expression of CCL2, IL-1β, MMP-13, ADMATS-5, and macrophage infiltration in the joint. In cultured chondrocytes, hyperosmolar or IL-1β stimulation significantly enhanced the expression of NFAT5, CCL2, IL-1β, IL-6, and MMP-13, and this effect was abolished in chondrocytes from NFAT5^+/- mice. Hyperosmolarity or IL-1β-induced NFAT5 and CCL2 downregulated by inhibiting p38 MAPK, JNK, and ERK pathways.

CONCLUSIONS

Our results indicate that NFAT5 is a crucial regulator of OA pathogenesis by upregulating CCL2 expression and macrophage recruitment. In chondrocyte, NFAT5 plays an important role in the response to hyperosmolar or IL-1β stimulation. Thus, NFAT5 could be an attractive therapeutic target for OA treatment.

Association between metabolic syndrome and Behçet's disease: A nationwide population-based study

Metabolic syndrome (MetS) is characterized by insulin resistance, high blood pressure/sugar, dyslipidemia, and obesity. Whether MetS and its components affect the development of Behçet's disease (BD) remains unclear. This study was performed to investigate the associations between metabolic syndrome and risk of BD using nationwide population data. We conducted a retrospective cohort study of 10 505 818 Korean subjects who received health checkups in 2009-2012. Patients were classified into a MetS and its components group and were followed-up until 2016 for new-onset BD. A Cox proportional hazards model was used to assess the independent or synergistic effects of MetS and its components on the risk of incident BD. Compared to subjects without MetS components, the hazard ratio (HR) for development of BD in patients with MetS was 0.874 (95% confidence interval [CI]: 0.819-0.933) and this association was more prominent when all components of MetS were present (HR = 0.675, 95% CI = 0.571-0.798). Subjects with low high density lipoprotein (HDL) has a significantly increased risk of the development of BD (HR = 1.51, 95% CI = 1.4-1.594) compared to controls. This study showed that the incidence of Behçet's disease was reduced in subjects with MetS. Moreover, the presence of MetS components, with the exception of HDL, was negatively related to the development of BD.

Development of Monitoring System for Assessing Rheumatoid Arthritis within 5 Minutes Using a Drop of Bio-Fluids

Rheumatoid arthritis (RA) disease activity fluctuates over time. The disease activity score 28 (DAS28_ESR) is a widely used and validated scoring system for assessing RA activity; however, it requires time and expertise. This study aimed to develop a new molecular assay capable of rapidly and objectively assessing RA activity. We used a rapid immuno-assay system (FREND™) to measure soluble CD14 (sCD14) levels, which reflect the DAS28_ESR. SCD14 concentrations in urine and serum of RA patients were measured, and RA activity and responses to anti-rheumatic drugs were examined at baseline and after 6 months. FREND™ quantified sCD14 levels in a drop of serum and urine accurately and within 5 min. Serum sCD14 concentrations and its changes correlated well with disease activity and treatment responses, and the results were comparable to C-reactive protein. The new composite indices, including the DAS28_CD14 and simplified DAS_CD14, better detected RA activity than a single sCD14 value and correlated strongly with the DAS28_ESR. These indices exhibited excellent diagnostic performance for discriminating a good response 6 months after treatment. We developed a new system for assessing RA activity and therapeutic outcome within 5 min. CD14-based composite indices may have utility for accurate and frequent monitoring of RA status.

Dynamic transcriptome analysis unveils key proresolving factors of chronic inflammatory arthritis

Despite recent advances in understanding chronic inflammation remission, global analyses have not been explored to systematically discover genes or pathways underlying the resolution dynamics of chronic inflammatory diseases. Here, we performed time-course gene expression profiling of mouse synovial tissues along progression and resolution of collagen-induced arthritis (CIA) and identified genes associated with inflammation resolution. Through network analysis of these genes, we predicted 3 key secretory factors responsible for the resolution of CIA: Itgb1, Rps3, and Ywhaz. These factors were predominantly expressed by Tregs and antiinflammatory M2 macrophages, suppressing production of proinflammatory cytokines. In particular, Ywhaz was elevated in the sera of mice with arthritis resolution and in the urine of rheumatoid arthritis (RA) patients with good therapeutic responses. Moreover, adenovirus-mediated transfer of the Ywhaz gene to the affected joints substantially inhibited arthritis progression in mice with CIA and suppressed expression of proinflammatory cytokines in joint tissues, lymph nodes, and spleens, suggesting Ywhaz is an excellent target for RA therapy. Therefore, our comprehensive analysis of dynamic synovial transcriptomes provides previously unidentified antiarthritic genes, Itgb1, Rps3, and Ywhaz, which can serve as molecular markers to predict disease remission, as well as therapeutic targets for chronic inflammatory arthritis.

The Role of Calcium-Calcineurin-NFAT Signaling Pathway in Health and Autoimmune Diseases

Calcium (Ca²⁺) is an essential signaling molecule that controls a wide range of biological functions. In the immune system, calcium signals play a central role in a variety of cellular functions such as proliferation, differentiation, apoptosis, and numerous gene transcriptions. During an immune response, the engagement of T-cell and B-cell antigen receptors induces a decrease in the intracellular Ca²⁺ store and then activates store-operated Ca²⁺ entry (SOCE) to raise the intracellular Ca²⁺ concentration, which is mediated by the Ca²⁺ release-activated Ca²⁺ (CRAC) channels. Recently, identification of the two critical regulators of the CRAC channel, stromal interaction molecule (STIM) and Orai1, has broadened our understanding of the regulatory mechanisms of Ca²⁺ signaling in lymphocytes. Repetitive or prolonged increase in intracellular Ca²⁺ is required for the calcineurin-mediated dephosphorylation of the nuclear factor of an activated T cell (NFAT). Recent data indicate that Ca²⁺-calcineurin-NFAT1 to 4 pathways are dysregulated in autoimmune diseases. Therefore, calcineurin inhibitors, cyclosporine and tacrolimus, have been used for the treatment of such autoimmune diseases as systemic lupus erythematosus and rheumatoid arthritis. Here, we review the role of the Ca²⁺-calcineurin–NFAT signaling pathway in health and diseases, focusing on the STIM and Orai1, and discuss the deregulated calcium-mediated calcineurin-NFAT pathway in autoimmune diseases.

Transcription Factor NFAT5 Promotes Migration and Invasion of Rheumatoid Synoviocytes via Coagulation Factor III and CCL2

Fibroblast-like synoviocytes (FLSs) play a key role in the progression of rheumatoid arthritis (RA) as a primary component of invasive hypertrophied pannus. FLSs of RA patients (RA-FLSs) exhibit cancer-like features, including promigratory and proinvasive activities that largely contribute to joint cartilage and bone destruction. In this study, we hypothesized that the NF of activated T cell 5 (NFAT5), a transcription factor involving tumor invasiveness, would control the migration and invasion of RA-FLSs. Analyses of transcriptomes demonstrated the significant involvement of NFAT5 in locomotion of RA-FLSs and that tissue factor (TF; also known as coagulation factor III) and CCL2 were the major downstream target genes of NFAT5 involving FLS migration and invasion. In cultured RA-FLSs, IL-1β and TGF-β increased TF and CCL2 expression by upregulating NFAT5 expression via p38 MAPK. Functional assays demonstrated that NFAT5- or TF-deficient RA-FLSs displayed decreased lamellipodia formation, cell migration, and invasion under IL-1β- or TGF-β-stimulated conditions. Conversely, factor VIIa, a specific activator of TF, increased migration of RA-FLSs, which was blocked by NFAT5 knockdown. Recombinant CCL2 partially restored the decrease in migration and invasion of NFAT5-deficient RA-FLSs stimulated with IL-1β. NFAT5-knockout mouse FLSs also showed decreased expressions of TF and CCL2 and reduced cell migration. Moreover, KRN2, a specific inhibitor of NFAT5, suppressed migration of FLSs stimulated with TGF-β. Conclusively, to our knowledge, this is the first study to provide evidence of a functional link between osmoprotective NFAT5 and TF in the migration and invasion of RA-FLSs and supports a role for NFAT5 blockade in the treatment of RA.

Suppression of NFAT5-mediated inflammation and chronic arthritis by novel κB-binding inhibitors

Nuclear factor of activated T cells 5 (NFAT5), also known as the tonicity-responsive enhancer-binding protein, is a transcription factor whose DNA binding domain shares structural homology with NF-kB and other members of the NFAT family. Evidence is emerging that NFAT5 is crucial to the pathogenesis of various human diseases, including cancer and arthritis. However, therapeutic agents specifically inhibiting NFAT5 activity are currently unavailable. To discover NFAT5 inhibitors, we screened a library of >40,000 chemicals for the suppression of nitric oxide, a NFAT5 target, through high-throughput screening. We validated anti-NFAT5 activity of the primary hit compounds using an NFAT5-specific reporter and identified the novel NFAT5 inhibitor KRN2, 13-(2-fluoro)-benzyl-berberine and its oral derivative, KRN5. KRN2 suppressed the transcriptional activation of NFAT5 by blocking NF-κB binding to the NFAT5 promoter region, inhibiting NFAT5 mRNA and protein expression in macrophages stimulated with lipopolysaccharide. Interestingly, KRN2 selectively inhibited the expression of pro-inflammatory genes, including Nos2, Tnf, and Il6 without hampering high-salt-induced NFAT5 and its target gene expressions. Moreover, KRN2 and KRN5 ameliorated experimentally induced arthritis in mice, decreasing pro-inflammatory cytokine production. Particularly, orally administered KRN5 was more potent in suppressing arthritis than methotrexate, a commonly used anti-rheumatic drug. Therefore, KRN2 and KRN5 can be potential therapeutic agents in the treatment of chronic arthritis.

Suppression of NFAT5-mediated Inflammation and Chronic Arthritis by Novel κB-binding Inhibitors

Nuclear factor of activated T cells 5 (NFAT5) has been implicated in the pathogenesis of various human diseases, including cancer and arthritis. However, therapeutic agents inhibiting NFAT5 activity are currently unavailable. To discover NFAT5 inhibitors, a library of > 40,000 chemicals was screened for the suppression of nitric oxide, a direct target regulated by NFAT5 activity, through high-throughput screening. We validated the anti-NFAT5 activity of 198 primary hit compounds using an NFAT5-dependent reporter assay and identified the novel NFAT5 suppressor KRN2, 13-(2-fluoro)-benzylberberine, and its derivative KRN5. KRN2 inhibited NFAT5 upregulation in macrophages stimulated with lipopolysaccharide and repressed the formation of NF-κB p65-DNA complexes in the NFAT5 promoter region. Interestingly, KRN2 selectively suppressed the expression of pro-inflammatory genes, including Nos2 and Il6, without hampering high-salt-induced NFAT5 and its target gene expressions. Moreover, KRN2 and KRN5, the latter of which exhibits high oral bioavailability and metabolic stability, ameliorated experimentally induced arthritis in mice without serious adverse effects, decreasing pro-inflammatory cytokine production. Particularly, orally administered KRN5 was stronger in suppressing arthritis than methotrexate, a commonly used anti-rheumatic drug, displaying better potency and safety than its original compound, berberine. Therefore, KRN2 and KRN5 can be potential therapeutic agents in the treatment of chronic arthritis.

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We identify a novel NFAT5 suppressor KRN2, 13-(2-fluoro)-benzylberberine, and its derivative KRN5 to inhibit NFAT5 activity.

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KRN2 inhibits the transcriptional activation of NFAT5 and the pro-inflammatory responses.

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KRN2 and KRN5 suppress experimentally induced arthritis in mice.

NFAT5 has been implicated in the pathogenesis of arthritis. However, therapeutic agents specifically inhibiting NFAT5 activity are currently unavailable. To discover NFAT5 inhibitors, a library of > 40,000 chemicals was screened, leading to the discovery of novel berberine-based NFAT5 suppressors, KRN2 and its oral derivative KRN5. KRN2 inhibited the transcriptional activation of NFAT5 by blocking NF-κB binding to the NFAT5 promoter region, thereby reducing the expression of pro-inflammatory genes. Moreover, KRN2 and KRN5 ameliorated experimentally induced arthritis in mice without serious adverse effects. Therefore, we propose that KRN2 and KRN5 may be potential therapeutic agents in the treatment of chronic arthritis.

Urinary interleukin-6 as a predictor of radiographic progression in rheumatoid arthritis: A 3-year evaluation

Previously, we demonstrated that the urine proteome signature of patients with rheumatoid arthritis (RA) reflects inflammation-related cellular processes. Here, we measured interleukin (IL)-6, IL-8, and chemokine ligand 2 (CCL2) concentrations in the urine of RA patients and prospectively investigated their role in predicting RA activity and prognosis. One hundred seventy-three RA patients and 62 non-RA controls were recruited. Urinary IL-6, CCL2, and IL-8 levels were elevated in RA patients and correlated well with disease activity. Urinary IL-6 level at presentation was an independent risk factor of radiographic progression at 1 and 3 years. High urinary IL-6 level increased the risk ratio of radiographic progression by 2.9-fold, which was comparable to high serum CRP. Moreover, combination of urinary IL-6 and serum CRP measures synergistically increased the predictability of radiographic progression. In a subgroup with normal ESR, patients with the highest tertile of urinary IL-6 were at 6.4-fold greater risk of radiographic progression. Conclusively, high urinary IL-6 level at presentation is an independent risk factor for radiographic progression of RA, reflecting disease activity. Urinary IL-6 in combination with serum CRP may be a useful parameter for estimating RA prognosis.

Anti-inflammatory effects of essential oils extracted from Chamaecyparis obtusa on murine models of inflammation and RAW 264.7 cells

Antimicrobial, antifungal and anti-inflammatory effects of essential oils extracted from Chamaecyparis obtusa (EOCO) have previously been reported. In the present study, the anti-inflammatory effects of EOCO were investigated in two murine models of inflammation: Carrageenan-induced paw edema and thioglycollate-induced peritonitis, and in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The expression levels of proinflammatory cytokines were analyzed by ELISA, the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were determined by western blotting, and nitrite concentration was measured using Griess reagent. In mice with carrageenan-induced edema, paw thickness and the expression levels of interleukin (IL)‑1β and IL-6 in paw homogenates were significantly decreased in the EOCO (5 and 10 mg/kg) group, as compared with the control group. In mice with thioglycollate-induced peritonitis, treatment with EOCO (5 and 10 mg/kg) reduced the number of total cells and suppressed tumor necrosis factor‑α (TNF‑α), IL‑1β and IL‑6 levels in peritoneal fluid. In addition, EOCO reduced nitric oxide, TNF‑α and IL‑6 production, and suppressed iNOS and COX‑2 expression in LPS‑stimulated RAW 264.7 cells. These results suggest that EOCO may exert anti‑inflammatory effects in vivo and in vitro, and that these effects may be associated with the inhibition of inflammatory mediators. Therefore, EOCO may be considered an effective therapeutic agent for the treatment of inflammatory diseases.

GREM1 Is a Key Regulator of Synoviocyte Hyperplasia and Invasiveness

OBJECTIVE

To investigate the expression of Gremlin 1 (GREM1), an antagonist of bone morphogenetic protein, in rheumatoid arthritis (RA) synovia and its involvement in the hyperplasia and invasiveness of fibroblast-like synoviocytes of RA (RA-FLS).

METHODS

Computational analysis was introduced to identify FLS-predominant regulators. GREM1 expression was examined by immunohistochemistry, real-time PCR, and ELISA. FLS proliferation and apoptosis were determined using tetrazolium-based colorimetric assay and APOPercentage assay, respectively. FLS migration and invasion were evaluated by wound migration and Matrigel invasion assay, respectively. Expressions of Bax, Bcl2, pErk1/2, and pAkt were detected by Western blot analysis.

RESULTS

Through global transcriptome profiling, we identified a GREM1 gene predominantly expressed in RA-FLS. Indeed, the GREM1 expression was higher in synovia, synovial fluids, and FLS of patients with RA than in those of patients with osteoarthritis, and its levels correlated well with proinflammatory cytokine concentrations. Knockdown of GREM1 transcripts using short interfering RNA (siRNA) reduced the proliferation and survival of RA-FLS along with downregulation of pErk1/2, pAkt, and Bcl2 expressions, whereas it induced Bax expression. Conversely, the addition of recombinant GREM1 to RA-FLS showed the opposite results. Moreover, GREM1 siRNA decreased the migratory and invasive capacity of RA-FLS, whereas exogenous GREM1 increased it. The GREM1-induced FLS survival, migration, and invasion were completely blocked by neutralizing antibodies to ανβ3 integrin on RA-FLS, suggesting that ανβ3 integrin mediates the antiapoptotic and promigratory effects of GREM1.

CONCLUSION

GREM1 is highly expressed in RA joints, and functions as a regulator of survival, proliferation, migration, and invasion of RA-FLS.

Antinociceptive and anti-inflammatory effects of essential oil extracted from Chamaecyparis obtusa in mice

Essential oil extracted from Chamaecyparis obtusa (EOCO) consists of several monoterpenes with anti-inflammatory effects. Monoterpenes are expected to have an analgesic effect through inhibition of pro-inflammatory mediators. The present study investigated the anti-nociceptive and anti-inflammatory effects of EOCO in animal models of pain. Intraperitoneal injection with EOCO (5 or 10mg/kg), aspirin (positive control, 300mg/kg), or DMSO (negative control) was performed 1h before the nociception tests: acetic acid-induced writhing response, formalin test, and hot plate test in mice, and acidic saline-induced allodynia in rats. The expression of pro-inflammatory cytokines and pro-inflammatory enzymes in formalin-injected paws was determined by ELISA and western blotting, respectively. Treatment with EOCO significantly reduced acetic acid-induced writhing and paw-licking time in late response of the formalin tests. The anti-nociceptive effect was comparable with aspirin. However, EOCO did not affect the reaction time of licking of the hind paws or jumping in hot plate test and the mechanical withdrawal thresholds in acidic saline-induced allodynia model. Formalin-injected paws of mice treated with EOCO revealed the down-regulated expression of tumor necrosis factor-α, interleukin-1β, inducible nitric oxide synthase, and cyclooxygenase-2, as compared with those of control mice. These data showed the anti-nociceptive and anti-inflammatory effects of EOCO. The pain-relieving effect might be attributed to inhibition of peripheral pain in association with inflammatory response. EOCO could be a useful therapeutic strategy to manage pain and inflammatory diseases.

DNA Methylation Regulates the Differential Expression of CX3CR1 on Human IL-7Rαlow and IL-7Rαhigh Effector Memory CD8+ T Cells with Distinct Migratory Capacities to the Fractalkine

DNA methylation is an epigenetic mechanism that modulates gene expression in mammalian cells including T cells. Memory T cells are heterogeneous populations. Human effector memory (EM) CD8(+) T cells in peripheral blood contain two cell subsets with distinct traits that express low and high levels of the IL-7Rα. However, epigenetic mechanisms involved in defining such cellular traits are largely unknown. In this study, we use genome-wide DNA methylation and individual gene expression to show the possible role of DNA methylation in conferring distinct traits of chemotaxis and inflammatory responses in human IL-7Rα(low) and IL-7Rα(high) EM CD8(+) T cells. In particular, IL-7Rα(low) EM CD8(+) T cells had increased expression of CX3CR1 along with decreased DNA methylation in the CX3CR1 gene promoter compared with IL-7Rα(high) EM CD8(+) T cells. Altering the DNA methylation status of the CX3CR1 gene promoter changed its activity and gene expression. IL-7Rα(low) EM CD8(+) T cells had an increased migratory capacity to the CX3CR1 ligand fractalkine compared with IL-7Rα(high) EM CD8(+) T cells, suggesting an important biological outcome of the differential expression of CX3CR1. Moreover, IL-7Rα(low) EM CD8(+) T cells induced fractalkine expression on endothelial cells by producing IFN-γ and TNF-α, forming an autocrine amplification loop. Overall, our study shows the role of DNA methylation in generating unique cellular traits in human IL-7Rα(low) and IL-7Rα(high) EM CD8(+) T cells, including differential expression of CX3CR1, as well as potential biological implications of this differential expression.

Anti-inflammatory effects of essential oils extracted from Chamaecyparis obtusa in inflammatory models of mice and raw 264.7 cells (CAM1P.165)

Although the biological activities of essential oil extracted from Chamaecyparis obtusa (EOCO) are not yet fully understood, antimicrobial, antifungal and anti-inflammatory effects have been reported. In this study, we investigated the anti-inflammatory effects of EOCO in two inflammatory models of mice, carrageenan-induced paw edema and thioglycollate-induced peritonitis, and lipopolysaccharide (LPS)-stimulated Raw 264.7 macrophage cells. Levels of pro-inflammatory cytokines were analyzed by ELISA, expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were determined by western blotting, and nitrite concentration was measured using Griess reagent. The thicknesses of mice paw edema induced by carrageenan and interleukin-1β (IL-1β) and interleukin-6 (IL-6) levels in paw homogenates were significantly decreased in the EOCO (5 and 10 mg/kg) group as compared with control group. In mice with thioglycollate-induced peritonitis, EOCO (5 and 10 mg/kg) treatment reduced the numbers of total cells and suppressed tumor necrosis factor (TNF)-α, IL-1β, and IL-6 levels in peritoneal fluid. EOCO also decreased nitric oxide (NO), TNF-α and IL-6 production and inhibited iNOS and COX-2 expressions in LPS-stimulated Raw 264.7 cells. These data showed that EOCO has anti-inflammatory effect both in vivo and in vitro, and this effect may be related with inhibition of inflammatory mediators. In conclusion, EOCO could be an effective therapeutic agent in inflammatory diseases.

Urinary proteome profile predictive of disease activity in rheumatoid arthritis

Current serum biomarkers for rheumatoid arthritis (RA) are not highly sensitive or specific to changes of disease activities. Thus, other complementary biomarkers have been needed to improve assessment of RA activities. In many diseases, urine has been studied as a window to provide complementary information to serum measures. Here, we conducted quantitative urinary proteome profiling using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and identified 134 differentially expressed proteins (DEPs) between RA and osteoarthritis (OA) urine samples. By integrating the DEPs with gene expression profiles in joints and mononuclear cells, we initially selected 12 biomarker candidates related to joint pathology and then tested their altered expression in independent RA and OA samples using enzyme-linked immunosorbent assay. Of the initial candidates, we selected four DEPs as final candidates that were abundant in RA patients and consistent with those observed in LC-MS/MS analysis. Among them, we further focused on urinary soluble CD14 (sCD14) and examined its diagnostic value and association with disease activity. Urinary sCD14 had a diagnostic value comparable to conventional serum measures and an even higher predictive power for disease activity when combined with serum C-reactive protein. Thus, our urinary proteome provides a diagnostic window complementary to current serum parameters for the disease activity of RA.

Human monocytes have increased IFN-γ-mediated IL-15 production with age alongside altered IFN-γ receptor signaling

IL-15 is involved in regulating host defense and inflammation. Monocytes produce the biologically active cell surface IL-15 in response to IFN-γ. Although aging can alter the immune system, little is known about whether and how aging affects IFN-γ-mediated IL-15 production in human monocytes. We showed that monocytes of healthy older adults (age ≥ 65) had increased cell surface IL-15 expression in response to IFN-γ compared to those of healthy young adults (age ≤ 40). This finding stems in part from increased IFN-γ receptor (R)1/2 expression on monocytes in older adults, leading to enhanced STAT1 activation and interferon regulatory factor 1 synthesis with increased IL15 gene expression. Our study suggests that with aging the IFN-γ-mediated IL-15 production pathway in human monocytes is uncompromised, but rather augmented, and could be considered as a therapeutic target point to modulate host defense and inflammation in older adults.

Role of endoplasmic reticulum stress in rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by abnormal proliferation of synoviocytes, leukocyte infiltration, and angiogenesis. The endoplasmic reticulum (ER) is the site of biosynthesis for all secreted and membrane proteins. The accumulation of unfolded proteins in the ER leads to a condition known as ER stress. Failure of the ER's adaptive capacity results in abnormal activation of the unfolded protein response. Recently, we have demonstrated that ER stress-associated gene signatures are highly expressed in RA synovium and synovial cells. Mice with Grp78 haploinsufficiency exhibit the suppression of experimentally induced arthritis, suggesting that the ER chaperone GRP78 is crucial for RA pathogenesis. Moreover, increasing evidence has suggested that GRP78 participates in antibody generation, T cell proliferation, and pro-inflammatory cytokine production, and is therefore one of the potential therapeutic targets for RA. In this review, we discuss the putative, pathophysiological roles of ER stress and GRP78 in RA pathogenesis.

Defining cellular characteristics of human IL-7Rαlow memory CD8+ T cells using a genome-wide DNA methylation analysis (P1432)

DNA methylation is one of the predominant epigenetic mechanisms to propagate heritable epigenetic information. Recently, we identified two subsets of memory CD8+ T cells expressing high and low levels of IL-7Rα in humans. IL-7Rαlow memory CD8+ T cells have impaired proliferation and survival in response to TCR triggering and IL-7, respectively. Importantly, the expansion of IL-7Rαlow memory CD8+ T occurs in human aging and lupus, suggesting a potential role for this cell subset in immunosenescence and autoimmunity. However, the exact characteristics of this cell subset are yet to be defined. Of interest, IL-7Rα expression in T cells is tightly regulated by DNA methylation in the IL-7Rα gene promoter. Here, we investigated how DNA methylation contributes to determining the distinct characteristics and functions of IL-7Rαhigh and IL-7Rαlow memory CD8+ T cells using genome-wide DNA methylation profiling technique. Methylation profiling revealed genes that are differentially methylated between IL-7Rαhigh and IL-7Rαlow memory CD8+ T cells. In particular, we found that the most significantly hypomethylated genes in IL-7Rαlow memory CD8+ T cells are associated with chemotaxis (CX3CR1, CXCR1, CCL3, and CCL4). Furthermore, the hypomethylation of these genes directly correlated with increased gene expression in this cell subset. Our data suggest that DNA methylation can be an important mechanism involved in defining the characteristics of IL-7Rαlow memory CD8+ T cells.

Association of polymorphisms modulating low-density lipoprotein cholesterol with susceptibility, severity, and progression of rheumatoid arthritis

OBJECTIVE

Dyslipidemia, a risk factor for cardiovascular diseases, is more prevalent in patients with rheumatoid arthritis (RA) than in the general population. We investigated whether single-nucleotide polymorphisms (SNP) modulating low-density lipoprotein (LDL) cholesterol affect susceptibility, severity, and progression of RA.

METHODS

We enrolled 302 patients with RA and 1636 healthy controls, and investigated the SNP modulating LDL cholesterol. Clinical characteristics of RA, serum adipocytokine concentrations, and radiographic severity were analyzed according to genotype score based on the number of unfavorable alleles. The influence of genotype score on radiographic progression was also investigated using multivariable logistic models.

RESULTS

We identified 3 SNP (rs688, rs693, and rs4420638) modulating LDL cholesterol in Koreans, which correlated well with LDL cholesterol levels in both patients with RA and controls. Among them, 2 SNP, rs688 and rs4420638, were more prevalent in patients with RA than in controls. In patients with RA carrying more unfavorable alleles (genotype score ≥ 3), disease activity measures, serum adipocytokine levels, and radiographic severity were all increased. The genotype score was an independent risk factor for radiographic progression of RA over 2 years, and its effect was greater than the influence of conventional risk factors.

CONCLUSION

SNP modulating LDL cholesterol influence the risk, activity, and severity of RA. These results provide the first evidence that genetic mechanisms linked to dyslipidemia may directly contribute to the susceptibility and prognosis of RA, a representative of chronic inflammatory diseases, explaining the high incidence of dyslipidemia in RA.

The Wnt inhibitor secreted Frizzled-Related Protein 1 (sFRP1) promotes human Th17 differentiation

Wnt/β-catenin signaling plays a crucial role during embryogenesis and tumorigenesis, and in T cells, promotes the differentiation of Th2 cells. However, the role of Wnt signals in the differentiation and maintenance of human Th17 cells remains poorly understood. We found that the higher levels of IL-17 in the synovial fluid of rheumatoid arthritis (RA) patients compared with that of osteoarthritis (OA) patients were associated with a higher concentration of sFRP1 (secreted Frizzled-Related Protein 1), an inhibitor of the Wnt/β-catenin pathway. The addition of sFRP1 during TCR-mediated stimulation induced a significant increase in IL-17 production by both naïve and memory CD4(+) T cells. Moreover, under Th17-differentiation conditions, the addition of sFRP1 significantly reduced the requirement for TGF-β. Mechanistically, we observed that sFRP1 significantly enhanced the phosphorylation of Smad2/3 in CD4(+) T cells upon TGF-β stimulation and that blocking TGF-β signaling abolished the Th17-promoting activity of sFRP1. Our findings reveal a novel function for sFRP1 as a potent inducer of human Th17-cell differentiation. Consequently, sFRP1 may represent a promising target for the treatment of Th17-mediated disease in humans.

A novel pathogenic role of the ER chaperone GRP78/BiP in rheumatoid arthritis

An accumulation of misfolded proteins can trigger a cellular survival response in the endoplasmic reticulum (ER). In this study, we found that ER stress-associated gene signatures were highly expressed in rheumatoid arthritis (RA) synoviums and synovial cells. Proinflammatory cytokines, such as TNF and IL-1β, increased the expression of GRP78/BiP, a representative ER chaperone, in RA synoviocytes. RA synoviocytes expressed higher levels of GRP78 than osteoarthritis (OA) synoviocytes when stimulated by thapsigargin or proinflammatory cytokines. Down-regulation of Grp78 transcripts increased the apoptosis of RA synoviocytes while abolishing TNF- or TGF-β-induced synoviocyte proliferation and cyclin D1 up-regulation. Conversely, overexpression of the Grp78 gene prevented synoviocyte apoptosis. Moreover, Grp78 small interfering RNA inhibited VEGF(165)-induced angiogenesis in vitro and also significantly impeded synoviocyte proliferation and angiogenesis in Matrigel implants engrafted into immunodeficient mice. Additionally, repeated intraarticular injections of BiP-inducible factor X, a selective GRP78 inducer, increased synoviocyte proliferation and angiogenesis in the joints of mice with experimental OA. In contrast, mice with Grp78 haploinsufficiency exhibited the suppression of experimentally induced arthritis and developed a limited degree of synovial proliferation and angiogenesis. In summary, this study shows that the ER chaperone GRP78 is crucial for synoviocyte proliferation and angiogenesis, the pathological hallmark of RA.

NF-AT5 is a critical regulator of inflammatory arthritis

OBJECTIVE

To investigate the role of NF-AT5, an osmoprotective transcription factor, in synovial hyperplasia and angiogenesis in patients with rheumatoid arthritis (RA).

METHODS

The expression of NF-AT5 in synovial tissue and synoviocytes from RA patients was examined by immunohistochemistry and Western blot analysis, respectively. Messenger RNA (mRNA) in RA synoviocytes and human umbilical vein endothelial cells (HUVECs) transfected with dummy small interfering RNA (siRNA) or NF-AT5 siRNA were profiled using microarray technology. Assays to determine synoviocyte apoptosis and proliferation were performed in the presence of NF-AT5 siRNA. VEGF₁₆₅-induced angiogenesis was assessed by measuring the proliferation, tube formation, and wound migration of HUVECs. Experimental arthritis was induced in mice by injection of anti-type II collagen antibody.

RESULTS

NF-AT5 was highly expressed in rheumatoid synovium, and its activity was increased by proinflammatory cytokines, such as interleukin-1β and tumor necrosis factor α. The mRNA profiling of synoviocytes and HUVECs transfected with NF-AT5-targeted siRNA revealed 3 major changes in cellular processes associated with the pathogenesis of RA: cell cycle and survival, angiogenesis, and cell migration. Consistent with these results, NF-AT5 knockdown in RA synoviocytes and HUVECs inhibited their proliferation/survival and impeded angiogenic processes in HUVECs. Mice with NF-AT5 haploinsufficiency (NF-AT5(+/-)) developed a very limited degree of synovial proliferation, as seen on histologic analysis, and decreased angiogenesis, and they exhibited a nearly complete suppression of experimentally induced arthritis.

CONCLUSION

NF-AT5 regulates synovial proliferation and angiogenesis in chronic arthritis.

Anti-neuropilin-1 peptide inhibition of synoviocyte survival, angiogenesis, and experimental arthritis

OBJECTIVE

To delineate the role of neuropilin-1 (NP-1), a vascular endothelial growth factor receptor (VEGFR), in rheumatoid inflammation and to determine whether blockade of NP-1 could suppress synoviocyte survival and angiogenesis.

METHODS

VEGF(111-165) peptide, which encompasses the NP-1 binding domain of VEGF(165), was generated by cleaving VEGF(165) with plasmin. The effect of this peptide on the interaction between VEGF(165) and its receptor was determined by (125)I-VEGFR binding assay. Assays to determine synoviocyte apoptosis, adhesion, and migration were performed in the presence of VEGF(165) and/or the peptide. VEGF(165)-induced angiogenesis was assessed by measuring the proliferation, tube formation, and wounding migration of endothelial cells (ECs). Mice were immunized with type II collagen to induce experimental arthritis.

RESULTS

VEGF(111-165) peptide specifically inhibited the binding of (125)I-VEGF(165) to NP-1 on rheumatoid synoviocytes and ECs. The peptide eliminated the VEGF(165)-mediated increase in synoviocyte survival and activation of p-ERK and Bcl-2. The peptide also completely inhibited a VEGF(165)-induced increase in synoviocyte adhesion and migration. In addition, the anti-NP-1 peptide blocked VEGF(165)-stimulated proliferation, capillary tube formation, and wounding migration of ECs in vitro. VEGF(165)-induced neovascularization in a Matrigel plug in mice was also blocked by treatment with the peptide. Finally, subcutaneous injection of anti-NP-1 peptide suppressed arthritis severity and autoantibody formation in mice with experimental arthritis and inhibited synoviocyte hyperplasia and angiogenesis in arthritic joints.

CONCLUSION

Anti-NP-1 peptide suppressed VEGF(165)-induced increases in synoviocyte survival and angiogenesis, and thereby blocked experimental arthritis. Our findings suggest that anti-NP-1 peptide could be useful in alleviating chronic arthritis.

Inhibition of synovial hyperplasia, rheumatoid T cell activation, and experimental arthritis in mice by sulforaphane, a naturally occurring isothiocyanate

OBJECTIVE

To investigate whether sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables such as broccoli, regulates synoviocyte hyperplasia and T cell activation in rheumatoid arthritis (RA).

METHODS

Synoviocyte survival was assessed by MTT assay. The levels of Bcl-2, Bax, p53, and pAkt were determined by Western blot analysis. Cytokine concentrations in culture supernatants from mononuclear cells were analyzed by enzyme-linked immunosorbent assay. The in vivo effects of SFN were examined in mice with experimentally induced arthritis.

RESULTS

SFN induced synoviocyte apoptosis by modulating the expression of Bcl-2/Bax, p53, and pAkt. In addition, nonapoptotic doses of SFN inhibited T cell proliferation and the production of interleukin-17 (IL-17) and tumor necrosis factor alpha (TNFalpha) by RA CD4+ T cells stimulated with anti-CD3 antibody. Anti-CD3 antibody-induced increases in the expression of retinoic acid-related orphan receptor gammat and T-bet were also repressed by SFN. Moreover, the intraperitoneal administration of SFN to mice suppressed the clinical severity of arthritis induced by injection of type II collagen (CII), the anti-CII antibody levels, and the T cell responses to CII. The production of IL-17, TNFalpha, IL-6, and interferon-gamma by lymph node cells and spleen cells from these mice was markedly reduced by treatment with SFN. Anti-CII antibody-induced arthritis in mice was also alleviated by SFN injection.

CONCLUSION

SFN was found to inhibit synovial hyperplasia, activated T cell proliferation, and the production of IL-17 and TNFalpha by rheumatoid T cells in vitro. The antiarthritic and immune regulatory effects of SFN, which were confirmed in vivo, suggest that SFN may offer a possible treatment option for RA.

A novel pathogenic mechanism of the ER chaperone BiP/Grp78 response in rheumatoid synoviocytes (137.27)

The accumulation of misfolded proteins can trigger a cellular survival response in the endoplasmic reticulum (ER). In this study, we investigated the role of the ER chaperone BiP/Grp78 in abnormal proliferation of rheumatoid arthritis (RA) synoviocytes, which is the pathologic hallmark of RA. The results showed that BiP protein was highly expressed in RA synovium and synoviocytes. The proinflammatory cytokines, such as TNF-alpha and IL-1beta, and hypoxic stimuli, but not IL-10, increased the BiP expression in RA synoviocytes. RA synoviocytes were more resistant to ER-stress-induced apoptosis as compared to OA synoviocytes. ER stress inducers, thapsigargin and tunicamycin, increased BiP and Bcl-2 expressions in synoviocytes, which were much greater in RA synoviocytes than in OA synoviocytes. A BiP-inducer, BIX, blocked the ER-stress induced synoviocyte apoptosis, possibly by increasing Bcl-2 and BiP expression. In contrast, BiP knockdown in RA synoviocytes, using siRNA, abolished the TNF-alpha- and TGF-beta-induced synoviocyte proliferation and cyclin D1 upregulation. BiP with a higher molecular size than intracellular BiP was found in all (6/6) RA synovial fluids tested. Exogenous BiP strongly increased IL-17 and TNF-alpha production from RA mononuclear cells, but not from mononuclear cells of healthy controls. In summary, we demonstrated first that BiP is crucial to the resistance to apoptosis of RA synoviocytes and synoviocyte proliferation, and it involves the production of IL-17 and TNF-alpha from mononuclear cells, suggesting that ER chaperone BiP response contributes to RA pathogenesis by inducing synovial hyperplasia and Th17 cell generation.

NADPH quinone oxidoreductase induction by sulforaphane inhibits synovial hyperplasia and rheumatoid T cell proliferation. (50.15)

Sulforaphane (SFN), derived from cruciferous vegetables, has been previously shown to induce phase II enzyme and to have anti-carcinogenic activity. In this study, we investigated whether SFN regulates synoviocyte hyperplasia and T cell proliferation in rheumatoid arthritis (RA). SFN induced synoviocyte apoptosis by regulating Bcl-2/Bax expression and pAkt activity. In addition, SFN dose-dependently inhibited T cell proliferation and the production of IL-17 and TNF-alpha by RA mononuclear cells stimulated with anti-CD3 antibody, but enhanced the enzyme activities of NADPH quinone oxidoreductase-1 (NQO1), a representative phase II enzyme. SFN inhibition of synoviocyte survival was abrogated by co-treatment with curcumin, an inhibitor of NQO1 or by downregulation of NQO1 transcripts. The intra-peritoneal administration of SFN to mice with type II collagen (CII)-induced arthritis suppressed arthritis severity, anti-CII antibody levels, and T cell proliferative response to CII. The productions of IL-17, TNF-alpha, IL-6, and IFN-gamma from lymph node and spleen cells of these mice also were markedly reduced by SFN treatment. Moreover, in mice with anti-CII antibody-induced arthritis, a passive model of arthritis that is independent of adaptive immunity, SFN treatment reduced arthritis severity and synovial hyperplasia. In summary, NQO1 induction by SFN was found to inhibit synoviocyte proliferation and TH17 cell activation in vitro. Moreover, the anti-arthritic and immune regulatory effects of SFN were confirmed in vivo, which suggests that SFN may offer a possible treatment option for RA.

Circulating osteoprotegerin levels are elevated and correlated with antiphospholipid antibodies in patients with systemic lupus erythematosus

Patients with antiphospholipid syndrome (APS) have an increased risk for the development of thrombotic complications. Recent studies indicate that osteoprotegerin (OPG) acts as an important molecule in the development of vascular diseases. The aim of the present study was to examine the association between serum OPG levels and APS manifestations in patients with SLE. Seventy-nine patients with SLE and ninety-two healthy controls, matched for age and sex, were included in this study. Serum levels of OPG, monocyte chemoattractant protein(MCP)-1 and soluble E-selectin were determined by ELISA. At the time of serum sampling, various clinical and laboratory parameters were assessed. We found that serum levels of OPG were significantly higher in patients with SLE than in healthy controls (1236 ± 82 vs 967 ± 37 pg/mL, P = 0.003). Particularly, serum OPG levels were significantly higher in SLE patients with APS than those without (1615 ± 191 vs 1171 ± 91 pg/mL, P = 0.006). Serum OPG levels correlated with titres of IgG anti-cardiolipin antibody ( P = 0.026) and anti-β2-glycoprotein I antibody ( P < 0.001). Moreover, serum OPG also correlated with serum levels of sE-selectin ( P = 0.002), which is an endothelial cell activation marker, and MCP-1 ( P = 0.003), a well known chemokine implicated in thrombogenesis. Collectively, serum OPG levels were increased in SLE patients with APS and correlated with titres of antiphospholipid antibodies, suggesting that OPG might be linked to the development of APS.

The Therapeutic Effect of Extracellular Superoxide Dismutase (EC-SOD) Mouse Embryonic Fibroblast (MEF) on Collagen-Induced Arthritis (CIA) Mice

Rheumatoid arthritis is a chronic inflammatory disease. The generation of reactive oxygen species (ROS) within an inflamed joint has been suggested as playing a significant pathogenic role. Extracellular superoxide dismutase (EC-SOD) is a major scavenger enzyme of ROS, which has received growing attention for its therapeutic potential. To investigate the therapeutic effect of EC-SOD in mice with collagen-induced arthritis (CIA), we used mouse embryonic fibroblast (MEF) of transgenic mice that overexpresses EC-SOD on the skin by using hK14 promoter. DBA/1 mice that had been treated with bovine type II collagen were administrated subcutaneous injections of EC-SOD transgenic MEF (each at 1.4 × 106 cells) on days 28, 35, and 42 after primary immunization. To test EC-SOD activity, blood samples were collected in each group on day 49. The EC-SOD activity was nearly 1.5-fold higher in the transgenic MEF-treated group than in the non-transgenic MEF-treated group (p < 0.05). The severity of arthritis in mice was scored in a double-blind manner, with each paw being assigned a separate clinical score. The severity of arthritis in EC-SOD transgenic MEF-treated mice was significantly suppressed in the arthritic clinical score (p < 0.05). To investigate the alteration of cytokine levels, ELISA was used to measure blood samples. Levels of IL-1β and TNF-α were reduced in the transgenic MEF-treated group (p < 0.05). Abnormalities of the joints were examined by H&E staining. There were no signs of inflammation except for mild hyperplasia of the synovium in the transgenic MEF-treated group. The proliferation of CII-specific T cells was lower in the transgenic MEF-treated mice than in those in the other groups. The transfer of EC-SOD transgenic MEF has shown a therapeutic effect in CIA mice and this approach may be a safer and more effective form of therapy for rheumatoid arthritis.

Soluble Fas ligand inhibits angiogenesis in rheumatoid arthritis

The characteristics of rheumatoid arthritis (RA) pathology include the infiltration of inflammatory leukocytes, the proliferation of synovial cells, and the presence of extensive angiogenesis, referred to as rheumatoid pannus. Fas ligand is critical to the homeostatic regulation of the immune response, but its role in the angiogenic process of RA remains to be defined. In this study, we investigated whether soluble Fas ligand (sFasL) induces synoviocyte apoptosis and regulates angiogenesis of endothelial cells in RA. The levels of sFasL were elevated in the synovial fluids of RA patients when compared to those of osteoarthritis (OA) patients, and they correlated inversely with vascular endothelial growth factor₁₆₅ (VEGF₁₆₅) concentrations. sFasL, ranging from 10 to 100 ng/ml, induced the apoptosis of RA fibroblast-like synoviocytes (FLS) in vitro, and thereby decreased VEGF₁₆₅ production. In addition, sFasL inhibited VEGF₁₆₅-induced migration and chemotaxis of endothelial cells to basal levels in a manner independent of the Fas-mediated cell death. sFasL dose-dependently suppressed the VEGF₁₆₅-stimulated increase in pAkt expression in endothelial cells, which might be associated with its anti-migratory effect on endothelial cells. Moreover, sFasL strongly inhibited neovascularization in the Matrigel plug in vivo. Our data suggest that sFasL shows anti-angiogenic activity within RA joints not only by inducing apoptosis of VEGF₁₆₅-producing cells but also by blocking VEGF₁₆₅-induced migration of endothelial cells, independent of Fas-mediated apoptosis.

Calcineurin modulates the catabolic and anabolic activity of chondrocytes and participates in the progression of experimental osteoarthritis

OBJECTIVE

To determine whether intracellular calcineurin (Cn), a calcium-activated phosphatase, regulates the anabolic and catabolic activities of chondrocytes, and is a potential target in the treatment of osteoarthritis (OA).

METHODS

CnA expression was examined in cartilage tissue samples and cultured chondrocytes from OA patients, using immunohistochemistry and Western blot analysis, respectively. Concentrations of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases 1 (TIMP-1) in the culture supernatants were determined using enzyme-linked immunosorbent assay. Levels of nitric oxide (NO) and type II collagen (CII) were measured using the Griess reaction and Western blot analysis, respectively. In addition, the pathologic role of Cn was examined in an in vivo model in which experimental OA was induced in mice by injecting type VII collagenase into the knee joints.

RESULTS

CnA was highly expressed in the chondrocytes of lesional OA cartilage. Cyclosporin A (CSA), a Cn inhibitor, inhibited spontaneous and interleukin-1beta-stimulated production of NO, MMP-1, and MMP-3 in chondrocytes. However, CSA increased the levels of production of CII, TIMP-1, and transforming growth factor beta. Similar changes in MMP-1, NO, and CII expression levels in chondrocytes were observed after the targeted inhibition of Cn by overexpression of calcineurin binding protein 1, a natural Cn antagonist. Moreover, in the mouse model, animals treated with CSA showed a significant decrease in both the extent and the severity of cartilage damage, which were assessed macroscopically and microscopically, compared with vehicle-treated animals.

CONCLUSION

These results suggest that CnA is critically involved in the catabolic and anabolic activities of chondrocytes as well as in the progression of experimental OA. Targeted inhibition of CnA may be an effective treatment strategy for OA.

MLN51 and GM-CSF involvement in the proliferation of fibroblast-like synoviocytes in the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease of unclear etiology. This study was conducted to identify critical factors involved in the synovial hyperplasia in RA pathology. We applied cDNA microarray analysis to profile the gene expressions of RA fibroblast-like synoviocytes (FLSs) from patients with RA. We found that the MLN51 (metastatic lymph node 51) gene, identified in breast cancer, is remarkably upregulated in the hyperactive RA FLSs. However, growth-retarded RA FLSs passaged in vitro expressed small quantities of MLN51. MLN51 expression was significantly enhanced in the FLSs when the growth-retarded FLSs were treated with granulocyte – macrophage colony-stimulating factor (GM-CSF) or synovial fluid (SF). Anti-GM-CSF neutralizing antibody blocked the MLN51 expression even though the FLSs were cultured in the presence of SF. In contrast, GM-CSF in SFs existed at a significant level in the patients with RA (n = 6), in comparison with the other inflammatory cytokines, IL-1β and TNF-α. Most RA FLSs at passage 10 or more recovered from their growth retardation when cultured in the presence of SF. The SF-mediated growth recovery was markedly impaired by anti-GM-CSF antibody. Growth-retarded RA FLSs recovered their proliferative capacity after treatment with GM-CSF in a dose-dependent manner. However, MLN51 knock-down by siRNA completely blocked the GM-CSF/SF-mediated proliferation of RA FLSs. Taken together, our results imply that MLN51, induced by GM-CSF, is important in the proliferation of RA FLSs in the pathogenesis of RA.

Interaction of vascular endothelial growth factor 165 with neuropilin-1 protects rheumatoid synoviocytes from apoptotic death by regulating Bcl-2 expression and Bax translocation

Rheumatoid arthritis (RA) synoviocytes are resistant to apoptosis and exhibit a transformed phenotype, which might be caused by chronic exposure to genotoxic stimuli including reactive oxygen species and growth factors. In this study, we investigated the role of vascular endothelial growth factor165 (VEGF165), a potent angiogenic factor, and its receptor in the apoptosis of synoviocytes. We demonstrated here that neuropilin-1, rather than fms-like tyrosine kinase-1 and kinase insert domain-containing receptor, is the major VEGF165 receptor in the fibroblast-like synoviocytes. Neuropilin-1 was highly expressed in the lining layer, infiltrating leukocytes, and endothelial cells of rheumatoid synovium. The production of VEGF165, a ligand for neuropilin, was significantly higher in the RA synoviocytes than in the osteoarthritis synoviocytes. The ligation of recombinant VEGF165 to its receptor prevented the apoptosis of synoviocytes induced by serum starvation or sodium nitroprusside (SNP). VEGF165 rapidly triggered phospho-Akt and phospho-ERK activity and then induced Bcl-2 expression in the rheumatoid synoviocytes. The Akt or ERK inhibitor cancelled the protective effect of VEGF165 on SNP-induced synoviocyte apoptosis. Moreover, VEGF165 blocks SNP-induced Bcl-2 down-regulation as well as SNP-induced Bax translocation from the cytosol to the mitochondria. The down-regulation of the neuropilin-1 transcripts by short interfering RNA caused spontaneous synoviocyte apoptosis, which was associated with both the decrease in Bcl-2 expression and the increase in Bax translocation to mitochondria. Collectively, our data suggest that the interaction of VEGF165 with neuropilin-1 is crucial to the survival of rheumatoid synoviocytes and provide important implications for the abnormal growth of synoviocytes and therapeutic intervention in RA.

Serum Amyloid A Binding to Formyl Peptide Receptor-Like 1 Induces Synovial Hyperplasia and Angiogenesis

Serum amyloid A (SAA) is a major acute-phase reactant, and has been demonstrated to mediate proinflammatory cellular responses. Although SAA has been used as an indicator for a variety of inflammatory diseases, the role of SAA in synovial hyperplasia and proliferation of endothelial cells, a pathological hallmark of rheumatoid arthritis (RA), has yet to be elucidated. In this study, we have demonstrated that SAA promotes the proliferation of human fibroblast-like synoviocytes (FLS). In addition, SAA protects RA FLS against the apoptotic death induced by serum starvation, anti-Fas IgM, and sodium nitroprusside. The activity of SAA appears to be mediated by the formyl peptide receptor-like 1 (FPRL1) receptor, as it was mimicked by the WKYMVm peptide, a specific ligand for FPRL1, but completely abrogated by down-regulating the FPRL1 transcripts with short interfering RNA. The effect of SAA on FLS hyperplasia was shown to be caused by an increase in the levels of intracellular calcium, as well as the activation of ERK and Akt, which resulted in an elevation in the expression of cyclin D1 and Bcl-2. Moreover, SAA stimulated the proliferation, migration, and tube formation of endothelial cells in vitro, and enhanced the sprouting activity of endothelial cells ex vivo and neovascularization in vivo. These observations indicate that the binding of SAA to FPRL1 may contribute to the destruction of bone and cartilage via the promotion of synoviocyte hyperplasia and angiogenesis, thus providing a potential target for the control of RA.

Calcineurin is expressed and plays a critical role in inflammatory arthritis

Calcineurin is a calcium-activated phosphatase to mediate lymphocyte activation and neuron signaling, but its role in inflammatory arthritis remains largely unknown. In this study, we demonstrate that calcineurin was highly expressed in the lining layer, infiltrating leukocytes, and endothelial cells of rheumatoid synovium. The basal expression levels of calcineurin were higher in the cultured synoviocytes of rheumatoid arthritis patients than those of osteoarthritis patients. The calcineurin activity in the synoviocytes was increased by the stimulation with proinflammatory cytokines such as IL-1beta and TNF-alpha. Moreover, rheumatoid arthritis synoviocytes had an enlarged intracellular Ca(2+) store and showed a higher degree of [Ca(2+)](i) release for calcineurin activity than osteoarthritis synoviocytes when stimulated with either TNF-alpha or phorbol myristate acetate. IL-10, an anti-inflammatory cytokine, failed to increase the Ca(2+) and calcineurin activity. The targeted inhibition of calcineurin by the overexpression of calcineurin-binding protein 1, a natural calcineurin antagonist, inhibited the production of IL-6 and matrix metalloproteinase-2 by rheumatoid synoviocytes in a similar manner to the calcineurin inhibitor, cyclosporin A. Moreover, the abundant calcineurin expression was found in the invading pannus in the joints of mice with collagen-induced arthritis. In these mice, calcineurin activity in the cultured synovial and lymph node cells correlated well with the severity of arthritis, but which was suppressed by cyclosporin A treatment. Taken together, our data suggest that the abnormal activation of Ca(2+) and calcineurin in the synoviocytes may contribute to the pathogenesis of chronic arthritis and thus provide a potential target for controlling inflammatory arthritis.

Arginine-rich anti-vascular endothelial growth factor (anti-VEGF) hexapeptide inhibits collagen-induced arthritis and VEGF-stimulated productions of TNF-alpha and IL-6 by human monocytes

Vascular endothelial growth factor (VEGF) has been suggested to play a critical role in the pathogenesis of rheumatoid arthritis (RA). We previously identified a novel RRKRRR hexapeptide that blocked the interaction between VEGF and its receptor through the screening of peptide libraries. In this study, we investigated whether anti-VEGF peptide RRKRRR (dRK6) could suppress collagen-induced arthritis (CIA) and regulate the activation of mononuclear cells of RA patients. A s.c. injection of dRK6 resulted in a dose-dependent decrease in the severity and incidence of CIA and suppressed synovial infiltration of inflammatory cells in DBA/1 mice. In these mice, the T cell responses to type II collagen (CII) in lymph node cells and circulating IgG Abs to CII were also dose-dependently inhibited by the peptides. In addition, VEGF directly increased the production of TNF-alpha and IL-6 from human PBMC. Synovial fluid mononuclear cells of RA patients showed a greater response to VEGF stimulation than the PBMC of healthy controls. The major cell types responding to VEGF were monocytes. Moreover, anti-VEGF dRK6 inhibited the VEGF-induced production of TNF-alpha and IL-6 from synovial fluid mononuclear cells of RA patients and decreased serum IL-6 levels in CIA mice. In summary, we observed first that dRK6 suppressed the ongoing paw inflammation in mice and blocked the VEGF-induced production of proinflammatory cytokines. These data suggest that dRK6 may be an effective strategy in the treatment of RA, and could be applied to modulate various chronic VEGF-dependent inflammatory diseases.

Effect of annexin I on insulin secretion through surface binding sites in rat pancreatic islets

This study investigates the effect of extracellular annexin I (Anx I) on regulating insulin secretion in isolated rat pancreatic islets. Results show that Anx I stimulates insulin release in pancreatic islets regardless of the presence or absence of extracellular Ca2+. In particular, confocal microscopy shows that Anx I binds to the surface of islet cells in the absence of extracellular Ca2+. However, insulin secretion through Anx I significantly decreases in trypsin-treated islets. Likewise, there is minimal binding of Anx I to the surface of trypsin-treated islets. Anti-Anx I polyclonal antibody also inhibits the stimulating effect of Anx I on insulin secretion. These results indicate that Anx I is capable of binding to the cell surface receptor, in order to regulate the stimulation of insulin release in rat pancreatic islets.