Monocyte MicroRNA Expression in Active Systemic Juvenile Idiopathic Arthritis Implicates MicroRNA-125a-5p in Polarized Monocyte Phenotypes

A Bionic Thermosensitive Sustainable Delivery System for Reversing the Progression of Osteoarthritis by Remodeling the Joint Homeostasis

Although the pathogenesis of osteoarthritis (OA) is unclear, inflammatory cytokines are related to its occurrence. However, few studies focused on the therapeutic strategies of regulating joint homeostasis by simultaneously remodeling the anti-inflammatory and immunomodulatory microenvironments. Fibroblast growth factor 18 (FGF18) is the only disease-modifying OA drug (DMOAD) with a potent ability and high efficiency in maintaining the phenotype of chondrocytes within cell culture models. However, its potential role in the immune microenvironment remains unknown. Besides, information on an optimal carrier, whose interface and chondral-biomimetic microenvironment mimic the native articular tissue, is still lacking, which substantially limits the clinical efficacy of FGF18. Herein, to simulate the cartilage matrix, chondroitin sulfate (ChS)-based nanoparticles (NPs) are integrated into poly(D, L-lactide)-poly(ethylene glycol)-poly(D, L-lactide) (PLEL) hydrogels to develop a bionic thermosensitive sustainable delivery system. Electrostatically self-assembled ChS and ε-poly-l-lysine (EPL) NPs are prepared for the bioencapsulation of FGF18. This bionic delivery system suppressed the inflammatory response in interleukin-1β (IL-1β)-mediated chondrocytes, promoted macrophage M2 polarization, and inhibited M1 polarization, thereby ameliorating cartilage degeneration and synovitis in OA. Thus, the ChS-based hydrogel system offers a potential strategy to regulate the chondrocyte-macrophage crosstalk, thus re-establishing the anti-inflammatory and immunomodulatory microenvironment for OA therapy.

Collagen sponge scaffolds loaded with Trichostatin A pretreated BMSCs-derived exosomes regulate macrophage polarization to promote skin wound healing

The process of wound healing includes the inflammatory stage, which plays an important role. Macrophages can promote inflammatory response and also promote angiogenesis, wound contraction and tissue remodeling required for wound healing. It is crucial to promote macrophages to polarize from M1 pro-inflammatory phenotype to M2 anti-inflammatory phenotype at a critical time for the quality of wound healing. Because mesenchymal stem cell-derived exosomes have broad therapeutic prospects in the field of tissue repair and regeneration, in this study, we explored whether trichostatin A pretreated bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (T-Exo) could promote wound healing by binding to biomaterial scaffolds through certain anti-inflammatory effects. In the cell experiment, we established macrophage inflammation model and then treated with T-Exo, and finally detected the expression levels of macrophage polarization proteins CD206, CD86 and TNF-α, iNOS, and Arg-1 by Western Blot and immunofluorescence staining; detected the expression levels of inflammation-related genes TNF-α, iNOS, IL-1β, IL-10 and anti-inflammatory genes CD206 and Arg-1 by qRT-PCR; explored the promoting ability of T-Exo to promote cell migration and tube formation by cell scratch experiment and angiogenesis experiment. The results showed that T-Exo could promote the polarization of M1 macrophages to M2 macrophages, and promote the migration and angiogenesis of HUVECs. Because TSA pretreatment may bring about changes in the content and function of BMSCs-derived exosomes, proteomic analysis was performed on T-Exo and unpretreated BMSCs-derived exosomes (Exo). The results showed that the differentially expressed proteins in T-Exo were related to some pathways that promote angiogenesis, cell migration, proliferation, and re-epithelialization. Then, exosome/collagen sponge (T-Exo/Col) biological scaffolds were prepared, and the physicochemical properties and biocompatibility of the scaffolds were investigated. Animal skin wound models were established, and the therapeutic effect and anti-inflammatory effect of T-Exo/Col in wound repair were evaluated by small animal in vivo imaging, H&E staining, Masson trichrome staining, immunohistochemical staining, Western Blot, and qRT-PCR. The results showed that T-Exo significantly promoted wound healing by inhibiting inflammation, thereby further promoting angiogenesis and collagen formation in vivo. Moreover, the existence of Col scaffold in T-Exo/Col enabled T-Exo to achieve a certain sustained release effect. Finally, we further explored whether TSA exerts beneficial effects by inhibiting HDAC6 gene of BMSCs, but the results showed that knockdown of HDAC6 gene would cause oxidative stress damage to BMSCs, which means that TSA does not produce these beneficial effects by inhibiting HDAC6 gene. What molecular mechanisms TSA exerts beneficial effects through needs to be further elucidated in the future.

MCP-1 controls IL-17-promoted monocyte migration and M1 polarization in osteoarthritis

Osteoarthritis (OA) is a low-grade inflammatory joint illness in which monocytes migrate and infiltrate synovial tissue, differentiating into the pro-inflammatory M1 macrophage phenotype. IL-17 is a proinflammatory mediator principally generated by Th17 cells, which is elevated in OA patients; nevertheless, investigators have yet to elucidate the function of IL-17 in M1 polarization during OA development. Our analysis of clinical tissues and results from the open online dataset discovered that the level of M1 macrophage markers is elevated in human OA tissue samples than in normal tissue. High-throughput screening demonstrated that MCP-1 is a potential candidate factor after IL-17 treatment in OA synovial fibroblasts (OASFs). Immunohistochemistry data revealed that the level of MCP-1 is higher in humans and mice with OA than in normal tissues. IL-17 stimulation facilitates MCP-1-dependent macrophage polarization to the M1 phenotype. It also appears that IL-17 enhances MCP-1 synthesis in human OASFs, enhancing monocyte migration via the JAK and STAT3 signaling cascades. Our findings indicate the IL-17/MCP-1 axis as a novel strategy for the remedy of OA.

Interplay between mesenchymal stem cells and macrophages: Promoting bone tissue repair

The repair of bone tissue damage is a complex process that is well-orchestrated in time and space, a focus and difficulty in orthopedic treatment. In recent years, the success of mesenchymal stem cells (MSCs)-mediated bone repair in clinical trials of large-area bone defects and bone necrosis has made it a candidate in bone tissue repair engineering and regenerative medicine. MSCs are closely related to macrophages. On one hand, MSCs regulate the immune regulatory function by influencing macrophages proliferation, infiltration, and phenotype polarization, while also affecting the osteoclasts differentiation of macrophages. On the other hand, macrophages activate MSCs and mediate the multilineage differentiation of MSCs by regulating the immune microenvironment. The cross-talk between MSCs and macrophages plays a crucial role in regulating the immune system and in promoting tissue regeneration. Making full use of the relationship between MSCs and macrophages will enhance the efficacy of MSCs therapy in bone tissue repair, and will also provide a reference for further application of MSCs in other diseases.

Lactic acid in macrophage polarization: A factor in carcinogenesis and a promising target for cancer therapy

Cancer remains a formidable challenge, continually revealing its intricate nature and demanding novel treatment approaches. Within this intricate landscape, the tumor microenvironment and its dynamic components have gained prominence, particularly macrophages that can adopt diverse polarization states, exerting a profound influence on cancer progression. Recent revelations have spotlighted lactic acid as a pivotal player in this complex interplay. This review systematically explores lactic acid's multifaceted role in macrophage polarization, focusing on its implications in carcinogenesis. We commence by cultivating a comprehensive understanding of the tumor microenvironment and the pivotal roles played by macrophages. The dynamic landscape of macrophage polarization, typified by M1 and M2 phenotypes, is dissected to reveal its substantial impact on tumor progression. Lactic acid, a metabolic byproduct, emerges as a key protagonist, and we meticulously unravel the mechanisms underpinning its generation within cancer cells, shedding light on its intimate association with glycolysis and its transformative effects on the tumor microenvironment. Furthermore, we decipher the intricate molecular framework that underlies lactic acid's pivotal role in facilitating macrophage polarization. Our review underscores lactic acid's dual role in carcinogenesis, orchestrating tumor growth and immune modulation within the tumor microenvironment, thereby profoundly influencing the balance between pro-tumor and anti-tumor immune responses. This duality highlights the therapeutic potential of selectively manipulating lactic acid metabolism for cancer treatment. Exploring strategies to inhibit lactic acid production by tumor cells, novel approaches to impede lactic acid transport in the tumor microenvironment, and the burgeoning field of immunotherapeutic cancer therapies utilizing lactic acid-induced macrophage polarization form the core of our investigation.

NGF facilitates ICAM-1-dependent monocyte adhesion and M1 macrophage polarization in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder in which monocytes adhering to synovial tissue differentiate into the pro-inflammatory M1 macrophage phenotype. Nerve growth factors (NGF) referred to as neurotrophins have been associated with inflammatory events; however, researchers have yet to elucidate the role of NGF in RA. Our examination of clinical tissue samples and analysis of data sourced from the Gene Expression Omnibus dataset unveiled elevated expression levels of M1 macrophage markers in human RA synovial tissue samples compared to normal tissue, with no such distinction observed for M2 markers. Furthermore, immunofluorescence data depicted increased expression levels of NGF and M1 macrophages in RA mice in contrast to normal mice. It appears that NGF stimulation facilitates macrophage polarization from the M0 to the M1 phenotype. It also appears that NGF promotes ICAM-1 production in human RA synovial fibroblasts, which enhances monocyte adhesion through the TrkA, MEK/ERK, and AP-1 signaling cascades. Our findings indicate NGF/TrkA axis as a novel target for the treatment of RA.

Single-cell RNA sequencing in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is one of the most common chronic inflammatory rheumatic diseases in children, with onset before age 16 and lasting for more than 6 weeks. JIA is a highly heterogeneous condition with various consequences for health and quality of life. For some JIA patients, early detection and intervention remain challenging. As a result, further investigation of the complex and unknown mechanisms underlying JIA is required. Advances in technology now allow us to describe the biological heterogeneity and function of individual cell populations in JIA. Through this review, we hope to provide novel ideas and potential targets for the diagnosis and treatment of JIA by summarizing the current findings of single-cell RNA sequencing studies and understanding how the major cell subsets drive JIA pathogenesis.

Effect of Traditional Chinese Non-Pharmacological Therapies on Knee Osteoarthritis: A Narrative Review of Clinical Application and Mechanism

Knee osteoarthritis (KOA) stands as a degenerative ailment with a substantial and escalating prevalence. The practice of traditional Chinese non-pharmacological therapy has become a prevalent complementary and adjunctive approach. A mounting body of evidence suggests its efficacy in addressing KOA. Recent investigations have delved into its underlying mechanism, yielding some headway. Consequently, this comprehensive analysis seeks to encapsulate the clinical application and molecular mechanism of traditional Chinese non-pharmacological therapy in KOA treatment. The review reveals that various therapies, such as acupuncture, electroacupuncture, warm needle acupuncture, tuina, and acupotomy, primarily target localized knee components like cartilage, subchondral bone, and synovium. Moreover, their impact extends to the central nervous system and intestinal flora. More perfect experimental design and more comprehensive research remain a promising avenue in the future.

Regulatory macrophages in solid organ xenotransplantation

Due to a critical organ shortage, pig organs are being explored for use in transplantation. Differences between species, particularly in cell surface glycans, can trigger elevated immune responses in xenotransplantation. To mitigate the risk of hyperacute rejection, genetically modified pigs have been developed that lack certain glycans and express human complement inhibitors. Nevertheless, organs from these pigs may still provoke stronger inflammatory and innate immune reactions than allotransplants. Dysregulation of coagulation and persistent inflammation remain obstacles in the transplantation of pig organs into primates. Regulatory macrophages (Mregs), known for their anti-inflammatory properties, could offer a potential solution. Mregs secrete interleukin 10 and transforming growth factor beta, thereby suppressing immune responses and promoting the development of regulatory T cells. These Mregs are typically induced via the stimulation of monocytes or macrophages with macrophage colony-stimulating factor and interferon gamma, and they conspicuously express the stable marker dehydrogenase/reductase 9. Consequently, understanding the precise mechanisms governing Mreg generation, stability, and immunomodulation could pave the way for the therapeutic use of Mregs generated in vitro. This approach has the potential to reduce the required dosages and durations of anti-inflammatory and immunosuppressive medications in preclinical and clinical settings.

Molecular Pathways in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis

Systemic juvenile idiopathic arthritis (sJIA) is a rare childhood chronic inflammatory disorder with risk for life-threatening complications including macrophage activation syndrome and lung disease. At onset, sJIA pathogenesis resembles that of the autoinflammatory periodic fever syndromes with marked innate immune activation, expansion of neutrophils and monocytes, and high levels of interleukin-18. Here, we review the current conceptual understanding of sJIA pathogenesis with a focus on both innate and adaptive immune pathways. Finally, we consider how recent progress toward understanding the immunologic basis of sJIA may support new therapies for refractory disease courses.

Omentin-1 ameliorates the progress of osteoarthritis by promoting IL-4-dependent anti-inflammatory responses and M2 macrophage polarization

Osteoarthritis (OA) is a prevalent joint disease commonly associated with aging and obesity, which can lead to pain, stiffness, joint dysfunction, and disability. Omentin-1 (also called intelectin-1) is a newly discovered adipokine, which plays a protective role in suppressing the secretion of pro-inflammatory cytokines. Based on data from the Gene Expression Omnibus (GEO) dataset and clinical samples obtained at our institution revealed, determined that omentin-1 and IL-4 (an anti-inflammatory cytokine) levels were significantly lower in OA patients than in normal controls. Omentin-1 was shown to induce IL-4-depedent anti-inflammatory responses and M2 macrophage polarization in OA synovial fibroblasts via the PI3K, ERK, and AMPK pathways. Administering omentin-1 was shown to block cartilage degradation and bone erosion resulting from anterior cruciate ligament transection by inhibiting the production of pro-inflammatory cytokines and promoting M2 macrophage polarization in vivo. Our findings indicate omentin-1 as a promising therapeutic avenue for the treatment for OA.

The macrophage polarization by miRNAs and its potential role in the treatment of tumor and inflammation (Review)

The characteristics of monocyte/macrophage lineage are diversity and plasticity, mainly manifested by M1 and M2 subtypes in the body tissues, and playing different roles in the immunity. In the polarization process of macrophages, the classic molecular mechanism is related to sequential transcription factors. Whether in tumor or inflammatory local microenvironment, the pathological factors of the local microenvironment often affect the polarization of M1 and M2 macrophages, and participate in the occurrence and development of these pathological processes. In recent years, a growing number of research results demonstrated that non‑coding RNA (ncRNA) also participates in the polarization process of macrophages, in addition to traditional cytokines and transcriptional regulation signal pathway molecules. Among numerous ncRNAs, microRNAs (miRNAs) have attracted more attention from scholars both domestically and internationally, and significant progress has been made in basic and clinical research. Therefore, for improved understanding of the molecular mechanism of miRNAs in macrophage polarization and analysis of the potential value of this regulatory pathway in tumor and inflammatory intervention therapy, a comprehensive review of the progress of relevant literature research was conducted and some viewpoints and perspectives were proposed.

MicroRNAs in Juvenile Idiopathic Arthritis: State of the Art and Future Perspectives

Juvenile Idiopathic Arthritis (JIA) represents the most common chronic pediatric arthritis in Western countries and a leading cause of disability in children. Despite recent clinical achievements, patient management is still hindered by a lack of diagnostic/prognostic biomarkers and targeted treatment protocols. MicroRNAs (miRNAs) are short non-coding RNAs playing a key role in gene regulation, and their involvement in many pathologies has been widely reported in the literature. In recent decades, miRNA's contribution to the regulation of the immune system and the pathogenesis of autoimmune diseases has been demonstrated. Furthermore, miRNAs isolated from patients' biological samples are currently under investigation for their potential as novel biomarkers. This review aims to provide an overview of the state of the art on miRNA investigation in JIA. The literature addressing the expression of miRNAs in different types of biological samples isolated from JIA patients was reviewed, focusing in particular on their potential application as diagnostic/prognostic biomarkers. The role of miRNAs in the regulation of immune responses in affected joints will also be discussed along with their potential utility as markers of patients' responses to therapeutic approaches. This information will be of value to investigators in the field of pediatric rheumatology, encouraging further research to increase our knowledge of miRNAs' potential for future clinical applications in JIA.

Mild treadmill exercise inhibits cartilage degeneration via macrophages in an osteoarthritis mouse model

Objective

We previously reported how treadmill exercise can suppress cartilage degeneration. Here, we examined the changes in macrophage dynamics in knee osteoarthritis (OA) during treadmill exercise and the effect of macrophage depletion.

Design

OA mouse model, generated via anterior cruciate ligament transection (ACLT), was subjected to treadmill exercise of different intensities to investigate the effects on cartilage and synovium. In addition, clodronate liposomes, which deplete macrophages, were injected intra-articularly into the joint to examine the role of macrophages during treadmill exercise.

Results

Cartilage degeneration was delayed by mild exercise, and concomitantly, an increase in anti-inflammatory factors in the synovium was observed, with a decrease in the M1 and increase in M2 macrophage ratio. On the contrary, high-intensity exercise led to the progress of cartilage degeneration and was associated with an increase in the M1 and a decrease in the M2 macrophage ratio. The clodronate liposome-induced reduction of synovial macrophages delayed cartilage degeneration. This phenotype was reversed by simultaneous treadmill exercise.

Conclusions

Treadmill exercise, especially at high intensity, was detrimental to articular cartilage, whereas mild exercise reduced cartilage degeneration. Moreover, M2 macrophage response appeared necessary for the chondroprotective effect of treadmill exercise. This study indicates the importance of a more comprehensive analysis of the effects of treadmill exercise, not limited to the mechanical stress added directly to cartilage. Hence, our findings might help determine the type and intensity of prescribed exercise therapy for patients with knee OA.

Activated macrophage membrane-coated nanoparticles relieve osteoarthritis-induced synovitis and joint damage

Osteoarthritis (OA) is a common joint condition that is a leading cause of disability worldwide. There are currently no disease-modifying treatments for osteoarthritis, which is associated with multiple kinds of inflammatory cytokines produced by M1 macrophages in the synovium of the joint. Despite recent therapeutic advancements with anti-cytokine biologics, the OA therapy response rate continues to be inadequate. To treat OA, the pro-inflammatory and anti-inflammatory responses of synoviocytes and macrophages must be controlled simultaneously. Therefore, the immune regulation capabilities of an ideal nano-drug should not only minimize pro-inflammatory responses but also effectively boost anti-inflammatory responses. In this paper, an M2H@RPK nanotherapeutic system was developed, KAFAK and shRNA-LEPR were condensed with polyethylenimine (PEI) to form a complex, which was then modified with hyaluronic acid (HA) to negatively charge to cover the M2 membrane. It was discovered that the repolarization of macrophages from the M1 to the M2 phenotype lowered pro-inflammatory responses while enhancing anti-inflammatory responses in macrophages and synoviocytes. In vitro and in vivo studies demonstrate that M2H@RPK dramatically decreases proinflammatory cytokines, controls synovial inflammation, and provides significant therapeutic efficacy by reducing joint damage. Overall, it has been demonstrated that M2H@RPK provides inflammation-targeted therapy by macrophage repolarization, and it represents a promising OA therapeutic strategy.

Study of the shared gene signatures of polyarticular juvenile idiopathic arthritis and autoimmune uveitis

Objective

To explore the shared gene signatures and potential molecular mechanisms of polyarticular juvenile idiopathic arthritis (pJIA) and autoimmune uveitis (AU).

Method

The microarray data of pJIA and AU from the Gene Expression Omnibus (GEO) database were downloaded and analyzed. The GEO2R tool was used to identify the shared differentially expressed genes (DEGs) and genes of extracellular proteins were identified among them. Then, weighted gene co-expression network analysis (WGCNA) was used to identify the shared immune-related genes (IRGs) related to pJIA and AU. Moreover, the shared transcription factors (TFs) and microRNAs (miRNAs) in pJIA and AU were acquired by comparing data from HumanTFDB, hTFtarget, GTRD, HMDD, and miRTarBase. Finally, Metascape and g: Profiler were used to carry out function enrichment analyses of previously identified gene sets.

Results

We found 40 up-regulated and 15 down-regulated shared DEGs via GEO2R. Then 24 shared IRGs in positivity-related modules, and 18 shared IRGs in negatively-related modules were found after WGCNA. After that, 3 shared TFs (ARID1A, SMARCC2, SON) were screened. And the constructed TFs-shared DEGs network indicates a central role of ARID1A. Furthermore, hsa-miR-146 was found important in both diseases. The gene sets enrichment analyses suggested up-regulated shared DEGs, TFs targeted shared DEGs, and IRGs positivity-correlated with both diseases mainly enriched in neutrophil degranulation process, IL-4, IL-13, and cytokine signaling pathways. The IRGs negatively correlated with pJIA and AU mainly influence functions of the natural killer cell, cytotoxicity, and glomerular mesangial cell proliferation. The down-regulated shared DEGs and TFs targeted shared DEGs did not show particular functional enrichment.

Conclusion

Our study fully demonstrated the flexibility and complexity of the immune system disorders involved in pJIA and AU. Neutrophil degranulation may be considered the shared pathogenic mechanism, and the roles of ARID1A and MiR-146a are worthy of further in-depth study. Other than that, the importance of periodic inspection of kidney function is also noteworthy.

Bibliometric and visualization analysis of macrophages associated with osteoarthritis from 1991 to 2021

Background

Macrophages significantly contributes to symptomology and structural progression of osteoarthritis (OA) and raise increasing attention in the relative research field. Recent studies have shown that tremendous progress has been made in the research of macrophages associated with osteoarthritis. However, a comprehensive bibliometric analysis is lacking in this research field. This study aimed to introduce the research status as well as hotspots and explore the field of macrophages research in OA from a bibliometric perspective.

Methods

This study collected 1481 records of macrophages associated with osteoarthritis from 1991 to 2021 in the web of science core collection (WoSCC) database. CiteSpace, VOSviewer, and R package “bibliometrix” software were used to analyze regions, institutions, journals, authors, and keywords to predict the latest trends in macrophages associated with osteoarthritis research.

Results

The number of publications related to macrophages associated with osteoarthritis is increasing annually. China and the USA, contributing more than 44% of publications, were the main drivers for research in this field. League of European Research Universities was the most active institution and contributed the most publications. Arthritis and Rheumatism is the most popular journal in this field with the largest publications, while Osteoarthritis and Cartilage is the most co-cited journal. Koch AE was the most prolific writer, while Bondeson J was the most commonly co-cited author. “Rheumatology”, “Orthopedics”, and “Immunology” were the most widely well-represented research areas of OA associated macrophages. “Rheumatoid arthritis research”, “clinical symptoms”, “regeneration research”, “mechanism research”, “pathological features”, and “surgery research” are the primary keywords clusters in this field.

Conclusion

This is the first bibliometric study comprehensively mapped out the knowledge structure and development trends in the research field of macrophages associated with osteoarthritis in recent 30 years. The results comprehensively summarize and identify the research frontiers which will provide a reference for scholars studying macrophages associated with osteoarthritis.

Analysis of chromatin data supports a role for CD14+ monocytes/macrophages in mediating genetic risk for juvenile idiopathic arthritis

Introduction

Genome wide association studies (GWAS) have identified multiple regions that confer genetic risk for the polyarticular/oligoarticular forms of juvenile idiopathic arthritis (JIA). However, genome-wide scans do not identify the cells impacted by genetic polymorphisms on the risk haplotypes or the genes impacted by those variants. We have shown that genetic variants driving JIA risk are likely to affect both innate and adaptive immune functions. We provide additional evidence that JIA risk variants impact innate immunity.

Materials and methods

We queried publicly available H3K4me1/H3K27ac ChIP-seq data in CD14+ monocytes to determine whether the linkage disequilibrium (LD) blocks incorporating the SNPs that tag JIA risk loci showed enrichment for these epigenetic marks. We also queried monocyte/macrophage GROseq data, a functional readout of active enhancers. We defined the topologically associated domains (TADs) encompassing enhancers on the risk haplotypes and identified genes within those TADs expressed in monocytes. We performed ontology analyses of these genes to identify cellular processes that may be impacted by these variants. We also used whole blood RNAseq data from the Genotype-Tissue Expression (GTEx) data base to determine whether SNPs lying within monocyte GROseq peaks influence plausible target genes within the TADs encompassing the JIA risk haplotypes.

Results

The LD blocks encompassing the JIA genetic risk regions were enriched for H3K4me1/H3K27ac ChIPseq peaks (p=0.00021 and p=0.022) when compared to genome background. Eleven and sixteen JIA were enriched for resting and activated macrophage GROseq peaks, respectively risk regions (p=0.04385 and p=0.00004). We identified 321 expressed genes within the TADs encompassing the JIA haplotypes in human monocytes. Ontological analysis of these genes showed enrichment for multiple immune functions. Finally, we found that SNPs lying within the GROseq peaks are strongly associated with expression levels of plausible target genes in human whole blood.

Conclusions

These findings support the idea that both innate and adaptive immunity are impacted by JIA genetic risk variants.

Pentraxin 3 regulated by miR-224-5p modulates macrophage reprogramming and exacerbates osteoarthritis associated synovitis by targeting CD32

Emerging evidence has shown an imbalance in M1/M2 macrophage polarization to play an essential role in osteoarthritis (OA) progression. However, the underlying mechanistic basis for this polarization is unknown. RNA sequencing of OA M1-polarized macrophages found highly expressed levels of pentraxin 3 (PTX3), suggesting a role for PTX3 in OA occurrence and development. Herein, PTX3 was found to be increased in the synovium and articular cartilage of OA patients and OA mice. Intra-articular injection of PTX3 aggravated, while PTX3 neutralization reversed synovitis and cartilage degeneration. No metabolic disorder or proteoglycan loss were observed in cartilage explants when treated with PTX3 alone. However, cartilage explants exhibited an OA phenotype when treated with culture supernatants of macrophages stimulated with PTX3, suggesting that PTX3 did not have a direct effect on chondrocytes. Therefore, the OA anti-chondrogenic effects of PTX3 are primarily mediated through macrophages. Mechanistically, PTX3 was upregulated by miR-224-5p deficiency, which activated the p65/NF-κB pathway to promote M1 macrophage polarization by targeting CD32. CD32 was expressed by macrophages, that when stimulated with PTX3, secreted abundant pro-inflammation cytokines that induced severe articular cartilage damage. The paracrine interaction between macrophages and chondrocytes produced a feedback loop that enhanced synovitis and cartilage damage. The findings of this study identified a functional pathway important to OA development. Blockade of this pathway and PTX3 may prevent and treat OA.

Anakinra in Patients With Systemic Juvenile Idiopathic Arthritis: Long-term Safety From the Pharmachild Registry

OBJECTIVE

To evaluate the long-term safety profile of anakinra in patients with systemic juvenile idiopathic arthritis (sJIA).

METHODS

Data from patients with sJIA enrolled in the Pharmachild registry (ClinicalTrials.gov: NCT03932344) prior to September 30, 2018, and treated with anakinra were analyzed. The study endpoints were the occurrence of non-serious adverse events (SAEs) of at least moderate severity and SAEs, including macrophage activation syndrome (MAS), and the duration of anakinra treatment with reasons for discontinuation. All endpoints were analyzed overall by 6-month time windows, and in different treatment sets represented by those patients treated continuously with anakinra for at least 12, 18, and 24 months (set-12, -18, and -24, respectively).

RESULTS

Three hundred six patients were enrolled. Of these patients, 46%, 34%, and 28% had been treated for at least 12, 18, and 24 months, respectively. Two hundred and one AEs, mostly represented by infections, were reported for 509.3 patient-years (PY) with an overall incidence rate (IR) of 39.5 per 100 PY. Among 56 SAEs (IR 11.0/100 PY), 23.2% were infections and 19.6% MAS episodes. The IR of AEs was higher during the first 6 months of anakinra treatment, followed by decreasing IRs in the long-term treatment sets. Treatment discontinuation occurred in 76% of patients, most frequently in the first 6 months, because of inefficacy (43%), remission (31%), or AEs/intolerance (15%). No deaths or malignancies occurred during anakinra treatment.

CONCLUSION

The results of the present study confirm the long-term safety profile of anakinra in patients with sJIA and demonstrate an overall decreasing incidence of AEs over time. [ClinicalTrials.gov: NCT01399281 and NCT03932344].

Cell-Crossing Functional Network Driven by microRNA-125a Regulates Endothelial Permeability and Monocyte Trafficking in Acute Inflammation

Opening of the endothelial barrier and targeted infiltration of leukocytes into the affected tissue are hallmarks of the inflammatory response. The molecular mechanisms regulating these processes are still widely elusive. In this study, we elucidate a novel regulatory network, in which miR-125a acts as a central hub that regulates and synchronizes both endothelial barrier permeability and monocyte migration. We found that inflammatory stimulation of endothelial cells induces miR-125a expression, which consecutively inhibits a regulatory network consisting of the two adhesion molecules VE-Cadherin (CDH5) and Claudin-5 (CLDN5), two regulatory tyrosine phosphatases (PTPN1, PPP1CA) and the transcription factor ETS1 eventually leading to the opening of the endothelial barrier. Moreover, under the influence of miR-125a, endothelial expression of the chemokine CCL2, the most predominant ligand for the monocytic chemokine receptor CCR2, was strongly enhanced. In monocytes, on the other hand, we detected markedly repressed expression levels of miR-125a upon inflammatory stimulation. This induced a forced expression of its direct target gene CCR2, entailing a strongly enhanced monocyte chemotaxis. Collectively, cell-type-specific differential expression of miR-125a forms a synergistic functional network controlling monocyte trafficking across the endothelial barrier towards the site of inflammation. In addition to the known mechanism of miRNAs being shuttled between cells via extracellular vesicles, our study uncovers a novel dimension of miRNA function: One miRNA, although disparately regulated in the cells involved, directs a biologic process in a synergistic and mutually reinforcing manner. These findings provide important new insights into the regulation of the inflammatory cascade and may be of great use for future clinical applications.

The role of epigenetics in childhood autoimmune diseases with hematological manifestations

Autoimmune diseases with hematological manifestations are often characterized by chronicity and relapses despite treatment, and the underlying pathogenetic mechanisms remain unknown. Epigenetic alterations play a vital role in the deregulation of immune tolerance and the development of autoimmune diseases. In recent years, study of epigenetic mechanisms in both adult and childhood autoimmune disorders has been seeking to explain the pathophysiology of these heterogeneous diseases and to elucidate the interaction between genetic and environmental factors. Various mechanisms, including DNA methylation, histone modifications (chromatin remodeling), and noncoding RNAs (ncRNAs), have been studied extensively in the context of autoimmune diseases. This paper summarizes the epigenetic patterns in some of the most common childhood autoimmune disorders with hematological manifestations, based on epigenetic studies in children with primary immune thrombocytopenia (ITP), systemic lupus erythematosus (SLE), and juvenile idiopathic arthritis (JIA). Research findings indicate that methylation changes in genes expressed on T cells, modifications at a variety of histone sites, and alterations in the expression of several ncRNAs are involved in the pathogenesis of these diseases. These mechanisms not only determine the development of these diseases but also affect the severity of the clinical presentation and biochemical markers. Further studies will provide new tools for the prevention and diagnosis of childhood autoimmune disorders, and possible novel treatment options.

Inhibition of Knee Osteoarthritis Progression in Mice by Administering SRT2014, an Activator of Silent Information Regulator 2 Ortholog 1

OBJECTIVE

Previous findings suggest that silent information regulator 2 ortholog 1 (SIRT1) plays essential roles in chondrocytes and prevents osteoarthritis (OA) development. The purpose of this study was to investigate the effects of intraperitoneal (i.p.) and intra-articular (i.a.) administration of the SIRT1 activator SRT2104, which has been approved for use in humans.

DESIGN

OA was induced by destabilizing the medial meniscus in the knee joint of 12-week-old CL57BL/6J mice. The mice were divided into 3 groups, that is, the control group, SRT2104 i.p.-injection group, and SRT2104 i.a.-injection group. Tissues were harvested at 4, 8, 12, and 16 weeks postsurgery. OA progression was evaluated using the Osteoarthritis Research Society International (OARSI) score. The production of OA-related proteins in cartilage and synovium was examined by immunohistochemistry.

RESULTS

OARSI scores in the control group were significantly higher at 8 and 12 weeks compared with other 2 groups. Immunohistochemical analysis showed that Sirt1 and type-2 collagen significantly increased, whereas MMP-13, ADAMTS-5, IL-1β, IL-6, cleaved caspase 3, PARP p85, acetylated NF-κB p65, and iNOS decreased significantly in cartilage tissues from the i.p. and i.a, SRT2104 groups. In the synovium, more iNOS-positive M1-like macrophages were observed in the control group than in the i.p. and i.a, SRT2104 groups, whereas more CD206-positive M2-like macrophages were detected in the i.p. and i.a. SRT2104 groups.

CONCLUSIONS

Both i.p. and i.a. SRT2104 injection reduced OA progression in the mouse OA model, suggesting that SRT2104 can serve as a new treatment for OA.

Significance of Macrophage Subtypes in the Peripheral Blood of Children with Systemic Juvenile Idiopathic Arthritis

INTRODUCTION

Symptomatic juvenile idiopathic arthritis (sJIA) is an autoinflammatory disease, and monocytes/macrophages play an important role. However, which macrophage subtype plays a major role in different stages of sJIA is still unclear. This study aimed to explore macrophage subtypes in different stages of sJIA.

METHODS

Twenty-two children with sJIA who were followed up at Shanghai Children's Hospital from January 2018 to December 2020 were enrolled in this study. sJIA children were divided into an activity group (n = 12) and an inactivity group (n = 10). In the activity group, subjects with newly diagnosed sJIA and untreated were included; in the inactivity group, subjects with inactive sJIA meeting the 2011 ACR criteria for sJIA were recruited. Ten children with orthostatic proteinuria served as controls. Peripheral blood was collected. Flow cytometry was performed to detect macrophage subtypes: M1 (CD14⁺CD86⁺CD80⁺), M2a (CD14⁺CD206⁺CD301⁺), M2b (CD14⁺CD206⁺CD86⁺) and M2c (CD14⁺CD206⁺CD163⁺), and the contents of cytokines were also examined, including interleukins (IL) (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10 and IL-17), interferon-α, interferon-γ, and tumor necrosis-α.

RESULTS

M1 marker CD80 and M2 marker CD163, CD301 were highly expressed in children with active sJIA. The majority of macrophages were M1 and M2a in the activity group (P < 0.05). In the inactivity group, M2 tended to polarize into M2b and M2c (P < 0.05). IL-6 significantly increased in the activity group (P < 0.05), while IL-10, IL-4 and IL-17 markedly increased in the inactivity group (P < 0.05).

CONCLUSIONS

In the active sJIA, M1 activation promotes inflammation, while M2a rapidly responds to inhibit inflammation; in the inactive sJIA, M2b and M2c play a major role in inhibiting inflammation.

miR-23a contributes to T cellular redox metabolism in juvenile idiopathic oligoarthritis

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease of unknown origin. The regulation of inflammatory processes involves multiple cellular steps including mRNA transcription and translation. Different miRNAs tightly control these processes. We aimed to determine the roles of specific miRNAs within JIA pathogenesis.

METHODS

We performed a global miRNA expression analysis in parallel in cells from the arthritic joint and peripheral blood of oligoarticular JIA patients and healthy controls. QRT-PCR analysis was used to verify expression of miRNA in T cells. Ex vivo experiments and flow cytometric analyses were used to analyze proliferation and redox metabolism.

RESULTS

Global miRNA expression analysis demonstrated a different composition of miRNA expression at the site of inflammation compared with peripheral blood. Bioinformatic analysis of predicted miRNA target genes suggest a huge overrepresentation of genes involved in metabolic and oxidative stress pathways in the inflamed joint. Despite enhanced ROS levels within the local inflammatory milieu, JIA T cells are hyperproliferative and reveal an overexpression of miR-23a, which is an inhibitor of PPIF, the regulator of mitochondrial ROS escape. Mitochondrial ROS escape is diminished in JIA T cells resulting in their prolonged survival.

CONCLUSION

Our data suggest that miRNA dependent mitochondrial ROS shuttling might be a mechanism that contributes to T cell regulation in JIA at the site of inflammation.

Signals and Mechanisms Regulating Monocyte and Macrophage Activation in the Pathogenesis of Juvenile Idiopathic Arthritis

Monocytes (Mos) and macrophages (Mφs) are key players in the innate immune system and are critical in coordinating the initiation, expansion, and regression of many autoimmune diseases. In addition, they display immunoregulatory effects that impact inflammation and are essential in tissue repair and regeneration. Juvenile idiopathic arthritis (JIA) is an umbrella term describing inflammatory joint diseases in children. Accumulated evidence suggests a link between Mo and Mφ activation and JIA pathogenesis. Accordingly, topics regarding the signals and mechanisms regulating Mo and Mφ activation leading to pathologies in patients with JIA are of great interest. In this review, we critically summarize recent advances in the understanding of how Mo and Mφ activation is involved in JIA pathogenesis and focus on the signaling pathways and mechanisms participating in the related cell activation processes.

Tuning Monocytes and Macrophages for Personalized Therapy and Diagnostic Challenge in Rheumatoid Arthritis

Monocytes/macrophages play a central role in chronic inflammatory disorders, including rheumatoid arthritis (RA). Activation of these cells results in the production of various mediators responsible for inflammation and RA pathogenesis. On the other hand, the depletion of macrophages using specific antibodies or chemical agents can prevent their synovial tissue infiltration and subsequently attenuates inflammation. Their plasticity is a major feature that helps the switch from a pro-inflammatory phenotype (M1) to an anti-inflammatory state (M2). Therefore, understanding the precise strategy targeting pro-inflammatory monocytes/macrophages should be a powerful way of inhibiting chronic inflammation and bone erosion. In this review, we demonstrate potential consequences of different epigenetic regulations on inflammatory cytokines production by monocytes. In addition, we present unique profiles of monocytes/macrophages contributing to identification of new biomarkers of disease activity or predicting treatment response in RA. We also outline novel approaches of tuning monocytes/macrophages by biologic drugs, small molecules or by other therapeutic modalities to reduce arthritis. Finally, the importance of cellular heterogeneity of monocytes/macrophages is highlighted by single-cell technologies, which leads to the design of cell-specific therapeutic protocols for personalized medicine in RA in the future.

Novel biomarkers for prediction of outcome and therapeutic response in juvenile idiopathic arthritis

INTRODUCTION

The search for biomarkers in juvenile idiopathic arthritis (JIA) is a promising and rapidly expanding field of investigation. The biomarkers identified so far may help to dissect the clinical heterogeneity of the illness, measure the level of disease activity, predict clinical remission, relapse, response to medications, course over time, complications, and forestall disease flares.

AREAS COVERED

We provide a summary of the most recent advances in the development and application of biomarkers in JIA. We performed a PubMed search for significant articles combining predetermined keywords related to biomarkers in non-systemic and systemic JIA, chronic uveitis, and macrophage activation syndrome (MAS). The biomarkers available or under study are presented and discussed separately for non-systemic and systemic subtypes and for the two main disease complications, uveitis and MAS.

EXPERT OPINION

The incorporation of valid and reliable biomarkers in standard clinical care may help to design better patient-tailored treatment regimens and to improve the therapeutic strategies based on the treat-to-target approach. The establishment of biomarkers that predict the risk of disease flare may lead to define the optimal modalities for treatment discontinuation after the achievement of clinical remission.

Pseudolaric acid B ameliorates synovial inflammation and vessel formation by stabilizing PPARγ to inhibit NF-κB signalling pathway

Synovial macrophage polarization and inflammation are essential for osteoarthritis (OA) development, yet the molecular mechanisms and regulation responsible for the pathogenesis are still poorly understood. Here, we report that pseudolaric acid B (PAB) attenuated articular cartilage degeneration and synovitis during OA. PAB, a diterpene acid, specifically inhibited NF-κB signalling and reduced the production of pro-inflammatory cytokines, which further decreased M1 polarization and vessel formation. We further provide in vivo and in vitro evidences that PAB suppressed NF-κB signalling by stabilizing PPARγ. Using PPARγ antagonist could abolish anti-inflammatory effect of PAB and rescue the activation of NF-κB signalling during OA. Our findings identify a previously unrecognized role of PAB in the regulation of OA and provide mechanisms by which PAB regulates NF-κB signalling through PPARγ, which further suggest targeting synovial inflammation or inhibiting vessel formation at early stage could be an effective preventive strategy for OA.

Fargesin ameliorates osteoarthritis via macrophage reprogramming by downregulating MAPK and NF-κB pathways

Background

To investigate the role and regulatory mechanisms of fargesin, one of the main components of Magnolia fargesii, in macrophage reprogramming and crosstalk across cartilage and synovium during osteoarthritis (OA) development.

Methods

Ten-week-old male C57BL/6 mice were randomized and assigned to vehicle, collagenase-induced OA (CIOA), or CIOA with intra-articular fargesin treatment groups. Articular cartilage degeneration was evaluated using the Osteoarthritis Research Society International (OARSI) score. Immunostaining and western blot analyses were conducted to detect relative protein. Raw264.7 cells were treated with LPS or IL-4 to investigate the role of polarized macrophages. ADTC5 cells were treated with IL-1β and conditioned medium was collected to investigate the crosstalk between chondrocytes and macrophages.

Results

Fargesin attenuated articular cartilage degeneration and synovitis, resulting in substantially lower Osteoarthritis Research Society International (OARSI) and synovitis scores. In particular, significantly increased M2 polarization and decreased M1 polarization in synovial macrophages were found in fargesin-treated CIOA mice compared to controls. This was accompanied by downregulation of IL-6 and IL-1β and upregulation of IL-10 in serum. Conditioned medium (CM) from M1 macrophages treated with fargesin reduced the expression of matrix metalloproteinase-13, RUNX2, and type X collagen and increased Col2a1 and SOX9 in OA chondrocytes, but fargesin alone did not affect chondrocyte catabolic processes. Moreover, fargesin exerted protective effects by suppressing p38/ERK MAPK and p65/NF-κB signaling.

Conclusions

This study showed that fargesin switched the polarized phenotypes of macrophages from M1 to M2 subtypes and prevented cartilage degeneration partially by downregulating p38/ERK MAPK and p65/NF-κB signaling. Targeting macrophage reprogramming or blocking the crosstalk between macrophages and chondrocytes in early OA may be an effective preventive strategy.

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.

Serum miRNA Signature in Rheumatoid Arthritis and "At-Risk Individuals"

Background

MicroRNAs (miRNAs) are small non-coding RNAs which have been implicated as potential biomarkers or therapeutic targets in autoimmune diseases. This study examines circulatory miRNAs in RA patients and further investigates if a serum miRNA signature precedes clinical manifestations of disease in arthralgia or “at-risk individuals”.

Methods

Serum was collected from HC subjects (N = 20), RA patients (N = 50), and arthralgia subjects (N = 10), in addition to a subgroup of the RA patients post-methotrexate (MTX) (N = 18). The FirePlex miRNA Immunology-V2 panel was selected for multiplex analysis of 68 miRNAs in each sample. DNA intelligent analysis (DIANA)-mirPath and Ingenuity Pathway Analysis (IPA) software were used to predict pathways targeted by the dysregulated miRNAs.

Results

8 miRNA (miR-126-3p, let-7d-5p, miR-431-3p, miR-221-3p, miR-24-3p, miR-130a-3p, miR-339-5p, let-7i-5p) were significantly elevated in RA serum compared to HC (all p < 0.01) and 1 miRNA (miR-17-5p) was significantly lower in RA (p < 0.01). High specificity and sensitivity were determined by receiver operating characteristic (ROC) curve analysis. Both miR-339-5p and let-7i-5p were significantly reduced post-MTX (both p < 0.01). MiR-126-3p, let-7d-5p, miR-431-3p, miR-221-3p, miR-24-3p, miR-130a-3p were also significantly elevated in subjects “at risk” of developing RA (all p < 0.05) compared to HC. IPA analysis of this miRNA signature identified downstream targets including key transcription factors NF-κB, STAT-1, STAT-3, cytokines IL-1β, TNF-α, and matrix-metalloproteases all importantly associated with RA pathogenesis.

Conclusion

This study identified six miRNAs that are altered in both RA and “at-risk individuals,” which potentially regulate key downstream pathways involved in regulating inflammation. These may have potential as predictive signature for disease onset and early progression.

The Potential Importance of MicroRNAs as Novel Indicators How to Manage Patients with Juvenile Idiopathic Arthritis More Effectively

Small, noncoding sequences of ribonucleic acid called microRNAs (miRNAs, miR) are functioning as posttranscriptional regulators of gene expression. As they draw increasing attention of rheumatologists, there is a growing body of evidence concerning specific molecules that may affect the long-term care of patients with inflammatory arthritides. Findings involving children with juvenile idiopathic arthritis (JIA) are still limited though. The aim of the study was to browse the available data on microRNAs which may be utilized as potential biomarkers helpful in diagnosing and monitoring JIA patients. The review contains a brief summary on the most studied sequences: miR-16, miR-125a-5p, miR-146a, miR-155, and miR-223. It is complemented with other miRNAs possibly relevant for JIA (miR-145, miR-23b, miR-27a, and miR-204) and discussion on challenges for using miRNAs in pediatric rheumatology (particularly, issues regarding specificity of biomarkers and measurements involving synovial fluid).

MicroRNAs Associated With a Good Prognosis of Acute Myeloid Leukemia and Their Effect on Macrophage Polarization

Acute myeloid leukemia (AML) is an aggressive myeloid malignancy with poor outcomes despite very intensive therapeutic approaches. For the majority of patients which are unfit and treated less intensively, the prognosis is even worse. There has been unspectacular progress in outcome improvement over the last decades and the development of new approaches is of tremendous interest. The tumor microenvironment is credited with an important role in supporting cancer growth, including leukemogenesis. Macrophages are part of the tumor microenvironment and their contribution in this setting is increasingly being deciphered, these cells being credited with a tumor supporting role. Data on macrophage role and polarization in leukemia is scarce. MicroRNAs (miRNAs) have a role in the post-transcriptional regulation of gene expression, by impending translation and promoting degradation of messenger RNAs. They are important modulators of cellular pathways, playing major roles in normal hematopoietic differentiation. miRNA expression is significantly correlated with the prognosis of hematopoietic malignancies, including AML. Oncogenic miRNAs correlate with poor prognosis, while tumor suppressor miRNAs, which inhibit the expression of proto-oncogenes, are correlated with a favorable prognosis. miRNAs are proposed as biomarkers for diagnosis and prognosis and are regarded as therapeutic approaches in many cancers, including AML. miRNAs with epigenetic or modulatory activity, as well as with synergistic activity with chemotherapeutic agents, proved to be promising therapeutic targets in experimental, pre-clinical approaches. The clinical availability of emerging compounds with mimicking or suppressor activity provides the opportunity for future therapeutic targeting of miRNAs. The present paper is focusing on miRNAs which, according to current knowledge, favorably impact on AML outcomes, being regarded as tumor suppressors, and reviews their role in macrophage polarization. We are focusing on miRNA expression in the setting of AML, but data on correlations between miRNA expression and macrophage polarization is mostly coming from studies involving normal tissue.

Bone marrow mesenchymal stem cell-derived exosomes prevent osteoarthritis by regulating synovial macrophage polarization

Osteoarthritis is a chronic degenerative disease that can lead to restricted activity or even disability. Bone marrow mesenchymal stem cells can repair cartilage damage and treat osteoarthritis via cell therapies or in-tissue engineering. Research has shown that the paracrine mechanism is the main mode of action of mesenchymal stem cells. Exosomes are the smallest known membrane-bound nanovesicles. Exosomes are also important carriers of paracrine delivery agents and promote communication between cells. We demonstrated that bone marrow mesenchymal stem cell-derived exosomes can delay the progression of osteoarthritis. Exosomes alleviate cartilage damage, reduce osteophyte formation and synovial macrophage infiltration, inhibit M1 macrophage production and promote M2 macrophage generation. In synovial fluid, the expression levels of the proinflammatory cytokines, IL-1β, IL-6, and TNF-α were decreased and the release of the anti-inflammatory cytokine, IL-10 was increased. In vitro, macrophages treated with exosomes maintain chondrocytes’ chondrogenic characteristics and inhibit hypertrophy. Our results demonstrated that bone marrow mesenchymal stem cell-derived exosomes may relieve osteoarthritis by promoting the phenotypic transformation of synovial macrophages from M1 to M2.

Monocyte and bone marrow macrophage transcriptional phenotypes in systemic juvenile idiopathic arthritis reveal TRIM8 as a mediator of IFN-γ hyper-responsiveness and risk for macrophage activation syndrome

OBJECTIVES

Systemic juvenile idiopathic arthritis (SJIA) confers high risk for macrophage activation syndrome (MAS), a life-threatening cytokine storm driven by interferon (IFN)-γ. SJIA monocytes display IFN-γ hyper-responsiveness, but the molecular basis of this remains unclear. The objective of this study is to identify circulating monocyte and bone marrow macrophage (BMM) polarisation phenotypes in SJIA including molecular features contributing to IFN response.

METHODS

Bulk RNA-seq was performed on peripheral blood monocytes (n=26 SJIA patients) and single cell (sc) RNA-seq was performed on BMM (n=1). Cultured macrophages were used to define consequences of tripartite motif containing 8 (TRIM8) knockdown on IFN-γ signalling.

RESULTS

Bulk RNA-seq of SJIA monocytes revealed marked transcriptional changes in patients with elevated ferritin levels. We identified substantial overlap with multiple polarisation states but little evidence of IFN-induced signature. Interestingly, among the most highly upregulated genes was TRIM8, a positive regulator of IFN-γ signalling. In contrast to PBMC from SJIA patients without MAS, scRNA-seq of BMM from a patient with SJIA and MAS identified distinct subpopulations of BMM with altered transcriptomes, including upregulated IFN-γ response pathways. These BMM also showed significantly increased expression of TRIM8. In vitro knockdown of TRIM8 in macrophages significantly reduced IFN-γ responsiveness.

CONCLUSIONS

Macrophages with an 'IFN-γ response' phenotype and TRIM8 overexpression were expanded in the bone marrow from an MAS patient. TRIM8 is also upregulated in SJIA monocytes, and augments macrophage IFN-γ response in vitro, providing both a candidate molecular mechanism and potential therapeutic target for monocyte hyper-responsiveness to IFNγ in cytokine storms including MAS.

The Multi-Omics Architecture of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is highly heterogeneous in terms of etiology and clinical presentation with ambiguity in JIA classification. The advance of high-throughput omics technologies in recent years has gained us significant knowledge about the molecular mechanisms of JIA. Besides a minor proportion of JIA cases as monogenic, most JIA cases are polygenic disease caused by autoimmune mechanisms. A number of HLA alleles (including both HLA class I and class II genes), and 23 non-HLA genetic loci have been identified of association with different JIA subtypes. Omics technologies, i.e., transcriptome profiling and epigenomic analysis, contributed significant knowledge on the molecular mechanisms of JIA in addition to the genetic approach. New molecular knowledge on different JIA subtypes enables us to reconsider the JIA classification, but also highlights novel therapeutic targets to develop a cure for the devastating JIA.

Modification of PLGA Scaffold by MSC-Derived Extracellular Matrix Combats Macrophage Inflammation to Initiate Bone Regeneration via TGF-β-Induced Protein

The immunologic response toward chronic inflammation or bone regeneration via the accumulation of M1 or M2 macrophages after injury could determine the fate of biomaterial. Human umbilical cord mesenchymal stem cells (hUCMSCs) have a pivotal immunomodulatory property on directing macrophage behaviors. Herein, for the first time, 3D-printed poly(lactide-co-glycolide) (PLGA) scaffolds modified with hUCMSC-derived extracellular matrix (PLGA-ECM) are prepared by a facile tissue engineering technique with physical decellularization and 2.44 ± 0.29 mg cm^-3 proteins immobilized on the PLGA-ECM contain multiple soluble cytokines with a sustainable release profile. The PLGA-ECM not only attenuates the foreign body response, but also improves bone regeneration by increasing the accumulation of M2 macrophages in an improved heterotopic transplantation model of SCID mice. Furthermore, the PLGA-ECM scaffolds with the knockdown of transforming growth factor-β-induced protein (TGFβI/βig-H3) demonstrate that M2 macrophage accumulation improved by the PLGA-ECM could be attributed to increasing the migration of M2 macrophages and the repolarization of M1 macrophages to M2 phenotype, which are mediated by multiple integrin signaling pathways involving in integrin β7, integrin α9, and integrin β1 in a TGFβI-dependent manner. This study presents an effective surface modification strategy of polymeric scaffolds to initiate tissue regeneration and combat inflammatory response by increasing M2 macrophage accumulation.

Macrophages regulate the progression of osteoarthritis

OA is now well accepted as a low-grade inflammatory disease affecting the whole joint. In addition to mechanical loading, inflammation (particularly synovitis), contributes significantly to OA. Synovial macrophages act as immune cells and are of critical importance in the symptomology and structural progression of OA. Activated macrophages are regulated by mTOR, NF-κB, JNK, PI3K/Akt and other signaling pathways, and are polarized into either M1 or M2 subtypes in OA synovial tissues, synovial fluid, and peripheral blood. The activation state and the M1/M2 ratio is highly associated with OA severity. Aside from autocrine interactions, paracrine interactions between macrophages and chondrocytes play a vital role in the initiation and development of OA by secreting inflammatory cytokines, growth factors, matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs), which lead to subsequent cartilage degradation and destruction. Treatments targeting synovial macrophages relieve pain, and protect from synovitis, cartilage damage, and osteophyte formation during OA development. Macrophage reprogramming of transformation from the M1 to M2 subtype, more than a decrease in the quantity of activated macrophages, appears to be an effective treatment option for OA. This review provides a broad understanding of the contributions of polarized macrophages to joint health and disease. Multifunctional agents with immunomodulatory effects on macrophage reprogramming can skew the inflammatory microenvironment towards a pro-chondrogenic atmosphere, and are thus, potential therapeutic options for the treatment of OA and other immune diseases.

Measurement of circulating miRNA-125a exhibits good value in the management of etanercept-treated psoriatic patients

This study aimed to explore the correlation of miR-125a with risk and severity of psoriasis, and further investigate the potential of miR-125a for predicting response to etanercept (ETN) treatment in psoriatic patients. Moderate to severe plaque psoriatic patients (n = 126) about to undergo ETN treatment for 6 months were recruited. Their plasma samples were obtained, and Psoriasis Area and Severity Index (PASI) scores and PASI-75 response rate were assessed at baseline (M0), and at 1 (M1), 3 (M3) and 6 months (M6) of treatment. Referring to PASI-75 response status at M6, patients were categorized as PASI-75 responders and PASI-75 non-responders. Healthy controls (HC, n =120) were also enrolled and their plasma samples were collected. In addition, plasma miR-125a was determined by quantitative polymerase chain reaction. miR-125a was decreased in psoriatic patients compared with HC; further, the receiver-operator curve (ROC) exhibited that miR-125a was of good value in differentiating psoriatic patients from HC with an area under the curve (AUC) of 0.802. In psoriatic patients, miR-125a was negatively associated with PASI score to some extent. Interestingly, baseline miR-125a was lower in PASI-75 responders than PASI-75 non-responders; further, ROC showed it predicted PASI-75 response at M6 to some extent with AUC of 0.672. Multivariate logistic regression also revealed that miR-125a was an independent predictive factor for worse PASI-75 response at M6. Furthermore, miR-125a expression was gradually increased during the treatment in PASI-75 responders, but unchanged in PASI-75 non-responders. Measurement of circulating miR-125a exhibits good value in the management of ETN-treated psoriatic patients.

Synovial-Fluid miRNA Signature for Diagnosis of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory rheumatism in childhood; microRNAs (miRNAs) have been proposed as diagnostic biomarkers. Although joints are the primary targets for JIA, a synovial fluid-based miRNA signature has never been studied. We aim to identify miRNA biomarkers in JIA by comparing synovial fluid and serum samples from children with JIA and K. kingae septic arthritis (SA). With next-generation high-throughput sequencing, we measured the absolute levels of 2083 miRNAs in synovial fluid and serum from an exploratory cohort of children and validated differentially expressed miRNAs in a replication study by using RT-qPCR. We identified a 19-miRNA signature only in synovial fluid samples that was significantly deregulated, with at least 2-fold change in expression, in JIA versus SA (p < 0.01). The combination of miR-6764-5p, miR-155, and miR-146a-5p expression in synovial fluid yielded an area under the receiver operating characteristic curve of 1 (95% CI 0.978 to 1), thereby perfectly differentiating JIA from SA in children. We propose, for the first time, a synovial fluid-specific miRNA signature for JIA and associated signaling pathways that may indicate potential biomarkers to assist in the classification and differential diagnosis of JIA and help in understanding JIA pathogenesis.

Functional Regulation of Macrophage Phenotypes by MicroRNAs in Inflammatory Arthritis

Inflammatory arthritis including rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) exhibit the shared feature of changes in activation and polarization of circulating monocytes and tissue macrophages. Numerous microRNAs (miRs) have been found to have key functions in regulating inflammation and macrophage polarization. Although there is increasing interest in the roles of miRs in both RA and JIA, less is known regarding how miRs relate to functional properties of immune cells, including monocytes and macrophages. Interestingly, miRs can function both to promote inflammatory phenotypes and pro-inflammatory polarization, as well as through negative-feedback loops to limit inflammation. Here, we review the functional roles of several miRs in macrophages in inflammatory arthritis, with a particular focus on vivo effects of miR alteration in experimental arthritis. We also consider how current efforts to target miRs clinically could modify functional monocyte and macrophage polarization in vivo, and serve as novel therapies for diseases such as RA and JIA.

Elevated serum levels of interleukin-10 in adult-onset Still's disease are associated with disease activity

To evaluate the serum levels of the anti-inflammatory cytokine interleukin-10 (IL-10) in patients with adult-onset Still's disease (AOSD), a rare, systemic, and multigenic inflammatory disease. The serum levels of IL-10, IL-1β, IL-6, IL-18, and TNF-α were examined by electrochemiluminescence assay. The serum levels of IL-10 were higher in AOSD patients than in healthy controls and positively correlated with systemic score, erythrocyte sedimentation rate (ESR), C-reactive protein level (CRP), ferritin, and inflammatory cytokine (IL-1β, IL-6, IL-18, and TNF-α) levels. Moreover, the levels of IL-10 were significantly higher in AOSD patients who had fever, sore throat, rash, lymphadenopathy, splenomegaly, pneumonia, and arthralgia than in patients who did not. IL-10 was increased in AOSD patients and correlated with disease activity. KEY POINTS: • In this manuscript, we confirmed the elevated serum levels of the anti-inflammatory cytokine IL-10 in AOSD patients, which was previously poorly defined. • We revealed for the first time that the levels of IL-10 were correlated with disease activity and inflammatory cytokine levels in AOSD.

The role of damage-associated molecular pattern for pathogenesis and biomarkers in adult-onset Still's disease

Introduction: Adult-onset Still's disease (AOSD) is a systemic inflammatory disease, which presents itself as an adult form of systemic juvenile idiopathic arthritis. Innate immune activation driven by a combination of genetic and environmental factors is the primary mechanism underlying disease pathogenesis in AOSD patients. Few biomarkers have been identified for AOSD diagnosis or for the assessment of disease activity or prediction of clinical outcomes. Damage-associated molecular patterns (DAMPs) can activate innate immunity, resulting in tissue damage. Changes in several DAMPs are associated with disease pathogenesis in AOSD patients. Areas covered: This review describes the role of DAMPs in AOSD pathogenesis and discusses their potential for use as disease biomarkers. Together with overall pathogenesis of AOSD, high-mobility group box-1, advanced glycation end products, S100 proteins, and neutrophil extracellular traps are introduced and discussed in detail. Expert opinion: The activation of macrophages and neutrophils is associated with several DAMPs, causing high concentrations of proinflammatory cytokines in AOSD patients. Involvement of certain DAMPs in AOSD patients is well documented due to the presence of sterile inflammation; however, direct evidence for some DAMPs is lacking. Further research into the role of DAMP molecules in AOSD patients may reveal new biomarkers and provide targets for disease intervention.

Micro-RNAs in inflammatory arthritis: From physiopathology to diagnosis, prognosis and therapeutic opportunities

Micro-RNAs are an area of research exponentially expanding over the past years. These small sequences of 20-22 nucleotides have a strong role as post-transcriptional regulators of gene expression. Inflammatory arthritis pathophysiology involves various key players from innate to adaptive immunity, as well as various signalling pathways of inflammation. In this review, we discuss how micro-RNAs are involved in rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis and juvenile inflammatory arthritis, from pre-clinical phases to established diseases. We describe mi-RNAs key roles in fibroblast like synoviocytes migration, proliferation, apoptosis and cytokine production, in macrophages polarization, as well as in B cells and T cell proliferation and differentiation, with a special emphasis on Treg/Th17 imbalance. We finally discuss the application of these findings in pre-clinical models and highlight opportunities and limits of a therapeutic approach using mi-RNAs agonists or antagonists.

A Multiparameter Flow Cytometry Analysis Panel to Assess CD163 mRNA and Protein in Monocyte and Macrophage Populations in Hyperinflammatory Diseases

CD163 facilitates regulation and resolution of inflammation and removal of free hemoglobin and is highly expressed in myeloid cells from patients with inflammatory disorders, such as systemic juvenile idiopathic arthritis (SJIA) and macrophage activation syndrome (MAS). Our recent studies indicate that regulation of CD163 mRNA expression is a key functional property of polarized monocytes and macrophages and is mediated at the transcriptional and posttranscriptional level, including via microRNAs. The goal of the current study is to develop a multiparameter flow cytometry panel incorporating detection of CD163 mRNA for polarized monocyte and macrophage populations in disorders such as SJIA and MAS. THP-1 cells and CD14⁺ human monocytes were stained using fluorochrome-conjugated Abs to myeloid surface markers, along with CD163 mRNA. Staining for mRNA could reliably detect CD163 expression while simultaneously detecting different macrophage populations using Abs targeting CD14, CD64, CD80, CD163, and CD209. This approach was found to be highly sensitive for increased mRNA expression when macrophages were polarized with IL-10 [M(IL-10)], with a strong signal over a broad range of IL-10 concentrations, and showed distinct kinetics of CD163 mRNA and protein induction upon IL-10 stimulation. Finally, this panel demonstrated clear changes in polarization markers in unstimulated monocytes from patients with SJIA and MAS, including upregulated CD163 mRNA and increased CD64 expression. This approach represents a robust and sensitive system for RNA flow cytometry, useful for studying CD163 expression as part of a multimarker panel for human monocytes and macrophages, with broad applicability to the pathogenesis of hyperinflammatory diseases.