Is IL-1 a good therapeutic target in the treatment of arthritis?

Interleukin inhibitors and the associated risk of candidiasis

Interleukins (ILs) are vital in regulating the immune system, enabling to combat fungal diseases like candidiasis effectively. Their inhibition may cause enhanced susceptibility to infection. IL inhibitors have been employed to control autoimmune diseases and inhibitors of IL-17 and IL-23, for example, have been associated with an elevated risk of Candida infection. Thus, applying IL inhibitors might impact an individual's susceptibility to Candida infections. Variations in the severity of Candida infections have been observed between individuals with different IL inhibitors, necessitating careful consideration of their specific risk profiles. IL-1 inhibitors (anakinra, canakinumab, and rilonacept), IL-2 inhibitors (daclizumab, and basiliximab), and IL-4 inhibitors (dupilumab) have rarely been associated with Candida infection. In contrast, tocilizumab, an inhibitor of IL-6, has demonstrated an elevated risk in the context of coronavirus disease 2019 (COVID-19) treatment, as evidenced by a 6.9% prevalence of candidemia among patients using the drug. Furthermore, the incidence of Candida infections appeared to be higher in patients exposed to IL-17 inhibitors than in those exposed to IL-23 inhibitors. Therefore, healthcare practitioners must maintain awareness of the risk of candidiasis associated with using of IL inhibitors before prescribing them. Future prospective studies need to exhaustively investigate candidiasis and its associated risk factors in patients receiving IL inhibitors. Implementing enduring surveillance methods is crucial to ensure IL inhibitors safe and efficient utilization of in clinical settings.

Effects of synovial macrophages in osteoarthritis

Osteoarthritis (OA) is a common degenerative disease in mammals. However, its pathogenesis remains unclear. Studies indicate that OA is not only an aging process that but also an inflammation-related disease. Synovitis is closely related to the progression of OA, and synovial macrophages are crucial participants in synovitis. Instead of being a homogeneous population, macrophages are polarized into M1 or M2 subtypes in OA synovial tissues. Polarization is highly associated with OA severity. However, the M1/M2 ratio cannot be the only factor in OA prognosis because intermediate stages of macrophages also exist. To better understand the mechanism of this heterogeneous disease, OA subtypes of synovial macrophages classified by gene expression were examined. Synovial macrophages do not act alone; they interact with surrounding cells such as synovial fibroblasts, osteoclasts, chondrocytes, lymphocytes and even adipose cells through a paracrine approach to exacerbate OA. Treatments targeting synovial macrophages and their polarization are effective in relieving pain and protecting cartilage during OA development. In this review, we describe how synovial macrophages and their different polarization states influence the progression of OA. We summarize the current knowledge of the interactions between macrophages and other joint cells and examine the current research on new medications targeting synovial macrophages.

Role of Interleukin-36 in inflammatory joint diseases

Interleukin (IL)-36 is a family of cytokines that belongs to the larger IL-1 superfamily. IL-36 agonist/antagonist binds to the interleukin-36 receptor involving in physiological inflammation regulation and pathogenesis of many inflammatory diseases. In inflammatory joint diseases, the expression of IL-36 changes, and some studies have initially explored the role of IL-36 in these diseases. In psoriatic arthritis, IL-36 signal mediates plasma cell and fibroblast-like synoviocyte crosstalk presenting IL-36 agonist/antagonist imbalance. In rheumatoid arthritis, IL-36 agonists induce fibroblast-like synoviocyte to produce pro-inflammatory factors, while IL-36 antagonist deficiency leads to lesion progression. In osteoarthritis, IL-36 agonists induce chondrocytes to produce catabolic enzymes and pro-inflammatory factors. This article reviews the expression and function of IL-36 in different inflammatory joint diseases to provide a reference for revealing their pathogenic mechanisms and discovering therapeutic targets.

Association of mental distress with chronic diseases in 1.9 million individuals: A population-based cross-sectional study

OBJECTIVE

Mental distress has a high global prevalence and is associated with poor health outcomes. This study aimed to estimate the relationship between mental distress and the risk of 10 chronic diseases using data from the Behavioral Risk Factor Surveillance System (BRFSS).

METHODS

Cross-sectional data from the 2013, 2014, 2015, 2016 and 2017 BRFSS were analyzed. The association between mental distress based on the number of days of poor mental health and the risk of 10 chronic diseases, namely obesity, diabetes, asthma, chronic obstructive pulmonary disease (COPD), arthritis, kidney disease, coronary heart disease (CHD), stroke, skin cancer, and other cancers, were assessed by logistic regression models to calculate odds ratios and 95% confidence intervals. Subgroup analyses stratified by age and sex were also conducted.

RESULTS

Positive associations between mental distress and chronic diseases were observed. We also found a dose-response gradient between mental distress levels and the risk of all chronic diseases except skin cancer. In respondents aged 18-44 years reporting ≥23 days/month of mental distress, there has the largest odds ratio between mental distress levels and each chronic disease. Moreover, mental distress was associated with higher risks of obesity and arthritis in women relative to men.

CONCLUSIONS

Mental distress was positively associated with chronic diseases. Age and sex are crucial in this relationship. Further studies with longitudinal data are needed to clarify the direction of this association.

Synergistic Interaction of Low Salinity Stress With Vibrio Infection Causes Mass Mortalities in the Oyster by Inducing Host Microflora Imbalance and Immune Dysregulation

A sudden drop in salinity following extreme precipitation events usually causes mass mortality of oysters exposed to pathogens in ocean environment. While how low salinity stress interacts with pathogens to cause mass mortality remains obscure. In this study, we performed an experiment by low salinity stress and pathogen infection with Vibrio alginolyticus to investigate their synergistic effect on the mortality of the Pacific oyster toward understanding of the interaction among environment, host, and pathogen. We showed that low salinity stress did not significantly affect proliferation and virulence of V. alginolyticus, but significantly altered microbial composition and immune response of infected oysters. Microbial community profiling by 16S rRNA amplicon sequencing revealed disrupted homeostasis of digestive bacterial microbiota with the abundance of several pathogenic bacteria being increased, which may affect the pathogenesis in infected oysters. Transcriptome profiling of infected oysters revealed that a large number of genes associated with apoptosis and inflammation were significantly upregulated under low salinity, suggesting that low salinity stress may have triggered immune dysregulation in infected oysters. Our results suggest that host-pathogen interactions are strongly affected by low salinity stress, which is of great significance for assessing future environmental risk of pathogenic diseases, decoding the interaction among environment, host genetics and commensal microbes, and disease surveillance in the oyster.

The Therapeutic Landscape of Rheumatoid Arthritis: Current State and Future Directions

Rheumatoid arthritis (RA) is a debilitating autoimmune disease with grave physical, emotional and socioeconomic consequences. Despite advances in targeted biologic and pharmacologic interventions that have recently come to market, many patients with RA continue to have inadequate response to therapies, or intolerable side effects, with resultant progression of their disease. In this review, we detail multiple biomolecular pathways involved in RA disease pathogenesis to elucidate and highlight pathways that have been therapeutic targets in managing this systemic autoimmune disease. Here we present an up-to-date accounting of both emerging and approved pharmacological treatments for RA, detailing their discovery, mechanisms of action, efficacy, and limitations. Finally, we turn to the emerging fields of bioengineering and cell therapy to illuminate possible future targeted therapeutic options that combine material and biological sciences for localized therapeutic action with the potential to greatly reduce side effects seen in systemically applied treatment modalities.

Deciphering Role of Cytokines for Therapeutic Strategies Against Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is a systemic, chronic, autoimmune, inflammatory disorder that affects both large and small synovial joints in a symmetric pattern. RA initiates as painful inflammation of the joints leading to stiffness of joint, joint destruction and further worsens the condition causing permanent irreversible damage to the joints, making them physically disabled. Across the globe, there are around 1.2 million cases of RA reported. Inspite of various available therapeutic and pharmacological agents against RA, none of the treatments assure complete cure. Understanding the in depth-role of cytokines and interleukins in the disease pathogenesis of RA could help in exploiting them for developing novel therapeutic strategies against RA. This review provides insights into the pathogenesis of RA and gives a brief overview of cytokines, which play an important role in the progression of the disease. We have also discussed the possible role of interleukins in the context of RA, which could help future researchers to explore them for identifying new therapeutic agents.

Gout and AA-Amyloidosis: A Case-Based Review

Background:

AA-amyloidosis complicates many chronic infections and inflammatory diseases, including rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis, but its relationship to gout is extremely rare. As it is unknown definitely what the pathophysiological connections between gout and amyloidosis are, treatment issues of the diseases are open for discussion.

Aim:

To establish a link between gout and AA-amyloidosis, and to improve the quality of treatment in patients suffering from gout and AA-amyloidosis.

Methods:

We reviewed the English-language literature sources, searching not only for rare cases of the combination of gout and AA amyloidosis, but also detailed descriptions of the medical treatments for the two pathologies.

Results:

By July 2020, we had identified 14 cases describing AA amyloidosis in patients with gout. Most of those patients had been suffering tophaceous gout for at least 10 years, and were prescribed various methods of treatment; however, not all patients took colchicine regularly. In some cases, therapy with allopurinol and colchicine was effective against attacks of gouty arthritis, although amyloidogenic inflammation was not controlled sufficiently. However, there were no cases that described in detail the successful treatment of both diseases. Besides those 14 patients described in literature, we examined one more patient with amyloidosis that is secondary to gout, in whom the protein of amyloid A (AA) had affected the kidneys, intestines, and adrenal glands. The patient has been successfully treated with the combination of canakinumab, prednisone, colchicine and allopurinol.

Conclusion:

Clinicians should be aware that patients may have atypical combinations of diseases like gout and amyloidosis. The obtained results help to explain some pathogenic processes associated with AA-amyloidosis. Further research is necessary to confirm the effectiveness of different treatment options such as lifestyle biologic agents or other medicines with anti-inflammatory properties.

Antitumor Effect and Immune Response of Nanosecond Pulsed Electric Fields in Pancreatic Cancer

Nanosecond pulsed electric fields (nsPEFs) have emerged as a novel and effective strategy for the non-surgical and minimally invasive removal of tumors. However, the effects of nsPEFs treatment on the tumor immune microenvironment remain unknown. In this study, the changes in the morphology and function of pancreatic cancer cells after nsPEFs were assessed and the modifications in the immune profile in pancreatic cancer models were investigated. To this end, electrodes were inserted with different parameters applied to ablate the targeted tumor tissues. Tumor development was found to be inhibited, with decreased volumes post-nsPEFs treatment compared with control tumors (P < 0.05). Hematoxylin and eosin staining showed morphological changes in pancreatic cancer cells, Ki-67 staining confirmed the effects of nsPEFs on tumor growth, and caspase-3 staining indicated that nsPEFs caused apoptosis in the early stages after treatment. Three days after nsPEFs, positron emission tomography demonstrated little residual metabolic activity compared with the control group. Gene expression profiling identified significant changes in immune-related pathways. After treatment with nsPEFs, CD8⁺ T lymphocytes increased. We showed that nsPEFs led to a significant decrease in immune suppressive cells, including myeloid derived suppressor cells, T regulatory cells, and tumor-associated macrophages. In addition, the levels of TNF-α and IL-1β increased (P < 0.05), while the level of IL-6 was decreased (P < 0.05). NsPEFs alleviated the immunosuppressive components in pancreatic cancer stroma, including hyaluronic acid and fibroblast activation protein-α. Our data demonstrate that tumor growth can be effectively inhibited by nsPEFs in vivo. NsPEFs significantly altered the infiltration of immune cells and triggered immune response.

Febuxostat mitigates concanavalin A-induced acute liver injury via modulation of MCP-1, IL-1β, TNF-α, neutrophil infiltration, and apoptosis in mice

AIM

Liver plays a crucial role in innate immunity reactions. This role predisposes the liver to innate-mediated liver injury when uncontrolled inflammation occurs. In this study, the effect of febuxostat administration on acute liver injury induced by concanavalin A (Con A) injection into mouse eye orbital sinus was studied.

MATERIALS AND METHODS

Two doses of febuxostat (10 and 20 mg/kg, orally) were administered either 1 h before or 30 min after the administration of Con A. Febuxostat at a low dose (10 mg/kg) before and after Con A modulated the elevation of serum ALT, liver uric acid, liver myeloperoxidase (MPO), and interleukin-1β (IL-1β) induced by Con A. The same dose of febuxostat before Con A also decreased serum total bilirubin and neutrophil infiltration, as evidenced by flow cytometry and histopathological analysis.

KEY FINDINGS

Febuxostat at a high dose (20 mg/kg) significantly improved serum ALT, AST, albumin, total bilirubin, liver uric acid, MPO, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), interleukin-4 (IL-4), IL-1β, and neutrophil infiltration induced by Con A administration. The results of histopathological examination of liver cells paralleled the observed biochemical improvements. Hepatocyte apoptosis as evidenced by immunohistochemical examination of cleaved caspase-3 was markedly decreased in the febuxostat protection and treatment groups, in a dose-dependent manner SIGNIFICANCE: These results indicate that febuxostat, especially at the higher dose, may be an effective inhibitor of immune reactions evoked by Con A administration.

Antibody-mediated inhibition of syndecan-4 dimerisation reduces interleukin (IL)-1 receptor trafficking and signalling

OBJECTIVE

Syndecan-4 (sdc4) is a cell-anchored proteoglycan that consists of a transmembrane core protein and glucosaminoglycan (GAG) side chains. Binding of soluble factors to the GAG chains of sdc4 may result in the dimerisation of sdc4 and the initiation of downstream signalling cascades. However, the question of how sdc4 dimerisation and signalling affects the response of cells to inflammatory stimuli is unknown.

METHODS

Sdc4 immunostaining was performed on rheumatoid arthritis (RA) tissue sections. Interleukin (IL)-1 induced extracellular signal-regulated kinases (ERK) phosphorylation and matrix metalloproteinase-3 production was investigated. Il-1 binding to sdc4 was investigated using immunoprecipitation. IL-1 receptor (IL1R1) staining on wild-type, sdc4 and IL1R1 knockout fibroblasts was performed in fluorescence-activated cell sorting analyses. A blocking sdc4 antibody was used to investigate sdc4 dimerisation, IL1R1 expression and the histological paw destruction in the human tumour necrosis factor-alpha transgenic mouse.

RESULTS

We show that in fibroblasts, the loss of sdc4 or the antibody-mediated inhibition of sdc4 dimerisation reduces the cell surface expression of the IL-1R and regulates the sensitivity of fibroblasts to IL-1. We demonstrate that IL-1 directly binds to sdc4 and in an IL-1R-independent manner leads to its dimerisation. IL-1-induced dimerisation of sdc4 regulates caveolin vesicle-mediated trafficking of the IL1R1, which in turn determines the responsiveness to IL-1. Administration of antibodies (Ab) against the dimerisation domain of sdc4, thus, strongly reduces the expression IL1R1 on arthritic fibroblasts both in vitro and an animal model of human RA.

CONCLUSION

Collectively, our data suggest that Ab that specifically inhibit sdc4 dimerisation may support anti-IL-1 strategies in diseases such as inflammatory arthritis.

Safety, tolerability and pharmacokinetics and pharmacodynamics of HL2351, a novel hybrid fc-fused interleukin-1 receptor antagonist, in healthy subjects: A first-in-human study

AIMS

We performed a first-in-human study with HL2351, a novel hybrid Fc-fused interleukin (IL)-1 receptor antagonist, to evaluate its tolerability, pharmacokinetics and pharmacodynamics (PD) after a single subcutaneous (SC) administration in healthy subjects.

METHODS

A randomized, double-blind, placebo- and active-controlled, dose-escalation study was conducted. Eligible subjects randomly received a single SC administration of HL2351 (1, 2, 4, 8 and 12 mg/kg) or placebo in a ratio of 8:2. Subjects in the active-controlled group received a single SC administration of anakinra at 100 mg. Serial blood samples were collected for pharmacokinetics and PD analyses. An ex-vivo activation test was performed to evaluate the PD using peripheral blood mononuclear cells treated with IL-1β. Anti-HL2351 antibodies were determined at baseline and 29 days postdose. Tolerability was assessed throughout the study.

RESULTS

HL2351 was eliminated more slowly than anakinra (terminal half-life: 27.21-45.28 vs 3.97 h). Serum concentrations of HL2351 were increased dose-proportionally. The mean apparent clearance of HL2351 were 0.6, 0.66, 0.75, 0.51, 0.65 L/h at 1, 2, 4, 8 and 12 mg/kg, respectively. The percent inhibition of IL-6 expression varied widely (range: 0-92.1%), showing no clear trend or discernible difference between HL2351, anakinra and placebo. HL2351 was well tolerated after a single SC administration.

CONCLUSION

HL2351 was well tolerated and showed linear pharmacokinetic characteristics after a single SC administration at doses up to 12 mg/kg in healthy subjects. HL2351 remained in the body 7-11 times longer than anakinra. HL2351 can be developed as a potential therapeutic alternative to anakinra.

Activation of Toll-Like Receptor 3 Induces Interleukin-1 Receptor Antagonist Expression by Activating the Interferon Regulatory Factor 3

Toll-like receptor 3 (TLR3) is a sensor of endogenous cell necrosis during the process of acute inflammation. Interleukin (IL)-1 receptor antagonist (IL-1Ra) is an anti-inflammatory cytokine and can negatively regulate the pathogenesis of inflammation. However, whether and how activation of TLR3 can regulate IL-1Ra expression has not been clarified. Here, we show that poly(I:C) induces IL-1Ra expression in primarily cultured human fibroblast-like synoviocytes and other types of cells. Induction of IL-1Ra by poly(I:C) was dependent on TLR3, but was independent of melanoma differentiation--associated protein 5 or retinoic acid-inducible gene I. Interferon regulatory factor 3 (IRF3) directly binds to the IL-1Ra promoter and promotes IL-1Ra expression in response to poly(I:C) stimulation. Induction of IL-1Ra by poly(I:C) was abolished by the inhibition of the NF-κB signaling, attenuated by the inhibition of the PI3K-Akt signaling, enhanced by inhibition of the ERK1/2 or MSK1/2 activation, but was independent of the p38 MAPK signaling. Treatment with poly(I:C) or Sendai virus elevated the levels of serum IL-1Ra in wild-type, but not in TLR3-/- or IRF3-/- mice. Our findings may provide new insights into the intrinsic anti-inflammatory function of TLR3 and double-stranded RNA-induced IL-Ra expression by TLR3 and its regulation.

Correlations between Interleukin-33 and -1α Levels in Gingival Crevicular Fluid and Plasma in Patients with Chronic or Aggressive Periodontitis and Disease-free Subjects

Interleukin (IL)-33 is a dual-function protein that may play important roles as both a cytokine and intracellular nuclear factor. It may also function similarly to prototypical alarmin IL-1α, as an endogenous danger signal to alert innate immune system cells to tissue damage during trauma or infection, as it can be released in the extracellular space after endothelial cell damage or mechanical injury. The aim of this study was to determine possible correlations between concentrations of IL-33 and IL-1α in gingival crevicular fluid (GCF) and plasma obtained from healthy patients, those with chronic periodontitis (CP), and those with generalized aggressive periodontitis (GAP) patients. Forty-five patients with an age range of 20-60 years were enrolled and divided into 3 groups: Group H, 30 samples (15 GCF and 15 plasma) from 15 patients with healthy periodontium; Group CP, 30 samples from 15 patients with CP; and Group GAP, 30 samples from 15 patients with GAP. The clinical periodontal parameters investigated in all groups comprised the gingival index score, probing pocket depth, and clinical attachment level. The GCF and plasma levels of IL-33 and IL-1α were quantitated using enzyme linked immunosorbent assay. The mean IL-33 concentrations in GCF and plasma were highest in Group GAP, followed by Group CP, with the lowest in Group H; the difference among them was statistically significant (p<0.05). Concentration of IL-1α followed the same trend as that of IL-33 in GCF, but was lower than detection levels in plasma. The GCF and plasma concentrations of IL-33 correlated with IL-1α concentrations in GCF. Concentrations of IL-33 and IL-1α in GCF varied significantly between healthy patients and those with disease, allowing healthy patients to be distinguished from those with GAP or CP. The results of this study suggest that IL-33 offers a potential inflammatory marker of periodontal disease, similar to IL-1α.

MERS-CoV infection is associated with downregulation of genes encoding Th1 and Th2 cytokines/chemokines and elevated inflammatory innate immune response in the lower respiratory tract

•

MERS-CoV infection downregulates Th1 and Th2 cytokines and chemokines.

•

MERS-CoV infection provokes high levels of IL-1α, IL-1β and IL-8 (CXCL8).

•

Inflammatory cytokines/chemokines correlate with MERS-CoV case fatality rate.

•

Th1/Th2 downregulation may contribute to severe infection and evolution of ARDS.

MERS-CoV, a highly pathogenic virus in humans, is associated with high morbidity and case fatality. Inflammatory responses have a significant impact on MERS-CoV pathogenesis and disease outcome. However, CD4⁺ T-cell induced immune responses during acute MERS-CoV infection are barely detectable, with potent inhibition of effector T cells and downregulation of antigen presentation. The local pulmonary immune response, particularly the Th1 and Th2-related immune response during acute severe MERS-CoV infection is not fully understood. In this study, we offer the first insights into the pulmonary gene expression profile of Th1 and Th2-related cytokines/chemokines (Th1 & Th2 responses) during acute MERS-CoV infection using RT² Profiler PCR Arrays. We also quantified the expression level of primary inflammatory cytokines/chemokines. Our results showed a downregulation of Th2, inadequate (partial) Th1 immune response and high expression levels of inflammatory cytokines IL-1α and IL-1β and the neutrophil chemoattractant chemokine IL-8 (CXCL8) in the lower respiratory tract of MERS-CoV infected patients. Moreover, we identified a high viral load in all included patients. We also observed a correlation between inflammatory cytokines, Th1, and Th2 downregulation and the case fatality rate. Th1 and Th2 response downregulation, high expression of inflammatory cytokines, and high viral load may contribute to lung inflammation, severe infection, the evolution of pneumonia and ARDS, and a higher case fatality rate. Further study of the molecular mechanisms underlying the Th1 and Th2 regulatory pathways will be vital for active vaccine development and the identification of novel therapeutic strategies.

Vitamin D as a Principal Factor in Mediating Rheumatoid Arthritis-Derived Immune Response

Rheumatoid arthritis (RA) is a systemic multifactorial autoimmune disorder. The interactions between diverse environmental and genetic factors lead to the onset of this complex autoimmune disorder. Serum levels of vitamin D (VD) are involved in the regulation of various immune responses. Vitamin D is a key signaling molecule in the human body that maintains calcium as well as phosphate homeostasis. It also regulates the functions of the immune system and, thus, can play a substantial role in the etiology of various autoimmune disorders, including RA. Low serum VD levels have been found to be associated with a higher risk of RA, although this finding has not been replicated consistently. The molecular mechanisms by which VD influences autoimmunity need to be further explored to understand how variation in plasma VD levels could affect the pathogenesis of RA. This mini-review focuses on the influence of VD and its serum levels on RA susceptibility, RA-associated complexities, treatment, and transcriptome products of key proinflammatory cytokines, along with other cytokines that are key regulators of inflammation in rheumatoid joints.

ACPAs promote IL-1β production in rheumatoid arthritis by activating the NLRP3 inflammasome

OBJECTIVES

Anti-citrullinated protein antibodies (ACPAs) are a group of autoantibodies targeted against citrullinated proteins/peptides and are informative rheumatoid arthritis (RA) biomarkers. ACPAs also play a crucial role in RA pathogenesis, and their underlying mechanism merits investigation.

METHODS

Immunohistochemical (IHC) assays were carried out to determine IL-1β levels in ACPA⁺ and ACPA^- RA patients. PBMC-derived monocytes were differentiated into macrophages before stimulation with ACPAs purified from RA patients. The localization and interaction of molecules were analyzed by confocal microscopy, co-IP, and surface plasmon resonance.

RESULTS

In our study, we found that IL-1β levels were elevated in ACPA⁺ RA patients and that ACPAs promoted IL-1β production by PBMC-derived macrophages. ACPAs interacted with CD147 to enhance the interaction between CD147 and integrin β1 and, in turn, activate the Akt/NF-κB signaling pathway. The nuclear localization of p65 promoted the expression of NLRP3 and pro-IL-1β, resulting in priming. Moreover, ACPA stimulation activated pannexin channels, leading to ATP release. The accumulated ATP bound to the P2X7 receptor, leading to NLRP3 inflammasome activation.

CONCLUSIONS

Our study suggests a new hypothesis regarding IL-1β production in RA involving ACPAs, which may be a potential therapeutic target in RA treatment.

Anti-Inflammatory Effects of Aurantio-Obtusin from Seed of Cassia obtusifolia L. through Modulation of the NF-κB Pathway

Aurantio-obtusin, an anthraquinone compound, isolated from dried seeds of Cassia obtusifolia L. (syn. Senna obtusifolia; Fabaceae) and Cassia tora L. (syn. Senna tora). Although the biological activities of Semen Cassiae have been reported, the anti-inflammatory mechanism of aurantio-obtusin, its main compound, on RAW264.7 cells, remained unknown. We investigated the anti-inflammatory effect of aurantio-obtusin on lipopolysaccharide- (LPS)-induced RAW264.7 cells in vitro and elucidated the possible underlying molecular mechanisms. Nitric oxide production (NO) and prostaglandin E₂ (PGE₂) were measured by the Griess colorimetric method and enzyme-linked immunosorbent assay (ELISA), respectively. Protein expression levels of cyclooxygenase 2 (COX-2) were monitored by cell-based ELISA. Interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-α) synthesis were analyzed using ELISA. The mRNA expression of nitric oxide synthase (iNOS), COX-2, and the critical pro-inflammatory cytokines (IL-6 and TNF-α) were detected by quantitative real-time PCR. Aurantio-obtusin significantly decreased the production of NO, PGE₂, and inhibited the protein expression of COX-2, TNF-α and IL-6, which were similar to those gene expression of iNOS, COX-2, TNF-α and IL-6 (p < 0.01). Consistent with the pro-inflammatory gene expression, the Aurantio-obtusin efficiently reduced the LPS-induced activation of nuclear factor-κB in RAW264.7 cells. These results suggested that aurantio-obtusin may function as a therapeutic agent and can be considered in the further development of treatments for a variety of inflammatory diseases. Further studies may provide scientific evidence for the use of aurantio-obstusin as a new therapeutic agent for inflammation-related diseases.

Glucocorticoid receptor in stromal cells is essential for glucocorticoid-mediated suppression of inflammation in arthritis

BACKGROUND

Glucocorticoid (GC) therapy is frequently used to treat rheumatoid arthritis due to potent anti-inflammatory actions of GCs. Direct actions of GCs on immune cells were suggested to suppress inflammation.

OBJECTIVES

Define the role of the glucocorticoid receptor (GR) in stromal cells for suppression of inflammatory arthritis.

METHODS

Bone marrow chimeric mice lacking the GR in the hematopoietic or stromal compartment, respectively, and mice with impaired GR dimerisation (GRdim) were analysed for their response to dexamethasone (DEX, 1 mg/kg) treatment in serum transfer-induced arthritis (STIA). Joint swelling, cell infiltration (histology), cytokines, cell composition (flow cytometry) and gene expression were analysed and RNASeq of wild type and GRdim primary murine fibroblast-like synoviocytes (FLS) was performed.

RESULTS

GR deficiency in immune cells did not impair GC-mediated suppression of STIA. In contrast, mice with GR-deficient or GR dimerisation-impaired stromal cells were resistant to GC treatment, despite efficient suppression of cytokines. Intriguingly, in mice with impaired GR function in the stromal compartment, GCs failed to stimulate non-classical, non-activated macrophages (Ly6Cneg, MHCIIneg) and associated anti-inflammatory markers CD163, CD36, AnxA1, MerTK and Axl. Mice with GR deficiency in FLS were partially resistant to GC-induced suppression of STIA. Accordingly, RNASeq analysis of DEX-treated GRdim FLS revealed a distinct gene signature indicating enhanced activity and a failure to reduce macrophage inflammatory protein (Mip)-1α and Mip-1β.

CONCLUSION

We report a novel anti-inflammatory mechanism of GC action that involves GR dimerisation-dependent gene regulation in non-immune stromal cells, presumably FLS. FLS control non-classical, anti-inflammatory polarisation of macrophages that contributes to suppression of inflammation in arthritis.

Modulation of Inflammatory Arthritis in Mice by Gut Microbiota Through Mucosal Inflammation and Autoantibody Generation

OBJECTIVE

Observations of microbial dysbiosis in patients with rheumatoid arthritis (RA) have raised interest in studying microbial-mucosal interactions as a potential trigger of RA. Using the murine collagen-induced arthritis (CIA) model, we undertook this study to test our hypothesis that microbiota modulate immune responses leading to autoimmune arthritis.

METHODS

CIA was induced by immunization of mice with type II collagen (CII) in adjuvant on days 0 and 21, with arthritis appearing on days 23 and 24. Intestinal microbiota were profiled by 16S ribosomal RNA sequencing every 7 days during the course of CIA, and intestinal mucosal changes were evaluated on days 14 and 35. Then, microbiota were depleted either early (7 days before immunization) or late (day 21 after immunization) by administration of broad-spectrum antibiotics. Disease severity, autoantibody and systemic cytokine production, and intestinal mucosal responses were monitored in the setting of microbial reduction.

RESULTS

Significant dysbiosis and mucosal inflammation occurred early in CIA, prior to visible arthritis, and continued to evolve during the course of disease. Depletion of the microbiota prior to the induction of CIA resulted in an ~40% reduction in disease severity and in significantly reduced levels of serum inflammatory cytokines and anti-CII antibodies. In intestinal tissue, production of interleukin-17A (IL-17A) and IL-22 was delayed. Unexpectedly, microbial depletion during the late phase of CIA resulted in a >50% decrease in disease severity. Anti-CII antibodies were mildly reduced but were significantly impaired in their ability to activate complement, likely due to altered glycosylation profiles.

CONCLUSION

These data support a model in which intestinal dysbiosis triggers mucosal immune responses that stimulate T and B cells that are key for the development of inflammatory arthritis.

Anti-inflammatory activities of essential oil isolated from the calyx of Hibiscus sabdariffa L

Hibiscus sabdariffa Linn., belonging to the family of Malvaceae, is considered to be a plant with health care applications in China. The main purpose of this study was to analyze the composition of its essential oil and assess its potential therapeutic effect on anti-inflammatory activity. A water steam distillation method was used to extract the essential oil from H. Sabdariffa. The essential oil components were determined by gas chromatography/mass spectrometry (GC-MS) analysis and a total of 18 volatile constituents were identified, the majority of which were fatty acids and ester compounds. Biological activity showed that the essential oil extracted from H. Sabdariffa exhibited excellent anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells. The nitric oxide (NO) inhibition rate reached 67.46% when the concentration of the essential oil was 200 μg mL^-1. Further analysis showed that the anti-inflammatory activity of the essential oil extracted from H. Sabdariffa might be exerted through inhibiting the activation of NF-κB and MAPK (JNK and ERK1/2) signaling pathways to decrease NO and pro-inflammatory cytokine (IL-1, IL-6, TNF-α, COX-2, and iNOS) production. Thus, the essential oil extracted from H. Sabdariffa is a good source of a natural product with a beneficial effect against inflammation, and it may be applied as a food supplement and/or functional ingredient.

Pathogenetic insights from the treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic autoimmune disease that causes progressive articular damage, functional loss, and comorbidity. The development of effective biologics and small-molecule kinase inhibitors in the past two decades has substantially improved clinical outcomes. Just as understanding of pathogenesis has led in large part to the development of drugs, so have mode-of-action studies of these specific immune-targeted agents revealed which immune pathways drive articular inflammation and related comorbidities. Cytokine inhibitors have definitively proven a critical role for tumour necrosis factor α and interleukin 6 in disease pathogenesis and possibly also for granulocyte-macrophage colony-stimulating factor. More recently, clinical trials with Janus kinase (JAK) inhibitors have shown that cytokine receptors that signal through the JAK/STAT signalling pathway are important for disease, informing the pathogenetic function of additional cytokines (such as the interferons). Finally, successful use of costimulatory blockade and B-cell depletion in the clinic has revealed that the adaptive immune response and the downstream events initiated by these cells participate directly in synovial inflammation. Taken together, it becomes apparent that understanding the effects of specific immune interventions can elucidate definitive molecular or cellular nodes that are essential to maintain complex inflammatory networks that subserve diseases like rheumatoid arthritis.

Delivery of anti-inflammatory peptides from hollow PEGylated poly(NIPAM) nanoparticles reduces inflammation in an ex vivo osteoarthritis model

Targeted delivery of anti-inflammatory osteoarthritis treatments have the potential to significantly decrease undesirable systemic side effects and reduce required therapeutic dosage. Here we present a targeted, non-invasive drug delivery system to decrease inflammation in an osteoarthritis model. Hollow thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) nanoparticles have been synthesized via degradation of a N,N'-bis(acryloyl)cystamine (BAC) cross-linked core out of a non-degradable pNIPAM shell. Sulfated 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) was copolymerized in the shell to increase passive loading of an anti-inflammatory mitogen-activated protein kinase-activated protein kinase 2 (MK2)-inhibiting cell-penetrating peptide (KAFAK). The drug-loaded hollow nanoparticles were effective at delivering a therapeutically active dose of KAFAK to bovine cartilage explants, suppressing pro-inflammatory interleukin-6 (IL-6) expression after interleukin-1 beta (IL-1β) stimulation. This thermosensitive hollow nanoparticle system provides an excellent platform for the delivery of peptide therapeutics into highly proteolytic environments such as osteoarthritis.

Succinate/NLRP3 Inflammasome Induces Synovial Fibroblast Activation: Therapeutical Effects of Clematichinenoside AR on Arthritis

Clematichinenoside AR (C-AR) is a triterpene saponin isolated from the root of Clematis manshurica Rupr., which is a herbal medicine used in traditional Chinese medicine for the treatment of arthritis. C-AR exerts anti-inflammatory and immunosuppressive properties, but little is known about its action in the suppression of fibroblast activation. Low oxygen tension and transforming growth factor-β (TGF-β1) induction in the synovium contribute to fibrosis in arthritis. This study was designed to investigate the effect of C-AR on synovial fibrosis from the aspects of hypoxic TGF-β1 and hypoxia-inducible transcription factor-1α (HIF-1α) induction. In the synovium of rheumatoid arthritis (RA) rats, hypoxic TGF-β1 induction increased succinate accumulation due to the reversal of succinate dehydrogenase (SDH) activation and induced NLRP3 inflammasome activation in a manner dependent on HIF-1α induction. In response to NLRP3 inflammasome activation, the released IL-1β further increased TGF-β1 induction, suggesting the forward cycle between inflammation and fibrosis in myofibroblast activation. In the synovium of RA rats, C-AR inhibited hypoxic TGF-β1 induction and suppressed succinate-associated NLRP3 inflammasome activation by inhibiting SDH activity, and thereby prevented myofibroblast activation by blocking the cross-talk between inflammation and fibrosis. Taken together, these results showed that succinate worked as a metabolic signaling, linking inflammation with fibrosis through NLRP3 inflammasome activation. These findings suggested that synovial succinate accumulation and HIF-1α induction might be therapeutical targets for the prevention of fibrosis in arthritis.

Leukocyte-poor platelet-rich plasma is more effective than the conventional therapy with acetaminophen for the treatment of early knee osteoarthritis

INTRODUCTION

Knee osteoarthritis (OA) is a degenerative and progressive articular cartilage disease. Infiltration of autologous platelet-rich plasma (PRP) has been proposed as a therapeutic alternative due to the content of biologically active cytokines in PRP. We aimed to compare the clinical response of acetaminophen and intra-articular leukocyte-poor PRP (LP-PRP) in early knee OA.

MATERIALS AND METHODS

A total of 65 patients with clinically and radiographically documented knee OA (grade 1-2) were analyzed. Patients were randomized into two groups: 32 were treated with acetaminophen (500 mg/8 h) over 6 weeks, and 33 received three intra-articular injections of autologous LP-PRP (once every 2 weeks). All patients were evaluated by the Visual Analogue Scale (VAS), the Western Ontario and McMaster Universities (WOMAC) score, and the SF-12 health survey at baseline and 6, 12, and 24 weeks of follow-up. All LP-PRP preparations were analyzed for the platelet, leukocyte, IL-1ra, and TGF-β concentrations.

RESULTS

The decrease in the VAS pain level in the LP-PRP group was greater than that in the acetaminophen group (p < 0.05). Patients treated with LP-PRP showed a sustained improvement in knee function at week 24 (p < 0.01). The SF-12 results only indicated an improvement in quality-of-life in the LP-PRP group at 6, 12, and 24 weeks of follow-up (p < 0.01). Both IL-1ra and TGF-β were detected in the LP-PRP samples (313.8 ± 231.6 and 21,183.8 ± 8556.3 pg/mL, respectively).

CONCLUSIONS

Treatment with LP-PRP injections resulted in a significantly better clinical outcome than did treatment with acetaminophen, with sustained lower EVA and WOMAC scores and improvement in quality-of-life (higher SF-12 score). Therapy with LP-PRP may positively modify the inflammatory joint environment by counteracting IL-1β action.

Effects of IL-1β, IL-6 and IL-8 on erythrocytes, platelets and clot viscoelasticity

Complex interactions exist between cytokines, and the interleukin family plays a fundamental role in inflammation. Particularly circulating IL-1β, IL-6 and IL-8 are unregulated in systemic and chronic inflammatory conditions. Hypercoagulability is an important hallmark of inflammation, and these cytokines are critically involved in abnormal clot formation, erythrocyte pathology and platelet hyper-activation, and these three cytokines have known receptors on platelets. Although these cytokines are always unregulated in inflammation, we do not know how the individual cytokines act upon the structure of erythrocytes and platelets, and which of the viscoelastic clot parameters are changed. Here we study the effects of IL-1β, IL-6 and IL-8 at low physiological levels, representative of chronic inflammation, by using scanning electron microscopy and thromboelastography. All three interleukins caused the viscoelastic properties to display an increased hypercoagulability of whole blood and pathology of both erythrocytes and platelets. The most pronounced changes were noted where all three cytokines caused platelet hyper-activation and spreading. Erythrocyte structure was notably affected in the presence of IL-8, where the morphological changes resembled that typically seen in eryptosis (programmed cell death). We suggest that erythrocytes and platelets are particularly sensitive to cytokine presence, and that they are excellent health indicators.

Interleukin-1β induces fibroblast growth factor 2 expression and subsequently promotes endothelial progenitor cell angiogenesis in chondrocytes

Angiogenesis is an important event in the process of arthritis. Stimulating chondrocytes with IL-1β increased the expression of FGF-2, via the IL-1RI/ROS/AMPK/p38/NF-κB signalling pathway. FGF-2-neutralizing antibody abolished ATDC5-conditional medium-mediated angiogenesis both in vitro and in vivo.

Arthritis is a process of chronic inflammation that results in joint damage. IL (interleukin)-1β is an inflammatory cytokine that acts as a key mediator of cartilage degradation, and is abundantly expressed in arthritis. Neovascularization is one of the pathological characteristics of arthritis. However, the role of IL-1β in the angiogenesis of chondrocytes remains unknown. In the present study, we demonstrate that stimulating chondrocytes (ATDC5) with IL-1β increased the expression of FGF (fibroblast growth factor)-2, a potent angiogenic inducer, and then promoted EPC (endothelial progenitor cell) tube formation and migration. In addition, FGF-2-neutralizing antibody abolished ATDC5-conditional medium-mediated angiogenesis in vitro, as well as its angiogenic effects in the CAM (chick chorioallantoic membrane) assay and Matrigel plug nude mice model in vivo. IHC (immunohistochemistry) staining from a CIA (collagen-induced arthritis) mouse model also demonstrates that arthritis increased the expression of IL-1β and FGF-2, as well as EPC homing in articular cartilage. Moreover, IL-1β-induced FGF-2 expression via IL-1RI (type-1 IL-1 receptor), ROS (reactive oxygen species) generation, AMPK (AMP-activated protein kinase), p38 and NF-κB (nuclear factor κB) pathway has been demonstrated. On the basis of these findings, we conclude that IL-1β promotes FGF-2 expression in chondrocytes through the ROS/AMPK/p38/NF-κB signalling pathway and subsequently increases EPC angiogenesis. Therefore IL-1β serves as a link between inflammation and angiogenesis during arthritis.

Mesenchymal Stem Cell-Derived Interleukin 1 Receptor Antagonist Promotes Macrophage Polarization and Inhibits B Cell Differentiation

The role of interleukin 1 receptor antagonist (IL1RA) in mediating the immunosuppressive effect of mesenchymal stem/stromal cells (MSCs) has been reported in several studies. However, how MSC-derived IL1RA influences the host response has not been clearly investigated. We therefore derived MSCs from the bone marrow of IL1RA knockout mice and evaluated their immunosuppressive effect on different immune cell subsets. IL1RA deficient (IL1RA(-/-) ) or wild type (wt) MSCs inhibited to the same extend the proliferation of T lymphocytes. On the contrary, IL1RA(-/-) MSCs were less effective than wt MSCs to induce in vitro the macrophage polarization from M1 to M2 phenotype secreting IL10 and exerting a suppressive effect on CD4(+) T cells. Moreover compared with wt MSCs, IL1RA(-/-) MSCs did not efficiently support the survival of quiescent B lymphocytes and block their differentiation toward CD19(+) CD138(+) plasmablasts secreting IgG antibodies. The effectiveness of IL1RA secreted by MSCs in controlling inflammation was further shown in vivo using the collagen-induced arthritis murine model. MSCs lacking IL1RA expression were unable to protect mice from arthritic progression and even worsened clinical signs, as shown by higher arthritic score and incidence than control arthritic mice. IL1RA(-/-) MSCs were not able to decrease the percentage of Th17 lymphocytes and increase the percentage of Treg cells as well as decreasing the differentiation of B cells toward plasmablasts. Altogether, our results provide evidence of the key role of IL1RA secreted by MSCs to both control the polarization of macrophages toward a M2 phenotype and inhibit B cell differentiation in vivo.

Flavonoids inhibit COX-1 and COX-2 enzymes and cytokine/chemokine production in human whole blood

Cyclooxygenase 2 (COX-2) and the production of cytokines/chemokines are important targets for the modulation of the inflammatory response. Although a large variety of inhibitors of these pathways have been commercialized, some of those inhibitors present severe side effects, governing the search for new molecules, as alternative anti-inflammatory agents. This study was undertaken to study an hitherto not evaluated group of flavonoids, concerning its capacity to inhibit COX-1 and COX-2 enzymes, as well as to inhibit the production of the cytokines and a chemokine, in a complex matrix involved in the systemic inflammatory process, the blood, aiming the establishment of a structure-activity relationship. The results obtained reveal promising flavonoids for the modulation of the inflammatory process, namely the ones presenting a catechol group in B ring, as some flavonoids were able to simultaneously inhibit the production of inflammatory prostaglandin E2 and pro-inflammatory cytokines.

Protective effects of alginate-chitosan microspheres loaded with alkaloids from Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. (Zuojin Pill) against ethanol-induced acute gastric mucosal injury in rats

Zuojin Pill (ZJP), a traditional Chinese medicine formula, consists of Coptis chinensis Franch. and Evodia rutaecarpa (Juss.) Benth. in a ratio of 6:1 (w/w) and was first recorded in “Danxi’s experiential therapy” for treating gastrointestinal disorders in the 15th century. However, the poor solubility of alkaloids from ZJP restricted the protective effect in treating gastritis and gastric ulcer. The aim of the study was to investigate the protective mechanism of mucoadhesive microspheres loaded with alkaloids from C. chinensis Franch. and E. rutaecarpa (Juss.) Benth. on ethanol-induced acute gastric mucosal injury in rats. Surface morphology, particle size, drug loading, encapsulation efficiency, in vitro drug release, mucoadhesiveness, and fluorescent imaging of the microspheres in gastrointestinal tract were studied. The results showed that the mucoadhesive microspheres loaded with alkaloids could sustain the release of drugs beyond 12 hours and had gastric mucoadhesive property with 82.63% retention rate in vitro. The fluorescence tracer indicated high retention of mucoadhesive microspheres within 12 hours in vivo. The mucoadhesive microspheres loaded with alkaloids could reduce the gastric injury by decreasing the mucosal lesion index, increasing the percentage of inhibition and increasing the amount of mucus in the gastric mucosa in an ethanol-induced gastric mucosal injury rat model. Moreover, the mucoadhesive microspheres loaded with alkaloids reduce the inflammatory response by decreasing the levels of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), downregulating the mRNA expression of inducible nitric oxide synthase, TNF-α, and IL-1β in gastric mucosa. All the results indicate that mucoadhesive microspheres loaded with alkaloids could not only increase the residence time of alkaloids in rat stomach, but also exert gastroprotective effects through reducing the inflammatory response on ethanol-induced gastric mucosal damage. Thus, these microspheres could be developed as a potential controlled release drug for treatment of gastric ulcer.

Chitinase 3-Like 1 Promotes Candida albicans Killing and Preserves Corneal Structure and Function by Controlling Host Antifungal Responses

Chitinase 3-like 1 (CHI3L1) has been shown to play a role in promoting antibacterial responses, decreasing tissue injury, and enhancing pulmonary repair. This study sought to elucidate the role of CHI3L1 in augmenting the corneal innate immune response to Candida albicans infection in an animal model of fungal keratitis. Flagellin applied topically 24 h prior to C. albicans inoculation significantly protected the corneal from C. albicans and induced CHI3L1 expression in C57BL/6 mouse corneas. CHI3L1, however, played a detectable but minor role in flagellin-induced protection. While C. albicans keratitis was more severe in the corneas treated with Chi3l1 small interfering RNA (siRNA), corneas treated with recombinant CHI3L1 before C. albicans inoculation had markedly ameliorated keratitis, reduced fungal load, and decreased polymorphonucleocyte (PMN) infiltration in an interleukin 13 receptor α2 (IL-13Rα2)-dependent manner. CHI3L1 treatment resulted in the induction of the antimicrobial peptides β-defensin 3, CRAMP, and chemokine CXCL10 and its receptor CXCR3 in corneal epithelial cells. Importantly, CHI3L1 administered after C. albicans inoculation also had strong protection against fungal keratitis, suggesting a therapeutic window. This is the first report demonstrating that CHI3L1 is induced during fungal infection, where it acts as an immunomodulator to promote fungal clearance and to regulate antifungal innate immune responses in the cornea.

Effects of PVA coated nanoparticles on human immune cells

Nanotechnology provides new opportunities in human medicine, mainly for diagnostic and therapeutic purposes. The autoimmune disease rheumatoid arthritis (RA) is often diagnosed after irreversible joint structural damage has occurred. There is an urgent need for a very early diagnosis of RA, which can be achieved by more sensitive imaging methods. Superparamagnetic iron oxide nanoparticles (SPION) are already used in medicine and therefore represent a promising tool for early diagnosis of RA. The focus of our work was to investigate any potentially negative effects resulting from the interactions of newly developed amino-functionalized amino-polyvinyl alcohol coated (a-PVA) SPION (a-PVA-SPION), that are used for imaging, with human immune cells. We analyzed the influence of a-PVA-SPION with regard to cell survival and cell activation in human whole blood in general, and in human monocytes and macrophages representative of professional phagocytes, using flow cytometry, multiplex suspension array, and transmission electron microscopy. We found no effect of a-PVA-SPION on the viability of human immune cells, but cytokine secretion was affected. We further demonstrated that the percentage of viable macrophages increased on exposure to a-PVA-SPION. This effect was even stronger when a-PVA-SPION were added very early in the differentiation process. Additionally, transmission electron microscopy analysis revealed that both monocytes and macrophages are able to endocytose a-PVA-SPION. Our findings demonstrate an interaction between human immune cells and a-PVA-SPION which needs to be taken into account when considering the use of a-PVA-SPION in human medicine.

Effect of ebosin on modulating interleukin-1β-induced inflammatory responses in rat fibroblast-like synoviocytes

The interleukin-1β-mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways are involved in the pathogenesis of rheumatoid arthritis. Ebosin, a novel exopolysaccharide (EPS), exhibits anti-inflammatory activity in rat collagen-induced arthritis by suppressing the production of tumor necrosis factor-α, interleukin-6 and interleukin-1β. The aim of the present study was to assess the effects of ebosin on NF-κB and MAPK signaling pathways mediated through interleukin-1β in rat fibroblast-like synoviocytes (FLSs). Western blotting showed decreased production of phosphorylated p38, JNK1, JNK2, IKKα, IKKβ and IκB in the cytoplasm and NF-κB in the nucleus upon ebosin treatment. The DNA-binding activity of NF-κB in the cell nucleus was also inhibited by ebosin treatment, as demonstrated using an electrophoresis mobility gel shift assay. Analysis of the results of the immunofluorescence assay also showed a reduced amount of NF-κB in the nucleus of cells affected by ebosin. These results provided evidence for the effects of ebosin on both interleukin-1β-mediated MAPK and NF-κB signaling pathways in rat FLSs. In addition, enzyme-linked immunosorbent assay demonstrated that ebosin reduces the levels of matrix metalloproteinases MMP-1 and MMP-3 and the chemokines, interleukin-8 and RANTES. Thus, the results of the present study provide further evidence for understanding the medicinal activity of ebosin at a molecular level, therefore nominating this EPS as a potential therapeutic candidate for the treatment of rheumatic arthritis.Cellular & Molecular Immunology advance online publication, 4 May 2015; doi:10.1038/cmi.2015.36.

Discovery of novel 2,5-dioxoimidazolidine-based P2X(7) receptor antagonists as constrained analogues of KN62

Novel 2,5-dioxoimidazolidine-based conformationally constrained analogues of KN62 (1) were developed as P2X7 receptor (P2X7R) antagonists using a rigidification strategy of the tyrosine backbone of 1. SAR analysis of the 2,5-dioxoimidazolidine scaffold indicated that piperidine substitution at the N3 position and no substitution at N1 position were preferable. Further optimization of the substituents at the piperidine nitrogen and the spacer around the skeleton resulted in several superior antagonists to 1, including 1-adamantanecarbonyl analogue 21i (IC50 = 23 nM in ethidium uptake assay; IC50 = 14 nM in IL-1β ELISA assay) and (3-CF3-4-Cl)benzoyl analogue (-)-21w (54 nM in ethidium uptake assay; 9 nM in IL-1β ELISA assay), which was more potent than the corresponding (+) isomer. Compound 21w displayed potent inhibitory activity in an ex vivo model of LTP-induced pain signaling in the spinal cord and significant anti-inflammatory activity in in vivo models of carrageenan-induced paw edema and type II collagen-induced joint arthritis.

Cyr61 participates in the pathogenesis of rheumatoid arthritis by promoting proIL-1β production by fibroblast-like synoviocytes through an AKT-dependent NF-κB signaling pathway

IL-1β plays a major role in the development of rheumatoid arthritis (RA). We previously showed that Cyr61 participates in RA pathogenesis as a proinflammatory factor. Here, we found that the levels of IL-1β and Cyr61 were higher in RA SF than in osteoarthritis (OA) SF. IL-1β mRNA and proIL-1β protein levels were remarkably increased in Cyr61-stimulated FLS; however, IL-1β was hardly detectable in the supernatant. We also found that the level of adenosine triphosphate (ATP) in SF and ST was significantly increased in RA patients and that the level of IL-1β in supernatants from Cyr61-activated FLS increased significantly when we added exogenous ATP to the culture. Mechanistically, Cyr61 induced proIL-1β production in FLS via the AKT-dependent NF-κB signaling pathway, and ATP caused Cyr61-induced proIL-1β to generate IL-1β in a caspase-1-dependent manner. Our results reveal a novel role of Cyr61 in RA that involves the promotion of proIL-1β production in FLS.

Protective effects of baicalin on LPS-induced injury in intestinal epithelial cells and intercellular tight junctions

AIMS

To investigate the protective effects and mechanisms of baicalin on lipopolysaccharide (LPS)-induced injury in intestinal epithelial cells and intercellular tight junctions.

METHODS

IEC-6 cells were stimulated with LPS (1.0 μg/mL), with or without baicalin, for 24 h. The levels of the inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α were determined using ELISA. Quantitative real-time PCR was used for determining the mRNA expression level of claudin-3, occludin, and ZO-1; Western blot and immunofluorescence analysis were used for analyzing the expression level and the distribution patterns of ZO-1 protein.

RESULTS

Pretreatment with baicalin (10.0 μg/mL) improved LPS-stimulated cell viability and repressed IL-6 and TNF-α levels. In addition, pretreatment with baicalin up-regulated mRNA and protein expression levels of ZO-1 and kept the protein intact in IEC-6 cells injured with LPS.

CONCLUSION

Baicalin has the capacity to protect IEC-6 cells and the intercellular tight junctions from LPS-induced injury. The mechanisms may be associated with inhibiting the production of inflammatory cytokines, and up-regulating the mRNA and protein expression of ZO-1.

Comparative studies of paeoniflorin and albiflorin from Paeonia lactiflora on anti-inflammatory activities

CONTEXT

Paeonia lactiflora Pall. (Ranunculaceae) has been used for more than 1000 years in traditional Chinese medicine for the treatment of gynecological problems, cramp, pain, giddiness, and congestion. Paeoniflorin, monoterpene glycosides isolated from P. lactiflora, possesses a variety of pharmacological activities. However, the pharmacological activity of the pharmacological activity of albiflorin, another main monoterpene glycoside, has not been well studied.

OBJECTIVES

The present study investigated the anti-inflammatory activities of paeoniflorin and albiflorin using models of lipopolysaccharides (LPS) induced RAW 264.7 cells.

MATERIALS AND METHODS

Production of nitric oxide (NO) was measured by the Griess colorimetric method. In addition, prostaglandin E2 (PGE2), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) synthesis were analyzed using an enzyme-linked immunosorbent assay (ELISA). The protein expression of cyclooxygenase-2 (COX-2) was detected by a cell-based ELISA. The gene expression levels of inducible nitric oxide synthase (iNOS), COX-2, TNF-α, and IL-6 were detected by quantitative real-time reverse-transcription polymerase chain reaction (real-time RT-PCR).

RESULTS

Compared with the LPS-induced group, the inhibition rates of NO, PGE2, TNF-α, and IL-6 production were 17.61, 27.56, 20.57, and 29.01% by paeoniflorin and 17.35, 12.94, 15.29, and 10.78% by albiflorin. The IC50 values of paeoniflorin and albiflorin on NO production were 2.2 × 10(-4 )mol/L and 1.3 × 10(-2 )mol/L, respectively. The protein expression of COX-2 was reduced by 50.98% with paeoniflorin and 17.21% with albiflorin. The inhibition rates of gene expression of iNOS, COX-2, IL-6, and TNF-α were 35.65, 38.08, 19.72, and 45.19% by paeoniflorin and 58.36, 47.64, 50.70, and 12.43% by albiflorin, respectively.

CONCLUSION

These results show that albiflorin has similar anti-inflammatory effects to paeoniflorin, which provides new evidence that albiflorin can serve as a new chemical marker for the quality control of Paeoniae Radix and the Chinese Pharmacopoeia can be updated.

Negative regulation of the NLRP3 inflammasome by A20 protects against arthritis

Rheumatoid arthritis is a chronic autoinflammatory disease that affects 1-2% of the world's population and is characterized by widespread joint inflammation. Interleukin-1 is an important mediator of cartilage destruction in rheumatic diseases, but our understanding of the upstream mechanisms leading to production of interleukin-1β in rheumatoid arthritis is limited by the absence of suitable mouse models of the disease in which inflammasomes contribute to pathology. Myeloid-cell-specific deletion of the rheumatoid arthritis susceptibility gene A20/Tnfaip3 in mice (A20(myel-KO) mice) triggers a spontaneous erosive polyarthritis that resembles rheumatoid arthritis in patients. Rheumatoid arthritis in A20(myel-KO) mice is not rescued by deletion of tumour necrosis factor receptor 1 (ref. 2). Here we show, however, that it crucially relies on the Nlrp3 inflammasome and interleukin-1 receptor signalling. Macrophages lacking A20 have increased basal and lipopolysaccharide-induced expression levels of the inflammasome adaptor Nlrp3 and proIL-1β. As a result, A20-deficiency in macrophages significantly enhances Nlrp3 inflammasome-mediated caspase-1 activation, pyroptosis and interleukin-1β secretion by soluble and crystalline Nlrp3 stimuli. In contrast, activation of the Nlrc4 and AIM2 inflammasomes is not altered. Importantly, increased Nlrp3 inflammasome activation contributes to the pathology of rheumatoid arthritis in vivo, because deletion of Nlrp3, caspase-1 and the interleukin-1 receptor markedly protects against rheumatoid-arthritis-associated inflammation and cartilage destruction in A20(myel-KO) mice. These results reveal A20 as a novel negative regulator of Nlrp3 inflammasome activation, and describe A20(myel-KO) mice as the first experimental model to study the role of inflammasomes in the pathology of rheumatoid arthritis.

Mechanisms of T-cell immunosuppression by mesenchymal stromal cells: what do we know so far?

Mesenchymal stromal cells (MSCs) are multipotent cells, which can give rise to several cell types including osteoblasts, adipocytes, and chondroblasts. These cells can be found in a variety of adult and fetal tissues, such as bone marrow, adipose tissue, cord blood, and placenta. In recent years, the biological properties of MSCs have attracted the attention of researchers worldwide due to their potential application for treating a series of clinical situations. Among these properties, special attention should be given to the immunoregulatory potential of those cells. MSCs are able to act on all cells of the immune system, which includes the capacity to inhibit the proliferation and function of T-cells. This feature renders them natural candidates to treat several diseases in which cellular immune response is exacerbated. In this review, we outline the main mechanisms by which MSCs immunosuppress T-cell response, focusing on cell-cell contact, secretion of soluble factors, and regulatory T-cell generation. The influence of surface markers in the immunosuppression process and features of MSCs isolated from different sources are also discussed. Finally, the influences of toll-like receptors and cytokines on the inflammatory microenvironment are highlighted regarding the activation of MSCs to exert their immunoregulatory function.