Elevated expression of caspase-3 inhibitors, survivin and xIAP correlates with low levels of apoptosis in active rheumatoid synovium

E3 ubiquitin ligase gene BIRC3 modulates TNF-induced cell death pathways and promotes aberrant proliferation in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by synovitis, degradation of articular cartilage, and bone destruction. Fibroblast-like synoviocytes (FLS) play a central role in RA, producing a significant amount of inflammatory mediators such as tumor necrosis factor(TNF)-α and IL-6, which promote inflammatory responses within the joints. Moreover, FLS exhibit tumor-like behavior, including aggressive proliferation and enhanced anti-apoptotic capabilities, which collectively drive chronic inflammation and joint damage in RA. TNF is a major pro-inflammatory cytokine that mediates a series of signaling pathways through its receptor TNFR1, including NF-κB and MAPK pathways, which are crucial for inflammation and cell survival in RA. The abnormal proliferation and anti-apoptotic characteristics of FLS in RA may result from dysregulation in TNF-mediated cell death pathways such as apoptosis and necroptosis. Ubiquitination is a critical post-translational modification regulating these signaling pathways. E3 ubiquitin ligases, such as cIAP1/2, promote the ubiquitination and degradation of target proteins within the TNF receptor complex, modulating the signaling proteins. The high expression of the BIRC3 gene and its encoded protein, cIAP2, in RA regulates various cellular processes, including apoptosis, inflammatory signaling, immune response, MAPK signaling, and cell proliferation, thereby promoting FLS survival and inflammatory responses. Inhibiting BIRC3 expression can reduce the secretion of inflammatory cytokines by RA-FLS under both basal and inflammatory conditions and inhibit their proliferation. Although BIRC3 inhibitors show potential in RA treatment, their possible side effects must be carefully considered. Further research into the specific mechanisms of BIRC3, including its roles in cell signaling, apoptosis regulation, and immune evasion, is crucial for identifying new therapeutic targets and strategies.

Small molecule and big function: MicroRNA-mediated apoptosis in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune condition and chronic inflammatory disease, mostly affecting synovial joints. The complex pathogenesis of RA is supportive of high morbidity, disability, and mortality rates. Pathological changes a common characteristic in RA synovial tissue is attributed to the inadequacy of apoptotic pathways. In that regard, apoptotic pathways have been the center of attention in RA therapeutic approaches. As the regulators in the complex network of apoptosis, microRNAs (miRNAs) are found to be vital modulators in both intrinsic and extrinsic pathways through altering their regulatory genes. Indeed, miRNA, a member of the family of non-coding RNAs, are found to be an important player in not even apoptosis, but proliferation, gene expression, signaling pathways, and angiogenesis. Aberrant expression of miRNAs is implicated in attenuation and/or intensification of various apoptosis routes, resulting in culmination of human diseases including RA. Considering the need for more studies focused on the underlying mechanisms of RA in order to elevate the unsatisfactory clinical treatments, this study is aimed to delineate the importance of apoptosis in the pathophysiology of this disease. As well, this review is focused on the critical role of miRNAs in inducing or inhibiting apoptosis of RA-synovial fibroblasts and fibroblast-like synoviocytes and how this mechanism can be exerted for therapeutic purposes for RA.

XAF1 promotes osteoclast apoptosis by antagonizing the XIAP-caspase axis

Background

Over-activated osteoclast (OC) is a major cause of diseases related to bone loss and bone metabolism. Both bone resorption inhibition and apoptosis induction of osteoclast are crucial in treating these diseases. X-linked inhibitor of apoptosis protein (XIAP)-associated factor 1 (XAF1) is an important interferon-stimulated and apoptotic gene. However, how XAF1 regulates bone formation and remodeling is unknown.

Methods

We generate global and chimeric Xaf1 knockout mouse models and utilize these models to explore the function and mechanism of XAF1 in regulating bone formation and remodeling in vivo and in vitro.

Results

We show that XAF1 depletion enhances osteoclast generation in vitro. XAF1 knockout increases osteoclast number and bone resorption, thereby exacerbating bone loss in both OVX and osteolysis models. Activation of XAF1 with BV6 (a potent XIAP inhibitor) suppresses osteoclast formation. Mechanistically, XAF1 deletion decreases osteoclast apoptosis by facilitating the interaction between XIAP and caspase-3/7.

Conclusions

Our data illustrates an essential role of XAF1 in controlling osteoclastogenesis in both osteoporosis and osteolysis mouse models and highlights its underlying mechanism, indicating a potential role in clinical treatment.The translational potential of this article: The translation potential of this article is that we first indicated that osteoclast apoptosis induced by XAF1 contribute to the progression of osteoporosis and osteolysis, which provides a novel strategy in the prevention of osteoporosis and osteolysis.

Mitochondrial functioning in Rheumatoid arthritis modulated by estrogen: Evidence-based insight into the sex-based influence on mitochondria and disease

Alteration of immune response and synovium microvasculature in Rheumatoid arthritis (RA) progression has been suggested to be associated with mitochondrial functioning. Mitochondria, with maternally inherited DNA, exhibit differential response to the female hormone estrogen. Various epidemiological evidence has also shown the prominence of RA in the female population, depicting the role of estrogen in modulating the pathogenesis of RA. As estrogen regulates the expression of differential proteins and associated signaling pathways of RA, its influence on mitochondrial functioning seems evident. Thus, in this review, the studies related to mitochondria and their relation with estrogen and Rheumatoid arthritis were retrieved. We analyzed the different mitochondrial activities that are altered in RA and the possibility of their estrogenic control. The study expands to in silico analysis, revealing the differential mitochondrial proteins expressed in RA and examining these proteins as potential estrogenic targets. It was found that ALDH2, CASP3, and SOD2 are the major mitochondrial proteins involved in RA progression and are also potent estradiol targets. The analysis establishes the role of mitochondrial proteins in RA progression, which were found to be direct or indirect targets of estrogen, depicting its potential for regulating mitochondrial functions in RA.

Itaconate attenuates osteoarthritis by inhibiting STING/NF-κB axis in chondrocytes and promoting M2 polarization in macrophages

Osteoarthritis (OA) is a progressive joint disease characterized by the degradation and destruction of articular cartilage, which is involved with pathological microenvironmental alterations induced by damaged chondrocytes and inflammatory macrophages. However, the current therapies cannot effectively alleviate the progression of OA. Our previous studies have shown that the pathological process of OA progression is accompanied by DNA damage, and inhibition of STING, a key molecule in DNA damage, may become a potential method for the treatment of OA. Itaconate, a metabolite highly expressed in macrophages under inflammatory conditions, has shown a wide range of anti-inflammatory effects, but its effect on OA and its underlying mechanism has not yet been studied. In this study, we found that exogenous supplementation of itaconate can activate Nrf2, and accordingly inhibit the STING-dependent NF-κB pathway, thereby alleviating the inflammation, ECM degeneration and senescence of chondrocytes stimulated by IL-1β. In addition, itaconate can regulate the polarization of RAW264.7 macrophages, further reducing the apoptosis of chondrocytes. In vivo, intra-articular injection of itaconate reduces the degradation of cartilage and inflammation of synovial membrane in the mouse OA model. In conclusion, the present work suggests that exogenous supplementation of itaconate inhibits the inflammation, senescence and ECM degeneration of chondrocytes through the Nrf2/STING/NF-κB axis and regulates the polarization of synovial macrophages, thereby ameliorating the progression of OA, which supports that itaconate as a potential drug for the treatment of OA.

Disease-Modifying Anti-rheumatic Drug Prescription Baihu-Guizhi Decoction Attenuates Rheumatoid Arthritis via Suppressing Toll-Like Receptor 4-mediated NLRP3 Inflammasome Activation

As a traditional Chinese medicine-originated disease-modifying anti-rheumatic drug prescription, Baihu-Guizhi decoction (BHGZD) is extensively used for the treatment of rheumatoid arthritis (RA) with a satisfying therapeutic efficacy. Mechanically, our previous data indicated that BHGZD may ameliorate RA partially by restoring the balance of the “inflammation-immune” system through regulating the TLR4-c-Fos-IL2-TNF-alpha axis. Toll-like receptor 4 (TLR4) has been revealed to be involved in the activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome complex. Thus, the aim of the current study was to determine the regulatory effects of BHGZD on the TLR4–mediated inflammasome activation during RA progression based on the modified adjuvant-induced arthritis model (AIA-M) and the lipopolysaccharide/adenosine triphosphate (LPS/ATP)–induced pyroptosis cellular models. As a result, oral administration of BHGZD exhibited prominent improvement in the disease severity of AIA-M rats, such as reducing the redness and swelling of joints, arthritis incidence, arthritic scores, and diameter of the limb and increasing pain thresholds. In line with the in vivo findings, BHGZD treatment effectively inhibited the LPS/ATP–induced pyroptosis of both Raw264.7 macrophage and MH7A cells in vitro by reducing pyroptotic cell death morphology (swollen cells) and decreasing propidium iodide–positive and terminal deoxynucleotidyl transferase–mediated dUTP-fluorescein nick end labeling (TUNEL)–positive cells. Notably, the increased expression levels of TLR4, NLRP3, interleukin 1β, and interleukin 18 proteins and the elevated activities of caspase-1 and lactic dehydrogenase in in vivo and in vitro disease models were markedly reversed by the treatment with BHGZD. In conclusion, the above findings proved the immunomodulatory and anti-inflammatory activities of BHGZD, especially in pyroptosis, which may be attributed to the activation of TLR4–mediated NLRP3 inflammasome signaling.

Survivin as a biological biomarker for diagnosis and therapy

Introduction: Survivin (SVN) is a member of the inhibitor of apoptosis (IAP) protein family that promotes cellular proliferation and inhibits apoptosis. Overexpression of SVN is associated with autoimmune disease, hyperplasia, and tumors and can be used as a biomarker in these diseases. SVN is widely recognized as a tumor-associated antigen (TAA) and has become an important target for cancer diagnosis and treatment.Areas covered: We reviewed SVN research progress from the PubMed and clinical trials focused on SVN from https://clinicaltrials.gov since 2000 and anticipate future developments in the field. The trials reviewed cover various modalities including diagnostics for early detection and disease progression, small molecule inhibitors of the SVN pathway and immunotherapy targeting SVN epitopes.Expert opinion: The most promising developments involve anti-SVN immunotherapy, with several therapeutic SVN vaccines under evaluation in phase I/II trials. SVN is an important new immune-oncology target that expands the repertoire of individualized combination treatments for cancer.

Nonsurgical periodontal therapy decreases the severity of rheumatoid arthritis and the plasmatic and salivary levels of RANKL and Survivin: a short-term clinical study

AIM

To investigate the influence of nonsurgical periodontal treatment (NSPT) on clinical periodontal status, rheumatoid arthritis (RA) activity, and plasmatic and salivary levels of biomarkers through a controlled clinical trial on individuals with RA and periodontitis (PE).

METHODS

Sixty-six individuals from a convenience sample were considered eligible and consecutively allocated in 3 groups: (1) individuals without PE and RA (-PE-RA, n = 19); (2) individuals without PE and with RA (-PE+RA, n = 23), and (3) individuals with PE and RA (+PE+RA, n = 24). Full-mouth periodontal clinical examinations, Disease Activity Score (DAS-28) evaluations, and analysis in plasma and saliva of RANKL, OPG, RANKL/OPG, and Survivin were performed at baseline (T1) and 45 days after NSPT (T2).

RESULTS

NSPT in the +PE+RA group was very effective to improve periodontal condition. At T2, significant reductions in DAS-28 were observed in +PE+RA (p = 0.011). Significantly higher levels of Survivin and RANKL were observed in saliva and plasma from RA individuals (with and without PE) compared to controls. Additionally, Survivin e RANKL demonstrated positive correlations with DAS-28 and an expressively significant reduction in +PE+RA at T2 (p < 0.001).

CONCLUSIONS

NSPT was effective on improving both the periodontal and the RA clinical status and reducing the concentration of Survivin and RANKL in saliva and plasma.

PRACTICAL IMPLICATIONS

Nonsurgical periodontal treatment was effective on reducing the concentration of Survivin and RANKL and on improving both the periodontal and the RA clinical status of affected individuals.

TRIAL REGISTRATION

Brazilian Registry of Clinical Trials (ReBEC) protocol #RBR-8g2bc8 ( http://www.ensaiosclinicos.gov.br/rg/RBR-8g2bc8/ ).

Targeting RIP Kinases in Chronic Inflammatory Disease

Chronic inflammatory disorders are characterised by aberrant and exaggerated inflammatory immune cell responses. Modes of extrinsic cell death, apoptosis and necroptosis, have now been shown to be potent drivers of deleterious inflammation, and mutations in core repressors of these pathways underlie many autoinflammatory disorders. The receptor-interacting protein (RIP) kinases, RIPK1 and RIPK3, are integral players in extrinsic cell death signalling by regulating the production of pro-inflammatory cytokines, such as tumour necrosis factor (TNF), and coordinating the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome, which underpin pathological inflammation in numerous chronic inflammatory disorders. In this review, we firstly give an overview of the inflammatory cell death pathways regulated by RIPK1 and RIPK3. We then discuss how dysregulated signalling along these pathways can contribute to chronic inflammatory disorders of the joints, skin, and gastrointestinal tract, and discuss the emerging evidence for targeting these RIP kinases in the clinic.

Escape from X chromosome inactivation and female bias of autoimmune diseases

Generally, autoimmune diseases are more prevalent in females than males. Various predisposing factors, including female sex hormones, X chromosome genes, and the microbiome have been implicated in the female bias of autoimmune diseases. During embryogenesis, one of the X chromosomes in the females is transcriptionally inactivated, in a process called X chromosome inactivation (XCI). This equalizes the impact of two X chromosomes in the females. However, some genes escape from XCI, providing a basis for the dual expression dosage of the given gene in the females. In the present review, the contribution of the escape genes to the female bias of autoimmune diseases will be discussed.

miR-431-5p regulates cell proliferation and apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis by targeting XIAP

BACKGROUND

miR-431-5p is dysregulated in various cancers and plays an important function in the development of cancer. However, its role in fibroblast-like synoviocytes (FLSs) in patients with rheumatoid arthritis (RA) remains to be understood.

METHODS

Quantitative real-time polymerase chain reaction was used to detect the relative expression of miR-431-5p in synovial tissues and FLSs. Cell proliferation assays helped examine RA FLS proliferation. Flow cytometry was performed to determine apoptosis and cell cycle progression in RA FLSs. We used dual-luciferase assays to determine the correlation between miR-431-5p and its putative target, X-linked inhibitor of apoptosis (XIAP). Quantitative real-time PCR and western blotting were used to measure XIAP levels in synovial tissues and transfected RA FLSs.

RESULTS

miR-431-5p was downregulated in synovial tissues and FLSs of patients with RA. Upregulation of miR-431-5p prohibited cell proliferation and the G0/G1-to-S phase transition but promoted apoptosis in RA FLSs, while miR-431-5p inhibition showed the opposite results. miR-431-5p directly targeted XIAP in RA FLSs and reversely correlated with XIAP levels in synovial tissues. Notably, XIAP silencing partially restored the effects of miR-431-5p inhibition in RA FLSs.

CONCLUSION

miR-431-5p regulates cell proliferation, apoptosis, and cell cycle of RA FLSs by targeting XIAP, suggesting its potential in the treatment of RA.

Novel gene Merlot inhibits differentiation and promotes apoptosis of osteoclasts

Extended osteoclast longevity is deeply involved in the pathogenesis of bone diseases such as osteoporosis and rheumatoid arthritis, though the mechanisms that determine osteoclast lifespan are not fully understood. Here we present findings indicating that the newly characterized gene Merlot, which encodes a highly conserved yet uncharacterized protein in vertebrates, is an important regulator for termination of osteoclastogenesis via induction of apoptosis. Mice lacking Merlot exhibited low bone mass due to increased osteoclast and bone resorption. Furthermore, osteoclast precursors overexpressing Merlot failed to differentiate into mature osteoclasts, while Merlot deficiency led to hyper-nucleation and prolonged survival of osteoclasts, accompanied by sustained nuclear localization of nuclear factor of activated T cell c1 (NFATc1) and derepression of glycogen synthase kinase-3β (GSK3β) activity, known to regulate NFATc1 activity and induce apoptosis. Merlot-deficient osteoclasts were found to represent suppression of caspase-3-mediated apoptosis and Merlot deficiency caused transcriptional downregulation of a proapoptotic cascade, including Bax, Bak, Noxa, and Bim, as well as the executor caspase members Casp-3, -6, and -7, and upregulation of anti-apoptotic Bcl2, resulting in a low apoptotic threshold. Thus, Merlot regulates osteoclast lifespan by inhibition of differentiation and simultaneous induction of apoptosis via regulation of the NFATc1-GSK3β axis.

Cell death in chronic inflammation: breaking the cycle to treat rheumatic disease

Cell death is a vital process that occurs in billions of cells in the human body every day. This process helps maintain tissue homeostasis, supports recovery from acute injury, deals with infection and regulates immunity. Cell death can also provoke inflammatory responses, and lytic forms of cell death can incite inflammation. Loss of cell membrane integrity leads to the uncontrolled release of damage-associated molecular patterns (DAMPs), which are normally sequestered inside cells. Such DAMPs increase local inflammation and promote the production of cytokines and chemokines that modulate the innate immune response. Cell death can be both a consequence and a cause of inflammation, which can be difficult to distinguish in chronic diseases. Despite this caveat, excessive or poorly regulated cell death is increasingly recognized as a contributor to chronic inflammation in rheumatic disease and other inflammatory conditions. Drugs that inhibit cell death could, therefore, be used therapeutically for the treatment of these diseases, and programmes to develop such inhibitors are already underway. In this Review, we outline pathways for the major cell death programmes (apoptosis, necroptosis, pyroptosis and NETosis) and their potential roles in chronic inflammation. We also discuss current and developing therapies that target the cell death machinery.

Correlation of synovial caspase-3 concentration and the photodynamic effectiveness in osteoarthritis treatment

BACKGROUND

The present study focuses on investigation of Intra-articular PDT mechanisms for OA treatment. Also, a search for determination of the most effective dose of chlorin e6 (Ce6) for anti-inflammatory PDT of OA was carried out.

METHODS

The study was carried out on laboratory animals (11 Chinchilla rabbits, 1 year, 2.5 kg) with a gonarthritis model of post-traumatic OA. According to the instructions for using Photoditazin (Ce6 based PS) for PDT of human oncological and non-oncological diseases, the recommended dose is 0.7-1.2 mg/kg. For studies on rabbits, taking into account the conversion coefficient (3.2), the PS doses of 2.4, 3.2 and 6.4 mg/kg were selected. Fluorescence spectra were measured intra-articular before and after PDT using spectrometer with fiber-optic probe. The intrajoint PDT was carried out using a laser (662 ± 10 nm) and a fiber-optic catheter with a cylindrical diffuser inside a sapphire needle for a uniform distribution of the laser radiation. The immunohistochemical study was carried out by staining the samples with caspase-3.

RESULTS

Histological and immunohistochemical analysis showed that the best PS dose for intravenous administration for PDT of rabbit gonarthritis is 3.2 mg/kg. The PS concentration directly in the synovial tissue was 0.5 mg/kg, and this was enough to achieve the most positive results to reduce the caspase-3 level.

CONCLUSION

The caspase-3 level correlates well with other signs of inflammation in the synovial membrane (edema, etc.). Therefore, to assess the PDT effectiveness in the treatment of gonarthritis accompanied by synovitis, it is sufficient to analyze only for caspase-3. The efficacy of PDT with Ce6 showed that 3.2 mg/kg PS dose (1 mg/kg for a human) is the most effective.

RETRACTED: Human bone mesenchymal stem cells-derived exosomes overexpressing microRNA-26a-5p alleviate osteoarthritis via down-regulation of PTGS2

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figures 2E, 3D and F, 4B, E+G, 5D+I, and 6D+F, which appear to have a similar phenotype as contained in many other publications, detailed here: https://pubpeer.com/publications/73C0A79F5EDF9ECC9818CE2D9B2A09; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. The provenance of the flow cytometry data in Figure 5A was also questioned, as it appeared to have histograms that were hand drawn. The journal requested the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Effect of erythropoietin on Fas/FasL expression in brain tissues of neonatal rats with hypoxic-ischemic brain damage

Hypoxic-ischemic brain damage (HIBD) occurs due to intrauterine hypoxia ischemia influencing the energy supply for fetal brain cells, which affects the metabolism of the brain to make the brain suffer a severe damage. Erythropoietin (EPO), which regulates hemacytopoiesis, is a kind of cytokine. EPO is sensitive to hypoxia ischemia. In this study, we aimed to investigate the effect of EPO on the expression of Fas/FasL in brain tissues of neonatal rats with HIBD. Neonatal rats were assigned randomly to sham, HIBD, and EPO groups. Five time points for observation were 6, 12, 24, 48, and 72 h after the HIBD rat model had been established, respectively. In the HIBD group, Fas/FasL expression began to rise at 6 h, reached the peak at 12–24 h, and dropped from 24 h. In the EPO group, the expression of Fas/FasL was lower than those in HIBD group at 12, 24, and 48 h (P<0.05). Our findings suggest that EPO may reduce cell apoptosis after hypoxic-ischemic damage through reduction of the expression of Fas and FasL, and that optimal therapeutic time window is 6–24 h after HIBD.

TNF-Related Apoptosis-Inducing Ligand Receptor 1 in Patients With Ankylosing Spondylitis

OBJECTIVES

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) belongs to the tumor necrosis factor (TNF) superfamily and is reported to play a role in autoimmune diseases. In this study, we aimed to measure serum TRAIL receptor 1 (TRAIL-R1) concentration and assess any phenotypic relationship in patients with ankylosing spondylitis (AS).

METHODS

Fifty-three patients with AS were recruited from August 2014 to December 2014 cross-sectionally. Fifty-three sex- and age-matched healthy controls were also recruited. Serum TRAIL-R1 concentrations were measured using an enzyme-linked immunosorbent assay. The association between serum TRAIL-R1, TNF-α, disease activity indices, markers of systemic inflammation, and clinical features were evaluated.

RESULTS

Serum TRAIL-R1 and TNF-α levels were increased in patients with AS compared with healthy controls (4.5 ± 2.3 vs 3.5 ± 2.3 pg/mL, p = 0.036; 3.8 [1.6-7.7] vs 2.0 [0.21-5.7] pg/mL, p = 0.048, respectively). Serum TRAIL-R1 displayed a medium positive correlation with serum TNF-α concentrations (r = 0.412; p = 0.002). Serum TRAIL-R1 concentration was higher in human leucocyte antigen (HLA)-B27-positive patients compared with non-HLA-B27 patients (5.5 ± 2.2 vs 3.1 ± 1.6 pg/mL, p < 0.001). No relationship was found between serum TRAIL-R1 concentration and disease activity scores.

CONCLUSIONS

This study confirms that serum TRAIL-R1 levels are higher in AS patients than healthy controls. The persistence of significantly elevated serum TRAIL-R1 levels, even in patients with low disease activity or after excluding biologic treatment, and the association with HLA-B27 positivity, warrants further investigation due to the unclear role of TRAIL-R1 in the pathophysiology of AS.

MicroRNA-21-5p are involved in apoptosis and invasion of fibroblast-like synoviocytes through PTEN/PI3K/AKT signal

The function of microRNA-21-5p (miR-21) in fibroblast-like synoviocytes in RA was still unclear. In our study, we used tumor necrosis factor alpha (TNFα) (10 ng/ml) to mimic RA-FLSs and we found that normal FLS stimulated with TNFα caused the increasing expression of miR-21, a disintegrin and metalloproteinase with thrombospondin motifs 5 and matrix metalloproteinase 3, which were in accord with RA-FLSs changes. Our data showed that miR-21 overexpression significantly increased cell invasion and decreased apoptosis in FLSs. Knockdown of miR-21 in FLSs causes the opposite result. However, miR-21 may not affect the proliferation of FLSs. Meanwhile, we showed that miR-21 activated the PI3K/AKT signaling pathway to participate in RA by inhibiting PTEN expression. Taken together, our results suggested that miR-21 may play a positive role in RA and may be a promising new therapeutic target for RA.

Survivin Measurement improves Clinical Prediction of Transition From Arthralgia to RA-Biomarkers to Improve Clinical Sensitivity of Transition From Arthralgia to RA

Background: Arthralgia often predates development of rheumatoid arthritis (RA). A set of joint symptoms commonly found in patients during their transition from arthralgia to RA, has been recently proposed.

Aim: To combine clinical and serological markers and to improve recognition of imminent rheumatoid arthritis (RA) among patients with arthralgia.

Methods: The total of 1,743 first-visit patients attending the rheumatology ward in Gothenburg for joint symptoms were identified during 12 consecutive months. Among those, 63 patients were classified as RA, 73 had undifferentiated arthritis and 180 had unexplained arthralgia. New RA cases, which prospectively developed during 48 months, comprised the preclinical (pre) RA group. The joint symptoms of the first-visit were analyzed aiming to distinguish patients with arthralgia and arthritis, and patients with pre-RA, who later developed the disease. The receiver operating characteristics curves were constructed. In the model, symptoms with the odds ratio >2.0 between the arthralgia and pre-RA were combined with information about RA-specific antibodies, C-reactive protein (CRP), and survivin in serum.

Results: The proposed set of clinical symptoms distinguished the arthralgia patients from RA and pre-RA. Presence of survivin in serum showed strong association with clinical joint symptoms in arthralgia. A combination of symptoms in several small joint areas, increasing number of joints with symptoms, and patient's experience of swelling in small hand joints at the first visit identified pre-RA cases with 93% specificity. Grouping those symptoms with information about survivin, RA-specific antibodies, and CRP (or gender) in the final algorithm achieved 91% specificity and 55.2% of positive prediction for transition from arthralgia to RA.

Conclusion: Clinical and serological parameters in combination aid recognition of imminent RA among arthralgia patients with appropriate sensitivity.

RETRACTED: GZMB gene silencing confers protection against synovial tissue hyperplasia and articular cartilage tissue injury in rheumatoid arthritis through the MAPK signaling pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. An Expression of Concern for this article was previously published while an investigation was conducted (see related editorial: https://doi.org/10.1016/j.biopha.2022.113812). This retraction notice supersedes the Expression of Concern published earlier. Concern was raised about the reliability of the Western blot data in Figure 7C, which appear to contain a similar phenotype to those found in other publications, as detailed here: https://pubpeer.com/publications/7DD2DDC979F8CE2B00555332B01F81; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. The journal requested the corresponding author comment on these concerns and provide the associated raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Higher incidence of sperm granuloma in the epididymis of C57BL/6N mice

C57BL/6N mice are inbred strains widely used in biomedical research. Hence, a large amount of basic data has been accumulated. However, in the field of histopathology, spontaneous data for relatively younger mice that are used more frequently are not yet abundant, in contrast to data for older mice and their neoplastic lesions. To acquire the essential background data required by various research and toxicological assessments, 120 mice of the C57BL/6N strain (10 and 13 weeks of age) were collected from two institutions (From Korea and Japan) and subjected to histopathological analyses of the major organs (liver, spleen, kidney, thymus, heart, testis, epididymis). The results showed significantly higher incidence of sperm granulomas in the epididymides (10-56%) of these mice, compared with that in other strains or species of lab animals. Upon closer inspection, oligospermia/clear cell hyperplasia, cellular debris, and tubular vacuolation were also observed in the epididymides with sperm granulomas. Moreover, diseased organs were significantly heavier than healthy ones. Immunohistochemical staining showed a significant increase in the chromatic figures of cysteine-dependent aspartate-directed proteases-3 (caspase-3) and cleaved-poly(ADP-ribose) polymerase (c-PARP), and damages to the tubule due to spontaneous apoptosis, which may have led to the sperms leaking out of the tubule, causing the granuloma. To conclude, spontaneous sperm granuloma can occur in 10- and 13-week-old C57BL/6N mice and may thus affect the results of various studies using these mice. Therefore, sperm granuloma in epididymis needs to be carefully considered as an important factor when design the study using C57BL/6N.

Anti-interleukin-6 signalling therapy rebalances the disrupted cytokine production of B cells from patients with active rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with abnormal B cell-functions implicating antibody-dependent and -independent mechanisms. B cells have emerged as important cytokine-producing cells, and cytokines are well-known drivers of RA pathogenesis. To identify novel cytokine-mediated B-cell functions in RA, we comprehensively analysed the capacity of B cells from RA patients with an inadequate response to disease modifying anti-rheumatic drugs to produce cytokines in comparison with healthy donors (HD). RA B cells displayed a constitutively higher production of the pathogenic factors interleukin (IL)-8 and Gro-α, while their production of several cytokines upon activation via the B cell receptor for antigen (BCR) was broadly suppressed, including a loss of the expression of the protective factor TRAIL, compared to HD B cells. These defects were partly erased after treatment with the IL-6-signalling inhibitor tocilizumab, indicating that abnormal IL-6 signalling contributed to these abnormalities. Noteworthy, the clinical response of individual patients to tocilizumab therapy could be predicted using the amounts of MIP-1β and β-NGF produced by these patients' B cells before treatment. Taken together, our study highlights hitherto unknown abnormal B-cell functions in RA patients, which are related to the unbalanced cytokine network, and are potentially relevant for RA pathogenesis and treatment.

Survivin in autoimmune diseases

Survivin is a protein functionally important for cell division, apoptosis, and possibly, for micro-RNA biogenesis. It is an established marker of malignant cell transformation. In non-malignant conditions, the unique properties of survivin make it indispensable for homeostasis of the immune system. Indeed, it is required for the innate and adaptive immune responses, controlling differentiation and maintenance of CD4⁺ and CD8⁺ memory T-cells, and in B cell maturation. Recently, survivin has emerged as an important player in the pathogenesis of autoimmune diseases. Under the conditions of unreserved inflammation, survivin enhances antigen presentation, maintains persistence of autoreactive cells, and supports production of autoantibodies. In this context, survivin takes its place as a diagnostic and prognostic marker in rheumatoid arthritis, psoriasis, systemic sclerosis and pulmonary arterial hypertension, neuropathology and multiple sclerosis, inflammatory bowel diseases and oral lichen planus. In this review, we summarise the knowledge about non-malignant properties of survivin and focus on its engagement in cellular and molecular pathology of autoimmune diseases. The review highlights utility of survivin measures for clinical applications. It provides rational for the survivin inhibiting strategies and presents results of recent reports on survivin inhibition in modern therapies of cancers and autoimmune diseases.

Negative Regulators of JAK/STAT Signaling in Rheumatoid Arthritis and Osteoarthritis

Elevated levels of pro-inflammatory cytokines are generally thought to be responsible for driving the progression of synovial joint inflammation in rheumatoid arthritis (RA) and osteoarthritis (OA). These cytokines activate several signal transduction pathways, including the Janus kinase/Signal Transducers and Activators of Transcription (JAK/STAT), Stress-Activated/Mitogen-Activated Protein Kinase (SAPK/MAPK) and phosphatidylinositol-3-kinase/Akt/mechanistic target of rapamycin (PI3K/Akt/mTOR) pathways which regulate numerous cellular responses. However, cytokine gene expression, matrix metalloproteinase gene expression and aberrant immune cell and synoviocyte survival via reduced apoptosis are most critical in the context of inflammation characteristic of RA and OA. Negative regulation of JAK/STAT signaling is controlled by Suppressor of Cytokine Signaling (SOCS) proteins. SOCS is produced at lower levels in RA and OA. In addition, gaining further insight into the role played in RA and OA pathology by the inhibitors of the apoptosis protein family, cellular inhibitor of apoptosis protein-1, -2 (c-IAP1, c-IAP2), X (cross)-linked inhibitor of apoptosis protein (XIAP), protein inhibitor of activated STAT (PIAS), and survivin (human) as well as SOCS appears to be a worthy endeavor going forward.

Survivin co-ordinates formation of follicular T-cells acting in synergy with Bcl-6

Follicular T helper (Tfh) cells are recognized by the expression of CXCR5 and the transcriptional regulator Bcl-6. Tfh cells control B cell maturation and antibody production, and if deregulated, may lead to autoimmunity. Here, we study the role of the proto-oncogene survivin in the formation of Tfh cells. We show that blood Tfh cells of patients with the autoimmune condition rheumatoid arthritis, have intracellular expression of survivin. Survivin was co-localized with Bcl-6 in the nuclei of CXCR5⁺CD4 lymphocytes and was immunoprecipitated with the Bcl-6 responsive element of the target genes. Inhibition of survivin in arthritic mice led to the reduction of CXCR5⁺ Tfh cells and to low production of autoantibodies. Exposure to survivin activated STAT3 and induced enrichment of PD-1⁺Bcl-6⁺ subset within Tfh cells. Collectively, our study demonstrates that survivin belongs to the Tfh cell phenotype and ensures their optimal function by regulating transcriptional activity of Bcl-6.

CTGF promotes articular damage by increased proliferation of fibroblast-like synoviocytes in rheumatoid arthritis

OBJECTIVES

Fibroblast-like synoviocytes (FLS) are a major component of the hyperplastic synovial pannus, which aggressively invades cartilage and bone during the course of rheumatoid arthritis (RA). Connective tissue growth factor (CTGF or CCN2) is a product of a growth factor-inducible immediate early gene and is involved in cell adhesion, proliferation, and differentiation. However, the role that CTGF plays in FLS proliferation has remained undetermined. The aim of this study was to identify the role of CTGF in regulating the proliferation of FLS derived from patients with RA.

METHOD

CTGF levels in serum and synovial fluid (SF) were determined by enzyme-linked immunosorbent assay (ELISA). Expression of CTGF in FLS was determined using reverse transcription polymerase chain reaction (RT-PCR). FLS proliferation stimulated by CTGF was measured by thymidine incorporation. The influence of CTGF small interfering RNA (siRNA) on FLS apoptosis was detected by flow cytometry.

RESULTS

CTGF was overexpressed in serum and SF samples from RA patients compared with samples from normal controls. Elevated levels of CTGF in RA SF promoted the proliferation of FLS. Furthermore, in samples from RA patients, CTGF was found to protect FLS from apoptosis and to sustain the expression of survivin in FLS. The expression of CTGF in FLS can be up-regulated by tumour necrosis factor (TNF)-α.

CONCLUSIONS

Our findings indicate that CTGF plays a crucial role in the proliferation of FLS in RA and probably contributes to synovial lining cell hyperplasia and eventually to joint destruction in patients with RA.

The X-Linked Inhibitor of Apoptosis Protein Inhibitor Embelin Suppresses Inflammation and Bone Erosion in Collagen Antibody Induced Arthritis Mice

Objective. To investigate the effect of Embelin, an inhibitor of X-Linked Inhibitor of Apoptosis Protein (XIAP), on inflammation and bone erosion in a collagen antibody induced arthritis (CAIA) in mice. Methods. Four groups of mice (n = 6 per group) were allocated: CAIA untreated mice, CAIA treated with Prednisolone (10 mg/kg/day), CAIA treated with low dose Embelin (30 mg/kg/day), and CAIA treated with high dose Embelin (50 mg/kg/day). Joint inflammation was evaluated using clinical paw score and histological assessments. Bone erosion was assessed using micro-CT, tartrate resistant acid phosphatase (TRAP) staining, and serum carboxy-terminal collagen crosslinks (CTX-1) ELISA. Immunohistochemistry was used to detect XIAP protein. TUNEL was performed to identify apoptotic cells. Results. Low dose, but not high dose Embelin, suppressed inflammation as reflected by lower paw scores (P < 0.05) and lower histological scores for inflammation. Low dose Embelin reduced serum CTX-1 (P < 0.05) and demonstrated lower histological score and TRAP counting, and slightly higher bone volume as compared to CAIA untreated mice. XIAP expression was not reduced but TUNEL positive cells were more abundant in Embelin treated CAIA mice. Conclusion. Low dose Embelin suppressed inflammation and serum CTX-1 in CAIA mice, indicating a potential use for Embelin to treat pathological bone loss.

Suppressed diversity of survivin splicing in active rheumatoid arthritis

Introduction

Alternative splicing distinguishes normal and pathologic cells. High levels of oncoprotein survivin recognise patients with severe rheumatoid arthritis (RA). Here, we assess clinical relevance of alternative splicing of survivin in leukocytes of peripheral blood (PBMC) and bone marrow (BM) in RA patients.

Method

Transcription of survivin wild-type (survivin-WT), survivin-2B and survivin-ΔEx3 was measured in 67 randomly selected RA patients and in 23 patients before and after B cell depletion with rituximab. Analysis was done in relation to disease activity, anti-rheumatic treatment and serum levels of rheumatoid factor (RF) and survivin.

Results

Survivin-WT was the dominant splice variant equally expressed in T and B cells, while survivin-2B and survivin-ΔEx3 were higher in B cells. High disease activity (DAS28>5.1) was associated with an excess of survivin-WT and low ratios between survivin-2B/WT (p=0.035) and survivin-ΔEx3/WT in PBMC. Depletion of B cells by rituximab caused a decrease in survivin-WT (p=0.005) in PBMC, increasing the ratio between survivin-2B/WT (p=0.009) and survivin-ΔEx3/WT (p=0.001) in BM. This increase in survivin-2B/WT was associated with reduction in CD19+ BM cells (r=0.929, p=0.007), RF (IgM, r=0.857, p=0.024; IgA, r=0.739, p=0.021), and DAS28 (0.636, p=0.054). The increase in survivin-ΔEx3 in BM was associated with a reduction of CD19+ BM cells (r=0.714, p=0.058) and DAS28 (r=0.648, p=0.049), while survivin-ΔEx3/WT was associated with RF (IgG, r=0.882, p=0.016).

Conclusion

This study demonstrates that the suppressed diversity of survivin splicing in leukocytes may attribute to adverse self-recognition in RA. Depletion of autoantibody producing B cells improves the balance of survivin splicing.

The proto-oncogene survivin splice variant 2B is induced by PDGF and leads to cell proliferation in rheumatoid arthritis fibroblast-like synoviocytes

Survivin is an independent prognostic factor for joint destruction in rheumatoid arthritis (RA). However, the expression and function of survivin in RA synoviocytes remain unclear. We certified the expression of survivin in RA synovial tissues and performed the experiment using RA fibroblast-like synoviocytes (RA-FLS) treated with siRNA. As a result, the expression levels of wild type (WT) survivin and the 2B splice variants in RA synovial tissues were higher than those in osteoarthritis tissue samples, and, these variants were highly expressed in RA-FLS. The expression levels of survivin-WT and -2B in the RA-FLS were upregulated by PDGF. Treatment with siRNA against survivin-2B led to decreased viability of PDGF-treated RA-FLS due to cell cycle suppression and apoptosis promotion, while the siRNA against all survivin isoforms did not affect the viability. Moreover, an overexpression of survivin-2B in RA-FLS led to cell proliferation through cell cycle activation and by conferring resistance to apoptosis. In conclusion, survivin-2B has an important role in RA-FLS proliferation. These data suggest that survivin-2B might contribute to rheumatoid synovial hyperplasia, and have the potential as a novel therapeutic target for RA.

Down-regulation of survivin alleviates experimental arthritis

Survivin is a proto-oncogene that regulates cell division and apoptosis. It is a molecular marker of cancer. Recently, survivin has emerged as a feature of RA, associated with severe joint damage and poor treatment response. The present study examined if inhibition of survivin affects experimental arthritis, which was induced in mBSA-immunized mice by an injection of mBSA in the knee joint or developed spontaneously in collagen type II-immunized mice. The inhibition of survivin transcription by a lentivirus shRNA construct alleviated joint inflammation and reduced bone damage. The inhibition of survivin reduced the levels of metalloproteinases, β-catenin, and vimentin, limiting the invasive capacity of synovia, while no inhibition of osteoclastogenesis could be found. The inhibition of survivin led to a p53-independent reduction of T cell proliferation and favored the transcription and activity of Blimp-1, which limited IL-2 production and facilitated formation of regulatory Foxp3(+)CD4(+) and effector CD8(+) T cells. The study shows that the inhibition of survivin is sufficient to reduce joint inflammation and bone damage in preclinical models of arthritis. Antiarthritic effects of survivin inhibition are related to p53-independent control of lymphocyte proliferation.

Survivin but not Fms-like tyrosine kinase 3 ligand is up-regulated before the onset of rheumatoid arthritis: a pilot study

Introduction

Antibodies against citrullinated peptides (anti-CCP) and increased levels of cytokines precede the development of rheumatoid arthritis (RA) by several years. Recently, the proteins survivin and Fms-like tyrosine kinase 3 ligand (Flt3L) have been identified as biomarkers of RA associated with joint destruction. Our objective was to investigate the potential of survivin and Flt3L as predictors of RA in samples from patients prior to onset of symptoms.

Methods

This study included 47 individuals sampled before onset of RA (median 2.5 years (IQR 4.5) and 155 matched controls, all were donors to the Medical Biobank of Northern Sweden, and 36 RA patients. Levels of anti-CCP, survivin and Flt3L were measured using ELISAs and 29 cytokines/chemokines by multiplex detection.

Results

Levels of survivin were increased in pre-symptomatic individuals compared with controls (P = 0.003), whilst the levels of Flt3L were similar. The frequency of survivin positivity in the pre-symptomatic individuals was increased compared with the controls (36.2 vs.14.2%, P = 0.001) and predicted disease development (odds ratio (OR) =3.4 (95% confidence interval (CI) 1.6-7.2)). The frequency of survivin and Flt3L in RA patients was increased compared with the controls (both, P <0.0001, OR = 12.1 (95% CI, 5.3-27.6) and OR = 11.0 (95% CI, 3.9-30.9), respectively). Anti-CCP positive pre-symptomatic individuals and patients had significantly higher levels of survivin compared with anti-CCP2 negative individuals. In pre-symptomatic individuals, survivin correlated with IL-12, IL-1β and IL-9 whereas Flt3L correlated to a significantly broader spectrum of cytokines in RA patients.

Conclusion

Proto-oncogene survivin was increased in individuals prior to onset of symptoms of RA and was correlated to cytokines suggesting its role at pre-clinical stages of the disease.

Smoking in combination with antibodies to cyclic citrullinated peptides is associated with persistently high levels of survivin in early rheumatoid arthritis: a prospective cohort study

Introduction

High levels of the oncoprotein survivin may be detected in the majority of patients with early rheumatoid arthritis (RA). Survivin is a sensitive predictor of joint damage and persistent disease activity. Survivin-positive patients are often poor responders to antirheumatic and biological treatment. The aim of this study was to investigate the reproducibility of survivin status and its significance for clinical and immunological assessment of RA patients.

Methods

Survivin levels were measured in 339 patients from the Better Anti-Rheumatic FarmacOTherapy (BARFOT) cohort of early RA at baseline and after 24 months. The association of survivin status with joint damage (total Sharp-van der Heijde score), disease activity (Disease Activity Score based on evaluation of 28 joints (DAS28)), functional disability (Health Assessment Questionnaire (HAQ)), and pain perception (Visual Analogue Scale (VAS)) was calculated in the groups positive and negative for survivin on both occasions, and for the positive-negative and negative-positive groups.

Results

In 268 patients (79%) the levels of survivin were similar at baseline and after 24 months, 15% converted from survivin-positive to survivin-negative, and 5% from survivin-negative to survivin-positive. A combination of smoking and antibodies against cyclic citrullinated peptides (aCCP) predicted persistently (baseline and 24 months) high levels of survivin (odds ratio 4.36 (95% CI: 2.64 to 7.20), P < 0.001), positive predictive value 0.66 and specificity 0.83). The independent nature of survivin and aCCP was demonstrated by statistical and laboratory analysis. Survivin positivity on both test occasions was associated with the progression of joint damage, significantly higher DAS28 and lower rate of remission at 24 and 60 months compared to negative-negative patients. Survivin status was less associated with changes in HAQ and VAS.

Conclusions

Survivin is a relevant and reproducible marker of severe RA. Persistently high levels of survivin were associated with smoking and the presence of aCCP and/or RF antibodies and predicted persistent disease activity and joint damage.

Th17 and Th22 cells in psoriatic arthritis and psoriasis

INTRODUCTION

The aim of this study was to characterize interleukin 17 (IL-17) and interleukin 22 (IL-22) producing cells in peripheral blood (PB), skin, synovial fluid (SF) and synovial tissue (ST) in patients with psoriasis (Ps) and psoriatic arthritis (PsA).

METHODS

Flow cytometry was used to enumerate cells making IL-22 and IL-17, in skin and/or SF and PB from 11 patients with Ps and 12 patients with PsA; skin and PB of 15 healthy controls and SF from rheumatoid arthritis (RA) patients were used as controls. Expression of the interleukin 23 receptor (IL-23R) and chemokine receptors CCR4 and CCR6 was examined. Secretion of IL-17 and IL-22 was measured by ELISA. ST was analysed by immunohistochemical staining of IL-17 and IL-22.

RESULTS

Increased frequencies of IL-17+ and IL-22+ CD4+ T cells were seen in PB of patients with PsA and Ps. IL-17 secretion was significantly elevated in both PsA and Ps, whilst IL-22 secretion was higher in PsA compared to Ps and healthy controls. A higher proportion of the CD4+ cells making IL-17 or IL-22 expressed IL-23R and frequencies of IL-17+, CCR6+ and CCR4+ T cells were elevated in patients with Ps and those with PsA. In patients with PsA, CCR6+ and IL-23R + T cells numbers were elevated in SF compared to PB. Increased frequencies of IL-17+ and IL-22+ CD4+ T cells were demonstrated in Ps skin lesions. In contrast, whilst elevated frequencies of CD4+ IL-17+ cells were seen in PsA SF compared to PB, frequencies of CD4+ IL-22+ T cells were lower. Whereas IL-17 expression was equivalent in PsA, osteoarthritis (OA) and RA ST, IL-22 expression was higher in RA than either OA or PsA ST, in which IL-22 was strikingly absent.

CONCLUSIONS

Elevated frequencies of IL-17 and IL-22 producing CD4+ T cells were a feature of both Ps and PsA. However their differing distribution at disease sites, including lower frequencies of IL-22+ CD4+ T cells in SF compared to skin and PB, and lack of IL-22 expression in ST suggests that Th17 and Th22 cells have common, as well as divergent roles in the pathogenesis of Ps and PsA.

Intracellular Signaling Pathways in Rheumatoid Arthritis

Dysfunctional intracellular signaling involving deregulated activation of the Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT) and "cross-talk" between JAK/STAT and the stress-activated protein kinase/mitogen-activated protein kinase (SAPK/MAPK) and Phosphatidylinositide-3-Kinase/AKT/mammalian Target of Rapamycin (PI-3K/AKT/mTOR) pathways play a critical role in rheumatoid arthritis. This is exemplified by immune-mediated chronic inflammation, up-regulated matrix metalloproteinase gene expression, induction of articular chondrocyte apoptosis and "apoptosis-resistance" in rheumatoid synovial tissue. An important consideration in the development of novel therapeutics for rheumatoid arthritis will be the extent to which inhibiting these signal transduction pathways will sufficiently suppress immune cell-mediated inflammation to produce a lasting clinical remission and halt the progression of rheumatoid arthritis pathology. In that regard, the majority of the evidence accumulated over the past decade indicated that merely suppressing pro-inflammatory cytokine-mediated JAK/ STAT, SAPK/MAPK or PI-3K/AKT/mTOR activation in RA patients may be necessary but not sufficient to result in clinical improvement. Thus, targeting aberrant enzyme activities of spleen tyrosine kinase, sphingosine kinases-1, -2, transforming growth factor β-activated kinase-1, bone marrow kinase, and nuclear factor-κB-inducing kinase for intervention may also have to be considered.

TNF-related apoptosis-inducing ligand (TRAIL) in rheumatoid arthritis: what's new?

TNF-related apoptosis-inducing ligand (TRAIL) is a type II transmembrane protein of the TNF superfamily that serves as an extracellular signal that triggers programmed cell death in tumor cells, without affecting normal cells. Recently, scientists have turned their attention to the emerging role of TRAIL in immune and autoimmune responses. TRAIL has been shown to down-regulate the self-antigens in autoimmune diseases, such as rheumatoid arthritis (RA) by exerting its apoptotic effect on activated T cells and synoviocytes and by its local anti-inflammatory effect. The impact of TRAIL molecular variants and agonistic monoclonal antibodies in the regulation of TRAIL activity in arthritis animal models strongly supports the idea of testing the role of TRAIL in humans, with the aim of developing new effective therapies that promote apoptosis of synoviocytes and/or infiltrating lymphocytes, by targeting TRAIL. The aim of this review is to summarize recent progress and current knowledge of TRAIL functions in RA.

Reduced apoptosis correlates with enhanced autophagy in synovial tissues of rheumatoid arthritis

OBJECTIVE

Defective apoptosis contributes to the massive synovial hyperplasia in rheumatoid arthritis (RA), but the mechanism is largely unknown. To investigate the reasons for the reduced apoptosis in RA synovium, we analyzed autophagy and its relationship to apoptosis in synovial tissues from RA and osteoarthritis (OA) patients.

METHODS

Synovial tissues were obtained from seven RA and 12 OA patients undergoing knee replacement surgery. Apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and staining for p85 fragment of PolyADP-ribose polymerase (PARP). Autophagy was determined by immunoblotting for the autophagic markers Beclin-1 and LC3. MicroRNA-30a (miR-30a), which targets Beclin-1, was measured by real-time RT-PCR. The interplay between autophagy and apoptosis was determined via Spearman's correlation analysis.

RESULTS

In comparison with OA, the synovial tissues from RA displayed decreased TUNEL-positive nuclei (P < 0.01). In contrast, Beclin-1 and LC3 were overexpressed in the synovial lining layers of RA, which was correlated with decreased levels of miR-30a. Moreover, there was a significant reverse relationship between apoptosis and autophagy in RA synovial tissues (P < 0.01 and r = -0.8937).

CONCLUSION

The impaired apoptosis in RA synovium might result from increased autophagy, which in turn could be due to the deregulation of miRNA-30a.

Activation of Fms-like tyrosine kinase 3 signaling enhances survivin expression in a mouse model of rheumatoid arthritis

Survivin is known as an inhibitor of apoptosis and a positive regulator of cell division. We have recently identified survivin as a predictor of joint destruction in patients with rheumatoid arthritis (RA). Flt3 ligand (Flt3L) is expressed in the inflamed joints and has adjuvant properties in arthritis. Studies on 90 RA patients (median age 60.5 years [range, 24–87], disease duration 10.5 years [range, 0–35]) show a strong positive association between the levels of survivin and Flt3L in blood. Here, we present experimental evidence connecting survivin and Flt3L signaling. Treatment of BALB/c mice with Flt3L led to an increase of survivin in the bone marrow and in splenic dendritic cells. Flt3L changed the profile of survivin splice variants, increasing transcription of the short survivin40 in the bone marrow. Treatment with an Flt3 inhibitor reduced total survivin expression in bone marrow and in the dendritic cell population in spleen. Inhibition of survivin transcription in mice, by shRNA lentiviral constructs, reduced the gene expression of Flt3L. We conclude that expression of survivin is a downstream event of Flt3 signaling, which serves as an essential mechanism supporting survival of leukocytes during their differentiation, and maturation of dendritic cells, in RA.

Polyethylene particles stimulate expression of ITAM-related molecules in peri-implant tissues and when stimulating osteoclastogenesis in vitro

Wear particle-induced orthopaedic prosthesis loosening is associated with elevated osteoclast activity. The immunoreceptor tyrosine-based activation motif (ITAM)-related molecules OSCAR, FcRγ, TREM2 and DAP12 are important for osteoclast formation. The aim of this study was to determine if these molecules are involved in peri-implant loosening by investigating their expression in peri-implant tissues obtained at revision of joint replacement components containing polyethylene (PE) wear particles, and in osteoclasts formed in vitro in the presence of PE particles. The results showed that there was a marked and statistically significant increase in protein levels of the ITAM-related molecules in the revision tissues. The levels of OSCAR, FcRγ, TREM2 and DAP12 mRNA in the revision tissues were also increased. In vitro PE particles stimulated osteoclast resorption in the presence of 50 ng ml(-1) receptor activator NFκB (RANKL) and significantly elevated the expression of OSCAR, FcRγ, TREM2 and DAP12 during osteoclast formation. These findings suggest that the ITAM signalling molecules and their co-receptors have a role in pathogenic bone loss associated with implant PE wear.

Apoptosis as a mechanism of action of tumor necrosis factor antagonists in rheumatoid arthritis

Tumor necrosis factor (TNF) antagonists are drugs developed to block endogenous TNF, an essential proinflammatory molecule with a central role in the pathogenesis of rheumatoid arthritis (RA). Although extensive studies have been performed concerning the mode of action of TNF-blocking agents, there are still many unresolved questions and potential differences between different TNF-blocking drugs. One unresolved issue is to what extent apoptosis is affected by TNF blockade in RA. We provide an overview of studies that have investigated the proapoptotic effect of different anti-TNF drugs in RA, searching for a unified interpretation of somewhat contradictory data.

Down-regulation of microRNA-34a* in rheumatoid arthritis synovial fibroblasts promotes apoptosis resistance

OBJECTIVE

To investigate the expression and effect of the microRNA-34 (miR-34) family on apoptosis in rheumatoid arthritis synovial fibroblasts (RASFs).

METHODS

Expression of the miR-34 family in synovial fibroblasts with or without stimulation with Toll-like receptor (TLR) ligands, tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), hypoxia, or 5-azacytidine was analyzed by real-time polymerase chain reaction (PCR). Promoter methylation was studied by combined bisulfite restriction analysis. The effects of overexpression and silencing of miR-34a and miR-34a* on apoptosis were analyzed by annexin V/propidium iodide staining. Production of X-linked inhibitor of apoptosis protein (XIAP) was assessed by real-time PCR and immunohistochemistry analysis. Reporter gene assay was used to study the signaling pathways of miR-34a*.

RESULTS

Basal expression levels of miR-34a* were found to be reduced in synovial fibroblasts from RA patients compared to osteoarthritis patients, whereas levels of miR-34a, miR-34b/b*, and miR-34c/c* did not differ. Neither TNFα, IL-1β, TLR ligands, nor hypoxia altered miR-34a* expression. However, we demonstrated that the promoter of miR-34a/34a* was methylated and showed that transcription of the miR-34a duplex was induced upon treatment with demethylating agents. Enforced expression of miR-34a* led to an increased rate of FasL- and TRAIL-mediated apoptosis in RASFs. Moreover, levels of miR-34a* were highly correlated with expression of XIAP, which was found to be up-regulated in RA synovial cells. Finally, we identified XIAP as a direct target of miR-34a*.

CONCLUSION

Our data provide evidence of a methylation-specific down-regulation of proapoptotic miR-34a* in RASFs. Decreased expression of miR- 34a* results in up-regulation of its direct target XIAP, thereby contributing to resistance of RASFs to apoptosis.

The oncofetal gene survivin is re-expressed in osteoarthritis and is required for chondrocyte proliferation in vitro

Background

Regulation of cell death and cell division are key processes during chondrogenesis and in cartilage homeostasis and pathology. The oncogene survivin is considered to be critical for the coordination of mitosis and maintenance of cell viability during embryonic development and in cancer, and is not detectable in most adult differentiated tissues and cells. We analyzed survivin expression in osteoarthritic cartilage and its function in primary human chondrocytes in vitro.

Methods

Survivin expression was analyzed by immunoblotting and quantitative real-time PCR. The localization was visualized by immunofluorescence. Survivin functions in vitro were investigated by transfection of a specific siRNA.

Results

Survivin was expressed in human osteoarthritic cartilage, but was not detectable in macroscopically and microscopically unaffected cartilage of osteoarthritic knee joints. In primary human chondrocyte cultures, survivin was localized to heterogeneous subcellular compartments. Suppression of survivin resulted in inhibition of cell cycle progression and sensitization toward apoptotic stimuli in vitro.

Conclusions

The present study indicates a role for survivin in osteoarthritic cartilage and human chondrocytes. In vitro experiments indicated its involvement in cellular division and viability. Learning more about the functions of survivin in chondrocyte biology might further help toward understanding and modulating the complex processes of cartilage pathology and regeneration.

Mechanisms and clinical relevance of TRAIL-triggered responses in the synovial fibroblasts of patients with rheumatoid arthritis

OBJECTIVE

Results of studies in mice suggest a protective role for TRAIL in arthritis. The aim of this study was to investigate the role of TRAIL in patients with rheumatoid arthritis (RA).

METHODS

In the present study, we compared RA fibroblast-like synoviocytes (FLS) that were resistant or sensitive to TRAIL-induced apoptosis and the expression of TRAIL receptors in these cells, and also investigated the clinical features of the patients from whom the FLS were derived. Furthermore, we evaluated the levels of TRAIL and its soluble decoy receptor osteoprotegerin (OPG) in patients with RA, patients with osteoarthritis (OA), and patients with spondylarthritis (SpA).

RESULTS

Sensitivity to TRAIL-induced apoptosis varied in FLS from different patients, and the severity of disease in patients with RA was inversely correlated with the susceptibility of their FLS to TRAIL-induced apoptosis. TRAIL-sensitive cells expressed significantly lower levels of TRAILR-1, and silencing of TRAILR-1 increased TRAIL-induced apoptosis in RA FLS. TRAIL levels were elevated in the arthritic joints of patients with established RA, and TRAIL levels in the synovial fluid of these patients were elevated compared with levels in the synovial fluid of patients with OA or SpA. At baseline, a low OPG-to-TRAIL ratio in the sera of patients with early RA was associated with a better evolution of disease activity, but high serum levels of TRAIL at followup were associated with joint damage.

CONCLUSION

These findings suggest that TRAIL has a dual role in RA, and that the resistance of RA FLS to TRAIL-induced apoptosis is associated with a disease-promoting activity of TRAIL in RA.

HIV infection enhances TRAIL-induced cell death in macrophage by down-regulating decoy receptor expression and generation of reactive oxygen species

BACKGROUND

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) could induce apoptosis of HIV-1-infected monocyte-derived macrophage (MDM), but the molecular mechanisms are not well understood.

METHODOLOGY/PRINCIPAL FINDINGS

By using an HIV-1 Env-pseudotyped virus (HIV-1 PV)-infected MDM cell model we demonstrate that HIV-1 PV infection down-regulates the expression of TRAIL decoy receptor 1 (DcR1) and 2 (DcR2), and cellular FLICE-inhibitory protein (c-FLIP), but dose not affect the expression of death receptor 4 and 5 (DR4, DR5), and Bcl-2 family members in MDM cells. Furthermore, recombinant soluble TRAIL and an agonistic anti-DR5 antibody, AD5-10, treatment stimulates reactive oxygen species (ROS) generation and JNK phosphorylation.

CONCLUSIONS/SIGNIFICANCE

HIV infection facilitates TRIAL-induced cell death in MDM by down-regulating the expression of TRAIL decoy receptors and intracellular c-FLIP. Meanwhile, the agonistic anti-DR5 antibody, AD5-10, induces apoptosis synergistically with TRAIL in HIV-1-infected cells. ROS generation and JNK phosphorylation are involved in this process. These findings potentiate clinical usage of the combination of TRAIL and AD5-10 in eradication of HIV-infected macrophage and AIDS.

TWEAK and Fn14 expression in the pathogenesis of joint inflammation and bone erosion in rheumatoid arthritis

INTRODUCTION

TNF-like weak inducer of apoptosis (TWEAK) has been proposed as a mediator of inflammation and bone erosion in rheumatoid arthritis (RA). This study aimed to investigate TWEAK and TWEAK receptor (Fn14) expression in synovial tissue from patients with active and inactive rheumatoid arthritis (RA), osteoarthritis (OA) and normal controls and assess soluble (s)TWEAK levels in the synovial fluids from patients with active RA and OA. Effects of sTWEAK on osteoclasts and osteoblasts were investigated in vitro.

METHODS

TWEAK and Fn14 expression were detected in synovial tissues by immunohistochemistry (IHC). Selected tissues were dual labelled with antibodies specific for TWEAK and lineage-selective cell surface markers CD68, Tryptase G, CD22 and CD38. TWEAK mRNA expression was examined in human peripheral blood mononuclear cells (PBMC) sorted on the basis of their expression of CD22. sTWEAK was detected in synovial fluid from OA and RA patients by ELISA. The effect of sTWEAK on PBMC and RAW 264.7 osteoclastogenesis was examined. The effect of sTWEAK on cell surface receptor activator of NF Kappa B Ligand (RANKL) expression by human osteoblasts was determined by flow cytometry.

RESULTS

TWEAK and Fn14 expression were significantly higher in synovial tissue from all patient groups compared to the synovial tissue from control subjects (P < 0.05). TWEAK was significantly higher in active compared with inactive RA tissues (P < 0.05). TWEAK expression co-localised with a subset of CD38+ plasma cells and with CD22+ B-lymphocytes in RA tissues. Abundant TWEAK mRNA expression was detected in normal human CD22+ B cells. Higher levels of sTWEAK were observed in synovial fluids isolated from active RA compared with OA patients. sTWEAK did not stimulate osteoclast formation directly from PBMC, however, sTWEAK induced the surface expression of RANKL by human immature, STRO-1+ osteoblasts.

CONCLUSIONS

The expression of TWEAK by CD22+ B cells and CD38+ plasma cells in RA synovium represents a novel potential pathogenic pathway. High levels of sTWEAK in active RA synovial fluid and of TWEAK and Fn14 in active RA tissue, together with the effect of TWEAK to induce osteoblastic RANKL expression, is consistent with TWEAK/Fn14 signalling being important in the pathogenesis of inflammation and bone erosion in RA.

Expression of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 protein (Fn14), in healthy tissues and in tissues affected by periodontitis

BACKGROUND AND OBJECTIVE

Host-derived enzymes, cytokines and other proinflammatory mediators play an integral role in periodontal destruction. The levels of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 protein (Fn14), are elevated in tissues from a number of chronic inflammatory diseases. The aim of the present study was to investigate the expression of TWEAK and Fn14 at the protein and mRNA levels in gingival biopsies from periodontitis patients and from clinically healthy patients.

MATERIALS AND METHODS

Gingival biopsies were obtained from healthy sites (n = 7) and from sites affected by periodontitis (n = 27). The expression of TWEAK and Fn14 was investigated by immunohistochemistry in formalin-fixed, paraffin-embedded tissues. The levels of mRNA for TWEAK and Fn14 were also investigated by RT-PCR.

RESULTS

The expression of TWEAK and Fn14 proteins was significantly higher in periodontitis tissue than in healthy tissue. In periodontitis tissues, TWEAK and Fn14 proteins were mainly expressed by mononuclear leukocytes (morphologically resembling lymphocytes and plasma cells), by cells lining blood vessels, by spindle-shaped cells resembling fibroblasts and by multinucleated cells. The Fn14 mRNA level in periodontitis tissue was significantly higher than that in healthy tissue. A moderate correlation between TWEAK/Fn14 expression and inflammation and bone loss, but not pocket depth, was noted.

CONCLUSION

This study demonstrates higher expression of TWEAK protein and of Fn14 mRNA and protein in periodontitis tissues than in clinically healthy controls. Our data support the concept that TWEAK/Fn14 signaling is an additional player in the pathogenesis of periodontitis and adds to the increasing number of cytokine networks involved in periodontal inflammation.