Evidence that cytokines play a role in rheumatoid arthritis

A Novel Hypothetical Approach to Explain the Mechanisms of Pathogenicity of Rheumatic Arthritis

The autoimmune disorder rheumatoid arthritis (RA) is a relapsing and chronic inflammatory disease that affects the synovial cells, cartilage, bone, and muscle. It is characterised by the accumulation of huge numbers of polymorphonuclear neutrophils (PMNs) and macrophages in the synovia. Auto-antibodies are deposited in the joint via the activity of highly cationic histones released from neutrophil extracellular traps (NETs) in a phenomenon termed NETosis. The cationic histones function as opsonic agents that bind to negatively charged domains in autoantibodies and complement compounds via strong electrostatic forces, facilitating their deposition and endocytosis by synovial cells. However, eventually the main cause of tissue damage is the plethora of toxic pro-inflammatory substances released by activated neutrophils recruited by cytokines. Tissue damage in RA can also be accompanied by infections which, upon bacteriolysis, release cell-wall components that are toxic to tissues. Some amelioration of the damaged cells and tissues in RA may be achieved by the use of highly anionic heparins, which can neutralize cationic histone activity, provided that these polyanions are co-administrated with anti-inflammatory drugs such as steroids, colchicine, or methotrexate, low molecular weight antioxidants, proteinase inhibitors, and phospholipase A2 inhibitors.

Myeloid IPMK promotes the resolution of serum transfer-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by widespread joint inflammation, which leads to joint damage, disability, and mortality. Among the several types of immune cells, myeloid cells such as macrophages are critical for controlling the pathogenesis of RA. Inositol phosphates are water-soluble signaling molecules, which are synthesized by a series of enzymes including inositol phosphate kinases. Previous studies revealed actions of inositol phosphates and their metabolic enzymes in the modulation of inflammation such as Toll-like receptor-triggered innate immunity. However, the physiological roles of inositol polyphosphate (IP) metabolism in the regulation of RA remain largely uncharacterized. Therefore, our study sought to determine the role of inositol polyphosphate multikinase (IPMK), a key enzyme for IP metabolism and various cellular signaling control mechanisms, in mediating RA. Using myeloid cell-specific IPMK knockout (KO) mice, arthritis was induced via intraperitoneal K/BxN serum injection, after which disease severity was evaluated. Both wild-type and IPMK KO mice developed similar RA phenotypes; however, conditional deletion of IPMK in myeloid cells led to elevated arthritis scores during the resolution phase, suggesting that IPMK deficiency in myeloid cells impairs the resolution of inflammation. Bone marrow-derived IPMK KO macrophages exhibited no apparent defects in immunoglobulin Fc receptor (FcR) activation, osteoclast differentiation, or resolvin signaling. Taken together, our findings suggest that myeloid IPMK is a key determinant of RA resolution.

Modulation of PTPN2/22 Function by Spermidine in CRISPR-Cas9-Edited T-Cells Associated with Crohn's Disease and Rheumatoid Arthritis

Crohn's Disease (CD) and Rheumatoid Arthritis (RA) share some single nucleotide polymorphisms (SNPs) in protein tyrosine phosphatase non-receptor types 2 and 22 (PTPN2/22). Recently, we reported that clinical samples from CD and RA patients associated with PTPN2:rs478582 or PTPN22:rs2476601 genotypes were linked to overactive immune response and exacerbation of inflammation. Here, we investigated in vitro the effects of these SNPs in Jurkat T-cells using CRISPR-Cas9. All cells were evaluated for PTPN22/22 loss of function and effects on cell response. We measured gene expression via RT-qPCR and cytokines by ELISA. We also measured cell proliferation using a BrdU labeling proliferation ELISA, and T-cell activation using CD-25 fluorescent immunostaining. In PTPN2 SNP-edited cells, PTPN2 expression decreased by 3.2-fold, and proliferation increased by 10.2-fold compared to control. Likewise, expression of PTPN22 decreased by 2.4-fold and proliferation increased by 8.4-fold in PTPN22 SNP-edited cells. IFN-γ and TNF-α secretions increased in both edited cell lines. CD25 expression (cell activation) was 80.32% in PTPN2 SNP-edited cells and 85.82% in PTPN22 SNP-edited cells compared to 70.48% in unedited Jurkat T-cells. Treatment of PTPN2 and PTPN22-edited cells with a maximum 20 μM spermidine restored PTPN2/22 expression and cell response including cell proliferation, activation, and cytokines secretion. Most importantly, the effect of spermidine on edited cells restored normal expression and secretion of IFN-γ and TNF-α. The data clearly demonstrated that edited SNPs in PTPN2 or PTPN22 were associated with reduced gene expression, which resulted in an increase in cell proliferation and activation and overactive immune response. The data validated our earlier observations in CD and RA clinical samples. Surprisingly, spermidine restored PTPN2/22 expression in edited Jurkat T-cells and the consequent beneficial effect on cell response and inflammation. The study supports the use of polyamines dietary supplements for management of CD and in RA patients.

Role of S100A8/A9 for Cytokine Secretion, Revealed in Neutrophils Derived from ER-Hoxb8 Progenitors

S100A9, a Ca²⁺-binding protein, is tightly associated to neutrophil pro-inflammatory functions when forming a heterodimer with its S100A8 partner. Upon secretion into the extracellular environment, these proteins behave like damage-associated molecular pattern molecules, which actively participate in the amplification of the inflammation process by recruitment and activation of pro-inflammatory cells. Intracellular functions have also been attributed to the S100A8/A9 complex, notably its ability to regulate nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. However, the complete functional spectrum of S100A8/A9 at the intracellular level is far from being understood. In this context, we here investigated the possibility that the absence of intracellular S100A8/A9 is involved in cytokine secretion. To overcome the difficulty of genetically modifying neutrophils, we used murine neutrophils derived from wild-type and S100A9^−/− Hoxb8 immortalized myeloid progenitors. After confirming that differentiated Hoxb8 neutrophil-like cells are a suitable model to study neutrophil functions, our data show that absence of S100A8/A9 led to a dysregulation of cytokine secretion after lipopolysaccharide (LPS) stimulation. Furthermore, we demonstrate that S100A8/A9-induced cytokine secretion was regulated by the nuclear factor kappa B (NF-κB) pathway. These results were confirmed in human differentiated HL-60 cells, in which S100A9 was inhibited by shRNAs. Finally, our results indicate that the degranulation process could be involved in the regulation of cytokine secretion by S100A8/A9.

β-Sitosterol-loaded solid lipid nanoparticles ameliorate complete Freund's adjuvant-induced arthritis in rats: involvement of NF-кB and HO-1/Nrf-2 pathway

Rheumatoid arthritis (RA), autoimmune disease that is categorized via chronic inflammation manifestation, obesity, cardiovascular risk and even enhanced the mortality and affect the 0.3 and 1% of population worldwide. The current experimental study was scrutinize the anti-arthritic effect of β-sitosterol loaded solid lipid nanoparticles (SLN) against complete Fruend adjuvant (CFA)-induced arthritis via dual pathway. Double emulsion solvent displacement method was used for the preparation of β-sitosterol solid lipid nanoparticles (SLN). CFA was used to induce arthritis and rats were divided into different groups for 28 days. Biochemical, anti-inflammatory, pro-inflammatory cytokines and inflammatory mediator were estimated, respectively. Receptor activator of nuclear factor kappa-B ligand (RANKL), signal transducer and activator of transcription-3 (STAT3) nuclear factor erythroid 2–related factor 2 (Nrf₂), Heme Oxygenase-1(HO-1) and Nuclear factor-κB (NF-κB) expression were estimated. β-sitosterol-SLN significantly (p < .001) reduced the paw edema, arthritic index and increased the body weight. β-sitosterol-SLN increased the redox status of synovium {reduce the malonaldehyde (MDA) and increase superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT)} level and reduced the cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-2, interleukin-6, interleukin-16, interleukin-17 and increased level of interleukin-10, Transforming growth factor beta (TGF-β). β-sitosterol-SLN significantly (p < .001) reduced the level of cyclooxygenase-2 (COX-2), prostaglandin E₂ (PGE₂), vascular Endothelial Growth Factor (VEGF) and NF-κB. β-sitosterol-SLN significantly increased the expression of HO-1,Nrf₂ and decreased the expression of NF-κB, RANKL, STAT3. In conclusion, β-sitosterol SLN showed the antiarthritic effect via suppression of NF-kB and activation of HO-1/Nrf-2 pathway.

Folate-methotrexate loaded bovine serum albumin nanoparticles preparation: an in vitro drug targeting cytokines overwhelming expressed immune cells from rheumatoid arthritis patients

The study planned to estimate biological parameters linked to rheumatoid arthritis (RA) patients, detecting the influence of MTX and biotherapy treatments on these parameters and synthesizing methotrexate bovine serum albumin nanoparticles linked to folate (FA-MTX-BSA NPs) to reduce the overwhelming expression of inflammatory cytokines. Inflammatory parameters showed significant increases in newly diagnosed and MTX-receiving groups while no changes were observed in the biotherapy-maintained group. MTX-loaded BSA nanoparticles were fabricated by the desolvation method and further linked to activated folic acid to obtain FA-MTX-BSA NPs. FA-MTX-BSA NPs were successfully characterized within the nanoscale range using different screening techniques. FA-MTX-BSA NPs showed an in vitro release in a sustained manner. The potential of MTX, MTX-BSA NPs, and FA-MTX-BSA NPs in inducing cytokine level reduction was detected. Significant decreases in interleukin- 1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) levels were obtained in cultures treated with FA-MTX-BSA NPs compared to the untreated culture in a dose-dependent pattern. Furthermore, FA-MTX-BSA NPs comparing with MTX and MTX-BSA NPs exhibited a significant advanced effect in decreasing cytokines levels. Accordingly, the conjunction of BSA NPs and MTX linked to folate potentially reduced cytokines manifestation in RA.

CX3CL1/fractalkine regulates the differentiation of human peripheral blood monocytes and monocyte-derived dendritic cells into osteoclasts

Osteoclast differentiation is promoted under inflammatory conditions and osteoclasts play a major role in bone destruction in rheumatoid arthritis (RA). Chemokine (C-X3-C motif) ligand 1 (CX3CL1), also known as fractalkine, functions as a chemoattractant and adhesion molecule, and is involved in the pathogenesis of RA. The blockade of CX3CL1 inhibits the migration of macrophages and osteoclast precursor cells into the inflamed synovium. In the present study, we investigated the direct stimulatory effects of CX3CL1 on osteoclast differentiation from human peripheral blood monocytes and monocyte-derived dendritic cells. A stimulation with CX3CL1 significantly promoted osteoclast differentiation from CD16^- monocytes and also monocyte-derived dendritic cells induced by macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL). On the other hand, CD16⁺ monocytes treated with M-CSF and RANKL did not differentiate into osteoclasts, even with CX3CL1. Calcium resorption was significantly increased by monocyte-derived osteoclasts, but not by dendritic cell-derived osteoclasts, following the addition of CX3CL1. The present results suggest that CX3CL1 directly regulates osteoclast differentiation. CX3CL1 may play important roles in the pathogenesis of RA, not only through the accumulation of inflammatory cells, but also through osteoclastogenesis.

Chronic Pain in Patients with Rheumatoid Arthritis

PURPOSE OF REVIEW

Chronic pain is highly prevalent in patients with rheumatoid arthritis (RA) and can cause various physical and psychological impairments. Unfortunately, the appropriate diagnosis of chronic pain syndromes in this population can be challenging because pain may be primary to RA-specific inflammation and/or secondary to other conditions, typically osteoarthritis (OA) and fibromyalgia (FM). This disparity further poses a clinical challenge, given that chronic pain can often be discordant or undetected with standard RA-specific surveillance strategies, including serological markers and imaging studies. In this review, we provide a robust exploration of chronic pain in the RA population with emphasis on epidemiology, mechanisms, and management strategies.

RECENT FINDINGS

Chronic pain associated with RA typically occurs in patients with anxiety, female sex, and elevated inflammatory status. Up to 50% of these patients are thought to have chronic pain despite appropriate inflammatory suppression, typically due to peripheral and central sensitization as well as secondary OA and FM. In addition to the standard-of-care management for OA and FM, patients with RA and chronic pain benefit from behavioral and psychological treatment options. Moreover, early and multimodal therapies, including non-pharmacological, pharmacological, interventional, and surgical strategies, exist, albeit with varying efficacy, to help suppress inflammation, provide necessary analgesia, and optimize functional outcomes. Overall, chronic pain in RA is a difficult entity for both patients and providers. Early diagnosis, improved understanding of its mechanisms, and initiation of early, targeted approaches to pain control may help to improve outcomes in this population.

ZFAS1 knockdown inhibits fibroblast-like synoviocyte proliferation, migration, invasion and inflammation, and promotes apoptosis via miR-3926/FSTL1 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by joint disorders. Long non-coding RNA zinc finger antisense 1 (ZFAS1) is aberrantly expressed in numerous human diseases, including RA. The present study aimed to investigate the functions and underlying mechanisms of ZFAS1 in RA. Reverse transcription-quantitative PCR was performed to determine the expression levels of ZFAS1, microRNA (miR)-3926 and follistatin-like protein 1 (FSTL1). MTT assay, flow cytometric analysis and Transwell assay were performed to examine the proliferation, apoptosis, migration and invasion of fibroblast-like synoviocytes (FLSs), respectively. Western blotting was employed to measure the protein expression levels of cleaved caspase-3, interleukin (IL)-6, IL-1β, tumor necrosis factor-α and FSTL1. Dual-luciferase reporter assay was performed to verify the interaction between miR-3926 and ZFAS1 or FSTL1. The results demonstrated that ZFAS1 and FSTL1 were upregulated, and miR-3926 was downregulated in RA synovial tissues and RA-FLSs. ZFAS1 knockdown suppressed cell proliferation, migration, invasion and inflammatory cytokine production, and induced apoptosis in RA-FLSs. ZFAS1 acted as a sponge for miR-3926, and ZFAS1 overexpression abolished the impact of miR-3926 on the development of RA-FLSs. FSTL1 was a direct target of miR-3926, and the effect of FSTL1 knockdown on the progression of RA-FLSs was rescued by miR-3926 inhibition. Furthermore, ZFAS1 regulated FSTL1 expression levels via sponging miR-3926 in RA-FLSs. In conclusion, ZFAS1 knockdown inhibited RA-FLS proliferation, migration, invasion and inflammatory cytokine production, and induced apoptosis in RA via the miR-3926/FSTL1 axis.

Duchesnea indica Extract Attenuates Coal Fly Ash-Induced Inflammation in Murine Alveolar Macrophages through the NF-Kappa B Pathway

Duchesnea indica is known as false strawberry, is found in East Asia, and has numerous biological properties. The aim of this study was to investigate the anti-inflammatory effect of Duchesnea indica extract (DIE) on coal fly ash- (CFA-) induced inflammation in murine alveolar macrophages (MH-S). Following the induction of inflammation in MH-S cells by CFA, nitric oxide (NO) was measured to evaluate the anti-inflammatory property of DIE. Cell viability and inflammatory gene expression were analyzed using polymerase chain reaction (PCR). The inflammatory pathway in MH-S cells was determined via western blotting and immunofluorescence (IF) analysis. Finally, the major components of the DIE were identified and separated through ultra-performance liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS) analysis. Our results showed that the DIE dose-dependently inhibited the CFA-induced NO production in MH-S cells. Moreover, the DIE could suppress the CFA-induced proinflammatory mediators, such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). In addition, the inhibitory effect of the DIE on proinflammatory cytokines, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α), was detected with PCR. Moreover, the effect of the DIE on the nuclear factor-κB (NF-κB) pathway in CFA-activated MH-S cells was measured via western blotting. Furthermore, the inhibition of the phosphorylated NF-κB (p-NF-κB) translocation was analyzed using IF assay. The findings of this study indicated that the DIE potentially inhibited the CFA-induced inflammation by blocking the NF-κB inflammatory signaling pathway in MH-S cells and that the DIE might contain favorable anti-inflammatory compounds which may be effective in attenuating lung inflammation.

Rationally designed TNF-α inhibitors: Identification of promising cytotoxic agents

Design and synthesis of new indole derivatives as tumor growth inhibiting agents via inhibiting the TNF-α is described. The preliminary results showed the inhibition of LPS induced production of NO, TNF-α and IL-6 by these compounds out of which compounds 2d and 2g exhibited appreciable cytotoxicity against the 60 cell lines panel of human cancer. The rationale behind the design of the molecules and the results of their biological studies are presented. 2009 Elsevier Ltd. All rights reserved.

Serum Tumor Necrosis Factor-Alpha as a Competent Biomarker for Evaluation of Disease Activity in Early Rheumatoid Arthritis

Aim The cytokines particularly tumor necrosis factor-alpha (TNF-α) have a substantial role in the pathophysiology of rheumatoid arthritis (RA). The goal of this study was to evaluate the role of serum TNF-α as a competent biomarker of disease activity in RA and to assess the correlation of serum TNF-α with DAS28-ESR (disease activity score-erythrocyte sedimentation rate in 28 joints) and other markers expressed in serum of RA patients. Methodology The study was conducted from May 2020 to October 2020 after approval from the Ethical Review Committee of Ziauddin University. This cross-sectional study included 90 diagnosed cases of RA from 30 to 65 years with the complaint of arthralgia. Patients from the rheumatology clinic were enrolled in the study by a non-probability consecutive sampling technique. Informed consent was taken from each patient and they were assessed through a set of questions based upon disability in the performance of daily activities due to RA. Evaluation of serum levels of anti-cyclic citrullinated peptide (ACCP), rheumatoid factor (RF), erythrocyte sedimentation rate, and TNF-α were done by enzyme-linked immunosorbent assay (ELISA). Patients were segregated into groups based upon DAS28-ESR with erythrocyte sedimentation rate as an inflammatory marker. The Kruskal Wallis test was applied for the comparison of different variables in these groups. Spearman correlation was applied for the association between different variables. Multiple variable analysis was performed to assess the predictability of disease activity by serum markers included in the study. Results The results of our study disclosed a significant difference in ACCP, TNF-α, tender joint count of 28 joints (TJ-28), swollen joint count of 28 joints (SJ-28), and health assessment questionnaire-disability index (HAQ-DI) in disease activity groups. A significant correlation of serum TNF-α with DAS28-ESR in RA patients was observed. Conclusion This study illustrated a significant correlation of serum TNF-α with DAS28-ESR in RA patients. We found that expression of serum TNF-α may intensify the inflammatory activity in early RA, therefore, RA patients must be screened for this cytokine to monitor that disease activity could be useful for patients undergoing anti-TNF therapy.

Expression of the myeloid inhibitory receptor CLEC12A correlates with disease activity and cytokines in early rheumatoid arthritis

The myeloid inhibitory receptor CLEC12A negatively regulates inflammation. Reduced CLEC12A expression enhances inflammation in CLEC12A knock-out mice with collagen antibody-induced arthritis. Moreover, CLEC12A internalisation augments human neutrophil activation. We thus postulated that CLEC12A expression on circulating myeloid cells of rheumatoid arthritis patients is associated with disease manifestations. Cell-surface, CLEC12A receptor expression was determined on circulating neutrophils and monocytes of eRA patients and of healthy donors. Generalized estimating equations model, Student’s t-test and Spearman’s correlations were performed to compare CLEC12A expression between groups and test its association with disease activity and clinical parameters. Plasma cytokines were measured by multiplex immunoassay. Patients with reduced neutrophil or monocyte CLEC12A expression at baseline and at 3 months have an increased simple disease activity index. Low baseline CLEC12A expression also correlates with a higher SDAI at 6 months. In contrast, positive correlations were observed between baseline CLEC12A expression and several cytokines. Moreover, neutrophil and monocyte CLEC12A expression is significantly higher in early rheumatoid arthritis patients at baseline than healthy controls. Circulating neutrophil and monocyte CLEC12A expression correlates with disease activity at baseline and is predictive of SDAI at later stages of the disease indicative of a regulatory role for CLEC12A in RA.

Biomarker Approach Towards Rheumatoid Arthritis Treatment

Rheumatoid arthritis is an auto-immune disorder, recognized by cartilage as well as bone destruction, which causes irreversible joint deformities, which further results in functional limitations in the patient. Genes like HLA-DRB1 and PTPN22 are likely implicated in the genetic predisposition of rheumatoid arthritis pathology. The first and foremost clinical manifestation in a person with rheumatoid arthritis is joint destruction followed by cartilage and bone destruction caused by cell-cell interactions. The cell-cell interactions are thought to be initialized through the contact of antigen-presenting cells (APC) with CD4+ cells, leading to the progression of the disease. APC includes a complex of class ІІ major histocompatibility complex molecules along with peptide antigens and binds to the receptors present on the surface of T-cells. Further, the activation of macrophages is followed by the release of various pro-inflammatory cytokines such as IL-1 and TNF-α, which lead to the secretion of enzymes that degrade proteoglycan and collagen, which in turn, increase tissue degradation. Biomarkers like IL-6, IL-12, IL-8 and IL-18, 14-3-3η, RANKL, IFN-γ, IFN-β and TGF-β have been designated as key biomarkers in disease development and progression. The study of these biomarkers is very important as they act as a molecular indicator of pathological processes that aggravate the disease.

Correlation Between Level of Interleukin-37 and Rheumatoid Arthritis Progression

Background

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease that primarily affects joints. Interleukin-37 (IL-37) is an anti-inflammatory cytokine that is known to suppress immune response and inflammation. The objective of this study is to evaluate the correlation between level of IL-37 and RA progression using the disease activity score in 28 joints (DAS-28).

Methods

A total of 87 RA patients were separated into 4 groups based on the DAS28, referred to as the remission, mild, moderate and severe groups. 18 healthy volunteers were also included. Serum level of IL-37 and IL-37 mRNA expression level in peripheral blood mononuclear cells (PBMCs) in each individual participant as well as IL-37 mRNA expression level in synovial cells were assessed to explore their correlation with RA progression.

Results

Serum level of IL-37 and IL-37 mRNA expression levels in both PBMCs and synovial cells were all positively correlated with the severity of RA as reflected by the DAS28. Receiver operating characteristic (ROC) analysis revealed area under curve (AUC) values of 1, 0.5262 and 0.7789 for the three parameters.

Conclusion

Our results suggest that serum IL-37 level and mRNA expression levels of IL-37 in PBMCs and synovial cells are correlated with the severity of RA in a Chinese population.

Activation of the Nrf2/HO-1 signaling pathway by dimethyl fumarate ameliorates complete Freund's adjuvant-induced arthritis in rats

The nuclear factor erythroid 2-related factor (Nrf2) signaling pathway has recently emerged as a novel therapeutic target in treating various diseases. Therefore, the present study aimed to assess the protective role of the Nrf2 activator, dimethyl fumarate (DMF) in the complete Freund's adjuvant (CFA)- induced arthritis model. DMF (25, 50, and 100 mg/kg) and dexamethasone (2 mg/kg) were orally administered for 14 days. Pain-related tests, paw volume, and arthritic scores were measured weekly. Serum TNF-α, IL-1β, cyclic citrullinated peptide (CCP), C-reactive protein (CRP), and rheumatoid factor (RF) levels were estimated. Nitrite, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH), catalase (CAT), and myeloperoxidase (MPO) levels were also evaluated. NF-κB, Nrf2, HO-1, and COX-2 levels were estimated in the joint tissue. DMF treatment exerted anti-arthritic activity by enhancing the nociceptive threshold, improving arthritis scores, and reducing paw edema. Also, DMF suppressed changes in oxidative stress markers and inflammatory mediators and enhanced Nrf2 and HO-1 levels in CFA-injected rats. These findings indicate that the anti-arthritic activity of DMF may be mediated by the activation of the Nrf2/HO-1 pathway, which reduced oxidative damage and inflammation.

Identification of the specific microRNAs and competitive endogenous RNA mechanisms in osteoporosis

Objective

Osteoporosis and osteoarthritis are metabolic skeletal disorders. This study aimed to identify specific networks of competitive endogenous RNA (ceRNA) in osteoporosis that differ from those in osteoarthritis.

Methods

The dataset GSE74209 was downloaded from the Gene Expression Omnibus, and differentially expressed microRNAs (DEmiRNAs) in osteoporotic samples and osteoarthritic samples were identified. After predicting target genes and linked long noncoding (lnc)RNAs, ceRNA networks of DEmiRNAs were constructed. The nodes that overlapped between ceRNA networks and the Comparative Toxicogenomics Database were selected as key candidates.

Results

Fifteen DEmiRNAs (including 2 downregulated and 13 upregulated miRNAs) were identified in osteoporotic samples versus osteoarthritic samples; these targeted 161 genes and linked to 60 lncRNAs. The ceRNA network consisted of 6 DEmiRNAs, 63 target genes, and 53 lncRNAs. After searching the Comparative Toxicogenomics Database and mining the literature, 2 lncRNAs (MALAT1 and NEAT1), 2 DEmiRNAs (hsa-miR-32-3p, downregulated; and hsa-miR-22-3p, upregulated) and 6 genes (SP1, PTEN, ESR1, ERBB3, CSF1R, and CDK6) that relate to cell death, growth, and differentiation were identified as key candidates separating osteoporosis from osteoarthritis.

Conclusions

Two miRNA–ceRNA networks (including NEAT1/MALAT1-hsa-miR-32-3p-SP1/FZD6 and NEAT1/MALAT1-hsa-miR-22-3p-PTEN/ESR1/ERBB3/CSF1R/CDK6) might have crucial and specific roles in osteoporosis.

Objective and noninvasive biochemical markers in rheumatoid arthritis: where are we and where are we going?

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects approximately 1% of the adult population. RA is multi-factorial, and as such our understanding of the molecular pathways involved in the disease is currently limited. An increasing number of studies have suggested that several molecular phenotypes (i.e. endotypes) of RA exist, and that different endotypes respond differently to various treatments. Biochemical markers may be an attractive means for achieving precision medicine, as they are objective and easily obtainable.

AREAS COVERED

We searched recent publications on biochemical markers in RA as either diagnostic or prognostic markers, or as markers of disease activity. Here, we provide a narrative overview of different classes of markers, such as autoantibodies, citrulline products, markers of tissue turnover and cytokines, that have been tested in clinical cohorts or trials including RA patients.

EXPERT OPINION

Although many biochemical markers have been identified and tested, few are currently being used in clinical practice. As more treatment options are becoming available, the need for precision medicine tools that can aid physicians and patients in choosing the right treatment is growing.

miR-216a-5p Suppresses the Proliferation, Invasion and Migration of Fibroblast-Like Synoviocyte in Rheumatoid Arthritis by Targeting Zinc Finger and BTB Domain-Containing Protein 2 (ZBTB2)

MicroRNAs have been reported to be associated with the initiation and progression of rheumatoid arthritis (RA). miR-216a-5p, one of the miRNAs, is involved in cancer cell proliferation, invasion and migration. However, the role of miR-216a-5p in RA remains to be explored. The expressions of miR-216a-5p and zinc finger and BTB domain-containing protein 2 (ZBTB2) in fibroblast-like synoviocytes (FLS) of RA or healthy controls were detected by qRT-PCR and western blot analysis. Transfection of overexpressed and silenced miR-216a-5p were performed to explore the functional role of miR-216a-5p in RA-FLS. Cell Counting Kit-8 (CCK-8) assay and transwell assay were employed to assess cell proliferation and cell invasion, respectively. Moreover, luciferase reporter assay was executed to verify the combination of miR-216a-5p and ZBTB2. The results showed that miR-216a-5p expression in RA-FLS was downregulated than healthy controls. Overexpres-sion of miR-216a-5p inhibited RA-FLS cell proliferation, invasion and migration, while miR-216a-5p silencing revealed the opposite results. In addition, ZBTB2 was identified to be a direct target of miR-216a-5p in RA-FLS and its expression was higher than that in healthy controls. Rescue experiments revealed that ZBTB2 overexpression reversed the effects of miR-216a-5p on the proliferation, invasion and migration of RA-FLS. These data indicated the suppressive role of miR-216a-5p in RA-FLS via the regulation of ZBTB2, suggesting that miR-216a-5p and ZBTB2 may be the new targets for the treatment of RA.

Sustained Hypoxia Suppresses Joint Destruction in a Rat Model of Rheumatoid Arthritis via Negative Feedback of Hypoxia Inducible Factor-1α

Hypoxia inducible factor (HIF)-1α has been implicated in the pathogenesis of rheumatoid arthritis (RA). HIF-1α, which is expressed in hypoxia, is reversely suppressed in sustained hypoxia. Here, we investigated the inhibitory effect of hypoxia on arthritis by controlling HIF-1α. Rheumatoid fibroblast-like synoviocyte MH7A cells were cultured in a hypoxic incubator for up to 72 h to evaluate the expression of HIF-1. Furthermore, collagen-induced arthritis (CIA) model rats were maintained under 12% hypoxia in a hypoxic chamber for 28 days to evaluate the effect on arthritis. In MH7A cells, HIF-1α protein level increased at 3 h, peaked at 6 h, and subsequently decreased in a time-dependent manner. The transcription of pro-inflammatory cytokines increased at 1 h; however, they decreased after 3 h (p < 0.05). Deferoxamine-mediated activation of HIF-1α abolished the inhibitory effect of sustained hypoxia on pro-inflammatory cytokines. In the rat CIA model, the onset of joint swelling was delayed and arthritis was suppressed in the hypoxia group compared with the normoxia group (p < 0.05). Histologically, joint destruction was suppressed primarily in the cartilage. Thus, sustained hypoxia may represent a new safe, and potent therapeutic approach for high-risk patients with RA by suppressing HIF-1α expression.

Effect of Moxibustion on β-EP and Dyn Levels of Pain-Related Indicators in Patients with Rheumatoid Arthritis

Background

Rheumatoid arthritis (RA) is a systemic immunodeficiency disease characterized by persistent synovial inflammation, pannus formation, and bone and cartilage destruction, resulting in joint malformations and function decline.

Objective

The purpose of this study is to evaluate the effect of moxibustion on clinical symptoms and levels of pain-related indicators beta-endorphin (β-EP) and dynorphin (Dyn) in patients with RA and to explore the potential anti-inflammatory and analgesic mechanisms of moxibustion in RA treatment.

Methods

A total of 64 patients with RA who met the inclusion criteria were randomly and equally classified into the control and treatment groups. The control group received conventional treatment (oral methotrexate, folate, or leflunomide prescribed for a long time). The treatment group was treated with moxibustion at ST36 (Zusanli), BL23 (Shenshu), and Ashi points with respect to the control group. Patients' clinical symptoms and routine inspection indexes (rheumatoid factor [RF], erythrocyte sedimentation rate [ESR], and C-reactive protein [CRP]) were recorded before and after treatment. Serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), β-EP, and Dyn were determined by enzyme-linked immunosorbent assay (ELISA). The software SPSS24.0 was used for statistical analysis.

Results

(1) Compared with the pretreatment result, both of the two groups' clinical symptoms and routine inspection indexes (RF, ESR, and CRP) improved (P < 0.05), and the improvement of clinical symptoms in the treatment group outperformed that in the control group (P < 0.05). (2) TNF-α and IL-1β levels decreased significantly in the treatment group after treatment (P < 0.01), while no significant difference was observed in the control group (P > 0.05). (3) β-EP and Dyn levels in the treatment group were significantly increased after treatment (P < 0.01, P < 0.01), but the control group showed no significant difference (P > 0.05, P > 0.05). It is worth mentioning that the serum TNF-α, IL-1β, β-EP, and Dyn levels between the two groups were significantly different after 8 weeks of treatment (P < 0.05). (4) Differences in the serum β-EP and Dyn levels in the patients of the treatment group were correlated with TNF-α and IL-1β levels after treatment, and the correlation was mainly negative (r < 0).

Conclusion

Moxibustion can improve joint pain in patients with RA using conventional western medicine. One of the mechanisms may affect the serum β-EP and Dyn levels by downregulating the inflammatory factors to play an anti-inflammatory and analgesic role.

CCL25 and CCR9 is a unique pathway that potentiates pannus formation by remodeling RA macrophages into mature osteoclasts

This study elucidates the mechanism of CCL25 and CCR9 in rheumatoid arthritis (RA). RA synovial fluid (SF) expresses elevated levels of CCL25 compared to OA SF and plasma from RA and normal. CCL25 was released into RA SF by fibroblasts (FLS) and macrophages (MΦs) stimulated with IL-1β and IL-6. CCR9 is also presented on IL-1β and IL-6 activated RA FLS and differentiated MΦs. Conversely, in RA PBMCs neither CCL25 nor CCR9 are impacted by 3-month longitudinal TNF inhibitor therapy. CCL25 amplifies RA FLS and monocyte infiltration via p38 and ERK phosphorylation. CCL25-stimulated RA FLS secrete potentiated levels of IL-8 which is disrupted by p38 and ERK inhibitors. CCL25 polarizes RA monocytes into nontraditional M1 MΦs that produce IL-8 and CCL2. Activation of p38 and ERK cascades are also responsible for the CCL25-induced M1 MΦ development. Unexpectedly, CCL25 was unable to polarize RA PBMCs into effector Th1/Th17 cells. Consistently, lymphokine like RANKL was uninvolved in CCL25-induced osteoclastogenesis; however, this manifestation was regulated by osteoclastic factors such as RANK, cathepsin K (CTSK), and TNF-α. In short, we reveal that CCL25/CCR9 manipulates RA FLS and MΦ migration and inflammatory phenotype in addition to osteoclast formation via p38 and ERK activation.

4-Phenylbutyric acid, a potent endoplasmic reticulum stress inhibitor, attenuates the severity of collagen-induced arthritis in mice via inhibition of proliferation and inflammatory responses of synovial fibroblasts

4-Phenylbutyric acid (4-PBA) exerts potent pharmacological effects, including anti-inflammatory properties, via inhibition of endoplasmic reticulum (ER) stress. However, it is not known whether 4-PBA attenuates the severity of rheumatoid arthritis. The present study aimed to determine whether the inhibition of ER stress by 4-PBA ameliorated experimentally induced arthritis. The proliferation of synovial fibroblasts (SFs) and expression of matrix metalloproteinases (MMPs) were evaluated in the presence of interleukin (IL)-1β with or without 4-PBA. The effect of 4-PBA on the phosphorylation of Mitogen-activated protein kinase (MAPK) and the activation of Nuclear factor-κB (NF-κB) in IL-1β-stimulated SFs was assessed. In an in vivo study, the effects of 4-PBA were investigated using DBA/1 mice with collagen-induced arthritis (CIA). Clinical, histological, and serological assessments of CIA treated with 4-PBA were performed to determine the therapeutic effect of 4-PBA. In vitro, 4-PBA inhibited the proliferation and expression of IL-1β-stimulated SFs and MMP-1 and MMP-3 through the suppression of both the phosphorylation of MAPKs and NF-κB in IL-1β-stimulated SFs. The 4-PBA treatment markedly attenuated the severity of arthritis in CIA mice. The 4-PBA treatment ameliorated joint swelling and the degree of bone erosion and destruction and decreased the level of inflammatory cytokines and MMP-3 and Cox-2. Furthermore, remarkable improvements in histopathological findings occurred in 4-PBA-treated mice. These findings suggested that 4-PBA could attenuate the severity of arthritis in CIA mice by partially blocking the phosphorylation of MAPKs and the activation of NF-κB in SFs. Thus, through the inhibition of ER stress, 4-PBA may be a potent agent for the treatment of RA.

In vitro anti-inflammatory potential of marine macromolecules cross-linked bio-composite scaffold on LPS stimulated RAW 264.7 macrophage cells for cartilage tissue engineering applications

Biomaterials serve as an integral component of tissue engineering. They are designed to provide architectural framework of native extracellular matrix so as to encourage cell growth and eventual tissue regeneration. Naturally occurring biopolymers as scaffolds offer options for cartilage tissue engineering due to anti-inflammatory, biocompatibility, biodegradability, low toxicity of degradation by-products and plasticity in processing into a variety of material formats. Here we studied in vitro anti-inflammatory potential of marine macromolecules cross-linked bio-composite scaffold composed of hydroxyapatite, alginate, chitosan and fucoidan named as HACF on LPS stimulated RAW 264.7 macrophage cells. The effects of HACF on the viability of RAW264.7 cells, nitrite level, intracellular ROS as well as the mRNA levels of NF-κB, iNOS, COX-2, TNF-α, IL-1β and IL-6 were examined in LPS induced RAW264.7 macrophage cells. The results revealed that HACF hydrogel scaffold exerts anti-inflammatory effect by inhibiting the production of ROS, suppress NF-kB translocation to the nucleus and thereby inhibiting the production of inflammatory mediators. Hence, our results confirm that HACF has a strong anti-oxidant capacity to inhibit inflammation associated gene expression by suppressing NF-kB signaling pathway. It clearly reveals the anti-oxidant and anti-inflammatory effect of HACF hydrogel scaffold on LPS induced RAW 264.7 cells.

Macrophage 3D migration: A potential therapeutic target for inflammation and deleterious progression in diseases

Macrophages are heterogeneous cells that have different physiological functions, such as chemotaxis, phagocytosis, endocytosis, and secretion of various factors. All physiological functions of macrophages are integral to homeostasis, immune defense and tissue repair. However, in several diseases, macrophages are recruited from the blood towards inflammatory sites. This process is called macrophage migration, which promotes deleterious disease progression. Macrophage migration is a key player in many inflammatory diseases, autoimmune diseases and cancers because it contributes to the accumulation of proinflammatory factors, the destruction of tissues and the development of tumors. Therefore, macrophage migration is proposed to be a potential therapeutic target. Macrophages migrate between two-dimensional (2D) and three-dimensional (3D) environments, implying that distinct migratory features and mechanisms are involved. Compared with the 2D migration of macrophages, 3D migration involves more complex variations in cellular morphology and dynamics. The structure of the extracellular matrix, a key factor, is modified in diseases that influence macrophage 3D migration. Macrophage 3D migration relates to disease pathology. Research that focuses on macrophage 3D migration is an emerging field and was reviewed in this article to indicate the molecular and cellular mechanisms of macrophage migration in 3D environments and to provide potential targets for controlling disease progression associated with this migration.

The Effect of Epicatechin-(4β-8)-Catechin on Some Biomarkers of Fatigue in Packed Donkeys (Equus Asinus) during the Dry Season in Northern Nigeria

Overworking and overloading of donkeys may cause fatigue. The experiment aims to determine the effects of epicatechin-(4β-8)-catechin (EEC) on some fatigue biomarkers in packed donkeys during the dry season. 10 jacks, aged between four and five years were used for the study. Five were given EEC in feed seven days before packing (test), while another five were given feed only (control). Blood samples collected for biochemical analyses were analyzed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), total antioxidant capacity (TAC), creatine kinase (CK) and tumor necrosis factor-alpha (TNF-α). The SOD activity increased significantly (P < 0.05) in the test group during the cold-dry season after packing. The values of TAC during the packing period were significantly (P < 0.05) higher in test group during the hot-dry season. The TNF-α concentration was higher (P > 0.05) in the control group especially one-hour on route. The CK activity was significantly (P < 0.05) higher in the control donkeys during the hot-dry season. In conclusion, packing donkeys during the dry season resulted in fatigue, but EEC served as an anti-fatigue agent.

Association between dementia and systemic rheumatic disease: A nationwide population-based study

Objectives

Systemic rheumatic disease is characterized by autoimmunity and systemic inflammation and affects multiple organs. Few studies have investigated whether autoimmune diseases increase the risk of dementia. Herein, we evaluate the relationship between systemic rheumatic disease and dementia through a population-based study using the Korean National Health Insurance Service (NHIS) claims database.

Methods

We conducted a nationwide population-based study using the Korean NHIS database, consisting of individuals who submitted medical claims from 2002–2013. Dementia was defined as having an acetylcholinesterase inhibitors (AChEIs) prescription along with symptoms satisfying the Alzhemier’s disease (AD) International Classification of Diseases (ICD)-10 codes (F00 or G30), or vascular dementia (VaD; ICD-10 or F01) criteria. Control subjects were matched to the dementia patients by age and sex. The study group was limited to those diagnosed with rheumatic disease at least 6 months prior to diagnosis of dementia. Rheumatic disease was defined by the following ICD-10 codes: Rheumatoid arthritis (RA: M05), Sjögren’s syndrome (SS: M35), systemic lupus erythematosus (SLE: M32), and Behcet’s disease (BD: M35.2).

Results

Of the 6,028 dementia patients, 261 (4.3%) had RA, 108 (1.6%) had SS, 12 (0.2%) had SLE, and 6 (0.1%) had BD. SLE history was significantly higher in dementia patients (0.2%) than in controls (0.1%) and was associated with dementia (odds ratio [OR], 2.48; 95% confidence interval [CI], 1.19–5.15). In subgroup analysis, SLE significantly increased dementia risk, regardless of dementia type (AD: OR, 2.29; 95% CI, 1.06–4.91; VaD: OR, 4.54; 95% CI, 1.36–15.14). However, these associations were not sustained in the mild CCI or elderly group.

Conclusion

SLE was independently associated with a higher risk of dementia, including AD and VaD when compared to the control group, even after adjustment. SLE patients (<65 years old) are a high-risk group for early vascular dementia and require screening for early detection and active prevention.

Plasma interleukin-21 levels and genetic variants are associated with susceptibility to rheumatoid arthritis

Background

Rheumatoid Arthritis (RA) is a chronic inflammatory condition characterized by autoantibodies development and an elevated spectrum of pro-inflammatory cytokines. Previous reports highlighted a relationship between IL-21and the pathogenesis of RA. Although elevated IL-21 levels have been reported in RA patients, the association of common IL-21 genetic variants with a predisposition to RA development in the Chinese population lacks.

Materials and methods

Five hundred and fourteen Chinese subjects (healthy controls: 303 and rheumatoid arthritis patients: 211) were enrolled in the study. Clinical data of patients were collected from medical records, and patients were treated as per the guidelines. Common single nucleotide polymorphisms in the IL-21 gene (rs907715, rs2221903, rs2055979 and rs6822844) were genotyped by TaqMan SNPs genotyping method. IL-21 level in plasma of RA patients and healthy subjects was measured by ELISA.

Results

The plasma level of IL-21 was significantly higher in subjects with rheumatoid arthritis relative to healthy controls (p < 0.0001). A positive correlation was observed between IL-21 level and DAS28 score, indicating the association of the cytokine with the worsening of the disease (Spearman r = 0.61, p < 0.0001). The prevalence of AA genotype (rs2055979) was significantly higher in RA subjects than in the controls (p < 0.0001, χ2 = 34.73, OR = 4.34, 95% CI = 2.623 to 7.219). Furthermore, elevated plasma IL-21 was observed in the rs2055979-AA genotype compared to CC type (p < 0.0001).

Conclusion

IL-21 plays a crucial function in rheumatoid arthritis pathogenesis. IL-21 rs2055979 polymorphism is associated with IL-21 plasma levels and is predisposed to RA development in the Chinese population.

Rheumatoid cachexia: the underappreciated role of myoblast, macrophage and fibroblast interplay in the skeletal muscle niche

Although rheumatoid arthritis affects 1% of the global population, the role of rheumatoid cachexia, which occurs in up to a third of patients, is relatively neglected as research focus, despite its significant contribution to decreased quality of life in patients. A better understanding of the cellular and molecular processes involved in rheumatoid cachexia, as well as its potential treatment, is dependent on elucidation of the intricate interactions of the cells involved, such as myoblasts, fibroblasts and macrophages. Persistent RA-associated inflammation results in a relative depletion of the capacity for regeneration and repair in the satellite cell niche. The repair that does proceed is suboptimal due to dysregulated communication from the other cellular role players in this multi-cellular environment. This includes the incomplete switch in macrophage phenotype resulting in a lingering pro-inflammatory state within the tissues, as well as fibroblast-associated dysregulation of the dynamic control of the extracellular matrix. Additional to this endogenous dysregulation, some treatment strategies for RA may exacerbate muscle wasting and no multi-cell investigation has been done in this context. This review summarizes the most recent literature characterising clinical RA cachexia and links these features to the roles of and complex communication between multiple cellular contributors in the muscle niche, highlighting the importance of a targeted approach to therapeutic intervention.

Ethyl acetate extract of Tibetan medicine Rhamnella gilgitica ameliorated type II collagen-induced arthritis in rats via regulating JAK-STAT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Rhamnella gilgitica Mansf. et Melch. (སེང་ལྡེང་།, RG) is a traditional Tibetan medicinal plant that is currently grown throughout Tibet. According to the theory of Tibetan medicine, RG is efficient for removing rheumatism, reducing swelling, and relieving pain. Hence, it has been used for the treatment of rheumatoid arthritis (RA) in Tibet for many years. However, there are no previous reports on the anti-RA activities of ethyl acetate extract of RG (RGEA).

AIM OF THE STUDY

This study aimed to explore the anti-RA effect and mechanism of RGEA on collagen-induced arthritis (CIA) in rats.

MATERIALS AND METHODS

The CIA model was established in male Wister rats by intradermal injection of bovine type II collagen and Complete Freund's Adjuvant at the base of the tail and left sole, respectively. The rats were orally administered with RGEA (9.71, 19.43, or 38.85 mg/kg) for 23 days. The body weight, swelling volume, arthritis index score, thymus and spleen indices, and pathological changes were observed to evaluate the effect of RGEA on RA. Furthermore, the inflammatory cytokines in serum, such as interleukin1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), interleukin6 (IL-6), interleukin17 (IL-17), interferon-γ (INF-γ), interleukin4 (IL-4), and interleukin10 (IL-10) were measured by enzyme linked immunosorbent assay (ELISA) to explore the anti-inflammatory effects of RGEA. The terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining was used to examine apoptosis. Finally, the protein and gene expression of B-cell lymphoma-2-associated X (Bax), B-cell lymphoma 2 (Bcl-2), Caspase3, janus-activated kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signaling1 (SOCS1), and 3 (SOCS3) in synovial tissue were detected using immunohistochemistry and real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

After the treatment with RGEA, the body weight of rats was restored, both the arthritis index and paw swelling were suppressed, and spleen and thymus indices were decreased. RGEA reduced the inflammatory cells and synovial hyperplasia in the synovial tissue of the knee joint, and suppressed bone erosion. Meanwhile, RGEA decreased the levels of IL-1β, IL-6, IL-17, TNF-α, and INF-γ, while increased the levels of IL-4 and IL-10. TUNEL fluorescence apoptosis results confirmed that RGEA obviously promoted the apoptosis of synovial cells. Further studies showed that RGEA inhibited the proteins and mRNAs expression of JAK2 and STAT3 as well as increased the proteins and mRNAs expression of SOCS1 and SOCS3. In addition, RGEA upregulated the expression of Bax and Caspase3, and downregulated the expression of Bcl-2.

CONCLUSION

The anti-RA effectof RGEA might be related to the promotion of apoptosis and inhibition of inflammation, which regulated the JAK-STAT pathway.

Roles of leptin on the key effector cells of rheumatoid arthritis

Leptin, an adipokine sharing structural characteristics of the long-chain helical cytokine family with the crucial role as a regulator in energy homeostasis, has been paid more and more attention to its immunoregulatory function. Emerging evidence has indicated the roles of leptin on autoimmune diseases such as systemic lupus erythematous (SLE), multiple sclerosis (MS), rheumatoid arthritis (RA) and psoriasis, implying that leptin may be involved in autoimmune disorders. It is very definite that there exists immunocyte dysfunction in RA patients. Growing data has manifested that leptin is increased in both serum and synovial fluid of RA patients compared to healthy controls, suggesting leptin probably takes part in the pathogenesis of RA. The aim of this review is to discuss about what we currently know with regard to the role of leptin in immune system and its effects on RA crucial cells. To clarify the role of leptin in the pathogenesis of RA is beneficial to both the treatment and medical study.

The Role of Natural Killer Cells in Autoimmune Diseases

Natural killer (NK) cells, the large granular lymphocytes differentiated from the common lymphoid progenitors, were discovered in early 1970’s. They are members of innate immunity and were initially defined by their strong cytotoxicity against virus-infected cells and by their important effector functions in anti-tumoral immune responses. Nowadays, NK cells are classified among the recently discovered innate lymphoid cell subsets and have capacity to influence both innate and adaptive immune responses. Therefore, they can be considered as innate immune cells that stands between the innate and adaptive arms of immunity. NK cells don’t express T or B cell receptors and are recognized by absence of CD3. There are two major subgroups of NK cells according to their differential expression of CD16 and CD56. While CD16⁺CD56^dim subset is best-known by their cytotoxic functions, CD16^-CD56^bright NK cell subset produces a bunch of cytokines comparable to CD4⁺ T helper cell subsets. Another subset of NK cells with production of interleukin (IL)-10 was named as NK regulatory cells, which has suppressive properties and could take part in immune-regulatory responses. Activation of NK cells is determined by a delicate balance of cell-surface receptors that have either activating or inhibitory properties. On the other hand, a variety of cytokines including IL-2, IL-12, IL-15, and IL-18 influence NK cell activity. NK-derived cytokines and their cytotoxic functions through induction of apoptosis take part in regulation of the immune responses and could contribute to the pathogenesis of many immune mediated diseases including ankylosing spondylitis, Behçet’s disease, multiple sclerosis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus and type-1 diabetes. Dysregulation of NK cells in autoimmune disorders may occur through multiple mechanisms. Thanks to the rapid developments in biotechnology, progressive research in immunology enables better characterization of cells and their delicate roles in the complex network of immunity. As NK cells stand in between innate and adaptive arms of immunity and “bridge” them, their contribution in inflammation and immune regulation deserves intense investigations. Better understanding of NK-cell biology and their contribution in both exacerbation and regulation of inflammatory disorders is a requisite for possible utilization of these multi-faceted cells in novel therapeutic interventions.

Role of natural products in alleviation of rheumatoid arthritis-A review

Rheumatoid arthritis (RHA) is one of the most prevalent complex, chronic, inflammatory diseases, manifested by elevated oxidative stress and inflammatory biomarkers. Prolonged administration of NSAIDs, steroids, and DMARDs, used in the treatment of RHA, is associated with deleterious side effects. This necessitates the urge of new and safe approaches for RHA management, based on the complementary and alternative system of medicine. Documented evidences have suggested that supplementation with nutritional, dietary, and herbal components; can play a crucial role as an adjuvant, in the alleviation of the RHA symptoms, through their influence on the pathological inflammatory processes. Dietary phenolic compounds, flavonoids, carotenoids, and alkaloids with their ability to modulate prooxidant and pro-inflammatory pathways, have been effective in delaying the arthritic disease progression. Moreover, in scientific explorations, herbs containing phenolic compounds, alkaloids, carotenoids flavonoids, spices such as ginger, turmeric, Ayurvedic formulations, different diets such as Mediterranean diet, vegan diet, beverages, and oils such as sesame oil, rice bran oil, vitamins, and probiotics are proven to modulate the action of inflammatory molecules, involved in RHA pathology. Subsequently, the purpose of this review article is to summarize various in vitro, in vivo, and clinical studies in RHA, which have documented remarkable insights into the anti-inflammatory, antioxidant, analgesic, and immunomodulatory, bone erosion preventing properties of dietary, nutritional, and herbal components with the focus on their molecular level mechanisms involved in RHA. Even though major findings were derived from in vitro studies, several in vivo and clinical studies have established the use of diet, herbal, and nutritional management in RHA treatment. PRACTICAL APPLICATIONS: Thickening of the synovial membrane, bone erosion, and cartilage destruction is known to trigger rheumatoid arthritis causing inflammation and pain in bone joints. Continuous intake of NSAIDs, steroids, and DMARD therapy are associated with detrimental side effects. These side effects can be overcome by the use of dietary, nutritional, and herbal interventions based on the complementary and alternative therapy. This concept portrays the food components and other natural components having the potential to promote health, improve general well-being, and reduce the risk of RHA.

Microbiota-Derived Metabolites, Indole-3-aldehyde and Indole-3-acetic Acid, Differentially Modulate Innate Cytokines and Stromal Remodeling Processes Associated with Autoimmune Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the synovial joints. Inflammation, new blood vessel formation (angiogenesis) and bone resorption (osteoclastogenesis) are three key processes involved in the joint damage and deformities of arthritis. Various gut microbiota-derived metabolites are implicated in RA pathogenesis. However, there is barely any information about the impact of two such metabolites, indole-3-aldehyde (IAld) and indole-3-acetic acid (I3AA), on arthritis-related processes. We conducted a comparative analysis of IAld and I3AA using established cell-based models to understand how they might influence RA pathogenesis. Although structurally similar, the bioactivities of these two metabolites were profoundly different. IAld but not I3AA, inhibited the expression of pro-inflammatory cytokines (IL-1β and IL-6) in RAW 264.7 (RAW) cells stimulated with heat-killed M. tuberculosis sonicate (Mtb) and lipopolysaccharide (LPS). IAld also exhibited pro-angiogenic activity and pro-osteoclastogenic activity. In contrast, I3AA exhibited anti-angiogenic activity on endothelial cell tube formation but had no effect on osteoclastogenesis. Both IAld and I3AA have been proposed as aryl hydrocarbon receptor (AhR) agonists. Use of CH-223191, an inhibitor of the AhR, suppressed the anti-angiogenic activity of I3AA but failed to mitigate the effects of IAld. Further investigation of the anti-inflammatory activities of IAld and I3AA in LPS-treated RAW cells indicated that inhibition of MyD88-dependent activation of NF-κB and MAPK pathways was not likely involved. Our results suggest that the relative bioavailability of these indole derivatives may differentially impact RA progression and possibly other diseases that share similar cellular processes.

Curcumin Supplementation Enhances Bone Marrow Mesenchymal Stem Cells to Promote the Anabolism of Articular Chondrocytes and Cartilage Repair

Mesenchymal stem cells derived from bone marrows (BMSCs) and curcumin derived from turmeric were used for osteoarthritis (OA) treatment, respectively. We invested the effects of curcumin supplementation for BMSC therapeutic effects. In vitro, rat BMSCs were identified by dual-immunofluorescent staining of CD44 and CD90, and flow cytometry. Primary articular chondrocytes were identified by toluidine blue staining and immunofluorescent staining of Col2a1. EdU incorporation, migration assay, real-time quantitative polymerase chain reaction, and Western blot analyses were performed to evaluate the alterations of chondrocytes cocultured with BMSCs. In vivo, the rat model of OA was established by monoiodoacetic acid. After intra-articular injection of allogeneic BMSCs, articular cartilage damage and OA progression were evaluated by histological staining, and Osteoarthritis Research Society International and Mankin score evaluation. Although curcumin alone did not improve cell viability of primary articular chondrocytes, it promoted proliferation and migration of chondrocytes when cocultured with BMSCs. Meanwhile, the expression of anabolic genes in chondrocytes was remarkably increased both at mRNA and protein levels. In OA rats, curcumin and BMSCs cooperated to greatly promote articular cartilage repair and retard OA progression. Therefore, curcumin supplementation enhanced the BMSC function for the proliferation and migration of articular chondrocytes, and anabolic gene expression of extracellular matrix in articular chondrocytes in vitro, and the generation of articular cartilage in vivo. Our study shed light on the potential clinical application of curcumin cooperated with BMSCs in cartilage repair for OA treatment.

Factors of Progression and Occurrence of Atherosclerosis in Rheumatoid Arthritis

Aim      To determine in a prospective study factors of progressive atherosclerotic lesion of blood vessels in patients with rheumatoid arthritis (RA).Material and methods  This prospective study included 124 patients with RA and suspected ischemic heart disease (IHD) and 30 patients with IHD (comparison group) aged 58 [52; 63] years. On enrollment to the study and at 3 years of follow-up, all patients underwent clinical and instrumental examination according to European and Russian guidelines for diagnosis and treatment of stable IHD (2013), including coronography as indicated. For all RA patients of the comparison group, risk factors (RF) were evaluated, including arterial hypertension, smoking, excessive body weight, family history of cardiovascular diseases (CVD), diabetes mellitus, and dyslipidemia. The following laboratory data were evaluated: blood count; biochemistry, including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), rheumatoid factor (RhF), cyclic citrullinated peptide antibodies, and high-sensitivity C-reactive protein (hsCRP). Proinflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF- α), were measured in RA patients once, at 3 years of follow-up.Results Incidence of FRs for CVD was similar in RA patients and in the comparison group. Median RA duration before inclusion into the study was 11 years, and median DAS28 index score was 3.8. Incidence of dyslipidemia due to increased TC, LDL-C, and HDL-C was higher for RA patients at baseline. The LDL-C goal (&lt;1.8 mmol/l) was achieved only in 3 (10 %) patients of the comparison group and 10 (8 %) RA patients. RA patients had higher levels of the inflammation indexes, hsCRP (0.75 mg/dl vs. 0.16 mg/dl; p&lt;0.05) and erythrocyte sedimentation rate (ESR) (15 mm/h vs. 11.5 mm/h; p&lt;0.05). In the RA group at baseline, atherosclerotic plaques with carotid artery (CTA) stenosis of 20% or more were found in 94 (77 %) patients; in 3 of them, CA stenosis was &gt;50%. Patients with RA frequently had unchanged or slightly changed coronary arteries (CA) (47% of patients), and less frequently they had hemodynamically significant multi-arterial coronary atherosclerotic lesions (7 % vs. 57 % of patients in comparison group). At 37.5 months, 21 (23 %) of 94 RA patients had progressive atherosclerosis in CA and/or CTA; 12 (13 %) RA patients had only progressive CA atherosclerosis; 7 (8 %) had only progressive CTA atherosclerosis; and 2 (2 %) had simultaneous progression of CA and CTA atherosclerosis. Two groups of RA patients were formed, with the progression of atherosclerosis (n=21) and without the progression of atherosclerosis (n=69). RFs for the development/progression of atherosclerosis in RA patients included smoking, family history of CVD, and duration of the disease. Levels of lipids did not differ. Levels of proinflammatory cytokines (IL-1β, IL-6, TNF-α) were higher in RA patients with progressive atherosclerosis. No effects of the anti-rheumatic therapy on the progression of atherosclerosis were observed.Conclusion      Progression of atherosclerosis in RA remains in disease with low and moderate activity during the anti-rheumatic and hypolipidemic treatment. The development of atherosclerosis in RA is determined by lipid, inflammatory, and immune disorders.

Nutraceuticals against Oxidative Stress in Autoimmune Disorders

Antioxidant mechanisms are constituted of enzymes, endogenous, and non-enzymatic, exogenous, which have the role of counterbalancing oxidative stress. Intake of these compounds occurs in the diet. Vegetables, plants, and fruits contain a wide range of alkaloids, polyphenols, and terpenoids which are called “phytochemicals”. Most of these substances are responsible for the positive properties of fruits and vegetables, which are an essential part of a healthy life with roles in ameliorating chronic illnesses and favoring longevity. Nutraceuticals are substances contained in a food or fragment of it influencing health with positive effects on health helping in precenting or treating disorders. We conducted a review illustrating the principal applications of nutraceuticals in autoimmune disorders. Literature reported several studies about exogenous dietary antioxidant supplementation in diverse autoimmune diseases such as rheumatoid arthritis, lupus, diabetes, and multiple sclerosis. In these pathologies, promising results were obtained in some cases. Positive outcomes were generally associated with a reduction of oxidative stress parameters and a boost to antioxidant systems, and sometimes with anti-inflammatory effects. The administration of exogenous substances through food derivates or dietary supplements following scientific standardization was demonstrated to be effective. Further bias-free and extended studies should be conducted that include ever-increasing oxidative stress biomarkers.

Total Saponins from Nigella glandulifera Seeds Ameliorate Adjuvant-Induced Rheumatoid Arthritis in Rats by Inhibition of an Inflammatory Response and Bone Erosion

Rheumatoid arthritis (RA) is a widespread inflammatory disease whose clinical manifestations are joint swelling, pain, and disability, affecting approximately 1% of individuals worldwide. Conventional anti-RA drugs currently used in clinic have severe side effects. The present study is aimed at investigating the antiarthritic effects of total saponins from Nigella glandulifera seeds (TSNGS) in rats with adjuvant-induced rheumatoid arthritis (AIA). Arthritis score, paw swelling, and body weight were monitored throughout the period of TSNGS treatment. The histopathological features and levels of cytokines, including IFN-γ, TNF-α, IL-1β, IL-4, IL-6, IL-10, and IL-17A, and OPG/RANKL signaling, were measured to determine the amelioration by TSNGS and its potential mechanisms on the inflammatory response and bone erosion. The differentiation of regulatory T cells (Tregs) in serum was assessed by flow cytometry. The results demonstrate that TSNGS at 10 mg/kg, 50 mg/kg, and 250 mg/kg inhibited AIA-induced clinical score, paw swelling, and histological changes. TSNGS reduced the immune-inflammatory reaction by restoring the secretion and expression of inflammatory cytokines and elevating the proportion of CD4+ CD25+ Tregs, accompanied by an increase in transcription factor Foxp3 levels. TSNGS also displayed bone protection by upregulation of the OPG/RANKL pathway. Collectively, TSNGS inhibited arthritis in AIA rats and so represents a potential novel treatment for RA.

Cognitive Decline in Rheumatoid Arthritis: Insight into the Molecular Pathogenetic Mechanisms

Cognitive decline refers to a deterioration of intellectual and learning abilities and related memory problems, and is often associated with behavioral alterations, which prevents sufferers from carrying out the most common daily activities, such as maintaining normal productive interpersonal relationships, communicating, and leading an autonomous life. Numerous studies have highlighted the association between cognitive decline and autoimmune disorders, including rheumatoid arthritis (RA). RA is a chronic, inflammatory, autoimmune disease that involves systems and organs other than the bones and joints, with varying severity among patients. Here, we review the studies investigating the link between cognitive decline and RA, focusing on the main molecular pathogenetic mechanisms involved. The emerging body of data suggests that clinical, psychological, and biological factors may contribute to the pathogenesis of cognitive decline in RA, including cardiovascular complications, chronic pain, depression, inflammatory factors, changes in hormone levels, drug side effects, and genetics. Further studies are warranted in order to fully clarify the basis underlying the association between cognitive decline and RA and to find new possible diagnostic strategies and therapeutic targets for RA patients.

Roflumilast Reduced the IL-18-Induced Inflammatory Response in Fibroblast-Like Synoviocytes (FLS)

Pro-inflammatory cytokines, such as the IL-18-induced inflammatory response and associated damage in fibroblast-like synoviocytes (FLS), play an important role in the pathogenesis of rheumatoid arthritis (RA). Roflumilast, an inhibitor of phosphodiesterase-4 (PDE-4), has been licensed for the treatment of chronic obstructive pulmonary disease (COPD). However, it is unknown whether roflumilast possesses a protective effect against the IL-18-induced inflammatory response in FLS. We found that roflumilast attenuated IL-18-induced oxidative stress by reducing the production of reactive oxygen species and malondialdehyde (MDA) in MH7A fibroblast-like synoviocytes (FLS). Additionally, roflumilast prevented IL-18-induced expressions and secretions of pro-inflammatory cytokines such as IL-6, IL-8, and TNF-α. Importantly, we found that roflumilast inhibited IL-18-induced expressions of chemokines such as CCL5, CXCL9, and CXCL10. Further, roflumilast inhibited the expression of extracellular matrix degradative enzymes, such as matrix metalloproteinase-3 (MMP-3) and MMP-13. Mechanistically, we found that roflumilast suppressed the activation of the transcriptional factor AP-1 and NF-κB. Our results suggest that roflumilast might be a potential therapeutic agent for the treatment of RA.

Phenolic Compounds Impact on Rheumatoid Arthritis, Inflammatory Bowel Disease and Microbiota Modulation

Non-communicable chronic diseases (NCDs) are nowadays the principal cause of death, especially in most industrialized nations. These illnesses have increased exponentially with the consumption of diets very high in fat and sugar, not to mention stress and physical inactivity among other factors. The potential impact of suboptimal diets on NCDs’ morbidity and mortality rates brings to the forefront the necessity for a new way of improving dietary habits. The literature provides extensive scientific work that presents evidence that phenolic compounds from diets have antioxidant, anti-inflammatory and antiproliferative activities that impact human health. Gut microbiota modulation by some phenolic compounds leads to favorable changes in abundance, diversity, and in the immune system. However, polyphenol’s limited bioavailability needs to be overcome, highlighting their application in new delivery systems and providing their health benefits in well-established ways such as health maintenance, treatment or adjuvant to conventional pharmacological treatments. In this context, novel dietary approaches, including new food supplements, have emerged to prevent diseases and preserve health.

Shared development of targeted therapies among autoimmune and inflammatory diseases: a systematic repurposing analysis

Background:

Pathogenic inflammatory pathways are largely shared between different autoimmune and inflammatory diseases (AIDs). This offers the potential to develop a given targeted therapy in several AIDs.

Methods:

We analyzed two clinical trials registries (ClinicalTrials.gov and EU Clinical Trials Register) to identify the targeted therapies whose development is shared between at least two of the most common AIDs [rheumatoid arthritis (RA), spondyloarthritis (SpA), cutaneous psoriasis (cPso), inflammatory bowel diseases (IBD), systemic lupus erythematosus (SLE), primary Sjögren’s syndrome (pSS), systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIM), giant cell arteritis (GCA), and multiple sclerosis (MS)] using an in-depth repurposing analysis.

Results:

We identified 142 shared targeted therapies. The four diseases in which shared targeted therapies were the most numerous were RA (n = 92), cPso (n = 67), IBD (n = 58), and SLE (n = 56). The two clusters of diseases between which the overlap of targeted therapies was the most important were RA and SLE as well as RA, SpA, cPso, and IBD. The targeted therapies which were shared by five diseases or more were abatacept, ustekinumab, rituximab, anakinra, etanercept, infliximab, secukinumab, tofacitinib, alemtuzumab, tocilizumab, adalimumab, apremilast, baricitinib, belimumab, brodalumab, filgotinib, and upadacitinib. The most frequently targeted molecules and pathways were (by descending frequency): JAK-STAT pathways, Th17 axis, TNF-α, IL-6, costimulation molecules, BAFF, CD20, BTK, chemokines and integrins, IL-1, and type I interferon.

Conclusion:

Many targeted therapies are developed in several AIDs, reflecting the overlap of pathogenic pathways and potential of drug repurposing. This suggests that a revision of the current, clinically based classification of AIDs towards a more mechanistic-based taxonomy might be relevant.

Identification of differentially expressed genes, signaling pathways and immune infiltration in rheumatoid arthritis by integrated bioinformatics analysis

Background

The disability rate associated with rheumatoid arthritis (RA) ranks high among inflammatory joint diseases. However, the cause and potential molecular events are as yet not clear. Here, we aimed to identify differentially expressed genes (DEGs), pathways and immune infiltration involved in RA utilizing integrated bioinformatics analysis and investigating potential molecular mechanisms.

Materials and methods

The expression profiles of GSE55235, GSE55457, GSE55584 and GSE77298 were downloaded from the Gene Expression Omnibus database, which contained 76 synovial membrane samples, including 49 RA samples and 27 normal controls. The microarray datasets were consolidated and DEGs were acquired and further analyzed by bioinformatics techniques. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of DEGs were performed using R (version 3.6.1) software, respectively. The protein-protein interaction (PPI) network of DEGs were developed utilizing the STRING database. Finally, the CIBERSORT was used to evaluate the infiltration of immune cells in RA.

Results

A total of 828 DEGs were recognized, with 758 up-regulated and 70 down-regulated. GO and KEGG pathway analyses demonstrated that these DEGs focused primarily on cytokine receptor activity and relevant signaling pathways. The 30 most firmly related genes among DEGs were identified from the PPI network. The principal component analysis showed that there was a significant difference between the two tissues in infiltration immune.

Conclusion

This study shows that screening for DEGs, pathways and immune infiltration utilizing integrated bioinformatics analyses could aid in the comprehension of the molecular mechanisms involved in RA development. Besides, our study provides valuable data related to DEGs, pathways and immune infiltration of RA and may provide new insight into the understanding of molecular mechanisms.

Acetazolamide ameliorates the severity of collagen-induced arthritis in rats: Involvement of inducing synovial apoptosis and inhibiting Wnt/β-catenin pathway

We previously revealed that the overexpression of synovial aquaporin 1 (AQP1) aggravated collagen-induced arthritis (CIA) in rats via regulating β-catenin signaling. This study was to demonstrate the therapeutic effect of acetazolamide (AZ, an AQP1 inhibitor) on rat CIA and explored its underlying mechanisms. Paw swelling, arthritis index, pathological assessments, and serum levels of collagen type II (Col II) antibody, IL-1β and TNF-α were measured to evaluate the anti-arthritic effect of AZ on rat CIA. Ki67 immunohistochemistry and TUNEL assay were performed to reveal the anti-proliferative and pro-apoptotic effects of AZ on synovial cells in vivo. The protein levels of apoptosis-related genes and Wnt/β-catenin pathway key members were detected by western blot. We found that AZ treatment on CIA rats could inhibit paw swelling, reduce arthritis index, alleviate the pathologic changes of ankle joint and decrease the serum levels of Col II antibody, TNF-α and IL-1β. AZ could reduce Ki67 expression and increase apoptosis index in CIA synovial tissues by reducing Bcl-2 protein level, increasing Bax and caspase 3 protein levels and normalizing Bcl-2/Bax ratio. Moreover, AZ could reduce the protein levels of Wnt1, β-catenin, p-GSK-3β (Ser9), c-myc, cyclin D1 and MMP9, while increase GSK-3β protein level in CIA synovial tissues. Importantly, these mentioned effects of AZ (60 mg/kg) on CIA rats could be reversed by the combined use of lithium chloride (LiCl), an activator of Wnt/β-catenin pathway. In short, AZ exerted potent anti-arthritic effects on CIA rats by inducing synovial apoptosis and inhibiting Wnt/β-catenin pathway.

A comparative study on the anti-inflammatory effect of angiotensin-receptor blockers & statins on rheumatoid arthritis disease activity

Background & objectives

: Rheumatoid artherits (RA) is a refractory disease and the imbalance between pro- and anti-inflammatory cytokines in favor of pro-inflammatory cytokines has been implicated in pathogenesis of RA. In this context, the aim of the present study was to compare the anti-inflammatory and antioxidant effects of candesartan, an angiotensin-receptor blocker, and atorvastatin in RA patients.

Methods

: In this single-blinded parallel randomized placebo controlled study, the patients recruited between December 2017 and May 2018 were categorized into three groups: group 1 included 15 RA patients who served as control group and received traditional therapy (+ placebo); group 2 included 15 RA patients who received traditional therapy + candesartan (8 mg/day); and group 3 included 15 patients who received traditional therapy + atorvastatin (20 mg/day) for three months. Clinical status in RA patients was evaluated by Disease Activity Score 28 (DAS28), Health Assessment Questionnaire-Disability Index (HAQ-DI) and morning stiffness before and three months after treatment. All groups were subjected to biochemical analysis of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), tumour necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and malondialdehyde (MDA) before and three months after treatment.

Results

: Both candesartan and atorvastatin treated groups showed significant decrease in serum levels IL-1β and TNF-α, acute-phase reactants (CRP and ESR), number of swollen joint and patient global assessment. This was also associated with improvement in disease activity and quality of life regarding DAS28 and HAQ-DI as compared to baseline data and the control group. Atorvastatin group showed significant decrease in the serum level of oxidative stress marker (MDA).

Interpretation & conclusions

: Both candesartan and atorvastatin showed anti-inflammatory effect and immunomodulatory effects leading to improvement in clinical status and disease activity in RA patients. However, atorvastatin was superior to candesartan through its anti-oxidant effect.

Polyherbal formula SC-E3 inhibits rheumatoid arthritis activity in a mouse model of type-II collagen-induced arthritis

OBJECTIVE

SC-E3 is a polyherbal formula that contains five medicinal herbs used frequently in traditional herbal medicine. In our previous study, we demonstrated the antioxidant and anti-inflammatory effects of SC-E3. The present study examined the effects of SC-E3 in a mouse model of type-II collagen-induced arthritis (CIA).

METHODS

In vivo, male DBA/1J mice were immunized by intradermal injection of bovine type-II collagen and complete or incomplete Freund's adjuvant, to induce arthritis. SC-E3 was orally administered daily for 23 days. In vitro, bone marrow-derived macrophages (BMMs) were treated with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL) in the absence or presence of SC-E3.

RESULTS

Administrations of SC-E3 were found to have anti-arthritic effects in the joints of CIA mice, as evidenced by reduced paw swelling, bone erosion and deformation, inflammatory cell infiltration, and inflammation in synovial membrane. SC-E3 also reduced serum levels of tumor necrosis factor-α, interleukin-1β, aspartate aminotransferase and alanine aminotransferase. Furthermore, tartrate-resistant acid phosphatase-positive osteoclast numbers in the joints were significantly lower in SC-E3-treated CIA mice than in CIA mice. In addition, the differentiations of BMMs to multinucleated osteoclasts induced by M-CSF and RANKL stimulation were dose-dependently reduced by SC-E3.

CONCLUSION

These results suggest that SC-E3 possesses substantial anti-arthritic activity because it inhibits pro-inflammatory cytokines and osteoclastogenesis, and that SC-E3 has potential therapeutic use for the treatment of rheumatoid arthritis.

[Rheumatic diseases and neuropathic pain : Diagnosis and treatment]

Pain is a leading symptom in inflammatory rheumatic diseases. For a long time it has been assumed that this pain is of nociceptive origin; however, in about one fifth of all patients the pain remains despite successful anti-inflammatory treatment and is not typically described as nociceptive by those affected. Recent studies indicate that some patients with rheumatoid arthritis (RA) experience pain with a neuropathic pain component. The treatment of neuropathic pain with damage to the somatosensory system differs markedly from the treatment of nociceptive pain in which the pain processing system is intact. Thus, the recognition and, above all, the more precise differentiation of the pain symptoms of affected patients make a decisive contribution to a successful treatment. With the help of a few points in the history and a physical examination, the assumption of the diagnosis neuropathic pain can often be rejected or substantiated. Pain with a neuropathic component does not adequately respond to typical analgesics. Instead, the high efficacy of co-analgesics, such as anticonvulsants and antidepressants, has been repeatedly proven.

Association between IL-33 and other inflammatory factors in patients with rheumatoid arthritis and in fibroblast-like synoviocytes in vitro

IL-33 is a member of the IL-1 family of cytokines whose role remains controversial in rheumatoid arthritis (RA). The present study was performed to evaluate the correlation of IL-33 with other cytokines and chemokines in serum and the synovia, and to explore the nature of the association. The concentration of IL-33 in samples from 96 patients with RA was analyzed. The response of fibroblast-like synoviocytes (FLSs) to treatment with different concentrations of IL-33 was assessed in vitro. IL-33 was indicated to exhibit an association with multiple cytokines and chemokines in synovial fluid with an inverted-U-shaped trend, including IL-6, IL-1β, IL-8, MIG and IP-10, but not in the serum. Furthermore, in vitro experiments confirmed that IL-33 also exerted a U-type dose-dependent regulatory effect on FLS function. In addition, the data-points do not exactly follow the U-shaped curve fit in most cases, therefore, the applicability of this mathematical model in clinical practice is limited.

The Jak/STAT pathway: A focus on pain in rheumatoid arthritis

Pain is a manifestation of rheumatoid arthritis (RA) that is mediated by inflammatory and non-inflammatory mechanisms and negatively affects quality of life. Recent findings from a Phase 3 clinical trial showed that patients with RA who were treated with a Janus kinase 1 (Jak1) and Janus kinase 2 (Jak2) inhibitor achieved significantly greater improvements in pain than those treated with a tumor necrosis factor blocker; both treatments resulted in similar changes in standard clinical measures and markers of inflammation. These findings suggest that Jak1 and Jak2 inhibition may relieve pain in RA caused by inflammatory and non-inflammatory mechanisms and are consistent with the overarching involvement of the Jak-signal transducer and activator of transcription (Jak/STAT) pathway in mediating the action, expression, and regulation of a multitude of pro- and anti-inflammatory cytokines. In this review, we provide an overview of pain in RA, the underlying importance of cytokines regulated directly or indirectly by the Jak/STAT pathway, and therapeutic targeting of the Jak/STAT pathway in RA. As highlighted herein, multiple cytokines directly or indirectly regulated by the Jak/STAT pathway play important roles in mediating various mechanisms underlying pain in RA. Having a better understanding of these mechanisms may help clinicians make treatment decisions that optimize the control of inflammation and pain.

The Role of NLRP3 Inflammasome in Pneumococcal Infections

Inflammasomes are innate immune sensors that regulate caspase-1 mediated inflammation in response to environmental, host- and pathogen-derived factors. The NLRP3 inflammasome is highly versatile as it is activated by a diverse range of stimuli. However, excessive or chronic inflammasome activation and subsequent interleukin-1β (IL-1β) release are implicated in the pathogenesis of various autoimmune diseases such as rheumatoid arthritis, inflammatory bowel disease, and diabetes. Accordingly, inflammasome inhibitor therapy has a therapeutic benefit in these diseases. In contrast, NLRP3 inflammasome is an important defense mechanism against microbial infections. IL-1β antagonizes bacterial invasion and dissemination. Unfortunately, patients receiving IL-1β or inflammasome inhibitors are reported to be at a disproportionate risk to experience invasive bacterial infections including pneumococcal infections. Pneumococci are typical colonizers of immunocompromised individuals and a leading cause of community-acquired pneumonia worldwide. Here, we summarize the current limited knowledge of inflammasome activation in pneumococcal infections of the respiratory tract and how inflammasome inhibition may benefit these infections in immunocompromised patients.