Predictors of response to TNF-α antagonist therapy in Chinese rheumatoid arthritis

Exploring the pharmacological mechanisms and key active ingredients of total flavonoids from Lamiophlomis rotata (Benth.) Kudo against rheumatoid arthritis based on multi-technology integrated network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Lamiophlomis rotata (Benth.) Kudo (LR, Lamiaceae) is a traditional Tibetan medicinal material in China. Tibetan medicine classic and research report suggested that LR could be used to cure rheumatoid arthritis (RA). However, the anti-RA active ingredients and pharmacological mechanisms of LR have not been elucidated.

AIM OF THE STUDY

To explore the mechanisms and key active ingredients of total flavonoids from LR (TFLR) against RA.

MATERIALS AND METHODS

First, the mechanisms of TFLR against RA were investigated on collagen-induced arthritis (CIA) rat model by analyzing paw appearance, paw swelling, arthritis score, spleen index, thymus index, inflammatory cytokine (TNF-α, IL-1β, IL-6 and IL-17) levels in serum, histopathology of ankle joint and synovium from knee joint (hematoxylin-eosin, safranin O-fast green and DAB-TUNEL staining), and apoptosis-related protein (PI3K, Akt1, p-Akt, Bad, p-Bad, Bcl-xL and Bcl-2) levels in the synovium of ankle joints (Western blot). Then, the crucially active ingredients of TFLR against RA were explored by network pharmacology, ingredient analysis, in vitro metabolism and TNF-α-induced human RA synovial fibroblast MH7A proliferation assays. Network pharmacology was applied to predict the key active ingredients of TFLR against RA. The ingredient analysis and in vitro metabolism of TFLR were performed on HPLC, and MH7A proliferation assay were applied to evaluate the predicted results of network pharmacology.

RESULTS

TFLR shown excellently anti-RA effect by reducing paw swelling, arthritis score, spleen index, thymus index and inflammatory cytokine (IL-1β, IL-6 and IL-17) levels, and improving the histopathological changes of ankle joint and synovium from knee joint in CIA rats. Results of Western blot indicated that TFLR reversed the changes of PI3K, p-Akt, p-Bad, Bcl-xL and Bcl-2 levels in the ankle joint synovium of CIA rats. Results of network pharmacology exhibited that luteolin was identified as the pivotal active ingredient of TFLR against RA. The ingredient analysis of TFLR indicated that the main ingredient in TFLR was luteoloside. The in vitro metabolism study of TFLR suggested that luteoloside could be converted to luteolin in artificial gastric juice and intestinal juice. Results of MH7A proliferation assay showed that there was no significant difference between TFLR and equal luteoloside on the viability of MH7A cells, indicating that luteoloside was the key active ingredient of TFLR against RA. Additionally, the luteolin (same mol as luteoloside) showed better inhibitory effect on the viability of MH7A cells than luteoloside.

CONCLUSION

TFLR showed anti-RA effect, and the mechanism was related to promoting synovial cell apoptosis mediated by PI3K/Akt/Bad pathway. Meanwhile, this work indicated that luteoloside was the key active ingredient of TFLR against RA. This work lays a foundation for providing TFLR product with clear mechanism and stable quality to treat RA.

Serum matrix metalloproteinase-3 levels monitor the therapeutic efficacy in Syrian patients with rheumatoid arthritis

Background

The plans for the successful treatment of rheumatoid arthritis (RA) seek to attain low disease activity or reach clinical remission.

Objective

Our study aimed to compare the serum MMP-3 levels with predictors of response to therapy of rheumatoid arthritis in Syrian patients and explore its worth as a new valuable biomarker for RA therapy outcomes in daily practice.

Methods

Serum samples were gathered from 43 RA patients at diagnosis and 12 weeks of therapy. Related clinical and laboratory tests were estimated, levels of serum MMP-3 were measured by ELISA method and the disease activity was assessed using disease activity scores in 28 joints with an erythrocyte sedimentation rate (DAS28-ESR) before and after therapy.

Results

The mean of Serum MMP-3 levels significantly decreased (322.3 ± 43.83 ng/ml) after therapy (12 weeks) in RA patients compared to its mean at baseline (486.49 ± 34.5 ng/ml). There wasn't a statistically significant difference in the mean of MMP-3 levels before and after therapy (P = 0.137) in non-responder patients. Patients who showed a good response (N = 38) presented higher MMP-3 levels at first which subsequently decreased significantly at the 12-week follow-up (P < 0.05). Also, there was a statistically significant difference in MMP-3 levels between the two groups of patients after therapy (P = 0.002). To differentiate between RA patients who responded to therapy and who did not, our results found that the cut-off value of serum MMP-3 was 317.8 ng/ml (sensitivity was 80%, specificity was 73%, AUC was 0.818, 95% CI: 1.114-112.5; P = 0.045) and the best cut-off value of DAS28-ESR was 5.325 (sensitivity 100%, specificity 100%, AUC = 100%,95% CI: 15.2 to 47203.8).

Conclusion

serum MMP-3 can be added as a novel and valuable biomarker in estimating the therapeutic response in RA patients, but it isn't better than DAS28-ESR.

Prediction of response to anti-TNF treatment using laboratory biomarkers in patients with rheumatoid arthritis: a systematic review

OBJECTIVES

In this systematic review, we aim to identify laboratory biomarkers that predict response to tumour necrosis factor inhibitors (TNFi) in patients with rheumatoid arthritis (RA).

METHODS

EMBASE, PubMed and Cochrane Library (CENTRAL) were searched for studies that presented predictive accuracy measures of laboratory biomarkers, or in which these were calculable. Likelihood ratios were calculated in order to determine whether a test result relevantly changed the probability of response. Likelihood ratios between 2-10 and 0.5-0.1 were considered weak predictors, respectively, and ratios above 10 or below 0.1 were considered strong predictors of response. Primary focus was on biomarkers studied ≥3 times.

RESULTS

From 41 included studies, data on 99 different biomarkers were extracted. Five biomarkers were studied ≥3 times, being (1) anti-cyclic citrullinated peptide (CCP), (2) rheumatoid factor, (3) -308 polymorphism in the TNF-α gene, (4) SE copies in the HLA-DRB1 gene and (5) FcGR2A polymorphism. No studies showed a strong predictive association and only one study on anti-CCP showed a weak positive association.

CONCLUSIONS

No biomarkers were found that consistently showed a (strong) predictive effect for response to TNFi in patients with RA. Given the disappointing yield of previous predictive biomarker research, future studies should focus on exploring, combining and validating the most promising laboratory biomarkers identified in this review, and searching for new predictors. Besides this, they should focus on contexts where prediction-aided decision-making can have a large impact (even with limited predictive value of markers/models).

PROSPERO REGISTRATION NUMBER

CRD42021278987.

Traditional Tibetan medicine: therapeutic potential in rheumatoid arthritis

Rheumatoid arthritis (RA) is a severe inflammatory autoimmune disease characterized by the failed spontaneous resolution of inflammation. The induction of immune regulation and resolution of inflammatory pathways are effective in alleviating inflammation in RA. As the oldest medical system in the world, traditional Tibetan medicine (TTM) has a long history of preventing and treating RA. This review provides a comprehensive overview of medicinal plants with anti-RA activity in the TTM system, using classic books of Tibetan medicine, modern research literature, and drug standards. A total of 27 species have been found to be effective in treating RA, including Tinospora sinensis (Lour.) Merr., Terminalia chehula Retz., P. hookeri (C. B. Clarke) Hock.), and Aconitum pendulum Busch. Alkaloids, flavonoids, polyphenols, and terpenoids have turned out to be the major bioactive components for RA treatment. The inhibition of pro-inflammatory cytokine expression by mediating the NF-κB, MAPK, and JAK/STAT pathways is the core mechanism in RA treatment. In conclusion, this review provides key information and research perspectives for further research on the anti-RA effects of TTM.

Interleukin-34 promotes tumorigenic signals for colon cancer cells

Colorectal carcinoma (CRC) is one of the most common forms of malignancy in the Western world. Accumulating evidence indicates that colon carcinogenesis is tightly controlled by tumour-associated immune cells and stromal cells, which can either stimulate or suppress CRC cell growth and survival, mainly via the production of cytokines. Interleukin-34 (IL-34), a cytokine known to regulate mainly monocyte/macrophage survival and function, is highly produced within the CRC microenvironment by several cell types, including cancer cells, tumour-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs), and regulates the pro-tumoural functions of such cells. In this article, we summarize the available data supporting the multiple effects of IL-34 in human CRC.

Predictors of response to etanercept-methotrexate treatment: a post hoc logistic regression analysis of a randomized, open-label study in Latin American patients with rheumatoid arthritis

BACKGROUND

Determining potential predictors of clinical response would allow a more personalized rheumatoid arthritis (RA) treatment approach in heterogeneous populations such as Latin American (LA) patients.

METHODS

Post hoc analysis to identify baseline characteristics predictive of clinical remission in response to treatment with etanercept (ETN) plus methotrexate (MTX) in LA patients with moderate to severe MTX-resistant RA. We report data from the group of patients who received ETN 50 mg/week plus MTX (ETN + MTX, n = 281) in a clinical trial consisting of an initial 24-week open-label phase, followed by a 104-week extension. Remission was defined as 28-joint Disease Activity Score with erythrocyte sedimentation rate (DAS28-ESR) score < 2.6. Cutoff values to dichotomize baseline variables maximizing the detection of remission were obtained from Receiver Operator Curve analyses. Baseline dichotomized and categorical variables were analyzed altogether in a stepwise logistic regression model. Odds of attaining response at Weeks 24 and 128 were estimated for each significant predictor.

RESULTS

At Week 24 and Week 128, 27% (66/241) and 42% (91/219) of patients in the ETN + MTX group achieved remission. On average, patients achieving remission were younger and had lower baseline ESR, lower Physician Global Assessment (PGA) scores, lower total Health Assessment Questionnaire (HAQ) scores, and lower visual analog scale (VAS) Pain scores compared with patients who did not achieve remission. The best subset of baseline variables predicting Week 24 remission in the stepwise regression model were age ≤ 49 years (odds ratio [OR] 2.93), body mass index (BMI) > 28.5 kg/m² (OR 3.24), disease duration > 3.7 years (OR 2.22), ESR ≤ 42 mm/h (OR 2.72), PGA ≤ 6 (OR 3.21), tender joint count ≤ 14 (OR 2.25), and total HAQ score ≤ 1.6 (OR 2.86). At Week 128, age ≤ 42 years (OR 2.21), SF-36 Mental Health Scale score > 39.6 (OR 2.16), White race (OR 4.07), > 18 swollen joints (OR 2.11), and VAS Pain ≤ 41 (OR 6.05) at baseline were the best subset of significant predictors of remission.

CONCLUSIONS

In LA patients with RA, younger age, higher BMI, longer disease duration, higher SF-36 Mental Health Scale score, higher swollen joint count, and overall lower disease activity predicted clinical response to ETN + MTX therapy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00848354.

Lnc RNA ZFAS1 regulates the proliferation, apoptosis, inflammatory response and autophagy of fibroblast-like synoviocytes via miR-2682-5p/ADAMTS9 axis in rheumatoid arthritis

Backgrounds: Rheumatoid arthritis (RA) is a frequent autoimmune disease. Emerging evidence indicated that ZNFX1 antisense RNA1 (ZFAS1) participates in the physiological and pathological processes in RA. However, knowledge of ZFAS1 in RA is limited, the potential work pathway of ZFAS1 needs to be further investigated.

Methods: Levels of ZFAS1, microRNA (miR)-2682-5p, and ADAM metallopeptidase with thrombospondin type 1 motif 9 (ADAMTS9) were estimated using quantitative real-time polymerase chain reaction (qRT-PCR) assay. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was conducted to explore the ability of cell proliferation in fibroblast-like synoviocytes (FLS-RA). Cell apoptosis was measured via flow cytometry. Also, levels of ADAMTS9, apoptosis-related proteins, cleaved-caspase-3 (active large subunit), and autophagy-related proteins were identified adopting Western blot. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the productions of inflammatory cytokines. Beside, the interrelation between miR-2682-5p and ZFAS1 or ADAMTS9 was verified utilizing dual-luciferase reporter assay.

Results: High levels of ZFAS1 and ADAMTS9, and a low level of miR-2682-5p were observed in RA synovial tissues and FLS-RA. Knockdown of ZFAS1 led to the curbs of cell proliferation, inflammation, autophagy, and boost apoptosis in FLS-RA, while these effects were abolished via regaining miR-2682-5p inhibition. Additionally, the influence of miR-2682-5p on cell phenotypes and inflammatory response were eliminated by ADAMTS9 up-regulation in FLS-RA. Mechanically, ZFAS1 exerted its role through miR-2682-5p/ADAMTS9 axis in RA.

Conclusion: ZFAS1/miR-2682-5p/ADAMTS9 axis could modulate the cell behaviors, inflammatory response in FLS-RA, might provide a potential therapeutic target for RA treatment.

The twin cytokines interleukin-34 and CSF-1: masterful conductors of macrophage homeostasis

Macrophages are specialized cells that control tissue homeostasis. They include non-resident and tissue-resident macrophage populations which are characterized by the expression of particular cell surface markers and the secretion of molecules with a wide range of biological functions. The differentiation and polarization of macrophages relies on specific growth factors and their receptors. Macrophage-colony stimulating factor (CSF-1) and interleukine-34 (IL-34), also known as "twin" cytokines, are part of this regluatory landscape. CSF-1 and IL-34 share a common receptor, the macrophage-colony stimulating factor receptor (CSF-1R), which is activated in a similar way by both factors and turns on identical signaling pathways. However, there is some discrete differential activation leading to specific activities. In this review, we disscuss recent progress in understanding of the role of the twin cytokines in macrophage differentiation, from their interaction with CSF-1R and the activation of signaling pathways, to their implication in macrophage polarization of non-resident and tissue-resident macrophages. A special focus on IL-34, its involvement in pathophsyiological contexts, and its potential as a theranostic target for macrophage therapy will be proposed.

Communications Between Bone Marrow Macrophages and Bone Cells in Bone Remodeling

The mammalian skeleton is a metabolically active organ that continuously undergoes bone remodeling, a process of tightly coupled bone resorption and formation throughout life. Recent studies have expanded our knowledge about the interactions between cells within bone marrow in bone remodeling. Macrophages resident in bone (BMMs) can regulate bone metabolism via secreting numbers of cytokines and exosomes. This review summarizes the current understanding of factors, exosomes, and hormones that involved in the communications between BMMs and other bone cells including mensenchymal stem cells, osteoblasts, osteocytes, and so on. We also discuss the role of BMMs and potential therapeutic approaches targeting BMMs in bone remodeling related diseases such as osteoporosis, osteoarthritis, rheumatoid arthritis, and osteosarcoma.

Emerging roles of IL-34 in health and disease

Macrophages are part of the innate immune system and are present in every organ of the body. They fulfill critical roles in tissue homeostasis and development and are involved in various pathologies. An essential factor for the development, homeostasis, and function of mononuclear phagocytes is the colony stimulating factor-1 receptor (CSF-1R), which has two known ligands: CSF-1 and interleukin-34 (IL-34). While CSF-1 has been extensively studied, the biology and functions of IL-34 are only now beginning to be uncovered. In this review, we discuss recent advances of IL-34 biology in health and disease with a specific focus on mononuclear phagocytes.

Role of Interleukin-34 in Cancer

Cross-talk between cancer cells and the immune cells occurring in the tumor microenvironment is crucial in promoting signals that foster tumor growth and metastasis. Both cancer cells and immune cells secrete various interleukins (IL), which, either directly or indirectly, stimulate cancer-cell proliferation, survival, and diffusion, as well as contribute to sculpt the immune microenvironment, thereby amplifying tumorigenic stimuli. IL-34, a cytokine produced by a wide range of cells, has been initially involved in the control of differentiation, proliferation, and survival of myeloid cells. More recent studies documented the overexpression of IL-34 in several cancers, such as hepatocarcinoma, osteosarcoma, multiple myeloma, colon cancer, and lung cancer, and showed that tumor cells can produce and functionally respond to this cytokine. In this review, we summarize the multiple roles of IL-34 in various cancers, with the aim to better understand the relationship between the expression of this cytokine and cancer behavior and to provide new insights for exploring a new potential therapeutic target.

Immunomodulation of Interleukin-34 and its Potential Significance as a Disease Biomarker and Therapeutic Target

Interleukin (IL)-34 is a cytokine discovered a few years ago and identified as the second colony-stimulating factor (CSF)-1 receptor (CSF-1R) ligand. Although CSF-1 and IL-34 share the same receptor through which they trigger similar effects, IL-34 also binds to receptors protein-tyrosine phosphatase (PTP)-ζ and syndecan-1. Thus, IL-34 is involved in several signaling pathways and participates in a wide array of biological actions. This review analyzes current studies on the role of IL-34 under physiological and pathological conditions, and explores its potential significance as a disease biomarker and therapeutic target. In physiological conditions, IL-34 expression is restricted to the microglia and Langerhans cells, with a fundamental role in cellular differentiation, adhesion and migration, proliferation, metabolism, and survival. It is released in response to inflammatory stimuli, such as pathogen-associated molecular patterns or pro-inflammatory cytokines, with effects over various immune cells, including monocytes, macrophages, and regulatory T cells that shape the immune microenvironment. Over the past decade, accumulating evidence has suggested a potent immune regulation of IL-34 in pathological states such as autoimmune diseases, cancer, transplant rejection, neurologic diseases, infections, and inflammatory diseases. Importantly, IL-34 may hold great promise for acting as a biomarker for monitoring disease severity and progression, and may serve as a new therapeutic target for the treatment of several diseases in clinical settings.

Assessing prognosis and prediction of treatment response in early rheumatoid arthritis: systematic reviews

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, debilitating disease associated with reduced quality of life and substantial costs. It is unclear which tests and assessment tools allow the best assessment of prognosis in people with early RA and whether or not variables predict the response of patients to different drug treatments.

OBJECTIVE

To systematically review evidence on the use of selected tests and assessment tools in patients with early RA (1) in the evaluation of a prognosis (review 1) and (2) as predictive markers of treatment response (review 2).

DATA SOURCES

Electronic databases (e.g. MEDLINE, EMBASE, The Cochrane Library, Web of Science Conference Proceedings; searched to September 2016), registers, key websites, hand-searching of reference lists of included studies and key systematic reviews and contact with experts.

STUDY SELECTION

Review 1 - primary studies on the development, external validation and impact of clinical prediction models for selected outcomes in adult early RA patients. Review 2 - primary studies on the interaction between selected baseline covariates and treatment (conventional and biological disease-modifying antirheumatic drugs) on salient outcomes in adult early RA patients.

RESULTS

Review 1 - 22 model development studies and one combined model development/external validation study reporting 39 clinical prediction models were included. Five external validation studies evaluating eight clinical prediction models for radiographic joint damage were also included. c-statistics from internal validation ranged from 0.63 to 0.87 for radiographic progression (different definitions, six studies) and 0.78 to 0.82 for the Health Assessment Questionnaire (HAQ). Predictive performance in external validations varied considerably. Three models [(1) Active controlled Study of Patients receiving Infliximab for the treatment of Rheumatoid arthritis of Early onset (ASPIRE) C-reactive protein (ASPIRE CRP), (2) ASPIRE erythrocyte sedimentation rate (ASPIRE ESR) and (3) Behandelings Strategie (BeSt)] were externally validated using the same outcome definition in more than one population. Results of the random-effects meta-analysis suggested substantial uncertainty in the expected predictive performance of models in a new sample of patients. Review 2 - 12 studies were identified. Covariates examined included anti-citrullinated protein/peptide anti-body (ACPA) status, smoking status, erosions, rheumatoid factor status, C-reactive protein level, erythrocyte sedimentation rate, swollen joint count (SJC), body mass index and vascularity of synovium on power Doppler ultrasound (PDUS). Outcomes examined included erosions/radiographic progression, disease activity, physical function and Disease Activity Score-28 remission. There was statistical evidence to suggest that ACPA status, SJC and PDUS status at baseline may be treatment effect modifiers, but not necessarily that they are prognostic of response for all treatments. Most of the results were subject to considerable uncertainty and were not statistically significant.

LIMITATIONS

The meta-analysis in review 1 was limited by the availability of only a small number of external validation studies. Studies rarely investigated the interaction between predictors and treatment.

SUGGESTED RESEARCH PRIORITIES

Collaborative research (including the use of individual participant data) is needed to further develop and externally validate the clinical prediction models. The clinical prediction models should be validated with respect to individual treatments. Future assessments of treatment by covariate interactions should follow good statistical practice.

CONCLUSIONS

Review 1 - uncertainty remains over the optimal prediction model(s) for use in clinical practice. Review 2 - in general, there was insufficient evidence that the effect of treatment depended on baseline characteristics.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016042402.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Biological functions and clinical implications of interleukin-34 in inflammatory diseases

Interleukin (IL)-34 is a recently discovered cytokine and ligand of the colony-stimulating factor (CSF)-1 receptor. Although CSF-1 and IL-34 share similar biological properties, their expression patterns and downstream signaling pathways are distinct. IL-34 can influence differentiation and has functions in multiple cell types (e.g., dendritic cells, monocytes, macrophages). In the pathological conditions, IL-34 is induced by pro-inflammatory stimuli (e.g., cytokines, pathogen-associated molecular patterns, and infection). Current evidence shows that IL-34 is a critical player in inflammatory response and is involved in the pathogenesis of inflammatory autoimmune dysfunction. Therefore, IL-34 may be a promising clinical biomarker and therapeutic target for treating inflammatory related disorders. In this article, we review the advances in biological functions of IL-34 and our understanding of its role in the development of inflammatory diseases as well as therapeutic applications.

Interleukin-34, a comprehensive review

IL-34 is a novel cytokine that was identified in 2008 in a comprehensive proteomic analysis as a tissue-specific ligand of CSF-1 receptor (CSF-1R). IL-34 exists in all vertebrates including fish, amphibians, birds, and mammals, showing high conservation among species. Structurally, IL-34 belongs to the short-chain helical hematopoietic cytokine family but shows no apparent consensus structural domains, motifs, or sequence homology with other cytokines. IL-34 is synthesized as a secreted homodimeric glycoprotein that binds to the extracellular domains of CSF-1R and receptor-type protein-tyrosine phosphatase-zeta (PTP-ζ) in addition to the chondroitin sulfate chains of syndecan-1. These interactions result in activating several signaling pathways that regulate major cellular functions, including proliferation, differentiation, survival, metabolism, and cytokine/chemokine expression in addition to cellular adhesion and migration. In the steady state, IL-34 contributes to the development and maintenance of specific myeloid cell subsets in a tissue-specific manner: Langerhans cells in the skin and microglia in the brain. In pathological conditions, changes in IL-34 expression-increased or decreased-are involved in disease pathogenesis and correlate with progression, severity, and chronicity. One decade after its discovery, IL-34 has been introduced as a newcomer to the big family of interleukins with specific physiological functions, critical pathological roles, and promising clinical applications in disease diagnosis and treatment. In this review, we celebrate the 10th anniversary of IL-34 discovery, introducing its biological characteristics, and discussing the importance of IL-34 signaling network in health and disease.

IL-34 regulates IL-6 and IL-8 production in human lung fibroblasts via MAPK, PI3K-Akt, JAK and NF-κB signaling pathways

IL-34 plays diverse roles in disease due to its inflammatory and immunosuppressive properties. Elevated IL-34 expression has been observed in lung cancers and pulmonary infections although its role is unclear. We found that IL-34 addition to primary lung fibroblasts significantly promoted IL-6 and IL-8 expression in a dose and time dependent manner. These effects were reversed when JAK, NF-κB, Akt and p38 inhibitors were included before IL-34 addition. Protein phosphorylation in these pathways was also observed through western-blotting. Stimulation of human lung fibroblasts with IL-34 in combination with TNF-α, IL-17A and IL-4 enhanced inflammatory cytokine production. Our data confirmed the inflammatory effect of IL-34 on human lung fibroblasts and suggested that the IL-34/CSF-1R axis may be a novel therapeutic target in pulmonary disease.

Anti-inflammatory and anti-angiogenic activities in vitro of eight diterpenes from Daphne genkwa based on hierarchical cluster and principal component analysis

Rheumatoid arthritis (RA) is one of the most prevalent chronic inflammatory and angiogenic diseases. The aim of this study was to evaluate the anti-inflammatory and anti-angiogenic activities in vitro of eight diterpenoids isolated from Daphne genkwa. LC-MS was used to identify diterpenes isolated from D. genkwa. The anti-inflammatory and anti-angiogenic activities of eight diterpenoids were evaluated on LPS-induced macrophage RAW264.7 cells and TNF-α-stimulated human umbilical vein endothelial cells (HUVECs) using hierarchical cluster analysis (HCA) and principal component analysis (PCA). The eight diterpenes isolated from D. genkwa were identified as yuanhuaphnin, isoyuanhuacine, 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl, yuanhuagine, isoyuanhuadine, yuanhuadine, yuanhuaoate C and yuanhuacine. All the eight diterpenes significantly down-regulated the excessive secretion of TNF-α, IL-6, IL-1β and NO in LPS-induced RAW264.7 macrophages. However, only 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl markedly reduced production of VEGF, MMP-3, ICAM and VCAM in TNF-α-stimulated HUVECs. HCA obtained 4 clusters, containing 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl, isoyuanhuacine, isoyuanhuadine and five other compounds. PCA showed that the ranking of diterpenes sorted by efficacy from highest to lowest was 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl, yuanhuaphnin, isoyuanhuacine, yuanhuacine, yuanhuaoate C, yuanhuagine, isoyuanhuadine, yuanhuadine. In conclusion, eight diterpenes isolated from D. genkwa showed different levels of activity in LPS-induced RAW264.7 cells and TNF-α-stimulated HUVECs. The comprehensive evaluation of activity by HCA and PCA indicated that of the eight diterpenes, 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl was the best, and can be developed as a new drug for RA therapy.

Interleukin 34, from pathogenesis to clinical applications

Interleukin-34 (IL-34) is a hematopoietic cytokine that was described for the first time in 2008 as a second ligand of CSF1R in addition to M-CSF. IL-34 and M-CSF share no sequence homology, but have similar functions, affecting the biology of myeloid cell lineage. In contrast to M-CSF, IL-34 shows unique signaling and expression patterns. Physiologically, IL-34 expression is restricted to epidermis and CNS, acting as a regulator of Langerhans cells and microglia, respectively. However, IL-34 expression can be induced and regulated by NF-κB under pathological conditions. Importantly, growing evidence indicates a correlation between IL-34 and disease severity, chronicity and progression. In addition to its promising roles as a novel diagnostic and prognostic biomarker of disease, IL-34 may also serve as a powerful target for therapeutic intervention. Here, we review the current knowledge regarding the emerging roles of IL-34 in disease, and focus on the clinical applications of IL-34 in medicine.

LncRNA HOTAIR alleviates rheumatoid arthritis by targeting miR-138 and inactivating NF-κB pathway

Rheumatoid arthritis (RA) is a chronic and autoimmune-mediated inflammatory disease. We aimed to investigate the regulation of lncRNA HOTAIR in LPS-treated chondrocytes and RA mouse. Our results showed that HOTAIR expression was significantly reduced in LPS-treated chondrocytes. The HOTAIR was then over-expressed in chondrocytes by transfecting recombinant lentivirus carrying sequences encoding HOTAIR. The LPS-induced reduction of cell proliferation rate and production of two inflammatory factors interleukin (IL)-17, IL-23 were markedly inhibited. Enforced expression of HOTAIR also led to the upregulation of proliferation-related protein Ki67 and proliferating cell nuclear antigen (PCNA). Moreover, a negative correlation was detected between the expression of HOTAIR and microRNA (miR)-138, and the expression of miR-138 was significantly increased in LPS-induced chondrocytes. The effects of HOTAIR over-expression on the proliferation and inflammation were partly reversed by miR-138 overexpression. Furthermore, the overexpression of HOTAIR significantly inhibited the activation of nuclear transcription factor-κB (NF-κB) in LPS-treated chondrocytes by suppressing p65 to cell nucleus, resulting in the down-regulation of IL-1β and tumor necrosis factor (TNF)-α. In addition, the in vivo experiments exhibited that overexpression of HOTAIR increased cell proliferation and inhibited inflammation in RA rats, which were demonstrated by upregulation of Ki67 and PCNA, reduced CD4⁺IL-17⁺,CD4⁺IL-23⁺ cells, and down-regulation of p-p65, IL-1β and TNF-α. In summary, our study suggests HOTAIR plays a protective role in RA by increasing proliferation rate and inhibiting inflammation, which may be related with the regulation of miR-138 expression and NF-κB signaling pathway. These results suggest that the regulation of HOTAIR may be a promising therapeutic strategy for RA.

Immunoregulatory properties of the cytokine IL-34

Interleukin-34 is a cytokine with only partially understood functions, described for the first time in 2008. Although IL-34 shares very little homology with CSF-1 (CSF1, M-CSF), they share a common receptor CSF-1R (CSF-1R) and IL-34 has also two distinct receptors (PTP-ζ) and CD138 (syndecan-1). To make the situation more complex, IL-34 has also been shown as pairing with CSF-1 to form a heterodimer. Until now, studies have demonstrated that this cytokine is released by some tissues that differ to those where CSF-1 is expressed and is involved in the differentiation and survival of macrophages, monocytes, and dendritic cells in response to inflammation. The involvement of IL-34 has been shown in areas as diverse as neuronal protection, autoimmune diseases, infection, cancer, and transplantation. Our recent work has demonstrated a new and possible therapeutic role for IL-34 as a Foxp3+ Treg-secreted cytokine mediator of transplant tolerance. In this review, we recapitulate most recent findings on IL-34 and its controversial effects on immune responses and address its immunoregulatory properties and the potential of targeting this cytokine in human.

Functions of interleukin-34 and its emerging association with rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic, synovial inflammation affecting multiple joints, finally leading to extra-articular lesions for which limited effective treatment options are currently available. Interleukin-34 (IL-34), recently discovered as the second colony-stimulating factor-1 receptor (CSF-1R) ligand, is a newly discovered cytokine. Accumulating evidence has disclosed crucial roles of IL-34 in the proliferation and differentiation of mononuclear phagocyte lineage cells, osteoclastogenesis and inflammation. Recently, IL-34 was detected at high levels in patients with active RA and in experimental models of inflammatory arthritis. Blockade of functional IL-34 with a specific monoclonal antibody can reduce the severity of inflammatory arthritis, suggesting that targeting IL-34 or its receptors may constitute a novel therapeutic strategy for autoimmune diseases such as RA. Here, we have comprehensively discussed the structure and biological functions of IL-34, and reviewed recent advances in our understanding of the emerging role of IL-34 in the development of RA as well as its potential utility as a therapeutic target.