Development of ROS-Sensitive Sulfasalazine-Loaded Ferrocene Nanoparticles and Evaluation of Their Antirheumatic Effects in a 3D Synovial Hyperplasia Model

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by joint inflammation, synovial hyperplasia, and bone and cartilage destruction, which significantly impairs physical function and quality of life. Disease-modifying antirheumatic drugs, such as sulfasalazine (SSZ), are crucial for altering the course and progression of RA; however, their clinical use is hampered by poor water solubility and lack of specificity for the reactive oxygen species (ROS)-rich environment typical of RA. To overcome these challenges, ROS-sensitive SSZ-loaded ferrocene nanoparticles are developed. The nanoparticles facilitate enhanced solubility and stability of SSZ and particularly enable precision targeting through the distinctive redox properties of ferrocene. Using a 3D synovial hyperplasia model with fibroblast-like synoviocytes derive from RA patients and validate at both the protein and gene levels, these nanoparticles significantly reduce lactate dehydrogenase, ROS, and inflammatory cytokine levels. Further validation using a collagen-induced arthritis model demonstrates therapeutic efficacy and cytokine modulation in vivo. These findings highlight the potential of ferrocene nanoparticles as a novel and effective therapeutic strategy for RA, offering improved drug delivery and reduced systemic toxicity.

Exploring Neutrophil Heterogeneity and Plasticity in Health and Disease

Neutrophils, the most abundant polymorphonuclear leukocytes, are critical first responders to infection, and have historically been underappreciated in terms of their functional complexity within the immune response. Once viewed primarily as short-lived, innate immune cells with limited functional plasticity, recent research has illuminated their considerable heterogeneity and diverse functional roles, which extend beyond their involvement in steady-state immunity. This review seeks to provide an updated analysis of neutrophil development, maturation, heterogeneity, and plasticity, with a focus on how these characteristics influence immune modulation in both healthy and diseased tissues. Beginning with the origin of neutrophils, we explore their maturation into effector cells and their evolving roles in immune defense under homeostatic and disease-associated conditions. We then delve into their heterogeneity, discussing recent breakthroughs in neutrophil research that challenge the traditional view of neutrophils as a uniform population. We address the significant advances that have been made in identifying distinct neutrophil subsets, the emerging complexities of their plasticity, and the challenges that remain in fully understanding their functional diversity. Finally, we highlight future directions and opportunities for continued exploration in this rapidly advancing field, shedding light on how these insights could open new avenues for therapeutic interventions.

Screening of the key response component groups and mechanism verification of Huangqi-Guizhi-Wuwu-Decoction in treating rheumatoid arthritis based on a novel computational pharmacological model

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by the destruction of synovial tissue and articular cartilage. Huangqi-Guizhi-Wuwu-Decoction (HGWD), a formula of Traditional Chinese Medicine (TCM), has shown promising clinical efficacy in the treatment of RA. However, the synergistic effects of key response components group (KRCG) in the treatment of RA have not been well studied.

METHODS

The components and potential targets of HGWD were extracted from published databases. A novel node influence calculation model that considers both the node control force and node bridging force was designed to construct the core response space (CRS) and obtain key effector proteins. An increasing coverage coefficient (ICC) model was employed to select the KRCG. The effectiveness and potential mechanism of action of KRCG were confirmed using CCK-8, qPCR, and western blotting.

RESULTS

A total of 796 key effector proteins were identified in CRS. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses confirmed their effectiveness and reliability. In addition, 59 components were defined as KRCG, which contributed to 85.05% of the target coverage of effective proteins. Of these, 677 targets were considered key reaction proteins, and their enriched KEGG pathways accounted for 84.89% of the pathogenic genes and 87.94% of the target genes. Finally, four components (moupinamide, 6-Paradol, hydrocinnamic acid, and protocatechuic acid) were shown to inhibit the inflammatory response in RA by synergistically targeting the cAMP, PI3K-Akt, and HIF-1α pathways.

CONCLUSIONS

We have introduced a novel model that aims to optimize and analyze the mechanisms behind herbal formulas. The model revealed the KRCG of HGWD for the treatment of RA and proposed that KRCG inhibits the inflammatory response by synergistically targeting cAMP, PI3K-Akt, and HIF-1α pathways. Overall, the novel model is plausible and reliable, offering a valuable reference for the secondary development of herbal formulas.

How does the same ligand activate signaling of different receptors in TNFR superfamily: a computational study

TNFα is a highly pleiotropic cytokine inducing inflammatory signaling pathways. It is initially presented on plasma membrane of cells (mTNFα), and also exists in a soluble variant (sTNFα) after cleavage. The ligand is shared by two structurally similar receptors, TNFR1 and TNFR2. Interestingly, while sTNFα preferentially stimulates TNFR1, TNFR2 signaling can only be activated by mTNFα. How can two similar receptors respond to the same ligand in such a different way? We employed computational simulations in multiple scales to address this question. We found that both mTNFα and sTNFα can trigger the clustering of TNFR1. The size of clusters induced by sTNFα is constantly larger than the clusters induced by mTNFα. The systems of TNFR2, on the other hand, show very different behaviors. Only when the interactions between TNFR2 are very weak, mTNFα can trigger the receptors to form very large clusters. Given the same weak binding affinity, only small oligomers were obtained in the system of sTNFα. Considering that TNF-mediated signaling is modulated by the ligand-induced clustering of receptors on cell surface, our study provided the mechanistic foundation to the phenomenon that different isoforms of the ligand can lead to highly distinctive signaling patterns for its receptors.

Identification of immune-related genes in acute myocardial infarction based on integrated bioinformatical methods and experimental verification

Background

Acute myocardial infarction (AMI) is one of the leading causes of death worldwide. The etiology of AMI is complex and has not been fully defined. In recent years, the role of immune response in the development, progression and prognosis of AMI has received increasing attention. The aim of this study was to identify key genes associated with the immune response in AMI and to analyze their immune infiltration.

Methods

The study included a total of two GEO databases, containing 83 patients with AMI and 54 healthy individuals. We used the linear model of microarray data (limma) package to find the differentially expressed genes associated with AMI, performing weighted gene co-expression analysis (WGCNA) to further identify the genes associated with inflammatory response to AMI. We found the final hub genes through the protein-protein interaction (PPI) network and least absolute shrinkage and selection operator (LASSO) regression model. To verify the above conclusions, we constructed mice AMI model, extracting myocardial tissue to perform qRT-PCR. Furthermore, the CIBERSORT tool for immune cells infiltration analysis was also carried out.

Results

A total of 5,425 significant up-regulated and 2,126 down-regulated genes were found in GSE66360 and GSE24519. A total of 116 immune-related genes in close association with AMI were screened by WGCNA analysis. These genes were mostly clustered in the immune response on the basis of GO and KEGG enrichment. With construction of PPI network and LASSO regression analysis, this research found three hub genes (SOCS2, FFAR2, MYO10) among these differentially expressed genes. The immune cell infiltration results revealed that significant differences could be found on T cells CD4 memory activated, Tregs (regulatory T cells), macrophages M2, neutrophils, T cells CD8, T cells CD4 naive, eosinophils between controls and AMI patients.

TNF-α Affects Signature Cytokines of Th1 and Th17 T Cell Subsets through Differential Actions on TNFR1 and TNFR2

Tumor necrosis factor (TNF)-α is a pleiotropic cytokine implicated in the etiology of several autoimmune diseases, including rheumatoid arthritis (RA). TNF-α regulates diverse effector functions through the activation of TNF-α receptor (TNFR)1 and TNFR2. Although the detrimental role of this cytokine has been addressed in distinct disease settings, the effects of TNF-α on cytokine production by isolated CD4⁺ T helper type 1 (Th1) and Th17 cells, two T cell subpopulations that contribute to the pathogenesis of RA, have not been completely elucidated. Here, we show that TNF-α promotes a reduction and expansion in the frequency of both T cell subsets producing IFN-γ and IL-17, respectively. Selective blockade of TNFR1 or TNFR2 on Th1 and Th17 cells revealed that TNFR2 mediates the decrease in IFN-γ production, while signaling through both receptors augments IL-17 production. We also demonstrate that Th1, but not Th17 cells from RA patients present lower levels of TNFR1 compared to healthy controls, whereas TNFR2 expression on both T cell types is similar between patients and controls. Since TNF-α receptors levels in RA patients are not significantly changed by the therapeutic blockade of TNF-α, we propose that targeting TNFR2 may represent an alternative strategy to normalize the levels of key cytokines that contribute to RA pathogenesis.

Naringenin as a natural immunomodulator against T cell-mediated autoimmune diseases: literature review and network-based pharmacology study

T cells, especially CD4+ T helper (Th) cells, play a vital role in the pathogenesis of specific autoimmune diseases. Naringenin, a citrus flavonoid, exhibits anti-inflammatory, anti-oxidant, and antitumor properties, which have been verified in animal autoimmune disease models. However, naringenin's possible effects and molecular mechanisms in T cell-mediated autoimmune diseases are unclear. This review summarizes the findings of previous studies and predicts the target of naringenin in T cell-mediated autoimmune disorders such as multiple sclerosis, inflammatory bowel disease, and rheumatoid arthritis through network pharmacology analysis. We performed DAVID enrichment analysis, protein-protein interaction analysis, and molecular docking to predict the positive effect of naringenin on T cell-mediated autoimmune disorders. Sixteen common genes were screened, among which the core genes were PTGS2, ESR1, CAT, CASP3, MAPK1, and AKT1. The possible molecular mechanism relates to HIF-1, estrogen, TNF, and NF-κB signaling pathways. Our findings have significance for future naringenin treatment of T cell-mediated autoimmune diseases.

Analysis of combined deficiency of interleukin-1 and -6 versus single deficiencies in TNF-mediated arthritis and systemic bone loss

Aims

Insufficient treatment response in rheumatoid arthritis (RA) patients requires novel treatment strategies to halt disease progression. The potential benefit of combination of cytokine-inhibitors in RA is still unclear and needs further investigation. To explore the impact of combined deficiency of two major cytokines, namely interleukin (IL)-1 and IL-6, in this study double deficient mice for IL-1αβ and IL-6 were investigated in different tumour necrosis factor (TNF)-driven inflammatory bone disorders, namely peripheral arthritis and sacroiliitis, as well as systemic bone loss.

Methods

Disease course, histopathological features of arthritis, and micro-CT (µCT) bone analysis of local and systemic bone loss were assessed in 15-week-old IL1^-/-IL6^-/-hTNFtg in comparison to IL1^-/-hTNFtg, IL6^-/-hTNFtg, and hTNFtg mice. µCT bone analysis of single deficient and wild-type mice was also performed.

Results

Combined deficiency of IL-1/IL-6 markedly ameliorated TNF-mediated arthritis and bilateral sacroiliitis, but without additive benefits compared to single IL-1 deficiency. This finding confirms the important role of IL-1 and the marginal role of IL-6 in TNF-driven pathways of local joint damage, but questions the efficacy of potential combinatorial therapies of IL-1 and IL-6 in treatment of RA. In contrast, combined deficiency of IL-1/IL-6 led to an additive protective effect on TNF-driven systemic bone loss compared to single IL-1 and IL-6 deficiency. This finding clearly indicates a common contribution of both IL-1 and IL-6 in TNF-driven systemic bone loss, and points to a discrepancy of cytokine dependency in local and systemic TNF-driven mechanisms of inflammatory arthritis.

Conclusion

Combinatorial treatments in RA might provide different benefits to inflammatory local arthritis and systemic comorbidities.

Cite this article: Bone Joint Res 2022;11(7):484–493.

Understanding the functional role of membrane confinements in TNF-mediated signaling by multiscale simulations

The interaction between TNFα and TNFR1 is essential in maintaining tissue development and immune responses. While TNFR1 is a cell surface receptor, TNFα exists in both soluble and membrane-bound forms. Interestingly, it was found that the activation of TNFR1-mediated signaling pathways is preferentially through the soluble form of TNFα, which can also induce the clustering of TNFR1 on plasma membrane of living cells. We developed a multiscale simulation framework to compare receptor clustering induced by soluble and membrane-bound ligands. Comparing with the freely diffusive soluble ligands, we hypothesize that the conformational dynamics of membrane-bound ligands are restricted, which affects the clustering of ligand-receptor complexes at cell-cell interfaces. Our simulation revealed that only small clusters can form if TNFα is bound on cell surface. In contrast, the clustering triggered by soluble TNFα is more dynamic, and the size of clusters is statistically larger. We therefore demonstrated the impact of membrane-bound ligand on dynamics of receptor clustering. Moreover, considering that larger TNFα-TNFR1 clusters is more likely to provide spatial platform for downstream signaling pathway, our studies offer new mechanistic insights about why the activation of TNFR1-mediated signaling pathways is not preferred by membrane-bound form of TNFα.

Adalimumab-Induced Erythema Multiforme in a Patient With Rheumatoid Arthritis: A Case Report

Tumor necrosis factor-alpha (TNF-α) inhibitors are a group of biological medications that revolutionized the treatment of rheumatoid arthritis (RA) and several other inflammatory autoimmune diseases. The wide use of these drugs has been associated with some adverse reactions. Erythema multiforme (EM) is an immune-mediated cutaneous disorder that represents a hypersensitivity reaction to infections, vaccines, and some medications. We present a female patient with EM with characteristic skin lesions following anti-TNF-α medication adalimumab for rheumatoid arthritis.

14-3-3 epsilon is an intracellular component of TNFR2 receptor complex and its activation protects against osteoarthritis

OBJECTIVES

Osteoarthritis (OA) is the most common joint disease; however, the indeterminate nature of mechanisms by which OA develops has restrained advancement of therapeutic targets. TNF signalling has been implicated in the pathogenesis of OA. TNFR1 primarily mediates inflammation, whereas emerging evidences demonstrate that TNFR2 plays an anti-inflammatory and protective role in several diseases and conditions. This study aims to decipher TNFR2 signalling in chondrocytes and OA.

METHODS

Biochemical copurification and proteomics screen were performed to isolate the intracellular cofactors of TNFR2 complex. Bulk and single cell RNA-seq were employed to determine 14-3-3 epsilon (14-3-3ε) expression in human normal and OA cartilage. Transcription factor activity screen was used to isolate the transcription factors downstream of TNFR2/14-3-3ε. Various cell-based assays and genetically modified mice with naturally occurring and surgically induced OA were performed to examine the importance of this pathway in chondrocytes and OA.

RESULTS

Signalling molecule 14-3-3ε was identified as an intracellular component of TNFR2 complexes in chondrocytes in response to progranulin (PGRN), a growth factor known to protect against OA primarily through activating TNFR2. 14-3-3ε was downregulated in OA and its deficiency deteriorated OA. 14-3-3ε was required for PGRN regulation of chondrocyte metabolism. In addition, both global and chondrocyte-specific deletion of 14-3-3ε largely abolished PGRN's therapeutic effects against OA. Furthermore, PGRN/TNFR2/14-3-3ε signalled through activating extracellular signal-regulated kinase (ERK)-dependent Elk-1 while suppressing nuclear factor kappa B (NF-κB) in chondrocytes.

CONCLUSIONS

This study identifies 14-3-3ε as an inducible component of TNFR2 receptor complex in response to PGRN in chondrocytes and presents a previously unrecognised TNFR2 pathway in the pathogenesis of OA.

Validation of GWAS-Identified Variants for Anti-TNF Drug Response in Rheumatoid Arthritis: A Meta-Analysis of Two Large Cohorts

We aimed to validate the association of 28 GWAS-identified genetic variants for response to TNF inhibitors (TNFi) in a discovery cohort of 1361 rheumatoid arthritis (RA) patients monitored in routine care and ascertained through the REPAIR consortium and DANBIO registry. We genotyped selected markers and evaluated their association with response to TNFi after 6 months of treatment according to the change in disease activity score 28 (ΔDAS28). Next, we confirmed the most interesting results through meta-analysis of our data with those from the DREAM cohort that included 706 RA patients treated with TNFi. The meta-analysis of the discovery cohort and DREAM registry including 2067 RA patients revealed an overall association of the LINC02549_rs7767069 SNP with a lower improvement in DAS28 that remained significant after correction for multiple testing (per-allele OR_Meta=0.83, P_Meta=0.000077; P_Het=0.61). In addition, we found that each copy of the LRRC55_rs717117G allele was significantly associated with lower improvement in DAS28 in rheumatoid factor (RF)-positive patients (per-allele OR_Meta=0.67, P=0.00058; P_Het=0.06) whereas an opposite but not significant effect was detected in RF-negative subjects (per-allele OR_Meta=1.38, P=0.10; P_Het=0.45; P_Interaction=0.00028). Interestingly, although the identified associations did not survive multiple testing correction, the meta-analysis also showed overall and RF-specific associations for the MAFB_rs6071980 and CNTN5_rs1813443 SNPs with decreased changes in DAS28 (per-allele OR_{Meta_rs6071980} = 0.85, P=0.0059; P_Het=0.63 and OR_{Meta_rs1813443_RF+}=0.81, P=0.0059; P_Het=0.69 and OR_{Meta_rs1813443_RF-}=1.00, P=0.99; P_Het=0.12; P_Interaction=0.032). Mechanistically, we found that subjects carrying the LINC02549_rs7767069T allele had significantly increased numbers of CD45RO+CD45RA+ T cells (P=0.000025) whereas carriers of the LINC02549_rs7767069T/T genotype showed significantly increased levels of soluble scavengers CD5 and CD6 in serum (P=0.00037 and P=0.00041). In addition, carriers of the LRRC55_rs717117G allele showed decreased production of IL6 after stimulation of PBMCs with B burgdorferi and E coli bacteria (P=0.00046 and P=0.00044), which suggested a reduced IL6-mediated anti-inflammatory effect of this marker to worsen the response to TNFi. In conclusion, this study confirmed the influence of the LINC02549 and LRRC55 loci to determine the response to TNFi in RA patients and suggested a weak effect of the MAFB and CNTN5 loci that need to be further investigated.

Comparative study between human mesenchymal stem cells and etanercept as immunomodulatory agents in rat model of rheumatoid arthritis

To compare human adipose tissue mesenchymal stem cells (AT-MSCs) and etanercept as immunomodulatory agents for collagen-induced arthritis (CIA). CIA was induced by rats' immunization with collagen type II (CII) in complete Freund's adjuvant in days 0 and 7. Before the onset of CIA, prevention group received five doses of AT-MSCS intraperitoneally. After establishment of arthritis, rats received either five doses of AT-MSCs or phosphate-buffered saline (PBS) intraperitoneally or six doses of etanercept subcutaneously. Clinical and histopathological evaluation were performed in all groups; serum levels of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and anti-collagen II were assessed by enzyme-linked immunosorbent assay (ELISA). A total percent of autoreactive T and regulatory T (Treg) cells were quantified using spleen immune histochemical analysis. AT-MSCs were able to delay the onset of CIA, suppress the ongoing clinical and histopathological signs, decrease serum levels of TNF-α and anti-collagen type II, and downregulate the autoreactive T cells as etanercept. AT-MSCs were more potent in Treg cells upregulation, producing high serum levels of IL10. AT-MSCs might have a therapeutic effect in CIA via their potency in immune cell education, representing an effective new promising approach in rheumatoid arthritis in human.

TNFR2/14-3-3ε signaling complex instructs macrophage plasticity in inflammation and autoimmunity

TNFR1 and TNFR2 have received prominent attention because of their dominance in the pathogenesis of inflammation and autoimmunity. TNFR1 has been extensively studied and primarily mediates inflammation. TNFR2 remains far less studied, although emerging evidence demonstrates that TNFR2 plays an antiinflammatory and immunoregulatory role in various conditions and diseases. Herein, we report that TNFR2 regulates macrophage polarization, a highly dynamic process controlled by largely unidentified intracellular regulators. Using biochemical copurification and mass spectrometry approaches, we isolated the signaling molecule 14-3-3ε as a component of TNFR2 complexes in response to progranulin stimulation in macrophages. In addition, 14-3-3ε was essential for TNFR2 signaling-mediated regulation of macrophage polarization and switch. Both global and myeloid-specific deletion of 14-3-3ε resulted in exacerbated inflammatory arthritis and counteracted the protective effects of progranulin-mediated TNFR2 activation against inflammation and autoimmunity. TNFR2/14-3-3ε signaled through PI3K/Akt/mTOR to restrict NF-κB activation while simultaneously stimulating C/EBPβ activation, thereby instructing macrophage plasticity. Collectively, this study identifies 14-3-3ε as a previously unrecognized vital component of the TNFR2 receptor complex and provides new insights into the TNFR2 signaling, particularly its role in macrophage polarization with therapeutic implications for various inflammatory and autoimmune diseases with activation of the TNFR2/14-3-3ε antiinflammatory pathway.

Clinical Evidence-Guided Anti-rheumatoid Arthritis Study of Shuji Tablet in Adjuvant-Induced Arthritis Rats and Mechanism Exploration via Network Pharmacological Approach

Background: Rheumatoid arthritis (RA) is a kind of chronic autoimmune disease with several tissues damaged. Shuji tablet (SJT) is a prescription approved for treating lumbago and leg pain in the clinic. However, the efficacy of SJT against RA is still unknown. This study aims to evaluate the therapeutic effect of SJT on adjuvant-induced arthritis (AIA) rats and explore the mechanism via a network pharmacological approach.

Methods: AIA rats were treated with SJT for 30 days at the dosages of 3.6, 1.8, and 0.9 g/kg, respectively, and the anti-RA effect was determined by measuring paw swelling, systemic symptoms score, arthritis index, and histopathological change. ELISA assay was used to evaluate the level of inflammatory cytokines in serum. The mechanism exploration and target prediction of SJT against RA were performed via a network pharmacological approach.

Results: SJT showed excellent alleviation on AIA rats, with evidence of reducing paws swelling, decreasing systemic symptoms score, and arthritis index. Furthermore, SJT significantly reduced the serum cytokines of IL-6, IL-1β, TNF-α in AIA rats. Histopathological examination showed SJT remarkably reduced synovial hyperplasia, cartilage damage, and inflammatory infiltration in the secondary-side paws. According to network pharmacological analysis, 208 candidate compounds and 445 potential targets of SJT were identified, and 4465 RA therapy-related targets were searched out. Subsequently, 292 target genes of SJT were speculated to be associated with RA treatment, among which the top 5 “response values” targets were STAT3, AKT1, JUN, HSP90AA1, TNF. GO and KEGG enrichment analysis suggested that 45 signaling pathways were associating with SJT treating RA. The top 10 signaling pathways were PI3K-Akt, MAPK, AGE-RAGE pathway in diabetic complications, Ras, HIF-1, TNF, Chemokine, IL-17, FoxO, and Rap1.

Conclusion: Our experimental study showed that SJT significantly alleviated rheumatoid arthritis of AIA rats. Network pharmacology showed that the key targets of SJT against RA probably were STAT3, AKT1, JUN, HSP90AA1, TNF, and the potential mechanism was associated with modulation on the signaling pathways of PI3K-Akt, MAPK, Ras, AGE-RAGE, HIF-1, TNF, chemokine, IL-17, FoxO, Rap 1. Our study strongly provides evidence for Shuji tablet in RA therapy and would enlarge its application in the clinic.

Switching from TNFα inhibitor to tacrolimus as maintenance therapy in rheumatoid arthritis after achieving low disease activity with TNFα inhibitors and methotrexate: 24-week result from a non-randomized, prospective, active-controlled trial

Background

Tapering or stopping biological disease-modifying anti-rheumatic drugs has been proposed for patients with rheumatoid arthritis (RA) in remission, but it frequently results in high rates of recurrence. This study evaluates the efficacy and safety of tacrolimus (TAC) as maintenance therapy in patients with established RA in remission after receiving combination therapy with tumor necrosis factor inhibitor (TNFi) and methotrexate (MTX).

Methods

This 24-week, prospective, open-label trial included patients who received TNFi and MTX at stable doses for ≥24 weeks and had low disease activity (LDA), measured by Disease Activity Score-28 for ≥12 weeks. Patients selected one of two arms: maintenance (TNFi plus MTX) or switched (TAC plus MTX). The primary outcome was the difference in the proportion of patients maintaining LDA at week 24, which was assessed using a logistic regression model. Adverse events were monitored throughout the study period.

Results

In efficacy analysis, 80 and 34 patients were included in the maintenance and switched arms, respectively. At week 24, LDA was maintained in 99% and 91% of patients in the maintenance and switched arms, respectively (odds ratio, 0.14; 95% confidence interval, 0.01–1.59). Drug-related adverse effects tended to be more common in the switched arm than in the maintenance arm (20.9% versus 7.1%, respectively) but were well-tolerated.

Conclusion

This controlled study tested a novel treatment strategy of switching from TNFi to TAC in RA patients with sustained LDA, and the findings suggested that TNFi can be replaced with TAC in most patients without the patients experiencing flare-ups for at least 24 weeks.

Trial registration

Korea CDC CRIS, KCT0005868. Registered 4 February 2021—retrospectively registered

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02566-z.

Efficacy and Safety of Adalimumab Biosimilars: Current Critical Clinical Data in Rheumatoid Arthritis

Adalimumab, as a TNF inhibitor biologic for the treatment of rheumatoid arthritis, is one of the top-selling drugs worldwide. As its various patents have gradually expired, experiments on its biosimilars are constantly being implemented. In this review, we summarized clinical trials of seven biosimilars currently approved by the FDA and/or EMA for the treatment of rheumatoid arthritis, namely: ABP 501 (Amjevita/Amgevita/Solymbic), BI 695501 (Cyltezo), SB5 (Imraldi/Hadlima), GP2017 (Hyrimoz/Hefiya/Halimatoz), MSB11022 (Idacio), FKB327 (Hulio), and PF-06410293 (Abrilada). Overall, these biosimilars showed similar efficacy, safety, and immunogenicity to adalimumab. All biosimilar switching trials indicated that switching from adalimumab to a biosimilar does not have a significant impact on efficacy, safety, and immunogenicity.

In Vitro Physical and Functional Interaction Assays to Examine the Binding of Progranulin Derivative Atsttrin to TNFR2 and Its Anti-TNFα Activity

TNFα/TNFR signaling plays a critical role in the pathogenesis of various inflammatory and autoimmune diseases, and anti-TNFα therapies have been accepted as the effective approaches for treating several autoimmune diseases. Progranulin (PGRN), a multi-faced growth factor-like molecule, directly binds to TNFR1 and TNFR2, particularly to the latter with higher affinity than TNFα. PGRN derivative Atsttrin is composed of three TNFR-binding domain of PGRN and exhibits even better therapeutic effects than PGRN in several inflammatory disease models, including collagen-induced arthritis. Herein we describe the detailed methodology of using (1) ELISA-based solid phase protein-protein interaction assay to demonstrate the direct binding of Atsttrin to TNFR2 and its inhibition of TNFα/TNFR2 interaction; and (2) tartrate-resistant acid phosphatase (TRAP) staining of in vitro osteoclastogenesis to reveal the cell-based anti-TNFα activity of Atsttrin. Using the protocol described here, the investigators should be able to reproducibly detect the physical inhibition of TNFα binding to TNFR and the functional inhibition of TNFα activity by Atsttrin and various kinds of TNF inhibitors.

The Immunomodulatory and Anti-Inflammatory Effect of Curcumin on Immune Cell Populations, Cytokines, and In Vivo Models of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a widespread chronic autoimmune disorder affecting the joints, causing irreversible cartilage, synovium, and bone degradation. During the course of the disease, many immune and joint cells are activated, causing inflammation. Immune cells including macrophages, lymphocytes, neutrophils, mast cells, natural killer cells, innate lymphoid cells, as well as synovial tissue cells, like fibroblast-like synoviocytes, chondrocytes, and osteoclasts secrete different proinflammatory factors, including many cytokines, angiogenesis-stimulating molecules and others. Recent studies reveal that curcumin, a natural dietary anti-inflammatory compound, can modulate the response of the cells engaging in RA course. This review comprises detailed data about the pathogenesis and inflammation process in rheumatoid arthritis and demonstrates scientific investigations about the molecular interactions between curcumin and immune cells responsible for rheumatoid arthritis development to discuss this herbal drug’s immunoregulatory role in RA treatment.

TNF signaling via TNF receptors does not mediate the effects of short-term exercise on cognition, anxiety and depressive-like behaviors in middle-aged mice

BACKGROUND

We recently reported that tumor necrosis factor (TNF) signaling via the TNFR1 and TNFR2 receptors mediates the effects of long-term exercise on locomotion, cognition and anxiety, but not depressive-like behavior. We now investigated whether the TNF signaling via its receptors also mediates the effects of short-term exercise on cognition, anxiety and depressive-like behaviors.

METHODS

Thirteen-month-old C57BL/6 (WT), TNF^-/-, TNFR1^-/-, and TNFR2^-/- mice were provided with 4 weeks of voluntary wheel running followed by behavioral testing using an established behavioral battery. Each genotype had a respective non-exercise control.

RESULTS

There was no interaction between genotype and exercise in any of the tests but the main effect of genotype, and not exercise, were found to be significant in the open field (OF), forced-swim test (FST) and Barnes maze (BM). In the OF, the control and exercise TNFR2^-/- mice spent significantly less time in the inner zone than mice in the control and exercise WT and TNF^-/- cohorts. In the FST, control and exercise WT mice showed significantly higher immobility time than their control and exercise TNF^-/-, TNFR1^-/- and TNFR2^-/- cohorts. In the BM, the latency to escape over 4 days of training was significantly higher in all KO groups compared to WT, irrespective of exercise. Also, the latency to escape to the original location during the probe trial was higher for control and exercise WT compared to corresponding TNFR1^-/- mice. In contrast, the latency to escape to the new location was lower for control and exercise WT compared to control and exercise TNFR1^-/- and TNFR2^-/- mice. The latency to escape to the new location in exercise groups was longer compared to control within all genotypes.

CONCLUSION

While TNF signaling via the TNF receptors mediates cognition, anxiety and depressive-like behaviors independently, it does not mediate the effects of short-term exercise on these behaviors in middle-aged mice.

Hsa_circ_0056558 regulates cyclin-dependent kinase 6 by sponging microRNA-1290 to suppress the proliferation and differentiation in ankylosing spondylitis

The aims of this study was to investigate the influences of hsa_circ_0056558/miR-1290/CDK6 axis in ankylosing spondylitis (AS). The differentially expressed has_circ_0056558 and miR-1290 in AS tissue were analysed based on RNA-seq data and microarray data, respectively. qRT-PCR was performed for detection of relative expression levels of hsa_circ_0056558, miR-1290, CDK6, osteogenic differentiation markers (Runx2 and Osterix) and other inflammatory factors (TNF-α, IL-1β, and IL-6). Western blotting analysis was conducted to test the protein levels of CDK6, osteogenic differentiation markers (Runx2 and Osterix), and PI3K/AKT/NF-κB pathway-associated proteins. CCK8 assay and flow cytometry were conducted to determine cell proliferation and cell apoptotic ability, respectively. Targeted relationships were predicted by bioinformatic analysis and verified by dual-luciferase reporter assay. The differentiation of fibroblast cells was analysed by alkaline phosphatase (ALP) activity assay. Our findings revealed that the expression levels of both circ_0056558 and CDK6 in AS tissue were significantly higher than that in normal samples. Besides, hsa_circ_0056558 could suppress cell proliferation and differentiation by facilitating CDK6 expression and suppressing miR-1290 expression in AS. Over-expression of miR-1290 negatively regulated CDK6 expression to enhance cell proliferation. The protein levels of p-AKT, p-NF-κB p65, and p-IκBα were promoted by hsa_circ_0056558 or CDK6 over-expression while suppressed by miR-1290 up-regulation. In conclusion, our study demonstrated that hsa_circ_0056558 and CDK6 suppressed cell proliferation and differentiation while enhanced cell apoptosis by competitive binding to miR-1290 in AS, which might be possibly achieved by PI3K/AKT/NF-κB pathway, providing us novel therapeutic strategy for AS.

CARD6 protects against collagen-induced rheumatoid arthritis in mice through attenuating the inflammatory response and joint destruction via suppression of TNFR1/TRAF2 signaling

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, characterized by chronic inflammation and bone destruction. However, the pathogenesis that contributes to RA is still unclear. Caspase recruitment domain protein 6 (CARD6) is a typical member of CARD domain-containing proteins, and shows regulatory effects on nuclear factor-κB (NF-κB) activation to meditate inflammation. In the present study, the role of CARD6 in the progression of inflammatory bone erosion in RA was investigated using the in vitro and in vivo experiments. In vitro results indicated that CARD expression was markedly down-regulated in the activated macrophages induced by lipopolysaccharide (LPS), accompanied with time-dependently increased expression of pro-inflammatory cytokines. Notably, over-expressing CARD6 in macrophages by adenoviral (Ad) vector significantly abolished the expression levels of pro-inflammatory cytokines and chemokines. We found that CARD6 over-expression-suppressed inflammatory response was associated with the blockage of tumor necrosis factor receptor-1/tumor necrosis factor receptor-associated factor-2 (TNFR1/TRAF2) signaling, inhibiting NF-κB pathway subsequently. In addition, LPS-induced apoptosis in macrophages was also blunted due to AdCARD6 infection. CARD6-alleviated inflammatory response and apoptotic cell death were further confirmed in TNF-α-stimulated macrophages. Then, the in vivo studies showed that promoting CARD6 expression using adeno-associated virus (AAV) effectively attenuated the severity of arthritis, improved histopathological damage, and hindered the bone erosion in collagen-induced arthritis (CIA) mice. Moreover, pro-inflammatory factors in the joint samples were also markedly decreased in CIA mice with CARD6 over-expression, which was related to the down-regulation of TNFR1/TRAF2/NF-κB signaling pathway. Meanwhile, apoptosis in joint of CIA mice was also ameliorated by AAV-CARD6, as evidenced by the obviously reduced expression of cleaved Caspase-3. These results clearly suggested that CARD6 might have anti-inflammatory and anti-apoptotic effects during RA progression, and thus could be defined as a novel therapeutic target for RA treatment in future.

[Biologicals and small molecules for rheumatoid arthritis]

In recent years tremendous progress has been made in the therapeutic management of rheumatoid arthritis. Rheumatologists now have a large armamentarium of highly efficient drugs with different mechanisms of action at their disposal. These new drugs consist of biologicals (biological disease-modifying antirheumatic drugs, bDMARDs) as well as targeted synthetic DMARDs (tsDMARD). A common feature of these new drugs for treatment of rheumatoid arthritis is that the molecular target of the drug is known, which is not the case for conventional DMARDs. With the help of the new drugs, the therapeutic goal of inducing remission in patients with rheumatoid arthritis has become reality for many patients. Nevertheless, there is still a significant proportion of patients who do not adequately respond to all available drugs, leaving room for still further improvement. This review gives a short overview on the currently available and effective substances for the treatment of rheumatoid arthritis.

The Biological Role of Apurinic/Apyrimidinic Endonuclease1/Redox Factor-1 as a Therapeutic Target for Vascular Inflammation and as a Serologic Biomarker

Endothelial dysfunction promotes vascular inflammation by inducing the production of reactive oxygen species and adhesion molecules. Vascular inflammation plays a key role in the pathogenesis of vascular diseases and atherosclerotic disorders. However, whether there is an endogenous system that can participate in circulating immune surveillance or managing a balance in homeostasis is unclear. Apurinic/apyrimidinic endonuclease 1/redox factor-1 (henceforth referred to as APE1/Ref-1) is a multifunctional protein that can be secreted from cells. It functions as an apurinic/apyrimidinic endonuclease in the DNA base repair pathway and modulates redox status and several types of transcriptional factors, in addition to its anti-inflammatory activity. Recently, it was reported that the secretion of APE1/Ref-1 into the extracellular medium of cultured cells or its presence in the plasma can act as a serological biomarker for certain disorders. In this review, we summarize the possible biological functions of APE1/Ref-1 according to its subcellular localization or its extracellular secretions, as therapeutic targets for vascular inflammation and as a serologic biomarker.

Single-cell mass cytometry reveals cross-talk between inflammation-dampening and inflammation-amplifying cells in osteoarthritic cartilage

Aging or injury leads to degradation of the cartilage matrix and the development of osteoarthritis (OA). Because of a paucity of single-cell studies of OA cartilage, little is known about the interpatient variability in its cellular composition and, more importantly, about the cell subpopulations that drive the disease. Here, we profiled healthy and OA cartilage samples using mass cytometry to establish a single-cell atlas, revealing distinct chondrocyte progenitor and inflammation-modulating subpopulations. These rare populations include an inflammation-amplifying (Inf-A) population, marked by interleukin-1 receptor 1 and tumor necrosis factor receptor II, whose inhibition decreased inflammation, and an inflammation-dampening (Inf-D) population, marked by CD24, which is resistant to inflammation. We devised a pharmacological strategy targeting Inf-A and Inf-D cells that significantly decreased inflammation in OA chondrocytes. Using our atlas, we stratified patients with OA in three groups that are distinguished by the relative proportions of inflammatory to regenerative cells, making it possible to devise precision therapeutic approaches.

Deciphering the Pharmacological Mechanisms of the Huayu-Qiangshen-Tongbi Formula Through Integrating Network Pharmacology and In Vitro Pharmacological Investigation

Rheumatoid arthritis is a chronic inflammatory autoimmune disease, causing articular and extra-articular dysfunctions among patients, and it could result in irreversible joint damages or disability if untreated. A traditional Chinese medicine formula, Huayu-Qiangshen-Tongbi (HT) formula, has been observed successful in controlling rheumatoid arthritis progression in traditional Chinese medicine clinics. In this study, we conducted a systematic analysis of the HT formula with a purpose of proposing for its potential mechanism of action using network pharmacological methods. The potential targets of the formula were collected and screened according to the topological features of their protein–protein interaction network, and we subsequently validated our prediction results through in vitro experiments. We proposed that the HT formula could interfere with the bone metabolism and the inflammatory pathways of the body. The experimental validation results indicated that HT formula could exhibit anti-inflammatory effects by regulating several signaling pathways specifically the Toll-like receptor signaling pathway, phosphoinositide-3-kinase–Akt signaling pathway, hypoxia-inducible factor 1 signaling pathway, mitogen-activated protein kinase signaling pathway and activator protein 1 signaling pathway.

Interference of tumor necrosis factor inhibitor treatments on soluble tumor necrosis factor receptor 2 levels in rheumatoid arthritis

Objective

Soluble Tumor Necrosis Factor Receptor II (sTNFR2) is used as a biomarker to study cardiovascular disease (CVD) in diverse populations. TNF inhibitors (TNFi's) are a common treatment for inflammatory conditions. The objective of this study was to examine whether TNFi use impacts measured sTNFR2 levels.

Methods

We studied blood samples from a cohort of RA patients with clinical data and high sensitivity-C-reactive protein (hsCRP) measurements. To assess for interference, we tested the entire cohort for the expected positive correlation between sTNFR2 and TNFi using Pearson correlations. We then performed Pearson correlations between sTNFR2 and TNFi and sequentially removed subjects on adalimumab, etanercept, and infliximab; if interference was occurring, no correlation would be observed between hsCRP and sTNFR2, and correlation would be restored by removing subjects on the treatment causing the interference.

Results

We studied 190 subjects, 84.2% female, 73.4% anti-CCP positive. All subjects with sTNFR2 level exceeding measurable level were on etanercept. The expected positive correlation between hsCRP and sTNFR2 was not observed when assessing the entire cohort, r = 0.05, p = 0.51. However, the expected correlation was restored only after excluding subjects on etanercept, r = 0.46, p < 0.0001, and not adalimumab or infliximab. ELISA for sTNFR2 was performed using etanercept only and demonstrated direct binding to sTNFR2.

Conclusions

Our data identified interference between etanercept and the TNFR2 assay. Of the TNFi's, only etanercept has a TNF-binding domain modeled after TNFR2. These data should be considered when designing studies using sTNFR2 in populations where etanercept is a treatment option.

Transient expression of etanercept therapeutic protein in tobacco (Nicotiana tabacum L.)

Etanercept is a recombinant fusion protein of TNFR2 with the Fc portion of human IgG1. Etanercept, an anti-TNF drug, treats autoimmune diseases and improves patients' health. The main goal of the present study was to investigate the possibility of expressing recombinant protein of etanercept in a plant system. For this aim, first a modified version of pCAMBIA1305.1 plasmid with a new multiple cloning site and signal sequence of KDEL for protein secretion was constructed (pCAMBIA1305.1-linker). Then etanercept gene was cloned into the linker fragment of pCAMBIA1305.1-linker vector. Cloning was confirmed by PCR, enzymatic digestion and sequencing techniques. To evaluate the transient expression of the gene, agroinfiltrated tobacco leaves were inoculated with Agrobacterium tumefaciens containing etanercept gene cassette. The recombinant etanercept protein was examined by dot blot and ELISA assays. Our results using anti-human IgG HRP-conjugated antibody confirmed a high level expression of etanercept gene in the tobacco leaves.

Immunoregulatory properties of cell-free DNA in plasma of celiac disease patients - A pilot study

The elevated plasma cell-free DNA (cfDNA) concentrations were repeatedly reported in association with the process of inflammation. The qualitative and quantitative characteristics of plasma cfDNA in active (newly diagnosed) celiac disease patients (CD) have not yet been studied despite the fact that cfDNA of healthy individuals is able to regulate immune response. We determined the total cfDNA concentration and relative content of telomeric sequences in plasma cfDNA in CD (n = 10) and healthy age- and sex-matched controls (HC, n = 10) by quantitative PCR. To obtain the evidence that the observed biological effects are caused solely by cfDNA molecules, we applied the treatment of paired plasma samples with DNase. Using paired samples of plasma (non-treated/native and treated by DNase), we analyzed the contribution of cfDNA to the activation of TLR9 and TNF-α mRNA expression in THP1 monocytic cell line. There were no significant differences in the quantities of plasma cfDNA and relative contents of telomeric sequences in their pools. When we compared the levels of TNF-α mRNA expression in THP1 cells achieved after stimulation with native CD and HC plasma samples, we found significantly (p = .031) higher expression after stimulation with CD samples. We documented also the ability of cfDNA contained in CD plasma samples to stimulate the production of TLR9 mRNA. The TLR9 mRNA expression levels were significantly (p = .014) lowered after cfDNA removal from CD plasma samples. The design of our experiments allowed us to study the effects of cfDNA without its isolation from plasma. cfDNA contained in CD plasma samples differs significantly in its immunoregulatory capacity from cfDNA in HC plasma. The differences are caused neither by different concentrations of cfDNA in plasma samples nor by different relative abundance of telomeric sequences. Further studies are needed to elucidate the role of plasma cfDNA in celiac disease pathogenesis.

Galectin-3 Deficiency Facilitates TNF-α-Dependent Hepatocyte Death and Liver Inflammation in MCMV Infection

Galectin-3 (Gal-3) has a role in multiple inflammatory pathways. Various, opposite roles of Gal-3 in liver diseases have been described but there are no data about the role of Gal-3 in development of hepatitis induced with cytomegalovirus infection. In this study we aimed to clarify the role of Gal-3 in murine cytomegalovirus (MCMV)-induced hepatitis by using Gal-3-deficient (Gal-3 KO) mice. Here we provide the evidence that Gal-3 has the protective role in MCMV-induced hepatitis. Enhanced hepatitis manifested by more inflammatory and necrotic foci and serum level of ALT, enhanced apoptosis and necroptosis of hepatocytes and enhanced viral replication were detected in MCMV-infected Gal-3 deficient mice. NK cells does not contribute to more severe liver damage in MCMV-infected Gal-3 KO mice. Enhanced expression of TNF-α in the hepatocytes of Gal-3 KO mice after MCMV infection, abrogated hepatocyte death, and attenuated inflammation in the livers of Gal-3 KO mice after TNF-α blockade suggest that TNF-α plays the role in enhanced disease in Gal-3 deficient animals. Treatment with recombinant Gal-3 reduces inflammation and especially necrosis of hepatocytes in the livers of MCMV-infected Gal-3 KO mice. Our data highlight the protective role of Gal-3 in MCMV-induced hepatitis by attenuation of TNF-α-mediated death of hepatocytes.

Dual neutralization of TNFR-2 and MMP-2 regulates the severity of S. aureus induced septic arthritis correlating alteration in the level of interferon gamma and interleukin-10 in terms of TNFR2 blocking

Severity of S. aureus septic arthritis is correlated to prolonged inflammation by inflammatory cytokines like TNF-α, IL-1β, and IL-6 even after successful elimination of bacteria. Role of TNF-α via TNFR2 is not well established in this aspect. IFN-γ induces TNF-α release from the macrophages augmenting the inflammatory arthritis. IL-10 modulates the levels of pro-inflammatory cytokines promoting resolution of inflammation. TNF-α-TNFR2 signaling upregulates both of these cytokines. Higher level of MMP-2 induction by inflammatory cytokines during arthritis promotes tissue destruction. Whether dual neutralization of TNFR-2 and MMP-2 regulates the severity of S. aureus arthritis by modulating local and systemic cytokine milieu mainly due to TNFR-2 blocking was an obvious question. Here, we attempted the effects of neutralization of MMP-2 and TNFR2 on S. aureus arthritis and its impact on pro-inflammatory cytokines and some other parameters related to tissue destruction. Reduction in arthritis index was noticed in infected mice treated with both MMP-2 inhibitor and TNFR2 antibody. Lowest levels of inflammatory cytokines, iNOS, RANKL, NF-κb, JNK kinase, ROS, and MPO, and lysozyme activity were observed in combined neutralization group at 9 and 15 dpi, but at 3 dpi, most of the above parameters remained elevated due to TNFR2 neutralization. Diminished IL-10 and IFN-γ levels as a result of TNFR2 neutralization at early and later phase of infection respectively might be responsible for these contrasting effects. Overall, it can be suggested that administration of MMP-2 inhibitor and TNFR2 antibody in combination is protective against the inflammation and tissue destruction associated with S. aureus infection during the arthritic episode.

The Effect of Human Recombinant Tumor Necrosis Factor Receptor-2 on Reducing Inflammatory of Collagen -Induced Arthritis in Balb/c Mice

Background

The tumor necrosis factor alpha (TNFα) is a cytokine that produced principally by monocyte/macrophages and T lymphocytes, respectively. TNFα is recognized as the primary mediator of immunity in inflammation reaction. One important application of Tumor Necrosis Factor Receptor 2 (TNFR2) is for the treatment of autoimmune diseases like rheumatoid arthritis (RA).

Objectives

The aim of this study is to examine the therapeutic trace of the recombinant humanTNFR2 on collagen-induced arthritis (CIA) in mice.

Materials and Methods

CIA was created in 20 mice by immunization with bovine type II collagen (CII). After the mice were boosted on day 21, they were injected with the recombinant protein in test group (1 mg.kg-1) and assessed edema in paws and knee joints after two weeks. The quantities of inflammatory cytokines such as TNF-α, interleukin-1 beta (IL-β1), interleukin-6 (IL-6), and interleukin-10(IL-10) in serum were evaluated through enzyme-linked immunosorbent assay (ELISA) kit. In addition, the histopathology of joints sections was analyzed.

Results

The cytokines TNF-α, IL-1β, and IL-6 values in serum markedly decreased in groups treated with TNFR2 (P < 0.01-0.001). The results showed that treatment with TNFR2 significantly reduced edema in paws and joints (P < 0.01-0.001).

Conclusions

Pathological investigations proved that administration of recombinant TNF receptor has blocked or protected joints from progressive damage. This study suggests that the anti-arthritic effectiveness of TNFR2 will repress the symptoms of rheumatoid arthritis. Moreover, it seems that TNFR2 is a strong candidate for the treatment of the RA disease.

Neutralization of MMP-2 and TNFR1 Regulates the Severity of S. aureus-Induced Septic Arthritis by Differential Alteration of Local and Systemic Proinflammatory Cytokines in Mice

Despite advancement in the field of antibiotics septic arthritis remains a serious concern till date. Staphylococcus aureus is the most common bacterium that causes septic arthritis. Severity of this disease is directly correlated with chronic inflammation induced by proinflammatory cytokines like TNF-α, interleukin (IL)-1β, IL-6, and induction of matrix metalloproteinases (MMPs) including MMP-2. The objective of our study was to evaluate the role of MMP-2 and tumor necrosis factor receptor 1 (TNFR1) in the pathogenesis of S. aureus infection-induced septic arthritis. Mice were infected with live S. aureus (5 × 10⁶ cells/ml) followed by administration of MMP-2 inhibitor and TNFR1 antibody. Arthritis index showed highest reduction in severity of arthritis in mice treated with both MMP-2 inhibitor and TNFR1 antibody after infection. Combined neutralization of MMP-2 and TNFR1 led to marked diminution in bacterial count in the combined group. Lowest levels of pro inflammatory cytokines like TNF-α, IL-1β, IL-6, and IFN-γ were observed in both serum and synovial tissues indicating maximum protection in S. aureus arthritis during combination treatment. Increment in the level of IL-10 in the combination group could be positively correlated with the recovery of arthritis. Similarly, expressions of COX-2 and iNOS, markers of acute inflammation were also significantly reduced in the combination group due to resolution of inflammation. Levels of O2^.- and NO also showed a significant fall in case of the group treated with MMP-2 inhibitor and TNFR1 antibody both. Neutralization of both MMP-2 and TNFR1 caused rapid decline in recruitment of neutrophil and macrophages in the synovial tissues as evident from reduced MPO and MCP-1 levels, respectively, compared to other groups. Overall, it can be suggested that administration of MMP-2 inhibitor and TNFR1 antibody in combination is protective against the severity of inflammation and cartilage destruction associated with S. aureus infection-induced septic arthritis by altering the levels of cytokines.

Effectiveness of lentivirus-mediated RNA interference targeting mouse tumor necrosis factor α in vitro and in vivo

The aim of the present study was to identify the effectiveness of lentivirus-mediated RNA interference (RNAi) targeting mouse tumor necrosis factor-α (TNF-α). RNAi lentivirus was used in vitro to transfect RAW264.7 cells, and the expression of TNF-α, interleukin (IL)-1β and IL-6 mRNAs and TNF-α protein in RAW264.7 cells was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay, respectively. In vivo, mice with collagen-induced arthritis (CIA) were injected intravenously with RNAi lentivirus, and CIA arthritis scores and the serum levels of TNF-α were detected. Additionally, joint tissues were subjected to pathological examination. In the cells, the expression level of TNF-α mRNA in the RNAi lentivirus group was 0.29±0.02, which was significantly lower than that of the lentivirus negative control (0.93±0.01; t=25.4, P<0.001). In the mice, the serum TNF-α level in the RNAi lentivirus group was 249.25±11.22 ng/ml, which was significantly lower than that of the negative control group (381.86±6.28 ng/ml; P<0.05). However, no difference in IL-1α and IL-6 mRNA levels was identified among the groups (t=1.00, P=0.37; t=1.22, P=0.29). The CIA arthritis score in the RNAi lentivirus group was significantly reduced compared with those in the control and negative control groups (P<0.05). Furthermore, the arthritis scores in the RNAi lentivirus and positive control groups continued to decrease for ≥2 weeks, and the serum TNF-α levels in the RNAi lentivirus and positive control groups were 31.58±2.18 and 35.21±2.25 pg/ml, which were significantly lower than those in the negative control group (46.62±3.02 pg/ml; P<0.05). Thus, targeting of the TNF-α gene in mice via lentivirus-mediated RNAi in vitro and in vivo achieved TNF-α gene downregulation, which indicates that lentivirus-mediated RNA interference may be an effective form of gene therapy against rheumatoid arthritis.

Neutralization of TNFR-1 and TNFR-2 modulates S. aureus induced septic arthritis by regulating the levels of pro inflammatory and anti inflammatory cytokines during the progression of the disease

Staphylococcal septic arthritis remains a serious medical concern due to rapid and sustained production of inflammatory cytokines that leads to progressive and irreversible joint destruction with high mortality rate in patients despite adequate antibiotics treatment. TNF-α signalling via TNFR-1 contributes to arthritic destruction by aggravating inflammation. Impact of TNFR-2 signalling is not well established in this aspect. Hence the objective of our study was to evaluate the role of dual neutralization TNFR-1 and TNFR-2 in the pathogenesis of S. aureus infection induced septic arthritis. Mice were infected with live S. aureus (5 × 10⁶ cells/ml) followed by administration of TNFR-1and TNFR-2 neutralizing antibody. To measure arthritis index and osteoclastogenesis, histology result in joint tissue and TRAP staining images of arthritis joints have been performed respectively. Maximum reduction in the joint and paw swelling was observed in infected mice treated with both TNFR-1 and TNFR-2 antibody. NF-κB signalling was found to be mainly regulated by TNFR-1 whereas TNFR-2 significantly modulated JNK pathway. Lowest levels of inflammatory cytokines like TNF-α, IL-1β, IL-6, and IFN-γ were observed in both serum and synovial tissues signifying maximum protection in S. aureus arthritis during combination treatment. However IFN-γ and IL-10 levels were significantly altered by TNFR-2 neutralization that indicates both pro and anti inflammatory role of TNFR-2 respectively. Highest decrement in ROS concentration, iNOS expression with least MPO and lysozyme activity was detected in case of combined neutralization. During the early phase of infection all the aforesaid inflammatory parameters remained elevated due to lack of IL-10 as a result of TNFR-2 neutralization as IL-10 negatively modulates pro inflammatory cytokines. Increase in inflammatory cytokines during early phase might also be responsible for decreased bacterial count in TNFR-2 neutralized groups. Thus it can be suggested that combined administration of TNFR-1 and TNFR-2 antibody has a beneficial effect against the severity of S. aureus induced arthritis.

Osteoimmunology in Bone Fracture Healing

PURPOSE OF REVIEW

In the process of bone fracture healing, inflammation is thought to be an essential process that precedes bone formation and remodeling. We review recent studies on bone fracture healing from an osteoimmunological point of view.

RECENT FINDINGS

Based on previous observations that many types of immune cells infiltrate into the bone injury site and release a variety of molecules, recent studies have addressed the roles of specific immune cell subsets. Macrophages and interleukin (IL)-17-producing γδ T cells enhance bone healing, whereas CD8⁺ T cells impair bone repair. Additionally, IL-10-producing B cells may contribute to bone healing by suppressing excessive and/or prolonged inflammation. Although the involvement of other cells and molecules has been suggested, the precise underlying mechanisms remain elusive. Accumulating evidence has begun to reveal the deeper picture of bone fracture healing. Further studies are required for the development of novel therapeutic strategies for bone fracture.

Inflammatory osteolysis: a conspiracy against bone

There are many causes of inflammatory osteolysis, but regardless of etiology and cellular contexts, the osteoclast is the bone-degrading cell. Thus, the impact of inflammatory cytokines on osteoclast formation and function was among the most important discoveries advancing the treatment of focal osteolysis, leading to development of therapeutic agents that either directly block the bone-resorptive cell or do so indirectly via cytokine arrest. Despite these advances, a substantial number of patients with inflammatory arthritis remain resistant to current therapies, and even effective anti-inflammatory drugs frequently do not repair damaged bone. Thus, insights into events such as those impacted by inflammasomes, which signal through cytokine-dependent and -independent mechanisms, are needed to optimize treatment of inflammatory osteolysis.

Etanercept-Synthesising Mesenchymal Stem Cells Efficiently Ameliorate Collagen-Induced Arthritis

Mesenchymal stem cells (MSCs) have multiple properties including anti-inflammatory and immunomodulatory effects in various disease models and clinical treatments. These beneficial effects, however, are sometimes inconsistent and unpredictable. For wider and proper application, scientists sought to improve MSC functions by engineering. We aimed to invent a novel method to produce synthetic biological drugs from engineered MSCs. We investigated the anti-arthritic effect of engineered MSCs in a collagen-induced arthritis (CIA) model. Biologics such as etanercept are the most successful drugs used in anti-cytokine therapy. Biologics are made of protein components, and thus can be theoretically produced from cells including MSCs. MSCs were transfected with recombinant minicircles encoding etanercept (trade name, Enbrel), which is a tumour necrosis factor α blocker currently used to treat rheumatoid arthritis. We confirmed minicircle expression in MSCs in vitro based on GFP. Etanercept production was verified from the conditioned media. We confirmed that self-reproduced etanercept was biologically active in vitro. Arthritis subsided more efficiently in CIA mice injected with mcTNFR2MSCs than in those injected with conventional MSCs or etanercept only. Although this novel strategy is in a very early conceptual stage, it seems to represent a potential alternative method for the delivery of biologics and engineering MSCs.

TNF-α Autocrine Feedback Loops in Human Monocytes: The Pro- and Anti-Inflammatory Roles of the TNF-α Receptors Support the Concept of Selective TNFR1 Blockade In Vivo

Selective TNFR1 blockade in inflammatory diseases is emerging as a clinical strategy. We studied the roles of the two TNF-α receptors, TNFR1 and TNFR2, in human monocytes, the principal producer of TNF-α and central to many TNF-α driven diseases. We hypothesised that TNF-α has pro- and anti-inflammatory effects on monocytes, occurring differentially via TNFR1 and TNFR2. Monocytes were isolated from healthy human subjects and exposed to LPS, plus/minus the addition of blocking antibodies to TNF-α or its receptors. Pro- and anti-inflammatory cytokine production was quantified using real-time PCR and ELISAs. Cell surface expression of TNFR1/2 was measured by flow cytometry. We demonstrated that monocytes vary in the expression patterns of TNFR1 and TNFR2. Autocrine binding of TNF-α led to sustained upregulation of proinflammatory cytokines via TNFR1. In contrast, autocrine binding via TNFR2 upregulated the anti-inflammatory cytokine, IL-10, without proinflammatory effect. TNFR2 was responsible for binding soluble TNF-α secreted by monocytes, clearing the cytokine from the pericellular environment. TNFR1 blockade did not change the cell surface expression of TNFR2, leaving this receptor free to upregulate IL-10. These novel results support the concept of selective TNFR1 blockade in vivo in order that positive anti-inflammatory effects of TNF-α can be retained via TNFR2 ligation.

The role of progranulin in arthritis

Progranulin (PGRN) is a growth factor with a unique beads-on-a-string structure that is involved in multiple pathophysiological processes, including anti-inflammation, tissue repair, wound healing, neurodegenerative diseases, and tumorigenesis. This review presents up-to-date information concerning recent studies on the role of PGRN in inflammatory arthritis and osteoarthritis, with a special focus on the involvement of the interactions and interplay between PGRN and tumor necrosis factor receptor (TNFR) family members in regulating such musculoskeletal diseases. In addition, this paper highlights the applications of atsttrin, an engineered protein comprising three TNFR-binding fragments of PGRN, as a promising intervention in treating arthritis.

Adalimumab ameliorates OVA-induced airway inflammation in mice: Role of CD4(+) CD25(+) FOXP3(+) regulatory T-cells

Asthma is a chronic inflammatory heterogeneous disorder initiated by a dysregulated immune response which drives disease development in susceptible individuals. Though T helper 2 (TH2) biased responses are usually linked to eosinophilic asthma, other Th cell subsets induce neutrophilic airway inflammation which provokes the most severe asthmatic phenotypes. A growing evidence highlights the role of T regulatory (Treg) cells in damping abnormal Th responses and thus inhibiting allergy and asthma. Therefore, strategies to induce or augment Treg cells hold promise for treatment and prevention of allergic airway inflammation. Recently, the link between Tumor necrosis factor-α (TNF-α) and Treg has been uncovered, and TNF-α antagonists are increasingly used in many autoimmune diseases. Yet, their benefits in allergic airway inflammation is not clarified. We investigated the effect of Adalimumab, a TNF-α antagonist, on Ovalbumin (OVA)-induced allergic airway inflammation in CD1 mice and explored its impact on Treg cells. Our results showed that Adalimumab treatment attenuated the OVA-induced increase in serum IgE, TH2 and TH1 derived inflammatory cytokines (IL-4 and IFN-γ, respectively) in bronchoalveolar lavage (BAL) fluid, suppressed recruitment of inflammatory cells in BAL fluid and lung, and inhibited BAL fluid neutrophilia. It also ameliorated goblet cell metaplasia and bronchial fibrosis. Splenocytes flow cytometry revealed increased percentage of CD4(+) CD25(+) FOXP3(+) Treg cells by Adalimumab that was associated with increase in their suppressive activity as shown by elevated BAL fluid IL-10. We conclude that the beneficial effects of Adalimumab in this CD1 neutrophilic model of allergic airway inflammation are attributed to augmentation of Treg cell number and activity.

TNFRSF1B Is Associated with ANCA in IBD

The genetic basis of antineutrophil cytoplasmic antibody, an important biomarker of inflammatory bowel disease (IBD), has never been thoroughly examined on a genome-wide scale. In this study, we performed a 2-stage genome-wide association study (GWAS) on antineutrophil cytoplasmic antibody in IBD cases. In the 2959 IBD cases in the discovery stage, we observed an association between a variant in the gene TNFRSF1B with antineutrophil cytoplasmic antibody level (rs5745994, minor allele frequency = 0.028, beta = 18.12, 95% CI, 11.82-24.22, P = 1.89 × 10). This association was replicated in an independent cohort of 419 IBD cases (beta = 16.91, 95% CI, 6.13-27.69, P = 2.38 × 10). With a Q-value of 0.036, we performed a fixed-effect meta-analysis for the association of rs5745994 in both cohorts and observed a stronger association signal (beta = 17.81, 95% CI, 12.36-23.25, P = 8.97 × 10). TNFRSF1B gene codes for tumor necrosis factor (TNF) receptor 2 (TNFR2), thereby we examined the reported TNFRSF1B variant with serum TNFR2 level. We observed a negative association with serum TNFR2 level being 8.23 EU/mL in carriers and 9.12 EU/mL in noncarriers (P = 0.033). This finding indicates the functional role of identified TNFRSF1B variant in IBD serology and may be reflective of the underlying biological mechanisms that determine clinical expression and/or response to certain therapies.