Macrophage polarization in rheumatoid arthritis: signaling pathways, metabolic reprogramming, and crosstalk with synovial fibroblasts

Vitamin D enhances the effect of Soufeng sanjie formula in alleviating joint inflammation in CIA mice through VDR-NOTCH3/DLL4 signaling in macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA), defined as Bi Zheng syndrome in traditional Chinese medicine (TCM), is a chronic inflammatory and autoimmune disease that can cause substantial articular degradation and impairment. In RA, the polarization of macrophages to a proinflammatoy phenotype contributes to chronic inflammation and joint injury. Soufeng sanjie formula (SF), a traditional Chinese formula used to treat RA, consists of Scolopendra subspinipes mutilans L. Koch, Buthus martensii Karsch, Astragalus membranaceus (Fisch), and Glycine max (L.) Merr seed coats and plays a role in the regulation of macrophage polarization. Vitamin D (VD), a specific activator of the vitamin D receptor (VDR), promotes the differentiation of M2 macrophages and significantly enhances the therapeutic effects of TCM on arthritis. However, whether SF can be combined with VD to regulate macrophage polarization and alleviate RA remains unclear.

AIM OF THE STUDY

In this study, we examined the regulatory mechanisms and therapeutic effects of the combination of SF and VD on macrophages in RA.

MATERIALS AND METHODS

We used network pharmacology to analyze the targets and pathways of SF in RA. Clinical data were analyzed to confirm the expression of key targets. The RA immune landscape for cell-gene correlations was built using bioinformatics. A collagen-induced arthritis (CIA) model was established to evaluate the combined therapeutic effects of SF and VD on joint injury and inflammation. Quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting (WB), and immunofluorescence were used to assess the expression of key molecules in macrophages. Macrophage polarization was analyzed using flow cytometry.

RESULTS

SF acts on RA through multiple pathways, including hub genes, such as VDR, ABL1, DNMT1, and CXCR4. Immune infiltration analysis of RA showed that a reduction in the number of M2 macrophages significantly affected RA. Clinical data analysis and prognostic assessments corroborated the pivotal roles played by hub genes, such as VDR, ABL1, DNMT1, and CXCR4. Crucially, this study demonstrated a strong association between the key hub gene VDR and M2 macrophages. In vivo and in vitro models of RA showed that VD significantly improved the efficacy of SF against arthritis in CIA mice and stimulated macrophage polarization toward the M2 phenotype via modulation of the NOTCH3/DLL4 pathway. Furthermore, siRNA-mediated interference with the expression of VDR confirmed that the downregulation of VDR significantly activated the NOTCH3/DLL4 signaling pathway and blocked the regulation of SF combined with VD on the polarization of macrophages toward the M2 phenotype.

CONCLUSIONS

Our results demonstrate that the combination of SF and VD markedly improves the therapeutic effect of SF on RA via M2 macrophage differentiation through the VDR-NOTCH3/DLL4 signaling pathway. The VD-enhancing effect of SF in improving RA symptoms offers a new strategy and theoretical foundation for the clinical treatment of the condition.

Study of Folate-Modified Carboxymethyl Chitosan-Sinomenine-Curcumin Nanopolymer for Targeted Treatment of Rheumatoid Arthritis

Sinomenine hydrochloride (SH) has been clinically utilized for many years to treat rheumatoid arthritis (RA) in both oral and injectable forms. However, its low bioavailability, poor targeting, high dosage requirements, and side effects, present significant challenges. This study developed folic acid-carboxymethyl chitosan-modified sinomenine-curcumin nanopolymers (named SCNP) for the targeted treatment of RA, to reduce dosage and side effects. The design of SCNP employs folic acid (FA) as a targeting moiety, facilitating specific binding to the folate receptor (FR) on the surface of macrophages and enabling internalization into activated macrophages via endocytosis, thereby achieving targeted delivery to sites of inflammation. In a rat and cell model of RA, SCNP was found to decrease reactive oxygen species (ROS) and pro-inflammatory factors while increasing the anti-inflammatory factor IL-10 through the NF-κB/NLRP3 pathway. These findings indicate that SCNP has the potential to lower drug dosage, enhance therapeutic efficacy, and minimize side effects such as diarrhea and rash, thereby highlighting its promise as an inflammation-targeting nanopolymer.

Hyaluronic acid-modified PtPdCo-CQ nanocatalyst with triple enzyme-like activities regulates macrophage polarization and autophagy levels for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovial inflammation and imbalanced macrophage polarization. Pro-inflammatory M1 macrophages exacerbate joint damage through excessive production of reactive oxygen species (ROS), while anti-inflammatory M2 macrophages are prone to ferroptosis, limiting the long-term efficacy of existing nanozyme therapies. This study aimed to develop a novel nanocatalyst combining efficient ROS scavenging and M2 macrophage protection to synergistically regulate macrophage polarization and autophagy levels for sustained RA remission. We designed a hyaluronic acid-modified PtPdCo-CQ nanocatalyst (HPPCQ) with triple enzyme-like activities-superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). In vitro experiments demonstrated that HPPCQ activated the Nrf2/HO-1 antioxidant pathway by scavenging ROS, promoted M1-to-M2 phenotypic repolarization, and protected M2 macrophages from autophagy-dependent ferroptosis via controlled release of chloroquine (CQ). In a collagen-induced arthritis (CIA) mouse model, HPPCQ targeted inflamed joints, significantly reducing clinical scores, synovial hyperplasia, and pro-inflammatory cytokine levels (TNF-α, IL-1β). Histological analysis revealed markedly alleviated cartilage destruction and inflammatory infiltration in HPPCQ-treated mice. By integrating ROS scavenging, macrophage reprogramming, and ferroptosis inhibition, this work provides a novel therapeutic strategy with enhanced efficacy and durability for RA treatment.

Cationic liposomes encapsulating IL-2 selectively induce apoptosis and significantly reduce the secretion of cytokines on M1-murine polarized macrophages

Inflammatory diseases pose a global challenge due to the critical role of macrophages in their pathogenesis. This study evaluated the effects of cationic liposomes encapsulating IL-2 (LIP-IL-2) on murine peritoneal macrophages (MP) polarized towards M1 and M2 phenotypes. M1 MP (CD86+), which overexpressed IL-2Rα and CD14 receptors, underwent apoptosis following LIP-IL-2 treatment, whereas M2 MP (CD206+) were unaffected. Furthermore, LIP-IL-2 significantly reduced the secretion of pro-inflammatory cytokines, including IL-6, TNF-α, IFN-γ, and IL-12, exclusively in M1 macrophages. These findings suggest that LIP-IL-2 could serve as a promising therapeutic tool for chronic inflammatory diseases by selectively inducing apoptosis in pro-inflammatory M1 macrophages without affecting M2 ones, opening avenues for targeted therapies in diseases where chronic macrophage-mediated inflammation is a key factor.

Advances in nanodelivery systems based on apoptosis strategies for enhanced rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder primarily characterized by persistent synovial inflammation and progressive bone erosion. The pathogenesis of RA involves a complex cascade of cellular and molecular events, including sustained hyperactivation of macrophages, excessive recruitment and activation of neutrophils, pathological proliferation and invasion of fibroblast-like synoviocytes (FLS), and dysregulated differentiation and function of osteoclasts (OCs). The inflammatory factors secreted by these dysregulated cells significantly disrupt the joint microenvironment through multiple pathological mechanisms, primarily by promoting synovial inflammation, cartilage matrix degradation, osteoclast-mediated bone erosion, and pathological angiogenesis. Therapeutic strategies targeting the induction of apoptosis in these malignant cells have demonstrated considerable potential in preclinical studies, offering a promising approach to enhance treatment outcomes by simultaneously reducing inflammatory cytokine production and inhibiting pathogenic cell proliferation. However, conventional therapeutic drugs are limited in clinical applications because of their high toxicity and side effects. Inflammation induces morphological and functional changes in cells within the rheumatoid arthritis microenvironment (RAM), particularly the overexpression of specific receptors on cell membranes. This phenomenon has driven the development of ligand-modified targeted nanodelivery systems (NDSs), which can specifically target and induce apoptosis in specific cell types, thereby enhancing therapeutic efficacy. This paper comprehensively reviews the research progress of targeted NDSs based on apoptosis strategies for RA therapy, with a detailed discussion of their advantages in inducing apoptosis in various disease-associated cells. Furthermore, the potential of combining apoptosis of multiple cell types for RA treatment is explored. This review is expected to improve insights into the apoptosis of malignant cells to enhance RA therapy. STATEMENT OF SIGNIFICANCE: This review highlights recent advances in nanodelivery systems (NDSs) based on apoptotic strategies for enhanced rheumatoid arthritis (RA) therapy. Unlike conventional NDSs, these optimized systems specifically induce apoptosis in malignant cells within the RA microenvironment by integrating multiple therapeutic strategies. By summarizing the latest research, our work demonstrates the potential of these NDSs to suppress inflammatory responses and prevent bone destruction through targeted elimination of malignant cells, offering a novel direction for RA treatment. This review is significant as it provides a comprehensive overview for researchers and clinicians, facilitating the development of more effective therapeutic approaches for RA and other chronic inflammatory diseases.

Research advances in the treatment of arthritis from natural products (2014-present)

Arthritis, encompassing osteoarthritis (OA), rheumatoid arthritis (RA), and gouty arthritis (GA), is a prevalent inflammatory disease that significantly impacts quality of life. Natural products (NPs), derived from animals, plants, marine organisms, and microorganisms, have demonstrated beneficial effects in arthritis treatment both domestically and internationally. These natural compounds offer advantages in drug discovery due to their skeletal diversity, structural complexity, and multi-effect, multi-target, and low-toxicity properties compared to conventional small-molecule medicines. However, unclear mechanisms have hindered the development and clinical application of NPs. This review summarizes recent experimental studies from the past decade on natural medicine for arthritis treatment, emphasizing key NPs with therapeutic effects on OA, RA, and GA. It examines the effects and molecular mechanisms of NPs acting on different cells to treat arthritis. Furthermore, this review provides insights into the future prospects of NP research in this field, which is crucial for advancing NP-based arthritis treatments.

Biomarker identification for rheumatoid arthritis with inadequate response to DMARD and TNF therapies using multidimensional analyses

PURPOSE

Rheumatoid arthritis (RA) is an immune system disorder disease accompanied with severe joint damage. However, the molecular mechanism of RA with insensitive to medicine remains insufficient. Thus, this study aims to identify the biomarkers of RA patients with inadequate responses (IR) toward disease-modifying antirheumatic drug (DMARD) and antitumor necrosis factor (TNF) therapies, using multidimensional analyses.

METHODS

Gene expression data GSE45291 originating from clinics were downloaded from the Gene Expression Omnibus public database (GEO). Differentially expressed genes (DEGs) closely associated with DMARD&TNF-IR RA were identified using the Limma R package. Weighted gene co-expression network analysis (WGCNA) was carried out to identify critical genes. The CIBERSORT algorithm and single sample Gene Set Enrichment Analysis (ssGSEA) were employed for immune infiltration analysis and functional enrichment analysis, respectively. Lastly, mRNA expression levels of the identified hub genes in inflammatory conditions of collagen-induced arthritis (CIA) rats and lipopolysaccharide (LPS)-induced RAW264.7 cells were further observed using RT-qPCR.

RESULTS

In this work, a total of 17 genes were identified as hub genes. Of these, the expression levels of UHMK1, ELK4, APOC2, and SFT2D1 were significantly lowered in inflammatory conditions. GSEA indicated B cells with the immune-related genes play an essential role in the course of DMARD&TNF-IR RA. Notable differences in immune cell proportions (activated. Dendritic. cell, CD56 bright. Natural. killer. Cell, gamma. Delta. T. cell, MDSC, macrophage) were observed between normal and disease groups, suggesting immune involvement.

CONCLUSION

The findings of this study provide additional understanding of the detection of DMARD&TNF-IR RA.

Unlocking the Power of the Mediterranean Diet: Two in One-Dual Benefits for Rheumatic and Thyroid Autoimmune Diseases

In recent years, autoimmune diseases are becoming more and more prevalent worldwide, with this rapid rise being influenced by environmental factors linked to lifestyle changes in modern societies. In this context, the role of diet has been the topic of extensive research as evidence has mounted that particular dietary patterns may contribute to or modulate autoimmunity. The present review specifically focuses on the Mediterranean diet (MD) as a whole dietary pattern, and on its peculiar components, such as n-3 polyunsaturated fatty acids (PUFAs), polyphenols and fiber. We explored their potential benefits in a spectrum of both systemic and organ-specific autoimmune disorders, including rheumatic diseases (like rheumatic arthritis and systemic lupus erythematosus), and thyroid diseases (like Hashimoto's thyroiditis), since they often occur in the same individuals. Here, we offer a comprehensive review about the influence of dietary factors on these autoimmune diseases and potential translation into therapeutic interventions, as an adjuvant therapeutic approach to improve autoimmunity-related outcomes.

S-propargyl-cysteine attenuates temporomandibular joint osteoarthritis by regulating macrophage polarization via Inhibition of JAK/STAT signaling

BACKGROUND

Temporomandibular joint osteoarthritis (TMJ-OA) is a disease characterized by cartilage degradation and synovial inflammation, with limited effective treatment currently. Synovial macrophage polarization is pivotal in TMJ-OA progression, making it a promising therapeutic aspect. This study investigated the effects of S-propargyl-cysteine (SPRC), an endogenous H2S donor, on macrophage polarization and its therapeutic potential in alleviating TMJ-OA.

METHODS

A MIA-induced TMJ-OA rat model and LPS-stimulated RAW264.7 macrophages were employed to evaluate the effects of SPRC in vivo and in vitro. TMJ bone and cartilage were analyzed via micro-CT and histological methods, while macrophage polarization markers expression were assessed via RT-qPCR, western blot, and immunofluorescence. RNA sequencing was performed on macrophages, and the JAK2/STAT3 signaling pathway was validated using the JAK2-specific inhibitor AG490. The direct effects of SPRC on rat primary condylar chondrocytes were examined by evaluating ECM synthesis and degradation. Co-culture experiments further assessed macrophage-chondrocyte interactions.

RESULTS

SPRC significantly alleviated cartilage and bone damage in the TMJ-OA rat model, as demonstrated by improved bone volume and cartilage structure. SPRC reduced pro-inflammatory M1 macrophage infiltration and enhanced anti-inflammatory M2 macrophage polarization. SPRC effectively inhibited the JAK2/STAT3, leading to reduction of inflammatory markers, including TNF-α, IL-6, and iNOS. Co-culture experiments revealed that SPRC-treated macrophage-conditioned medium improved chondrocyte metabolic activity and restored ECM integrity.

CONCLUSIONS

SPRC-modulated macrophage polarization alleviates TMJ-OA via JAK/STAT downregulation, thereby reducing synovial inflammation and cartilage degradation. These findings position SPRC as a promising therapeutic candidate for TMJ-OA and provide insights into novel strategies targeting macrophage polarization and synovium-cartilage crosstalk.

Modulation of M1 and M2 macrophage polarization by metformin: Implications for inflammatory diseases and malignant tumors

Macrophages perform an essential role in the body's defense mechanisms and tissue homeostasis. These cells exhibit plasticity and are categorized into two phenotypes, including classically activated/M1 pro-inflammatory and alternatively activated/M2 anti-inflammatory phenotypes. Functional deviation in macrophage polarization occurs in different pathological conditions that need correction. In addition to antidiabetic impacts, metformin also possesses multiple biological activities, including immunomodulatory, anti-inflammatory, anti-tumorigenic, anti-aging, cardioprotective, hepatoprotective, and tissue-regenerative properties. Metformin can influence the polarization of macrophages toward M1 and M2 phenotypes. The ability of metformin to support M2 polarization and suppress M1 polarization could enhance its anti-inflammatory properties and potentiate its protective effects in conditions such as chronic inflammatory diseases, atherosclerosis, and obesity. However, in metformin-treated tumors, the proportion of M2 macrophages is decreased, while the frequency ratio of M1 macrophages is increased, indicating that metformin can modulate macrophage polarization from a pro-tumoral M2 state to an anti-tumoral M1 phenotype in malignancies. Metformin affects macrophage polarization through AMPK-dependent and independent pathways involving factors, such as NF-κB, mTOR, ATF, AKT/AS160, SIRT1, STAT3, HO-1, PGC-1α/PPAR-γ, and NLRP3 inflammasome. By modulating cellular metabolism and apoptosis, metformin can also influence macrophage polarization. This review provides comprehensive evidence regarding metformin's effects on macrophage polarization and the underlying mechanisms. The polarization-inducing capabilities of metformin may provide significant therapeutic applications in various inflammatory diseases and malignant tumors.

Resolution of inflammation during rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes synovial joint inflammation as well as bone destruction and erosion, typically characterized by joint pain, swelling, and stiffness, with complications and persistent pain after remission posing a significant health burden for RA patients. The etiology of RA has not yet been fully elucidated, but a large number of studies have shown that the initiation of inflammation in RA is closely related to T-cell activation, the production of a variety of pro-inflammatory cytokines, macrophage M1/M2 imbalance, homeostatic imbalance of the intestinal flora, fibroblast-like synoviocytes (FLSs) and synovial tissue macrophages (STMs) in the synovial lumen of joints that exhibit an aggressive phenotype. While the resolution of RA is less discussed, therefore, we provided a systematic review of the relevant remission mechanisms including blocking T cell activation, regulating macrophage polarization status, modulating the signaling pathway of FLSs, modulating the subpopulation of STMs, and inhibiting the relevant inflammatory factors, as well as the probable causes of persistent arthritis pain after the remission of RA and its pain management methods. Achieving resolution in RA is crucial for improving the quality of life and long-term prognosis of patients. Thus, understanding these mechanisms provide novel potential for further drug development and treatment of RA.

Lysyl Oxidase-Like 1 (LOXL1) Up-Regulation in Chondrocytes Promotes M1 Macrophage Activation in Osteoarthritis via NF-κB and STAT3 Signaling

Purpose

Osteoarthritis (OA) constitutes a widespread degenerative joint disease predominantly affecting the elderly, leading to disability. There is still a lack of biomarkers for OA, so it cannot be intervened in time.

Methods

OA biomarkers were identified from human cartilage datasets using LASSO and SVM-RFE, followed by ROC analysis. LOXL1 was prioritized for further research due to its high expression in OA cartilage and robust predictive performance. Anterior cruciate ligament transection (ACLT) surgery-induced OA rats were used to explore the correlation between LOXL1 and inflammatory factors and macrophages. Macrophage markers and cytokine secretion were detected from macrophages treated with LOXL1, or co-cultured with chondrocytes after LOXL1 siRNA silencing.

Results

Five hub biomarkers with OA-specific expression were identified. Elevated LOXL1 correlated with IL-6 and IL-8 in patients and increased M1 macrophages in OA rats. LOXL1-stimulated macrophages upregulated CD86 and inflammatory cytokines. Silencing LOXL1 in chondrocytes reduced CD86, inflammatory cytokines, and NF-κB p65 and p-STAT3 expression in co-cultured macrophages, mitigating MMP13 and chondrocyte apoptosis. STAT3 and NF-κB signal inhibition reduces p-STAT3, p-p65, CD86, IL-6 and IL-1β expression in LOXL1-stimulated macrophages.

Conclusion

This study underscores the pivotal role of LOXL1 in activating M1 macrophages through NF-κB and STAT3 signaling, thereby promoting pro-inflammatory cytokine secretion and contributing to OA pathogenesis. LOXL1 holds promise as a potential marker for early diagnosis of OA inflammation and as a novel therapeutic target.

Glycosylation Regulation by TMEM230 in Aging and Autoimmunity

Aging is often a choice between developing cancer or autoimmune disorders, often due in part to loss of self-tolerance or loss of immunological recognition of rogue-acting tumor cells. Self-tolerance and cell recognition by the immune system are processes very much dependent on the specific signatures of glycans and glycosylated factors present on the cell plasma membrane or in the stromal components of tissue. Glycosylated factors are generated in nearly innumerable variations in nature, allowing for the immensely diverse role of these factors in aging and flexibility necessary for cellular interactions in tissue functionality. In previous studies, we showed that differential expression of TMEM230, an endoplasmic reticulum (ER) protein was associated with specific signatures of enzymes regulating glycan synthesis and processing and glycosylation in rheumatoid arthritis synovial tissue using single-cell transcript sequencing. In this current study, we characterize the genes and pathways co-modulated in all cell types of the synovial tissue with the enzymes regulating glycan synthesis and processing, as well as glycosylation. Genes and biological and molecular pathways associated with hallmarks of aging were in mitochondria-dependent oxidative phosphorylation and reactive oxygen species synthesis, ER-dependent stress and unfolded protein response, DNA repair (UV response and P53 signaling pathways), and senescence, glycolysis and apoptosis regulation through PI3K-AKT-mTOR signaling have been shown to play important roles in aging or neurodegeneration (such as Parkinson's and Alzheimer's disease). We propose that the downregulation of TMEM230 and RNASET2 may represent a paradigm for the study of age-dependent autoimmune disorders due to their role in regulating glycosylation, unfolded protein response, and PI3K-AKT-mTOR signaling.

Senescent macrophages trigger a pro-inflammatory program and promote the progression of rheumatoid arthritis

This study explores the complex mechanisms between Rheumatoid Arthritis (RA) and cellular senescence, with a focus on the role of four key genes (MMP1, CCL7, CXCL1, HK3) identified through transcriptome analysis in the GEO database. These genes are closely related to IL-17 signalling and the pathogenesis of RA. In a macrophage senescence model induced by hydrogen peroxide (H2O2) and bleomycin (BLM), quantitative real-time PCR (qRT-PCR) and Western blot confirmed the significant upregulation of these genes and an increase in the secretion of the cytokine IL-17, which promotes an inflammatory environment for the polarization of macrophages to M1. When co-cultured with mouse synovial fibroblasts (MSF), MSF showed enhanced vitality and increased invasiveness, indicating a key role for these genes in the progression of RA. Additionally, HK3, less reported in RA, when its expression is knocking down, lactate secretion and lactylation modification at lysine 14 of histone H3 in macrophages were reduced, leading to a change in macrophage polarity. The study concludes that the altered polarity of senescent macrophages drives the proliferation and invasion of MSF, significantly promoting the development of RA and providing insights into the pathophysiology of RA.

Macrophage metabolic reprogramming: A trigger for cardiac damage in autoimmune diseases

Macrophage metabolic reprogramming has a central role in the progression of autoimmune and auto-inflammatory diseases. The heart is a major target organ in many autoimmune conditions and can sustain functional and structural impairments, potentially leading to irreversible cardiac damage. There is mounting clinical evidence pointing to a link between autoimmune disease and cardiac damage. However, this association remains poorly understood, and numerous patients do not receive appropriate preventive measures, which poses serious cardiovascular risks and significantly impacts their quality of life. This review discusses the relationship between macrophage metabolic reprogramming and cardiac damage in patients with autoimmune diseases and the role of adaptive immunity in macrophage reprogramming. It also provides an overview of the immunosuppressive therapies used at present. Exploiting the properties of macrophage reprogramming could lead to development of novel treatments for patients with autoimmune-related cardiac damage.

Asperosaponin VI suppresses ferroptosis in chondrocytes and ameliorates osteoarthritis by modulating the Nrf2/GPX4/HO-1 signaling pathway

Background

Asperosaponin VI (AVI) is a naturally occurring monosaccharide derived from Dipsacus asperoides renowned for its anti-inflammatory and bone-protective properties.

Objective

To elucidate the specific mechanism through which AVI affects chondrocytes in osteoarthritis (OA).

Methods

For the in vitro experiments, primary chondrocytes were to elucidate the molecular mechanisms underlying the action of AVI.For the in vivo experiments, rat OA models were established using a modified Hulth method. The severity of knee osteoarthritis was evaluated 8 weeks post-surgery. Micro-CT imaging, hematoxylin-eosin staining, and Safranin O-fast green staining were used to assess degeneration in rat knee joints. Immunohistochemistry techniques were conducted to measure the levels of collagen II, MMP13, Nrf2, GPX4, ACSL4, and HO-1 within cartilage tissues. ELISA assays were performed to measure those of TNF-α, IL -6, and PGE2 in serum samples.

Results

AVI alleviated chondrocyte apoptosis and extracellular matrix degradation in rat OA induced by IL-1β. It attenuated the levels of TNF-α, IL-6, and PGE2 while reducing those of Fe2+ and malondialdehyde (MDA). AVI upregulated the expression of Nrf2, HO-1, and GPX4 while downregulating that of ACSL4. Mechanistic studies revealed that ML385-induced inhibition of the Nrf2 signaling pathway reversed the increase in GPX4 and ACSL4 expression and increased Fe2+ and MDA levels; treatment with erastin, a ferroptosis inducer, produced comparable results. In vivo experiments demonstrated that AVI improved the bone volume/tissue volume and trabecular separation values in OA rats; reversed the Osteoarthritis Research Society International score; upregulated Nrf2, HO-1, and GPX4 expression; downregulated ACSL4 and MMP13 expression, and decreased the serum levels of TNF-α, IL-6, and PGE2.

Conclusion

Our findings suggest that AVI is a promising therapeutic agent for OA. It exerted its protective effect by regulating the Nrf2/GPX4/HO-1 signaling axis to inhibit cartilage cell ferroptosis and improve osteoarthritis.

The Roles of Forkhead Box O3a (FOXO3a) in Bone and Cartilage Diseases - A Narrative Review

Bone and cartilage diseases are significantly associated with musculoskeletal disability. However, no effective drugs are available to cure them. FOXO3a, a member of the FOXO family, has been implicated in cell proliferation, ROS detoxification, autophagy, and apoptosis. The biological functions of FOXO3a can be modulated by post-translational modifications (PTMs), such as phosphorylation and acetylation. Several signaling pathways, such as MAPK, NF-κB, PI3K/AKT, and AMPK/Sirt1 pathways, have been implicated in the development of bone and cartilage diseases by mediating the expression of FOXO3a. In particular, FOXO3a acts as a transcriptional factor in mediating the expression of various genes, such as MnSOD, CAT, BIM, BBC3, and CDK6. FOXO3a plays a critical role in the metabolism of bone and cartilage. In this article, we mainly discussed the biological functions of FOXO3a in bone and cartilage diseases, such as osteoporosis (OP), osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis (AS), and intervertebral disc degeneration (IDD). FOXO3a can promote osteogenic differentiation, induce osteoblast proliferation, inhibit osteoclast activity, suppress chondrocyte apoptosis, and reduce inflammatory responses. Collectively, up-regulation of FOXO3a expression shows beneficial effects, and FOXO3a has become a potential target for bone and cartilage diseases.

PFKFB3 decreases α-ketoglutarate production while partial PFKFB3 knockdown in macrophages ameliorates arthritis in tumor necrosis factor-transgenic mice

OBJECTIVE

Aberrant 6-phosphofructo-2kinase/fructose-2,6-bisphoshatase 3 (PFKFB3) expression is tightly correlated with multiple steps of tumorigenesis; however, the pathological significance of PFKFB3 in macrophages in patients with rheumatoid arthritis (RA) remains obscure. In this study, we examined whether PFKFB3 modulates macrophage activation and promotes RA development.

METHOD

Peripheral blood mononuclear cells (PBMCs) from patients with RA, THP-1 cells, and bone marrow-derived macrophages from conditional PFKFB3-knockout mice were used to investigate the mechanism underlying PFKFB3-induced macrophage regulation of RA.

RESULT

We demonstrated that patients with RA have higher PFKFB3 levels than healthy volunteers. PFKFB3 silencing suppressed M1 macrophage polarization and downregulated IL-1β, CD80, IFIT1, CCL8, and CXCL10 in macrophages of patients with RA. PFKFB3 overexpression markedly upregulated IRF5, HIF1α, IL-1β, CD80, IFI27, IFI44, IFIT1, IFIT3, CCL2, CCL8, CXCL10, CXCL11, and MMP13 in phorbol 12-myristate 13-acetate-induced THP-1 cells, although these changes were partially reversed by PFK15, an inhibitor of PFKFB3 enzyme activity. Co-immunoprecipitation assays revealed that PFKFB3 interacted with GLUD1 and decreased glutamate dehydrogenase (GDH) activity and α-ketoglutarate production. PFKFB3, TNFα, IL-6, IFNγ, CXCL9, CXCL10, CXCL11, MMP13, and MMP19 were downregulated in bone marrow-derived macrophages of conditional PFKFB3-knockout mice relative to those of wild-type mice. Partial PFKFB3 knockdown in macrophages ameliorated the clinical signs of arthritis and bone destruction, inhibited proinflammatory factor expression, and promoted GDH activity and α-ketoglutarate production in tumor necrosis factor-transgenic mice. Single-cell sequencing revealed that macrophages were the most abundant cells in the ankles of arthritic mice, and partial PFKFB3 knockdown promoted M2-like polarization and was correlated with TREM2, SPP1, APOE, and C1Q expression.

CONCLUSION

PFKFB3 is upregulated in macrophages in patients with RA. PFKFB3 aggravates arthritis by modulating macrophage activity, which may be related to decreased α-ketoglutarate production.

Spatial transcriptomics in autoimmune rheumatic disease: potential clinical applications and perspectives

Spatial transcriptomics is a cutting-edge technology that analyzes gene expression at the cellular level within tissues while integrating spatial location information. This concept, which combines high-plex RNA sequencing with spatial data, emerged in the early 2010s. Spatial transcriptomics has rapidly expanded with the development of technologies such as in situ hybridization, in situ sequencing, in situ spatial barcoding, and microdissection-based methods. Each technique offers advanced mapping resolution and precise spatial assessments at the single-cell level. Over the past decade, the use of spatial transcriptomics on clinical samples has enabled researchers to identify gene expressions in specific diseased foci, significantly enhancing our understanding of cellular interactions and disease processes. In the field of rheumatology, the complex and elusive pathophysiology of diseases such as rheumatoid arthritis, systemic lupus erythematosus, and Sjögren's syndrome remains a challenge for personalized treatment. Spatial transcriptomics provides insights into how different cell populations interact within disease foci, such as the synovial tissue, kidneys, and salivary glands. This review summarizes the development of spatial transcriptomics and current insights into the pathophysiology of autoimmune rheumatic diseases, focusing on immune cell distribution and cellular interactions within tissues. We also explore the potential of spatial transcriptomics from a clinical perspective and discuss the possibilities for translating this technology to the bedside.

Macrophage polarization in sepsis: Emerging role and clinical application prospect

Sepsis is a severe, potentially fatal condition defined by organ dysfunction due to excessive inflammation. Its complex pathogenesis and poor therapeutic outcomes pose significant challenges in treatment. Macrophages, with their high heterogeneity and plasticity, play crucial roles in both the innate and adaptive immune systems. They can polarize into M1-like macrophages, which promote pro-inflammatory responses, or M2-like macrophages, which mediate anti-inflammatory responses, positioning them as critical mediators in the immune response during sepsis.Macrophages are the main regulators of inflammatory responses, and their polarization is also regulated by inflammatory signaling pathways. This review highlights recent advances in the inflammatory signaling pathways involved in sepsis, mechanism of macrophage polarization mediated by inflammation-related signaling pathways in sepsis, and the role of signaling pathway mediated macrophage polarization in organ dysfunction involved in sepsis. We also explore the therapeutic potential of targeting macrophage polarization for immunotherapy, offering new perspectives on macrophage-targeted treatments for sepsis.

Interaction with IGF1 overrides ANXA2-mediated anti-inflammatory functions of IGFBP5 in vivo

Background

IGFBP5 is a differentially expressed gene (DEG) between M1 and M2 macrophages. This study explained why it causes opposite effects in different circumstances.

Methods

Gene expression profiles of various cell subsets were compared by mining a public database. THP-1 cells were treated by siRNAs, recombinant IGFBP5, lipopolysaccharide (LPS), picropodophyllin, IGF1 or the combinations. Clinical implication of IGFBP5 changes was investigated using rheumatoid arthritis (RA) and acute lung injury (ALI) models. IGFBP5-bound and differential proteins were identified by Liquid Chromatography Mass Spectrometry method.

Results

IGFBP5 situated in the center of a network constructed by the DEGs of M0 and M1/2 macrophages. Its expression negatively correlated to inflammation in vitro. When IGFBP5 was silenced, monocytes released more IL-1β and IL-6. NF-κB downstream proteins were overexpressed. IGFBP5 interacted with ANXA2 directly. In ANXA2-silenced cells, it showed no anti-inflammatory effect. Monocytes of adjuvant-induced arthritis rats and RA patients expressed less IGFBP5 than normal controls, but its blood levels increased significantly. Adipocytes secreted large amounts of IGFBP5. This secretion was reinforced by the above sera. IGFBP5 decreased in ALI mice's blood, while its supplement exacerbated inflammation. By binding to IGF1, IGFBP5 prevented its interaction with IGF1R. An IGF1R inhibitor picropodophyllin antagonized functions of IGF1/IGF1R too, but didn't reinforce the effects of IGFBP5.

Conclusion

IGFBP5 eases inflammation by interacting with ANXA2, an activator of NF-κB; as an antagonist of IGF1/IGF1R, IGFBP5 may disrupt immune homeostasis in vivo, due to impairment of the latter's anti-inflammatory functions; excessive IGFBP from adipocytes would be a pathogenic factor in certain diseases.

Anti-Inflammatory Effect of Extract from Fragaria ananassa Duch. Calyx via MAPK and NF-κB Signaling Pathway

Currently, Fragaria ananassa Duch. are discarded as by-products except for the fruit part, so we developed a natural material using the top (= calyx), one of the by-products, and prepared an extract using 70% ethanol to investigate its effects on anti-inflammatory mechanisms. The polyphenol content of 70% ethanol extracts from Fragaria ananassa Duch. calyx was measured to be 265.86 ± 0.85 mg TAE/100 g, respectively. The antioxidant activity was confirmed through the electron donating ability and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging ability measurements. When extracts from Fragaria ananassa Duch. calyx was treated to LPS-induced RAW 264.7 cells, it was confirmed that the production of inflammation-related factors, NO, PGE2, iNOS, COX-2, TNF-a, and IL-6, was inhibited. In addition, it was confirmed that extracts from Fragaria ananassa Duch. calyx affected the MAPK signaling pathway by reducing the protein expression of p-ERK, p-JNK, and p-p38, which are the upper signaling pathways. In addition, it was confirmed to reduce the protein expression of p-p65 and p-IκB, which are NF-κB signaling pathways. Therefore, this study suggests that extracts from Fragaria ananassa Duch. calyx affect the regulation of the production of major inflammation-related factors by inhibiting the MAPK and NF-κB signaling pathway. These results confirmed that extracts from Fragaria ananassa Duch. calyx have the potential to be developed as a new natural material with anti-inflammatory activity.

Study of the mechanism of fibroblast-like synoviocytes-derived exosomes inducing macrophages M1 polarization and CD8+T cells immune regulation ferroptosis and autophagy in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects the joints. The pathogenesis of RA is complex, involving membrane lipid antioxidant systems, oxidative stress, and lipid peroxidation. In this study, it was found that cysteine dioxygenase 1 (CDO1) is significantly upregulated in RA fibroblast-like synoviocytes (RA-FLS) and that exosomes derived from these RA-FLS deliver CDO1 to promote M1 polarization of macrophages, thus facilitating RA progression. In the immune microenvironment, CD8+T cells play a role in immune regulation by producing cytokines such as interferon gamma (IFNγ) in various diseases. The results of this study suggested that in RA-FLS, CD8+T cells deliver IFNγ, which not only inhibits the viability of RA-FLS but also affects glutathione (GSH) through CDO1, regulating the GPX4 antioxidant signaling pathway to promote ferroptosis and autophagy in cells. It was also discovered that IFNγ enhances the expression of TRI69, ubiquitinates and degrades FSP1, thereby forming a cooperative regulation process of GPX4 and FSP1 in ferroptosis. These findings provide a new direction for the treatment of RA.

FOXA2 inhibits the TLR4/NF-κB signaling pathway and alleviates inflammatory activation of macrophages in rheumatoid arthritis by repressing LY96 transcription

BACKGROUND

Rheumatoid arthritis (RA) remains a devastating autoimmune disease characterized by joint damage, inflammation, and disability. This study investigates the function of lymphocyte antigen 96 (LY96) in the inflammatory response in RA and explores its regulatory mechanism.

METHODS

A mouse model of RA was developed using type II collagen, and the LY96 expression in the ankle joint tissue was determined. Upstream regulators targeting LY96 were investigated using bioinformatics, followed by chromatin immunoprecipitation and luciferase reporter assays for validation. Gain- or loss-of-functions of LY96 and forkhead box A2 (FOXA2) were performed to analyze their roles in arthritis score, pathological changes, and inflammatory responses in mice. The effects of FOXA2 and LY96 on pro-inflammatory activation of macrophages were additionally investigated in vitro using a mouse RAW264.7 macrophage model with lipopolysaccharide treatment.

RESULTS

LY96 mRNA and protein (MD-2) levels were increased in the RA mice. Knockdown of LY96 alleviated arthritis severity, joint deformities, inflammation, and cartilage destruction in mice. In vitro, the LY96 knockdown reduced the pro-inflammatory activation of RAW264.7 macrophages by inhibiting the TLR4/NF-κB inflammatory signaling transduction. FOXA2 was identified as a transcriptional repressor of LP96 poorly expressed in RA. Overexpression of FOXA2 similarly alleviated inflammation and reduced M1-type macrophages in vivo and in vitro. However, these changes were reversed by the additional LY96 upregulation.

CONCLUSION

This study suggests that FOXA2 represses LY96 transcription to inhibit the TLR4/NF-κB signaling transduction, thus reducing pro-inflammatory activation of macrophages in the context of RA.

Visnagin alleviates rheumatoid arthritis via its potential inhibitory impact on malate dehydrogenase enzyme: in silico, in vitro, and in vivo studies

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder. The present study aimed to evaluate the in silico, in vitro, and in vivo inhibitory effect of visnagin on malate dehydrogenase activity and elucidate its inflammatory efficacy when combined with methotrexate in the RA rat model. The molecular docking, ADMET simulations, MDH activity, expression, and X-ray imaging were detected. Moreover, CRP, RF, (anti-CCP) antibody, (TNF-α), (IL-6), (IL-17), and (IL-10) were evaluated. The expression levels of MMP3 and FOXP3 genes and CD4, CD25, and CD127 protein levels were assessed. Histological assessment of ankle joints was evaluated. The results revealed that visnagin showed reversible competitive inhibition on MDH with inhibitory constant (Ki) equal to 141 mM with theoretical IC50 equal to 1202.7 mM, LD50 equal to 155.39 mg/kg, and LD25 equal to 77.69 mg/kg. In vivo studies indicated that visnagin exhibited anti-inflammatory effects through decreasing MDH1 activity and expression and induced proliferation of anti-inflammatory CD4+CD25+FOXP3 regulatory T cells with increasing the anti-inflammatory cytokine IL-10 levels. Moreover, visnagin reduced the levels of inflammatory cytokines and the immuno-markers. Our findings elucidate that visnagin exhibits an anti-inflammatory impact against RA through its ability to inhibit the MDH1 enzyme, improve methotrexate efficacy, and reduce oxidative stress.

Qing-Luo-Yin Eased Adjuvant-Induced Arthritis by Inhibiting SIRT1-Controlled Visfatin Production in White Adipose Tissues

Background

Nicotinamide adenine dinucleotide (NAD)-dependent deacetylase SIRT1 regulates both metabolism and immune functions. This study investigated if SIRT1 inhibitory property of herbal formula Qing-Luo-Yin (QLY) contributed to its anti-rheumatic effects.

Methods

Adjuvant-induced arthritis (AIA) rats were treated by QLY and nicotinamide mononucleotide (NMN, a biosynthesis precursor of NAD) for 38 days. After sacrifice, blood, paws, liver and white adipose tissues (WAT) were collected. Pre-adipocytes were cultured by the rats' serum. The medium was used for monocytes culture. Some pre-adipocytes were treated by QLY-derived SIRT1 inhibitors. SIRT1 was silenced or overexpressed beforehand. The samples were subjected to kits-based quantification, polymerase-chain reaction, western-blot, immunofluorescence, and histology experiments.

Results

AIA rats experienced significant fat loss in liver and WAT. Expression of many SIRT1-related signals like PPARγ, PGC-1α, HSL, ATGL and CPT-1A were altered. QLY attenuated all these abnormalities and joint injuries. By pan-acetylation up-regulation, visfatin was obviously reduced in QLY-treated AIA rats' blood (from 191.8 to 127.0 pg/mL). NMN sustained SIRT1 activation by replenishing NAD, and weakened these effects. QLY-containing serum and the related compounds showed similar impacts on pre-adipocytes, resembling the changes in QLY-treated AIA rats' WAT. These treatments suppressed AIA serum-induced visfatin secretion (from 49.3 to 36.1 and 30.7 pg/mL). This effect was impaired by SIRT1 overexpression. The medium from the compounds-treated pre-adipocytes impaired NF-κB activation in AIA serum-cultured monocytes.

Conclusion

Besides fat depletion, SIRT1 up-regulation in rheumatic subjects' WAT promotes visfatin production, and exacerbates inflammation. SIRT1 inhibition in WAT is an anti-rheumatic way of QLY independent of immune regulation.

Advancements in rheumatoid arthritis therapy: a journey from conventional therapy to precision medicine via nanoparticles targeting immune cells

Rheumatoid arthritis (RA) is a progressive autoimmune disease that mainly affects the inner lining of the synovial joints and leads to chronic inflammation. While RA is not known as lethal, recent research indicates that it may be a silent killer because of its strong association with an increased risk of chronic lung and heart diseases. Patients develop these systemic consequences due to the regular uptake of heavy drugs such as disease-modifying antirheumatic medications (DMARDs), glucocorticoids (GCs), nonsteroidal anti-inflammatory medicines (NSAIDs), etc. Nevertheless, a number of these medications have off-target effects, which might cause adverse toxicity, and have started to become resistant in patients as well. Therefore, alternative and promising therapeutic techniques must be explored and adopted, such as post-translational modification inhibitors (like protein arginine deiminase inhibitors), RNA interference by siRNA, epigenetic drugs, peptide therapy, etc., specifically in macrophages, neutrophils, Treg cells and dendritic cells (DCs). As the target cells are specific, ensuring targeted delivery is also equally important, which can be achieved with the advent of nanotechnology. Furthermore, these nanocarriers have fewer off-site side effects, enable drug combinations, and allow for lower drug dosages. Among the nanoparticles that can be used for targeting, there are both inorganic and organic nanomaterials such as solid-lipid nanoparticles, liposomes, hydrogels, dendrimers, and biomimetics that have been discussed. This review highlights contemporary therapy options targeting macrophages, neutrophils, Treg cells, and DCs and explores the application of diverse nanotechnological techniques to enhance precision RA therapies.

99mTc-labeled, tofacitinib citrate encapsulated chitosan microspheres loaded in situ gel formulations for intra-articular treatment of rheumatoid arthritis

Inflammatory diseases including rheumatoid arthritis are major health problems. Although different techniques and drugs are clinically available for the diagnosis and therapy of the disease, novel approaches regarding radiolabeled drug delivery systems are researched. Hence, in the present study, it was aimed to design, prepare, and characterize 99mTc-radiolabeled and tofacitinib citrate-encapsulated microsphere loaded poloxamer in situ gel formulations for the intra-articular treatment. Among nine different microsphere formulations, MS/TOFA-9 was chosen as the most proper one due to particle size, high encapsulation efficiency, and in vitro drug release behavior. Poloxamer 338 at a concentration of 15% was used to prepare in situ gel formulations. For intra-articular administration, microspheres were dispersed in an in situ gel containing 15% Poloxamer 338 and characterized in terms of gelation temperature, viscosity, rheological, mechanical, and spreadability properties. After the determination of the safe dose for MS/TOFA-9 and PLX-MS/TOFA-9 as 40 µL/mL in the cell culture study performed on healthy cells, the high anti-inflammatory effects were due to significant cellular inhibition of fibroblasts. In the radiolabeling studies with 99mTc, the optimum radiolabeling condition was determined as 200 ppm SnCl2 and 0.5 mg ascorbic acid, and both 99mTc-MS/TOFA-9 and 99mTc-PLX-MS/TOFA-9 exhibited high cellular binding capacity. In conclusion, although further in vivo experiments are required, PLX-MS/TOFA-9 was found to be a promising agent for intra-articular injection in rheumatoid arthritis.

JAK Inhibitors in Rheumatoid Arthritis: Immunomodulatory Properties and Clinical Efficacy

Rheumatoid arthritis (RA) is a highly prevalent autoimmune disorder. The pathogenesis of the disease is complex and involves various cellular populations, including fibroblast-like synoviocytes, macrophages, and T cells, among others. Identification of signalling pathways and molecules that actively contribute to the development of the disease is crucial to understanding the mechanisms involved in the chronic inflammatory environment present in affected joints. Recent studies have demonstrated that the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway regulates the behaviour of immune cells and contributes to the progression of RA. Several JAK inhibitors, such as tofacitinib, baricitinib, upadacitinib, and filgocitinib, have been developed, and their efficacy and safety in patients with RA have been comprehensively investigated in a number of clinical trials. Consequently, JAK inhibitors have been approved and registered as a treatment for patients with RA. In this review, we discuss the involvement of JAK/STAT signalling in the pathogenesis of RA and summarise the potential beneficial effects of JAK inhibitors in cells implicated in the pathogenesis of the disease. Moreover, we present the most important phase 3 clinical trials that evaluated the use of these agents in patients.